Radiographic Progression of Osteoarthritis after Rotational Acetabular Osteotomy: Minimum 10-Year Follow-up Outcome According to the Tönnis Grade

BACKGROUND: Although satisfactory mid- to long-term results of rotational acetabular osteotomy for early osteoarthritis secondary to acetabular dysplasia have been reported, there is still controversy about the long-term effects of this surgery in more advanced osteoarthritis. The purpose of this study was to investigate the radiographic progression of osteoarthritic changes after rotational acetabular osteotomy in acetabular dysplasia according to the preoperative Tönnis grade and evaluate its effects after minimum 10-year follow-up. METHODS: We performed 71 consecutive rotational acetabular osteotomies in 64 patients with symptomatic acetabular dysplasia between November 1984 and April 2005. Of these, 46 hips (four hips with Tönnis grade 0, 30 with grade 1, and 12 with grade 2) whose clinical and radiographic findings were available after minimum 10-year follow-up were evaluated in this study. The mean age at the time of surgery was 39.0 years (range, 18 to 62 years) and the average follow-up duration was 17.3 years (range, 10.0 to 27.7 years). Clinical and radiographic evaluations were performed according to the preoperative Tönnis grade. RESULTS: The average Harris hip score improved from 71.8 (range, 58 to 89) to 85.1 (range, 62 to 98). The radiographic parameters also improved in all Tönnis grades after the index surgery. Although the improvement of radiographic parameters was not different between preoperative Tönnis grades, the incidence of osteoarthritic progression was significantly different between grades (zero in Tönnis grade 0, four in Tönnis grade 1, and 10 in Tönnis grade 2; p < 0.001). The mean age at the time of surgery was also significantly older in osteoarthritic progression patients (p < 0.002). Kaplan-Meier survivorship analysis, with radiographic progression of osteoarthritis as the endpoint, predicted a 10-year survival rate of 100% in Tönnis grade 0, 85.7% in Tönnis grade 1, and 14.3% in Tönnis grade 2 (p < 0.001). CONCLUSIONS: The outcome of rotational acetabular osteotomy in most hips with Tönnis grade 0 and 1 was satisfactory after an average of 17 years of follow-up. The incidence of osteoarthritic progression was higher in Tönnis grade 2 and older age. Our results support that early joint preserving procedure is essential in the case of symptomatic dysplastic hips.

Pelvic Osteotomy in Adults / 대한정형외과학회잡지

Pelvic osteotomy is a surgery for correcting acetabular deformity, which causes incomplete coverage of the femoral head or biomechanically abnormal load to the hip joint. Pelvic osteotomy can be divided into two categories: reconstructive or realignment osteotomy and salvage osteotomy. Reconstructive osteotomy can be performed to correct the dysplastic hip with good congruency, and include most pelvic osteotomies, except Chiari osteotomy. Among these, Bernese osteotomy, rotational acetabular osteotomy, and periacetabular rotational osteotomy are commonly being used. Salvage osteotomy, which include Chiari osteotomy only, can be performed to increase the coverage of the femoral head of hip joint with joint incongruency due to the severely deformed femoral head and acetabulum or advanced osteoarthritis. Chiari osteotomy is a kind of arthroplasty reducing the pressure applied to the head, and increasing the bone coverage on the upper part of the femoral head. It is effective in reducing hip pain and slowing degenerative changes; however, as the surface is covered by fibrous cartilage, it is vulnerable to degenerative changes. The pelvic osteotomy is a very important and useful surgical technique to preserve joints, despite being a difficult procedure that is technically demanding.

Modified rotational acetabular osteotomy for the treatment of adult acetabular dysplasia / 中国矫形外科杂志

[Objective]To investigate the method and efficiency of operative modified rotational acetabular osteotomy for treatment of adult acetabular dysplasia. [Methods]Twenty-seven patients with 30 hips with acetabular dysplasia were treated with modified rotational acetabular osteotomy. The study group consisted of three men with 3 hips and twenty-four women with 27 hips,the average age of the patients was 29.4 years(range,fifteen to forty-two years ).The anteroposterior plevis view,lateral and abduction view of bilateral hip were taken,CE angle(center-edge angle) and AC angle(acetabular roof obliquity) were measured,the changes of the rotational center of the hip ,Shenton's line and the degree of osteoarthritis were recorded ,the Harris score was obtained before and after operation.[Results]The femoral head coverage was improved in all patients. On average ,the CE angle was improved from 3.2 (-15?～15?)to 28.5?(20?～40?),the AC angle was declined from 26.6?(15?～38?)to 3.9?(0?～12?). The rotational center of the hip was medialized in 19 hips(63.3%),the discontinuity rate of Shenton's line was declined from 67% to 23%. On average 4.2 years follow-up ,1 case lost follow-up,the degree of osteoarthritis in 28 hips was not aggravated,pain was aggravated in 1 hip ,the Harris score was improved from 82.7(67～96) to 97.8(87～100).Two patients have had Fibre-union of pubic and one patient has had stress fracture of the inferior pubic ramus postoperatively,non-union of iliac and posterior column of the osteotomy or the greater trochanter was not found.[Conclusion]The method of modified rotational acetabular osteotomy for treatment of adult acetabular dysplasia is effective and safety.

Rotational Acetabular Osteotomy for the Dysplastic Hip: A Follow-up for 5 to 18 years / 대한정형외과학회잡지

PURPOSE: To evaluate the midterm result of patients who underwent rotational acetabular osteotomy for the treatment of acetabular dysplasia. MATERIALS AND METHODS: The clinical and radiographic outcomes of 36 patients, who underwent rotational acetabular osteotomy between January 1987 and September 1998, were evaluated after a minimum followup of five years. The mean follow-up period was 8.6 years. The clinical evaluation included recording the level of pain, the ambulation status and range of motion according to the d'Aubigne and Postel system. Radiographic analysis included the C-E angle of Wiberg, the acetabular roof obliquity, and arthritis grade of Tonnis. RESULTS: The average Postel score increased from 12.5 points preoperatively to 15.7 points at the final follow up. All the radiologic indices improved after surgery. In five hips (13.1%), there was a progression of arthritis prior to surgery. CONCLUSION: Rotational acetabular osteotomy is a valuable procedure for preventing the progression of early osteoarthritis in patients with a dysplastic hip. However the results were unsatisfactory for hips with more advanced osteoarthritis.

Stress Distribution According to Center-Edge Angle in Dysplastic Hip and the Biomechanical Effect of Rotational Acetabular Osteotomy / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to estimate the biomechanical effect of rotational acetabular osteotomy by analyzing the stress on the surface of the femoral head according to center-edge (CE) angle by computer simulation. MATERIALS AND METHODS: We performed computer simulation by simplifying the pelvis and femur to 3-dimensional flat stress. We analyzed the change of distribution of stress and the amount of deformation according to the degree of acetabular dysplasia, represented by the change of CE angle, by using a Finite element model (FEM). Stress and deformation were calculated in two cases that underwent rotational acetabular osteotomy. RESULTS: In the FEM model, the stress was 3.74 MPa at a CE angle of 30.and the deformation was 1.37 mm. The stress was 14 MPa at 15., 34.2 MPa at 0., and 82.4 MPa at -15. In a case of rotational acetabular osteotomy, the pre-operative and post-operative stresses were 26.1 MPa and 5.16 MPa, and the maximal deformations were 16.1 mm and 1.6 mm, respectively. CONCLUSION: As the severity of acetabular dysplasia increases, the stress concentration also increases. When the CE angle is below 0., a high concentration of stress develops. After rotational acetabular osteotomy, maximal stress was reduced to normal levels and sufficient stress distribution was achieved.

Rotational Acetabular Osteotomy for the Dysplastic Acetabulum / 대한정형외과학회잡지

For the management of adult dysplastic hips with early degenerative arthritis, we can prevent further progress of secondary degenerative changes of the hip by a Rotational Acetabular Osteotomy, which effectively corrects the preoperatively inadequate acetabular coverage of the femoral head. Biomechanical advantages of this procedure are, l. An adequate coverage of tl; femoral head then enlarges the actual weight-bearing surface area, and so diminishes the resultant force per unit area of the acetabular weight-bearing surface and femoral head. 2. The resultant forces are also diminished by a medial shift of the femoral head. 3. The shearing force is decreased by the reduction of roof obliquity. 4. Because of the rotation of the original articular surface, remodeling the post-operative acetabular articular surface as Chiari operation is not necessary, and so can be performed even on elderly patients.