Roentgenographic evaluation of geometric total knee arthroplasty with a six-year average follow-up period.

The geometric total knee prosthesis was used in the reconstruction of 70 damaged knee joints in 56 patients from November 1973 through March 1979. The average follow-up period extended to six years and seven months. Eleven patients had died and four could not be located. Eighty-one percent of the remaining knees had little or no pain at the time of the review. Pain in the patellofemoral joints was an insignificant problem in this series. The femorotibial shaft angle ranged from 0 degrees to 10 degrees of valgus in 43 (82.7%) of 52 knees. Six knees showed varus deformity at the time of follow-up examination. Stress fracture of the medial condyle of the tibia was found in two of these six knees. The absence of a radiolucent zone at the tibial cement-bone interface was noted in only ten (19.2%) of the 52 knee roentgenograms. New formation or progression of a radiolucent zone from six to 12 months after the operation was found in 36.5%. Positional abnormality of the marker wires seen in serial roentgenograms existed in 51.9% of the knees. Nine knees (17.3%) disclosed a gap between the metallic articular surface and the tibial component and also showed the collision of the tibial intercondylar eminence against the femur in the standing position. The tibial component of the prosthesis was fractured in one knee.