Does joint-sparing tumor resection jeopardize oncologic and functional outcomes in non-metastatic high-grade osteosarcoma around the knee?

BACKGROUND: We previously reported joint-sparing tumor resection for osteosarcoma with epiphyseal involvement in which transepiphyseal osteotomy went through the in situ ablated epiphysis. However, we do not know whether this is a safe approach when compared with joint-sacrificed tumor resection. Our objective was to compare oncologic and functional outcomes between patients who underwent joint preservation (JP) and joint replacement (JR) tumor resection. Furthermore, we identified the risk factors of local recurrence, metastasis and survival. METHODS: Eighty-nine patients with non-metastatic high-grade osteosarcoma around the knee were treated with limb-salvage surgery (JP in 47 and JR in 42). Age, gender, tumor location, pathologic fracture, plain radiographic pattern, limb diameter change, perivascular space alteration, surgical margin, local recurrence, metastasis, death, and the Musculoskeletal Tumor Society (MSTS)-93 scores were extracted from the records. Univariate analysis was performed to compare oncologic and functional outcomes. Binary logistic and cox regression models were used to identify predicted factors for local recurrence, metastasis, and survival. RESULTS: Local recurrence, metastasis and overall survival were similar in the JP and JR group (p = 0.3; p = 0.211; p = 0.143). Major complications and limb survival were also similar in the JR and JP group (p = 0.14; p = 0.181). The MSTS score of 27.06 ± 1.77 in the JP group was higher than that of 25.88 ± 1.79 in the JR group (p = 0.005). The marginal margin of soft tissue compared with a wide margin was the only independent predictor of local recurrence (p = 0.006). Limb diameter increase and perivascular fat plane disappearance during neoadjuvant chemotherapy were independent predictors for metastasis (p = 0.002; p = 0.000) and worse survival (p = 0.000; p = 0.001). CONCLUSIONS: Joint-sparing tumor resection with the ablative bone margin offers advantage of native joint preservation with favorable functional outcomes while not jeopardizing oncologic outcomes compared with joint-sacrificed tumor resection. Surgeon should strive to obtain adequate soft tissue surgical margin decreasing risk of local recurrence. Novel drug regimens might be reasonable options for patients with obvious limb diameter increase and perivascular fat disappearance during chemotherapy.