For meniscal allograft transplantation, cell viability and metabolic activity are desirable. The various modalities of preserving the menisci described in the literature include, deep freezing, gluteraldehyde, lyophillisation and cryopreservation. Since formalin in low concentrations is a proven and inexpensive method of tissue preservstion, we attempted to analyse the viability of fibrochondrocytes in the meniscal tissue preserved in three different concentrations of formalin. Twenty-four rabbit menisci were assessed, three groups of 6 menisci each were preserved in 0.25%, 1%, 5% formalin for a period of three weeks; fourth group of 6 fresh menisci were used as controls. The uptake of Na235SO4 and LDH (lactate de-hydrogenase) were analysed for indirect evidence of cell viability. Menisci preserved in 0.25% of formaldehyde showed statistically similar Na235SO4 uptake and LDH activity as the controls; reflecting a similarity in the level of cell viability and metabolic activity. The menisci preserved in 1% and 5% formaldehyde solution showed a decreased radioactive uptake as well as LDH activity.
To evaluate the mechanism of dislocation of the navicular in complex foot trauma; we hypothesize this is similar to lunate/perilunate dislocations. Our experience with 6 cases of total dislocation of navicular without fracture, and an analysis of 7 similar cases reported world-wide was used as the basis for this hypothesis. Radiographs of our patients and the published cases were analyzed in detail, and associated injuries/instablilities were assessed. The position of the dislocated navicular and the mechanism of trauma was considered and correlated, and this hypothesis was propounded. When the navicular dislocates without fracture, it most frequently comes to lie medially, with superior or inferior displacement, depending upon the foot position at injury. It is hypothesized that the forefoot first dislocates laterally (perhaps transiently) at the naviculocunieform joint by an abduction injury; in all cases we recorded significant lateral injury (either cuboid fracture, or lateral midfoot dislocation). The relocating forefoot subsequently pushes the unstable navicular from the talonavicular joint, and depending upon the residual attachments of soft tissues, this bone comes to lie at different places medially. This is a similar mechanism to the lunate dislocation in the wrist, where the relocating carpus push the lunate volarly. Our clinical experience with these complex injuries has shown that the whole foot is extremely unstable. For reduction, the talonavicular joint has to be reduced first, and then the rest of the forefoot easily reduces on to the navicular. An understanding of injury mechanics allows us to primarily stabilize both the columns of the foot, and subsequent subluxation and associated residual pain are avoided. Pure navicular dislocations are not isolated injuries, but are complex midfoot instabilities, and are similar to perilunate injuries of the wrist.
Twenty-six patients with femoral neck fractures were treated by open reduction, cancellous screw fixation and free fibular grafting. The patients were between 14 and 50 years of age. There were 16 old and 10 fresh fractures. Four patients had radiological signs of avascular necrosis before the treatment was instituted. Bony union was achieved in all patients except one, where the failure occurred because of a technical error. The patients were followed up for at least two years. No new case of avascular necrosis was detected after treatment, and there was clinical and radiological improvement in all four patients with pre-operative avascular necrosis.