Introduction. Limb-length discrepancy (LLD) is a common postoperative complication after total hip arthroplasty (THA). This study focuses on the correlation between patients’ perception of LLD after THA and the anatomical and functional leg length, pelvic and knee alignments and foot height. Previous publications have explored this topic in patients without significant spinal pathology or previous spine or lower extremity surgery. The objective of this work is to verify if the results are the same in case of stiff or fused spine. Methods. 170 patients with stiff spine (less than 10° L1-S1 lordosis variation between standing and sitting) were evaluated minimum 1 year after unilateral primary THA implantation using EOS® images in standing position (46/170 had previous lumbar fusion). We excluded cases with previous lower limbs surgery or frontal and sagittal spinal imbalance. 3D measures were performed to evaluate femoral and tibial length, femoral offset, pelvic obliquity, hip-knee-ankle angle (HKA), knee flexion/hyperextension angle, tibial and femoral rotation. Axial pelvic rotation was measured as the angle between the line through the centers of the hips and the EOS x-ray beam source. The distance between middle of the tibial plafond and the ground was used to investigate the height of the foot. For data with normal distribution, paired Student's t-test and independent sample t-test were used for analysis. Univariate logistic regression was used to determine the correlation between the perception of limb length discrepancy and different variables. Multiple logistic regression was used to investigate the correlation between the patient perception of LLD and variables found significant in the univariate analysis. Significance level was set at 0.05. Results. Anatomical femoral length correlated with patients’ perception of LLD but other variables were significant (the height of the foot, sagittal and frontal knee alignment, pelvic obliquity and pelvic rotation more than 10°). Interestingly some factors induced an unexpected perception of LLD despite a non-significant femoral length discrepancy less than 1cm (pelvic rotation and obliquity, height of the foot). Conclusions. LLD is a multifactorial problem. This study showed that the anatomical femoral length as the factor that can be modified with THA technique or choice of prosthesis is not the only important factor. A comprehensive clinical and radiological evaluation is necessary preoperatively to investigate spinal stiffness, pelvic obliquity and rotation, sagittal and coronal knee alignment and foot deformity in these patients. Our study has limitations as we do not have preoperative EOS measurements for all patients. We cannot assess changes in leg length as a result of THA. We also did not investigate the degree of any foot deformities as flat foot deformity may potentially affect the patients perception of the leg length. Instead, we measured the distance between the medial malleolus and ground that can reflect the foot arch height. More cases must be included to evaluate the potential influence of pelvis anatomy and functional orientation (pelvic incidence, sacral slope and pelvic tilt) but this study points out that spinal stiffness significantly decreases the LLD tolerance previously reported in patients without degenerative stiffness or fusion

Introduction. Leg length discrepancy (LLD) in patients with unilateral developmental dysplasia of the hip (DDH) can be problematic for both patients and surgeons. Patients can acquire gait asymmetry, back pain, and arthritis. Surgical considerations include timing of correction and arthroplasty planning. This study audits standing long leg films performed at skeletal maturity in our patients. The aim of this study is to identify if surgical procedure or AVN type could predict the odds of needing an LLD Intervention (LLDI) and influence our surveillance. Materials and Methods. Hospital database was searched for all patients diagnosed with DDH. Inclusion criteria were patients with appropriately performed long leg films at skeletal maturity. Exclusion criteria were patients with non DDH pathology, skeletally immature and inadequate radiographs. All data was tabulated in excel and SPSS was used for analysis. Traumacad was used for measurements and AVN and radiologic outcome grades were independently classified in duplicate. Results. 110 patients were identified. The mean age of follow-up was 15 years with final average LLD of 1mm(±5mm). The DDH leg tended to be longer and length primarily in the femur. 31(28.2%) patients required an LLDI. 19 Patients had a final LLD >1.5cm. There was no statistical significant difference in the odds of needing an LLDI by type of surgical procedure or AVN. AVN type 4 was associated with greatest odds of intervention. The DDH leg was more likely to require ipsilateral epiphysiodesis or contralateral lengthening in Type 1 and 2 AVN. Conclusions. The DDH leg tends to be longer, leg lengths should be monitored, and leg length interventions are frequently required irrespective of previous DDH surgical procedure or the presence of AVN

Introduction. While THA is associated with positive results and long-term improvement in patient quality of life, outcomes are nonetheless associated with adverse events and post-procedural deficits related to discrepancies in leg length (LLD), offset and cup placement. Post-THA errors in these parameters are associated with gait alteration, low back pain and patient dissatisfaction. Such discrepancies often necessitate revision and increasingly lead to medical malpractice litigation. Maintaining accuracy in post-surgical leg length, offset and cup placement during THA is difficult and subject to error. The sensitivity of these factors is highlighted in studies that have shown that a change of as little as 5 degrees of flexion or abduction can induce alterations in leg length of up to several millimeters. Similarly, positioning of implants can alter global and femoral offset, affecting abductor strength, range of motion and overall physical function. Compounding the biochemical issues associated with inaccurate leg length are the costs associated with these deficits. Traditional freehand techniques of managing intra-operative parameters rely on surgeon experience and tissue tensioning to manually place components accurately. These methods, however, are only able to assess leg length and are subject to inaccuracies associated with patient movement or orientation changes during surgery. Mechanical methods of minimizing post-surgical discrepancies have been developed, such as outrigger or caliper devices, although these methods also address leg length only and provide poor feedback regarding offset and center of rotation, therefore providing insufficient data to accurately achieve appropriate post-surgical leg length. Computer-assisted navigation methods provide more data regarding leg length, offset and center of rotation, but are limited by their cumbersome nature and the large capital costs associated with the systems. The Intellijoint HIP. ®. surgical smart tool (Intellijoint Surgical, Inc., Waterloo, ON) is an intra-operative guidance tool that provides surgeons with real time data on leg length, offset and center of rotation, thereby allowing for confident selection of the correct implant in order to ensure appropriate post-surgical biomechanics. The early clinical results from an initial cohort of patients indicate that Intellijoint HIP. ®. is safe and effective. No adverse events were reported in the initial cohort, and the smart tool was able to measure surgical parameters to within 1mm when compared to radiographic measurements. With training cases removed, 100% of cases had a post-procedure leg length discrepancy of less than 5mm. This paper describes the indications, procedural technique and early clinical results of the Intellijoint HIP. ®. smart tool, which offers a safe, accurate and easy-to-use option for hip surgeons to manage leg length, offset and cup position intra-operatively

Objective. Open-wedge high tibial osteotomy (OWHTO) involves performing a corrective osteotomy of the proximal tibia and removing a wedge of bone to correct varus alignment. Although previous studies have investigated changes in leg length before and after OWHTO using X-rays, none has evaluated three-dimensional (3D) leg length changes after OWHTO. We therefore used 3D preoperative planning software to evaluate changes in leg length after OWHTO in three dimensions. Methods. The study subjects were 55 knees of 46 patients (10 men and 36 women of mean age 69.9 years) with medial osteoarthritis of the knee or osteonecrosis of the medial femoral condyle with a femorotibial angle of >185º and restricted range of motion (extension <–10º, flexion <130º), excluding those also suffering from patellofemoral arthritis or lateral osteoarthritis of the knee. OWHTO was simulated from computed tomography scans of the whole leg using ZedHTO 3D preoperative planning software. We analyzed the hip-knee-ankle angle (HKA), flexion contracture angle (FCA), mechanical medial proximal tibial angle (mMPTA), angle of correction, wedge length, 3D tibial length, 3D leg length, and 3D increase in leg length before and after OWHTO. We also performed univariate and multivariate analysis of factors affecting the change in leg length (preoperative and postoperative H-K-A angle, wedge length, and correction angle). Results. Mean HKA increased significantly from −4.7º ± 2.7º to 3.5º ± 1.3º, as did mean mMPTA from 83.7º ± 3.3º to 92.5º ± 3.0º (p <0.01). Mean FCA was 4.7º ± 3.6° preoperatively and 4.8º ± 3.3º postoperatively, a difference that was not significant (p = 0.725). The mean correction angle was 9.1º ± 2.8º and the mean wedge length was 9.4º ± 3.2º mm. Mean tibial length increased significantly by 4.7 ± 2.3 mm (p <0.01), and mean leg length by 5.6 ± 2.8 mm (p <0.01). The change in leg length was strongly correlated with wedge length (R = 0.846, adjusted R. 2. = 0.711, p <0.01). Discussion and Conclusion. Mean 3D leg length after OWHTO increased significantly by 5.4 ± 3.1 mm. A difference in leg length of >5 mm is believed to affect back pain and gait abnormalities, and changes in leg length must therefore be taken into consideration. The 3D dimensional change in leg length was strongly correlated with wedge length, and could be predicted by the formula (change in leg length in mm) = [(wedge length in mm) ×0.75) − 1.5]. For any figures or tables, please contact authors directly

Leg length inequality, both actual and functional, is the most important cause of disappointment for the surgeon and his patient. The reported incidence of leg length inequality of 1 cm has been reported to be between 23% and 50%, and half of these patients require a lift in their shoe. In the author’s opinion, there is a relationship between leg length and stability of the hip. Increase in leg length and offset improves soft tissue tension and reduces the dislocation rate. The goal at surgery is:. To restore the center of rotation for the hip. To restore offset, i.e. abductor moment arm. To restore hip center to lesser trochanter difference. The various tests for hip stability, soft tissue tension and contractures:. Assess component position. Assess for anterior impingement. Assess for tight anterior capsule. Assess for tight iliotibial band (Ober’s test). Assess for tight rectus, iliopsoas and adductors. Correct soft tissue balance. Leg length inequality is caused by:. Increase in anatomic leg length or offset or both. Tight anterolateral structures, which include:. IT band. Anterior and lateral capsule and gluteus maximus. Adduction contractures of the opposite hip. Spinal deformity causing pelvic tilt. Excessive trochanteric advancement causing abduction contracture

Typical devices to limit leg length changes rely on a fixed point in the ileum and femur in order to measure leg length changes intraoperatively. The aim of this study is to determine the ideal position for placement of these devices and to identify potential sources of error. Using saw bones the leg length device was attached at four different positions along the iliac crest extending from the ASIS to its midpoint. After marking the femur on the lateral edge of the Greater Trochanter, measurements were taken with gradually increasing leg length from each individual position on the ileum. This was also performed for different degrees of hip flexion. It was determined that when the hip was in an extended position the degree of error was small for all positions along the iliac crest, with a tendency for an increase error the closer the pin is to the ASIS. When the hip is flexed the error is increased with pin positions closer to the ASIS. With a lengthening of 10 mm, minimal leg length changes can be determined using the device. More than 20 mm resulted in significant change using the leg length device. Ideal iliac crest pin position is towards the midpoint of the iliac crest, which will minimise the potential error. Measuring the leg length while the hip is in a neutral position will limit the error and increase the accuracy—thus avoiding unwanted lengthening

Introduction. Leg length discrepancy is a significant concern after total hip replacement (THR). We hypothesised that the intra-operative use of a navigation system was able to accurately control the leg length during THR. Material. 50 cases have been prospectively analysed. There were 29 men and 21 women, with a mean age of 66.1 years (range, 50 to 80 years), all operated on for THR for end-stage hip osteoarthritis. Methods. All procedures were performed with a non-image based navigation system. The expected correction of the leg length was defined prior to the procedure. The leg length was recorded before any bone resection by the 3D-distance between the pelvic and the femoral navigation trackers when placing the operated leg in a position near the anatomic one. The THR was performed according to the indication of the navigation system. The vertical positioning of the femoral component and the length of the prosthetic neck were defined to achieve the expected planning; however a correction was allowed to compensate for excessive muscular tension or risk of prosthetic instability according to the surgeon's judgment. The final leg length was recorded with the same technique as previously, with an accurate control of the repositioning of the limb in the 3D space by the navigation system. The length variation before and after THR measured by the navigation system was compared to the planning and to a conventional radiographic measurement on plain, standing pelvic X-rays with a Wilcoxon test at a 5% level of significance. The linear correlation coefficient between the different techniques was calculated. The agreement between the different techniques was assessed according to Bland-Altman. Results. The mean planned leg length change was 7.1 ± 6.1 mm. The mean leg length variation was 9.7 ± 4.2 mm as measured by the navigation system, and 11.0 ± 9.2 mm as measured on plain X-rays. The expected goal was achieved within 5 mm for 45 patients (90%). There was no significant difference between paired navigated and radiographic measurements (p=0.46). There was no significant difference between the planning variation and the navigated measurements (p=0.15). There was a good correlation between the planning variation and the navigated measurements (R. 2. =0.59, p<0.001). There was a good coherence between the planning variation and the navigated measurements. Discussion. The hypothesis of the current study was confirmed. The navigation system used in the current study was able to control very accurately the leg length change during THR. This technique of measurements may be more accurate and more precise than any conventional technique of intra-operative leg length control. The incidence of changes in the implant size or position can be easily detected, and the best compromise may be chosen intra-operatively

Summary. The mathematical model has proven to be highly accurate in measuring leg length before and after surgery to determine how leg length effects hip joint mechanics. Introduction. Leg length discrepancy (LLD) has been proven to be one of the most concerning problems associated with total hip arthroplasty (THA). Long-term follow-up studies have documented the presence of LLD having direct correlation with patient dissatisfaction, dislocation, back pain, and early complications. Several researchers sought to minimize limb length discrepancy based on pre-operative radiological templating or intra-operative measurements. While often being a common occurrence in clinical practice to compensate for LLD intra-operatively, the center of rotation of the hip joint has often changes unintentionally due to excessive reaming. Therefore, the clinical importance of LLD is still difficult to solve and remains a concern for clinicians. Objective. The objective of this study is two-fold: (1) use a validated forward-solution hip model to theoretically analyze the effects of LLD, gaining better understanding of mechanisms leading to early complication of THA and poor patient satisfaction and (2) to investigate the effect of the altered center of rotation of the hip joint regardless LLD compensation. Methods. The theoretical mathematical model used in this study has been previously validated using fluoroscopic results from existing implant designs and telemetric devices. The model can be used to theoretically investigate various surgical alignments, approaches, and procedures. In this study, we analyzed LLD and the effects of the altered center of rotation regardless of LLD compensation surgeons made. The simulations were conducted in both swing and stance phase of gait. Results. During swing phase, leg shortening lead to loosening of the hip capsular ligaments and subsequently, variable kinematic patterns. The momentum of the lower leg increased to levels where the ligaments could not properly constrain the hip leading to the femoral head sliding from within the acetabular cup (Figure 1). This piston motion led to decreased contact area and increased contact stress within the cup. Leg lengthening did not yield femoral head sliding but increased joint tension and contact stress. A tight hip may be an influential factor leading to back pain and poor patient satisfaction. During stance phase, leg shortening caused femoral head sliding leading to decreased contact area and an increase in contact stress. Leg lengthening caused an increase in capsular ligaments tension leading to higher stress in the hip joint (Figure 2). Interestingly, when the acetabular cup was superiorized and the surgeon compensated for LLD, thus matching the pre-operative leg length by increasing the neck length of the femoral implant, the contact forces and stresses were marginally increased at heel strike (Figure 3). Conclusion and Discussion. Altering the leg length during surgery can lead to higher contact forces and contact stresses due to tightening the hip joint or increasing likelihood of hip joint separation. Leg shortening often lead to higher stress within the joint. Further assessment must be conducted to develop tools that surgeons can use to ensure post-operative leg length is similar to the pre-operative condition. For any figures or tables, please contact authors directly

Introduction: Leg length inequality (LLI) following arthroplasty, though often asymptomatic, can be cause for considerable morbidity and has increasing medicolegal consequences. There are various methods of quantifying leg length inequality on plain AP radiograph. The aim of this study is to review the established practice in the measurement of leg length inequality and compare it to two methods used locally. Methods: This is a retrospective study assessing the radiographs of 35 patients with a mix of native, unilateral and bilateral total hip arthroplasty. Two methods of measuring leg length inequality were prominent in the literature, the Woolson method and the Williamson method. A further two methods are used locally. Measurements for all four techniques were made by two senior consultant radiologist to on the trust PACS to assess inter and intra observer variability. Data analysis was performed using SPS 16 to produce intraclass correlation co-efficient (ICC) and Bland Altman plots. Results: ICC for all methods in the measurement of LLI is excellent (≥0.90). The repeatability ICC for the four methods is; Woolson 0.65, Williamson 0.87, Direct 0.96 and the Leeds method 0.95. Discussion: This study demonstrates that all four methods have excellent correlation; however the repeatability is better for the Direct and the Leeds methods than the two that are more widely used in the literature. While the Direct measurement is able to give an overall measurement for the leg length inequality, the Leeds method is able to distinguish between any inequality due to cup malpostion and stem malposition. It is therefore of particular value in the assessment of bilateral or revision arthroplasty and the audit of practice

Introduction:. High tibial osteotomy (HTO) is a common treatment for medial compartment arthritis of the knee in younger, more active patients. The HTO shifts load away from the degenerative medial compartment and into the lateral compartment. This change can be accomplished with either a lateral closing or a medial opening wedge HTO. An HTO also potentially affects leg length. Mathematical models predict that the osteotomy type (opening versus closing) and the magnitude of the correction determine the change in leg length, but no in vivo studies have been published. The purpose of this study is to quantify and compare leg length change following opening and closing wedge HTO. Study Design:. Retrospective cohort study – Level III evidence. Methods:. Thirty-two medial opening and 32 lateral closing HTO's were selected from patients treated at our institution between 2006 and 2009. Pre-operative and one-year post-operative full-length lower extremity radiographs were obtained along with operative reports. Pre- and post-operative coronal plane alignment and leg length were measured and surgical details were collected. Results:. The 64 osteotomies were performed in 62 patients (43 male, 19 female) at an average age of 57 years. The mean opening wedge was 9.3 mm (range: 5 to 17 mm) and the mean closing wedge was 8.0 mm (range: 6 to 10 mm). Knee alignment changed from a mean of 174 degrees pre-operatively to a mean of 183 degrees post-operatively in both groups. In the medial opening wedge group, total leg length was found to increase from 836.3 ± 63.5 mm pre-operatively to 841.8 ± 64.1 post-operatively, a change of 5.5 ± 4.4 mm (p < 0.0001). A significant correlation was found between the amount of correction and the increase in overall leg length (r. 2. = 0.21, p = 0.009). In the lateral closing wedge group, total leg length was found to decrease from 840.6 ± 51.5 mm pre-operatively to 837.9 ± 52.0 post-operatively, a decrease of 2.7 ± 4.0 mm (p = 0.0008). No correlation was found between the amount of correction and the change in overall leg length. The difference in mean leg length change between opening and closing wedge osteotomies was 8.2 ± 5.9 mm (p < 0.0001). Conclusions:. Medial opening wedge HTO can result in significant leg lengthening depending on the degree of opening. Leg length changes associated with lateral closing wedge HTO are generally smaller. Both techniques results in less leg length change than mathematical models predict. Pre-operative leg length discrepancy should be considered when choosing an osteotomy technique

Introduction. Leg length and offset are important considerations in total hip arthroplasty (THA). Navigation systems are capable of providing intra-operative measurements of leg length and offset, and high accuracy has been shown in experimental studies. Objective. This in-vivo study assesses the accuracy of an imageless navigation system, with a pin-less femoral array, in measuring offset and leg length changes. Method. A prospective, consecutive series of 24 patients undergoing navigated total hip arthroplasty were included in the study. Intra-operative measurements of leg length and offset were recorded using the navigation system. For each patient pre- and post-operative digital radiographs were scaled and analysed to provide radiographic measurements of change in leg length and offset. Results. Measurements of leg length change made by the navigation system showed a statistically significant correlation with the size of change measured radiographically (R=.77, P < 0.0001). The mean difference between the radiographic and navigational measurement was 0.4 ± 2.8 mm. The navigation system was accurate to within 1 mm of the radiographic measurement in 50% of cases, within 2 mm in 67% of cases, and within 5 mm in 96% of cases. Measurements of offset change by the navigation system also showed a statistically significant correlation with radiographic measurements, however the correlation was less pronounced (R=.47, P=0.02). The mean difference between navigational and radiographic measurements was 1.4 ± 6.4 mm. The navigation system was accurate to within 1 mm of the radiographic measurement in 8% of cases, within 2 mm in 25% of cases, and within 5 mm in 75% of cases. Conclusion. This study demonstrates in-vivo that an imageless, non-invasive navigation system is a reliable tool for intra-operative leg length and offset measurement

We have developed a technique with the underlying principle being that the difference in height between what is removed and what is inserted will determine the leg length correction (Figure 1). The height of the implant to be inserted is determined from the manufacturer's specifications. We have developed a Vertical Measurement Tool to accurately and reproducibly determine the height of the resected bone (Figure 2). Leg length correction = a−b−c+d. Vertical Measurement Tool validation was performed by 4 separate surgeons on 20 resected femoral heads in the laboratory. Inter and intra-observer error was assessed. Fifty patients were assessed clinically and radiologically, to assess if desired leg length correction was achieved. Statistical analysis showed the device to be accurate with high intra and inter observer reliability. Differences between the observers were tested using a general linear model in a repeated measure design. No main effect and interaction effects were found. Intra operatively the resected head was measured and the formula was applied. The range of desired correction was 0mm to 18mm. In all cases the post-operative correction was within 4mm of the pre-operative planned correction. Statistical analysis showed that a linear Regression with ‘Actual’ as dependent and ‘Lambda’ as independent variables resulted in R= 0.889. We believe that it is consistently possible to achieve a leg length correction to within 5 mm of the pre-operative plan using the Vertical Measurement System. The system is simple and reproducible even in the hands of relatively inexperienced surgeons. For any figures or tables, please contact the authors directly by clicking on ‘Info & Metrics’ above to access author contact details

Introduction. One of the more common complaints from patients in their post-operative total knee arthroplasty (TKA) is the perceived feeling of the operative leg feeling longer than the non-operative leg. Studies have shown that the leg length discrepancies may occur in up to 80% of patients following unilateral TKA patients. The purpose of this study was to determine the incidence of leg length discrepancy (LLD) after primary TKA as well as determine the correlation between deformity and incidence of LLD. Methods. We retrospectively reviewed 1108 patients who underwent a primary unilateral TKA at a single institution. 97 patients were excluded for lack of imaging, prior total hip replacement or body mass index greater than 40 kg/m2. Hip to ankle biplanar radiographs were obtained pre-operative and 6 weeks postoperatively for all patients. Two independent observers measures leg length, femur length, tibia length, overall alignment and deformity present for all radiographs. Results. 1,101 patients were included. Mean overall lengthening was 3.4 mm [Range −21 to 22.8mm; SD 7.4] with 81% of limbs lengthened. In our cohort, 9% of patients had LLD greater than 10 mm and 43% of patients had LLD of more than 5mm after TKA. Post-operative radiographic LLD was associated with increased pre-operative LLD (P<.001) and with female gender (p=0.03). Patients with pre-operative valgus deformity were more likely to have an increased lengthening of greater than 5mm compared to patients with varus deformity (OR:1.66). Conclusion. 43% of patients will have a LLD >5mm following correction of deformity and ligament balances in knee replacement surgery. Surgeons should be aware and this should be reviewed with patients as part of their expectations of surgery. For figures, tables, or references, please contact authors directly

Aims. There is no consensus about the best method of achieving equal leg lengths at total hip arthroplasty (THA) in patients with Crowe type-IV developmental dysplasia of the hip (DDH). We reviewed our experience of a consecutive series of patients who underwent THA for this indication. Patients and Methods. We retrospectively reviewed 78 patients (86 THAs) with Crowe type-IV DDH, including 64 women and 14 men, with a minimum follow-up of two years. The mean age at the time of surgery was 52.2 years (34 to 82). We subdivided Crowe type-IV DDH into two major types according to the number of dislocated hips, and further categorised them into three groups according to the occurrence of pelvic obliquity or spinal curvature. Leg length discrepancy (LLD) and functional scores were analysed. Results. Type-I included 53 patients with unilateral dislocation, in which 25 (category A) had no pelvic obliquity or spinal deformity, 19 (category B) had pelvic obliquity with a compensated spinal curvature and nine (category C) had pelvic obliquity and decompensated spinal degenerative changes. Type-II included 25 patients with one dislocated and one dysplastic hip, in which there were eight of category A, 15 of category B and two of category C. Pre-operatively, there were significant differences between the anatomical and functional LLD in type-IB (p = 0.005) and -IC (p < 0.001), but not in type-IA, -IIA or -IIB. Post-operatively, bony LLD increased significantly in types-IB, -IC and -IIB, whereas functional LLD decreased significantly in each type except for IIA. The mean functional LLD decreased from 30.7 mm (standard deviation (. sd. ) 18.5) pre-operatively to 6.2 mm (. sd. 4.4) post-operatively and the mean anatomical LLD improved from 35.8 mm (. sd. 19.7) pre-operatively to 12.4 mm (. sd. 8.3) post-operatively. Conclusion. Pelvic and spinal changes are common in patients with Crowe type-IV DDH and need to be taken into consideration when planning THA, in order to obtain equal leg lengths post-operatively. The principal subdivisions of Crowe type-IV DDH which we describe proved effective in achieving equal leg lengths and satisfactory outcomes. Cite this article: Bone Joint J 2017;99-B:872–9

Introduction: Modular prostheses were first developed for use in total hip arthroplasty (THA) in the 1980s as a potential solution to the problem of leg length inequality. There is much literature discussing the advantages and disadvantages of modularity in THA but there are few studies directly comparing modular and non-modular prostheses and their accuracy in restoring normal anatomy. Our aim was to assess whether modularity in THA improves the restoration of femoral offset and leg length. Methods: An analysis of post-operative radiographs of 76 patients who underwent THA - 38 using modular and 38 using non-modular prostheses was undertaken. The femoral offset and leg length of the operated and un-operated hip were measured for each patient. Inter-and intra-observer errors were reduced to a minimum. A two-tailed T test was then applied to the data. Results: Restoration of leg length (to within +/− 10mm of the un-operated hip) was achieved in 81.6% of patients in the non-modular group, compared to 78.9% in the modular group (p=0.60). On average, the modular system increases leg length of the operated hip by 0.64mm compared to the non-modular system, which reduces leg length by 3.76mm (p=0.016). The femoral offset is restored to within 5mm of the un-operated hip in 60.5% of modular THA and in 55.3% using a non-modular prosthesis (P=0.48). On average, modular prostheses increased offset by 0.85mm and non-modular prostheses by 0.15mm (P=0.64). Discussion: The modular and non-modular hip prostheses are equally successful in achieving restoration of leg length and femoral offset to the pre-pathological state

Introduction. Leg length and offset are important considerations in total hip arthroplasty (THA). Navigation systems are capable of providing intra-operative measurements, which help guide the surgeon in leg length and offset adjustment. Objective. This controlled study investigates whether the use of computer navigation leads to more accurate achievement of pre-operative leg length and offset targets in THA. Method. A total of 61 patients were included in the study. A prospective, consecutive series of 24 patients undergoing navigated total hip arthroplasty were compared to an historic, consecutive series of 37 patients who underwent total hip arthroplasty without the use of navigation. The changes made to leg length and femoral offset were measured from scaled pre- and post-operative digital radiographs. The target changes to leg length and femoral offset were recorded from pre-operative digital templating sessions. Results. No statistically significant differences in terms of age, sex and body mass index were found between the two groups. Femoral offset targets were more closely achieved in the navigated cohort compared with the non-navigated group (P < 0.05). The mean deviation from the pre-operative target offset change was 2.9 ± 2.7 mm in the navigated group, and 5.1 ± 4.6 mm in the non-navigated group. For leg length, no statistically significant difference was found between the navigated and non-navigated cohorts in the difference between planned targets and radiographic changes (P=0.78). The mean deviation from target leg length change was 3.9 ± 2.9 mm in the navigated group and 4.2 ± 3.4 mm in the non-navigated group. When the navigation system was employed, procedure time was longer by a mean of 6 minutes, however this finding was not statistically significant (P=0.084). Conclusion. The use of navigation helps the surgeon to achieve their pre-operative goals for offset change. The navigation system was not shown to impact leg length management

Background. Leg length discrepancy real or perceived remains an important source of patient dissatisfaction after a total hip replacement. Pre-operative templating and intra-operative measurement has to be used to ensure an accurate restoration of the normal centre of rotation of the hip as well as equal leg lengths. Theoretically more bone has to be resected from the femur to maintain the centre of the femoral head in the same location. This is due to a smaller size of the prosthetic femoral head compared to the native femoral head. It was postulated that this was an accurate predictor of leg length after a total hip replacement. Methods. 56 consecutive patients who underwent a total hip replacement (cemented, uncemented or hybrid) had intra-operative measurements documented of their femoral head-neck resection distance. This was compared with the measurement of the femoral prosthesis that was inserted. A telephonic survey of the patients perceived leg equality as well as a radiological measurement of their actual leg lengths on a standing AP X-ray at 6 weeks post-operatively was done. Results. Forty eight of the 56 patients (85%) reported subjectively equal leg lengths. Eight patients reported unequal leg lengths, 5 longer and 3 shorter. Of the 5 cases that reported longer leg lengths 4 had more prosthesis inserted than bone resected. The 3 shorter reported legs also had more prosthesis inserted than bone resected in 2 cases. Of the 8 patients who reported unequal leg lengths only 3 were unequal on X-ray measurement (2 longer and 1 shorter). There was good correlation between the amount of bone resected versus prosthesis inserted and the patient's subjective evaluation of leg length discrepancy, but poor correlation between subjective leg length discrepancy and objective radiological evaluation. NO DISCLOSURES

Background. Total hip arthroplasty for Crowe type IV developmental dysplasia of the hip is a technically demanding procedure. Restoration of the anatomical hip center frequently requires limb lengthening in excess of 4 cm and increases the risk of neurologic traction injury. However, it can be difficult to predict potential leg length change, especially in total hip arthroplasty for Crowe type IV developmental hip dysplasia. The purpose of the present study was to better define features that might aid in the preoperative prediction of leg length change in THAs with subtrochanteric femoral shortening osteotomy for Crowe type IV developmental dysplasia of the hip. Patients and Methods. Primary total hip arthroplasties with subtrochanteric femoral shortening osteotomy were performed in 70 hips for the treatment of Crowe type IV developmental hip dysplasia. The patients were subdivided into two groups with or without iliofemoral osteoarthritis. Leg length change after surgery was measured radiographically by subtracting the amount of resection of the femur from the amount of distraction of the greater trochanter. Preoperative passive hip motion was retrospectively reviewed from medical records and defined as either higher or lower motion groups. Results. The preoperative flexion of patients without iliofemoral osteoarthritis was significantly higher than for patients with iliofemoral osteoarthritis. All hips without iliofemoral OA had higher motion. The preoperative flexion in the higher motion group both with and without iliofemoral OA was significantly greater than in the lower group with iliofemoral OA (Figure 1). Leg length change in patients without iliofemoral osteoarthritis was significantly greater than with iliofemoral osteoarthritis (Figure 2), and the higher hip motion group had greater leg length change in THA than the lower motion group. No clinical evidence of postoperative neurologic injury was observed in patients with iliofemoral OA. Postoperative transient calf numbness in the distribution of the sciatic nerve was observed in 2 of 25 hips without iliofemoral OA (8.0%), however, no sensory and motor nerve deficit was observed. Discussion. The authors hypothesized that preoperative hip motion could affect soft tissue contractures, and our findings suggest that the soft tissues surrounding the hip joint with iliofemoral OA should be more contracted than the hip without OA. We also found leg length change in the higher motion group was greater than in the lower motion group. Previous studies reported limb lengthening in excess of 4 cm could increase the risk of nerve palsy. Transient calf numbness in the distribution of the sciatic nerve was observed in 2 hips without iliofemoral OA and their leg length change was not greater than 4 cm. Our findings suggest that hips without iliofemoral OA should be paid attention to protect the nerves from excessive elongation. The current study identifies several features that might help predict leg length change during the preoperative planning of total hip arthroplasty for Crowe type IV developmental hip dysplasia

Introduction Leg length inequalities (LLIs) are a common finding in every orthopaedic practice. They can be classified into anatomical and functional LLIs. LLIs can e.g. cause gait and balance disabilities, low back pain and functional scoliosis of the spine. In patients with a total hip replacement a higher rate of aseptic loosening of the prosthesis was found when LLIs were present (Gurney 2002). Until today LLIs are treated statically by wooden blocs, which are placed under the shorter extremity, until the pelvis is levelled. However, the correction of LLIs should also be evaluated dynamically to examine the influence of correction onto the spine and pelvis during gait. Therefore, we seek to evaluate in this pilot study the influence of simulated LLIs on spine and pelvis during gait. Methods A total of 30 healthy subjects (17 females & 13 males) with an average age of 24.4 years were measured in this study. First, LLIs (1 to 4 cm) were simulated with the subjects standing on a simulation platform, which height could be controlled, as previously described (Betsch 2012). In addition, a specially designed sandal with different insole heights (1 to 4 cm) was used to simulate LLIs under dynamic condition while subjects were walking on a treadmill. Changes in pelvic position and spinal posture caused by the LLIS were measured using a rasterstereographic system (Formetric 4D motion, Diers International GmbH, Germany). All data were checked for Gaussian distribution by the Chi square test. Student t-tests were used to check for differences between the LLIs. The level of significance was set at p

Introduction/Aims: Early results of a prospective randomised control trial suggested improved position of components implanted during primary hip replacement. The aim of this study is to definitively show the benefit of computer aided navigation in hip arthroplasty with regard to acetabular component position, stem position and leg length. Method: Eighty consecutive patients were prospectively recruited. Patients were quasi-randomised, on an alternating basis, to undergo hip arthroplasty conventionally or with imageless computer navigation. Postoperatively, a CT scan was performed of the pelvis and lower limb. Using a dynamic CT planning software package, the cup and stem position was measured and compared to the position expected by the three operating surgeons in control cases and the position given by the navigation unit in the study group. Change in leg length was measured clinically and compared with the navigation predicted leg length change. Statistical analysis was performed by a statistician. Results: Thirty nine navigated hips (29 female, 10 male) and forty one control hips (26 female, 15 male) were recruited. In the navigated group, the mean age was 65.7 and mean BMI was 29.1. In the control group, the mean age was 64.7 and the mean BMI was 29.4 in the control group. Uncemented, securfit/trident hips were used in 18 navigated cases and 20 control cases, with all other cases being cemented Exeter stems and contemporary cups. None of these differences were significant using the Mann-Whitney test. The mean operating time was 128 minutes for navigated hips and 84 minutes for controls, the difference significant at p< 0.005 using t-test. There was no significant correlation between clinical leg length change, measured in the operating theatre and the leg length change predicted by navigation. Accuracy of cup and stem placement was assessed by comparison of the homogeneity of variances, the Levene statistic, in the navigated and control groups. The range of cup inclination, cup version and stem version was significantly narrowed in the navigation group (p< 0.05). Conclusion: Computer navigation improves the accuracy of component placement in hip arthroplasty with respect to cup version, cup inclination and stem version with either cemented or uncemented hips

There has been controversy about whether limb length discrepancy (LLD) affects outcome after total hip replacement (THR). We examined input variables and outcomes of over 1200 patients who received primary THR with the Exeter stem and a variety of acetabular components in the Exeter Primary Outcomes Study. This was a non randomized prospective multi centre study. We examined whether specific groups of patients or surgeons were more likely to have LLD at one year after surgery. Data for leg length measured on clinical assessment were available for 1207 patients at 1 year. 237 patients were recorded as having a leg length difference of 1 cm or more, and 73 a difference of 2 cm or more. 138 were longer on the operated side and 99 were shorter. The likelihood of having LLD of 2 cm or more was not significantly affected by the grade of surgeon (consultant or trainee), BMI, age of patient, position of patient during surgery or surgical approach, or the use of regional or general anaesthetic. We examined the effect of LLD on outcomes at 3 months and 1,2,3 and 4 years. Patients with LLD > 1cm had significantly worse Oxford Hip Scores (OHS) at 1, 2, 3 and 4 years (p< 0.01), with the OHS generally being an average 2 points worse in those with LLD. The most consistent difference between those with and without LLD was a patient reported limp on the Oxford Hip Questionnaire. We conclude that LLD is a common problem after THR and that all patient groups may be affected. It is associated with a significantly worse functional outcome as measured by a validated hip score. Systematic adoption of accurate intra-operative measures of leg length might pay dividends in minimizing this complication

Inaccurate component placement during total hip arthroplasty (THA) can have significant and costly consequences. Malpositioning of the acetabular cup components can lead to dislocation and revision surgery, while postoperative discrepancies in leg length can lead to biomechanical imbalances, causing chronic low back pain. Current methods for monitoring these parameters intraoperatively rely on manual methods such as tissue tensioning or on the surgeon's experience, both of which are subject to inaccuracies. Computer-assisted navigation, while currently used in only a small percentage of THA procedures, is an emerging technology that has the potential to improve the accuracy with which surgeons place components during THA by providing real-time, intraoperative data. One innovative navigation system – Intellijoint HIP. ®. (Intellijoint Surgical, Waterloo, ON) – has demonstrated its accuracy, time-neutrality, safety and effectiveness in clinical studies and has the potential to improve outcomes and reduce re-admissions and revisions during both primary and revision THA. The ability to assist with placement of the cup component at a preoperative target is a hallmark of navigation systems. In studies examining the proportion of cups placed within Lewinnek's safe zone, significantly more cups were placed within this zone with the Intellijoint system than when using traditional methods (anteversion: 58% vs. 37%, p=0.005; inclination: 87% vs. 67%, p=0.002). Similarly, surgeons were better able to place the cup at a functional orientation of 40 degrees inclination/20 degrees anteversion, with a significantly higher proportion of cups placed within 10 degrees of this target while using the Intellijoint system (70%) than during conventional THA (53%, p=0.02). In comparisons with postoperative imaging, the Intellijoint system has demonstrated excellent accuracy. In a recent study, intraoperative measurements of anteversion and inclination were within 3.3 ± 3.1 degrees and 1.1 ± 0.9 degrees, respectively, of postoperative 3D EOS imaging. Results for leg length discrepancy are similarly accurate: across several studies, the mean difference between navigation and radiographic measurements ranged from 0.3 to 4.3mm. Evidence indicates that the 90-day rates of dislocation and revision surgery following primary THA with the Intellijoint system were substantially lower than rates associated with traditional methods. These results hold true following navigation-assisted revision surgery as well. At 90 days, 1 year and 2 years post-procedure, no dislocations were reported. Beyond dislocation, the overall rate of adverse events in cases using Intellijoint has been reported as remarkably low. No device-related fractures have been reported, nor have any instances of postoperative pain at the sites of the surgical pins supporting the camera and/or tracker components. Finally, there is no significant increase in surgical time associated with the use of this device, with a large study comparing navigated THA with traditional THA showing a 2.9-minute increase in procedural time (p=0.60), 1.0 minute of which occurs prior to primary incision (unpublished data). Computer-assisted navigation – and the Intellijoint HIP system specifically – has demonstrated the ability to improve the accuracy with which surgeons implant components during THA without adversely affecting operating room efficiency or patient safety. This technology has the potential to dramatically improve patient-related outcomes in both the short- and long-term and represents the benefits associated with advanced technologies in the operating room

Leg-length inequality is not uncommon following primary total hip arthroplasty and can be distressing to the patient. An excellent clinical result with respect to pain relief, function, component fixation, range of motion and radiographic appearance can be transformed into a surgical failure because of patient dissatisfaction due to leg-length inequality. Postoperative leg-length discrepancy was determined radiographically for 200 patients who had had a primary custom total hip arthroplasty. In all cases the opposite hip was considered to have a normal joint center. The femoral component was designed and manufactured individually for each patient using screened marker x-rays. A graduated calliper was used at the time of surgery to control depth of femoral component insertion. The transverse acetabular ligament was used to control placement of the acetabular component and therefore restore acetabular joint center. Using this method 94% of subjects had a postoperative leg-length discrepancy that was 6mm or less when compared to the normal side (average, +0.38mm). The maximum value measured for leg-length discrepancy was +/−8mm. We describe a simple technique for controlling leg length during primary total hip arthroplasty and propose an alternative radiographic method for measuring leg-length discrepancy

Objectives/Background: Long-term outcome in THR is multifactorial influenced. Malpositioning leads to complications as early loosening, leg length difference or dislocation of the artificial joint. A proven factor for early losening is a misplacment of the center of rotation or varusposition of the stem. A higher luxation risk results out of high inclination and anteversion angles an reduced soft tissue tension. Aim of this study was to prove the image free navigation software in the modular Navitrack-System to check the implant position based on anatomical intraoperative acquired data. Design/Methods: In 35 consecutive cases we implantet the ACA screwcup and the Optan anatomical stem with use of the Navitrack navigation System. The software calculates al relevant data out of intraopertive probed landmarks. Intraoperative the shifting of the center of rotation, the cup anteversion and inclination, the stem inclination and torsion and the leglength shift is shown in real time. Intraoperative data were compared with postoperative position measurement in plain X-rays and in 15 patients in postoperative CT scans. Results: In all cases navigated implantpositioning was possible. In 3 cases stem positioning was not possible cause of refference loosening. Mean inclination of the cup as shown in the Navigation System was 52 (range 45 – 58 ), mean anteversion was 11 (range -5 – 27). Mean postoperative inclination measured on postoperative X-Ray was 53,8 (range 49 – 60). The difference between the shown values from the CAS System to the postoperative X Ray for the inclination was 1,8 (range -9 – 6). The leg length difference on postoperative X-ray was in mean 3,1 mm, on screenshots 2,8 mm. The difference between screenshot and X ray was in mean 0,83 mm. Conclusions: This study shows, that with the CT free software for the Navitrack-System reliable cup and stem navigation is possible. Whenever the hip joint allows to probe a spherical segment in the femoral head or acetabulum navigated THR is possible without the need of intraoperative fluoroscopy or preoperative CT scan. For leg length control and cup Inclination the data are still promising. Further investigation is necessary for stem axis and cup anteversion according to the navigation based reference coordinate system. Whenever no geometric sphere existent, e.g. severe hip dysplasia, the system must be developed as a hybrid system with CT (NMR) based cup and image-less stem navigation

Introduction. Limb length discrepancy after THA can result in medicolegal litigation. It can create discomfort for the patient and potentially cause back pain or affect the longevity of the implant. Some patients tolerate the length inequality better compared to others despite difference in anatomical femoral length after surgery. Methods and materials. We analyzed the 3D EOS images of 75 consecutive patients who underwent primary unilateral THA (27 men, 48 women). We measured the 3D length of the femur and tibia (anatomical length), the 3D global anatomical length (the sum of femur and tibia anatomical lengths), the 3D functional length (center of the femoral head to center of the ankle), femoral neck-shaft angle, hip-knee-ankle angle, knee flexum/recurvatum angle, sacral slopes and pelvic incidence. We correlated these parameters with the patient perception of the leg length. Results. The values for leg length and pelvic parameters are shown in table 1. 37 patients had a perception of the LLD (49.3%). When the global anatomical length was shorter on the operated side, the perception of the discrepancy was observed in 56% of the cases. In case of anatomical length longer on the operated side, the perception of the discrepancy was described by the patients in 46% of the cases. The LLD perception was correlated with difference in functional length (p=0.0001), pelvic obliquity (p=0.003) and sacral slope (p=0.023). The anatomical femoral length was not correlated with the LLD perception (p=0,008). Discussion. The perception of LLD is a multifactorial complication. We found that the anatomical femoral length (that can be directly affected by the position of the stem) is not the only important factor. The functional length of the lower extremity which can also be affected by the knee deformities is better correlated with the LLD. The pelvic obliquity and version also affect the patient perception of the LLD

Introduction: Dislocation is the most common complication resulting in re-operation after total hip arthroplasty. This study investigates the association between acetabular prosthesis position, changes in femoral offset and leg length and the risk of dislocation. Patients and Methods: All total hip arthroplasties performed over the past 17 years at one institution were reviewed. The posterolateral approach was used in all cases. Only hips that included all of the following were included in the study: diagnosis of primary osteoarthritis, no previous surgery, unconstrained liner. 3682 hips met the inclusion criteria. 60 hips (1.6%) sustained a dislocation. Cup inclination and version was determined from scanned radiographs using Hip Analysis Suite software (University of Chicago) in all hips that dislocated and a control group of 60 patients matched for femoral head size, sex, age at surgery, side of hip replacement, time from surgery, BMI, type of prosthesis and bearing surface. We compared femoral offset and length against the contralateral normal hip, on standardised radiographs. Therefore dislocation cases where the contralateral hip had been replaced, where arthritic changes were present, or where previous surgery had been undertaken were not included in the analysis. 24 dislocating hips were measured and compared with 48 controls matched using the same criteria as above. Radiographs were analysed using Hip Analysis Suite. Results: There is a statistically significant difference (p=0.025) in anteversion between dislocators and matched controls. Inclination is not significantly associated with dislocation (p=0.536). There is a relative risk of 3.0 of dislocation in cups with ≤15 degrees of anteversion compared with > 15 degrees of anteversion. This difference in dislocation is statistically significant (p< 0.01). Increased femoral offset compared with the normal contralateral hip is statistically significantly associated with an increased risk of dislocation (p=0.03). Change in leg length is not associated with dislocation risk. Discussion: Decreased cup anteversion is associated with an increased risk of dislocation in hips operated on via the postero-lateral approach. Our results indicate that the surgeon should aim for a minimum of 15 degrees of anteversion to reduce the risk of dislocation. The increase in femoral offset in the prosthetic hip compared with the normal contralateral hip and its association with dislocation may be due to intraoperative attempts to compensate for an unstable hip by increasing offset. These results indicate that a surgeon should be cautious when increasing femoral offset alone to try and compensate for a potentially unstable hip. Other factors, for example acetabular version should be addressed, with readjustment of cup position intra-operatively if required

Incorrect restoration of leg length (LL) and offset is a major source of patient dissatisfaction and dysfunction after total hip arthroplasties (THAs). Evaluations on anterior-posterior x-ray images are state-of-the-art to assess the accuracy of such techniques. However, x-ray based measurements of LL and offset are challenging and limited in terms of accuracy. Within this study, we evaluated the accuracy of such measurements by analysing a series of clinical data. We evaluated the results on the non-treated side, since we know that there should be no significant difference between pre- and postoperative measurements on this side. A series of 44 consecutive patients was analysed regarding changes in the difference between pre- and post-operative LL and offset measurements. Anterior-posterior x-rays were taken pre- (pre-OP) and post-operatively (post-OP) with a calibration by a scaling ruler (pre-OP) or implant size (post-OP). The LL and offset measurements were performed with a digital planning software based on the teardrop and transischial line. The distance between the teardrop/transischial line and the trochanter minor was measured to assess LL differences. Femoral offset (FO) was calculated as the orthogonal distance between the centre of the femoral head and the proximal shaft axis. Global offset (GO) was calculated as the distance between the inferior aspect of the teardrop figure and the shaft axis along the teardrop line. Descriptive statistics (mean value ± standard deviation) were calculated for the different types of measurements. Statistically significant differences were checked according to a student's t-test (α = 0.05). The differences between the pre-and post-operative situation was 0.8±3.2 mm for LL, 0.2±3.5 mm for GO, and −0.5±2.5 mm for FO when referencing to the teardrop line and 0.9±4.0 mm (LL) and −0.3±2.7 mm (FO) for the transischial line. The error distributions did not show statistically significant differences when referencing to the teardrop or transischial line. But high differences (0.1±6.6 mm) were found when comparing the LL values (teardrop vs. transischial) case-by-case. Within this study we demonstrated that x-ray based offset and LL measurements show reasonable inaccuracies. X-ray based evaluations of navigation-based techniques to assist LL and offset restoration cannot produce significantly better results than these analysed limits. That is, even if the navigation technique would be perfectly accurate, the evaluation would not achieve better accuracies than approximately ±3.5 mm for LL, ±3.5 mm for GO, and ±2.5 mm for FO

INTRODUCTION. Leg length discrepancy following total hip arthroplasty (THA) can be functionally disabling for affected patients and can lead on to litigation issues. Assessment of limb length discrepancy during THA using traditional methods has been shown to produce inconsistent results. The aim of our study was to compare the accuracy of navigated vs. non navigated techniques in limb length restoration in THA. METHODS. A dataset of 160 consecutive THAs performed by a single surgeon was included. 103 were performed with computer navigation and 57 were non navigated. We calculated limb length discrepancy from pre and post op radiographs. We retrieved the intra-operative computer generated limb length alteration data pertaining to the navigated group. We used independent sample t test and descriptive statistics to analyse the data. RESULTS. The two subgroups were matched for age, diagnosis and preoperative leg length discrepancy. The mean age was 69.12 (37–89, SD-8.3) and the mean BMI was 29 (19–44, SD-5.03). The mean post op limb length discrepancy in the non navigated group was 5 mm (SD-6) as compared to mean of 3.5mm (SD-6.5) for the computer navigated group. This difference was statistically significant (p<0.04). 18% of patients in the non navigated group had a limb length discrepancy of >10 mm as compared to 12% in the navigated group. There was no statistically significant difference between the computer predicted leg length alterations and those measured on radiographs. (p>0.15). DISCUSSION & CONCLUSION. The use of Computer navigation in THA can be useful in reducing errors related to leg length discrepancy. It helps in reducing the rates of unacceptably high discrepancies. In our experience, the results of this technique were predictable and reproducible. We intend to continue using this tool for our total hip arthroplasties

Aims

Temporary epiphysiodesis (ED) is commonly applied in children and adolescents to treat leg length discrepancies (LLDs) and tall stature. Traditional Blount staples or modern two-hole plates are used in clinical practice. However, they require accurate planning, precise surgical techniques, and attentive follow-up to achieve the desired outcome without complications. This study reports the results of ED using a novel rigid staple (RigidTack) incorporating safety, as well as technical and procedural success according to the idea, development, evaluation, assessment, long-term (IDEAL) study framework.

Introduction

Leg length discrepancy (LLD) is a common sequalae of limb reconstruction procedures. The subsequent biomechanical compensation can be directly linked to degenerative arthritis, lower back pain, scoliosis and functional impairment. It becomes particularly problematic when >2cm, established as a clinical standard. This two-arm experimental study assesses how reliable an iPhone application is in the measurement of LLD at different distances in control and LLD patients.

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.

Aims. Perthes’ disease (PD) often results in femoral head deformity and leg length discrepancy (LLD). Our objective was to analyze femoral morphology in PD patients at skeletal maturity to assess where the LLD originates, and evaluate the effect of contralateral epiphysiodesis for length equalization on proximal and subtrochanteric femoral lengths. Methods. All patients treated for PD in our institution between January 2013 and June 2020 were reviewed retrospectively. Patients with unilateral PD, LLD of ≥ 5 mm, and long-leg standing radiographs at skeletal maturity were included. Total leg length, femoral and tibial length, articulotrochanteric distance (ATD), and subtrochanteric femoral length were compared between PD side and the unaffected side. Furthermore, we compared leg length measurements between patients who did and who did not have a contralateral epiphysiodesis. Results. Overall, 79 patients were included, of whom 21 underwent contralateral epiphysiodesis for leg length correction. In the complete cohort, the mean LLD was 1.8 cm (95% confidence interval (CI) 1.5 to 2.0), mean ATD difference was 1.8 cm (95% CI -2.1 to -1.9), and mean subtrochanteric difference was -0.2 cm (95% CI -0.4 to 0.1). In the epiphysiodesis group, the mean LLD before epiphysiodesis was 2.7 cm (95% CI 1.3 to 3.4) and 1.3 cm (95% CI -0.5 to 3.8) at skeletal maturity. In the nonepiphysiodesis group the mean LLD was 2.0 cm (95% CI 0.5 to 5.1; p = 0.016). The subtrochanteric region on the PD side was significantly longer at skeletal maturity in the epiphysiodesis group compared to the nonepiphysiodesis group (-1.0 cm (95% CI -2.4 to 0.6) vs 0.1 cm (95% CI -1.0 to 2.1); p < 0.001). Conclusion. This study demonstrates that LLD after PD originates from the proximal segment only. In patients who had contralateral epiphysiodesis to balance leg length, this is achieved by creating a difference in subtrochanteric length. Arthroplasty surgeons need to be aware that shortening of the proximal femur segment in PD patients may be misleading, as the ipsilateral subtrochanteric length in these patients can be longer. Therefore, we strongly advise long-leg standing films for THA planning in PD patients in order to avoid inadvertently lengthening the limb. Cite this article: Bone Joint J 2021;103-B(11):1736–1741

Aims. Achieving accurate implant positioning and restoring native hip biomechanics are key surgeon-controlled technical objectives in total hip arthroplasty (THA). The primary objective of this study was to compare the reproducibility of the planned preoperative centre of hip rotation (COR) in patients undergoing robotic arm-assisted THA versus conventional THA. Methods. This prospective randomized controlled trial (RCT) included 60 patients with symptomatic hip osteoarthritis undergoing conventional THA (CO THA) versus robotic arm-assisted THA (RO THA). Patients in both arms underwent pre- and postoperative CT scans, and a patient-specific plan was created using the robotic software. The COR, combined offset, acetabular orientation, and leg length discrepancy were measured on the pre- and postoperative CT scanogram at six weeks following surgery. Results. There were no significant differences for any of the baseline characteristics including spinopelvic mobility. The absolute error for achieving the planned horizontal COR was median 1.4 mm (interquartile range (IQR) 0.87 to 3.42) in RO THA versus 4.3 mm (IQR 3 to 6.8; p < 0.001); vertical COR mean 0.91 mm (SD 0.73) in RO THA versus 2.3 mm (SD 1.3; p < 0.001); and combined offset median 2 mm (IQR 0.97 to 5.45) in RO THA versus 3.9 mm (IQR 2 to 7.9; p = 0.019). Improved accuracy was observed with RO THA in achieving the desired acetabular component positioning (root mean square error for anteversion and inclination was 2.6 and 1.3 vs 8.9 and 5.3, repectively) and leg length (mean 0.6 mm vs 1.4 mm; p < 0.001). Patient-reported outcome measures were comparable between the two groups at baseline and one year. Participants in the RO THA group needed fewer physiotherapy sessions postoperatively (median six (IQR 4.5 to 8) vs eight (IQR 6 to 11; p = 0.005). Conclusion. This RCT suggested that robotic-arm assistance in THA was associated with improved accuracy in restoring the native COR, better preservation of the combined offset, leg length correction, and superior accuracy in achieving the desired acetabular component positioning. Further evaluation through long-term and registry data is necessary to assess whether these findings translate into improved implant survival and functional outcomes. Cite this article: Bone Joint J 2024;106-B(4):324–335

Aims. This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH). Methods. The study analyzed a consecutive series of 69 patients who underwent robotic-arm assisted THA between September 2018 and December 2019. Of these, 30 patients had DDH and were classified according to the Crowe type. Acetabular component alignment and 3D positions were measured using pre- and postoperative CT data. The absolute differences of cup alignment and 3D position were compared between DDH and non-DDH patients. Moreover, these differences were analyzed in relation to the severity of DDH. The discrepancy of leg length and combined offset compared with contralateral hip were measured. Results. The mean values of absolute differences (postoperative CT-preoperative plan) were 1.7° (standard deviation (SD) 2.0) (inclination) and 2.5° (SD 2.1°) (anteversion) in DDH patients, and no significant differences were found between non-DDH and DDH patients. The mean absolute differences for 3D cup position were 1.1 mm (SD 1.0) (coronal plane) and 1.2 mm (SD 2.1) (axial plane) in DDH patients, and no significant differences were found between two groups. No significant difference was found either in cup alignment between postoperative CT and navigation record after cup screws or in the severity of DDH. Excellent restoration of leg length and combined offset were achieved in both groups. Conclusion. We demonstrated that robotic-assisted THA may achieve precise cup positioning in DDH patients, and may be useful in those with severe DDH. Cite this article: Bone Joint Res 2021;10(10):629–638

Introduction: Leg length discrepancy (LLD) following hip arthroplasty can produce abnormal loading leading to pain, increased wear and loosening of implants. The aim of this study was to investigate the relationship between LLD and static limb loading.

Methods: A pedobarograph was used to measure the limb loading of 19 normal volunteers aged 18 to 58. Each volunteer was asked to stand on the Pedobarograph with both feet so that their weight could be recorded. The load through the left leg was then recorded with the right leg on a platform level beside it. The platform was then raised in 1 cm increments to 6 cm, to simulate different levels of LLD. In each position 3 readings were taken with the right knee flexed (pelvis level), and straight (pelvis tilted).

Results: When the feet were level the left leg took 53 % of the load. As the height of the right foot was increased the load through the left leg increased in a non-linear fashion.

With the knee flexed, a 1 cm difference produced a 3 % increase in loading. This was significant (P< 0.05). All subsequent increases were also significant. The largest increase in load was observed between 1 cm & 2 cm (+5 %). At 6cm the left leg load was 70.9 %.

With the pelvis tilted, there were smaller increases in loading. These did not become significant until a difference of 5 cm. The maximum load was 62.1 % at 6 cm.

Discussion: The length-loading relationship was non-linear. The pelvis tilted stance produced less loading asymmetry, but more discomfort than the flexed knee stance.

At Sheffield Children’s Hospital 40 children with leg length discrepancies (caused variously by sepsis, trauma, hemihypertrophy, congenital longitudinal deficiencies) were assessed using three clinical methods: measuring blocks in the standing erect position, supine measurement from the anterior superior iliac spine to the medial malleolus, and prone measurement with the knees flexed, which allowed separate measurement of femoral and tibial discrepancies. All were then subjected to comparative CT scanogram.

The mean age of the 24 boys and 16 girls was 10 years (5 to 16). Children with abnormal pelvic architecture or a fixed pelvic obliquity were excluded from the study. The mean clinical length discrepancy was 29 mm (0 to 80 mm). The mean CT scanogram measurement was 26.4 mm (0 to 75 mm). The mean difference between clinical measurements taken prone and CT scanogram measurements was only 3.6 mm (0 to 14). There was little difference in the accuracy of measuring femoral and tibial discrepancies clinically or by CT scanogram. The prone method of measurements is a useful adjunct to Staheli’s rotational profile in the prone position.

In previous congress of ISTA in Hawaii, we reported the results about accuracy of the cup center position in our image-free navigation system. In the new version of our navigation system, leg elongation and offset change as well as cup center position can be navigated. In this study, we therefore investigated the accuracy of cup center position, leg elongation and offset change.

Twenty four THA operations were performed with using the image-free OrthoPilot THA3.1 dysplasia navigation system (B. Braun Aesculap, Tuttlingen, Germany) between August 2009 and December 2009 by three experienced surgeons. In this system, cup center height was shown as the distance from tear drop, and cup medialization was shown as horizontal distance from inner wall of acetabulum. Leg elongation and offset change were navigated by comparing the two reference points in femur between registration before neck resection and that after inserting the trial implant. After operation, the cup angles were measured on CT image, and cup center position, leg elongation and offset change were measured on plain radiography. We compared these values that indicated by the navigation system to those measured on the CT image and the plain radiography.

The average cup inclination was 37.5 ± 7.0 degree and anteversion was 22.2 ± 4.7 degree. The average absolute difference between navigation and measured angles were 5.2 ± 4.0 degree in inclination, 5.9 ± 4.0 degree in anteversion. The difference of cup height was 5.8 ± 3.9 mm, cup medialization was 3.8 ± 2.7 mm, leg elongation was 4.3±3.3mm, and offset was 5.4±4.1mm, respectively.

By using this new version navigation system, we can plan the cup center position and navigate it within smaller error of vertical and horizontal direction than the previous system. Moreover, leg elongation and offset change can be satisfactory navigated during operation. However surgeon's skill and learning curve might have influence the accuracy. We have to continue to evaluate this system and make effort to further improvement.

Thirty four patients underwent 34 single entry percutaneous physiodesis (SEPP) of both distal femur and proximal tibia between July 1996 and June 2004. Twenty six patients had attained maturity and the rest continue to be followed up. There were 10 females and 16 males. The mean ages were12.8yrs (range11–14yrs) and 13.8yrs (range11–15) respectively.

All patients underwent at least three assessments of limb length discrepancy(lld) using CT Scannograms. The Mosely’s straight line graph was then used to predict lld and timing of correction. The procedure was performed under image intensifier control using a 6.5mm drill passed through a small incision. The drill was passed in three directions through a single entry . The physis was curetted.

The mean lld at SEPP was 3.36cm(range1.5–5.9cm). The prediction of lld at maturity after SEPP was a mean of 1.4cm(range0.2–2.5cm) and final lld was a mean of 1.38cm (range0.3–2.5cm). The accuracy of prediction was found to have a mean of 0.44cm (range0–0.7cm). One patient (6%) complained of knee pain for about 2 weeks that settled.

The rest had no complications. We feel that this technique is minimally invasive with a cosmetic scar, has a shorter hospital stay, low complications and is reliable for phuseal ablation. This technique aided by the CT scannogram and a Mosely’s straight line graph provides a reliable and effective method in the management of small amounts of lld.

Aims. The primary aim of this study was to compare the hip-specific functional outcome of robotic assisted total hip arthroplasty (rTHA) with manual total hip arthroplasty (mTHA) in patients with osteoarthritis (OA). Secondary aims were to compare general health improvement, patient satisfaction, and radiological component position and restoration of leg length between rTHA and mTHA. Methods. A total of 40 patients undergoing rTHA were propensity score matched to 80 patients undergoing mTHA for OA. Patients were matched for age, sex, and preoperative function. The Oxford Hip Score (OHS), Forgotten Joint Score (FJS), and EuroQol five-dimension questionnaire (EQ-5D) were collected pre- and postoperatively (mean 10 months (SD 2.2) in rTHA group and 12 months (SD 0.3) in mTHA group). In addition, patient satisfaction was collected postoperatively. Component accuracy was assessed using Lewinnek and Callanan safe zones, and restoration of leg length were assessed radiologically. Results. There were no significant differences in the preoperative demographics (p ≥ 0.781) or function (p ≥ 0.383) between the groups. The postoperative OHS (difference 2.5, 95% confidence interval (CI) 0.1 to 4.8; p = 0.038) and FJS (difference 21.1, 95% CI 10.7 to 31.5; p < 0.001) were significantly greater in the rTHA group when compared with the mTHA group. However, only the FJS was clinically significantly greater. There was no difference in the postoperative EQ-5D (difference 0.017, 95% CI -0.042 to 0.077; p = 0.562) between the two groups. No patients were dissatisfied in the rTHA group whereas six were dissatisfied in the mTHA group, but this was not significant (p = 0.176). rTHA was associated with an overall greater rate of component positioning in a safe zone (p ≤ 0.003) and restoration of leg length (p < 0.001). Conclusion. Patients undergoing rTHA had a greater hip-specific functional outcome when compared to mTHA, which may be related to improved component positioning and restoration of leg length. However, there was no difference in their postoperative generic health or rate of satisfaction. Cite this article: Bone Joint Res 2021;10(1):22–30

Hop tests are used to determine return to sports after ACL reconstruction. They mostly measure distance and symmetry but do not assess kinematics and kinetics. Recently, biomechanical evaluations have been incorporated into these functional jump tests for the better assessment of return to sport. We assessed the sagittal plane range of motion (ROM) of the knee, the deviation axis of rotation (DAOR), and the vertical ground reaction force (vGRF) normalized to body weight in nine healthy participants during the single leg (SLH) and crossover hop tests (COHT). Participants' leg lengths were measured. Jumping distances were marked in the test area as being 4/5 of the leg length. Four sensors were placed on the thighs, the legs and the feet. These body parts were handled as a single rigid body. Eight 480 Hz cameras were used to capture the movements of these rigid bodies. vGRF at landing were measured using a force plate (Bertec, Inc, USA). The ROM of the knee joint and the DAOR were obtained from kinematic data. Participants' joint kinematics metrics were similar in within-subjects statistical tests for SLH and COHT. We therefore asked whether the repeated vGRF normalized to body weight will be similar in both legs during these jumps. Joint kinematics metrics however were different in between subjects indicating the existence of a personalized jumping strategy. These hop tests can be recorded at the beginning of the training season for each individual, which can establish a comparative evaluation database for prospective lower extremity injury recovery and return to sport after ACL injury

Introduction. Legg-Calvé-Perthes disease (LCPD) often results in femoral head deformity and leg length discrepancy (LLD). Objective of this study was to analyse femoral morphology in LCPD patients at skeletal maturity to assess where the LLD originates, and evaluate the effect of contralateral epiphysiodesis for length equalisation on proximal and subtrochanteric femoral lengths. Materials and Methods. All patients treated for LCPD in our institution between January 2013 and June 2020 were retrospectively reviewed. Patients with unilateral LCPD, LLD of ≥5mm and long leg standing radiographs at skeletal maturity were included. Total leg length, femoral and tibial length, articulotrochanteric distance (ATD) and subtrochanteric femoral length were compared between LCPD side and unaffected side. Furthermore, we compared leg length measurements between patients who did and who did not have a contralateral epiphysiodesis. Results. 79 patients were included, 21/79 underwent contralateral epiphysiodesis for leg length correction. In the complete cohort the average LLD was 1.8cm (95% CI 1.5 – 2.0), average ATD difference was 1.8cm (95% CI −2.1 – −1.9) and average subtrochanteric difference was −0.2cm (95% CI −0.4 – 0.1). In the epiphysiodesis group the average LLD before epiphysiodesis was 2.7 (1.3 – 3.4) cm and 1.3 (−0.5 – 3.8) cm at skeletal maturity. In the non-epiphysiodesis group the average LLD was 2.0 (0.5 – 5.1), p=0.016. The subtrochanteric region on the LCPD side was significantly longer at skeletal maturity in the epiphysiodesis group compared to the non-epiphysiodesis group: −1.0 (−2.4 – 0.6) versus 0.1 (−1.0 – 2.1), p<0.001. Conclusions. This study concludes that LLD after LCPD originates from the proximal segment only. In patients who had had a contralateral epiphysiodesis, the subtrochanteric femoral region was significantly longer on the LCPD side. These anatomical changes need to be considered by paediatric surgeons when advising leg length equalisation procedures, and by arthroplasty surgeons when LCPD patients present for hip arthroplasty

Aims. Traditionally, acetabular component insertion during total hip arthroplasty (THA) is visually assisted in the posterior approach and fluoroscopically assisted in the anterior approach. The present study examined the accuracy of a new surgeon during anterior (NSA) and posterior (NSP) THA using robotic arm-assisted technology compared to two experienced surgeons using traditional methods. Methods. Prospectively collected data was reviewed for 120 patients at two institutions. Data were collected on the first 30 anterior approach and the first 30 posterior approach surgeries performed by a newly graduated arthroplasty surgeon (all using robotic arm-assisted technology) and was compared to standard THA by an experienced anterior (SSA) and posterior surgeon (SSP). Acetabular component inclination, version, and leg length were calculated postoperatively and differences calculated based on postoperative film measurement. Results. Demographic data were similar between groups with the exception of BMI being lower in the NSA group (27.98 vs 25.2; p = 0.005). Operating time and total time in operating room (TTOR) was lower in the SSA (p < 0.001) and TTOR was higher in the NSP group (p = 0.014). Planned versus postoperative leg length discrepancy were similar among both anterior and posterior surgeries (p > 0.104). Planned versus postoperative abduction and anteversion were similar among the NSA and SSA (p > 0.425), whereas planned versus postoperative abduction and anteversion were lower in the NSP (p < 0.001). Outliers > 10 mm from planned leg length were present in one case of the SSP and NSP, with none in the anterior groups. There were no outliers > 10° in anterior or posterior for abduction in all surgeons. The SSP had six outliers > 10° in anteversion while the NSP had none (p = 0.004); the SSA had no outliers for anteversion while the NSA had one (p = 0.500). Conclusion. Robotic arm-assisted technology allowed a newly trained surgeon to produce similarly accurate results and outcomes as experienced surgeons in anterior and posterior hip arthroplasty. Cite this article: Bone Jt Open 2021;2(6):365–370

Aims. This study aimed to investigate the incidence of ≥ 5 mm asymmetry in lower and whole leg lengths (LLs) in patients with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH-OA) and primary hip osteoarthritis (PHOA), and the relationship between lower and whole LL asymmetries and femoral length asymmetry. Methods. In total, 116 patients who underwent unilateral total hip arthroplasty were included in this study. Of these, 93 had DDH-OA and 23 had PHOA. Patients with DDH-OA were categorized into three groups: Crowe grade I, II/III, and IV. Anatomical femoral length, femoral length greater trochanter (GT), femoral length lesser trochanter (LT), tibial length, foot height, lower LL, and whole LL were evaluated using preoperative CT data of the whole leg in the supine position. Asymmetry was evaluated in the Crowe I, II/III, IV, and PHOA groups. Results. The incidences of whole and lower LL asymmetries were 40%, 62.5%, 66.7%, and 26.1%, and 21.7%, 20.8%, 55.6%, and 8.7% in the Crowe I, II/III, and IV, and PHOA groups, respectively. The incidence of tibial length asymmetry was significantly higher in the Crowe IV group (44.4%) than that in the PHOA group (4.4%). In all, 50% of patients with DDH-OA with femoral length GT and LT asymmetries had lower LL asymmetry, and 75% had whole LL asymmetry. The incidences of lower and whole LL asymmetries were 20% and 42.9%, respectively, even in the absence of femoral length GT and LT asymmetries. Conclusion. Overall, 43% of patients with unilateral DDH-OA without femoral length asymmetry had whole LL asymmetry of ≥ 5 mm. Thus, both the femur length and whole LL should be measured to accurately assess LL discrepancy in patients with unilateral DDH-OA. Cite this article: Bone Jt Open 2024;5(2):79–86

Purpose. Leg length discrepancy after total hip arthroplasty (THA) sometimes causes significant patient dissatisfaction. In consideration of the leg length after THA, leg length discrepancy is often measured using anteroposterior (AP) pelvic radiography. However, some cases have discrepancies in femoral and tibial lengths, and we believe that in some cases, true leg length differences should be taken into consideration in total leg length measurement. We report the lengths of the lower limb, femur, and tibia measured using the preoperative standing AP full-leg radiographs of the patients who underwent THA. Materials and methods. From August 2013 to February 2017, 282 patients underwent standing AP full-leg radiography before THA. Of the patients, 33 were male and 249 were female. The mean age of the patients was 65.7±9.4 years. We measured the distances between the center of the tibial plafond and lesser trochanter apex (A-L), between the femoral intercondylar notch and lesser trochanter (K-L), and between the centers of the tibial plafond and intercondylar spine of the tibia (A-K) on standing AP full-leg radiographs before THA operation. We examined the differences in leg length and the causes of these discrepancies after guiding the difference between them. Results. The mean A-L was 674±44 mm on the right and 677±43 mm on the left. The mean difference between the left and the right was 6.2±7 mm. The differences of ≥5 and ≥10 mm between the left and right were confirmed in 131 (46%) and 39 cases (14%), respectively. The mean K-L was 343±23 mm on the right and 343±23 mm on the left, with a mean difference of 4.4±4 mm. The lateral differences of ≥5 and ≥10 mm were confirmed in 88 (31%) and 22 (8%), respectively. The mean A-K was 325±22 mm on the right and 327±22 mm on the left, with a mean difference of 4±4.5 mm. The differences of ≥5 and ≥10 mm between the left and right were confirmed in 24 (9%) and 67 cases (%), respectively. Discussion. Considering the total length of the lower limbs beyond the little trochanter and the leg length after THA, we confirmed that 46% of the leg length differences of ≥5 mm were admitted to 14%. Thus, THA appeared effective. Perthes head, Crowe classifications 3 and 4, history of childhood paralysis, and so on may be factors for leg length differences beyond the lesser trochanter. Conclusion. We think that it would be preferable to prepare a preoperative plan to measure leg length after THA by measuring the total length of the lower extremity before surgery and determining the difference between the left and right sides

Abstract. OBJECTIVES. Application of deep learning approaches to marker trajectories and ground reaction forces (mocap data), is often hampered by small datasets. Enlarging dataset size is possible using some simple numerical approaches, although these may not be suited to preserving the physiological relevance of mocap data. We propose augmenting mocap data using a deep learning architecture called “generative adversarial networks” (GANs). We demonstrate appropriate use of GANs can capture variations of walking patterns due to subject- and task-specific conditions (mass, leg length, age, gender and walking speed), which significantly affect walking kinematics and kinetics, resulting in augmented datasets amenable to deep learning analysis approaches. METHODS. A publicly available (. https://www.nature.com/articles/s41597-019-0124-4. ) gait dataset (733 trials, 21 women and 25 men, 37.2 ± 13.0 years, 1.74 ± 0.09 m, 72.0 ± 11.4 kg, walking speeds ranging from 0.18 m/s to 2.04 m/s) was used as the experimental dataset. The GAN comprised three neural networks: an encoder, a decoder, and a discriminator. The encoder compressed experimental data into a fixed-length vector, while the decoder transformed the encoder's output vector and a condition vector (containing information about the subject and trial) into mocap data. The discriminator distinguished between the encoded experimental data from randomly sampled vectors of the same size. By training these networks jointly using the experimental dataset, the generator (decoder) could generate synthetic data respecting specified conditions from randomly sampled vectors. Synthetic mocap data and lower limb joint angles were generated and compared to the experimental data, by identifying the statistically significant differences across the gait cycle for a randomly selected subset of the experimental data from 5 female subjects (73 trials, aged 26–40, weighing 57–74 kg, with leg lengths between 868–931 mm, and walking speeds ranging from 0.81–1.68 m/s). By conducting these comparisons for this subset, we aimed to assess the synthetic data generated using multiple conditions. RESULTS. We visually inspected the synthetic trials to ensure that they appeared realistic. The statistical comparison revealed that, on average, only 2.5% of the gait cycle showed significantly differences in the joint angles of the two data groups. Additionally, the synthetic ground reaction forces deviated from the experimental data distribution for an average of 2.9% of the gait cycle. CONCLUSIONS. We introduced a novel approach for generating synthetic mocap data of human walking based on the conditions that influence walking patterns. The synthetic data closely followed the trends observed in the experimental data, also in the literature, suggesting that our approach can augment mocap datasets considering multiple conditions, an approach unfeasible in previous work. Creation of large, augmented datasets allows the application of other deep learning approaches, with the potential to generate realistic mocap data from limited and non-lab-based data. Our method could also enhance data sharing since synthetic data does not raise ethical concerns. You can generate and download virtual gait data using our GAN approach from . https://thisgaitdoesnotexist.streamlit.app/. . Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Angular deformities of the distal femur can be corrected by opening, closing and neutral wedge techniques. Opening wedge (OW) and closing wedge (CW) are popular and well described in the literature. CW and OW techniques lead to leg length difference whereas the advantage of neutral wedge (NW) technique has several unique advantages. NW technique maintains limb length, wedge taken from the closing side is utilised on the opening side and since the angular correction is only half of the measured wedge on either side, translation of distal fragment is minimum. Leg lengths are not altered with this technique hence a useful technique in large deformities. We found no reports of clinical outcomes using NW technique. We present a technique of performing external fixator assisted NW correction of large valgus and varus deformities of distal femur and dual plating and discuss the results. Materials & Methods. We have treated 20 (22 limbs – 2 patients requiring staged bilateral corrections) patients for distal femoral varus and valgus deformities with CWDFO between 2019 and 2022. Out of these 4 patients (5 limbs) requiring large corrections of distal femoral angular deformities were treated with Neutral Wedge (NW) technique. 3 patients (four limbs) had distal femoral valgus deformity and one distal femoral varus deformity. Indication for NW technique is an angular deformity (varus or valgus of distal femur) requiring > 12 mm opening/closing wedge correction. We approached the closing side first and marked out the half of the calculated wedge with K – wires in a uniplanar fashion. Then an external fixator with two Schanz screws is applied on the opposite side, inserting the distal screw parallel to the articular surface and the proximal screw 6–7 cm proximal to the first pin and at right angles to the femoral shaft mechanical axis. Then the measured wedge is removed and carefully saved. External fixator is now used to close the wedge and over correct, creating an appropriate opening wedge on the opposite side. A Tomofix (Depuoy Synthes) plate is applied on the closing side with two screws proximal to osteotomy and two distally (to be completed later). Next the osteotomy on the opposite side is exposed, the graft is inserted. mLDFA is measured under image intensifier to confirm satisfactory correction. Closing wedge side fixation is then completed followed by fixation of opposite side with a Tomofix or a locking plate. Results. 3 patients (4 limbs) had genu valgum due to constitutional causes and one was a case of distal femoral varus from a fracture. Preoperative mLDFA ranged from 70–75° and in one case of varus deformity it was 103°. We achieved satisfactory correction of mLDFA in (85–90°) in 4 limbs and one measured 91°. Femoral length was not altered. JLCA was not affected post correction. Patients were allowed to weight bear for transfers for the first six weeks and full weight bearing was allowed at six weeks with crutches until healing of osteotomy. All osteotomies healed at 16–18 weeks (average 16.8 weeks). Patients regained full range of movement. We routinely recommend removal of metal work to facilitate future knee replacement if one is needed. Follow up ranged from 4 months to 2 yrs. Irritation from metal work was noted in 2 patients and resolved after removing the plates at 9 months post-surgery. Conclusions. NWDFO is a good option for large corrections. We describe a technique that facilitates accurate correction of deformity in these complex cases. Osteotomy heals predictably with uniplanar osteotomy and dual plate fixation. Metal work might cause irritation like other osteotomy and plating techniques in this location

In recent years, there has been increasing interest in the use of simultaneous hip arthroplasty compared to staged procedures in patients with bilateral pathology. The aim of this study was to compare simultaneous and staged hip arthroplasty in patients with bilateral pathology by assessing the transfusion rate, postoperative hemoglobin drop, length of stay (LOS), in-hospital complications, 30-days readmissions, leg length difference and early functional outcome. We conducted a retrospective cohort study that included all patients who were undergoing primary total hip arthroplasty (THA) by a single surgeon in a high-volume arthroplasty center between 2015 and 2020 as simultaneous or staged procedures. Staged bilateral arthroplasties were performed within 12 months and were stratified by the time between procedures. Data was acquired through the electronic files at the Orthopädische Chirurgie München (OCM). For functional outcome we compared the ability of the patients to walk independently on the ward and the ability to walk a set of stairs alone which was recorded daily by the attending physiotherapist. In total n=290 patients were assessed for eligibility and included in this study. One hundred and thirty eight patients were allocated to the staged arthroplasty group. The second staged procedure was performed within 12 months of the first procedure. One hundred and fifty two patients were allocated to the simultaneous arthroplasty group. No statistical difference was found between the two groups regarding demographic data. Primary outcome measurements: There was no significant difference in transfusion rate or complication rate (p=0.1147). In both groups the transfusion rate was actually 0%. Secondarily, no statistically significant difference was found between the postoperative hemoglobin drop (p=0.1147) and the functional outcome (p=0.7249), nor the length of stay (LOS) (p=: 0.6415), as well as the 30 days readmission rate between both groups. No difference was found in leg length in the simultaneous group. The OR time in the simultaneous group ranged from 62min to 111min with an average of 77min. No surgery exceeded a 120min window. We observed no significant differences in transfusion rate, in hospital complications, as well as readmission rate between both groups. The early functional outcome showed no significant difference in mobility. Simultaneous hip arthroplasty is as safe as a staged procedure, with no higher risk for the patient, in a specialized high volume center with a specialized surgeon and an adequate team. Level of evidence: Level IV

Preoperative planning is a crucial step for total hip arthroplasty (THA), and 2D X-ray images are commonly used. The planning aims to provide the correct implant size, restore functional biomechanical conditions and avoid early complication such as dislocation, leg length discrepancy or abductors insufficiency. Limitations of 2D planning, besides the low accuracy in sizing, concerns the inability of planning the anteversion of both acetabular and femoral component on axial plane. Also, the verification of the planning intraoperatively is wholly left to qualitative measurements and the surgeon's experience. The need for having a more accurate and functional preoperative planning has been addressed using 3D models. The MyHip Planner (MHP) (Medacta International, Castel San Pietro, Switzerland), is a preoperative planning software which through artificial intelligent algorithm converts the CT scans into a 3D model that perfectly match the patient's anatomy. Then, automatic positioning of the implants is performed following the personal settings of the surgeon which will check and validate the planning, a personalized simulation of six daily activities to detect impingement of implants and bones. The MyHip Verifier (MHV) intraoperatively verifies the execution of the planning in terms of leg length and offset using two fluoroscopic images. Also, the size and cup angles can be calculated. The purpose of the present study was to validate the accuracy of the MHP [Fig 1] and MHV [Fig 2]. The dataset consisted of 13 patients who underwent primary uncemented THA. Each patient had a preoperative CT scan, intraoperative fluoroscopy, and postoperative CT scan after the surgery. The CT protocol used was low radiation (0,2 mm slicing for the pelvis, 0,5 mm for knees and ankles). The patients have been preoperatively planned used the MPH, and the accuracy of the components size prediction has been evaluated by comparing the preoperative planned values with the surgical reports. The MVH calculated the leg length and offset in terms of the difference between the preoperative and postoperative position of the femur concerning the pelvis. The accuracy of the measurements has been evaluated using postoperative CT scans. The MPH was able to predict the implanted size in 83% of the patient for the femoral stem and 96% for the acetabular component. The accuracy of the MVH in measuring the leg length was under 2 mm (1,6 ± 0,7 mm) while the offset was 2,5±1,6 mm. The cup angles were 5±1,1deg and 2,3±1,3deg for the anteversion and inclination, respectively. The average cup anteversion was 28,3°, mean cup inclination was 42,6°; femoral offset and leg length was restored in 96,5% of patients within a range of ±3 mm concerning the preoperative position. The results demonstrated the reliability of the MPH in predicting the implant size, and the accuracy of the MVH to verify the execution of the plan intraoperatively. The two software can be used in the clinical routine to improve the clinical outcome in THA. Limitations of this study are represented mainly by the small cohort of patients involved. For any figures or tables, please contact the authors directly

Introduction. The most challenging aspect in rotational deformity correction is translating the pre-operative plan to an accurate intra-operative correction. Landmarks away from the osteotomy site are typically employed at pre-operative planning and this can render inadequate correction. Our proposed technique of pre-operative planning using CT scan and leg length radiographs can translate to accurate intra-operative correction. Materials and Methods. A circle was superimposed at osteotomy site with its centre serving as the centre of correction of rotation. Medio-lateral distance at osteotomy site measured and used as diameter of the circle. Circumference of the circle was calculated by multiplying diameter with Pi and used in the below formula to obtain accurate de-rotation distance;. Derotation distance = (Circumference/360) × correction value for desired ante-version. The exact site of osteotomy was measured in theatre under C-arm and exposed. Derotation distance was marked on the surface of bone as point A and point B with a flexible ruler. Osteotomy performed with saw and derotation was done till point A and point B were co-linear. Derotation distance obtained using this technique is specific for the site of chosen osteotomy and implies a specific degree of correction for every millimeter derotated. Distal femur was the chosen site of osteotomy if there was associated patellar instability and proximal femur if there was no patellar instability. Results. We have used the above technique to successfully correct rotational malalignment of femur and tibia in three patients thus far. The foot progression angle improved in all patients following surgery. One patient had post-operative CT scan of the hips which showed accurate reduction of ante-version. Conclusions. Our new technique of rotational deformity correction is simple and reproducible using commonly available tools as CT scan and leg length radiographs. This technique effectively translates the pre-operative plan to accurate intra-operative correction of rotational deformity

Aims. Hip arthroplasty does not always restore normal anatomy. This is due to inaccurate surgery or lack of stem sizes. We evaluated the aptitude of four total hip arthroplasty systems to restore an anatomical and medialized hip rotation centre. Methods. Using 3D templating software in 49 CT scans of non-deformed femora, we virtually implanted: 1) small uncemented calcar-guided stems with two offset options (Optimys, Mathys), 2) uncemented straight stems with two offset options (Summit, DePuy Synthes), 3) cemented undersized stems (Exeter philosophy) with three offset options (CPT, ZimmerBiomet), and 4) cemented line-to-line stems (Kerboul philosophy) with proportional offsets (Centris, Mathys). We measured the distance between the templated and the anatomical and 5 mm medialized hip rotation centre. Results. Both rotation centres could be restored within 5 mm in 94% and 92% of cases, respectively. The cemented undersized stem performed best, combining freedom of stem positioning and a large offset range. The uncemented straight stem performed well because of its large and well-chosen offset range, and despite the need for cortical bone contact limiting stem positioning. The cemented line-to-line stem performed less well due to a small range of sizes and offsets. The uncemented calcar-guided stem performed worst, despite 24 sizes and a large and well-chosen offset range. This was attributed to the calcar curvature restricting the stem insertion depth along the femoral axis. Conclusion. In the majority of non-deformed femora, leg length, offset, and anteversion can be restored accurately with non-modular stems during 3D templating. Failure to restore hip biomechanics is mostly due to surgical inaccuracy. Small calcar guided stems offer no advantage to restore hip biomechanics compared to more traditional designs. Cite this article: Bone Jt Open 2021;2(7):476–485

We investigated whether a novel, real-time fluoroscopy based navigation system optimized component positioning and leg length in fluoroscopically aided Direct Anterior Approach Total Hip Arthroplasty (DAA-THA). We retrospectively reviewed 75 fluoroscopically assisted DAA-THA performed by a single surgeon: 37 procedures used the software intraoperatively to overlay anteversion, inclination, and leg length information over the existing fluoroscopic radiograph with the aim of enhancing component positioning. The control group consisted of 38 procedures from the single surgeon's patient pool who had undergone non-navigated fluoroscopic assisted DAA-THA one month prior to the system's trial. We used the software to compute each data point on an immediate post operative AP radiograph to replicate the intra operative measurement process. Our results demonstrate that the navigation group measurements were significantly closer to the target numbers with less variation. The mean values were significantly closer to target values anteversion (control: 14°, navigated: 19.1°), inclination (control: 37.7°, navigated: 40.8°) and leg length discrepancy (control: 4.7mm, navigated: 0.1mm). The mean difference from target value were also statistically significant: for anteversion (control: −6.0°, navigated: −0.9°), inclination (control: −2.3°, navigated: 0.8°) and leg length discrepancy (control: 2.7°, navigated: −1.9°). In addition, surgical time was shorter in the navigation group (75.7 vs. 74 minutes; p=0.001). The p values were all statistically significant (anteversion 0.0001, inclination 0.0019, LLD < 0.001 and surgical time 0.001). The real-time feedback and calculations provided by the navigation software provided a reproducible precision for component positioning and leg length measurement during DAA-THA. For any figures or tables, please contact authors directly

Infected non-unions of proximal femoral fractures are difficult to treat. If debridement and revision fixation is unsuccessful, staged revision arthroplasty may be required. Non-viable tissue must be resected, coupled with the introduction of an antibiotic-eluting temporary spacer prior to definitive reconstruction. Definitive tissue microbiological diagnosis and targeted antibiotic therapy are required. In cases of significant proximal femoral bone loss, spacing options are limited. We present a case of a bisphosphonate-induced subtrochanteric fracture that progressed to infected non-union. Despite multiple washouts and two revision fixations, the infection remained active with an unfavourable antibiogram. The patient required staged revision arthroplasty including a proximal femoral resection. To enable better function by maintaining leg length and offset, a custom-made antibiotic-eluting articulating temporary spacer, the Cement-a-TAN, was fabricated. Using a trochanteric entry cephalocondylar nail as a scaffold, bone cement was moulded in order to fashion an anatomical, patient-specific, proximal femoral spacer. Following resolution of the infection, the Cement-a-TAN was removed and a proximal femoral arthroplasty was successfully performed. Cement-a-TAN is an excellent temporary spacing technique in staged proximal femoral replacement for infected non-union of the proximal femur where there has been significant bone loss. It preserves mobility and maintains leg length, offset and periarticular soft-tissue tension

Aims. There is little information in the literature about the use of dual-mobility (DM) bearings in preventing re-dislocation in revision total hip arthroplasty (THA). The aim of this study was to compare the use of DM bearings, standard bearings, and constrained liners in revision THA for recurrent dislocation, and to identify risk factors for re-dislocation. Methods. We reviewed 86 consecutive revision THAs performed for dislocation between August 2012 and July 2019. A total of 38 revisions (44.2%) involved a DM bearing, while 39 (45.3%) and nine (10.5%) involved a standard bearing and a constrained liner, respectively. Rates of re-dislocation, re-revision for dislocation, and overall re-revision were compared. Radiographs were assessed for the positioning of the acetabular component, the restoration of the centre of rotation, leg length, and offset. Risk factors for re-dislocation were determined by Cox regression analysis. The modified Harris Hip Scores (mHHSs) were recorded. The mean age of the patients at the time of revision was 70 years (43 to 88); 54 were female (62.8%). The mean follow-up was 5.0 years (2.0 to 8.75). Results. DM bearings were used significantly more frequently in elderly patients (p = 0.003) and in hips with abductor deficiency (p < 0.001). The re-dislocation rate was 13.2% for DM bearings compared with 17.9% for standard bearings, and 22.2% for constrained liners (p = 0.432). Re-revision-free survival for DM bearings was 84% (95% confidence interval (CI) 0.77 to 0.91) compared with 74% (95% CI 0.67 to 0.81) for standard articulations, and 67% (95% CI 0.51 to 0.82) for constrained liners (p = 0.361). Younger age (hazard ratio (HR) 0.92 (95% CI 0.85 to 0.99); p = 0.031), lower comorbidity (HR 0.44 (95% CI 0.20 to 0.95); p = 0.037), smaller heads (HR 0.80 (95% CI 0.64 to 0.99); p = 0.046), and retention of the acetabular component (HR 8.26 (95% CI 1.37 to 49.96); p = 0.022) were significantly associated with re-dislocation. All DM bearings which re-dislocated were in patients with abductor muscle deficiency (HR 48.34 (95% CI 0.03 to 7,737.98); p = 0.303). The radiological analysis did not reveal a significant relationship between restoration of the geometry of the hip and re-dislocation. The mean mHHSs significantly improved from 43 points (0 to 88) to 67 points (20 to 91; p < 0.001) at the final follow-up, with no differences between the types of bearing. Conclusion. We found that the use of DM bearings reduced the rates of re-dislocation and re-revision in revision THA for recurrent dislocation, but did not guarantee stability. Abductor deficiency is an important predictor of persistent instability. Cite this article: Bone Joint J 2024;106-B(5 Supple B):89–97

Hip abductor deficiency (HAD) associated with hip arthroplasty can be a chronic, painful condition that can lead to abnormalities in gait and instability of the hip. HAD is often confused with trochanteric bursitis and patients are often delayed in diagnosis after protracted courses of therapy and steroid injection. A high index of suspicion is subsequently warranted. Risk factors for HAD include female gender, older age, and surgical approach. The Hardinge approach is most commonly associated with HAD because of failure of repair at the time of index surgery or subsequent late degenerative or traumatic rupture. Injury to the superior gluteal nerve at exposure can also result in HAD and is more commonly associated with anterolateral approaches. Multiple surgeries, chronic infection, and chronic inflammation from osteolysis or metal debris are also risk factors especially as they can result in bone stock deficiency and direct injury to muscle. Increased offset and/or leg length can also contribute to HAD, especially when both are present. Physical exam demonstrates abductor weakness with walking and single leg stance. There is often a palpable defect over the greater trochanter and palpation in that area usually elicits significant focal pain. Note may be made of multiple incisions. Increased leg length may be seen. Radiographs may demonstrate avulsion of the greater trochanter or significant osteolysis. Significant polyethylene wear or a metal-on-metal implant should be considered as risk factors, as well as the presence of increased offset and/or leg length. Ultrasound or MRI are helpful in confirming the diagnosis but false negatives and positive results are possible. Treatment is difficult, especially since most patients have failed conservative management before diagnosis of HAD is made. Surgical options include allograft and mesh reconstruction as well as autologous muscle transfers. Modest to good results have been reported, but reproducibility is challenging. In the case of increased offset and leg length, revision of the components to reduce offset and leg length may be considered. In the case of significant instability, abductor repair may require constrained or multi-polar liners to augment the surgical repair. HAD is a chronic problem that is difficult to diagnose and treat. Detailed informed consent appropriately setting patient expectations with a comprehensive surgical plan is required if surgery is to be considered. Be judicious when offering this surgery

Restoring native hip anatomy and biomechanics is important to create a well-functioning total hip arthroplasty (THA). Hip offset and leg length are regarded as the most important biomechanical characteristics. This study investigated their association with clinical outcomes including patient reported outcome measures (PROMs) and functional tests. This prospective cohort study was conducted in 77 patients undergoing primary THA (age=65±11 years). Hip offset and leg length were measured on anteroposterior radiographs of the hip pre- and postoperatively. Participants completed the Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC) and performed functional tests (i.e. gait, single leg stance, sit-to-stand, block step-up) preoperatively, and 3 and 12 months postoperatively. A wearable motion sensor was used to derive biomechanical parameters. Associations between radiographic and functional outcomes were investigated with the Spearman's rho correlation coefficient. Subgroup comparisons were conducted for patients with more than 15% decreased or increased femoral offset after THA. Differences in postoperative offset and leg length had little impact on clinical outcomes. Femoral offset subgroups demonstrated no significantly different WOMAC function scores. In functional tests, patients with >15% decreased femoral offset after THA demonstrated more sagittal plane motion during block step-up (14.43° versus 10.66°; p=0.04) while patients with >15% increased femoral after THA demonstrated more asymmetry of frontal plane motion during block step-up (34.05% versus 14.18%; p=0.03). To create a well-functioning THA, there seems to be a reasonable safe zone regarding the reconstruction of offset and leg length

Aims. Cement-in-cement revision of the femoral component represents a widely practised technique for a variety of indications in revision total hip arthroplasty. In this study, we compare the clinical and radiological outcomes of two polished tapered femoral components. Methods. From our prospectively collated database, we identified all patients undergoing cement-in-cement revision from January 2005 to January 2013 who had a minimum of two years' follow-up. All cases were performed by the senior author using either an Exeter short revision stem or the C-Stem AMT high offset No. 1 prosthesis. Patients were followed-up annually with clinical and radiological assessment. Results. A total of 97 patients matched the inclusion criteria (50 Exeter and 47 C-Stem AMT components). There were no significant differences between the patient demographic data in either group. Mean follow-up was 9.7 years. A significant improvement in Oxford Hip Score (OHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and 12-item Short-Form Survey (SF-12) scores was observed in both cohorts. Leg lengths were significantly shorter in the Exeter group, with a mean of -4 mm in this cohort compared with 0 mm in the C-Stem AMT group. One patient in the Exeter group had early evidence of radiological loosening. In total, 16 patients (15%) underwent further revision of the femoral component (seven in the C-Stem AMT group and nine in the Exeter group). No femoral components were revised for aseptic loosening. There were two cases of femoral component fracture in the Exeter group. Conclusion. Our series shows promising mid-term outcomes for the cement-in-cement revision technique using either the Exeter or C-Stem AMT components. These results demonstrate that cement-in-cement revision using a double or triple taper-slip design is a safe and reliable technique when used for the correct indications. Cite this article: Bone Joint J 2021;103-B(7):1215–1221

Custom 3D printed implants can be anatomically designed to assist in complex surgery of the bony pelvis in both orthopaedic oncology and orthopaedic reconstruction surgery. This series includes patients who had major pelvic bone loss after initially presenting with tumours, fractures or infection after previous total hip arthroplasty. The extent of the bone loss in the pelvis was severe and therefore impossible to be reconstructed by conventional ‘off –the-shelve’ implants. The implant was designed considering the remaining bony structures of the contra-lateral hemi- pelvis, to provide an anatomical, secured support for the reconstructed hip joint. The latter was realised by strategically orientated screws and by porous structures (an integral part of the implant), which stimulates osseointegration. A custom pelvic implant was designed, manufactured and 3D printed. Reconstruction of the pelvis was performed together with a cemented (bipolar bearing) acetabular cup. In some cases, a proximal femoral replacement was also necessary to compensate for bony defects. All patients had sufficient range of motion (ROM) at the hip with post-operative stability. It has been verified, at six and twelve months postoperatively, that there is a strong hold of the implant due to osseointegration. Additionally, in patients whose posterior acetabular wall was missing, it was discovered that the implant assisted in bone formation and covered the entire posterior surface of the implant. All patients in this study managed with this novel treatment option, proved to have a stable pelvic reconstruction with restoration of leg lengths, improvement of strength and independent ambulation at short and medium term follow-up

Introduction. Coronal malalignment and leg length discrepancies (LLD) are frequently associated. Temporary hemiepiphysiodesis (tHED) is commonly employed for the correction of limb malalignment in skeletally immature patients. For treatment of LLD greater than 2 cm, lengthening with intramedullary legnthening nails is a safe and reliable technique. However, the combined application of these approaches in skeletally immature patients has not yet been investigated. Materials & Methods. Retrospective radiological and clinical analysis of 25 patients (14 females, 11 males) who underwent intramedullary femoral lengthening with an antegrade PRECICE® lengthening nail as well as tHED of the distal femur and / or proximal tibia between 2014 and 2019. tHED was conducted by implantation of flexible staples (FlexTack™) either prior (n = 11), simultaneously (n = 10), or subsequently (n = 4) to femoral lengthening. The mean follow-up period was 3.7 years (±1.4). Results. The median initial LLD was 39.0 mm (35.0–45.0). 21 patients (84%) presented valgus and 4 (16%) showed varus malalignment. Leg length equalization was achieved in 13 patients at skeletal maturity (62%). The median LLD of patients with a residual LLD > 10 mm was 15.5 mm (12.8–21.8). Limb realignment was obtained in nine of seventeen skeletally mature patients (53%) in the valgus group, and in one of four patients (25%) in the varus group. Conclusions. The combination of antegrade femoral lengthening and tHED can efficiently correct LLD and coronal limb malalignment in skeletally immature patients. Nevertheless, achieving limb length equalization and realignment may render difficult in cases of severe LLD and angular deformity. Furthermore, the reported techniques ought to be thoroughly planned and executed and require regular clinical and radiological examinations until skeletal maturity to avoid - or timely detect and manage - adverse events such as overcorrection and rebound of deformity

Vacuum orthoses are being applied in the care of patients with foot and lower leg conditions, as ankle fractures or sprains. The lower leg is protected and immobilized, which increases mobility. Due to the design, the orthoses lead to a difference in leg length, i.e. the side with the orthosis becomes longer, which changes the gait kinematics. To prevent or mitigate the unfavourable effects of altered gait kinematics, leg length-evening devices (shoe lifts) are offered that are worn under the shoe on the healthy side. Our aim was to evaluate the effect of such a device on the normality of gait kinematics. Gait analysis was conducted with 63 adult, healthy volunteers having signed an informed consent form that were asked to walk on a treadmill at a speed of 4.5km/h in three different conditions:. barefoot - as reference for establishing the normality score baseline. with a vacuum orthosis (VACOPed, OPED GmbH, Germany) and a sport shoe. with a vacuum orthosis and a shoe lift (EVENup, OPED GmbH, Germany). Data was sampled using the gait analysis system MCU 200 (LaiTronic GmbH, Austria). The positions of the joint markers were exported from the software and evaluated for the joint angles during the gait cycle using custom software (implemented in DIAdem 2017, National Instruments). A normality score using a modification of the Gait Profile Score (GPS) was calculated in every 1%-interval of the gait cycle and evaluated with a Wilcoxon signed rank test. The GPS value was reduced by 0.33° (0.66°) (median and IQR) while wearing the shoe lift. The effect was statistically significant, and very large (W = 1535.00, p < .001; r (rank biserial) = 0.52, 95% CI [0.29, 0.70]). The significant reduction of the GPS value indicates a more normal gait kinematics while using the leg length-evening device on the contralateral shoe. This rather simple and inexpensive device thus might improve patient comfort and balance while using the vacuum orthoses

To investigate differences in the drop vertical jump height in female adolescents with an ACL injury and healthy controls and the contribution of each limb in this task. Forty female adolescents with an ACL injury (ACLi, 15.2 ± 1.4 yrs, 164.6 ± 6.0 cm, 63.1 ± 10.0 kg) and thirty-nine uninjured (CON, 13.2 ± 1.7 yrs, 161.7 ± 8.0 cm, 50.6 ± 11.0 kg) were included in this study. A 10-camera infrared motion analysis system (Vicon, Nexus, Oxford, UK) tracked pelvis, thigh, shank, and foot kinematics at 200Hz, while the participants performed 3 trials of double-legged drop vertical jumps (DVJ) on two force plates (Bertec Corp., Columbus, USA) sampled at 2000Hz.The maximum jump height normalised by dominant leg length was compared between groups using independent samples t-test. The maximum vertical ground reaction force (GRFz) and sagittal ankle, knee and hip velocities before take-off were compared between limbs in both groups, using paired samples t-test. The normalised jump height was 11% lower in the ACLi than in the CON (MD=0.04 cm, p=0.020). In the ACLi, the maximum GRFz (MD=46.17N) and the maximum velocities of ankle plantar flexion (MD=79.83°/s), knee extension (MD=85.80°/s), and hip extension (MD=36.08°/s) were greater in the non-injured limb, compared to the injured limb. No differences between limbs were found in the CON. ACL injured female adolescents jump lower than the healthy controls and have greater contribution of their non-injured limb, compared to their injured limb, in the DVJ task. Clinicians should investigate differences in the contribution between limbs during double-legged drop vertical jump when assessing patients with an ACL injury, as this could help identify asymmetries, and potentially improve treatment, criteria used to clear athletes to sport, and re-injury prevention

Dual-mobility (DM) bearings are effective to mitigate dislocation in revision total hip arthroplasty (THA). However, data on its use for treating dislocation is scarce. Aim of this study was to compare DM bearings, standard bearings and constrained liner (CL) in revision THA for recurrent dislocation and to identify risk factors for re-dislocation. We reviewed 100 consecutive revision THAs performed for dislocation from 2012 and 2019. 45 hips (45%) received a DM construct, while 44 hips (44%) and 11 hips (11%) had a standard bearing and CL, respectively. Rates of re-dislocation, re-revision for dislocation and overall re-revision were compared. Radiographs were assessed for cup positioning, restoration of centre of rotation, leg length and offset. Risk factors for re-dislocation were determined by cox regression analysis. Modified Harris hip scores (mHHS) were calculated. Mean follow-up was 53 months (1 to 103). DM constructs were used more frequently in elderly patients (p=0.011) and hips with abductor deficiency (p< 0.001). The re-dislocation rate was 11.1% for DM bearings compared with 15.9% for standard bearings and 18.2% for CL (p=0.732). Revision-free survival for DM constructs was 83% (95% CI 0.77 – 0.90) compared to 75% (95% CI 0.68 – 0.82) for standard articulations and 71% (95% CI 0.56 – 0.85) for CL (p=0.455). Younger age (HR 0.91; p=0.020), lower comorbidity (HR 0.42; p=0.031), smaller heads (HR 0.80; p=0.041) and cup retention (HR 8.23; p=0.022) were associated with re-dislocation. Radiological analysis did not reveal a relationship between restoration of hip geometry and re-dislocation. mHHS significantly improved from 43.8 points to 65.7 points (p<0.001) with no differences among bearing types. Our findings suggest that DM bearings do not sufficiently prevent dislocation in revision THA for recurrent dislocation. Reconstruction of the abductor complex may play a key role to reduce the burden in these high-risk patients

To investigate if the countermovement jump height differs between ACL injured and uninjured female adolescents and to explore kinematic differences between limbs. Additionally, the association between isometric knee extension strength and jump height was investigated. Thirty-one ACL injured female adolescents (ACLi, 15.3 ± 1.4yrs, 163.9 ± 6.6cm, 63.0 ± 9.3kg) and thirty-eight uninjured (CON, 13.2±1.7yrs, 161.7 ± 8.1cm, 50.6 ± 11.1kg) participated in this study. All participants performed a countermovement jump task, with 3D kinematics collected using a motion analysis system (Vicon, Nexus, Oxford, UK) at 200Hz, and a maximum isometric knee extension task on an isokinetic dynamometer (Biodex Medical Systems, New York, USA) for three trials. The peak torque was extracted from the isometric trials. Independent samples t-test compared the maximum jump height normalised by the dominant leg length between groups, paired samples t-test compared the maximum hip and knee extension and ankle plantar flexion velocities before take-off between limbs in both groups, and a Pearson's correlation test investigated the association between the isometric knee extension strength and jump height. The ACLi jumped 13% lower compared to the CON (p=0.022). In the ACLi, the maximum hip and knee extension and ankle plantar flexion velocities were greater in the non-injured limb, compared to the injured limb; however, no differences between limbs were found in the CON. The isometric knee extension strength of both limbs was positively correlated with jump height (limb 1: r=0.329; p=0.006, and limb 2: r=0.386; p=0.001; whereas limb 1 corresponds to the ACLi injured limb and CON non-dominant limb, and limb 2 to the ACLi non-injured limb and CON dominant limb). ACL injured female adolescents present lower jump height than controls and greater contribution of their non-injured limb, compared to their injured limb, during a countermovement jump task. Also, current results indicate that jump height is positively related to isometric knee extension strength measure

In the congenital hip dysplasia, patients treated with total hip replacement (THR) often report persistent disability and pain, with unsatisfactory function and quality of life. A major challenge is to restore the center of rotation of the hip and a satisfactory abduction function [1]. The position of the acetabular cup during THR might be crucial, as it affects abduction moment and motor function. Recently, several software systems have been developed for surgical planning of endoprostheses. Previously developed software called HipOp [2], which is routinely used in clinics, allows surgeons to properly position the prosthetic components into the 3D space of CT data. However, this software did not allow to simulate the articular range of motion and the condition of the abductor muscles. Our aim is to present HipOpCT, an advanced version of the software that includes 3D musculoskeletal planning, through the application to hip dysplasia patients to add knowledge in the diagnosis and treatment of such patients who need THR. 40 hip dysplasia patients received pre-operative CT scanning of pelvis and thighs and had their THR surgery planned using HipOpCT. The base planning includes import of CT data, positioning of prosthetic components interactively through multimodal display, as well as geometrical measurements of the implant and the host bone. The advanced planning additionally includes evaluation of femoro-acetabular impingement and calculation of leg lengths, abductor muscle lengths and lever arms through the automatic creation of a musculoskeletal model. The musculoskeletal parameters in all patients were calculated during the surgical planning, and the data were processed to evaluate pre- and post-operative differences in leg length discrepancy, length and lever arm of the abductor muscles, and how these parameters correlated. The surgical planning led to an increase in the operated leg length of 7.6 ± 5.7 mm. The variation in abductors lever arm was −0.9% ± 4.8% and significantly correlated with the variation in the operated leg length (r = −0.49), pre-operative leg length discrepancy (r = 0.32) and variation in abductors length (r = −0.32). The variation in abductors length was 6.6% ± 5.5%, and significantly correlated with the variation in the operated leg length (r = 0.92), post-operative leg length discrepancy (r = 0.37), pre-operative abductors length (r = −0.37) and variation in abductors lever arm (r = −0.32). The increase in the operated leg length was strongly correlated to the increase in abductor muscle length. Conversely, abductor lever arms slightly decreased on average, and were inversely correlated to leg length variation and abductors lengths. This interactive technology for surgical planning represent a powerful tool for orthopaedic surgeons to consider the best muscle reconstruction, and for rehabilitation specialists to achieve the best functional recovery based on biomechanical outcomes. In a parallel study, we are investigating how these advanced planning is reflected onto the function, pain and biomechanical outcome after a rehabilitation protocol is completed

Introduction. When performing a total hip arthroplasty (THA), some surgeons routinely perform an intraoperative anteroposterior (AP) pelvis radiograph to assess components. The purpose of this study was to evaluate the reliability of the intraoperative radiograph to accurately reflect acetabular inclination, leg length, and femoral offset as compared to the immediate postoperative supine AP radiograph. Methods. The intraoperative (lateral decubitus position) and immediate postoperative (supine position) AP pelvis x-rays of 100 consecutive patients undergoing primary THA were retrospectively reviewed. Acetabular inclination, leg length, and femoral offset were measured on both radiographs. We analyzed the correlation coefficient of the recorded measurements between the two films as well as the interobserver reliability of each measurement obtained. Results. Our data demonstrated a high positive correlation between the intraoperative and postoperative acetabular inclination measurements of both reviewers (r=.886 and .896). In addition, no significant difference was observed between the inclination measurements (p= .06 and .37). There was a moderate correlation among the leg length (r= .58 and .66) and poor correlation among the offset (r= .29 and .25) between the two radiographs. One observer generated a significant difference between leg length measurements while both reviewers generated a significant difference between offset measurements. Interobserver reliability was high for all measurements. Conclusion. Intraoperative AP radiographs are commonly obtained during THA to aid in evaluation of component position and size, femoral neck cut, femoral canal fill, and detection of occult fractures. Results from this study suggest that this film could also be used to accurately measure acetabular inclination, but is a less reliable indicator of femoral offset and leg length when compared to the immediate postoperative film. In addition, the high interobserver correlation illustrates the high reproducibility of the measurement methods utilized

Introduction. Aneurysmal bone cysts commonly found in lower limbs are locally aggressive masses that can lead to bony erosion, instability and fractures. This has major implications in the lower limbs especially in paediatric patients, with potential growth disturbance and deformity. In this case series we describe radical aneurysmal bone cyst resection and lower limb reconstruction using cable transport and syndesmosis preservation. Materials & Methods. Case 1 - A 12-year-old boy presented with a two-week history of atraumatic right ankle pain. An X-ray demonstrated a distal tibia metaphyseal cyst confirmed on biopsy as an aneurysmal bone cyst. The cyst expanded on interval X-rays from 5.5cm to 8.5cm in 9 weeks. A wide-margin en-bloc resection was performed leaving a 13.8cm tibial defect. A cable transport hexapod frame and a proximal tibial osteotomy was performed, with syndesmosis screw fixation. The transport phase lasted 11 months. While in frame, the boy sustained a distal femur fracture from a fall. The femur and the docking site were plated at the same sitting and frame removed. At one-year post-frame removal he is pain-free, with full ankle dorsiflexion but plantarflexion limited to 25 degrees. He has begun graduated return to sport. Results. Case 2 - A 12-year-old girl was referred with a three-month history of lateral left ankle swelling. X-ray demonstrated an aneurysmal bone cyst in the distal fibula metaphysis. The cyst grew from 4.2 × 2.3cm to 5.2 × 3.32cm in 2 months. A distal fibula resection (6.2cm) with syndesmosis fixation and hexapod cable transport frame were undertaken. The frame was in situ for 13 weeks and during this time she required an additional osteotomy for premature consolidation and had one pin site infection. After 13 weeks a second syndesmosis screw was placed, frame removed, and a cast applied. 3 months later she had fibular plating, BMAC and autologous iliac crest bone graft for slow union. At 3 years post-operative she has no evidence of recurrence, is pain-free and has no functional limitation. Conclusions. We describe two cases of ankle syndesmosis preservation using cable transport for juxta-articular aneurysmal bone cysts. This allows wide resection to prevent recurrence while also preserving primary ankle stability and leg length in children. Both children had a minor complication, but both had an excellent final outcome. Cable bone transport and prophylactic syndesmosis stabilization allows treatment of challenging juxta-articular aneurysmal bone cysts about the ankle. These techniques are especially useful in large bone defects

Restoration of anatomy is paramount in total hip arthroplasty (THA) to optimise function and stability. Leg-length discrepancy of ≥10mm is poorly tolerated and can be the subject of litigation. We routinely use a multimodal protocol to optimise soft tissue balancing which involves pre-operative templating, leg-length measurement supine and in the lateral position after positioning, and the use of an intra-operative leg-length measurement device to ensure optimisation of leg-length. We have analysed the results of our protocol in restoring leg-length in primary THA. Radiological leg-length was measured in a consecutive series of 50 patients who had THA for unilateral arthritis by an independent observer pre- and post-operatively using validated methods utilising radiological software. The measurements pre- and post-operative were compared. Patients with bilateral hip arthritis and poor imaging were excluded. Leg-length was successfully restored to within 5.0mm of the target leg-length in 84.0% of patients (mean +0.7mm (95% CI +0.2 to +1.1)). The other 14.0% of patients were restored to within 5.1–8.0mm (mean +2.2mm (95% CI −2.7 to +7.1)) and 2.0% of patients were restored to within 8.1–10.0mm. Leg length was accurately restored across the subset of patients within a narrow range of either side of the mean target leg length. Intra-operative measurement of leg length can be difficult but is vital in ensuring appropriate restoration of leg-length. We recommend a similar multimodal protocol to ensure restoration of leg-length within narrow limits to maximise function and patient satisfaction

Introduction. Correct postoperative leg length restoration is among the most important goals of hip arthroplasty. Therefore, we developed, validated and clinically applied a novel software algorithm based on surgical navigation, which allows the surgeon to restore a defined femur position without establishing a femoral coordinate system or the hip joint center and measure the leg length accurately and simply. Material and Methods. This new leg length algorithm was used in 154 hips (145 patients) that underwent CT-based computer-assisted THA (VectorVision Build 274 prototype; BrainLAB AG, Helmstetten, Germany) with a tissue preserving superior capsulotomy. Intraoperatively, a pelvic and a femoral dynamic reference bases (DRB) were applied and the anterior pelvic plane (APP) was set as the pelvic coordinate system. Then, the hip joint was put in a neutral position and this position, and the relative position of the femoral DRB relative to the pelvic DRB, was captured and stored by the navigation system. After implantation of the prosthesis the same above described femoral position with the same amplitude of flexion/extension, abduction/adduction and rotation was restored. Now, any resulting difference was due to linear changes. Validation of this new algorithm was performed by comparing the navigated results to measurements from calibrated antero-posterior pre- and postoperative radiographs. The radiographic results were compared to the mean leg length change measured with the navigation system. Results. No significant difference was found between radiographic leg length change and the results from the navigation system (p=0.658). The mean difference between the radiographic results and the results from the navigation system was −0.5 (1–8 mm (range, −5–4 mm). The mean registration accuracy of the navigation system was 2.04 (0.58 mm (range, 0.70–3.00 mm). Discussion. This novel tool has the potential to increase the accuracy and consistency of leg-length change measurement during hip arthroplasty. Improved methods of measuring leg length change during surgery are even more critical now, when smaller incisions are being used, because traditional mechanical measurement methods are potentially even more unreliable than they are when larger exposures are used. This current method of measuring leg length change eliminates the need to calculate the center of rotation of the arthritic hip joint, which is often not accurately possible, and eliminates the need to establish a femoral coordinate system, which can be time consuming and frustrating. Besides registration accuracy, validation with plain radiographs is another potential source of error. Nonetheless, there was a substantial agreement between the radiographic results and the results from the navigation system. This novel computer-assisted method represents an accurate and simple tool for intraoperative leg length measurement

Aims. Iliopsoas pathology is a relatively uncommon cause of pain following total hip arthroplasty (THA), typically presenting with symptoms of groin pain on active flexion and/or extension of the hip. A variety of conservative and surgical treatment options have been reported. In this retrospective cohort study, we report the incidence of iliopsoas pathology and treatment outcomes. Methods. A retrospective review of 1,000 patients who underwent THA over a five-year period was conducted, to determine the incidence of patients diagnosed with iliopsoas pathology. Outcome following non-surgical and surgical management was assessed. Results. In all, 24 patients were diagnosed as having developed symptomatic iliopsoas pathology giving an incidence of 2.4%. While the mean age for receiving a THA was 65 years, the mean age for developing iliopsoas pathology was 54 years (28 to 67). Younger patients and those receiving THA for conditions other than primary osteoarthritis were at a higher risk of developing this complication. Ultrasound-guided steroid injection/physiotherapy resulted in complete resolution of symptoms in 61% of cases, partial resolution in 13%, and no benefit in 26%. Eight out of 24 patients (who initially responded to injection) subsequently underwent surgical intervention including tenotomy (n = 7) and revision of the acetabular component (n = 1). Conclusion. This is the largest case series to estimate the incidence of iliopsoas pathology to date. There is a higher incidence of this condition in younger patients, possibly due to the differing surgical indications. Arthoplasty for Perthes' disease or developmental dysplasia of the hip (DDH) often results in leg length and horizontal offset being increased. This, in turn, may increase tension on the iliopsoas tendon, possibly resulting in a higher risk of psoas irritation. Image-guided steroid injection is a low-risk, relatively effective treatment. In refractory cases, tendon release may be considered. Patients should be counselled of the risk of persisting groin pain when undergoing THA. Cite this article: Bone Joint J 2021;103-B(2):305–308

The MAKO Robotic arm is a haptic robotic system that can be used to optimise performance during total hip arthroplasty (THA). We present the outcome of the first 40 robotic cases performed in an NHS foundation trust along with the technique of performing robotic THA in our unit. Forty consecutive patients undergoing robotic THA (rTHA) were compared to a case matched group of patients undergoing manual THA (m-THA). 2:1 blinded case matching was performed for age, sex, implants used (Trident uncemented socket and cemented Exeter stem, Stryker Mahwah, NJ, US) and surgeon grade. Comparisons were made for radiological positioning of implants, including leg length assessment, and patient reported functional outcome (PROMS). Pre- and post-operative radiographs were independently analysed by 2 authors. All patients underwent THA for a primary diagnosis of osteoarthritis. No significant difference between groups was identified for post-operative leg length discrepancy (LLD) although pre-operatively a significantly higher LLD was highlighted on the MAKO group, likely due to patient selection. Significantly lower post-operative socket version was identified in the MAKO cohort although no difference in post-operative cup inclination was noted. However, there was significantly larger variance in post-op LLD (p=0.024), cup version (p=0.004) and inclination (p=0.05) between groups indicating r-THA was significantly less variable (Levene's test for homogeneity of variance). There was no significant difference in the number of cases outside of Lewinnek's ‘safe’ zone for inclination (p=0.469), however, there were significantly more cases outside Lewinnek's ‘safe’ zone for version (12.5% vs 40.3%, p=0.002) in the m-THA group. We report the commencement of performance of MAKO robotic THA in an NHS institution. No problems with surgery were reported during our learning curve. Robotic THA cases had less variability in terms of implant positioning suggesting that the MAKO robot allows more accurate, less variable implant positioning with fewer outliers. Longer term follow-up of more cases is needed to identify whether this improved implant positioning has an effect on outcomes, but the initial results seem promising

INTRODUCTION. Combining novel diverse population-based software with a clinically-demonstrated implant design is redefining total hip arthroplasty. This contemporary stem design utilized a large patient database of high-resolution CT bone scans in order to determine the appropriate femoral head centers and neck lengths to assist in the recreation of natural head offset, designed to restore biomechanics. There are limited studies evaluating how radiographic software utilizing reference template bone can reconstruct patient composition in a model. The purpose of this study was to examine whether the application of a modern analytics system utilizing 3D modeling technology in the development of a primary stem was successful in restoring patient biomechanics, specifically with regards to femoral offset (FO) and leg length discrepancy (LLD). METHODS. Two hundred fifty six patients in a non-randomized, post-market multicenter study across 7 sites received a primary cementless fit and fill stem. Full anteroposterior pelvis and Lauenstein cross-table lateral x-rays were collected preoperatively and at 6-weeks postoperative. Radiographic parameters including contralateral and operative FO and LLD were measured. Preoperative and postoperative FO and LLD of the operative hip were compared to the normal, native hip. Clinical outcomes including the Harris Hip Score (HHS), Lower Extremity Activity Scale (LEAS), Short Form 12 (SF12), and EuroQol 5D Score (EQ-5D) were collected preoperatively, 6 weeks postoperatively, and at 1 year. RESULTS. The mean age is 62 years old (range 32 – 75), 136 male and 120 female, BMI 29.7. The preoperative FO and LLD of the operative hip were 43.5 mm (±9.0 mm) and 3.0 mm (±6.5 mm) compared to the native contralateral hip, respectively. The postoperative FO and LLD were 46.4 mm (±8.7 mm) and 1.6 mm (±7.6 mm) compared to the native contralateral hip, respectively. The change in FO on the operative side was 3.0 mm (±7.2 mm) (p<0.0001) and the change in LLD from preoperative to 6-weeks postoperative was 1.6 mm (±8.4 mm) (p=0.0052) (Figure 1), demonstrating the ability of this stem design to recreate normal hip biomechanics in this study. The HHS increased considerably from a preoperative score of 55.9 to 78.4 at 6 weeks and 92.7 at 1 year. Clinically significant improvements were also seen at 1 year in the LEAS (+2.3), SF12 PCS (+16.3), and EQ-5D TTO (+0.26) and the EQ-5D VAS (+15.7). DISCUSSION and CONCLUSION. This study demonstrated that recreation of normal anatomic leg length and offset is possible by utilizing a modern fit and fill stem that was designed by employing an advanced anthropomorphic database of CT scans. We hypothesize that when surgeons utilize this current fit and fill stem design, it will allow them to accurately recreate a patient's natural FO and leg length, assisting in the restoration of patient biomechanics. Summary Sentence. In this study, modern design methods of a press-fit stem using 3D modeling tools recreated natural femoral offset and leg length, assisting in the restoration of patient biomechanics

Acetabular cup positioning remains a real challenge and component malpositioning after total hip arthroplasty (THA) can lead to increased rates of dislocation and wear. It is a common cause for revision THA. A novel 3D imageless mini-optical navigation system was used during THA to provide accurate, intraoperative, real-time, and non-fluoroscopic data including component positioning to the surgeon. This retrospective comparative single surgeon and single approach study examined acetabular component positioning between traditional mini-posterolateral THA and mini-posterolateral THA using the 3D mini-optical navigation system. A retrospective chart review was conducted of 157 consecutive (78 3D mini-optical navigation and 79 traditional non-navigation methods) THAs performed by the senior author using a mini-posterolateral approach at an ambulatory surgery center and hospital setting. Two independent reviewers analyzed postoperative radiographs in a standardized fashion to measure acetabular component positioning. Demographic, clinical, surgical, and radiographic data were analyzed. These groups were found to have no statistical difference in age, gender, and BMI (Table I). There was no difference between groups in acetabular components in the Lewinnek safe zone, 31.2% vs 26.6% (p = 0.53). Cup anteversion within the safe zone did not differ, 35.1% vs 40.5% (p = 0.48); while cup inclination within the safe zone differed, with more in the navigation group, 77.9% vs 51.9% (p < 0.01). Change in leg length was significantly different with the navigation group's leg length at 1.9 ± 6.3, less than the traditional at 5.4 ± 7.0 (p < 0.01). There was no difference in mean change in offset between groups (4.5 ± 5.9 vs 6.2 ± 7.9, p = 0.12); navigation, traditional) (Table II). The 3D mini-optical navigation group did have significantly longer operative time (98.4 ± 17.5 vs 89.3 ± 15.5 p < 0.01). Use of the novel 3D Mini-optical Navigation System significantly improved cup inclination compared to traditional methods while increasing operative time. For any figures or tables, please contact the authors directly

Purpose: Clinical studies still show significant variability in offset and leg length reconstruction after 28mmTHA. Precise restoration of hip biomechanics is important since it reduces wear and improves stability, abductor function and patient satisfaction. There is a tendency to increase offset and leg length to ensure stability of 28mmTHA. This may not be needed with the more stable LDHTHA and hip resurfacing implants, therefore potentially improving the precision of the hip reconstruction. The aim of this study was to verify this assumption. Method: Leg length and femoral offset were measured on standardized digital radiographs with a computer software in 254 patients (49 HR, 74 LDHTHA, 132 28mmTHA) with unilateral hip involvement and compared to the normal contralateral side. Results: Femoral offset was increased in 72% of 28mmTHA (mean +3.3mm), 56% of LDHTHA (mean +1.0mm) and 8% of HR (mean −3.2mm) (intergroup differences p< 0.05). The mean LLI was greater after 28mmTHA (+2,29mm) vs. (−0.45mm for LDHTHA and −1.8mm for HR). The percentage of patients with increased leg length > 4mm was greater for 28mmTHA (11%) compared to LDHTHA (2.7%) and HR (2%). Conclusion: The stability afforded by the larger head of LDHTHA reduces the surgeon’s tendency to increased leg length and femoral offset to avoid instability as during 28mmTHA. In addition, compared to HR, LDHTHA allows more precise restoration of equal leg length and femoral offset in patient with greater pre operative deformities (low femoral offset and LLI > 1cm). LDHTHA may represent the most precise method of hip joint reconstruction

In schoolchildren screened for scoliosis about 40% have minor, non-progressive, lumbar scolioses secondary to pelvic tilt with leg-length and/or sacral inequality [1] not reported with preoperative thoracic curves [2]. Forty-nine of 108 consecutive adolescent patients referred from routine scoliosis school screening during 1996–1999 had lower spinal scoliosis with measurable radiological sacral alar and hip tilt angles – lumbar scoliosis 18, thoracolumbar scoliosis 31 (girls 41, boys 8, mean Cobb angle 16 degrees, range 4–38 degrees). In standing full spine antero-posterior radiographs measurements were made of Cobb angle and pelvic asymmetries as sacral alar and iliac heights (left minus right). From anthropometric measurements derivatives were calculated as ilio-femoral length (total leg length minus tibial length) and several length asymmetries, namely: ilio-femoral length asymmetry, total leg length inequality and tibial length asymmetry (all left minus right). Ilio-femoral length asymmetry correlates significantly with sacral alar height asymmetry (girls negatively r= − 0.456, p=0.002, boys positively r=0.726 p=0.041) but not iliac height asymmetry (girls p=0.201) from which three types are identified. Total leg length inequality but not tibial length asymmetry in the girls is associated with sacral alar height asymmetry (r= − 0.367 p=0.017 & r=0.039 p=0.807 respectively). Interpretation is complicated by total leg lengths each including some ilium in which there is asymmetry [3]. But lack of association between ilio-femoral length asymmetry and iliac height asymmetry suggests that the femoral component is more important than iliac component in determining the associations between sacral alar height asymmetry and each of ilio-femoral length asymmetry and total leg length inequality. Conclusions:. Sacral alar height asymmetry and leg length asymmetries. The evidence suggests that sacral alar height asymmetry is not secondary to the leg length inequalities at least in most girls (negative correlations) and is more likely to result from primary skeletal changes in femur(s) and sacrum. Sacral alar height asymmetry and Cobb angle. Scoliosis progression and iliac height asymmetry [3] appear to need factors additional to those that determine ilio-femoral length asymmetry – for in the girls Cobb angle is associated with both sacral alar height asymmetry and iliac height asymmetry (each p< 0.001) but not with either ilio-femoral length asymmetry (p=0.249) or total leg length inequality (p=0.650). The additional factors may be biomechanical [4], and/or biological in the trunk [5] and central nervous system [6]

Background. Exeter Trauma Stem (ETS) is a polished tapered collarless monopolar prosthesis used for cemented hemiarthroplasty for fracture neck of femur. Two modular rasps are available on the instrumentation set. The larger rasp, in practice, rarely fits into the femur making trial reduction impossible. Our hypothesis was that the absence of a trial reduction could affect leg length and stability of the prosthesis. Aim. To evaluate the leg length discrepancy following use of Exeter Trauma Stem for intracapsular fracture neck of femur. Methods. All patients who underwent ETS hemiarthroplasty between June 2009 to March 2010 (n = 100) were included in the study. Radiographic assessment of leg length was performed by two independent assessors based on measurements by Woolson et al. Results. Upto half of the patients had equal leg length measurements. Forty four patients had lengthening of the operated leg with a mean of 10mm (5–25). Further complications included four dislocations. There was no statistical significance between leg lengths and dislocations. Conclusion. Care is needed with regards to correct positioning of the ETS prosthesis to achieve equal leg lengths. Following this study a new intermediate sized modular rasp has been introduced to the instrumentation set

Background. It is unclear which form of anaesthesia is the most favourable in primary total hip replacement (THR) surgery. A recently published systematic review of modern anaesthesia techniques in primary THR surgery (Macfarlane 2009) was not able to show any convincing benefit of regional or general anaesthesia. One retrospective study that examined anaesthesia and leg length (Sathappan 2008), found an increased incidence of leg length difference > 5 mm in those patients who were operated with regional anaesthesia. Our department used a mini invasive approach in supine as standard procedure in THR. The type of anaesthesia that is chosen is up to the individual anaesthetist. Purpose. We wanted to see if there was any correlation between type of anaesthesia and leg length, total time spent in theatre and recovery room, postoperative hospital stay, blood loss or operating time in primary THR surgery with a mini invasive approach in supine. Materials and Methods. Our study was a retrospective study of 170 primary THR patients. All patients received an uncemented Corail stem and a cemented Marathon cup. Patients with abnormal anatomy, BMI > 46, simultaneous removal of internal fixation or incomplete data were excluded in the analysis. Radiograpic leg length was measured using the inter teardrop line and the lesser trochanter. Results. 99 patients were operated on with spinal anaesthesia and 71 with total intravenous anaesthesia (TIVA). There were 65% women in both groups. Average age was 74 years (32–95) in the spinal anaesthesia group and 67 years (38–93) in the TIVA group. We found no significant difference in the average operating time (spinal 65 min, TIVA 64 min), drop in haemoglobin to the first postoperative day (spinal 16%, TIVA 16%), postoperative hospital stay (Spinal 1.4 days, TIVA 1.4) or in transfusion rate (spinal 1%, TIVA 1.4%). We found a significant difference in the proportion of patients with a leg length difference of more than 7 mm (Spinal 22%, TIVA 6%, p = 0.02) and the average total time spent in theatre and post-operative department (spinal 325 min, TIVA 293 min, p < 001). Discussion. The study is retrospective and is therefore fettered by the limitations inherent in such a study. Our study seems to confirm the earlier findings that the type of anaesthesia can affect leg length in primary THR. It is speculated that spinal anaesthesia has a more unpredictable effect on muscular tension which could explain this

Introduction:. Paley et al has developed a multiplier method for calculating both leg length and total height. In the development of this algorithm, they evaluated the effect of factors including bone age and sex. They established that sex had a significant impact, but adjusting for bone age did not improve accuracy. Bone age and menarche have been shown to improve other height prediction models. Purpose:. We used a large prospective cohort to evaluate if the multiplier is independent of physiological age using menarche as a proxy. Methods:. Using the ALSPAC dataset we determined the accuracy of the Paley multiplier for predicting total height and leg length, and assed weather if the date of first menses increased the accuracy of the multiplier. Female patients over the age of 8, with documented final height and final sub-ishial leg length over the age of 15 and a date of first menses were evaluated. Predicted final height was compared with actual final height at all data points. Results:. There were 28332 data points in 3062 girls prior to skeletal maturity in the total height cohort and 8395 data points in 2300 girls in the leg length cohort. When age was corrected using the difference in age at onset of menarche from average, the accuracy of multiplier decreased for both measurements. When a correction of 50% was used, there was an improvement in the accuracy of multiplier predictions, reducing the average error by up to 24%. Conclusions:. Previous studies have failed to demonstrate that the accuracy of the multiplier is improved when adjusted for bone age. We have used the date of first menses as a proxy for bone age and established that making a 50% correction for physiological age improves the accuracy of this method. Significance:. This will potentially allow more accurate prediction of leg length discrepancy, and total height in girls with early menarche

Cement-in-cement revision of the femoral component represents a widely practiced technique for a variety of indications. In this study we compare the clinical and radiological outcomes of two polished tapered stems. From our prospectively collated database we identified all patients undergoing cement-in-cement revision from January 2005 – 2013 who had a minimum of two years follow-up. All cases were performed by the senior author using either an Exeter short revision stem or the C-stem AMT high offset No 1. Patients were followed-up annually with clinical and radiological assessment. Ninety-seven patients matched the inclusion criteria. There were 50 Exeter and 47 C-stem AMT components. There were no significant differences between the patient demographics in either group. Mean follow-up was 9.7 years. A significant improvement in OHS, WOMAC and SF-12 scores was observed in both cohorts. Leg lengths were significantly shorter in the Exeter group, with a mean of -4mm in this cohort compared to 0mm in the C-stem AMT group. One patient in the Exeter group had early evidence of radiological loosening. In total, 16 patients (15%) underwent further revision of the femoral component (seven in the C-stem AMT group and nine in the Exeter group). No femoral components were revised for aseptic loosening. There were two cases of femoral component fracture in the Exeter group. Our series shows promising long-term outcomes for the cement-in-cement revision technique using either the Exeter or C-stem AMT components. These results demonstrate that cement-in-cement revision using a double or triple taper-slip design is a safe and reliable technique when used for the correct indications

Background:. Paley et al has developed the multiplier method for predicting leg length. It is a tool that is used clinically to predict leg length discrepancy. The method is also a way of comparing different populations, to identify differences in growth trajectory. This has been done by identifying the differing multipliers for girls and boys. However it has not been used to identify trends in populations separated by time. Tanner showed that in the first half of the twentieth century girls went from an average age of menarche of 15 in 1900, to 13 in 1970, how this has affected growth trajectory over the last 50 years has not been studied. Purpose:. The multiplier method is based on data collected in the 1950's by Anderson and Green, we aim to assess whether there has been a change in growth trajectory between this historical cohort and a contemporary European based cohort. Methods:. The Avon Longitudinal Study of Parents and Children of the 90s (ALSPAC) is a longitudinal cohort study of children recruited antenatally, and followed prospectively. Assessment of sub ischial leg length was made on clinical measurements. There were up to 8 measurements per patient, 2311 girls with a final age at assessment of greater than 15 years and 123 males with a final age of assessment of greater than 16 years were assessed. We used the multiplier method to assess the predicted final leg length and compared this with the actual leg length. Result:. There was no difference between the multiplier in girls, in the contemporary cohort and the historical cohort. The average age of menarche in the contemporary group was 12.7. In boys the data is limited, due to later growth and it is not possible to draw comparisons from this group. Conclusion:. This data provides good evidence that there has not been a significant change in growth trajectory in girls over the last 50 years. Significance:. Implications on the confidence with which we can use the multiplier method in this population

Introduction. The primary purpose of Total Hip Arthroplasty (THA), aside from pain relief, is to restore hip biomechanics such that the patient experiences no discernible functional deficit, while also providing an environment conducive to implant longevity. Key factors in determining a successful THA include achieving the desired pre-operative femoral offset and leg length, as well as the restoration of range of motion (ROM). Minor leg length discrepancies (LLDs), less than a centimetre, are common after THA and usually well tolerated. However, in some patients, even these small discrepancies are a source of dissatisfaction. More significant discrepancies can be a risk factor for more serious concerns such as nerve injury, abnormal gait and chronic pain. The level of the femoral neck osteotomy is a critical step in reproducing a planned femoral stem position. Frequently the femoral osteotomy is too high and can lead to an increase in leg length and varus stem positioning. If the desired implant positions are identified from preoperative 3D templating, a planned femoral osteotomy can be used as a reference to recreate the correct leg length and offset. The aim of this study was assess the accuracy of a 3D printed patient-specific guide for delivering a pre-planned femoral neck osteotomy. Methodology. A consecutive series of 33 patients, from two surgeons at a single institution, were sent for Trinity OPS pre-operative planning (Optimized Ortho, Australia). Trinity OPS is a pre-operative, dynamic, patient-specific modelling system for acetabular and femoral implant positioning. The system requires a pre-operative CT scan which allows patient specific implant sizing as well as positioning. Once the preoperative implant positioning plan was confirmed by the surgeon, a patient-specific guide was designed and printed to enable the planned level of femoral neck osteotomy to be achieved, Fig 1. All patients received a Trinity cementless acetabular component (Corin, UK) and a cementless TriFit TS femoral component (Corin, UK) through a posterior approach. The achieved level of osteotomy was confirmed postoperatively by doing a 3D/2D registration, in the Mimics X-ray Module (Materialise, Belgium), of the planned 3D resected femur to the postoperative AP radiograph, Fig 2. The image was then scaled and the difference between the planned and achieved level of osteotomy was measured (imatri Medical, South Africa), Fig 2. Results. The mean absolute difference between the planned and achieved osteotomy level was 0.7mm (range 0.1mm − 6.6mm). Only 1 patient had a difference of more than 3mm, Fig 3. Of the 33 patients, 28 had a difference of less than 1mm. Conclusions. The results from this initial series of 33 patients suggest that a 3D printed patient-specific guide can be a simple and accurate way of intraoperatively reproducing a planned femoral neck osteotomy, though there was one significant outlier. Whether the 3D planning, patient-specific guide and accurate femoral osteotomy can then be used to achieve precise leg length and offset recreation is the subject of an on-going evaluation

Background:. Acetabular cup positioning. 1, 2. , leg length discrepancy. 3. and global offset. 4. are important parameters associated with outcomes following total hip arthroplasty (THA). Deviation from an accepted range of values for each of these parameters can lead to significant complications including nerve injury, low back pain, abnormal gait, increased dislocation rate, and bearing surface wear. The primary purpose of this study was to assess whether the use of the MAKO™ robotic hip system is reliable in predicting post-operative radiographic measurements of cup inclination, cup anteversion, leg length change, and global offset change in THA. Materials and Methods:. All robotic-assisted THAs performed using the MAKO™ system between June 2011 and Dec 2012 were reviewed. A single surgeon performed all cases through a mini-posterior approach. The intra-operative measurements of cup inclination and anteversion angles, leg length change, and global offset change recorded by the MAKO™ system were compared to the post-operative radiographic measurements. Results:. Sixty one cases met the inclusion and exclusion criteria. A strong inter- and intra-observer correlation was found for the radiographic measurements of cup inclination, cup anteversion, leg length discrepancy and global offset (r > 0.8 with p < 0.001 for all). Comparison between the MAKO™ and the radiographic measurements showed mean differences in inclination of 3.2° ± 2.7° (CI. 95. = 0.7), mean differences in anteversion of 3.8° ± 2.6° (CI. 95. = 0.7), mean differences in leg length change of 3.5 ± 2.6 mm (CI. 95. = 0.7), and mean differences in global offset change of 4.5 ± 3.7 mm (CI. 95. = 1.0). 85.2% of MAKO™-measured inclination angles were within 5° of radiographic measurements, and 96.7% within 10°. 65.6% of MAKO™-measured anteversion angles were within 5° of radiographic measurements, and 98.4% within 10° (Figure 1). 69.4% of MAKO™-measured leg length change measurements were within 5 mm of radiographic measurements, and 100% within 10 mm. 71.4% of MAKO™-measured global offset change measurements were within 5 mm of radiographic measurements, and 91.8% within 10 mm (Figure 2). Conclusion:. The MAKO™ robotic hip system showed good predictive value for cup inclination and anteversion angles, leg length change and femoral offset change measurements done post-operatively on plain radiographs. Further refinement of the MAKO™ system would be expected to make it more accurate in predicting the post-operative parameters mentioned

Introduction. Acetabular component positioning, offset, combined anteversion, leg length, and soft tissue envelope around the hip plays an important role in hip function and durability. In this paper we will focus on acetabular positioning of the cup. Technique. The axis of the pelvis is identified intra-operatively as a line drawn from the highest point of the iliac crest to the middle of the greater trochanter. Prior to reaming the acetabulum, an undersized trial acetabular component is placed parallel and inside the transverse ligament, inside the anterior column and projecting posterior to the axis of the pelvis. This direction is marked and the subsequent reaming and final component placement is performed in the same direction. The lateral opening is judged based on the 45-degree angle from the tear drop to the lateral margin of the acetabulum on anteroposterior pelvic radiographs. The final anteversion of the cup is adjusted based on increased or decreased lumbar lordosis and combined anteversion. Methods. Anteroposterior pelvic radiographs of 100 consecutive patients undergoing posterior THR between September 2010 and March 2011 with this method were evaluated for cup inclination angle and anteversion using EBRA software. Results. There were no malalignments or dislocations. The mean cup inclination angle and anteversion were 41 ± 5.1 degrees (range 37.1 – 48.4) and 22.1 ± 4.8 degrees (range 16.6 – 29.3), respectively. Conclusion. This is a reproducible method of cup positioning and with proper femoral component position and restoring leg length, offset, combined anteversion, and balance soft tissue around the hip. These factors affect the incidence of dislocation, infection, reduced wear, and durability

Introduction. Computer navigation is a highly sophisticated tool in orthopedic surgery for component placement in total hip arthroplasty (THA). A number of recommendations have been published. Although Lewinnek's safe-zone is the best-known among these its significance is questioned in recent years since it addresses the acetabular socket only ignoring the femoral stem. Modern target definitions consider both socket and stem and provide well-defined recommendations for complementary component positioning. We present a new small-sized hand-held imageless navigation system that implies these targets and supports the surgeon in realizing the concept of combined anteversion and combined Target-Zone (cTarget- Zone) in THA and to control leg length and offset without altering the standard surgical work-flow and we report initial results. Methods. The targets for positioning the components of a total hip as expressed by radiographic cup inclination (cRI) and anteversion (cRA), stem antetorsion (sAT) and neck-to-shaft angle (sNSA) are determined for a specific prosthesis system using a computerized 3D-model. The optimizing goal is maximizing the size of the cSafe-Zone providing the largest target zone for an impingement-free prosthetic range of motion (pROM) in order to minimize the risk for dislocation in physiologic and combined movements. Independent parameters like head size, head-to-neck ration and also component orientations like cRI, cRA, sAT and sNSA were varied systematically and the optimal cSafe-Zone was computed in semi-automated batch runs. These optimized prosthesis-specific results were introduced into the software of the hand-held navigation system. This system measures leg length, offset, acetabular and femoral head centers intraoperatively. Results. In contrast to Lewinnek the outline of our cSafe-Zone is not rectangular but polygonal. Its size shows prosthesis-specific maxima. The largest zones are found for optimal sNSA values at 126° +/−4°, optimal ranges for cRI depend on head size and range from 44° to 36°, best sAT range from 10° to 18°, cRA from 18° to 25°. There is a prosthesis- specific linear correlation between sAT and cRA that denotes the combined anteversion. The target value for combined anteversion is not dependent on pelvic tilt but on sNSA. The hand-held navigation system displays all these orienting parameters as well as leg-length and offsets. Furthermore, it supports a virtual reduction work-flow thus accelerating surgery. All these information provide important decision-making details for the surgeon intraoperatively in real-time for augmented quality. Conclusion. The combined Target-Zone provides the basis for patient- and implant-specific control of prosthesis implantation. It includes all important positioning parameters of both total hip components and such gives well-defined individual recommendations for the targets. The new hand-held navigation system (Naviswiss) provides a smart way to direct and control the total hip implantation according to the best combined orientation considering also the concept of combined Safe-Zone. Such it prevents outliers, provides better safety and documents the surgical workflow and the final result of the surgery

Predictions of lower limb growth are based upon historical data, collected from patients who had coexistent poliomyelitis. By utilising standardised longitudinal prospective European data, our objective was to generate superior estimates for the age and rate at which lower limb skeletal maturity is reached; thus improving the timing of epiphysiodesis, for the management of leg length discrepancy. The Avon Longitudinal Study of Parents and Children of the 90s (ALSPAC) is a longitudinal cohort study of children recruited antenatally 2. Using a previously validated Multiplier Method, a sequence of leg length multipliers were calculated for each child. 15,458 individuals were recruited to the ALSPAC study; and of those whose growth was measured, 52% were boys and 48% girls, each with an average of eight recording episodes. 25,828 leg length multiplier (LLM) values were calculated with final recordings taken at a mean age of 15.5 years. From this data, the age at which girls reach skeletal maturity (LLM=1) is 11 months later than previously calculated and for boys nearly 9 months earlier. With nearly 4000 more children recruited in this cohort than preceding studies, this study brings increased power to future leg length calculations

Aims. Accurate placement of acetabular and femoral stem components in total hip arthroplasty (THA) is an important factor in the success of the procedure. A variety of free hand or navigated techniques is reported. Survivorship and complications have been shown to be directly related to implant position during THA. The aim of this cadaver study was to assess the accuracy of the placement of the components in THA using patient specific instruments (PSI) in combination with a 3D planning software and the direct anterior approach. Method. Patient specific instruments (PSI) were developed to guide the surgeon during THA that were 3D printed with their bone models following a 3D software planning protocol (LPH software V2.5.1, Onefit-Medical, Eos Imaging Company, Besancon, France). Acetabular guides: cup, offset and straight reamer handle and impactor, femoral- and chisel guides were used in each THA (Fig. 1). To define anatomic bone landmarks and to generate a 3D model of each hip joint CT scans were performed preoperatively. The planning of component position was done by one surgeon (AZ) preop. Surgery was performed by two experienced surgeons (AZ, SD) on cadaver specimen with 4 hips in two separate series. A total of 8 hip replacements were evaluated pre- and postoperatively using CT-scans of each hip joint to compare planned to achieved results. Mechanical simulations of the guides were carried out to verify that there were no conflicts between the different instruments. To meet the ISO standard 16061: 2015 the compatibility of the instruments with the guides has been checked. Parameters were evaluated in 3D pelvic and femoral planes: center cup position, inclination angle, anteversion angle, cutting height and plan orientation, anteversion angle, flexion/extension angle, varus/valgus angle, anatomical and functional leg length, offset. Acceptance criteria: postop. parameters evaluated must not have a deviation of more than 5 degrees, 2,5 mm according to preop. planning. For every THA the test protocol has been completely realized. Results. The difference between the preop. and postop. measures in the first series of 4 hips revealed 2 outliers because of fractures of the acetabulum in 2 cases, related to bad cadaver quality. In the second series we found satisfactory results comparing the planned preop and postop component position (Fig. 2). For example difference of leg length showed a mean absolute of 1,58 mm, standard deviation 1,21 mm (min 0,62; max 3,34 mm). Offset revealed a mean absolute of 1,62 mm, standard deviation 0,57 mm (min 1,06; max 2,14 mm) concerning the difference between preop. planning and result postop. Conclusion. Accurate and safe placement of total hip components in THA, both acetabular cup and stem, performing the direct anterior approach can be achieved using a 3D preoperative planning along with patient specific instruments. The results of the cadaver study tests are promising and that is to be proven in the clinical setting and by application in the future

Abstract. Objectives. 1. To investigate the effect of revision total knee replacement (TKR) on gait kinematics in patients with a primary TKR and instability.2. To compare gait kinematics between patients with a well-functioning TKR and those with a primary TKR and symptoms of instability. Methods. This single-centre observational study is following patients who have had a revision TKR due to knee instability. Data was collected pre- and post-operatively at 8–12 week follow-up. The data was compared to a control group of 18 well-functioning TKR patients. Kinematic gait data was collected during routine clinics using a treadmill-based infrared 3D system (Vicon, Oxford, UK) and a published lower limb marker-set. Patients performed 15 strides at three different speeds: 0.6mph, self-selected, and a ‘slow walk’ normalised to leg length (Froude number 0.09). PROMs questionnaires were collected. NHS ethical approval was obtained. Results. Data was collected for 18 well-functioning TKR patients and 8 revision TKR patients pre- and post-operatively, but only 5 could walk at the normalised speed. When walking at a normalised speed (Froude 0.09), patients with a TKR with instability had reduced range of knee flexion (52° (sd 14)) compared to those with a well-functioning TKR (59° (sd 11)). Short term follow-up after a revision TKR operation demonstrated a stiffer knee (45° (sd 12)). However, those with revision TKR had a more flexed knee during stance phase. Conclusions. At short-term follow-up, this cohort of revision TKR patients appear to have reduced flexion range, while remaining more flexed during stance. This may represent a less efficient gait pattern, which may also adversely affect the implant[1]. Longer term follow-up may demonstrate whether this normalises with post-operative rehabilitation. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Acetabular component positioning is highly correlated with total hip arthroplasty (THA) outcomes. Multiple reports however indicate that less than 50% of acetabular cups are placed within surgeon-desired ranges for abduction and anteversion angles when using conventional cup positioning techniques. Issues with improper placement include instability-dislocation, impingement and impact on range of motion, polyethylene wear, leg length discrepancy, and gait mechanics. Accuracy in placement of the acetabular component is complicated by the need to estimate cup impactor angles to create desired cup position. A low cost approach to THA using Image-based Ultrasonic Guidance (IUG) (Orthosensor, Sunrise, FL) coupled to existing surgical tools is presented. IUG utilises acoustic measurement techniques for achieving optimal component positioning and leg length. A precisely machined Hip Test Fixture (HTF) has been built to simulate the anatomical pelvis, acetabular cup, and femur to validate system accuracy. The IUG was affixed to the HTF to demonstrate placement of the cup during THA. The HTF was loaded onto a 27-inch Graphic User Interface (GUI) providing three-dimensional CAD data of the HTF. Registration points included the Iliac Crest and 10 points around the acetabular cup. These points were mapped to the CAD data by the GUI. The HTF was set to 45° of abduction and 0° of version to begin testing. Abduction and version were measured over a +15° range in 1-degree increments while leg length and offset were measured over a +5mm range in 2mm increments. A high-resolution coordinate measurement machine (FaroArm EDGE) verified the accuracy and margin of error for inclination, version, leg length and offset at each increment. The HTF provided a precise means for evaluating IUG system accuracy of simulated THA in a controlled environment. Acceptable margins of error were reported on the HTF: mean error for version was 0.36° (SD 0.02°; 0.25° to 0.38°); mean error for inclination was 1.04° (SD 0.52°; 0.48° to 1.66°); mean error for leg length and offset were respectively 0.36mm (SD 0.86mm; −0.65 to 1.55mm) and 0.41mm (SD 0.28; 0.05 to 0.80mm). IUG provides a means for achieving acceptable precision and accuracy in component placement during THA as evaluated with the HTF. Further study is however necessary to correlate accuracy of IUG with clinical utility and short-term clinical outcomes

Aims. Leg length inequality following total hip replacement remains common. In an effort to reduce this occurrence, surgeons undertake pre-operative templating and use various forms of intra-operative measurements, including computer navigation. This study aims to delineate which measurement technique is most appropriate for measuring leg length inequality from a pelvic radiograph. Method. Three observers took a total of 9600 measurements from 100 pelvic radiographs. Four lines were constructed on each of the radiographs, bisecting the acetabular teardrops (Methods 1/2), ishial spines (Method 3/4), inferior sacroiliac joint (Method 5/6) and inferior obturator foramen (Method 7/8). Measurements were taken from these lines to the midpoint on the LT and to the tip of the GT. The effect of pelvic positioning was also assessed using radiographs of a synthetic pelvis and femur using the same eight methods by a single observer (ED). Intra-observer variability was analysed using within subject standard deviation. Inter-observer variability was analysed using the coefficient of inter-observer variability (CIV). Results. When considering the 100 pelvic radiographs measurement methods 3 (SD 3.5, CIV 0.34) and 8 (SD 3.3 CIV 0.33) showed the best inter and intra observer variability. Methods 4 and 6 performed badly for inter and intra observer variability (SD 3.8 CIV 0.4 and SD 4.6 CIV 0.4). Methods 1, 2, 5 and 7 performed well in one aspect but poorly in the other. When considering the effect of pelvic positioning using radiographs of the synthetic pelvis and femur construct, methods 3 and 7 performed best (SD 6.7 and SD 7.4). Discussion. Measuring from the ischial tuberosities to the LT has the best intra- and interobserver variability. It also performs well despite pelvic malposition. As techniques improve in the measurement of intra-operative leg length, a more accurate measurement of leg length is needed to validate these technologies by

Introduction: Patients following resurfacing frequently remark about the natural feel of the resurfaced hip joint in contrast to those with total hip arthroplasty. Possible reasons for this include the larger femoral head size, conservation of bone and superior biomechanics of the implant with more accurate restoration of femoral offset, leg length and femoral anteversion. Our aim was to assess femoral offset and leg length following hip resurfacing and hybrid THR (uncemented acetabulum) performed by the same surgeon. Methods: A consecutive group of patients were identified (35 resurfacing and 25 hybrid). AP pelvis radiographs were evalulated, films with evidence of malrotation or inadequate imaging of the femur were excluded, leaving 21 resurfacing and 15 hybrid. Comparison was made between the pre-op and post-op films together with the contralateral hip on the same film. Patients with hip dysplasia or significant pathology in the contralateral hip were excluded. Magnification of the films was measured by comparison of the templated diameter of the implanted femoral head and the acutal diameter of the implant. To allow comparison between pre-op films a measurement was taken between the obturaror foraminae. All films were analysed by the same investigator using the technique described by Jolles et al (J Arthroplasty 2002). A horizontal line was drawn between the base of the teardrop on both sides, and perpendicular lines drawn from the back of the teardrops. The anatomical femoral axis was drawn and femoral offset measured from this. The centre of rotation of the femoral head was determined by templating and the acetabular offset obtained. Distance from tip of the greater trochanter to the centre of the femoral head in the axis of the femur was determined on pre and post-op films, as this shows little variation with rotation of the femur. Leg length was measured from the horizontal line to the tip of the greater trochanter together with the angle between the femoral axis and the horizontal to correct for abduction of the hip. Results: Mean total femoral offset compared to the contralateral side was −1.3mm (SD 5.3) and −3.2mm (SD 6.5) for the resurfacing and hybrid groups respectively. No significant difference was detected in leg length or other measurements. Discussion and Conclusion: No significant differences were demonstrated between femoral offset or leg length in the resurfacing and hybrid arthroplasty groups. This study does not support the hypothesis that resurfacing produces more accurate restoration of hip biomechanics than hybrid total hip arthroplasty

Total hip replacement for high dislocation of the hip joint remains technically difficult in terms of preparation of the true acetabulum and restoration of leg length. We describe our experience of cementless total hip replacement combined with a subtrochanteric femoral shortening osteotomy in 20 hips with Crowe grade IV dislocation with a mean follow-up of 8.1 years (4 to 11.5). There was one man and 17 women with a mean age of 55 years (44 to 69) at the time of the operation. After placment of the acetabular component at the site of the natural acetabulum, a cementless porous-coated cylindrical femoral component was implanted following a subtrochanteric femoral shortening osteotomy. The mean Japanese Orthopedic Association hip score improved from a mean of 38 (22 to 62) to a mean of 83 points (55 to 98) at the final follow-up. The mean lengthening of the leg was 14.8 mm (−9 to 34) in patients with iliofemoral osteoarthritis and 35.3 mm (15 to 51) in patients with no arthritic changes. No nerve palsy was observed. Total hip replacement combined with subtrochanteric shortening femoral osteotomy in this situation is beneficial in avoiding nerve injury and still permits valuable improvement in inequality of leg length

Introduction & aims. Correct prosthetic alignment is important to the longevity and function of a total hip replacement (THR). With the growth of 3-dimensional imaging for planning and assessment of THR, the importance of restoring, not just leg length and medial offset, but anterior offset has been raised. The change in anterior offset will be influenced by femoral anteversion, but there are also other factors that will affect the overall change after THR. Consequently, the aim of this study was to investigate the relationship between anterior offset and stem anteversion to determine the extent to which changing anteversion influences anterior offset. Method. Sixty patients received a preoperative CT scan as part of their routine planning for THR (Optimized Ortho, Sydney). All patients received a Trinity cementless shell and a cemented TaperFit stem (Corin, UK) by the senior author through an anterolateral approach. Stem anteversion was positioned intraoperatively to align with cup anteversion via a modified Ranawat test. Postoperatively, patients received a CT scan which was superimposed onto the pre-op CT scan. The difference between native and achieved stem anteversion was measured, along with the 3-dimensional change in head centre from pre-to post-op. Finally, the relationship between change in stem anteversion and change in anterior offset was investigated. Results. Mean change in anterior offset was −2.3mm (−14.0 to 7.0mm). Mean change in anteversion from native was −3.0° (−18.8° to 10.5°). There was a strong correlation between change in anterior offset and change in anteversion, with a Pearson correlation coefficient of 0.89. A 1° increase in anteversion equated to a 0.7mm increase in anterior offset. Conclusions. A change in the anteroposterior position of the femoral head is primarily affected by a change in stem anteversion, with a 1° increase in anteversion equating to a 0.7mm increase in anterior offset. The AP position of the stem in the canal, along with the flexion of the stem will also contribute. Given the well-recognised influence of leg length, medial offset and combined anteversion on restoring hip function, it seems reasonable to assume that anterior offset will also have a significant effect on the biomechanics of the replaced hip

While squeaking ceramic bearings in total hip arthroplasty are increasingly reported in the literature, the etiology remains unclear. Cup inclination and anteversion have been correlated with the phenomenon but even amongst well positioned cups bearing noise is observed. Most studies do not distinguish between different types of noise or incidence rate and do only investigate actively complaining patients. This study analysed the incidence of ceramic bearing noise in a single type of hip implant and investigates correlations with patient, implant and surgery parameters. In a consecutive series of 145 ceramic-on-ceramic primary hips (Stryker ABG-II, 28mm head) in 132 patients (m/f=72/60, avg. age=54yrs) and an average follow-up of 3.0 (1–7) years, noisy bearings were identified by a patient questionnaires stating the type of noise (squeaking, clicking, scratching, combinations), time of initial incidence, incidence rate (permanent, often, sometimes, rare) and type of movement. Patient demographics (age, gender, height, weight, BMI, side of surgery, leg length difference), implant parameters (cup and stem size, neck length) and surgery parameters (cup and stem position, leg length correction) were recorded and compared between the noisy and silent groups (t-test, Fisher Exact test). Twenty-eight noisy hips (19.3%) were identified with 14 patients reporting squeaking, 16 clicking and 5 scratching including 7 with a combination of noises. Quasi permanent noises were reported for 7 hips (2 often) but in 17 cases the noise appeared only sometimes (2 rare). The average time of first incidence was 1.74 years port-op with 7 hips reporting noise directly after operation and 15 after 2 years or more. Silent and noisy hips were statistically not different regarding age, gender, follow-up time, side of operation, height, weight, BMI, cup and stem size, leg length difference or stem position. Significant differences were identified with the noise group having a steeper cup inclination (49.9° vs 46.9°, p< 0.05) and less frequent shorter (−2.7mm) necks (0 vs 22%, p< 0.01) but more frequent longer (+4mm) necks (50% vs 37%, p< 0.05). Leg length correction was performed less frequent (31 vs 55%, p< 0.01). In the noise group 5 (17%) and in the silent group only 1 (0.9%) cup revisions was performed (p< 0.01). The incidence of noisy ceramic bearings was higher than usually reported (< 5%) as not only actively complaining subjects but all patients were interviewed. Cup position was confirmed to be a contributing factor but patient weight, height or BMI did not play a role. However, the use of long necks, the absence of short necks and less frequently performed leg length corrections significantly contributed to producing bearing noise. Biomechanical restoration, preoperative planning and soft tissue tension seem to be important factors in bearing noise etiology

We compared a modular neck system with a non-modular system in a cementless anatomical total hip replacement (THR). Each group consisted of 74 hips with developmental hip dysplasia. Both groups had the same cementless acetabular component and the same articulation, which consisted of a conventional polyethylene liner and a 28 mm alumina head. The mean follow-up was 14.5 years (13 to 15), at which point there were significant differences in the mean total Harris hip score (modular/non-modular: 98.6 (64 to 100)/93.8 (68 to 100)), the mean range of abduction (32° (15° to 40°)/28 (0° to 40°)), use of a 10° elevated liner (31%/100%), the incidence of osteolysis (27%/79.7%) and the incidence of equal leg lengths (≥ 6 mm, 92%/61%). There was no disassociation or fracture of the modular neck. The modular system reduces the need for an elevated liner, thereby reducing the incidence of osteolysis. It gives a better range of movement and allows the surgeon to make an accurate adjustment of leg length

Introduction. Our primary hypothesis was simple: does gait on a downhill gradient distinguish between types of knee arthroplasty? Our secondary hypotheses were these: are stride length and other kinematic variables affected by cruciate ligament integrity following knee arthroplasty?. Participants. Ethical approval was sought and gained prior to commencement of the study. 52 subjects were tested on the instrumented treadmill, 3 groups (UKA, TKA, and young healthy control) of 19, 14, and 19 respectively. The two high performing arthroplasty groups were recruited from a database of patient related outcome measures (PROMs) and were chosen based on high Oxford knee scores (OKS) with a minimum 12 months post hip arthroplasty. Gait Analysis. Gait performance was tested on a validated instrumented treadmill (Kistler Gaitway®, Kistler Instrument Corporation, Amherst NY)[22, 23]. The rear of the treadmill was ramped with 30 cm axle stands in order to create a 7 degree decline for downhill walking (figure 1). The speed was increased incrementally. Hof scaling and body weight normalising was also applied to the outputted mechanical data to correct for leg length and mass differences, respectively. Results. Patient Related Outcome Measures. Both arthroplasty groups outcome scores were substantially better than the average reported by national joint registries. Treadmill Gait Analysis. When walking fast downhill, UKA patients walked 15% faster than the TKA patients (1.75 vs 1.52 m/sec p=0.000) despite having the same cadence (134 vs 135step/min) (figures 2,3,4). The 15% difference in speed was largely due to the reduced mean step (p=0.001) and stride lengths (p=0.000) seen in the TKA patients. These finding persisted after Hof scaling, which normalised speed for leg length (p=0.000). The values are indicated as means ± standard deviation; †significant difference between implant versus control (p <0.05); ‡significant difference between implant groups (p<0.05);H=normalized to leg length; BW=normalized to body weight. Discussion. The UKA group walked 15% faster than the TKA, with stride length almost matching the normal controls. The presence of intact cruciate ligaments allow a normal and co-ordinated swing phase, enabling the more normal stride, while the absence of the anterior cruciate ligament contributes to the reduction of knee flexion in swing phase, and thus the shorter stride length

The position of the gastrocnemius tendon relative to the calcaneus and fibular head distance may be different in children with cerebral palsy (CP) when compared to normal children. However, no such data is available. Usually, palpation of the muscle bellies or previous experience of the operating surgeon is employed to place the surgical incision. Inaccurate localisation may cause incorrect incision and a risk of iatrogenic damage to the vital structures (i.e. sural nerve). The aim of our study is to compare gastrocnemius muscle length in-vivo between paretic and unaffected children and suggest a formula to localise muscle-tendon junction. Ten children with di/hemiplegia (seven females and three males; mean age 8y 7mo, range 2–14y) were recruited. None of them had received any conventional medical treatment. An equal number of age/sex matched, typically developing children (mean age 9y 1mo, range 4–14y) were recruited. Participants lay prone on an examination plinth with their feet hanging from its edge. Sagittal-plane ultrasound scanning of the gastrocnemius muscle at rest was performed to measure the length of gastrocnemius bellies. We also measured the heights, lower leg lengths, thigh lengths and leg lengths. At similar age, the lower leg lengths in CP patients were shorter than normal children. Similarly, gastrocnemius medial (GM) muscles were shorter in CP children when compared to similar aged normal children. In CP children, the GM muscle and lower leg ratio ranges between 35 to 50% with an average ratio of 45%. When compared to leg length, the ratio is 22%. Using these figures we created a formula that may be used clinically to identify the tendon for open or endoscopic lengthening and also to make simple and accurate localisation of GM-tendon junction for surgical access. This minimizes the risk of iatrogenic neurovascular injuries and decreases the length of the surgical incision

Total hip joint replacement (THJR) for high riding congenital hip dislocation (CDH) is often performed in young patients, and presents unique problems with acetabular cup placement and leg length inequality. A database and the NZ Joint Registry were used to identify 76 hips in 57 patients with a diagnosis of CDH who underwent THJR in the Wellington region between 1994 and 2015. Records and radiographs of 46 hips in 36 patients classified pre-operatively as Crowe II, III or IV were reviewed. Surgical technique used a direct lateral approach, the uncemented acetabular component was located in the anatomic hip center and a primary femoral stem was used in all but one hip. Whether a step-cut sub-trochanteric femoral osteotomy was performed depended on degree of correction, tension on the sciatic nerve, and restoration of leg length. For the 36 patients classified as Crowe II or higher, the average age at operation was 44 years (26 – 66), female:male ratio was 4.5:1 and follow-up averaged 10 years (2 – 22.3). Of the 15 hips classified as Crowe IV, 10 required a step-cut sub-trochanteric femoral osteotomy to shorten the femur, but 5 were lengthened without undo tension on the sciatic nerve. Nine Crowe IV hips received a conventional proximally coated tapered primary femoral component. Oxford hip scores for 76% of patients was excellent (> 41/48), and 24% had good scores (34 – 41). All femoral osteotomies healed. Five hips have been revised, one at 2 years for femoral loosening, one at 5 years for dislocation, two at 12 years for liner exchanges, and one at 21 years for femoral loosening. THJR using primary prostheses for CDH can provide durable long-term results