Profile of bilateral anterior cruciate ligament injuries: A retrospective follow-up study

Journal of Orthopaedic Surgery, Dec 2004 by Motohashi, M

ABSTRACT

Purpose. To assess the mechanism of injury of anterior cruciate ligaments, surgical results, and radiographic findings among patients with bilateral knee injuries, and to compare these features with those of patients sustaining unilateral injuries.

Methods. From 1977 to 1988, among 458 patients with injury of anterior cruciate ligament operated in our hospital, 11 were of bilateral injury, in whom 10 could be followed up. A laxity score was calculated to evaluate laxity of 7 joints. A notch width index was measured to show the narrowing of femoral notch.

Results. The mean follow-up duration was 3 years 3 months. All 10 patients with bilateral injury of anterior cruciate ligaments were female, and 90% had non-contact injuries. The mean (standard deviation) laxity score was significantly higher in the bilateral injury group than in the unilateral injury group (3.3 [1.4] versus 2.2 [1.4] points; p

Conclusion. These results suggest that several factors are involved in the occurrence of the anterior cruciate injuries. Besides being younger at the time of the first injury, patients in bilateral injury group had higher mean laxity score and lower mean notch width index than unilateral injury group. Most of the injuries in bilateral group were of non-contact type.

Key words: anterior cruciate ligament; joint instability; knee injuries

INTRODUCTION

Injuries of the anterior cruciate ligaments (ACL) can occur during participation in sports, and are classified into two types, depending on the mechanism of injury: contact and non-contact. Non-contact injury is more common. Souryal et al.1 reported that 58 (79.5%) of 73 ACL injuries were non-contact. The aetiology of ACL injuries, however, is probably multifactorial. By examining patients with injuries of the ACL who underwent surgery at our hospital, we compared the age, activity level, injury mechanisms, surgical results, and radiographic findings between those who had bilateral injuries and those who had unilateral injuries.

MATERIALS AND METHODS

Surgical treatment of injuries of the ACL in 458 knees was performed at Kowan Hospital in Japan between January 1977 and December 1987. A total of 161 patients-54 males and 107 females-had unilateral injuries and could be followed up after surgery. The mean age of 161 patients at the time of injury was 19.8 years (range, 12.0-45.0 years). Injuries were bilateral in 11 patients (i.e. 22; 4.8% of knees), one of whom was lost to follow-up. The mean age of the other 10 patients-all females-at the time of surgery was 18.2 years (range, 12.8-23.7 years). The patients were operated on on separate occasions. The mean follow-up duration was 3.3 years (range, 1.1-7.4 years). Because the period of treatment spanned more than 10 years, different surgical methods were used: for example, primary suture of the ACL and reconstruction using the iliotibial band in 7 knees, reconstruction using semi-tendinous muscles and the iliotibial band in 6 knees, and reconstruction using semi-tendinous muscles and the gracilis muscle ligament in 2 knees.2,3 Some injuries were complicated, and involved the medial meniscus alone in 5 knees, the medial meniscus and posterior cruciate ligament in one knee, the lateral meniscus and lateral collateral ligament in one knee, and the medial and lateral menisci in one knee.

The author examined all patients and investigated the types of injuries and level of sports that caused them. Patients were also classified according to how they returned to sporting activities: group A, patients returning to the former level of sporting activities; group B, those returning to sporting activities with a reduced ability; group C, those turning to other sports; and group D, those who discontinued sports.2

Joint mobility and other factors were also evaluated. According to the Nakajima, Lachman, and anterior drawer tests, instability was described as severe or definite, slight, and no instability. The Nakajima test is a reverse pivot shift test. The flexibility of 7 joints (wrist, knee, spine, elbow, shoulder, ankle, and hip) was assessed with the joint laxity test (Fig. 1).4 Each flexible joint was given one point; a total of 7 points was the full joint laxity score, signifying maximum flexibility.

The standing femorotibial angle-the lateral angle between axes of femoral and tibial shafts-was measured by using anteroposterior radiographs of the knee in the standing position. The inclination angle of the tibial plateau-the average inclination of medial and lateral tibial plateau to the tibial shaft-was measured by using lateral radiographs. A line was drawn from the popliteal groove parallel to the joint surface on the images of the intercondylar fossa, and the notch width index-the ratio of the width of the intercondylar notch to that of the distal femur-was measured (Fig. 2). This method was based on the one described by Souryal et al.1 However, we considered that their method would give the anterior outlet-the anterior portion and the narrowest site-of the intercondylar fossa, we measured the clear osteosclerotic posterior arch and regarded it as the width of the intercondylar fossa.