Why the Idea That an ACL Can Heal Itself Is Surgical Sacrilege

As I have written before, if modern surgical sports medicine has one sacred cow, it’s ACL reconstruction. That’s why the fact that we have dozens of MRI examples of non-healing torn ACLs improving with our Perc-ACLR procedure has raised eyebrows. Now a new study that shows that some ACLs can heal themselves has apparently angered some surgeons. Let’s dig in.


The anterior cruciate ligament (ACL) is a critical structure for maintaining the stability of the knee. Rupture of the ACL is a common injury, particularly among athletes, resulting in decreased quality of life and the risk of further injuries. One common treatment for this condition is ACL reconstruction surgery; however, recent research raises questions about the cost-effectiveness of this procedure.

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Lots of ACL Surgeries

The precise number of ACL injuries in the United States is not exact, but estimates suggest there are between 60,000 and 200,000 such injuries annually [1]. There were 283,810 ACL reconstructions between 2002 and 2014. The overall rate of ACL reconstruction increased 22% over this period, from 61.4 per 100,000 person-years in 2002 to 74.6 per 100,000 person-years in 2014. The rate was relatively stable for isolated ACL reconstruction but showed a substantial increase for ACL reconstruction with concomitant meniscal surgery, particularly among children and adolescents.

The Cost Effectiveness of ACL Reconstruction Surgery

Studies focusing on the cost-effectiveness of ACL reconstruction surgeries suggest that this approach may not be the most cost-efficient treatment for all patients. One such study conducted a cost-utility analysis for two commonly used treatment strategies after ACL rupture: early ACL reconstruction and rehabilitation versus late reconstruction after rehab only in cases of persistent instability and inability to return to sports [2][3].

The study included a total of 167 patients, 85 of whom underwent early ACL reconstruction, while 82 underwent rehabilitation followed by optional reconstruction if needed. It was found that from a healthcare perspective, the cost to gain a quality-adjusted life year (QALY) when performing early surgery compared with rehabilitation plus an optional reconstruction was 48,460 €. From a societal perspective, the cost was even higher, at 78,179 €. Given the maximum willingness to pay of 20,000 €/QALY, routine early ACL reconstruction was not considered cost-effective as compared with rehabilitation followed by optional reconstruction.

Does ACL Reconstruction Work?

Based on the high-level research, is reconstructing the ACL surgically an effective treatment for most patients with ACL tears? Not really.

First, surgeons often cite the need for ACL reconstruction as protecting the patient against the eventual onset of osteoarthritis. However, this doesn’t happen as just as many ACL reconstructed knees get arthritis as those that remain unoperated [4-6]. We also know that waiting to reconstruct knees results in about half of the patients who never need or want the surgery [7]. Finally, research has shown that early reconstruction is not superior to waiting and entering patients into physical therapy and then only operating on selected patients with continued disability [4].

So if we know all this about this procedure, why is the early reconstruction of the ACL still the surgical standard?

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The Final Nail in the ACL Reconstruction Coffin?

The reason surgeons had been so eager to reconstruct the ACL surgically is based on the medical tradition that the ligament has very little natural ability to heal. However, now that concept has been blown out of the water by a study published in the British Journal of Sports Medicine. In the new study, 80 consecutive patients with complete ACL tears who were, on average, 26 years old were placed into a brace and given rehab [8]. 90% of the ACLs showed evidence of healing on a 3-month MRI. About half of those had evidence of good healing, and these patients were more functional.

Isn’t This Good News?

While this would seem to be fantastic data that means that we can start reducing the exposure of patients to a surgical procedure, surgeons quoted by the Washington Post weren’t so happy about it [9]:

“Some experts scoff, though. “It does not seem plausible” that ACLs heal themselves, said Timothy Hewett, a professor of orthopedic surgery at the Marshall University Joan C. Edwards School of Medicine, who’s co-written hundreds of peer-reviewed articles, many about ACL injuries.

The MRI scans that appear to show the raw ends of the torn ACLs rejoining are probably picking up scarring or being misread, Hewett said. “The term ‘healing’ should not be used by the authors in this context,” he said.

At a recent international conference of surgeons and knee researchers in Boston, Hewett continued, attendees discussed — and to some extent, dismissed — the new study. “One world-renowned researcher could be easily overheard stating, ‘That is B.S.,’” he said.”

Why Would We Want to Reduce Exposure to a Surgery That’s Not Cost-Effective?

ACL surgery has side effects and complications. These include:

  • Chronic stiffness (1%–4%)
  • Septic arthritis (0.1%–1.7%)
  • Deep venous thrombosis (0.53%–14.9%)
  • Re-rupture of the graft (3.2%–11.1%) [10,11].

Shouldn’t Our Job Now Be to Facilitate ACL Healing?

Much of Scandinavia has already made the switch to rehab and late ACL reconstruction only for patients who can’t return to sports. At Regenexx, we’ve been using this approach for more than a decade and then inserting another step before surgery. We give the patient that first three months to heal, and if the patient can’t return to sports and still has evidence of an ACL tear on MRI, then we use our Perc-ACL procedure which precisely injects high-dose, autologous bone marrow concentrate into the torn ligament. Follow-up MRIs with this approach have shown high rates of healing on follow-up MRI and return to sports, with fewer retears than surgery [12-14]. The few patients who don’t heal with this interventional orthobiologics approach are sent for a BEAR implant or surgical reconstruction.

Think about how much money insurers could save if they used the Regenexx approach to ACL tears. Based on a recent QALY analysis I presented at the TOBI conference last month in Las Vegas, we now understand the magnitude of these cost savings. In addition, the complication rate and number of surgical injuries would drop substantially.

The upshot? Some surgeons don’t like this new research showing that the job of a physician when faced with an ACL tear should be to facilitate healing. However, as more cost analyses are performed, I suspect that the evidence will become overwhelming that early ACL reconstruction is not the way to go, and the practice needs to be relegated to the dustbin of medical history.



  1. Herzog MM, Marshall SW, Lund JL, Pate V, Mack CD, Spang JT. Trends in Incidence of ACL Reconstruction and Concomitant Procedures Among Commercially Insured Individuals in the United States, 2002-2014. Sports Health. 2018 Nov/Dec;10(6):523-531. doi: 10.1177/1941738118803616. PMID: 30355175; PMCID: PMC6204641.
  2. Eggerding V, Reijman M, Meuffels DE, et alACL reconstruction for all is not cost-effective after acute ACL ruptureBritish Journal of Sports Medicine 2022;56:24-28.
  3. Eggerding V, Reijman M, Meuffels DE, van Es E, van Arkel E, van den Brand I, van Linge J, Zijl J, Bierma-Zeinstra SM, Koopmanschap M. ACL reconstruction for all is not cost-effective after acute ACL rupture. Br J Sports Med. 2022 Jan;56(1):24-28. doi: 10.1136/bjsports-2020-102564. Epub 2021 Mar 18. PMID: 33737313; PMCID: PMC8685656.
  4. Frobell RB, Roos EM, Roos HP, et al.. A randomized trial of treatment for acute anterior cruciate ligament tears. N Engl J Med 2010;363:331–42. 10.1056/NEJMoa0907797
  5. van Meer BL, Oei EHG, Meuffels DE, et al.. Degenerative changes in the knee 2 years after anterior cruciate ligament rupture and related risk factors: a prospective observational follow-up study. Am J Sports Med 2016;44:1524–33. 10.1177/0363546516631936
  6. van Yperen DT, Meuffels DE, Reijman M. Twenty-Year follow-up study comparing operative versus Nonoperative treatment of anterior cruciate ligament ruptures in high-level athletes: response. Am J Sports Med 2018;46:NP57–8. 10.1177/0363546518788317
  7. Reijman M, Eggerding V, van Es E, van Arkel E, van den Brand I, van Linge J, Zijl J, Waarsing E, Bierma-Zeinstra S, Meuffels D. Early surgical reconstruction versus rehabilitation with elective delayed reconstruction for patients with anterior cruciate ligament rupture: COMPARE randomised controlled trial. BMJ. 2021 Mar 9;372:n375. doi: 10.1136/bmj.n375. PMID: 33687926; PMCID: PMC7941216.
  8. Filbay SR, Dowsett M, Chaker Jomaa M, et alHealing of acute anterior cruciate ligament rupture on MRI and outcomes following non-surgical management with the Cross Bracing ProtocolBritish Journal of Sports Medicine Published Online First: 14 June 2023. doi: 10.1136/bjsports-2023-106931
  9. Washington Post. A torn ACL can heal itself, new study shows. Surgeons disagree. https://www.washingtonpost.com/wellness/2023/06/28/torn-acl-healing-therapy-surgery/ Accessed 7/8/23
  10. Magnussen RA, Meschbach NT, Kaeding CC, et al.. Acl graft and contralateral ACL tear risk within ten years following reconstruction: a systematic review. JBJS Rev 2015;3. 10.2106/JBJS.RVW.N.00052.
  11. Nadarajah V, Roach R, Ganta A, et al.. Primary anterior cruciate ligament reconstruction: perioperative considerations and complications. Phys Sportsmed 2017;45:1–13. 10.1080/00913847.2017.1294012
  13. Centeno C, Markle J, Dodson E, Stemper I, Williams C, Hyzy M, Ichim T, Freeman M. Symptomatic anterior cruciate ligament tears treated with percutaneous injection of autologous bone marrow concentrate and platelet products: a non-controlled registry study. J Transl Med. 2018 Sep 3;16(1):246. doi: 10.1186/s12967-018-1623-3. PMID: 30176875; PMCID: PMC6122476.
  14. Centeno CJ, Pitts J, Al-Sayegh H, Freeman MD. Anterior cruciate ligament tears treated with percutaneous injection of autologous bone marrow nucleated cells: a case series. J Pain Res. 2015 Jul 31;8:437-47. doi: 10.2147/JPR.S86244. PMID: 26261424; PMCID: PMC4527573.
Chris Centeno, MD is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. View Profile

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NOTE: This blog post provides general information to help the reader better understand regenerative medicine, musculoskeletal health, and related subjects. All content provided in this blog, website, or any linked materials, including text, graphics, images, patient profiles, outcomes, and information, are not intended and should not be considered or used as a substitute for medical advice, diagnosis, or treatment. Please always consult with a professional and certified healthcare provider to discuss if a treatment is right for you.

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