Osteoarthritis (foot)

• foot is involved with a variable frequency according to the joint sites
  • hindfoot osteoarthritis (OA) is quite uncommon, but forefoot OA is a frequent joint disease, particularly at the level of the first metatarsophalangeal joint, that represents the prime site of OA changes
    • estimated that OA of the big toe joint affects 35% to 60% of adults aged over 65 years (1)
  • midfoot is rarely involved in OA alterations and only few research groups have described non-Charcot arthropathy of the midfoot, including patients with primary OA in this joint site
    • midfoot OA is usually post-traumatic - miidfoot injuries affect are commonly seen in the athletic population

Aetiology of foot OA is poorly understood

• linked to trauma, sport injuries, inflammatory arthropathy, mechanical stress and idiopathic osteoarthritis
• OA of the first metatarsophalangeal joint of the foot, commonly referred to as hallux limitus or hallux rigidus
  • thought to be caused by the compression of the dorsal aspect of the joint during the propulsive phase of gait in people with an excessively wide first metatarsal, wide proximal phalanx and long sesamoids
• people with flat feet or high arches are at greater risk for developing foot OA
• also general factors as aging and obesity seem to play a key role in the pathomechanism of OA

Clinical features

• usual symptoms associated with foot OA include:
  • pain and stiffness of the affected foot
  • swelling near the affected joint
  • limited range of motion
  • difficulty in walking and bony protrusions
    
    
• foot joints that are most commonly affected by osteoarthritis include:
  • the 3 joints of the hindfoot (talocalcaneal joint, talonavicular joint, calcaneocuboid joint)
  • the midfoot (metatarsocuneiform joint)
  • the great toe (first metatarsophalangeal joint)
    
    
• structural alterations of the first metatarsophalangeal joint are described as either hallux limitus or hallux rigidus
  • term used depends on the magnitude of available joint motion and the severity of joint degeneration. Hallux limitus is characterized by restricted sagittal plane motion (primarily dorsiflexion) caused by periarticular osteophytes; whereas hallux rigidus displays an absence of joint motion due to end stage degenerative joint disease and subsequent joint ankylosis (2)

Diagnosis

• physical examination can detect swelling, bone spurs or other deformities, limited range of motion and pain which occurs with movement.
• however, to define the diagnosis conventional radiographs are required to assess typical alterations found in foot OA joints
  • US and MRI are gaining importance in the diagnostic pathway of OA, even if conventional radiology must still be referred as the "gold standard" imaging technique (3)

Management principles:

• conservative therapy
  • weight-loss is often proposed as an important endpoint to reduce foot pain
  • exercise has been proven to be a protective factor against OA as it stimulates biosynthetic activity of chondrocytes
    • patients with OA capable of exercise should be encouraged to partake in a low-impact aerobic exercise program (e.g. walking, biking, swimming or other aquatic exercise)
  • pharmacological options include
    • oral or topical non-steroidal anti-inflammatory drugs, and intra-articular corticosteroid injections; while intra-articular hyaluronate injections, and opioids are conditionally recommended in patients who have an inadequate response to initial therapy
      
      
• surgical options
  • in consideration of hallux rigidus and hallux limitus
    • surgical options to treat hallux rigidus and/or limitus. Procedures include cheilectomy (removal of a bony lump at the joint margin), arthrodesis (surgical fusion of bones), arthroplasty (joint replacement via remodelling or implant), osteotomy (cutting bone to shorten, lengthen or realign), soft tissue release and sesamoid release or excision

Reference:

• Van Saase JL, Van Romunde LK, Cats A, Vandenbroucke JP, Valkenburg HA. Epidemiology of osteoarthritis: Zoeter - meer survey. Comparison of radiological osteoarthritis in a Dutch population with that in 10 other populations. Ann Rheum Dis 1989; 48: 271-280.
• World Health Organization: International Statistical Clas - sification of Diseases and Related Health Problems, 10th Revision; 2007.
• Iagnocco A et al. Osteoarthritis of the foot: a review of the current state of knowledge.Med Ultrason. 2013 Mar;15(1):35-40.