Single-Legged Hop
Tests and Predictors of Self-Reported Knee Functional After Anterior Cruciate
Ligament Reconstruction: The Delaware-Oslo ACL Cohort Study

D, Grindem H, Lynch A, Eitzen I, Engebresten L, Risberg MA, Axe MJ, &
Snyder-Mackler L. American Journal of Sports Medicine. 2012; 40:12348-2356. doi

cruciate ligament (ACL) reconstruction is performed regularly with relatively
favorable results.  However, there
remains a lack of evidence to predict who will have favorable outcomes and who may
have problems after surgery.  Therefore,
purpose of this prospective cohort study was to assess the effectiveness single-legged hop tests to predict self-reported knee function 1-year post ACL
reconstruction.  One hundred twenty
patients (mean age = 26) received ACL reconstruction surgery and followed the
same pre- and post-operative rehabilitation programs.  Patients performed 4 single-legged hop tests
(i.e., single hop, crossover
hop, triple hop, and 6-m timed hop
) at the end of pre-operative rehabilitation
and at 6 months post-surgery. Patients also completed the IKDC 2000 (knee
outcome survey) 1-year post surgery. 
Only 84% of the patients completed the preoperative hop testing due to
various reasons (e.g., meniscal injuries, missed appointments, quadriceps
weakness/poor dynamic stability).  There
were no significant differences found in IKDC scores between those who did or
did not perform the pre-operative hop tests. 
Among the 79 patients that completed the pre-operative hop tests and
1-year knee outcome survey the authors found that none of the preoperative hop
tests could conclusively predict function 1-year post ACL reconstruction.  However, among the 85 patients that completed
the 6-month post-surgery hop tests and 1-year knee outcome surveys the authors
discovered that all of the hop tests successfully predicted self-reported knee
function. They noted that the crossover hop and 6-m timed hop indexes were the
most accurate at identifying patients who would or would not have normal knee
function at 1 year.

it appears that the single-legged hop tests performed at 6-months are accurate
predictors of self-reported outcomes 1-year post-surgery.  However, we are still lacking a tool to
assess and potentially identify patients that will likely have favorable surgical
outcomes prior to their having the surgery done.  While the study controlled for rehabilitation,
it contained a variety of graft types. 
It would be interesting to see if there were any differences among graft
types with some sub-analyses.  Furthermore,
it may be interesting to see if there are certain exercises that could be
provided if someone performed poorly at a 6-month assessment.  While the results seem favorable, there is
still room for more investigation to verify these results and to explore
pre-surgery predictors, as well as to evaluate what we can do for the patients
that are not performing well on hop tests at 6 months post-surgery.  Have you seen other clinical measures that
seem to predict favorable (or even not favorable) function after an ACL

by: Nicole Cattano 
by: Jeffrey Driban


Logerstedt, D., Grindem, H., Lynch, A., Eitzen, I., Engebretsen, L., Risberg, M., Axe, M., & Snyder-Mackler, L. (2012). Single-Legged Hop Tests as Predictors of Self-Reported Knee Function After Anterior Cruciate Ligament Reconstruction: The Delaware-Oslo ACL Cohort Study The American Journal of Sports Medicine, 40 (10), 2348-2356 DOI: 10.1177/0363546512457551