Rheumatologic Disorders
Matthew J. Anderson
Stefanos Haddad
Hollie Garber
INTRODUCTION
Rheumatologic conditions have a varied effect on the foot. Many will cause serious morbidity and disability associated with foot pain and instability. The main goal for the foot, as with all rheumatologic conditions, is early detection and pharmacologic treatment of the underlying disease to prevent long-term sequelae. Once pathology is manifest within the joint or soft tissues of the foot, treatment modalities progress and ultimately surgery to restore pain-free ambulation.
RHEUMATOID ARTHRITIS
Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by synovitis, periarticular bone loss, and osteoporosis. The disease affects between 0.3% and 2.1% of the general population1 and is 2 to 4 times more common in women than in men.2 The disease prevalence peaks in the third to fifth decades and follows 1 of 3 pathways: (1) a relentless, destructive, and aggressive course; (2) a monocyclic course notable for a single episode of synovitis without permanent cartilage damage; and (3) a polycyclic course with multiple episodes of attack followed by remissions, which is the most common.
The disease can affect all joints of the body but preferentially affects the small joints of the hand and foot. Foot and ankle symptoms account for 50% of the presenting complaints at diagnosis, and it is estimated that 85% to 90% of patients with RA will experience foot or ankle problems3 with increasing incidence over the duration of the disease process.4
Initial complaints with rheumatoid arthritis involve vague forefoot pain and metatarsalgia resulting from synovitis and intra-articular effusion, a variable waxing and waning course of foot swelling, pain with ambulation, and tenderness to palpation. The course of rheumatoid arthritis can be broken up into 4 stages based on physical examination and radiographic findings:
Stage I: Discomfort and synovitis; no bone deformity or significant joint space narrowing
Stage II: Early involvement with flexible deformity; minimal erosive changes
Stage III: Fixed soft tissue deformity; significant erosive joint changes (Figure 13.1)
Stage IV: Severe hallux valgus, dislocation of the lesser metatarsophalangeal (MTP) joints with fixed hammer toe or claw toe deformities, pes planovalgus (flatfoot), and hindfoot arthroses; articular destruction (Figure 13.2)
The characteristic x-ray findings of RA are similar for all synovial joints. Early examination reveals soft tissue swelling and diffuse juxta-articular osteoporosis.5 Continued bouts of synovial inflammation lead to marginal cortical erosions,6 eventually giving to central erosions, joint space narrowing, and subluxation or dislocation. Radiologic progression correlates to the number of macrophages lining the joint and activate osteoclasts and other inflammatory cells.7 These cells release the inflammatory
cytokines and proteinases resulting in joint destruction.
cytokines and proteinases resulting in joint destruction.
 FIGURE 13.1 Arthritic changes with mild hallux valgus. (Reproduced with permission from Campbell JT. Hallux metatarsophalangeal arthrodesis. Tech Foot Ankle Surg. 2003;2(4);237-248. doi:10.1097/00132587-200312000-00004) |
Diagnosis of RA is based on clinical, radiographic, and laboratory findings (Table 13.1). The American College of Rheumatology recommends that at least 4 of the 7 criteria be present to make the diagnosis of RA.8 Serologic testing for rheumatoid factor is present in 70% to 90% of cases of RA, but may be elevated in numerous inflammatory conditions and other diseases.
Rheumatoid arthritis manifestations in the forefoot begin with inflammation in the synovium resulting in joint effusions. Significant joint effusions destabilize the capsular structures and collateral ligaments and with continued ambulation results in subluxation and eventual dislocation occur.4,9 The proximal phalanx displaces proximally and dorsally; the long flexor tendons and intrinsic muscles contract locking the proximal phalanx behind the metatarsal neck and generating a downward force on the metatarsal head. The dislocation of the lesser toes creates imbalances in the intrinsic and extrinsic muscles resulting in progressive claw toe deformity (Figure 13.3). With the lesser toes significantly clawed, the hallux loses lateral stability and migrates laterally to position below the second and third toes. As the hallux valgus deformity worsens, the weight-bearing of the first ray decreases with increasing force through the second and third metatarsal heads.
 FIGURE 13.2 Severe hallux valgus with deformity of the second toe. (Reproduced with permission from Campbell JT. Hallux metatarsophalangeal arthrodesis. Tech Foot Ankle Surg. 2003;2(4);237-248. doi:10.1097/00132587-200312000-00004) |
Midfoot pathology begins with synovitis and chondrolysis of the tarsometatarsal joints (Figure 13.4). The flattening of the midfoot is multifactorial with links to arthritis, ligamentous laxity, and posterior tibial tendon rupture.10,11 The pes planus foot typically continues to have limited motion producing a fibrous or boney ankyloses. Occasionally, the MTC joint becomes hypermobile which can result in transfer metatarsalgia and make weight-bearing difficult.
Hindfoot pathology is a less common finding associated with rheumatoid arthritis,
involved 10 times less frequent than the forefoot.12 Changes to the hindfoot occur later or slower as there is a significant increase in percentage of patients with symptomatic hindfoot arthrosis among patients diagnosed with RA for more than 5 years.9 Similar to other joints the pathology of RA in the hindfoot begins with destruction of the capsule and surrounding ligaments destabilizing the joint, beginning with the subtalar joint. The progression of RA to the pes planovalgus deformity and subtalar destruction can result in the difficult situation of pantalar arthritis and instability.
involved 10 times less frequent than the forefoot.12 Changes to the hindfoot occur later or slower as there is a significant increase in percentage of patients with symptomatic hindfoot arthrosis among patients diagnosed with RA for more than 5 years.9 Similar to other joints the pathology of RA in the hindfoot begins with destruction of the capsule and surrounding ligaments destabilizing the joint, beginning with the subtalar joint. The progression of RA to the pes planovalgus deformity and subtalar destruction can result in the difficult situation of pantalar arthritis and instability.
TABLE 13.1 Clinical Diagnosis of Rheumatoid Arthritis | ||||||||
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 FIGURE 13.3 Progressive claw toe deformity. (Reproduced with permission from Johnson JT. Treatment of fixed deformities of the distal interphalangeal and proximal interphalangeal joints of the lesser toes. Tech Foot Ankle Surg. 2004;3(2):100-105. doi:10.1097/01.btf.0000127976.85423.a1) |
Treatment
Treating pain due to RA requires an understanding of the natural progression of RA and what causes the pain at each stage. The goals of treatment are to maintain functional ambulation, of which pain control is an important aspect.
Pharmacotherapy
Pharmacotherapy is centered on the reduction of inflammation, which directly reduces pain and has the indirect effect of decreasing joint effusions which reduces the instability and has been shown to improve ambulatory capacity.13 This starts with nonsteroidal anti-inflammatory drugs (NSAIDs) in mild cases. The use of occasional intra-articular corticosteroid injection is an important addition, but systemic steroid is rarely used due to the well-known systemic side effects. As RA progresses disease-modifying antirheumatic drugs (DMARDs) are added to the treatment. Methotrexate, sulfasalazine, leflunomide, and hydroxychloroquine are examples of DMARDs which are all generally well tolerated, but can develop complications with chronic use. Newer agents termed “biologics” consist of monoclonal antibodies designed to inhibit the tumor necrosis factor (TNF)-α (infliximab, etanercept, and adalimumab) or IL-1 (anakinra) pathways. These medications show great promise with improvement of foot pain after 12 weeks of anti-TNF-α therapy14 and infliximab combined with methotrexate halting joint damage over the course of 1 year.
Despite appropriate pharmacologic treatment, many patients will develop characteristic deformities of the foot and secondary osteoarthritis. The initial treatment is to ensure proper footwear, and although there is not broad agreement on the perfect footwear, involvement of the pedorthist is key. Orthotic devices and shoes that redistribute forces help to
decrease pressure areas, decrease shear forces, support unstable joints, and reduce motion are helpful.15 Custom orthotics that incorporate a metatarsal dome pad are more effective at decreasing metatarsalgia and reducing pressure beneath the first and second metatarsal heads.16 Despite the importance of footwear, there may be no difference between expensive custom orthotics and rocker bottom shoes.17 Involvement of the hindfoot necessitates the
use of an Arizona brace (Figure 13.5) to stabilize the ankle and hindfoot or an ankle-foot orthosis (AFO) to stabilize from the leg through the midfoot.
decrease pressure areas, decrease shear forces, support unstable joints, and reduce motion are helpful.15 Custom orthotics that incorporate a metatarsal dome pad are more effective at decreasing metatarsalgia and reducing pressure beneath the first and second metatarsal heads.16 Despite the importance of footwear, there may be no difference between expensive custom orthotics and rocker bottom shoes.17 Involvement of the hindfoot necessitates the
use of an Arizona brace (Figure 13.5) to stabilize the ankle and hindfoot or an ankle-foot orthosis (AFO) to stabilize from the leg through the midfoot.
 FIGURE 13.4 Anteroposterior (AP) (A) and lateral (B) radiographs of midfoot flattening with abduction of the forefoot. (Reproduced with permission from Zide JR, Brodsky JW. Surgical approaches to arthritis and deformity of the midfoot. Tech Foot Ankle Surg. 2016;15(2):87-92. doi:10.1097/btf.0000000000000121) |
 FIGURE 13.5 Custom ankle-foot orthosis (AFO) (A) and Arizona (B) braces. (Reproduced with permission from Neville CG, Houck JR, Flemister AS. Science behind the use of orthotic devices to manage posterior tibial tendon dysfunction. Tech Foot Ankle Surg. 2008;7(2):125-133. doi:10.1097/btf.0b013e3181757571) |
Along with footwear, physical therapy is an important adjunct to maintain motion. Stretching of contracted tendons, particularly the Achilles, can help restore and maintain motion. Muscle strengthening may help maintain ambulatory capacity, and exercise in early RA improves neuromuscular performance with no significant effects on joint disease.18 As RA progresses and involves numerous joints, gait training with use of ambulatory aids may be required to maintain functional independence.
When pain, instability, and deformity progress beyond conservative management, the next option is surgery. Arthrodesis is the mainstay of treatment for rheumatoid foot and ankle. Commonly performed fusions include ankle arthrodesis (Figure 13.6), isolated hindfoot fusions, triple arthrodesis, midfoot arthrodesis, and arthrodesis of the first MTP joint (Figures 13.7 and 13.8). In the hindfoot, isolated fusions are acceptable,19 but will alter motion of the remaining joints.20 If more than 1 joint is diseased, a double or triple arthrodesis (Figure 13.9) is necessary. Midfoot fusions generally have little consequence on the foot given that there is normally less than 10° of motion within the joints of the midfoot. In the forefoot, fusion is only indicated for the first MTP joint. The joint is placed in a slightly dorsiflexed position to aid ambulation and has good results.21 Fusions will alter gait22 and alter biomechanics in adjacent joints ultimately increasing arthritic wear,23 but generally provide pain relief and a stable foot.
 FIGURE 13.6 Anteroposterior (AP) (A) and lateral (B) radiographs of ankle arthrodesis. (Reproduced with permission from Marsh A, Kooner S, Conlin C, Hussain R, Yeganeh KM, Lau J. Arthroscopic ankle arthrodesis. Tech Foot Ankle Surg. 2020;19(1):19-25. doi:10.1097/btf.0000000000000268) |
Ankle arthroplasty (Figure 13.10) has developed as a viable alternative to arthrodesis and maintains the motion of the ankle joint. The procedure is indicated for relatively low-demand individuals with minimal deformity. The technical difficulty of the procedure and issue with fusion should it fail has kept the volume of ankle arthroplasty far below that of the hip or knee. Despite limited use, total ankle arthroplasty has continued to progress and shown improved success rates with modern designs.24,25 Arthroplasty of the first MTP joint can be performed but has relatively high failure rates due to implant failure and loosening.26,27 The procedure is also relatively contraindicated with advanced deformity, which is often present in RA. Future implant designs and techniques may change the use of first MTP joint
arthroplasty, but it is currently not common for the treatment of RA.
arthroplasty, but it is currently not common for the treatment of RA.
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