Nathan Harward

Background: The anterior cruciate ligament (ACL) is the chief ligament within the knee joint, responsible for anterior and rotational stability¹. Most ACL ruptures are sports-related, and ligament reconstruction is generally preferred over attempted repair, even if the tear is partial². Approximately 200,000 ACL reconstructions (ACLR) are performed each year in the US, and the number is growing³. Autografts using quadriceps, hamstring, or patellar tendons are considered “gold standard” for graft materials⁴. ACLR has improved dramatically in recent years, but only 87% of patients report their knee feels stable, 70% return to sport, 13% will need non-ACL surgery on the same knee, and 7% will need revision ACLR⁵. As the prevalence of ACLR rises, internal bracing (IB) has become a prominent research topic as a method to improve patient-reported-outcome-measures (PROMs).

Research Methods: PubMed was searched for the terms “ACL Reconstruction”, “ACL Internal Brace”, and “ACL Graft Augmentation” to perform a literature review of articles published within the last five years.

Results: For various reasons, a surgeon may not feel the graft available is adequate for stable reconstruction and will implement IB within ACLR, suture tape being the most common material used for IB^1,6. It is thought that IB acts as a secondary stabilizer to facilitate healing and graft integration, while allowing for earlier rehabilitation without increasing graft failure risk⁷. Early clinical studies show no significant difference in PROMs between ACLR with vs without IB^1,8,9. Research also suggests IB may lead to lower revision rates (1% vs 7%) and decreased ACL-laxity at 6 months^8,9. Biomechanical tests using porcine models show a 33% decrease in cyclic displacement, 22% increase in ultimate strength, and 25% increase in yield strength, with no significant increase in graft stiffness¹⁰. There is evidence of a “safety-belt” effect, where the IB exhibits minimal load-sharing until higher loads are applied; and little stress-shielding of the graft by the suture tape IB is observed^11,12.

Conclusions: Current ACLR methods are effective but leave much to be desired in terms of clinical outcomes and risk of revision ALCR^3,4,5. IB is successfully used in reconstruction of other ligaments, and it is time that this tactic is implemented within ACLR¹³. Biomechanical testing elucidates improved mechanical properties with IB-augmented grafts^10,11,12. Clinical research suggests IB may facilitate earlier rehabilitation and reduce risk of repeat injury without sacrificing PROMs^1,7,8,9,13. While further research is needed prior to mainstream adoption by orthopedic surgeons, IB shows great promise in improvement of current ACLR procedures.

Works Cited:

1. Daniel AV, Wijdicks CA, Smith PA. Reduced incidence of revision anterior cruciate ligament reconstruction with internal brace augmentation. Orthop J Sports Med. 2023;11(7):23259671231178026. Published 2023 Jul 24. doi:10.1177/23259671231178026.
2. Wilson WT, Hopper GP, Banger MS, Blyth MJG, Riches PE, MacKay GM. Anterior cruciate ligament repair with internal brace augmentation: a systematic review. Knee. 2022;35:192-200. doi:10.1016/j.knee.2022.03.009.
3. Paschos NK, Howell SM. Anterior cruciate ligament reconstruction: principles of treatment. EFORT Open Rev. 2017;1(11):398-408. Published 2017 Mar 13. doi:10.1302/2058-5241.1.160032.
4. Migliorini F, Torsiello E, Trivellas A, et al. Bone-patellar tendon-bone versus two- and four-strand hamstring tendon autografts for ACL reconstruction in young adults: a Bayesian network meta-analysis. Sci Rep. 2023;13:6883. doi:10.1038/s41598-023-33899-1.
5. Randsborg PH, Cepeda N, Adamec D, Rodeo SA, Ranawat A, Pearle AD. Patient-reported outcome, return to sport, and revision rates 7-9 years after anterior cruciate ligament reconstruction: results from a cohort of 2042 patients. Am J Sports Med. 2022;50(2):423-432. doi:10.1177/03635465211060333.
6. Huntington L, Griffith A, Spiers L, et al. Suture-tape augmentation of anterior cruciate ligament reconstruction: a prospective, randomized controlled trial (STACLR). Trials. 2023;24:224. doi:10.1186/s13063-023-07127-0.
7. Benson DM, Hopper GP, Wilson WT, Mackay GM. Anterior cruciate ligament reconstruction using bone–patellar tendon–bone autograft with suture tape augmentation. Arthrosc Tech. 2021;10(2):e249-e255. doi:10.1016/j.eats.2020.10.009.
8. Daniel AV, Sheth CD, Shubert DJ, Smith PA. Primary anterior cruciate ligament reconstruction with suture tape augmentation: a case series of 252 patients. J Knee Surg. 2024;37(5):381-390. doi:10.1055/a-2129-8893.
9. von Essen C, Sarakatsianos V, Cristiani R, Stålman A. Suture tape reinforcement of hamstring tendon graft reduces postoperative knee laxity after primary ACL reconstruction. J Exp Orthop. 2022;9:20. doi:10.1186/s40634-022-00454-2.
10. Wicks ED, Stack J, Rezaie N, Zeini IM, Osbahr DC. Biomechanical evaluation of suture tape internal brace reinforcement of soft tissue allografts for ACL reconstruction using a porcine model. Orthop J Sports Med. 2022;10(5). doi:10.1177/23259671221091252.
11. Mackenzie EA, Huntington LS, Tulloch S. Suture tape augmentation of anterior cruciate ligament reconstruction increases biomechanical stability: a scoping review of biomechanical, animal, and clinical studies. Arthroscopy. doi:10.1016/j.arthro.2021.12.036.
12. Bachmaier S, Smith PA, Bley J, Wijdicks CA. Independent suture tape reinforcement of small and standard diameter grafts for anterior cruciate ligament reconstruction: a biomechanical full construct model. Arthroscopy. doi:10.1016/j.arthro.2017.10.037.
13. Nishimura A, Nakazora S, Senga Y, et al. Arthroscopic Internal Brace Augmentation With Arthroscopic Modified Broström Operation for Chronic Ankle Instability. Arthrosc Tech. 2021;10(4):e995-e1000. Published 2021 Mar 8. doi:10.1016/j.eats.2020.11.021