OBJECTIVES: The purpose of this study was to objectively assess the functional outcome after implantation of a Thrust Plate Prosthesis. DESIGN: This retrospective study compared the gait patterns of 33 patients to a control group. BACKGROUND: Few studies have been published about this type of prosthesis describing clinical and radiographic outcome. Even though the evaluation of the functional outcome is a commonly accepted way to measure the success of an implant it has not been reported in previous studies. METHODS: Beside clinical (SF-36, and Harris Hip Score) and radiographic evaluation subjects were examined by three dimensional gait analysis and surface electromyography from seven leg and trunk muscles bilaterally. RESULTS: The average Harris Hip Score was 85.7 points, and the SF-36 only differed significantly from controls regarding physical functioning. The radiography showed considerable radiolucencies under the Thrust Plate. Kinematic parameters indicated a slight impairment of the operated limb. The analysis revealed a decreased hip (28.2%) and knee (51.2%) range of motion during gait. The joint moments on the operated side were reduced in hip (72%) and knee abduction (59%) in comparison to controls. The average electromyographic parameters indicated a significantly higher mean and peak amplitude of the tensor fasciae latae (mean 56%, peak 54%), and gluteus medius (mean 33%, peak 21%) and a lower peak activity of the gluteus maximus (19%). CONCLUSIONS: The results indicate a generally good functional outcome even though a slightly asymmetrical loading was observed. No major limitations in physical functioning and health-related quality of life was seen. The radiographic signs of loosening might indicate difficulties in achieving the proximal load transfer of this implant. RELEVANCE: The data provided in this study may serve to establish the Thrust Plate Prosthesis as an alternative procedure in total hip replacement in younger patients.
OBJECTIVES: The purpose of this study was to objectively assess the functional outcome after implantation of a Thrust Plate Prosthesis. DESIGN: This retrospective study compared the gait patterns of 33 patients to a control group. BACKGROUND: Few studies have been published about this type of prosthesis describing clinical and radiographic outcome. Even though the evaluation of the functional outcome is a commonly accepted way to measure the success of an implant it has not been reported in previous studies. METHODS: Beside clinical (SF-36, and Harris Hip Score) and radiographic evaluation subjects were examined by three dimensional gait analysis and surface electromyography from seven leg and trunk muscles bilaterally. RESULTS: The average Harris Hip Score was 85.7 points, and the SF-36 only differed significantly from controls regarding physical functioning. The radiography showed considerable radiolucencies under the Thrust Plate. Kinematic parameters indicated a slight impairment of the operated limb. The analysis revealed a decreased hip (28.2%) and knee (51.2%) range of motion during gait. The joint moments on the operated side were reduced in hip (72%) and knee abduction (59%) in comparison to controls. The average electromyographic parameters indicated a significantly higher mean and peak amplitude of the tensor fasciae latae (mean 56%, peak 54%), and gluteus medius (mean 33%, peak 21%) and a lower peak activity of the gluteus maximus (19%). CONCLUSIONS: The results indicate a generally good functional outcome even though a slightly asymmetrical loading was observed. No major limitations in physical functioning and health-related quality of life was seen. The radiographic signs of loosening might indicate difficulties in achieving the proximal load transfer of this implant. RELEVANCE: The data provided in this study may serve to establish the Thrust Plate Prosthesis as an alternative procedure in total hip replacement in younger patients.