Anatomical Study of the Developmental Mechanism of Lesser Toe Deformity

: [Purpose] An anatomical study was performed in order to investigate the effects of the activity of the flexor digitorum brevis (FDB) and flexor digitorum longus (FDL) in elderly frail people with hammer toe deformity. [Participants and Methods] Nine feet from five cadavers were used in this study. All the third toes were disarticulated at the tarsometatarsal joint. The tendons of FDB and FDL, and the joint capsule were left intact, but other soft tissues were removed. The tendons of FDB and FDL were pulled separately under two conditions: (1) Contact condition: the bottom of the phalanx was contacting the floor; (2) Non-contact condition: the bottom of the phalanx was not contacting the floor. [Results] When the FDB was pulled, because the proximal interphalangeal joint was flexed, the distal interphalangeal joint extended to show hammer toe. [Conclusion] The actions of the FDB and FDL were different under the two conditions. It was considered that over-activation of the FDB was an important factor of hammer toe in elderly frail people.

[1]  Sebastien Racinais,et al.  Recruitment of the plantar intrinsic foot muscles with increasing postural demand. , 2012, Clinical biomechanics.

[2]  Oh-Yun Kwon,et al.  A comparison in the muscle activity of the abductor hallucis and the medial longitudinal arch angle during toe curl and short foot exercises. , 2011, Physical therapy in sport : official journal of the Association of Chartered Physiotherapists in Sports Medicine.

[3]  H. Menz,et al.  ISB Clinical Biomechanics Award 2009: toe weakness and deformity increase the risk of falls in older people. , 2009, Clinical biomechanics.

[4]  C. Verheyen,et al.  Definitions of hammer toe and claw toe: an evaluation of the literature. , 2009, Journal of the American Podiatric Medical Association.

[5]  M. Morris,et al.  Foot and ankle risk factors for falls in older people: a prospective study. , 2006, The journals of gerontology. Series A, Biological sciences and medical sciences.

[6]  R. Fuhrmann.  [Lesser toe deformities]. , 2004, Therapeutische Umschau. Revue therapeutique.

[7]  J. Koebke,et al.  Pathomorphology of the hammer toe , 1998 .

[8]  M. Coughlin.  Mallet toes, hammer toes, claw toes, and corns. Causes and treatment of lesser-toe deformities. , 1984, Postgraduate medicine.

[9]  D. Green,et al.  Interossei and lumbricales muscles of the foot. An anatomical and functional study. , 1980, Journal of the American Podiatry Association.