Purpose. This study aims to report the radiological corrections achieved and complication profile of Peri-Acetabular Osteotomy (PAO) undertaken through the minimally invasive approach. Method. 106 PAOs were performed in 103 patients, by senior author, using a minimally invasive approach from 2007 to 2015. Pre- and post-operative radiographs were reviewed and the degree of acetabular re-orientation was analysed. Case notes were examined retrospectively to identify haemoglobin levels and complications across two sites. Results. 73 female and 30 male patients underwent PAO procedures at a mean age of 25 years (9 – 54 years). Follow-up ranged from 23 to 80 months. 26 patients had concurrent proximal femoral osteotomies. Pre-operatively the average centre edge angle measured −1.6° with the vertical centre edge angle reading −0.2°. Post-operative radiographs confirmed correction of these values to 30° and 25.1° respectively. Sharp's angle also improved from a mean value of 49.5° to 33.3°. Review of the Tönnis angle showed correction from an average of 24.1° to 6.9°. The average drop in haemoglobin was calculated as 39 g/L with around 50 % of the patients requiring a peri-operative blood transfusion. The mean preoperative modified Harris Hip Score was 65.6 (Standard deviation σ=11.6) and the same at follow-up was 84.1(σ=11.5). Our outcome scores were comparable with recent PAO series including that of Gray et al. 10 patients reported lateral cutaneous nerve hypoesthesia and 9 had problematic screws. 2 patients underwent washouts as treatment for haematoma and infection. 4 patients had delayed union of the pubic osteotomy and a further 8 patients had asymptomatic osteotomy non-union. One posterior column non-union necessitated plating. One painful fibrous union of ischium and 3 inferior pubic rami stress fractures. Conclusion. This study shows that minimally invasive approach has favourable outcomes and that it is feasible to achieve adequate correction with results/complication profile comparable to traditional approach

Purpose of the study is to investigate the outcome of the patients with Perthes disease who have had a surgical dislocation of their hip for the treatment of resultant symptoms from the disease process. Retrospective review of consecutive patients treated with surgical dislocation of the hip for Perthes disease. Review of clinical case notes and radiological imaging. Patient outcome was assessed at follow-up. Between 2010 and 2015, 31 cases of surgical hip dislocation were performed for Perthes disease at our institution by 2 senior surgeons. Age range at time of surgery was 12–33. Male:female ratio was 13:18; right:left ratio was 15:17. Age at the time of Perthes diagnosis was between 3 and 13 years, with 3 diagnosed retrospectively. Mean follow-up was 18months. All patients had an EUA and arthrogram while 61.3%(19/31) had previous surgery for Perthes. 71%(22/31) required a labral repair, 6.5%(2/31) had a peri-acetabular osteotomy at the time of surgery and 3.2%(1/31) required a proximal femoral valgus osteotomy. 22.5%(7/31) required microfracture (femoral head or acetabulum): all of whom had evidence of contained area of degenerative changes on preoperative MRI. 64.5%(20/31) had the trochanteric screws removed. Complications included 1 greater trochanter non-union, 1 pain secondary to suture anchor impinging on psoas tendon, 1 AVN leading to early THR 12 months post-op. Another 2 had further deterioration of degenerative changes and pain leading to THR 18 and 24 months post-op. All 3(9.7%) had microfracture at the time of the dislocation for established degenerative change and also required custom made prostheses. Surgical hip dislocation is an option in treating Perthes patient with resultant symptoms such as impingement. Improved outcome is seen in patients who are younger with a congruent hip joint in contrast to those with established degenerative change evident on MRI / intraoperatively and have an arrow shaped femoral head

A total of 47 non-walking patients (52 hips) with severe cerebral palsy and with a mean age of 14 years, (9 to 27) underwent a Dega-type pelvic osteotomy after closure of the triradiate cartilage, together with a derotation varus-shortening femoral osteotomy and soft-tissue correction for hip displacement which caused pain and/or difficulties in sitting. The mean follow-up was 48 months (12 to 153). The migration percentage improved from a pre-operative mean of 70% (26% to 100%) to 10% (0% to 100%) post-operatively. In five hips the post-operative migration percentage was greater than 25%, which was associated with continuing pain in two patients. Three patients had persistent hip pain and a migration percentage less than 25%. In five hips a fracture through the acetabulum occurred, and in another there was avascular necrosis of the superior acetabular segment, but these had no adverse effect on functional outcome. We conclude that it is possible to perform a satisfactory pelvic osteotomy of this type in these patients after the triradiate cartilage has been closed.

Proximal femoral varus osteotomy improves the biomechanics of the hip and can stimulate normal acetabular development in a dysplastic hip. Medial closing wedge osteotomy remains the most popular technique, but is associated with shortening of the ipsilateral femur.

We produced a trigonometric formula which may be used pre-operatively to predict the resultant leg length discrepancy (LLD). We retrospectively examined the influence of the choice of angle in a closing wedge femoral osteotomy on LLD in 120 patients (135 osteotomies, 53% male, mean age six years, (3 to 21), 96% caucasian) over a 15-year period (1998 to 2013). A total of 16 of these patients were excluded due to under or over varus correction. The patients were divided into three age groups: paediatric (< 10 years), adolescent (10 to 16 years) and adult (> 16 years). When using the same saw blades as in this series, the results indicated that for each 10° of angle of resection the resultant LLD equates approximately to multiples of 4 mm, 8 mm and 12 mm in the three age groups, respectively.

Statistical testing of the 59 patients who had a complete set of pre- and post-operative standing long leg radiographs, revealed a Pearson’s correlation coefficient for predicted versus radiologically observed shortening when using a wedge of either 10° or 20° of 0.93 (p <  0.001). The 95% limits of agreement from the Bland–Altman analysis for this subgroup were –3.5 mm to +3.3 mm. It has been accepted that a 10 mm discrepancy is clinically acceptable.

This study identified a geometric model that provided satisfactory accuracy when using specific saw blades of known thicknesses for this formula to be used in clinical practice.

Cite this article: Bone Joint J 2014;96-B:1124–9