Responsiveness of the SF-36 and WOMAC Following Periacetabular Osteotomy for Acetabular Dysplasia

The Adolescent and Young Adult Hip Unit, Department of Orthopaedic Surgery, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115, USA.
The Journal of Bone and Joint Surgery (Impact Factor: 5.28). 12/2011; 93(23):2214-8. DOI: 10.2106/JBJS.J.00687
Source: PubMed


Periacetabular osteotomy is a relatively common reconstructive procedure for the adolescent or young adult with acetabular dysplasia. Although several measures have been used to characterize the outcome, the responsiveness of these measures in this population has not been determined. The purpose of this study was to estimate the responsiveness of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Short Form-36 (SF-36) in patients with acetabular dysplasia treated with periacetabular osteotomy.
Eighty-three patients with acetabular dysplasia treated with periacetabular osteotomy between 2000 and 2005 completed the WOMAC and SF-36 both preoperatively and postoperatively. The scores on each domain of these outcome measures were calculated and analyzed to determine the parameters of responsiveness, including the minimal detectable change at the 90% confidence level.
The mean duration of follow-up was 1.9 years. Comparison of the effect size, standardized response mean, and minimal detectable change for the SF-36 and WOMAC demonstrated that the WOMAC was more sensitive to change than the SF-36 was, particularly in the physical function domain (minimal detectable change, 9.1) and the pain domain (minimal detectable change, 5.5). Only one of the eight domains of the SF-36, bodily pain, demonstrated a change in outcome that exceeded the minimal detectable change, which was 2.38.
Both the WOMAC and the SF-36 demonstrated adequate responsiveness to change over time in patients with acetabular dysplasia treated with periacetabular osteotomy, although the WOMAC was more sensitive to change. These results indicate that the WOMAC is sufficiently responsive to be used as a joint-specific measure for assessing changes following periacetabular osteotomy for the treatment of acetabular dysplasia.

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    ABSTRACT: Background As the Bernese periacetabular osteotomy (PAO) has grown in popularity, specific indications and the results in patients treated for those indications need to be evaluated. Currently, although many patients undergo PAO after having had prior pelvic osteotomy, there is limited information regarding the efficacy of the PAO in these patients. Questions/purposes The purpose of this study was to compare the (1) early pain, function, activity, and quality of life outcomes; (2) radiographic correction; and (3) major complications and failures between patients who underwent PAO after prior pelvic reconstruction versus those who had a PAO without prior surgery. Methods Between February 2008 and January 2012, 39 patients underwent PAO after prior pelvic osteotomy at one of 11 centers and were entered into a collaborative multicenter database. Of those, 34 (87%) were available for followup at a mean of 2.5 years (range 1–5 years). This group was compared with a matched group of 78 subjects, of whom 71 (91%) were available for followup at a similar interval. We compared clinical outcomes including UCLA activity score, SF-12, and Hip Disability and Osteoarthritis Outcome Score (HOOS); radiographic measures—anterior and lateral center-edge angle and acetabular inclination (AI)—and reoperations, major complications, and conversions to total hip arthroplasty. Results Although both groups reached clinical improvement in all categorical measures, the revision PAO group demonstrated greater pain (HOOS pain, study 74 versus 85, p = 0.03; 95% confidence interval [CI], 18.58 to −0.95) and less function (HOOS activities of daily living, study 80 versus 92, p = 0.002; 95% CI, 018.99–4.45) than the primary cohort. The revision cohort achieved a smaller average radiographic correction than in patients undergoing PAO without prior pelvic surgery. The mean correction in AI was less dramatic when directly comparing the revision and comparison groups (−12° to −17°, p < 0.001, SD 2.3–8.5). Although there was no difference in severe complications requiring further surgery, there were two conversions to hip arthroplasty (p = 0.109; 95% CI, 0.004–2.042) in the study group. Conclusions PAO performed after prior pelvic surgery is associated with improvements in pain, function, radiographic correction, and early complication rates, but the improvements observed at short-term followup were smaller and more variable than those seen in patients who had not undergone prior pelvic surgery. We recommend considering PAO for residual deformities after prior osteotomy to improve function and quality life but warning patients of potential ceiling effects with a second periacetabular surgery. Level of Evidence Level III, therapeutic study.
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