Surgery: splint – brace – or bandage – Orthopedic bandage – Splint or brace
Reexamination Certificate
2001-11-23
2004-04-20
Lucchesi, Nicholas D. (Department: 3764)
Surgery: splint, brace, or bandage
Orthopedic bandage
Splint or brace
C602S016000
Reexamination Certificate
active
06723061
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to medical therapeutic systems, and deals more particularly with methods and devices for treating and curing functional disorders of the human carpus. More particularly, the present invention provides a splint for providing dynamic pressure to the transverse carpal, volar carpal, and intra-carpal ligaments, in a manner tending to relieve contractures of these ligaments and thus relieve the pain caused thereby.
2. Description of the Related Art
A. General Description of the Condition
Carpal tunnel syndrome (CTS) is a painful condition caused by compression of the median nerve of the forearm. The median nerve and the flexor tendons pass from the forearm to the hand through the wrist canal, or carpal tunnel. The median nerve in particular can be compressed by one or more factors such as a reduction in carpal tunnel volume or swelling of tissues passing through the carpal tunnel. Such compression of the median nerve causes intense pain to the patient, often necessitating extended therapy or surgery to alleviate the problem.
It is commonly believed that CTS is caused by prolonged repetitive activity, such as holding the hand, wrist, and forearm in an awkward position for extended lengths of time while exerting the associated muscles. Prolonged exertion at a keyboard or manual labor are common, but by no means the only, associations with CTS. The direct cause of CTS is believed to be a biomechanical ligament imbalance in the volar carpal ligaments, where the term “volar” indicates a direction towards the palm of the hand as opposed to “dorsal” which indicates a direction towards the back of the hand. Specifically, this biomechanical imbalance of the ligaments is believed to comprise a thickening of the palmer transverse carpal ligament (PTCL, also known as the retinacular ligament), a thickening of the volar intracarpal ligaments, and contraction of an assortment of volar carpal ligaments.
B. Kinematics of the Carpal/Forearm Complex
The flexor muscle tendons of the forearm acting on the wrist, fingers, and thumb volarly exert a collective static force many times greater than the extensor muscle tendons acting dorsally to stabilize these same members. This interaction between the flexor muscles (antagonist) and the extensor muscles (agonist) is termed “cocontraction”. Cocontraction tends to hold the joint in a fixed and stable position. The flexor-to-extensor ratio of these opposing forces is normally four to one. However, work demands often increase this ratio through hypertrophy of the flexor muscle tendon units; this hypertrophy is caused by executing high intensity tasks involving extended duration and which dominantly involve finger, thumb, and wrist function.
The interaction between the carpal ligaments and the flexor and extensor muscles becomes more pronounced with time and intensity of activity. The effect of the volar flexor forces, acting upon the PTCL as a pulley, attenuate the PTCL and apply forces anteriorly and medially. This places traction forces to the ligament ends of the carpus. Each night, while the flexor/extensor muscles are at rest, the volar intracarpal ligaments restore their normal position grossly; however, some minute anteriomedial deformity remains, and slack of the PTCL is concurrently taken up by contractile forces of this and the other ligament(s). Numerous cycles of activity followed by rest develop an established deforming characteristic which is manifested by narrowing the horseshoe ends of the carpal tunnel, which are held in position by a thickening PTCL and other volar carpal ligaments, resulting in a transverse deformity. Simultaneously, the PTCL, acting as a pulley, concentrates the load of the finger and thumb function so that a volar glide is initiated, where volar glide is defined as movement of the carpal metacarpal complex as a unit in a volar direction. This volar glide of the carpal metacarpal complex attenuates the predisposed thin dorsal carpal ligaments (DCL) originating from the distal radial ulna (DRU). Since the volar carpal ligaments collectively become less stressed, they begin to contract, thus encouraging the anteriomedial collapse of the intercarpal spaces simultaneous to a longitudinal deformity.
The long moment arm of the carpal muscle tendon units are only capable of stabilization of the carpus when the muscle tone is within normal limits, i.e. flexor-to-extensor ration of approximately 4 to 1; these forces acting on the carpus in flexion are convergent toward the muscle origin and are regulated by an interplay of antagonists, pulleys, and joint alignment. A variation of one or more serves to simplify convergence towards a direct line to this point of origin and shorten the distance therebetween. This force results in a decreasing biomechanical advantage which is manifested by a volar shift of the axis of the proximal carpal row. This may account for the propensity of patients with CTS to develop odd compensatory behaviors as, for example, flexing the wrist during power grasping, conceivably to account for the change in position of the more volarly placed PTCL. Carpal tunnel volume is further reduced, and any other predisposition will hasten onset of the painful and crippling CTS condition. Thus, the resistance of the PTCL and related volar ligaments which is encountered when returning the carpal metacarpal complex to a neutral position, i.e. dorsal glide, should be indicative of the severity of the condition of carpal tunnel syndrome or the propensity of the subject to incur the condition.
C. Standard Treatment of Carpal Tunnel Syndrome
To date, CTS has been treated with wrist rests, anti-inflammatory medications, cortisone injections, surgery, and static and dynamic wrist splints. Alone or combined, these treatments have met with varying degrees of minimal success. Symptom relief is short lived and compounded by surgical complications. Even after these treatments are applied, the patient's biomechanical configuration remains unchanged or complicated. Reduced grasp strength has been well documented. The obvious solution, i.e. removing the cause of the injury by refraining from the manual labor believed to cause the problem, is not always practical since the cause of the injury is frequently the means by which the patient obtains his or her livelihood. The next best choice, prevention through proper intervention, can be achieved by enlarging the carpal tunnel to maintain adequate space for the median nerve and thus avoid compression. However, the mechanism for correcting this condition long term does not yet exist.
The carpal tunnel can be enlarged by osteopathic manipulation and stretching maneuvers, thereby alleviating compression on the median nerve and resolving CTS. While severe cases may require other treatment, manipulation is effective in the majority of cases and has the advantage of being prophylactic, i.e. a preventative. Optimum resolution of the symptoms requires frequent stretching and the assistance of another person, a physician or therapist to perform the manipulation. There is a need for an appliance which a patient can use to augment treatment by the physician or therapist. It is known from studies of rehabilitated knee joints and elbow joints that the longest period of low force stretching produces the greatest amount of permanent elongation of connective tissue. Ideally, the stretching would be accomplished by means of an appliance which is adjusted by the physician or therapist to provide the appropriate force for stretching, preferably continuously.
The prior art is replete with splint appliances which are designed to reduce CTS pain. One such appliance is described in U.S. Pat. No. 5,417,645, issued to Lemmen, where a carpal splint is provided with an elongated, flexible member having a palmar portion configured to extend from the middle of the forearm, across the volar carpal area, and across the palm to bias the palm in a dorsal direction. It also functions as a reminder of the proper positioning to
Harvey III James F.
Lucchesi Nicholas D.
Pham Huong Q.
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