Indications for arthroscopic ankle fusion are similar to those for open procedures, with a few exceptions. Arthroscopic fusion is also a desirable option for patients who have compromise of the soft tissue envelope about the ankle. This may be due to prior trauma, vascular insult, or other systemic diseases [12] (Fig. 2.2).

The ideal scenario for an arthroscopic ankle fusion is a patient with severe ankle arthritis and minimal associated malalignment, defined as less than 10–15 degrees of coronal plane deformity and less than 10 mm of translation in the sagittal plane [11]. Arthroscopic ankle fusion has been successful in patients with a variety of conditions, including peripheral vascular disease [11], rheumatoid arthritis [11, 13], congenital deformity [9, 11], hemophilic arthropathy [11, 14–16], previous incisions about the foot and ankle [9, 17], and osteochondritis dissecans [11] (Fig. 2.3).

With arthroscopic techniques, it can be difficult to correct substantial deformity including rotation, translation, or varus/valgus malalignment [11]. Greater than 10–15 degrees of varus/valgus malalignment or more than 10 mm of anterior or posterior translation can be challenging to manage through an arthroscopic approach (Fig. 2.4). This is partly due to the fact that with arthroscopic fusion, there is minimal bony and/or soft tissue dissection, potentially leaving scar and extra-articular osteophytes that may block optimal positioning [11]. Additionally, arthroscopic correction is challenging in the setting of substantial bone loss, as structural bone grafting is difficult to perform through limited incisions. Avascular necrosis of the talus has historically been cited as a contraindication, although more recent evidence supports the use of minimally invasive approaches if less than 30% of the talus is affected [9]. Active infection is always a contraindication to arthrodesis, and relative contraindications include neuropathic arthropathy and smoking [12].

Standard preoperative evaluation begins with a detailed history. This includes eliciting a history of previous trauma, surgery, or other injuries. Comorbidities that may affect outcome must be reviewed, including diabetes, smoking, poor nutrition, and peripheral vascular disease. A thorough discussion regarding attempted non-operative measures should be held, including NSAIDs, bracing, physical therapy, or injections.

Physical examination begins with inspection of the ankle. This includes assessment of overlying skin changes, swelling, deformity (Fig. 2.5), previous incisions, and vascularity. Standing alignment with the patient facing both toward and away from the examiner should be evaluated. Gait should also be assessed. Range of motion of the tibiotalar, subtalar, and surrounding joints should be examined. If there is ankle equinus, it should be determined if this is due to bony impingement or either a gastrocnemius or combined gastroc-soleus contracture.

Because patients can have concurrent adjacent joint arthritis, the adjacent joints should be isolated and examined as a potential source of pain. This is an important point, as pain from surrounding joints can radiate proximally and present as ankle pain. The foot and ankle should be palpated to localize areas of tenderness, and muscle strength should be tested with resisted dorsiflexion, plantarflexion, eversion, and inversion. It is imperative to evaluate the neurovascular status of the foot and ankle. Both dorsalis pedis and posterior tibial artery pulses should be evaluated. If unable to be palpated, further workup with studies such as ankle brachial indices and toe oxygen pressures must be measured to confirm adequate blood flow. Sensation should be tested in the superficial peroneal, deep peroneal, sural, saphenous, and tibial nerve distributions. In a patient with known or suspected peripheral neuropathy, a Semmes-Weinstein filament is used to assess for protective sensation.

Preoperative radiographs should include weight-bearing anteroposterior (AP), lateral, and mortise views of the ankle. It is important to obtain weight-bearing views in order to provide a dynamic assessment of the foot and ankle. If hindfoot malalignment is suspected, a Harris hindfoot alignment or Saltzman alignment view can also be helpful. If there is uncertainty regarding the extent of arthritis, computed tomography (CT) is useful to define osseous architecture in further detail. CT imaging can also be helpful to evaluate for adjacent joint disease or define the extent of cystic change and/or bone loss in affected joints. In the setting of deformity, a scanogram can evaluate the overall alignment of the lower extremity. Magnetic resonance imaging (MRI) may be helpful in the setting of isolated cartilage defects or osteochondral lesions, but will have lower utility in more advanced arthritic processes.

In patients with a history of infection, persistent nonunion, or a history or physical examination worrisome for an infectious process, inflammatory markers including c-reactive protein and erythrocyte sedimentation rate should be obtained. In these patients, it is imperative to rule out any remaining infection prior to proceeding with arthrodesis. White blood cell count may also be obtained but in the setting of chronic infection will often be only mildly elevated or even normal.

In the setting of adjacent joint disease or difficulty ascertaining the true etiology of symptoms, selective fluoroscopic injections of the surrounding joints can be both diagnostic and therapeutic. These injections may be critical to identifying which joints are the true source of pain and can be helpful for accurate preoperative planning.

In the majority of cases, the initial treatment of ankle arthritis includes nonsurgical measures with an emphasis on alleviating pain. Non-operative modalities may include NSAIDs, activity modification, physical therapy, and walking aids. Bracing and/or immobilization may also be effective. Steroid injections also improve pain to varying degrees, but are somewhat unpredictable. When conservative modalities no longer provide lasting relief and symptoms are severely impacting the quality of life, surgical management carries a predictably high likelihood of achieving significant pain relief.