Total knee replacement versus osteochondral allograft in proximal tibia bone tumours

Total knee modular megaprosthesis or osteochondral allograft are used to preserve joint movement in bone tumours of the proximal tibia. The aim of this study was to compare two groups of patients with total knee modular megaprosthesis and osteochondral allograft through an objective analysis. Eighteen patients, ten treated with prosthesis (TKR group) and eight with osteochondral allografts (AL group), were included in the study. X-ray, muscular strength measurements, and studies of gait analysis including electromyography (EMG) were used to compare functional results of patients. In the TKR group a higher incidence of knee extension lag was found. While the TKR group had a prevalent knee stiff/hyperextension pattern with reduced rectus femoris activity, the AL group had a higher percentage of normal knee pattern. Knee extensor muscular strength was reduced in the TKR group. TKR functional performance during gait is in most cases abnormal, consistent with the weakness of the extensor apparatus and knee extension lag. Although a greater rate of normal walking was found in the AL group, problems related to a short patellar tendon, knee instability, and joint mismatching were considered to be responsible for abnormal knee kinematics. An allograft, when optimal reconstruction is performed, gives better functional results.