COMBINED INJURIES OF THE ANTERIOR CRUCIATE AND MEDIAL COLLATERAL LIGAMENTS OF THE KNEE - EFFECT OF TREATMENT ON STABILITY AND FUNCTION OF THE JOINT

We performed a retrospective study of sixty-six patients (forty-one ma le and twenty-five female) who had a combined injury of the anterior c ruciate and medial collateral ligaments, Our purpose was to determine the prevalence of late valgus instability of the knee, The mean age of the patients was thirty-five years (range, sixteen to sixty-three yea rs), The mean follow-up interval was forty-five months (range, twenty- one to 108 months), Twenty patients had been injured while snow-skiing ; twenty-four, during other sports activities; seven, in a motor-vehic le accident; and the remaining fifteen, during activities of daily liv ing, Eleven patients had reconstruction of the anterior cruciate ligam ent and repair of the medial collateral ligament, thirty-three had rec onstruction of only the anterior cruciate ligament, and twenty-two wer e managed non-operatively. There was no evidence of valgus instability on clinical examination at the most recent follow-up visit, However, there was evidence of instability on stress roentgenograms of the knee in eight (13 per cent) of sixty patients, With the numbers available, we could detect no relationship between the presence of valgus instab ility and the method of treatment of the ligamentous tears (p > 0.4). We also compared the results for twenty-one of the thirty-three patien ts who had a combined ligamentous injury and reconstruction of only th e anterior cruciate ligament with those for thirty-seven patients who had reconstruction of an isolated tear of the anterior cruciate ligame nt, After a mean follow-up interval of thirty-five months (range, twen ty-one to sixty-six months), there was no difference in the anterior d isplacement, impairment of function, level of participation in sports activities, results of the one-leg-hop for distance test, or strength as determined by testing on a Cybex machine. On the basis of the findi ngs in this study, we believe that, when there is mild or moderate val gus instability, an injury of the medial collateral ligament does not need to be repaired when the anterior cruciate ligament is repaired af ter a combined ligamentous injury.