Background

Knuckle pads are benign, asymptomatic, well-circumscribed, smooth, firm, skin-colored papules, nodules, or plaques, located in the skin over the dorsal aspects of the metacarpophalangeal (MCP) and interphalangeal (IP) joints. A history of repetitive trauma related to sports or occupation is often present.

Garrod first described knuckle pads in the medical literature in 1893,^[1] but knuckle pads have been observed since the Renaissance era. Allison et al shows a photo of Michelangelo's statue of David displaying knuckle pads (Florence, Italy) as well as his statue of Moses (Rome, Italy), Victory (Florence, Italy), and Giuliano de Medici (Rome, Italy).^[2] The name knuckle pad seems to be a misnomer because in most reported cases, lesions occur over the proximal interphalangeal (PIP) joint, not over the knuckles.

Pathophysiology

Knuckle pads may be idiopathic, genetic, acquired as a response to repetitive trauma, or associated with several other acquired conditions.

Epidemiology

Frequency

United States

Knuckle pads are a common occurrence. Measurement of prevalence of knuckle pads is difficult because patients are asymptomatic and do not seek medical attention for them.

International

Knuckle pads were noted in about 9% of subjects in one survey. Patients with Dupuytren contracture are four times as likely as the general population to have knuckle pads.

Race

No racial predilection is associated with knuckle pads.

Sex

Prevalence of knuckle pads is equal for men and women. Even in the presence of Dupuytren contracture, the prevalence of knuckle pads remains equal.

Age

Knuckle pads can present at any age. They have been reported in young children who bite and suck their fingers.^[3] More commonly, knuckle pads are observed in adults older than 40 years.

Prognosis

Little morbidity is associated with knuckle pads. Patients typically are asymptomatic, but some patients experience pain and difficulty with hand functioning, including writing, as a result of their condition. Cosmetic issues drive most patients to seek attention for knuckle pads. Spontaneous resolution can occur, especially if an inciting repetitive injury is identified and eliminated. In most cases, knuckle pads persist indefinitely with little change.