What complications can occur during above‑knee surgery on the operating table?

Intraoperative Complications During Above-Knee Surgery

The most critical preventable complications during above-knee surgery on the operating table include peripheral nerve injuries (particularly common peroneal nerve in lithotomy position), lower limb compartment syndrome, pressure necrosis over bony prominences, and positioning-related injuries—all of which require meticulous attention to padding, positioning assessment every 30 minutes, and careful patient transfer techniques. 1

Peripheral Nerve Injuries

High-Risk Nerves During Above-Knee Procedures

• Common peroneal nerve injury is the primary concern during lithotomy positioning, which is frequently used for above-knee procedures 1
• The ulnar nerve (when supine), dependent radial nerve (lateral position), and brachial plexus (after prolonged lateral neck flexion) are also at risk 1
• Comprehensive padding of probable nerve injury sites before surgery initiation is essential, with routine assessment every 30 minutes throughout the procedure 1

Prevention Strategies

• Avoid elbow flexion >90° and maintain forearm in neutral or slightly supinated position to minimize cubital tunnel pressure 2
• Prevent arm abduction ≥90° and non-neutral head alignment to avoid brachial plexus injury 2
• Ensure proper padding at all pressure points before surgical draping 1

Compartment Syndrome

Specific Risk with Above-Knee Positioning

• Lower limb compartment syndrome can result from lithotomy position, prolonged intra-abdominal insufflation, or pelvic surgery 1
• The hemilithotomy position specifically increases intracompartmental pressure in the contralateral leg, creating risk of well-leg compartment syndrome 2
• Minimize use of hemilithotomy position when possible to reduce this complication risk 2

Pressure-Related Complications

Tissue Necrosis and Skin Injury

• Elderly patients are at particularly high risk due to friable skin, reduced skin depth and vascularity, and decreased muscle mass 1
• Pressure necrosis typically develops over bony prominences such as the heel during prolonged procedures 1
• Prolonged hypotension may contribute to pressure necrosis development 1

Prevention Measures

• Use adequate padding with emphasis on cushions under osseous prominences 2
• Exercise extreme care during patient transfer between bed and operating table 1
• Avoid razor hair removal; use alternative methods 1
• Take precautions when removing adherent items (diathermy pads, tape, dressings) to prevent skin tears 1
• Monitor contact warming devices carefully as friable skin is more prone to thermal damage 1

Cardiovascular and Hemodynamic Complications

Age-Related Considerations

• Older patients have reduced homeostatic compensation for blood/fluid loss and boluses of intravenous fluids 1
• Age-related alterations in pharmacokinetics render elderly patients sensitive to anesthetic overdose, resulting in myocardial depression and reduced blood pressure homeostasis 1
• Patients aged >65 years have higher mortality with substantial operative blood loss or pre-operative hematocrit <24% 1

Fluid Management

• Avoid prolonged pre-operative fasting; allow clear fluids up to 2 hours before surgery to prevent dehydration 1
• Use restrictive fluid therapy that avoids hypovolemia while replacing pre- and intra-operative losses 1

Thromboembolic Complications

• Proper positioning combined with appropriate fluid therapy and antithrombotic measures reduces peri-operative thromboembolism risk in elderly patients 1
• Consider the patient's mobility limitations and implement prophylaxis accordingly 1

Musculoskeletal Positioning Complications

Joint and Deformity Considerations

• Account for pre-existing conditions including kyphoscoliosis, arthritic joints, and fixed flexion deformities when positioning 1
• Do not remove functional splints if practicable 1
• Special positioning modifications may be required for patients with ipsilateral hip fusion or other joint abnormalities 3, 4

Surgical Site-Specific Issues

• Increased Trendelenburg positioning and episodic foot-of-table flexion may be necessary for optimal exposure in complex cases 3
• Surgeon positioning and handedness can affect surgical accuracy, with less convenient operative positions leading to higher deviation from mechanical alignment 5

Common Pitfalls to Avoid

• Failing to assess nerve injury sites every 30 minutes during prolonged procedures 1
• Inadequate padding before surgical draping begins 1, 2
• Using hemilithotomy position without considering compartment syndrome risk 2
• Rough handling during patient transfer, particularly in elderly patients with friable skin 1
• Neglecting to account for pre-existing joint deformities when positioning 1