Aims. Instability is a common indication for revision total hip arthroplasty (THA). However, even after the initial revision, some patients continue to have recurrent dislocation. The aim of this study was to assess the risk for recurrent dislocation after revision THA for instability. Methods. Between 2009 and 2019, 163 patients underwent revision THA for instability at Stanford University Medical Center. Of these, 33 (20.2%) required re-revision due to recurrent dislocation. Cox proportional hazard models, with death and re-revision surgery for periprosthetic infection as competing events, were used to analyze the risk factors, including the size and alignment of the components. Paired t-tests or Wilcoxon signed-rank tests were used to assess the outcome using the Veterans RAND 12 (VR-12) physical and VR-12 mental scores, the Harris Hip Score (HHS) pain and function, and the Hip disability and Osteoarthritis Outcome score for Joint Replacement (HOOS, JR). Results. The median follow-up was 3.1 years (interquartile range 2.0 to 5.1). The one-year cumulative incidence of recurrent dislocation after revision was 8.7%, which increased to 18.8% at five years and 31.9% at ten years postoperatively. In multivariable analysis, a high American Society of Anesthesiologists (ASA) grade (hazard ratio (HR) 2.72 (95% confidence interval (CI) 1.13 to 6.60)), BMI between 25 and 30 kg/m. 2. (HR 4.31 (95% CI 1.52 to 12.27)), the use of specialized liners (HR 5.39 (95% CI 1.97 to 14.79) to 10.55 (95% CI 2.27 to 49.15)), lumbopelvic stiffness (HR 6.03 (95% CI 1.80 to 20.23)), and postoperative abductor weakness (HR 7.48 (95% CI 2.34 to 23.91)) were significant risk factors for recurrent dislocation. Increasing the size of the acetabular component by > 1 mm significantly decreased the risk of dislocation (HR 0.89 (95% CI 0.82 to 0.96)). The VR-12 physical and HHS (pain and function) scores improved significantly at mid term. Conclusion. Patients requiring revision THA for instability are at risk of recurrent dislocation. Higher ASA grades, being overweight, a previous lumbopelvic fusion, the use of specialized liners, and postoperative abductor weakness are significant risk factors. Cite this article: Bone Joint J 2024;106-B(5 Supple B):105–111

Instability is a common indication for revision total hip arthroplasty (THA). However, even after the initial revision, some patients continue to have recurrent dislocations. This study investigates those at risk for recurrent dislocation after revision THA for instability at a single institution. Between 2009 and 2019, 163 patients underwent revision THA for instability at a single institution. Thirty-three of these patients required re-revision THA due to recurrent dislocation. Cox proportional hazard models with death as a competing event were used to analyze risk factors, including prosthesis sizing and alignment. Paired t-tests or Wilcoxon signed rank tests were used to assess patient outcomes (Veterans RAND 12 (VR-12) physical score, VR-12 mental score, Harris Hip Score, and hip disability and osteoarthritis outcome score for joint replacement). Duration of follow-up until either re-revision or final follow-up was a mean of 45.3 ± 38.2 months. The 1-year cumulative incidence for recurrent dislocation after revision was 8.7%, which increased to 19.6% at 5 years and 32.9% at 10 years postoperatively. In the multivariable analysis, high ASA score [HR 2.71], being underweight (BMI<18 kg/m. 2. ) [HR 36.26] or overweight/obese (BMI>25 kg/m. 2. ) [HR 4.31], use of specialized liners [HR 5.51–10.71], lumbopelvic stiffness [HR 6.29], and postoperative abductor weakness [HR 7.20] were significant risk factors for recurrent dislocation. Increasing the cup size decreased the dislocation risk [HR 0.89]. The dual mobility construct did not affect the risk for recurrent dislocation in univariate or multivariable analyses. VR-12 physical and HHS (pain and function) scores improved postoperatively at midterm. Patients requiring revision THA for instability are at risk for recurrent dislocation. Higher ASA scores, abnormal BMI, use of special liners, lumbopelvic stiffness, and postoperative abductor weakness are significant risk factors for re-dislocation

Keywords. Complete Abductor Detachament, Direct Lateral Approach, Abductor Insuffenciency, Hip Arthroplasty. Backgroung. Approach of Total hip replacement (THR) is a very important part of the surgery, the approach dictates the postoperative complications. Lateral approach is one of the most commonly used approaches. The initial lateral approach relied on bony (trochanteric) osteotomy which was later modified to tendon detachment, there are many versions of the lateral approach but the main goal is to detach the hip abductors mechanism to gain access to the underlying joint. One of the modifications is to completely detach the abductors tendon, this offers superior exposure compared to the traditional partial detachment (Hardinge) approach. Objectives. We aimed to perform the first study comparing the complications rate following complete detachment of hip abductors to the documented complications rate of the traditional approach. Study Design & Methods. Retrospective study to evaluate the rate of approach specific complications following complete abductor detachment approach, we included s all patients who had THR using this approach 8–18 months ago. The study group comprised of 44 patients of different age groups and genders. Patients were reviewed to assess gait abnormality, abductor weakness with Trendlenberg test, lateral trochanteric pain (LTP) and heterotopic ossification (H.O). Results. Out of the 44 patients in our study group 20 patients had abductor weakness with positive Trendelnberg test (45.5%) while the reported percentage of abductor weakness following the traditional approach is 4–20%.7 patients (15%) were dissatisfied with the postoperative gait. LTP was reported in 5 patients (11%) compared to 4.9% associated with standard lateral approach. In our series 9 (20.4%) patients had H.O which is within the acceptable range (up to 25%). Conclusions. Complete abductor detachment approach offers better exposure and quicker alternative to the traditional lateral approach of the hip (Hardinge) but on the other hand it has relatively higher complication rate

Over the past 15 years Anterior Approach (AA) THA has shown a dramatic increase in adoption by surgeons (over 30%) and choice by patients with a corresponding decrease in the percentage of hips performed with traditional posterior and lateral approaches. I began AA in 1996 in order to solve the classic problems of potential dislocation associated with posterior approach and potential abductor weakness associated with the lateral (Harding) approach. Surgeon education on AA began in 2013 and has accelerated since. AA is usually performed with the aid of an orthopaedic table which facilitates exposure though many cases are also performed on a standard operating table. Intraoperative image intensification has provided real-time feedback and accuracy for cup position leg length and offset and is facilitated by the supine position and a radiolucent orthopaedic table, however, AA can be performed without it. Earlier functional recovery with decreased post-operative pain is the best documented benefit of AA as well as decreased dislocation rate. My own point of view is to take advantage of a switch to AA to improve more than your surgical approach. Improve also hip biomechanics, cup position, ease of surgery, bone preparation, and soft tissue handling. A proven and repeatable technique and use of available technologies will facilitate this

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

Complete or nearly complete disruption of the attachment of the gluteus is seen in 10–20% of cases at the time of THA. Special attention is needed to identify the lesion at the time of surgery because the avulsion often is visible only after a thickened hypertrophic trochanteric bursa is removed. From 1/1/09 to 12/31/13, 525 primary hip replacements were performed by a single surgeon. After all total hip components were implanted, the greater trochanteric bursa was removed, and the gluteus medius and minimus attachments to the greater trochanter were visualised and palpated. Ninety-five hips (95 patients) were found to have damage to the muscle attachments to bone. Fifty-four hips had mild damage consisting of splits in the tendon, but no frank avulsion of abductor tendon from their bone attachments. None of these cases had severe atrophy of the abductor muscles, but all had partial fatty infiltration. All hips with this mild lesion had repair of the tendons with #5 Ticron sutures to repair the tendon bundles together, and drill holes through bone to anchor the repair to the greater trochanter. Forty-one hips had severe damage with complete or nearly complete avulsion of the gluteus medius and minimus muscles from their attachments to the greater trochanter. Thirty-five of these hips had partial fatty infiltration of the abductor muscles, but all responded to electrical stimulation. The surface of the greater trochanter was denuded of soft tissue with a rongeur, the muscles were repaired with five-seven #5 Ticron mattress sutures passed through drill holes in the greater trochanter, and a gluteus maximus flap was transferred to the posterior third of the greater trochanter and sutured under the vastus lateralis. Six hips had complete detachment of the gluteus medius and minimus muscles, severe atrophy of the muscles, and poor response of the muscles to electrical stimulation. The gluteus medius and minimus muscles were sutured to the greater trochanter, and gluteus maximus flap was transferred as in the group with functioning gluteus medius and minimus muscles. Postoperatively, patients were instructed to protect the hip for 8 weeks, then abductor exercises were started. The normal hips all had negative Trendelenburg tests at 2 and 5 years postoperative with mild lateral hip pain reported by 11 patients at 2 years, and 12 patients at 5 years. In the group of 54 with mild abductor tendon damage that were treated with simple repair, positive Trendelenburg test was found in 5 hips at 2 years and in 8 hips at 5 years. Lateral hip pain was reported in 7 hips at 2 years, and in 22 at 5 years. In the group of 35 hips with severe avulsion but good muscle tissue, who underwent repair with gluteus maximus flap transfer, all had good abduction against gravity and negative Trendelenburg tests at 2 and 5 years postoperative, and none had lateral hip pain. Of the 6 hips with complete avulsion and poor muscle who underwent abductor muscle repair and gluteus maximus flap transfer, all had weak abduction against gravity, mildly positive Trendelenburg sign, and mild lateral hip pain at 2 and 5 years postoperative. Abductor avulsion is uncommon but not rare, and is detected during THA only by direct examination of the tendon and removal of the trochanteric bursa. Simple repair of mild abductor tendon damage did not prevent progressive abductor weakness in some hips; and the increase in number of patients with lateral hip pain from 2 to 5 years suggests progressive deterioration. Augmentation of the repair with a gluteus maximus flap appears to provide a stable reconstruction of the abductor muscles, and seemed to restore abductor function in the hips with functioning muscles

Avulsion of the abductor muscles of the hip may cause severe limp and pain. Limited literature is available on treatment approaches for this problem, and each has shortcomings. This study describes a muscle transfer technique to treat complete irreparable avulsion of the hip abductor muscles and tendons. Ten adult cadaver specimens were dissected to determine nerve and blood supply point of entry in the gluteus maximus and tensor fascia lata (TFL) and evaluate the feasibility and safety of transferring these muscles to substitute for the gluteus medius and minimus. In this technique, the anterior portion of the gluteus maximus and the entire TFL are mobilised and transferred to the greater trochanter such that the muscle fiber direction of the transferred muscles closely matches that of the gluteus medius and minimus. Five patients (five hips) were treated for primary irreparable disruption of the hip abductor muscles using this technique between January 2008 and April 2011. All patients had severe or moderate pain, severe abductor limp, and positive Trendelenburg sign. Patients were evaluated for pain and function at a mean of 28 months (range, 18–60 months) after surgery. All patients could actively abduct 3 months post-operatively. At 1 year post-operatively, three patients had no hip pain, two had mild pain that did not limit their activity, three had no limp, and one had mild limp. One patient fell, fractured his greater trochanter, and has persistent limp and abduction weakness. The anterior portion of the gluteus maximus and the TFL can be transferred to the greater trochanter to substitute for abductor deficiency. In this small series, the surgical procedure was reproducible and effective; further studies with more patients and longer follow-up are needed to confirm this

Revision hip approaches can be divided into posterior, anterior, transgluteal, and transtrochanteric. The approach chosen is dictated by what needs to be exposed and the approaches with which the surgeon is comfortable. The posterior approach remains posterior to the gluteus medius and protects the hip abductors. The disadvantage of a posterior approach is post-operative dislocation. The direct anterior approach is currently enjoying popularity as a primary technique. Surgeons experienced in the primary technique are applying it to revision surgery. The anterior approaches also protect the hip abductors. The disadvantage is poor access to the posterior acetabular column and mobilization of the femur to gain access to the femoral diaphysis. Transgluteal approaches split the gluteus medius typically keeping the anterior portion of the medius intact with the vastus lateralis. Proximal exposure is limited by the superior gluteal nerve, which is 4 cm above the tip of the trochanter. The disadvantage of the transgluteal approach is difficult access to the posterior acetabular column and occasional abductor weakness. The advantage of both the anterior and transgluteal approaches is a lower dislocation rate. All three approaches are acceptable for revisions that only require acetabular rim and proximal femoral exposure. More extensive exposure requires modifications to these approaches or the use of a transtrochanteric approach. Transtrochanteric approaches are defined by the length of the osteotomy (conventional or extended) and if the vastus lateralis remains attached to the trochanteric fragment (slide). Distally extended osteotomies improve access to the femur. Osteotomies without a distal attachment to the lateralis can be retracted proximally thus improving exposure of the ilium

Introduction. Complete or nearly complete disruption of the gluteus attachment is seen in 10–20% of cases at the time of total hip arthroplasty (THA). Special attention is needed to identify the lesion at the time of surgery because the avulsion often is visible only after a thickened hypertrophic trochanteric bursa is removed. The purpose of this study was to evaluate a technique designed to restore abductor function by transferring the gluteus maximus to compensate for the deficient medius and minimus muscles. Methods. From Jan 1 2009 to Dec 31 2013, 525 primary THAs were performed by the author. After the components were implanted, the greater trochanteric bursa was removed, and the gluteus medius and minimus attachments to the greater trochanter were visualized and palpated. Ninety-five hips (95 patients) were found to have damaged muscle attachments to bone. Fifty-four hips had mild damage consisting of splits in the tendon, but no frank avulsion of abductor tendon from the bone attachment. None had severe atrophy of the abductor muscles, but all had partial fatty infiltration. All hips with this mild lesion had repair of the tendons with #5 Ticron sutures to repair the tendon bundles together, anchored to the greater trochanter. Forty-one hips had severe damage with complete or nearly complete avulsion of the gluteus medius and minimus muscles from their attachments to the greater trochanter. Thirty-five of these hips had partial fatty infiltration of the abductor muscles, but all responded to electrical stimulation. The surface of the greater trochanter was denuded of soft tissue with a rongeur, the muscles were repaired with five-seven #5 Ticron mattress sutures passed through drill holes in the greater trochanter, and a gluteus maximus flap was transferred to the posterior third of the greater trochanter and sutured under the vastus lateralis. Six hips had complete detachment of the gluteus medius and minimus muscles, severe atrophy of the muscles, and poor response of the muscles to electrical stimulation. The gluteus medius and minimus muscles were sutured to the greater trochanter, and the gluteus maximus flap was transferred. Postoperatively, patients were instructed to protect the hip for 8 weeks, then abductor exercises were started. Results. The normal hips all had negative Trendelenburg tests at 2 and 5 years postoperative with mild lateral hip pain reported by 11 patients at 2 years, and 12 patients at 5 years. In the 54 with mild abductor tendon damage treated with simple repair, positive Trendelenburg test was found in 5 hips at 2 years and in 8 hips at 5 years. Lateral hip pain was reported in 7 hips at 2 years, and in 22 at 5 years. In the 35 hips with severe avulsion but good muscle tissue, who had repair with gluteus maximus flap transfer, all had good abduction against gravity and negative Trendelenburg tests at 2 and 5 years postoperative, and none had lateral hip pain. Of the 6 hips with complete avulsion and poor muscle who underwent abductor muscle repair and gluteus maximus flap transfer, all had weak abduction against gravity, mildly positive Trendelenburg sign, and mild lateral hip pain at 2 and 5 years postoperative. Conclusions. Abductor avulsion is uncommon but not rare, and is detected during THA only by direct examination of the tendon and removal of the trochanteric bursa. Simple repair of mild abductor tendon damage did not prevent progressive abductor weakness in some hips; and the increase in number of patients with lateral hip pain from 2 to 5 years suggests progressive deterioration. Augmentation of the repair with a gluteus maximus flap appears to provide stable reconstruction of the abductor muscles, and seemed to restore function in the hips with functioning muscles

Revision hip approaches can be divided into posterior, anterior, transgluteal, and transtrochanteric. The approach chosen is dictated by what needs to be exposed and the approaches with which the surgeon is comfortable. The posterior approach remains posterior to the gluteus medius and protects the hip abductors. The disadvantage of a posterior approach is post-operative dislocation. The direct anterior approach is currently enjoying popularity as a primary technique. Surgeons experienced in the primary technique are applying it to revision surgery. The anterior approaches also protect the hip abductors. The disadvantage is poor access to the posterior acetabular column and mobilisation of the femur to gain access to the femoral diaphysis. Transgluteal approaches split the gluteus medius typically keeping the anterior portion of the medius intact with the vastus lateralis. Proximal exposure is limited by the superior gluteal nerve, which is 4cm above the tip of the trochanter. The disadvantage of the transgluteal approach is difficult access to the posterior acetabular column and occasional abductor weakness. The advantage of both the anterior and transgluteal approaches is a lower dislocation rate. All three approaches are acceptable for revisions that only require acetabular rim and proximal femoral exposure. More extensive exposure requires modifications to these approaches or the use of a transtrochanteric approach. Transtrochanteric approaches are defined by the length of the osteotomy (conventional or extended) and if the vastus lateralis remains attached to the trochanteric fragment (slide). Distally extended osteotomies improve access to the femur. Osteotomies without a distal attachment to the lateralis can be retracted proximally thus improving exposure of the ileum

Electromyographic and clinical studies were performed on patients undergoing total hip replacement by the modified direct lateral (29 hips), the direct lateral (29 hips) and the posterior approaches (21 hips). Assessments were made three months after operation. The Trendelenburg test was positive (Grade II) in eight cases operated upon by the direct lateral route, but in only one of each of the other two groups. Denervation occurred in only five of the 28 hips with abductor weakness without statistical difference between the groups. In the modified direct lateral group, radiological evidence of union of the trochanteric sliver was associated with significantly better abductor function than in those with malunion or non-union

Introduction: Femoral offset plays an important part in the biomechanics of the hip with inaccurate balancing at the time of arthroplasty leading to abductor weakness, leg length discrepancies and altered wear characteristics. Aim: To look at the degree of external rotation of the leg at the time of pre-operative x-rays and to assess the effect of this on templating for femoral offset. Methods: A radiological review of a cohort of patients attending for hip arthroplasty with unilateral osteoarthritis. Results: Externally rotated posturing of the affected leg is common amongst patients with osteoarthritis attending for hip arthroplasty. The effect of this change in the positioning of the femoral neck is to create an apparent reduction in the offset of the femoral shaft. This will lead to underestimation of the correct offset for the chosen prosthesis. In over 50% of cases templating would have been incorrect. Conclusions: When templating prior to hip arthroplasty surgery an assessment of the profile of the lesser trochanter will give an impression of the leg position. If this is externally rotated it should be presumed that the offset will be larger than the measured value. If the other hip is in a better rotational position this should be used for assessment

1. The treatment of contractures at the hip secondary to poliomyelitis by Soutter's muscle slide or by Yount's fasciotomy gives excellent results. So does high femoral osteotomy, but it is not superior to the other two and should therefore be kept in reserve as a supplementary operation for the completion of correction of a deformity so gross as not to be wholly remediable by division of the soft parts. 2. Subluxation of the hip occurs only if the paralysis comes on during the first eighteen months of life and is a product not of severe paralysis but of unbalanced and often slight weakness of muscles. Correction of the invariable valgus deformity of the femoral neck by osteotomy is followed by relapse; acetabuloplasty too is unreliable. The most promising remedy seems to be some form of acetabuloplasty combined with transplantation of an iliopsoas of adequate strength into the greater trochanter. The indications for arthrodesis are few, but the results of this operation are good. 3. In the few patients with abductor weakness and little else the dipping gait may be abolished by iliopsoas transplantation

Background: Abductor failure after total hip arthroplasty is a rare but debilitating problem. The diagnosis is difficult, and when recognized, there are few successful treatment options. The purpose of this study is to review our experience with a new surgical technique using fresh-frozen Achilles tendon allograft with an attached calcaneal bone graft to reconstruct a deficient abductor mechanism after total hip arthroplasty. Methods: From 2003 to 2006, we performed seven abductor reconstructions with Achilles tendon allograft for patients with abductor deficiency after total hip arthroplasty. Four patients had a prior posterior approach and three had a prior anterolateral approach. At a mean of 29 months from index procedure, all seven patients suffered from symptoms of lateral hip pain and abductor weakness as documented by positive Trendelenburg sign, limp, and limited motor strength with side-lying abduction. Hip arthrograms were obtained in five of seven patients. Results: The average pre-reconstruction Harris Hip Score was 34.7 and average pain score was 11.4. All five hip arthrograms showed extravasation of dye over the greater trochanter, confirming the diagnosis of a bald greater trochanter and massive abductor loss found at time of surgery. At a minimum 24 month follow-up and an average follow-up of 31 months, the post-reconstruction Harris Hip Score was 85.9 and the average pain score was 38.9. Conclusions: Abductor reconstruction with Achilles tendon allograft using calcaneal bone block fastened to the greater trochanter has offered significant relief of pain and improvement in function at early follow-up in this series of patients

Introduction. Some patients with Cerebral Palsy who had a de-rotation osteotomy performed for correction of excessive anteversion had persistence of internal foot progression even after surgery. Potential causes which have been implicated include: weak hip abductors, spasticity of the anterior fibres of the gluteus medius, hip adductor spasm and persistent femoral anterversion. The aim of this study was to see if there is any relationship between significant abductor weakness [less than Grade III: MRC] and persistence of internal foot progression. Methods. We included all ambulatory patients with cerebral palsy who had had a derotation osteotomy between the periods of 2000-2005, who had also had a pre and post operative gait analysis, assessment of anteversion [Gage Test], hip range of motion and muscle charting. There were 12 patients [17 hips, 5 bilateral] with an average age of 13. Seven were diplegic, two hemiplegic and three had asymmetric diplegia. Data was assessed using SPSS13.0. The Spearman Co-relation Coefficient was used to test if there was any correlation. Results. Of the 17 limbs operated, pre-operative femoral anteversion was 20-60 degrees [mean: 45] and post op femoral anteversion was 0-35 [mean: 15]. Of these, 7 hips had persistent internal rotation gait on gait analysis. None of the patients with persistent internal rotation had any hip capsular contractures, and there was no significant change in abductor power after surgery. On testing the hypothesis it was found that there is no relationship between weak hip abductors and persistent internal rotation. [r = -0.07]. Conclusion. This study suggests that hip abductor muscle weakness may not be a cause for the persistence of the internal foot progression. Significance: Weak abductor power is not a contraindication to de-rotation osteotomies and do not affect outcome

Purpose: Some patients with Cerebral Palsy who had a de-rotation osteotomy performed for correction of excessive anteversion had persistence of internal foot progression even after the surgery. The aim of this study was to see if there is any relationship between significant abductor weakness [less than Grade III: MRC] and persistence of internal foot progression. Methods: We included all ambulatory patients with cerebral palsy who had had a de-rotation osteotomy between the periods of 2000 – 2005, who had also had a pre and post operative gait analysis, assessment of anteversion, muscle charting and hip range of movements. There were 12 patients [17 hips, 5 bilateral] 5 male 7 female with an average age of 13. Seven were diplegic, two hemiplegic and three had asymmetric diplegia. Data was assessed using SPSS 13.0. As the data was found to be normally distributed the Fisher exact test and the Spearman’s Co-relation Coefficient was used. Results: Of the 17 limbs operated, preoperative femoral anteversion was 20–60 degrees [mean: 45] and post op femoral anteversion was 0–35[mean: 15]. Of these 7 hips had persistent internal rotation gait on gait analysis. None of these patients with persistent internal rotation had any hip capsular contractures, and there was no significant change in abductor power after surgery. On testing the hypothesis it was found that there is no relationship between weak hip abductors and persistent internal rotation. [Fisher exact test: p value: 0.8, r = −0.07]. Conclusion: Weak abductors may not be a cause of persistent internal rotation following de-rotation osteotomy. Weak abductor power is not a contraindication to de-rotation osteotomies and do not affect outcome of surgery

Purpose: Some patients with Cerebral Palsy who had a de-rotation osteotomy performed for correction of excessive anteversion had persistence of internal foot progression even after the surgery. The aim of this study was to see if there is any relationship between significant abductor weakness [less than Grade III: MRC] and persistence of internal foot progression. Methods: We included all ambulatory patients with cerebral palsy who had had a de-rotation osteotomy between the periods of 2000 – 2005, who had also had a pre and post operative gait analysis, assessment of ante-version, muscle charting and hip range of movements. There were 12 patients [17 hips, 5 bilateral] 5 male 7 female with an average age of 13. Seven were diplegic, two hemiplegic and three had asymmetric diplegia. Data was assessed using SPSS 13.0. As the data was found to be normally distributed the Fisher exact test and the Spearman’s Co-relation Coefficient was used. Results: Of the 17 limbs operated, preoperative femoral anteversion was 20–60 degrees [mean: 45] and post op femoral anteversion was 0–35[mean: 15]. Of these 7 hips had persistent internal rotation gait on gait analysis. None of these patients with persistent internal rotation had any hip capsular contractures, and there was no significant change in abductor power after surgery. On testing the hypothesis it was found that there is no relationship between weak hip abductors and persistent internal rotation. [Fisher exact test: p value: 0.8, r = -0.07]. Conclusion: Weak abductors may not be a cause of persistent internal rotation following de-rotation osteotomy. Weak abductor power is not a contraindication to de-rotation osteotomies and do not affect outcome of surgery

We examined the position of the superior gluteal nerve in forty-four cadaveric hips in relation to the greater trochanter and the acetabulum . We found that the nerve lay a mean of 4.8 centimetres from the greater trochanter with a range of two to nine centimetres and a mean of 3.2 centimetres from the acetabulum. The nerve was visibly damaged in three out of forty-four hips following direct lateral approach. Our study does not support the “safe zone” proximal to the greater trochanter and suggests the proximity of the nerve to the acetabulum as a potential cause of nerve injury. Abductor weakness following the direct lateral approach to the hip is well described and is associated with damage to the superior gluteal nerve on neurophysiological testing in from 23–26 %. A “safe zone” has been described of up to five centimeters proximal to the greater trochanter. We examined forty-four cadaveric hips exposed by the direct lateral approach by surgeons not directly involved with the study. We measured the position of the superior gluteal nerve in relation to the greater trochanter, the acetabulum and the margin of the skin incision. We examined the nerve for visible signs of damage. We found the position of the superior gluteal nerve to be a mean of 4.8 centimeters from the greater trochanter (range two to nine), 3.2 centimeters from the superior margin of the acetabulum (range one to eight), and 4.1 centimeters from the margin of the skin incision. There was visible damage to the nerve in three of forty-four cases. Neurophysiological studies show subclinical damage to the superior gluteal nerve in up to 77% of cases following direct lateral approach to the hip and in association with abductor weakness in 23–26%. Our study does not support the notion of a “safe zone” of five centimetres proximal to the greater trochanter, and with a mean of 4.8 centimetres the zone is unsafe more often than it is safe. The proximity of the superior gluteal nerve to the superior margin of the acetabulum suggests that it may be damaged by retractor placement at this site

Hip prostheses that do not reproduce the patients’ preoperative femoral offset have been correlated with increased wear rate, instability, abductor weakness and reduced range of motion. We have reviewed the results of 54 primary low friction arthroplasties with low offset stem commonly called “¾ neck Charnley” in 49 patients (47 females and 2 males). There has been no publication in literature on the results of this stem. Mean age was 68 years (range 30 to 83). The operations were performed by one of us, (VR) as an orthopaedic trainee, with a mean follow up of 8.7 ± 2 years. The preoperative diagnosis was 40 OA, 8 protrusio, 2 DDH, 2 post-traumatic, 1 SUFE and 1 RA. The preoperative offset was 41.9 ± 7.1 mm (mean ± STD), weight 65 ± 8.4 kg, height 156.4 ± 8 cm. At their latest review 3 cases had been revised for infection or recurrent instability with a survivorship of 93.5% using Kaplan Meyer’s analysis. None of the femoral or acetabular components were loose or at risk of loosening. 16 cups showed demarcation in 1 zone of ≤ 1mm, and 2 cups had a 2 mm demarcation in 2 zones that was not progressive. 7 stems had ≤ 1mm demarcation in 1 zone, and 5 stems at 2 zones. Condensation at the tip of the stem was noted in 2 hips. The linear wear rate was 0.2 ± 0.08mm/year. Using Pearson’s correlation coefficient with P< 0.05, no statistically significant correlation was found between the preoperative offset and the linear wear rate. We believe that the surgeon should try to reproduce the patient’s femoral offset aiming for the best intra-operative soft tissue balance. The linear wear rate in this series is higher than previously reported in cases that survived for over 20 years from this unit. However, at this stage of analysis low offset Charnley stems produce good medium term results

Introduction. Our classic outcome scores increasingly fail to distinguish interventions or to reflect rising patient demands. Scores are subjective, have a low ceiling and score pain rather than function. Objective functional assessment tools for routine clinical use are required. This study validates inertial sensor motion analysis (IMA) by differentiating patients with knee versus hip osteoarthritis in a block-step test. Methods. Step up and down from a block (h=20cm, 3 repetitions) loading the affected (A) and unaffected (UA) leg was measured in n=59 subjects using a small inertial sensor (3D gyro and accelerometer, m=39g) attached onto the sacrum. Patients indicated for either primary unilateral THA (n=20; m/f=4/6, age=69.4yrs ±9.8) or TKA (n=16;m/f=7/9;age=67.8yrs ±8.2) were compared to healthy controls (n=23;m/f=13/10;age=61.7yrs ±6.2) and between each other to validate the test's capacity for diagnostics and as an outcome measure. The motion parameters derived (semi-) automatically in Matlab for both legs were: front-back (FB-) sway and left-right (LR-) sway (up and down); peak-to-peak accelerations (Acc) during step down. In addition the asymmetry between both legs (ASS) was calculated for each parameter. Group differences were tested (t-test) and the diagnostic value determined by the area under the curve (AUC) of the ROC-curve. Results. During step-up FB-sway was higher for THA (20.4°±4.9) and TKA (21.7°±5.9) patients than for healthy controls (15.5°±3.4, p<0.001). Also asymmetry was higher (THA=20%, TKA=21%, H=11%, p<0.001). Results were similar during step down except for the affected leg of THA patients where FB-sway (THA=16.2°±3.0) was similar to controls but sign. different to TKA patients (22.2±4.4) producing a high diagnostic power (AUC=0.88) to differentiate THA and TKA. LR-sway was also indicative for THA patients being the only subjects showing high asymmetry between the legs (A=14.3°±3.7 vs UA=11.9°±3.1, p<0.001). Acceleration during step-down asymmetric in patients, especially in THA (H<TKA<THA;p<0.05; AUC=0.87). Discussion. The IMA-block-step test could detect pathology specific compensation mechanism: During step-up patients use more FB-sway (+29%) to generate momentum for compensating muscle weakness and decrease joint loading. During step-down, only THA patients showed less FB-sway with their affected leg avoiding the painful hip flexion. Also in THA the LR-sway was higher in the affected than unaffected side due to the typical abductor weakness and resulting Trendelenburg sign. The IMA-block-step test could objectify compensation mechanisms used in OA and showed the power to differentiate between H, TKA and THA. It is low cost and fast to perform (<5min) by non-specialist personnel and thus could be used in clinical routine to supplement questionnaire based outcome scores