Last Updated on January 12, 2024
Ankle arthrodesis or ankle fusion is the surgical fusion of ankle joint articular surfaces to block the motion of the ankle. It is commonly performed for end-stage arthritis resulting from various ankle conditions.
Though recent studies have suggested a better functional outcome with ankle arthroplasty and its use is increasing, ankle arthrodesis is still a common treatment for end-stage arthritis. End-stage ankle arthritis is a condition that causes pain and swelling in the ankle joint where the symptoms are worsened by standing and moving. It could be the result of trauma or some other condition affecting the ankle.
In young, highly active patients ankle arthrodesis is preferred as ankle arthroplasty may not meet the functional requirement and is associated with greater complications.
Relevant Anatomy
Indications of Ankle Arthrodesis
Ankle fusion is indicated in cases of end-stage arthritis after a minimum of 3 months of conservative treatment has been tried. End-stage arthritis can result from many conditions of the ankle. Common conditions are given below
- Posttraumatic
- Rheumatoid arthritis
- Infection
- Neuromuscular disorders
- Bone tumors around the ankle
- Osteoarthritis
Ankle arthrodesis is also done for
- Failed total ankle arthroplasty.
- Failed previous ankle fusion
Contraindications
- Active infection at the site
- Vascular diseases
- patient not ready to accept compromise of the movement (as evaluated after putting preoperative simulating cast)
Position
The goal is to provide a plantigrade foot for maximum functional use.
The optimal position for ankle arthrodesis is
- 0 degrees of flexion
- 0 to 5 degrees of valgus
- 5 to 10 degrees of external rotation with a slight posterior displacement of the talus.
In case of genu recurvatum and hindfoot varus deformities, the foot can be kept in equinus.
Before proceeding with arthrodesis, a below-knee cast is applied in the desired position to see if the patient can tolerate the loss of movement due to fusion.
Approaches of Ankle Arthrodesis
Ankle fusion can be done by open dissection or using an arthroscopic approach.
Open Method
The ankle can be accessed using any of the following approaches.
- Anterior
- Posterior
- Medial
- Lateral
- Combined Medial and Lateral
The open approach provides better exposure and thus makes it easier to correct the deformities and apply implants like plates. However, the extensive dissection of soft tissue can also lead to a greater risk of postoperative complications. The open method should be used in moderate to severe ankle deformities.
Arthroscopic Method
An arthroscopic method is typically for patients with no or mild deformity. Typically, an arthroscopic approach can be used in patients with less than 15 degrees of varus or valgus. The recent studies have suggested better union rates with the arthroscopic method.
Arthroscopic ankle fusion is also associated with lesser complications as the dissection is minimal.
Arthroscopically assisted ankle arthrodesis offers the advantages of
- Quicker fusion because of the limited exposure and less extensive periosteal stripping
- Preserving the ankle mortise’s overall contour gives a better cosmetic result.
Fixation Methods in Ankle Arthrodesis
Both internal and external fixation methods are used in ankle arthrodesis. Each implant has its unique advantages and disadvantages and the use comes down to patient profile, deformity, and surgeon’s preference. The results with internal fixation methods are better than external fixation.
External fixation
External fixation is typically used in
- Patients with significant bone defects
- Limb length discrepancy
- Poor bone quality,
- Infection
Different types of external fixation devices that are used in ankle arthrodesis are
- Ring Fixator
- Tubular external fixators
- Charnley fixation clamp
- Calandruccio compression device
Internal Fixation
Internal fixation has several theoretical advantages over external fixation.
- Ease of insertion
- Patient convenience
- Comparable rates of delayed union, malunion, nonunion, and infection
- Greater resistance to shear stress.
The following modalities are used in internal fixation
- Cancellous screws – parallel or crossed
- Easier to use
- It can be used arthroscopically
- Plating
- Direct compression plates
- Lateral T-plate
- Posterior blade plate fixation.
- Plates offer stronger and more rigid constructs
- Kirschner wires
- Retrograde intramedullary nails
- Especially when subtalar arthrodesis also needs to be done
Procedure of Ankle Arthrodesis
Open Procedure
The patient is placed in a supine or lateral position depending on the approach. The joint is approached with the preoperatively decided approach.
The tibiofibular joint is identified and soft tissues including ligaments and interosseous membrane are resected. An osteotomy of the fibula is done in several procedures but some surgeons prefer to spare fibula. In any case, the fibular cartilage is denuded to promote the union of the susion. Ankle joint is identified, and accessed, and joint surfaces are fully exposed. The cartilage is removed from both the tibia and talus to expose the subchondral bone while maintaining joint congruency.
The joint is placed in the desired arthrodesis position and fixed with temporary K-wires. Pushing the talus posteriorly increases the contact surface of the joint and also reduces the lever arm of the construct. The joint is fixed by using an appropriate implant like screws or plate. A bone graft may be used to enhance the union. The bone graft can be taken from the tibia or either the lateral or medial malleolus.
Arthroscopic Procedure
Arthroscopic arthrodesis approaches the joint by usual arthroscopy of the ankle. Using shavers, the joint cartilage is removed and the joint is fixed with cannulated cancellous screws under fluoroscopy.
Postoperatively, the arthrodesed ankle joint is kept in a leg cast for six weeks and the limb is kept non-weight bearing for that period. Then, the cast is removed and the limb is put in a walker boot. Fusion is assessed by x-rays and the patient may be allowed partial weight bearing if the progress is satisfactory. The patient is allowed full weight bearing after fusion union has occurred.
Prognosis
In general overall shortening generally is less than 1 cm and the fusion rate is 80% to 90%.
Arthrodesis offers good pain relief but limited hindfoot motion can result in difficulty walking on uneven surfaces. The development of adjacent hindfoot arthritis is a concern.
References
- Yasui Y, Hannon CP, Seow D, Kennedy JG. Ankle arthrodesis: A systematic approach and review of the literature. World J Orthop. 2016 Nov 18;7(11):700-708. [Link]
- Betz MM, Benninger EE, Favre PP, Wieser KK, Vich MM, Espinosa N. Primary stability and stiffness in ankle arthrodesis-crossed screws versus anterior plating. Foot Ankle Surg. 2013;19:168–172. [Link]
- Ling JS, Smyth NA, Fraser EJ, Hogan MV, Seaworth CM, Ross KA, Kennedy JG. Investigating the relationship between ankle arthrodesis and adjacent-joint arthritis in the hindfoot: a systematic review. J Bone Joint Surg Am. 2015;97:513–520. [Link]
