2017 ISAKOS Biennial Congress Paper #112
Rotational Laxity and Collateral Ligament Laxity after Total Knee Arthroplasty with Rotating Platform
Hermann O. Mayr, MD, Prof., Munich GERMANY
Anke Bernstein, MD, PhD, Freiburg GERMANY
Norbert P. Suedkamp, MD, PhD, Freiburg GERMANY
Amelie Stoehr, MD, Munich GERMANY
University Hospital, Freiburg, GERMANY
FDA Status Not Applicable
TKA with rotating platform preop valgus knees show a significantly increased rotational laxity but no increased collateral ligament laxity compared to preoperative varus knees
Question: Is there an increased laxity of clinical significance at knees with preoperative(preop) valgusalignement compared to knees with preoperative varusalignement after total knee arthroplasty (TKA) with rotating platform?
Retrospective study including 81 patients (43f, 38m), 6 years follow up, either preoperative valgus- or varusalignement of the leg. All patients had been supplied with the same TKR (CR) with a rotating platform. The subjective and objective findings were assessed by KSS, OKS, WOMAC, KOOS and IKDC 2000. Rotational laxity of the joints was evaluated with a validated instrument (Laxitester) under a 2 Nm torque in internal and external rotation of the knee 30 ° flexion of and compared to the contralateral side.
follow-up: 6.4 ± 0.9 years. 31 patients had a preoperative valgusalignement 11 ° -18 and 50 patients a varus leg axis 8 ° -19 °. In the preop valgus knees rotational analysis showed an average of increased laxity in external rotation of 7.9 ° and 2.8 ° in internal rotation compared to the varus knees (p = 0.001). There was no significant difference in medial (valgus: 2.6mm/varus: 2.5mm) and lateral (valgus: 2.8mm/varus: 2.7mm) laxity in 30 ° flexion. In all classical joint replacement scores there was no significant difference in follow-up. In IKDC objective 50% of the preop varus knees and 25.8% of the preop valgus knees were nearly normal (Group B). The difference in the IKDC objective was highly significant (p <0.001).
6 years after TKA with rotating platform preop valgus knees show a significantly increased rotational laxity but no increased collateral ligament laxity compared to preoperative varus knees. There is a significant difference in IKDC objective.