Prevalence of the extensor digitorum, extensor digiti minimi and extensor indicis tendons and their variations

The impact of socioeconomic status on hand injury severity

Socioeconomic status (SES) is an important factor affecting different aspects of human health, including self-care and healthcare service use. The relation between SES and hand injury severity is not well defined; therefore, the present study aimed to investigate the relation between SES and hand injury severity. This cross-sectional descriptive and analytical study included 215 patients with hand injury. Demographic, clinical, and SES-related factors were collected by questionnaire. Injury severity was assessed on Hand Injury Severity Score (HISS). Statistical analysis used the Student t-test, chi-square test and a multinomial regression model to calculate the odds ratio (OR) of each predictive factor. Mean age was 38.02 ± 13.49 years (range, 12-80 years). 73.5% of the participants were men. Patients with low SES were significantly more likely to develop severe hand injury (OR = 5.25 and 9.25 at HISS levels 3 and 4, respectively). In addition, there was a significant association between being born in rural areas and severe (HISS level 3, OR = 2.63) or major (HISS level 4, OR = 2.63) hand injury. Also, major (HISS level 4) hand injuries were significantly more prevalent in patients living in rural areas (OR = 4.23) and those injured in road accidents (OR = 1.98) or practicing sports (OR = 3.51). The study concluded that patients with low SES were 5-10-fold more likely to suffer from severe and major hand injuries, and thus provided valuable information for Iranian policymakers to take preventive measures for hand injuries. It is recommended to improve postoperative care in patients with low SES who underwent hand surgery, take the necessary measures to decrease the incidence of road accident injuries, facilitate early referral of patients with hand injury to trauma centers, and improve postoperative follow-up until full recovery. LEVEL OF EVIDENCE: III.

Anatomic relationship of extensor indicis propius and extensor digitorum communis: Implications for tendon transfer

BACKGROUND

The extensor indicis proprius (EIP) tendon is a frequently used donor for a variety of tendon transfers, most commonly for reconstruction of the extensor pollicis longus (EPL). EIP is known to have frequent anatomic variants including split tendons and variations in tendon arrangement.

AIM

To characterize the anatomy of the EIP at the level of the extensor retinaculum, where tendon harvest is often performed, and share our preferred technique for EIP to EPL transfer.

METHODS

Twenty-nine fresh-frozen cadaveric forearms without history of forearm or hand injury or surgery were dissected. Tendon circumference and relationship of the EIP and extensor digitorum communis to the index (EDCI) at the metacarpophalangeal (MCP) joint and the distal extensor retinaculum were recorded. Distance from the distal extensor retinaculum to the EIP myotendinous junction was measured.

RESULTS

EIP was ulnar to the EDCI in 96.5% of specimens (28/29) at the distal edge of the extensor retinaculum. In the remaining specimen, EIP was volar to EDCI. Tendon circumference at the distal extensor retinaculum averaged (9.3 mm ± 1.7 mm) for EDCI and 11.1 mm (± 2.7 mm) for EIP (P = 0.0010). The tendon circumference at the index MCP joint averaged 11.0 mm (± 1.7 mm) for EDCI and 10.6 mm (± 2.1 mm) for EIP (P = 0.33). EIP had a greater circumference in 76% (22/29) of specimens at the distal extensor retinaculum whereas EIP had a greater circumference in only 31% (9/29) of specimens at the MCP joint.

CONCLUSION

The EIP tendon is frequently ulnar to and greater in circumference than the EDCI at the distal extensor retinaculum, which can be taken into consideration for tendon transfers involving EIP.

Bilateral anatomical variations in the extensor compartment of forearm and hand

An unusual variation of the extensor muscles was found during the routine dissection of the posterior compartment of the forearm. The left forearm presented an extensor medii proprius muscle, the tendon of which had an unusual trajectory. It passed through the second extensor compartment between the tendons of the extensor carpi radialis longus and extensor carpi radialis brevis muscles. The right forearm presented two muscles for the index finger: one, the extensor indicis et medius communis, the tendon of which was split into three tendons, one radial and one ulnar for the index finger and a rudimentary tendon for the middle finger; the second muscle for the index finger had an unusual origin, common with the extensor carpi radialis brevis, and its tendon ran superficially to the tendon of the extensor indicis et medius communis muscle. Knowledge goes tendon variations can be significant not only for clinicians to misdiagnose a debilitating wrist extensor pain syndrome but also for surgeons to avoid iatrogenic injuries in hand surgery.