Effect of K-wire Reuse and Drill Mode on Heat Generation in Bone.

BACKGROUND: We examined the effect of Kirschner wire (K-wire) reuse and use of oscillating mode on heat generation within cortical bone. METHODS: Two trocar-tipped K-wires were drilled through the diaphysis of each of 30 human metacarpals and phalanges: one K-wire was inserted in rotary mode and another in oscillating mode. Each wire was reused once. Thermocouples placed within the dorsal and volar bone adjacent to the K-wire drill path measured temperatures throughout each test. RESULTS: Peak cortex temperatures were 25°C to 164°C. Rotary drilling achieves peak temperatures quicker (31 ± 78 seconds vs 44 ± 78 seconds, P = .19) than oscillating drilling, but insertion time is also less, resulting in lower overall heat exposure. This effect is also seen when the K-wire is reused (34 ± 70 seconds vs 41 ± 85 seconds, P = .4). The length of time that cortical bone was exposed to critical temperatures (47°C or more) was significantly higher when a wire was reused (36 ± 72 seconds vs 43 ± 82 seconds, P = .008). Peak temperatures greater than 70°C (a temperature associated with instantaneous cell death) were observed on many occasions. CONCLUSIONS: Overall heat exposure may be higher if a K-wire is reused or inserted in oscillating mode. In the absence of external cooling, K-wire insertion into cortical bone can easily expose bone to temperatures that exceed 70°C and may increase the risk of osteonecrosis.

Biomechanics of an Articulated Screw in Acute Scapholunate Ligament Disruption.

Background An injury to the scapholunate interosseous ligament (SLIL) leads to instability in the scapholunate joint. Temporary fixation is used to protect the ligament during reconstruction or healing of the repair. Rigid screw fixation-by blocking relative physiological motion between the scaphoid and lunate-can lead to screw loosening, pullout, and fracture. Purpose This study aims to evaluate changes in scaphoid and lunate kinematics following SLIL injury and the effectiveness of an articulating screw at restoring preinjury motion. Materials and Methods The kinematics of the scaphoid and lunate were measured in 10 cadaver wrists through three motions driven by a motion simulator. The specimens were tested intact, immediately following SLIL injury, after subsequent cycling, and after fixation with a screw. Results Significant changes in scaphoid and lunate motion occurred following SLIL injury. Postinjury cycling increased motion changes in flexion-extension and radial-ulnar deviation. The motion was not significantly different from the intact scapholunate joint after placement of the articulating screw. Conclusion In agreement with other studies, sectioning of the SLIL led to significant kinematic changes of the scaphoid and lunate in all motions tested. Compared with intact scapholunate joint, no significant difference in kinematics was found after placement of the screw indicating a correction of some of the changes produced by SLIL transection. These findings suggest that the articulating screw may be effective for protecting a SLIL repair while allowing the physiological rotation to occur between the scaphoid and lunate. Clinical Relevance A less rigid construct, such as the articulating screw, may allow earlier wrist rehabilitation with less screw pullout or failure.

Capnocytophaga canimorsus Sepsis Following a Minor Dog Bite to the Finger: Case Report.

Capnocytophaga canimorsus is a gram-negative bacillus present in the oral cavities of 22% to 74% of healthy dogs. Capnocytophaga canimorsus has unique virulence factors that enable it to evade the human immune system and cause life-threatening sepsis following a dog bite. We report a previously well 68-year-old woman who presented with septic shock and multiorgan failure following a seemingly minor dog bite to the finger. The patient required intensive care treatment, intravenous antibiotic therapy, and multiple surgical procedures including amputation of the affected finger. The septicemia and coagulopathy that ensued resulted in gangrene and amputation of additional fingers and toes. The purpose of this report is to raise awareness of this organism among hand surgeons when faced with a patient presenting in septic shock and minimal signs at the site of a dog bite.

Radial head dislocation during proximal radial shaft osteotomy.

The following case report describes a 48-year-old female patient with a longstanding both-bone forearm malunion, who underwent osteotomies of both the radius and ulna to improve symptoms of pain and lack of rotation at the wrist. The osteotomies were templated preoperatively. During surgery, after performing the planned radial shaft osteotomy, the authors recognized that the radial head was subluxated. The osteotomy was then revised from an opening wedge to a closing wedge with improvement of alignment and rotation. The case report discusses the details of the operation, as well as ways in which to avoid similar shortcomings in the future.

Fixation of distal ulna fractures associated with distal radius fractures using intrafocal pin plate.

Background Unstable distal ulna fractures in the setting of distal radius fractures can present a challenging problem, especially in the elderly population. Operative fixation of the subcapital distal ulna fracture may help to provide a stable ulnar buttress for attempting to reduce the distal radius fracture. Traditional fixation techniques of the distal ulna may prove unsatisfactory in the setting of osteoporosis and comminution. Description The intrafocal pin plate is placed through a small incision distally and uses the curve of the plate to obtain multiple points of fixation within the intramedullary canal. The overhang of the distal aspect of the plate helps to reduce the fracture. The plate is secured using unicortical locking screws in the ulnar head. Patients and Methods The most ideal fracture pattern for this fixation technique is a subcapital distal ulna fracture that is unstable and associated with a distal radius fracture. This technique is contraindicated in ulnar head fractures, segmental fractures with proximal extension, and open fractures with gross contamination as well as in the setting of active infection. Results This technique has provided a stable ulnar buttress and aided in the reduction of grossly unstable distal radius fractures. All of these patients have gone on to union, and we have not experienced a need for plate removal due to pain or soft tissue irritation. Conclusions We have found the intrafocal pin plate to provide both a stable ulnar buttress as well as intramedullary fixation to aid in the fixation of distal radius fractures associated with unstable distal ulna subcapital fractures.

Scaphoid fractures: what's hot, what's not.

The scaphoid is the most commonly fractured carpal bone of the wrist. It is an unusual carpal bone in that it bridges both the proximal and the distal rows; this subjects it to continuous shearing and bending forces. Approximately 80% of the scaphoid is covered by cartilage, which limits its ligamentous attachment and vascular supply. Most scaphoid fractures occur at the waist. Acute stable fractures or incomplete fractures of the scaphoid may be treated nonsurgically; a high rate of union can be expected. However, there is considerable debate about the type of immobilization needed. Although closed treatment of stable wrist fractures of the scaphoid achieve a high rate of healing, prolonged cast immobilization may lead to complications, including muscle atrophy, possible joint contracture, and disuse osteopenia. Because of this, internal fixation of minimally displaced fractures of the scaphoid has recently become popular. There is consensus in the literature that nonunion of the scaphoid and proximal pole fractures should be treated surgically. In the past several decades, percutaneous arthroscopic techniques of scaphoid stabilization, which minimize surgical morbidity, have become popular. There also has been a significant improvement in the management of difficult scaphoid nonunions, with or without deformity. Improved techniques include open and dorsal approaches and vascularized bone grafting of resistant scaphoid nonunions. Declining in popularity is the prolonged immobilization of unstable fractures when surgical stabilization may have been a better treatment option.

Intrafocal pin plate fixation of distal ulna fractures associated with distal radius fractures.

Subcapital ulnar fractures in association with distal radius fractures in elderly patients increase instability and pose a treatment challenge. Fixation of the ulnar fracture with traditional implants is difficult due to the subcutaneous location, comminution, and osteoporosis. We describe an intrafocal pin plate that provides fixation by a locking plate on the distal ulna and intramedullary fixation within the shaft. The low profile and percutaneous technique make this device a useful alternative for treatment of subcapital ulna fractures in the elderly.

Management of proximal interphalangeal joint dislocations in athletes.

Proximal interphalangeal joint dislocations are common athletic injuries. In dislocations and fracture dislocations, the most important treatment principle is congruent joint reduction and maintenance of stability. This article reviews the relevant anatomy, injury characteristics, and treatment options for proximal interphalangeal joint dislocations and fracture dislocations. Treatment methods discussed include closed reduction, percutaneous fixation, and open reduction.

Anthropometry of the human scaphoid.

PURPOSE: Internal fixation has become a well-established alternative to casting for acute scaphoid fractures. Screw design has evolved, and several different types of screws of varying sizes are now available. The purpose of this study was to establish morphometric data for the human scaphoid, document variation in scaphoid dimensions between genders, and to evaluate symmetry in scaphoid measurements between the two sides. METHODS: We measured length, width, and morphology of the scaphoid in 30 paired cadaveric specimens with reference to the long axis of the scaphoid from the proximal pole to the distal articular surface. The width of the bone was compared with diameters of commercially available screws. RESULTS: When measured along an axis from proximal pole to the distal articular surface, male scaphoids (31.3 mm +/- 2.1) were significantly longer than female specimens (27.3 mm +/- 1.7). The male scaphoid was also significantly wider than the female specimen when measured perpendicular to the long axis 2 mm from the proximal pole (4.5 mm +/- 1.4 vs 3.7 mm +/- 0.5) and at the waist (13.6 mm +/- 2.6 vs 11.1 mm +/- 1.2). There was no significant difference in the distal pole diameter measured 2 mm from the tip between genders (7.2 mm +/- 1.0 vs 7.2 mm +/- 1.2). The diameters of most commercially available standard screws were larger than the proximal pole of the female scaphoid. CONCLUSIONS: Allowing for countersinking of the screw 2 mm beneath either pole, our data suggest the usual screw length will be 27 mm and 23 mm for male and female scaphoids, respectively. The small width of the proximal pole of the female scaphoid will not accommodate standard-sized screws from most manufacturers, and consideration must be given to distal to proximal screw placement or use of "mini" screws if the implant is to be inserted in a proximal to distal direction.

Biomechanics and biology of external fixation of distal radius fractures.

External fixation is a versatile and useful tool for management of complex fractures. There is little to choose between the various types of commercially available fixators, and it is important to use one that allows the surgeon adequate versatility and follows sound biomechanical principles. Ligamentotaxis can be used effectively to reduce the most difficult fractures; however, over-distraction and prolonged traction are harmful and should be avoided. Certain types of fractures do not respond to treatment with ligamentotaxis alone and require adjunctive treatment, such as limited internal fixation. A single K-wire significantly adds to the stability of fixation and should be considered in all cases. Understanding the basic mechanical principles and respect for pin-bone biology allow for successful use of external fixation with minimal complications.