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There is limited knowledge regarding the anatomic relationships and functional anatomy of the Obturator Externus muscle (OE). It is described as a muscle which originates from the external bony margin of the obturator foramen with a cylindrical tendon which passes like a sling under the femoral neck and inserts in the trochanteric fossa. The primary aim of this study is to describe the OE morphology and its anatomic relationship to the acetabulum. A secondary aim is to postulate its action. Eighteen fresh human cadaveric hips were dissected to investigate the anatomy of the OE. A plastic model of the pelvis and femur was used to create a string model based on a technique previously described by Beck et al. The plastic model was used to determine the function of the OE. We conclude that the Obturator externus muscle helps to stabilise the head of the femur in the socket. The mechanical model demonstrated that the primary action of the obturator externus muscle was to externally rotate the femur when the hip was in neutral position and flexed at 90°. Its secondary function was as an adductor when the hip was in flexion.

The analysis and treatment of hips with healed Legg-Calvé-Perthes disease (LCPD) differs substantially from the treatment in the acute phase of the disease. More specifically, the treating orthopaedic surgeon is often faced with a complex three-dimensional pathomorphology of the hip that is difficult to understand and correct. To date, none of the current classification systems provide a useful decision-making algorithm with regards to the type of surgical intervention necessary to improve hip function in patients with sequelae of LCPD. The conceptual recognition of the femoroacetabular impingement (FAI) and the ability to safely dislocate the hip have revolutionised our diagnostic and therapeutic algorithm for joint-preserving surgery of hips with structural residuals of LCPD. We present a systematic approach to analyse femoral and acetabular pathomorphologic features. The resulting pathomechanisms and the surgical treatment options are presented.

Introduction With excessive acetabular coverage, such as coxa profunda or protrusio, contact between the femoral neck and acetabular rim cause direct damage to the labrochondral junction, and indirect edge loading from a levering effect which may result in hip arthrosis. Arthrosis may be delayed or avoided by addressing the overcoverage and restoring mechanical function of the labrum. We describe four cases of adjunctive complete acetabular labral replacement for circumferential, irreparable labral injury using fresh frozen semitendinous allografts through surgical hip dislocation. Materials and Methods Over a two-year period four patients (age range: 20 to 47 years) underwent surgical hip dislocation to address femoroacetabular impingement with rim trimming, femoral osteochondroplasty, and labral reconstruction. Pre- and postoperative patient reported outcomes were assessed by Oxford Hip Score (OHS), Hip Outcome Score (HOS), and Global Treatment Outcome (GTO) score. Disease progression was graded using AP pelvic radiographs and arthroMR. Results The average LCE correction was 18° (range 7-25°), achieving an average LCE of 33° (range 32-35) postoperatively. Using protected weight bearing all trochanteric osteotomies healed within six weeks after surgery. OA did not progress in any hips. Mean OHS and HOS scores improved 6.3 and 19.8 at one-year follow up. All four patients reported good results according to the GTO. There were two adverse events that resolved and did not affect outcome. Summary and Conclusions Despite complex deformities and preexisting cartilage and labrum wear in this young cohort, three of four patients reported significant functional improvement after treatment of this rare condition. Preliminary experience with circumferential labral reconstruction using hamstring allografts is promising, although long-term data needs to be established.

Acetabular retroversion following acetabular osteotomy in hips with dysplasia can negatively effect the outcome. Total retroversion, where the entire anterior rim is lateral to the posterior rim, is rare and can easily be missed on pelvic radiographs due to the lack of a crossover sign. We evaluated the clinical and radiographic presentation, the surgical management, and the outcome of hips with total acetabular retroversion. We retrospectively reviewed 26 patients (26 hips) with total retroversion following 15 periacetabular osteotomies (PAO) (1), 10 triple type, and one Salter osteotomy (2). We obtained range of motion (ROM), anterior impingement test, Drehmann's sign, Merle d'Aubigné-Postel score, and Tönnis score for osteoarthrosis. Corrective surgery included 19 revision PAOs and seven total hip arthroplasties (THA). The mean follow-up was 4.7 ± 4.2 (range 0.5-13.8) years. Patients presented with a restricted ROM (flexion and internal rotation), a positive anterior impingement test, a positive Drehmann's sign, and a decreased Merle d'Aubigné-Postel score due to pain. Corrective surgery was performed after mean of 7 ± 5 (1-15) years. Complications for revision PAO and THA occurred in 37% and 29%, respectively. At follow-up, the Merle d'Aubigné-Postel score improved for both revision PAOs and THAs. The prevalence of a positive anterior impingement test and Drehmann's sign decreased for revision PAOs. There was a tendency for progression of OA in hips with revision PAO. Iatrogenic total acetabular retroversion following reorientation is a disabling condition for the patients. Corrective surgery including revision PAO and THA results in improved clinical outcome. However, these procedures are technically challenging and associated with high complication rates.

Controversies exist regarding the best treatment for slipped capital femoral epiphysis (SCFE). Subcapital anatomical reorientation of the epiphysis by surgical dislocation and a retinacular soft tissue flap has been described recently as an effective approach. We evaluated the clinical and radiographic efficacy of this technique and compared these to published results. A series of 20 SCFE (18 stable, 2 unstable) treated by subcapital re-orientation through surgical hip dislocation and an extended retinacular soft tissue flap was reviewed retrospectively. Preoperatively and at most recent follow-up, patients were clinically examined with regard to pain and function according to the Harris hip score and to the Western Ontario and McMaster universities (WOMAC) score. Radiological examination included measurement of preoperative and postoperative anteroposterior (AP) and lateral (L) Southwick angles; and at follow-up the alpha angle was measured. The average follow-up time was 24 months. The mean WOMAC score was 2.80 post-operatively. The mean pre-operative slip angle was 40.2 degrees on the AP view and 50.65 degrees on the lateral view. Post-operatively, the mean values were 7,20 degrees on the AP view and 9,45 degrees on the lateral view. The mean post-operative average alpha angle was 43,11 degrees. No cases of avascular necrosis were seen. Our short term clinical and radiographic results are similar to outcomes published in the recent literature. The small number of technical complications appears favourable considering the surgical complexity of the procedure, and our technique offers clear advantages in treating these complex deformities.

We present a case of epiphyseal reperfusion in a 12-year-old boy following subcapital realignment of a unstable slipped capital femoral epiphysis. The case demonstrates that even if delayed, anatomical surgical realignment of the femoral head can be successful in preserving or reestablishing blood flow to the femoral epiphysis.

One theory for the aetiology of osteoarthrosis of the hip is the impingement of the anterior femoral neck against the acetabulum in flexion. The reduced femoral head-neck offset not visible on AP-radiography is implicated in this impingement. The anterior part of the head-neck region is well visualised on cross table lateral radiographs. A retrospective analysis of the offset using cross table lateral radiographs was therefore performed on twelve symptomatic and ten asymptomatic hips. The anterior offset (AOS) was defined as the difference in radius between the anterior femoral head and the anterior femoral neck. The offset ratio (OSR) was defined as the AOS divided by the femoral head diameter. The AOS was 11.6 ± 0.7 mm in the asymptomatic group and 7.2 ± 0.7 mm in the symptomatic group, which was statistically significantly different (p=0.0006). The OSR was 0.21 ± 0.03 in the asymptomatic group and 0.13 ± 0.05 in the symptomatic group, which was also statistically significantly different (p=0.0004). Cross-table lateral radiographs of the hip are useful for screening patients complaining of anterior femoro-acetabular impingement symptoms, as their anterior femoral head-neck offset may be smaller.

The Bernese periacetabular osteotomy is a joint preserving procedure used in young adults to improve acetabular coverage and stabilize the femoral head. This juxta-articular osteotomy respects the vascular blood supply to the acetabular fragment. It facilitates extensive acetabular reorientation and can be combined with a femoral osteotomy. All acetabular osteotomy steps are performed using the modified Smith-Petersen approach. Anterior joint inspection provides information on acetabular rim pathology and allows control of an impingement free range of motion. The posterior column remains mechanically intact allowing minimal internal fixation and early mobilisation. The dimensions of the true pelvis remain unchanged permitting vaginal delivery. Over 700 pelvic osteotomies have been performed since the introduction of the Bernese periacetabular osteotomy. A greater than 10 year follow-up of the first 75 osteotomies revealed hip joint preservation in 82% of cases with a good to excellent result in 73%. Poor results correlated with increased age, pre-existing arthritis, labral pathology and the amount of correction. Treatment of the labral lesions was performed only if unstable and included either refixation or resection.