Platelet-rich plasma
Use of platelet-rich plasma (and/or related growth factors) may provide a suitable milieu for ACL healing.[93]Murray MM, Spindler KP, Devin C, et al. Use of a collagen-platelet rich plasma scaffold to stimulate healing of a central defect in the canine ACL. J Orthop Res. 2006;24:820-30.
http://www.ncbi.nlm.nih.gov/pubmed/16555312?tool=bestpractice.com
This approach may enable primary ACL repair to achieve good functional outcome, with much less morbidity than conventional reconstruction. To date, research is encouraging but the majority of studies have been carried out in animal models. It is likely that if this treatment is shown to work, it would be given in combination with other treatments. Some human studies have suggested that the addition of platelet concentrates to ACL reconstruction may have a beneficial effect on graft maturation, but there is considerable variability between studies regarding the level of benefit.[94]Vavken P, Sadoghi P, Murray MM. The effect of platelet concentrates on graft maturation and graft-bone interface healing in anterior cruciate ligament reconstruction in human patients: a systematic review of controlled trials. Arthroscopy. 2011;27:1573-83.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206130
http://www.ncbi.nlm.nih.gov/pubmed/21862277?tool=bestpractice.com
Platelet concentrates do not appear have a significant beneficial effect on graft-bone interface healing following ACL reconstruction, and no significant benefit in terms of clinical outcomes.[94]Vavken P, Sadoghi P, Murray MM. The effect of platelet concentrates on graft maturation and graft-bone interface healing in anterior cruciate ligament reconstruction in human patients: a systematic review of controlled trials. Arthroscopy. 2011;27:1573-83.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206130
http://www.ncbi.nlm.nih.gov/pubmed/21862277?tool=bestpractice.com
[95]Moraes VY, Lenza M, Tamaoki MJ, et al. Platelet-rich therapies for musculoskeletal soft tissue injuries. Cochrane Database Syst Rev. 2014;(4):CD010071.
http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010071.pub3/full
http://www.ncbi.nlm.nih.gov/pubmed/24782334?tool=bestpractice.com
Growth factors
Use of growth factors may provide a suitable milieu for ACL healing.[96]Meaney Murray M, Rice K, Wright RJ, et al. The effect of selected growth factors on human anterior cruciate ligament cell interactions with a three-dimensional collagen-GAG scaffold. J Orthop Res. 2003;21:238-44.
http://www.ncbi.nlm.nih.gov/pubmed/12568954?tool=bestpractice.com
[97]Murray MM, Bennett R, Zhang X, et al. Cell outgrowth from the human ACL in vitro: regional variation and response to TGF-beta1. J Orthop Res. 2002;20:875-80.
http://www.ncbi.nlm.nih.gov/pubmed/12168681?tool=bestpractice.com
[98]Kondo E, Yasuda K, Yamanaka M, et al. Effects of administration of exogenous growth factors on biomechanical properties of the elongation-type anterior cruciate ligament injury with partial laceration. Am J Sports Med. 2005;33:188-96.
http://www.ncbi.nlm.nih.gov/pubmed/15701604?tool=bestpractice.com
Gene therapy
Use of gene therapy may provide a suitable milieu for ACL healing. This approach may enable primary ACL repair to achieve good functional outcome, with much less morbidity than conventional reconstruction. To date, research is encouraging but limited to animal models.
Collagen scaffolds
Use of collagen scaffolds may provide a suitable milieu for ACL healing. Early results from a phase I trial of bridge-enhanced ACL repair have shown encouraging results, and participants are currently being followed to monitor longer term outcomes.[99]Murray MM, Fleming BC, Badger GJ, et al. Bridge-Enhanced Anterior Cruciate Ligament Repair Is Not Inferior to Autograft Anterior Cruciate Ligament Reconstruction at 2 Years: Results of a Prospective Randomized Clinical Trial. Am J Sports Med. 2020 May;48(6):1305-15.
https://www.doi.org/10.1177/0363546520913532
http://www.ncbi.nlm.nih.gov/pubmed/32298131?tool=bestpractice.com
Novel arthroscopic suture anchors
Some investigators are looking at other forms of direct repair of torn ACLs, with improved surgical technique and use of newer suture anchors.[100]DiFelice GS, Villegas C, Taylor S. Anterior cruciate ligament preservation: early results of a novel arthroscopic technique for suture anchor primary anterior cruciate ligament repair. Arthroscopy. 2015;31:2162-71.
http://www.ncbi.nlm.nih.gov/pubmed/26542201?tool=bestpractice.com
Tranexamic acid before and during surgical reconstruction
One clinical trial showed that intravenous administration of tranexamic acid in the pre- and peri-operative period of arthroscopic anterior cruciate ligament reconstruction surgery significantly decreased post-operative pain, hemarthrosis, and the need for joint aspiration with no increase in DVT or other adverse outcomes.[101]Karaaslan F, Karaoğlu S, Yurdakul E. Reducing intra-articular hemarthrosis after arthroscopic anterior cruciate ligament reconstruction by the administration of intravenous tranexamic acid: a prospective, randomized controlled trial. Am J Sports Med. 2015;43:2720-6.
http://www.ncbi.nlm.nih.gov/pubmed/26337246?tool=bestpractice.com
Bone morphogenetic proteins (BMPs)
Use of BMPs has shown promise in stimulating bone healing at graft tunnel sites, and may also enhance fixation of tendon grafts.
Hyperbaric oxygen
Use of hyperbaric oxygen may also hold promise as an adjunct treatment for ACL healing.
Grafts
The Ligament Augmentation and Reconstruction System (LARS) is a synthetically-produced ligament scaffold, which is designed to encourage tissue growth and provide support to the repairing ligament. In the UK, The National Institute for Health and Care Excellence (NICE) describe LARS as an alternative surgical approach, after autograft or allograft repair techniques have been considered.[102]National Institute for Health and Care Excellence. LARS for reconstructing damaged intra-articular cruciate knee ligaments. May 2015 [internet publication].
https://www.nice.org.uk/advice/mib30
Prolotherapy
Prolotherapy (injecting dextrose or similar solutions into injured tissue to theoretically stimulate healing) has been advocated as a possible treatment for ACL injury, but evidence is lacking.