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Foot and Ankle Pain MARK D. PRICE  •  CHRISTOPHER P. CHIODO

KEY POINTS The differential diagnosis for foot and ankle pain is vast. Localizing symptoms by anatomic region helps narrow this differential. On physical examination, most structures in the foot and ankle are immediately subcutaneous and readily palpable. Beyond medications, useful nonoperative treatments include bracing, shoewear modification, orthoses, and physical therapy. Most surgical procedures in foot and ankle surgery fall into one of the following categories: arthrodesis, arthroplasty, corrective osteotomy, ostectomy, tendon débridement and transfer, and synovectomy. Patient compliance and soft tissue integrity are important factors when considering surgery. Advances in medical management now make joint-sparing procedures possible in many patients with inflammatory arthritis who previously would have required arthrodesis.

Foot and ankle pain are independent risk factors for locomotor instability, impaired balance, and increased risk for falling, as well as compromised functional activities of daily living.1-5 Foot and ankle pain appear to affect approximately one in five middle-aged to older individuals. Interference with daily activities occurs in one-half to one-third of affected individuals but is rarely disabling outside the context of rheumatoid arthritis. Foot and ankle pain is significantly more common in women, a finding that has been attributed to gender-specific footwear.

CAUSES OF FOOT AND ANKLE PAIN The differential diagnosis of foot and ankle pain is vast and includes conditions of tendons, ligaments, muscle, bone, joints, periarticular structures, nerves, and vessels, as well as referred pain (Table 49-1). The most common cause of pain of the foot and ankle is osteoarthritis (OA). Although OA is the most prevalent joint disease, its pathophysiology remains poorly understood. Research regarding foot and ankle OA in particular is limited by absence of a standard case definition. Ankle and foot OA results from damage and loss of the articular cartilage, which can cause inflammation, stiffness, pain, swelling, deformity, and limitation of function, such as walking or standing. Osteophyte formation can lead to impingement and further pain. In the foot, OA most commonly occurs in the big toe, the midfoot, and ankle. In the early stages, pain may occur only at the beginning and at 700

the end of an activity, but as the condition progresses it can become constant, even at rest. The ankle is a complex joint that is subjected to enormous forces during daily activities and in sports, especially running. It is also the joint most commonly injured in the human body. This combination of factors predisposes the ankle joint to degenerative changes, although the risk is lower than other weight-bearing joints, such as the hip and knee. The ankle also rarely develops arthritic changes without an identifiable cause. The most common cause of ankle OA is trauma and can develop following a fracture or repeated sprains. Other causes of OA are abnormal foot mechanics (flat and high-arched feet) and, rarely, systemic diseases such as hemochromatosos. Foot and ankle pain is the presenting complaint in approximately 15% to 20% of newly diagnosed rheumatoid arthritis (RA) patients.6 Further, of those patients already diagnosed with RA, the prevalence of foot and ankle involvement has been estimated to be greater than 90%.7 Evaluation of the rheumatoid foot and ankle begins with a thorough history and physical examination. The location, timing, and duration of symptoms can help establish a specific diagnosis and help guide the subsequent course of treatment. Radiographs and advanced imaging modalities provide useful adjuncts in the evaluation of specific foot and ankle pathologies. The treatment of the rheumatoid foot and ankle is aimed at both alleviating pain and preserving function (i.e., maintaining the ambulatory status of the patient). Initial nonoperative treatment includes medical management, physical therapy, shoewear modification, orthotics, and bracing. These measures provide substantial relief for many. For recalcitrant symptoms, surgical intervention may be necessary. Most surgical procedures fall into one of the following general categories: arthrodesis (joint fusion), arthroplasty (joint replacement), corrective osteotomy, ostectomy, and synovectomy (joint or tendon).

FUNCTIONAL ANATOMY AND BIOMECHANICS The ankle, or tibiotalar joint, is composed of the articulation between the foot (talus) and the lower leg (distal tibia and fibula). Its primary motion is plantar flexion and dorsiflexion in the sagittal plane. In addition, the articulation between the distal tibia and fibula allows a lesser amount of internal and external rotation to occur in the axial, or transverse, plane. The foot may be loosely divided into three anatomic regions: forefoot, midfoot, and hindfoot. The forefoot

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Table 49-1  Differential Diagnosis of Foot and Ankle Pain Tendon, Ligament, and Muscle Gastroc-soleus strain Plantaris rupture Anterior talofibular ligament tear Calcaneofibular ligament tear Deltoid ligament tear Anterolateral impingement due to complete tear of anterior talofibular ligament and anterior inferior tibiofibular ligament Syndesmotic impingement due to tear of syndesmosis Sinus tarsi syndrome (lateral hindfoot pain and instability due to injury of contents of the sinus and tarsal tunnel) Achilles tendinitis Achilles rupture Plantar fasciitis Posterior tibial tendon dysfunction Flexor hallucis longus dysfunction Tibialis anterior tendon tear Peroneus brevis tendon tear Bone Fracture of talus Calcaneal fracture Navicular fractures Lisfranc fracture-dislocation (fracture of the first metatarsal base with dislocation of medial cuneiform) Metatarsal stress fracture Freiberg’s infraction (sclerosis and flattening of the second metatarsal head due to trauma or microtrauma) Avascular necrosis of the talus Fracture of the phalanges Fracture of the sesamoids Sesamoiditis Metatarsalgia Joint Osteoarthritis Gout Rheumatoid arthritis Other inflammatory arthritides Charcot’s joint Osteochondral lesion of the talus Periarticular Structures Shin splint (periosteal avulsion and periostitis at the insertion of the medial soleus due to repetitive overuse, such as in running and hiking) Hallux rigidus Hallux valgus Ingrown toenail Toe deformities Turf toe (sprain of the first metatarsophalangeal joint due to hyperextension forces) Plantar fasciitis Plantar fibromatosis Nerves Anterior tarsal tunnel syndrome (involvement of deep peroneal nerve under the superficial fascia of the ankle) Morton’s neuroma Vessels Atherosclerosis Compartment syndrome Referred Pain Complex regional pain syndrome Courtesy Dr. George Raj, Non Surgical Spine and Joint Clinic PS, Bellingham, Wash.

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consists of the toes and metatarsal bones, along with the metatarsophalangeal (MTP) and interphalangeal (IP) joints. The tarsometatarsal (TMT) joints connect the forefoot to the midfoot, which comprises the three cuneiform bones, the navicular, and the cuboid. Finally, the hindfoot, located below the ankle, consists of the talus and calcaneus. The joints of the hindfoot include the talocalcaneal (subtalar), talonavicular, and calcaneocuboid articulations. Forefoot and midfoot motion is primarily plantarflexion and dorsiflexion in the sagittal plane, with some secon­­ dary pronation and supination in the coronal plane and abduction/adduction in the axial plane. Motion in the hindfoot is primarily composed of inversion/eversion in the coronal plane, with secondary internal/external rotation in the axial plane and plantarflexion/dorsiflexion in the sagittal plane. Knowledge of these anatomic divisions is important because radiographs often demonstrate polyarticular disease in patients with RA. An intimate understanding of the local anatomy greatly aids in the establishment of an accurate diagnosis and formulation of an appropriate treatment plan.

DIAGNOSTIC EVALUATION Physical Examination A thorough physical examination of the foot and ankle begins with gait analysis, even if simply observing the patient enter the examination room. Normal human gait is divided into two phases. The stance phase is the weightbearing portion of the gait cycle and comprises roughly 60% of normal walking. It begins with heel-strike and then extends through foot-flat to toe-off. Meanwhile, the swing phase of gait extends from toe-off to heel-strike and comprises the remaining 40% of the gait cycle. Patients with an “antalgic” gait pattern will have a shortened stance phase on the side of the affected limb, as they attempt to more quickly transfer their weight to the nonpainful limb. In addition to an antalgic gait, foot and ankle pain often results in the avoidance of ground contact with the painful part of the foot. A further problem noted in stance phase is dynamic collapse of the medial longitudinal arch, most apparent at foot-flat and toe-off. During the swing phase of gait, a “steppage” gait may be noted. This is characterized by excessive hip and knee flexion to allow a patient’s foot to clear the ground in the setting of a footdrop. In patients with RA, it may be caused by attritional rupture of the anterior tibialis tendon, which is the main dorsiflexor of the ankle. Following gait analysis, the foot and ankle are inspected, both with the patient sitting and standing. The location of swelling is usually well correlated with the joint(s) involved (e.g., ankle vs. talocalcaneal joint). Deformity should also be noted. Commonly seen deformities in patients with RA include hallux valgus, or bunion (Figure 49-1); hammertoes; and flatfoot deformity (characterized by hindfoot valgus/ forefoot abduction). Callosities develop over regions of increased pressure and are associated with deformity and fat pad atrophy. Rheumatoid nodules can appear anywhere on the foot but are often found in areas of repetitive trauma (i.e., at the site of irritation from a tight shoe counter). Similarly, ulcerations appear in areas of repeated injury such

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| DIFFERENTIAL DIAGNOSIS OF REGIONAL AND DIFFUSE MUSCULOSKELETAL PAIN including arthritis, synovitis, impingement, and osteochondral defect (OCD). A more detailed description of these conditions and their correlation with anatomic location is provided later in the chapter and in Table 49-2. Following inspection and palpation, range-of-motion analysis is performed. Passive range of motion of the ankle is normally between 10 and 20 degrees of dorsiflexion and 40 and 50 degrees of plantarflexion. Normal hindfoot inversion and eversion are approximately 20 and 10 degrees, respectively. The first MTP joint should have approximately 45 degrees of “plantarflexion” (flexion) and 70 to 90 degrees of “dorsiflexion” (extension). Deviations from these norms should be noted as part of the standard workup. Imaging

Figure 49-1  Clinical photograph of hallux valgus deformity.

as those found in tight-fitting shoes. Finally, wear patterns on shoes should also be noted. As Hoppenfeld observed8: “A deformed foot can deform any good shoe; in fact, in many cases the shoe is a literal showcase for certain disorders.” Following inspection, the foot and ankle are thoroughly palpated. The dorsum of the foot and ankle has little overlying musculature. As such, many of the bones and tendons are immediately subcutaneous and a great deal of information can be gained from palpating these structures. It is helpful to palpate the foot and ankle by anatomic location (i.e., forefoot, midfoot, hindfoot, anterior and posterior ankle). In the forefoot, the first metatarsal head and MTP joint can be palpated at the base of the hallux (great toe), at the medial aspect of the “ball” of the foot. Proceeding laterally, the lesser metatarsal heads and MTP joints can then be sequentially palpated. In patients with RA, such palpation often reveals tenderness, synovitis, and bursal swelling. In the second and third MTP joints, sagittal plane instability often results from attenuation of the plantar joint capsule. This can be appreciated by gently translating the second and third toes dorsally. In the hindfoot the calcaneus is readily palpable, and its various parts can be palpated individually. A stress fracture should always be considered in patients with RA. Further, tenderness over the posterior aspect of the bone may indicate Achilles tendinitis while pain over the medial tubercle (palpable on the medial plantar surface) may indicate plantar fasciitis. Tenderness over the “sinus tarsi” of the hindfoot (located laterally, just anterior and distal to the tip of the fibula) indicates talocalcaneal joint pathology. Finally, posteromedial tenderness may be secondary to tenosynovitis, posterior tibial tendinosis, and tarsal tunnel syndrome (usually secondary to adjacent tenosynovitis). In the ankle joint proper, tenderness over the anterior joint line usually correlates with ankle joint pathology

Despite the abundant availability of advanced imaging modalities such as magnetic resonance imaging (MRI) and computed tomography (CT), radiographs remain the imaging mainstay in the evaluation of foot and ankle pain. Weight-bearing images should be obtained whenever possible because joint space narrowing and deformity may not be apparent in non-weight-bearing images. Standard images consist of weight-bearing anteroposterior, lateral, and oblique views of the foot and anteroposterior, mortise, and lateral views of the ankle. Further radiographic findings of RA include periarticular erosions and osteopenia. MRI provides reliable imaging of soft tissue structures and can be a useful tool in the evaluation of the rheumatoid foot and ankle. Early in the course of RA, MRI allows one to look for signs of the disease such as synovitis, tenosynovitis, periarticular edema, and bursitis.9 Later, MRI is useful in assessing disease progression and extent of joint involvement, as well as in distinguishing between tendon rupture and tendinitis/tendinopathy (Figure 49-2). CT scan10 and nuclear scintigraphy11 are also used in the evaluation of foot and ankle pain. For example, either method can be quite helpful in postoperative evaluation in fusion surgery. Ultrasound is gaining utility as a method to evaluate tendon integrity as well. However, the results are largely technique dependent with minimization of artifacts being of utmost concern. In addition, ultrasound is difficult

Table 49-2  Anatomic Characteristics of Pain in the Foot and Ankle Location

Dysfunction

Forefoot

Hallux valgus, hammertoes Metatarsophalangeal arthritis/synovitis/ instability Plantar fasciitis, arthritis, synovitis (rare) Hindfoot valgus deformity, arthritis Stress fracture Arthritis, synovitis, impingement, osteochondral defect Achilles tendinitis/tendinosis, bursitis Stress fracture Peroneal tendinitis, tear, instability Posterior tibial tendinitis/dysfunction Flexor hallucis longus/flexor digitorum longus tendinitis Tarsal tunnel syndrome

Midfoot Hindfoot Anterior ankle Posterior ankle Posterolateral ankle Posteromedial ankle

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symptoms of “impingement.” Specifically, patients will note pain with ankle dorsiflexion, such as when they walk up stairs or an incline. On physical examination, there may be anterior tenderness and/or pain with terminal passive dorsiflexion. Anterior osteophyte formation may produce even more pronounced impingement symptoms, although such osteophytes are more commonly seen with OA and longstanding ankle instability. Central Joint Pain Two other causes of central ankle pain, stress fracture and osteochondral defect, should be considered. Stress fractures are commonly seen in patients with periarticular and generalized osteopenia. An osteochondral defect (OCD) is a focal defect in the articular cartilage and subchondral bone. These lesions are encountered more commonly in patients without inflammatory arthritis. In the setting of RA, their presence may represent an early manifestation of RA or a separate pathologic process. Figure 49-2  Axial magnetic resonance image of ankle demonstrating posterior tibial tendon degeneration and synovitis (arrow).

to use in preoperative planning because important landmarks are often not included.12 Anesthetic arthrograms are an extremely useful adjunct in diagnosing foot and ankle pain in patients with RA. Given the complex and crowded geometry of the foot and the propensity of RA to affect multiple joints and tendons, it is often difficult to determine if the pain is articular and, if so, which joint is symptomatic. With an anesthetic arthrogram, a mixture of steroid, anesthetic, and contrast material is injected under fluoroscopic guidance into a suspect joint. This allows the clinician to more precisely determine whether or not the injected joint is a significant pain generator. Again, this is especially helpful in the foot and ankle, where multiple joints are in close proximity and may be simultaneously diseased.13

COMMON CAUSES OF ANKLE PAIN From a diagnostic standpoint, it is useful for the clinician to conceptualize ankle pain on the basis of anatomic location. This approach applies to patients with virtually any form of ankle or foot pain, and RA will be used to illustrate how to formulate a differential diagnosis and treatment plan as advances in medical management temper disease and “allow” patients to develop other, noninflammatory disorders. Anterior Ankle Pain Anterior ankle pain, in patients both with and without RA, is most often the result of intra-articular pathology. Anteriorly, the ankle joint is not shielded by the malleoli and is immediately subcutaneous. Further, the anterior extensor tendons are typically not prone to the development of tendinitis and tendinosis. In early RA, synovitis can cause anterior joint line pain, swelling, and tenderness. Clinically, this results in

Posterior Joint Pain Posterior ankle pain usually originates from the Achilles tendon, its insertion onto the calcaneal tuberosity, and two associated bursae in this region. The Achilles tendon is the largest tendon in the body but lacks a true synovial lining. As such, isolated Achilles tendinitis is uncommon. In most instances, Achilles pain results from degenerative tendinosis, with or without an overlying tendinitis. Although associated spur formation is common, it is important to remember that Achilles spurs are a manifestation of a disease process. As such, surgeries directed at spur excision also frequently entail tendon débridement and reconstruction, as well as tendon transfer. The Achilles tendon is protected by two distinct bursae. A more superficial bursa is immediately subcutaneous and becomes inflamed primarily with irritation from ill-fitting shoes with a tight counter (“pump bump”). The “retrocalcaneal” bursa is a larger structure that lies deep to the Achilles. Inflammation of this structure often accompanies Achilles tendinitis/tendinosis. It may also be irritated by an enlarged posterior superior calcaneal tuberosity, sometimes referred to as “Haglund’s” deformity. Medial and Lateral Ankle Pain As with anterior, central, and posterior ankle pain, the origin of medial or lateral ankle pain is also anatomically based. On the medial side, pain directly over the medial malleolus should alert the clinician to the possibility of a stress fracture. Pain anterior to the medial malleolus is usually articular in nature. Pain posterior to the medial malleolus is often caused by inflammation and/or degeneration of the posteromedial flexor tendons. These include the posterior tibial tendon and the flexor hallucis longus and flexor digitorum longus tendons. The posterior tibial tendon is the largest and strongest of the posteromedial flexor tendons. Its primary function is to invert the hindfoot and thus support the medial longitudinal arch of the foot. Long-standing synovitis and dysfunction of this tendon may ultimately lead

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to collapse of the arch and the development of an acquired flatfoot deformity. On the lateral side of the ankle, pain directly over the lateral malleolus may be caused by a stress fracture. This is especially relevant in the setting of hindfoot valgus and a flatfoot, which will increase fibular loading. Similar to the medial side, pain anterior to the lateral malleolus is usually articular in nature. Finally, pain posterior to this lateral malleolus is usually indicative of peroneal tendon pathology. In patients with RA, the peroneal tendons may be affected by tenosynovitis, longitudinal “split” tears, and chronic tendon instability. With the latter, the tendons sublux over the posterolateral edge of the fibula, causing pain as well as attritional tearing.

COMMON CAUSES OF FOOT PAIN Typically, the forefoot is the most common site of involvement early in the course of diseases such as RA but also can occur in gout and OA.14 The pathogenesis of forefoot pain and deformity in the rheumatoid forefoot is inflammation and progressive synovitis that eventually leads to a capsular distention at the MTP joints and destruction of the plantar plates.15 Eventually it progresses to loss of collateral ligament stability and, finally, destruction of the articular cartilage and bone (Figure 49-3A and B). Clinically, this manifests as dorsal subluxation or dislocation of the lesser toe MTP joints with a hallux valgus deformity and presents as metatarsalgia. In the lesser MTP joints, loss of stability leads to progressive deformity secondary to the various forces on the forefoot. Muscle imbalance and dorsiflexion forces at toe-off lead to progressive subluxation and even dorsal dislocation of the MTP joints. With this, the metatarsal head is prone to forming keratotic skin lesions that can ulcerate. Muscle imbalance can also lead to the development of painful hammertoe and claw toe deformities that can exert a plantardirected force that further exacerbates symptomatic

metatarsalgia. Lesser MTP joint subluxation has been reported to be as high as 70% with a concomitant incidence of pressure sores in approximately 30% of those patients. In the hallux, RA can cause both articular erosions and loss of capsular integrity that often results in the development of a hallux valgus deformity, or bunion (see Figure 49-1). The progression of this deformity may be further accelerated by loss of support from the adjacent lesser MTP joints. The incidence of hallux valgus deformity in patients with RA has been estimated to be up to 70%. The midfoot is a less common site of involvement in the rheumatoid foot. Radiographically there can be erosions; however, the prevalence of symptoms is often quite low. The most frequent site of involvement is the first tarsometatarsal (TMT) joint. The symptoms seen here, though, may not be from rheumatoid synovitis per se, as seen in the forefoot. Rather, pain may also be due to hindfoot and hallux valgus deformities that lead to increased stresses across the TMT joint. Eventually this increased stress can lead to dorsiflexion of the first TMT joint and resultant lesser toe TMT joint abduction and dorsiflexion, thereby leading to pain in the dorsomedial midfoot. In addition, progressive biomechanical changes can lead to OA of the midfoot TMT joints yielding discomfort and pain with weight bearing. The three joints of the hindfoot (talonavicular, talocalcaneal, and calcaneocuboid) are commonly affected by RA. Although these joints are affected at different rates, the overall prevalence of hindfoot involvement in RA is between 21% and 29%. The talonavicular joint is most often affected, followed by the talocalcaneal and then calcaneocuboid joints. Further, the hindfoot becomes more symptomatic and involved the longer the duration of RA. The incidence of hindfoot deformity in those with RA less than 5 years has been estimated to be 8% and increases to 25% in those with RA longer than 5 years.16 Clinically, patients with talocalcaneal or calcaneocuboid involvement will complain of lateral hindfoot pain. Meanwhile, arthritis and synovitis of the talonavicular joint are manifested by dorsal or medial pain. The deformity most often seen in patients with hindfoot RA is an acquired flatfoot deformity, characterized by heel valgus and forefoot abduction. This usually results from articular deformity and instability but may also be caused by tenosynovitis and tendinosis of the posterior tibial tendon, the main supporter of the longitudinal arch of the foot.

NONOPERATIVE TREATMENT

A

B

Figure 49-3  Preoperative (A) and postoperative (B) anteroposterior radiograph of hallux valgus deformity with lesser metatarsophalangeal joint erosions treated by fusion and lesser metatarsal head resections.

Medical management remains the cornerstone of treatment for many forms of foot and ankle arthritis. In fact, many of the current recommendations for operative treatment may soon be modified given the alteration of disease progres­­ sion with current medical regimens for RA.17 The most common medical management still consists of nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, and diseasemodifying antirheumatic drugs (DMARDs) and, more recently, biologic therapies. Although each of these drug classes has done much to alleviate patient suffering, they are not without impact on the surgical management of rheumatic disease. There is concern about lower fusion rates in

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the setting of NSAIDs and increased infection rates in the setting of steroids or DMARDs.18,19 Moreover, those who have been on chronic steroids are at risk for postoperative adrenal insufficiency and may require perioperative corticosteroids.20 Close communication and collaboration between the rheumatologist and surgeon are essential to good outcomes. Footwear modification can often have profound benefits for patients. Shoes should be examined in the clinic to be sure that they can accommodate a patient’s deformity. Patients often feel best in shoes with a deep, wide toe-box, a firm heel counter, and soft heel. Well-constructed walking or jogging shoes usually provide sufficient room for mild to moderate deformities. It is helpful to provide patients with a list of suitable manufacturers when making such recommendations. Often it is necessary to prescribe a custom orthotic insert for those with more moderate deformities. Typically the insole of the shoe must be removed in order to make room for the orthotic. Again, most walking or jogging shoes will suffice. In general, custom orthotics can be divided into rigid, semirigid, and softer accommodative devices. Rigid and semirigid orthotics are usually used to correct supple deformities and should be used with caution in patients with RA.21 More commonly, patients benefit from accommodative orthotics (i.e., orthotics made of softer material that can be molded to “accommodate” a deformity).22 These can then be further modified by incorporating a “relief” under a deformity, thereby further unloading it. When sending patients for orthotics, it is best to provide the orthotist with a prescription that includes the patient’s precise diagnosis (e.g., RA or OA with metatarsalgia), as well as the type of orthotic and any modifications desired (e.g., a “custom accommodative orthotic with a relief under the lesser metatarsal heads”).23 Finally, injections of a mixture of anesthetic and corticosteroid to areas of inflammation or bursitis are useful in the treatment of both inflammatory and noninflammatory conditions affecting the foot and ankle. In the foot and ankle, however, such injections must be judiciously employed. Most importantly, injections into and around tendons should be avoided. Due to the forces associated with weight bearing and ambulation, these tendons are under substantial load. The injection of a corticosteroid directly into or even near a tendon can adversely affect the biomechanical properties of the tendon, ultimately leading to rupture.24 A further precaution is to avoid corticosteroid injections into the lesser MTP when there is evidence of joint instability (manifested by valgus or varus deviation on radiographs or sagittal plane instability on physical examination). Such injections can lead to further attenuation of the joint capsule and can result in frank joint dislocation.

OPERATIVE TREATMENT If symptoms persist despite nonoperative management, surgical intervention should be considered. Two important factors must be taken into account when deciding whether or not to proceed with surgery. First, the soft tissues and vascular status must be carefully assessed. Both may be

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compromised and could negatively affect outcome. Second, the ability of patients to comply with the postoperative regimen (e.g., being able to use crutches and not bear weight if necessary) must be considered. Even limited noncompliance can lead to a poor outcome, especially in fusion surgery. As noted earlier, most surgical procedures fall into one of the following categories: arthrodesis (joint fusion), arthroplasty (joint replacement), corrective osteotomy, ostectomy, and synovectomy (joint or tendon). Arthrodesis Arthrodesis remains a surgical cornerstone for the rheumatoid foot and ankle. With an arthrodesis procedure, the two sides of the joint are roughened with a burr or small chisel. Next, the two bones to be fused are compressed and fixed together, usually with one or more screws (see Figure 49-3B). In the weeks and months following surgery, the body is “tricked” into thinking that there is a fracture present at the fusion site and heals this with bone. As such, the two bones become one and are considered fused. Fusion surgery offers reliable pain relief in the majority of patients. One obvious concern with fusion surgery is the loss of motion. For the patient, however, this usually results in only mild functional compromise. Further, to the untrained eye, there is remarkably little change in gait. Commonly performed fusions in patients with RA include ankle arthrodesis, isolated hindfoot fusions, triple arthrodesis, midfoot arthrodesis, and arthrodesis of the first MTP joint. A triple arthrodesis involves fusion of the talocalcaneal, talonavicular, and calcaneocuboid joints. Together, these joints allow coronal plane motion and thereby are most important when walking on uneven ground. Fusion remains the gold standard for patients with RA of the ankle. If there is minimal deformity and no loss of bone stock, ankle fusion surgery may be performed arthroscopically or through a “miniopen” approach. These techniques involve less soft tissue dissection and stripping, thereby minimizing loss of bony perfusion. Nevertheless, the time period for which the patient must avoid bearing weight (from 6 to 12 weeks) remains the same. The success rate of ankle fusion surgery in patients with RA is generally 85% or greater. Although the osteopenia associated with the disease can compromise fixation, it can also theoretically enhance fusion because there is less sclerotic subchondral bone. In the hindfoot, fusion surgery may be performed on one or more of the three joints of this part of the foot (i.e., the talocalcaneal, talonavicular, and calcaneocuboid joints). If only one of these joints is diseased, an isolated fusion of this joint is acceptable.25 This reduces surgical morbidity and the extent of the procedure. Nevertheless, with fusion of just one of the joints of the hindfoot, motion in the other joints is reduced.26 If more than one joint is diseased, a “double” or “triple” arthrodesis is necessary. In the midfoot, fusion surgery results in negligible loss of motion because the joints of the midfoot normally have less than 10 degrees of motion. With both OA and inflammatory arthritis, symptomatology is most often limited to the medial (first through third) TMT joints. The lateral (fourth

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and fifth) TMT joints are infrequently symptomatic, even in the setting of advanced radiographic changes. Finally, in the forefoot, fusion surgery is indicated only for the first metatarsophalangeal (MTP) joint. This procedure is used for both arthrosis and advanced hallux valgus (bunion) deformities. When the first MTP joint is fused, it is positioned in a slightly dorsiflexed position to assist ambulation. With MTP fusion in 47 feet, Coughlin27 reported 96% good to excellent results and 100% fusion at an average 6.2-year follow-up. In summary, fusion surgery generally provides reliable pain relief and a stable, plantigrade foot. Nevertheless, the loss of motion of the fused joint can lead to increased motion and altered biomechanics at adjacent joints. This ultimately may lead to arthritic changes in these joints.28 Further, fusion surgery may lead to subtle albeit real changes in gait.29 Finally, the minimal ramifications of fusing just one joint may become much greater in the setting of a subsequent fusion in either the ipsilateral or contra­ lateral limb. Arthroplasty Concerns regarding fusion have driven many to work toward improving joint replacement surgery (arthroplasty) in the foot and ankle. Most notably, total ankle replacement surgery continues to evolve and remains a controversial topic among orthopedic surgeons. Although there are many who perform ankle replacement surgery, there are many that do not or that do so only on a limited basis. To this end, the U.S. Food and Drug Administration currently approves only four ankle prostheses for implantation. Long-term survival data as published for hip and knee arthroplasty are not yet available. The main advantage of ankle arthroplasty is preserva­ tion of motion. Its main two disadvantages are technical complexity and the difficulty with subsequent fusion if the procedure fails. In general, ankle replacement surgery is indicated for middle-aged and elderly individuals with low functional demands and minimal deformity. Two other indications especially pertinent in patients with ankle arthritis include (1) bilateral disease and (2) concomitant ipsilateral hindfoot disease or preexisting arthrodesis. The paradox of ankle replacement surgery remains as follows: Ankle replacement is contraindicated in young patients for whom preservation of motion is most important. On the other hand, arthroplasty is more commonly performed in older patients for whom preservation of motion is less important and who would do well with a fusion. Nevertheless, total ankle replacement surgery continues to evolve and reported success rates with modern designs continue to improve30,31(Figure 49-4). In the foot, arthroplasty is performed by some surgeons for the first MTP joint. The relevant literature is still somewhat conflicted, though. Although there were some encouraging early results with arthroplasty, other studies have shown high rates of implant failure and loosening secondary to synovitis from polymeric silicone (Silastic) particle wear.32-34 Further, advanced deformity, often present in patients with RA, is considered to be a relative contraindication to first MTP joint arthroplasty. Nevertheless, new implant designs may hold increased promise. In general,

Figure 49-4  Anteroposterior radiograph of total ankle arthroplasty.

these implants are lower profile and resect less bone, which also makes it easier to perform a subsequent fusion, if necessary. Osteotomy Corrective osteotomies are used primarily for two reasons in the treatment of RA: to correct deformity and/or to redistribute forces on a joint or the terminal aspect of a bone. Examples of osteotomies to correct deformity include calcaneal osteotomies for pes planovalgus and metatarsal osteotomies for hallux valgus. Previously, patients with RA and concomitant pes planovalgus or hallux valgus underwent fusion surgery. However, with advances in medical management of the disease, it is not unreasonable to attempt joint preservation surgery in patients who have mild to moderate disease, healthy soft tissues, and flexible deformities. Examples of osteotomies to redistribute forces include tibial osteotomies in the setting of eccentric ankle arthritis and metatarsal osteotomies in the setting of metatarsalgia. Patients requiring surgery for ankle RA previously underwent fusion surgery only, while patients requiring surgery for metatarsalgia underwent metatarsal head resection. Again, however, advances in medical management of the disease allow joint preservation osteotomies to be considered. This is especially the case for metatarsalgia, which is common in patients with RA yet increasingly does not entail frank dislocation or articular erosion. Ostectomy Although more commonly seen in patients with OA, some patients with RA may present with symptoms of mechanical ankle impingement arising from anterior bone spurs. In cases without global joint destruction, surgical resection of

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the spurs, or cheilectomy, is a reasonable treatment. Although no studies have examined cheilectomy in RA specifically, patients with less severe erosive changes tend to be more satisfied with the results of cheilectomy.35 Synovectomy For those patients with inflammatory arthritis resistant to medical management and nonoperative treatment, synovectomy can provide a period of pain relief for many patients.36,37 It is thought that early synovectomy of either the affected joint or tendon may help halt the progress of joint destruction. Joint synovectomy is indicated in those who have failed medical management yet still have a relatively preserved articular surface. Otherwise, synovectomy of the affected tendons allows some preservation of function.

CONCLUSION Foot and ankle pain is a prevalent and potentially debili­ tating problem. Unfortunately, many forms of arthritis, including RA, set up a vicious cycle of foot and ankle pain and biomechanics. Synovitis and articular erosions lead to both pain and deformity. A proper history and physical examination are essential for establishing an anatomic diagnosis. Although advanced imaging modalities such as MRI and CT can be useful as adjuncts, radiography remains the gold standard. Nonoperative modalities such as medications, bracing, physical therapy, orthotics, and footwear modification are able to relieve pain and maintain function for many. For recalcitrant symptoms, substantial relief may be afforded by surgical intervention in the form of arthrodesis, arthroplasty, osteotomy, ostectomy, and synovectomy. References 1. Bowling A, Grundy E: Activities of daily living: changes in functional ability in three samples of elderly and very elderly people, Age Ageing 26(2):107–114, 1997. 2. Keysor JJ, Dunn JE, Link CL, et al: Are foot disorders associated with functional limitation and disability among community-dwelling older adults? J Aging Health 17(6):734–752, 2005. 3. Menz HB, Morris ME, Lord SR: Foot and ankle characteristics associated with impaired balance and functional ability in older people, J Gerontol A Biol Sci Med Sci 60(12):1546–1552, 2005. 4. Menz HB, Morris ME, Lord SR: Foot and ankle risk factors for falls in older people: a prospective study, J Gerontol A Biol Sci Med Sci 61(8):866–870, 2006. 5. Peat G, Thomas E, Wilkie R, et al: Multiple joint pain and lower extremity disability in middle and old age, Disabil Rehabil 28(24):1543– 1549, 2006. 6. Vanio E: Rheumatoid foot. Clinical study with pathological and roentgenological comments, Ann Chir Gynaecol. Fenniae 45(S):1–107, 1956. 7. Flemming A, Crown JM, Corbett M: Early rheumatoid disease. I. Onset, Ann Rheum Dis 35:357–360, 1976. 8. Hoppenfeld S: Physical examination of the spine and extremities, Norwalk, Conn, 1976, Appleton and Lange. 9. Boutry N, Flipo RM, Cotton A: MR imaging appearance of rheumatoid arthritis in the foot, Semin Musculoskelet Radiol 9:199–209, 2005.

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10. Seltzer SE, Weismann BN, Braunstein EM, et al: Computed tomography of the hindfoot with rheumatoid arthritis, Arthritis Rheum 28:1234–1242, 1985. 11. Groshar D, Gorenberg M, Ben-Haim S, et al: Lower extremity scintigraphy: the foot and ankle, Semin Nucl Med 28:62–77, 1998. 12. Riente L, Delle Sedie A, Iagnocco A, et al: Ultrasound imaging for the rheumatologist. V. Ultrasonography of the ankle and foot, Clin Exp Rheumatol 24:493–498, 2006. 13. Khoury NK, el-Khoury GY, Saltzman CL, et al: Intrarticular foot and ankle injections to identify source of pain before arthrodesis, AJR Am J Roentgenol 167:669–673, 1996. 14. Vidigal E, Jacoby RK, Dixon AS, et al: The foot in chronic rheumatoid arthritis, Ann Rheum Dis 34:292–297, 1975. 15. Jaakkola JI, Mann RA: A review of rheumatoid arthritis affecting the foot and ankle, Foot Ankle Int 25:866–874, 2004. 16. Spiegel TM, Spiegel JS: Rheumatoid arthritis in the foot and ankle— diagnosis, pathology and treatment, Foot Ankle 2:318–324, 1982 17. Matteson EL: Current treatment strategies for rheumatoid arthritis, Mayo Clin Proc 75:69–74, 2000. 18. Conn DL, Lim SS: New role for an old friend: prednisone is a diseasemodifying agent in early rheumatoid arthritis, Curr Opin Rheumatol 15:192–196, 2003. 19. Mohan AK, Cote TR, Siegel JN, et al: Infectious complications of biologic treatment of rheumatoid arthritis, Curr Opin Rheumatol 15:179–184, 2003. 20. Coursin DB, Wood KE: Corticosteroid supplementation for adrenal insufficiency, JAMA 287:236–240, 2002. 21. Clark H, Rome K, Plant M, et al: A critical review of foot orthoses in the rheumatoid arthritic foot, Rheumatology 45:139–145, 2006. 22. Woodburn J, Barker S, Helliwell PS: A randomised controlled trial of foot orthoses in rheumatoid arthritis, J Rheumatol 29:1377–1383, 2002. 23. Magalhaes E, Davitt M, Filho DJ, et al: The effect of foot orthoses in rheumatoid arthritis, Rheumatology 45:449–453, 2006. 24. Hugate R, Pennypacker J, Saunders M, et al: The effects of intratendinous and retrocalcaneal intrabursal injections of corticosteroid on the biomechanical properties of rabbit Achilles tendons, J Bone Joint Surg Am 86:794–801, 2004. 25. Chiodo CP, Martin T, Wilson MG: A technique for isolated arthro­ desis for inflammatory arthritis of the talonavicular joint, Foot Ankle Int 21:307–310, 2000. 26. Astion DJ, Deland JT, Otis JC, et al: Motion of the hindfoot after simulated arthrodesis, J Bone Joint Surg Am 79:241–246, 1997. 27. Coughlin M: Rheumatoid forefoot reconstruction. A long term follow-up study, J Bone Joint Surg Am 82:322–341, 2000. 28. Coester LM, Saltzman CL, Leupold J, et al: Long-term results following ankle arthrodesis for post-traumatic arthritis, J Bone Joint Surg Am 83:219–228, 2001. 29. Thomas R, Daniels TR, Parker K: Gait analysis and functional outcomes following ankle arthrodesis for isolated ankle arthritis, J Bone Joint Surg Am 88:526–535, 2006. 30. Easly ME, Vertullo CJ, Wrban WC, et al: Total ankle arthroplasty, J Am Acad Orthop Surg 10:157–167, 2002. 31. Saltzman CL, Mann RA, Ahrens JE, et al: Prospective controlled trial of STAR total ankle replacement versus ankle fusion: initial results, Foot Ankle Int 30:579–596, 2009. 32. Deheer PA: The case against first metatarsal phalangeal joint implant arthroplasty, Clin Podiatr Med Surg 23:709–723, 2006. 33. Bommireddy R, Singh SK, Sharma P, et al: Long term followup of Silastic joint replacement of the first metatarsophalangeal joint, Foot 12:151–155, 2003. 34. Shankar NS: Silastic single-stem implants in the treatment of hallux rigidus, Foot Ankle Int 16:487–491, 1995. 35. Hattrup SJ, Johnson KA: Subjective results of hallux rigidus treatment with cheilectomy, Clin Orthop Relat Res 226:182–191, 1988. 36. Aho H, Halonen P: Synovectomy of the MTP joints in rheumatoid arthritis, Acta Orthop Scand Suppl 243:1, 1991. 37. Tokunaga D, Hojo T, Takatori R, et al: Posterior tibial tendon tenosynovectomy for rheumatoid arthritis: a report of three cases, Foot Ankle Int 27:465–468, 2006. The references for this chapter can also be found on www.expertconsult.com.