Surgeons performing hip resurfacing ante-vert and translate the femoral component anterior to maximize head/neck offset and educe impingement. The anterior femoral neck is under tensile forces during gait similarly to the superior neck [6]. This study was esigned to determine the risk of femoral neck fracture after anterior or posterior notching of the femoral neck.

Method: Fortyseven 4th generation synthetic femora were implanted with Birmingham Hip Resurfacing pros-theses (Smith & Nephew Inc. emphis, USA). Implant preparation was performed using imageless computer navigation (VectorVision SR 1.0, BrainLAB, Grmany). The virtual prosthesis was initially planned for neutral version and translated anterior, or posterior, to create the notch. The femora were fixed in a single-leg stance and tested with axial compression using a mechanical testing machine. This method enabled comparison with previously published data. The synthetic femora were prepared in 8 experimental groups:2mm and 5mm anterior notches, 2mm and 5mm posterior notches, neutral alignment with no notching (control), 5mm superior notch, 5mm anterior notch tested with the femur in 25° flexion and 5mm posterior notch tested with the femur in 25° extension We tested the femora flexed at 25° flex-ion to simulate loading as seen during stair ascent. [3] The posterior 5mm notched femoral necks were tested in extension to simulate sporting activities like running. The results were compared to the control group in neutral alignment using a one-way ANOVA:

Results: Testing Group Mean load to failure Significance Neutral (Control) 4303.09 ± 911.04N Anterior 2mm 3926.62 ± 894.17N p=0.985 Anterior 5mm 3374.64 ± 345.65N p=0.379 Posterior 2mm 4208.09 ± 1079.81N p=1.0 Posterior 5mm 3988.07 ± 728.59N p=0.995 Superior 5mm 2423.07 ± 424.16N p=0.003 Anterior 5mm in 25° flexion 3048.11 ±509.24N p=0.087 Posterior 5mm in 25° extension 3104.61±592.67N p=0.117 Both the anterior 5mm notch tested in single-leg stance and anterior notch in flexion displayed lower compressive loads to failure (3374.64N and 3048.11N). The mean load to failure value for the posterior 5mm notches in extension was 3104.62N compared to 4303.09N for the control group. Our data suggests that anterior and posterior 2mm notches are not statistically significantly weaker in axial compression. The anterior 5mm notches tend towards significance in axial compression (p=0.38) and bordered significance in flexion (p=0.087). The 5mm posterior notches were not significantly weakened in axial compression (p=0.995), but tended towards significance in extension (p=0.117). The 5mm superior notch group was significantly weaker with axial compression supporting previous data published (p=0.003). We are currently assessing offset and other variables that may reduce data spread.

Conclusion: We conclude that anterior and posterior 2mm notching of the femoral neck has no clinical implications, however 5mm anterior notches may lead to fracture. The fracture is more likely to occur with stair ascent rather than normal walking. Posterior 5mm notches are not likely to fracture with normal gait, but may fracture with higher impact activities that promote weight bearing in extension. Hip resurfacing is commonly performed on active patients and ultimately 5mm notching in the anterior or posterior cortices has clinically important implications.

Oxidized Zirconium (Oxinium, Smith & Nephew, Inc., Memphis, TN) is a relatively new material that features an oxidized ceramic surface chemically bonded to a tough metallic substrate. This material has demonstrated the reduced polyethylene wear characteristics of a ceramic, without the increased risk of implant fracture. The purpose of the current investigation was to assess clinical outcomes following primary total hip arthroplasty with Oxinium versus Cobalt Chrome femoral heads.

One hundred uncemented primary total hip arthroplasty procedures were prospectively performed in 100 patients. There were 52 males and 48 females with mean age at the time of surgery of 51 years (SD 11, range, 19–76). Using a process of sealed envelope randomization, patients were divided into 2 groups. Each group contained fifty patients. Those in group 1 received an Oxinium femoral head (OX), while those in group 2 a cobalt-chrome femoral head (CC).

The current study reports clinical outcome measures for both the OX and CC groups at a minimum follow-up of 2 years postoperatively. At the time of latest follow-up, stem survival for both groups was 98%. There was a significant improvement in all clinical outcome scores between preoperative and 2 year postoperative time periods for both bearing groups (p< 0.003). There were no significant differences between bearing groups for any of the clinical outcome scores at final follow-up (p> 0.159). Mean Harris Hip Scores at 2 years postoperatively were 92 and 92.5 for OX and CC, respectively (range; 65–100 OX, 60–100 CC). For SF-12, both the Physical Component Summary Scale (PCS) and the Mental Component Summary Scale (MCS) are reported. Mean PCS scores at final follow-up were 45.2 and 49.21 for OX and CC (range; 27.1–56.7 OX, 26.3–61.8 CC). Mean MCS scores were 53.8 and 52.57 for OX and CC (range; 39.2–65.5 OX, 34.3–64 CC). Mean final WOMAC scores are reported as 84.9 and 87 for OX and CC, respectively.

The current data suggest that total hip arthroplasty utilizing Oxinium femoral heads is safe and effective. Additional follow-up of the current cohort will be performed in order to fully assess mid-to long-term clinical outcomes.

Posterior slope of the tibial component is an important factor in overall alignment of Total Knee Arthroplasty. The purpose of this study was to compare the accuracy and reproducibility of tibial bone cuts utilizing traditional extramedullary 0 degree and angled 5 degree cutting blocks, and computer aided navigation, in primary total knee arthroplasty.

We identified 3 groups of patients. Group one were primary total knees performed using an extramedullary 0 degree cutting block for posterior slope, group 2 were performed using an extramedullary 5 degree cutting block and the third group were performed with computer navigation. Patients in all 3 groups were age and sex matched. All operations were performed by residents or clinical fellows, under the supervision of the senior authors. Lateral digital radiographs were reviewed and posterior slope was determined in a standardized fashion. Two independent blinded researchers assessed the posterior slope using Siemens Magicweb software version VA42C_0206.

The average difference from the ideal posterior slope in navigated knees was lower than with non-navigated knees, however this was not significant (p=0.086). The average difference from the ideal posterior slope in computer navigated knees was 1.77 degrees (95% CI=1.28 to 2.26) compared to 2.37 degrees (95% CI=1.56 to 3.17) with the 5 degree cutting block and 2.70 degrees (95% CI=1.73 to 3.66) with the 0 degree block. No absolute significant difference was highlighted between the 3 groups using ANOVA testing (p=0.22).

All three techniques used to obtain ideal tibial slope were accurate. Accuracy was not increased by the use of computer navigation; however navigation resulted in less variation in outcome. The two jig based methods produced similar outcomes and either technique can be used successfully.

This study was designed to determine the risk of femoral neck fracture after anterior or posterior notching of the femoral neck. The anterior femoral neck is under tensile forces during gait similarly to the superior neck [6].

Method: Fortyseven 4th generation synthetic femora were implanted with Birmingham Hip Resurfacing pros-theses (Smith & Nephew Inc. Memphis, USA). Implant preparation was performed using imageless computer navigation (VectorVision SR 1.0, BrainLAB, Germany). The prosthesis was initially planned for neutral version and translated anterior, or posterior, to create a femoral neck notch. The femora were fixed in a single-leg stance and tested with axial compression. This method enabled comparison with previously published data. The synthetic femora were prepared in 8 experimental groups: 2mm and 5mm anterior notches, 2mm and 5mm posterior notches, neutral alignment with no notching (control), 5mm superior notch, 5mm anterior notch tested with the femur in 25° flexion and 5mm posterior notch tested with the femur in 25° extension

We tested the femora flexed at 25° flexion to simulate loading as seen during stair ascent. [3] The posterior 5mm notched femoral necks were tested in extension to simulate sporting activities like running. The results were compared to the control group in neutral alignment using a one- way ANOVA:

Results: Testing Group Mean load to failure Significance

Neutral (Control) 4303.09 ± 911.04N

The anterior 5mm notch tested in single-leg stance and anterior notch in flexion displayed lower compressive loads to failure (3374.64N and 3048.11N). The mean load to failure value for the posterior 5mm notches in extension was 3104.62N compared to 4303.09N for the control group.

Our data suggests that anterior and posterior 2mm notches are not significantly weaker in axial compression. The anterior 5mm notches was not significant in axial compression (p=0.38), but trended towards significance in flexion (p=0.087). A 5mm posterior notch was not significant. (p=0.995, p=0.117). The 5mm superior notch group was significantly weaker with axial compression supporting previous published data (p=0.003).

Conclusion: We conclude that anterior and posterior 2mm notching of the femoral neck has no clinical implications, however a 5mm anterior femoral neck notch may lead to fracture. The fracture is more likely to occur with stair ascent rather than normal walking given the reduction in strength noted after testing in flexion. Posterior 5mm notches are not likely to fracture. Hip resurfacing is commonly performed on active patients and 5mm notching of anterior cortex has clinically important implications.

Minimizing tip-apex distance has been shown to reduce clinical failure of sliding hip screws used to fix peritro-chanteric fractures. The purpose of this study was to determine if such a relationship exists for the position of the lag screw in the femoral head using a cephalomedullary device.

Methods: Thirty intact synthetic femur specimens (Model #3406, Pacific Research Laboratories, Vashon, WA) were potted into cement blocks distally for testing on an Instron 8874 (Instron, Canton, MA). A long cephalomedullary nail (Long Gamma 3 Nail, Stryker, Mahwah, NJ) was inserted into each of the femurs. An unstable four-part fracture was created, anatomically reduced, and repaired using one of 5 lag screw placements in the femoral head:

Superior (N=6),

Mechanical tests were repeated for axial, lateral and torsional stiffness. All specimens were radiographed in the anterioposterior and lateral planes and tip-apex (TAD) distance was calculated. A calcar referenced tip-apex distance (CalTAD) was also calculated.

ANOVA was used to compare means of the five treatment groups. Linear regression analysis was used to compare axial, lateral and torsional stiffness (dependant variables) to both TAD and CalTAD (independent variables).

Results: ANOVA testing proved that the mean axial (p< 0.01) and torsional stiffness (p< 0.01) between the 5 groups was significantly different, but lateral stiffness was not statistically different (p=0.494). Post hoc analysis showed that the inferior lag screw position provided significantly higher mean axial stiffness (568.14±66.9N/ mm) than superior (428.0±45.6N/mm; p< 0.01), anterior (443.2±45.4N/mm; p=0.02) and posterior (456.7±69.3N/ mm; p=0.04) lag screw positions. There was no significant difference in mean axial stiffness between inferior (568.14±66.9N/mm) and central (525.4±81.7N/mm) lag screw positions (p=0.77). Post hoc analysis revealed significantly less mean torsional stiffness for the superior lag screw position compared to other lag screw positions (p< 0.01 all 4 pairings). There were no significant correlations between TAD and axial (r=−0.33, p=0.08), lateral (r=−0.22, p=0.24) or torsional (r=0.08, p=0.69) stiffness. There were significant correlations between CalTAD and axial (r=−0.66, p< 0.01), lateral (r=−0.38, p=0.04) and torsional (r=−0.38, p=0.04) stiffness.

Discussion: Our results suggest that placement of the lag screw inferiorly in the femoral head when using a cephalomedullary nail to treat an unstable peritrochanteric fracture results in the stiffest construct in axial and torsional biomechanical testing. A simple radiographic measurement, CalTAD, provides an intraoperative method of determining optimal cephalomedullary nail lag screw position to achieve greatest construct stiffness.

The use of metal on polyethylene articulations was a key development in establishing total hip arthroplasty as a successful and reproducible treatment for end stage osteoarthritis. In order to ensure implant durability in relatively younger populations, there is a need for alternative, wear resistant bearing surfaces. Oxidized Zirconium (Oxinium, Smith & Nephew, Inc., Memphis, TN) is a relatively new material that features an oxidized ceramic surface chemically bonded to a tough metallic substrate. This material has demonstrated the reduced polyethylene wear characteristics of a ceramic, without the increased risk of implant fracture. The purpose of the current investigation was to assess early clinical outcomes following primary total hip arthroplasty with Oxinium versus Cobalt Chrome femoral heads.

One-hundred primary THA procedures were prospectively performed in 100 patients. There were 52 males and 48 females. Using a process of sealed envelope randomization, patients were divided into 2 groups. Group 1 consisted of fifty patients, each receiving primary THA implants with an Oxinium femoral head (OX). The mean age of each patient was 51 years (SD 10.8, Range 22–74) with 26 males and 24 females. Group 2 also consisted of 50 patients. Within this group again each patient received primary THA implants however with a cobalt-chrome femoral head (CC). Demographics were similar with mean age 51 years (SD 11.0, Range 19–76) and again 26 males and 24 females.

The current study reports clinical outcome measures for both the OX and CC groups at a minimum follow-up of 2 years postoperatively. At the time of latest follow-up, stem survival for both groups was 98%. There was a significant improvement in all clinical outcome scores between preoperative and 2 year postoperative time periods for both bearing groups (p< 0.003). There were no significant differences between bearing groups for any of the clinical outcome scores at final follow-up (p> 0.159). Mean Harris Hip Scores at 2 years postoperatively were 92 and 92.5 for OX and CC, respectively (range; 65–100 OX, 60–100 CC). For SF-12, both the Physical Component Summary Scale (PCS) and the Mental Component Summary Scale (MCS) are reported. Mean PCS scores at final follow-up were 45.2 and 49.21 for OX and CC (range; 27.1–56.7 OX, 26.3–61.8 CC). Mean MCS scores were 53.8 and 52.57 for OX and CC (range; 39.2–65.5 OX, 34.3–64 CC). Mean final WOMAC scores are reported as 84.9 and 87 for OX and CC, respectively.

The current data suggest that total hip arthroplasty utilizing Oxinium femoral heads is safe and effective. Additional follow-up of the current cohort will be performed in order to fully assess mid- to long-term clinical outcomes.

Background: Hip fracture trials have employed a wide range of patient-reported outcomes (PRO) suggesting a lack of consensus among clinicians on what are considered the most relevant outcomes. Variability in functional outcome reporting in hip fracture management creates challenges in the comparison of results across trials. The purpose of this study was to conduct a systematic review of the functional outcomes fielded in randomized controlled trials in post-operative hip fracture treatment for the aged. We hypothesized that over time there had been an increase in patient-reported outcomes along with aggregate scoring systems of hip function.

Methods: An electronic database search was conducted using key terms combining: ‘hip fracture’ with ‘RCT’ with ‘age 65 years and over’. s and titles were screened in duplicate and independently. All of the articles that met eligibility criteria were reviewed using the 21-point Detsky Quality Assessment Scale.

Results: In 2451 citations, 86 studies were included and also met accepted standards of inter-observer reliability (kappa, 0.92; 95% confidence interval, 0.87 to 0.98). The mean score (and standard error) for the quality of the randomized trials was: 75.8% ± 1.76% (95% confidence interval, 72.3%–79.3%) and 27 (32.6%) of the trials scored < 75%. Medical trials had a higher mean quality score than did surgical trials (83.7% compared with 72.7 %, p = 0.025). 59 trials (30 Surgical, 11 medical and 18 rehabilitation trials) scored > 75% in quality. Out of 86 trials, 8 (13.6%) used EQ-5D for utility and 6 (10.1%) used the SF-36 health status measures. At most, 12 trials used the same composite score: 12 (13.9%) ADL Katz Index, 9 (10.4%) trials used the HHS and 8 (9.3%) trials used Parker’s mobility score.

Conclusion: Although in the past decade more studies have made use of outcome instruments that capture both impairment and functional status in one aggregate score, there is a lack of standardized assessment.

Introduction: This study aimed to determine the accuracy of computer navigation in simulated fixation of femoral neck and supracondylar femoral fractures using different sizes of guidewires and drills from commercially available cannulated screw systems.

Methods: Simulated fracture fixation was performed with 2.5mm, 2.8mm and 3.2mm threaded guidewires and 3.2mm and 5mm drill bits using 20 4th generation synthetic femurs. The drill or guide wire was inserted in the synthetic femurs, using fluoroscopy based computer navigation (24 drills/guidewires in each group). Pre and postoperative fluoroscopy images were acquired with the C-arm and synthetic bone in the same orientations. Virtual and real wire/drill positions were compared, and errors calculated for each diameter of drill/guidewire (sum AP + Lateral error (mm)). Errors were compared using a general linear model with Tukey adjustment for multiple comparisons. Statistical significance at a two-tailed p-value < 0.05.

Results: The mean error for the 5.0mm drill (3.20mm) was significantly less than all the threaded wires (p< 0.05). The mean error for the 3.2mm drill (5.68mm) was significantly less than the 2.5mm guidewire (9.27mm) p< 0.05, and less than the 2.8mm (8.19mm) and 3.2mm (7.14mm) threaded wires.

Discussion: For cannulated screws, the 3.2mm drill was the most accurate size tested. The most accurate drill, 5mm, would allow solid screw insertion. However, its large size may preclude screw repositioning, and unlike a cannulated screw, would not maintain fracture position whilst the screw was being inserted.

Introduction: This study compared the accuracy of reduction of intra-medullary nailed femoral shaft fractures, comparing conventional and computer navigation techniques.

Methods: Twenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9–53mm in length. All fractures were fixed with antegrade 9mm diameter femoral nails on a radiolucent operating table. Five fractures (control) were fixed with conventional techniques. Fifteen fractures (study) were fixed with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. The surgeon was blinded to defect size. Two landmark protocols were used in the study group referencing the piriform fossa (Group A, n=10) or proximal shaft axis (Group B, n=5). Postoperative CT scans, blindly reported by a musculoskeletal radiologist, were used to compare femoral length and rotation with the normal leg.

Results were analysed using ANOVA with 95% Confidence Intervals.

Results: The control and study groups were not statistically different with respect to age of cadaver or size of femoral defect. Results: The mean leg length discrepancy in the study groups were significantly less (3.6mm (95% CI 1.072 – 6.128) and 4.2mm (95% CI 0.63–7.75), compared with 9.8mm (95% CI 6.225 – 13.37) in the control group (p< 0.023). The mean torsional deformities in the study groups were 8.7 degrees (95% CI 4.282 – 13.12) and 5.6 degrees (95% CI -0.65 – 11.85), compared with 9 degrees (95% CI 2.752 – 15.25) in the control group (p=0.650). Within the navigated study group, length discrepancy was similar in subgroups 1 (3.6mm) and 2 (4.2mm). Torsion appeared more accurate in group 2 (5.6 degrees) than group 1 (8.7 degrees), although this was not statistically significant.

Discussion: Computer navigation significantly improves the accuracy of femoral shaft fracture fixation with regard to length. With further modifications to improve reduction of rotational deformity, it may be a useful technique in the treatment of femoral fractures.

Aim of the study: To evaluate the use of a gelfoam sponge as a scaffold material in delivering osteoblast cells transfected with the VEGF gene for fracture repair.

Methods: In vitro: Osteoblasts were cultured from periosteum of rabbit bone and labeled with the visible CMTMR. Commercially available gelfoam with 12 pieces (each 3 × 3 × 3 mm3) was impregnated and cultured with the labelled cells (1×106) in a 12 wells plate for 1, 3 and 7 days. We embedded the gelfoam with labeled cells in an OCT compound enface, and the sections were then examined under a fluorescent microscope. In vivo: Osteoblasts were transfected with VEGF by use of SuperFect (Qiagen Inc) and cultured for 24 hours. The gelfoam pieces were impregnated with the transfected cells (5×106) saline solution for 30 minutes and placed into a segmental bone defect created in the rabbit tibia for 7 (n=3) and 14 (n=3) days. The specimens including the new bone were cut through each site of the segmental defect and embedded in paraffin. The sections were dewaxed and immunostained with mouse anti-human VEGF.

Results: In vitro: CMTMR-labeled cells survived and were detected within gelfoam at different time intervals (days 1, 3 and 7). In vivo: Immunostained VEGF proteins were visualized in the tissues surrounding the residual gel-foam at the fracture site at days 7 and 14 post surgery.

Conclusion: Our results indicate that the labeled/transfected cells are capable of growth in a gelfoam sponge both in vitro and in vivo.

Purpose: In a prospective randomized clinical trial, we have previously reported the “limb-specific” results comparing operative (plate fixation) versus non-operative (sling) treatment for completely displaced fractures of the shaft of the clavicle. We also sought to determine the effect that a fracture of the shaft of the clavicle had on general health status, as measured by the SF-36 General Health Status instrument. We then evaluated the effects of different treatment methods (operative versus non-operative), on general health scores.

Materials: We performed a multi-center, randomized clinical trial of operative versus non-operative treatment of completely displaced clavicular shaft fractures in 111 patients. In addition to radiographic, surgeon-based, and limb-specific data we prospectively gathered SF-36 questionnaires at baseline, and at 6 weeks and 3, 6, 12, and 24 months post-injury.

Results: Both groups had SF-36 scores equivalent to or slightly superior to population norms at baseline. A clavicular shaft fracture had a significant negative effect on SF-36 scores (especially the physical components) in both groups at 6 weeks (p< 0.01) and 3 months (p> < 0.01). There was a statistically greater decrease in Physical Component Scores (PCS) in the non-operative group compared to the operative group (P> < 0.05). At 6 months, scores had returned to pre-operative levels in the operative group, but remained significantly decreased in the non-operative group (p=0.04). This difference persisted at the one and two year points.

Conclusions: A displaced fracture of the clavicular shaft has a clinically significant negative effect on general health status scores. This effect can be mitigated by primary operative fixation, which restores scores to normal levels by six months post-injury. Patients treated non-operatively for a displaced fracture of the shaft of the clavicle demonstrated lower PCS scores at two years post-injury.

Background: The literature on hip fractures is increasingly reporting patient-reported outcomes along with aggregate scoring systems. However, this rapid growth in the number and types of patient-based outcomes can be confusing. The purpose of this paper is to conduct a systematic review of the functional outcome instruments fielded in high quality randomized clinical trials evaluating postoperative hip fracture management and rehabilitation in the aged.

Methods: An electronic database search was conducted using a variety of key terms combining: ‘hip fracture’ with ‘RCT’ with ‘age 65 years and over’. Abstracts and titles were screened in duplicate and independently. Studies were eligible based on the following criteria: hip fracture, randomized controlled trial, mean age of 65 years, and in the English language. Studies were excluded based on the following criteria: inclusion of fractures other than hip, minimum age of patient enrolment < 50 years old and prevention or fracture risk reduction as primary outcome of study. All of the articles that met eligibility criteria were reviewed using the Detsky Quality Assessment Scale.

Results: In 2451 citations, 86 studies were included and also met accepted standards of inter-observer reliability (kappa, 0.92; 95% confidence interval, 0.87 to 0.98). Discordance was resolved by consensus. The mean score (and standard error) for the quality of the randomized trials was: 75.8% ± 1.76% (95% confidence interval, 72.3%–79.3%) and 27 (32.6%) of the trials scored < 75%. Medical trials had a higher mean quality score than did surgical trials (83.7% compared with 72.7 %, p = 0.025). Data was abstracted from the 59 trials (30 Surgical, 11 medical and 18 rehabilitation trials) scoring > 75% in quality. Surgical trials had 16.7% more measures of disability than measures of impairment. Furthermore, 70% of the surgical trials used composite scores when compared to either medical or rehabilitation trials. Eight trials (13.6%) used EQ-5D for utility and 6 (10.1%) used the SF-36 health status measures. At most, 10 trials used the same composite score: 10 (16,9%) ADL Katz Index, 9 (15.2%) trials used the Harris hip score and 5 (8.5%) trials used Parker’s mobility score.

Discussion/Conclusion: Although there is a trend towards studies assessing functional recovery as a primary outcome in the aged with hip fractures, none of the measures were used consistently. A lack of standardized assessment in these groups of patients will overestimate treatment effects.

The effect of cup geometry in uncemented Total Hip Arthroplasty has not been investigated. We reviewed the radiological and clinical results of 527 primary total hip arthroplasties. We assessed the bone ingrowth potential of two geometric variations of an uncemented cup and compared hydroxyappetite and porous coated shells.

Patients undergoing primary hip arthroplasty between 1997 and 2004 were prospectively entered into an arthroplasty database. Patients were reviewed at 1,2,4,5,8 and 10 years post surgery. Three acetabular shell types were used. These included hemispherical cups with porous or hydroxyapatite coating, and cups with peripheral expansion with porous coating. Radiographs with minimum 1-year follow-up were examined in 542 cases, using digital templating software. Radiographs were assessed for signs of bone in-growth, lucent lines, migration and polyethylene wear. Survivorship analysis was performed using Kaplan-Meier analysis with 95% confidence intervals. Radiological findings and cup type were analysed using Fishers exact test.

Radiological evidence of bone ingrowth was seen in 82% of hemispherical cups, compared with 59% of peripherally expanded cups, which was significant (p,0.05). Bone ingrowth was not affected by the presence of HA coating. The most common diagnoses were osteoarthritis (67%) and avascular necrosis (12%). The mean age was 56 years. Survivorship with revision or impending revision for aseptic loosening was 95.6% at 7 years (95%CI 1.0134-0.8987). The 3 revisions and 1 impending revision for loosening were in patients with avascular necrosis (3) or previous acetabular and femoral osteotomies for DDH (1), with a mean age of 44 years.

Hemispherical shells have improved radiographic outcome in comparison with peripherally expanded components. At 7 years, clinical results are similar for both components.

This study compared the accuracy of reduction of intra-medullary nailed femoral shaft fractures, comparing conventional and computer navigation techniques.

Twenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9–53mm in length. All fractures were fixed with antegrade 9mm diameter femoral nails on a radiolucent operating table. Five fractures (control) were fixed with conventional techniques. Fifteen fractures (study) were fixed with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. The surgeon was blinded to defect size. Two landmark protocols were used in the study group referencing the piriform fossa (n=10) or proximal shaft axis (n=5). Postoperative CT scans, blindly reported by a musculoskeletal radiologist, were used to compare femoral length and rotation with the normal leg. Results were analysed using the Wilcoxon two-sample test.

The mean leg length discrepancy in the study group was 3.8mm (range 1–9), compared with 9.8mm(range 0–17) in the control group (p=0.076). The mean torsional deformity in the study group was 7.7 degrees (range 20–2) compared with 9 degrees (range 0–22) in the control group (p=0.86). Within the navigated study group, length discrepancy was similar in subgroups A (3.6mm) and B (4.2mm). Torsion appeared more accurate in group B (5.6 degrees) than group A (8.7 degrees), although not significantly.

Computer navigation appears to improve leg length discrepancy following femoral nailing. Technique modification during the study improved rotational accuracy, and with further improvement, will make this technique applicable to femoral fracture fixation.

In perfroming hip resurfacing arthroplasty, concern has been expressed as to the proximity of the femoral neurovascular bundle during the anterior capsulotomy and the risk of damage during this maneuver. We therefore aimed to identify the proximity of the femoral nerve, artery and vein during an anterior capsulotomy done during a hip resurfacing procedure using the posterior approach.

A standard posterior approach was performed in 5 fresh frozen cadavic limbs. An anterior incision was then used to measure the distance of the femoral neurovascular structures to the anterior capsule. Measurements from the most posterior aspect of the vessels and nerves to the most anterior aspect of the anterior capsule were taken prior to hip dislocation. The femoral head was then dislocated, and measurements were made with the hip in both flexion and extension. In a separate group of eleven patients that underwent routine MR imaging of the hip, measurements were taken to assess the proximity of the anterior joint capsule to the femoral neurovascular bundle, by a specialist musculoskeletal radiologist who had no prior knowledge of the results obtained during the cadaveric dissection

All 5 cadaveric limbs were utilised. 3 were male and 2 were female. The average age was 72.4 years (range 56–84). The patients whom underwent routine MR imaging incorporated 6 males and 5 females with a mean age of 43.7 years (age range 18–64 years). There was no significant difference between the mean distances to the nerve (p=0.21), artery (p=0.21) or vein (p=0.65) between the MR and cadaveric groups. Prior to dislocation the femoral artery and vein were closest to the anterior capsule (mean distance of 21mm) and the femoral nerve was the furthest away (mean distance 25mm). Following dislocation there was a significant increase (25mm to 31mm) in mean distance to the femoral nerve when the superior capsule was cut with the hip in a flexed position (p=0.01) and to the femoral artery in flexion (increase mean distance from 21mm to 35mm) (p< 0.0001) and in extension(increase mean distance from 21mm to 31mm) (p=0.005). When the inferior capsule was cut, there was a significant increase (25mm to 31mm) in mean distance to the femoral nerve and femoral artery when the hip was dislocated and the capsule cut with the hip in flexion (increase mean distance from 21mm to 27mm) (p=0.019) and in extension(increase mean distance from 21mm to 28mm) (p=0.015).

This study suggests that the neurovascular structures are relatively well protected during an anterior capsulotomy performed during hip resurfacing. The procedure may be safer if the capsulotomy is performed with the hip dislocated and the hip in a flexed position while cutting the antero-superior aspect and in an extended position while cutting the antero-inferior aspect.

The purpose of this study was to develop a cell-based VEGF gene therapy in order to accelerate fracture healing and investigate the effect of VEGF on bone repair in vivo.

Twenty-one rabbits were studied. A ten millimeter segmental bone defect was created after twelve millimeter periosteal excision in the middle one third of each tibia and each tibia was plated. Primary cultured rabbit fibroblasts were transfected by use of SuperFect (Qiagen Inc) with pcDNA-VEGF. 5.0 X 106 cells in 1ml PBS were delivered via impregnated gelfoam into the fracture site. Experimental groups were:

Transfected fibroblasts with VEGF (n=7),

Radiology: Fracture healing was defined as those with bone bridging of the fracture defect. After ten weeks, fourteen tibial fractures were healed in total including six in group one, four in group two and four in group three. The VEGF group had an earlier initial sufficient volume of bridging new bone formation. Histological evaluation demonstrated ossification across the entire defect in response to the VEGF gene therapy, whereas the defects were predominantly fibrotic and sparsely ossified in groups two and three. Numerous positively stained (CD31) vessels were shown in the VEGF group. MicroCT evaluation showed complete bridging for the VEGF group, but incomplete healing for groups two and three. Micro-CT evaluation of the new bone structural parameters showed that the amount of new bone (volume of bone (VolB) x bone mineral density (BMD)), bone volume fractions (BVF), bone volume/tissues (BV/TV), trabecular thickness (Tb.Th), number (Tb.N) and connectivity density (Euler number) were higher; while structure model index (SMI), bone surface/bone volume (BS/BV), and trabecular separations (Tb.Sp) were lower in the VEGF group than the other groups. P-Values < 0.05 indicated statistical significance (ANOVA, SPSS) in all parameters except for SMI (0.089) and VolBx-BMD (0.197).

These results indicate that cell-based VEGF gene delivery has significant osteogenic and angiogenic effects and demonstrates the ability of cell based VEGF gene therapy to enhance healing of a critical sized defect in a long bone in rabbits.

The purpose of this study was to assess the accuracy of clinical assessment compared to imageless computer navigation in determining the amount of fixed flexion during knee arthroplasty.

In fourteen cadaver knees, a medial para-patella approach was performed and the navigation anatomy registration process performed. The knees were held in various degrees of flexion with two crossed pins. The degree of flexion was first recorded on the computer and then on lateral radiographs. The cadaver knees were draped as for a knee arthroplasty and nine examiners (three arthroplasty surgeons, three fellows, and three residents) were asked to clinically assess the amount of fixed flexion. Three examiners repeated the process one week later.

The mean error from the radiograph in the navigation group was 2.18 degrees (95%CI 2.18+/−0.917) compared to 5.57 degrees (CI 5.57+/− 0.715) in the observer group. The navigation was more consistent with a range of error of only 5.5 degrees (standard deviation 1.59). The observers had a range of error of 18.5 degrees (S.D. = 4.06). When analysing the observers’ error with respect to flexion (+) and extension (−), they tended to under-estimate the amount of knee flexion (median error=−4) whereas the navigation was more evenly distributed (median error=0). The highest correlation was found between navigation and the radiograph r=0.96. The highest observer correlation with the radiograph was a consultant surgeon (r=0.91) and the worst was from a resident (r=0.74). The intra-class correlation coefficient was 0.88 for the three surgeons who repeated the measurements; their mean error was 3.5 degrees with a range of fifteen degrees.

The use of computer navigation appears to be more accurate in assessing the degree of knee flexion, with a reduced range of error when compared to clinical assessment. It is therefore less likely to leave the patient with residual fixed flexion after knee arthroplasty.

The purpose of this study was to evaluate the effect of previous femoral osteotomy on the outcome of total hip replacement performed for degenerative arthritis secondary to developmental dysplasia of the hip.

Eighty three primary total hip arthroplasties were performed in sixty-nine patients with osteoarthritis secondary to developmental hip dysplasia (DDH) with a minimum three year follow up. Twenty six hips had undergone previous femoral osteotomy (eleven hips, femoral osteotomy alone (FO); fifteen hips, combined femoral and pelvic osteotomy and fifty-seven hips, no previous surgery. The non operative patients with DDH served as an age and sex matched control group (control). Cementless arthroplasty was performed in seventy-eight hips. The mean duration from femoral osteotomy to primary THA was 22.9 years. The mean follow up was 7.6 years (FO) and 7.2 years (control).

The overall revision rate was 15.4 % (FO) and 21.1 % in the Control group (p> 0.05). Twenty-one hips had one or more complications during or after surgery. The FO group had a higher femoral fracture rate (23.1%) compared to controls (10.5%) (p< 0.05). At latest mean follow-up (7.4 yrs (range, two to sixteen)), the mean Harris hip score was eighty-five (FO) and eighty-five (control group) (p> 0.05). The function and pain scores in the femoral osteotomy group were similar to the controls (p> 0.05). The requirement for bone grafting was similar and operative time significantly greater (FO) compared to controls. The frequency of radiolucent lines around the femoral component in the FO group (36%) was significantly higher than the control group (12.2%) (p< 0.05). Survival analysis was performed with the Kaplan-Meier method. At ten years, the survival of the acetabular component was 84.6%/73.6% and for the femoral component 92.2%/96% in the FO/control group.

Patients with a prior femoral osteotomy have no significant difference in functional outcome, overall complication rate or revision rate compared to controls. However, there is a significant increase in femoral fracture and operative time. Previous femoral osteotomy does not compromise the functional outcome of subsequent total hip arthroplasty.

To assess the accuracy of plain digitised radiographic images for measurement of neck-shaft and stem-shaft angles in hip resurfacing arthroplasty.

Fifteen patients having undergone hip resurfacing arthroplasty with the Birmingham Hip Resurfacing (BHR) were selected at random. Digital radiographs were analyzed by three observers. Each observer measured the femoral neck-shaft angles (NSA) of the pre-operative and stem-shaft angles (SSA) of the postoperative radiographs on two separate occasions spanning one week. The effect of femur position on SSA measured by digital radiographs was also analyzed. A BHR prosthesis was cemented into a third generation Sawbone composite femur. Radiographs were taken with the synthetic specimen positioned in varying angles of both flexion and external rotation in increments of 10° ranging from 0° to 90°.

The mean intraobserver difference in measured angle was 3.13° (SD 2.37°, 95% CI +/−4.64°) for the NSA group and 1.49° (SD 2.28°, 95% CI +/−4.47°) for the SSA group. The intraclass correlation coefficient for the NSA group was 0.616 and for the SSA group was 0.855. Flexion of the synthetic femur of twenty degrees resulted in a five degree discrepancy in measured SSA and flexion of forty degrees resulted in a thirteen degree discrepancy. External rotation of the synthetic specimen of twenty and forty degrees resulted in a three and nine degree discrepancy in measured SSA, respectively.

Patient malposition during radiographic imaging can contribute to erroneous NSA and SSA results. Significant intra- and inter-observer variation was noted in the measurement of neck shaft angle however, variation was less marked for measurement of stem shaft angle.

The purpose of this study was to evaluate functional outcome following supracondylar femur fractures using patient-based outcome measures.

Patients having sustained supracondylar femur fractures between 1990 and 2004 were identified from the fracture databases of two level-one trauma centres. Three patient-based outcome measures, the Short Form-36 (SF-36) Version two, the Short Musculoskeletal Functional Scale (SMFA), and the Lower Extremity Functional Scale (LEFS) were used to evaluate functional outcome. Each patient’s medical record was also reviewed to obtain information regarding potential predictors of outcome, including age, gender, fracture type (AO classification), presence of comorbidities, smoking status, open vs. closed fracture, and occurrence of complications. Univariate and multivariate models were then used to identify significant predictors of outcome, as reflected in the SMFA bother and dysfunction scores.

Sixty-one patients (thirty-five males and twenty-six females) with an average age (at time of injury) of 53 ± 18 years consented to participate. The average length of follow-up was 64 ± 34 months from the time of injury. Mean SF-36 V2 scores were lower than Canadian population norms indicating decreased function or greater pain, while mean SMFA scores were higher than published population norms indicating greater impairment and bother. The mean LEFS score was 40.78 ± 15.90 out of a maximum score of eighty. At the univariate level, the presence of complications was a significant predictor of both the SMFA bother (p=0.002) and dysfunction scores (p=0.015), while positive smoking status was a significant predictor of the bother score (p=0.002). Based on a multivariate linear regression model, the presence of complications (p=0.013) and positive smoking status (p=0.011) were both significant predictors of a higher SMFA bother score. In the multivariate model for SMFA dysfunction score, the presence of complications (p=0.014) and the presence of comorbidities (p=0.017) were significant predictors of a higher score.

Comparing SF-36 and SMFA scores with published population norms, supracondylar femur fractures were associated with residual impact. Based on our analysis, smoking, the presence of medical comorbidities at the time of fracture, and the occurrence of complications following fracture repair were the main predictors of poorer patient outcomes following supracondylar femur fracture.