Preliminary results after total knee arthroplasty without femoral trochlea: evaluation of clinical results, quality of life and gait function

Evaluation of the clinical and functional results of a new prosthetic knee design with conservation of the physiologic properties of the patellofemoral joint. After total knee arthroplasty there are often patella problems. Some of them may be a result of excessive retropatellar pressure caused by the prosthetic design. Twelve patients with an average age of 68.6 years were evaluated after a follow-up of 16.4 months after implantation of a new prosthetic design. The clinical results were evaluated with the Hospital for Special Surgery Scores (HSS) and the Knee Society Clinical Rating Systems (KSS). Pain was rated on a Visual Analog Scale (VAS). Quality of life was determined with the SF-36 questionnaire. Furthermore, clinical gait analysis was performed with a 3D motion analysis system and force plates as well as surface electromyography of seven lower extremity muscles. The HSS-Score reached a mean value of 79.3 points. The KSS reached 82.3 points for the knee score and 75 points for the functional score. The VAS for pain revealed an average value of 1.7. For the gait analysis only three parameters indicated significant differences between the affected and the contralateral leg. The mean EMG amplitude revealed a significant difference only for the biceps femoris. The clinical and functional outcome of a new prosthesis design show satisfactory results. Even if the presented results appear promising, a further application and long term results are needed.