Why doesn't Anterior Cruciate Ligament (ACL) surgery affect the gracilis and hamstring muscles?

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Last updated: May 21, 2025View editorial policy

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From the Guidelines

ACL surgery does not necessarily affect the gracilis and hamstrings when alternative graft sources are used for reconstruction, as highlighted in recent clinical guidelines such as the Aspetar clinical practice guideline on rehabilitation after anterior cruciate ligament reconstruction 1. The decision to spare the gracilis and hamstrings during ACL surgery depends on various factors, including the patient's activity level, age, and surgeon preference.

  • The gracilis and hamstrings are commonly used as autografts for ACL reconstruction, but alternative graft options like patellar tendon, quadriceps tendon, or allograft tissue from donors can be used instead, allowing these muscles to remain intact and functional.
  • Preserving the gracilis and hamstrings is beneficial for maintaining knee stability and function, as they play important roles in hip adduction, knee flexion, and providing posterior stability to the knee joint.
  • The use of alternative graft sources can potentially result in better post-operative strength and reduced recovery time for certain patients, which is in line with the goals of rehabilitation after ACL reconstruction, as outlined in the Aspetar clinical practice guideline 1.
  • The guideline emphasizes the importance of minimizing the risk of reinjury and optimizing the patient's return to sport, which can be influenced by the choice of graft source and the preservation of key muscles like the gracilis and hamstrings.

From the Research

ACL Surgery and Gracilis/Hamstrings

  • The gracilis and hamstrings are not directly affected by ACL surgery in terms of their function, as the surgery focuses on reconstructing the ACL using grafts such as patellar tendon or hamstring tendons 2.
  • However, the harvesting of hamstring tendons, including the gracilis, for use as grafts in ACL reconstruction can lead to decreased hamstring strength and active knee flexion angle loss 3.
  • The study by 3 found that the addition of gracilis harvest to an isolated semitendinosus harvest for ACL reconstruction results in statistically significant, but likely not clinically relevant differences in isokinetic and isometric hamstring strength.
  • Another study 2 described a combined intra- and extra-articular arthroscopic ACL reconstruction using hamstring tendons, which includes some original steps, and found highly satisfactory results with no major complications.
  • The preservation of the gracilis tendon during ACL reconstruction may be beneficial in maintaining hamstring strength, but the current evidence suggests that the differences in outcomes between gracilis preservation and harvest are not clinically significant 3.

Rehabilitation and Outcomes

  • Rehabilitation protocols after ACL repair techniques are not well established, and more research is needed to address how physical therapies must adapt to these innovative repair techniques 4.
  • The study by 4 recommends that physical therapists understand the differences among the various ACL surgery techniques and work with surgeons to develop a rehabilitation protocol for their mutual patients.
  • The outcomes of ACL surgery can be optimized by considering factors such as graft choice, surgical technique, and rehabilitation protocol 5.
  • The use of autograft reconstruction is not the only reasonable option for ACL surgery, and alternative treatments such as tissue-engineered approaches are being developed to minimize patient morbidity and improve outcomes 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Arthroscopic intra- and extra-articular anterior cruciate ligament reconstruction with gracilis and semitendinosus tendons.

Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 1998

Research

Does Gracilis Preservation Matter in Anterior Cruciate Ligament Reconstruction? A Systematic Review.

Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association, 2016

Research

Optimizing outcomes of ACL surgery-Is autograft reconstruction the only reasonable option?

Journal of orthopaedic research : official publication of the Orthopaedic Research Society, 2021

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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