The Unstable Metacarpophalangeal Joint in Rheumatoid Arthritis: Anatomy, Pathomechanics, and Physical Rehabilitation Considerations

Abstract

The metacarpophalangeal (MCP) joints bestow important strength to the longitudinal and transverse arch systems of the hand. In addition, these joints guide active movements of the fingers in 2 degrees of freedom, while allowing sufficient laxity for passive accessory motions. Both stability and mobility functions are attained in the healthy hand by a complex interaction among the muscles and the joints' periarticular connective tissues. Rheumatoid arthritis (RA) often causes destruction of the MCP joints' connective tissues, which leads to weakness of the tissues and an imbalance of active and passive forces, and subsequently, instability, pain, and deformity. The 2 most common deformities of the MCP joints associated with RA and instability are palmar subluxation and ulnar ''drift.'' Therapists and physicians often collaborate to treat these conditions through a combination of surgical and nonsurgical interventions. Two of the more conservative nonsurgical interventions typically involve a combination of splinting and education on joint protection. Additional nonsurgical treatment may include the judicious use of exercise and methods for relieving pain and reducing inflammation. Surgical intervention is often indicated when the more conservative treatments fail to arrest the progression of the pain or deformity. Regardless of the specific approach, effective intervention for instability of the MCP joint requires that the clinician possess a sound knowledge of the anatomy and the pathomechanical influences that predispose or cause the instability. This clinical commentary is intended to provide this information, as well as offer treatment guidelines based on our clinical experience. Whenever possible, research will be cited to support clinical interventions. This paper is especially geared to the therapist who may not currently specialize in the treatment of instability of the MCP joint but may require basic information on this important topic. J Orthop Sports Phys Ther 2005;35:502-520.

Ultrasonography of the metacarpophalangeal joints in healthy subjects using an 18 MHz transducer.

“…During the time numerous anatomic and imaging (US, magnetic resonance imaging) studies were performed in order to describe all the structures involved in the functionality of this joint [9,[13][14][15][16][17] and to explain the localization of the lesions in specific parts of the joints [17]. The US appearance of normal MCP joint is largely influenced by the examination techniques: the perpendicular examination in order to avoid anisotropy, the correct setting for grey-scale of the US machine, the use of high frequency transducers, the quantity of gel (transducer not in contact with the skin), the joint position [18], the quality of images acquisition, etc.…”

A new concept of orthosis for correcting fingers ulnar deviation

“…Regarding patient's opinions about the current design orthotics devices for ulnar deviation of the fingers correction that is indicated in the service, discomfort and loss of function are the problems encountered in current treatment, what is also stated by Bielefeld and Neumann (2005).…”

Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology

“…(Bielefeld and Neumann, 2005). During inflammation subsequent to RA, the joint capsules are loosened and the collateral ligaments are The key anatomical changes associated with ulnar drift are: the phalanges shift and rotate towards the ulna, the carpal bones deviate towards the radius, and the metacarpals rotate towards the radius.…”

“…The most recognizable change is the fingers rotating towards the ulna. The carpus bones deviate in the radial direction, and the metacarpals rotate radially (Bielefeld and Neumann, 2005;Resnick, 1976;Shapiro, 1968;Shapiro et al, 1971;Taleisnik, 1979;van Vugt et al, 1999). Also, it has been noticed that the transverse arch in the hand flattens (Seyfried, 1969).…”