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The Bone & Joint Journal
Vol. 106-B, Issue 1 | Pages 77 - 85
1 Jan 2024
Foster AL Warren J Vallmuur K Jaiprakash A Crawford R Tetsworth K Schuetz MA

Aims

The aim of this study was to perform the first population-based description of the epidemiological and health economic burden of fracture-related infection (FRI).

Methods

This is a retrospective cohort study of operatively managed orthopaedic trauma patients from 1 January 2007 to 31 December 2016, performed in Queensland, Australia. Record linkage was used to develop a person-centric, population-based dataset incorporating routinely collected administrative, clinical, and health economic information. The FRI group consisted of patients with International Classification of Disease 10th Revision diagnosis codes for deep infection associated with an implanted device within two years following surgery, while all others were deemed not infected. Demographic and clinical variables, as well as healthcare utilization costs, were compared.


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_3 | Pages 32 - 32
23 Feb 2023
Green N Barlow G Erbulut D Stubican M Vindenes F Glatt V Tetsworth K
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This study investigated concurrent talar dome injuries associated with tibial pilon fractures, mapping their distribution across the proximal talar dome articular surface. It compared the two main mechanisms of injury (MOI), falling from a height and motor vehicle accident (MVA), and whether the fractures were open or closed.

From a previously compiled database of acute distal tibial pilon fractures (AO/OTA 43B/C) in adults of 105 cases, 53 cases were identified with a concurrent injury to the talar dome with a known mechanism of injury and in 44 it was known if the fracture was open or closed. Case specific 2D injury maps were created using a 1×1mm grid, which were overlayed in an Excel document to allow for comparative analyses. A two-way ANOVA was conducted that examined the effect of both MOI and if the fracture was open or closed on what percentage of the talar dome surface was injured.

There was a statistically-significant difference between the average percentage of injured squares on the talar dome by both whether the fracture was open or closed (f(1)=5.27, p= .027) and the mechanism of injury (f(1)=8.08, p= .007), though the interaction between these was not significant (p= .156). Open injuries and injuries that occurred during an MVA were more likely to increase the surface area of the talar dome injuries.

We have identified both MOI and if the fracture was either open or closed impacts the size of the injury present on the talar dome. Future research will investigate the aetiology of the differences noted, highlighting the clinical implications.

Surgeons treating tibial pilon fractures caused by either a MVA or an open fracture, should be aware of an increased risk of large injuries to the surface of the talar dome.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_2 | Pages 102 - 102
10 Feb 2023
White J Wadhawan A Min H Rabi Y Schmutz B Dowling J Tchernegovski A Bourgeat P Tetsworth K Fripp J Mitchell G Hacking C Williamson F Schuetz M
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Distal radius fractures (DRFs) are one of the most common types of fracture and one which is often treated surgically. Standard X-rays are obtained for DRFs, and in most cases that have an intra-articular component, a routine CT is also performed. However, it is estimated that CT is only required in 20% of cases and therefore routine CT's results in the overutilisation of resources burdening radiology and emergency departments. In this study, we explore the feasibility of using deep learning to differentiate intra- and extra-articular DRFs automatically and help streamline which fractures require a CT.

Retrospectively x-ray images were retrieved from 615 DRF patients who were treated with an ORIF at the Royal Brisbane and Women's Hospital. The images were classified into AO Type A, B or C fractures by three training registrars supervised by a consultant. Deep learning was utilised in a two-stage process: 1) localise and focus the region of interest around the wrist using the YOLOv5 object detection network and 2) classify the fracture using a EfficientNet-B3 network to differentiate intra- and extra-articular fractures.

The distal radius region of interest (ROI) detection stage using the ensemble model of YOLO networks detected all ROIs on the test set with no false positives. The average intersection over union between the YOLO detections and the ROI ground truth was Error! Digit expected.. The DRF classification stage using the EfficientNet-B3 ensemble achieved an area under the receiver operating characteristic curve of 0.82 for differentiating intra-articular fractures.

The proposed DRF classification framework using ensemble models of YOLO and EfficientNet achieved satisfactory performance in intra- and extra-articular fracture classification. This work demonstrates the potential in automatic fracture characterization using deep learning and can serve to streamline decision making for axial imaging helping to reduce unnecessary CT scans.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_2 | Pages 26 - 26
10 Feb 2023
Chavan A Hoellwarth J Tetsworth K Lu W Oomatia A Alam S Vrazas E Al Muderis M
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Traditional socket prosthesis (TSP) rehabilitation for amputees is associated with substantial dissatisfaction due to poor mobility and pain from soft tissue squeezing. Osseointegration (OI), eliminates skin compression and prosthesis fit issues, providing superior mobility and quality of life (QOL) for most amputees. The potential for OI to benefit patients with exceptionally poor mobility is understudied. To address this knowledge gap, this project investigated the mobility and QOL changes.

A retrospective review was performed to identify transfemoral amputees who presented with wheelchair-bound mobility (K0) and had at least five years of post-osseointegration follow-up. Outcome measures included changes in mobility (K-level, daily prosthesis wear hours, Timed Up and Go (TUG), 6 minute walk test (6MWT)) and QOL (Questionnaire for persons with a Transfemoral Amputation (QTFA); Short Form Health Survey 36 (SF36). Adverse events recorded included debridement for infection, implant revision surgery, fractures, and implant failures.

9 patients with mean age 48.2±7.7 (range 34-59) years were included. The proportion of patients achieving K-level >2 improved from 0/9=0% to [9/9=100%], p<0.001. The 6MWT improved from 0±0 to 320.65±57 meters (p<0.001). The TUG improved from incapable to 10.68±2.7 seconds (p<0.001). Statistically significant QOL metrics included QTFA global score (33.33±31 vs 68.52±21, p=0.039), SF36 physical component score (30.03±6.3 vs 42.34±12, p=0.023) and the SF36 mental component score (47.89±8.8 vs 51.95±10.4, p=0.332). Six patients required operative intervention to address complications. Five developed infections: three had debridement, and 2 required implant removal and reimplantation.

Osseointegration does confer significant sustained mobility and quality of life improvement for wheelchair bound transfemoral amputees. All 9 K0 patients had statistically improved mobility and QOL after osseointegrated reconstruction. This supports osseointegration as an effective rapid and long-term rehabilitation alternative for patients who have the neurologic and muscular capacity to walk but are unable due to issues related to their TSP.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_2 | Pages 82 - 82
10 Feb 2023
Tetsworth K Green N Barlow G Stubican M Vindenes F Glatt V
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Tibial pilon fractures are typically the result of high-energy axial loads, with complex intra- articular fractures that are often difficult to reconstruct anatomically. Only nine simultaneous pilon and talus fractures have been published previously, but we hypothesised the chondral surface of the dome is affected more frequently.

Data was acquired prospectively from 154 acute distal tibial pilon fractures (AO/OTA 43B/C) in adults. Radiographs, photographs, and intra-operative drawings of each case were utilised to document the presence of any macroscopic injuries of the talus. Detailed 1x1mm maps were created of the injuries in each case and transposed onto a statistical shape model of a talus; this enables the cumulative data to be analysed in Excel. Data was analysed using a Chi-squared test.

From 154 cases, 104 were considered at risk and their talar domes were inspected; of these, macroscopic injuries were identified in 55 (52.4%). The prevalence of talar dome injury was greater with B-type fractures (53.5%) than C-type fractures (31.5%) (ρ = .01). Injuries were more common in men than women and presented with different distribution of injuries (ρ = .032). A significant difference in the distribution of injuries was also identified when comparing falls and motor vehicle accidents (ρ = .007).

Concomitant injuries to the articular surface of the dome of the talus are relatively common, and this perhaps explains the discordance between the post-operative appearance following internal fixation and the clinical outcomes observed. These injuries were focused on the lateral third of the dome in men and MVAs, whereas women and fall mechanism were more evenly distributed.

Surgeons who operatively manage high-energy pilon fractures should consider routine inspection of the talar dome to assess the possibility of associated macroscopic osteochondral injuries.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_7 | Pages 56 - 56
1 Jul 2022
Low J Akhtar MA Walmsley P Hoellwarth J Al-Muderis M Tetsworth K
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Abstract

Introduction

Knee arthrodesis is one of the treatment options for limb salvage of a failed total knee replacement (TKR) when further revisions were contraindicated. The aim of this study is to determine patient outcomes after knee arthrodesis (KA) following a failed TKR.

Methodology

A literature search was conducted for studies published from January 2000 through January 2022 via Medline, Web of Science, Embase and Cochrane databases. Only primary research studies were included with independent extraction of articles by two reviewers. Results were synthesised by narrative review according to PRISMA guidelines, with full tabulation of all included study results.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_13 | Pages 63 - 63
1 Nov 2021
Visscher L White J Tetsworth K McCarthy C
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Introduction and Objective

Malunion after trauma can lead to coronal plane malalignment in the lower limb. The mechanical hypothesis suggests that this alters the load distribution in the knee joint and that that this increased load may predispose to compartmental arthritis. This is generally accepted in the orthopaedic community and serves as the basis guiding deformity correction after malunion as well as congenital or insidious onset malalignment. Much of the literature surrounding the contribution of lower limb alignment to arthritis comes from cohort studies of incident osteoarthritis. There has been a causation dilemma perpetuated in a number of studies - suggesting malalignment does not contribute to, but is instead a consequence of, compartmental arthritis. In this investigation the relationship between compartmental (medial or lateral) arthritis and coronal plane malalignment (varus or valgus) in patients with post traumatic unilateral limb deformity was examined. This represents a specific niche cohort of patients in which worsened compartmental knee arthritis after extra-articular injury must rationally be attributed to malalignment.

Materials and Methods

The picture archiving system was searched to identify all 1160 long leg x ray films available at a major metropolitan trauma center over a 12-year period. Images were screened for inclusion and exclusion criteria, namely patients >10 years after traumatic long bone fracture without contralateral injury or arthroplasty to give 39 cases. Alignment was measured according to established surgical standards on long leg films by 3 independent reviewers, and arthritis scores Osteoarthritis Research Society International (OARSI) and Kellegren-Lawrence (KL) were recorded independently for each compartment of both knees. Malalignment was defined conservatively as mechanical axis deviation outside of 0–20 mm medial from centre of the knee, to give 27 patients. Comparison of mean compartmental arthritis score was performed for patients with varus and valgus malalignment, using Analysis of Variance and linear regression.


Bone & Joint Research
Vol. 10, Issue 10 | Pages 690 - 692
1 Oct 2021
Hoellwarth JS Tetsworth K Akhtar MA Al Muderis M


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_8 | Pages 50 - 50
1 Aug 2020
Woloszyk A Tuong K Tetsworth K Glatt V
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Treatment of segmental bone defects remains a major clinical problem, and innovative strategies are often necessary to successfully reconstruct large volumes of bone. When fractures occur, the resulting hematoma serves as a reservoir for growth factors and a space for cell infiltration, both crucial to the initiation of bone healing. Our previous studies have demonstrated very clear ultrastructural differences between fracture hematomas formed in normally healing fractures and those formed in segmental bone defects. However, there is little information available regarding potential differences in the underlying gene expression between hematomas formed in normal fractures, which usually heal by themselves, and segmental bone defects, which do not. Therefore, the aim of this study was to identify differences in gene expression within hematomas collected from 0.5 mm (normal fracture) and 5 mm (segmental bone defect) fracture sites during the earliest stages of bone healing.

Osteotomies of 0.5 and 5 mm in the femur of Fisher 344 rats were stabilized with external fixators (RISystem AG). After 3 days the rats were sacrificed, and the fracture hematomas were collected for RNA-sequencing. Ingenuity pathway analysis (IPA) was used to identify upstream regulators and biological functions that were significantly enriched with differentially expressed genes from the RNA-sequencing analysis. Animal procedures were conducted following the IACUC protocol of the UT Health Science Center San Antonio.

Key upstream regulators of bone formation were less active (e.g. TGFB1, FGF2, SMAD3) or even inhibited (e.g. WNT3A, RUNX2, BMP2) in non-healing defects when compared to normally healing fractures. Many upstream regulators that were uniquely enriched in healing defects were molecules recently discovered to have osteogenic effects during fracture healing (e.g. GLI1, EZH2). Upstream regulators uniquely enriched in non-healing defects were mainly involved in an abnormal modulation of hematopoiesis, revealing evidence of impaired maturation of functional macrophages and cytokines (e.g. IL3, CEBPE), both essential for successful bone healing. In addition, the enrichment pattern suggested a dysregulation of megakaryopoiesis (e.g. MRTFA, MRTFB, GATA2), which directly affects platelet production, and therefore fracture hematoma formation. Remarkably, the organization of the ECM was the most significantly enriched biological function in the normally healing fractures, and implies that the defect size directly affected the structural properties within the fracture hematoma. Conversely, genes encoding important ECM components (e.g. BGN, various collagens, IBSP, TNC), cell adhesion molecules, MMPs (MMP2), and TIMPs were all significantly downregulated in non-healing defects.

Our most recent findings reveal new important key molecules that regulate defect size-dependent fracture healing. Combined with our previous results, which identified structural differences in fracture hematomas from both types of defects, current findings indicate that differential expression of genes is dictated by the structural properties of the hematomas formed during early fracture healing. Consequently, creating a bioscaffold that mimics the structure of normal fracture hematomas could be the first step towards developing new orthoregenerative treatment strategies that potentiate healing of large bone defects and non-healing fractures.


The Bone & Joint Journal
Vol. 102-B, Issue 2 | Pages 162 - 169
1 Feb 2020
Hoellwarth JS Tetsworth K Kendrew J Kang NV van Waes O Al-Maawi Q Roberts C Al Muderis M

Aims

Osseointegrated prosthetic limbs allow better mobility than socket-mounted prosthetics for lower limb amputees. Fractures, however, can occur in the residual limb, but they have rarely been reported. Approximately 2% to 3% of amputees with socket-mounted prostheses may fracture within five years. This is the first study which directly addresses the risks and management of periprosthetic osseointegration fractures in amputees.

Methods

A retrospective review identified 518 osseointegration procedures which were undertaken in 458 patients between 2010 and 2018 for whom complete medical records were available. Potential risk factors including time since amputation, age at osseointegration, bone density, weight, uni/bilateral implantation and sex were evaluated with multiple logistic regression. The mechanism of injury, technique and implant that was used for fixation of the fracture, pre-osseointegration and post fracture mobility (assessed using the K-level) and the time that the prosthesis was worn for in hours/day were also assessed.


The Bone & Joint Journal
Vol. 98-B, Issue 7 | Pages 952 - 960
1 Jul 2016
Muderis MA Tetsworth K Khemka A Wilmot S Bosley B Lord SJ Glatt V

Aims

This study describes the Osseointegration Group of Australia’s Accelerated Protocol two-stage strategy (OGAAP-1) for the osseointegrated reconstruction of amputated limbs.

Patients and Methods

We report clinical outcomes in 50 unilateral trans-femoral amputees with a mean age of 49.4 years (24 to 73), with a minimum one-year follow-up. Outcome measures included the Questionnaire for persons with a Trans-Femoral Amputation, the health assessment questionnaire Short-Form-36 Health Survey, the Amputation Mobility Predictor scores presented as K-levels, 6 Minute Walk Test and timed up and go tests. Adverse events included soft-tissue problems, infection, fractures and failure of the implant.


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. 95-B, Issue SUPP_2 | Pages 9 - 9
1 Jan 2013
Wansbrough G Tetsworth K
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High-energy injuries involving the proximal tibia sometimes result in significant soft tissue injuries that may create an incompetent knee extensor mechanism. Reconstruction of the extensor mechanism using the gastrocnemii has been previously described in those patients with tissue loss following either arthroplasty or tumour surgery. In 2009, a single cross-sectional study of eight patients described the technique after trauma, and their outcome at an average of 24 months. Use of a gastrocnemius rotational myoplasty has been described in the literature for six additional cases following trauma.

We present our indications, technique and 5-year results of a separate series of four patients in whom the extensor mechanism of the knee was rendered incompetent after direct tissue loss, or subsequent infection, secondary to trauma. In each case, after stabilisation of the periarticular fracture and control of infection, the medial gastrocnemius was employed both to reconstruct the patellar ligament, and to simultaneously restore soft tissue coverage.

Three out of 4 patients had excellent outcomes, have returned to their previous occupations and participate in regular sport. The overall mean scores were: Oxford knee Score (38.25), Knee Injury and Osteoarthritis Outcome Score (KOOS) (64.5) and Modified Cincinnati Score (68.25). Mean knee ROM was 5–97 degrees. Video for basic gait analysis was recorded.

For those traumatic injuries with the difficult combination of a soft tissue deficit and incompetence of the knee extensor mechanism, we believe the medial gastrocnemius rotational myoplasty provides an excellent reconstructive option to address both of these fundamental problems simultaneously.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XLI | Pages 138 - 138
1 Sep 2012
Gupta A McAuliffe M Brazel P Tetsworth K Bansi P
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We propose a model of care where by Regular scheduled outreach visits by a Single team provides more dependability of care and understanding of the local needs and cultural practises. Thereby titrating the care to meet local needs rather than enforcing the Western model of care to a very different cultural background.

I have been fortunate as a SET 4 Registrar to be involved with an Outreach team to Latouka Hospital. Spear headed by Dr M McAuliffe over the last 3 years the annual visit has taken shape as a dependable way of providing care to the community of Latouka. The team has evolved over the years to involve Dr Brazel, Dr Tetsworth, Dr Bansi, and our scrub staff. The team consists of 2 teams which visit Latouka every 6 months and help institute a multimodal care plan. 1) Regularity of visits helps build confidence locally and engraves the foundations of dependability of care. 2) Difficult and complex cases are discussed in specially earmarked clinics held every 6 months providing a brain storming sessions to the local clinicians and helping them achieve the best care for the patients under the restrictions of the local infrastructure. 3) Regular teaching sessions / practical workshops are held for the registrars and junior doctors empowering them to carry the baton once the visiting team leaves. 4) Regular follow up of the patients operated upon is attained to titrate care to the locals based upon the local needs and cultural practises. 5) Helping the surgical teams, nurses, radiographers, physiotherapists formulate protocols of care and comparing them to the protocols used in Australia/NZ. 6) Creating an educational fund for the local registrars enabling them to attend observer ships and courses in Australia/New Zealand.

We think that this model of care provides a much more organised and long term benefit to the local community compared to erratic visits by volunteer teams.

A similar model of care, if instituted over many divisional hospitals of the South Pacific, will be vital in improving the health care needs of the locals and provide the local staff with the much needed support they deserve.


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.