What ligament or tendon is most likely stretched during lithotomy position, causing postoperative groin pain radiating laterally to the hip with a sensation of dislocation?

Iliopsoas Tendon Stretch During Lithotomy Position

The iliopsoas tendon is the most likely structure stretched during lithotomy positioning, causing postoperative groin pain radiating laterally to the hip with a sensation of dislocation. 1, 2

Anatomical Mechanism of Injury

The lithotomy position creates excessive hip flexion beyond 90 degrees combined with external rotation and abduction, which places significant tension on the iliopsoas tendon as it courses over the anterior hip capsule and acetabular rim. 3, 4 This positioning stretches the hamstring muscle group beyond comfortable range, which can indirectly affect adjacent structures including the iliopsoas complex. 3

Hip flexion beyond 90 degrees specifically increases tension on the iliopsoas tendon and can lead to compression symptoms, particularly when maintained for prolonged surgical procedures. 4, 1 The combination of hip flexion with external rotation creates both stretching of the tendon and increased pressure at the inguinal ligament where the tendon passes beneath. 4

Clinical Presentation Pattern

Patients with iliopsoas tendinopathy present with:

• Persistent groin pain triggered specifically by hip flexion activities (ascending stairs, getting out of chairs, active hip flexion against resistance) 2, 5
• Pain radiating ventromedially along the anterior thigh toward the lateral hip 6, 7
• Sensation of hip instability or "dislocation" due to the tendon's role in hip stability and flexion 2, 8
• Reproducible pain with resisted hip flexion on examination 5
• Pain with hyperextension of the hip as the tendon is stretched over the anterior structures 6

Differential Considerations

While iliopsoas tendinopathy is the primary concern, the American Society of Anesthesiologists notes that stretching the hamstring muscle group beyond comfortable range may increase sciatic neuropathy risk, though this typically presents with pain radiating below the knee rather than laterally to the hip. 3, 1

Femoral nerve compression should be considered if there is associated weakness in knee extension, though this is less likely to produce the sensation of dislocation described. 1 The lateral femoral cutaneous nerve (causing meralgia paresthetica) produces lateral thigh burning without motor symptoms and would not explain the groin pain component. 1

Diagnostic Confirmation

Fluoroscopy-guided iliopsoas tendon sheath injection with local anesthetic and corticosteroid serves as both diagnostic confirmation and initial treatment - significant pain relief after injection confirms the diagnosis. 2 This diagnostic approach has been validated in multiple studies examining iliopsoas pathology after hip procedures. 2, 7

MRI may demonstrate fluid-filled cysts in anatomical proximity to the iliopsoas tendon or signs of tendinitis, though imaging findings do not always correlate with symptom severity. 6, 5

Risk Factors for Lithotomy-Related Injury

Younger patients are at significantly higher risk - the mean age for developing iliopsoas pathology is 54 years compared to 65 years for typical surgical patients. 7 Procedures requiring prolonged lithotomy positioning (>2 hours) increase risk through sustained tendon stretch. 3

The American Society of Anesthesiologists notes that flexibility of the hamstring muscle group is important to assess preoperatively when placing patients in lithotomy position, though no consensus exists on specific degree recommendations for hip flexion to reduce femoral or iliopsoas injury risk. 3

Management Approach

Initial treatment with ultrasound-guided corticosteroid injection combined with physiotherapy resolves symptoms completely in 61% of cases and partially in an additional 13%. 7 This conservative approach should be attempted first given its low risk and reasonable efficacy. 7

For refractory cases (26% of patients who fail conservative management), arthroscopic or endoscopic iliopsoas tenotomy is highly effective when the diagnosis is correct - patients with isolated pain on hip flexion activities and reproducible pain with resisted flexion respond best. 5, 7 Eight out of 24 patients (33%) in one series ultimately required surgical intervention. 7

Prevention Strategies

Maintaining hip flexion within comfortable limits during lithotomy positioning, generally not exceeding 90 degrees, may reduce risk, though the American Society of Anesthesiologists acknowledges no majority consensus was reached on specific degree recommendations. 3, 4, 1 Periodic assessment of hip position during prolonged procedures is recommended. 1

Avoiding stretching the hamstring muscle group beyond the normal range of motion comfortable during preoperative assessment may decrease risk, though again no consensus exists on this recommendation. 3