Ankle Joint Replacements

Ankle joint replacement is at a more experimental stage than the well-established replacement operations for hip and knee joints.

Whereas the hip is a ball in socket joint and the knee is fundamentally a hinge joint, the ability of the ankle and forefoot to flex, extend, invert and evert makes is a complex joint. These actions are necessary to be able to walk over uneven ground.

Indications¹

Pain due to severe ankle arthritis, where conservative treatment is not providing adequate pain relief. (Ankle joint replacement does not generally increase mobility of the joint, though it usually maintains existing range of movement.)

The arthritis may be due to:

• Osteoarthritis including post-traumatic and after sports injuries
• Rheumatoid arthritis

Other treatments for ankle arthritis¹

Conservative treatments may be tried first:

• Non-surgical, including:
  • Analgesia
  • Orthotics, such as a splint and/or a shoe with a "rocker sole".
• Surgical:
  • Arthroscopic debridement
  • Ilizarov joint distraction - an external frame fixed around the joint

• It has a much lower rate of failure or complications and does not 'wear out'. It is equally effective for pain relief.
• The ankle joint will be rigid, although there can be some compensation from increased mobility at nearby joints.
• There is concern that it may lead to increased strain and therefore arthritis of nearby joints, particularly the subtalar joint. In practice, there seem to be radiological changes of the subtalar joint but few symptoms.

Replacement or fusion? Factors to consider¹

• Function of the whole limb and mobility of surrounding joints.
• Suitable patients for joint replacement tend to be in the older age group (over 50) and prepared to accept a rather higher risk of failure than with hip or knee arthroplasty.
• Younger patients are approached with more caution, as they have longer expected life, tend to be more active and so put prosthetic joints under more stress.
• Occupation and its likely stress on the joint must be considered.
• With bilateral ankle arthritis - a bilateral fusion can be disabling for certain tasks, e.g. getting up from a chair; in this situation, it may be preferable to replace one or both joints.

Contra-indications¹

• Muscle or neurological dysfunction of the limb
• Heavy manual occupation
• Severe deformity of the joint
• Local soft tissue problems e.g. skin ulcers
• Previous infection of the joint

Examples are:

• Agility™ Total Ankle System³
• Scandinavian Total Ankle Replacement (STAR)⁴
• Buechel-Pappas (BP) Ultra Total Ankle Replacement⁵

• DVT prophylaxis may be needed (as with any leg operation).
• Practical points after ankle replacement surgery¹ (details will vary according to surgical practice and patient's needs):
  • A splint or plaster cast will be fitted, and the patient may be non-weightbearing for several weeks.
  • Physiotherapy may be advised.
  • Driving may be possible after 3 months.

Function after ankle replacement¹

• Gait can be normal or near-normal (assuming the rest of the limb is unimpaired).
• Running is unlikely.
• Cycling and swimming are possible.

Complications

The following complications have been reported. (The figures quoted are examples only, taken from a systematic review⁶ and a private clinic website¹ with figures rounded to the nearest %).

• Deep infection of the joint (1-2%)
• Wound infection (1%)
• Delayed wound healing or breakdown (5%)
• Deep vein thrombosis or pulmonary embolism (1%)
• Pain and stiffness despite replacement (3-5%)
• Malleolar fracture (10%)
• Impingement (14%)
• Failure of implant (85% survival at 10 years)
• Further surgery needed (13%)
• Fusion needed following replacement surgery (6%)