Abstract
Background: Anterior cruciate ligament (ACL) grafts that are placed for reconstruction are subject to complex forces. Current “anatomic” ACL reconstruction techniques may result in greater in situ graft forces. The biological effect of changing magnitudes of ACL graft force on graft-tunnel osseointegration is not well understood. Purpose: The research objective is to determine how mechanical force on the ACL graft during knee motion affects tendon healing in the tunnel. Study Design: Controlled laboratory study. Methods: Male rats (N = 120) underwent unilateral ACL reconstruction with a soft tissue flexor tendon autograft. ACL graft force was modulated by different femoral tunnel positions at the time of surgery to create different graft force patterns with knee motion. External fixators were used to eliminate graft load during cage activity. A custom knee flexion device was used to deliver graft load through controlled daily knee motion. Graft-tunnel healing was then assessed via biomechanical, micro–computed tomography, and histological analyses. Results: ACL graft-tunnel healing was sensitive to dynamic changes in graft forces with postoperative knee motion. High ACL graft force with joint motion resulted in early inferior ACL graft load to failure as compared with knees that had low-force ACL grafts and joint motion and knees that were immobilized (mean ± SD: 5.50 ± 2.30 N vs 9.91 ± 3.54 N [P =.013] and 10.90 ± 2.8 N [P =.001], respectively). Greater femoral bone volume fraction was seen in immobilized knees and knees with low-force ACL grafts when compared with high-force ACL grafts at 3 and 6 weeks. Conclusion: The authors were able to demonstrate that ACL graft-tunnel incorporation is sensitive to dynamic changes in ACL graft force with joint motion. Early high forces on the ACL graft appear to impair graft-tunnel osseointegration. Clinical Relevance: Current “anatomic” techniques of ACL reconstruction may result in greater graft excursion and force with knee motion. Our results suggest that the postoperative rehabilitation regimen may need to be modified during the early phase of healing to protect the reconstruction.
| Original language | English |
|---|---|
| Pages (from-to) | 915-923 |
| Number of pages | 9 |
| Journal | American Journal of Sports Medicine |
| Volume | 46 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - Mar 1 2018 |
Bibliographical note
Publisher Copyright:© 2018, © 2018 The Author(s).
Funding
*Address correspondence to Richard Ma, MD, Missouri Orthopaedic Institute, Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, 1100 Virginia Ave, DC953.00, Columbia, MO USA (email: MaRicha@health.missouri.edu). yMissouri Orthopaedic Institute, Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri, USA. zSports Medicine and Shoulder Service, Tissue Engineering, Regeneration, and Repair Program, Hospital for Special Surgery, New York, New York, USA. Presented at the 40th annual meeting of the AOSSM, Seattle, Washington, July 2014. One or more of the authors has declared the following potential conflict of interest or source of funding: S.A.R. receives royalties from Zimmer Biomet. This study was financially supported by the Orthopaedic Research Education Foundation and the Hospital for Special Surgery’s Institute for Sports Medicine Research.
| Funders | Funder number |
|---|---|
| Orthopaedic Research and Education Foundation |
ASJC Scopus Subject Areas
- Physical Therapy, Sports Therapy and Rehabilitation
- Orthopedics and Sports Medicine