We performed a total of 741 PAOs in 712 patients for symptomatic acetabular dysplasia from October 1, 1997, to May 15, 2008. We reviewed the clinical records from these patients to identify all hips that had a previous reconstructive hip procedure before the index PAO. Of these 712 patients, we identified 74 patients (78 hips) who underwent a previous reconstructive hip surgery (shelf procedure, pelvic osteotomy, PFO, or combination thereof). Eleven patients (11 hips) with less than 2-year followup were not available for evaluation and could not be located despite extensive efforts. The average followup of these 11 patients was 13 months (range, 0–22 months). Two of these 11 patients never returned after their procedure; nine returned and none of these had failed treatment or had a complication at the time of last followup. Excluding these 11 patients, the remaining 63 patients (85%) (67 hips) had a minimum of 2 years of clinical and radiographic followup. One patient did not have a preoperative HHS, but this patient was included in the analysis. Four patients had staged bilateral PAO procedures. Twenty-nine procedures were performed at hospitals affiliated with Washington University School of Medicine (JCC, PLS), while 38 of these procedures were performed at Children’s Hospital Boston (YJK, MBM). There were 52 female patients and 11 male patients, and the average age at the time of surgery was 19.2 years (range, 10–40 years). The average BMI was 23 (range, 15–35). The minimum followup was 24 months (average, 59 months; range, 24–147 months). The review of the data included in this study was approved by the institutional review board at each institution (Washington University School of Medicine and Children’s Hospital Boston).
The preoperative diagnoses in the 67 cases performed included isolated hip dysplasia in 49 hips, while the remainder of cases involved hip dysplasia in addition to one of the following diagnoses: Charcot-Marie-Tooth disease (three hips), peripheral arthrogryposis (one hip), proximal femoral focal deficiency (one hip), multiple epiphyseal dysplasia (one hip), femoral growth arrest (one hip), and Legg-Calvé-Perthes disease (10 hips). One patient had femoroacetabular impingement secondary to a retroverted acetabulum after a previous PAO (Fig. ).
Fig. 1A–C (A) An AP pelvic radiograph shows the hips of a 31-year-old woman who presented with left hip pain 10 years after PAO. Clinically, she was diagnosed with symptomatic femoroacetabular impingement from acetabular retroversion. (B) She was treated (more ...)
Ninety previous procedures were performed on these 67 hips (Table ). Eighteen hips had a prior pelvic osteotomy to correct for acetabular dysplasia, 21 hips had undergone a varus- or valgus-producing PFO, and 28 hips underwent a combined pelvic and PFO procedure. Three of the 18 prior pelvic-only procedures involved salvage osteotomies (Chiari osteotomy or shelf procedures), and four hips from the combined pelvic/PFO group included a salvage pelvic osteotomy. The reconstructive (nonsalvage) osteotomy procedures performed about the pelvis included Salter (13 hips), Dega (three hips), Pemberton (seven hips), Steele (three hips), and Ganz PAO (four hips) and unspecified osteotomies (10 hips). The time from each patient’s index reconstructive hip procedure to PAO at one of our institutions was not specified in enough cases to be included in this study.
Previous surgical procedures
We performed a thorough history of ongoing symptoms and previous surgical procedures and examination of hip ROM in all patients. We also performed a radiographic analysis of AP pelvis and false-profile radiographs. Patients were considered candidates for PAO surgery if they had hip pain, radiographic evidence of acetabular dysplasia or retroversion, acetabular deformity that was correctible through the use of a PAO, Tönnis Grade 0 or 1 osteoarthritis (OA) [29
], and adequate hip motion (hip flexion of at least 90°). Patients were not considered good surgical candidates if they had advanced Tönnis OA (Grade 3 and 4), if their previous reconstructive hip surgery resulted in a severely incongruent joint, or if they had poor hip motion. Mild preoperative joint incongruity was accepted in this more complex patient population.
We used a modified anterior [22
] or Smith-Peterson [13
] approach to perform the acetabular osteotomy procedure as previously described by Ganz et al. [6
]. Modifications in the surgical incision and approach were made on a case-by-case basis in hips that had undergone a previous pelvic osteotomy surgery when necessary. Previous hardware was removed if it would interfere with the osteotomy cuts or fixation of the osteotomy fragment. In no cases with previous pelvic osteotomy surgery was a separate surgical dissection performed to release or explore the sciatic nerve before PAO. A Cell Saver®
device (Haemonetics, Braintree, MA, USA) was used for blood collection and reinfusion, and EMG peripheral nerve monitoring in the operative extremity was also utilized in all procedures at one of the institutions. We used intraoperative AP and false-profile views with fluoroscopic image intensification to monitor the osteotomy cuts, the reduction and correction of the osteotomy fragment, and screw fixation of the osteotomy fragment. Three, four, or five 4.5-mm cortical screws were used to fix the acetabular fragment. The goal for deformity correction was to improve femoral head coverage and to medialize the hip to help reduce the joint reaction force. When possible, we corrected the lateral center-edge angle (LCEA) and anterior center-edge angle (ACEA) to greater than 20° and the Tönnis angle to less than 10°, and we medialized the hip such that the most medial aspect of the femoral head was 5 to 10 mm lateral to the ilioischial line. In some hips with more severe deformity, this extent of correction was limited by the ability to obtain stable osteotomy fragment fixation because of deformity from previous surgery or because correction of the deformity would lead to an unacceptable limitation in postoperative ROM (< 90° hip flexion). In these hips, a balance was accomplished that allowed adequate hip motion at the expense of complete correction of the radiographic parameters described above. In cases of severe acetabular retroversion, the anterior margin of the pubic ramus osteotomy was resected with a high-speed burr to facilitate correction and avoid binding on the remnant medial pubic osteotomy segment if necessary. On completion of acetabular fragment fixation, an anterior arthrotomy was variably performed (32 of 67 hips, 48%), and the ROM of each hip was assessed in all cases for impingement or residual deformity that limited postcorrection motion. We made an intraoperative decision based on this assessment to perform additional reconstructive procedures if necessary. A total of 42 hips (63%) had PAO only, while 25 hips (37%) had an additional procedure performed to reduce hip impingement or improved residual deformity. Thirteen hips had an osteoplasty at the anterior head-neck junction for impingement. Five hips had a varus- or valgus-producing PFO performed to correct residual proximal femoral deformity, and three hips had a surgical hip dislocation procedure combined with advancement of the greater trochanter to functionally lengthen the femoral neck and improve hip offset. A total of four hips had both PFO and surgical hip dislocation with head-neck junction osteoplasty, labral repair, and trochanteric advancement to correct residual deformity. Two of the patients who underwent both PAO and PFO also had an adductor tenotomy to address an adductor contracture. In all these cases, the PAO was performed first, followed by the subsequent procedure on the femoral side of the joint if necessary. In cases with severe femoral deformity in which the deformity will not allow for the PAO correction to be performed, an initial femoral procedure to reduce this deformity may be necessary, but this situation did not occur in this series of cases.
An epidural catheter was used in most patients for 24 to 48 hours postoperatively for pain control, and patients were encouraged to ambulate with the assistance of crutches or a walker under the supervision of a physical therapist on Postoperative Day 2. Weightbearing was limited to 50% body weight in most cases for 4 weeks. Once independence with ambulation and adequate pain control were achieved, patients were discharged from the hospital with instructions to participate in a physical therapy routine until their gait normalized or plateaued.
Patients returned to their surgeon’s outpatient clinic at a minimum routine interval of 2 weeks, 6 weeks, 3 months, 6 months, and annually thereafter. We assessed hip function using the HHS [15
]. Patients were assessed preoperatively and at subsequent postoperative followup clinic visits. One patient (two hips) in the cohort did not have a preoperative HHS, and this patient’s postoperative score was excluded from the analysis. We defined clinical failure as a patient having persistent hip pain and progression of hip arthrosis requiring conversion to a THA. These patients (n = 5) were analyzed separately, and their hip scores and radiographic analysis were excluded from the remainder of the cohort. The average followup for the remainder of the patients was 60 months (range, 24–147 months). We noted the need for and type of subsequent surgical procedures and recorded the presence of complications using a version of the Clavien-Dindo complication classification system for general surgery [4
] that was modified for hip preservation procedures [26
]. In this scheme, complications are graded from 1 to 5 in severity, with each grade based on the long-term morbidity of the complication and the treatment necessary to manage the complication. A Grade 1 complication needs no change in postoperative care, Grade 2 requires modification in outpatient care, Grade 3 involves an invasive surgical or radiographic intervention, Grade 4 includes potential life-threatening complications or those with high long-term morbidity, and a Grade 5 complication involves death.
Two orthopaedic joint reconstruction/hip preservation fellows (GGP, ENN) performed an unblinded radiographic analysis of preoperative and postoperative radiographic images for procedures performed at Washington University School of Medicine and Children’s Hospital Boston, respectively. From AP and false-profile radiographs obtained at each clinic visit, the following measurements were performed: LCEA [2
], ACEA [14
], Tönnis angle [29
], medialization of hip center in millimeters, and Tönnis OA grade [29
]. These measurements are widely accepted as reliable ways to quantify the extent of hip deformity and are useful to calculate the extent of correction [19
]. Preoperative and postoperative values at most recent followup for these measurements were compared to quantify the extent of deformity correction and to assess for the progression to OA. The presence of bridging bone across the osteotomy sites was used to determine radiographic evidence of osteotomy healing. One patient (one hip) did not have preoperative radiographs available for review, and her data were excluded from the analysis.
We used a paired Student’s t-test to compare preoperative and followup radiographic measurements and clinical hip scores (Microsoft Corp, Redmond, WA, USA).