Special high-flexion prosthetic designs show a small increase in postoperative flexion compared to standard designs and some papers show increased anterior knee pain with these prosthesis. However, no randomised controlled trails have been published which investigate difference in postoperative complaints of anterior knee pain. To assess difference in passive and active postoperative flexion and anterior knee pain we performed a randomized clinical trial including the two extremes of knee arthroplasty designs, being a high flex posterior stabilized rotating platform prosthesis versus a traditional cruciate retaining fixed bearing prosthesis. We hypothesised that the HF-PS design would allow more flexion, due to increased femoral rollback with less anterior knee pain than the CR design. We specifically assessed the following hypotheses: Patients have increased flexion after HF-PS TKA compared to CR TKA, both passive and active. Patients show an increased femoral rollback in the HF-PS TKA as compared to the CR TKA. Patients receiving a HF-PS TKA design report reduced anterior knee pain relative to those receiving the CR TKA. In total 47 patients were randomly allocated to a standard cruciate retaining fixed bearing design (CR) in 23 patients and to a high-flexion posterior stabilized mobile bearing design (HF-PS) in 24 patients. Preoperative and one year postoperative we investigated active and passive maximal flexion. Furthermore, we used the VAS pain score at rest and during exercise and the Feller score to investigate anterior knee pain. A lateral roentgen photograph was used to measure femoral rollback during maximal flexion.Introduction
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