[Periacetabular osteotomy medium term survival in adult acetabular dysplasia]

Acetabular dysplasia is a recognized cause of early onset degenerative hip disease. With the widespread use of arthroplasty, the role for conservative treatment has become a controversial issue. Periacetabular osteotomy (PAO) as proposed by Ganz has several advantages, but remains a technically difficult procedure. The purpose of this work was to assess our mid-term results considering indications and potential complications and to describe changes in our technique.

This study included 33 dysplasic hips in 24 women and four men, treated by PAO. Mean age was 32 years (range 18-47). Mean follow-up was 12 years (range 2-19). The radiographic work-up included an anteroposterior view of the pelvis and anterior and Lequesne oblique views of the hip joint. The cephalocervicodiaphyseal (CC'D), lateral cover (VCE), anterior cover (VCA), and acetabular roof horizontality (HTE) angles and noted whether osteoarthritis was present or not. Hips were classified with the Hip Study Group system as moderate dysplasia (VCE and VCA 25 degrees to 21 degrees ), severe dysplasia (20 degrees to 5 degrees ) and extreme dysplasia (less than 5 degrees ). The complete work-up included an assessment of joint congruency with recentered films in addition to the surgical lateral view of the hip in order to determine a new index called S/FH (S: acetabular surface, FH: half of the femoral head surface). ArthroCT and MRI were performed in patients with signs of osteoarthritis. The original technique included three cuts (ilio-ischiatic, iliopubic, and iliac) close to the acetabulum using a triple access: infracoxofemoral, intrapelvic, and extrapelvic. The first change in the technique was an osteotomy of the anterosuperior iliac spine and an oblique iliac cut farther from the acetabulum.

Preoperatively, average angle measurements were as follows: 135 degrees (121 to 150 degrees ) for CC'D, 23.2 degrees (3 degrees to 40 degrees ) for HTE, 7.6 degrees (-14 degrees to 22 degrees ) for VCE, 11.3 degrees (-26 degrees to 32 degrees ) for VCA. Postoperatively, the values were as follows: 134.5 degrees (121 degrees to 150 degrees ) for CC'D, 9.5 degrees (-9 degrees to 20 degrees ) for HTE, 31.7 degrees (14 degrees to 60 degrees ) for VCE and 31.7 degrees (10 degrees to 48 degrees ) for VCA. An intertrochanteric osteotomy was also performed in one patient. The mean Postel-Merle-d'Aubigné score improved from 7.5 points (range 5.6-11) preoperatively to 14.9 (range 8.1-18). At last follow-up, there was no sign of osetoarthritic degradation in 17 patients (51.5%). Seven patients required total hip arthroplasty at mean four years (two to nine years), including one for aseptic acetabular necrosis. Survival was 73.8+/-9 % at 12 years.

This study confirmed the importance of PAO as part of the therapeutic armamentarium for conservative treatment of acetabular dyplasia. Several changes were made in the original technique: the three cuts were all done via the intrapelvic access; for severe and extreme dysplasia, a two thirds PAO was performed. At the present time, the best indication appears to be young subjects (aged less than 30 years) with moderate to severe dysplasia, with no sign (even minimal) of intra-articular disorder or osteoarthritis.