Analysis of the Current Indications for Microfracture of Chondral Lesions in the Hip Joint

Abstract

Background: Data on the efficacy of microfracture for treatment of chondral defects in the hip are currently limited, and the recommended criteria for its use (minimal osteoarthritis; a focal, contained lesion <4 cm2 in size) have been taken from those that were established for the knee. Purpose: To determine if the current microfracture (ie, knee) criteria are appropriate for chondral lesions in the hip. Study Design: Case series; Level of evidence, 4. Methods: Seventy patients who had hip arthroscopy and 2 years of follow-up after treatment of labral tears and cam and pincer bony deformities, as well as microfracture of full-thickness chondral defects, are the basis of this study. The size and location of the chondral defects were recorded on each patient’s “hip sheet” and operative note at the time of hip arthroscopy and were confirmed from intraoperative photographs. The chondral defects were debrided and microfractured regardless of their size. All hips were assessed with the 100-point modified Harris Hip Score (mHHS) before arthroscopy and at 3, 6, 12, and 24 months after surgery. Patients who had a total hip arthroplasty or repeat arthroscopy during their 2-year follow-up period were assigned poor results. Results: The average age of the 70 patients was 41 years, and the average size of the lesions microfractured was 143 mm2. Outcomes, based on patients’ 2-year mHHS or being assigned a poor result for revision surgery, were as follows: 32 excellent, 11 good, 6 fair, and 21 poor; overall, 43 patients (61%) had good and excellent results, and 27 (39%) had fair and poor results. The revision surgery rate was 24%. Seven of the 70 patients had chondral lesions greater than the recommended size for microfracture in the hip (>400 mm) and ranged from 430 to 750 mm2. Their 2-year outcomes included 3 excellent, 1 good, 1 fair, and 1 poor result; the outcomes were the same as for the 8 patients with medium (200-400 mm2) and the 55 patients with smaller (<200 mm2) lesions ( P = .25). There also was no difference in the 2-year outcomes of the older patients (age ≥50 years; P = .91). Conclusion: Microfracture in the hip should not be limited to the criteria of knee lesions (<400 mm2) or to younger patients (age <50 years). However, the results also indicate that patients with full-thickness cartilage defects can anticipate a high rate of conversion to total hip arthroplasty within 2 years of their microfracture surgery and that only 60% of them will have good/excellent results over that time period.