Risk of neurovascular injury with limited-open carpal tunnel release: defining the "safe-zone".

Limited-open carpal tunnel release was performed in ten cadaver arms using the "Safeguard" system. The "Safeguard" guide was intentionally placed off of the longitudinal middle/ring finger axis, either in 15 degrees of radial deviation or 15 degrees of ulnar deviation. Despite the errant placement, carpal tunnel release was performed without damage to any neurovascular structure. The proximity of neurovascular structures to the middle/ring finger axis was measured in all ten cadaver specimens. From this, a "safe-zone" was defined for endoscopic or limited-open carpal tunnel release. The "safe-zone" expands when surgery is performed from distal to proximal. The area of the "safe-zone" is greatest when a protective guide is placed between the bursal sac of the carpal canal and the flexor retinaculum.

The treatment of trapeziometacarpal arthritis with arthrodesis.

In this article, the authors discussed the indications for TM arthrodesis, the surgical approach, the types of fixation, expected outcome, and complications. Fusion of the thumb TM joint allows maintenance of pinch and grip strength and provides relief of pain, but limits thumb mobility. An important factor in the success of the arthrodesis is correct thumb position. Trapeziometacarpal joint arthrodesis is advantageous over soft tissue interposition when grip and pinch strength are to be maintained. After TM fusion, however, there are increased stresses across the peritrapezial joints that can cause laxity, pain, and arthritis. Treatment of this may require additional surgical intervention. Treatment of TM arthritis with soft tissue interposition has the advantages of pain relief and increased mobility, but pinch and grip strength are reduced to approximately 75% of normal and rate of reoperation is minimal. The authors recommend TM arthrodesis in the young active person with arthritis limited to the TM joint in whom strong pinch and grip are required. Arthrodesis of the TM joint is safe and predictable and has good subjective and objective results.

Traumatic dislocation of trapezium: case report and review of the literature.

A complete dislocation of the trapezium from its fossa is rare. We present a case of a 36-year-old man with a complete ulnar and volar dislocation of the trapezium. The trapezium was reduced with manual manipulation and was held in anatomic position by using multiple Kirschner wires. The patient's clinical course is reviewed and similar cases from the literature are discussed.

A comparison of plate and pin fixation for arthrodesis of the rheumatoid wrist.

This retrospective study compared plate fixation versus pin fixation in 57 patients with rheumatoid arthritis who underwent wrist arthrodesis. Fixation was achieved by using plates in 32 patients and longitudinal pins in 25 patients. Clinical follow-up averaged 29 months (range: 12-57 months) and radiographic follow-up averaged 16 months (range 12-39 months). Union occurred in 97% of the wrists fixed with plates and in 96% of the wrists fixed with pins. There were 6 (19%) complications in the plate group and 7 (28%) complications in the pin group. Three (12%) wrists fixed with pins moved from the immediate postoperative position to a position of relative volar flexion, while radiographs showed no changes in wrist position in the plate group. With both methods, successful arthrodesis stabilized the wrist in a high percentage of patients. Plate fixation offers an excellent alternative method for arthrodesis of the rheumatoid wrist.

The role of arthroscopy in wrist arthritis.

Recent advances in arthroscopic surgery techniques and instrumentation have enabled the surgeon to improve the treatment of wrist pathology. The arthroscopist can now perform a proximal row carpectomy or radial styloidectomy with minimal dissection and potentially less morbidity. The surgery requires a high level of skill from the surgeon. This is an area of medicine that is still evolving. Long-term studies are lacking but short-term results are promising. In the near future, the role of arthroscopy will better be defined as more research becomes available.

The role of arthroplasty and arthrodesis following trauma to the upper extremity.

Intra-articular fractures in the hand and wrist are common. Prompt treatment with adequate fixation to allow early motion provides the best chance for a successful outcome. Arthrodesis and arthroplasty are the two main options for treatment of residual pain, deformity, or instability in the hand. Management of late wrist symptoms may include proximal row carpectomy, limited wrist fusion, or complete wrist fusion.

Fractures of the elbow.

Elbow fractures encompass a spectrum of severity from low energy nondisplaced fractures to high energy fractures with associated severe soft-tissue injury. Treatment is based on fracture pattern, patient age, bone quality, associated soft-tissue injuries, and associated fractures. The basis for treatment relies on the knowledge of the complex osseous and soft-tissue anatomy of the elbow. The goals of operative and nonoperative treatment are to achieve a stable, anatomic reduction that allows early motion to maximize function.

Fixation of phalangeal fractures.

The indications and methods for operative treatment of phalangeal fractures are reviewed. Included are descriptions with examples of closed reduction and percutaneous pin fixation, percutaneous reduction and percutaneous fixation, open reduction and internal fixation, and static and dynamic external fixation. Also included are tips for facilitating phalangeal fixation and a description of potential complications.

Correlation of wrist ligamentotaxis with carpal distraction: implications for external fixation.

Cadaver forearms were tested to measure carpal bone separation and wrist ligament tension in response to MTS-based incremental wrist distraction. Distraction of 2 mm separated the proximal carpal row from the radius and transmitted an average tension of 8 N. The mid-carpal joint also began to widen at this level of distraction. Distraction of 4 mm resulted in an average tension of 20 N. At this level of distraction, radioscaphoid separation started to exceed radiolunate separation. A transition from low- to high-stiffness response was observed over a range of 4-8 mm distraction for the 12 specimens tested, with an average tension of 80 N associated with 8 mm distraction. Average values of carpal height ratio, revised carpal height ratio, and carpal height index were found to be poor indicators of distraction, owing to their high variability between specimens.

Displaced intra-articular fractures of the distal radius: the effect of fracture displacement on contact stresses in a cadaver model.

Contact stresses in the wrist were measured after simulating displaced fractures of the lunate fossa in the distal radius of eight human cadaver arms. Osteotomies created displaced lunate fossa fractures of 0, 1, 2, and 3 mm. Contact stresses were measured with Fuji pressure-sensitive film after loads of 100 N were applied to the wrist through wrist flexor and extensor tendons. Mean contact stresses were significantly increased with step-offs of 1 mm or more. Maximum stresses and overloaded areas were significantly increased with step-offs of 2 mm or more. As the magnitude of the fracture displacement increased, there was a shift in the focus of the maximum stresses toward the fracture line. In this model, simulated displaced die-punch fractures created alterations in both the magnitude and location of contact stresses in the wrist joint.

Radial instability of the metacarpophalangeal joint of the thumb. A biomechanical investigation.

Human cadaver thumbs were tested to evaluate stability of the radial side of the MP joint. The contributions of the dorsal capsule, radial collateral ligament, accessory collateral ligament, and volar plate were examined with the joint in 0 degrees and 30 degrees of flexion. At 0 degrees flexion, the average joint angulation increased 4 degrees following isolated radial collateral ligament transection and 6 degrees following isolated accessory collateral ligament transection. Release of both the accessory and radial collateral ligaments produced marked instability with joint angulation of at least 46 degrees. The accessory collateral ligament helped to stabilize the extended MP joint. There were no significant contributions to stability from the dorsal capsule and volar plate when the collateral ligaments were intact. In the laboratory setting, radial-side instability of the MP joint of the thumb requires transection of both the proper and accessory radial collateral ligament.

Studies on the autocrine activation of a synovial cell line.

The lapine synovial cell line HIG-82 secretes factors that activate cultures of articular chondrocytes. We showed that these "chondrocyte-activating factors" (CAF) also activate quiescent cultures of HIG-82 cells in an autocrine fashion. After exposure to partially purified preparations of CAF, HIG-82 cells increased their synthesis of prostaglandin E2 (PGE2) and the neutral proteinases collagenase, gelatinase, and stromelysin. CAF also induced their own synthesis. Both PGE2 synthesis and endogenous production of CAF started to increase between 1 and 3 h after treatment of cells with exogenous CAF, but the neutral proteolytic activity of the conditioned medium took approximately 12 h to increase. Induction of neutral proteinases by CAF was inversely related to the degree of cell confluency, whereas their induction by phorbol myristate acetate (PMA) was independent of this parameter. Both CAF and PMA provoked morphologic changes in subconfluent cultures of HIG-82 cells. Although the intracellular concentration of free Ca2+ increased rapidly in response to CAF, the results of experiments with calcium channel blockers and ionophores failed to support a role for Ca2+ fluxes in induction of neutral proteinases. In similar types of experiments, no evidence could be found to implicate fluxes in cyclic AMP or cyclic GMP in the induction of collagenase, gelatinase, or stromelysin. Because PMA is such a strong inducer of these enzymes, protein kinase C may be involved in signal transduction, but further work is needed to determine whether this is so.

Vertebral column allografts for the treatment of segmental spine defects. An experimental investigation in dogs.

Vertebral column allografts, with their intervertebral discs, were implanted into thoracic spine defects (T7-T9) in 11 dogs in an attempt to re-establish spinal stability and preserve spinal biomechanics. Before implantation, the allografts were harvested under sterile conditions from similar-sized dogs and deep frozen at -80 C. The animals were followed for 18 months postoperatively. Radiographs demonstrated gradual loss of intervertebral disc height. Biomechanical analysis showed that the dogs with allografts had no significant difference in spine stiffness compared with normal spines in compression, flexion, and extension testing. Control spines that had been fused were significantly stiffer than the allograft spines in all modes tested (P less than 0.05). Histologic analysis showed incorporation of the allograft but with incomplete revascularization of the allograft's eighth thoracic body. This investigation found that vertebral body allografts with intervertebral discs can function successfully for 18 months in a canine model. This research may assist in the development of physiologic treatment for spinal deficiencies in humans.

Peripheral tears of the meniscus. The effect of open versus arthroscopic repair on intraarticular contact stresses in the human knee.

The mechanical properties of the repaired meniscus may affect its ability to heal and to protect the articular surface against degenerative changes. We compared the immediate biomechanical consequences of open versus arthroscopic repair in the human cadaver knee. Additionally, having measured postoperative stresses at various degrees of knee flexion, we have addressed the effect of tethering of the meniscus, a question relevant to both meniscus repair and replacement. Peak stresses were measured by the Pressensor system. Fresh human cadaver knees were subjected to loading in an Instron unit, on an unconstrained base. Instantaneous loads were applied with the knee in 0 degree, 30 degrees, or 60 degrees of flexion, and stress distributions were measured after repair of a 2 cm peripheral tear, by an open or arthroscopic approach. The results of loading experiments on five knees revealed no statistically significant differences between stresses after the two repairs. Similarly, there was no statistically significant difference between the normal and repaired menisci. In our model, this suggests that the immediate biomechanical consequences of open and arthroscopic repair are equivalent and that the "tethered" meniscus distributes loads as well as the normal meniscus.

Meniscal tears: the effect of meniscectomy and of repair on intraarticular contact areas and stress in the human knee. A preliminary report.

The role of the meniscus in load transmission across the knee has long been a subject of debate. In this study, we examined the biomechanical consequences of the operative treatments for bucket-handle and peripheral meniscal tears. Contact areas and instantaneous intraarticular pressure distributions were measured in two groups of human cadaver knees. In Group I, consisting of four knees, we created a bucket-handle tear involving the inner one-third of the meniscus, followed by partial, and then total meniscectomy. Knees were tested in an Instron testing machine after each procedure, using a 400 pound load at 0 degrees or 30 degrees flexion. Contact areas and local stresses were measured using Prescale, a pressure-sensitive film. After partial meniscectomy, contact areas decreased approximately 10%, and peak local contact stresses (PLCS) increased approximately 65%. After total meniscectomy, contact areas decreased approximately 75%, and PLCS increased approximately 235%. In Group II, consisting of three additional knees, we created a 2 cm peripheral tear of the posterior meniscal horn, followed by open repair, arthroscopic repair, segmental, and then total meniscectomy. Repair of the tear was accomplished with either vertically placed sutures by an open technique or horizontally placed sutures by an arthroscopic technique. Knees were tested in the neutral position in the Instron machine and contact areas and local stresses measured using Prescale. PLCSs and contact areas were found to be the same using either repair technique. There was, however, a 110% increase in PLCS after segmental meniscectomy of that portion of the meniscus involved in the peripheral tear.(ABSTRACT TRUNCATED AT 250 WORDS)