Tashfeen Ahmad

Bone Reinnervation After Fracture: A Study in the Rat

Reinnervation after tibial fracture in the rat was studied by analyzing the occurrence of growth‐associated protein 43 (GAP‐43), a marker for regenerating nerve fibers, and protein gene product 9.5 (PGP‐9.5), a marker for mature nerve fibers, by immunohistochemistry. At 3 days postfracture, GAP‐43‐immunoreactive nerve fibers were first observed in the fracture hematoma and periosteum. At 7 days postfracture, abundant sprouting of GAP‐43‐positive fibers was seen in the callus, hyperplastic periosteum, and edge of fibrocartilage. In the latter region, the nerve fibers were nonvascular, showing dense ramifications and terminal sprouting close to chondroid cells. At 14 days and 21 days postfracture, many GAP‐43‐positive fibers were still sprouting into the fibrocartilage and new woven bone. Fine varicose GAP‐43‐positive fibers also were present in the bone marrow. In contrast to GAP‐43, PGP‐9.5‐positive nerve fibers were observed only occasionally at 3 days postfracture but gradually increased in number from day 14 to 21. Our study shows that intense nerve regeneration occurs in early fracture healing partly unrelated to neovascularization. Considering that neuronal mediators have been shown to participate in local bone formation and resorption, the nerve regeneration observed may prove to be essential for delivery of neuronal mediators required for normal callus formation and/or neovascularization.

Bone and joint neuropathy in rats with type-2 diabetes ☆

We have previously demonstrated that Goto-Kakizaki (GK) rats with spontaneous type-2 diabetes and peripheral neuropathy exhibit regional osteopathic changes. In the present study on 18 GK rats and 21 control Wistar rats, the occurrence of the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP), and the autonomic neuropeptide Y (NPY) was analysed in bone and joints, dorsal root ganglia and lumbar spinal cord by immunohistochemistry and radioimmunoassay (RIA). Immunohistochemistry disclosed a predominance of immunoreactivities in vessel-related nerve fibers, although some were also seen in free terminals. While SP, CGRP and NPY in periosteum, cortical bone and synovium was confined to neuronal tissue, the bone marrow in addition exhibited an abundance of NPY-positive megakaryocytes. Apart from this cellular source of NPY, the observations suggest that the three neuropeptides analysed in bone and joints are of neuronal origin. Quantification by RIA showed a significant decrease of NPY in cortical bone (-36%), bone marrow (-66%) and ankle (-29%) of GK rats. CGRP was decreased in the spinal cord (-19%) and dorsal root ganglia (-26%) but was unchanged in bone and joints, as with SP. Given the suggested anabolic role of NPY and CGRP on bone, neuropeptidergic deficit in diabetes may prove to be an important factor underlying the development of regional osteopenia.

Peripheral quantitative computed tomography for the detection of diabetic osteopathy: a study in the Goto-Kakizaki rat.

Ahmad T, Ohlsson C, Östenson C-G, et al. Peripheral quantitative computed tomography for the detection of diabetic osteopathy: A study in the Goto-Kakizaki rat. Invest Radiol 2003;38:171–176. Rationale and Objective. To assess the utility of dual energy x-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT) in detecting trabecular and cortical bone changes in diabetes as a model of osteopenia. Materials and Methods. The tibia from 10 type-2 diabetic Goto-Kakizaki (GK) rats and 10 control Wistar rats were analyzed by DEXA, pQCT, and ash weight determination. Results. DEXA of GK rats showed a significant reduction in mineral content (32%) and density (24%) of the metaphysis, but not of the diaphysis. PQCT disclosed that the reduction of density predominantly pertained to the trabecular bone (reduced by 62%). Periosteal and endosteal circumferences of the diaphyses were increased and cortical thickness was unchanged leading to increased moment of inertia. Conclusions. This study suggests that in osteopathic conditions, cortical and trabecular bone should be separately examined within specific subregions to obtain relevant information. Loss of metaphyseal trabecular bone seems to be a predominant feature in diabetic rats. Moreover, there is increased moment of inertia in the diaphysis implying increased strength. These diagnostic features of diabetic osteopathy can only be assessed by pQCT. It may prove that similar changes occur in human type-2 diabetes, which could explain the susceptibility to periarticular fracture and Charcot arthropathy.

Differential Bone Turnover in an Angulated Fracture Model in the Rat

We have developed a simple rat model of angulated tibial fracture which elicits substantial differences in bone formation and resorption within the same bone. In 35 rats the right mid-tibia was manually fractured and fixed with an intramedullary 17-gauge cannula needle. Twenty tibias were fixed in anterior angulation (27 ± 5°) and 15 in posterior angulation (31 ± 5°). Serial X-rays were taken over a 12-week period. All fractures healed completely within five weeks. In both groups, bone thickness was already significantly greater on the concave side than on the convex side at week 3 and remained so until the end of the experiment. The thickness on the convex side decreased dramatically within 3 to 5 weeks and gradually thereafter. For morphological analysis of bone mineralization, 3 rats from each group were given calcein and alizarin red injected at different time points up to 14 weeks. Maximum new bone formation was noted within the first 3 weeks. Over the ensuing weeks, new bone formation remained intense on the concave side, but it was virtually absent on the convex side. These results show that angulated fracture deformity reproducibly exhibits differential bone turnover, which can be exploited in research on local regulatory factors. To exemplify the utility of the model, an immunohistochemical study on two local markers was done. Callus tissue of five rats in the anterior angulation group at week 3 post-fracture was stained for the cytokine IL-1β, a stimulator of bone resorption, and the neuropeptide CGRP, an inhibitor of resorption, showing clear differences in positive staining between the concave and convex sides. Our in-vivo model offers a means of analyzing morphologically and quantitatively the differential expression and action of factors involved in local bone turnover.

Spontaneous correction of angular fracture deformity in the rat

Background The different parts of long bone are known to participate in the spontaneous correction of fracture deformity. However, the relative contribution of growth plate, epiphysis and diaphysis of bone during the correction process is not clear. Animals and methods We used a rat model of tibial fracture fixed with a semi-rigid intramedullary pin in anterior angulation, and evaluated the magnitude, temporal course and pertinent sites of spontaneous deformity correction by means of radiography and bone mineral uptake. Results Over a 12-week period, the mean angular deformity was corrected from 27° to 11°. The major portion of the correction (14° of 16°) occurred within 3 weeks, concomitantly with fracture healing. The angle of the proximal growth plate changed 8° over the study period. The first 3 weeks were characterized by intense bone formation on the concave side of the fracture. From weeks 3–8, signs of resorption predominated on the corresponding convex side. On the concave side, the front of new bone formation in the proximal diaphysis moved in the opposite direction to that at the fracture level, so that both sites contributed to deformity correction. Interpretation We found that different sites of a diaphyseal bone fractured in angulation respond quite differently, but still in an orchestrated way to promote correction by modeling. Notably, most of the spontaneous correction occurred during the reparative phase, the major contributor being the diaphysis, not the growth plate. Compared to other reports on angulated fracture using rigid fixation and limb immobilization, our data suggest that semi-rigid fixation and early weight bearing is more efficient in enhancing not only healing, but also deformity correction.

Preliminary radiological result after establishment of hospital-based trauma registry in level-1 trauma hospital in developing country setting, prospective cohort study

Introduction Injuries are the second most common cause of disability, the fifth most common cause of healthy years of life lost per 1000 people and unfortunately 90% of mortality takes place in low-to middle-income countries. Trauma registries guide policymakers and health care providers in decision making in terms of resource allocation as well as enhancing trauma care outcomes. Furthermore data from these registries inform policy makers to decrease the rate of death and disability occurring as a result of injuries. We present our experience in setting up an orthopedic trauma registry and the first short term follow-up of radiological outcomes. Materials and methodology Our study is a non-funded, non-commercial, prospective cohort study that was registered at Research Registry. The primary objectives of our study included assessing pattern of injuries in patients with upper and lower limb skeletal trauma presenting to our tertiary care academic university hospital and their respective outcomes. Data was collected by the musculoskeletal service line team members supervised by an experienced research associate and trauma consultants. The work has been reported in line with the STROCSS criteria. Results A total of 177 patients were included in this analysis, of whom 101 (57.1%) patients had lower limb fractures, 64(36.1%) patients ad upper limb fractures and 12 (6.8%) patients had both upper and lower limbs involved. A total of 189 upper and lower limb fracture cases were recorded. 176 patients (93.1%) underwent surgeries and 13(6.9%) were managed nonoperatively. Roentgenographic outcomes were assessed using radiological criteria for each bone fractured. Conclusion Establishing a trauma registry assists in identification of the pattern of injuries presenting to the hospital which helps in priority setting, care management and planning. This continuous audit of outcomes in turn, plays a significant role in quality improvement.