Purpose

To evaluate the clinical and radiologic midterm results of rotational acetabular osteotomy (RAO) in incongruent hip joints.

Background. Rotational acetabular osteotomy (RAO) is an effective treatment option for symptomatic acetabular dysplasia. However, excessive lateral and anterior correction during the periacetabular osteotomy may lead to femoroacetabular impingement. We used preoperative planning software for total hip arthroplasty to perform femoroacetabular impingement simulations before and after rotational acetabular osteotomies. Methods. We evaluated 11 hips in 11 patients with available computed tomography taken before and after RAO. All cases were female and mean age at the time of surgery was 35.9 years. All cases were early stage osteoarthritis without obvious osteophytes or joint space narrowing. Radiographic analysis included the center-edge (CE) angle, Sharp's acetabular angle, the acetabular roof angle, the acetabular head index (AHI), cross-over sign, and posterior wall sign. Acetabular anteversion was measured at every 5 mm slice level in the femoral head using preoperative and postoperative computed tomography. Impingement simulations were performed using the preoperative planning software ZedHip (LEXI, Tokyo, Japan). In brief, we created a three-dimensional model. The range of motion which causes bone-to-bone impingement was evaluated in flexion (flex), abduction (abd), external rotation in flex 0°, and internal rotation in flex 90°. The lesions caused by impingement were evaluated. Results. In the radiographic measurements, the CE angle, Sharp's angle, acetabular roof angle, and AHI all indicated improved postoperative acetabular coverage. The cross-over sign was recognized pre- and postoperatively in each case. Acetabular retroversion appeared in one case before RAO and in three cases after RAO. Preoperatively, there was a tendency to reduce the acetabular anteverison angle in the hips from distal levels to proximal. In contrast, there was no postoperative difference in the acetabular anteversion angle at any level. In our simulation study, bone-to-bone impingement occurred in flex (preoperative/postoperative, 137°/114°), abd (73°/54°), external rotation in flex 0°(34°/43°), and internal rotation in flex 90°(70°/36°). Impingement occurred within internal rotation 45°in flexion 90°in two preoperative and eight postoperative cases. The impingement lesions were anterosuperior of the acetabulum in all cases. Discussion. It is easy to make and assess an impingement simulation using preoperative planning software, and our data suggest the simulation was helpful in a clinical setting, though there were some remaining problems such as approximation of the femoral head center and differences in femur movement between the simulation and reality. In the postoperative simulation there was a tendency to reduce the range of motion in flex, abd, and internal rotation in flex 90°. There was a correlation between acetabular anteversion angle and flex. Since impingement occurred within internal rotation 45°in flexion 90°in eight postoperative simulations, we consider there is a strong potential for an increase in femoroacetabular impingement after RAO

Rotational acetabular osteotomy (RAO) is a circumacetabular osteotomy of the acetabulum designed to correct the dysplastic hip. In this procedure, the femoral head is covered with the articular cartilage of the acetabulum and the forces of weight-bearing are distributed more evenly. The purpose of this study was to determine whether RAO is effective in delaying the onset of arthrosis in patients with painful hip dysplasia. We determined the outcome of 20 female patients in whom RAO was performed between 1975 and 1984; all were aged 20 to 29 years at the time of surgery. The pre-operative centre-edge angle of Wiberg was 0 or negative with proximal subluxation of the femoral head. Of these, 10 were lost to follow-up before the age of 42. In these patients, however, radiographs showed no signs of arthrosis at the last follow-up. The remaining 10 patients were examined 15 to 25 years after surgery, when they were 42 to 47 years old. Radiographs revealed findings of arthrosis in only two of them who had had the secondary acetabulum before surgery. To evaluate the efficacy of preventive medicine, it is necessary to compare the results of intervention with the natural course of the disease. Wiberg reported on the natural history of seven female patients with severe hip dysplasia in 1939. When these patients were 13 to 34 years old, radiographs demonstrated no sign of arthrosis and the centre-edge angle was equal to or less than 12 degrees with proximal subluxation of the femoral head. These hips deteriorated to advanced arthrosis by the age of 42 years. Thus the outcome of our patients was significantly better than the natural course. In conclusion, our study suggests that RAO is effective in delaying the onset of arthrosis in patients with painful hip dysplasia

Rotational acetabular osteotomy (RAO) for developmental dysplasia of the hip (DDH) may not restore normal hip range of motion (ROM) due to the inherent deformity of the hip and it may lead to femoro-acetabular impingement. The purpose of this study was to investigate morphological factors of the pelvis and femur influencing on simulated ROM after RAO with a fixed target for femoral head coverage. We retrospectively reviewed CT images of 52 DDHs with an average lateral centre edge angle (CEA) of 7.9° (−12° to 19°). After virtual RAO with 30° of lateral CEA and 55° of anterior CEA producing femoral head coverage similar to that of the normal hips, we measured simulated flexion ROM using pelvic and femoral computer models reconstructed from the CT images. Pelvic sagittal inclination, acetabular anteversion, lateral CEA, femoral neck anteversion, femoral neck shaft angle (FNSA), alpha angle and the position of the anterior inferior iliac spine (AIIS) were investigated as morphological factor. When the most prominent point of the AIIS existed more distally than the cranial tip of the acetabular joint line in a lateral view of the pelvis model in supine position, the subjects were defined as AIIS-Type1; the remaining subjects were defined as Type 2. There were 10 hips with Type 1 and 42 hips with Type 2 AIIS. The Kappa value of inter-observer reproducibility to classify AIIS was 0.82. Multiple regression analyses were performed to analyse the relationship between ROM and the morphological parameters. We also analysed the relationship between the probability of flexion ROM being less than 110° and the factors which influenced on flexion ROM. FNSA and AIIS-Type independently influenced on simulated flexion ROM after RAO (standard regression coefficient: −0.51 and 0.37, respectively. p< 0.001). The multiple correlation coefficient was 0.68. Flexion ROM after RAO with a fixed femoral head coverage similar to that of the normal hips ranged from 95° to 141° with an average of 121°±8°. The probability of ROM being less than 110° was significantly higher in subjects with AIIS-Type 1 than in those with Type 2 (odds ratio: 13.3, p<0.01). It was also significantly higher in subjects with more than 135° of FNSA than in those with less than 135° of FNSA (odds ratio: 9.5, p<0.05). FNSA and the type of AIIS influenced on flexion ROM after RAO with approximately 40° of variation in spite of a fixed target for femoral head coverage. A large FNSA and a distal positioning of AIIS were independently associated with smaller flexion ROM after RAO

Satisfactory intermediate and long-term results of rotational acetabular osteotomy (RAO) for the treatment of early osteoarthritis secondary to developmental dysplasia of the hip have been reported. The purpose of this study is to examine the 30-year results of RAO.

Between 1987 and 1994, we treated 49 patients (55 hips) with RAO for diagnosis of pre- OA or early-stage OA. Of those patients, 35 patients (43 hips) were available at a minimum of 28 years. The follow-up rate was 78.2% and the mean follow-up was 30.5 years. The mean age at the time of surgery was 34 years. Clinical evaluation was performed with the Merle d'Aubigne and Postel rating scale, and radiographic analyses included measurements of the center-edge angle, acetabular roof angle, and head lateralization index on preoperative, postoperative AP radiographs of the pelvis. Postoperative joint congruency was classified into four grades. The radiographic evidence of progression of OA was defined as the minimum joint space less than 2.5mm.

The mean preoperative clinical score was 14.0, which improved to a mean of 15.3 at the time of the latest follow-up. The mean center-edge angle improved from 0.6° preoperatively to 34° postoperatively, the mean acetabular roof angle improved from 28.4°preoperatively to 1.0°postoperatively, the mean head lateralization index improved from 0.642 preoperatively to 0.59 postoperatively. Postoperative joint congruency was excellent in 11 hips, good in 29 hips, and fair in 3 hips. Nineteen patients (20 hips) had radiographic OA progression, and 10 patients (11 hips) were converted to THA. Kaplan-Meier survivorship analysis, with radiographic OA progression as the end point, predicted survival of 75.6% at 20 years and 48.8% at 30 years, and with THA conversion as the end point, 90.2% at 20 years and 71.2% at 30 years.

The RAO is an effective surgical procedure for symptomatic dysplastic hips of pre- and early-stage OA and could change the natural history of the dysplastic hip.

[Introduction]

Total hip arthroplasty (THA) markedly improves pain, gait, and activities of daily living for most patients with osteoarthritis. However, pelvic osteotomy has been recommended for young and active patients with hip dysplasia, because THA in that population is associated with high rates of revision THA. The rotational acetabular osteotomy (RAO) of Ninomiya and Tagawa, and the eccentric rotational acetabular osteotomy of Hasegawa for hip dysplasia reportedly are successful in young and active patients. However, even after the surgery of RAO, osteoarthritis developed in some cases and leaded to the conversion to THA. The differences of bone quality of acetabulum have been reported between at the surgery of THA after RAO and at the surgery of primary THA. We should not discuss the results of these two THA equally. The purpose of this study is to report the results of THA after RAO.

Objective

To investigate the biomechanical basis and report preliminary clinical efficacy of eccentric rotational acetabular osteotomy (ERAO) when treating developmental dysplasia of the hip (DDH).

Background

The rotational acetabular osteotomy (RAO), that was developed in Japan, has been used successfully in patients with developmental dysplasia of the hip (DDH) (Figure 1). However there are some patients who are forced to have a total hip arthroplasty (THA) due to the progression of osteoarthritis. It is unknown if a RAO poses technical difficulties or increases the chances of complications if a THA must be performed afterwards becausethere is not much data on patients who underwent a THA after a previous RAO.

Objective

To investigate the biomechanical mechanism and report preliminary clinical efficacy of eccentric rotational acetabular osteotomy (ERAO) when conduct treatment for developmental dysplasia of the hip (DDH).

Adolescent and young adult patients with a history of DDH and residual hip dysplasia tend to have an early presentation of symptoms. In these patients, a severe acetabular dysplasia, aspheric femoral head and/or high greater trochanter are often observed. We evaluated the long-term results of rotational acetabular osteotomy (RAO) for symptomatic hip dysplasia in patients younger than 21 years.

We performed 492 RAOs for hip dysplasia from 1987 to 2017. In these cases, patients younger than 21 years at the time of surgery were 40 patients (46 hips). We evaluated 34 patients (40 hips, follow-up rate; 85%) retrospectively. There were 32 females and two males; their mean age at the time of surgery was 17.8 years (12–21). The mean follow-up period was 16.8 years (1–30). In eight hips, isolated RAO was not adequate to correct instability and/or congruency. For these hips, four varus femoral osteotomies, two valgus femoral osteotomies and two greater trochanter displacement were combined with RAO.

The mean clinical score (JOA) was improved from 80 to 90 significantly at the final follow-up. The mean CE angle was improved from −3.4 (−35–10) degrees to 27 (8–42) degrees, acetabular roof angle from 30 (15–60) degrees to 6.7 (−3–30) degrees, head lateralization index from 0.665 (0.5–1.0) to 0.614 (0.429–0.7) postoperatively. Radiographic OA progression was observed in four hips, but no hip was converted to THA.

The RAO is an effective technique for surgical correction of a relatively severe dysplastic hip in adolescent and young adults.

Background: A retroverted acetabulum has been hypothesized as a cause of osteoarthritis. This study was performed to evaluate whether radiographical cross-over sign influence the painful femoro-acetabular impingement or the radiographical progression of osteoarhritis after rotational acetabular osteotomy (RAO) for dysplastic hip.

Methods: Between 1987 and 1999, 104 patients (115 hips) who had pre- or early stage osteoarthritis of the hip due to dysplasia underwent a RAO. There were 99 women and five men; their mean age at the time of surgery was 34.7 years. The mean follow-up period was 13 years. Clinical follow-up was performed with use of the system of Merle d’Aubigne and the impingement sign was evaluated. Radiographical analyses included measurements of the center-edge angle, acetabular roof angle, head lateralization index, joint congruency, cross-over sign, posterior wall sign, acetabular index of depth to width, pistol grip deformity and femoral head-femoral neck ratio.

Results: The mean clinical score improved significantly from 14.6 preoperatively to 17.0 at follow-up. The impingement sign at the follow-up was observed in 14 hips (12.2%). The center-edge angle improved significantly from mean −0.6 degrees to a postoperative mean of 34 degrees. The acetabular roof angle improved from 30 degrees to 2.2 degrees, and head lateralization index from 0.64 to 0.60. The cross-over sign was observed in 8 hips (7.0%) preoperatively and in 49 hips (42.6%) postoperatively. The posterior wall sign was observed in 70 hips (60.9%) preoperatively and observed in 73 hips (63.5%) postoperatively. The mean preoperative acetabular index of depth to width was 35.5% and the mean preoperative femoral head to femoral neck ratio was 1.49. The pistol grip deformity was observed in only 4 hips (3.5%) preoperatively. The impingement sign after the RAO was positive significantly in the postoperative cross-over sign positive hips (p=0.0074). Radiographical progression of osteoarthritis was observed in 11 hips (cross over sign positive; 7 hips, cross over sign negative; 4 hips). The Kaplan-Meier survivorship analysis predicted a survival rate of 84.6 % at 15 years. The only factors significantly associated with radiographic signs of progression of osteoarthritis after RAO were fair (rather than excellent and good) postoperative joint congruency (p< 0.0001) and age at surgery (p=0.0042). Presence of postoperative cross-over sign had no effect on the outcome (p=0.2073).

Conclusions: Although there was no significant radiographical progression of osteoarthritis despite a significant retroversion in most cases, the goal of RAO should be a correct alignment of the acetabulum including a correct version with a negative cross-over sign.

Aims: To evaluate technical and clinical results of a new 2-incision technique of rotational acetabular osteotomy. Methods: 27 patients, with a mean age of 40 years, were reviewed after a minimum of 1 year subsequently to rotational acetabular osteotomy, which was done through short low midline and iliac approaches. An analysis of complications, the length of rehabilitation period, time to union of the osteotomy, radiographic correction of acetabular roof, proceeding of hip arthrosis, as well as of clinical status at follow-up, using scores by Merle DñAubigne and Harris, was performed. Results: No major operative complications were observed. The median time to union of osteotomy and a painless status was 10 weeks. Femoral head covering by acetabular roof increased signiþcantly, whereas the range of motion of the operated hip was not compromised by the operation. A signiþcant increase in the mean scores, mainly caused by a decrease in pain, were observed in a subgroup of 20 patients with a minimum follow-up of 2 years. The most signiþcant factor predisposing poor outcome was grave preoperative arthrosis of the hip. Conclusions: This new technique of osteotomy is safe and less traumatic than previous methods, allowing early weight bearing and a fast recovery. The early clinical results are satisfactory

BACKGROUND

Our modified procedure for rotational acetabular osteotomy (RAO) aimed to reduce operative invasion of soft tissue and to minimize incision length.

Introduction. Dysplasia of the hip is the commonest cause of secondary osteoarthritis. One treatment is periacetabular osteotomy such as rotational acetabular osteotomy(RAO). These procedures have generally produced satisfactory mid- and long-term results, but unfavorable results have been reported in a few cases. We evaluated the 10-year results to determine the factors of prognostic importance.

Methods. We studied 91 patients (100 hips) at prearthritis or early stage. The mean age at surgery was 36 years (13 – 58) and mean follow-up period was 11 years (8–16). 81 were women (89 hips) and 10 were men (11 hips). Clinical follow-up was done using the system of Merle d’Aubigne. Radiologically, CE angle, AC angle and head lateralization index (HLI) were measured prior to surgery, 3 months postoperatively and at follow-up. Postoperative joint congruencies were classified into four grades.

Results. The mean clinical score significantly increased from 14 to 17 and only in 4 cases the mean score decreased. CE angle, AC angle, and HLI significantly improved after surgery. Progression of osteoarthritis was radiologically observed at follow-up in 7 hips. Kaplan-Meier survivorship analysis predicted the rate of prevention of osteoarthritic progression at 10 years as 93%. Parametric survivorship analysis using the Cox hazards model indicated that postoperative joint congruency is a risk factor for progression of osteoarthritis.

Discussion/Conclusion. Our findings have suggested that RAO is valuable in preventing osteoarthritic progression for at least 10 years. If risk factors can be reduced, a longer operative effect may be expected.

Rotational acetabular osteotomy (RAO), one of periacetabular osteotomies, is an effective joint-preserving surgical treatment for developmental dysplasia of the hip. Since 2013, we have been using a CT-based navigation for RAO to perform safe and accurate osteotomy. CT-based navigation allows precise osteotomy during surgery but cannot track the bony fragment after osteotomy. Thus, it is an issue to achieve successful reorientation in accordance with preoperative planning. In this presentation, we introduce a new method to achieve reorientation and evaluate its accuracy. Thirty joints in which CT-based navigated RAO was performed were included in this study. For the first 20 joints, reorientation was confirmed by tracing the lateral aspect of rotated fragment with navigation and checked if it matched with the preoperative planning. For the latter 10 joints, a new method was adopted. Four fiducial points were made on lateral side of the acetabulum in the preoperative 3-dimensional model and intraoperatively, rotation of the osteotomized bone was performed so that the 4 fiducial points match the preoperative plan. To assess the accuracy of position of rotated fragment in each group, preoperative planning and postoperative CT were compared. A total of 24 radial reformat images of postoperative CT were obtained at a half-hour interval following the clockface system around the acetabulum. In every radial image, femoral head coverage of actual postop- and planned were measured to evaluate the accuracy of acetabular fragment repositioning. The 4-fiducial method significantly reduced the reorientation error. Especially in the 12:00 to 1:00 position of the acetabulum, there were significantly fewer errors (p<0.01) and fewer cases with under-correction of the lateral acetabular coverage. With the new method with 4 reference fiducials, reorientation of the acetabulum could be obtained as planned with lesser errors

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