A Re-evaluation of Amputations versus Rotationplasties in the Reconstruction of Tumors about the Knee

Abstract

Background Rotationplasties are considered superior to above knee amputations (AKA) in the reconstruction of tumor-ablated limbs. We compared both procedures performed for patients with musculoskeletal tumors about the knee, to answer the following: 1. Are subjective functional outcomes among knee rotationplasty (KRP) patients superior to above knee amputees? 2. Are objective gait parameters of above knee amputees inferior to rotationplasty patients? Methods We evaluated 19 patients who had undergone AKA or KRP for distal femur or proximal tibia tumors. Four underwent AKA, while 7 had KRP. Patients were assessed using motion capture and force plate array analysis. Subjective function was assessed using the Musculoskeletal Tumor Society (MSTS) Score. Results Ten males and 9 females were followed an average 4.0 ± SD5.5 years. Mean age was 31 ± SD10 years. Above-knee amputees showed greater thigh acceleration on the affected side (22m/s2 ± SD 9 versus 13m/s2 ± SD6 for the unaffected side, p=0.02) whereas rotationplasty patients exhibited greater acceleration on the normal side (29m/s2 ± SD7 versus 15m/s2 ± SD5, p=0.0009). Amputees exerted stronger thigh forces (166N ± SD56 versus 105N ± SD47, p=0.005) on the operated side compared to the unaffected side, while KRP patients generated weaker thigh forces on the post-operative side (105N ± SD42 versus 208 ± SD62, p=0.02). MSTS scores were not statistically significant between the two groups. Conclusions Above-knee amputated limbs are stronger and more functionally normal than rotationplasty limbs. Advances in prosthetic design may eventually circumvent the need for this more complex procedure.