Foot Capsulitis 
​Overview
Capsulitis of the foot is inflammation of the joint capsule, the thick ligamentous tissue that surrounds and stabilizes a joint.
It most commonly affects the second metatarsophalangeal (MTP) joint, but can involve other forefoot joints.
Capsulitis leads to pain, swelling, and instability under the ball of the foot and can mimic or coexist with other forefoot disorders such as Morton’s neuroma or metatarsalgia.
If untreated, progressive ligament attenuation may result in joint subluxation or dislocation, often leading to crossover toe deformity.


Etiology (Causes and Risk Factors)
Foot capsulitis results from mechanical overload and microtrauma of the joint capsule.
Mechanical/Structural Factors
  • Abnormal forefoot biomechanics:
    • Long second metatarsal or relatively short first metatarsal leading to excessive plantar pressure under the second MTP joint.
    • Hypermobile first ray or hallux valgus transferring load to the second MTP joint.
  • Pes planus (flatfoot) with forefoot overload.
  • Equinus contracture (tight Achilles or gastrocnemius) increasing forefoot pressure during gait.
  • Hammertoe or claw toe deformities altering weight distribution.
Overuse and Traumatic Factors
  • High-impact activities such as running, dancing, or court sports.
  • Occupational or recreational activities requiring prolonged standing or walking on hard surfaces.
  • Direct injury or repetitive microtrauma to the MTP joint.
Systemic/Inflammatory Factors
  • Rheumatoid arthritis or other inflammatory arthropathies may cause or worsen capsulitis.
  • Less commonly, gout or crystalline arthropathy.


Clinical Presentation and Diagnosis
Symptoms
  • Pain and swelling at the ball of the foot, most often beneath the second MTP joint.
  • Pain aggravated by walking barefoot, wearing thin-soled shoes, or high-impact activity.
  • Sensation of “walking on a stone” or fullness under the joint.
  • Progressive instability: feeling that the toe is “lifting” or drifting.
Physical Examination
  • Point tenderness over the affected joint capsule.
  • Mild edema and sometimes warmth.
  • Positive drawer test of the MTP joint (dorsal translation of the toe indicates capsular laxity).
  • Observation for toe deviation, early crossover deformity, or hammertoe.
Imaging
  • Weight-bearing radiographs: Assess metatarsal length, alignment, and subluxation.
  • Ultrasound or MRI: Useful to confirm synovitis, capsular tears, or to rule out Morton’s neuroma or stress fracture.


Treatment
Treatment is tailored to reduce inflammation, offload the joint, and correct underlying biomechanical causes.
Conservative Management (First-Line)
  • Activity modification and rest: Reduce running, jumping, and prolonged standing.
  • Footwear changes: Wide toe box, low heel, well-cushioned soles.
  • Orthotic devices:
    • Metatarsal pads or offloading inserts to redistribute pressure.
    • Custom orthoses to correct biomechanical faults (e.g., long second metatarsal or first-ray hypermobility).
  • Taping or splinting: Plantarflexion strapping of the toe to stabilize the joint and reduce capsular strain.
  • Anti-inflammatory therapy: Oral NSAIDs or topical anti-inflammatory gels.
  • Physical therapy: Calf stretching, strengthening of intrinsic foot muscles, and gait retraining.
Procedural/Surgical Treatment
  • Corticosteroid injection: May provide temporary relief in refractory cases but is used cautiously due to risk of further capsular weakening.
  • Surgery is considered for:
    • Persistent pain or progressive deformity despite several months of conservative care.
    • Procedures may include plantar plate repair, metatarsal shortening osteotomy (e.g., Weil osteotomy), or correction of associated deformities such as hallux valgus or hammertoe.


Expectations and Prognosis
  • Mild to moderate cases: Symptoms often improve with nonoperative treatment within 6–12 weeks, though complete resolution can take several months.
  • Chronic or severe cases: Without treatment, the capsule can attenuate and rupture, leading to toe drift, crossover deformity, and metatarsalgia, which may require surgical correction.
  • After surgery, most patients can expect pain relief and functional improvement, with return to normal shoes in 6–8 weeks and gradual activity progression over several months.
  • Long-term prognosis is excellent when underlying mechanical factors are corrected and preventive measures (proper footwear, orthoses) are maintained.


Key References (Peer-Reviewed)
  1. Coughlin MJ. Second metatarsophalangeal joint instability in the athlete. Foot Ankle Clin. 2009;14(2):287–301.
  2. Gregg JM, Silberstein M. Plantar plate pathology at the lesser metatarsophalangeal joints. Clin Podiatr Med Surg. 2011;28(1):41–56.
  3. Blitz NM, Ford LA, Christensen JC. Second metatarsophalangeal joint instability: diagnosis and treatment. J Foot Ankle Surg. 2004;43(5):326–335.
  4. Nery C, Coughlin MJ, Baumfeld D, Mann TS, Saito GH. Lesser metatarsophalangeal joint instability: prospective evaluation and treatment with plantar plate repair and Weil osteotomy. Foot Ankle Int. 2012;33(4):301–308.
  5. Gregg JM, Silberstein M, Schneider T, Marks P. Role of MRI and ultrasound in diagnosing plantar plate pathology. Foot Ankle Clin. 2015;20(3):515–534.


Summary
Foot capsulitis is inflammation of the joint capsule, most often at the second metatarsophalangeal joint, caused by repetitive mechanical stress and abnormal foot biomechanics.
It presents with pain, swelling, and instability under the ball of the foot.
Diagnosis is primarily clinical and supported by imaging when needed.
Conservative management—including footwear modification, orthoses, and physical therapy—is usually effective; persistent or progressive cases may require surgical repair.
With appropriate treatment, long-term outcomes are excellent and recurrence is uncommon when biomechanical issues are addressed.