Lesser MTPJ instability - plantar plate disorders

Introduction

The plantar plate may be a small anatomic structure but, when damaged, it can contribute to significant pathology and result in complex deformities. The treatment of plantar plate disorders is challenging and often a topic of significant debate. Before treatment begins, however, an accurate diagnosis must be made. The diagnosis of plantar plate dysfunction is difficult and is highly dependent on the clinical examination and a high index of suspicion.

 

Classification for PDS (pre dislocation syndrome)

  • Stage I:  Mild joint oedema dorsally and plantarly; extreme tenderness; normal alignment
  • Stage II:  Moderate oedema; noticeable toe deviation clinically and radiographically; lack of toe purchase
  • Stage III: Moderate oedema; pronounced deviation clinically; subluxation or dislocation on radiographs

 

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Classic clinical presentation of plantar plate dysfunction. The second toe is subluxated dorsally and medially and lies dorsally on the hallux.

 

Demographics and Patient History

  • Two common population groups:
    • sedentary, older women (50-70y) with prevalent use of high-heeled shoes
    • more athletic men aged 25-64y with repetitive activity causing joint instability
  • More prevalent in the female population
  • Typical presentation is acute or subacute onset of pain around the plantar aspect of the lesser MTPJ often with no history of trauma
  • Pain is often described as aching / throbbing, sometimes sharp, which increases with activity
  • Symptoms may include the feeling of a lump or bruise on the ball of their foot
  • The magnitude of pain described is often markedly disproportionate to the physical examination
  • Interference with activities and lifestyle may result in anxiety or depression

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Clinical examination showing stage I of PDS. There is localized oedema plantarly and tenderness to palpation of the plantar lateral aspect of the second metatarsophalangeal joint. No malalignment is seen.

(A) Clinical examination showing stage II of PDS. There is medial deviation of the second toe resulting in gapping between the second and third toes. (B) Radiograph showing stage II of PDS. There is obvious medial deviation of the second metatarsophalangeal joint.

 

Causative Factors

  • PDS can be described as a monoarticular synovitis or capsulitis that causes attenuation of the plantar plate
  • Intrinsic factors:
    • inflammatory arthropathies, including rheumatoid arthritis and connective tissue disorders
    • structural deformities
    • abnormal biomechanics
      • first ray insufficiency
      • medial column hypermobility
      • elongated or elevated metatarsal
      • hallux valgus can cause elevation of the second toe and subluxation of the MTPJ
    • Hindfoot deformities including pes planovalgus, pes cavus, and equinus are common contributing factors to lesser MTPJ instability and digital deformities
  • Extrinsic factors:
    • acute trauma
    • shoe wear that creates increased pressure and stress on the forefoot, such as high-heeled shoes 

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PDS Stage III; complete subluxation of the second metatarsophalangeal joint has resulted

 

Differential Diagnosis

  • Morton's neuroma
  • Hallux valgus with lateral deviation of the lesser toes
  • Hammer / claw toes
  • Rheumatoid arthritis
  • Osteoarthritis
  • Gout
  • Sesamoiditis
  • Freiberg's disease

 

Clinical Examination

  • Look: inspect for deformity, swelling, or discoloration
  • Feel: palpate the affected metatarsophalangeal joint for tenderness, instability, or crepitus
  • Move: assess the range of motion of the affected toe, including flexion, extension, abduction, and adduction
  • Special tests:
    • Vertical drawer test: assess joint stability by moving the proximal phalanx plantar and dorsally while holding the metatarsal head stable
    • Provocative tests: various manoeuvres to elicit pain or instability in the affected joint, such as the plantar plate stress test or the metatarsal squeeze test
  • Gait analysis
  • Neurovascular exam

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(A, B) The vertical drawer test is performed clinically and then demonstrated on saw bones. It is imperative that the force applied on the proximal phalanx is purely vertical and the movement is not dorsiflexion of the metatarsophalangeal joint. (C, D) Radiographs of a positive vertical stress test, indicative of attenuation or a tear of the plantar plate.

 

Radiographic Evaluation

  • X-rays: weight-bearing AP, lateral, and oblique views
  • MRI: to assess the soft tissues of the foot, including the plantar plate, ligaments, and tendons; MRI can also detect bone marrow oedema, synovitis, or other signs of inflammation
  • Ultrasound: provides dynamic joint assessment to assess the integrity of the plantar plate and other soft tissues

 

Treatment

Conservative management:

  • analgesia, incl NSAIDs
  • rest, ice, compression, and elevation (RICE),
  • physical therapy
  • patient education: foot care, footwear, and activity modification
  • orthotics including toe taping

Surgical management:

  • plantar plate repair or reconstruction
  • ligament repair or reconstruction
  • tendon transfer
  • excision arthroplasty (MT head or Stainsby)
  • combination (e.g. Weil’s + PIPJ fusion)
  • rarely MTPJ arthrodesis
  • rehabilitation: restore strength, flexibility, and function to the affected foot

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(A) Acute, traumatic dorsal and medial dislocation of the 2nd MTPJ with rupture of the plantar plate following a fall. (B) Postoperative radiograph after repair of the plantar plate, second metatarsal osteotomy, and second hammertoe repair. (C) Postoperative photograph showing good alignment and reduction.

 

The choice of treatment for lesser MTP instability will depend on the severity of the instability, the presence of any associated deformities or joint damage, and the patient's overall health and activity level. A multidisciplinary approach may be necessary to ensure optimal outcomes for patients with this condition.

 

References

  • Coughlin MJ. Crossover second toe deformity. Foot Ankle 1987;8:29
  • Coughlin MJ. When to suspect crossover second toe deformity. J Musculoskel Med 1987;4:39–48
  • Coughlin MJ. Second metatarsophalangeal joint instability in the athlete. Foot Ankle 1993;14:309–19
  • Coughlin MJ. Subluxation and dislocation of the second metatarsophalangeal joint. Orthop Clin North Am 1989;20:535–5
  • Nery C, Coughlin MJ, Baumfeld D, et al. Lesser metatarsophalangeal joint instability:prospective evaluation and repair of plantar plate and capsular insufficiency. Foot Ankle Int 2012;33:301–11
  • Yu GV, Judge MS. Predislocation syndrome of the lesser metatarsophalangeal joint: a distinct clinical entity. In: Camasta CA, Vickers NS, Carter Sr, editors
  • Reconstructive surgery of the foot and leg: update ’95. Tucker (GA): The Podiatry Institute; 1995,109–13
  • Yu GV, Judge MS, Hudson JR, et al. Predislocation syndrome: progression subluxation/dislocation of the lesser metatarsophalangeal joint. J Am Podiatr Med Assoc 2002;92:182–99
  • Kaz AJ, Coughlin MJ. Crossover second toe: demographics, etiology, and radiographic assessment. Foot Ankle Int 2007;28:1223–37
  • Butterworth ML, Block AJ. Update on Fibrocartilaginous Disease Clinical Examination. Clin Podiatr Med Surg. 2022 Jul;39(3):371-392. doi: 10.1016/j.cpm.2022.03.002. PMID: 35717056