Anterior cruciate ligament injured copers and noncopers: A differential response to injury

Abstract

Background: Rupture of the Anterior Cruciate Ligament (ACL) results in increased tibiofemoral laxity and usually disturbs neuromuscular function, thereby ultimately resulting in knee instability and dysfunction. However, ACL rupture does not automatically result in functional impairment and instability, as confirmed by the ACL deficient (ACLD) coper, who can resume pre-morbid activity levels. Few studies have shown that ACL reconstruction (ACLR) actually restores dynamic knee stability or enables full return to preinjury activity level in most individuals.Purpose: To review the dilemma regarding which ACL-injured individuals need to undergo ACLR.Study design: Meta-analysisMethods: Electronic searches of Medline, EMBase, CINAHL, and the Musculoskeletal Injuries Group’s specialized register were performed up to June 2009 using medical subject headings and free-text words. Subject-specific search was based on the terms “ ACL rehabilitation,” “copers,” and “noncopers.”Results: Three prospective, longitudinal trials have been undertaken following an ACL screening examination. Copers (non-operated) and noncopers (operated) have been followed over a few years post injury. The results show that a similar percentage of subjects in both groups return to sporting activity. Regarding the differences between copers and noncopers, there exists investigative evidence that noncopers have deficits in quadriceps strength, vastus lateralis atrophy, quadriceps activation deficits, altered knee movement patterns, reduced knee flexion moment, higher quadriceps/hamstring co-contraction, and a tendency to hold the tibia in a more posterior position. Conclusion: No single measurement tool is sufficient in determining the functional status of the ACLD individual. Passive instability tests are poor predictors of future rehabilitation outcome. A collaboration of tests to determine the functional status of the ACL deficient individual is recommended, specifically incorporating the KOS-Sport, Global Knee Function Rating, hop tests, and Quadriceps Index. The ACL screening examination shows preliminary evidence for detecting potential copers; however, a gold-standard method of detecting who will be successful is still lacking. ACL-injured subjects should be informed of the possibility of good knee function following a nonoperative rehabilitation program.