Summary

An “inside-out” method of arthroscopic bone grafting for acetabular subchondral cysts represents a safe treatment option which produces effective early- to mid-term outcomes when utilized during hip arthroscopy in appropriately selected patients.

Abstract

Background

Acetabular subchondral cysts are commonly identified signs of joint degeneration and early arthritis and are a contraindication to hip preservation surgery for many surgeons. Outcomes in the treatment of acetabular cysts have been rarely characterized. The purpose of this study was to investigate whether arthroscopic bone grafting of acetabular subchondral cysts during hip arthroscopy is a safe and efficacious treatment option.

Methods

A prospective database was used to collect initial data, including presence of acetabular subchondral cysts, reoperation rate, complications, and return to play time on patients with femoroacetabular impingement (FAI) and/or hip dysplasia who underwent hip arthroscopy by the senior author between May 2013 and March 2021. Patients were included if they underwent arthroscopic grafting of acetabular cysts. An “inside-out” technique of arthroscopic bone grafting was utilized, in which a curved delivery device allowed for deeper and more precise access to the cyst cavity through the articular side for delivery of bone graft material after the cyst was decompressed. Patients with follow-up less than 1 year were excluded. The primary outcome measures were the International Hip Outcome Tool (iHOT)-12 score and the Non-Arthritic Hip Score (NAHS) at follow-up. Secondary outcomes included follow-up magnetic resonance imaging (MRI) findings of percent cyst resolution.

Results

In total, 27 patients (27 hips) were included. Preoperative lateral center edge angle (LCEA) averaged 21 degrees (range, -5 to 41 degrees). Fourteen of the 27 hips subsequently underwent periacetabular osteotomy (PAO) following hip arthroscopy for hip dysplasia or excessive acetabular anteversion. iHOT-12 scores improved from 39.3 ± 18.5 preoperatively to 79.9 ± 20.3 at a mean follow-up of 1.93 years (range, 1.0-5.0 years) (p < 0.0001). NAHS scores improved from 60.6 ± 22.9 preoperatively to 86.7 ± 14.7 at latest follow-up (p < 0.0001). MRI on 9 patients showed 80-100% resolution of the cyst at 1-year follow-up. Seventy-five percent of the cysts were in the anterolateral location (1-3 o’clock) while 25% were more lateral in nature (11-2 o’clock).

Conclusion

An “inside-out” method of arthroscopic bone grafting for acetabular subchondral cysts represents a safe treatment option which produces effective early- to mid-term outcomes when utilized during hip arthroscopy in appropriately selected patients.