Outcomes of Patellar Subchondroplasty Surgery: A Case Series

Abstract

A select subset of patients can present with anterior knee pain in the setting of normal patellar tracking, no significant cartilage damage, and the presence of a bone marrow lesion (BML) involving the patella on advanced imaging. One novel treatment option for this condition is patellar subchondroplasty, where calcium phosphate is injected into the subchondral bone under fluoroscopic guidance. The purpose of this study is to report preliminary outcomes of patients who have undergone subchondroplasty of the patella. The surgical log of the senior author was retrospectively reviewed to identify patients who had undergone patellar subchondroplasty from January 2014 to June 2019. Indications for surgery included the presence of retropatellar pain refractory to conservative management without significant arthritis with a related focal BML on magnetic resonance imaging. International Knee Documentation Committee, Knee Injury and Osteoarthritis Outcome Score (KOOS), and Veterans Rand 12-item Health Survey (VR-12) were obtained preoperatively, at 6 months and at final follow-up. Eight patients (nine knees) who underwent patellar subchondroplasty with minimum 1-year follow-up participated in the study. On preoperative magnetic resonance imaging, patients had a mean BML that was 2 cm in diameter. Patients had a median Kellgren–Lawrence grade of 2 both preoperatively and at final radiographic follow-up (15.50 ± 20.52 months). No patient underwent subsequent surgery or conversion to arthroplasty. Compared with baseline, VR-12 mental (p = 0.046) and physical (p = 0.003), KOOS joint replacement (p = 0.024), KOOS pain (p = 0.033), and KOOS sports (p = 0.034) scores were significantly increased at final follow-up (24.00 ± 13.55 months). In addition, on a scale of 0 to 100, patient-reported satisfaction was 73.88 ± 33.90. This study introduces patellar subchondroplasty as a surgical treatment for patients with symptomatic BMLs of the patella without significant arthritis after failure of conservative management. Our results demonstrated good outcomes and patient satisfaction. In addition, no patients converted to patellofemoral or total knee arthroplasty. This study suggests that patellar subchondroplasty may be a reasonable treatment option in the correct patient population.