Quantitative anatomy of the extensor digiti minimi muscle in the growing human fetus.

Introduction Age-specific reference intervals for the extensor digiti minimi muscle (EDMM) in the human fetus may be relevant in the detailed evaluation of the musculoskeletal systems with potential relevant aspects for surgical treatment. The aim of the study was to examine the age-specific reference intervals and growth dynamics of the EDMM in relation to its length, width, projection surface area and volume. Material and methods The examined material included 70 human formalin-fixed fetuses of both sexes (37♀, 33♂) aged from 17 to 29 weeks. With the use of anatomical dissection every EDMM was visualized, recorded in a form of JPG formats and analyzed by the digital image analysis system and statistical methods. Results No variability of the EDMM was found. All the morphometric parameters of the EDMM revealed neither sex nor laterality differences. With fetal age most linear parameters of the EDMM concerning its examined lengths and widths increased in accordance with natural logarithmic functions. The only two exceptions to this referred to the belly width of EDMM measured at its mid-length and the tendon width of EDMM measured proximal to the extensor retinaculum of wrist, which both followed square root functions. The projection surface areas of the EDMM followed natural logarithmic functions, while the volumetric growth of the EDMM was proportionate to fetal age. Conclusions The variability of the EDMM in the human fetus is minimal. The morphometric data of the EDMM represents age-specific reference intervals of clinical significance. Morphometric parameters of the EDMM reveal neither sex nor laterality differences. The EDMM displays three different growth dynamics: from gradual growth deceleration according to both natural logarithmic functions (total length of the muscle and its tendons, belly length, tendon lengths, belly width at its origin, tendon width at its insertion, and projection surface areas) and square root functions (belly width at its mid-length and tendon width in the pre-retinacular segment) to a proportionate growth (total volume).

Anomalous Extensor Digiti Minimi with Multiple Slips and Bulbous Appearance.

The extensor digiti minimi is a muscle in the posterior compartment of the forearm that extends the fifth digit. Variations of the extensor tendons of the hand are common and mostly asymptomatic, however, some may impinge and occupy the narrow dorsal compartments of the wrist causing dorsal wrist pain and impairment of digital movement. Orthopedic literature illustrates how frequent anomalies of the extensor indicis proprius, extensor digitorum brevis manus, and extensor medii proprius occur; however, minimal literature documents a bulbous, multi slip extensor digiti minimi. Within this case, a 30-year-old, right-handed woman with no prior hand trauma presented with recurrent snapping localized to her right fifth digit, causing intermittent pain and an audible "click". This study aims to provide a thorough anatomical description of a rare extensor digit minimi anomaly and a viable option to treat successfully an inflamed, symptomatic extensor retinaculum affecting the extensor digiti minimi.

Attritional Extensor Digiti Minimi Tendon Rupture Associated With a Distal Ulna Fracture.

Attritional extensor tendon ruptures are common in the setting of arthritis but, to our knowledge, have never previously been reported in the setting of a distal ulna fracture. This case report describes a 56-year-old male patient who sustained a left-hand dog bite resulting in crush injuries to the thumb and ring finger and a minimally displaced distal ulna fracture. The patient initially underwent appropriate surgical intervention for the thumb and finger crush injuries and non-operative management of the distal ulna fracture with splint immobilization. He experienced an extensor digiti minimi tendon (EDM) rupture two and a half weeks post-operatively. Radiographs demonstrated interval distal ulna fracture displacement with a prominent dorsal spike and absence of arthritis. He subsequently underwent distal ulna open reduction internal fixation and an extensor indicis proprius (EIP) to EDM tendon transfer. This case demonstrates a novel complication following non-operative management of a distal ulna fracture in which the prominent dorsal distal ulna resulted in direct irritation to the extensor tendon and subsequent attritional extensor tendon rupture. This potential complication should be considered in determining appropriate treatment for distal ulna fractures.

New Insights into Boxer's Knuckle Injury of the Little Finger.

BACKGROUND: The original description of boxer's knuckle injury of the fifth ray mentions that the injury occurs between the extensor digitorum communis (EDC) and the extensor digiti minimi (EDM). Subsequent reports claim similar findings. Anatomical studies show that the EDC of the fifth ray is absent in most patients, while the EDM is generally composed of two slips. We present a modification of the current description of boxer's knuckle injury of the little finger based on the correlation between advanced preoperative 3D imaging and intraoperative findings. METHODS: Five patients were investigated preoperatively using high-resolution ultrasound and 3D tendon reconstruction-based MR arthrography. Surgical exploration identified the lesion site relative to the EDM and EDC. RESULTS: All patients had two slips of the EDM and no EDC to the fifth ray. The injury appeared as a longitudinal tear of the EDM between its two slips. The mean gap was 7.8 mm (range 4.5-10 mm) on the pathological side vs. 1.3 mm (range 1-2 mm) on the healthy contralateral side. CONCLUSIONS: We believe that previous descriptions of boxer's knuckle of the fifth ray are inaccurate. High-resolution ultrasound and 3D reconstructions based on MR arthrography are reliable diagnostic tools allowing to locate the injury with precision.

Is It Possible to Perform Fifth Carpometacarpal Joint Arthroscopy? Cadaveric Study on Its Feasibility, Safety, and Potential Hazards in Portal Creation.

Background Fifth carpometacarpal joint (CMCJ) fracture dislocation is a relatively rare injury and most will require operative treatment because of its unstable nature. Improper reduction and fixation lead to joint surface destruction, pain, and reduced grasping power. Intra-articular fragment reduction is often obscured by dorsally displaced ulnar fragment. Therefore, fifth CMCJ arthroscopy can be advantageous in assisting intra-articular fragment reduction. However, there is no detailed description of the portal landmarks or portals' relationship with adjacent important structures in the literature. Purposes To explore the feasibility and safety of fifth CMCJ arthroscopy, locations of the portals are examined in cadaveric hand specimens. Their proximity to important anatomical structures such as dorsal cutaneous branch of ulnar nerve (DCBUN), ring finger and little finger extensor digitorum communis (EDC), and extensor digiti minimi (EDM) is measured. Methods Fifth CMCJ arthroscopy is performed on 11 cadaveric hand specimens by specialist-level surgeon. The portals are marked and portal positions are further confirmed under the fluoroscopy. Then the cadaveric specimens were undergone anatomical dissection by specialist-level surgeon. During dissection, the spatial relationship between the portal positions and DCBUN, EDC to ring finger and little finger, and EDM is identified. The distance between the portals and the above important structures was measured in millimeters. Results DCBUN was consistently found between fourth metacarpohamate (4-MH) and fifth metacarpohamate (5-MH) portals, with it being closer to the latter (mean distance, 2.03 mm; range, 0-4.43 mm; standard deviation [SD], 1.09 mm). The closest tendon for 4-MH portal is ring finger EDC (mean distance, 2.65 mm; range, 0-5.89 mm; SD, 1.78 mm), while 5-MH portal and accessory portal were closest to EDC (mean distance, 1.88 mm; range, 0-3.69 mm; SD, 1.25 mm) and EDM (mean distance, 7.79 mm; range, 6.63-10.72 mm; SD, 1.49 mm), respectively. During the process of specimen dissection, we found no damage to the above structures after portal introduction. Conclusion The above findings support the use of fifth CMCJ arthroscopy, which can be used for assisted reduction in fifth metacarpal base fracture dislocation and hamate body fracture. Gentle soft tissue spreading technique during portal creation prevents injury to the important structure surrounding the portals. Level of evidence This is a Level V study.

Ulnar-sided wrist pain due to radial bifurcation of the extensor digiti minimi tendon: A case report and literature review.

Stenosing tenosynovitis of the extensor digiti minimi (EDM) without trauma is very rare. We report a 21-year-old woman who presented with dorsoulnar wrist pain during palmar wrist flexion and soft tissue mass at the site of pain. Ultrasonography and magnetic resonance imaging showed a round mass radial to the EDM tendon. Conservative treatment for 3 months failed to improve the patient's pain levels. Intraoperative findings revealed smaller radial slip of the EDM tendon, and bifurcation of these was under the distal portion of the extensor retinaculum (ER). Surgical release of the ER, resection of the smaller slip of the EDM tendon, and tenosynovectomy were performed. Histological examination showed tenosynovitis. At the final follow-up 1 year postoperatively, she was asymptomatic. A literature review suggested that stenosing tenosynovitis of the EDM tendon might be caused by frequent use of the hand with a background history of bifurcation of the EDM tendon.

Extensor digiti minimi muscular flap: From a clinical case to an anatomical study.

We present a case report of a failed posterior interosseous flap with distal pedicle rescued by an extensor digiti minimi (EDM) island pedicle flap supplied by the posterior interosseous artery (PIOA) in reverse flow to cover a soft tissue defect in the hand of a 25-year-old man. We subsequently performed an anatomical study on 5 cadaver limbs to determine the EDM muscle's vascularization: it was segmental, multiple and came from the PIOA. The rotation arc reached the dorsal side of the metacarpophalangeal (MCP) joints, as well as the distal part of the thumb. The indications selected are the same as those of the distal pedicle flap: defect on dorsal side of the hand and MCP joints, coverage of carpal tunnel, failure of posterior interosseous flap. This study describes a new flap and adds to our understanding of the EDM muscle's vascularization.