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Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_15 | Pages 68 - 68
7 Nov 2023
Hohmann E Paschos N Keough N Molepo M Oberholster A Erbulut D Tetsworth K Glat V Gueorguiev B
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The purpose of this study was to develop a quality appraisal tool for the assessment of laboratory basic science biomechanical studies.

Materials andScore development comprised of the following phases: item identification/development, item reduction, content/face/criterion validity, weighting, test-retest reliability and internal consistency. For item identification/development, the panel was asked to independently list criteria and factors they considered important for cadaver study and generate items that should be used to appraise cadaver study quality. For content validity, the content validity ratio (CVR) was calculated. The minimum accepted content validity index (CVI) was set to 0.85. For weighting, equal weight for each item was 6.7% [15 items]. Based on these figures the panel was asked to either upscale or downscale the weight for each item ensuring that the final sum for all items was 100%. Face validity was assessed by each panel member using a Likert scale from 1–7. Strong face validity was defined as a mean score of >5. Test-retest reliability was assessed using 10 randomly selected studies. Criterion validity was assessed using the QUACS scale as standard. Internal consistency was assessed using Cronbach's alpha.

Five items reached a CVI of 1 and 10 items a CVI of 0.875. For weighting five items reached a final weight of 10% and ten items 5%. The mean score for face validity was 5.6. Test-retest reliability ranged from 0.78–1.00 with 9 items reaching a perfect score. Criterion validity was 0.76 and considered to be strong. Cronbach's alpha was calculated to be 0.71 indicating acceptable internal consistency.

The new proposed quality score for basic science studies consists of 15 items and has been shown to be reliable, valid and of acceptable internal consistency. It is suggested that this score should be utilised when assessing basic science studies.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_15 | Pages 89 - 89
7 Nov 2023
Greenwood K Molepo M Mogale N Keough N Hohmann E
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The posterior compartments of the knee are currently accessed arthroscopically through anterior, posteromedial or posterolateral portals. A direct posterior portal to access the posterior compartments has been overlooked due to a perceived high-risk of injury to the popliteal neurovascular structures. Therefore, this study aimed to investigate the safety and accessibility of a direct posterior portal into the knee.

This cross-sectional study comprised a sample of 95 formalin-embalmed cadaveric knees and 9 fresh-frozen knees. Cannulas were inserted into the knees, 16mm from the vertical plane between the medial epicondyle of the femur and medial condyle of the tibia and 8 and 14mm (females and males respectively) from the vertical plane connecting the lateral femoral epicondyle and lateral tibial condyle. Landmarks were identified in full extension and cannula insertion was completed with the formalin-embalmed knees in full extension and the fresh-frozen in 90-degree flexion. Posterior aspects of the knees were dissected from superficial to deep, to assess potential damage caused by cannula insertion. Incidence of neurovascular damage was 9.6% (n=10); 0.96% medial cannula and 8.7% lateral cannula. The medial cannula damaged one small saphenous vein (SSV) in a male specimen. The lateral cannula damaged one SSV, 7 common fibular nerves (CFN) and both CFN and lateral cutaneous sural nerve in one specimen. All incidences of damage occurred in formalin-embalmed knees. The posterior horns of the menisci were accessible in all specimens.

A medial-lying direct posterior portal into the knee is safe in 99% of occurrences. The lateral-lying direct posterior portal is of high risk to the CFN.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_15 | Pages 88 - 88
7 Nov 2023
Greenwood K Molepo M Mogale N Keough N Hohmann E
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Knee arthroscopy is typically approached from the anterior, posteromedial and posterolateral portals. Access to the posterior compartments through these portals can cause iatrogenic cartilage damage and create difficulties in viewing the structures of the posterior compartments. The purpose of this study was to assess the feasibility of needle arthroscopy using direct posterior portals as both working and visualising portals.

For workability, the needle scope was inserted advanced from anterior between the cruciate ligament bundle and the lateral wall of the medial femoral condyle until the posterior compartments were visualised. For visualisation, direct postero-lateral and -medial portals were established. The technique was performed in 9 knees by two experienced researchers.

Workability and instrumentation of the posteromedial compartment and meniscus was achieved in 56%. The posterior horns could not be visualised in four specimens as the straight lens could not provide a more medial field of view. Visualisation from the direct medial posterior portal allowed a clear view of the medial meniscus, femoral condyle and posterior cruciate ligament in all specimens. Workability and instrumentation of the posterolateral compartment was not possible with the needle scope.

Direct posterior approaches for the posteromedial compartment access are challenging with the current needle scope options and could only be achieved in over 50%. The postero-lateral compartment was not accessible. An angled lens or a flexible Needle scope would be better suited for developing this technique further.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_15 | Pages 21 - 21
7 Nov 2023
Molepo M Hohmann E Oduoye S Myburgh J van Zyl R Keough N
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This study aimed to describe the morphology of the coracoid process and determine the frequency of commonly observed patterns. The second purpose was to determine the location of inferior tunnel exit with superior based tunnel drilling and the superior tunnel exit with inferior based tunnel drilling.

A sample of 100 dry scapulae for the morphology aspect and 52 cadaveric embalmed shoulders for tunnel drilling were used. The coracoid process was described qualitatively and categorized into 6 different shapes. A transcoracoid tunnel was drilled at the centre of the base. Twenty-six shoulders were used for the superior-inferior tunnel drilling approach and 26 for the inferior-superior tunnel drilling approach. The distances to the margins of the coracoid process, from both the entry and exit points of the tunnel, were measured.

Eight coracoid processes were of convex shape, 31 of hooked shape, 18 of irregular shape, 18 of narrow shape, 25 of straight shape, and 13 of wide shape. The mean difference for the distances between superior entry and inferior exit from the apex was Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation 3.65+3.51mm (p=0.002); 1.57+2.27mm for the lateral border (p=0.40) and 5.53+3.45mm for the medial border (p=0.001). The mean difference for the distances between inferior entry and superior exit from the apex was 16.95+3.11mm (p=0.0001); 6.51+3.2mm for the lateral border (p=0.40) and 1.03+2.32 mm for the medial border (p=0.045).

The most common coracoid process shape observed was a hooked pattern. Both superior to inferior and inferior to superior tunnel drilling directed the tunnel from a more anterior and medial entry to a posterior-lateral exit. Superior to inferior drilling resulted in a more posteriorly angled tunnel. With inferior to superior tunnel drilling cortical breaks were observed at the inferior and medial margin of the tunnel.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_29 | Pages 29 - 29
1 Aug 2013
Hohmann E Coyle C Bryant A
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Introduction:

Gait analysis is an important tool to measure function following total knee replacement. It is currently unknown whether there is a correlation between subjective and objective outcome. The purpose of this study was to analyse relationships between subjective outcome scores and kinematic and kinetic data.

Methods:

25 consecutive patients (15 males, 10 females) were selected (mean age 68 years, BMI 31.8). All subjects were tested a minimum of 24 months following total knee replacement. SF12, Oxford knee score, knee society and KOOS scores were collected. Muscle strength was assessed using a Biodex dynamometer and symmetry indices were analysed. A timed up and go test and KT2000 measurements were performed.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_29 | Pages 60 - 60
1 Aug 2013
Hohmann E Bryant A Tetsworth K
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Purpose:

Imageless navigation has improved the accuracy of acetabular cup placement but relies on manual identification of pelvic anatomy. Thick soft tissues in obese patients could obscure these landmarks and result in large variances of cup placement. The purpose of this study was to investigate the relationship between BMI, soft tissue thickness, navigated cup and final post-operative cup position.

Methods:

Thirty patients with an average age of 66.5 years underwent primary navigated THA. Final intra-operative cup position was recorded. Soft tissue thickness and final post-operative cup alignment were measured on a multi-slice pelvis CT scan.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_29 | Pages 63 - 63
1 Aug 2013
Hohmann E Bryant A Tetsworth K
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Purpose:

Correct placement of the acetabular cup is a crucial step in hip replacement to achieve a satisfactory result and remains a challenge with free hand techniques. Imageless navigation may provide a viable alternative to freehand technique and improve placement significantly. The purpose of this project was to assess and validate intra-operative placement values as displayed by an imageless navigation system to postoperative measurement of cup position using high resolution CT scans.

Methods:

Thirty-two subjects who underwent primary hip joint arthroplasty using imageless navigation were included. The average age was 66.5 years (range 32–87). 23 non-cemented and 9 cemented acetabular cups were implanted. The desired position for the cup was 45 degrees of inversion and 15 degrees of anteversion. A pelvic CT scan using a multi-slice CT was used to assess the position of the cup radiographically.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_29 | Pages 6 - 6
1 Aug 2013
Hohmann E Bryant A Tetsworth K
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Background:

The aim of this study was to investigate the outcome after ACL reconstruction between a group of patients receiving a standardized supervised physiotherapy guided rehabilitation program and a group of patients who followed an un-supervised, home-based rehabilitation program.

Methods:

40 patients with isolated anterior cruciate ligament injuries were allocated to either a supervised physiotherapy intervention group or home-based exercise group. Patients were investigated by an independent examiner pre-operative, 3, 6, 9 and 12 months post-surgery using the following outcome measures: Lysholm Score and Tegner Activity Scale, functional hopping tests, isometric and isokinetic strength assessments.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_29 | Pages 4 - 4
1 Aug 2013
Hohmann E Bryant A Reaburn P Tetsworth K
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Purpose:

A higher posterior tibial slope can potentially result in kinetic and kinematic changes of the knee. These changes may influence knee functionality in ACL-deficient and ACL-reconstructed subjects. The purpose of this study was to investigate the relationship between knee functionality and posterior tibial slope in ACL-deficient and ACL-reconstructed subjects.

Methods:

Subjects with isolated ACL injuries and subjects who underwent ACL-reconstruction with bone-patella-bone-tendon (BPTP) between 18 and 24 months post surgery were included in the study. Posterior tibial slope was measured on a lateral radiograph using the posterior tibial cortex as a reference. The Cincinnati scoring system was used to assess knee functionality.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_29 | Pages 54 - 54
1 Aug 2013
Hohmann E Bryant A Tetsworth K
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Purpose:

Malpositioning of the acetabular cup component in total hip arthroplasty can result in increased wear, early nonseptic loosening and is the most common cause of dislocation. Previous research has defined a safe zone with an inclination of 40±10 degrees and anteversion of 15±10 degrees. The purpose of this study was to compare cup placement using imageless navigation to a matched control group using CT based measurements.

Methods:

30 patients receiving a primary hip replacement were included. Alignment of the implant is based on the acquisition of landmarks (ASIS and pubic tubercle) and placement of tracking pins into the ASIS. The target position for all patients was 45 degrees of inclination and 15 degrees of anteversion. A multi-slice CT scan was used to assess cup position.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIII | Pages 233 - 233
1 May 2012
Hohmann E Tay M Tetsworth K Bryant A
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Given their role in reducing anterior tibial translation, the recruitment patterns and viscoelastic properties of the hamstring muscles have been implicated as neuromuscular factors contributing to the ACL gender bias. Nevertheless, it is uncertain whether patterns of aberration displayed by the female neuromuscular system significantly alters the antagonist moments generated by the hamstrings during maximal effort knee extension. The purpose of the current study was to examine the effect of gender on hamstring antagonist moments in order to explain the higher ACL injury rates in females.

Eleven females (age 30.6 ± 10.1 years, mass 62.1± 6.9 kg, height 165.9 ± 4.6) and 11 males (age 29.0 ± 8.2 years, mass 78.6± 14.4 kg, height 178.5± 6.2) were recruited as subjects. Surface electrodes were placed over the semitendinosus (ST) and biceps femoris (BF) muscles of the dominant and non-dominant limbs. Each subject performed two sets of five maximal extension and flexion repetitions at 180-1. EMG, isokinetic torque and knee displacement data were sampled at 1000Hz using an AMLAB data acquisition system.

Average hamstring antagonist torque data across the range of knee flexion for female subjects was significantly higher (%Diff=24%) than for the male control subject. Statistical analyses revealed a significant main effect of gender (F = 4.802; p = 0.036).

Given that females possess a more compliant ACL and hamstring musculature, compared with their male counterparts, an augmented hamstring antagonist may represent a compensatory neuromuscular strategy to increase knee stiffness to control tibial translation and ACL strain. The results of this project suggest that it is unlikely that gender-related differences in hamstring antagonist torque is one of the predisposing factors contributing to the higher ACL injury rates in females.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIII | Pages 234 - 234
1 May 2012
Hohmann E Tay M Tetsworth K Bryant A
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Anthropometric anatomical factors may influence mechanical and functional stability of joints. An increased posterior tibial slope places the anterior cruciate ligament at a theroretical biomechanical disadvantage. An increased posterior tibial slope can potentially alter forces during landing tasks by either increasing anterior tibial translation and/or ACL loading. The purpose of this study is to investigate the relationship between posterior tibial slope and anterior cruciate ligament injuries. It is hypothesised that subjects with an ACL injury have an increased posterior tibial slope compared to a normal population.

Posterior tibial slope in 211 patients (154 male, 57 female), aged 15–49, who underwent anterior cruciate ligament reconstruction was measured using the posterior tibial cortex as reference. A matched control group was used for comparison.

The average posterior tibial slope in the ACLR population was 6.1 degrees, whilst the control group had average values of 5.4 degrees. This finding nearly reached statistical significance (p=0.057). In the male population, average values were 5.5 degrees in the ACLR group and 5.9 in the control group. This was not significant (p=0.21). However, there was a significant difference (p=0.04) in the female group. ACLR females had higher values 6.5 degrees whereas the control group had average values of 5.2 degrees.

Increased posterior tibial slope decreases the inclination of the ACL and potentially decreases vector force during dynamic tasks. We could not confirm the results of previous studies demonstrating an increased degree of posterior tibial slope in ACL injured patients. However, we demonstrated a significant difference in tibial slope in females. Based on our results, an increased posterior tibial slope is not a risk factor in males but possibly contributes to ACL injuries in females. Increased posterior tibial slope may be one of the reasons why females have a higher incidence of ACL injuries.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIII | Pages 180 - 180
1 May 2012
Hohmann E Tay M Tetsworth K Bryant A
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Previous research has shown that tunnel placement is critical in ACL reconstruction. The ultimate position of both the femoral and tibial tunnel determines knee kinematics and overall function of the knee post surgery. As with all techniques there is a definite learning curve for the arthroscopic technique. However, the effect of the learning curve on tunnel placement has been studied sparsely. The purpose of this project therefore is to investigate the effect of the learning curve on tunnel placement.

Postoperative radiographs of the first 200 anterior cruciate reconstructions with bone-tendon-bone patella tendon of a single orthopaedic surgeon performed during the first four years of independent practice were analysed for tunnel placement. Radiographs were digitalised and imported into a CAD program.

Tunnel placement both femoral and tibial antero-posterior and sagittal was assessed using Sommer's criteria. A rating scale was developed to assess overall placement. A total of 100 points indicated perfect placement. A maximum of 30 points each were allocated for sagittal femoral and tibial placement and a maximum of 20 points each were allocated for coronal placement.

Tunnel placement scores improved from 66 for the first 25 procedures to 87 for the last 25 procedures. Sagittal femoral placement (zone 1–4 with zone 1 being the preferred zone of placement) improved from an average of 1.44 to 1.08. Sagittal tibial placement (45% from anterior border of tibia) did not change significantly and remained between 42.82 t0 44.76%. Coronal femoral placement (between 10:00–11:00 o'clock for the right knee and 1:00–2:00 for the left knee) ranged from 10.45–11.15 and 12:45-1:15 o'clock respectively. This finding may be related to the transtibial tibial technique used to place the femoral tunnel. Coronal tibial placement (45% from medial tibial border) ranged from 45-46.58%.

Correct placement of the femoral and tibial bone tunnels is important for a successful reconstruction of the anterior cruciate ligament (ACL). This study demonstrated a definitive learning curve and steady improvement of tunnel placement. Whilst there was no significant improvement in sagittal placement, overall placement improved significantly.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIII | Pages 232 - 232
1 May 2012
Hohmann E Tetsworth K Tay M Bryant A
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A higher posterior tibial slope can potentially result in kinetic and kinematic changes of the knee. These changes may influence knee functionality in ACL-deficient and ACL-reconstructed subjects. The purpose of this study is to investigate the relationship between knee functionality and posterior tibial slope in ACL-deficient and ACL-reconstructed subjects.

Subjects with isolated ACL injuries and subjects who underwent ACL- reconstruction with BPTP between 18 and 24 months post surgery were included in the study. Posterior tibial slope was measured on a lateral radiograph using the posterior tibial cortex as a reference. The Cincinnati scoring system was used to assess knee functionality.

Frty-four ACL-deficient patients with a mean age of 26.6 years, and 44 ACL-reconstructed patients with a mean age of 27.2 (25–49) years were included. The posterior tibial slope in the ACL-deficient group averaged 6.10±3.57 degrees (range 0–17 degrees) and 7.20±4.49 degrees (range 0–17) in the ACL-reconstructed group. The mean Cincinnati score in the ACL-deficient subject was 62.0±14.5 and 89.3±9.5 in the ACL-reconstructed subject.

There was a moderate but non-significant correlation (r=0.47) between knee functionality and slope in the ACL-deficient subject. By dividing posterior tibial slope into intervals, a strong significant correlation (r=0.91, p=0.01) was observed between knee functionality and slope. There was a weak but non-significant correlation (r=0.24) between knee functionality and slope in the ACL-reconstructed patient. Dividing posterior tibial slope into intervals (0-4, 5-9, >10) a strong and significant correlation (r=0.96, p=0.0001) was observed between knee functionality and slope.

The results of this study suggest that subjects with a higher posterior tibial slope have higher knee functionality. This is in contrast to previous research.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIII | Pages 230 - 230
1 May 2012
Hohmann E Bryant A Clarke R Bennell K Payne C Murphy A
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Estrogen fluctuations have been implicated in the soft tissue injury gender-bias due to the hormones effect on the viscoelastic properties. The isolated effect of estrogen on the mechanical behaviour of human tendon is unknown. The purpose of this study was to elucidate the effect of circulating levels of estrogen on the strain properties of the human Achilles tendon.

Twenty females (18–35 years) who were using the pill together with 20 matched, non-pill users, participated in this study. Non-pill users were tested at the time of lowest (menstruation) and highest (ovulation) estrogen whilst pill users, who exhibited constant and attenuated estrogen levels, were tested at menstruation and two weeks later. At each test session, maximal isometric plantarflexion efforts were performed on a calf-raise apparatus whilst synchronous real-time ultrasonography of the triceps surae aponeurosis was recorded. Connective tissue length (Lo) of the triceps surae complex was measured and tendon strain was calculated by dividing aponeurosis displacement during plantarflexion by Lo.

Repeated measures ANOVA revealed a significant (p < 0.05) main effect of subject group with significantly higher Achilles strain rates (16.1%) in the non-pill users compared to the pill users. Augmented Achilles tendon strain was associated with higher average estrogen levels in non-pill users.

Those results suggest that higher estrogen levels diminish the joint stabilising capacity of the triceps surae musculotendinous unit and may alter the energy storage capacity of the Achilles tendon during stretch-shorten cycle activities. This may result in a higher incidence of injuries during periods of high estrogen concentration.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIII | Pages 235 - 235
1 May 2012
Hohmann E Tay M Tetsworth K Bryant A
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A number of validated knee outcome rating scales are used to assess knee function in the ACL-deficient and ACL-reconstructed knee. These scores use a numeric system to rate findings such as pain, swelling, subjective assessment of function and level of activity.

However, it is unknown whether there is a correlation between the outcome rating scales and whether they can be used interchangeably. The aim of this study was to investigate the correlation between the four commonly used outcome rating scales (Lysholm, IKDC, Cincinnati and Tegner).

Inclusion criteria included physically active patients between the age of 18 and 35 years with isolated ACL injuries. A power calculation for sample size was performed. Selecting an alpha level of 0.05 and power value of 0.8, 24 ACL- deficient and 24 ACL-reconstructed subjects were needed to achieve adequate statistical power. Statistical analysis included the calculation of means and standard deviations for the dependant variables. Pearson's product moment correlation coefficients were used to establish the strength of the relationships.

Forty-four ACL-deficient and 24 ACL reconstructed subjects (mean age 27.0, range 16–49), with a minimum of 12 months post surgery, completed the tests. Pre-operatively, strong significant correlations (r=0.53-0.74, p=0.0001-0.001) between IKDC and the other scoring systems (Cinncinati, Lysholm and Tegner) were observed. The Lysholm score was significantly correlated to IKDC (r=0.74, p=0.0001) and Cinncinati (r=0.60, p=0.001) scores. Non-significant moderate correlations were observed between Lysholm and Tegner (r=0.38, p=0.17) and Cinncinati and Tegner (r=0.36, p=0.18) scores. Post-operatively all scores were strongly related (r=0.61- 0.93). However, only the relationships between Lysholm and IKDC score (p=0.001) and IKDC and Cinncinati score (p=0.01) reached statistical significance.

The results of this study indicate that the commonly used rating scales produce interchangeable results in the ACL-deficient patient. In the ACL-reconstructed patient, knee scoring systems seem to measure different aspects of physical activity, physical disability and subjective patient satisfaction—all of which are not interchangeable. As such, the classification of results may vary and may explain the findings.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIII | Pages 192 - 192
1 May 2012
Hohmann E Tay M Tetsworth K Bryant A
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Epidemiologic studies project an increase of hip fractures worldwide. They are an important cause of morbidity and mortality in the elderly and represent an increasing burden on a country's health service. The aim of the study was to evaluate the mortality of hip fractures admitted to a regional hospital in Australia and calculate the relative risk ratio of morbidity variables on mortality.

This retrospective review included all patients admitted from 2003 to 2008 to a regional Queensland hospital with a hip fracture. The relative risk ratio for the probability of death was calculated for the following variables: previous mobility (independent, home with help, nursing home), type of treatment (hemiarthroplasty, ORIF, DHS/Nail, total hip arthroplasty, conservative), ASA, comorbidities (dementia, hypertension, cardiac, respiratory, renal, previous hip fractures, diabetes), pre-operative haemoglobin, BUN ratio, length of stay, operative time, anaesthetic time and type (general, spinal) and, gender.

A total of 211 patients (136 female, 75 male) with an average age of 79.1 years were admitted. Seventy-six patients died during the specified interval. The average 30 day mortality was 6.2% and the average time of survival was 318 days. The relative risk of death was above one for the following variables: female gender 1,16; nursing home 1,11; more than 1 comorbidity 1,38; more than 4 comorbidities 1,78; dementia 1,12; diabetes 1,3; hypertension 1,35, previous fractures 1,43; ASA 4 1,5; operating time more than 120 minutes 7,4; length of stay more than 20 days 2,16, BUN ratio>0.1 1,38 and BUN ration<0.04 1,78.

This retrospective project identified a number of variables influencing mortality of hip fractures. These results demonstrate that the relative risk substantially increases with length of surgical time, length of hospital stay in excess of 20 days and more than four associated comorbidities.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_III | Pages 108 - 108
1 Feb 2012
Hohmann E Tetsworth K Wisniewski T
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Introduction

Primary wound closure in open tibial fractures has not been recommended. Traditionally initial debridement with fracture stabilisation and delayed wound closure was the accepted treatment. However this practice was developed before the use of prophylactic intravenous antibiotics and improved techniques for fracture stabilisation. Studies suggest that infections are not caused by the initial contamination but the organisms acquired in the hospital. Subsequent primary wound closure after adequate wound care and fracture stabilisation should be a safe concept and should not increase the rate of complications.

Material/methods

In a retrospective study we analysed 95 patients with open tibial fractures Gustilo-Anderson Type 1-3a treated at two different teaching hospitals with primary fracture stabilisation and delayed wound closure as group I and primary fracture stabilisation and primary wound closure as group II. Exclusion criteria to the study were the following conditions: Grade 3b and 3c fractures, polytrauma, other fractures, significant medical history, previous surgery 6 months prior to admission. In group I 46 patients (38 males, 8 females) with a mean age of 30.2 years (16-56) were included. 19 sustained Grade 1 open, 16 Grade 2 open, 4 Grade 3a open and 7 gunshot fractures to the shaft of the tibia. In group II 49 patients (36 males, 13 females) with a mean age of 33.4 (18-69) were included. 19 sustained Grade 1 open, 19 Grade 2 open, 3 Grade 3a open and 8 gunshot fractures. The mean follow-up in group 1 was 11.5 (9-18) and 11.7 (8-16) months. The criteria for post-operative infection were clinical/radiological.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_III | Pages 114 - 114
1 Feb 2012
Hohmann E Bryant A Newton R Steele J
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The level of hamstring antagonist activation is thought to be related to knee functionality following anterior cruciate ligament (ACL) injury/surgery as pronounced co-activation can control anterior tibial translation (ATT). The purpose of this study was to examine relationships between knee functionality and hamstring antagonist activation during isokinetic knee extension in ACL deficient (ACLD) and ACL reconstructed (ACLR) patients. Knee functionality was rated using the Cincinnati Knee Rating System for the involved limb of 10 chronic, functional ACLD patients and 27 ACLR patients (14 using a patella tendon (PT) graft and 13 using a semitendinosus/gracilis tendon (STGT) graft). Each subject also performed maximal effort isokinetic knee extension and flexion at 180°. s-1 for the involved limb with electromyographic (EMG) electrodes attached to the semitendinosus (ST) and biceps femoris (BF) muscles. Antagonist activity of the ST and BF muscles was calculated in 10° intervals between 80-10° knee flexion.

For the ACLD group, Pearson product moment correlations revealed significant (p<0.05) moderate, positive relationships between knee functionality and ST and BF antagonist activity across the majority of the knee flexion intervals. For both ACLR groups, several significant (p<0.05) moderate, negative associations were found between ST and BF antagonist activity and knee functionality.

Amplified hamstring antagonist activity in ACLD patients at flexion angles representative of those at footstrike and deceleration improves knee functionality as increased crossbridge formation increases hamstring stiffness and decreases ATT. Lower-level hamstring activation is sufficient to unload the ACL graft and improve knee functionality in ACLR patients.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 204 - 204
1 May 2011
Hohmann E Tetsworth K
Full Access

Introduction: Correct placement of the acetabular cup is a crucial step in total hip replacement to achieve a satisfactory result and remains a challenge with free hand techniques. Imageless navigation may provide a viable alternative to freehand technique and improve placement significantly. The purpose of this study therefore was to assess and validate intra-operative placement values as displayed by the navigation unit to postoperative measurement of cup position using high resolution CT scans.

Methods: 32 patients underwent primary hip joint replacement using imageless navigation. The average age was 66.5 years (range 32–87). 23 non-cemented and 9 cemented acetabular cups were implanted. During surgery we aimed for 45 degrees of inversion and 15 degrees of anteversion. A pelvic CT scan using a multi-slice CT was used to assess the position of the cup radiographically.

Results: 2 patients were excluded because of dislodgement of the tracking pin. Pearson correlation revealed a strong significant correlation (r=0.68; p< 0.006), for cup inclination and a moderate non-significant correlation (r=0.53; p=0.45) between intra-operative readings and cup placement.

Discussion: These findings can be explained with possible introduction of systematic error. Even though the acquisition of anatomic landmarks are simple they must be acquired with great precision. An error of 1 cm can result in a mean anteversion error of 6 degrees and inclination error of 2.5 degrees. Whilst navigation results in highly accurate cup placements in relation to inclination, ante-version of the cup can not be determined accurately.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 129 - 129
1 May 2011
Hohmann E Tetsworth K
Full Access

Introduction: Malpositioning of the acetabular cup component in total hip arthroplasty can result in increased wear, early nonseptic loosening and is the most common cause of dislocation. Previous research has defined a safe zone with an inclination of 40±10 degrees and anteversion of 15±10 degrees. The purpose of this study was to compare cup placement using imageless navigation to a historical control group using CT based measurements.

Methods: 34 patients receiving a primary hip replacement between June 2005 and December 2006 were enrolled in the study. Alignment of the implant is based on the acquisition of landmarks (ASIS and pubic tubercle) and placement of tracking pins into the ASIS. The target position for all patients was 45 degrees of inclination and 15 degrees of anteversion. The position was determined by postoperative Ct scans of the pelvis. This group was compared to a matched control group.

Results: Descriptive statistics revealed that the demographics of both groups were comparable. Mean cup placement in the navigation group was 46.6±5.9 deg of inclination and 18.8±5.6 deg of anteversion. Mean cup placement in the control group was 48.4±8.85 deg of inclination and 22.33±10.9 deg of anteversion. With navigation 73.7% resp 89.5% of cups were placed within the safe zone for inclination resp. anteversion whereas only 56.2% resp. 50% of cups were placed with freehand technique. Taking both inclination and anteversion into consideration 68.4% of cups were placed in the safe zone with navigation. Only 12.5% were placed for both inclination and anteversion were placed into the safe zone.

Discussion: Computer navigation for total joint arthroplasty, if helpful to the surgeon, has to increase reliability of component placement and show a significant reduction in variation compared to freehand techniques. Our results demonstrate that imageless navigation is a reliable tool which significantly increases precision of acetabular cup placement. Further studies are needed to evaluate and further increase the accuracy of the system.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 175 - 175
1 May 2011
Hohmann E Bryant A Tetsworth K Urbaniak M
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Introduction: Anthropometric anatomical factors may influence mechanical and functional stability of joints. An increased posterior tibial slope places the anterior cruciate ligament at a theroretical biomechanical disadvantage. An increased posterior tibial slope can potentially alter forces during landing tasks by either increasing anterior tibial translation and/or ACL loading. The purpose of this study is to investigate the relationship between posterior tibial slope and anterior cruciate ligament injuries. It is hypothesized that subjects with an ACL injury have an increased posterior tibial slope compared to a normal population.

Methods: Posterior tibial slope in 211 patients (154 male, 57 female) aged 15–49 who underwent anterior cruciate ligament reconstruction was measured using the posterior tibial cortex as reference. A matched control group was used for comparison.

Results: The average posterior tibial slope in the ACLR population was 6.1 degrees while the control group had average values of 5.4 degrees. This finding nearly reached statistical significance (p=0.057). In the male population average values were 5.5 degrees in the ACLR group and 5.9 in the control group. This was not significant (p=0.21). However there was a significant difference (p=0.04) in the female group. ACLR females had higher values 6.5 degrees whereas the control group had average values of 5.2 degrees.

Discussion: Increased posterior tibial slope decreases the inclination of the ACL and potentially decreases vector force during dynamic tasks. It may further result in suboptimal length-tension relationships of agonistic muscles, increases in electromechanical delays and result in lower force development further leading to increased vector forces on the ACL. Posterior tibial slope angles were slightly smaller than with other published studies. However by using the posterior tibial cortex as reference an average of 3 degrees must be added to the measured values. We could not confirm the results of previous studies demonstrating an increased degree of posterior tibial slope in ACL injured patients. However we demonstrated a significant difference in tibial slope in females. Based on our results an increased posterior tibial slope is not a risk factor in males but possibly contributes to ACL injuries in females. Increased posterior tibial slope may be one of the reasons why females have a higher incidence of ACL injuries.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 189 - 189
1 Mar 2010
Hohmann E Tay M Tetsworth K Bryant A
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Anterior cruciate ligament reconstruction has become a standard procedure with a documented good and excellent outcome of 70–90%. Important variables of outcome after surgery consist of objective and subjective variables. It is important to examine the relationship between commonly used knee rating systems and functional tests to assess whether there is a correlation between rating systems and functional performance. The purpose of this study was to determine if a correlation exists between four commonly used knee rating systems (Lysholm, Tegner, IKDC, Noyes) and commonly performed dunctional tests: single and timed hop, vertical jump and isometric, isokinetic and eccentric muscle strength.

44 consecutive patients (31 males and 13 females) were selected (mean age 27.9 years). All subjects were tested prior and 12 month following anterior cruciate ligament reconstruction. The subjects completed the above knee rating scores. The patients were then evaluated performing the following tests: single leg hop for distance, timed hop and vertical jump. Muscle strength was assessed using a Biodex dynamometer. Isometric strength was examined at 30 and 60 degrees of flex-ion. Isokinetic testing (concentric and eccentric) was performed at 120 and 180 degrees/sec. Their results of functional testing were expressed as percentage of the contralateral non involved limb.

A positive correlation was found between single leg hop, Lysholm (r=0.53, p< 0.05). IKDC (r=0.30, p< 00002) and Noyes score (r=0.45, p< 0.01). A positive correlation was found between vertical jump, Lysholm (r=0.21, p< 0002), IKDC (r=0.31, p< 0.0001) and Noyes score (r=0.31, p< 0.0001). There was no correlation between timed hop and knee scores. A negative correlation (r=0.25–0.46) was noted between eccentric peak extension torque at 120 degrees/sec and 180 degrees/sec (r=0.230.26). However it only reached significance (p< 0.04) between IKDC and eccentric torque at 120 degrees/sec and 180 degrees/sec (p< 0.01). In addition there was a moderate negative correlation (r=0.26, p< 0.0004)) between Lysholm score and eccentric peak torque at 180 degrees/sec. No correlations were found for isokinetic and isometric torque for the knee flexors.

Knee rating systems seem to reflect functional capabilities and subjective satisfaction of patients prior and post ACL reconstruction. Isokinetic strength does not seem to be an important predictor of knee function.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 183 - 183
1 Mar 2010
Hohmann E Tay M Tetsworth K Bryant A
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Malpositioning of the acetabular cup component in total hip arthroplasty can result in increased wear, early nonseptic loosening and is the most common cause of dislocation. Previous research has defined a safe zone with an inclination of 40±10 degrees and anteversion of 15±10 degrees. The purpose of this study was to using CT based measurements.

32 patients receiving a primary hip replacement between June 2005 and December 2006 were enrolled in the study. Alignment of the implant is based on the acquisition of landmarks (ASIS and pubic tubercle) and placement of tracking pins into the ASIS. The target position for all patients was 45 degrees of inclination and 15 degrees of anteversion. The position was determined by postoperative Ct scans of the pelvis. This group was compared to a historical control group.

Descriptive statistics revealed that the demographics of both groups were comparable. Mean cup placement in the navigation group was 46.6±5.9 deg of inclination and 18.8±5.6 deg of anteversion. Mean cup placement in the control group was 45.8±9.5 deg of inclination and 27.3±15.0 deg of anteversion. With navigation 73.7% resp 89.5% of cups were placed within the safe zone for inclination resp. anteversion whereas only 60.9% resp. 39% of cups were placed with freehand technqie. Taking both inclination and anteversion into consideration 68.4% of cups were placed in the safe zone with navigation. Only 25.7% were placed for both inclination and anteversion were placed into the safe zone.

Computer navigation for total joint arthroplasty, if helpful to the surgeon, has to increase reliability of component placement and show a significant reduction in variation compared to freehand techniques. Our results demonstrate that imageless navigation is a reliable tool which significantly increases precision of acetabular cup placement. Further studies are needed to evaluate and further increase the accuracy of the system


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 194 - 195
1 Mar 2010
Hohmann E Imhoff A
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Large osteochondral defects of the femoral condyle still pose a difficult problem to treat. A variety of options is available but most of result in replacement with inferior fibrous or hyaline-like cartilage in the load-bearing zone of the knee joint. We present the five year results of Mega-OATS. This technique utilizes the posterior femoral condyle for coverage of osteochondral defects and is called Mega-OATS.

From July 1999, 33 patients of mean age 34.3 years (15–59) were treated with MEGA-OATS. Fifteen patients additionally underwent high tibial osteotomy and two bone grafting using bone harvested from the proximal tibia. The average defect size was 6.2±1.8 cm2. The mean follow up was 66.4±13.2 months. The technique calls for excision of the posterior femoral condyle which is placed in a specially designed work station.

The Lysholm score increased post-operatively from 49.0±19.4 to 88.5±14.9 12 months post surgery to 85.5±16.0 five years post surgery. Three months post-operatively, patients attained a full range of motion and became fully weight-bearing. There was no difference in patients undergoing combined surgery with high tibial osteotomy and patients undergoing Mega OATS as a single procedure after five years. No post-operative meniscal lesions of the posterior horn have been observed.

Mega-OATS achieves a congruent reconstruction of the articular surface in the load bearing zone of the femoral condyle. We consider it a good alternative and salvage procedure in the treatment of large osteochondral defects of the femoral condyle.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 189 - 189
1 Mar 2010
Hohmann E Tay M Tetsworth K Bryant A Tay M
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Anterior cruciate ligament reconstruction has become a standard procedure with a documented good and excellent outcome of 70–90%. It has been demonstrated by previous research that all patients following surgery demonstrate a strength deficit of almost 20%. However it is not known whether these strength deficits have an influence on postoperative functionality.

52 consecutive patients (38 males and 14 females) were selected (mean age 27.9 years). All subjects were tested prior and 12 month following anterior cruciate ligament reconstruction. Muscle strength was assessed using a Biodex dynamometer. Isometric strength was examined at 30 and 60 degrees of flexion. Isokinetic testing was performed at 180 degrees/sec and peak torque and symmetry indices were analysed.

No correlations were found between the Cinncinnati Score and isokinetic peak torque for extension. A moderate significant (p=0.001–0.007) correlation (r=0.200.45) was found for peak flexion torque in ACL reconstructed patients. In ACL deficient patients symmetry indices (r=0.36–0.43, p=0.001–0.004) were moderately related to functionality for both flexion and extension.

Quadriceps muscle strength does not seem to be an important predictor of knee function after ACL reconstruction. Flexors seem to be important to protect the graft from overload. In ACLD knees functionality is related to high symmetry indices suggesting similar strength is necessary to perceive knee function as near normal. This is possibly a normal neuromuscular adaptation caused by contralateral quadriceps avoidance.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 194 - 194
1 Mar 2010
Coyle C Tay M Tetsworth K Bryant A Hohmann E
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Gait analysis is an important tool to measure function following total knee replacement. It is currently unknown whether there is a correlation between subjective and objective outcome variables. The purpose of this study was to analyse relationships between subjective outcome scores and kinematic and kinetic data.

25 consecutive patients (15 males, 10 females) were selected (mean age 68 years, BMI 31.8). All subjects were tested a minimum of 24 months following total knee replacement. SF12, Oxford knee score, knee society and KOOS scores were collected. Muscle strength was assessed using a Biodex dynamometer and symmetry indices were analysed. A timed up and go test and KT2000 measurements were performed.

Strong correlations (r=0.52–0.74) were found between scoring systems (SF 12, Oxford knee score, knee society score, KOOS score) and the timed up and go test. Moderate correlations (r=0.27–0.35) were found between knee scores and KT2000 measurements. Only weak correlations (r=0.09–0.12) were found between knee scores and strength. None of the correlations reached statistical significance. Post hoc contrasts demonstrated adequate power (0.95) of the study.

The finding of this study suggests that outcome scores and objective and functional tests following total knee arthroplasty measure different variables of outcome. Whilst objective tests and gait analysis provide an understanding of joint mechanics after surgery and can be used to calculate resultant forces and moments, patient perceived outcomes have no Significant correlation to knee biomechanics. This may be related to factors such as pain relief, improved quality of life and the ability to perform activities of daily life. In contrast modern implants may provide a satisfactory outcome resulting in high patient satisfaction. The results of this study underline the importance of using subjective patient outcome measures to follow up total knee replacement patients.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 214 - 214
1 Mar 2010
Hohmann E Tay M Tetsworth K Bryant A
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Non-operative treatment of lateral clavicle fractures presents a difficult problem. A high incidence of non-union, residual pain and shoulder girdle instability has been reported. A variety of fixation techniques have been described but the complication rates of these procedures can be high. This retrospective review describes the use of distal radius locking plates for fixation of lateral unstable clavicle fractures.

From January 2006 until December 2007 23 patients (17 males, 5 females; mean age 31 yrs (12–70) presented to our service. 2 patients sustained type 1, 16 patients type 2, 2 patients type 4 and 3 patients type 5 fractures (Neer classification). Patients were reviewed clinically, radiographically and with Constant score assessment.

Union was acchieved at a mean follow up of 7.2 weeks. The mean Constant score at 6 months was 84, the mean DASH score 27.7. The following complications were seen during the follow-up period: 1 superficial infection settling with oral antibiotics and 1 non-union in a type 5 fracture requiring bone grafting.

Clavicle fractures of the lateral aspect are controversial. The mechanism of injury often results in ruptures of the adjacent coracoclavicular ligaments and create instability and increased motion between the proximal and distal fragment. The result of this series of cases are encouraging and we recommend the use of distal radius locking plates to treat unstable lateral clavicle fractures. However a larger study is needed to further evaluate mid- and long-term shoulder function.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 349 - 349
1 Sep 2005
Hohmann E Bryant A Eiling E Peterson W Murphy A
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Introduction and Aims: Hormonal factors are one plausible explanation for differences in musculotendinous stiffness (MTS) and knee laxity between men and women, and the resulting higher risk for ACL injury in women. This study examined MTS and ACL laxity over the course of the menstrual cycle in women and investigated the interaction of warm-up.

Method: Eight female netball players aged between 16–18 years (mean = 16.3 ± 0.8 years) participated in this study. None of the participants were using oral contraceptives and all demonstrated regular menstrual cycles. Venous blood samples and MTS data were collected each week over the 28-day menstrual cycle. MTS was assessed prior to, and following a standardised warm-up consisting of light cycling and jumping. ACL laxity was determined at the beginning of each test session using the KT2000™ knee arthrometer (MEDmetric Corporation, San Diego, USA).

Results: Repeated measures ANOVA results revealed significant (p < 0.05) main effects of warm-up and test session on MTS. For the effect of warm-up, MTS was found to significantly decrease by 4.2% following the warm-up intervention, indicating that relatively low levels of activity can acutely alter the viscoelastic properties of muscle. Post hoc contrasts for test session revealed that MTS was significantly lower at week three (corresponding to the ovulatory phase), in contrast to weeks one and two (7% and 4.5% decrease, respectively). For ACL laxity, repeated measures ANOVA revealed no significant (p < 0.05) differences at 30 lb anterior force across the menstrual cycle. The results did however demonstrate a trend towards increased ACL laxity during ovulation (week three) when the lower limb musculature was most compliant.

Conclusion: While there were no significant differences in static ACL laxity, reduced MTS is one of the main causes of prolonged electromechanical delay (EMD) and has particular relevance for ACL injury. In conclusion, females are at greater risk of incurring an ACL injury during ovulation when oestrogen levels are highest.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 349 - 350
1 Sep 2005
Hohmann E Imhoff A Woertler K
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Introduction and Aims: The possible deleterious effects of long distance running remain controversial. The repetitive loading could potentially predispose to the subsequent development of osteoarthritis. The purpose of this study is to investigate whether external impact loading in marathon runners creates internal stresses on bone and cartilage that are demonstrable on MR images.

Method: Six recreational, two semi-professional runners and seven beginners underwent magnetic resonance (MR) imaging of the hip and knee before and after a marathon run using coronal body phased-arrayed coil and the following pulse sequences: a coronal T1 weighted spin echo sequence and STIR sequences. To be included in the study, the runners had to successfully finish a previous race in less than 4.5 hours. The following exclusion included surgery for overuse injuries in the prior 48 months, and symptoms of overuse in the six months preceding the race.

Results: The pre- and post-run scans failed to demonstrate marrow oedema, periosteal stress reactions or joint effusions in seven runners. One patient who underwent a reconstruction of his anterior cruciate ligament 18 months ago demonstrated a small effusion in the reconstructed knee before and after the race. Six of the beginners demonstrated minimal effusions in the hip and knee joints. However no bone oedema was seen in any of the beginners.

Conclusions: Our results suggest that the high impact forces in long distance running are well tolerated and subsequently not demonstrated on MR images in experienced runners. Beginners do compensate the impact stresses to a certain extend and it is postulated that long distance runners undergo a natural selection process.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 309 - 309
1 Sep 2005
Hohmann E Radziekowski J Wiesniewski T
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Introduction and Aims: Primary wound closure in open tibial fractures has not been recommended. Studies suggest that infections are not caused by the initial contamination but the organisms acquired in the hospital. Primary wound closure after adequate wound care and fracture stabilisation should be a safe concept.

Method: We analysed 95 patients with open tibial fractures Gustilo-Anderson Type 1-3a treated with primary fracture stabilisation and delayed wound closure (group I) and primary fracture stabilisation and primary wound closure (group II). In group I, 46 patients (38 males, eight females) with a mean age of 30.2 years (range 16–56) were included. In group II, 49 patients (36 males, 13 females) with a mean age of 33.4 (range 18–69) were included. The mean follow-up in group I was 11.5 (range 9–18) and 11.7 (range 8–16) months.

Results: The mean operating time in group I was 96 (range 45–180) minutes, in group II, 101 (range 40–170) minutes. The hospital stay in group I was 8.6 (range 3–20) days and in group II, 15.4 (range 4–52) days. One infectious case in group I was seen (2%) and two cases in group II (4.3%) were found. On further analysis, one case in group II, in our opinion, should not have been treated with primary fixation and wound closure. He only had three doses of a first generation cephalosporin and was operated 20 hours after admission to hospital. The corrected infection rate in group II should therefore should be calculated without that case and then is 2.1%.

Conclusions: Our results support recent findings that primary wound closure after thorough debridement in Grade I and II open fractures does not increase the infection rate in comparison to the standard treatment. It shortens hospital stay and is cost-effective treatment. We conclude that primary wound closure is safe.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_I | Pages 25 - 25
1 Mar 2005
Hohmann E Imhoff A
Full Access

High tibial osteotomies are commonly performed for varus/valgus malalignment of the knee. In the past we have been well aware that a high tibial osteotomy corrects the coronal plane but we did not consider changes of the tibial slope. Altering the slope has an impact on the in situ forces of the cruciate ligaments and influences the stability of the knee. The purpose of this study was to investigate the amount of alteration of the tibial slope by a closed wedge osteotomy.

From January 2001 to September 2001 we reviewed retrospectively all Xrays of patients that underwent a high tibial osteotomy or were admitted for removal of hardware. 80 patients were included. 67 patients could be followed up.

The slope on the preoperative xrays was 6,1 degrees (0–12). A closed wedge osteotomy decreased the slope by a mean of 4,88 degrees. A high tibial osteotomy of six degrees in the coronal plane decreased the slope by 4.29 degrees, a HTO of eight degrees decreased the slope by 7 degrees, a HTO of ten degrees by altered the slope by 4.75 and of twelve degrees by decreased the slope by 6.5 degrees.

A closed wedge osteotomy decreases the tibial slope. It is the preferred technique when a combined procedure (HTO and ACL reconstruction) is planned. There is no correlation between the degree of correction of the coronal plane by a closed wedge high tibial osteotomy and changes of the tibial slope.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_I | Pages 26 - 26
1 Mar 2005
Hohmann E Schoettle R Imhoff A
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Osteochondral autologous transplantation (OATS) is a new technique for the treatment of osteochondral defects.

In a prospective study between April 1996 und May 2001 we used the OATS technique to treat 201 patients (125 male, 76 female) with a mean osteochondral defect of 3,3 cm2. The defect was in the medial femoral condyle in 96 cases, the lateral femoral condyle in 16, the patella in 22, the trochlea in seven, the tibial plateau in one, the talus in 48, the tibial plafond in two and capitellum in four. There were 17 other locations. The procedure was performed either open or arthroscopically. A mean of 2,2 cylinders was transplanted.

The Lysholm score in the lower limbs increased from a preoperative mean of 58,3 (20 to77) to a mean of 90,2 (70 to 100). Treatment by OATS alone increased the score from 65,2 to 91,6. With additional ACL/PCL reconstruction, the score increased from 49,9 to 82,6. The combination of OATS, HTO, ACL/PCL reconstruction increased the Lysholm score from 55,5 to 85,5. Ten per cent of patients complained of pain at the donor site in the lateral femoral condyle. There were no complications related to OATS performed in the upper limbs, and control MRI three months postoperatively showed incorporation of all cylinders.

The results are encouraging, and give rise, to the hope that this cost-effective and safe treatment for limited osteochondral defects may delay or even prevent the onset of osteoarthritis.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_I | Pages 24 - 24
1 Mar 2005
Hohmann E Schmid A
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Traumatic shoulder dislocations at young age result in a significant re-dislocation rate and lead to chronic instability. Conservative treatment fails in 25–96% of cases especially in young active patients. The accepted standard treatment is the classical open Bankart repair which almost always results in loss of motion. The development of new techniques and devices has lead to an increase in arthroscopic techniques for shoulder stabilisations.

Between September 1996 and October 2000 262 arthroscopic shoulder stabilisations were performed by the senior author: 159 cases FASTak® titanium anchors, 26 Panalok® anchors and 57 cases Suretac® anchors were used. Minimum follow up was 12 months with a mean follow up of 24.9 months (12–50). Rowe score and a visual analogue scale was used to measure patient satisfaction.

The Rowe score increased to 83,1 +/− 20,9. The visual analogue score demonstrated overall patient satisfaction. Complications included redislocations(4.7%) sub-luxations (6.3%) and ongoing instability (6.3%). Return to sports occurred in 89.1% of patients with 68.4% being able to return to their previous sports activity level.

This study demonstrates that arthroscopic shoulder stabilisation is comparable to the gold standard open Bankart repair. It is associated with a high patient satisfaction, lower morbidity, faster return to the previous activity level, better range of motion and less postoperative pain. The disadvantage of the technique is a long learning curve and the potentially longer operating times.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_I | Pages 24 - 24
1 Mar 2005
Hohmann E Schmid A Martinek V Imhoff A
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Posttraumatic shoulder instability is a common problem in the field of sports medicine. Especially overhead athletes need intact stabilisers to meet the functional requirements. Open procedures often result in limitations of movement postoperatively. Arthroscopic techniques offer potential advantages such as better range of motion and shorter rehabilitation times.

Between September 1996 and October 2000 159 arthroscopic shoulder stabilisations were performed with FASTak® anchors. The mean follow up was 24.9 months (12–50). Rowe score and a visual analogue scale were used to measure patient satisfaction. 72 patients (m=57, f=15)with a mean age of 27.6 years (17–65) were included and clinically examined.

The Rowe score increased to 83.1 after primary stabilisation and 68.1 after revision procedures. The visual analogue score demonstrated overall patient satisfaction. 89.1% (n=64) of the patients could return to sports with 68,4% (n=49) being able to return to their previous sports activity level. Overhead athletes returned to sports in 89.4% of cases and 63.3% to their pre-injury level. In the non-overhead athletes 86% returned to sports with 60% to their pre-injury level.

This study demonstrates that arthroscopic shoulder stabilisation with FASTak® anchors may be offered to the athlete regardless of the sports activity. It allows return to sports in a high percentage and does offer the potential advantages of a faster return to the previous activity level, better range of motion and less postoperative pain. Disadvantages of the technique is a long learning curve and should therefore only be performed by dedicated and experienced shoulder surgeons.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_IV | Pages 481 - 481
1 Apr 2004
Hohmann E Schoettle P Imhoff A
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Introduction Osteochondral autologous transplantation (OATS) is a technique to treat hyaline cartilage injuries in different joints. It delivers high quality hyaline cartilage to the defect.

Methods In a prospective study we used the OATS technique in 201 patients (125 male, 76 female). The mean defect size was 3.3 sq cm. The medial femoral condyle was treated in 96 cases, the lateral femoral condyle in 16, the patella in 22, the trochlea in seven, the tibial plateau in one, the talus in 48, the tibial plafond in two and the capitellum in four. There were 17 other locations. The procedure was performed either open or arthroscopically. A mean of 2.2 cylinders were implanted. Mal-alignment was corrected in 20 cases with an osteotomy and instability of the knee by anterior (ACL) or posterior (PCL) reconstruction. Five patients required reconstruction of both the ACL and PCL.

Results The Lysholm score increased from 58.3 (20 to 77) to a mean of 90.2 (70 to 100) in the lower extremity. Treatment by OATS alone increased the score from 65.2 to 91.6. With additional ACL/PCL reconstruction, the score increased from 49.9 to 82.6. The combination of OATS, HTO and ACL/PCL reconstruction increased the Lysholm score from 55.5 to 85.5. Post-operative MR imaging with intravenous contrast showed incorporation of all but one cylinder. Complications included one case of arthrofibrosis and sinking of one cylinder. One patient developed regional pain syndrome and three had pain at the malleolar osteotomy site resolved by screw removal. Ten percent of the patients developed pain at the donor site.

Conclusions The results are encouraging. It is a cost effective and safe treatment.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_IV | Pages 472 - 472
1 Apr 2004
Hohmann E Imhoff A
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Introduction High tibial osteotomies (HTO) are commonly performed for either varus or valgus malalignment of the knee. In the past we have been well aware that HTO corrects the coronal plane of the knee, but we did not consider changes of the tibial slope in the sagittal plane when planning or evaluating osteotomies. Because the tibia is a three-dimensional structure with a triangular shape, osteotomy may result in changes in both the coronal plane and the sagittal plane. Altering the tibial slope has an impact on the in situ forces of the cruciate ligaments and may influence the stability of the knee. The purpose of this study is to investigate any possible alteration of the tibial slope introduced by HTO.

Methods This study was conducted as a retrospective radiographic review of a consecutive series of patients. Between January and September 2001 a total of 80 patients underwent either HTO or the removal of hardware from a prior HTO. The radiographs of 67 of these patients were suitable for review. There were 41 males with an average age of 36.6 years (17 to 67). There were 26 females with an average age of 39.4 years (19 to 62). Routine radiographs of the knee were obtained using standard methods, and these were assessed by comparison to corresponding preoperative studies.

Results The posterior slope on pre-operative radiographs averaged 6.1° (0 to 12). HTO using a closing wedge technique was found to decrease this posterior slope by a mean of 4.9°. The change in the posterior slope was not found to correlate directly with the magnitude of the correction in the coronal plane. HTO of six degrees in the coronal plane decreased the posterior slope by 4.3° degrees, HTO of eight degrees decreased the posterior slope by seven degrees, HTO of 10° altered the slope by 4.8° degrees, and HTO of 12° degrees decreased the posterior slope by 6.5°.

Conclusions HTO by a closing wedge technique for sagittal plane correction often distorts alignment in the coronal plane as well, resulting in a decrease in the normal posterior tibial slope. We found no direct correlation between the degree of correction of the coronal plane and alteration of the tibial slope. Decreasing this slope potentially decreases in situ forces acting on the ACL while simultaneously increasing forces acting on the PCL. This may have advantages when managing combined cases with both malalignment and instability. The closing wedge technique is our preferred method when a combined procedure (HTO and ACL reconstruction) is planned.

In relation to the conduct of this study, one or more of the authors has received, or is likely to receive direct material benefits.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_IV | Pages 488 - 488
1 Apr 2004
Hohmann E Schmid A Martinek V Imhoff A
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Introduction Traumatic shoulder dislocations at a young age result in a significant re-dislocation rates and lead to chronic instability. Conservative treatment fails in 25% to 96% of cases especially in young active patients. The accepted standard treatment is the classical open Bankart repair. Re-dislocation rate could be decreased to 3.5% to 14.9% but almost always results in loss of motion. The development of new techniques and devices has lead to an increase in arthroscopic techniques for shoulder stabilisations.

Methods Between September 1996 and October 2000, 262 arthroscopic shoulder stabilisations were performed by one surgeon (ABI). For the refixation of the injured labrum suture anchors were used. In 159 cases FASTak (Arthrex) titanium anchors, in 26 cases Panalok (Mitek) and in 57 cases Suretac (Smith and Nephew) were used. The minimum follow-up was 12 months with a mean follow-up of 24.9 months (12 to 50). Exclusion criteria were SLAP and HAGL lesions, glenoid fractures, the inverted pear sign and hooked or posterior dislocations. Rowe score and a visual analogue scale were used to measure patient satisfaction.

Results The Rowe score increased to 83.1 +/− 20.9. The visual analogoue score demonstrated overall patient satisfaction. The redislocation rate was five percent, three percent having a history of adequate trauma. Complaints of subluxations and ongoing instability occured in six percent. Eighty-nine percent of the patients could return to sports with 68% being able to return to their previous sports level.

Conclusions This study demonstrates that arthroscopic shoulder stabilisation is comparable to the golden standard of open Bankart repair.


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_III | Pages 207 - 208
1 Mar 2003
Hohmann E Imhoff A
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It is suggested that there is a link between arch type of the foot and overuse injuries. The use of individual selected running shoes can reduce running injuries substantially. To select the correct shoe the runner needs to have appropriate knowledge of his own foot anatomy and biomechanics. A questionnaire was used to investigate the knowledge of the runner about his arch height and biomechanics of running. Clinical examination was performed by 5 orthopaedic surgeons and experienced orthopaedic technicians. Weight-bearing podograms were used to further define the deformity.

We examined 92 volunteers with a mean age of 35.4 (12–63) years, a mean size of 176 cm (154–195) with a mean body weight of 70.38 kg (45–95). Eighteen out of 47 runners with a flatfoot deformity identified their deformity correctly. Twenty five out of 43 volunteers with a normal arch were correct in assessing their foot. Two runners with a cavus foot were correct in identifying their foot. Only 4 out of 38 runners that diagnosed themselves as being pronators have been found to be pronators. Four runners with a self-diagnosed non-pro-nating foot were classified as being pronators. Three runners that could not classify themselves were diagnosed as pronators.

This study demonstrates the poor knowledge of foot deformities in the running community.


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_III | Pages 207 - 207
1 Mar 2003
Hohmann E Brucker P Imhoff A
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Large osteochondral defects are difficult to treat, but several treatment options are available. The posterior condyle transfer salvage technique described by Wagner in 1964 and Imhoff in 1990 has been developed further and is now used for coverage of large osteochondral defects in the load-bearing zone. The new technique is called MEGA-OATS.

From July 1999, 25 patients of mean age 33.3 years (17 to 60) were treated with MEGA-OATS. Thirteen patients additionally underwent high tibial osteotomy and two bone grafting, using bone harvested from the proximal tibia. The mean follow up was 17.8 months. The technique calls for excision of the posterior femoral condyle which is placed in a specially designed work station. A MEGA-OATS cylinder of diameter 20 mm to 35 mm is prepared and, using the press-fit technique, grafted into the prepared defect zone. The Lysholm score increased postoperatively from 66.33 (49 to 71) to 87.8 (72 to 97). Three months postoperatively control MRI showed incorporation of all cylinders. Between six and 12 weeks postoperatively patients attained a full range of motion and became fully weight-bearing. To date one superficial infection resolving on oral antibiotics and two cases of arthrofibrosis four months postoperatively that required arthroscopic release were seen. No postoperative meniscal lesions of the posterior horn have been observed.

MEGA-OATS achieves a congruent reconstruction of the articular surface in the load-bearing zone of the femoral condyle. We consider it a good alternative in the treatment of large osteochondral defects of the femoral condyle in young patients.


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_II | Pages 143 - 143
1 Feb 2003
Hohmann E Imhoff A
Full Access

High tibial osteotomy is commonly performed for varus/ valgus misalignment of the knee. Altering the sagittal plane can affect the forces of the cruciate ligaments and influence stability. This retrospective study looked at the alteration of the tibial slope produced by closed wedge osteotomy, in which the importance of the sagittal plane is often overlooked.

We followed-up 67 of 80 patients admitted for high tibial osteotomy or removal of hardware between January and September 2001. The mean age of the 41 men was 36.6 years (17 to 67) and of the 26 women 39.4 years (19 to 62).

On preoperative radiographs the mean slope was 6.1( (0( to 12(). The frontal plane was changed by a mean of 7.93( (2( to 12(). A closed wedge osteotomy decreased the slope by a mean of 4.88( (0( to 10( posteriorly and 0( to 6( anteriorly). Alteration of the coronal plane by 6( decreased the slope by 4.29(, 8( by 7(, 10( by 4.75( and 12( degrees by 6.5(.

A closed wedge osteotomy decreases the tibial slope. This causes an anterior shift in the starting position of the tibia, potentially decreasing in situ forces acting on the anterior cruciate ligament. There was no correlation between the correction of the coronal plane and alteration of the sagittal plane.


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_II | Pages 148 - 148
1 Feb 2003
Hohmann E Imhoff A
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It is suggested that there is a link between overuse injuries and the type of arch of the foot, and that the use of appropriate running shoes may reduce running injuries substantially. However, to select the correct shoe, a runner needs knowledge of the anatomy and biomechanics of his/her foot.

Five orthopaedic surgeons and experienced orthopaedic technicians examined the feet of 92 runners of mean age 35.4 years (12 to 63), mean height 176 cm (154 to 195) and mean body weight 70.38 kg (45 to 95). Weight-bearing podograms were used to define deformities of the feet further. A questionnaire ascertained what runners knew about their arch heights and the biomechanics of running. Of 43 volunteers with normal arches, 25 correctly assessed their feet, but only 18 of 47 runners with a flatfoot deformity identified their deformity. Two runners with a cavus foot identified it correctly. Only four of 38 runners who diagnosed themselves as pronators were found to be, and four runners who self-diagnosed non-pronation were classified as pronators. Three runners who could not classify themselves were diagnosed as pronators.

This study demonstrates the poor knowledge of foot deformities in the running community.


Orthopaedic Proceedings
Vol. 84-B, Issue SUPP_I | Pages - 87
1 Mar 2002
Hohmann E Schöttle PB Imhoff A
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Osteochondral autologous transplantation (OATS) is a new technique for the treatment of osteochondral defects.

In a prospective randomised study, between November 1996 and June 2000 we used the OATS technique to treat 136 patients (90 male, 46 female) with a mean osteochondral defect of 3.3 cm2. The defect was in the medial femoral condyle in 54 cases, the lateral femoral condyle in nine, the patella in 15, the trochlea in six, the tibial plateau in one, the talus in 29, the tibial plafond in two, the capitellum in four. There were 16 other locations. The procedure was performed either open or arthroscopically. A mean of 2.2 cylinders was transplanted. At the same time, we treated malalignment by high tibial osteotomy (HTO) in 20 patients, and instability by anterior (ACL) or posterior cruciate ligament (PCL) reconstruction in 16. Five patients required reconstruction of both ACL and PCL.

The Lysholm score in the lower limbs increased from a preoperative mean of 58.3 (20 to 77) to a mean of 90.2 (70 to 100). Treatment by OATS alone increased the score from 62.9 to 91.6. The combination of OATS and HTO increased the score from 65.2 to 91.6. With additional ACL/PCL reconstruction, the score increased from 49.9 to 82.6. The combination of OATS, HTO and ACL/PCL reconstruction increased the Lysholm score from 55.5 to 85.5. Control postoperative MRI with IV contrast (Gd-DTPA) showed incorporation of all but one cylinder. Complications included one case of arthrofibrosis and sinking of one cylinder. One patient developed regional pain syndrome and three had pain at the malleolar osteotomy site, resolved by screw removal. For four weeks after the operation, 10% of patients complained of pain at the donor side in the lateral femoral condyle. There were no complications related to OATS performed in the upper limbs, and control MRI three months postoperatively showed incorporation of all cylinders.

The results are encouraging, and give rise to the hope that this cost-effective and safe new treatment for limited osteochondral defects may delay or even prevent the onset of osteoarthritis.


Orthopaedic Proceedings
Vol. 84-B, Issue SUPP_I | Pages 88 - 88
1 Mar 2002
Hohmann E Agneskirchner J Imhoff A
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Knee trauma often causes meniscal injuries. Only 15% of all tears can be repaired. Partial or complete meniscectomy subsequently leads to an increased incidence of chondral damage and onset of early osteoarthritis. In Europe in 1999, 355 000 meniscal injuries were treated, 284 000 of which required partial or complete meniscectomy

As an alternative to allograft, the collagen meniscus implant (CMI®) can be used for reconstruction. A collagen matrix moulded in the form of a meniscus, this is trimmed to defect size and sutured into place arthroscopically. It then serves as a scaffold for cellular invasion. Indications are tears that require partial meniscectomy or an intact remnant stable meniscus. Cruciate ligament injuries, malalignment, osteoarthritis and stage-IV osteochondral defects are the principal contraindications.

Between July 1998 and March 2000, 10 patients received a CMI in our department. Additional pathologies (four anterior cruciate ligament (ACL) injuries, four varus malalignments and five chondral defects) were treated simultaneously. The Lysholm score increased from 70 to 99 in patients treated with an additional high tibial osteotomy (HTO), from 58 to 91 in the group with ACL reconstruction, from 71 to 93 in patients with osteochondral autologous transplantation (OATS). The Lysholm score of the combined group (two patients with HTO and OATS, two with HTO and ACL reconstruction) improved from a preoperative 69 to 99 postoperatively.

CMI, a biocompatible resorbable implant, induces cellular ingrowth and arthroscopic implantation. However, there are still questions to be answered. Few cases have been reported and no long-term studies have yet been published. It is not yet known whether osteochondral defects, unstable joints or malignment are limitations of using the implants.


Orthopaedic Proceedings
Vol. 84-B, Issue SUPP_I | Pages - 87
1 Mar 2002
Hohmann E Brucker P Imhoff A
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Large osteochondral defects are difficult to treat, but several treatment options are available. The posterior condyle transfer salvage technique described by Wagner in 1964 and Imhoff in 1990 has been developed further, and is now used for coverage of large osteochondral defects in the load-bearing zone. The new technique is called MEGA-OATS.

From July 1999, 17 patients of mean age 39 years (16 to 6) were treated by MEGA-OATS. Two patients additionally underwent high tibial osteotomy and two bone grafting, using bone harvested from the proximal tibia. The mean follow-up was 12 months. The technique calls for excision of the posterior femoral condyle, which is placed in a specially designed work station. A MEGA-OATS cylinder of diameter 20 mm to 35 mm is prepared and, using the press-fit technique, grafted into the prepared defect zone.

The Lysholm score increased postoperatively from 63 (49 to 71) to 81 (72 to 85). Three months postoperatively control MRI showed incorporation of all cylinders. Between six and 12 weeks postoperatively, patients attained a full range of motion and became fully weight-bearing. To date no postoperative complications or meniscal lesions of the posterior horn have been observed.

MEGA-OATS achieves a congruent reconstruction of the articular surface in the load-bearing zone of the femoral condyle. We consider it a good alternative in the treatment of large osteochondral defects of the femoral condyle in young patients.