Comparison of clinical features, management and outcomes of osteosarcoma located in proximal fibula and proximal tibia: a propensity score matching analysis

Abstract

Background

The aim of this study was to compare proximal fibular and proximal tibial sites regarding osteosarcoma in the proximal crus. Furthermore, we proposed a hypothesis explaining the differences.

Methods

From Jaunary 2000 to February 2015, 28 patients with non-metastatic proximal fibular osteosarcoma and 214 patients with non-metastatic proximal tibial osteosarcoma underwent surgery were identified in our center. All clinical data were analyzed retrospectively. Propensity score matching of patients in a 1:2 ratio was conducted based on age, gender and Enneking stage. To analyze possible factors resulting in amputation, we investigated extraosseous tumor volumes (ETVS), the nearest of the blood vessel to reactive zone (NBR) and the nearest of the blood vessel to tumor (NBT).

Results

Amputation rates were higher in the proximal fibula cohort (35.7%) than in the proximal tibia cohort (14.3%; p = 0.046). Comparing possible clinical characteristics related with amputation between two cohorts, the proximal fibula cohort had larger ETVS (p = 0.000). Moreover, the proximal fibula cohort had a smaller NBT for anterior tibial vessels (p = 0.025), a smaller NBR for posterior tibial vessels (p = 0.013) and a smaller NBT for posterior tibial vessels (p = 0.007) than the proximal tibia cohort. Univarite and multivariable analyses showed that NBT for posterior tibial vessels was the only independent factor associated with amputation. The 3-year event-free survival (EFS) and overall survival (OS) rates for the proximal fibula cohort vs. the proximal tibia cohort were 52.6% vs. 78.0% (p = 0.045) and 63.7% vs. 81.2% (p = 0.177), respectively. The MSTS scores for the functional evaluation of limb-salvaging surgery were similar in both groups (p = 0.212).

Conclusions

Amputation rates among patients were higher when osteosarcoma was located in proximal fibula than in proximal tibia. A smaller NBT for posterior tibial vessels was associated with higher amputation rates. Prognosis of the proximal fibula cohort was poorer than that of the proximal tibia cohort of osteosarcoma patients.