INTRODUCTION. This study aimed to intra-operatively quantify the improvements in knee stability given both by anatomic double-bundle (ADB) and single-bundle with additional lateral plasty (SBLP) ACL reconstruction using a navigation system. MATERIALS AND METHODS. We prospectively included 35 consecutive patients, with an isolated anterior cruciate ligament injury, that underwent both ADB and SBLP ACL reconstruction (15 ADB, 20 SBLP). The testing protocol included anterior/posterior displacement at 30° and 90° of flexion (AP30–AP90), internal/external rotation at 30° and 90° of flexion (IE 30–IE90) and varus/valgus test at 0° and 30° of flexion (VV0–VV30); pivot-shift (PS) test was used to determine dynamic laxity. The tests were manually performed before and after the ACL reconstruction and the data were acquired by means a surgical navigation system (BLU-IGS, Orthokey, USA). Comparisons of pre- and post-reconstruction laxities were made using paired Student t-test (P=0.05) within the same group; comparison between ADB and SBLP groups was indeed performed using independent Student t-test (P=0.05), analysing both starting pre-operative condition and post-operative one. RESULTS. Statistically significant reduction of the global amount of laxity and global displacement was observed for both reconstructions (p<0.05) in all the performed clinical tests. Statistical differences was found between the two reconstruction considering the recovery (pre-post laxities) due to the each reconstruction, in VV0 (SBLP: 3.7±0.2° and ADB: 2.3±0.5°, p<0.0001) and in IE90 (SBLP: 9.2±3.1° and ADB: 5.0±2.8°, p=0.0022). Statistical differences were also found between the two reconstruction considering the recovery of global displacement, in particular for the lateral compartment during AP90 SBLP: 8.8±1.0 mm, ADB: 6.4±0.4 mm, p<0.0001), for the maximal lateral joint opening during VV0 (SBLP: 4.5±1.2 mm, ADB: 1.2±1.1 mm, p<0.0001) and VV30 (SBLP 3.5±1.3 mm, ADB 1.8±0.1 mm, p=0.0013) and both for the medial and lateral AP displacement during IE90 (in in medial compartment SBLP:5.6±0.6 mm, ADB: 2.7±0.7 mm, p<0.0001, in lateral compartment SBLP:8.2±1.0 mm, ADB: 3.9±0.8 mm, p<0.0001). During PS test ADB patients revealed less “hysteresis” after reconstruction (p=0.0005). Moreover SBLP patients presented more acceleration after the reconstruction compared to ADB and more evident displacement (p=0.0009). DISCUSSION. Both the reconstructions worked similarly for what concerns knee static laxity. The considered extra-articular procedure plays an important role in better controlling lateral tibial compartment displacement in drawer test and in controlling maximal lateral joint opening both at 0° and 30° of flexion. On the other hand the ADB reconstruction better restores the dynamic behaviour of the joint under PS test

Objectives. The biomembrane (induced membrane) formed around polymethylmethacrylate (PMMA) spacers has value in clinical applications for bone defect reconstruction. Few studies have evaluated its cellular, molecular or stem cell features. Our objective was to characterise induced membrane morphology, molecular features and osteogenic stem cell characteristics. Methods. Following Institutional Review Board approval, biomembrane specimens were obtained from 12 patient surgeries for management of segmental bony defects (mean patient age 40.7 years, standard deviation 14.4). Biomembranes from nine tibias and three femurs were processed for morphologic, molecular or stem cell analyses. Gene expression was determined using the Affymetrix GeneChip Operating Software (GCOS). Molecular analyses compared biomembrane gene expression patterns with a mineralising osteoblast culture, and gene expression in specimens with longer spacer duration (> 12 weeks) with specimens with shorter durations. Statistical analyses used the unpaired student t-test (two tailed; p < 0.05 was considered significant). Results. Average PMMA spacer in vivo time was 11.9 weeks (six to 18). Trabecular bone was present in 33.3% of the biomembrane specimens; bone presence did not correlate with spacer duration. Biomembrane morphology showed high vascularity and collagen content and positive staining for the key bone forming regulators, bone morphogenetic protein 2 (BMP2) and runt-related transcription factor 2 (RUNX2). Positive differentiation of cultured biomembrane cells for osteogenesis was found in cells from patients with PMMA present for six to 17 weeks. Stem cell differentiation showed greater variability in pluripotency for osteogenic potential (70.0%) compared with chondrogenic or adipogenic potentials (100% and 90.0%, respectively). Significant upregulation of BMP2 and 6, numerous collagens, and bone gla protein was present in biomembrane compared with the cultured cell line. Biomembranes with longer resident PMMA spacer duration (vs those with shorter residence) showed significant upregulation of bone-related, stem cell, and vascular-related genes. Conclusion. The biomembrane technique is gaining favour in the management of complicated bone defects. Novel data on biological mechanisms provide improved understanding of the biomembrane’s osteogenic potential and molecular properties. Cite this article: Dr H. E. Gruber. Osteogenic, stem cell and molecular characterisation of the human induced membrane from extremity bone defects. Bone Joint Res 2016;5:106–115. DOI: 10.1302/2046-3758.54.2000483

Magnetic resonance imaging (MRI) validation of a novel method of assessing Distal Radial Fracture (DRF) reduction using the hypothesised constant relationship between the dorsal radial cortex (DC) and the superior pole of the lunate (SL). MRI scans of 28 normal wrists were examined. Scans included the distal third of the radius to the proximal carpal row. Beginning 5cm proximal to the distal radius articular surface, a line was superimposed upon the DC extending distally through the metaphyseal flare. Lunate height (LH) and distance from the DC line to the SL (DC-SL) were measured at 5-degree rotational increments around the radial shaft central axis to a total of 30 degrees of supination and pronation (S+P). The DC-SL/LH ratio was compared to 0 degrees (anatomical lateral) using the two-tailed paired student t-test. There was no significant difference in DC-SL:LH between 0 degrees of rotation and any 5-degree increment up to 30 degrees of S+P (lowest p=0.075). The DC line lay consistently dorsal to the SL. A constant DC-SL relationship exists with up to 30 degrees of S+P. This reference can be quickly and accurately used to assess DRF reduction in poorly-taken films with malrotation up to 30 degrees from anatomical lateral. Research comparing DC-SL distance with volar tilt to assess DRF reduction is needed

Intro. Distal radial fractures are a commonly encountered fracture & anatomical reduction is the standard. Dorsal angulation is the traditional method of assessment but is inaccurate in rotated lateral xrays. Previously a relationship has been demonstrated between the dorsal cortex (DC) of the radius & the superior pole of the lunate (SL) & its sensitivity for assessing dorsal angulation & translation. Hypothesis. A constant anatomical relationship maintained between the DC and the SL when rotated up to 30 degrees from standard lateral?. Methods. MRI scans of 28 wrists including the distal third of the radius to the proximal carpal row. Beginning 5cm proximal to the distal radius articular surface, a line was superimposed upon the DC extending distally through the metaphysis. Lunate height (LH) & distance from the DC line to the SL (DC-SL) were measured at 5-degree rotational increments around the radial shaft central axis to 30 degrees of supination & pronation (S+P). The DC-SL/LH ratio was compared to 0 degrees (anatomical lateral) using the two-tailed paired student t-test. Results. No significant difference in DC-SL:LH between 0 degrees of rotation and any 5-degree increment up to 30 degrees of S+P (lowest p=0.075). The DC line lay consistently dorsal to the SL. Conclusion. A constant DC-SL relationship is maintained with up to 30 degrees of S+P. This reference can be quickly and accurately used to assess DRF reduction in poorly-taken films with malrotation

Objectives. The additive use of an external modular device may improve dorsal compression forces in pelvic external fixation. This would improve the efficiency of indirect reduction and stabilization with an anterior pelvic external fixator. The purpose of this study was to determine the forces of the posterior pelvis achieved by a new device improving the application of a supraacetabular anterior external fixator compared with other constructs. Material and Method. Synthetic pelvic models were used. Complete pelvic ring instability was created by symphyseal and unilateral sacroiliac joint disruption. Four different constructs of fixation were tested. A pressure-sensitive film was placed in the sacroiliac joint. The constructs were applied in a standardized way. The maximum sacroiliacal compression loads (N) of each trial was recorded. Statistics was performed with the student t-test. Results. Standard supraacetabular two-pin external fixator achieved a dorsal compression load of 13.84 (SD 8.13). The new dorsal pelvic compression device delivered 177.05N (SD 32.32) of load across the sacroiliac joint when the pins were inserted half way and 183.58N (SD 46.64) with full pin insertion. Both the half- and full-pin construct demonstrated a significant dorsal load improvement with the pelvic compressor (p<0.05) compared with the standard supraacetabular fixator group. The C-clamp revealed compression forces of 384.88N (SD 22.95), which was significantly greater than all the other groups (p<0.05). Conclusion. We tested a simple and new modular device for improved application of pelvic external fixation. The centres of rotation of supra-acetabular pins were determined and used to achieve greater dorsal compression forces in disrupted pelvic ring injuries. The compression load is less than with a C-Clamp, but significantly greater than the familiar technique of standard external supra-acetabular fixation. This improves the initial stability in acute management of unstable, disrupted and life threatening pelvic ring fractures

Introduction. Osteoarthritis (OA) of the hip and knee causes pain and functional limitations which lead to decreased physical activity level (1,2). Half of all male, and two thirds of all female, patients with early knee OA do not fulfill the recommendations for physical activity level (30 min/day of at least 5 days/week) (1). We tested the hypothesis that Scandinavian patients prior to total joint replacement had reduced actual physical activity and intensity levels compared with matched controls and that most patients did not fulfill the recommendations for physical activity. Methods. Physical activity and intensity were measured during 5 consecutive days with SenseWearTM Armband (SWA; BodyMedia, Inc., Pittsburgh, PA) in 53 patients with severe knee (n = 26) or hip (n = 27) OA prior to total joint replacement (51% women, age: 68 ± 5 years, BMI: 29.8 ± 10.2) and compared with data from 15 age-matched population-based controls (53% women, age: 68 ± 5 years, BMI: 26.9 ± 3.3). Sedentary, moderate, vigorous and very vigorous intensities were equivalent to Sense Wear Armband recordings of 3 MET, >36 MET, >69 MET, >9MET, respectively. In addition, total energy expenditure, average MET, numbers of steps/day, and the combined activity of moderate, vigorous, and very vigorous activity were calculated (min/day). Unpaired students t-test was used for between group comparisons (p < 0.05). Results. Participants wore the device for a mean ± SD of 98.5 ± 1.5% of the time. Patients spent significant less time being vigorously physically active (0.093 ± 0.082 vs. 0.156 ± 0.099 hours/day) and very vigorously active (0.015 ± 02 vs.0.028 ± 0.035 hours/day) than controls. However, no differences were observed for total energy expenditure, average MET, time spend being sedentary, and time spend being moderately physically active. The average activity of combined moderate, vigorous, and very vigorous activity for patients were 185 ± 1 min/day and 11.3% did not reach the recommended activity level. Finally, a tendency (p = 0.059) towards less steps/day was observed for patients (6778 ± 3196 vs. 8576 ± 2872 steps/day). Conclusions. Since Scandinavian OA patients prior to joint replacement show no or little decrease in physical activity, and that the majority fulfills recommendations for physical activity an increase in actual physical activity cannot be expected from surgery. This unexpected finding needs to be confirmed

Limb reconstruction requires high levels of patient compliance and impacts heavily on social circumstances. The epidemiology and socioeconomic description of trauma patients has been well documented, however no study has assessed the epidemiology of limb reconstruction patients. The aim of this project is to describe patients attending Limb Reconstruction Services (LRS) in order to highlight and address the social implications of their care. All LRS cases under a single surgeon in a district general hospital were included from 2010 – 2016. Demographics, ASA grade, smoking status, mental health status and employment status were collated. Postcode was converted into an Index of Multiple Deprivation score using GeoConvert® software. Patient socioeconomic status was then ranked into national deprivation score quintiles (quintile 1 is most affluent, quintile 5 is most deprived). Deprivation scores were adjusted by census data and analysed with Student's T-test. The distance from the patient's residence to the hospital was generated through AA route planner®. Patient attendance at clinic and elective or emergency admissions was also assessed. Patient outcomes were not part of this research. There were 53 patients, of which 66% (n=35) were male, with a mean age of 45 years (range 21–89 years). Most patients were smokers (55%, n=29), 83% (n=42) were ASA 1 or 2 (there were no ASA 4 patients). The majority of indications were for acute trauma (49%), chronic complications of trauma (32%), congenital deformity (15%) and salvage fusion (4%). Mental health issues affected 23% (n=12) of cases and 57% of working-aged patients were unemployed. Mental health patients had a higher rate of trauma as an indication than the rest of the cohort (93% vs. 76%). Deprivation quintiles identified that LRS patients were more deprived (63% in quintiles 4 and 5 vs. 12% of 1 and 2), but this failed to reach statistical significance (p=0.9359). The mean distance from residence to hospital was 12 miles (range 0.35–105 miles, median 7 miles). The patients derived from a large region made up of 12 local authorities. There was a mean of 17 individual LRS clinic attendances per patient (range: 3–42). Cumulative distance travelled for each patient during LRS treatment was a mean of 495 miles (range 28 – 2008 miles). The total distance travelled for all 53 patients was over 26,000 miles. The results largely mirror the findings of trauma demographic and socioeconomic epidemiology, due to the majority of LRS indications being post-traumatic in this series. The high rates of unemployment and mental health problems may be a risk factor for requiring LRS management, or may be a product of the treatment. Clinicians may want to consider a social care strategy alongside their surgical strategy and fully utilise their broader MDT to address the social inequalities in these patients. This strategy should include a mental health assessment, smoking cessation therapy, sign-posted support for employment circumstances and a plan for travel to the hospital. The utilisation and cost of ambulance services was not possible with this methodology. Further work should prospectively assess the changes in housing circumstances, community healthcare needs and whether there was a return to employment and independent ambulation at the end of treatment

Distal tibial physeal fractures are the second most common growth plate injury and the most common cause of growth arrest and deformity. This study assesses the accuracy of pre-operative planning for placement of the screws in these fractures using either standard radiographs or CT scans. We studied 62 consecutive physeal fractures over a period of four years. An outline of a single cut of the CT scan was used for each patient. An ideal position for the screw was determined as being perpendicular to and at the midpoint of the fracture. The difference in entry point and direction of the screw between the ideal and the observers’ assessments were compared using the paired Student’s t-test. There was a statistically significant improvement (p < 0.0001) in the accuracy of the point of insertion and the direction of the screw on the pre-operative plan when CT scans were used rather than plain radiographs. We would, therefore, recommend that CT scans are routinely used in the pre-operative assessment and treatment of distal tibial physeal fractures

Aims

No randomized comparative study has compared the extensile lateral approach (ELA) and sinus tarsi approach (STA) for Sanders type 2 calcaneal fractures. This randomized comparative study was conducted to confirm whether the STA was prone to fewer wound complications than the ELA.

Introduction. Femoral neck fractures are a large clinical and economical problem. One of the most common fixation options for femoral neck fractures are multiple cancellous screws. A previous clinical study has shown the lack of washers to be the single largest predictor of fixation failure in the treatment of femoral neck fractures with cancellous screws. This finding was somewhat surprising as washers do not prevent the screws from backing out and do not provide any increase resistance to varus collapse. Therefore a follow-up biomechanical study was designed to test this observation. The purpose was to evaluate the maximal insertional torque of screws in osteoporotic bone with and without washers. We hypothesized that the lateral cortex of an osteoporotic proximal femur does not provide sufficient counter resistance for the screw heads to obtain maximum torque upon screw insertion in the femoral head and that the use of washers would increase screw purchase by providing a larger rigid surface area and subsequent higher counter resistance thereby allowing a higher maximal screw insertion torque. Methods. We used eight matched pairs of osteoporotic fresh-frozen human cadaveric femurs (age >70 years, all female). Two screws each were inserted in each femur either with or without a washer and maximal insertional torque was measured using a 50 Nm torque transducer. The testing was performed using a customized device which allowed the torque transducer to apply a constant axial force and torque speed to the screws. A paired Student's t-test was used to compare the maximal screw insertional torque of screws with washers versus screws without washers in matched pairs. Results. Fifteen out of 16 times the maximal screw insertional torque was higher when a washer was used. The average maximal torque with a washer was 5.1 Newtonmeter (Nm) compared to 3.1 Nm without a washer (p<0.001). Conclusion. We conclude that the addition of washers increases the maximal insertion torque of cancellous screws in the treatment of osteoporotic femoral neck fractures by providing counter resistance to the screw heads at an otherwise weak lateral cortex. We have demonstrated that the washer prevents the screw heads from penetrating the lateral cortex and provides for an improved purchase of the screws in the femoral head. As a clinical reference value for interpretation of this data, the limit of torque limiting screw drivers used with locking plates is set between 4 and 6 Nm. Therefore the difference in insertion torques likely represents clinically relevant values. Since there is no apparent disadvantage in the use of washers and they are inexpensive and readily available even in less developed countries, we advocate for their routine use until larger clinical studies disprove their efficacy

Aims

Deep surgical site infection (SSI) remains an unsolved problem after hip fracture. Debridement, antibiotic, and implant retention (DAIR) has become a mainstream treatment in elective periprosthetic joint infection; however, evidence for DAIR after infected hip hemiarthroplaty is limited.

Introduction. Minimally invasive implanted unicompartmental knee arthroplasty (UKA) leads to excellent functional results. Due to the reduced intraoperative visibility it is difficult to remove extruded bone cement particles, as well as bone particles generated through the sawing. These loose third body particles are frequently found in minimally invasive implanted UKA. The aim of this study was to analyse the influence of bone and cement particles on the wear rate of unicompartmental knee prostheses in vitro. Material & Methods. Fixed- bearing unicompartmental knee prostheses (n = 3; Univation F®, Aesculap, Tuttlingen) were tested with a customized four-station servo-hydraulic knee wear simulator (EndoLab GmbH, Thansau, Germany) reproducing exactly the walking cycle as specified in ISO 14243-1:2002. After 5.0 million cycles crushed cortical bone chips were added to the test fluid for 1.5 million cycles to simulate bone particles, followed by 1.5 million cycles blended with PMMA- particles (concentration of the third-body particles: 5g/l; particle diameter: 0.5- 0.7 mm). Every 500 000 cycles the volumetric wear rate was measured (ISO 14243-2) and the knee kinematics were recorded. For the interpretation of the test results we considered four different phases: breaking in- (during the first 2.0 million cycles), the steady state- (from 2.0 million to 5 million cycles), bone particle- and cement particle phase. Finally, a statistical analysis was carried out to verify the normal distribution (Kolmogorov-Smirnov test), followed by direct comparisons to differentiate the volumetric wear amount between the gliding surfaces (paired Student's t-test, p<0.05). Results. The wear rate was 12.5±0.99 mm. 3. /mio. cycles in the breaking-in phase and decreased during the steady state phase to 4.4±0.91 mm. 3. /mio cycles (not significant, p = 0,3). The bone particles did not have any influence on the wear rate (3.0±1.27 mm. 3. /mio cycles; p = 0,83) compared to the steady state phase. The cement particles, however, lead to a significantly higher wear rate compared to the steady state phase (25.0±16.93 mm. 3. /mio cycles; p<0.05). Discussion. To our knowledge this is the first study demonstrating that free cement debris which can be found after minimally invasive implanted UKA increases significantly the wear- rate. Bone particles generated for instance through sawing during implantation, however, had no influence on the prostheses wear rate. Our Data suggests, that it is extremely important to remove all the extruded cement debris accurately during implantation in order to avoid a higher wear rate which could result in an early loosening of the prostheses

Background. Habitual hip subluxation and dislocation is a potentially disabling feature of Trisomy 21. We describe long-term outcomes following precise use of the femoral varus derotation osteotomy to achieve and maintain hip stability and community ambulation. Methods. All individuals with Trisomy 21, who had hip surgery at Toronto's Hospital for Sick Children between 1998 and 2008, were searched using the hospital databases. 16 hips in 9 children aged less than 10 years, were identified. All had a femoral varus derotation osteotomy (VDRO) with a target femoral neck shaft angle (NSA) of 105° and less than 20° external rotation. All were performed by the senior author JHW. The clinical notes and radiographs were reviewed from presentation to final follow up. Continuous variables were assessed for normality with the d'Agostino Pearson test. Normally distributed variables are presented as means with 95% confidence intervals. Pre and postoperative means were compared using the student's t-test for paired samples. Results. Mean age at first known hip dislocation was 4.56 years (3.98, 5.15), mean age at surgery 6.07 years (5.15, 7.0) and mean follow-up 5.4 years (3.75, 7.06). Mean femoral neck shaft angle (NSA) fell from 166.7° (162.2°, 171.1°) to 106.0° (103.1°, 110.2°). In 2 hips, significant intraoperative instability persisted and periacetabular osteotomies with capsulorraphies were required. All patients developed an asymptomatic waddling gait postoperatively. 14 hips developed peritrochanteric varus deformities, mean 20.7° (15.96°, 25.4°)2 (12.5%) sustained periprosthetic fractures 4 and 8 years postoperatively. 1 hip (6.2%) developed painful arthritis. None re-dislocated at latest follow up. Conclusion. Prevention of long term disabling pain from habitually dislocating or recurrently subluxed hips, in patients with Trisomy 21, requires surgical intervention to increase hip containment. We believe surgical management of habitually subluxed or dislocated Trisomy 21 hips allows for a predictable result. We recommend a varus producing proximal femoral osteotomy to correct the NSA to 105° with less than 20° of external rotation. This technique was successful at restoring and maintaining hip stability in 16 hips with a mean follow-up of 5.4 years, whilst maintaining the patient's ability to remain community ambulators. It should be performed before aged 8 or signs of a widened or V-shape teardrop develops. In our experience this has been effective in maintaining hip stability. However, little is known about the natural history of habitual hip dislocation in these children. Patients with Trisomy 21 are living longer with hips that are at continuous risk. Thought should be given to the potential benefits of periodic screening of this treatable hip condition

The purpose of the study is to evaluate the retrospective results of 92 surgically treated spastic hips. Twenty-one patients were able to walk in the community with aids, 19 were able to walk about the house, and 13 were wheelchair bound. The mean age at the time of the operation was 7 yrs (3–18) and the average follow-up was 5. The cohort of the study included 45 tetraplegic patients, 6 diplegic, and 2 hemiplegic. The dislocated hips were 25 and the subluxated ones 67. The surgical treatment included soft tissue and bone procedures. The 53 patients were divided into two age groups: those less than 7yrs old and those older than 7yrs. The cohort was also divided into 39 patients operated in one setting, and 14 operated in more than one. Clinical evaluation was based on the joint range of motion, the ambulatory status and the pain. The radiological evaluation criteria were based on Reimer's migration index, the center-edge angle, Sharp's angle, and neck-femoral angle. We used the interclass correlation coefficient to measure our interobserver reliability for MI 0,93, for CE angle 0,95 and for Sharp's angle 0,81, as the interobserver difference for MI averaged 9% for CE angle 7and for Sharp's angle 3. Statistical analysis of continuous variables was done by Student's t-test or the Wilcoxon rank sum test. Categorical variables were evaluated by Fisher's test. Concerning the walking ability, from the 13 severe quadriplegic patients, none improved his functional level but they achieved better sitting balance. The walking ability of the rest of the patients improved one level in 78% of the cases. The mean preoperative abduction was improved from 24,7 to 33,5, the mean flexion was slightly reduced from 123 preoperatively to 114 postoperatively and the mean extension reduced from −20 preoperatively to −8 postoperatively. Reimer's index reduced from 67,2 to 21,7 postoperatively, the CE angle increased from −10,6 to 20,5, the Sharp's angle increased from 36,9 to 40,5 and the neck-shaft angle increased from 119,7 to 157,5post-operatively. Of greater significance were MI and CE at p<0.05. A migration index of >50% at final follow-up was associated with a worse migration index and a worse CE angle at 1 year post-operatively. 46 hips were evaluated as good, 30 as satisfactory, and 16 as poor. The severe tetraplegic with small-negative CE angle and Reimer's migration index > 50%, as well as the small age of the patients (<7 yrs) were negative prognostic factors. Better results were observed when patients were operated at age <7yrs by soft tissue procedures and MI<30%, while patients >7yrs had satisfactory results only after combined bony and soft tissue procedures and MI <50%. A migration index of >50% at final follow-up was associated with a worse migration index and a worse CE angle at 1 year postoperatively

Introduction. Patellar tracking in total knee replacements has been extensively studied, but little is known about patellar tracking in isolated patellofemoral replacements. We compared patellar tracking and the position of the patellar groove in the natural knee, followed by implantation of the femoral component of a PFR (patella unresurfaced) and after implantation of the femoral & patellar component of the PFR. Methods. Computer navigation was used to track the patella in eight whole lower extremities of four cadavers in the natural knee, in the same knee with the femoral component of the PFR (PFR-P) and with the femoral and patellar component of the PFR (PFR+P, patella resurfaced) (Depuy Sigma PFR). The form and position of the trochlea in the natural knee and the patellar groove of the femoral component was also analysed. Values are means+/−SD, two tailed Student's t-test for paired samples. Results. With a PFR-P the patella had a slightly more lateral tilt (0.8+/−0.8° to 2.8+/−2.5° at 40–100° of flexion, p<0.05 vs. Nat), this was more pronounced with the PFR+P (2.0+/−0.7° to 4.9+/−1.8° at 20–90° flexion, p<0.05 vs. Nat., p<0.05 vs. PFR-P at 20–80° flexion). No differences in patella rotation were seen between the three groups. In the PFR-P group the patella tracked a little more medially compared to the natural knee (0.6+/− 0.7mm to 1.3+/−2.6mm, p<0.05 at 20°,80°,90° flexion). The difference was more pronounced after patella resurfacing (PFR+P) (2.1+/−2.0mm to 3.0+/−2.2mm, p<0.05 vs. Nat. at 10°–100°, p<0.05 vs. PFR-P from 10–100°). When analysed relative to the patellar groove of the trochlea/femoral component the patella in the natural knee tracked slightly lateral to the groove (2.0+/−1.7mm to 2.9+/−2.0mm at 50–100° p<0.05), so did the patella of PFR-P (2.0+/−2.3mm to 2.3+/−2.3mm at 60–90° flexion, p<0.05), whilst the PFR+P tracked right on the groove (0.6+/−3.7mm medially to 0.6+/−2.9mm laterally, p<0.05 vs Nat at 10–30° & 70–100°, p<0.05 vs. PFR-P at 10–100°). Distance from the patellatot the epicondylar axis was slightly larger in the PFR-P group (0.6+/− 0.7mm to 1.3+/−1.4mm, p<0.05 vs. Natu at 20,80 & 90°. This was more pronounced with patellar resurfacing (2.1+/−2.0 to 3.0+/−2.2mm, p<0.05 vs. Nat at 10–100°, p<0.05 vs. PFR-P at 20–100°) The patella groove on the natural knee and the implanted femoral component of the implanted PFR had the same radius, inclination relative to the femoral mechanical axis, antero-posterior position and medio-lateral orientation. As intended by the designers the groove of the patellar component extended about 13mm further superiorly and 0.5mm more inferiorly. Discussion. The patella groove on the femoral component of the PFR reproduces the natural trochlear anatomy well. Patella tracking in the PFR-P shows only minor differences compared to the natural knee. Resurfacing of the patella in the PFR+P group causes the patella to tilt a little more laterally and track a little more medially, the distance to the epicondylar axis is slightly larger but this allows the patella to engage better in the patellar groove of the femoral component

Aims

The primary aim of this study was to identify independent predictors associated with nonunion and delayed union of tibial diaphyseal fractures treated with intramedullary nailing. The secondary aim was to assess the Radiological Union Scale for Tibial fractures (RUST) score as an early predictor of tibial fracture nonunion.

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To compare results of institutional preferences with regard to treatment of soft tissues in the setting of open tibial shaft fractures.

Aims

The primary aim of this study was to establish the cost-effectiveness of the early fixation of displaced midshaft clavicle fractures.

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The aim of this study was to evaluate the clinical and radiological outcomes of locking plate fixation, with and without an associated fibular strut allograft, for the treatment of displaced proximal humeral fractures in elderly osteoporotic patients.

Aims

The primary aim of this study was to develop a reliable, effective radiological score to assess the healing of humeral shaft fractures, the Radiographic Union Score for HUmeral fractures (RUSHU). The secondary aim was to assess whether the six-week RUSHU was predictive of nonunion at six months after the injury.