Emerging Concepts In Treating Second Crossover Toe Deformity
Given the complexities of the second crossover toe deformity, these authors discuss key pathomechanics, review essential elements to the clinical examination, offer conservative care options and provide insights on different surgical techniques.
The crossover second toe deformity may be one of the most challenging surgical disorders foot and ankle surgeons face. The condition is most often associated with a pronounced hallux valgus deformity that one must address surgically in order to achieve a satisfactory and lasting result.
The pathomechanics of this condition are most interesting and can be documented throughout the developmental course of this foot disorder.
The patient typically will develop a cascade of deforming events. A hallux valgus deformity effectively “shortens” the great toe due to the angulation of the hallux. This leads to a relative increase in the length of the second toe.
The second toe becomes unstable due to a crowding and buckling effect caused by several factors. These factors include:
• toe buckling caused by stockings or shoes;
• intrinsic muscular instability as a result of a mechanical disadvantage;
• increase of the first and second intermetatarsal angles leading to central metatarsal overload;
• a frequently elongated second metatarsal leading to second metatarsal overload and metatarsalgia accompanied by chronic capsulitis and/or intractable plantar keratosis (IPK);
• hammertoe deformity with metatarsophalangeal (MPJ) extensor contracture; and
• wearing of the plantar plate due to increased load and shear of the second metatarsal head, and lack of load sharing by the contracted second toe.
Other factors that may lead to the aforementioned crowding and bucking effect include further abduction and deviation of the hallux laterally due to a lack of resistance of the dorsally located second toe. Another potential cause may be adduction of the second toe dorsally due to a lack of intrinsic stability, weakness of the hallux due to deformity (flexor substitution) and a medial pull by the long flexor tendon to the second toe.
Ultimately, physicians may see a dorsal dislocation of the second MPJ due to a rupture of the plantar plate off the base of the second toe and proximal phalanx.
Key Pearls For The Diagnostic Workup
A thorough history and clinical examination will often direct the treatment of patients presenting with a crossover toe deformity. Patients with a history of inflammatory joint disease or destruction fall in a separate category and a global appreciation of the disorder will drive the treatment options.
Conduct a typical physical examination of the ankle and foot. Obtain standing radiographs with a minimum of three views. Palpate the plantar surface. Examine the second MPJ for pain and swelling at the distal metatarsal region. Concurrent examination of the contralateral foot is especially helpful in appreciating the swelling. Perform a Kelikian push-up test to evaluate the ability of the second toe to plantarflex with pressure beneath the second metatarsal. Compare the amount of plantarflexion to the asymptomatic contralateral foot.
Proceed to perform a sagittal plane drawer test on the symptomatic MPJ joint. Again compare the affected foot with the normal foot for dorsal instability.
One would perform this by firmly stabilizing the second metatarsal head between the thumb and forefinger of the left hand. Grasp the base of the proximal phalanx with the thumb and forefinger of the right hand, and perform a retrograde and purely vertical (not dorsiflexion) maneuver to evaluate laxity and the ability of the MPJ to dislocate. A positive test indicates a toe that is at high risk to dislocate and, in our opinion, warrants a surgical recommendation in the healthy patient.