Knee manipulation following total knee arthroplasty. Analysis of prognostic variables.

In an effort to identify prognostic indicators for knee manipulation, the authors retrospectively reviewed the records of 60 osteoarthritic patients with posterior stabilized knee implants who required manipulation (94 knees) between January 1984 and December 1986. They also studied the records of 28 consecutive osteoarthritic patients who were implanted with 41 posterior stabilized knees between January 1985 and September 1985 whose knees did not require manipulation (control group). In both patient groups the following parameters were assessed and compared: overall knee alignment, joint line elevation, anterior to posterior (AP) dimension of the knee, AP placement of the tibial component, patellar height, obesity, age, preoperative flexion, time of manipulation, single vs bilateral knee implants, final flexion, final Hospital for Special Surgery (HSS) score, and the development of heterotopic ossification. The findings of this study showed that an increase in the AP knee dimension by 12% or greater was a critically independent variable that significantly predisposed patients to manipulation. They also show that quadriceps adhesions were another major factor leading to manipulation, and that rupturing of these adhesions led to an increase in heterotopic ossification. This review also indicated that 3 months after knee arthroplasty was a significant time for evaluation because knee flexion and HSS score at this point in the patient's recovery positively correlated with the final HSS score.