AIMS: Osseous invasion exhibited in soft-tissue sarcoma (STS) is recognized as a prognostic risk factor. Achieving a wide margin is the default surgical approach for local control. However, for STSs where the tumour is in contact with the adjacent cortex but without clear evidence of osseous invasion, such as medullary invasion, the question of whether bone resection can provide better local control or survival than more conservative sub-periosteal excision remains controversial. The aim of this study was to assess whether bone resection for thigh STS with cortical contact of the adjacent bone results in better local control and survival compared to sub-periosteal dissection, and to investigate the prognostic factors for clinical outcomes in STS. METHODS: A retrospective cohort study was conducted on 142 patients with thigh STS exhibiting cortical contact but without medullary invasion, from May 2000 to May 2020. Patients underwent either composite bone resection or sub-periosteal excision. Demographics, clinical outcomes, and functional outcomes were compared between the two groups. Additionally, Cox regression analysis was used to analyze risk factors for local recurrence. RESULTS: The five-year overall survival, local recurrence-free survival, and metastasis-free survival among patients with bone resection was 74.0%, 65.9%, and 74.1%, respectively, compared to 72.9%, 68.3%, and 72.0%, respectively, among patients with sub-periosteal excision. The cumulative incidence of recurrence was 33.1% for patients who underwent bone and 36.4% for those with sub-periosteal excision (p = 0.681). In multivariate analysis, STS with high Fédération Nationale des Centres de Lutte Contre Le Cancer (FNCLCC) grade, invasion involving posterior intermuscular septum, medial intermuscular septum, and adductor brevis were found to be associated with poorer prognosis. The mean Musculoskeletal Tumor Society (MSTS) score in the bone resection group was 24.7, significantly lower than the 28.3 in the sub-periosteal group (p <
0.001). CONCLUSION: Routine bone resection failed to improve local control or survival in STS patients with cortical bone contact, but resulted in significantly impaired postoperative function. A more conservative sub-periosteal excision approach may be preferable for these cases.