Abstract
Background:
The purpose of this study was to determine whether internal mal-rotation of the femoral component is associated with arthrofibrosis in TKA. Multiple etiological factors have been suggested, but specific causes have not been identified. We hypothesized arthrofibrosis may be triggered by a combination of non-physiological kinematics (femoral component internal rotation) and a tight medial compartment.
Methods:
From a consecutive cohort of 3058 mobile bearing TKA forty-four (1. 4%) cases were diagnosed as having arthrofibrosis, of which thirty-eight (86%) cases could be recruited. Thirty-eight patients with a well functioning TKA served as matched controls. Evaluation included CT investigation to determine femoral component rotation with reference to the transepicondylar axis (TEA).
Results:
Femoral components in the AF group were significantly (p< 0. 00001) internally mal-rotated by a mean of 4. 7 degrees ranging from ten degrees internal rotation (IR) to one degree external rotation (ER). Mean femoral rotational in the control group was parallel (0. 3 degrees IR) to the TEA (six degrees IR to four degrees ER). Arthrofibrosis was not associated with age, gender, body-mass-index, or preoperative diagnosis.
Conclusions:
There is a highly significant association between arthrofibrosis in TKA and internal mal-rotation of the femoral component. On the base of these results it was hypothesized that non-physiological kinematics in TKA with mal-aligned femoral components influence and/or trigger arthrofibrosis in TKA.
Clinical Relevance:
In TKA with arthrofibrosis, we now consider femoral CT evaluation with the view to surgically rebalancing the flexion gap and realigning the femoral component, when internal mal-rotation is confirmed.
*This study has been cleared by the Ethical Committee, University of Zurich, Switzerland.
Balgrist University and Schulthess Klinik, Zurich, Switzerland.
