Reconstruction of the Posterior Cruciate Ligament (PCL) carries higher complexity than ACL surgery due to two main factors: the close anatomical proximity of the popliteal artery—which increases the risk of rare vascular complications—and the high incidence of concomitant Posterolateral Corner (PLC) injuries. Unaddressed PLC injuries lead to graft failure. Understanding these complications helps patients detect issues early.
Early Complications (First 6 Weeks)
Early complications typically appear during the first six weeks following surgery:
- Popliteal Artery Injury (<1%): The most critical early complication, requiring emergency vascular intervention to save the limb.
- Nerve Injury (1–3%): Sciatic or tibial nerve traction, usually temporary and related to surgical positioning.
- Arthrofibrosis / Knee Stiffness (5–10%): Caused by rapid scar tissue formation or delayed rehabilitation.
- Hemarthrosis (2–4%): Rapid blood accumulation within the joint, managed by aspiration.
- Joint Infection (<1%): More common in uncontrolled diabetic patients, requiring arthroscopic lavage and intravenous antibiotics.
- Deep Vein Thrombosis (DVT) (<0.5%): Prevented through early mobilization, ankle pump exercises, and compressive stockings.
Late & Long-Term Complications
Late complications manifest months to years post-surgery:
- Graft Failure or Recurrent Tear (8–15%): Most commonly caused by an undiagnosed or untreated PLC injury that overloads the new graft, as well as premature return to sports.
- Medial Compartment Osteoarthritis (40–50% over 10 years): Develops over time if the instability remains uncorrected or rehabilitation is incomplete.
- Patellofemoral & Posterior Knee Pain (5–10%): Resulting from altered joint mechanics or quadriceps atrophy.
Key Complications Summary
| Complication | Approximate Rate | Primary Cause |
| Long-Term Osteoarthritis | 40–50% | Untreated PCL instability or incomplete rehabilitation |
| Graft Failure / Retear | 8–15% | Unaddressed PLC injury or premature return to activity |
| Knee Stiffness | 5–10% | Neglecting early physical therapy |
| Chronic Posterior Pain | 5–10% | Residual cartilage degeneration or biomechanical changes |
| Transient Nerve Injury | 1–3% | Intraoperative patient positioning |
| Joint Infection | <1% | Uncontrolled diabetes or surgical contamination |
| Popliteal Artery Injury | <1% | Anatomical proximity during tibial tunnel drilling |
Prevention Strategies
Most PCL complications can be prevented through:
- Accurate Diagnosis: Preoperative MRI, CT scans, and a 30-degree external rotation test to evaluate the PLC.
- Surgical Expertise: Choosing a specialized surgeon who regularly performs PCL reconstructions.
- Medical Optimization: Controlling HbA1c levels below 7.5% prior to surgery.
- Targeted Rehabilitation: Wearing a dedicated dynamic PCL brace and avoiding isolated hamstring contractions to prevent posterior tibial sagging during early healing.
- Gradual Return: Delaying sports return until full quadriceps strength (at least 90% relative to the uninjured limb) is restored, typically around 9–12 months.
When to Seek Immediate Medical Attention
Contact your surgeon or emergency care immediately if you experience:
- Coldness, numbness, or loss of sensation in the foot (vascular emergency).
- Sudden calf swelling, redness, or severe pain (suspected DVT).
- High fever, severe pain, or persistent wound drainage (suspected infection).
- Sudden sensation of the tibia sliding backward after the second month (suspected graft compromise).
frequently asked questions
Complications of PCL Reconstruction FAQ
What are the most common complications following PCL reconstruction?
The most frequent postoperative complications include:
• Residual Posterior Laxity: Mild to moderate posterior tibial sag or graft stretching.
• Knee Stiffness (Arthrofibrosis): Loss of full terminal extension or deep flexion.
• Patellofemoral Pain: Anterior knee pain stemming from quadriceps weakness or altered joint mechanics.
• Hardware Prominence: Localized irritation over tibial screws, staples, or cortical buttons.
Why is neurovascular injury a unique concern during PCL reconstruction?
The popliteal artery, popliteal vein, and tibial nerve pass directly behind the posterior joint capsule, extremely close to the tibial tunnel insertion site. Drilling the tibial tunnel carries a small but critical risk of vascular injury or nerve impingement. Surgeons utilize posterior capsular retractors, intraoperative fluoroscopy, or specialized depth-stop guides to protect these vital structures.
What causes residual posterior laxity or graft stretching after surgery?
Residual laxity can stem from several factors:
• Unrecognized or untreated posterolateral corner (PLC) instability.
• Failure to wear a dynamic PCL brace to counteract gravitational posterior sag during early healing.
• The “killer curve” effect, where mechanical friction at the posterior exit of the tibial tunnel causes graft attrition over time.
• Premature weight-bearing or aggressive early hamstrings activation.
How does a missed posterolateral corner (PLC) injury lead to PCL graft failure?
The posterolateral corner (PLC) acts as the primary restraint to varus forces and external rotation. If a concomitant PLC injury is missed during primary PCL reconstruction, abnormal rotational and varus forces place excessive mechanical stress on the isolated PCL graft, leading to progressive elongation and ultimate graft failure.
What is arthrofibrosis, and how is knee stiffness managed post-PCL surgery?
Arthrofibrosis is an abnormal buildup of dense scar tissue inside the joint capsule, restricting knee motion. Initial treatment involves structured physical therapy and patellar mobilization. If severe motion restriction persists beyond 10–12 weeks despite therapy, arthroscopic lysis of adhesions and gentle manipulation under anesthesia may be required.
What is the incidence of Deep Vein Thrombosis (DVT) after PCL surgery?
Symptomatic DVT occurs in approximately 1% to 3% of patients undergoing PCL reconstruction. Extended surgical duration, tourniquet use, and required postoperative immobilization contribute to venous stasis. Prevention strategies include mechanical compression boots, active ankle pumps, and prescribed blood thinners when indicated.
Why do some patients develop patellofemoral pain after PCL reconstruction?
Anterior knee pain is frequently linked to persistent quadriceps inhibition and altered joint biomechanics. Residual posterior displacement of the tibia increases patellofemoral joint contact pressures during knee flexion. Targeted, progressive quadriceps rehabilitation is essential to correct tracking and relieve pain.
What causes graft fixation hardware complications?
Fixation hardware—such as interference screws, cortical buttons, or tibial post-washers—can occasionally cause palpable skin prominence or soft tissue bursitis, particularly on the anterior aspect of the shin. If hardware remains symptomatic after the graft has fully osseointegrated (usually >1 year post-op), minor surgical removal can be performed.
What is the rate of deep joint infection (septic arthritis) following PCL surgery?
Deep intra-articular infection occurs in less than 1.5% of cases. Symptoms include rapidly progressive swelling, throbbing pain, localized heat, high fever, and cloudy incision drainage. Septic arthritis requires immediate arthroscopic irrigation and debridement alongside intravenous targeted antibiotics.
What red-flag symptoms require immediate medical attention post-surgery?
Contact your surgeon or seek emergency medical evaluation immediately if you experience:
• Severe calf pain, tightness, or pronounced leg swelling (potential DVT).
• Sudden onset of numbness, foot drop, or pale/cold toes (neurovascular compromise).
• High fever (>101°F / 38.3°C) with purulent wound drainage (infection).
• Sudden chest pain, coughing up blood, or shortness of breath (pulmonary embolism emergency).