Narrative review: Extensor hood injuries in elite boxers

Why this study matters

Hand injuries are the most common type of injury in amateur and professional boxers. The extensor hood is a sheet of tissue over the knuckle that holds the finger-straightening tendon in place. The article reports that injuries to it make up 16% of hand and wrist injuries in boxers, and that hood tears lead to an average of 110 days lost from the sport. Surgery is often needed. The authors say little is known about its results in these athletes, including whether they return to boxing. Most earlier reports were small series of fewer than 15 patients with short follow-up.

What the researchers did

The authors call this a prospectively designed cohort study of one surgeon’s experience. It included consecutive elite boxers, meaning professionals or international-level amateurs, who had surgery for a suspected extensor hood injury between 2008 and 2021. Each had a painful, tender knuckle that had affected boxing and competing. Information was recorded in a patient database as care took place. Surgery was done on 57 fingers in 45 patients. The mean age was 24 years (range 16 to 35), and the article reports that 95% were male.

The diagnosis was mostly made from the history and examination, with scans kept for unclear cases. The surgeon made a curved cut beside the knuckle and looked for a tear in the hood and in the joint capsule beneath it. The hood was stitched with the knuckle bent. Rehabilitation was supervised by a therapist, with a gradual return to light impact between 8 and 12 weeks. The outcomes were knuckle bend, return to boxing and its level, complications and further surgery. Return to boxing was checked at follow-up appointments, through medical staff and from BoxRec, a website that records boxing contests.

What they found

The middle finger was injured most often (35 of 57 fingers, 61%), followed by the index finger (15, 26%). Scans had been done before surgery for 22 fingers (39%). In two cases a scan showed a tear that surgery did not find, and in three a normal scan missed one. At surgery, a hood tear was found in 42 fingers. The other 15 (26%) had no tear, but in all of them the tendon had to be freed from the capsule it had stuck to. A tear in the joint capsule was found in 16 fingers (28%). A pseudobursa, a sac-like pocket of tissue that the authors say often lies over a tear, was found in 20 (35%). One patient had damage to the joint cartilage.

Results after surgery cover 56 fingers in 44 patients, because one patient did not complete rehabilitation. Mean follow-up was 4.1 years (range 0.1 to 10.9). The mean bend at the knuckle was 90 degrees (range 75 to 95). Of the 44 patients, 43 returned to the same level of boxing, at a mean of 8 months (range 1 to 24). The one who did not return was the patient with cartilage damage. One finger needed a second operation because the repair tore again six months later. That patient had received a steroid injection into the knuckle six weeks before surgery, and the authors suggest this may have contributed. The authors report no other complications or reoperations.

Strengths and limits

The authors describe this as a large series of elite boxers whose contests could be tracked through BoxRec. Results are given for all patients, whatever their length of follow-up.

There was no comparison group, so the study cannot show how surgery compares with other treatment. The article gives its level of evidence as IV. The authors say one experienced surgeon’s results may not apply to all surgeons. The surgeon’s protocol changed over the 13 years, and some patients had short follow-up. No validated patient-reported outcome measures were available, and grip and pinch strength were not measured. The article sometimes counts fingers and sometimes patients. It gives capsular tears as 28% in the results and 32% in the discussion.

What it adds to research on fighter health

The article sets out how one surgeon diagnosed, repaired and rehabilitated extensor hood injuries in elite boxers, and what was found inside the knuckle. It reports that 43 of 44 patients returned to boxing at their previous level. It also records that about a quarter of the operated fingers had no hood tear, and that scans and surgical findings did not always agree. The authors compare their series with an earlier United States series of 44 procedures. In that series capsular tears were more frequent and most tears were on the radial side, the side nearest the thumb. The authors suggest that differences in training between countries, or advances in injury prevention, may explain this.