Medial Collateral Ligament Knee Injury

Your doctor or MRI tells you that you have a partial tear of the medial collateral ligament (MCL)  of the knee. What are your treatment options?

Grade 1 MCL tear

Grade 2 MCL tear

The MCL is a strong ligament and doctors have confirmed the resilience of the MCL in their published findings. What they noted, like many doctors who prefer to utilize non-surgical options, is that the most frequent MCL injury, near its femoral attachment, can be healed spontaneously without surgical intervention.

Understanding the MCL

Medial Collateral Ligament Knee Injury

The medial collateral ligament (MCL), a vital static stabilizer of the knee, is the most commonly injured ligamentous structure of this joint. The term “MCL” in fact comprises several ligaments, including superficial and deep layers. The deep MCL (medial capsular ligament) is often the first layer to be injured by stresses created by the sudden change of direction. It is attached to the medial meniscus, and consequently, a meniscal tear may accompany these injuries. The MCL has greater healing potential than the ACL because of its greater vascularity, as well as its substantial capacity to increase vascularity (blood flow bringing healing factors) upon injury.

Inner knee pain and instability

In our nearly three decades of medical research and clinical assessment of thousands of patients, the outstanding understanding of knee instability is that one damaged structure in the knee affects the entire knee joint stability, and knee joint instability affects all the structures of the knee. A damaged ligament is stressing the other ligaments and may be providing wear and tear on the cartilage and meniscus. This may explain why a knee with a “fully healed” MCL remains unstable.

A June 2021 paper published in the journal Orthopedic Reviews (1) wrote: “The medial side of the knee is comprised of ligaments, myotendinous (or muscle-tendon-enthesis complex – where the muscle and tendon meet and where joint and muscle forces work together. As would be expected, the forces on these small bands of tissues make this a common location for strain (tear) injuries.)

The superficial medial collateral ligament is its core structure (of the inner knee). Still, all elements of the medial side have load-sharing relationships, leading to a cascade of events in the scenario of insufficiency of any of them. Understanding the medial soft tissue structures as part of a unit is of utmost importance because the most common ligaments damaged in knee injuries belong to it. Surprisingly, there is a lack of high-level evidence published around the issue, and most studies focus on the superficial medial collateral ligament, overlooking the complexity of these injuries.”

To answer the question again, why does a knee with a “fully healed” MCL still have knee instability? Doctors are overlooking the complexity of these injuries.

There is no one standard treatment for MCL injuries, but rather a range of practices from conservative to surgical measures.

A more unstable knee or a more extensively damaged MCL may still respond to conservative, non-surgical care. A study from doctors at the Department of Orthopaedics, University of Toledo Medical Center in the  Journal of Orthopaedics, (2) gives an introduction to the treatment problems of the knee’s medial collateral ligament:

It is fair to say that if you go into a surgeon’s office with a documented MRI finding, the above is an accurate assessment of what you will hear. You may need surgery, you may not. We will talk about the grade 3 MCL injury, a completely torn MCL below.

A partial MCL tear is capable of healing itself and even before complete healing occurs is sufficient enough to keep the knee stable

In incidents where the MCL is injured in isolation, university researchers writing in the Journal of Engineering in Medicine(3) found the healing characteristics of the MCL to be remarkable in their inconsistency, BUT, did find that the MCL could spontaneously heal. Listen to the researchers:

The purpose of this study was to observe how the MCL heals under different injury conditions. That corresponded to:

The researchers found that at the medium or middle stage of healing, the MCK exhibited characteristics of a fully healed MCL.

Does an MCL really heal on its own?

The answer is yes, the question is, what type of healing occurs? In a landmark study from 1983, cited in more recent studies on MCL stability, doctors examined scar formation in MCL healing.

In this study in the American Journal of Sports Medicine(4) researchers studied injured MCLs in rabbits and discovered that true ligament healing does not occur. Rather, a ligament scar develops that is in many ways inferior to true ligament tissue. The researchers were curious about the healing of untreated ligaments: is there true ligament regeneration or is there scar healing only? How fast do these ligaments heal? Is healing complete when left untreated?

This study showed a number of things:

The bottom line from this study is that ligaments heal by scar unless treated. Ligaments that heal with scar are significantly inferior in strength to normal ligaments and weak ligaments lead to ligament laxity, joint instability, and osteoarthritis.

MCL treatment options – Surgical

As mentioned above, knee instability by way of MCL weakness may be a cause of the desire to have surgery. A March 2022 paper in the Clinical Journal of Sports Medicine (5) suggests surgical debridement procedures may be effective. The authors write: “Most grade I and II injuries respond to conservative management, but symptoms persist in some patients. In these cases, treatment options are limited. ” In this paper, a case is present of successful treatment of chronic grade II MCL sprain with percutaneous ultrasonic debridement (in simplest terms a power washing of the ligament to remove dead, weak components). The case for debridement was also suggested in a March 2023 paper (6) where two patients who developed calcified or ossified lesions of the MCL.

MCL treatment options – Non-Surgical

Bone marrow-derived stem cells and lipoaspirate-derived stem cells

In our clinical experience, we have seen bone marrow-derived stem cells and lipoaspirate-derived stem cells provide satisfactory results for patients. However, the effectiveness of treatment is based on the proper candidacy of the patient and a realistic goal of treatment. These treatments do not work for everyone and there is great variation in how the treatments may be administered from clinic to clinic.

Mesenchymal stem cells

Transplanted, minimally manipulated, non-cultured mesenchymal stem cells (MSCs) from a patient’s own bone marrow or adipose fat are considered to be viable treatment options in cases of soft tissue damage such as in ligaments, tendons, and cartilage. Bone marrow is typically taken from the iliac crest of the pelvis and adipose fat is taken in a mini-liposuction type procedure. Treatments are generally one or the other.

An October 2020 paper in the journal Medical Archives (7) wrote: “Clinical application of Mesenchymal stem cells for the treatment of tendon and ligament injuries might be a good alternative option for athletes. Published clinical studies confirmed clinical improvement and integrity of impaired tissues. However, (more research is needed) to confirm the real potential of cell therapy and its advantages compared to other treatment options.

An April 2023 review study in the journal Medicina (8) writes: “Although the MCL has a relatively good healing capacity, several studies have demonstrated that healing ligaments are less organized (the ligament does not heal “as good as new”) with decreased mechanical strength, leading to an increased risk of reinjury and poor functional outcome. . .recent preclinical studies have shown promising results in enhancing MCL healing using Mesenchymal Stem Cells. However, only limited preclinical studies have been conducted, and the precise mechanism by which MSCs enhance MCL healing is still unknown.”

Platelet Rich Plasma treatments

A February 2020 paper in The Journal of international medical research (9) followed 52 patients with chronic, unresponsive knee pain after low-grade knee MCL injury, and, who were treated by intra-articular injection of autologous Platelet Rich Plasma injection once weekly for three weeks. Here are the study points:


Prolotherapy for MCL tears

The key to pain-free, healthy joints are healthy and strong ligaments and tendons. In the case of an injured MCL (or any injured ligament) is to treat with Prolotherapy. Prolotherapy stimulates repair by inducing mild inflammation in the weakened ligaments and tendons. The localized inflammation triggers a wound-healing cascade, resulting in the deposition of new collagen, the material that ligaments and tendons are made of. New collagen shrinks as it matures. The shrinking collagen tightens the ligament that was injected and makes it stronger. Prolotherapy has shown to be extremely effective at eliminating pain and sports injuries that are a result of ligament and/or tendon weakness. So instead of letting an injury “heal on its own” it’s best to treat injured ligaments with Prolotherapy to ensure proper regeneration of ligament tissue.

Prolotherapy helps provide a whole knee healing environment and stabilization for the MCL injury

When patients experience an MCL injury, they typically also injure the other knee ligaments such as the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and Lateral Collateral Ligament (LCL). Traditional medicine likes to treat these types of injuries with surgery. Surgery, however, means cutting and removing. Cutting through important knee structures will eventually lead to more knee instability and degeneration of the knee joint.

Prolotherapy for an MCL injury involves injections inside the joint, to the MCL, and the surrounding affected tissues. This treatment is comprehensive in order to treat all of the weakened areas, as injury to the MCL often involves injury to the other ligaments and surrounding tissue of the knee joint.

Although a totally torn ligament usually requires surgery, Prolotherapy can play a key healing role here as well. First, because Prolotherapy has been shown to regenerate tissue, this treatment should be given a chance to help the ligament heal itself, even before surgery is considered. Secondly, Prolotherapy can also be a healing complement to surgery because the other ligaments around the knee, as well as the joint capsule itself, were at least stretched during the injury to the knee. Untreated, this stretching would most likely lead to instability of the knee joint.

Along with a controlled exercise program for the healthy motion of the knee joint, Prolotherapy can successfully treat the injured medial collateral ligament and help patients get back to their normal activity levels.

Now let’s introduce another recent study on the effects of Prolotherapy injections on an MCL tear. A patient case study documents Prolotherapy treatment for a rugby player who had a grade 2 partial tear sprain of the MCL.

In his case, Prolotherapy, together with an exercise therapy program of three weeks had the patient pain-free, with a full range of motion, and he was able to perform all rugby-specific movements. (10) The success of this study was in how fast the player was able to return – three weeks as s opposed to 4 to 8 weeks for a grade two sprain. Prolotherapy induced a quicker “spontaneous healing.”

Do you have a question about Medial Collateral Ligament Knee Injury? You can get help and information from our Caring Medical staff


1 Requicha F, Comley A. Medial soft-tissue complex of the knee: Current concepts, controversies, and future directions of the forgotten unit. Orthopedic Reviews. 2021;13(2). [Google Scholar]
2 Andrews K, Lu A, Mckean L, Ebraheim N. Medial collateral ligament injuries. Journal of orthopaedics. 2017 Dec 1;14(4):550-4. [Google Scholar]
3 Wan C, Hao Z, Wen S. The effect of healing in the medial collateral ligament of human knee joint: A three-dimensional finite element analysis. Proc Inst Mech Eng H. 2016 Jun 30. pii: 0954411916656662. [Google Scholar]
4 Frank C, Woo SL, Amiel D, Harwood F, Gomez M, Akeson W. (1983). Medial collateral ligament healing. A multidisciplinary assessment in rabbits. The Journal of Sports Medicine, 11(6). [Google Scholar]
5 Park DJ, Rucci P, Sussman WI. Chronic Medial Collateral Ligament Sprain Treated With Percutaneous Ultrasonic Debridement: A Case Report. Clinical Journal of Sport Medicine. 2022 Mar 15;32(2):e175-7. [Google Scholar]
6 Sung K, Raja AE, Tunis JG, Tunis BG, Zheng K, Sussman WI, Raja A. Heterotopic Mineralization of the Medial Collateral Ligament: Our Experience Treating Two Cases of Calcific Versus Ossific Lesions With Ultrasonic Vacuum Debridement. Cureus. 2023 Mar 14;15(3).
7 Trebinjac S, Gharairi M. Mesenchymal stem cells for treatment of tendon and ligament injuries-clinical evidence. Medical Archives. 2020 Oct;74(5):387. [Google Scholar]
8 Lee CS, Jeon OH, Han SB, Jang KM. Mesenchymal Stem Cells for Enhanced Healing of the Medial Collateral Ligament of the Knee Joint. Medicina. 2023 Apr 7;59(4):725. [Google Scholar]
9 Zou G, Zheng M, Chen W, He X, Cang D. Autologous platelet-rich plasma therapy for refractory pain after low-grade medial collateral ligament injury. Journal of International Medical Research. 2020 Feb;48(2):0300060520903636. [Google Scholar]
10 Ada AM, Yavuz F. Treatment of a medial collateral ligament sprain using prolotherapy: a case study. Altern Ther Health Med. 2015 Jul;21(4):68-71. [Google Scholar]

This article was update May 3, 2023


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