Outcomes of Multiple Drilling for Osteonecrosis of the Femoral Head: A Retrospective Cohort Study With a Minimum 10-Year Follow-Up.

Abstract

Multiple drilling techniques, a minimally invasive variation of core decompression, have shown promise for joint preservation in early-stage osteonecrosis of the femoral head (ONFH). However, long-term outcomes remain insufficiently reported. This study extends the follow-up period to 30 years, aiming to deliver a thorough evaluation of the sustained effectiveness and potential limitations of multiple drilling in the management of ONFH. This retrospective analysis reviewed the original cohort from previous research, comprising patients who underwent multiple drilling procedures for ONFH. We reviewed 134 hips treated with multiple drilling between 1992 and 1998. All hips were classified by Ficat stage (I to III), Association Research Circulation Osseous classification (types 1 to 3), and necrotic lesion size, categorized as small (< 25%), medium (25 to 50%), or large (> 50%). Treatment failure was defined as the necessity for further surgical interventions or a Harris hip score below 75. Kaplan-Meier survival analysis was used to evaluate long-term outcomes. At an average follow-up of 19.4 years, 70 (52.2%) hips were without additional surgery. Success rates at the final follow-up were 70, 65, and 16% for Ficat stages I, II, and III, respectively; 96, 75, and 11% for Association Research Circulation Osseous types 1, 2, and 3, respectively; and 100, 65, and 42% for small, medium, and large lesions, respectively. Most failures occurred within the first five years. Etiology had no significant effect on outcomes. Heterotopic ossification (14.9%) and one subtrochanteric fracture occurred during the follow-up. The extended follow-up confirms that multiple drilling remains effective for managing ONFH, particularly in smaller lesions, early-stage disease, and cases where the necrotic margin remains confined to the lateral edge of the acetabulum. These results highlight the importance of timely intervention and patient selection. Multiple drilling remains a valuable joint-preserving option, but alternative treatments should be considered for larger lesions and advanced disease stages.