Collagen expression and biomechanical response to human recombinant transforming growth factor beta (rhTGF-beta2) in the healing rabbit MCL.

We investigated biomechanical and collagen expression in a healing bilateral rabbit medial collateral ligament (MCL) model to human recombinant transforming growth factor beta (rhTGF-beta2) at three and six weeks. Each rabbit had rhTGF-beta2 in a bioabsorbable pellet administered in one side, with the contralateral side serving as control (no rhTGF-beta2). All MCL healed with rhTGF-beta2 producing a profoundly increased scar mass at three weeks which decreased in size toward control at six weeks. In-situ hybridization demonstrated collagen expression (type I and III) no different than control at three weeks, but by six weeks elevated expression of type I was seen. Biomechanical analysis at three weeks showed no effect of rhTGF-beta2 on structural properties. However, at six weeks rhTGF-beta2 significantly inhibited both the maximum load (p < 0.05) and energy absorbed (p < 0.05) with no change in stiffness. Despite increased type I collagen expression and profound increase in early scar mass, rhTGF-beta2 did not improve the structural properties. Whether the dose or mode of delivery is responsible for decline in structural properties cannot be determined in this design. We hypothesize investigations of healing ligaments to cytokines should have biologic and biomechanical properties correlated in the same study at a minimum of two time points.

The biomechanics of hybrid external fixation.

OBJECTIVE: The objective of this study was to ascertain which factors determine the rigidity of a hybrid external fixation frame in a tibial periarticular fracture model. DESIGN: Laboratory investigation using a polyvinylchloride pipe periarticular tibia fracture model. SETTING: Simulated periarticular tibia fractures were created in a tibia model. Instrumented specimens were tested in a biomaterials testing system. INTERVENTION: Groups of simulated periarticular tibia fractures were stabilized with one of nine different external fixation constructs with components from one manufacturer. MAIN OUTCOME MEASUREMENTS: Elastic stiffness was measured for each specimen in compression, torsion, flexion bending, extension bending, and varus and valgus bending. RESULTS: The four-ring Ilizarov fixator was the stiffest in all modes of testing. There was a trend toward increasing stiffness with an increasing number of rings. Fixators constructed with multiple levels of fixation in the periarticular fragment were stiffer in all modes of testing. The additional spacing between wires gained by the use of a single thick carbon ring or the use of a drop wire three centimeters from a single ring did not increase stiffness in this model. Frame modifications intended to augment the bar-to-ring connection did not increase stiffness. The use of rings mounted with half-pins instead of a unilateral bar mounted with half-pins for diaphyseal fixation increased the stiffness of the frame only in torsional testing. CONCLUSIONS: Although the ideal stiffness of an external fixator is unknown, our results show that the addition of more than one level of fixation in the periarticular fragment increases the stiffness of hybrid external fixators in this periarticular tibia fracture model. Augmentation of the ring-to-bar connection did not significantly affect the stiffness of the frame.

Fusobacterium osteomyelitis and pyarthrosis: a classic case of Lemierre's syndrome.

Lemierre's syndrome, a systemic anaerobic infection caused by Fusobacterium necrophorum, is characterized by an acute oropharyngeal infection, septic thrombophlebitis of the internal jugular vein, sepsis, and multiple metastatic infections. It commonly leads to septic arthritis and occasionally to osteomyelitis. In the preantibiotic era, this infection was nearly universally fatal. Today it still poses a potentially grave threat to the young patients affected. Prompt recognition with appropriate debridement and antibiotic treatment results in complete recovery in most cases. We report a case of anaerobic septic arthritis and multifocal acute hematogenous osteomyelitis as part of a classic presentation of Lemierre's syndrome.

Late-onset sternomanubrial dislocation with progressive kyphotic deformity after a thoracic burst fracture.

Fractures and dislocations of the sternum may be associated with flexion-compression injuries of the thoracic spine. Sternal injuries most commonly occur at or near the sternomanubrial joint. We present a patient with a known thoracic spine fracture who developed a subsequent late-onset, symptomatic sternomanubrial dislocation and progression of thoracic kyphosis, ultimately requiring operative fixation of both the sternum and the spine. Internal fixation of these sternal injuries should be considered in the setting of a flexion-compression thoracic spine fracture to possibly prevent a worsening kyphosis and neurological decline.

Treatment priorities in patients with traumatic rupture of the thoracic aorta.

Autopsy studies reveal that 90 percent of patients with traumatic rupture of the thoracic aorta (TRTA) die at the scene of the accident and 25 percent of those reaching the hospital do not survive their injuries. Treatment priorities in patients with TRTA and associated life-threatening head and intra-abdominal injuries have not been adequately studied. The authors reviewed their experience with 57 consecutive patients sustaining TRTA to establish treatment priorities in these multiply injured patients. The mean age of the population was 35 years (43 men, 14 women). Hospital mortality was 24 percent; the most common cause of death was hemorrhage. Fully 95 percent of the patients had associated injuries requiring operative intervention. Abdominal injuries requiring laparotomy were present in 20 patients (35%): 14 splenic injuries, 8 liver injuries, 3 pancreatic injuries, and 3 mesenteric lacerations. Twenty-eight patients (49%) had orthopaedic injuries requiring operative fixation. Maxillofacial injuries requiring surgical repair occurred in 20 patients (35%). Fifteen patients (26%) sustained significant closed head injuries, but only 1 required craniotomy for hemorrhage. Nine hemodynamically unstable patients with intra-abdominal hemorrhage underwent immediate laparotomy for control of bleeding followed by aortography and aortic repair (2 deaths, 22%). Seven hemodynamically stable patients had aortography followed by laparotomy for control of intra-abdominal hemorrhage with subsequent thoracotomy (1 death, 14%). Thirty stable patients underwent aortography followed by immediate thoracotomy; 22 required no further procedures, while 8 required an additional operation (7 death, 23%).(ABSTRACT TRUNCATED AT 250 WORDS)