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BACKGROUND: Distal-ulna stump (DUS) instability often occurs when performing a distal radioulnar joint (DRUJ) arthroplasty. Recent studies suggest that the distal interosseous membrane (DIOM) reinforces the triangular fibrocartilage complex, providing additional stability to the DRUJ. The aim of this study was to determine whether the DIOM stabilizes the ulnar stump. METHODS: Twenty fresh-frozen random forearms were dissected. The presence of a distal oblique bundle (DOB) was recorded and measured. The radius was fixed to a vise and the ulna kept free. The DRUJ was fixed with a lag screw. A bone slice was removed by transverse ulna osteotomies 10 and 15 mm proximal to the DRUJ. A 10-N force was applied to the ulna in dorsal and volar directions. Displacements were measured. The DIOM was then transected, and maneuvers and measurements were repeated and compared. RESULTS: A distinct distal membrane was present in 70% and a cord-like DOB in 30%. The mean length was 29 mm. Its origin was proximal to the sigmoid notch; its insertion was on the distal third of the ulna, at its lateral border. This attachment is comprised between 39 and 48 mm proximal to the ulnocarpal joint. Initial displacements averaged 22 mm dorsally and 13 mm volarly. After DIOM transection, ulnar translocation increased to 31 mm dorsally and 19 mm volarly. CONCLUSION: In DRUJ arthroplasties, the DIOM does not appear to be a stabilizer of the DUS beneath a useful threshold. Its retaining effect occurs only after an initial 22-mm dorsal displacement, which we consider not clinically admissible. Therefore, in DRUJ arthroplasties, some augmentation might be advisable.

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Background: The distal half of the hypothenar eminence (HE) skin vascularization has been extensively investigated. Different flaps have been described based on these arteries. Similarly, the vascularization of the proximal half of HE has also been investigated, although to a lesser extent. The aim of this paper is to determine, in a cadaver sample, the anatomy of the hypothenar cutaneous branches in their proximal half. Methods: In all, 20 adult, red-colored-latex-injected hands were studied. Dissections were performed with a 4X to 10X magnification. Cutaneous branches in the proximal half of the HE were found. Their variants were studied, and they were classified into different types according to their relationships. Results: A cutaneous branch of the deep palmar artery (CBDPA) was identified. It was located in the subcutaneous cellular tissue thickness in the proximal half of the HE. Moreover, it presented 3 anatomical variants, classified according to its relationships with the superficial ulnar nerve branch (SUN). Type 1 variant: the CBDPA and the PDA ran in front of the SUN (60% of cases). Type 2: the CBDPA and the DPA ran behind the SUN (30% of cases). Type 3: the CBDPA ran in front of the SUN while the DPA ran behind it (10% of cases). Conclusion: There is a CBDPA which is the HE proximal half main cutaneous branch. Although it presented several variants, its existence is constant, making it possible to use it as pedicle for proximal hypothenar flaps.

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The abductor digiti quinti flap for thumb hypoplasia has been used in its muscular variant as musculocutaneous flap. Several authors have reported myocutaneous branches in the proximal hypothenar region which would vascularize the skin segment covering the hypothenar muscles. Nevertheless, the presence of a cutaneous branch deep palmar artery (CBDPA) vascularizing the proximal hypothenar territory and possibly responsible for the proximal hypothenar cutaneous vascularization was reported. In this paper, a fasciocutaneous hypothenar flap was designed, based on the CBDPA, transposed to the wrist anterior region for the treatment of a post burn contracture which was limiting the wrist extension. Its viability was assessed. The flap had a lozenge-shaped design from the cutaneous fold of the wrist to the fifth metacarpophalangeal joint over the abductor digiti quinti muscle. It was dissected in the fasciocutaneous plane to a width of 20 mm. The adipose tissue zone 10 mm distal to the pisiform was preserved, as well as the ulnar nerve sensory branch crossing the flap longitudinally. The flap was transposed to the anterior fold of the wrist. Neither the flap nor the donor site underwent complications. The patient improved wrist extension without referring any discomfort. Sensitivity was 8 mm 2 months after surgery compared to 6 mm within the preoperative period. In conclusion, it is possible to develop a proximal fasciocutaneous hypothenar flap based on CBDPA involving the proximal and distal hypothenar territory.

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BACKGROUND: The medial coracoclavicular ligament (MCCL), is a structure that shows defined morphologic and histologic features. However, little attention has been paid to the MCCL to date. This study was conducted to (1) determine whether the MCCL is a constant structure, (2) analyze its mechanical properties, and (3) determine its possible role in acromioclavicular (AC) stability. METHODS: AC joints, lateral coracoclavicular ligaments (LCCLs; conoid and trapezoid), and MCCLs were dissected in 30 fresh frozen upper limbs. In 6 of these specimens, we performed a sequential sectioning following the aforementioned order. A 20-N cephalad force was applied to the lateral clavicle at each step, recording the AC distance and coracoclavicular space and their variation. In 6 other specimens, we evaluated the anteroposterior motion of the clavicle following the MCCL section. Biomechanical testing was performed in 8 specimens, comparing the resistance of the MCCL to the LCCLs. RESULTS: The MCCL in all of the specimens featured a sharp-edge bundle stretching from the coracoid process to the clavicle and subclavius sheath. It showed ligament-like mechanical properties although less tensile resistance than the LCCLs. Once the AC and LCCLs were sectioned, transection of the MCCL determined a significant increase in both cephalad and posterior displacement. CONCLUSION: The MCCL is a constant structure with the mechanical behavior of a ligament. It may act as the last container of the coracoclavicular space both in cephalad and posterior directions, precluding additional displacement in the absence of the LCCLs.

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Introducción: El ligamento de Caldani o coracoclavicular medial ha sido estudiado anatómicamente, pero no hemos hallado mención alguna sobre su identificación imagenológica. El objetivo de este trabajo es presentar una técnica original de resonancia magnética que hemos desarrollado para identificarlo, y describir las imágenes correspondientes. Materiales y Métodos: Se incluyó a siete voluntarios sin patología de hombro conocida. Se utilizó un resonador magnético Philips Ingenia de una intensidad de campo magnético de 1.5 T, versión 4.1, diámetro de Gantry de 70 cm, bobina específica para hombro de 8 canales con imágenes de alta resolución. Se realizaron las secuencias de búsqueda del ligamento en tres planos. Resultados: El ligamento coracoclavicular medial fue identificado en todos los casos, se extendía oblicuamente desde la apófisis coracoides hasta la clavícula, lo que coincide con las descripciones de la bibliografía anatómica consultada. Tuvo una señal hipointensa en todas las secuencias, lo que indica el poco espacio entre fibras y que corresponde a tejido colágeno compacto. Su longitud promedio fue de 41,15 mm (rango 34-47 mm, desviación estándar 4,40). El espesor promedio fue de 2,11 mm (rango 1,3-3,2 mm, desviación estándar 0,66). Conclusiones: El ligamento coracoclavicular medial se puede observar en imágenes de resonancia magnética mediante la técnica original que describimos. La capacidad de localizarlo y observarlo con este estudio por imágenes abre las puertas a futuras investigaciones sobre su posible papel no solo en las compresiones neurovasculares, sino también en las lesiones traumáticas acromioclaviculares, especialmente en las de tipo V de Rockwood. Nivel de Evidencia: II

Introduction: Although Caldani´s ligament or medial coraco-clavicular ligament has been anatomically studied, we have not found any publication regarding its identification in imaging studies. The aim of this research is to present an original technique to locate the medial coraco-clavicular ligament on magnetic resonance imaging, as well as to describe the pertinent findings. Methods: Seven volunteers without any known shoulder pathology were studied by means of this original protocol. A Philips Ingenia magnetic resonance equipment was used, with a magnetic field intensity of 1,5 T, Gantry diameter: 70 cm, and an 8-channel coil for shoulder study. The sequences to locate the ligament were performed in three planes. Results: This ligament was observed in all cases. Its arrangement was similar to that described in previous anatomical studies. Its origin was at the coracoid process, with an oblique path to reach its insertion at the clavicle. The mean length was 41.14 (range 34-47 mm, standard deviation 4.40). The mean thickness was 2.11 mm (range 1.3-3.2 mm, standard deviation: 0.66). Conclusions: The medial coraco-clavicular ligament can be observed in magnetic resonance images using this original procedure. The ability to display this ligament in magnetic resonance images allows for future investigations on its possible role in both thoracic outlet syndrome and traumatic acromioclavicular dislocations, especially the Rockwood type V. Level of Evidence: II

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