Patellar height influences knee function in patients with aggressive bone tumors of the proximal tibia after endoprosthetic reconstruction

Abstract

Background: The proximal tibia is the second most common site of aggressive bone tumors. In proximal tibia resection, the patellar tendon is sectioned one to two centimeters from its insertion on the tibial tubercle, which makes it technically challenging to achieve an appropriate patellar height and firm fixation of the patellar tendon. The purpose of this study was to determine whether the patellar height influences knee function after proximal tibia endoprosthetic reconstruction (EPR).

Methods: Twenty-nine patients with pathologically confirmed aggressive bone tumors in the proximal tibia were retrospectively analyzed. We used the Insall-Salvati ratio (ISR) and the Blackburne-Peel index (BPI) to radiographically analyze the patellar height. Functional outcomes were retrospectively assessed using the Musculoskeletal Tumor Society (MSTS) score, the Oxford Knee Score (OKS) and the range of motion (ROM) which was evaluated through extensor lag and active flexion. Univariate analysis with Pearson's correlation and a multivariate linear regression of patient characteristics and surgery-related changes were performed.

Results: The postoperative ISRs were negatively correlated with the functionality domain of the MSTS score (function, gait, walking) and the OKS. Pearson's correlation analysis showed a significant correlation between the postoperative ISR and extensor lag. The change in patellar height had no impact on the active flexion of the knee.

Conclusions: Patellar height is an independent factor contributing to knee function after proximal tibia EPR. The quality of patellar tendon reconstruction is a key point in proximal tibia EPR after tumor resection.

Keywords: Bone tumor; Endoprosthesis; Patellar height; Tibia.