Effect of wrist position on power grip and key pinch strength following carpal tunnel decompression

Power grip and thumb key pinch strength were measured pre- and immediately postoperatively in 30 patients with carpal tunnel syndrome while the wrist was in flexion and extension. The carpal tunnel decompression was performed under local infiltration with 1% lignocaine. Grip strength decreased more in wrist flexion than in wrist extension. No difference was found in thumb pinch strength. The authors conclude that some of the immediate postoperative loss of grip strength in wrist flexion can be attributed to prolapse of flexor tendons out of the carpal tunnel in this position.     

Restoration of strong grasp and lateral pinch in tetraplegia due to cervical spinal cord injury.

Patients with tetraplegia who have "strong" sixth cervical neurologic (C-6) function often can be given active grasp and strong lateral pinch by tendon transfers and tenodeses. Wrist control can be retained by the extensor carpi radialis brevis and flexor carpi radialis and can permit transfer of the extensor carpi radialis longus to provide finger flexion. Either the brachioradialis or pronator teres then is available for transfer to restore adduction-opposition of the thumb with an in situ tendon graft of a paralyzed flexor superficialis rerouted to the thumb through a palmar fascial pulley. The other motor can provide thumb flexion for strong lateral pinch. Extrinsic extension can be provided by tendoeses. With seventh cervical neurologic (C-7) function retained, active digital extension is present and functional expectations are better. Ten hands in seven patients with traumatic tetraplegia from injuries at C-6 or C-7 level have been reconstructed. The average grasp and pinch force after operation was 5.5 and 3.0 Kg., respectively. All patients but one were pleased with the increased function a     

Carbonic anhydrase activity of human peripheral nerves: a possible histochemical aid to nerve repair

The return of usable function after injury of peripheral nerves depends upon the appropriate regeneration of axons to their end organs. Debridement trimmings of severed nerves harvested during surgery were stained to demonstrate carbonic anhydrase activity. This histochemical method can be accomplished within 3 to 4 hours of receiving the tissue. Nerve fascicles were readily discriminated from one another by the individual staining patterns of their constituent axons. Axoplasmic staining was predominantly a feature of sensory fibers, and myelin staining was characteristic of skeletal motor axons. Carbonic anhydrase histochemistry may provide a means of accurately matching fascicles in cut nerve ends.     

Spontaneous retrocarpal radial artery thrombosis: a report of two cases

Two patients with spontaneous retrocarpal radial artery thrombosis are reported. Both patients had numbness and cold intolerance of the thumb and index finger and one patient had splinter hemorrhages. Angiography revealed identical occlusions of the radial artery over a 2.5 cm segment dorsal to the wrist. Both patients had complete palmar arches. Flow from the ulnar artery was sufficient to prevent frank necrosis of the thumb but not to prevent ischemic symptoms. Both patients were successfully treated by resection of the area of thrombosis and interpositional vein grafting by use of microsurgical techniques. Symptoms resolved after operation in both cases. Follow-up examinations 3 months and 5 1/2 years later revealed continued graft patency.     

Von Frey's method of measuring pressure sensibility in the hand: an engineering analysis of the Weinstein-Semmes pressure aesthesiometer

The development of microsurgical techniques has generated a resurgence of interest in estimating local pressure sensibility as a measure of sensory improvement. Because our experience with Weinstein's modification of Von Frey's probes yielded variable and poorly understood results, we measured two sets of probes and examined them in the light of the engineering principles on which their behavior is based. The mechanical behavior of the nylon monofilaments can be described as buckling with one end built in and the other end pinned. The probes are relatively uniform and consistent. However, no loss in sensitivity would accompany division of the set into two or three equivalent sets. Variations in the buckling stress as high as a factor of eight are difficult to avoid. Gross errors arise from careless application, variations in the elastic modulus due to changes in temperature and humidity, and variations in the attachment of fibers to handles and differences in the ends of the filaments. Interpreting results for this instrument requires an understanding of the factors which can influence those results. The rpobes are simple to use but easy to misinterpret.     

The mechanism of dorsal fracture dislocation of the fifth carpometacarpal joint.

Fracture dislocation at the base of the fifth metacarpal is a rare injury. Fewer than 25 cases have been published in the English-language literature. A force acting along the longitudinal axis of the fifth metacarpal causes a fracture dislocation at the base of the bone in a dorsal-ulnar direction, because of the anatomy of the joint and the mechanical properties of the bone and the intermetacarpal ligament. The mechanism of other types of injury to this joint, namely dorsal-radial or palmar-radial dislocation of the base of the fifth metacarpal is different. A case is presented which demonstrates the mechanism of the fracture dislocation.     

Scapholunate dissociation from a fall on the elbow

We report an undescribed mechanism of injury that caused scapholunate dissociation. Scapholunate dissociation has been previously described as resulting from a fall on the outstretched hand. In this case injury was caused by a fall on the elbow. The mechanism is compared to that of an axe head that is repositioned by butting the handle of the axe on the ground. Recognition of this mechanism may help in the diagnosis of this injury.     

Biomechanical evaluation of metacarpophalangeal joint prosthesis designs.

A laboratory biomechanical analysis of metacarpophalangeal joint prosthesis designs was done with fresh cadaver finger rays. The center of rotation, range of motion, tendon excursion, and fingertip force were determined on the specimens before and after implanting Swanson, Niebauer, Steffee II, St. Georg-Buchholz, Schultz, and modified Strickland prostheses. Their biomechanical behavior varied considerably and none duplicated the normal metacarpophalangeal (MP) joint. Each has design characteristics that may be clinically advantageous as well as disadvantageous. Irrespective of the design, the studies done cannot be divorced from the following factors: (1) implant material properties--silicone rubber implants buckled with tendon loading; this deformity created a significant flexor mechanical advantage and an extensor mechanical disadvantage; (2) implant fixation--freely movable implant stems dampened part of the applied load; braided suture provided inadequate immediate fixation; (3) implantation technique--the articulated prostheses can be technically unforgiving; errors in technique resulted in alteration of their biomechanical behavior.     

Sarcoidosis of the upper extremity: case presentation and literature review

Sarcoidosis of the skeletal system is not rare but problems related to it are unusual. Two cases of sarcoidosis, with involvement of the upper extremity, are presented to point out problems that may occur in its treatment. Osteolytic sarcoid involvement of the phalanges leads to resorption and collapse, with a poor response to bone grafting or splinting. The phalangeal collapse could be treated with intramedullary cement or Kirschner wire fixation. Sarcoid involvement of fractures can lead to a nonunion and they should be treated with excision when appropriate, rather than attempting osteosynthesis. Arteriograms of sarcoid lesions show them to have a very poor blood supply. A bone scan can be used to demonstrate areas of sarcoid involvement before the characteristic lesion becomes evident on a radiography.     

Electromyographic analysis of the thumb: a study of isometric forces in pinch and grasp

An electromyographic study of thumb muscles was performed on eight subjects by means of integrated polyelectromyography and simultaneous recordings of isometric flexion-extension, abduction-adduction, and prehensile pinch and grasp of the thumb. The integrated electromyographic signal proved to be an excellent index of thumb muscle activity, with a linear relationship found at low to middle levels of muscle strength. To facilitate understanding of thumb function, thumb muscles can be classified as primary or secondary on the basis of electrical potential activity. In isometric flexion, the flexor pollicis longus (FPL) was primary, whereas in extension, the extensor pollicis longus (EPL) and abductor pollicis longus were primary. In adduction, the adductor pollicis and EPL were primary and the FPL was secondary. In abduction, the abductor pollicis brevis and opponens pollicis were primary. The adductor pollicis, and FPL were nearly equal during pinch and grasp, with significant electrical activity increasing with greater force requirements. The first dorsal interosseous and EPL contributed secondarily in both pinch and grasp. When surgeons consider tendon transfers for nonfunctioning thumb muscles, the primary muscles should be replaced first to best restore pinch and grasp strength.