GAIT ANALYSIS OF PATIENTS WITH TIBIAL ROTATIONPLASTY

PURPOSE: Treatment of osteosarcoma of the distal femur usually consists of above knee amputation, or, in extreme cases, hip disarticulation. As the survival rate for these patients has improved due to advances in chemotherapy, limb salvage techniques such as tibial rotationplasty have been developed to improve the patient's functional ability. In this relatively rare procedure, the tumor is resected by removing the knee joint, distal femur, and proximal tibia and fibula. The remaining tibia is then rotated 180 [degrees] and fused to the femur. The rotated ankle joint is then able to flex and extend the knee joint of a special prosthesis. The purpose of this study was to investigate the functional results of this treatment using gait analysis. SUBJECTS: Five subjects (3 males, 2 females, mean age = 19, range = 9-26) who had undergone tibial rotationplasty were compared to normal control subjects (n=15, 9 females, 6 males, mean age = 31, range = 17-42). METHODS AND MATERIALS: Fifteen retroreflective markers were placed over bony landmarks on the pelvis, femur, tibia, ankle, and feet. The motion analysis system consists of a six camera Expert Vision[R] system (Motion Analysis Corporation, Santa Rosa, CA) which provided three dimensional trajectory data of the markers using AMASS software (ADTECH, Gaithersburg, MD) at a sampling rate of 60 frames/second. Orthotrack 4.1 software (Motion Analysis Corp., Santa Rosa, CA) was used to calculate relative joint motion of the pelvis, hip, knee, and ankle in the sagittal, frontal, and transverse planes. ANALYSES: Temporal factors and sagittal plane kinematics (total joint excursion and mean joint angle) of the pelvis, hip, knee, and ankle of the rotationplasty limb during a gait cycle were compared to normal values. Two sample t-tests were performed to determine if these parameters differed significantly between rotationplasty and normal subjects, with significance set at p=0.05. RESULTS: While there were statistically significant differences between normal and the rotationplasty subjects for velocity and cadence, there was no difference for stride length and single limb support time of the rotationplasy extremity. No statistical difference was found for total joint excursion or mean joint angle in the sagittal plane for all joints except the ankle. CONCLUSIONS: A reduced total joint excursion value for the ankle was expected since the rotationplasty prosthesis has a solid ankle. Normal knee, hip, and pelvis function suggest that this procedure is a viable alternative to above knee amputation.
Kotajarvi BR, Shin DS, Sim FH, Kaufman KR; Orthopedic Biomechanics Lab, Mayo Foundation, Rochester, MN, [...]