What are the fundamentals of total hip arthroplasty—including hip anatomy, surgical approaches, operative steps, peri‑operative management, and postoperative care—for an orthopaedic resident?

Total Hip Arthroplasty: Comprehensive Guide for Orthopaedic Residents

Hip Anatomy Relevant to THA

The hip joint is a ball-and-socket articulation between the femoral head and acetabulum, requiring thorough understanding of surrounding neurovascular structures and muscular anatomy for safe surgical exposure. 1

Key Anatomical Considerations:

• Femoral head and neck: The femoral neck osteotomy level must be predetermined by preoperative templating to restore proper leg length and offset 2
• Acetabulum: Provides the socket for prosthetic cup placement, requiring adequate bone stock for fixation 3
• Neurovascular structures: The sciatic nerve (posterior approach), superior gluteal nerve (lateral approach), and lateral femoral cutaneous nerve (anterior approach) are at risk depending on surgical approach 1, 4
• Muscular anatomy: Abductor mechanism (gluteus medius and minimus) is critical for postoperative gait and must be preserved or adequately repaired 1

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Surgical Approaches

The three most commonly used approaches are posterior, direct lateral (Hardinge), and direct anterior, each with distinct anatomical planes and complication profiles. 1, 4

Posterior Approach:

• Internervous plane: Between gluteus maximus (inferior gluteal nerve) and short external rotators 4
• Advantages: Excellent acetabular and femoral exposure, preserves abductor mechanism 1
• Disadvantages: Higher historical dislocation rates (mitigated by posterior capsular repair) 1, 4
• At-risk structures: Sciatic nerve (especially with retraction or leg lengthening) 1

Direct Lateral (Hardinge) Approach:

• Technique: Splits gluteus medius and minimus in line with their fibers, detaching anterior portion from greater trochanter 1
• Advantages: Lower dislocation risk, stable hip construct 4
• Disadvantages: Risk of abductor insufficiency (Trendelenburg gait) if repair fails 1
• At-risk structures: Superior gluteal nerve (stay anterior to avoid) 1

Direct Anterior Approach:

• Internervous plane: Between tensor fascia lata (superior gluteal nerve) and sartorius (femoral nerve) 4
• Advantages: True internervous and intermuscular plane, potentially faster recovery 4
• Disadvantages: Steep learning curve, lateral femoral cutaneous nerve injury (meralgia paresthetica), femoral fracture risk 1, 4

Current evidence shows inconsistent differences in clinical outcomes between approaches; surgeons should use the approach they are most experienced with rather than switching based on perceived superiority. 5, 1, 4

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Operative Steps (Lateral Hardinge Approach as Example)

Preoperative Planning:

• Templating: Perform on calibrated radiographs to determine component sizes, femoral neck osteotomy level, and predict leg length/offset restoration 2, 6
• Patient optimization: Implement structured preoperative exercise and education programs 2

Intraoperative Sequence:

1. Exposure and Dislocation:

• Split gluteus medius/minimus and detach anterior portion from greater trochanter 1
• Perform capsulotomy and dislocate hip 1

2. Femoral Neck Osteotomy:

• Execute osteotomy at the predetermined templated level 2
• Remove femoral head 2

3. Acetabular Preparation:

• Expose acetabulum by removing labrum and osteophytes 3
• Ream sequentially to bleeding subchondral bone 3
• Position cup at 40° inclination and 15-20° anteversion (safe zone) 3
• Achieve press-fit fixation (cementless) or cement fixation based on bone quality 3

4. Femoral Preparation:

• Elevate proximal femur into surgical field using bone hook or femoral elevator 2
• Open femoral canal at piriformis fossa using box chisel or awl 2
• Broach sequentially to templated size 2
• Ensure proper version (typically 10-15° anteversion) 3

5. Trial Reduction:

• Conduct trial reduction to assess leg length equality, offset restoration, and stability through full range of motion 2
• Adjust component sizes or positions if needed 3

6. Definitive Implantation:

• Insert final components (cemented or cementless femoral stem based on bone quality and patient factors) 3
• Reduce hip and reassess stability through full range of motion 2

7. Closure:

• Repair abductor mechanism securely to greater trochanter (critical for lateral approach) 1
• Close fascia lata and subcutaneous tissues in layers using heavy non-absorbable sutures 2
• Close skin 2

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Perioperative Pain Management

The analgesic regimen should include paracetamol plus COX-2 inhibitors or NSAIDs as the foundation, with regional techniques added for high-risk pain patients, while avoiding epidural, femoral/lumbar plexus blocks, and gabapentinoids due to unfavorable risk-benefit profiles. 5, 2

Preoperative/Intraoperative:

• Basic analgesia: Administer oral paracetamol with NSAIDs or COX-2 inhibitors preoperatively 5, 2
• Dexamethasone: Give single IV dose of 8-10 mg intraoperatively for analgesic and antiemetic benefit 5, 2
• Regional analgesia: Consider fascia iliaca block or local infiltration analgesia (LIA) in patients with contraindications to basic analgesics or expected high postoperative pain 5, 2
• Intrathecal morphine: If spinal anesthesia is used, 0.1 mg intrathecal morphine may be added, though the guideline emphasizes associated risks (respiratory depression, pruritus, urinary retention) 5, 2

Postoperative:

• Continue paracetamol and NSAIDs/COX-2 inhibitors as primary strategy 5, 2
• Opioids for rescue only to minimize opioid-related adverse effects 5, 2

Techniques NOT Recommended:

• Epidural analgesia: Adverse effects outweigh benefits 5, 2
• Femoral nerve block: Risk of quadriceps weakness and falls 5, 2
• Lumbar plexus block: Complications exceed benefits 5, 2
• Gabapentinoids: No consistent analgesic benefit with significant side effects 5, 2

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Anesthetic Considerations

Either spinal or general anesthesia is appropriate; the choice should be based on patient factors and anesthesiologist preference rather than pain outcomes, as both techniques produce equivalent results. 5, 2

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Implant Selection

Bearing Surfaces:

• Metal-on-polyethylene: Most common, reliable long-term results 3
• Ceramic-on-polyethylene: Lower wear rates than metal-on-polyethylene 3
• Ceramic-on-ceramic: Lowest wear but risk of squeaking and fracture 3
• Metal-on-metal: Largely abandoned due to adverse reactions to metal debris (ARMD), pseudotumor formation, and elevated metal ions 7, 3

Femoral Fixation:

• Cementless: Preferred in younger patients with good bone quality 3
• Cemented: Preferred in elderly patients with osteoporotic bone 3

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Postoperative Management

Immediate Postoperative Care:

• Early mobilization: Ambulate on postoperative day 0 or 1 as part of rapid recovery protocols 8
• Venous thromboembolism prophylaxis: Implement according to institutional protocols 8
• Blood management: Minimize transfusions through multimodal blood conservation strategies 8

Hip Precautions:

• Approach-specific: Posterior approach traditionally requires posterior precautions (no flexion >90°, no adduction past midline, no internal rotation), though modern capsular repair may reduce dislocation risk 1
• Lateral approach: Generally fewer restrictions due to lower dislocation risk 1

Rehabilitation:

• Physical therapy: Focus on gait training, strengthening, and range of motion 8
• Occupational therapy: Teach activities of daily living modifications 8

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Follow-Up and Surveillance

Early postoperative surveillance within the first year enables evaluation of wound healing, detection of complications, and assessment of functional recovery. 7

Standard Follow-Up:

• Baseline radiographs: Obtain and archive postoperative radiographs as reference for future comparison 7
• First year: Schedule visits to monitor wound healing, early complications, and functional recovery 7

Metal-on-Metal Implants (Special Considerations):

• Routine follow-up: Every 1-2 years for asymptomatic MoM prostheses per FDA recommendations 7
• Imaging: Standard radiographs to evaluate positioning, loosening, osteolysis, and ARMD signs 7
• MRI surveillance: Beneficial because pseudotumor formation can occur asymptomatically 7
• Combined approach: Ultrasound plus metal-artifact-reduction sequence MRI (MARS-MRI) improves ARMD detection accuracy 7

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Common Complications and Prevention

Dislocation:

• Risk factors: Posterior approach (without capsular repair), component malposition, impingement, abductor insufficiency 1
• Prevention: Proper component positioning, capsular repair (posterior approach), abductor repair (lateral approach) 1

Abductor Insufficiency:

• Risk: Primarily with lateral approach if repair fails 1
• Prevention: Secure reattachment of abductors to greater trochanter 1

Nerve Injury:

• Sciatic nerve: Posterior approach, especially with excessive retraction or leg lengthening 1
• Superior gluteal nerve: Lateral approach if dissection extends too posterior 1
• Lateral femoral cutaneous nerve: Anterior approach (meralgia paresthetica) 1

Fracture:

• Intraoperative femoral fracture: Higher risk with anterior approach and cementless stems 1
• Prevention: Careful broaching technique, recognize risk factors (osteoporosis, revision surgery) 3

Infection:

• Prevention: Antibiotic prophylaxis, meticulous sterile technique, glycemic control 8

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Evidence Quality Considerations

While THA is highly successful at relieving pain and improving function, high-quality randomized controlled trials comparing THA to non-operative management are lacking, and some improvement may be attributable to natural history or non-surgical co-interventions rather than surgery alone. 9 This does not diminish THA's effectiveness for end-stage hip arthritis but highlights the need for appropriate patient selection and realistic outcome expectations 9, 3