When the ACL and MCL tear together, the usual approach is to let the MCL heal in a brace first, then reconstruct the ACL once the knee moves well. The MCL needs surgery only if it doesn't heal enough to keep the knee stable, or for certain tear patterns – but a loose MCL left untreated raises the risk of the new ACL failing.
Combined ACL and MCL injuries account for about a fifth of all knee ligament injuries. This guide from the knee team at Sports Orthopedics Institute, Bengaluru explains how they are diagnosed, when each ligament needs surgery, and what recovery involves.
Key takeaways
- Most MCL tears heal without surgery, even when the ACL is also torn.
- Delaying ACL reconstruction for a few weeks lets the MCL heal and the knee regain movement.
- Residual MCL laxity matters: in a Swedish registry of over 19,000 patients, a non-surgically treated MCL injury was linked with a higher risk of ACL revision.
- MCL surgery is considered for persistent valgus laxity, tibial-sided or avulsion tears, and Stener-type lesions.
- Graft choice should protect the inner knee – preserving the hamstring and sartorius tendons that support it.
The Two Ligaments and How They Tear
- ACL (anterior cruciate ligament): inside the knee; stops the shin bone sliding forwards and controls twisting.
- MCL (medial collateral ligament): on the inner side of the knee; stops the knee buckling inwards (valgus).
Both often tear together when the knee is forced inwards while twisting – a tackle from the side in football or kabaddi, a skiing fall, or an awkward landing.
Symptoms
- Pain and swelling, especially on the inner side of the knee
- A pop at the time of injury
- The knee giving way or feeling loose, particularly when turning
- Difficulty bending and straightening
Diagnosis and MCL Grades
- Examination: the Lachman test for the ACL; the valgus stress test (pushing the knee inwards with the knee slightly bent and straight) for the MCL
- X-rays: to check for fractures; the Ottawa knee rules help decide who needs one
- MRI: confirms both tears, shows where the MCL has torn (thigh or shin end), and identifies meniscus and cartilage damage
- Stress X-rays: sometimes used to measure how much the inner knee opens
|
MCL grade |
Damage |
Knee opening on stress test |
|---|---|---|
|
I |
Stretched |
Tender but stable |
|
II |
Partly torn |
Some opening, with a firm endpoint |
|
III |
Completely torn |
Clear opening, no firm endpoint |
Treatment: MCL First, Then ACL
The MCL has a good blood supply and usually heals; the ACL does not. So most surgeons treat the MCL in a hinged brace first and reconstruct the ACL a few weeks later.
Step 1 – Let the MCL heal (about 4–6 weeks)
- Hinged knee brace to protect against inward stress
- Early movement and quadriceps exercises
- Walking as comfort allows
Step 2 – Reconstruct the ACL
Once the knee bends and straightens well, swelling has settled and the MCL has tightened, the ACL is reconstructed.
What the evidence shows
- Delayed approach: a 2024 meta-analysis of 18 studies (1,534 cases) found no difference in patient-reported outcomes, movement or strength between non-surgical and surgical MCL treatment. Delaying reconstruction helps movement recover and allows lower-grade MCL tears to heal (Am J Sports Med, 2024).
- Randomised trials: in 47 patients with combined ACL and grade III MCL tears having early ACL reconstruction, operative and non-operative MCL treatment gave comparable outcomes (Am J Sports Med, 2006). Another trial found non-operative MCL treatment gave better early movement and quadriceps recovery (JBJS, 2009).
- But residual laxity matters: in the Swedish registry of 19,457 ACL reconstructions, an isolated ACL reconstruction had a lower revision risk than one with a non-surgically treated MCL injury, while MCL repair or reconstruction showed no extra risk. Surgical MCL treatment was, however, linked to worse 2-year knee function (KSSTA, 2019).
When Does the MCL Need Surgery?
MCL repair or reconstruction is considered when:
- The inner knee is still loose (valgus or anteromedial rotatory laxity) after a period of bracing and rehab
- The tear is at the shin-bone end or mid-substance – these grade III tears are less likely to regain stability without surgery than tears at the thigh-bone end (systematic review, 2023)
- The MCL has pulled off bone (avulsion) or become trapped outside the hamstring tendons (a Stener-type lesion), which may benefit from early repair
- There are multiple ligament injuries, or the injury is long-standing with chronic instability
Repair or reconstruction?
- Repair reattaches the torn ligament, often with suture anchors – best for acute avulsions and Stener-type lesions.
- Reconstruction replaces the MCL with a graft – used when the tissue is poor or the injury is chronic. Anatomical techniques recreate the main parts of the MCL (including “triangular” configurations that restore both the superficial MCL and the posterior oblique ligament).
Protecting the inner-knee tendons (ST-G-S complex)
The semitendinosus, gracilis and sartorius tendons (the pes anserinus) cross the inner knee and help resist inward buckling. Hamstring tendons are a common ACL graft source, so in an MCL-injured knee surgeons weigh this carefully. In a Swedish registry study of ACL reconstruction with a non-surgically treated MCL injury, graft choice didn't change revision risk, but using both semitendinosus and gracilis was linked to poorer 2-year knee function than semitendinosus alone (Swedish registry). Options include a patellar or quadriceps tendon graft, a semitendinosus-only graft, or an allograft.
Recovery Timeline
|
Stage |
Typical timing |
Focus |
|---|---|---|
|
MCL healing |
Weeks 0–6 |
Hinged brace; regain full straightening and bending; quadriceps activation |
|
ACL reconstruction |
Usually around 4–8 weeks after injury |
Surgery once movement is good and swelling has settled; MCL repair or reconstruction at the same time if needed |
|
Early rehab |
Weeks 0–6 after ACL surgery |
Walking normally, full movement, basic strength; brace if the MCL was operated on |
|
Strength and running |
Months 3–6 |
Progressive strengthening, balance, running once criteria are met |
|
Return to sport |
Usually 9–12 months |
After passing strength and hop tests |
Stiffness is a particular risk with combined injuries, so regaining movement early is a priority. For more detail, see our week-by-week ACL recovery guide.
Why the MCL Shouldn't Be Overlooked
- ACL graft failure: a loose MCL puts extra stress on the new ACL graft, raising the chance it stretches or tears
- Ongoing instability: the knee may keep giving way, especially when cutting or side-stepping
- Stiffness: operating on both ligaments too early, before movement returns, raises the risk of a stiff knee
The key is careful assessment at each stage – before ACL surgery, at the time of surgery, and during rehab.
How Sports Orthopedics Institute Can Help
Our knee team in HSR Layout, Bengaluru manages combined ligament injuries from bracing and rehabilitation to ACL reconstruction, MCL repair and reconstruction, and multi-ligament surgery – with graft choices tailored to protect your knee.
Book at sportsorthopedics.in or call +91 6364538660 / +91 9008520831.
Frequently Asked Questions
Do I need surgery for both the ACL and MCL?
Usually only the ACL. Most MCL tears heal in a brace. The MCL needs surgery if the inner knee stays loose after bracing, or for certain tear patterns such as avulsions and Stener-type lesions.
Why wait before ACL surgery?
Waiting a few weeks lets the MCL heal and the knee regain movement, which lowers the risk of stiffness after surgery.
Will a grade III MCL tear heal on its own?
Often, especially tears at the thigh-bone end. Tears at the shin-bone end or in the middle of the ligament are less likely to regain full stability without surgery.
Does an MCL injury affect my ACL reconstruction?
It can. A large Swedish registry found a higher risk of ACL revision when a concomitant MCL injury was treated non-surgically – which is why any remaining MCL laxity is checked carefully.
Which graft is best when the MCL is also injured?
There is no single best graft. Many surgeons prefer to preserve the inner-knee tendons by using a patellar or quadriceps tendon graft, a semitendinosus-only graft, or an allograft.
How long until I can play sport again?
Usually 9–12 months after ACL reconstruction, once you pass return-to-sport tests.
References
- Shultz CL, et al. Nonoperative management, repair, or reconstruction of the MCL in combined ACL and MCL injuries – which is best? A systematic review and meta-analysis. Am J Sports Med, 2024;52(2):522–534.
- Outcomes of combined complete ACL and grade III MCL injuries: a systematic review, 2023.
- Operative and nonoperative treatment of MCL rupture with early ACL reconstruction: a prospective randomized study. Am J Sports Med, 2006;34(7):1134–1140.
- Halinen J, et al. Range of motion and quadriceps muscle power after early surgical treatment of acute combined ACL and grade III MCL injuries: a prospective randomized study. J Bone Joint Surg Am, 2009;91(6):1305–1312.
- Svantesson E, et al. Increased risk of ACL revision with non-surgical treatment of a concomitant MCL injury: 19,457 patients from the Swedish National Knee Ligament Registry. Knee Surg Sports Traumatol Arthrosc, 2019;27(8):2450–2459.
- Svantesson E, et al. Graft choice for ACL reconstruction with a concomitant non-surgically treated MCL injury, 2020.
Disclaimer: This article is for general information and does not replace advice from a qualified orthopedic Surgeon.