Biomechanical stability of intramedullary nailed high proximal third tibial fractures with cement augmented proximal screws

OBJECTIVE: Intramedullary nailing of nonarticular proximal tibia fractures can be affected by bone density resulting in loss of stability, fixation, and malalignment in osteopenic bone. This study was designed to quantify the biomechanical effects of augmenting proximal screws with cement in intramedullary nailing of high proximal third tibial fractures. DESIGN: In vitro biomechanical study using anatomic specimens. METHODS: Reamed nails were inserted into seven pairs of fresh-frozen cadaveric proximal tibiae and secured using two oblique and two transverse proximal screws. Paired tibiae were randomly assigned into two groups: cemented and noncemented proximal screw-holes. Bone cement was injected into the screw-holes before screw insertion in the cemented tibiae. Specimens were then tested in flexion/extension and varus/valgus to 12 Nm and in torsion to 7 Nm. Physical measurements of bone density were obtained to determine the effect of density on stability. MAIN OUTCOME MEASURES: Stability of the construct in both groups was analyzed and compared statistically using paired t tests. RESULTS: Cement augmentation of the proximal screws significantly increased mechanical stability in torsion and varus/valgus load configurations, with average decreases in rotational motion of 5.4 degrees +/- 1.6 degrees and 5.1 degrees +/- 5 degrees respectively. No change in stability was observed in flexion/extension loading. A trend toward decreased stability was seen in the uncemented construct in varus/valgus; cement augmentation of the proximal screws eliminated this effect. CONCLUSIONS: Lower bone density decreased the stability of the uncemented construct; however, cement augmentation of the proximal screws showed a trend to eliminate this effect in the varus/valgus loading configuration and should be considered when nailing proximal third tibial fractures in osteoporotic patients.     

Gender differences in 24-hour urinary diaries of asymptomatic North American adults

PURPOSE: Two previously published studies from our center have described the urinary habits of asymptomatic men (284) and women (300) as revealed by 24-hour urinary diaries. Those gender specific studies found that urinary diary variables are affected by age and race. By comparing the data from those studies we determined the effect of gender on voiding habits. MATERIALS AND METHODS: In this secondary analysis we matched each female urinary diary to that of a male of similar age and race. Diary variables were compared using paired sign tests with results considered significant at the 5% level. RESULTS: A total of 141 matched pairs were studied. The population age ranged from 18 to 68 years and was racially diverse (56% black, 31% white, 7% Hispanic and 6% Asian). Men had higher total fluid intake and mean voided volume than women (p <0.001 and 0.04, respectively). Women voided more frequently than men (p = 0.006) and had more voids per liter of fluid intake (p <0.001). No gender differences were found for body mass index, nighttime or daytime diuresis rates, total urine volume, maximum voided volume or rates of nocturia. CONCLUSIONS: This analysis suggests that there are significant gender effects on 24-hour diary variables, with females tending to void more often and at lower mean volumes. The results of our study may be useful in the design of research studies or for patient counseling.     

Determinants of response to a parent questionnaire about development and behaviour in 3 year olds: European multicentre study of congenital toxoplasmosis

Background  

We aimed to determine how response to a parent-completed postal questionnaire measuring development, behaviour, impairment, and parental concerns and anxiety, varies in different European centres.     

Metastatic burst fracture risk prediction using biomechanically based equations

Clinical guidelines are a useful adjunct to select patients with spinal metastases for prophylactic intervention. The objective of this study is to determine the ability of biomechanically based models to accurately predict metastatic burst fracture risk. Ninety-two vertebrae with osteolytic spinal metastases were examined retrospectively. Vertebrae were categorized as burst fractured, wedge fractured, or intact and analyzed using three predictive models: vertebral bulge (maximum radial displacement under load), vertebral axial displacement (maximum axial displacement under load), and a volumetric estimate of tumor size. The load-bearing capacity parameter (tumor volume, bone mineral density, disc quality, pedicle involvement) was determined from computed tomography while the load-bearing requirement parameter (pressure load, loading rate) was determined using computed tomography and patient records (retrieved for 37 patients [52%]). Fracture prediction was optimized using the vertebral bulge model considering only load-bearing capacity with a specificity, sensitivity, and confidence interval of 1 to yield a clear threshold for burst fracture risk. Fracture prediction in the other two models, vertebral axial displacement considering only load-bearing capacity and tumor size, also was strong with receiver-operator curve values of 0.992 and 0.988, respectively. The predictive power of these models can provide useful clinical information for prophylactic decision-making.     

Open fractures of the calcaneus: a review of treatment and outcome

OBJECTIVES: The aim of this study was to evaluate the functional and clinical outcome of patients with open calcaneus fractures and to determine what factors were associated with these outcomes. DESIGN: Retrospective review of 2 level 1 prospective databases. SETTING/PATIENTS/PARTICIPANTS: All patients admitted with an open calcaneal fracture to 2 level 1 trauma units between January 1, 1987 and April 1, 1996 were identified. Data regarding demographics, injury characteristics, and treatment and complications were documented using a standardized data abstraction form. Radiographs were reviewed to document the fracture type according to Essex-Lopresti. For those patients who had computed tomography scans available, the Sanders et al classification was applied and documented. Patients were contacted and asked to return for follow-up evaluation including the American Orthopaedic Foot and Ankle Society ankle/hindfoot score, the Maryland Foot Score, and the Short Form 36 (SF-36). For patients not willing to return for examination, the questionnaires were completed over the telephone, and the objective scoring components were assigned to lowest score possible. RESULTS: Of 177 calcaneal fractures in patients treated as inpatients during the study period, we identified 30 open fractures in 29 patients. Twenty-seven patients had associated injuries. Two patients underwent amputation within 24 hours due to severe crush injury. Following urgent debridement, soft tissues were closed primarily (22 fractures) or with split thickness skin grafting (4 fractures) and free flap coverage (2 fractures); temporary spanning external fixation was used in 3 patients. Definitive fracture care was at the discretion of the treating surgeon and consisted of closed reduction without fixation (10 fractures), open reduction and bone grafting (1 fracture), minimal Kirschner wire (K wire) fixation (12 fractures), and formal lateral open reduction and internal fixation (5 fractures). There were no late amputations. There were no deep infections. Twenty-one of the 28 patients with salvaged limbs returned for follow-up evaluation, and 3 additional patients agreed to be interviewed by telephone. The average time to follow-up was 49 months with a range of 25 to 106 months. The overall American Orthopaedic Foot and Ankle Society ankle/hindfoot scores and Maryland Foot Scores were fair to poor. The average SF-36 results were within 1 standard deviation of published Canadian norms. Worse function was observed in patients with plantar wounds. Severely comminuted fractures had the worst function, whereas single joint depression injuries had the best functional outcome. CONCLUSION: Infection is uncommon following open calcaneus fractures treated with aggressive soft tissue management. Patients with plantar wounds and comminuted fractures are expected to have particularly poor functional results.     

Cellular response to pulsed low-dose rate irradiation in X-ray sensitive hamster mutant cell lines

The role of DNA repair mechanisms in the cellular response to low dose rate (LDR) irradiation was studied with the aim to gain insight in the process of sublethal damage (SLD) repair. Chinese hamster cell lines mutated in either DNA single strand break (ssb) repair or DNA double strand break (dsb) repair by non homologous end joining (NHEJ) and homologous recombination (HR), or showing an AT-like phenotype, were irradiated in plateau-phase either at high dose rate (HDR, 3.3 Gy/min) or at pulsed low dose rate (p-LDR, average 1 Gy/h). Cell survival after irradiation was assessed using the clonogenic assay. A change in sensitivity when the dose rate was decreased was observed for all parental cell lines and the DNA ssb repair mutant. No difference in cell survival after p-LDR versus. HDR irradiation was observed for the two NHEJ mutants, the AT-like mutant and the HR mutant. Based on these results we conclude that single strand break repair does not play a role in the dose rate effect. The AT like protein, functional NHEJ and XRCC3 are required for the dose rate effect.     

Proximal tibial fracture stability with intramedullary nail fixation using oblique interlocking screws

OBJECTIVES: The purpose of this study was to evaluate the mechanical stability of oblique interlocking screws in supplementing intramedullary nail fixation of high proximal tibial fractures. DESIGN: In vitro experimental testing.SETTING Orthopaedic biomechanics laboratory, Sunnybrook and Women's College Health Sciences Center. PARTICIPANTS: Ten paired fresh-frozen human cadaver tibiae. INTERVENTION: One tibia of each pair was randomized to be instrumented with an intramedullary nail (M/DN; Zimmer, Warsaw, Indiana), while the other was stabilized with a 13-hole stainless steel lateral tibial head plate (Synthes AO/ASIF). Specimens were tested in varus-valgus (v/v), flexion-extension (f/e) and torsion, before and after a 2-cm gap osteotomy was performed in the proximal segment. Testing of the nailed tibiae was performed with and without oblique proximal screws. Bone density was physically determined by removing a core of trabecular bone from the distal end of each tibia following testing. MAIN OUTCOME MEASUREMENT: Biomechanical construct stability. RESULTS: The addition of the proximally placed oblique screws increased the stability of the nail construct in v/v by 50% (6.8 mm, P < 0.05), in f/e by 47% (7.2 mm, P < 0.05), and in torsion by 18% (3.0 degrees, P < 0.05). There was no significant difference observed between the stability of the intramedullary nail construct with oblique screws and the plated construct. Trabecular bone density had a significant effect in reducing stability (P < 0.05) in nail and plate fixation. CONCLUSION: The addition of oblique interlocking screws significantly improves the stability of a nailed proximal tibia fracture and provides comparable stability to a plate osteosynthesis.     

Evolving Medical Strategies for Low Intensity Conflicts – A Necessity

Military medicine is the development within the art and science which is designed to carry out a specialized, essential and a highly significant mission under the adverse conditions of war. Low Intensity Conflict (LIC) is a mode of warfare which has come to stay and the Indian Military has to confront it as such. It is a campaign of nerves, less military and more psychological, with soldiers inevitably fighting with hands behind their back. The dichotomy the soldier faces, results in high levels of frustration leading to various stress disorders. The key in casualty survival lies in correct and timely psychological first-aid for which every section and platoon commander should be trained. Post Trauma Stress Disorder caused as a result of traumatic experience can deplete unit''s efficiency and therefore needs monitoring for early detection and treatment. Evolving medical strategies for Low Intensity Conflict Operations (LICO), therefore assumes significance.Key Words: Low Intensity Conflict, Post Traumatic Stress Disorder, Stress     

Calorie restriction in nonhuman primates: mechanisms of reduced morbidity and mortality

Long term chronic calorie restriction (CR) of adult nonhuman primates significantly reduces morbidity and increases median age of death. The present review is focused upon an ongoing study of sustained adult- onset calorie restriction, which has been underway for 15 years. Monkeys, initially calorie restricted at about 10 years of age, are now approximately 25 years old. The median life span of these restricted monkeys is increasing, now exceeding that of ad libitum (AL)-fed monkeys. In our laboratory, maximum life span for AL-fed monkeys appears to be about 40 years. Thus, whether CR can also increase maximal life span, as it does in rodents, cannot be determined for at least another 15 years. The earliest detectable positive benefit on morbidity in these monkeys was previously reported as the prevention of obesity. Current evidence, as reviewed here, suggests that much obesity- associated morbidity is also mitigated by sustained calorie restraint in nonhuman primates. Furthermore, probably because of the prevention of obesity, diabetes has also been prevented. Recent findings include the identification of extraordinary changes in the glycogen synthesis pathway, and on the phosphorylation of glycogen synthase in response to insulin. This calorie restriction-induced prevention of morbidity does not require excessive leanness, but is clearly present when body fat is within the normal range of 10 to 22%, and this is likely to be true in humans as well.