Definition
Knee arthrodesis is surgical fusion of the tibiofemoral joint. It is principally a salvage procedure when a stable, painless mobile knee cannot be reconstructed reliably.
Indications
- Salvage after failed or repeatedly infected total knee arthroplasty
- Irreparable extensor mechanism failure in selected cases
- Severe bone or soft-tissue loss
- Tumour reconstruction in selected circumstances
- Painful post-traumatic or neuropathic joint where replacement is unsuitable
Active uncontrolled infection must be treated before definitive fusion.
Position of fusion
A functional fusion is generally positioned in:
- 5–8° valgus
- 0–10° external rotation
- 0–15° flexion
A small amount of shortening may assist foot clearance and sitting.
Techniques
Intramedullary fixation
- Provides a strong load-sharing construct
- Useful in salvage after failed arthroplasty
- May use a long fusion nail or modular device
Plate fixation
- Allows compression and control of alignment
- Requires adequate soft-tissue cover and bone stock
External fixation
Useful when infection or compromised soft tissues make internal fixation undesirable.
Principles
- Remove nonviable tissue and implants when indicated
- Obtain broad bleeding bone surfaces
- Correct deformity
- Achieve compression and stable fixation
- Use bone graft where required
Complications
- Nonunion
- Persistent or recurrent infection
- Fracture around fixation
- Limb-length discrepancy
- Increased stress on ipsilateral hip and ankle
- Contralateral knee and lumbar spine symptoms
References
- Orthobullets. Knee Arthrodesis.