Dealing With Complications in THA – Case Presentations and Discussion

1. High-Yield Summary

• Multi-Etiology Spectrum: Total hip arthroplasty (THA) complications represent an interconnected spectrum comprising mechanical instability and dislocation, periprosthetic joint infection (PJI), periprosthetic fractures, aseptic loosening, and neurovascular injury, accounting for substantial patient morbidity and revision healthcare expenditure.
• Instability and Spinopelvic Mechanics: Dislocation remains among the most frequent early complications (1% to 3% in primary THA; exceeding 10% to 15% in complex revision). Contemporary management mandates dynamic spinopelvic evaluation, recognizing that static anatomical target zones are invalidated by spinal deformity, lumbosacral fusion, and pelvic stiffness.
• Periprosthetic Joint Infection Diagnostics: Early accurate diagnosis of PJI demands rigorous adherence to the validated International Consensus Meeting (ICM) criteria. Management diverges sharply between acute presentations amenable to debridement, antibiotics, and implant retention (DAIR) and chronic biofilm-mediated infections requiring staged explantation with antibiotic-loaded spacers.
• Fracture Stratification by Stem Stability: Periprosthetic femoral fractures require systematic classification using the Vancouver system. The critical management branching point centers on femoral stem stability: Vancouver B1 fractures with well-fixed implants undergo locked plating and cerclage fixation, whereas Vancouver B2 and B3 fractures with loose stems require bypass revision with fluted tapered modular stems or proximal femoral replacements.
• Systematic Algorithmic Revision: Revision surgery for THA complications requires definitive identification of the primary root cause. Addressing component malposition, abductor complex deficiency, bone loss, or occult infection before undertaking reconstructive revision is essential to prevent catastrophic re-failure.

2. Anatomy

Revision hip surgery and complication management necessitate precise anatomical orientation through scarred tissue planes and distorted tissue corridors. Surgeons must master the internervous planes and neurovascular danger zones governing hip exposure.

Neurovascular Danger Zones

• Sciatic Nerve: Situated posterior to the external rotators and quadratus femoris. In the posterior approach, the sciatic nerve is susceptible to direct retractor compression against the posterior column or excessive traction during limb lengthening exceeding 2 to 3 cm. Prior surgical scarring obliterates normal epineural fat planes, placing the peroneal division at disproportionate risk.
• Femoral Nerve and Vessels: Traverse anterior to the hip joint within the iliopectineal fossa. Anterior acetabular retractors placed beyond the anterior column can penetrate the iliopsoas belly and compress or lacerate the femoral neurovascular bundle. Transacetabular screw insertion in the anterosuperior quadrant risks external iliac vessel laceration; anteroinferior screw placement endangers the obturator neurovascular bundle.
• Obturator Neurovascular Bundle: Exits the obturator foramen adjacent to the inferior acetabular rim. Deep retractor placement below the transverse acetabular ligament or medial acetabular wall perforation during reaming poses acute hemorrhage hazards.
• Superior Gluteal Nerve: Exits the greater sciatic notch superior to the piriformis and courses between the gluteus medius and minimus. Proximal extension of the direct lateral (Hardinge) or anterolateral approach split in the gluteus medius greater than 3 to 5 cm proximal to the greater trochanter tip causes denervation of the anterior tensor fasciae latae and abductor complex.
• Lateral Femoral Cutaneous Nerve (LFCN): Traverses the pelvic brim under or through the inguinal ligament near the anterior superior iliac spine (ASIS). In direct anterior exposures, aggressive medial traction or lateral sartorius sheath violation produces painful meralgia paresthetica.

Surgical Planes and Safe Retraction Corridors

Acetabular fixation requires strict adherence to the Wasielewski quadrant system. The posterosuperior quadrant (bounded by lines extending from the anterior superior iliac spine through the center of the acetabulum to the posterior superior iliac spine) offers the greatest bone depth and safe trajectory into the sciatic buttress without neurovascular jeopardy. Transacetabular screws should be strictly confined to the posterosuperior and posteroinferior quadrants.

3. Pathogenesis

Complications following total hip reconstruction result from biological, mechanical, and patient-specific failure pathways that compromise implant fixation, articular articulation, or surrounding bone stock.

Mechanical Instability and Dislocation

Implant dislocation occurs when the femoral head translates past the acetabular rim, driven by component orientation outside functional targets, prosthetic or bony impingement, abductor complex insufficiency, or spinopelvic kinematics. Stiff lumbar spine segments or prior multisegmental lumbar arthrodesis eliminate physiological pelvic retroversion during sitting, forcing the functional acetabulum into persistent relative anteversion and vertical inclination, triggering anterior impingement with posterior dislocation during seated posture.

Periprosthetic Joint Infection

Pathogen inoculation occurs via direct intraoperative introduction, contiguous spread from wound breakdown, or hematogenous seeding from distant foci (e.g., dentoalveolar, urologic, or cutaneous). Bacteria adhere to biomaterial surfaces through hydrophobic and electrostatic interactions, producing extracellular polymeric substance (EPS) to establish mature biofilms. Within biofilm microenvironments, sessile bacterial colonies demonstrate profound phenotypic tolerance to systemic antimicrobials, requiring surgical debridement or complete hardware explantation.

Periprosthetic Femoral Fractures

Periprosthetic fractures develop intraoperatively from hoop stress generation during canal rasping, broaching, or wedge taper stem impaction, particularly in Dorr Type C osteopenic femoral morphology. Postoperative fractures occur after low-energy ground-level falls in elderly patients, where cortical stress risers at the stem tip or localized osteolytic defects concentrate torsional and bending moments.

Aseptic Loosening and Osteolysis

Polyethylene, metallic, or ceramic wear particles trigger chronic monocyte/macrophage activation. Phagocytosis of submicron particles stimulates pro-inflammatory cytokine release (TNF-alpha, IL-1, IL-6), upregulating RANKL-mediated osteoclastic bone resorption. Progressive osteolysis degrades interfacial bone support, producing mechanical micromotion exceeding 150 microns, which prevents biological bone ingrowth and leads to gross prosthetic migration.

4. Natural History

Untreated or inappropriately managed complications inevitably escalate into progressive bone destruction, catastrophic component failure, permanent neurological deficit, or chronic systemic debility.

Epidemiology and Clinical Burden

Primary THA delivers implant survivorship exceeding 90% at 20 years, yet complications remain a significant public health challenge. Instability represents the leading cause for revision within the initial postoperative year, accounting for 20% to 30% of early reoperations. Periprosthetic joint infection occurs in 0.5% to 1.5% of primary arthroplasties and represents the most catastrophic complication, with 5-year mortality rates following septic revision approaching 20%, surpassing several common solid-organ malignancies.

Long-Term Prognosis

Single isolated dislocations that undergo closed reduction with identifiable extrinsic factors carry a recurrence risk of approximately 30% to 40%. Once a hip experiences two or more dislocations, nonoperative salvage fails in more than 60% to 70% of cases, mandating reconstructive intervention. Postoperative periprosthetic femoral fractures exhibit 1-year mortality rates ranging from 10% to 15%, paralleling native geriatric proximal femur fractures.

5. Clinical Presentation

History

Evaluation requires a systematic history to differentiate septic, mechanical, and biological failure pathways:

• Temporal Pattern of Symptoms: Inquire about the symptom-free interval. Immediate postoperative pain suggests occult fracture, surgical neuropathy, or undersized unstable components. Pain emerging after a prolonged symptom-free interval indicates late hematogenous infection, progressive osteolysis, or fatigue fracture.
• Pain Characteristics: Start-up groin pain localized to the groin crease indicates acetabular loosening or anterior iliopsoas impingement. Mid-thigh pain with axial loading indicates femoral stem instability, toggle, or cortical stress shielding. Constant non-mechanical rest pain and night pain are pathognomonic for indolent deep periprosthetic infection.
• Mechanical Instability Events: Elicit the exact hip position during subluxation or dislocation. Posterior dislocation typically occurs during flexion, adduction, and internal rotation (e.g., tying shoes, low chair seating). Anterior dislocation occurs with extension and external rotation.
• Prior Surgical Details and Wound History: Document persistent drainage beyond postoperative day 5, prolonged antibiotic courses, prior surgical approaches, and host comorbidities (diabetes, inflammatory arthropathy, obesity, chronic kidney disease).

Physical Exam

Physical assessment should follow a structured sequence with verified diagnostic maneuvers:

• Gait and Abductor Integrity: Trendelenburg Sign: Patient stands unipedal on the affected leg -> Pelvis tilts downward toward the contralateral unsupported side; signifies gluteus medius/minimus disruption or superior gluteal nerve palsy [Sensitivity 73%, Specificity 77%].
• Resisted Straight Leg Raise (Stinchfield Test): Supine active straight leg raise against downward resistance at 30 degrees of hip flexion -> Reproduction of sharp groin pain; differentiates intra-articular pathology or stem instability from lumbar radiculopathy [Sensitivity 82%, Specificity 75%].
• Log Roll Maneuver: Passive internal and external rotation of the extended lower extremity -> Pain reproduction confirms intra-articular pathology or capsular distension while minimizing lumbar stress [Sensitivity 78%, Specificity 80%].
• Psoas Impingement Sign: Seated active resisted hip flexion -> Sharp anterior groin discomfort localized over the anterior acetabular rim; indicates prominent cup overhang or retained anterior screw irritating the iliopsoas tendon.
• Neurovascular Examination: Motor testing of tibialis anterior (deep peroneal/L4), extensor hallucis longus (deep peroneal/L5), and gastrocnemius-soleus (tibial/S1); sensory mapping across the dorsum and plantar aspects of the foot to document sciatic division integrity.

6. Imaging and Diagnostic Studies

Diagnostic workup requires progressive radiographic, advanced cross-sectional, and serological assessment.

Standard Radiographs and Measurements

• Radiographic Projections: Standard low-centered AP pelvis (centered on pubic symphysis), true AP of the affected hip, and cross-table lateral or Dunn 45-degree lateral view. Full-length bilateral femur views are mandatory when periprosthetic fracture, severe deformity, or revision stem planning is anticipated.
• Acetabular Inclination and Version: Target radiographic inclination is 40 degrees ± 10 degrees; radiographic anteversion target is 15 to 20 degrees. Measure against the trans-ischial or teardrop reference line.
• Component Migration and Zone Mapping: Screen for progressive radiolucent lines (>2 mm) or osteolysis across Gruen zones (1 to 7 on AP, 8 to 14 on lateral) for the femoral stem, and DeLee and Charnley zones (I to III) for the acetabular cup. Gross component migration, broken screws, or pedestal formation indicate mechanical loosening.
• Dynamic Spinopelvic Radiography: Standing and relaxed seated lateral spinopelvic views are indicated in recurrent instability. Quantify pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), and spinopelvic delta (change in sacral slope from standing to seated). Normal mobile spinopelvic mechanics exhibit a sacral slope decrease of greater than 10 degrees upon sitting. A stiff spine demonstrates change less than 10 degrees, creating posterior impingement and anterior instability.

Advanced Imaging

Computed tomography with metal artifact reduction software (MARS-CT) is the definitive modality for quantifying 3D acetabular cup anteversion, combined version, pelvic bone loss (Paprosky classification), and retroacetabular osteolysis. Magnetic resonance imaging with multi-acquisition variable-resonance image combination (MAVRIC) evaluates abductor tendon integrity and pseudotumor formations.

Infection Workup and Joint Aspiration

Serum biomarkers constitute the primary screening tier: serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). When either marker is elevated or clinical suspicion is moderate to high, image-guided hip joint aspiration is mandatory before reoperation. Synovial fluid is analyzed for total nucleated cell count, polymorphonuclear neutrophil percentage (PMN%), alpha-defensin immunoassay, and aerobic/anaerobic cultures held for 14 days.

7. Classification

Validated classification frameworks establish standardized prognostic communication and dictate reconstructive surgical strategy.

Vancouver Classification for Periprosthetic Femoral Fractures

International Consensus Meeting (ICM) 2018 Diagnostic Criteria for PJI

8. Treatment

Management of THA complications must be tailored to the exact failure etiology, patient physiological status, and implant-bone stock interface.

Medical / Nonoperative

• Acute Dislocation: First-time dislocations without component malposition or fracture undergo emergent closed reduction under procedural sedation. Post-reduction traction and cross-table radiographs confirm concentric seating. An abduction hip orthosis may be utilized for 4 to 6 weeks in non-compliant patients or posterior hip approach repairs.
• Non-Displaced Fractures (Vancouver AG / AL): Non-displaced greater trochanter or isolated lesser trochanter avulsions with stable stems are treated with 6 weeks of protected partial weight-bearing with touch-down crutch gait and abduction avoidance.
• Suppressive Antibiotic Therapy: Reserved exclusively for medically infirm patients unable to tolerate major staged revision, provided the implant remains mechanically stable and the offending organism has an oral bactericidal option with low resistance propensity.

Operative

• Recurrent Instability Reconstruction:
  Modular Head/Liner Exchange: Indicated only when component orientation is ideal, abductors are intact, and soft-tissue laxity is restored by increasing head size (e.g., 36 mm or 40 mm) or head offset (+4 to +8 mm).
  Dual-Mobility Articulation: Indicated in recurrent instability, abductor deficiency, neurological impairment (Parkinson disease, cognitive decline), or spinopelvic stiffness. Employs a small head captured within a freely mobile ultra-high-molecular-weight polyethylene liner articulating inside a polished metal shell, maximizing head-to-neck ratio and jump distance.
  Constrained Acetabular Liners: Salvage option for complete abductor loss where dual-mobility fails; mechanically locks the femoral head within the acetabular rim, carrying high rates of long-term cup loosening due to stress transfer to the bone-implant interface.
• Periprosthetic Fracture Fixation and Revision:
  Vancouver B1: Rigid open reduction and internal fixation utilizing a contoured broad locked periprosthetic plate spanning the entire femoral shaft. Proximal fixation combines locking screws and cerclage cables around the stem, while distal fixation achieves at least 4 bicortical locked screws.
  Vancouver B2 / B3: Complete stem explantation. Reconstruction utilizes a cementless modular fluted tapered titanium stem that bridges the fracture site by at least two diaphyseal cortical canal diameters (minimum 4 to 6 cm of scratch fit in pristine distal bone). Fractures are reduced and stabilized with cerclage cables before final stem seating to prevent iatrogenic hoop split propagation.
• Periprosthetic Joint Infection Management:
  Debridement, Antibiotics, and Implant Retention (DAIR): Strictly indicated for acute postoperative infection (within 3 to 4 weeks of index surgery) or acute hematogenous seeding (symptom duration < 3 weeks) with well-fixed components, healthy soft tissue envelope, and known organism with high susceptibility (e.g., methicillin-sensitive Staphylococcus aureus, streptococci). Requires modular head and liner exchange with aggressive synovectomy.
  Two-Stage Revision Arthroplasty: The gold standard for chronic PJI. Stage 1 consists of complete hardware removal, radical debridement of all foreign material and non-viable bone, and insertion of a high-dose articulating or static antibiotic-impregnated cement spacer. Targeted systemic antibiotics are administered for 6 weeks. Stage 2 reimplantation is performed after serological normalization, clinical healing, and negative aspirate cultures off antibiotics.

Indications and Numerical Reconstructive Thresholds

Surgical revision is indicated when acetabular inclination exceeds 50 degrees or falls below 30 degrees, anteversion deviates outside 10 to 25 degrees with recurrent instability, trochanteric displacement exceeds 2 cm with functional abductor lag, or progressive osteolytic radiolucency exceeds 2 mm across multiple zones.

9. Outcome

Reconstructive outcomes correlate with the timing of intervention, bone preservation, and biological host factors.

• Dual-Mobility Bearing Survivorship: Revision to dual-mobility bearing constructs for recurrent instability achieves 5-year survivorship free from redislocation ranging from 92% to 96%, significantly superior to conventional modular head and liner exchanges (75% to 82%).
• Periprosthetic Fracture Union: Vancouver B1 fractures managed with locked lateral plating and proximal cables achieve union rates of 88% to 95%. Vancouver B2 fractures managed with modular fluted tapered stems demonstrate osseointegration and union rates exceeding 90% at 2 to 5 years.
• Infection Eradication Rates: Two-stage exchange arthroplasty delivers infection eradication rates of 85% to 92% at 5 years. In contrast, DAIR in chronic or delayed settings demonstrates high failure rates, achieving durable eradication in only 40% to 60% of unselected cohorts.
• Patient-Reported Outcome Measures (PROMs): Functional recovery after revision THA shows significant gains in Modified Harris Hip Score (mHHS) and Hip Disability and Osteoarthritis Outcome Score (HOOS), though scores remain 10% to 15% lower than primary uncomplicated arthroplasty counterparts.

10. Complications

Complications are categorized by temporal occurrence and clinical severity:

11. Pearls and Pitfalls

• The Diagnostic Trap of Normal Plain Radiographs in Infection: Indolent PJI frequently presents with entirely normal component alignment and no radiolucency. Never attribute constant rest pain or nocturnal throbbing to soft tissue strains without obtaining serum ESR and CRP. When inflammatory markers are elevated, joint aspiration is mandatory before any revision surgery.
• Prophylactic Cerclage Before Revision Stem Seating: During revision for periprosthetic fractures or stem exchange, always place a prophylactic cerclage cable around the proximal femoral host bone just distal to the planned osteotomy or fracture before broaching or reaming. This prevents catastrophic propagation of longitudinal hoop stress fractures down the diaphysis.
• Spinopelvic Awareness in “Correctly Oriented” Cups: When a patient experiences recurrent dislocation despite an acetabular cup appearing within classic static target zones on supine radiographs, obtain seated and standing lateral spinopelvic views. A rigid lumbar spine prevents normal pelvic roll-back, causing functional retroversion loss during sitting. These patients require higher functional cup anteversion or dual-mobility bearings.
• Pitfall of Treating Vancouver B2 Fractures with Plate Fixation Alone: Attempting open reduction and locked plate fixation on a Vancouver B2 fracture without revising the loose stem is the most common technical error in periprosthetic fracture management, resulting in nonunion, plate breakage, and early reoperation in over 50% of cases. The loose stem must be revised to a long diaphyseal-engaging implant.
• Modular Exchange Limitations in Instability: Performing an isolated femoral head and liner exchange for instability without correcting an underlying malpositioned component (excessive retroversion or steep inclination) carries a failure rate exceeding 40%. The root anatomical cause must be identified and corrected.

12. Controversy

Key debates continue to shape contemporary complication management in total hip arthroplasty.

Dual-Mobility Articulations: Universal Protection vs Intraprosthetic Dislocation

While dual-mobility constructs provide substantial jump distance and impingement resistance in high-risk patients, critics highlight the unique failure mode of intraprosthetic dislocation (IPD), where the small femoral head dissociates from the mobile polyethylene liner due to wear or retentive rim fatigue. Modern second-generation and third-generation dual-mobility designs utilizing highly crosslinked polyethylene have drastically reduced IPD rates, but long-term registry surveillance continues to monitor volumetric wear and fretting corrosion at the modular metal shell liner interface.

DAIR vs Two-Stage Revision in Acute Hematogenous Infection

The role of DAIR in acute hematogenous PJI remains contentious. Proponents emphasize preserved bone stock, reduced morbidity, and accelerated recovery. Opponents cite multi-center cohort data demonstrating unacceptably high failure rates in patients with virulent pathogens (e.g., methicillin-resistant Staphylococcus aureus, enterococci), prolonged symptoms (>7 days), or immunocompromised hosts. Increasingly, surgeons employ strict algorithmic criteria (KLIC or CRIME80 scores) to reserve DAIR only for highly selected candidates.

Single-Stage vs Two-Stage Exchange Arthroplasty for Chronic PJI

European centers report successful eradication exceeding 85% to 90% using single-stage revision for chronic PJI under strict criteria: known organism with high sensitivity to oral antibiotics, pristine soft tissue envelope without sinus tract, and absence of prior revision failures. In North America, two-stage exchange remains the predominant standard of care, reflecting concern over unknown or resistant organisms and polymicrobial biofilm recurrence.

13. Evidence-Based Synthesis

Modern clinical decision-making is grounded in high-quality randomized controlled trials and prospective registry analyses, corroborated by seminal biomechanical and anatomical descriptions.

14. References

• Brady OH, Garbuz DS, Masri BA et al. The reliability and validity of the Vancouver classification of femoral fractures after hip replacement. J Arthroplasty. 2000. doi:10.1016/s0883-5403(00)91181-1 [Level II: Multicenter Diagnostic Validation Study]
• Parvizi J, Tan TL, Goswami K et al. The 2018 Definition of Periprosthetic Hip and Knee Infection: An Evidence-Based and Validated Criteria. J Arthroplasty. 2018. doi:10.1016/j.arth.2018.02.078 [Level II: Multicenter Diagnostic Consensus & Validation]
• Wyles CC, Maradit-Kremers H, Larson DR et al. Creation of a Total Hip Arthroplasty Patient-Specific Dislocation Risk Calculator. J Bone Joint Surg Am. 2022. doi:10.2106/JBJS.21.01171 [Level II: Longitudinal Prognostic Registry Cohort]
• Ang JJM, Onggo JR, Stokes CM et al. Comparing direct anterior approach versus posterior approach or lateral approach in total hip arthroplasty: a systematic review and meta-analysis. Eur J Orthop Surg Traumatol. 2023. doi:10.1007/s00590-023-03528-8 [Level I: Systematic Review / Meta-Analysis]
• Guarin Perez SF, Restrepo DJ, Perry KI et al. Acetabular Revision With Dual-Mobility Bearing Reduces Redislocation in Unstable Total Hip Arthroplasty. J Arthroplasty. 2025. doi:10.1016/j.arth.2025.04.005 [Level III: Comparative Cohort Study]

15. Master Class Pro-Tip

When approaching a failed or unstable total hip arthroplasty, never succumb to the temptation of performing an isolated ‘quick fix’ without definitively establishing the root cause of failure. In recurrent instability, do not simply upsize the modular femoral head or add a high-wall liner if the acetabular cup is retroverted, the spinopelvic complex is rigid, or the abductor complex is disrupted. In periprosthetic fractures, never treat a loose stem with plate fixation alone. Always scrutinize inflammatory markers before opening the joint, ensure comprehensive reconstructive hardware is on standby, and systematically restore limb length, femoral offset, and functional version to achieve permanent stability.

Master Class Surgical Pearl: Complex Total Hip Complications & Revision Decision-Making