Definition
Hip arthrodesis is surgical fusion of the hip joint. It is now uncommon but remains a salvage option in carefully selected patients.
Indications
Possible indications include:
- young, highly active patient with severe unilateral hip disease in whom arthroplasty is undesirable
- painful post-traumatic or post-infective hip with preserved contralateral hip, ipsilateral knee and lumbar spine
- salvage after failed total hip arthroplasty in selected cases
- selected tumour or neuropathic conditions
Contraindications
Important contraindications include:
- active infection
- significant degenerative disease of the lumbar spine
- contralateral hip arthritis
- significant ipsilateral knee disease
- major limb-length discrepancy
- severe osteoporosis
- bilateral hip disease
Position of fusion
A functional fusion position is approximately:
- 20–35° flexion
- 0–5° adduction
- 5–10° external rotation
Excessive flexion produces increased lumbar lordosis and back symptoms. Excessive abduction or adduction alters gait and may create apparent limb-length inequality.
Principles of arthrodesis
Successful fusion requires:
- preparation of viable cancellous bone surfaces
- broad bone-to-bone contact
- rigid internal fixation
- correction of deformity
- preservation of satisfactory limb length and alignment
Fixation may be achieved with screws, plates or combined constructs depending on anatomy and previous surgery.
Consequences of hip fusion
A fused hip increases compensatory motion and loading through:
- lumbar spine
- ipsilateral knee
- contralateral hip
Gait becomes less efficient and energy expenditure increases.
Conversion of a fused hip to total hip arthroplasty
Conversion may be considered for:
- severe low-back pain
- symptomatic ipsilateral knee degeneration
- contralateral hip pain
- unacceptable functional limitation
Outcome is strongly influenced by the condition of the abductor mechanism. Conversion is technically demanding because of distorted anatomy, bone loss and soft-tissue contracture.
References
- Orthobullets. Hip Arthrodesis.