Tooth-knuckle injury

Last revised by Hamish Smith on 8 Nov 2020

Citation, DOI, disclosures and article data

Citation:

Smith H, Kusel K, Knipe H, et al. Tooth-knuckle injury. Reference article, Radiopaedia.org (Accessed on 19 Apr 2024) https://doi.org/10.53347/rID-58604

DOI:

https://doi.org/10.53347/rID-58604

Permalink:

https://radiopaedia.org/articles/58604

rID:

58604

Article created:

27 Feb 2018, Hamish Smith

Disclosures:

At the time the article was created Hamish Smith had no recorded disclosures.

View Hamish Smith's current disclosures

Last revised:

8 Nov 2020, Hamish Smith

Disclosures:

At the time the article was last revised Hamish Smith had no recorded disclosures.

View Hamish Smith's current disclosures

Revisions:

6 times, by 4 contributors - see full revision history and disclosures

Systems:

Musculoskeletal, Trauma

Tags:

septic arthritis, osteomyelitis, trauma, hand, amputation, cases

Synonyms:

Fight bite injury
Closed fist injury
Clenched fist injury

Tooth-knuckle injuries are sustained when the clenched fist of a patient strikes the teeth of an opponent.

The injury most commonly involves the dominant hand (~65%) and the region over the metacarpophalangeal joint (~80%) ¹. Patients who present initially are more likely to have fractures and dislocations. Patients who delay presentation are more likely to present with the infective complications of this injury such as cellulitis, septic arthritis, septic tenosynovitis or osteomyelitis ². The average time delay from injury to presentation is 3 to 6 days ¹. Pain, swelling, erythema, an open discharging wound and reduced range of motion are common findings. Other trauma such as craniofacial and dental should be considered due to the nature of how the injury is sustained.

Pathology

Skin laceration sustained during the impact of the knuckle on the tooth permits the entrance of pathogens into the subcutaneous tissues ². Damage to deeper structures is also common such as the extensor tendon, joint capsule, cartilage and bone occurring in up to 75% of cases ¹. Damage to these structures and infection tracking into a deep cavity is a major concern. When the hand is relaxed, the proximal movement of the skin and the extensor tendon relative to the deeper tissues creates the possibility of sealing pathogens in a potential space with an anaerobic environment ².

The pathogens most commonly associated with the injury include: Staphylococcus aureus, Streptococcus viridans, Eikenella corrodens and Escherichia coli ¹.

Radiographic features

The injury may produce findings visible on plain radiograph such as dislocations, fractures (e.g. Boxer fracture), swelling of the subcutaneous tissues and the presence of foreign bodies (teeth or teeth fragments).

Septic arthritis may produce joint space narrowing and osteomyelitis may produce bone erosion and periostitis ³.

Treatment and prognosis

Treatment usually consists of broad-spectrum antibiotics active against Gram-negative and positive bacteria and anaerobes, debridement and washout of the wound, post-surgical hand elevation and ongoing hand therapy ⁴. Poor functional outcomes are common (in up to 65%) and chronic osteomyelitis is also possible making amputation necessary (reportedly in as many as 18% of patients) ^5,6. However, in one Australian study, the rate of amputation was found to be reassuringly low at 0% ⁷.

Delays in presentation, injuries over the proximal interphalangeal joint and deeply penetrating wounds are associated with more serious complications like septic arthritis, osteomyelitis and amputation ¹.