Back to Operative Surgery
Adult Reconstruction

Total Hip Replacement with Dual Mobility Cup

Comprehensive surgical technique guide for Total Hip Replacement with Dual Mobility Cup including indications, operative technique, complications, and outcomes - FRCS exam preparation

Core Procedure
intermediate
By OrthoVellum Medical Education Team

Reviewed by OrthoVellum Editorial Team

Editorial maintenance, source checking, and correction workflow • Published by OrthoVellum Medical Education Team

Editorial boardMethodologyReview policyReport a correction
High Yield Overview

TOTAL HIP REPLACEMENT WITH DUAL MOBILITY CUP

Dual articulation system for high-risk patients: two bearings (large outer 22-32mm, small inner 28-36mm) increase jump distance to 15-20mm vs 10mm standard | intermediate

Critical Danger Structures

Danger 1: Sciatic Nerve

Location: Exits pelvis through greater sciatic notch below piriformis, runs 2cm posterior to posterior hip joint, posterior to short external rotators. Protection: Identify early in posterior approach, gentle retraction, avoid excessive traction during dislocation, limit lengthening to 4cm, release if tight. Injury rate 0.5-2%, higher with lengthening >4cm.

Danger 2: Superior Gluteal Neurovascular Bundle

Location: Exits pelvis through greater sciatic notch ABOVE piriformis, runs between gluteus medius and minimus approximately 3-5cm proximal to greater trochanter. Protection: Avoid splitting gluteus medius >3-5cm proximal to GT, stay distal in posterior approach, avoid aggressive superior retraction in anterior approach. Injury causes abductor weakness (Trendelenburg gait).

Danger 3: Femoral Neurovascular Bundle

Location: Anterior to hip joint in femoral triangle - nerve lateral, artery middle, vein medial (mnemonic: NAVEL from lateral to medial). Protection: In anterior approach - place retractors carefully, stay lateral to iliopsoas, avoid deep medial retraction. Gentle retraction with blunt instruments. Injury rare but catastrophic.

Danger 4: Lateral Femoral Cutaneous Nerve

Location: Runs under inguinal ligament 1-2cm medial to ASIS, in subcutaneous fascia over sartorius. Protection: In anterior approach - identify during fascial dissection, stay deep to fascia, avoid traction. Injury causes meralgia paresthetica (lateral thigh numbness) in 10-20% anterior approach, usually self-limiting.

Danger 5: External Iliac Vessels

Location: Run along pelvic brim anteroinferiorly. Protection: Avoid acetabular screws in ANTEROINFERIOR quadrant (3-9 o'clock region). Use screws only in posterosuperior quadrant (10-2 o'clock right hip). Confirm screw length does not penetrate medial wall. Vascular injury during screw placement catastrophic.

Mnemonic

DUAL MOBILITYDUAL MOBILITY - Indications

Memory Hook:Use DUAL MOBILITY mnemonic for comprehensive indication list. Examiners love when candidates systematically categorize high-risk patients. Key point: dual mobility is NOT just for revision - liberal use in high-risk primary supported by Level A evidence.

Mnemonic

SEATEDSEATED - Ensuring Dual Mobility Liner Security

Memory Hook:SEATED ensures proper liner insertion - critical to prevent intraprosthetic dislocation (0.5-1%). Partial seating is the main preventable cause. Modern designs have improved locking mechanisms but technique still matters.

Indications for Dual Mobility

High-Risk Primary Total Hip Replacement

Absolute Indications:

  • Femoral neck fracture in elderly (>75 years) with displacement
  • Neuromuscular disease: Parkinson's disease, cerebrovascular accident, dementia
  • Spinopelvic pathology: flat lumbar lordosis, stiff spine, lumbosacral fusion
  • Severe cognitive impairment preventing compliance with hip precautions

Relative Indications (Strong Evidence):

  • Age >75 years (even without other risk factors)
  • History of previous hip dislocation (ipsilateral or contralateral)
  • Abductor muscle deficiency (previous trochanteric osteotomy, superior gluteal nerve injury)
  • Connective tissue disorders (Ehlers-Danlos, ligamentous laxity)
  • Large femoral head resection (tumour, prior surgery) with soft tissue deficiency
  • Anticipated non-compliance (substance abuse, psychiatric disease)

Revision Total Hip Replacement

Absolute Indications:

  • Recurrent instability/dislocation as primary indication for revision
  • Failed hemiarthroplasty with instability in elderly patient

Relative Indications:

  • Revision for aseptic loosening in high-risk patient (age >75, neuromuscular disease)
  • Revision with poor abductor function
  • Revision with significant bone loss requiring large cup (>60mm) where standard head size insufficient

Contraindications

Relative Contraindications:

  • Young active patient <55-60 years (theoretical concern for long-term intraprosthetic dislocation and wear - though modern evidence increasingly reassuring)
  • Severe acetabular bone loss with segmental rim defects >25% (dual mobility cup requires intact rim for stability - may need revision cup with augments)
  • Active infection (absolute contraindication for any arthroplasty)

Preoperative Planning

Clinical Assessment

History: Document dislocation history (number, direction, mechanism), neuromuscular symptoms, cognitive function, spine symptoms/fusion, compliance concerns, previous hip surgery.

Examination: Abductor strength (Trendelenburg test), leg length discrepancy, range of motion, spine flexibility (sit-to-stand test for spinopelvic mobility), neurovascular status.

Imaging

Standard Radiographs:

  • AP pelvis (assess acetabular bone stock, cup position if revision, leg length)
  • Lateral affected hip (assess offset, stem if revision)
  • Full spine radiographs if spinopelvic pathology suspected (AP/lateral standing)

Advanced Imaging:

  • CT pelvis with 3D reconstruction if acetabular defects suspected (revision cases)
  • MRI if soft tissue assessment needed (abductors, infection)

Templating

Acetabular Component:

  • Dual mobility cups typically 50-62mm outer diameter (smaller than standard cups due to thick PE liner inside)
  • Template for anatomic hip center (medialize to true floor - transverse ligament/teardrop)
  • Plan inclination 40-45°, anteversion 15-20° (Lewinnek safe zone)
  • Assess rim support - need intact 360° rim for dual mobility stability

Femoral Component:

  • Dual mobility compatible with ANY femoral stem design (standard, modular, revision)
  • Template stem size, offset, neck length
  • Plan anteversion 10-15° (combined anteversion 25-35° with cup)

Leg Length:

  • Measure discrepancy, plan correction (typically aim within 1cm)
  • Reference lesser trochanter to ischial tuberosity

Infection Workup (Revision Cases)

Mandatory for:

  • Revision THR for any indication
  • Failed hemiarthroplasty conversion
  • Any patient with risk factors (previous infection, wound problems, immunosuppression)

Tests:

  • Serology: ESR, CRP
  • Hip aspiration: cell count, differential, culture (hold antibiotics 2 weeks prior)
  • Consider alpha-defensin, synovial CRP if available

Patient Counseling

Benefits:

  • Dislocation rate reduced 50-80%: 0.5-3% vs 2-5% standard
  • Particularly effective in high-risk groups (femoral neck fracture: 1-2% vs 8-15%)
  • Similar long-term survivorship to standard THR (95-98% at 10 years)
  • Allows aggressive rehabilitation (critical in elderly)

Risks:

  • Intraprosthetic dislocation 0.5-1% (inner bearing dissociates) - requires revision surgery
  • All standard THR risks: infection, nerve injury, fracture, loosening, leg length discrepancy
  • Theoretical long-term wear concerns (reassuring modern data with HXLPE)

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 78-year-old woman with Parkinson's disease presents with a displaced femoral neck fracture. She is cognitively intact but has moderate tremor and rigidity. Discuss your management and justify the use of dual mobility."

EXCEPTIONAL ANSWER
This is a high-risk patient for dislocation: elderly (>75), neuromuscular disease (Parkinson's), and femoral neck fracture. I would recommend total hip replacement with a dual mobility cup. RATIONALE: (1) Parkinson's patients have 10-15% dislocation rate with standard THR vs 2-4% with dual mobility. (2) Femoral neck fracture in elderly has 8-15% dislocation with standard vs 1-2% with dual mobility - this is Level I evidence. (3) Dual mobility works by having two bearings: large outer bearing (22-32mm radius) and small inner bearing (28-36mm radius), increasing jump distance from 10mm to 15-20mm, nearly doubling dislocation resistance. (4) She can mobilize early with weight bearing as tolerated, critical in elderly to prevent deconditioning. (5) I would use posterior approach with meticulous capsule and rotator repair to further reduce dislocation. (6) Post-op: hip precautions 6 weeks, DVT prophylaxis, aggressive physiotherapy. Expected outcome: <2% dislocation risk vs >10% with hemiarthroplasty or standard THR.
VIVA SCENARIOStandard

EXAMINER

"What is intraprosthetic dislocation? How does it differ from standard dislocation? Describe the radiographic appearance and management."

EXCEPTIONAL ANSWER
Intraprosthetic dislocation is SPECIFIC to dual mobility cups - the inner articulation (femoral head) dissociates from the polyethylene liner while the outer articulation (liner) remains reduced in the metal cup. MECHANISM: The dual mobility liner has two bearing surfaces - large outer (articulates with femoral head) and small inner (articulates with liner cup). Normally both articulate freely. With intraprosthetic dislocation, the femoral head 'pops out' of the inner bearing surface but remains within the outer bearing. INCIDENCE: Modern designs (post-2000) with improved locking mechanisms: 0.5-1%. Historical designs (1970s-1990s): 5-10% - this high rate led to abandonment in USA until modern improvements. CAUSES: (1) Liner malseating during surgery - most preventable cause, (2) Impingement (stem-cup or bone-cup) causing levering force, (3) Trauma, (4) Late polyethylene wear with old designs (rare with modern HXLPE). RADIOGRAPHIC APPEARANCE: 'DOUBLE DENSITY' sign on X-ray - see TWO radiodense circles (femoral head + liner/cup), whereas standard dislocation shows only one radiodense circle displaced. Hip appears grossly reduced on examination but patient has sudden pain and cannot bear weight. MANAGEMENT: Cannot be closed reduced (locked-out configuration). Requires OPEN reduction via same surgical approach. Intraoperatively assess: (1) Liner seating - usually needs revision/replacement, (2) Impingement - remove if present, (3) Locking mechanism integrity. Address any identified cause. Good outcomes after appropriate revision.
VIVA SCENARIOStandard

EXAMINER

"A colleague tells you 'Dual mobility is great because you don't need to worry about component positioning - the large head compensates for malposition.' How would you respond?"

EXCEPTIONAL ANSWER
I would respectfully DISAGREE. This is a DANGEROUS misconception about dual mobility. While dual mobility dramatically reduces dislocation risk through increased jump distance, it does NOT compensate for malposition and you absolutely still need to achieve optimal component positioning. Here's why: (1) EDGE LOADING: Malpositioned cups create edge loading regardless of head size. This accelerates polyethylene wear, can cause early failure, and actually INCREASES risk of intraprosthetic dislocation (liner can lever out with impingement). (2) IMPINGEMENT: Malposition causes impingement (stem-cup, bone-cup) which creates levering forces that can cause intraprosthetic dislocation. The mechanism is different from standard dislocation but still occurs. (3) LEWINNEK SAFE ZONE STILL APPLIES: I still target 40-45° inclination and 15-20° anteversion. Studies show malpositioned dual mobility cups have higher complications including intraprosthetic dislocation. (4) DUAL MOBILITY MECHANISM: It works by increasing JUMP DISTANCE (from 10mm to 15-20mm) through two bearings, not by tolerating malposition. The large effective head size prevents dislocation by increasing distance to impingement, but this benefit is LOST with malposition. (5) EVIDENCE: Registry data shows malpositioned dual mobility cups fail at higher rates from wear and intraprosthetic dislocation. Proper technique remains critical. SUMMARY: Dual mobility is an ADJUNCT to good surgical technique, not a SUBSTITUTE for it. I still aim for perfect positioning in every case.

Total Hip Replacement with Dual Mobility Cup - Exam Summary

High-Yield Exam Summary

References

  1. Batailler C, White N, Ranaldi FM, Neyret P, Servien E, Lustig S. Improved implant position and lower dislocation rate with robotic-assisted unicompartmental knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2019;27(4):1232-1240. doi:10.1007/s00167-018-5081-5

  2. Grazioli A, Ek ET, Rudiger HA. Biomechanical concept and clinical outcome of dual mobility cups. Int Orthop. 2012;36(12):2411-2418. doi:10.1007/s00264-012-1678-3

  3. Philippot R, Adam P, Reckhaus M, et al. Prevention of dislocation in total hip revision surgery using a dual mobility design. Orthop Traumatol Surg Res. 2009;95(6):407-413. doi:10.1016/j.otsr.2009.04.016

  4. Chalmers BP, Syku M, Sculco TP, Mayman DJ, Lyman S, Vigdorchik JM. Dual mobility constructs in primary total hip arthroplasty in high-risk patients with spinal fusions: our institutional experience. Arthroplast Today. 2020;6(4):749-754. doi:10.1016/j.artd.2020.07.009

  5. Tardy N, Maqdes A, Brosset T, Guyen O. Intraprosthetic dislocation of dual mobility cups: a systematic review. Int Orthop. 2020;44(4):655-663. doi:10.1007/s00264-019-04473-9

  6. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report. Adelaide: AOA; 2023. https://aoanjrr.sahmri.com/annual-reports-2023

  7. Gaillard R, Bankhead C, Gaillard JP, Servien E, Lustig S. Comparison of outcomes between dual mobility and constrained liners in revision total hip arthroplasty. Bone Joint J. 2016;98-B(1 Suppl A):80-85. doi:10.1302/0301-620X.98B1.36331

  8. Adam P, Farizon F, Fessy MH. Dual articulation retentive acetabular liners and wear: surface analysis of 40 retrieved polyethylene implants. Orthop Traumatol Surg Res. 2014;100(1):85-91. doi:10.1016/j.otsr.2013.12.011

  9. Hailer NP, Weiss RJ, Stark A, Kärrholm J. Dual-mobility cups for revision due to instability are associated with a low rate of re-revisions due to dislocation: 228 patients from the Swedish Hip Arthroplasty Register. Acta Orthop. 2012;83(6):566-571. doi:10.3109/17453674.2012.742395

  10. Langlais FL, Ropars M, Gaucher F, Musset T, Chaix O. Dual mobility cemented cups have low dislocation rates in THA revisions. Clin Orthop Relat Res. 2008;466(2):389-395. doi:10.1007/s11999-007-0047-9