Carpal Tunnel Syndrome (CTS) has become the #1 industrial problem in the United States. Current rationale for the mechanism and etiology of CTS do not fully explain the epidemic we are now faced with and needs to be further examined. Traditional approaches to bracing for CTS fail to incorporate evolving concepts of soft tissue rehabilitation and thereby limit results. The M BRACE Radi-ul Carpression Angle™ offers an alternative support for the treatment and prevention of CTS.
The carpal tunnel is a conduit for the median nerve and nine tendons that pass from the forearm to the hand. The strength and stability of that passageway is maintained almost exclusively by ligamentous integrity, as there are no muscles at the wrist. Thus, the stability of the carpal tunnel is at risk. The traverse ligaments offer little support to the carpal tunnel and some even believe it to be a vestigial structure. (19) Repetitive use of the wrist during the course of the day naturally promotes laxity of the supportive ligaments. Lacking the compensating muscles to stabilize, the vulnerable carpal tunnel configuration will be altered. The proper juxtaposition of the radius and ulna is contingent upon a stable interosseous ligament and, more importantly, a structurally sound articular capsule. (3) The latter commonly displays significant damage and deterioration on MRI studies of confirmed CTS cases. The ensuing functional disrelationship results in a structural alteration that is best described as a decrease or flattening of the normally deep "U" shape of the carpal tunnel.
Anatomically, the carpal bones are wider at the posterior surface than the anterior, with the exception of the lunate bone. (3) This wedging orientation forms the arch shape of the carpal tunnel, held in place by the ligaments pulling in opposite directions. The lunate bone functions as the structural "linch-pin" much the same way as a Roman arch is stable against gravity. Ligamentous tension is the greatest on the palm side maintaining a vector force opposed to the structural shape of the carpal bones. Directional pull of the ligaments connecting the radius and ulna to the carpal bones are of major concern. The radiolunate and the ulnolunate ligaments form a three-point attachment with the radius and ulna as the base and the lunate bone forming the peak of the triangle. The carpal tunnel is formed from a combination of the shapes of the wider posterior surfaces of the carpal bones and ligamentous tension.
Providing that ligamentous integrity is maintained, the configuration of the deep "U" shape of the carpal tunnel is sustained. Mechanical deformation of the carpal tunnel occurs initially from fatigue of the intercarpal, interosseous and articular capsule ligaments. This allows the radius and ulna to separate, spreading the base of the triangular orientation formed by the radiolunate and ulnolunate ligaments. Separations of the radius and ulna from the midline will result in a migration of the lunate bone to the volar surface, protruding into the carpal tunnel itself and diminishing the available space within.
This distortion of the carpal tunnel, when present over an extended period of time, will cause compression, irritation and inflammation of the soft tissue structures within, especially the median nerve. The subsequent symptoms of CTS directly relate to the use of the wrist after the presence of this functional disrelationship, and the mechanical, chemical and metabolic aberrations described.
If a patient's condition is allowed to progress to the state of diseased tissue, conservative care may now be futile. (2,12,18) Effective results would best be obtained if the situations that created the condition are identified and corrected, and as always, swift diagnosis and treatment would be essential.
Proper splinting of the wrist for CTS should incorporate state of the art concepts of tissue rehabilitation.
Elastic wrist straps should also be used rarely. These compress the radius and ulna together, limiting proper translation upon flexion and extension, and expand the anterior to posterior dimension of the wrist by increasing intratunnel pressure. (15) The median nerve is thereby further compressed. Additionally, the vector forces of the elastic band are 360 degrees, directly pressuring the already protruding open anterior portion, worsening the symptoms the longer it is used. Finally, elastic bands place an unnatural pressure on the articular capsule surfaces. This extra pressure accelerates the degeneration process as a result of the piezo-electric effects on bones and joints.
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