Dorsal dislocation of the distal radioulnar joint secondary to plastic deformation of the ulna

An unusual case of an unstable dorsal, distal radioulnar dislocation secondary to plastic deformation of the ulna is presented. The etiology and pathomechanics of this rare injury are reviewed.     

An irreducible phalangeal epiphyseal fracture-dislocation. A case report

A 20-month-old infant sustained an irreducible epiphyseal fracture-dislocation of a proximal interphalangeal joint. The dorsal dislocation of the joint was associated with a 90 degree rotational displacement (Salter-Harris Type I fracture) of the epiphysis of the middle phalanx. This injury, which seems not to have been described previously, required open reduction through both volar and dorsal incisions because the intact collateral ligaments and extensor central slip did not permit adequate distraction of the joint.     

Continuous and intermittent levodopa differentially affect basal ganglia function

The effects of continuous and intermittent levodopa treatment on behavioral and biochemical indexes of basal ganglia function were compared in rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal dopamine pathway. Animals treated for 30 days with intermittent levodopa exhibited behavioral sensitization manifested by an enhanced rotational response to apomorphine; the rotational response of rats treated with an equivalent dose of levodopa by continuous infusion did not differ from that of saline-treated controls. Dopamine receptor up-regulation in the denervated striatum relative to the intact striatum was statistically significant for D1 but not D2 receptors: This asymmetry in dopamine receptor levels was diminished following intermittent levodopa treatment. Glutamic acid decarboxylase activity, modestly elevated in all groups in the denervated striatum relative to the intact striatum, increased substantially over control values bilaterally as a result of intermittent, but not continuous, levodopa treatment. These findings suggest a relation between the schedule of chronic levodopa administration and the development of behavioral sensitization, possibly as a consequence of alterations in neuronal systems located downstream from striatal dopamine receptors. The behavioral sensitization induced by chronic, intermittent dopaminomimetic treatment may serve as a model for motor fluctuations in Parkinson's disease.     

Biomechanical and histological evaluation of the Herbert screw

The Herbert screw has been demonstrated to have widespread clinical applicability. A biomechanical and histological evaluation of the Herbert screw was conducted to better define its applications. When subjected to pull-out, toggle, and compression testing, in a cancellous bone calf model, it was demonstrated to be biomechanically inferior to the 4.0 mm ASIF cancellous screw. The use of two Herbert screws minimized but did not eliminate this difference. Articular cartilage healing in a rabbit model was consistently demonstrated if the Herbert screw was buried deep to the osteochondral junction. However, toluidine blue histochemical staining showed that the hyaline-like repair cartilage differed qualitatively from normal cartilage. Utilization of the Herbert screw should include an understanding of the limitations of its fixation potential and a recognition of the repair response after intraarticular applications.     

Peripheral neuropathy--an unusual complication of meningococcemia.

A case of meningococcemia with a persisting peripheral neuropathy and gangrene of the fingers is presented. These unusual complications are thought to be related to the diffuse intravascular coagulation syndrome.