A Closer Look At Tendon Transfers For Crossover Hammertoe
When examining the patient with a crossover toe, one should scrutinize the presence of a hallux valgus deformity, digital contracture, plantarflexed second metatarsal, second MPJ instability, neuritic symptoms and gastrocnemius contracture.10 The gastrocnemius muscle is the predominant deforming force in patients with structural breakdown and chronic pathological changes related to the foot and ankle.13 Therefore, we stress the importance of addressing equinus if any surgical correction is going to be successful.
A Closer Look At Tendon Transfers And Juxtaposed Procedures
A crossover toe characteristically presents in a varus position at the MPJ, resulting in a hammertoe deformity. This intrinsic muscular instability is a result of a mechanical disadvantage that typically occurs at the second MPJ and is coupled with a hallux valgus deformity.14 The second MPJ is frequently subject to increased weightbearing loads, which produce progressive attenuation of the plantar plate insertion into the proximal phalanx. In patients with a combined hallux valgus deformity, this further increases the load placed on the second metatarsal head.6
It is helpful to remember that studies show 60 percent of normal weightbearing forces pass through the first ray from heel strike to toe-off.15 Once the first ray fails to support this necessary load, the medial column collapses. This also leads to a lateral load shift to the lesser metatarsals, continued biomechanical abnormalities and continued deforming forces, perpetuating an aggressive cycle.
Likewise, Morton proposed that the unstable first ray is an inherent cause of second metatarsal pathology.16 Greisberg and coworkers also reported similar findings as patients with second MPJ synovitis and metatarsalgia had greater first ray mobility. In clinical situations, the severe bunion is associated with lesser metatarsal overload (metatarsalgia) through an inefficient medial column (first ray).17 Stabilizing and realigning the first ray through a Lapidus procedure provides a stable construct to the medial column and also improves the efficiency of the peroneus longus.18 Following the Lapidus arthrodesis, the first ray is better able to absorb the ground reactive forces during weightbearing. The procedure is predictable in stabilizing the first ray in three planes with emphasis on the sagittal and frontal planes along with improved intermetatarsal angles.19
Crossover toe deformity treatment goals are to reduce the deformity, provide pain relief, improve function, reduce morbidity and prevent the progression of the existing deformity. The surgical approach to digital crossover deformity varies and is based on patient suitability and the surgeon’s preference. One may modify the surgical approach to address the presentation of contracted digits with or without additional MPJ pathology, hallux abductovalgus and first ray stability.20
The digital joint-destructive procedures include arthroplasty and arthrodesis as well as digital implants. Joint-sparing hammertoe correction is based on soft-tissue rebalancing and may entail open, percutaneous or closed procedures that aim at reducing capsular and tendon contractures, and deforming soft tissue forces by balancing the tendons.20