Acute posterolateral rotatory instability of the knee

Abstract

Posterolateral rotatory instability of the knee, a poste rior rotational subluxation of the lateral tibial plateau in relation to the lateral femoral condyle, is an unusual condition. Twelve cases of acute posterolateral rotatory instability are presented with an average followup of 7.5 years after surgical repair. Clinical signs suggestive of this injury included posterolateral knee tenderness, and a contusion or abrasion over the anteromedial aspect of the tibia. Indications for operative repair in cluded a 2+ or greater varus instability of the knee at 30° flexion in association with a positive external rota tion recurvatum or posterolateral drawer test. At oper ation, the consistent finding was a tear in the arcuate ligament complex in all patients. Primary operative repair resulted in stable and func tional knees in 8 of 11 patients without evidence of degenerative joint disease at 7½ years postinjury. Roentgenographic evidence of degenerative joint dis ease was present in three patients, two of whom had some residual posterolateral laxity. Results were evaluated subjectively, objectively, and functionally. There were eight good, three fair, and no poor subjective results; eight good, two fair, and one poor objective results; and seven good, three fair and one poor functional results. The single objective and functional poor result had a deep infection postopera tively. Eight of the 11 patients participated in recreational sports following repair and no patients were limited in the activities of daily living.