Executing an extended retinacular flap containing the blood supply for the femoral head, reduction osteotomy (FHO) can be performed, increasing the potential of correction of complex hip morphologies. The aim of this study was to analyse the safety of the procedure and report the clinical and radiographic results in skeletally mature patients with a minimum follow up of two years.

Twelve symptomatic patients (12 hips) with a mean age of 17 years underwent FHO using surgical hip dislocation and an extended soft tissue flap. Radiographs and magnetic resonance imaging producing radial cuts (MRI) were obtained before surgery and radiographs after surgery to evaluate articular congruency, cartilage damage and morphologic parameters. Clinical functional evaluation was done using the Non-Arthritic Hip Score (NAHS), the Hip Outcome Score (HOS), and the modified Harris Hip Score (mHHS).

After surgery, at the latest follow-up no symptomatic avascular necrosis was observed and all osteotomies healed without complications. Femoral head size index improved from 120 ± 10% to 100 ± 10% (p<0,05). Femoral head sphericity index improved from 71 ± 10% before surgery to 91 ± 7% after surgery (p<0,05). Femoral head extrusion index improved from 37 ± 17% to 5 ± 6% (p< 0,05). Twenty five percent of patients had an intact Shenton line before surgery. After surgery this percentage was 75% (p<0,05). The NAHS score improved from a mean of 41 ± 18 to 69 ± 9 points after surgery (p< 0,05). The HOS score improve from 56 ± 24 to 83 ± 17 points after surgery (p< 0,05) and the mHHS score improved from 46 ± 15 before surgery to 76 ± 13 points after surgery (p< 0,05).

In this series, femoral head osteotomy could be considered as safe procedure with considerable potential to correct hip deformities and improve patients reported outcome measures (PROMS).

Level of evidence - Level IV, therapeutic study

Keywords - Femoral head osteotomy, Perthes disease, acetabular dysplasia, coxa plana

Introduction: Hip Surgical Dislocation (SHD) according the technique described by Ganz et al. is a safe and powerful tool to access intra-articular hip pathology in adults. Some indications may also arise in younger patients to correct slipped capital femoral epiphysis or femoral neck deformities

Materials and Methods: From 2004 to 2008 we have selected 45 patients on whom the procedure was done to treat femoroacetabular impingement (FAI). The average follow up time is 3 years, and patient mean age 26 years. The indications for SHD were:

mixed FAI in 26 cases,

42 hips where graded as Tönnis 0 and 2 as Tönnis 1. All patients where evaluated according to the non arthritic hip score (NAHS – McCarthy et all) before and after the surgery at 3, 6, 12, 24 and 36 months. Osyrix^® software was used to measure radiographic parameters. The numeric variables where treated using SPSS for windows (paired t student test).

Surgical Technique: In all 45 cases we did SHD, acetabular and/or femoral head neck junction trimming and labrum refixation. In half cases an anterior step trochanteric osteotomy was done and in 7 cases additional relative neck lengthening was performed.

Results: The average alfa angle measured in the standard crosstable view x ray was 72° before surgery and 36° after surgery (p=0,0001). The NAHS before surgery was 40,8 average: 9,71 – pain; 6,9 – symptoms; 9 – function and 6,9 – activities and after surgery 76,38 average (p= 0,0001) 17,5 – pain (p= 0,0001); 12,9 – symptoms (p= 0,0001); 16 - function (p= 0,0001) and 14,9 - activities (p= 0,0001). All patients improved motion, specially flexion, internal rotation (p= 0,0001). The results did not differ significantly in the patients who had a trochanteric anterior step osteotomy. One patient had a total hip replacement for ongoing osteoartrithis

We had no avascular necrosis so far and no neurovascular damage. Trochanteric screw removal was done in 3 cases for local irritation. We had 2 capsule adhesions, released shortly after using arthroscopy.

Conclusions: SHD is a demanding technique with full access to femoral head and acetabular deformities as well as cartilage or labral tears. It can be done safely with a low complication rate. The best results are achieved in young patients without degenerative cartilage and significant labrum changes. Hip degenerative changes contraindicates this procedure. Modification of trochanteric osteotomy does not seem to influence results