Dysfunction of acetabular dysplasia is a complex problem which includes excessive stresses on the cartilage, dynamic instability and muscular fatigue eventually leading to degenerative osteoarthrosis if left uncorrected. The most physiologic solution for a young adult with this problem is to redirect the acetabulum into a normal position. Rotational acetabular osteotomy developed in Japan aims to transfer the position of the acetabulum en bloc by circumacetabular osteotomy using the curved osteotome. Because of same curvatures of osteotomy surfaces, this osteotomy produces the greater contact among bony surfaces, stable fixation and early solid union. However, this osteotomy requires abductors splitting, leaves acetabular teardrop in its original position, and has the risk of postoperative avascular necrosis of the transferred acetabulum. Bernese periacetabular osteotomy developed by Ganz also provides good coverage of the femoral head by redirecting the acetabulum. This osteotomy preserves the vascular supply of the transferred acetabulum and allows medialization of the hip joint. On the other hand, it poses the risk of considerable morbidities due to extensive exposure, and major and/or moderate complications, such as bleeding complications, reflex sympathetic dystrophy, motor nerve palsy and heterotopic ossification are reported. In order to reduce these disadvantages, we developed a curved periacetabular osteotomy (CPO), for the treatment of hip dysplasias and have performed CPO on more than 400 hips since 1995. Both an imaging of the margin of the hip presumed to be on the quadrilateral surface and a sophisticated operative technique are needed for CPO. However, the extent of soft tissue dissection is limited with abductors left intact, and the osteotomy surfaces retain their original curvature. There have been no major or moderate complications. These advantages seem to reduce postoperative complications and promote early postoperative rehabilitation.

Recently, we compared surgical invasion and complications in patients aged over 40 years who underwent CPO (n=30) or total hip arthroplasty (THA; n=30) using postoperative levels of interleukin (IL)-6 and C-reactive protein (CRP). The mean IL-6 levels were 55.4 pg/ml and 89.5 in the CPO and THA groups, respectively (p< 0.001). The mean CRP levels were 4.5 mg/dl and 5.8 in the CPO and THA groups, respectively (p< 0.01). No major or moderate complications were encountered in either group. CPO appears to be a less invasive and safer surgical procedure for middle-aged patients than THA.

The existing methods of assessing limb lengthening during total hip arthroplasty (THA) are prone to error because the measurements are not parallel to the limb lengthening axis. In order to address this, we designed a caliper to estimate limb lengthening during THA and evaluated its accuracy compared with our previous device, the straight caliper. Limb lengths were measured in 100 patients. The L-shaped caliper was used in 50 cases and the straight caliper in 50. The correlation between intra-operative and post-operative radiographic measurements was significantly improved using the L-shaped device (p < 0.0001, r = 0.934). This method was extremely accurate in predicting changes in limb length due to surgery.