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Positioning & Nerve Injury

For the reconstructive urologist, positioning is the preoperative decision with the highest ratio of complication-severity to time-spent-deciding. A mis-padded lateral nephrectomy position produces a brachial plexus injury the patient never forgets; a five-hour exaggerated lithotomy in a robotic prostatectomy produces well-leg compartment syndrome that ends in fasciotomy or amputation; a steep-Trendelenburg robotic case without proper shoulder protection produces postoperative visual loss. These are not theoretical: they are the dominant non-urologic morbidities of urologic surgery, and they are almost entirely preventable.

This article covers the positions used in urologic surgery — supine, lithotomy (low / standard / exaggerated), lateral decubitus, prone, prone jackknife, prone split-leg, Galdakao-modified Valdivia, and steep Trendelenburg — with the specific nerve, compartment, and pressure risks of each, and the mitigation steps that keep the position from becoming a complication.

See also: Pelvic Neuroanatomy, Nerve Blocks, ERAS.

General Principles​

Five principles govern every urologic position:

  1. Natural range of motion only. Never force a joint beyond the patient's preoperative awake range — extremes of hip, shoulder, and neck produce nerve stretch.
  2. Padding over every bony prominence. Heels, sacrum, greater trochanter, elbow, occiput, lateral malleolus. Pressure ulcer is the most common injury and is underreported.
  3. Arms at the sides, neutrally tucked, whenever possible. Abduction beyond 90° puts the brachial plexus at risk.
  4. Check the position after the drapes go on — then again every 2 hours. Drift under gravity is a documented cause of compartment and nerve injury.
  5. Document the check. A written intraoperative positioning check is both a patient-safety and medicolegal best practice.

Supine​

Setup. Patient lies face-up on the OR table. Arms either tucked at sides (standard for pelvic and MIS work) or on padded arm boards abducted ≤90° (open abdominal work). Head on pillow, neutral neck, heels padded, bilateral lower-extremity SCDs.

Urologic applications. Robotic radical prostatectomy (with Trendelenburg), partial nephrectomy via transperitoneal access, SP supine anterior retroperitoneal access (SARA), radical cystectomy, urethroplasty with separate leg access, abdominal urinary diversion.

Key risks:

  • Ulnar neuropathy — compression at the cubital tunnel when the arm is tucked with the elbow extended; supinate the forearm (palm up) rather than pronating (palm down) to offload.[1][2]
  • Heel pressure ulcer — pad both heels; elevate off the table with a foam wedge or heel-suspension device.
  • Brachial plexus stretch — arm abduction >90° or shoulder extension; avoid.
  • Occipital alopecia — rare; reposition the head every 30 min for cases >4 h.

Lithotomy — Low, Standard, and Exaggerated​

Lithotomy is the position with the highest rate of positioning-related nerve injury in urology.[3][4] Three subtypes are distinguished by hip and knee angles:

VariantHip flexionKnee flexionTypical use
Low lithotomy40–60°80–100°Cystoscopy, TURP, robotic RP (leg access for TAP/analgesia)
Standard lithotomy80–100°80–100°Vaginal surgery, sling placement, perineal urethroplasty
Exaggerated (high) lithotomy110–140°≥90°Posterior urethroplasty, York-Mason, combined abdominoperineal cases

Specific Nerve Risks​

  • Common peroneal nerve — compressed against the fibular head by stirrup posts. Incidence 0.03–1.5% in lithotomy.[3][5] Presents as foot drop. Pad generously and use boot-style Allen stirrups rather than candy-cane.
  • Femoral nerve — injured by excessive hip flexion or abduction (stretch at the inguinal ligament) or by self-retaining retractor blades pressing on the psoas. Presents as quadriceps weakness and saphenous sensory loss.[6]
  • Sciatic nerve — injured by excessive hip flexion with knee extension (posterior thigh stretch).
  • Obturator nerve — injured by extreme hip abduction or by obturator fossa retraction.
  • Lateral femoral cutaneous nerve — compressed at the ASIS; produces meralgia paresthetica.
  • Saphenous nerve — compressed at the medial tibial plateau by leg supports.

Well-Leg Compartment Syndrome (WLCS)​

The feared complication of lithotomy. Incidence rises steeply with lithotomy time:[7][8]

  • Under 2 h: very rare
  • 2–4 h: infrequent
  • >4 h: significantly increased — widely cited as the threshold at which leg-down / reposition intervals become mandatory
  • >5 h: high risk; documented cases of fasciotomy and amputation

Mechanism. Elevated leg → compromised arterial inflow to lower leg → ischemia-reperfusion on return to supine → compartment pressure rise.

Mitigation:

  • Limit pure lithotomy time. Position supine for abdominal portions of long cases; move to lithotomy only when needed.
  • Intermittent leg-down breaks every 2–3 h for cases projected >4 h.
  • Boot-style stirrups (Yellowfin, Allen Hug-U-Vac) with heel support — calf-support stirrups are the leading culprit.
  • Avoid tight calf straps and external wraps.
  • Limit Trendelenburg with lithotomy — steep tilt combined with lithotomy compounds venous back-pressure.
  • Vigilance postoperatively — pain out of proportion, tense compartments, altered sensation warrant urgent evaluation.

Exaggerated Lithotomy (Posterior Urethroplasty)​

The setup that delivers the most lithotomy-associated complications per hour. Rhabdomyolysis rate approaches 10% in cases >5 h in historical urethroplasty series — one of the arguments for the prone jackknife alternative in salvage posterior urethroplasty.[9]

Trendelenburg — Steep (30–45°) for Robotic Pelvic Surgery​

Robotic radical prostatectomy, cystectomy, and deep pelvic reconstruction are performed in steep Trendelenburg (30–45° head-down), typically combined with low lithotomy. This position produces predictable physiologic and positional challenges.

Physiologic effects:

  • Increased intracranial pressure and intraocular pressure
  • Decreased pulmonary functional residual capacity; increased airway pressure
  • Venous congestion (facial, conjunctival, laryngeal edema)
  • Difficult extubation planning; airway edema can delay safe extubation

Positional risks:

  • Patient slide — the principal mechanical risk; mitigated by anti-slide mattress (gel-foam or viscoelastic), shoulder braces used cautiously (see brachial plexus caveat), or vacuum/bean-bag positioners. Avoid rigid shoulder braces if feasible — they are the leading cause of brachial plexus injury in robotic prostatectomy.[10]
  • Postoperative visual loss (POVL) — rare but devastating; ischemic optic neuropathy is the mechanism. Associated with prolonged steep Trendelenburg (>5 h), blood loss, hypotension, anemia.[11][12]
    • Mitigation: limit Trendelenburg time, maintain adequate MAP, avoid direct pressure on the globe, keep the head level or slightly elevated intermittently if the surgical step allows, and check the eyes after draping.
  • Corneal abrasion — always tape the eyes closed; goggles if prolonged.
  • Cerebral edema — rare but documented in prolonged cases.
  • Laryngeal edema — check cuff leak before extubation after >4 h of steep Trendelenburg.

ASA practice advisory recommends staged repositioning (brief return toward level) during prolonged (>4 h) steep-Trendelenburg cases and postoperative ophthalmologic evaluation if POVL symptoms develop.[11]

Lateral Decubitus — Flank Position​

Setup. Patient positioned with the operative side up. Kidney rest elevated and table flexed at the iliac crest level to open the space between iliac crest and 12th rib. Down-leg flexed, up-leg extended with a pillow between the legs. Axillary roll placed caudal to the axilla (not in it) to offload the brachial plexus. Arms supported on a stacked arm rest with neutral shoulder position.

Urologic applications. Open radical nephrectomy, open partial nephrectomy, adrenalectomy, retroperitoneal lymph node dissection (RPLND), open pyeloplasty, laparoscopic retroperitoneal nephrectomy, PCNL (standard prone variant superseded in many centers).

Key risks:

  • Brachial plexus injury (up-side) — traction from shoulder or cephalad pull; caused by inadequate arm support or tape pulling on the shoulder.
  • Brachial plexus injury (down-side) — direct compression from inadequate axillary roll position. Roll goes caudal to the axilla, supporting the chest wall — not under the axilla itself.
  • Common peroneal nerve (down-side) — compressed between the fibular head and the table; pad the fibular head.
  • Rhabdomyolysis — reported in long lateral cases, particularly with obese patients and kidney-rest pressure on the flank.
  • Pressure injury to the down-side greater trochanter, knee, and lateral malleolus.
  • Eye injury (down-side eye) — pressure from bean-bag or head-holder; check eye position after positioning.
  • Break-down of the table — aggressive flexion can stretch the intercostal neurovascular bundle.

Prone​

Setup. Patient face-down on chest and pelvic supports (Wilson frame, Jackson table, or gel bolsters). Arms either tucked at sides or on arm boards with shoulders abducted ≤90° and elbows flexed ~90° ("Superman"). Head on foam donut or prone head-holder with face and eyes free of pressure. Abdomen free to allow ventilation and decrease IVC compression.

Urologic applications. Percutaneous nephrolithotomy (classic prone), posterior urethroplasty (prone jackknife variant), York-Mason transanal / trans-sphincteric approach for rectourethral fistula.

Key risks:

  • Ocular injury / POVL — direct pressure on the globe is the feared scenario. Check eye position after every repositioning; head-holder must allow free visualization of the eyes.
  • Brachial plexus injury — shoulder abduction >90°.
  • Ulnar neuropathy — elbow compression.
  • Breast and genitalia pressure — check after positioning; reposition if compressed.
  • Intra-abdominal pressure — inadequate abdominal free space increases IVC compression and ventilation pressures.

Prone Jackknife​

Break at the hip so the buttocks are elevated — standard for York-Mason rectal approach to the posterior urethra. Same risks as prone plus:

  • Back pain / ligamentous stretch at the hip break.
  • Increased venous congestion in the lower extremities.

Prone Split-Leg​

Prone with legs abducted on split-leg table sections — used for combined transanal and perineal access. Adds lithotomy-type risks (peroneal, femoral nerve) to the prone-position set.

Galdakao-Modified Valdivia — for PCNL​

The Valdivia position (1987) and its Galdakao modification (Ibarluzea 2007) allow simultaneous percutaneous and retrograde access for PCNL in a single setup — a major practical advance for complex stones and for combined antegrade/retrograde endoscopic work.[13][14]

Setup​

  • Patient supine on a standard OR table.
  • Ipsilateral side elevated ~30° with a 3-liter saline bag or dedicated wedge under the flank and ipsilateral shoulder.
  • Ipsilateral arm across the chest, contralateral arm on a standard arm board.
  • Ipsilateral leg extended, contralateral leg in lithotomy (Galdakao modification: both legs in a modified lithotomy to allow retrograde access).
  • This orientation opens the flank for percutaneous puncture while the perineum remains accessible for flexible ureteroscopy.

Advantages Over Prone PCNL​

  • Single position for combined antegrade + retrograde work ("ECIRS" — endoscopic combined intrarenal surgery).
  • Better airway access than prone; easier emergency airway management.
  • Lower anesthesia-related morbidity in obese and cardiopulmonary-limited patients.
  • Reduced risk of embolic and ventilation complications vs prone.

Disadvantages / Limitations​

  • Smaller working space than prone for percutaneous puncture.
  • Colon more likely to overlie the kidney on supine imaging — preoperative CT mapping of colonic position is prudent (retrorenal colon in ~1–5%).
  • Limited to kidneys accessible through the less steep angle — complex upper-pole access sometimes remains more ergonomic prone.

Modern Use​

Galdakao-modified Valdivia is the default positioning in many high-volume stone centers for complex stones, bilateral stones, or ECIRS cases; prone PCNL persists for selected upper-pole and morbidly obese cases. Comparative outcomes (stone-free rate, complications) are broadly equivalent.[15]

Common Positioning Complications — Summary​

ComplicationHighest-risk position(s)Prevention
Ulnar neuropathySupine with tucked armsSupinate forearm; pad cubital tunnel
Brachial plexus injuryLateral decubitus (both sides), prone, steep TrendelenburgAxillary roll caudal to axilla; avoid rigid shoulder braces; arm abduction ≤90°
Common peroneal palsyLithotomy (standard / exaggerated), lateral (down-leg)Boot stirrups; pad fibular head
Femoral neuropathyExaggerated lithotomyLimit hip flexion; avoid psoas retraction
Well-leg compartment syndromeLithotomy >4 hLeg-down breaks; boot stirrups; limit Trendelenburg combination
Postoperative visual loss (POVL)Prolonged steep Trendelenburg, proneLimit time; maintain MAP; check eyes; avoid globe pressure
Corneal abrasionAll general-anesthetic casesTape eyes; goggles if prolonged
RhabdomyolysisLateral nephrectomy in obese, exaggerated lithotomy >5 hLimit position time; adequate padding
Pressure ulcerAll long casesPad bony prominences; reposition intermittently
Brachial plexus (from shoulder braces)Steep TrendelenburgAnti-slide mattress; avoid rigid shoulder braces

Preoperative Positioning Plan — Practical Checklist​

For every urologic operation:

  1. Decide the position before the patient is anesthetized. Patient-awake range of motion is the ceiling — never force it.
  2. Estimate case duration and plan for reposition breaks if lithotomy projected >4 h.
  3. Mark the operative side and confirm with timeout.
  4. Pad every bony prominence — heels, sacrum, greater trochanter, elbow, lateral malleolus, occiput.
  5. Axillary roll caudal to the axilla in lateral decubitus.
  6. Forearms supinated when arms are tucked.
  7. Shoulder abduction ≤90° always.
  8. Eye protection — tape + goggles for prolonged or prone cases.
  9. Anti-slide mattress for steep Trendelenburg; avoid rigid shoulder braces.
  10. Document the positioning check after draping and at each 2-hour interval.

References​

1. Warner MA, Warner ME, Martin JT. "Ulnar Neuropathy: Incidence, Outcome, and Risk Factors in Sedated or Anesthetized Patients." Anesthesiology. 1994;81(6):1332–40. doi:10.1097/00000542-199412000-00006

2. American Society of Anesthesiologists Task Force. "Practice Advisory for the Prevention of Perioperative Peripheral Neuropathies 2018." Anesthesiology. 2018;128(1):11–26. doi:10.1097/ALN.0000000000001937

3. Warner MA, Warner DO, Harper CM, Schroeder DR, Maxson PM. "Lower Extremity Neuropathies Associated With Lithotomy Positions." Anesthesiology. 2000;93(4):938–42. doi:10.1097/00000542-200010000-00010

4. Sawyer RJ, Richmond MN, Hickey JD, Jarrratt JA. "Peripheral Nerve Injuries Associated With Anaesthesia." Anaesthesia. 2000;55(10):980–91. doi:10.1046/j.1365-2044.2000.01614.x

5. Chitwood A, Lee ZY, Eid SM, Gonzalez AA, Fleisher LA. "Lower Extremity Nerve Injury After Lithotomy Position." J Am Coll Surg. 2019;228(4):616–624. doi:10.1016/j.jamcollsurg.2018.12.032

6. Kvarnström A, Sokolov A, Swartling T, Åkeson J. "Femoral Nerve Injury and Psoas Compartment Dysfunction After Lithotomy Position." Anesth Analg. 2013;117(5):1238–1240.

7. Halliwill JR, Hewitt SA, Joyner MJ, Warner MA. "Effect of Various Lithotomy Positions on Lower-Extremity Blood Pressure." Anesthesiology. 1998;89(6):1373–6. doi:10.1097/00000542-199812000-00014

8. Simms MS, Terry TR. "Well-Leg Compartment Syndrome After Pelvic and Perineal Surgery in the Lithotomy Position." Postgrad Med J. 2005;81(958):534–6. doi:10.1136/pgmj.2004.030965

9. Angermeier KW, Rourke KF, Dubey D, Forsyth RJ, Gonzalez CM. "SIU/ICUD Consultation on Urethral Strictures: Evaluation and Follow-Up." Urology. 2014;83(3 Suppl):S8–17. doi:10.1016/j.urology.2013.09.011

10. Koç G, Tazeh NN, Joudi FN, Winfield HN, Tracy CR, Brown JA. "Lower Extremity Neuropathies After Robot-Assisted Laparoscopic Prostatectomy on a Split-Leg Table." J Endourol. 2012;26(8):1026–1029. doi:10.1089/end.2011.0664

11. American Society of Anesthesiologists Task Force. "Practice Advisory for Perioperative Visual Loss Associated With Spine Surgery 2019 (Updated)." Anesthesiology. 2019;130(1):12–30. doi:10.1097/ALN.0000000000002503

12. Goepfert CE, Ifune C, Tempelhoff R. "Ischemic Optic Neuropathy: Are We Any Further?" Curr Opin Anaesthesiol. 2010;23(5):582–587. doi:10.1097/ACO.0b013e32833e15d0

13. Valdivia Uría JG, Valle Gerhold J, López López JA, et al. "Technique and Complications of Percutaneous Nephroscopy: Experience With 557 Patients in the Supine Position." J Urol. 1998;160(6 Pt 1):1975–1978. doi:10.1097/00005392-199812010-00002

14. Ibarluzea G, Scoffone CM, Cracco CM, et al. "Supine Valdivia and Modified Lithotomy Position for Simultaneous Anterograde and Retrograde Endourological Access." BJU Int. 2007;100(1):233–236. doi:10.1111/j.1464-410X.2007.06960.x

15. Astroza G, Catalán M, Consigliere L, Selman T, Salvadó J, Sepúlveda F. "Is a Supine Position as Effective as a Prone Position for Percutaneous Nephrolithotomy? Outcomes From a Prospective Database." J Endourol. 2013;27(12):1431–1436. doi:10.1089/end.2013.0399