Bipolar hemiarthroplasty and lateral approach .
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bipolar hemiarthroplasty lateral approach hip
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hemiarthroplasty femoral neck fracture surgical approach
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Bipolar Hemiarthroplasty and the Lateral Approach
1. Hemiarthroplasty - Overview
Hemiarthroplasty replaces only the femoral head and neck with a stemmed component while leaving the native acetabulum intact. It is the standard treatment for:
- Displaced femoral neck fractures (Garden III/IV) in elderly/low-demand patients
- Patients with significant medical comorbidities or cognitive impairment (e.g., dementia, Parkinson disease), where compliance with dislocation precautions cannot be guaranteed
- Patients for whom THA's higher dislocation risk is unacceptable
"Those with a short life expectancy, significant medical comorbidities, or cognitive impairment are better served with hemiarthroplasty." - Campbell's Operative Orthopaedics 15th Ed 2026
2. Bipolar Hemiarthroplasty - Design and Mechanism
A bipolar prosthesis has two points of articulation, hence the name:
| Component | Articulation |
|---|---|
| Inner bearing | Artificial femoral head articulates within the outer metal shell (small, polished head inside a larger outer cup) |
| Outer bearing | The outer cup articulates with the native acetabular cartilage |
Rationale: By distributing motion across two surfaces, the bipolar design theoretically:
- Reduces wear on native acetabular cartilage compared to unipolar prostheses
- Provides a larger effective head size at the acetabulum, reducing dislocation risk
- Allows some motion within the prosthesis itself to reduce joint reactive forces
In contrast, a unipolar prosthesis has a fixed-size head that articulates directly with the native acetabulum with only one articulating surface.
"In the bipolar prosthesis (presently the most frequently used), the articulation is within the prosthesis itself." - Firestein & Kelley's Textbook of Rheumatology
3. Unipolar vs. Bipolar - Clinical Evidence
The evidence does not consistently show superiority of one over the other:
- Functional outcomes (Harris Hip Score, mobility): Similar between unipolar and bipolar at mid-to-long-term follow-up - Miller's Review of Orthopaedics 9th Ed
- Revision rates: Bipolar heads appear to offer similar revision rates compared with THA, whereas monopolar heads have higher revision rates after 3 months - Campbell's 2026
- The AAOS Guidelines rate the unipolar vs. bipolar recommendation as Moderate strength, stating "similar outcomes in unstable femoral neck fractures; bipolar may slightly lower revision rates"
4. Hemiarthroplasty vs. THA - Decision Framework
| Factor | Favors Hemiarthroplasty | Favors THA |
|---|---|---|
| Patient age/demand | Low-demand, elderly | Active, physiologically younger (ASA I-II, age <75) |
| Dislocation risk | Lower dislocation rate | Higher dislocation rate |
| Pre-existing arthritis | No significant arthropathy | Pre-existing OA/RA of hip |
| Cognitive status | Dementia/poor compliance | Cognitively intact, compliant |
| Mortality/comorbidity | High comorbidity burden | Charlson Comorbidity Index-adjusted cost-effective from age 44-65+ |
"A major concern with THA for femoral neck fracture is dislocation, which has led to an increased interest in using an anterior or anterolateral approach when THA is done for femoral neck fracture." - Campbell's 2026
5. The Lateral Approach (Hardinge/Direct Lateral Transgluteal Approach)
Eponym and Origin
The Hardinge approach (1982) is the most widely used lateral approach for hip arthroplasty. It is a modification of the McFarland and Osborne direct lateral approach, based on the observation that the gluteus medius and vastus lateralis are in functional continuity through the periosteum over the greater trochanter.
Patient Positioning
- Supine or lateral decubitus (lateral position is most common for hemiarthroplasty)
- Greater trochanter at the edge of the table
Incision
- Posteriorly directed lazy-J incision centered over the greater trochanter
Step-by-Step Technique (Hardinge - Technique 1.69, Campbell's)
- Divide the fascia lata in line with the skin incision over the greater trochanter
- Retract tensor fasciae latae anteriorly, gluteus maximus posteriorly
- Incise the tendon of gluteus medius obliquely across the greater trochanter, leaving the posterior half attached to the trochanter
- Carry the muscle split proximally in line with gluteus medius fibers at the junction of the middle and posterior thirds - no further than 4-5 cm from the tip of the greater trochanter (to protect the superior gluteal nerve and artery)
- Distally, carry the incision anteriorly in line with vastus lateralis fibers down to bone along the anterolateral femur
- Elevate the tendinous insertions of anterior gluteus minimus and vastus lateralis
- Abduct the thigh to expose the anterior capsule, then incise capsule as desired
- Closure: Repair gluteus medius tendon with non-absorbable braided sutures
Key Anatomical Danger: Superior Gluteal Nerve
- Lies approximately 5 cm proximal to the tip of the greater trochanter
- Muscle splitting beyond 4-5 cm risks transection of this nerve - Schwartz's Principles of Surgery 11th Ed
- Injury results in Trendelenburg gait / abductor weakness postoperatively
6. Advantages and Disadvantages of the Lateral Approach
| Feature | Lateral (Hardinge) Approach |
|---|---|
| Dislocation risk | Lower than posterior approach; comparable to anterior |
| Acetabular exposure | Excellent - good visualization for cup placement |
| Posterior column access | Limited vs. posterior approach |
| Abductor weakness | Higher risk of Trendelenburg limp vs. anterior/posterior |
| Heterotopic ossification | Lower risk than transtrochanteric lateral; higher vs. posterior |
| No trochanteric osteotomy | Advantage over historic Charnley technique |
| Extensile | Good; modifications (Dall, Head) for revision surgery |
"Residual abductor weakness and limp after this approach may be the result of avulsion of the repair of the anterior portion of the abductors or of direct injury to the superior gluteal nerve." - Campbell's 2026
7. Lateral Approach Variants for Hemiarthroplasty
| Variant | Key Feature |
|---|---|
| Watson-Jones (anterolateral) | Between gluteus medius and TFL; used for femoral neck fracture fixation and arthroplasty |
| Hardinge (direct lateral / transgluteal) | Splits gluteus medius/minimus; most common for hemiarthroplasty |
| Frndak modification | More anterior split over femoral head/neck; reduces retraction required |
| McLauchlan/Hay | Sims lateral position; rectangular bone slices from trochanter |
| Dall modification | Anterior abductor removed with thin bone wafer for better bony reattachment |
8. Why Lateral Approach for Hemiarthroplasty?
The lateral approach is specifically favored for hemiarthroplasty (and THA) for femoral neck fractures because:
- Lower dislocation rate than posterior approach - critically important given elderly patients with limited compliance
- Excellent acetabular visualization despite not replacing the cup
- Familiarity - widely taught and performed
- No need for a trochanteric osteotomy (unlike Charnley's original technique)
- The anterior approach (DAA) - though increasingly popular - carries higher femoral preparation difficulty and fracture risk in osteoporotic bone
9. Cemented vs. Cementless Stem
Cemented femoral components are recommended for femoral neck fractures treated with hemiarthroplasty:
- Osteoporotic bone in elderly patients makes press-fit fixation unreliable
- Moderate evidence favors cemented over non-cemented stems (functional outcomes and periprosthetic fracture rates)
- "Cemented femoral component is recommended when treating femoral neck fractures" - Miller's Review of Orthopaedics 9th Ed
10. Complications
| Complication | Notes |
|---|---|
| Dislocation | Lower with hemi vs. THA; lateral approach lowers risk further |
| Acetabular erosion | Progressive cartilage wear with bipolar prosthesis over years |
| Periprosthetic fracture | More risk with cementless in osteoporotic bone |
| Abductor weakness / Trendelenburg | Specific to lateral approach; from superior gluteal nerve injury or failed repair |
| Heterotopic ossification | Risk with any lateral approach; lower than transtrochanteric |
| Infection | ~1-2%; prophylactic antibiotics mandatory |
| Leg length discrepancy | Must be carefully managed intraoperatively |
| 1-year mortality | ~30% in elderly hip fracture patients (independent of surgical approach) |
Sources:
- Campbell's Operative Orthopaedics 15th Ed 2026, Chapter 60 (Femoral Neck Fractures), Chapter 1 (Surgical Approaches), Chapter 4 (Hip Arthroplasty)
- Miller's Review of Orthopaedics 9th Edition, Chapter 11 (Hip Fractures)
- Schwartz's Principles of Surgery 11th Ed, Chapter 43 (Joint Reconstruction)
- Bailey and Love's Short Practice of Surgery 28th Ed, Chapter 39
- Firestein & Kelley's Textbook of Rheumatology (Hemiarthroplasty in AVN)
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