Linear Fracture Metatarsal

The introduction of artifical sports surfaces in the late 1960s heralded a marked increase in injuries to the capsuloligamentous structures of the first MTP joint, presumably because of the higher friction coefficient of Astroturf as compared with grass. It is for this reason that the term ''turf toe'' was coined to describe this sports-related injury [24].

Turf toe is broadly defined by the Orthopedic Foot and Ankle Society as a ''plantar capsular ligament sprain'' of the first MTP joint. The mechanism of injury in the majority of cases is forced hyperextension. The injury occurs when the forefoot becomes fixed as a result of high friction and is positioned plantigrade with slight dorsiflexion and elevation of the heel off of the ground. Subsequently, an external force (another player) forces the first MTP joint into

2nd Metatarsal Synovitis
Fig. 11. Axial T1-weighted (A), axial STIR (B), sagittal STIR (C), and coronal T1-weighted (D) MR images demonstrate a midshaft second metatarsal stress fracture with a persistent linear fracture defect and exhuberant peripheral callus, with both marrow and parosteal soft tissue edema.

an even greater degree of dorsiflexion with a resultant tear of the capsular attachment at the level of the first metatarsal, which is its weakest point. The soft tissue injury may be complicated by cartilaginous or subchondral injury, as well as sesamoid fracture.

American football cleats have evolved to include an increased numbers of cleats, with greater flexibility of the forefoot. Both of these adaptations have been associated with an increased incidence of turf toe [25]. Although it has not been proven, hardening of the artifical turf over time may have a small contributory role to the increased incidence of turf toe [26].

The diagnosis is often evident from the history. Clinically the patient presents with acute inflammation of the first MTP joint, which worsens over the first day. Painful guarding limits active range of motion. Nevertheless, passive ranging reveals a pathologically increased range of motion, often more than 100° (as compared with a normal of 65° dorsiflexion from a neutral position) reflecting plantar capsuloligamentous insufficiency. Pain is typically worst at the plantar surface of the first MTP joint and is potentiated with passive

Metatarsal Stress Fracture
Fig. 12. Axial STIR (A) and sagittal T1-weighted and STIR (B,C) MR images demonstrate cres-centic low-signal marrow changes (arrows) in the subarticular second metatarsal head with flattening of the subchondral cortex and associated marrow and soft tissue edema.

dorsiflexion. Turf toe may be complicated by associated dorsal dislocation of the great toe [27].

Conventional radiographs may be used in the differential diagnosis of possible fracture or dislocation about the first MTP joint. Alternatively, sesamoiditis, tendonitis, and bursitis may be considered; however, sesamoiditis may be

Sesamoiditis

Fig. 13. Coronal T1-weighted (A) and STIR (B) images through the forefoot at the level of the first metatarsal head demonstrate sesamoiditis, manifest as uniform loss of fatty marrow signal localized to the tibial hallucal sesamoid (arrowhead). There is no contour defect or linear marrow signal alteration to suggest fracture or osteonecrosis.

Fig. 14. Sagittal STIR image demonstrates marrow edema within the tibial hallucal sesamoid. The curved white arrow indicates a linear fracture line without displacement or diastasis.

differentiated clinically from turf toe by its more indolent onset and association with repetitive trauma rather than acute, traumatic hyperextension of the first MTP joint. The gold standard for diagnosis of turf toe is MRI, which permits direct visualization of a tear through the plantar capsule [28]. MRI also allows direct visualization of concomitant soft tissue injury including synovitis, plantar soft tissue swelling, and tendonitis of the flexor hallucis longus and adductor hallucis, as well as possible associated osseous or cartilaginous injury to the ses-amoids or first metatarsal (Fig. 15).

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