Biomedical subjects
Publications and source records attributed to L K Chidgey.
This article discusses the joint mechanics and the anatomy of the forearm with respect to understanding instability of the distal radio-ulnar joint. Acute and chronic instability are reviewed, and treatments are discussed.
Following dorsally displaced fractures of the distal radius, the classic position of immobilization is with the wrist flexed and in ulnar deviation. This is not the position of function and entails morbidity in the form of finger stiffness, which may require prolonged rehabilitation. We treated 20 consecutive, comminuted, intraarticular distal radial fractures using a new external fixation system with the wrist in a neutral to extended position, thereby promoting metacarpophalangeal joint flexion by relatively relaxing the finger extensor tendons. Supplemental pin fixation was used in eight cases. Most patients were performing active digital motion on the day of surgery and 95% maintained functional finger motion during treatment. All fractures healed uneventfully. Palmar tilt was restored in 55% of patients in spite of a wrist neutral or extended position. This method of fixing distal radial fractures allows restoration of anatomy while avoiding hand stiffness.
Chronic wrist pain is among the most difficult diagnostic and therapeutic challenges faced by hand surgeons. The causes are often elusive, of long duration, and not uncovered easily by routine diagnostic methods. This article outlines a systematic evaluation of the patient with chronic wrist pain to determine which of many potential conditions is the cause of the wrist pain so an effective therapeutic plan can be formulated.
The collagen arrangement of the triangular fibrocartilage complex was studied in 20 fresh cadaver wrists by means of standard and polarized light microscopy and scanning electron microscopy. The collagen fibres in the articular disk are arranged in undulating sheets oriented at oblique angles to each other. The fibers of the radioulnar ligaments are oriented longitudinally from the radial origin to the ulnar insertion. The origin of the articular disk from the radius is characterized by thick fibers 1 to 2 mm in length radiating from the radius into the articular disk. Five specimens were also injected with india ink. The radioulnar ligaments and the peripheral 15% to 20% of the articular disk are well vascularized, whereas the central 80% of the articular disk is avascular.
Histologic examination of the TFC reveals parallel, longitudinally oriented collagen fibers peripherally, while the more central articular disc is made up of interweaving obliquely oriented sheets of collagen fibers. This suggests a peripheral region experiencing tensile loads between the region of origin from the radius and the area of insertion into the ulna. The fiber orientation in the central region is more compatible with a structure experiencing multidirectional stresses. The articular disc origin from the radius is reinforced by collagen bundles projecting out from the radius for 1 to 2 mm. A large number of traumatic tears are oriented parallel to the radial origin of the TFC and located approximately 1 to 2 mm from the origin site. This corresponds to the junction of the short, radially oriented fibers and the remainder of the articular disc. The inner 80% of the articular disc is avascular, as is its radial attachment. Traumatic tears in this region would have a low healing potential unless some method for introducing additional vascularity was undertaken, such as reattachment through drill holes in the radius, allowing neovascularization of this otherwise avascular region.
External compression was applied to the palmar surface of the wrist over the carpal tunnel in eight healthy volunteer subjects. With the arm in the maximum elevated position, the carpal tunnel pressure was elevated to 50 mm Hg, being continuously monitored by a slit catheter inserted into the carpal canal. Sensory and motor latencies and amplitudes were evaluated at 1-min intervals. When the sensory amplitude decreased by 50% (correlating with subjective sensory changes), the hand was lowered to heart level, still maintaining the carpal tunnel pressure at 50 mm Hg. Nerve conduction velocity and amplitude monitoring continued at 30-s intervals until complete sensory block. Four subjects demonstrated a transient reversal in the sensory amplitude decline with lowering of the hand to heart level, but soon progressed to a complete sensory block. The remaining four subjects demonstrated no change in the sensory amplitude decline with lowering of the hand to heart level. Our results suggest that with moderately elevated carpal tunnel pressures, once the sensory amplitude drops by 50% and the patient starts experiencing subjective sensory changes, lowering the hand to heart level may not change the local tissue blood flow sufficiently to maintain a sustained reversal in the declining nerve function and impending nerve damage.
Twenty-two patients with carpal tunnel syndrome scheduled to have a carpal tunnel release, and six volunteer control subjects had carpal tunnel pressures measured with their wrist in neutral position, maximum flexion, and maximum extension. The wrist was then repetitively flexed and extended to maximum position at a rate of 30 full cycles per minute for 1 minute. Pressures were then continually monitored and recorded at 30-second intervals. The pressures were found to be significantly elevated in the immediate post-exercise period in the patients with carpal tunnel syndrome, and they demonstrated a prolonged recovery time to reach the resting pressure when compared with the normal control subjects. This property of prolonged recovery time in patients with carpal tunnel syndrome suggests a possible cause for carpal tunnel syndrome in the occupational setting.
A 14-year-old boy is presented with syringomyelia and a neuropathic sternoclavicular joint. Recognition of neuropathic arthropathy of the upper extremity is important when a massive, destructive joint lesion exists in a patient with syringomyelia.
An 89-year-old woman developed an acute carpal tunnel syndrome secondary to hemarthrosis associated with pigmented villonodular synovitis of the wrist. Pigmented villonodular synovitis is rare in a patient of this age and is an unusual cause of carpal tunnel syndrome.
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