Socks and Foot Pathologies
The following foot pathologies can be directly affected by the type of hosiery worn by the athlete:
Toenails: subungual hematoma, onychomycosis, onychogryphosis
Integument: friction blisters, hyperkeratoses, heloma dura/molle
Infections: dermatophyte, yeast, bacteria, viral (verruca)
Mechanical or Shear Induced Injury of Subcutaneous tissue: capsulitis, bursitis, calcaneal fat pad atrophy
Mechanical or Shear Injury Against Bone Prominence: retrocalcaneal exostosis, sesamoiditis, hallux valgus, tailors bunion, accessory navicular, tibial crest periostitis, medial and lateral malleolar contusion
Causes:
The forces involved in generating the above-mentioned tissue injuries include ground reaction forces, tangential shearing forces, and a combination of pressure and shear induced by athletic footwear.
Numerous researchers have demonstrated that ground reaction forces can approach or exceed three times body weight in a running athlete. In addition, vertical plantar pressures against the calcaneus and metatarsals are significantly increased in the running athlete as well as special patient populations with foot deformities, i.e., rheumatoid arthritis and diabetes mellitus with neuropathy.
Shearing forces result from forward or sideways momentum of the athlete whether walking, jumping, running, or lunging. Spence and Shields identified four types of dynamic forces that can be associated with running gait: vertical forces, fore and aft shear, lateral shear, and torque. Shearing force on the skin surface of the foot is exacerbated by the type of playing surface, type of footwear, type of insole, and type of sock material. Shearing forces are thought to be more damaging to the feet than ground reactions forces. The combination of abnormal pressure and shear results in the formation of friction blisters in athletes and ulcerations on the feet of patients with diabetes mellitus.
In addition to the abnormal forces generated by the specific movements of the sport, the type of footwear worn by the athlete can generate unique damaging pressure and shear in specific areas of the feet or legs. The following unique forms of athletic footwear and the various locations of potential skin or deep tissue damage are illustrated in the following tables.
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