MCL tear
Also called: MCL sprain, medial collateral ligament injury, torn MCL, inside knee ligament injury. Clinical name: Medial collateral ligament (MCL) sprain of the knee.
Mild MCL sprains settle in 1–3 weeks, moderate tears in 3–6 weeks, and complete tears in 6 weeks or more. Most isolated MCL tears heal without surgery. Giving way or a locking knee can mean a combined ACL or meniscus injury and needs assessment.
What it actually is
The medial collateral ligament runs down the inner side of the knee and stops it buckling inwards. An MCL tear is the classic result of a blow to the outside of the knee or an awkward twist: a rugby tackle, a ski fall, a football challenge, a slip where the knee caves in. It is one of the most common knee ligament injuries, and it has one genuinely reassuring feature that sets it apart from the ACL.
That feature is healing. Unlike the ACL, the MCL has a rich blood supply and knits itself back together, so the overwhelming majority of MCL tears, including many complete ones, recover without surgery. The treatment is usually a period protecting the ligament (a hinged brace, sometimes crutches), then a graded rehab that rebuilds movement, strength and, last of all, side-to-side control. Mild tears are a few weeks; moderate tears a month or so; complete tears longer.
The thing to watch for is company. The MCL is often injured alongside the ACL or the meniscus, and that combination changes the timeline and sometimes the decision about surgery. A knee that popped and swelled fast, that gives way underneath you, or that locks and will not straighten, is telling you it may be more than an isolated MCL, and that is the point to get it properly assessed. Tracked day to day, an isolated MCL is one of the more predictable knee injuries to come back from.
How bad is it?
Injuries like this are usually described in grades. The grade is what shapes your timeline and what you can safely do while it settles.
A few ligament fibres overstretched. Tenderness on the inner knee, mild or no swelling, and the knee still feels stable. Usually back to sport inside a few weeks.
A partial tear. More pain and swelling on the inner knee, some looseness when a clinician stresses the joint, and it complains on turns and side-steps. A hinged knee brace is often used for a while.
A complete tear. Marked swelling, clear instability, and often bruising down the inner knee. Even so, an isolated grade 3 MCL frequently heals without surgery in a brace; the concern is a combined injury (ACL or meniscus) alongside it, which changes the plan.
How long will it take?
Recovery moves in phases. This is the typical shape of it — yours may run faster or slower, and the numbers below are general ranges, not a forecast for your specific injury.
When to get it looked at
Most cases settle with time and sensible loading. Get it assessed by a professional if any of these apply — they can point to something that needs hands-on care:
- The knee giving way, buckling or feeling like it will not hold you (may mean more than the MCL, such as the ACL)
- A knee that locks, catches or cannot fully straighten (possible meniscus involvement)
- Large immediate swelling within an hour of the injury, especially with a pop (raises suspicion of an ACL tear or fracture)
- Numbness, pins and needles, coldness or colour change below the knee
- Pain that is not clearly improving after two to three weeks of sensible rehab
This is a list of warning signs, not a diagnosis. If you are worried, or the pain is severe, see a GP, physiotherapist or urgent care.
What to track while you recover
MCL recoveries go wrong when side-to-side strength and stability come back slower than the pain does, and the first hard cut re-opens it. A short daily log of pain, swelling and what movement the knee tolerated keeps that gap visible.
- Pain score, 0–10, walking, on stairs, and on any turn or side-step
- Swelling on the inner knee compared with the other side (a quick evening look)
- Range of movement: can the knee fully straighten and fully bend yet
- The most the knee did today: walk, jog, run, change direction, and how it felt
- Any giving-way, locking or catching (note these clearly, they change the picture)
This is exactly what InjuryLog does.
Log each of these in seconds, watch the trend build day by day, and keep every scan and receipt tied to this one injury. Free on iOS, Android soon.
Wondering how long yours will take? Try the free recovery time estimator for a typical, phased timeline by injury and severity.
What to tell your physio
A clinician grades an MCL from the mechanism and how the joint feels under a sideways stress test, and mostly wants to rule out a combined ACL or meniscus injury. Bring the story of the moment it happened.
- How it happened: a blow to the outside of the knee, an awkward twist, or a fall, and whether you felt or heard a pop
- Whether you could keep playing or had to stop, and how fast it swelled
- Where exactly it hurts (inner knee for the MCL) and whether the knee has given way since
- Current pain, swelling, range of movement and what running or cutting you have tried
- Previous knee injuries and your target sport, surface and return date
Walk in with the whole picture.
InjuryLog turns your daily logs into a clean Physio Visit Pack, a one-page summary your physio can actually read, so the first appointment starts with facts, not guesswork.
The questions people actually ask
How long does an MCL tear take to heal?
It depends on grade. A mild grade 1 sprain usually settles in one to three weeks, a moderate grade 2 partial tear in about three to six weeks, and a complete grade 3 tear in six weeks or more. The good news is that the MCL has a strong blood supply and heals well, so even complete isolated tears often recover without surgery in a hinged brace. The timeline stretches when the MCL injury comes with an ACL or meniscus tear, which is why a proper assessment early on matters.
Do you need surgery for an MCL tear?
Usually not. The MCL is one of the few knee ligaments that reliably heals itself, so the large majority of isolated MCL tears, including many grade 3 tears, are treated without surgery: a period in a hinged knee brace, then progressive rehab. Surgery is mainly considered when the MCL injury is combined with other damage (an ACL or meniscus tear), when the knee stays unstable despite good rehab, or for certain tears where the ligament end is displaced. A clinician assessing the specific injury makes that call.
What does a grade 2 MCL tear feel like?
A moderate MCL tear typically gives pain and tenderness along the inner side of the knee, swelling there over the first day or two, and a knee that feels unsure on turns, side-steps and stairs even if it holds you in a straight line. A clinician stressing the knee sideways will find it opens up a little more than the other side. It rarely swells as dramatically or immediately as an ACL tear, and if the knee is truly giving way or locking, that points to more than an isolated MCL.
Can I walk on a torn MCL?
Often yes, for mild tears, and walking within comfort is part of recovery. Moderate and severe tears are usually more comfortable and better protected in a hinged brace, sometimes with crutches for the first week, so the ligament is not stressed sideways while it knits. What you should not do early is cut, pivot or take a knock to the knee. If you cannot bear weight at all, or the knee gives way when you try, get it assessed rather than pushing through.
When can I run and play sport again after an MCL tear?
Running usually returns before cutting, because the MCL is stressed most by side-to-side force. A rough pattern: straight-line jogging once you have full pain-free movement and decent strength (often a couple of weeks for grade 1, later for higher grades), then striding and change of direction, then full-speed cutting and contact last. Most mild tears are back in a few weeks, moderate tears around one to one and a half months, and complete tears longer. Return when strength, stability and confidence are back, not just when it stops hurting.
How do I know if it is my MCL or my ACL?
They feel different. An MCL tear hurts on the inner side of the knee, swells modestly, and stays fairly stable in a straight line. An ACL tear more often comes with a loud pop, rapid large swelling within an hour, and a knee that feels like it gives way underneath you, especially on turns. The two can happen together. Because the difference changes everything about the treatment and timeline, any knee that swelled fast, popped, or keeps giving way deserves a clinician's assessment rather than guesswork.
Sources
- Knee ligament injuries — NHS
- Collateral Ligament Injuries — AAOS OrthoInfo