The effect of individual isometric muscle loading on the alignment of the base of the thumb metacarpal: a cadaveric study

Abstract

Stability of the thumb carpometacarpal joint relies upon equilibrium between its ligaments, muscular support and joint congruity. We wanted to identify the muscles important in preventing or increasing dorsoradial subluxation of this joint. In ten cadaveric hands, a Fastrak® motion tracking device was used to assess the effects of individual isometric muscle loading on the base of the thumb metacarpal relative to the radius and to the base of the middle finger metacarpal. We found that the first dorsal interosseous muscle caused the least dorsoradial translation and highest distal migration of the base of the first metacarpal, whereas abductor pollicis longus was the primary destabilizer, increasing dorsoradial misalignment. The findings show different impacts of these muscles on joint alignment and stability, which suggests that treatment should be targeted to enhance the action of the primary stabilizing muscle, the first dorsal interosseous muscle.

APL Distal Insertion Variability: Cadaveric Variation in Abductor Pollicis Longus Accessory Slip Insertion Site

“…Dobrowolski M et al . APL Distal Insertion Variability : A Cadaveric Study muscle's plane of function but rather in a plane that is the sum of the force vectors of several contributing muscles [12] .…”

Necessity of Immobilizing the Metacarpophalangeal Joint in Carpometacarpal Osteoarthritis: Short-term Effect

“…According to Mobargha et al, the muscles supporting the thumb CMC joint serve as both stabilizers and destabilizers to the joint. 15 Consequently, these thumb muscles impact the stability of the thumb and thumb joint alignment and must be taken into consideration when providing an orthosis. Many patients suffering from CMC joint OA may present with MCP joint hyperextension.…”

Efficacy of combined conservative therapies on clinical outcomes in patients with thumb base osteoarthritis: protocol for a randomised, controlled trial (COMBO)

“…Specific attention will be drawn to performing the exercises in a way which prevents collapse (hyperextension) of the first metacarpophalangeal (MCP) joint while maintaining the web space (abduction). These exercises are based on recent evidence which emphasises the importance of proprioceptive exercises and strengthening for the first dorsal interosseous muscles,29 30 while aiming to be functional and similar to movements used for daily tasks. The exercise programme will be visually depicted using images from a website developed by physiotherapists from the New South Wales Department of Health, Sydney, Australia (see online supplementary appendix 2).…”