Posterior cruciate ligament tear (PCL)

Anatomy and function of the posterior cruciate ligament

The posterior cruciate ligament (PCL) runs in the knee joint from the inside of the thigh bone (femur) to the back of the shinbone surface (tibia). Above all, it prevents the shin from sliding backwards relative to the thigh and stabilizes the knee in a flexed position. Together with capsular structures and the posterolateral corner (PLC), it contributes to rotational control and overall stability.

• Primary function: Limiting posterior tibial translation
• Secondary function: rotation control, especially during flexion
• Interaction with posterolateral corner (PLC), collateral ligaments and menisci

Causes and typical accident mechanisms

PCL injuries often occur as a result of direct force on the bent knee or through extreme movements. It is not uncommon for combined injuries to occur, for example involving the posterolateral corner or collateral ligaments.

• “Dashboard Injury”: The front edge of the shin bone hits the dashboard in a car accident
• Falling on the bent knee (e.g. in contact or ball sports)
• Hyperflexion or, more rarely, hyperextension of the knee
• High-speed trauma with ligament and capsule injuries
• Rare: bony avulsion at the tibial PCL insertion (avulsion fracture)

Symptoms and warning signs

The symptoms vary depending on the severity and accompanying injuries. Some patients initially only notice pain and swelling, others report feelings of instability, especially when walking downhill or climbing stairs.

• Swelling of the knee (joint effusion) in the first few hours/days
• Pain in the back of the knee or diffuse
• Feeling of instability, “bending,” unsteady stance with the knee bent
• Pain when descending/downhill, sitting for long periods or bending knees
• Restricted movement, limping

Warning signs that should be clarified by a doctor are pronounced instability, pain at rest, significant limitation of movement, persistent swelling or suspicion of a combination injury.

Diagnostics: clinical tests and imaging

Diagnosis is based on history, physical examination and imaging. Important clinical tests examine the posterior drawer and signs of posterior instability. Imaging procedures differentiate the severity, identify accompanying injuries and guide the treatment decision.

• Clinical tests: posterior drawer test, posterior sag sign (tibia “sag”), quadriceps active test, dial test (with PLC involvement)
• X-ray: to rule out bony injuries; If necessary, stress test X-ray (instrumented) to quantify posterior translation
• MRI: Standard for assessing PCL fibers, menisci, cartilage and collateral ligaments
• Ultrasound: supplementary for effusion or soft tissue injuries
• Gait analysis/functional diagnostics: assessment of resilience and muscle coordination

A careful differential diagnosis excludes injuries to the anterior cruciate ligament, collateral ligaments, posterolateral corner, meniscal tears, and osteochondral lesions.

Severity and accompanying injuries

The severity depends on the extent of the posterior displacement of the tibia and the structures involved. It influences the choice between conservative and surgical therapy.

• Associated injuries: posterolateral corner (PLC), lateral/medial ligament, menisci, bony avulsions
• Chronic instability may contribute to anteromedial/medial gonarthrosis and patellofemoral joint overload

Conservative therapy: first approach for many PCL injuries

For most isolated partial PCL tears (grades I–II) and selected complete tears without relevant associated injuries, conservative treatment is the first choice. The goal is functional stability through tissue healing, muscular balance and coordination.

• Acute phase (0–2 weeks): relief from pain, cooling, elevation, anti-inflammatory measures; Crutches if necessary
• Splint: special PCL orthoses with dynamic anterior support to keep the tibia in an anterior position
• Load build-up: early functional, pain-adapted; Avoiding back drawer situations
• Physiotherapy: Focus on quadriceps activation, core and hip stability; Avoid hamstring-dominant exercises in the early phase
• Proprioception and coordination: start early, increase depending on the sport
• Everyday life: controlled flexion angles (e.g. avoid excessively deep squatting at the beginning)

Conservative therapy is planned in a structured manner over several months. Precise exercise control is crucial to avoid overload and persistent posterior translation.

Surgical therapy: indications and procedures

Surgery is considered if there is significant instability, if important accompanying structures are injured or if conservative measures do not achieve sufficient functional stability. The decision is made individually based on findings, activity level and goals.

• Absolute/clear indications: bony avulsion (avulsion fracture) at the base of the tibia, PCL tear with pronounced instability (grade III), combined injuries with PLC/collateral ligaments
• Relative indications: persistent instability and functional deficits despite consistent conservative therapy
• Timing: acute/subacute for refixation of avulsions; reconstructive, usually after swelling and movement gain

Operational options:

• Avulsion osteosynthesis: Refixation of the bony avulsion
• Arthroscopic PCL reconstruction: Replacement of the ligament with tendon graft (often semitendinosus/gracilis or quadriceps tendon); single or double bundled depending on the findings
• Selective augmentation/refixation of preserved fibers in individual cases
• Accompanying stabilization: care of the posterolateral corner and collateral ligaments in combined injuries

As with all ligament surgeries, there are benefits and risks. Realistic expectation management is important; The aim is to achieve resilient stability that is suitable for everyday use and sports, not the guarantee of a “return to the way it was before”.

Follow-up treatment and rehabilitation

Rehabilitation is a central success factor – after both conservative and surgical treatment. It takes place in phases, closely accompanied by physiotherapy and medical checks.

• Driving: only when safe emergency braking is possible without pain and no medication restrictions - to be checked individually
• Office work: usually possible after a few days; physical work later depending on the load
• Return to sport: depending on the injury and therapy, usually after 4-9 months, contact sport later

Regenerative processes: possibilities and limits

Biological procedures such as autologous blood preparations (e.g. PRP) are being discussed as a supplement to conservative therapy. To date, there is limited evidence for isolated posterior cruciate ligament tears. In selected cases, adjuvant use may be considered to support the healing environment. However, a standard recommendation cannot be derived from the current data situation.

Correct indications, mechanical stability (e.g. splint) and a structured rehabilitation program remain crucial for success.

Prognosis, everyday life and prevention

With consistent therapy, many patients achieve good stability suitable for everyday life and sports. The prognosis depends on the severity, concomitant injuries, adherence to treatment and muscular control. Chronic, untreated instabilities can change the mechanics of the knee joint and promote long-term degenerative changes.

• Everyday life: early, controlled activity is beneficial; Avoid sudden deep flexions initially
• Sport: gradual build-up with test criteria (strength symmetry, jump and change of direction tests, freedom from symptoms)
• Ability to work: depending on the job profile – determine individually
• Prevention: sport-specific technique training, quadriceps and hip strengthening, core stability, adequate footwear

Possible complications and risks

Overall, complications are rare, but should be known. A serious explanation includes both conservative and operational risks.

• Persistent instability or pain on exertion
• Restriction of movement, v. a. Flexion/extension deficit due to inadequate rehabilitation
• Anterior knee pain syndrome with insufficient quadriceps function
• During surgery: infection, thrombosis, scar problems, graft failure, neurovascular injury (rare)

PCB vs. ACL: important differences

The mechanism and treatment of a posterior cruciate ligament tear often differs from that of an anterior cruciate ligament tear. Isolated PCL injuries often respond well to conservative measures, whereas surgical reconstruction is more often discussed for ACL injuries - depending on the activity profile and instability.

• Mechanism: PCL often caused by direct impact trauma to the bent knee; ACL more likely due to rotation/valgus stress
• Symptoms: PCL instability is often noticeable when walking downhill; ACL instability is more likely when changing direction
• Therapy path: PCB initially conservative, ACL differentiated; each individual decision

Your appointment in Hamburg

Would you like a well-founded assessment of a posterior cruciate ligament tear? In our practice at Dorotheenstrasse 48, 22301 Hamburg, we offer structured diagnostics and a personal therapy concept - conservative, differentiated and tailored to your goals.