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

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/s 2 ± SD 9 versus 13m/s 2 ± SD6 for the unaffected side, p=0.02) whereas rotationplasty patients exhibited greater acceleration on the normal side (29m/s 2 ± SD7 versus 15m/s 2 ± 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.