THA Case Presentations and Discussion

Archival Presentation Notice: This article modernizes the multimedia presentation “THA Case Presentations and Discussion” originally presented as Session 8 at the International Congress for Joint Reconstruction (ICJR). The historical Flash lecture has been reconstructed into the synchronized video slide presentation above, with the original file preserved in the digital archives (case_presentations_and_discussion_session_8.swf).

1. High-Yield Summary

• Primary Clinical Scope: Case-based surgical decision-making in primary and complex total hip arthroplasty (THA), encompassing osteonecrosis with collapse, primary osteoarthritis, post-impingement deformity, femoral neck insufficiency fractures, and the diagnostic evaluation of the painful THA.
• Biomechanical Restoration: Successful total hip reconstruction mandates three-dimensional restoration of the hip center of rotation, femoral offset, and leg length parity while maintaining abductor muscle tension and impingement-free range of motion.
• Spinopelvic Alignment & Dynamic Planning: Assessment of dynamic sagittal spinopelvic mobility (sacral slope, pelvic tilt, and lumbar lordosis) is essential to customize cup anteversion and inclination, avoiding prosthetic impingement and edge loading in patients with stiff or fused spines.
• The Painful THA Triage: Any painful total hip arthroplasty requires a systematic workup to rule out periprosthetic joint infection (PJI) with serum erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) prior to considering mechanical etiologies such as aseptic loosening, psoas impingement, trunnionosis, or abductor insufficiency.
• Fixation Hierarchy: Uncemented hemispherical press-fit acetabular components with porous coatings and tapered-wedge or fit-and-fill femoral stems are standard, with cemented femoral fixation preferentially indicated in elderly patients exhibiting Dorr Type C osteopenic femoral morphology.

2. Clinical Case Analysis & Case-Based Discussion

Interactive case-based reviews present high-yield surgical dilemmas encountered in adult reconstruction. The five clinical cases analyzed below illustrate diagnostic evaluation, templating challenges, surgical approach selection, component fixation, and revision algorithms.

Case 1: Rapid-Onset Hip Pain and Osteonecrosis with Subchondral Collapse

Clinical Vignette: A 56-year-old male presents with a 4-week history of acute, progressive left groin and anterior thigh pain. He ambulates with a pronounced antalgic gait and demonstrates painful, restricted internal rotation and flexion. He has a history of remote corticosteroid therapy for an inflammatory pulmonary disorder. Plain radiographs demonstrate subchondral radiolucency (the crescent sign) with flattening and structural collapse of the superior-lateral femoral head articular surface (Steinberg Stage IV, Ficat Stage III).

• Diagnostic Evaluation: In the pre-collapse stages of osteonecrosis (Steinberg Stages I and II), plain radiographs may appear normal, necessitating magnetic resonance imaging (MRI) with T1-weighted coronal sequences demonstrating the characteristic low-intensity band delineating the necrotic zone. Once subchondral collapse occurs, plain anteroposterior (AP) pelvis and cross-table lateral radiographs confirm joint incongruity.
• Surgical Decision-Making: In patients with established articular collapse (Steinberg Stage IV or greater), joint-preserving procedures such as core decompression, vascularized free fibular grafting, or rotational osteotomy are contraindicated due to unacceptably high early failure rates. Modern cementless primary total hip arthroplasty is the definitive standard of care, yielding implant survivorship exceeding 95% at 10 to 15 years when modern highly cross-linked polyethylene or ceramic bearings are utilized.
• Technical Nuances: Acetabular bone stock is typically preserved in osteonecrosis compared to primary inflammatory arthritis. Careful reaming down to bleeding subchondral bone preserves the subchondral plate for rigid press-fit cup stability. On the femoral side, metaphyseal bone quality is usually excellent, permitting standard tapered-wedge cementless stem fixation.

Case 2: Primary Degenerative Hip Osteoarthritis and Surgical Approach Selection

Clinical Vignette: A 68-year-old female presents with a 2-year history of progressive right groin and buttock pain exacerbated by weight-bearing and transitioning from sitting to standing. Physical examination reveals an antalgic gait, positive Stinchfield test, painful flexion limited to 85 degrees, and absent internal rotation with the hip in 90 degrees of flexion. Pelvic radiographs confirm severe tricompartmental osteoarthritis with superior-lateral joint space obliteration, prominent marginal osteophytes, subchondral sclerosis, and acetabular subchondral cysts.

• The Hip-Spine Syndrome: In patients presenting with concurrent groin, buttock, and lumbar spine symptoms, distinguishing between hip pathology and lumbar spinal stenosis or radiculopathy is mandatory. Hip arthritis classically causes groin-predominant pain exacerbated by internal rotation. When clinical or radiographic overlap exists, an image-guided intra-articular hip local anesthetic injection provides definitive diagnostic differentiation: complete temporary pain relief confirms the hip as the primary pain generator.
• Surgical Approach Considerations: The choice among the direct anterior approach (DAA), direct lateral approach (Hardinge), and posterolateral approach (Moore) must be individualized. The DAA utilizes the true internervous and intermuscular plane (tensor fasciae latae laterally, rectus femoris/sartorius medially), accelerating early recovery during the first 6 weeks and reducing posterior dislocation risk. The posterior approach preserves the abductor mechanism and offers versatile extensibility for complex anatomy, but requires meticulous posterior capsular and conjoint tendon repair to maintain stability.
• Soft-Tissue Balancing: Restoration of the anatomic center of rotation and femoral offset relaxes contracted anterior-inferior capsular structures, eliminates adduction contractures, and restores equal leg lengths without causing abductor strain.

Case 3: Secondary Osteoarthritis Following Femoroacetabular Impingement in the Young Active Adult

Clinical Vignette: A 52-year-old active male athlete presents with chronic right anterior groin pain and stiffness. He reports a long-standing history of mechanical catching and reduced athletic tolerance. Physical examination reveals positive anterior impingement (FADIR test: flexion, adduction, internal rotation) and internal rotation restricted to 5 degrees. Radiographs reveal a pistol-grip femoral deformity (cam morphology with alpha angle of 72 degrees), an anterior overhanging acetabular rim (pincer morphology with cross-over sign), and full-thickness cartilage loss in the anterosuperior weight-bearing zone.

• Pathoanatomy & Limitations of Hip Arthroscopy: While hip arthroscopy with labral repair and osteochondroplasty is effective for pre-arthritic femoroacetabular impingement (FAI), its efficacy drops sharply when joint space narrows below 2 mm or Outerbridge Grade IV chondral delamination is established. At this stage, joint preservation results in high rates of early conversion, making total hip arthroplasty the definitive intervention.
• Bearing Surface Selection: In young, active patients with high physical demands, bearing longevity and wear resistance are paramount. Highly cross-linked polyethylene (HXLPE) paired with either a ceramic or cobalt-chromium femoral head provides predictable low wear rates (< 0.01 mm/year) and has largely eliminated osteolysis. Ceramic-on-ceramic (CoC) bearings offer near-zero wear but carry slight risks of ceramic squeaking (1-3%) and catastrophic component fracture (< 0.05%).
• Head Size Optimization: Utilizing 36 mm femoral heads (when acetabular cup outer diameter is 52 mm or greater) optimizes jump distance and head-to-neck ratio, expanding impingement-free range of motion and minimizing dislocation risk during demanding athletic activities.

Case 4: Acute Subcapital Fragility Fracture in Osteopenic Bone

Clinical Vignette: A 74-year-old female presents to the emergency department following a ground-level mechanical fall with immediate severe left hip pain and inability to bear weight. Physical examination reveals an externally rotated and shortened left lower extremity. Radiographs confirm a displaced intracapsular femoral neck fracture (Garden Type IV, Pauwels Type III) with underlying severe systemic osteopenia and thin cortical cortices (Dorr Type C canal morphology).

• Hemiarthroplasty vs. Total Hip Arthroplasty: In active, independent, community-ambulating elderly patients without significant cognitive impairment, randomized clinical trial evidence supports total hip arthroplasty over unipolar or bipolar hemiarthroplasty, demonstrating superior long-term pain relief, higher validated functional scores, and reduced reoperation rates related to acetabular cartilage erosion.
• Femoral Fixation Strategy (Cemented vs. Cementless): In patients with osteopenic or osteoporotic bone and cylindrical Dorr Type C canals, cementless femoral stems carry a significantly elevated risk of intraoperative periprosthetic fracture (calcar split or trochanteric fracture, 3-5% vs. < 1%) and early postoperative subsidence. Polished tapered cemented femoral stems provide immediate interlock, load transfer, and superior implant survivorship in this demographic.
• Mitigating Bone Cement Implantation Syndrome (BCIS): Cemented femoral fixation in elderly patients with cardiopulmonary comorbidity requires proactive intraoperative precautions: thorough canal pulse lavage to remove marrow debris, canal vacuum suctioning, retrograde cement pressurization using a distal restrictor plug, avoidance of excessive unvented pressurization, and vigilant communication with anesthesia during cement insertion.

Case 5: The Painful Total Hip Arthroplasty – Diagnostic Triage and Revision Strategies

Clinical Vignette: A 61-year-old male presents 18 months following an uncomplicated right total hip arthroplasty with progressive anterior groin pain, an antalgic limp, and an audible and palpable clicking sensation during active straight-leg raising and getting out of a low car seat. Radiographs demonstrate well-fixed cementless components without gross loosening, but the acetabular cup exhibits slight anterior prominence beyond the bony anterior acetabular rim.

• Step 1: Rule Out Periprosthetic Joint Infection (PJI): In any painful hip arthroplasty, occult infection must be systematically excluded regardless of clinical presentation. Serum ESR and CRP represent essential first-line screening tests. If either marker is elevated, or if clinical suspicion remains high, image-guided hip joint aspiration with synovial fluid leukocyte count, polymorphonuclear (PMN) percentage, and aerobic/anaerobic cultures must be performed prior to any surgical re-exploration.
• Step 2: Assess Mechanical Impingement & Component Positioning: Anterior cup prominence, excessive cup retroversion, or an unaddressed anterior osteophyte can cause chronic mechanical irritation and tendinopathy of the overlying iliopsoas tendon as it crosses the anterior acetabular rim. Cross-sectional axial pelvic CT imaging with metal artifact reduction allows precise quantification of acetabular cup version, inclination, and anterior cup overhang in millimeters.
• Step 3: Diagnostic Injection & Therapeutic Algorithm: An ultrasound- or fluoroscopically-guided iliopsoas bursa injection with local anesthetic and corticosteroid provides definitive confirmation if symptoms temporarily resolve. Nonoperative management with physical therapy and anti-inflammatory medications is first-line. If conservative care fails and cup position is otherwise acceptable (well-fixed, stable, anatomically positioned within the spinopelvic functional zone), arthroscopic or open iliopsoas tenotomy at the level of the acetabular rim provides reliable symptom resolution without requiring formal revision of the acetabular component.

3. Surgical Anatomy & Danger Zones

Safe execution of total hip arthroplasty requires mastery of three-dimensional pelvic and proximal femoral anatomy, including internervous planes and adjacent neurovascular structures at risk.

Internervous & Intermuscular Corridors

• Direct Anterior Approach (Hueter Interval): Explores the interval between the tensor fasciae latae (innervated by the superior gluteal nerve) laterally and the sartorius and rectus femoris (innervated by the femoral nerve) medially. This represents a true internervous and intermuscular plane.
• Anterolateral Approach (Watson-Jones Interval): Develops the interval between the tensor fasciae latae and the anterior border of the gluteus medius, both supplied by the superior gluteal nerve (intermuscular, but not internervous).
• Posterolateral Approach (Moore / Southern): Traverses the fibers of the gluteus maximus (inferior gluteal nerve) and detaches the short external rotators (piriformis, superior gemellus, obturator internus, inferior gemellus) and posterior capsule, preserving the gluteus medius and minimus intact on the greater trochanter.

Neurovascular Structures at Risk & Wasielewski Quadrants

• Sciatic Nerve: Situated immediately posterior to the external rotators and quadratus femoris. The peroneal division is especially susceptible to traction injury during vigorous leg lengthening (> 2 cm), direct thermal injury from electrocautery, or direct compression from posterior acetabular retractors misplaced beyond the posterior column.
• Femoral Nerve and Vessels: Lie directly anterior to the anterior acetabular wall, separated only by the iliopsoas muscle and tendon. Overly aggressive or unpadded anterior retractor placement over the anterior rim can cause femoral nerve neuropraxia or laceration of the femoral artery and vein.
• Lateral Femoral Cutaneous Nerve (LFCN): Traverses the inguinal ligament near the anterior superior iliac spine (ASIS). Its branches run adjacent to the superficial interval of the direct anterior approach; excessive lateral retraction or distal branch division leads to anterolateral thigh numbness or meralgia paresthetica.
• Superior Gluteal Nerve: Traverses through the greater sciatic notch above the piriformis, coursing between the gluteus medius and minimus. Splitting the gluteus medius more than 3 to 5 cm proximal to the greater trochanter tip risks permanent denervation of the anterior abductor muscle belly.
• Wasielewski Posterior-Superior Quadrant: Safe zone for dome screw fixation into the dense bone of the sciatic buttress.
• Wasielewski Posterior-Inferior Quadrant: Safe zone for shorter screws into the ischium (mind the internal pudendal and inferior gluteal vessels).
• Wasielewski Anterior-Superior Quadrant: High-risk danger zone containing the external iliac artery and vein. Screws must not penetrate the anterior cortex.
• Wasielewski Anterior-Inferior Quadrant: High-risk danger zone containing the obturator neurovascular bundle. Screw placement is strictly prohibited.

4. Preoperative Planning, Templating & Biomechanics

Precise preoperative templating on calibrated digital radiographs (AP pelvis centered on the pubic symphysis with a 25 mm calibration sphere and true cross-table lateral of the hip) allows anticipation of implant dimensions, leg length discrepancies, and femoral offset.

Biomechanical Triad of Hip Reconstruction

• Center of Rotation (COR): Reconstructing the anatomic center of rotation reduces joint contact stress. Superior or lateral cup placement shortens the abductor moment arm, increasing joint reaction forces and accelerating bearing wear.
• Femoral Offset: Represents the perpendicular distance from the femoral head center to the long axis of the femoral shaft. Restoring or slightly increasing femoral offset increases the abductor moment arm, eliminates soft-tissue laxity, prevents bony or prosthetic impingement against the pelvis, and decreases joint reaction forces.
• Leg Length Parity: Accurately established by referencing the trans-ischial or trans-teardrop line to the lesser trochanters bilaterally. Over-lengthening risks sciatic or peroneal neuropraxia, pelvic tilt, and intractable low back pain; under-lengthening precipitates abductor limp and soft-tissue laxity leading to dislocation.

Spinopelvic Motion & The Dynamic Safe Zone

The classical Lewinnek safe zone (inclination 40° ± 10°, anteversion 15° ± 10°) represents a static guideline that fails to account for dynamic spinopelvic interaction. In normal individuals, the pelvis rotates posteriorly (sacral slope decreases, pelvic tilt increases) when transitioning from standing to sitting, which naturally increases functional acetabular anteversion and inclination to accommodate femoral flexion without anterior impingement. In patients with stiff or fused lumbar spines (e.g., prior multi-level posterior spinal fusion), the pelvis cannot rotate posteriorly upon sitting, leading to anterior prosthetic impingement and posterior dislocation. Conversely, when standing, a stiff flatback posture causes anterior dislocation. Preoperative standing and sitting lateral lumbar-pelvis radiographs must be obtained in patients with spinal deformity or fusion to tailor cup orientation.

5. Surgical Approaches & Soft-Tissue Management

Each surgical approach has distinct mechanical advantages, exposure corridors, and soft-tissue release protocols:

• Direct Anterior Approach (DAA): Performed supine with or without a specialized traction table. Preserves posterior capsuloligamentous structures and abductors. Key steps include ascending branch ligation of the lateral femoral circumflex vessels, anterior capsule excision, and complete release of the pubofemoral ligament and posterior-superior capsule off the femoral neck saddle to deliver the femur for broaching.
• Posterolateral Approach: Performed in the lateral decubitus position. Provides unparalleled visualization of the posterior column and proximal femur. Critical soft-tissue steps mandate meticulous identification and elevation of the piriformis and conjoint tendon with stay sutures, followed by a formal posterior capsulotomy. Anatomical repair of the capsule and external rotators through transosseous drill holes into the greater trochanter reduces posterior dislocation rates to less than 1%.
• Direct Lateral Approach (Hardinge): Splits the anterior third of the gluteus medius and vastus lateralis as a continuous muscular sleeve. Offers excellent stability with negligible posterior dislocation risk, but carries a 5-10% risk of postoperative Trendelenburg lurch due to superior gluteal nerve traction or incomplete abductor tendon healing.

6. Component Fixation & Bearing Surface Selection

Implant longevity depends on durable biological or mechanical interlock and wear-resistant tribology:

• Acetabular Fixation: Hemispherical titanium shells with highly porous surface structures (trabecular titanium or porous tantalum) provide high friction coefficients and rapid osteointegration. Preparation typically employs under-reaming by 1 mm for press-fit stability in normal bone, supplemented by supplementary dome screws in osteopenic bone or complex cases.
• Femoral Fixation: Cementless tapered-wedge stems provide reliable proximal metaphyseal fit and rotational stability in Dorr Type A and B canals. Fully hydroxyapatite-coated or grit-blasted stems promote biological ingrowth. In cylindrical Dorr Type C canals with thin cortices, polished tapered cemented stems using modern third-generation cementing techniques (canal plug, vacuum mixing, retrograde gun delivery, pressurized insertion) eliminate periprosthetic fracture risk and subsidence.
• Bearing Surface – Highly Cross-Linked Polyethylene (HXLPE): Irradiated and remelted/annealed polyethylene reduces volumetric wear by over 80% compared to conventional polyethylene, demonstrating annual linear wear rates under 0.02 mm/year at 20-year follow-up.
• Bearing Surface – Ceramic-on-Polyethylene (CoP): Delta ceramic heads articulating against HXLPE represent the worldwide gold standard for both young and elderly patients, offering minimal wear, chemical inertness, and resistance to third-body scratching.
• Bearing Surface – Dual Mobility Articulations: Features a mobile polyethylene liner that articulates with a small femoral head (inner bearing) and a polished metal acetabular shell (outer bearing). Dual mobility substantially increases effective jump distance and impingement-free range of motion, and is indicated in high-risk instability populations (neuromuscular disorders, abductor deficiency, spinopelvic rigidity, prior lumbar fusion, and revision THA).

7. Classification Systems in Total Hip Arthroplasty

Validated clinical and radiographic classification systems guide surgical decision-making and predict implant survivorship:

8. Postoperative Management & Fast-Track Protocols

Modern fast-track arthroplasty protocols reduce hospital length of stay, optimize pain management, and accelerate functional recovery while lowering complication rates:

• Multimodal Analgesia (PROSPECT Recommendations): Preemptive oral acetaminophen and COX-2 inhibitors or non-steroidal anti-inflammatory drugs (NSAIDs), intraoperative local infiltration analgesia (LIA) combining long-acting local anesthetic (e.g., ropivacaine) with epinephrine infiltrated systematically into the posterior capsule, periacetabular tissues, and abductor musculature, and limited rescue oral opioids. Intrathecal morphine or motor-sparing peripheral nerve blocks (such as PENG – pericapsular nerve group block) can be considered.
• Immediate Ambulation: Full weight-bearing as tolerated is initiated on postoperative day 0 within 2 to 4 hours of surgical completion once spinal motor block has resolved. Early mobilization prevents venous stasis, reduces pulmonary atelectasis, and builds patient confidence.
• Venous Thromboembolism (VTE) Prophylaxis: Risk-stratified thromboprophylaxis combining mechanical pneumatic compression devices with chemical prophylaxis. In standard-risk patients, modern clinical practice guidelines and large randomized trials endorse oral aspirin (81 mg twice daily or 100 mg daily for 30-35 days) as non-inferior to low-molecular-weight heparin (LMWH) or direct oral anticoagulants (DOACs), with significantly lower bleeding and wound drainage complications. High-risk patients (prior VTE, active malignancy, hypercoagulable state) receive targeted DOAC or LMWH therapy.

9. Complications & Salvage Strategies

Complications in total hip arthroplasty can be categorized temporally into intraoperative, early postoperative, and late structural failures:

Intraoperative Complications

• Calcar and Greater Trochanter Fractures: Intraoperative calcar cracks during femoral broaching or stem seating occur in 1-3% of cementless stems. Recognition prior to final stem insertion is vital; placement of a prophylactic or therapeutic cerclage wire or cable around the proximal femoral neck below the lesser trochanter stabilizes the calcar and prevents propagation during stem impaction.
• Vascular Injury: Caused by errant screw placement through the anterior acetabular quadrants or retractors penetrating the anterior capsule. Emergency vascular surgery intervention and retroperitoneal exposure are required if active arterial pulsatile bleeding occurs.

Early Postoperative Complications (0 to 6 Weeks)

• Prosthetic Dislocation: Early instability results from component malorientation, inadequate soft-tissue tension, or patient compliance breakdown. Closed reduction under conscious sedation is performed. Persistent recurrent instability necessitates revision to optimize component orientation, convert to larger head size, or implant a dual mobility construct.
• Acute Periprosthetic Joint Infection: Developing within 4 weeks of surgery. Managed with urgent debridement, antibiotics, and implant retention (DAIR) with exchange of all modular components (polyethylene liner and femoral head).

Late Postoperative Complications (> 6 Weeks)

• Aseptic Loosening & Osteolysis: Secondary to mechanical micromotion or wear-debris-mediated macrophage activation. Presenting with progressive groin or thigh pain and continuous radiolucent lines (> 2 mm) or component migration. Revision to porous-coated biological fixation components is indicated.
• Trunnionosis & Adverse Local Tissue Reaction (ALTR): Mechanically assisted crevice corrosion at the modular head-neck junction can generate metallic wear debris, presenting as pain, cystic pseudotumors, or abductor destruction. Treatment entails revision to a ceramic head with a titanium sleeve or stem revision if trunnion damage is severe.

10. Pearls and Pitfalls

Synthesizing critical surgical judgment pearls to prevent common intraoperative errors:

• The Pelvic Position Trap: Patient lateral pelvic tilt or anterior/posterior roll during lateral decubitus positioning alters perceived acetabular inclination and anteversion. The pelvis must be rigidly secured with perpendicular positioning pegs, and anatomic bony landmarks (transverse acetabular ligament, anterior and posterior walls) verified prior to reaming.
• The Transverse Acetabular Ligament (TAL) Pearl: The TAL serves as a patient-specific anatomical guide for acetabular cup version and depth. Aligning the inferior border of the cup parallel to the TAL prevents excessive anteversion and vertical cup positioning.
• Calcar Crack Prophylaxis: In elderly patients with stiff Dorr Type A or osteopenic Type C bone, place a prophylactic cable around the proximal femoral metaphysis prior to final broaching if resistance is high, completely protecting the femur against longitudinal fracture propagation.
• Leg Length Parity Assessment: Compare intraoperative leg lengths using multiple independent methods: fixed pelvic pin caliper measurements, palpation of the contralateral knee and malleoli through sterile drapes, and restoration of the preoperatively templated lesser trochanter-to-head center distance.

11. Contemporary Controversies & Clinical Debate

• Direct Anterior vs. Posterolateral Approach: Extensive debate persists regarding the clinical superiority of the DAA over the posterolateral approach. While DAA demonstrates modestly accelerated recovery during the initial 2 to 6 weeks and lower posterior dislocation rates, high-level meta-analyses demonstrate identical functional scores, pain relief, and implant survivorship at 1 year, accompanied by higher rates of lateral femoral cutaneous nerve neuropraxia and femoral fracture during the surgical learning curve.
• Routine vs. Selective Dual Mobility Articulations: Proponents advocate for expanded use of dual mobility bearings in primary THA to virtually eliminate dislocation. However, concerns regarding intra-prosthetic dislocation, increased volumetric polyethylene wear over decades, and higher implant costs currently confine routine use to elderly patients, those with spinopelvic rigidity, neuromuscular deficits, or revision procedures.
• Cementless vs. Cemented Stems in the Elderly Female: Despite registry data from Europe and Australia showing significantly lower periprosthetic fracture and revision rates with cemented stems in patients aged 70 and older, cementless stem utilization remains high in North America. Educational initiatives and updated guidelines strongly recommend cemented femoral fixation in elderly patients with osteopenic bone to minimize catastrophic perioperative fracture morbidity.

12. Master Class Pro-Tip

“Master Class Surgical Pearl: In complex primary total hip arthroplasty, never adjust femoral neck length solely to resolve soft-tissue laxity without first evaluating femoral offset. Lengthening the prosthetic neck to achieve joint stability increases vertical leg length, causing postoperative leg length inequality that patients immediately notice and rarely forgive. If the hip is unstable on trial reduction, first optimize horizontal femoral offset using a high-offset stem option or lateralized liner. Restoring the abductor moment arm restores tension across the abductor complex and gluteus medius myofibers, conferring robust stability and preventing prosthetic impingement while preserving exact leg length parity.”

Master Class Surgical Pearl

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

• Chen X, Li X, Zhu Z et al. Effects of progressive resistance training for early postoperative fast-track total hip or knee arthroplasty: A systematic review and meta-analysis. Asian J Surg. 2021. doi:10.1016/j.asjsur.2021.02.007 [Level I (Therapeutic): Systematic Review / Meta-Analysis]
• Anger M, Valovska T, Beloeil H et al. PROSPECT guideline for total hip arthroplasty: a systematic review and procedure-specific postoperative pain management recommendations. Anaesthesia. 2021. doi:10.1111/anae.15498 [Level I (Therapeutic): Systematic Review / Meta-Analysis]
• 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 (Therapeutic): Systematic Review / Meta-Analysis]
• Steven M. Kurtz, Kevin Ong, Edmund Lau et al. Projections of Primary and Revision Hip and Knee Arthroplasty in the United States from 2005 to 2030. Journal of Bone and Joint Surgery. 2007. doi:10.2106/jbjs.f.00222 [Level V (Expert Conceptual Review): Seminal Conceptual / Observational Study]
• William Geerts, Graham F. Pineo, John A. Heit et al. Prevention of Venous Thromboembolism. CHEST Journal. 2004. doi:10.1378/chest.126.3_suppl.338s [Level V (Expert Conceptual Review): Seminal Conceptual / Observational Study]