Plantar Plate Insufficiency or Rupture (Turf Toe)

Anatomy

• During normal gait, MTPJ has to sustain more than 40 to 60% off bodyweight, during normal athletic activities this increases to 2-3 times the bodyweight. During running jump MTPJ sustains eight times the body weight.
• Metatarsophalangeal joint (MTPJ) is statically stabilised by the plantar plate and the collateral ligaments.
• Dynamic stability for the first MTPJ is provided by the short flexor complex, which is composed of medial and lateral bellies of flexor hallucis brevis, adductor hallucis and abductor hallucis muscles and the medial and lateral sesamoid bones and their ligaments.
• Plantar plate is the trapezoid shaped thickening of the MTPJ capsule at the weight bearing plantar aspect.
• It is a fibrocartilaginous structure that resists hyperextension and provides stability to the MTPJ.
• It is the major stabiliser of the MTPJ.
• It provides a smooth gliding surface for the flexor tendons inferiorly and metatarsal head superiorly.
• Proximally it is inserted into the metatarsal neck.
• Distally to the base of proximal phalanx by medial and lateral longitudinal bundles.
• It receives attachment from collateral ligaments, deep transverse metatarsal ligaments and vertical fibers of plantar aponeurosis.

Mechanism of injury

• Degenerative or traumatic rupture of plantar plate is an under-recognised cause of metatarsalgia.
• Degenerative rupture of plantar plate especially in the second MTPJ can lead to metatarsalgia with synovitis, which if untreated progresses to hammer-toe, claw-toe or crossover-toe deformity.
• In 2/3rd of cases the second toe is commonly involved as it tis the longest.
• Long term use of high heel foot wear may be a cause in older women as it causes chronic
• Lesions can cause metatarsalgia, instability, deformity and dislocation.
• Deformity may be in the sagittal plane such as hammertoe and claw toe or coronal plane such as crossover toe..
• During the heel-off and toe-off of stance phase of gait, the MTPJ becomes dorsiflexed. Dorsiflexion is passively resisted by the plantar plate and actively by the intrinsic musculature.
• With insufficiency of plantar plate, dorsal subluxation of MTPJ occurs. The interossei is displaced dorsally leading to hyperextension of MTPJ. The medially located lumbrical causes adduction deformity. Attenuation of collateral ligaments also contributed to the development of coronal plane deformity.
• Majority of cases have an insidious onset and is seen in sedentary older women.
• It can be seen in young athletic males after trauma.
• It can also be seen as a secondary deformity in association with hallux valgus, hallux varus, pes planus and hallux rigidus.
• The term Turf Toe introduced by Bowers and Martin in 1976 for injuries of the plantar plate of first metatarsophalangeal joint (MTPJ) of great toe seen in athletes playing on artificial turfs using lighter and flexible shoes.
• Coughlin coined the term ‘second crossover toe’ in 1987 to describe the coronal plane deformity.
• Hyper-dorsiflexion of the MTPJ is the most common mechanism of injury.
• Causes distractive forces on the plantar plate, sesamoid complex and toe flexors.
• In the big toe, the plantar plate rupture occurs distal to the sesamoids.
• Rarely tissue disruption occurs through the sesamoids producing sesamoid fracture.
• Injury may be partial or complete. It may extend to the collateral ligaments in presence of varus or valgus moment.
• Hyper-plantarflexion injury is called Sand Toe as it is common in beach volleyball.

Classification

Clinical Classification 

MRI Grading

Grade 1: Increased signal intensity with no loss of continuity in the plantar plate.

Grade 2: Button hole tear in the weight bearing area.

Grade 3: Partial rupture involving less than 50% of plantar plate thickness.

Grade 4: Rupture involve more than 50% of plantar plate thickness. Luxation present If collateral ligaments are torn.

Surgical Grading

0 – Plantar plate attenuation

1 – Transverse tear of distal attachment or mid substance involving less than 50%

2 – Transverse tear involving >50%

3 – Extensive tear which extends to collateral ligament

4 – Extensive tear with dislocation

Differential Diagnosis

• Stress fracture
• Degenerative arthritis
• Inflammatory arthritis
• Morton’s neuroma
• Frieberg’s infraction
• Instability of the lesser MTP joints
• Systemic arthritis with involvement of lesser MTP joints
• MTP joint synovitis
• Synovial cyst formation

Clinical Evaluation

• Clinical presentation varies. It ranges from metatarsalgia to frank MTPJ dislocation.
• Presentation is usually late.
• Plantar plate injuries are frequently missed in the initial examination.
• 95% present with gradual onset of pain, pain at the 2nd MTPJ, edema at the 2nd MTPJ and positive MTPJ drawer sign.
• Most common sign is localised tenderness over the plantar aspect of second MTPJ.
• In the history, ascertain the position of foot, weight bearing status and direction of force at the time of injury. Ask for the symptoms immediately after injury. Identify the site of pain and the activities that cause pain.
• When examining immediately after trauma, observe for any deformity, ecchymosis, soft tissue edema, joint effusion and site of tenderness.
• Initially there is no deformity, but later medial deviation is seen, followed by hyperextension and lastly involved toe crosses over the adjacent toes. Hammertoe deformity of PIPJ develops in chronic cases.
• It may be associated with hammer toe deformity.
• End stage of the spectrum of deformities is crossover toe.
• MTPJ movements is restricted especially the plantar flexion.
• Restriction of plantar flexion can be identified by Paper Pullout Test. A strip of paper is placed beneath the affected toe tip when the patient is standing. Patient is asked to grasp the paper with plantar flexion of toe. Inability to grasp is indicative of limitation of plantar flexion.
• Stress the MTPJ in valgus and varus to assess the integrity of collateral ligaments. Plantar flex to assess the dorsal capsule and dorsiflex to assess the plantar plate.
• MTPJ Drawer test- Stabilise the metatarsal neck with one hand. Hold the proximal phalanx with other hand.Try to translate the MTPJ in the dorsal and plantar direction to look for instability. Normally the proximal phalanx cannot be displaced dorsally. If proximal phalanx can be displaced with pain, the test is positive and indicates plantar plate tear.
• Test the strength of FHL and EHL.

Imaging

• Standard AP view, lateral oblique view and lateral view in weight bearing are required. If sesamoid fracture is suspected, sesamoid view may be necessary.
• Look for avulsion fractures, MTPJ subluxation and proximal migration of sesamoids.
• Stress lateral view in forced dorsiflexion can be helpful as it can show increased gap between sesamoids and proximal phalanx base when compared to lateral view in neutral position.
• Diagnosis can be confirmed by conventional arthography or MRI.
• MRI with  non-fat-suppressed T1-weighted or proton density–weighted sequence in three standard planes and  proton density–weighted fat-suppressed or short tau inversion recovery (STIR) sequences to assess plantar plate and ligaments is needed.
• Normal plantar plate has very low signal intensity on MRI and is difficult to differentiate from overlying flexor tendon.
• On the MRI, tears appear as areas of hyperintense signal in the normally low intensity plantar plate.
• Tears are usually located at the distal attachment adjacent to the metatarsal head.
• Plantar plate recess, a normal anatomic variant is present in 47% at the distal attachment. It should not be mistaken for a tear.

Treatment

• Most acute injuries are treated conservatively by R.I.C.E ( Rest, Ice, Compression, Elevation) followed by plaster immobilisation or taping in plantar flexion.
• Indications for surgery in chronic
  • Persistent loss of toe push off strength
  • Gross instability
  • Progressive subluxation
  • Progressive clawing
  • Large capsular avulsion with unstable joint
  • Displaced sesamoid fracture or proximal migration of sesamoids
  • Traumatic hallux valgus deformity
  • Failed nonsurgical treatment
• Goal of surgery is restoration of anatomy and function
• Ideal procedure is plantar plate repair or reconstruction.
• Indirect surgical realignment utilising soft tissue release, soft tissue reefing, tendon transfer, and periarticular osteotomies.
• Conservative treatment is usually ineffective in chronic tears with instability.
• Non-operative options
  • Thing of toe to the adjacent digit opposite to the coronal deformity
  • Foot wear with silicone insole and metatarsal bar.
  • Foot wear with reduced heel height and wide toe box.
  • Silicone toe sleeve for hammertoe.
• Options for surgical treatment
  • Plantar approach or dorsal approach with Weil osteotomy for lesser toes.
  • Medial approach with J shaped plantar extension or combined medial and plantar approach for big toe.
  • Postoperative management
    • Immobilise for 5-7 days. Passive plantar flexion allowed.
    • Non weight bearing for 4 weeks.
    • Active plantar flexion allowed after 4 weeks.
    • Active dorsiflexion permitted after 8 weeks.
    • Running started after 3 months.
    • Playing resumed at 4 months.
  • Plantar plate repair
  • Flexor tendon transfer to proximal phalanx indicated in those presenting late with claw toe deformity.
  • MTP joint synoviectomy
  • Soft tissue release with capsular reefing
  • Phalangeal or metatarsal osteotomy