Median nerve entrapment during closed reduction of antebrachium fracture in a child.

This is a case report of a four-year-old boy who suffered a forearm fracture managed with closed reduction and casting for six weeks. Postoperatively, the patient showed symptoms of median nerve affection which was misinterpreted as neuropraxia. Ultrasonography of the forearm revealed that the median nerve was trapped in the radius fracture site. The patient underwent a second operation with neurolysis and nerve grafting. This case report highlights the use of ultrasonography in the diagnostics of nerve entrapment neuropathy.

Removal of broken PRECICE Stryde intramedullary lengthening nails.

This paper describes two different techniques for removal of broken Precice Stryde intramedullary bone lengthening nails, which unlike trauma nails are solid containing mechanical components. Consequently, surgeons face unique challenges when these implants brake within medullary canal. Here, we present our surgical approach for removal of three broken implants. In one patient (46kg) both Ø10mm femoral Stryde implants (max. weight allowance 68kg) broke through the proximal locking screw hole preoperatively on the right side and intraoperatively on the left side (413 and 504 days after index surgery respectively). The third Ø11.5 femoral nail broke through the area containing the magnet (55kg patient, 325 days after index surgery). LEVEL OF EVIDENCE: IV.

[Children with obvious fractures may have sustained multiple injuries].

In this case report, a rare case of a distal forearm fracture in conjunction with an initially overlooked ipsilateral Monteggia Bado type III injury highlights the learning objectives of this case report. Multiple fractures occur in approximately 1% of all fracture cases in children and adolescents, and meticu-lous physical and appropriate radiographic examinations are mandatory in order to diagnose all injuries. Arthrography is a viable option for dynamic evaluation of joint congruity and stability intraoperatively.

Strontium and bone nanostructure in normal and ovariectomized rats investigated by scanning small-angle X-ray scattering.

The effect of SrCl(2) treatment on bone nanostructure in a rat ovariectomy model was studied using scanning small-angle X-ray scattering (sSAXS). Twelve 6-month-old female Wistar rats were used. Six animals were ovariectomized (+ovx) and six were left intact after sham surgery (-ovx). Six animals, three +ovx and three -ovx, were treated with 4 mmol SrCl(2) (aq)/kg/day (+Sr), whereas the remaining six received placebo (-Sr) for 140 days. Rats were labeled with flourochromes at days 7, 126, and 136. Femoral cross sections were studied using fluorescence microscopy, scanning electron microscopy including energy-dispersive X-ray analysis, and sSAXS. The SAXS data comprised about 5,500 measurements and provided information about mineral crystal thickness and orientation in new and old bone. The newly formed bone contained higher levels of Sr(2+) in +Sr than in -Sr animals, indicating that the Sr(2+) was incorporated into the new bone. Mineral plates were significantly thicker in old bone, 2.62 nm (95% CI 2.58-2.66), than in new bone, 2.41 nm (95% CI 2.36-2.46). Surprisingly, mineral plates in new bone were significantly thicker (2.52 [95% CI 2.47-2.57] nm vs. 2.41 [95% CI 2.36-2.46] nm, P = 0.017) in +ovx rats than in -ovx rats. However, no significant effect of SrCl(2) on mineral plate thicknesses in new bone was observed. The statistical model yielded estimates of the difference in bone mineral plate thickness induced by Sr. The estimated effect of Sr was -0.09 (95% CI -0.21 to 0.03) and 0.02 (95% CI -0.10 to 0.14) nm for new bone in -ovx and +ovx rats, respectively.

Nanostructure of the neurocentral growth plate: Insight from scanning small angle X-ray scattering, atomic force microscopy and scanning electron microscopy.

In this study, the experimental techniques scanning electron microscopy (SEM) including energy-dispersive X-ray analysis, atomic force microscopy (AFM) and scanning small angle X-ray scattering (SAXS) have been exploited to characterize the organization of large molecules and nanocrystallites in and around the neurocentral growth plate (NGP) of a pig vertebrae L4. The techniques offer unique complementary information on the nano- to micrometer length scale and provide new insight in the changes in the matrix structure during endochondral bone formation. AFM and SEM imaging of the NGP reveal a fibrous network likely to consist of collagen type II and proteoglycans. High-resolution AFM imaging shows that the fibers have a diameter of approximately 100 nm and periodic features along the fibers with a periodicity of 50-70 nm. This is consistent with the SAXS analysis that yields a cross-sectional diameter of the fibers in the range of 90 to 112 nm and a predominant orientation in the longitudinal direction of the NGP. Furthermore, we find inhomogeneities around 7 nm in the NGP by SAXS analysis. Moving towards the bone in the direction perpendicular to the growth plate, a systematic change in apparent thickness is observed, while the large-scale structural features remain constant. In the region of bone, the apparent thickness equals the mean mineral thickness and increases from 2 nm to approximately 3.5 nm as a function distance from the NGP. The mineral particles are organized as plates in a rather compact network structure. We have demonstrated that SEM, AFM and SAXS are valuable tools for the investigation of the organization of large molecules and nanocrystallites in the NGP and adjacent trabecular bone. Our findings will be an important basis for future work into identifying the defects on nanometer length scale responsible for idiopathic scoliosis and other growth-plate-related diseases.

The influence of alendronate treatment and bone graft volume on posterior lateral spine fusion in a porcine model.

STUDY DESIGN: An experimental animal study with randomized, paired control design was conducted using a porcine model. OBJECTIVES: The aim of this study was to evaluate the influence of alendronate treatment and the significance of different amounts of bone graft on posterior lateral spine fusion. SUMMARY OF BACKGROUND DATA: Treatment with bisphosphonates inhibits osteoclast-induced bone resorption and increases bone quality and density. It has been widely used clinically for treatment of osteoporosis. Bisphosphonates have been reported to elongate the callus remodeling process during fracture healing. Bisphosphonate treatment may modify bone graft healing and the remodeling process in spine fusion. The bone resorption phase exists during the healing process. Extensive bone graft resorption could reduce the basis for new bone formation, which could be an important factor for failure of spine fusion. Furthermore, different amounts of initially applied bone graft may influence spine fusion rate and bone graft incorporation process. METHODS: Twenty-two pigs were included in the study. Eleven pigs in the treatment group received alendronate 10 mg/day p.o. for 3 months after surgery. The other 11 pigs received no bisphosphonate and served as control group. Posterior lateral fusion with the CD Horizon system was performed on the lumbar spine using different amounts of autograft (4 g on one side and 8 g on the other side) in all animals. The fusion was evaluated using radiograph, CT scan, and histomorphometry at 3 months after operation. RESULTS: There was no statistical difference in either fusion rate or fusion mass volume between the two groups. The fusion rate based on radiograph was 75% on the 8-g autograft side and 45% on the 4-g side (P < 0.05). The mean volume of fusion mass was 2.36 cm3 on the 4-g side and 3.29 cm3 on the 8-g side (P < 0.01). No difference was found in either trabecular bone volume or fusion rate between treatment and control groups using histologic evaluation.The treatment group showed a higher fibrous tissue volume(P < 0.05), higher proportion of woven bone structure(P < 0.001), and lower bone marrow volume (P = 0.088) in the fusion mass. Different amounts of bone graft did not change the tissue composition of the fusion mass. CONCLUSIONS: Alendronate treatment in this study decreased fusion mass remodeling without inhibiting fusion rate. Increased amounts of autologous bone graft could improve the fusion rate in this experimental spine fusion study.

Healing properties of allograft from alendronate-treated animal in lumbar spine interbody cage fusion.

This study investigated the healing potential of allograft from bisphosphonate-treated animals in anterior lumbar spine interbody fusion. Three levels of anterior lumbar interbody fusion with Brantigan cages were performed in two groups of five landrace pigs. Empty Brantigan cages or cages filled with either autograft or allograft were located randomly at different levels. The allograft materials for the treatment group were taken from the pigs that had been fed with alendronate, 10 mg daily for 3 months. The histological fusion rate was 2/5 in alendronate-treated allograft and 3/5 in non-treated allograft. The mean bone volume was 39% and 37.2% in alendronate-treated or non-treated allograft (NS), respectively. No statistical difference was found between the same grafted cage comparing two groups. The histological fusion rate was 7/10 in all autograft cage levels and 5/10 in combined allograft cage levels. No fusion was found at all in empty cage levels. With the numbers available, no statistically significant difference was found in histological fusion between autograft and allograft applications. There was a significant difference of mean bone volume between autograft (49.2%) and empty cage (27.5%) (P<0.01). In conclusion, this study did not demonstrate different healing properties of alendronate-treated and non-treated allograft for anterior lumbar interbody fusion in pigs.

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is associated with osteoporotic vertebral fractures, but is a weak predictor of BMD.

Osteoporosis is a common disease with a strong genetic component. Linkage studies have suggested linkage between BMD and loci on chromosome 1. The MTHFR gene is located on chromosome 1. MTHFR catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methylenetetrahydrofolate, which is used for homocysteine methylation to methionine. The rare genotype (TT) of the C677T polymorphism has previously been demonstrated to be associated with increased plasma homocysteine levels in individuals with inadequate plasma folate levels. Recently, the TT genotype has been found to be associated with reduced bone mass. We therefore examined if the C677T polymorphism in the MTHFR gene is associated with changes in bone mass and risk of osteoporotic fractures in 388 osteoporotic patients and 336 normal individuals. The distributions of the genotypes CC, CT and TT in women with osteoporotic vertebral fractures and normal controls were 43.5%, 42.2% and 14.3% and 52.0%, 42.0% and 8.0%, respectively, chi2 = 5.62, P = 0.06. Since studies of the functionality of this polymorphism have revealed that only the TT genotype is associated with biochemical changes, we also compared the prevalence of the TT genotype versus the CT- and CC genotypes in patients and controls and found that the TT genotype is significantly more common in women with vertebral fractures (14.3%) compared with normal controls (8.0%), chi2 = 4.31, P < 0.05. Logistic regression analysis demonstrated that vertebral fractures were significantly associated with BMD (lumbar spine) and height but only marginally with the MTHFR genotype (P = 0.06). Multiple linear regression analysis revealed that weight, age and the MTHFR polymorphism were predictors of lumbar spine BMD in women. However, age- and gender-corrected BMD of the lumbar spine and the hip was not significantly different between MTHFR genotypes. Furthermore, individuals with the TT genotype did not have BMD significantly lower than the combined group of individuals with the CT- or CC genotypes. In conclusion, we have demonstrated that the rare TT genotype of the C677T polymorphism in the MTHFR gene is associated with increased risk of osteoporotic fractures in women and a weak predictor of lumbar spine BMD.

Methylprednisolone enhances contraction of porcine femoral head epiphyseal arteries.

The pathomechanism of steroid-induced femoral head necrosis is thought to be disturbed femoral head blood flow. We hypothesize that methylprednisolone increases vasocontraction of femoral head epiphyseal arteries, thereby reducing femoral head blood flow. Nine immature female domestic pigs were randomly selected from a group of 18 to receive 24-hour methylprednisolone treatment, whereas the nine remaining pigs received the placebo control in a blinded fashion. After sacrifice, lateral epiphyseal artery segments from the femoral heads were mounted as ring preparations on a small vessel myograph. Isometric active tension was measured in relation to cumulating doses of the vasoconstrictors noradrenaline and endothelin-1, and the vasodilator bradykinin. Vasocontraction to noradrenaline was not altered by methylprednisolone. Bradykinin elicited a concentration-dependent vasodilation which was lower in the corticosteroid-treated vessels. Vasoconstriction to endothelin-1 was stronger in the corticosteroid-treated vessels. Our data indicate that methylprednisolone enhances contraction of femoral head lateral epiphyseal arteries and may decrease femoral head blood flow. To our knowledge, this pathomechanic factor in femoral head necrosis has not been described before.

Femoral head blood flow reduction and hypercoagulability under 24 h megadose steroid treatment in pigs.

The pathogenesis of corticosteroid-induced femoral head necrosis is assumed to be ischemia. The purpose of this study was to investigate the perfusion pattern of the femoral head and plasma coagulability during 24 h corticosteroid megadose treatment, as recommended by the National Acute Spinal Cord Injury Studies (NASCIS), in the awake big animal model. Blindedly, 9 animals underwent megadose methylprednisolone infusion (30 mg/kg intravenously as an initial bolus, followed by 5.4 mg/kg/h for further 23 h) while 9 animals served as placebo treated controls. Regional blood flow of the systematically subdivided femoral head, proximal femur, acetabulum, and soft tissue hip regions was investigated by the microsphere technique at steady state (phase 1), after the initial bolus infusion (phase 2), and after the completed treatment (phase 3). Plasma coagulability was examined in phases 1 and 3. Blood flow of the femoral head epiphysis and metaphyseal cancellous bone was unchanged after one hour of steroid infusion, but decreased after the completed treatment at 24 h in the experimental group. Femoral head blood flow reduction was global without a tendency to more pronounced blood flow decrease in any subregion. Plasma fibrinogen was significantly higher after 24 h of steroid infusion than in the placebo control group. 24 h high dose methylprednisolone treatment causes femoral head blood flow reduction and hypercoagulability of plasma in the normal awake immature pig. These findings may be pathogenetic factors in the early stage of steroid-induced osteonecrosis.

Bone ingrowth characteristics of porous tantalum and carbon fiber interbody devices: an experimental study in pigs.

BACKGROUND CONTEXT: In preclinical and clinical joint replacement applications, porous tantalum has been shown to be osteoconductive and effective for biological fixation. Relatively little research has been undertaken to investigate the porous tantalum implants for potential application in intervertebral spinal fusion. PURPOSE: The current study was designed to assess the radiographic and histological performance of porous tantalum and carbon fiber devices in the porcine anterior lumbar interbody fusion (ALIF) model. STUDY DESIGN: A total of 10 Danish Landrace pigs underwent a three-level anterior intervertebral lumbar arthrodeses at L2-L3, L4-L5 and L6-L7. Each level was randomly allocated to one of three implants: a solid piece of porous tantalum, a porous tantalum ring packed with autograft or a carbon fiber cage, likewise packed with autograft. Two staples for fixation were supplemented in front of implant. METHODS: Pigs were sacrificed 3 months after operation. Specimens were evaluated by plain radiography, conventional tomography and histology. RESULTS: Bone graft filled into the central hole of the porous tantalum ring was less than that of the carbon fiber cage (p<.001). Radiolucencies around the porous tantalum solid were significantly higher than the carbon fiber cage (p=.02) and were not different between the porous tantalum ring and the carbon fiber cage. The bone volume in the hole of implants, within the pores of the porous tantalum and in the implant interface did not differ between implants. Bone volume in the hole of the porous tantalum ring did not differ from that of the adjacent vertebral bone; however, it was significantly different in the carbon fiber cage and the adjacent vertebral bone (p=.005). CONCLUSIONS: In this porcine ALIF model, the radiographic and histological appearances of the porous tantalum ring were equivalent to those of the carbon fiber cage. The high presence of radiolucencies and fibrous tissue layer at the vertebrae-implant interface suggests that an initial stabilizing biomechanical environment is important in order to achieve bone ingrowth in the interbody fusion devices in this ALIF model.

Effect of alendronate on bone ingrowth into porous tantalum and carbon fiber interbody devices: an experimental study on spinal fusion in pigs.

Recent studies have reported that bisphosphonates reduce the resorption of grafted bone and inhibit bone resorption at a bone-implant interface. However, it is not known whether bisphosphonates affect bone ingrowth into porous biomaterial or spine fusion interbody devices with an autograft. In this study, 18 pigs (9 in each group) underwent anterior intervertebral lumbar arthrodeses at L2-3, L4-5 and L6-7. Each level was randomly allocated to one of the 3 implants: a solid piece of porous tantalum (Hedrocel), a porous tantalum ring or a carbon fiber cage both packed with an autograft. Alendronate was given orally to one of the groups. The radiographic and histological findings in the two groups 3 months after operation were similar in these devices. Histological examination showed that the original graft was entirely replaced by new trabecular bone in both groups. On histomorphometric analysis, the bone volume fraction, both inside the central hole of porous tantalum ring and in the porous tantalum, was larger in the pigs given alendronate than in the controls, but the fraction inside and around the central hole of the carbon fiber cage was not affected by this treatment. Short-term alendronate treatment, in a relatively low dose, does not impair the formation of new bone, but increases bone ingrowth into the central hole of the porous tantalum ring and the pores of the porous tantalum in this porcine model. This may be an effective way to enhance early biologic fixation of porous intervertebral implants.

Spinal blood flow in 24-hour megadose glucocorticoid treatment in awake pigs.

OBJECT: Because of the controversy regarding the benefits of 24-hour administration of methylprednisolone in patients with spinal cord injury (SCI), it is important to investigate its mechanism of action and side effects. This study was conducted to determine if high-dose methylprednisolone modulates neural and vertebral blood flow in an awake large-sized animal model without SCI. METHODS: From a group of 18 immature female domestic pigs born to nine different litters, nine animals were randomly allocated to receive methylprednisolone treatment, whereas their nine female siblings served as controls. Drug or placebo was applied in a blinded fashion by a third person not involved in the study. The following treatment for SCI, as suggested by the North American Spinal Cord Injury Study, was administered to the awake pig: methylprednisolone (30 mg/kg of body weight) was infused into the jugular vein during a 15-minute period, followed by a 45-minute pause, and the infusion was maintained over a 23-hour period at a dose of 5.4 mg/kg body weight/hour. By means of the radioactive tracer microsphere technique, spinal cord blood flow (SCBF) was measured in the awake standing pig in the cerebrum, and in spinal gray and white matter, nerve roots, endplates, cancellous bone, cortical shell, and T12-L2 discs. Blood flow was measured before, 1 hour after initiation of infusion, and 24 hours postinfusion. Examination of blood flow in the neural and vertebral tissue samples, as well as of central hemodynamics, revealed no significant difference between the experimental and control groups, and this parity was maintained throughout the experimental phases. CONCLUSIONS: In the awake pig model, 24-hour methylprednisolone treatment does not modulate cerebral or SCBF, nor does it increase the risk for vertebral osteonecrosis by producing vertebral ischemia.