Inconclusive benefit of adjuvant ⁹⁰Yttrium hydroxyapatite to radiosynovectomy for diffuse-type tenosynovial giant-cell tumour of the knee

Aims Intra-articular ⁹⁰Yttrium (⁹⁰Y) is an adjunct to surgical treatment by synovectomy for patients with diffuse-type tenosynovial giant-cell tumour (dtTGCT) of the knee, with variable success rates. Clinical information is, however, sparse and its value remains unclear. We investigated the long-term outcome of patients who underwent synovectomy with and without adjuvant treatment with ⁹⁰Yttrium. Patients and Methods All patients with dtTGCT of the knee who underwent synovectomy between 1991 and 2014 were included in the study. Group A patients underwent synovectomy and an intra-articular injection of ⁹⁰Yttrium between six and eight weeks after surgery. Group B patients underwent surgery alone. Results There were 34 patients in group A and 22 in group B. Recurrence of dtTGCT was identified by MRI, which was undertaken in patients with further symptoms. At a mean follow-up of 7.3 years (2.5 to 25.4), there was residual disease in 15 patients in group A and 11 in group B (p < 0.363). The mean Musculoskeletal Tumor Society (MSTS) score at final follow-up was 85% and 83%, respectively (p < 0.91). Conclusion There were no significant differences in outcome between patients treated surgically for dtTGCT of the knee with or without an adjuvant intra-articular injection of ⁹⁰Yttrium. We were unable to provide conclusive evidence of any benefits derived from the adjuvant treatment.