الفهرس 
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Abstract
Although a progress in surgical techniques for nerve repair and understanding of nerve regeneration over the last 30 years are acceptable, functional recovery after a severe lesion of the major nerve trunk was often incomplete and unsatisfed. Functional recovery is particularly poor for injuries that sever or damage the nerve far from the target makes the target reinnervation delayed. There are new potential therapies either chemical or biological, which aim to improve the functional regeneration of the injured nerves through an acceptable time. The different recent studies discussed the outcomes of the use platelet-rich plasma (PRP) in the healing of different tissue such as tendon, ligament, muscle and bone. However, available literatures lack detailed information about the effect of PRP and bone marrow (BM) on the healing of injured nerve. The present study aimed to explore the effect of platelet-rich plasma (PRP) and bone marrow (BM) aspirate on the functional healing of surgically severed sciatic nerve in dogs after its end to end suturing.
Fifteen adult healthy mongrel dogs of both sexes (9 males and 6 non-pregnant, non-lactating females) were selected and housed in separate standard cages. The average body weight of the dogs was 15.65 kg (range =13-21 kg). Dogs were prepared for surgery and anesthetized by intravenous injection of xylazine and ketamine. The proposed site of sciatic nerve was prepared for aseptic surgery
and the sciatic nerve was approached and exposed. The nerve was severed by a scalpel blade and was then anastomosed by end-to-end fashion using 4 simple interrupted stitches through the epineurum. Dogs were then randomly allocated into three groups; A, B, and C (n=5 in each group). In group A, the control
group, the nerve was not treated but left sutured as previously described. In group B, 1 ml of PRP was injected into the epineurum and around the nerve at
the suture site using 1-ml syringe and fine needle. In group C, 1 ml of BM was
injected into the epineurum and around the nerve at the suture site using 1-ml syringe and fine needle. In all groups, the muscular layer, subcutis and skin were sutured routinely. A stint bandage was sutured with the skin over the surgical site. Dogs were given postoperative antibiotics and nonsteroidal anti- inflammatory drugs and monitored for presence of any postoperative complications.
Subjects were evaluated at one month-interval for 3 months by recording physiological parameters, neurological examination [posture reaction (knuckling, hopping, extensor thrust, hemi-walking and righting) and spinal reflexes (withdrawal, gastrocnemius, cranial tibialis, and sciatic reflexes), gait evaluation included the presence or absence of lameness and ataxia], laboratory examination (measuring serum aspartate transaminase (AST), creatine kinase
(CK), creatinine and urea), and histopathological examination. Data were expressed as mean ± SEM and analyzed statistically for significance at p<0.05.
Results revealed no significant changes in the physiological parameters (RT, HR and RR) pre- and post-operatively. All dogs completed till the end of the experiment except two animals, which were replaced by others. The animals lifted their treated limb off the ground for 3 days post-operation, and then they dragged them. The treated limb in all animals was in a knuckled position or a dorso-grade posture. All the animals in all groups developed ataxia post- operatively relative to their normal condition before surgery (P< 0.0001). There are no significant differences in the degree of ataxia at different times between the groups. Regarding the presence or absence of lameness, all the animals in different groups suffered a clearly demarcated lameness, post-operatively (P=0.0002).The difference of lameness was significantly clear between group A and both of groups B and C, but there is no significant variation in the degree of lameness between groups B and C. Proprioceptive deficits (Knuckling) were significantly changed between groups (A) and (B), (A) and (C) (P=0.041), and
(B) and (C) (P=0.041). Knuckling score enhanced in dogs of treated groups when compared to dogs of control group. In addition, knuckling score enhanced in dogs of the PRP group (B) when compared to that of BM group (C). There were significant differences in the hopping between groups A and both of group
B and C (P<0.05), but there was no significant variation between groups B and
C. The statistical analysis showed an obvious variation in the hemiwalking between groups A and C (P=0.0027), but there were no clear changes between groups A and B and groups B and C. The extensor thrust was significantly variant between groups A and both of groups B and C (P=0.0032), but the variation between groups B and C was not clear. The righting reaction was obviously different between groups A and C (P< 0.0001), but there were no clear changes between groups A and B and groups B and C. The changes in the biochemical values (AST, CK, Creatinine, urea) were variable.
Histopathological examination revealed variations in the architecture pattern of the healed nerves between groups with the nerves treated with PRP being superior.
In conclusion, addition of the PRP and BM aspirate to the nerve after its suturing limit or prevent the occurrence of the Wallerian degeneration, which may delay the process of healing. Although, histological findings in the PRP and BM aspirate groups were satisfactory 3 months after neurorraphy, the clinical findings were unacceptable and unsatisfied. It is recommended to postpone the follow-up period to 6-9 months after operation in the PRP and BM aspirate treated dogs to get reasonable and agreeable clinical results.