Trapeziometacarpal Ligaments Biomechanical Study: Implications in Arthroscopy

Mireia Esplugas, MD;  Alex Lluch-Bergada, MD; Nathalie Mobargha, MD, PhD;

Manuel Llusa-Perez, MD, PhD;  Elisabet Hagert, MD, PhD;  Marc Garcia-Elias, MD, PhD

Abstract

Purpose In the presence of early osteoarthritis, changes to the trapeziometacarpal joint (TMJ) often result in pain and is associated with joint instability and a tendency of dorsoradial subluxation. In these instances, arthroscopy may be indicated to: (1) assess the extent of cartilage disease and the laxity of ligaments and to (2) treat TMJ instability. The purpose of our study was to biomechanically analyze which ligaments are the primary stabilizers of the TMJ.

Methods Overall, 11 fresh-frozen human cadaver specimens were dissected and attached to a testing device with the thumb positioned in neutral abduction, neutral flexion, and neutral opposition. The four extrinsic and five intrinsic muscle tendons acting on the TMJ were simultaneously loaded with weights proportional to their physiological cross-sectional area. The dorsal, volar, and ulnar groups of ligaments were dissected. A motion-tracking device, FasTrak (Polhemus Inc., Colchester, VT), was used to study the spatial position of the base of the first metacarpal bone (MC1), before and after random sectioning of each of the ligaments. Statistical analysis of the MC1 translation along the transverse XY plane was performed using one-way analysis of variance and a paired t-test, with a significance level of p < 0.05.

Results After isolated sectioning of the volar or the ulnar ligaments, the MC1 moved dorsoradially with an average of 0.150 mm (standard deviation [SD]: 0.072) and 0.064 mm (SD: 0.301), respectively. By contrast, the destabilization of the MC1 after sectioning of the dorsal ligaments was substantially larger (0.523 mm; SD: 0.0512; p = 0.004).

Conclusions Sectioning of the dorsal ligament group resulted in the greatest dorsoradial translation of the MC1. Consequently, the dorsal ligaments may be regarded as the primary TMJ stabilizers.

Clinical Relevance This study suggests that stabilizing arthroscopic shrinkage of the TMJ should be targeted toward the dorsal TMJ ligaments

https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-0036-1581052

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La artroscopia de mano y muñeca

Hace unas semanas tuve la oportunidad de enseñar cómo realizar una artroscopia de muñeca a compañeros neófitos en el tema… Confío que les fuera provechoso… pero sobretodo fue provechoso para mi: recordé mis inicios: cuando no conseguía que se viera nada reconocible, cuando se me salía la cámara de sitio a cada movimiento, cuando no conseguía triangular cámara e instrumental, cuando sólo miraba la cámara sin echarle nunca un vistazo a la muñeca para orientarme, cuando forzaba el material porque no conseguía llegar donde pretendía, cuando me ruborizaba tras ver el estado en que dejaba el cartílago a mi paso,…. Es una técnica difícil, exigente, meticulosa, no exenta de complicaciones.

Existen múltiples cursos en cadáver para aprenderla y para perfeccionarla. Nuestra buena práctica exige iniciarse en ellos y no indicar o realizar una en el paciente hasta que no la dominemos: aunque no sea una gran articulación y no sea de carga, visto cómo quedan los cadáveres tras los cursos, seria inadmisible pensar que con nociones básicas se puede empezar en la práctica clínica.