We retrospectively reviewed 163 patients (178 hips) who underwent femoral head-neck osteochondroplasty either exclusively or in association with other procedures from October 2004 to December 2006 (Fig. ). The average age of the included patients at the time of surgery was 32.7 years (range, 15–56 years). Minimum clinical followup was 10 months (mean, 22.3 months; range, 10–65 months). Nineteen hips (10.6%) were lost to followup before 1 year. Four hips (2.2%) were converted to a total hip or resurfacing arthroplasty in less than 12 months. Two patients (1.1%) were unable to participate in the study owing to other medical issues. Three hips (1.6%) with major proximal femoral head deformity treated with proximal femoral osteotomies (PFO) and head-neck osteochondroplasty were later excluded from the study as a result of the severity of their deformity. Therefore, we reviewed 135 patients (150 hips) (Table ). One hundred five patients (113 hips) had radiographic and clinical data; 30 additional patients (37 hips) had inadequate radiographic data but full clinical followup. The minimum radiographic followup was 8 months (mean 20 months; range, 8–54 months). We obtained prior Institutional Review Board approval.
Flow diagram demonstrating the included and excluded patients from the initial group of patients reviewed. HRA = hip resurfacing arthroplasty.
All surgery was performed by one surgeon (JCC). Ninety hips with isolated FAI were treated with hip arthroscopy and limited open osteochondroplasty of the femoral head-neck junction for a cam-type lesion. Forty hips had a periacetabular osteotomy (PAO) for symptomatic acetabular dysplasia with an osteochondroplasty to prevent secondary impingement [12
]. Seventeen hips underwent surgical hip dislocation to address combined cam and pincer-type deformity, major pincer abnormalities, or severe femoral head deformities. Three additional hips with acetabular dysplasia and severe proximal femoral deformities underwent PAO as well a PFO with reshaping of the femoral head-neck junction. We performed hip arthroscopy using standard anterior, anterolateral, and posterolateral portals [5
]. After diagnostic arthroscopy and débridement of the labrum as necessary, limited anterior arthrotomy and osteochondroplasty were performed through a standard anterior approach to the hip. We performed periacetabular osteotomies as described by Ganz et al. [8
]. After the osteotomy, anterior arthrotomy and recontouring of the femoral head-neck junction was carried out to reduce the risk of secondary impingement. Surgical hip dislocations were performed as described by Ganz et al. [17
]. After the capsule was opened, the hip was dislocated and examined and the femoral head-neck offset restored. For all procedures, labral tears were débrided and repaired or resected as necessary. Forty-eight patients had acetabular cartilage defects for which we performed chondroplasty. Five patients had microfracture of their acetabular cartilage defect. Twelve patients had additional acetabular rim trimming. Intraoperative examination of the range of motion was performed routinely to ensure adequate impingement-free range of motion.
Postoperative rehabilitation required patients to be toe-touch weightbearing for a 6-week period. During that time, physical therapy focused on gentle range of motion and isometric exercises. After the 6-week period, patients progressed to weightbearing as tolerated with increasing stretching and strengthening. Patients were allowed to return to full sports activity at 4 months as tolerated.
Radiographic data were available for 105 patients (113 hips). The osteochondroplasty site was analyzed on the frog lateral radiographs. Ninety-two patients (100 hips) had preoperative frog lateral radiographs. One hundred five hips had postoperative radiographs and 109 hips followup radiographs. Postoperative films were obtained on the first followup visit rather than immediately after the procedure. All radiographic variables were measured serially by one observer (NAN) according to our previously published techniques [10
]. All measurements were performed using the EVMS Advanced Visualization Software, which has a measurement precision to the one-hundredth decimal place (Emageon Inc, Birmingham, AL).
The head-neck offset (HNO) was measured based on the method previously described by Eijer et al. [14
] on the frog leg lateral radiograph (Fig. ). Initially, a line was drawn so it was parallel and bisected the femoral neck irrespective of its location on the femoral head. A second line parallel to the first was drawn tangential to the anterolateral neck on the frog leg view. A third line, parallel to the first and second lines, was drawn tangential to the femoral head. The HNO was determined by measuring the perpendicular distance between the second and third lines. Postoperatively, as a result of the reshaping of the head-neck junction, the second line was drawn tangential to the proximal portion of the femoral neck; the third line was drawn tangential to the most anterolateral aspect of the femoral head as indicated by a circle template to ensure the measurement was consistent with the preoperative femoral head shape. A normal HNO is greater than 9 mm [14
]. The HNO in the preoperative and followup radiographs was normalized to the femoral head diameter in postoperative films, which allows for more direct comparisons between HNO between time points. The head-neck offset ratio (HNOR) was also calculated to account for error introduced by magnification differences across time points. The HNO was divided by the head diameter measured at every time point (preoperatively, immediately postoperatively, and at latest followup). The HNO measurement reportedly has a high intraobserver and a moderate interobserver reliability [13
Fig. 2A–B (A) The head-neck offset (HNO) was measured in a preoperative measurement on a frog leg lateral view. Line 1 is drawn to bisect the femoral neck. Parallel lines are draw tangential to the femoral neck (Line 2) and the femoral neck (Line 3). The HNO is (more ...)
We measured the alpha angle as previously described by Notzli et al. [31
] at every time point (Fig. ). A line was drawn through the longitudinal axis of the femoral neck. A circular template was drawn to match the diameter of the femoral head. A line was drawn from the center of the head through the point where the femoral head deviates from the circular template. After the osteochondroplasty, the alpha angle was determined by the point where the femoral head intersected the circular template. Ideally, this fell at the intersection of the resected area and femoral neck. The alpha angle in normal hips is approximately 42°. Measurement of the alpha angle reportedly has high inter- and intraobserver reliability [13
Fig. 3A–B (A) The alpha angle is measured by applying a circular template to match the diameter of the femur. A line is drawn along the longitudinal axis of the femoral neck. A second line is drawn from the center of the circular template to the point where the (more ...)
The degree of recorticalization at the osteochondroplasty site was also evaluated (Fig. ). If no evidence of recorticalization was present when comparing immediate postoperative films and the latest followup films, it was graded as “none.” If evidence of sclerosis of the bone margin was observed but was incomplete, it was graded as “partial.” If there was a continuous cortical line between the femoral head and head-neck junction, the sample was graded as “complete.” The degree of heterotopic ossification was determined as described by Brooker et al. [4
Fig. 4A–C The recorticalization of the femoral head-neck junction was assessed by comparing postoperative and followup films. They were labeled (A) “none” if no sclerotic margin was noted at the resection site and (B) “partial” if (more ...)
Patients were evaluated at 6 weeks for their first postoperative followup, then at 12-week, 6-month, 1-year, and 2-year intervals. We obtained Harris hip scores [21
] preoperatively and at annual followups. All patients included had a preoperative Harris hip score and all had an annual followup hip score. Patients who developed surgical site infections, fractures, avascular necrosis, or any repeat surgery were noted.
Longitudinal analyses for HNO, HNOR, and alpha angle that were measured at more than two time points were carried out using mixed model repeated measures analyses of variance with available data from each participant. As a result of heterogeneity of variance and lack of normality, data were rank-transformed before analysis. The Kruskal-Wallis test was used to compare the three recorticalization groups. A paired t-test was used to compare Harris hip preoperative scores with followup scores. A Spearman correlation was performed between recorticalization and Harris hip score as well as alpha angle and Harris hip score. The data analysis was generated using SAS software (Version 9.1.3, SAS Institute Inc, Cary, NC).