ORIGINAL ARTICLE Functional Recovery After Anterior Cruciate Ligament Reconstruction: A Longitudinal Perspective Diana M. Hopper, PhD, Geoff R. Strauss, MPE, Jeff J. Boyle, PhD, Jonathan Bell, MSc ABSTRACT. Hopper DM, Strauss GR, Boyle JJ, Bell J. Functional recovery after anterior cruciate ligament reconstruc- tion: a longitudinal perspective. Arch Phys Med Rehabil 2008; 89:1535-41. Objective: To evaluate functional hop performance in sub- jects with an anterior cruciate ligament (ACL) reconstruction with a bone-patellar tendon-bone graft during 12, 18, 26, 39, and 52 weeks. Design: A longitudinal comparative study. Setting: University research laboratory. Participants: Patients (N=19) were evaluated at 12, 18, 26, 39, and 52 weeks after ACL reconstruction surgery. Intervention: Testing on 5 separate occasions. Main Outcome Measures: The Cincinnati Knee Rating System and analog scales, the 6-meter timed hop, crossover hop, stair hop, and vertical hop, and limb symmetry indices. Results: The uninjured and injured legs and test order were randomized. There was a significant test occasion main effect for both the Cincinnati and analog scores (P=.001). Subjective rating scores improved over the 5 testing occasions. For all 4 hop tests, test occasion and limb main effects were significant (P=.001). Paired t test comparisons at each testing occasion indicated a significant difference between the reconstructed and uninjured limb (P.05). Furthermore, significant test occasion main effects were noted for limb symmetry indices for the 4 hop tests (P=.001). Using a score of greater than or equal to 85% as a criterion for normative limb symmetry, normative scores were recorded in the 6-m timed hop at the week 18 test occasion, the stair hop and vertical hop at the week 26 test occasion, and the crossover hop at the week 39 test occasion. Conclusions: These hop tests showed different levels of imposed demands on the knee that could be used to assess functional recovery and readiness to resume sport. Key Words: Anterior cruciate ligament; Knee; Rehabilitation. © 2008 by the American Congress of Rehabilitation Medi- cine and the American Academy of Physical Medicine and Rehabilitation T HE IMPORTANCE OF a patient’s perception of knee recovery, and self-confidence in performing physical tasks after ACL reconstruction, is reflected by the plethora of sub- jective rating scales reported in knee outcome studies. 1-4 Among the many rating systems, the Cincinnati Knee Rating System has been shown to be a reliable, sensitive, and valid measurement tool for defining functional knee status. 5-7 The popularity of functional performance tests for assessing knee status is clearly evident in the literature, with each task seen to place different demands on the knee joint under con- trolled clinical conditions. Both double and single-limb perfor- mance tests have been reported, involving running, jumping, and hopping tasks in straight lines or requiring pivoting and cutting actions. 8-15 The clinical utility of functional tests relates to their ability in providing an objective indication of dynamic lower-extremity performance under simulated conditions, de- signed to mimic the greater demands imposed on the knee in the everyday environment. 10,14,16-18 Single-limb tasks, such as hopping tests, offer considerable benefits compared with 2-legged tasks, because they provide between-limb, within- subject comparisons without the need to rely on population- specific normative data. The functional status of the knee is often defined by the limb symmetry index or ratio, with an index of less than 85% used as a guide for abnormal symme- try. 8,11 Furthermore, it is suggested that a score of less than 85% may indicate an increased risk of giving way of the knee during participation in sporting activities. 16 Many single-limb tests, however, have been noted to have poor sensitivity rates, and hence should not be used to detect specific deficits, but rather used as a general measure of lower-extremity perfor- mance to confirm functional limitations. 8,11 Furthermore, a combination of 2 tests or more is recommended to enhance the sensitivity of functional testing. 8,11 To date, outcome studies involving ACL-reconstructed popu- lations have largely reported knee functional status at specific postoperative periods. We have found few longitudinal reports evaluating functional recovery of the ACL-reconstructed knee during the first postoperative year. A systematic review 19 and randomized controlled trials in rehabilitation after ACL knee reconstruction 20,21 provide some insight into the rate of changes in a number of outcome measures between 3 months and 2 years after patella tendon autograft reconstruction. However, the funda- mental question of functional recovery and return to sport 22 is still unresolved. Even with the latest research, there still appears to be a paucity of literature that has investigated the progression of ACL knee construction functional recovery at different time intervals during the first year of recovery. This is especially important when advising athletes on return to sport. Therefore the primary purpose of the study was to examine functional recovery during the per- formance of 4 single-limb hop tests at 12, 18, 26, 39, and 52 weeks From the School of Physiotherapy, Curtin University of Technology, Bentley, Western Australia, Australia (Hopper, Strauss, Bell); and the Fremantle Football Club, Fremantle, Australia (Boyle). Supported by the Physiotherapy Research Foundation and Australian Physiother- apy Association, New South Wales Sports Physiotherapy Group. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organi- zation with which the authors are associated. Reprint requests to Diana M. Hopper, PhD, School of Physiotherapy, Curtin University of Technology, GPO Box U1987, Bentley, WA, Australia 6845. e-mail: D.Hopper@curtin.edu.au. Published online June 30, 2008 at www.archives-pmr.org. 0003-9993/08/8908-00181$34.00/0 doi:10.1016/j.apmr.2007.11.057 List of Abbreviations ACL anterior cruciate ligament ANOVA analysis of variance 1535 Arch Phys Med Rehabil Vol 89, August 2008