This entry is part 1 of 9 in the series Anterior Cruciate Ligament Injuries

Anterior Cruciate Ligament Injuries

Michael D’Amato, MD, and Bernard R. Bach, Jr., MD


As our understanding of the biology and biomechanics regarding the knee and graft reconstruction techniques has improved, rehabilitation after ACL injury has also changed. In the 1970s, ACL reconstructions were done through large arthrotomies, using extra-articular reconstructions, and patients were immobilized in casts for long periods after surgery. In the 1980s, arthroscopic techniques led to intra-articular reconstructions and eliminated the need for a large arthrotomy, which allowed the use of “accelerated” rehabilitation protocols that focused on early motion. In the 1990s, the concept of “accelerated” rehabilitation evolved in an effort to return athletes to the playing field quicker than ever. With this emphasis on quick return to sports, issues regarding open– and closed–kinetic chain exercises and graft strain have come to the forefront, as has the role of postoperative and functional bracing. In addition, the value of preoperative rehabilitation to prevent postoperative complications has been recognized.

Rehabilitation Rationale

Nonoperative treatment of the ACL-deficient knee may be indicated in older, sedentary people, but in active people, young or old, the ACL-deficient knee has a high incidence of instability, often leading to meniscal tears, articular injury, and subsequent degenerative changes in the knee. Adequate knee function may be maintained in the short term, particularly after hamstring strengthening programs, but this is unpredictable and function is usually below the preinjury level.

Surgical reconstruction of the ACL can now predictably restore the stability of the knee, and rehabilitation is focused on restoring motion and strength while maintaining knee stability by protecting the healing graft and donor site. Aggressive “accelerated” rehabilitation programs have been made possible through advances in graft materials and graft fixation methods and an improved understanding of graft biomechanics and the effects of various exercises and activities on graft strains. Whereas these protocols may ultimately prove to be safe and appropriate, they must be viewed cautiously until continued research into graft healing further delineates the limits to which rehabilitation after ACL reconstruction can be “accelerated.”

Protocols for rehabilitation after ACL reconstruction follow several basic guiding principles.

  • Achieving full ROM and reduction of inflammation and swelling before surgery to avoid arthrofibrosis.
  • Early weight-bearing and ROM, with emphasis on obtaining early full extension.
  • Early initiation of quadriceps and hamstring activity.
  • Efforts to control swelling and pain to limit muscular inhibition and atrophy.
  • Appropriate use of open– and closed–kinetic chain exercises, avoiding early open-chain exercises that may shear or tear the weak immature ACL graft (see section on open- and closed-kinetic chain exercises, following).
  • Comprehensive lower extremity muscle stretching and strengthening and conditioning.
  • Neuromuscular and proprioception retraining.
  • Functional training.
  • Cardiovascular training.
  • Stepped progression based on achievement of therapeutic goals.
Series NavigationBiomechanics of ACL Injuries»

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