For those undergoing post-operative rehabilitation after ACL reconstruction, moderate evidence supports early, accelerated, and non-accelerated protocols because they have similar outcomes.

Rationale
One high and one moderate strength study compared two year patient outcomes between a 19-week accelerated rehabilitation program versus a 32 week non-accelerated program.14, 15The rehabilitative programs were common relative to limits in knee ROM, the amount of weight bearing permitted, and type of rehab activity prescribed –however the accelerated programs had earlier initiation of activities known to strain the ACL, including unrestricted ROM (week 4 versus week 8), earlier weaning from brace (weeks 2-6 versus weeks 4-6), earlier OKC full knee extension (week 6 versus week 12), earlier CKC and functional tasks (week 5-6 versus week 12).  At 24-months post ACL reconstruction, the two groups had similar knee laxity, clinical assessments, patient satisfaction, activity levels and functional scores; and similar detection of passive motion and knee extensor strength. 14, 15

Other moderate strength studies examine early unrestricted motion and weight bearing (immediate versus 2-4 weeks; immediate versus 5-6 weeks) and early initiation open kinetic chain quadriceps exercise (limited range [90 – 40o] starting at 4 versus 12 weeks in isolation, and all reported similar patient outcomes with early versus late initiation of these activities.21,35, 47, 54 Early, accelerated protocols may include early weight bearing, range of motion, and strengthening including the addition of open kinetic chain exercises at six weeks.

Potential Benefits of Implementation
The benefit of early accelerated rehabilitation is that patients may be able to return to full, unrestricted activity sooner.

Potential Harms of Implementation
The impact on long term outcomes (e.g. progression of osteoarthritis) of the timing and intensity of rehabilitation programs is currently unknown.  For example, Beynnon (2005) noted that biomarkers of articular cartilage metabolism remained elevated well after the completion of both rehabilitation programs and the time interval that most individuals will return to full, unrestricted physical activity.  Cleavage of Type II collagen returned to normal after 12 months, while synthesis of Type II collagen and turnover of aggrecan approached normal but remained at 24 months.

Future Research
Current evidence is limited to two studies that have followed patients out 2 years post-surgery.  Additional research on long term outcomes of early, accelerated, and non-accelerated rehabilitation and return to activity on long term physical activity, biomechanical deficits and incidence of complications (e.g. onset of OA) are needed. Future Research should also address the influence of accelerated rehabilitation on graft integrity and the integrity of articular cartilage. This includes the use of imaging (MRI) to assess the effects of accelerated or delayed rehabilitation on graft healing and maturation and on the integrity of articular cartilage.
  1. (14) Beynnon BD, Johnson RJ, Naud S et al. Accelerated versus nonaccelerated rehabilitation after anterior cruciate ligament reconstruction: a prospective, randomized, double-blind investigation evaluating knee joint laxity using roentgen stereophotogrammetric analysis. Am J Sports Med 2011;39:2536-2548.
  2. (15) Beynnon BD, Uh BS, Johnson RJ et al. Rehabilitation after anterior cruciate ligament reconstruction: a prospective, randomized, double-blind comparison of programs administered over 2 different time intervals. Am J Sports Med 2005;33:347-359.
  3. (21) Christensen JC, Goldfine LR, West HS. The Effects of Early Aggressive Rehabilitation on Outcomes after Anterior Cruciate Ligament Reconstruction Using Autologous Hamstring Tendon: A Randomized Clinical Trial. J Sport Rehabil 2013.
  4. (35) Fukuda TY, Fingerhut D, Moreira VC et al. Open kinetic chain exercises in a restricted range of motion after anterior cruciate ligament reconstruction: a randomized controlled clinical trial. Am J Sports Med 2013;41:788-794.
  5. (47) Heijne A, Werner S. Early versus late start of open kinetic chain quadriceps exercises after ACL reconstruction with patellar tendon or hamstring grafts: a prospective randomized outcome study. Knee Surg Sports Traumatol Arthrosc 2007;15:402-414.
  6. (54) Isberg J, Faxen E, Brandsson S, Eriksson BI, Karrholm J, Karlsson J. Early active extension after anterior cruciate ligament reconstruction does not result in increased laxity of the knee. Knee Surg Sports Traumatol Arthrosc 2006;14:1108-1115.