Forced dorsiflexion injuries of the hallux MTP joint are relatively common in athletes and are known as "turf toe". The pathology includes sprains and tears of the plantar plate, ligament sprains, synovitis and occasionally impaction injuries of the dorsal metatarsal head. Taping and the RICE regime wil allow most to settle. A stiff soled shoe is recommended for prevention of future sprains.
If a soft tissue injuries fails to settle, MR may show joint surface injuries, loose bodies or synovitis and arthroscopic debridement may be recommended. There is not enough data to say how useful MR is in screening these injuries. Abnormalities found at arthroscopy include osteochondral lesions, synovitis and "meniscal lesions" equivalent to those in the ankle. The majority of patients improve markedly - Debnath et al (2006) reported a mean AOFAS hallux score of 97/100 at 2 years in trauma patients.
There is an equivalent forced plantarflexion injury first described in professional beach-volleyball players and hence known as "sand toe".
Almost all MTP dislocations are forced dorsiflexion injuries. Most reported cases are in the hallux, where Jahss developed a classification based on a small series. He found that the plantar plate became detached from the metatarsal neck, allowing the toe to dislocate dorsally with the plantar structures locked around the metatarsal head. Jahss described three variants:
- type 1 - the sesamoids and intersesamoid ligament remain intact, producing a tightly locked dislocation
- type 2A - the intersesamoid ligament ruptures, so the sesamoids appear widely separated on Xray and the dislocation is easily reduced
- type 2B - one of the sesamoids fractures; the proximal portion is held in normal repationship to the other sesamoid by the intersesamoid ligament while the distal portion retracts distally. Again the dislocation is usually easy to reduce.
Other variants have been described.
Dislocation of the lesser MTP joints in which the plantar plate becomes locked on the dorsum of the MT head, preventing reduction, have also been described (Rao 1979).
- Debnath UK et al. Indications for and technique of first metatarsophalangeal joint arthroscopy. FAI 2006;27:1049-54
- Frey C et al. Plantarflexion injury to the metatarsophalangeal joint ("sand toe"). FAI 1996;17:576-81
- Jahss, MH. Traumatic dislocations of the first metatarsophalangeal joint. Foot Ankle 1980;1:15-21
- Rao JP, Banzon MT. Irreducible dislocation of the metatarsophalangeal joints of the foot. CORR 1979;145:224-6
- Watson TS et al. Periarticular injuries to the hallux metatarsophalangeal joint in athletes. Foot Ankle Clinics 2000;5:687-713