Management of sarcomas possibly involving the knee joint when to perform extra-articular resection of the knee joint and is it safe?

We reviewed the oncological and functional outcomes of patients treated for a primary sarcoma possibly involving the knee joint and present an algorithm to guide treatment. The records of 76 patients who had a primary bone or soft tissue sarcoma possibly invading the knee between 1996 and 2012 were identified. Mean age and follow-up was 32 years (9-74) and 64 months (12-195), respectively. Patients were grouped according to the resection (Intra-articular [IAR] vs. Extra-articular [EAR] vs. Amputation/rotationplasty) for survival and functional outcomes. Overall 5 and 10 year survival was 61% and 53%, respectively. No differences in survival were found between the 3 groups (p = 0.55). Sixteen patients developed local recurrence with no difference between the groups. Mean MSTS score was 24.5 (12-30). Mean flexion at final follow-up was 106° (70-130°). We conclude that EAR of the knee allows for good oncologic and functional outcomes but with an increased risk of complications compared to IAR. Intra-operative assessment of joint involvement can be done in patients where joint infiltration by the tumour is not clear to avoid an unnecessary EAR. For chondrosarcoma patients with joint involvement, an EAR should be carefully considered because they present a significantly higher local recurrence risk.