Plantar Plate Injury (Turf Toe)

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Anatomy

See Drakos et al for a brief review.[1] The first MTPJ integrity is related primarily to the joint capsule, collateral capsular ligaments, and the flexor-tendon complexes coursing on either side. The soft tissues stabilise the joint allowing for approximately 50° of dorxiflexion and 30° of plantarflexion.

  • Medial and lateral collateral capsular ligaments - provide valgus and varus stability.
  • Medial flexor-tendon complex - comprised of the medial head of FHB and abductor hallucis, which envelops the medial sesamoid and attaches to the medial proximal phalanx.
  • Lateral flexor-tendon complex - comprised of the lateral head of FHB and adductor hallucis, which envelops the lateral sesamoid and attaches to the lateral proximal phalanx.
  • Sesamoids - fulcrums that increase the lever arm of the FHB tendons and increase the plantar strength of the first MTPJ.
  • Flexor hallucis longus (FHL) - the tendon is in a separate sheath between the sesamoids and inserts on the distal phalanx.
  • Plantar plate - fibrocartilaginous structure which is made up of the thickened plantar joint capsule, and medial and lateral flexor-tendon complexes. It courses from the first metatarsal head and attaches to the proximal phalanx. It is designed to resist dorsiflexion.

Injury

"Turf toe" normally refers to a sprain of the MTPJ as a result of a hyperextension injury. The plantar plate, designed to resist dorsiflexion, can be torn with variable severity. The abductor or adductor attachments or collateral ligaments can also be torn with lateral loading (cutting sports). The sesamoids can also be injured including fracture. A loose body may arise within the joint. Die-punch injuries, shear injuries, and bone marrow oedema may occur. Exacerbating factors can lead to stiffness, osteoarthritis, and pain. Injury to the plantar plate and FHB tendons can also reduce MTPJ competence and push-off strength.

Examination

  • Passive and active range of motion
  • FHL strength (attaches to the distal phalanx, flexes the distal phalanx and interphalangeal joint)
  • FHB strength: stabilise the interphalangeal joint in a neutral position, then ask the patient to flex the MTPJ against resistance applied to the proximal phalanx. Minimal strength suggests instability and substantial injury.
  • Stability testing: anteroposterior translation and varus-valgus stability.
  • Lachman test: stabilise the first metatarsal superiorly and inferiorly with one hand, apply an anterior and posterior translational force to the proximal phalanx, feel for dorsal or plantar subluxation.

Imaging

Radiographs
  • Weight-bearing views
  • Contralateral views for comparison if there is proximal sesamoid retraction, possible sesamoid fracture, or bipartite sesamoid is present.
  • Stress view to evaluate for instability, for example with the proximal phalanx dorsiflexed.
MRI

Can define ligamentous injuries but non dynamically.

Treatment

If there is instability, unfortunately there are no published prospective trials to guide treatment. Long term disability with MTPJ stiffness, arthrosis, and pain has been reported. Definitive criteria to guide operative management are still being investigated.

References

  1. Drakos et al. Plantar-plate disruptions: "the severe turf-toe injury." three cases in contact athletes. Journal of athletic training 2015. 50:553-60. PMID: 25695855. DOI. Full Text.

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