We used finite element analysis to study the mechanical displacements at three planes of the second through fourth hammertoes during the push-off phase of gait using a new neutral or 10° angled memory alloy intramedullary implant (FDA K070598) used for proximal interphalangeal joint arthrodesis.
After geometric reconstruction of the foot skeleton from computed tomographic images of a 36-year-old man, an intramedullary implant was positioned in the virtual model at the neutral and 10° angled positions at the proximal interphalangeal joints of the second through fourth hammertoes during the push-off phase of gait. The obtained displacement results in three planes were compared with those derived from the nonsurgical foot model using finite element analysis.
These results support the successful use of either a neutral or angled implant for proximal interphalangeal joint arthrodesis, with the neutral implant yielding slightly better results.
The neutral implant reduced vertical displacement to a greater extent than did the angled implant. We also highlight the potential risk of iatrogenic curly toe when performing a proximal interphalangeal joint arthrodesis using an angled implant specifically at the fourth toe.
Background: Transposition of the flexor digitorum longus tendon has been widely reported for the correction of flexible claw or hammer toe deformities. In contrast, a search of the literature revealed no previous reports of transposition of the flexor digitorum brevis tendon for treatment of these conditions. We performed a cadaver study to determine whether the flexor digitorum brevis tendon is long enough to be transferred to the dorsum of the proximal phalanx of the toe from its lateral or medial aspect.
Methods: Transposition of the flexor digitorum brevis tendon was attempted in 180 toes of cadaver feet: 45 second toes, 45 third toes, 45 fourth toes, and 45 fifth toes.
Results: The flexor digitorum brevis tendon was long enough to be successfully transposed in 100% of the second, third, and fourth toes and in 42 (93.3%) of the fifth toes. In the three remaining fifth toes (6.7%), the flexor digitorum brevis tendon was absent, a known anatomical variation.
Conclusions: Transfer of the flexor digitorum brevis tendon to the dorsum of the proximal phalanx can be performed for correction of claw or hammer toe deformities, especially in the second, third, and fourth toes. The transverse aponeurotic fibers originating from the extensor digitorum longus impede the transfer of the flexor digitorum brevis tendon, and meticulous excision of these fibers is essential to the success of the procedure. (J Am Podiatr Med Assoc 98(1): 27–35, 2008)