Aims. This study aimed to evaluate the association between the sagittal alignment of the femoral component in total knee arthroplasty (TKA) and new Knee Society Score (2011KSS), under the hypothesis that outliers such as the excessive extended or flexed femoral component were related to worse clinical outcomes. Methods. A group of 156 knees (134 F:22 M) in 133 patients with a mean age 75.8 years (SD 6.4) who underwent TKA with the cruciate-substituting Bi-Surface Knee prosthesis were retrospectively enrolled. On lateral radiographs, γ angle (the angle between the distal femoral axis and the line perpendicular to the distal rear surface of the femoral component) was measured, and the patients were divided into four groups according to the γ angle. The 2011KSSs among groups were compared using the Kruskal-Wallis test. A secondary regression analysis was used to investigate the association between the 2011KSS and γ angle. Results. According to the mean and SD of γ angle (γ, 4.0 SD 3.0°), four groups (Extended or minor flexed group, −0.5° ≤ γ < 2.5° (n = 54)), Mild flexed group (2.5° ≤ γ < 5.5° (n = 63)), Moderate flexed group (5.5° ≤ γ < 8.5° (n = 26)), and Excessive flexed group (8.5° ≤ γ (n = 13)) were defined. The Excessive flexed group showed worse 2011KSSs in all subdomains (Symptoms, Satisfaction, Expectations, and Functional activities) than the Mild flexed group. Secondary regression showed a convex upward function, and the scores were highest at γ = 3.0°, 4.0°, and 3.0° in Satisfaction, Expectations, and Functional activities, respectively. Conclusion. The groups with a sagittal alignment of the femoral component > 8.5° showed inferior clinical outcomes in 2011KSSs. Secondary regression analyses showed that mild flexion of the femoral component was associated with the highest score. When implanting the Bi-Surface Knee prosthesis surgeons should pay careful attention to avoiding flexing the femoral component extensively during TKA. Our findings may be applicable to other implant designs. Cite this article: Bone Joint J 2020;102-B(6 Supple A):36–42

We describe a case of symptomatic focal femoral osteolysis around a screw hole distal to the hydroxyapatite-coated portion of a cannulated femoral component in a revision hip replacement. No locking screw had been inserted into this, the most proximal of the three distal holes for locking screws. The presence of polyethylene wear debris in the tissue excised from the lesion suggested that it had passed through the cannulated portion of the stem and out of the proximal unfilled distal locking hole, initiating an osteolytic reaction in an otherwise well-fixed stem. This case highlights an important design characteristic of such cannulated, uncemented femoral components. We recommend that the proximal aperture of these cannulated stems be occluded at implantation

Aims. We evaluated a large database with mechanical failure of a single uncemented modular femoral component, used in revision hip arthroplasty, as the end point and compared them to a control group treated with the same implant. Patient- and implant-specific risk factors for implant failure were analyzed. . Methods. All cases of a fractured uncemented modular revision femoral component from one manufacturer until April 2017 were identified and the total number of implants sold until April 2017 was used to calculate the fracture rate. The manufacturer provided data on patient demographics, time to failure, and implant details for all notified fractured devices. Patient- and implant-specific risk factors were evaluated using a logistic regression model with multiple imputations and compared to data from a previously published reference group, where no fractures had been observed. The results of a retrieval analysis of the fractured implants, performed by the manufacturer, were available for evaluation. Results. There were 113 recorded cases with fracture at the modular junction, resulting in a calculated fracture rate of 0.30% (113/37,600). The fracture rate of the implant without signs of improper use was 0.11% (41/37,600). In 79% (89/113) of cases with a failed implant, either a lateralized (high offset) neck segment, an extralong head, or the combination of both were used. Logistic regression analysis revealed male sex, high body mass index (BMI), straight component design, and small neck segments were significant risk factors for failure. Investigation of the implants (76/113) showed at least one sign of improper use in 72 cases. Conclusion. Implant failure at the modular junction is associated with patient- and implant-specific risk factors as well as technical errors during implantation. Whenever possible, the use of short and lateralized neck segments should be avoided with this revision system. Implantation instructions and contraindications need to be adhered to and respected. Cite this article: Bone Joint J 2020;102-B(5):573–579

Aims. The aim of this study was to examine whether hips with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH) have significant asymmetry in femoral length, and to determine potential related factors. Patients and Methods. We enrolled 90 patients (82 female, eight male) with DDH showing unilateral OA changes, and 43 healthy volunteers (26 female, 17 male) as controls. The mean age was 61.8 years (39 to 93) for the DDH groups, and 71.2 years (57 to 84) for the control group. Using a CT-based coordinate measurement system, we evaluated the following vertical distances: top of the greater trochanter to the knee centre (femoral length GT), most medial prominence of the lesser trochanter to the knee centre (femoral length LT), and top of the greater trochanter to the medial prominence of the lesser trochanter (intertrochanteric distance), along with assessments of femoral neck anteversion and neck shaft angle. Results. The percentages of hips with an absolute difference of > 5 mm in femoral GT and LT lengths were significantly larger in the DDH group (24% for both) compared with those of the control group (2% and 7%, respectively). The femoral length GT of the affected femur was significantly shorter in Crowe I and longer in Crowe IV than that of the unaffected side. The affected-to-unaffected difference of the intertrochanteric distance showed positive correlation with that of the femoral length GT in Crowe I and Crowe II/III, and negative correlation with that of the femoral length LT in the Crowe I and Crowe IV groups. Conclusion. Hips with unilateral end-stage OA secondary to DDH show significant asymmetry in femoral length between both the greater and lesser trochanter and the knee compared with controls. The intertrochanteric distance was a morphological factor related to femoral-length asymmetry. When undertaking total hip arthroplasty (THA) in the presence of DDH, long leg radiographs or CT measurements should be used to assess true leg-length discrepancy. Cite this article: Bone Joint J 2019;101-B:297–302

Aims. Injury to the lateral femoral cutaneous nerve (LFCN) is one of the known complications after periacetabular osteotomy (PAO) performed using the anterior approach, reported to occur in between 1.5% and 65% of cases. In this study, we performed a prospective study on the incidence of LFCN injury as well as its clinical outcomes based on the Harris Hip Score (HHS), Short-Form 36 Health Survey (SF-36), and Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). Methods. The study included 42 consecutive hips in 42 patients (three male and 39 female) who underwent PAO from May 2016 to July 2018. We prospectively evaluated the incidence of LFCN injury at ten days, three months, six months, and one year postoperatively. We also evaluated the clinical scores, including the HHS, SF-36, and JHEQ scores, at one year postoperatively. Results. LFCN injury was observed in 31 of 42 (74%) patients at ten days, of which 11 resolved completely by one year. Incidence decreased gradually, to 25 of 42 (60%) patients at three months, 24 of 42 patients (57%) at six months, and 20 of 42 (48%) patients at one year postoperatively. There was no significant difference in the HHS between patients with and without LFCN injury at one year postoperatively. Regarding the SF-36 and JHEQ, a significant difference in the mental score was recognized between patients with and without LFCN injury, but there were no significant differences in the other clinical scores. Conclusion. The incidence of LFCN injury was 74% at ten days after PAO, and subsequently decreased to 48% at one year. LFCN injury did not influence the hip function as assessed by the HHS, but had a negative impact on mental health at one year. Cite this article: Bone Joint J 2021;103-B(4):659–664

Aims. This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA. Methods. Prospectively collected registry data involving 264 UKAs from a single institution were analyzed. The TCCAs and FCCAs were measured on postoperative radiographs and absolute angles were analyzed. Clinical assessment at six months, two years, and ten years was undertaken using the Knee Society Knee score (KSKS) and Knee Society Function score (KSFS), the Oxford Knee Score (OKS), the 36-Item Short-Form Health Survey questionnaire (SF-36), and range of motion (ROM). Fulfilment of expectations and satisfaction was also recorded. Implant survivorship was reviewed at a mean follow-up of 14 years (12 to 16). Multivariate regression models included covariates, TCCA, FCCA, and two-way interactions between them. Partial residual graphs were generated to identify angles associated with the best outcomes. Kaplan-Meier analysis was used to compare implant survivorship between groups. Results. Significant two-way interaction effects between TCCA and FCCA were identified. Adjusted for each other and their interaction, a TCCA of between 2° and 4° and a FCCA of between 0° and 2° were found to be associated with the greatest improvements in knee scores and the probability of fulfilling expectations and satisfaction at ten years. Patients in the optimal group whose TCCA and FCCA were between 2° and 4°, and 0° and 2°, respectively, had a significant survival benefit at 15 years compared with the non-optimal group (optimal: survival = 100% vs non-optimal: survival = 92%, 95% confidence interval (CI) 88% to 96%). Conclusion. Significant two-way interactions between the TCCA and FCCA demonstrate the importance of evaluating the alignment of the components concomitantly in future studies. By doing so, we found that patients who concomitantly had both a TCCA of between 2° and 4° and a FCCA of between 0° and 2° had the best patient-reported outcome measures at ten years and better survivorship at 15 years. Cite this article: Bone Joint J 2021;103-B(2):338–346

Aims. In patients where the proximal femur shows gross deformity due to degenerative changes or fracture, the contralateral femur is often used to perform preoperative templating for hip arthroplasty. However, femurs may not be symmetrical: the aim of this study was to determine the degree of variation between hips in healthy individuals and to determine whether it is affected by demographic parameters. Materials and Methods. CT-scan based modelling was used to examine the pelvis and bilateral femurs of 345 patients (211 males, 134 women; mean age 62 years (standard deviation (. sd). 17), mean body mass index 27 kg/m. 2. (. sd. 5)) representing a range of ethnicities. The femoral neck-shaft angle (NSA), femoral offset (FO), femoral neck version (FNV), femoral length (FL), femoral canal flare index (fCFI), and femoral head radius (FHr) were then determined for each patient. All measurements were constructed using algorithm-calculated landmarks, resulting in reproducible and consistent constructs for each specimen. We then analyzed femoral symmetry based on absolute differences (AD) and percentage asymmetry (%AS) following a previously validated method. Results. We found an asymmetry > 2% for NSA (mean AD 2.9°, mean %AS 2.3; p = 0.03), FO (AD 3.8 mm, %AS 9.1 ; p = 0.01), FNV (AD 5.1°, %AS 46.7 ; p = 0.001) and fCFI (AD 0.2 mm, %AS 5.4 ; p = 0.7). Significant relationships were found for AD regarding NSA and ethnicity (p = 0.037), FL and height (R. 2.  = 0.22), and fCFI and gender (R. 2.  = 0.34). Conclusion. Our data confirm the presence of asymmetry of proximal femurs, which is mostly independent of demographic parameters. In cases where contralateral templating is used, such asymmetry may lead to inaccurate anatomical restoration of the hip if the templated sizes are routinely implanted. However, the clinical impact cannot be determined from our investigation. Cite this article: Bone Joint J 2018;100-B:839–44

Aims. Compared with primary total hip arthroplasty (THA), revision surgery can be challenging. The cement-in-cement femoral revision technique involves removing a femoral component from a well-fixed femoral cement mantle and cementing a new stem into the original mantle. This technique is widely used and when carried out for the correct indications, is fast, relatively inexpensive and carries a reduced short-term risk for the patient compared with the alternative of removing well-fixed cement. We report the outcomes of this procedure when two commonly used femoral stems are used. Patients and Methods. We identified 1179 cement-in-cement stem revisions involving an Exeter or a Lubinus stem reported to the Swedish Hip Arthroplasty Register (SHAR) between January 1999 and December 2015. Kaplan-Meier survival analysis was performed. Results. Survivorship is reported up to six years and was better in the Exeter group (91% standard deviation (. sd). 2.8% versus 85% . sd. 5.0%) (p = 0.02). There was, however, no significant difference in the survival of the stem and risk of re-revision for any reason (p = 0.58) and for aseptic loosening (p = 0.97), between revisions in which the Exeter stem (94% . sd. 2.2%; 98% . sd. 1.6%) was used compared with those in which the Lubinus stem (95% . sd. 3.2%; 98% . sd.  2.2%) was used. The database did not allow identification of whether a further revision was indicated for loosening of the acetabular or femoral component or both. Conclusion. The cement-in-cement technique for revision of the femoral component gave promising results using both designs of stem, six years post-operatively. Cite this article: Bone Joint J 2017;99-B(4 Supple B):27–32

We performed a retrospective analysis of the clinical and radiological outcomes of total hip replacement using an uncemented femoral component proximally coated with hydroxyapatite. Of 136 patients, 118 who had undergone 124 primary total hip replacements were available for study. Their mean age was 66.5 years (19 to 90) and the mean follow-up was 5.6 years (4.25 to 7.25). At the final follow-up the mean Harris hip score was 92 (47.7 to 100). Periprosthetic femoral fractures, which occurred in seven patients (5.6%), were treated by osteosynthesis in six and conservatively in one. We had to revise five femoral components, one because of aseptic loosening, one because of septic loosening and three because of periprosthetic fracture. At the final follow-up there were definite signs of aseptic loosening in two patients. Radiologically, proximal femoral bone loss in Gruen zones I and VI was evident in 96.8% of hips, while bone hypertrophy in zones III and V was seen in 64.7%. In 24 hips (20.2%) the mean subsidence of the stem was 3.7 mm which occurred within the first 12 postoperative weeks. This indicated poor initial stability, which might have been aggravated by early weight-bearing. The high rate of failure in our study suggests that proximal femoral bone loss affects the long-term survival of the replacement

Aims. The aim of this study was to describe the epidemiology of closed isolated fractures of the femoral shaft in children, and to compare the treatment and length of stay (LOS) between major trauma centres (MTCs) and trauma units (TUs) in England. Patients and Methods. National data were obtained from the Trauma and Audit Research Network for all isolated, closed fractures of the femoral shaft in children from birth to 15 years of age, between 2012 and 2015. Age, gender, the season in which the fracture occurred, non-accidental injury, the mechanism of injury, hospital trauma status, LOS and type of treatment were recorded. Results. A total of 1852 fractures were identified. The mean annual incidence was 5.82 per 100 000 children (95% confidence interval (CI) 5.20 to 6.44). The age of peak incidence was two years for both boys and girls; this decreased with increasing age. Children aged four to six years treated in MTCs were more likely to be managed with open reduction and internal fixation compared with those treated in TUs (odds ratio 3.20; 95% CI 1.12 to 9.14; p = 0.03). The median LOS was significantly less in MTCs than in TUs for children aged between 18 months and three years treated in both a spica (p = 0.005) and traction (p = 0.0004). . Conclusion. This study highlights the current national trends in the management of closed isolated fractures of the femoral shaft in children following activation of major trauma networks in 2012. Future studies focusing on the reasons for the differences which have been identified may help to achieve more consistency in the management of these injuries across the trauma networks. Cite this article: Bone Joint J 2018;100-B:109–18

Aims. We previously reported the long-term results of the cementless Duraloc-Profile total hip arthroplasty (THA) system in a 12- to 15-year follow-up study. In this paper, we provide an update on the clinical and radiological results of a previously reported cohort of patients at 23 to 26 years´ follow-up. Patients and Methods. Of the 99 original patients (111 hips), 73 patients (82 hips) with a mean age of 56.8 years (21 to 70) were available for clinical and radiological study at a minimum follow-up of 23 years. There were 40 female patients (44 hips) and 33 male patients (38 hips). Results. All acetabular and femoral components were well fixed and showed signs of bone ingrowth. Nine acetabular components were revised due to wear-osteolysis-related problems and four due to late dislocation. The probability of not having component revision at 25 years was 83.2% (95% confidence interval (CI) 74.5 to 91.8; number at risk 41). Acetabular osteolysis was observed in ten hips. The mean femoral head penetration was 1.52 mm (. sd. 0.8) at 15 years and 1.92 mm (. sd. 1.2) at 25 years. Receiver operating characteristic (ROC) analysis revealed that mean femoral penetration with a value of 0.11 mm/year or more was associated with the appearance of osteolysis. The 25-year Kaplan–Meier survival with different endpoints was 89.9% for acetabular osteolysis (95% CI 83.3 to 96.5), 92.1% for proximal femoral osteolysis (95% CI 86.1 to 98.2), and 75.5% for femoral osteopenia (95% CI 66.5 to 84.5). Conclusion. The Duraloc-Profile THA system showed excellent long-term bone fixation. Nevertheless, monitoring is recommended in order to detect wear and late dislocations in this population that was relatively young at the time of surgery. Cite this article: Bone Joint J 2019;101-B:378–385

Aims. There is a paucity of long-term studies analyzing risk factors for failure after single-stage revision for periprosthetic joint infection (PJI) following total hip arthroplasty (THA). We report the mid- to long-term septic and non-septic failure rate of single-stage revision for PJI after THA. Methods. We retrospectively reviewed 88 cases which met the Musculoskeletal Infection Society (MSIS) criteria for PJI. Mean follow-up was seven years (1 to 14). Septic failure was diagnosed with a Delphi-based consensus definition. Any reoperation for mechanical causes in the absence of evidence of infection was considered as non-septic failure. A competing risk regression model was used to evaluate factors associated with septic and non-septic failures. A Kaplan-Meier estimate was used to analyze mortality. Results. The cumulative incidence of septic failure was 8% (95% confidence interval (CI) 3.5 to 15) at one year, 13.8% (95% CI 7.6 to 22) at two years, and 19.7% (95% CI 12 to 28.6) at five and ten years of follow-up. A femoral bone defect worse than Paprosky IIIA (hazard ratio (HR) 13.58 (95% CI 4.86 to 37.93); p < 0.001) and obesity (BMI ≥ 30 kg/m. 2. ; HR 3.88 (95% CI 1.49 to 10.09); p = 0.005) were significantly associated with septic failure. Instability and periprosthetic fracture were the most common reasons for mechanical failure (5.7% and 4.5%, respectively). The cumulative incidence of aseptic failure was 2% (95% CI 0.4 to 7) at two years, 9% (95% CI 4 to 17) at five years, and 12% (95% CI 5 to 22) at ten years. A previous revision to treat PJI was significantly associated with non-septic failure (HR 9.93 (95% CI 1.77 to 55.46); p = 0.009). At the five-year timepoint, 93% of the patients were alive (95% CI 84% to 96%), which fell to 86% (95% CI 75% to 92%) at ten-year follow-up. Conclusion. Massive femoral bone loss was associated with greater chances of developing a further septic failure. All septic failures occurred within the first five years following the one-stage exchange. Surgeons should be aware of instability and periprosthetic fracture being potential causes of further aseptic revision surgery. Cite this article: Bone Joint J 2021;103-B(7):1247–1253

Aims. Femoral impaction bone grafting was first developed in 1987 using morselised cancellous bone graft impacted into the femoral canal in combination with a cemented, tapered, polished stem. We describe the evolution of this technique and instrumentation since that time. . Patients and Methods. Between 1987 and 2005, 705 revision total hip arthroplasties (56 bilateral) were performed with femoral impaction grafting using a cemented femoral stem. All surviving patients were prospectively followed for a mean of 14.7 years (9.8 to 28.3) with no loss to follow-up. By the time of the final review, 404 patients had died. Results. There were 76 further revisions (10.8%) involving the stem; seven for aseptic loosening, 23 for periprosthetic fracture, 24 for infection, one for malposition, one for fracture of the stem and 19 cement-in-cement exchanges of the stem during acetabular revision. The 20-year survival rate for the entire series was 98.8% (95% confidence interval (CI) 97.8 to 99.8) with aseptic loosening as the endpoint, and 87.7% (95% CI 82.8 to 92.6) for revision for any reason. Survival improved with the evolution of the technique, although this was not statistically significant due to the overall low rate of further revision. Conclusion. This is the largest series of revision total hip arthroplasties with femoral impaction grafting, and the results support the continued use of this technique. Cite this article: Bone Joint J 2016;98-B:1611–19

Aims. Patients undergoing femoral lengthening by external fixation tolerate treatment less well when compared to tibial lengthening. Lengthening of the femur with an intramedullary device may have advantages. Patients and Methods. We reviewed all cases of simple femoral lengthening performed at our unit from 2009 to 2014. Cases of nonunions, concurrent deformities, congenital limb deficiencies and lengthening with an unstable hip were excluded, leaving 33 cases (in 22 patients; 11 patients had bilateral procedures) for review. Healing index, implant tolerance and complications were compared. Results. In 20 cases (15 patients) the Precice lengthening nail was used and in 13 cases (seven patients) the LRS external fixator system. The desired length was achieved in all cases in the Precice group and in 12 of 13 cases in the LRS group. The mean healing index was 31.3 days/cm in the Precice and 47.1 days/cm in the LRS group (p < 0.001). This was associated with an earlier ability to bear full weight without aids in the Precice group. There were more complications with LRS lengthening, including pin site infections and regenerate deformity. Implant tolerance and the patients’ perception of the cosmetic result were better with the Precice treatment. Conclusion. Femoral lengthening with the Precice femoral nail achieved excellent functional results with fewer complications and greater patient satisfaction when compared with the LRS system in our patients. Cite this article: Bone Joint J 2016;98-B:1382–8

Aims. The aim of this study was to describe, analyze, and compare the survival, functional outcome, and complications of minimally invasive (MI) and non-invasive (NI) lengthening total femoral prostheses. Patients and Methods. A total of 24 lengthening total femoral prostheses, 11 MI and 13 NI, were implanted between 1991 and 2016. The characteristics, complications, and functional results were recorded. There were ten female patients and ten male patients. Their mean age at the time of surgery was 11 years (2 to 41). The mean follow-up was 13.2 years (seven months to 29.25 years). A survival analysis was performed, and the failures were classified according to the Modified Henderson System. Results. The overall implant survival was 79% at five, ten, and 20 years for MI prostheses, and 84% at five years and 70% at ten years for NI prostheses. At the final follow-up, 13 prostheses did not require further surgery. The overall complication rate was 46%. The mean revision-free implant survival for MI and NI prostheses was 59 months and 49 months, respectively. There were no statistically significant differences in the overall implant survival, revision-free survival, or the distribution of complications between the two types of prosthesis. Infection rates were also comparable in the groups (9% vs 7%; p = 0.902). The rate of leg-length discrepancy was 54% in MI prostheses and 23% in NI prostheses. In those with a MI prosthesis, there was a smaller mean range of movement of the knee (0° to 62° vs 0° to 83°; p = 0.047), the flexion contracture took a longer mean time to resolve after lengthening (3.3 months vs 1.07 months; p < 0.001) and there was a lower mean Musculoskeletal Tumor Society (MSTS) score (24.7 vs 27; p = 0.295). Conclusion. The survival and complications of MI and NI lengthening total femoral prostheses are comparable. However, patients with NI prosthesis have more accurate correction of leg-length discrepancy, a better range of movement of the knee and an improved overall function

Aims. Although good clinical outcomes have been reported for monolithic tapered, fluted, titanium stems (TFTS), early results showed high rates of subsidence. Advances in stem design may mitigate these concerns. This study reports on the use of a current monolithic TFTS for a variety of indications. Methods. A multi-institutional retrospective study of all consecutive total hip arthroplasty (THA) and revision total hip arthroplasty (rTHA) patients who received the monolithic TFTS was conducted. Surgery was performed by eight fellowship-trained arthroplasty surgeons at four institutions. A total of 157 hips in 153 patients at a mean follow-up of 11.6 months (SD7.8) were included. Mean patient age at the time of surgery was 67.4 years (SD 13.3) and mean body mass index (BMI) was 28.9 kg/m. 2. (SD 6.5). Outcomes included intraoperative complications, one-year all-cause re-revisions, and subsidence at postoperative time intervals (two weeks, six weeks, six months, nine months, and one year). Results. There were eight intraoperative complications (4.9%), six of which were intraoperative fractures; none occurred during stem insertion. Six hips (3.7%) underwent re-revision within one year; only one procedure involved removal of the prosthesis due to infection. Mean total subsidence at latest follow-up was 1.64 mm (SD 2.47). Overall, 17 of 144 stems (11.8%) on which measurements could be performed had >5 mm of subsidence, and 3/144 (2.1%) had >10 mm of subsidence within one year. A univariate regression analysis found that additional subsidence after three months was minimal. A multivariate regression analysis found that subsidence was not significantly associated with periprosthetic fracture as an indication for surgery, the presence of an extended trochanteric osteotomy (ETO), Paprosky classification of femoral bone loss, stem length, or type of procedure performed (i.e. full revision vs conversion/primary). Conclusion. Advances in implant design, improved trials, a range of stem lengths and diameters, and high offset options mitigate concerns of early subsidence and dislocation with monolithic TFTS, making them a valuable option for femoral revision. Cite this article: Bone Joint J 2020;102-B(2):191–197

Aims. Abnormal femoral torsion (FT) is increasingly recognized as an additional cause for femoroacetabular impingement (FAI). It is unknown if in-toeing of the foot is a specific diagnostic sign for increased FT in patients with symptomatic FAI. The aims of this study were to determine: 1) the prevalence and diagnostic accuracy of in-toeing to detect increased FT; 2) if foot progression angle (FPA) and tibial torsion (TT) are different among patients with abnormal FT; and 3) if FPA correlates with FT. Patients and Methods. A retrospective, institutional review board (IRB)-approved, controlled study of 85 symptomatic patients (148 hips) with FAI or hip dysplasia was performed in the gait laboratory. All patients had a measurement of FT (pelvic CT scan), TT (CT scan), and FPA (optical motion capture system). We allocated all patients to three groups with decreased FT (< 10°, 37 hips), increased FT (> 25°, 61 hips), and normal FT (10° to 25°, 50 hips). Cluster analysis was performed. Results. We found a specificity of 99%, positive predictive value (PPV) of 93%, and sensitivity of 23% for in-toeing (FPA < 0°) to detect increased FT > 25°. Most of the hips with normal or decreased FT had no in-toeing (false-positive rate of 1%). Patients with increased FT had significantly (p < 0.001) more in-toeing than patients with decreased FT. The majority of the patients (77%) with increased FT walk with a normal foot position. The correlation between FPA and FT was significant (r = 0.404, p < 0.001). Five cluster groups were identified. Conclusion. In-toeing has a high specificity and high PPV to detect increased FT, but increased FT can be missed because of the low sensitivity and high false-negative rate. These results can be used for diagnosis of abnormal FT in patients with FAI or hip dysplasia undergoing hip arthroscopy or femoral derotation osteotomy. However, most of the patients with increased FT walk with a normal foot position. This can lead to underestimation or misdiagnosis of abnormal FT. We recommend measuring FT with CT/MRI scans in all patients with FAI. Cite this article: Bone Joint J 2019;101-B:1218–1229

Aims

Periprosthetic hip fractures (PPFs) after total hip arthroplasty are difficult to treat. Therefore, it is important to identify modifiable risk factors such as stem selection to reduce the occurrence of PPFs. This study aimed to clarify differences in fracture torque, surface strain, and fracture type analysis between three different types of cemented stems.

Aims. The morphometry of the distal femur was largely studied to improve bone-implant fit in total knee arthroplasty (TKA), but little is known about the asymmetry of the posterior condyles. This study aimed to investigate the dimensions of the posterior condyles and the influence of externally rotating the femoral component on potential prosthetic overhang or under-coverage. Patients and Methods. We analysed the shape of 110 arthritic knees at the time of primary TKA using pre-operative CT scans. The height and width of each condyle were measured at the posterior femoral cut in neutral position, and in 3º and 5º of external rotation, using both central and medial referencing systems. We compared the morphological characteristics with those of 14 TKA models. Results. In the neutral position, the dimensions of the condyles were nearly equal. Externally rotating the femoral cut by 3º and 5º with ‘central referencing’ induced width asymmetry >  3 mm in 23 (21%) and 33 (30%) knees respectively, while with ‘medial referencing’ it induced width asymmetry > 3 mm in 43 (39%) and 75 (68%) knees respectively. The asymmetries induced by rotations were not associated with gender, aetiology or varus-valgus alignment. Conclusion. External rotation may amplify the asymmetry between the medial and lateral condyles, and exacerbate prosthetic overhang, particularly in the superolateral zone. ‘Central referencing’ guides result in less potential prosthetic overhang than ‘medial referencing’ guides. Cite this article: Bone Joint J 2017;99-B:894–903

Aims. The aim of this study was to compare the design of the generic OptiStem XTR femoral stem with the established Exeter femoral stem. Materials and Methods. We obtained five boxed, as manufactured, implants of both designs at random (ten in total). Two examiners were blinded to the implant design and independently measured the mass, volume, trunnion surface topography, trunnion roughness, trunnion cone angle, Caput-Collum-Diaphyseal (CCD) angle, femoral offset, stem length, neck length, and the width and roughness of the polished stem shaft using peer-reviewed methods. We then compared the stems using these parameters. Results. We found that the OptiStems were lighter (p < 0.001), had a rougher trunnion surface (p <  0.001) with a greater spacing and depth of the machined threads (p < 0.001), had greater trunnion cone angles (p = 0.007), and a smaller radius at the top of the trunnion (p = 0.007). There was no difference in stem volume (p = 0.643), CCD angle (p = 0.788), offset (p = 0.993), neck length (p = 0.344), stem length (p = 0.808), shaft width (p = 0.058 to 0.720) or roughness of the polished surface (p = 0.536). Conclusion. This preliminary investigation found that whilst there were similarities between the two designs, the generic OptiStem is different to the branded Exeter design. Cite this article: Bone Joint J 2017;99-B:310–16