Plantar Plate Injury

By AAPSM on 3rd of December 2013 at 9:37am | Share on Facebook
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Tears of the plantar plate may be the most common cause of pain under the second metatarsophalangeal joint, though it can occur at any of the metatarsophalangeal joints. It is also referred to as predislocation syndrome, crossover toe deformity and floating toe syndrome.

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Tears of the plantar plate may be the most common cause of pain under the second metatarsophalangeal joint, though it can occur at any of the metatarsophalangeal joints.  It is also referred to as predislocation syndrome, crossover toe deformity and floating toe syndrome.  A fibrocartilaginous thickening of the metatarsophalangeal joint (see Figs 1, 2), the plantar plate serves to:

  • stabilize the metatarsophalangeal joint
  • assist in the windlass mechanism due its attachment to the plantar fascia
  • resist hyperextension of the metatarsophalangeal joint
  • absorb compressive loads

Figures 1 & 2 – Anatomy of the metatarsophalangeal joint demonstrating the plantar plate

Cause

The second metatarsophalangeal joint is most likely to be affected as it is the longest metatarsal and has unopposed lumbricals and no plantar interossei insertions.  Plantar plate tears usually result from repetitive overload from abnormal forefoot loading patterns resulting from hallux valgus, excessive pronation, short first metatarsal or long second metatarsal.  The tear usually arises from the base of the proximal phalanx.1

Clinical Features

The athlete usually complains of localized pain under the metatarsophalangeal joint.  Swelling may be present, extending to the dorsal aspect of the joint.  Pain is aggravated by dorsiflexion of the affected joint.  Neuroma-like symptoms may be experienced by patients due to irritation of the plantar digital nerve from the localized oedema.

Examination reveals pain at the base of the proximal phalanx which may be aggravated by dorsiflexion of the joint.  In relaxed stance a dorsiflexion deformity of the toe may be noted.  This is often accompanied by a crossover deformity.  The modified Lachman’s test can also be utilized.  The metatarsal head is stabilized and the proximal phalanx is dorsally translocated (see Fig 3).  A 2mm or 50% joint displacement is a positive sign of plantar plate laxity.

Figure 3 – Modified Lachman’s test


Investigations

An ultrasound may reveal a hypoechoic defect in the plantar plate, usually at the distal attachment.  An arthrogram may demonstrate synovial hypertrophy and extravasation of dye into the flexor tendon sheath.  MRI may also demonstrate a tear of the plantar plate with increased signal intensity within the plate, along with a loss of continuity.2

Treatment

Treatment initially consists of icing, NSAIDs, relative rest, plantarflexion strapping of the digit (see Fig 4) and accommodative padding to reduce loads under the affected metatarsophalangeal joint.  Orthoses and a stiff-soled shoe or rocker-bottom shoe are also required.  Orthosis modifications may include a plantar metatarsal pad (the bulk of the pad should sit proximal to the metatarsal heads), anterior shell edge longer to the second metatarsal (Fig 5), and control rearfoot and midfoot forces which may lead to overload at the 2nd MPJ.  Soft top covering options should also be considered.  An extra-articular corticosteroid injection may also be useful.  Primary repair of the plantar plate with or without a flexor tendon transfer may be required in patients that don’t respond to conservative measures.

 


Figure 4 – Plantarflexion strapping


Figure 5 – Orthosis modifications


References
1.    Yu GV, Judge MS, Hudson JR, Seidelmann FE. Predislocation Syndrome. JAPMA. 2002;92;182-199.

2.    Keir R, Abrahamian H, Caminear D, et al. MR Arthrography of the Second and Third Metatarsophalangeal Joints for the Detection of Tears of Plantar Plate and Joint Capsule. AJR. 2010;194;1079-1081.