In my first in a series of ‘Research Review’ articles for MedBridge Education, I will review a recent study that appeared in The American Journal of Sports Medicine. 

Shaarani et al investigated the utility of a Prehabilitation program for patients scheduled to undergo anterior cruciate ligament reconstruction (ACLR). Considering the variable rate of return to sport following ACLR (43-93%), urgency exists for improving rehabilitation following ACL injury.

Study Design

Randomized Controlled Trial (RCT).


20 patients with a rupture of the ACL were recruited from 2 orthopedic centers between December 2010 and December 2011. Following randomization, 11 patients were assigned to the intervention group while 9 were placed in the control group. No significant differences existed between groups for age, height, weight, body mass index, and Tegner activity level before/after injury.

Inclusion Criteria: Males between the ages of 18 and 45 years old with an isolated ACL tear. All patients had a positive anterior drawer, Lachman, and pivot-shift test.

Exclusion Criteria: Associated fractures, meniscal repair, collateral ligament injury requiring repair/reconstruction, comorbidities that would be contraindicated from high physical exertion, and living outside the Greater Dublin area for practical reasons related to exercise supervision and exercise gym usage.


Outcome Measures: Single-leg hop test, peak torque of the quadriceps and hamstring, muscle cross-sectional area (CSA), Modified Cincinnati Knee Rating System (mCKRS), and Tegner activity level.

Randomization: From a pool of 437 patients, 56 were eligible following inclusion/exclusion criteria. There were, however, 14 non-responders and 19 subjects who refused to participate. Randomization was determined following outpatient consultation. Opaque envelopes were used to randomly assign individuals to their group.

Interventions: The Prehabilitation Group (PG) was enrolled in a 6-week exercise program, which consisted of supervised resistance and balance training. This program was comprised of 4 exercise sessions per week, which included 2 supervised gym sessions and 2 supervised home sessions. The primary focus was lower limb strengthening with a quadriceps emphasis, as well as proprioceptive training. Each exercise consisted of 3 sets of 12 repetitions and the weights were increased weekly by 10-15%. During the last gym session, the weights were reduced to the previous week’s value to prevent preoperative fatigue and to favor the muscular response to endurance and gaining mass. In contrast, the Control Group (CG) was not given a pre-operative exercise program; however these patients were not discouraged from exercise or taking part in normal activity of daily living before surgery. Postoperatively, both groups received standardized physical therapy sessions, which included increasing range of motion (ROM) and weight-bearing while improving symmetry and gait pattern.


Immediately following the 6-week Prehabilitation program, the intervention group showed several significant improvements prior to surgery. These benefits included the following: significantly improved single-leg hop testing; increased quadriceps and vastus medialis CSA, and improved mCKRS. At 12 weeks post-operative, the rate of decline in the single leg hop test was less and the mCKRS was significantly improved in the exercise group compared with the CG, however no changes existed between groups in CSA. Of particular importance was that on average patients in the PG returned to sport in 34.2 weeks versus 42.5 weeks in the CG though this did not reach statistical significance (P=0.055).


The most important limitations of this study were the small sample size (n = 20) and the lack of a long-term follow-up in comparison to the typical rehabilitation length. It is therefore difficult to extrapolate these short-term benefits to long-term outcomes. Additionally, single-leg hop and peak quadriceps torque testing were observed by an individual who was not blinded to the treatment groups. Finally, in terms of the study design itself, utilizing a sham exercise program would have eliminated the potential attention bias.

Clinical Implications

This pilot study supports implementing a prehabilitation program following ACL injury in preparation for surgical intervention. As previously stated, the percentage of patients who are able to return to sport following ACLR is broad and relatively unimpressive. The benefits of prehabilitation demonstrated during this initial investigation could have a profound impact on return to sport following ACLR. The improvement in single-leg hop testing is particularly encouraging, as it has been documented to be a problematic area with regards to athletes following ACLR. Both Myers et al and Xergia et al found significant asymmetries in single-leg hop testing between individuals who had undergone ACLR and uninjured control subjects. Following rehabilitation, athletes need to have the proprioceptive ability and confidence to perform single-leg stopping, cutting, and jumping activities without hesitation. Coinciding with these measures, this study did show a shorter timeframe for return to sport in athletes who completed a course of prehabilitation. Despite not reaching statistical significance, an average decrease of over 8 weeks is clinically meaningful to any sports medicine practitioner, athlete, or coach.

Shaarani SR, O’Hare C, Quinn A, Moyna N, Moran R, O’Byrne JM. Effect of Prehabilitation on the Outcome of Anterior Cruciate Ligament Reconstruction. American Journal of Sports Medicine. 2013; 41(9): 2117–2127.

Continued Reading…

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