Arthroscopic Ankle Arthrodesis

Arthritis of the ankle can evolve from multiple causes, including, but not limited to, osteoarthritis, rheumatoid arthritis, and posttraumatic conditions. As the condition progresses, it generally leads to increased pain, gait abnormalities, and diminished function.

Surgical remedies are employed when conservative measures fail; they consist of the time-honored tibiotalar arthrodesis as well as total ankle replacement.^{2–4,9,19,21,28}

We will be discussing and illustrating the technique of arthroscopic ankle arthrodesis (AAA).^7,12,17,23

ANATOMY

The ankle joint is composed of the tibiotalar and fibulotalar articulations, with the fibula bearing about one-fifth of the weight-bearing stress across the ankle joint (FIG 1).

PATHOGENESIS

As with any condition, when articular cartilage is destroyed, either by systemic or local disease, the progression of arthritis may be unpredictably slow or rapid. If malalignment is an accompanying factor, the progression and pain are usually more pronounced.

NATURAL HISTORY

Once the breakdown of the articular surface has begun, it will progress at a rate that is not always predictable. Radiographic changes will not always reflect the degree of pain that the patient presents with. Some patients will come to surgery early, whereas others may languish for decades without needing surgical intervention.

PATIENT HISTORY AND PHYSICAL FINDINGS

Generally, the patient will complain of pain with weight bearing, usually lateral more than medial. Generally, it localizes anteriorly in a band from the lateral to the medial side of the ankle. There may be associated swelling and occasional night pain. The symptoms may in part be relieved by nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, crutches, bracing, and activity modification. When other joints are involved, such as the knee and the hip, the discomfort in these areas may overshadow the ankle symptomatology.

The patient will generally walk with an antalgic gait, and if there is any leg length discrepancy, there may be a short-leg component to it. Gait will generally improve with the assistance of crutches or a cane.

Stability is assessed with talar tilt and anterior drawer tests.

Standing evaluation is critical in determining the feasibility of arthroscopic technique versus open as well as necessary osteotomies.

Range of motion will be restricted in all planes, and pain will be elicited at the extremes of range of motion.

Loss of dorsiflexion with plantarflexion contracture needs to be addressed at surgery.

Careful isolation of ankle joint motion during the examination is critical so as not to confuse it with pathologic changes in the subtalar or midtarsal joints.

There will usually be associated swelling about the ankle joint. Synovial hypertrophy, osteophytes, and generalized enlargement of the ankle will present rather than a frank effusion, which could indicate a systemic component.

IMAGING AND OTHER DIAGNOSTIC STUDIES

Standing anteroposterior (AP), lateral, and mortise radiographs are necessary to determine the extent of arthritis, alignment, presence of osteophytes, and the presence or absence of avascular necrosis of the talus (FIG 2). Minor degrees of malalignment may be corrected up to 7 degrees, varus being the most important element to reverse to neutral.

Magnetic resonance imaging (MRI) scans may be helpful if avascular necrosis is suspected.

Computed tomography (CT) may be indicated if bone loss needs to be addressed.

Should there be questions on the circulatory status, a vascular workup may be necessary.

DIFFERENTIAL DIAGNOSIS

Infection

Charcot joint

Pseudogout and gout

Osteochondral lesions of the talus

Impingement

Inflammatory synovitis

NONOPERATIVE MANAGEMENT

As with most arthritic conditions, a wide variety of nonoperative measures can be employed. Medication in the form of NSAIDs, acetaminophen, and glucosamine sulfate can be used with careful monitoring for side effects. Bracing with simple soft tissue supports or a custom-made ankle–foot orthosis (AFO) can be effective. Cortisone injections, if used sparingly, can offer short-term pain relief. Off-label hyaluronic acid injections have been used with some reported success.

SURGICAL MANAGEMENT

When patients fail to respond to conservative care, a number of procedures can be undertaken for isolated end-stage ankle arthritis. The time-honored procedure is an open ankle arthrodesis, but over the past 15 years, some surgeons have come to prefer AAA.

Total ankle arthroplasty has been popularized recently and has the obvious advantage of motion preservation at the cost of a more challenging technical procedure and a higher complication rate.¹⁶

AAA will be discussed in detail in the following section.

Preoperative Planning

We cannot overstress the need for a thorough evaluation of alignment before AAA is undertaken (FIG 3). The films must be done in a standing position and compared to the opposite side. Often, patients will present with outside films showing a pseudovarus deformity, but when a weight-bearing film is taken, the alignment is satisfactory.

All medical conditions must be addressed. Vascular status needs to be examined as well as the skin condition. Patients need to stop smoking 3 months before the operative procedure and must stay off NSAIDs 5 days before and 3 months after the surgery.

Perioperative antibiotics are used as well as postoperative deep venous thrombosis prophylaxis in high-risk patients.

Positioning

The patient is placed in a supine position.

The use of a leg holder and tourniquet allows the extremity to be placed in a neutral position so that both the anteromedial and anterolateral aspects of the ankle can be easily accessed.

The foot of the table is dropped about 30 degrees.

The ankle is placed in a sterile traction device using a tensiometer, controlling traction to about 25 pounds (FIG 4).

Approach

The approach that will be described is that of an AAA.

Generally, a two-portal technique can be used with anteromedial and anterolateral portals, and on occasion, accessory portals located anterolateral, anteromedial, or posterolateral for additional flow or drainage (FIG 5).