Knee dislocations: where are the lesions? A prospective evaluation of surgical findings in 63 cases.

OBJECTIVE: To evaluate soft-tissue injury patterns in a large series of patients with knee dislocations to identify frequency and associations that may aid in surgical planning.

DESIGN: Prospective clinical study.

SETTING: Two institutions, both level I trauma centers.

PATIENTS: Sixty patients with 63 dislocatable knees.

RESULTS: Cause of injury was motor vehicle injury in 34 patients, sports in 23 patients, and falls in 3 patients; 71% of knees studied had bicruciate injuries. Eight knees had associated major intraarticular fractures. Vascular disruption occurred in 14% of knees. Peroneal nerve palsies occurred in 14% of knees. All injured knees with complete peroneal nerve palsies had anterior cruciate ligament, posterior cruciate ligament, and lateral collateral ligament disruptions. The incidence of vascular injury was the same for patients injured in sports as for those injured in road trauma. Reattachable ligamentous avulsions occurred in 19% for anterior cruciate ligament, 51% for posterior cruciate ligament, 64% for medial collateral ligament, and 84% for lateral collateral ligament injuries. Certain injury patterns also had a high association of tendon and capsule avulsions. Proximal lateral collateral ligament injuries were commonly associated with popliteus tendon avulsions and seldom with distal biceps avulsions. Distal lateral collateral ligament injuries were commonly associated with distal biceps avulsions and seldom with popliteus tendon avulsions. Reattachable meniscal capsular avulsions off the tibia occurred predominantly when the collateral ligament injury was a distal avulsion.

CONCLUSIONS: This study showed a wide variety of injury patterns. Knees had to have at least two ligaments injured to be dislocatable but not necessarily both cruciate ligaments. Sports injuries have the same pattern of injury as motor vehicle accidents, suggesting similar forces of injury. The study demonstrates a high incidence of reattachable avulsion injuries to ligaments and soft tissues in dislocatable knees. These may not be as easily dealt with if surgery is delayed beyond 3-4 weeks.