Does Pre-hab Improve Outcomes Post ACLR?

In the US, there are over 250,000 ACLR every year which equates to ~$5B direct health care cost annually.  However, this does not include the downstream health care cost associated with complications.  With recent literature indicating high probability for OA 12 years later (79%) and 20% suffering a second ACLR in 2 years, it is not surprising that more and more are looking at every possible alternative to improving short and long term outcomes.  As a result, it has become common practice in many sports medicine settings in the US for physicians to order pre-operative rehabilitation prior to surgery. 

In the US, the primary goals of this rehabilitation is decreasing effusion, increasing range of motion and improving or maintaining quadriceps strength prior to surgery.  The philosophy behind this is that the increased range of motion, the decrease in effusion and improved quadriceps strength will result in a higher level of strength prior to surgery which results in higher strength or faster return to baseline strength post-surgery.  Typically in the US this only consists of 1-4 sessions as the surgery is usually performed in the first week post injury.  Conceptually, this goes along with everything we know about muscle and soft tissue physiology and but yet has not been well supported in the research.  Not that this is contradicted in the research but rather that the research has not been done to support.  As a result, many insurance carriers refuse to pay or often question the practice (despite it is in the best interest of the patient).

In the September issue of the American Journal of Sports Medicine, there is a great article “Effect of Prehabilitation on the Outcome of Anterior Cruciate Ligament Reconstruction” that attempts to look at the impact of prehab has on outcomes.  In this study, the authors used 20 volunteers who were awaiting ACLR and assigned them to a control group (N=9) or exercise group (n=11).  Prior to the intervention, the authors collected the following data on each subject: single leg hop, quadriceps and hamstring peak torque, MRI cross sectional area of the quadriceps, modified Cincinnati Knee Rating System and muscle biopsy of the vastus lateralis.  Each of these was done at baseline, pre-operatively and 12 weeks post operatively.

Methods:  The exercise group performed a 6 week program consisting of 4 exercise sessions per week consisting of 2 supervised gym sessions and 2 supervised home sessions.  The gym exercise sessions focused on quadriceps strengthening and proprioception with the exercise intensity determined by 1 RM (% of 1 RM for starting point was not provided).  Exercises were performed for 3 sets of 12 reps with incremental increases of 10%-20% weekly. At post-op rehabilitation, patients underwent the same “aggressive” ACL rehabilitation protocol and were reassessed at 12 weeks.

Results:  At the pre-operative assessment, the Single Leg Hop tests and the Modified Cincinnati Knee Rating System were significantly improved in the exercise group when compared to the control.  However the cross sectional area (CSA) of the quadriceps was not significantly different when compared to the control.  These same results were also reflected at the 12 week post-operative reassessment.  So, although the patient’s self-reported function was better and the Single Leg Hop Test was better, the CSA of the quadriceps had little change with the pre-hab. 

Discussion: This might lead one to conclude that pre-had is not effective for decreasing the atrophy often seen post op ACLR and therefore pre-had is not beneficial.  Before one makes that conclusion, there are several things to consider with this study.

1. Application to pre-hab in the US.  This study was performed in Ireland and the pre-habilitation was performed for 6 weeks prior to surgery. In the US, most ACLR are done within the first week of the injury.  Therefore the disuse atrophy that you would see from this study may not be applicable as the surgery in the US is done much closer to the date of injury than in this study. The results are also the result of 6 weeks of training.  In the US, you would not usually have that amount of time with the patient prior to surgery.
2. Inflammation Control.  In this study there was no mention of controlling effusion.  We know that effusion has a large impact on quadriceps inhibition through mechanoreceptors stimulation as well as histamine release.  If this effusion is not controlled, this will have a profound impact on quadriceps atrophy. 
3. Cross Sectional Area of quadriceps – although the exercise program is based on 1RM (which implies intensity) there is no % of RM described.  That being said, if the % was too low, then this could account for lack of quadriceps development.  Along with that is the use of eccentric strengthening.  In studies published by LaStayo et al, we know eccentric training has a significant impact on quadriceps hypertrophy compared to controls.  In review of the exercise program, eccentric training did not appear to be a focus.

Considering the above points, the application of this study to US based pre-habilitation programs is not completely clear.  Therefore, one cannot base their decision on pre-hab solely on this study alone.  However, it does validate the importance of single limb testing.  In this study, there appears to be a strong correlation to single limb hop testing and patient’s self-reported outcome on the Modified Cincinnati Knee Rating System.  Several studies have indicated the importance of single leg hop test as a better indicator of return to sport capability versus the open kinetic chain testing of quadriceps peak torque.  Although both are important, since most of sports are single limb in nature and closed kinetic chain, this would seem to make sense that single leg hop is a better indicator and is a fact well supported in the literature.

It also lends to the question of how are return to sport decisions made?  Currently there is no standardized methodology to determine an athlete’s functional ability.  That being said, something that assesses the entire lower kinetic chain and which includes single limb testing would be a logical choice.

Reference:

Shaarani S, O’Hare C, Quinn A, Moyna N, Moran R, O’Byrne J.  Effect of Prehabilitation on the Outcome of Anterior Cruciate Ligament Reconstruction.  Am J Sport Med.  41:2117-2127.  2013.

Barber SD, Noyes F, Mangine R, DeMaio M.  Rehabilitation After ACLR: Functional Testing.  Orthopedics.  15:969-974.  1992.

Gerber P, Marcus R, Dibble L, LaStayo P.  The Use of Eccentrically Biased Resistance Exercise to Mitigate Muslce Impairments Following Anterior Cruciate Ligament Reconstruction. Sports Health. 1:31. 2009