Efficacy and recurrence of arthroscopic synovectomy plus postoperative low-dose radiotherapy (30-36 Gy) for knee diffuse-type tenosynovial giant cell tumor

Context Diffuse-type tenosynovial giant cell tumor (D-TGCT) of the knee is a rare, benign but locally aggressive synovial neoplasm for which complete surgical synovectomy is the mainstay of treatment, though postoperative recurrence rates remain high. This study aimed to evaluate the efficacy and recurrence rate of arthroscopic synovectomy combined with postoperative low-dose radiotherapy (LD-RT) for knee D-TGCT. Method A retrospective analysis was conducted on 98 patients who underwent arthroscopic synovectomy for knee D-TGCT between January 2020 and August 2023. Based on treatment regimen, patients were divided into a surgery-only group (n = 53) and a combined radiotherapy group (n = 45; receiving postoperative LD-RT of 30-36 Gy). Pain visual analogue scale (VAS) scores, Lysholm knee scale scores, International Knee Documentation Committee (IKDC) scores, and knee range of motion (ROM) were assessed preoperatively and at 3, 6, and 12 months postoperatively. Patients were followed for at least 2 years, with MRI every 6 months to detect recurrence. Result Among the 98 patients, 53 underwent surgery alone and 45 received additional LD-RT. Both groups showed significant improvement in VAS, Lysholm, IKDC, and ROM over time, with no significant intergroup differences at any follow-up (all P > 0.05). The recurrence rate was significantly lower in the combined radiotherapy group (2/45, 4.44%) than in the surgery-only group (10/53, 18.87%) ( P = 0.030). Local skin pigmentation occurred only in the radiotherapy group (6/45, 13.33%) ( P = 0.020). Summary For knee D-TGCT, arthroscopic synovectomy combined with postoperative LD-RT significantly reduces recurrence compared to surgery alone, though it is associated with an increased risk of localized skin pigmentation.