A prospective comparative clinical analysis of the first-generation knee replacements: polycentric vs. geometric knee...

A prospective study of 119 polycentric and 92 geometric knee replacements was performed to determine and compare the clinical effectiveness of these two prostheses. All kneex were followed for a minimum of 2 years and a mean time of 3 1/2 years (2--6 years). Data were collected using a specially designed proforma for subsequent computer analysis. Failure occurred in 11% of the polycentric and in 16% of the geometric knees. Males (8 of 47) and patients with osteoarthritic knees (22 of 68) failed most frequently. Both prostheses provided excellent relief of pain, the same degree of flexion and improvement in flexion contracture. However, walking, function, alignment, stability, muscle strength and patellar mobility varied as to the degree of improvement and the type of prosthesis. Present results with prosthetic knee replacement using a completely new operative technique can be used as a basis for comparison with other contemporary and future arthroplasty designs.