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What is a cruciate ligament tear
The knee has two cruciate ligaments. The anterior cruciate ligament (ACL) stops the shinbone from sliding forward and rotating against the thigh bone; the posterior one (PCL) stops it sliding backwards. The ACL is torn far more often.
The typical mechanism is a sudden pivot or landing without contact: football, skiing, basketball, handball. Many people hear a “pop”, and within a few hours the knee swells because of blood in the joint.
The menisci, cartilage and medial collateral ligament are often injured at the same time. These associated injuries frequently determine treatment more than the ligament itself.
At a glance
- ICD-10: S83.5 — acute tear, M23.5 — chronic instability
- Typical cause: pivoting on the standing leg, landing
- Main symptom: instability — the knee gives way
- Diagnosis: Lachman test and MRI
- Return to pivoting sport after reconstruction: usually 9–12 months
- Without surgery: 3–6 months of rehabilitation
Symptoms of an ACL tear
At the moment of injury
A pop or crack in the knee, sharp pain, inability to keep playing. Within 2–12 hours the knee swells noticeably.
A few days later
The swelling settles and walking is possible, but the knee gives way when turning, going downstairs or changing direction.
See a doctor urgently
The knee is locked and will not straighten, severe swelling, a numb foot, a deformed joint. Then you need to be examined within hours or days.
The posterior cruciate ligament is usually torn by a blow to the front of the shin (for example against a car dashboard) and is often treated without surgery. Similar symptoms occur with a meniscus tear — see meniscus tear.
Diagnosis: tests and MRI
The physician checks stability with the Lachman test, the anterior drawer and the pivot-shift test. MRI shows whether the tear is complete or partial and assesses the menisci, cartilage and bone bruising. An X-ray rules out a bony avulsion.
| Grade | What happens | Usual approach |
|---|---|---|
| I — sprain | Fibres are stretched, the ligament is intact | Rehabilitation |
| II — partial tear | Some fibres are torn, stability is partly preserved | Mostly rehabilitation; reconstruction is discussed if unstable |
| III — complete tear | The ligament is torn through | Rehabilitation or reconstruction depending on instability, age and sport |
If you already have an MRI, send it for a second opinion. If not, we arrange an MRI in Munich.
Can an ACL tear be treated without surgery
Yes, in many patients. In the Swedish randomised KANON trial, young active adults with an acute ACL tear had either early reconstruction or structured rehabilitation with the option of later surgery. At 2 and 5 years the results did not differ, and about half of the rehabilitation group never needed an operation.
- Rehabilitation without surgery fits if the knee does not give way in daily life, there is no large repairable meniscus tear and you do not plan pivoting sports.
- A partial ACL tear is usually treated without surgery.
- The basis is 3–6 months of exercises for thigh strength, balance and knee control; running follows the physiotherapist’s plan.
- If instability persists, reconstruction can still be done later — studies did not show that waiting worsens the outcome.
When ACL reconstruction is needed
ACL reconstruction is usually discussed for recurrent instability, young athletes in pivoting sports, a combined repairable meniscus tear and high occupational demands on the knee. Grafts are most often taken from the hamstring tendons or the patellar tendon.
| Stage after reconstruction | Usual timing |
|---|---|
| Walking without crutches | 2–6 weeks |
| Desk work | 2–3 weeks |
| Standing work / physical work | 2–3 months / 3–6 months |
| Straight-line running | about 3–4 months |
| Pivoting sports | usually after 9–12 months |
For self-paying patients, ACL reconstruction in Germany costs roughly €6,000–10,000 including the hospital stay; the clinic quotes the exact amount after examination and MRI. More on treatment cost.
Prices are approximate. Each clinic sets its own conditions and price: we send your request to several clinics and forward their offers so you can compare.
Regenerative methods for ACL injuries
A complete ACL rupture does not heal with injections: the ligament ends separate and joint fluid hinders healing. PRP is sometimes used as an addition for partial tears, sprains and after reconstruction to support recovery; evidence is still limited. More on PRP therapy.
Regenerative methods are more often helpful for the consequences of the injury: pain from cartilage or meniscus damage and early post-traumatic osteoarthritis. The clinic physician chooses the option based on the MRI.
Who should not have injections and possible risks
Injections are not suitable
Active infection, active cancer, clotting disorders, pregnancy, a recent corticosteroid injection into this knee.
Treatment risks
After an injection: pain and swelling for 1–3 days, rarely infection. After reconstruction: swelling, pain, rarely infection, thrombosis, graft re-rupture, loss of extension.
See a doctor at once
A locked knee, a numb or cold foot, severe calf pain after surgery — these need immediate examination.
Scientific evidence
The randomised KANON trial — early ACL reconstruction versus rehabilitation:
Frequently asked questions about ACL tears
Free knee MRI review
Send your MRI and describe how the injury happened and whether the knee gives way. The coordinator replies within 24 hours; a clinic physician gives an opinion in 1–3 business days.
Send MRI