Torn Patellar or Quadriceps Tendon: Signs, Surgery, Rehab

When to get help first

Exercise is for pain that has been checked or is clearly mild and settling.

Get urgent medical help if

Same day: a pop or tearing feeling at the front of the knee after a fall, stumble, jump or landing, then you can't straighten the knee or lift the straight leg off the bed, there's a dent above or below the kneecap, or the kneecap sits higher or lower than on the other side. Go to A&E or an urgent treatment centre, or get help from NHS 111. A torn quadriceps or patellar tendon does best when it's repaired soon.
Call 999 or go to A&E if you heard a crack when you were injured, the knee has changed shape or points at an odd angle, the leg below it is numb or tingling, or the skin has changed colour or is cold to touch. You may have broken a bone. Don't drive yourself.
You cannot move the knee or put any weight on it, or it is very painful, badly swollen or has changed shape.
After tendon repair: changes in feeling, severe pain or swelling, a change of colour in the leg or foot, oozing from the wound, a high temperature, or feeling hot and cold. Contact your surgical team, or ask for an urgent GP appointment or get help from NHS 111.
In a brace or on crutches: throbbing pain and swelling in one calf or thigh, with red or darkened skin or swollen veins. Ask for an urgent GP appointment or get help from NHS 111, as it could be a blood clot.
Leg pain or swelling with breathlessness or chest pain: call 999 or go to A&E, and do not drive yourself. It can be a blood clot that has reached the lungs.
During recovery: a new pop, suddenly being unable to lift the straight leg, or the kneecap moving position. Contact your team the same day, because the repair may have torn.
A child or teenager: after a jump, landing or fall, a pop or sudden severe pain below the kneecap, and the knee will not straighten or take weight. Get it checked the same day: the bony bump below the kneecap can break away instead of the tendon tearing, or a sleeve of bone and cartilage can pull off the lower kneecap.

See a doctor or physiotherapist if

Swelling that keeps rising after sessions, or the knee not straightening or bending as your team expects at each stage: tell your physiotherapist.
Months after a repair, you still can't fully straighten the knee by yourself (it sags when you lift the leg): ask your team to review it.
You've had a tendon rupture and you have kidney disease, lupus, rheumatoid arthritis or gout, or you take steroids: ask your GP whether anything needs treating to protect your other tendons.
Pain building just below the kneecap with jumping or running: tendon pain weakens the tendon, so start our jumper's knee guide's plan early. Pain building just above it, worse with deep squats, jumping or kneeling, is quadriceps tendinopathy: start that guide's plan early.
In a brace: sore skin, pressure marks, or a brace that no longer fits as the swelling goes down. Tell your physiotherapist or orthotics team.

Understand it

What the tendons do, and what a rupture isStrong evidence

The four quadriceps muscles at the front of the thigh join above the kneecap as the quadriceps tendon, and the patellar tendon runs from the bottom of the kneecap to the top of the shin. Together they straighten the knee. A partial tear frays the tendon; a complete tear splits it or pulls it off the bone, and then the knee can't be straightened against gravity.

Patellar tendons usually tear where they attach to the kneecap; tears through the middle are more typical of a tendon that was already diseased. In older people, quadriceps tears usually happen where the tendon meets the bone.

Sources 1, 2, 3, 4

How it happens and who gets itEmerging evidence

Usually a heavy load on a bent knee with the foot planted, such as an awkward landing, a jump or a stumble on the stairs; a fall; a direct blow; or a deep cut. A simple fall caused 62% of quadriceps tears in a review of 319 people.

Most are in middle-aged men. Of 726 people operated on for injuries to the knee's straightening mechanism, 91% of the quadriceps and 96% of the patellar tendon ruptures were in men, and 43% of the patellar tendon ruptures were in people over 40. Classically, quadriceps tears happen over 40, often with an underlying condition, and patellar tendon tears under 40, often in sport. They're uncommon: in US emergency departments, about 0.5 (patellar) and 0.3 (quadriceps) per 100,000 people a year, both rising as people stay active for longer. In one NHS trust, operated ruptures rose from 4.6 to 8.3 per 100,000 a year after the pandemic (median age 63).

Sources 1, 2, 5, 6, 7, 8, 9, 10, 11

What raises the riskEmerging evidence

Conditions that weaken tendons: chronic kidney failure and dialysis, an overactive parathyroid gland, gout, leukaemia, rheumatoid arthritis, lupus, diabetes, infection and metabolic disease. Steroids (tablets, anabolic steroids, and injections near the patellar tendon, which doctors usually avoid for this reason), fluoroquinolone antibiotics, long spells of immobilisation, and previous knee surgery, such as a knee replacement or an ACL (anterior cruciate ligament) reconstruction, also raise the risk. Tendon pain (jumper's knee) weakens the patellar tendon.

A 2024 review notes that several studies found the antibiotic risk small, and a 2025 review says quadriceps tears almost always happen in tendons that were already diseased. Medical conditions are common in people with these ruptures, more so in women, so surgeons are advised to look for one.

Sources 1, 2, 3, 4, 7

How it's recognisedStrong evidence

A tearing or popping feeling, then pain and swelling; difficulty walking because the knee buckles; a dent above the kneecap (quadriceps) or below it (patellar); the kneecap sagging (quadriceps) or riding up into the thigh (patellar); bruising, tenderness and cramping; and being unable to straighten the knee or do a straight-leg raise. A clinician checks whether you can straighten the knee against gravity.

If the tissue at the sides of the kneecap holds, a straight-leg raise may still be possible despite a ruptured patellar tendon, so being able to lift the leg doesn't rule a rupture out. For people who can't lift the straight leg, a newer bedside test picked up every rupture in 113 people at one centre and held up in a small blinded check.

Sources 1, 2, 12, 3, 13

Why they're missed, and what scans showEmerging evidence

They can be overlooked in a busy emergency department. In an older series of 72 ruptures, 28 (38%) were misdiagnosed at first. In 18 complete quadriceps ruptures, only 6 were correctly reported on the first X-ray, even though most X-rays showed signs of it. In 105 reported cases of quadriceps tendons torn in both knees at once, the diagnosis was delayed in 31%, by 65 days on average.

A side-view X-ray usually shows the kneecap out of place: low after a quadriceps tear and high after a patellar tendon tear. Ultrasound and MRI (magnetic resonance imaging) confirm a tear and tell partial from complete. In one hospital audit, ultrasound picked up every rupture but also suggested some that weren't there: 4 of 47 people had surgery that found an intact tendon. MRI was right every time.

Sources 8, 9, 14, 15, 1, 2, 3, 16

Without repair, or if repair is lateEmerging evidence

A complete tear doesn't restore straightening by itself. Tears treated 3 weeks or more after the injury (chronic tears) are harder to repair and do worse, with failure rates of 0 to 33% and often a knee that won't fully straighten by itself. After about a month the tendon may have shortened, sometimes needing a graft.

Sources 1, 2, 4, 17

After a knee replacement

A quadriceps tear after a knee replacement (in about 0.1 to 1.1% of replacements) is a different problem, with high complication rates whatever the technique, and your surgical team will plan its treatment. This guide's warning signs still apply.

Source 4

What helps, and how strong the evidence is

Complete tears need surgeryStrong evidence

A complete tear almost always needs surgical repair to restore straightening. One NHS trust calls repair the standard treatment for a patellar tendon rupture, and reviews agree for both tendons.

Sources 1, 2, 18, 3, 4

Sooner is better, though the cut-off is uncertainEmerging evidence

Results are better when the repair is done soon. Immediate repairs did better than late ones in a 1981 series; quadriceps repairs within a week gave similar results whatever the technique, while delayed repairs did worse; and a review of 319 quadriceps repairs found the worst results after delayed repair. Chronic tears, treated 3 weeks or more after the injury, are harder to fix and do worse.

One 16-year series from a UK trauma centre found no difference between early and delayed surgery, so the exact cut-off is uncertain, but no source recommends waiting.

Sources 1, 2, 9, 19, 5, 17, 20

Partial tears with straightening intact: a brace and rehabEmerging evidence

A partial tear that leaves the knee able to straighten is usually treated in a brace or splint holding the knee straight for 3 to 6 weeks, with crutches and straight-leg raises, then gradual bending and strengthening. In athletes with partial tears, 97% started without surgery and 58% never needed it, with 70 to 89% returning to sport after conservative care; another review of partial patellar tendon tears found 92% returned to sport after either approach. A large partial tear, or one in a worn tendon, may still be repaired.

Sources 1, 2, 3, 21, 22

The operationEmerging evidence

Stitches through holes drilled in the kneecap, or anchors in the bone, sometimes with wire, cable or tape to protect the repair, and occasionally a graft if the tendon has shortened. Techniques give similar results. Re-tears are uncommon: 2% after quadriceps repair in a review, and 3% in 504 patellar tendon repairs in the US military, though one 10-year follow-up found 8% after quadriceps repair, with worse scores afterwards.

Sources 1, 2, 3, 23, 4, 5, 24, 25

Rehab after repair: every team's protocol differsStrong evidence

Protocols differ, especially on how long the brace stays locked straight, how fast bending is allowed, and when weight-bearing, running and sport resume. Four examples:

One NHS trust: the brace is normally locked straight for the first 2 to 8 weeks, with bending increased gradually as the surgeon directs, and exercises 3 times a day.
Another NHS trust: locked straight at first; from week 2 a hinged brace allowing 0 to 100 degrees for walking, one crutch by week 5, and full weight with the brace off from week 6. Resisted straightening from month 3, impact from month 4, and contact sport from month 6, after tests.
A US protocol: locked straight at all times except for exercises until week 6, with full weight in the locked brace by week 4; light running at 16 to 24 weeks, and sport at 6 to 8 months.
The American Academy of Orthopaedic Surgeons (AAOS): toe-touch weight at first, about half your weight by 2 to 4 weeks and full weight by 4 to 6 weeks, with some surgeons allowing early movement. Full recovery takes at least 4 months after a quadriceps repair and about 6 after a patellar repair, and many people need 12 months to reach all their goals.

Sources 18, 26, 27, 2, 1

Moving early or keeping it still: the evidence points both waysMixed evidence

A network meta-analysis of 23 observational studies (709 people) found that early movement went with more complications than keeping the knee still for at least 6 weeks. But in a series of 50 repairs protected by an extra stitch, a regimen of controlled movement and full weight from 7 to 10 days, and walking without a brace from 6 weeks (reached at 7.7 weeks on average), led to no complications, and all 50 had good or excellent results. A 2024 review calls early movement safe and feasible after reinforced repairs, but says the best protocol isn't known.

Neither approach has been tested against the other in a trial. Your surgeon chooses, based on your repair.

Sources 28, 29, 3

Return to sport and workEmerging evidence

Across 48 studies (1,135 repairs), 89% returned to sport after a patellar and 90% after a quadriceps tendon repair, 81% and 70% at the same level, and about 96% returned to work. In 20 people after early patellar tendon repair, running came at an average of 9 months and same-level sport at 17 months, and people over 40 or with a body mass index (BMI) over 25 did less well; in 46 others, sport resumed at an average of 5.9 months.

Professional players fare less well: in the US National Football League (NFL), 19 of 24 players with patellar tendon ruptures returned to at least one game, and 7 of 14 with quadriceps tears; in the National Basketball Association (NBA), 3 of 12 players with patellar tendon tears never returned.

Sources 30, 31, 32, 33, 34, 35

Lasting effects are commonEmerging evidence

Weakness often lasts. In one series of quadriceps repairs, 53% had a thigh strength deficit of more than 20%, and more than half of the most active people couldn't return to their recreational sport. In 38 people aged 40 or under after quadriceps repair, 63% of athletes returned to sport and 32% had lasting pain and stiffness. In 141 people a year after repair, results were similar for the two tendons, worse in women and in those with poor scores before surgery, and a quarter rated their symptoms unacceptable. In the long term most score well, but a re-tear worsens results.

Sources 36, 37, 38, 39, 25

How much pain is OK while you exercise?

0 to 3, settled by the next morning, and never a pop or a lost straight-leg raiseEmerging evidence

After repair, one NHS trust's guide stops a strength set when pain rises more than 2 to 3 points out of 10 above your usual level, and a US protocol moves on from the protection phase only when pain with daily activities in the brace is 0 to 1 out of 10 and swelling has largely settled. So keep pain during exercise at about 0 to 3 out of 10, and check it has settled by the next morning, the same ceiling our ACL guide uses after surgery.

Swelling is the other gauge: if the knee swells after a session, you've done too much.

Your team's limits on the brace, bending and weight-bearing come before any pain rule. A pop, suddenly being unable to lift the straight leg, or the kneecap changing position is never part of the rule: contact your team the same day.

Sources 26, 27, 40, 1, 2

The exercise plan: 4 stages

Start at the first stage. Each move opens a full guide with a 3D demo.

Stage 1

Protect the repair (typically weeks 0 to 6, as your team allows)

As your team allows. The weeks in each stage are typical ranges from two NHS trusts, a US protocol and the AAOS, not targets: move on by your team's checks. Wear the brace exactly as instructed, locked straight for walking at first (for 2 to 8 weeks in one NHS trust, with a hinged range from week 2 in another). Use crutches with the weight you've been allowed. Rest with the leg raised and the knee straight, with nothing under the knee. No resisted straightening, and no bending beyond your team's limit. These exercises are from an NHS trust leaflet, done 3 times a day.

Quad set (static quads) demonstrated on the 3D figure

3D demoQuad set (static quads)Beginner · No equipment

Hold 10 s; 10 times, 3 times a day · An NHS leaflet's dose. Rest the heel on a rolled towel, with nothing under the knee

Harder: Straight-leg raise

Straight-leg raise demonstrated on the 3D figure

3D demoStraight-leg raiseBeginner · No equipment

Lift about 10 cm and hold 10 s; 10 times, 3 times a day, in the brace · An NHS leaflet's dose. One NHS trust starts these with help and expects them without help by week 5

Easier: Quad set (static quads) · Harder: Leg extension

Wall side leg lift (standing side kick at the wall) demonstrated on the 3D figure

3D demoWall side leg lift (standing side kick at the wall)Beginner · A wall

10 each side, standing, holding a support, brace on · An NHS leaflet's standing hip exercise

Harder: Lateral band walk, band at the feet

Standing band hip extension demonstrated on the 3D figure

3D demoStanding band hip extensionBeginner · A band + An anchor point

10 each side, standing, brace on, without the band at first · An NHS leaflet's standing hip extension

Harder: Back extension on a 45-degree bench

Slow calf raise demonstrated on the 3D figure

3D demoSlow calf raiseBeginner · A wall

10 slow raises on both feet, holding a worktop · Editorial dose; standing heel raises are in a US protocol's first phase

Easier: Seated bent-knee calf raise (soleus raise) · Harder: Standing dumbbell calf raise

Ankle circles demonstrated on the 3D figure

3D demoAnkle circlesBeginner · No equipment

10 slow circles each way, often · Ankle exercises are in an NHS trust's first phase

Harder: Ankle CARs (controlled articular rotations)

Move on when: Your team frees the brace, and you can lift the straight leg without the knee sagging. One NHS trust's 6-week checks: a sag of 5 degrees or less, the knee bending to 100 degrees or more, and full weight.

Follow along: a timer, a cue and the next move, one step at a time.

Stage 2

Protected movement (typically weeks 2 to 12, as your team allows)

As your team allows. Regain bending gradually within the range your team sets: one NHS trust allows 0 to 100 degrees in the brace from week 2 and no limit from week 6, and a US protocol aims for 90 degrees by week 10 and full movement by week 20. Wean off the brace and crutches (around 6 to 10 weeks), walk normally, and add shallow strength and balance work. Doses are editorial unless marked.

Supine heel slide demonstrated on the 3D figure

3D demoSupine heel slideBeginner · No equipment

10 slow repetitions, within your allowed range · Knee bending lying down is in an NHS leaflet once bending is allowed

Harder: Hip windshield wipers

Standing hamstring curl demonstrated on the 3D figure

3D demoStanding hamstring curlBeginner · A wall

10 times, holding a support, within your range, no ankle weight yet · An NHS leaflet's standing knee bend

Harder: Slider hamstring curl

Stationary cycling demonstrated on the 3D figure

3D demoStationary cyclingBeginner · Cardio machine

10 to 15 min, no or low resistance · Once the knee bends far enough to pedal round; one NHS trust starts from week 2, rocking back and forth if a full turn isn't possible

Harder: Air bike intervals

Sit squat (partial squat) demonstrated on the 3D figure

3D demoSit squat (partial squat)Beginner · No equipment

3 sets of 10, between straight and about 40 degrees of bend · A US protocol's range for weeks 6 to 10

Harder: Bodyweight squat

Single-leg stand demonstrated on the 3D figure

3D demoSingle-leg standBeginner · A wall

3 holds of 30 s, holding a support at first · Balance work is in this phase in both protocols

Easier: Tandem stance and heel-to-toe walk · Harder: Single-leg reach matrix

Treadmill walking demonstrated on the 3D figure

3D demoTreadmill walkingBeginner · Cardio machine

10 min, building gradually · Treadmill walking is in a US protocol's weeks 6 to 10

Harder: Treadmill jogging

Move on when: You walk normally without the brace, can lift the straight leg with little or no sag, the knee bends to about 90 degrees or more, and swelling is slight (a US protocol's checks).

Follow along: a timer, a cue and the next move, one step at a time.

Stage 3

Strength (typically months 3 to 5, as your team allows)

As your team allows. Build thigh strength on separate days: one NHS trust trains strength 3 to 4 times a week, with at least 24 hours between strength days. Keep squat depth moderate at first: a US protocol keeps this kind of work to about 70 degrees of bend for 16 weeks, and nothing deeper than 90 degrees until 6 months. Add resisted straightening only from about month 3, and gradually (an NHS trust). Doses are editorial unless marked.

3D demoStep-upBeginner · A step

3 sets of 8 to 10 each leg · In both protocols

Easier: Low step-up · Harder: Dumbbell step-up

3D demoLeg pressBeginner · Strength machine

3 sets of 10 to 12, within the depth your team allows · In both protocols. Never snap into a hard lockout

Harder: Bodyweight squat

3D demoWall sitBeginner · A wall

3 to 4 holds of 20 to 40 s, shallow · Wall squats are in a US protocol. Breathe normally through the hold

Easier: Straight-leg raise · Harder: Spanish squat (band squat hold)

Seated knee extension (chair) demonstrated on the 3D figure

3D demoSeated knee extension (chair)Beginner · A bench or box + Something with weight

3 sets of 10 to 15, light at first, from about month 3 if your team agrees · An NHS trust adds resisted straightening from month 3

Easier: Quad set (static quads) · Harder: Leg extension

Glute bridge demonstrated on the 3D figure

3D demoGlute bridgeBeginner · No equipment

3 sets of 12

Easier: Pelvic tilt into bridge · Harder: Glute kickback (quadruped hip extension)

Single-leg Romanian deadlift demonstrated on the 3D figure

3D demoSingle-leg Romanian deadliftAdvanced · A dumbbell

3 sets of 8 each leg, fingertips on a wall · One of an NHS trust's later tests

Easier: Dumbbell Romanian deadlift

Move on when: You walk normally, the knee straightens fully by itself, swelling is minimal, and you can hold a single-leg squat to 60 degrees for 5 seconds with good alignment, do 20 single-leg bridges and 10 single-leg sit-to-stands with control (an NHS trust's checks before impact work).

Follow along: a timer, a cue and the next move, one step at a time.

Stage 4

Impact and sport (typically from month 4, as your team allows)

As your team allows. Two-footed then one-footed landings and jumps, running, then agility and sport drills. One NHS trust allows impact from month 4 and contact sport from month 6, once all tests are over 90% of the other leg and the consultant agrees; a US protocol allows light running at 16 to 24 weeks if the thigh is less than 30% weaker than the other, and sport at 6 to 8 months. Doses here are editorial.

Treadmill jogging demonstrated on the 3D figure

3D demoTreadmill joggingIntermediate · Cardio machine

Walk-jog intervals on the flat · Only once your team agrees

Easier: Treadmill walking · Harder: Sprint intervals

3D demoPogo hopsIntermediate · No equipment

Short sets of 10 to 20, two-footed · Like an NHS trust's two-footed landing drills

Easier: Ankle bounces (mini pogo) · Harder: Single-leg pogo hops

Snapdown to athletic landing demonstrated on the 3D figure

3D demoSnapdown to athletic landingBeginner · No equipment

2 to 3 sets of 5, freezing each landing

Harder: Box drop landing

Single-leg hop and stick demonstrated on the 3D figure

3D demoSingle-leg hop and stickIntermediate · No equipment

3 sets of 5 each leg, small hops first · Get clearance first; like an NHS trust's single-leg landings

Easier: Standing broad jump with stuck landing · Harder: Alternate-leg bounding

Split squat demonstrated on the 3D figure

3D demoSplit squatIntermediate · No equipment

3 sets of 8 each leg, heavier · A split squat is one of an NHS trust's tests

Easier: Bodyweight squat · Harder: Reverse lunge

Shuttle runs demonstrated on the 3D figure

3D demoShuttle runsAdvanced · No equipment

Short sets, wide turns first · Like an NHS trust's agility drills

Easier: Treadmill jogging

Move on when: Your team clears you: strength at least 85 to 90% of the other leg, good endurance and balance, and no swelling (the AAOS), or all tests over 90% of the other leg (one NHS trust). Keep two strength sessions a week afterwards, because thigh weakness often lasts.

Follow along: a timer, a cue and the next move, one step at a time.

What to change for now

Typical timings, which your team may change

These come from two NHS trusts, a US protocol and the AAOS, and they differ. They are typical ranges, not deadlines; your own team's timings come first.

Brace locked straight: 2 to 8 weeks in one NHS trust; a hinged range of 0 to 100 degrees from week 2 in another; locked to week 6 in a US protocol.
Weight: toe-touch at first, about half by 2 to 4 weeks and full by 4 to 6 weeks (the AAOS); full weight in the locked brace by week 4 (a US protocol).
Brace and crutches off: around 6 to 10 weeks.
Resisted straightening: from about month 3.
Running and impact: from month 4 (an NHS trust) or 16 to 24 weeks (a US protocol), once strength allows.
Contact sport: from month 6 (an NHS trust) or 6 to 8 months (a US protocol), after tests.
Full recovery: at least 4 months after a quadriceps and about 6 after a patellar tendon repair; many people need 12 months to reach all their goals.

Sources 18, 26, 27, 1, 2

Resting, and stairs

Rest with the leg straight and nothing under the knee, so it doesn't stiffen in a bent position. On stairs, an NHS trust's sequence going up is the good leg, then the operated leg, then the crutch; coming down, the crutch, then the operated leg, then the good leg, always using the rail.

Sources 18, 27

If you have a condition that weakens tendons

Medical conditions are common in people with these ruptures, so it's worth asking your GP whether anything, such as kidney disease, gout, diabetes or a steroid medicine, needs attention to protect your other tendons.

Sources 7, 4, 1

Positions to swap, and why

Habit or position	Why it matters	Instead
Taking the brace off or unlocking it before you're told	The brace protects the repair in the first weeks.	Wear it as instructed, and ask your team if it rubs.
Deep squats, kneeling, or bending past your allowed range early on	Protocols build bending gradually; one keeps squats to about 70 degrees for 16 weeks, and nothing deeper than 90 degrees until 6 months.	Stay inside your range.Try: Supine heel slide
Resting with a pillow under the knee	It stops the knee straightening; the leaflets say rest with the knee straight and nothing under it.	Rest the heel on a rolled towel, and do quad sets.Try: Quad set (static quads)
The leg extension machine or ankle weights early on	One NHS trust adds resisted straightening from about month 3, and a US protocol allows no active straightening in the first 6 weeks.	Quad sets and straight-leg raises in the brace.Try: Quad set (static quads)
Running, jumping or sport before you're cleared	Impact usually starts at about 4 months, and contact sport at about 6 months or later.	Cycling, then the elliptical trainer.Try: Stationary cycling
Going up stairs leading with the operated leg	An NHS trust's sequence: up with the good leg first, down with the operated leg first, using the rail and your walking aid.	The trust's sequence.
Stopping strength work when you're discharged	More than half had a thigh strength deficit of more than 20% years later in one series.	Two strength sessions a week.Try: Leg press
Ignoring a new pop, or losing the straight-leg raise	The repair may have torn again.	Contact your team the same day.

Routines to follow

Low-impact leg workout (no jumping)

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 step

Knee control warm-up

A 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 band

More moves for this area

Questions people ask

How do I know if I've torn my patellar or quadriceps tendon?

Usually there's a pop or tearing feeling at the front of the knee, then pain, swelling and a knee that buckles. You can't straighten the knee or lift the straight leg off the bed, and there may be a dent above or below the kneecap. Get it checked the same day.

Can you walk with a torn patellar tendon?

Some people can, with difficulty, because the knee buckles or gives way, though most can't put weight on the leg. If the tissues at the sides of the kneecap hold, a straight-leg raise may still be possible, which is partly why these injuries are missed. Get a suspected rupture examined the same day.

Do I need surgery?

For a complete tear, almost always: it's the standard treatment to restore straightening. A partial tear that leaves the knee able to straighten can be treated in a brace holding it straight for 3 to 6 weeks, then rehab.

How soon does it need to be repaired?

Usually within days. Repairs done early do better, and after about a month the tendon may shorten and need a graft. Tears treated 3 weeks or more after the injury are harder to fix.

What's the difference between the two?

The quadriceps tendon is above the kneecap and tends to tear in people over 40, often with an underlying condition; the patellar tendon is below it and tends to tear in younger, sporty people. Both stop the knee straightening, and both are repaired in similar ways.

How long is recovery?

Most repairs are nearly healed by 6 months, but many people need about 12 months to reach all their goals. Impact work usually starts around 4 months and contact sport at about 6 months or later, depending on your team's protocol.

How long will I wear a brace?

Usually about 6 weeks, sometimes up to 8 to 10, starting locked straight and then gradually allowed to bend. Your team decides.

When can I run or play sport again?

Running usually starts at about 4 months in one NHS trust's guide and at 16 to 24 weeks in a US protocol, once strength allows. About 9 in 10 people return to sport, and 7 to 8 in 10 to the same level.

Will my knee be as strong as before?

Often not completely. In one series, more than half still had a thigh strength deficit of more than 20%, and about a third of people aged 40 or under had lasting pain or stiffness after a quadriceps repair. Keeping up strength work after discharge helps.

Why did my tendon tear?

Usually a heavy load on a bent knee, such as a stumble or awkward landing, often on a tendon already weakened by age, tendon disease, a condition such as kidney disease, diabetes, rheumatoid arthritis or lupus, or steroids. Some antibiotics carry a small extra risk.

Can it happen again?

Re-tears are uncommon, about 2 to 3% in large studies, though one long follow-up found 8% after quadriceps repair. Because underlying conditions are common, it's worth asking your GP about anything that weakens tendons.

I've had a knee replacement and torn my quadriceps tendon. Is this guide for me?

Only for the warning signs. A tear after a replacement is rarer and harder to treat, and your surgical team will plan it. Our knee replacement guide covers recovery after the replacement itself.

When to get help first

Get urgent medical help if

See a doctor or physiotherapist if

Understand it

What the tendons do, and what a rupture isStrong evidence

How it happens and who gets itEmerging evidence

What raises the riskEmerging evidence

How it's recognisedStrong evidence

Why they're missed, and what scans showEmerging evidence

Without repair, or if repair is lateEmerging evidence

After a knee replacement

What helps, and how strong the evidence is

Complete tears need surgeryStrong evidence

Sooner is better, though the cut-off is uncertainEmerging evidence

Partial tears with straightening intact: a brace and rehabEmerging evidence

The operationEmerging evidence

Rehab after repair: every team's protocol differsStrong evidence

Moving early or keeping it still: the evidence points both waysMixed evidence

Return to sport and workEmerging evidence

Lasting effects are commonEmerging evidence

How much pain is OK while you exercise?

0 to 3, settled by the next morning, and never a pop or a lost straight-leg raiseEmerging evidence

The exercise plan: 4 stages

Protect the repair (typically weeks 0 to 6, as your team allows)

Protected movement (typically weeks 2 to 12, as your team allows)

Strength (typically months 3 to 5, as your team allows)

Impact and sport (typically from month 4, as your team allows)

What to change for now

Typical timings, which your team may change

Resting, and stairs

If you have a condition that weakens tendons

Positions to swap, and why

Routines to follow

Low-impact leg workout (no jumping)

Knee control warm-up

More moves for this area

Questions people ask

Related exercise guides

Other pain guides

Sources