22/07/2025
A study from Eastlack et al. (1999) showed that ACL-deficient individuals who cope well can return to sport despite increased laxity. In other words, objective laxity ≠ functional instability.
Laxity values (KT-2000 measurements):
🔹 Copers: 5.5 ± 2.7 mm
🔹 Chronic non-copers: 5.1 ± 2.8 mm
🔹 Subacute non-copers: 4.2 ± 2.2 mm
- No significant difference in anterior tibial translation between groups.
Participants were classified into three groups: copers, subacute non-copers, and chronic non-copers. All had complete ACL ruptures and were previously involved in Level I or II sports. Subacute non-copers were 1–6 months post-injury, while chronic non-copers were more than 6 months post-injury. A non-coper was defined as someone unable to return to their pre-injury activity level due to repeated episodes of knee instability or “giving way.”
Despite having similar levels of knee laxity, copers significantly outperformed non-copers across all functional domains:
🔹 Higher Quadriceps Index, indicating better strength in the injured limb
🔹 Superior hop test results on all four tests: single hop, triple hop, cross-over hop, and timed hop
🔹 Higher self-reported function via Lysholm Knee Outcome Survey - Sport Score, and Global Rating scores
Predictive variables that best identified copers:
🔸 Global Rating of Knee Function
🔸 Knee Outcome Survey - Sport Score
🔸 Quadriceps Maximal Voluntary Isometric Contraction
🔸 Cross-over hop performance
Despite up to 5.5 mm laxity, copers had fewer giving-way episodes, better strength, and maintained Level I/II sports without surgery.
