Pain guide · Knee pain
The medial collateral ligament (MCL) runs down the inner side of the knee, and it's the knee ligament people injure most, usually from a blow to the outside of the knee or a twist. Most MCL sprains, even many complete tears, heal without surgery with early movement and progressive strengthening.
This guide covers the grades, rough recovery times (the evidence on timing is thin), bracing, and a staged plan from the first days to sport. Start with the warning signs: swelling of the whole knee, a pop or a knee that gives way suggest another injury, often to the anterior cruciate ligament (ACL), and need assessing first.
Exercise is for pain that has been checked or is clearly mild and settling.
The MCL runs down the inner side of the knee, from the thigh bone to the shin bone, and stops the knee being pushed inwards. It is the most commonly injured knee ligament. It tears when the knee is forced inwards with the foot on the ground: a blow to the outside of the knee, a twist, slipping on ice, or sports such as skiing, football and rugby. In older people a fall can do it. In elite football, 3 in 4 MCL injuries involved contact.
A sprain and a tear are the same injury at different grades. Clinicians grade it by pushing the knee inwards with it slightly bent (about 30°) and again with it straight. In elite footballers, grading by examination agreed almost perfectly with grading on MRI. Scans are mainly used to look for other injuries, and in one NHS area only the orthopaedic team requests an MRI.
The MCL lies outside the joint and has a good blood supply, so it heals much better than the ACL. An NHS leaflet says grade 1 injuries almost always heal and grade 3 injuries mostly heal, especially when the MCL is the only ligament torn. When a complete tear fails to heal, the inner side of the knee can stay loose.
Reviews agree that grade 1 and 2 sprains, and complete tears that leave the knee stable, are treated without surgery, with early functional rehab. Surgery is for tears with a marked knock-knee alignment, the ligament trapped in the wrong place, a piece of bone pulled off, or looseness that persists. In elite football, 2 of 130 MCL injuries were operated on.
In 35 athletes with complete tears and no other injury, treated with a hinged brace, early movement and then strengthening, knee function about 5 years later matched earlier results after surgery or plaster, with a faster return to sport; in 28 college footballers with complete tears, 20 of the 21 followed up did well. The studies are old and small, though: a 2024 review rated the evidence very low certainty.
In small, mostly old studies of athletes doing daily rehab, people were back to full play about 10 days after a grade 1 sprain and about 3 to 6 weeks after a grade 2, and back to full-contact training about 9 weeks after a complete tear. A US rehab protocol estimates 2 to 4, 6 to 8 and 8 to 12 weeks for the three grades. An NHS leaflet gives a longer range: healing normally takes about 6 to 12 weeks, and some discomfort and swelling for longer is normal.
The evidence is very low certainty, so treat these as rough guides, not deadlines. Recovery is judged by the knee, not the calendar.
In 51 college footballers with grade 1 or 2 sprains, active rehab with little or no time in a splint got them back to play in about 10 to 20 days, with no apparent rise in reinjury. An NHS leaflet recommends protecting the knee with relative rest while loading it gradually and walking as normally as possible early on, saying the evidence suggests this speeds recovery. Reviews recommend early movement and strengthening, then sport once strength and balance match the other side.
The US physical therapy guideline for knee ligament injuries says clinicians may use a brace for severe MCL injuries, based on expert opinion. In elite footballers with grade 2 sprains, those who wore a stabilising brace were out longer (about 42 against 32 days), though they may have had worse sprains, and the authors suggest routine bracing isn't needed for milder ones.
In a 2024 review, braces were worn for 2 to 5 weeks, flexible braces went with shorter lay-offs than rigid ones, and the evidence was very low certainty. Practice varies: one NHS area uses a hinged brace limited to 0° to 90° for 6 weeks, and a US protocol uses one possibly for grade 1 and most often for grades 2 and 3.
Combined MCL and ACL injuries are among the commonest injuries involving more than one knee ligament. The MCL is still usually treated without surgery, with a brace for about 6 weeks, and the ACL reconstructed once the knee moves well; if the inner side is still loose after 6 weeks in a brace, surgeons usually repair both. The ACL injury guide covers that part.
An NHS leaflet: do the exercises as pain allows, and some discomfort is acceptable. If a sharp, shooting pain comes on, ease off. Gently moving the knee should begin to reduce the pain, not cause further damage.
As a number, keep pain with activity below about 3 out of 10. A US protocol moves people with severe sprains on when pain with activity is below 3 out of 10 (lower for milder sprains), with no increase in swelling, tenderness or looseness on the inner knee.
Check the next morning: the inner knee should be no more swollen, sore or loose than before. If it is, drop back a step (our suggestion).
Start at the first stage. Each move opens a full guide with a 3D demo.
Protect the knee with relative rest while loading it as comfort allows, use ice, compression and raising the leg, and walk as normally as you can, with crutches if you need them (an NHS leaflet's advice). If you've been given a brace, take it off for the exercises unless told otherwise. Do the exercises little and often through the day.
3D demoSupine heel slideBeginner · No equipmentHold 5 s at the point of discomfort, a little further each time; 10 times · Hold time from an NHS leaflet; repetitions editorial
Harder: Hip Windshield Wipers
3D demoQuad set (static quads)Beginner · No equipmentHold 5 s; 10 times, little and often · With the heel on a rolled towel or a stool and nothing under the knee, let it sag straight between squeezes; build the time propped from 30 s to 3 min (an NHS leaflet)
Harder: Straight-leg raise
3D demoStraight-leg raiseBeginner · No equipmentHold 5 s; 10 times · Hold time from an NHS leaflet; repetitions editorial
Easier: Quad set (static quads) · Harder: Leg extension
3D demoGlute bridgeBeginner · No equipment10 slow repetitions (editorial)
Easier: Pelvic tilt into bridge · Harder: Glute kickback (quadruped hip extension)
3D demoClamshellBeginner · No equipment10 slow repetitions each side (editorial) · Keep the feet together and the pelvis still
Harder: Lateral band walk
3D demoStationary cyclingBeginner · Cardio machine10 to 20 min, easy (editorial) · Once the knee bends enough to pedal round
Harder: Air bike intervals
Move on when: You walk without a limp, the swelling is settling, the knee nearly straightens and bends fully, and the inner knee is no sorer after exercise.
Two to 3 strength days a week, 3 sets of 8 to 12 (editorial). Keep the knee over the middle toes; side-to-side and twisting work waits. One US protocol avoids significant sideways stress until 3 to 4 weeks after the injury.
3D demoWall sitBeginner · A wallHold 5 s; 10 times, then longer holds · Only as deep as discomfort allows, knees not bowing inwards; hold time from an NHS leaflet, repetitions editorial
Easier: Straight-leg raise · Harder: Spanish squat (band squat hold)
3D demoStep-upBeginner · A step3 sets of 8 to 10 each leg · Low step; knee over the middle toes
Easier: Low step-up · Harder: Dumbbell step-up
3D demoSingle-leg standBeginner · A wall3 holds of 30 to 60 s · Weaning off the support
Easier: Tandem stance and heel-to-toe walk · Harder: Single Leg Reach Matrix
3D demoSlow calf raiseBeginner · A wall3 sets of 12
Easier: Seated bent-knee calf raise (soleus raise) · Harder: Standing dumbbell calf raise
Move on when: Movement is full with only mild pain, there's no new swelling after sessions, and you can walk briskly without a limp. One protocol starts running once strength is about 75% of the other leg.
Running first, then sideways moves, hopping and cutting. In severe sprains one US protocol adds side shuffles at about 6 weeks, running at 8 weeks once strength is about 75% of the other leg, and jumping and agility drills at 10 weeks. Doses here are editorial.
3D demoSplit squatIntermediate · No equipment3 sets of 8 each leg
Easier: Bodyweight squat · Harder: Reverse lunge
3D demoTreadmill joggingIntermediate · Cardio machineWalk-jog intervals, then continuous running
Easier: Treadmill walking · Harder: Sprint intervals
3D demoLateral band walkBeginner · A band3 sets of 10 steps each way · The first sideways loading
Easier: Hip abduction machine · Harder: Lateral band walk, band at the feet
3D demoSingle-leg hop and stickIntermediate · No equipment3 sets of 5 each leg · Forwards first, then sideways
Easier: Standing broad jump with stuck landing · Harder: Alternate-leg bounding
3D demoLateral bound (skater jump)Beginner · No equipment2 to 3 sets of 5 each side · Hold each landing at first, and only once cleared for sideways jumps
Harder: Box push-off jump
3D demoShuttle runsAdvanced · No equipmentShort sets, building speed · Wide turns first
Easier: Treadmill jogging
Move on when: You can fully bend and straighten the knee without pain, your strength matches the other leg, and the knee doesn't swell or give way. For football, rugby or skiing, you can also jog without a limp, change direction without pain, and jump and hop on the injured leg without pain or giving way (an NHS leaflet's checks).
Side-to-side moves, cutting and pivoting come last: one protocol avoids significant sideways stress until 3 to 4 weeks after the injury, and an NHS leaflet notes that twisting and changing direction usually take longest to rehabilitate. Keep the knee over the middle toes in squats, step-ups and landings, rather than letting it drop inwards. Swing both legs together getting in and out of a car, so the knee doesn't twist.
If you've been given a brace, take it off for the exercises unless told otherwise. When you're allowed out of it, the same leaflet suggests leaving it off at night first, then wearing it only in busy places, then not at all.
In elite football, a quarter of MCL injuries were injected, mostly with platelet-rich plasma, with no difference in time out for grade 2 sprains, and a 2024 review rated the evidence for injections very low.
| Habit or position | Why it matters | Instead |
|---|---|---|
| Side-to-side moves, cutting and pivoting in the first weeks | They stress the healing ligament; one protocol avoids significant sideways stress until 3 to 4 weeks after the injury. | Straight-line strength: step-ups, sit-to-stands and cycling. |
| Letting the knee drop inwards in squats, step-ups and landings | It pushes the knee towards the position that injures the MCL. | Knees over the middle toes, in a shallower range. |
| Twisting the knee getting in and out of a car | It can irritate the MCL. | Swing both legs in and out together. |
| Total rest, or keeping the knee still | Early movement and loading help recovery. | Little-and-often exercises from the start. |
| Wearing a brace for a mild sprain just in case | In elite players with grade 2 sprains a brace went with a longer lay-off, and braces are for more severe sprains, as your clinician advises. | Wear one only if you're given it, and wean out of it as advised. |
| Returning to sport by the calendar | Recovery is judged by the knee, not by days and weeks. | Use the return-to-sport checks in stage 3. |
A gentle leg strength routine with no jumping: sit-to-stands, step-ups, wall sits, bridges and calf raises.
20 minBeginner7 movesA bench or box, A stepA 20-minute warm-up that trains your knees to track over your toes: side-hip strength, squats and lunges with alignment practice, balance and quiet landings.
20 minBeginner10 movesA wall, A bandIt depends on the grade, and the evidence is thin. In small, mostly old studies of athletes, people were back to play about 10 days after a grade 1 sprain, 3 to 6 weeks after a grade 2 and about 9 weeks after a complete tear. An NHS leaflet gives a longer range, about 6 to 12 weeks, with some discomfort and swelling for longer. Recovery is judged by the knee, not the calendar.
Rarely. Most MCL injuries, including most complete tears with no other damage, heal with early rehab. Surgery is mainly for tears with other injuries, a piece of bone pulled off, or a knee that stays loose.
Usually, yes: an NHS leaflet advises walking as normally as you can, with crutches if you need them. If you cannot put weight on the leg, get it checked.
Not for a mild sprain. Clinicians may use a hinged brace for more severe sprains, but in elite footballers with grade 2 sprains, wearing one went with a longer lay-off. If you're given one, wean out of it as advised.
Early on, side-to-side movements, cutting and twisting, and letting the knee drop inwards in squats or step-ups. Straight-line strength exercises are fine within the pain rule.
They're the same injury at different grades: grade 1 is a stretch, grade 2 a partial tear and grade 3 a complete tear. All three usually heal without surgery.
Swelling of the whole knee within hours, a pop, the knee giving way or locking, or being unable to put weight on it suggest another injury, often to the ACL. Get it assessed rather than waiting.
Usually not: clinicians grade MCL sprains by examination, which matched MRI closely in elite players. Scans are mainly for suspected other injuries.
When the knee bends and straightens fully without pain, your strength matches the other leg, and it doesn't swell or give way. You should also be able to jog without a limp, change direction without pain, and jump and hop on the injured leg without pain.
Yes, once the knee bends far enough to pedal round: an exercise bike is part of the first phase of rehab protocols. Start easy, with no resistance.
Exercise education, not a diagnosis or treatment plan. It is written from the guidelines and studies listed above; review by a clinician is pending. If your pain follows an injury, is severe, is getting worse, or comes with any warning sign listed on this page, get it assessed. Health disclaimer.
