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ESSENTIALS OF DIAGNOSIS

ESSENTIALS OF DIAGNOSIS

  • Bony bump at the base of the big toe.

  • Swelling, redness, or pain at the base of the big toe.

  • Difficulty with shoe wear.

GENERAL CONSIDERATIONS

A bunion is one of the most prevalent foot problems seen by foot and ankle specialists. Bunion is a deformity at the big toe joint with abduction and valgus rotation of the great toe combined with a medially prominent first metatarsal head (Figure E5–1A). Bunions form when there is a disruption of the balance of forces on the tendons that cross the big toe joint. The first metatarsal head is susceptible to external forces due to the fact that it has no muscular insertion. As the big toe deviates in a lateral direction, the adductor hallucis and flexor hallux brevis muscles serve as deforming forces as their pull shifts lateral to the longitudinal axis of the big toe joint. As the deformity continues to progress, the lateral soft tissues become contracted while the medial tissues become attenuated. It is considered to be a progressive deformity.

Figure E5–1.

A: External examination shows deformity of the big toe joint. B: Radiograph is necessary to evaluate the extent of the deformity. (Used, with permission, from M. Dini, DPM.)

There are five types of conditions that can lead to a bunion deformity: (1) arthritic conditions; (2) biomechanical abnormalities; (3) neuromuscular diseases; (4) genetic disorders; and (5) trauma. Abnormal foot mechanics that may contribute to a bunion deformity include equinus contracture and pes planus. Neuromuscular disease that can contribute to a bunion deformity includes cerebral palsy or cerebrovascular accident. Bunions may be associated with certain types of inflammatory arthritic conditions, such as rheumatoid arthritis. Genetic disorders that may lead to ligamentous laxity and subsequent instability leading to bunion deformity include Ehlers-Danlos syndrome, Down syndrome, and Marfan syndrome. Amputation of the second toe may increase the risk of developing a bunion deformity due to the loss of the lateral buttress that the second toe provides the big toe.

Any disorder that results in excessive amount of pronation can predispose a person to bunion development. Therefore, biomechanical control of the foot is particularly important in both the preoperative and postoperative setting. Patients with this deformity often have a significant family history of bunion deformity. Although bunions tend to run in families, it is the foot type that is passed down and not the bunion. The deformity is more prevalent in women, likely caused by wearing narrow footwear. Controversy remains, however, regarding effects of heredity and shoe gear as precursors to bunion deformity.

CLINICAL FINDINGS

A. Symptoms and Signs

Bunions may or may not be ...

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