Anterior displacement. Its effects on instability and radiolucency in total knee replacements.

One hundred sixty-nine posterior cruciate condylar knee arthroplasties were evaluated for investigation of the effect of anterior displacement on instability and interface radiolucency in total knee arthroplasty. All knees were followed for at least one year, and 37 knees were followed for at least three years. The status of the anterior cruciate ligament at surgery was first compared to the postoperative, six-month, one-year, and three-year anterior drawer sign. A correlation coefficient was computed to test for the existence of a relation between these two variables. A chi-square test for statistical significance was used to compare the overall anterior drawer results with time and the anterior drawer sign at each follow-up evaluation with pain and radiolucent zones between cement and bone. For further evaluation of the effect of anterior stability on radiolucent zones, the authors analyzed the records of all their posterior cruciate condylar total knee arthroplasties over a seven-year period (average follow-up period, 2.5 years). Anterior stability over time was independent of the status of the anterior cruciate at surgery, and the presence or absence of an anterior cruciate ligament at surgery did not affect anterior stability over time. Furthermore, cutting of the anterior cruciate did not change anterior stability over time. Anterior instability proved to be statistically less at six months than at surgery and did not become worse with time. Neither anterior instability nor the preoperative state of the anterior cruciate ligament affects pain and interface radiolucency between cement and bone.