Journal of orthopaedic research : official publication of the Orthopaedic Research Society
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Comparative Study
Motor functional and morphological findings following end-to-side neurorrhaphy in the rat model.
Nerve repair cannot always be achieved by the conventional end-to-end technique. This study evaluated the functional recovery of nerves repaired with end-to-side neurorrhaphy in a rat model. ⋯ Evaluation included gait analysis by calculation of a peroneal functional index, measurement of contractile function of the extensor digitorum longus muscle, wet weight of the extensor digitorum longus, and histological examination. The findings of this study suggested the following: (a) end-to-side neurorrhaphy allows effective motor functional recovery, demonstrated by earlier improvement of the peroneal functional index, stronger muscle contractile function, greater muscle weight, and higher density of regenerated axons compared with unrepaired nerves; (b) removal of the epineurium of the donor nerve at the nerve coaptation site increases the effectiveness of end-to-side neurorrhaphy, but the epineurium appears to be a partial barrier to axonal regeneration; (c) removal of the epineurium does not affect the structure and function of the donor nerve; and (d) end-to-end repair achieved the best functional recovery among the four groups; therefore, end-to-side repair should be considered as a potential alternative only when no proximal nerve is available.
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Comparative Study
Intramedullary pressure and bone marrow fat extravasation in reamed and unreamed femoral nailing.
This study was designed to investigate whether intramedullary pressure and embolization of bone marrow fat are different in unreamed compared with conventional reamed femoral nailing in vivo. In a baboon model, the femoral shaft was stabilized with interlocking nailing after a midshaft osteotomy. Intramedullary pressure was measured in the distal femoral shaft fragment at the supracondylar region. ⋯ Liberation of fat during insertion of 9-mm nails after reaming was recorded with a score of 3.5 +/- 0.4. In both groups, a positive correlation of fat extravasation with the rise in intramedullary pressure was found (reamed group: r(s) = 0.868; unreamed group: r(s) = 0.698), resulting in significantly less liberation of bone marrow fat in the unreamed stabilized group than in the reamed control group (p < 0.05). The data indicate that fat embolization during nailing procedures after femoral osteotomy increases with increasing intramedullary pressure and occurs in a lesser degree in unreamed than in reamed intramedullary femoral shaft stabilization.