Bone modeling and cell-material interface responses induced by nickel-titanium shape memory alloy after periosteal implantation.

The purpose of this study was to evaluate the new bone formation, modeling and cell-material interface responses induced by nickel-titanium shape memory alloy after periosteal implantation. We used a regional acceleratory phenomenon (RAP) model, in which a periosteal contact stimulus provokes an adaptive modelling response. NiTi has thermal shape memory and superelasticity properties uncommon in other implant alloys. So far, there are insufficient data concerning the biocompatibility of NiTi as a bone implant. NiTi was compared to stainless steel (stst) and Ti-6Al-4V. The test implant was placed in contact with the intact femur periosteum, but it was not fixed inside the bone. Histomorphometry with digital image analysis was used to determine the bone formation and resorption parameters. The ultrastructural features of cell-material adhesion were analysed with scanning electron microscopy (FESEM). A typical peri-implant bone wall modelation was seen due to the normal RAP. The maximum new woven bone formation started earlier (2 weeks) in the Ti-6Al-4V group than in the NiTi (P < 0.01) group, but also decreased earlier, and at 8 weeks the NiTi (P < 0.05) and stst (P < 0.005) groups had greater cortical bone width. At 12 and 26 weeks no statistical differences were seen in the histomorphometric values. The histological response of the soft tissues around the NiTi implant was also clearly non-toxic and non-irritating. Cell adhesion and focal contacts were similar between the materials studied by FESEM. We conclude that NiTi had no negative effect on total new bone formation or normal RAP after periosteal implantation during a 26-week follow-up.

Epidural abscess after lumbar discography. A case report.

STUDY DESIGN: The patient who suffered from pain in both lower legs and in whom discography was performed experienced a rare complication after discography. The findings and method of discography is described, as is usefulness of magnetic resonance imaging to image this rare complication. OBJECTIVES: To establish the possibility of getting a spinal epidural abscess after discography, how to make the diagnosis, and how to treat the complication. SUMMARY OF BACKGROUND DATA: Discitis after discography is a well-known complication, but epidural abscess is rare. METHODS: C-reactive protein concentration was measured and was more than 100 mg/L. Infection was suspected, and antibiotic therapy was started immediately. Magnetic resonance imaging was performed, and the diagnosis became clear. A laminotomy was performed. RESULTS: Symptoms due to epidural abscess disappeared soon after laminotomy. CONCLUSIONS: Some harmful and unpleasant complications are possible after discography. Antibiotic prophylaxis and stiletted needles should be used. Magnetic resonance imaging is the best radiologic procedure to image the complication, and surgery must be performed as soon as possible.

Assessment of tissue viability in frostbite by 99Tcm-HDP scintigraphy: an experimental study in New Zealand white rabbits.

Since the appearance of superficial tissue is often an unreliable indicator of deep tissue viability in cases of frostbite, radionuclide scintigraphy with 99Tcm-disodium oxidronate (HDP) was used to assess changes in tissue viability after experimental freezing and thawing of the rabbit ear. One shaved ear, left or right, of each of eight New Zealand white rabbits was frozen with a glass bottle (diameter of bottom 2 cm) filled with liquid nitrogen (-180 degrees C) for 5 min under Ketalar-Rompun anesthesia, the other ear serving as a control. Radionuclide scintigraphy was performed by giving a bolus intravenous injection of 130-170 MBq (3.5-4.5 mCi) 99Tcm-HDP. Radionuclide imaging was used to follow the development of the demarcation line. Scintigraphy was performed 2 h after frostbite and then after 24 h, 48 h, 1 week and 3 weeks. The frostbitten area seemed macroscopically to be warm and swollen immediately after the induction of frostbite. Scintigraphy showed the frostbitten area to be much warmer than the surrounding tissue for the first week and it was not until after that the first cold spots appeared in the middle of the frostbitten area. The necrotic and vital tissue could easily be distinguished after 3 weeks.

Improved method for detecting knee replacement infections based on extended combined 99mTc-white blood cell/bone imaging.

The purpose of this study was to evaluate whether an extension of the imaging time to 24 h post-injection improves the diagnostic accuracy of technetium-99m-hexamethylpropyleneamine oxime (99mTc-HMPAO) leucocyte imaging in detecting knee replacement infections. Thirty patients were studied, with infection confirmed in eight (27%) and excluded in 22 on the basis of clinical and microbiological findings. Leucocyte imaging was carried out at 2-4 h (routine images) and at 24 h (late images) post-injection. For comparison, bone imaging with technetium-99m-hydroxydiphosphonate (99mTc-HDP) was carried out at arterial, soft tissue and metabolic phases. Late leucocyte imaging was found to be more sensitive (100% vs. 87.5%) and more specific (82% vs. 77%) than routine leucocyte imaging in detecting infections. All the bone imaging methods showed a sensitivity of 100%, whereas the specificity varied from only 5% to 23%. All procedures had high negative predictive values (NPVs) (94 to 100%) for excluding infection. However, the positive predictive value (PPV) was only 28 to 32% for bone imaging and 58% for routine leucocyte imaging, whereas late leucocyte imaging showed a PPV of 67% and a diagnostic accuracy of 87%. The data indicate that late leucocyte imaging may be superior to routine leucocyte imaging for examining patients with symptomatic knee replacements.

99m Tc-ciprofloxacin (Infecton) imaging in the diagnosis of knee prosthesis infections.

The purpose of this study was to evaluate the usefulness of 99mTc labelled ciprofloxacin imaging in detecting the presence of infection in patients with symptomatic knee prostheses. Among 16 randomly selected patients of whom seven had infection based on clinical and microbiological findings and nine did not, 99mTc-ciprofloxacin images were obtained at 1, 4 and 24h after the injection of the tracer. While there was some diffuse non-specific accumulation of 99mTc-ciprofloxacin in large synovial joints and in prosthetic knee joints, the infected knee prostheses were found to show more intensive focal uptake, which also extended outside the synovial cavity. The infection related uptake remained visible in the 24h images, whereas non-specific uptake had a fading tendency at this time point. 99mTc-ciprofloxacin imaging showed diagnostic sensitivity of 86% and a specificity of 78% for correctly classifying the presence of infection. The data indicate that 99mTc-ciprofloxacin imaging may be used in the diagnosis of knee prosthesis infections. Infection-related uptake remains visible in the 24h images and is typically found also outside the synovial cavity, which should be noted in the evaluation of the images.

Comparison of 99mTc ciprofloxacin, 99mTc white blood cell and three-phase bone imaging in the diagnosis of hip prosthesis infections: improved diagnostic accuracy with extended imaging time.

The purpose of this study was to compare the utility of 99mTc labelled ciprofloxacin (Infecton) imaging with the 99mTc white blood cell and three-phase bone imaging procedures for identifying hip prosthesis infection. We studied 30 symptomatic patients in whom infection was confirmed in eight and excluded in 22 cases based on clinical and microbiological findings. 99mTc ciprofloxacin images were obtained at 1, 4 and 24 h after the injection of the tracer, and the data were compared to those obtained from 99mTc leukocyte and three-phase bone imaging. The 99mTc ciprofloxacin imaging correctly identified all true infections. In 13 (59%) of the non-infected patients, non-specific uptake of 99mTc ciprofloxacin was found in the 1-h and 4-h images, which disappeared, however, in the 24-h images. When the early and late 99mTc ciprofloxacin images were compared, the specificity was found to improve from 41% to 95%, positive predictive value from 38% to 89%, and the diagnostic accuracy from 57% to 97%. The accuracy of the conventional 99mTc leukocyte imaging was 90%. Dynamic bone imaging also yielded abnormal findings in all the infected patients although also in 23% of the non-infected patients. Current data indicate that 99mTc ciprofloxacin is a useful method for confirming hip prosthesis infection. The diagnostic efficiency of this method is improved when the imaging time is extended to 24 h post-injection of the tracer.

The formation of the demarcation line at experimental frostbite.

Experiments were carried out to gain a better understanding of the pathogenesis of frostbite and changes at the demarcation line after freezing and thawing and to determine the forming demarcation line as early as possible. These changes were investigated by histochemical techniques, by histofluorescence, by determining noradrenaline content in the tissue and nerve, by scintigraphy and thermography. The experimental animal was New Zealand white rabbit. The frostbite was produced using a small laboratory bottle filled with liquid nitrogen pressing against the shaved skin in the middle of the proximal part of the ear. Enzyme histochemistry was good in demonstrating the demarcation line between irreversibly damaged and healing frostbitten tissue. Especially the reaction to esterase was the clearest, the demarcation line was visible already after one week. The glyoxylic acid-induced fluorescence method was available for showing adrenergic nerves around the vessels and the accumulation of catecholamines in these nerves in the demarcation line. The result of quantitative measurement of catecholamines in the nerve and tissue was similar and the reaction was the most powerful during the first three days. Scintigraphy was better than thermography and necrotic areas in the middle of the frostbitten area became clearly visible after three weeks. It seems that many changes caused by frostbite happen both in tissue and cells. The role of catecholamines in vascular circumstances is important and that's why chemical or surgical sympathectomy could be useful.

Changes in adrenergic nerves and tissue perfusion after freezing injury to the ear skin of rabbits.

The aim of the present study was to investigate by a combined trypan blue and catecholamine fluorescence technique the sequential changes in cutaneous adrenergic nerves, the distribution of blood flow, and vascular permeability at the demarcation line that occurred after experimental cold injury. Nine New Zealand white rabbits weighing 4.0-4.4 kg had frostbite induced by pressing the bottom of a glass bottle 2 cm in diameter filled with liquid nitrogen against the shaved skin of the ear. All the rabbits were anaesthetised with ketamine hydrochloride (Ketamine) and xylazine hydrochloride (Rompun). Specimens were taken one and three days, and two weeks after frostbite. Control samples were taken from the opposite normal ear. Trypan blue was injected into a saphenous vein just before the specimens were taken. The specimens were always taken in the same way and selected so that the probable demarcation line of the frostbite ran across the middle. The glyoxylic acid-induced fluorescence method was used to show the adrenergic nerves. There were no adrenergic nerves around the vessels and no arteriovenous anastomoses in the central area of the injury after one day, but catecholamines had started to accumulate in the adrenergic nerve endings at the margins of the injured area. This accumulation was still more obvious three days after frostbite. Some fluorescent regenerating adrenergic nerves could already be seen at the probable demarcation line two weeks after frostbite. There was increased trypan blue fluorescence near the margin of the injured area after one day, indicating extravasation and vascular damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure of perivascular sympathectomy to remove adrenergic nerves from peripheral vessels of the rabbit ear skin.

A perivascular sympathectomy was performed at the base of the ear artery in 11 New Zealand white rabbits. Two days later three were killed, and the central nerve was cut in the remaining eight. The contralateral ear served as a control. Specimens were taken from the distal parts of both ears two days later and the glyoxylic acid-induced fluorescence method was used to show the adrenergic nerves. The arteries of the normal, control ear were surrounded by a dense plexus of fluorescent adrenergic nerves, which were abolished by perivascular sympathectomy only in the segment from which the adventitia had been removed. The adrenergic innervation was normal proximal to the site of perivascular sympathectomy, but there was a short segment of the central vessel distally in which it was diminished. No changes in adrenergic innervation were found in the distal third of the rabbit ear.

Penetration of Ullevaal hip screw into the pelvis.

The fracture of the femoral neck is usually treated operatively with screw osteosynthesis or prosthesis. There have been reported a rare complication both with screws and lag screws used in hip fractures, both can penetrate into the pelvis postoperatively. We present two cases with this similar rare complication when using Ullevaal screws. Both patients were reoperated on with a total hip arthroplasty (THA). We think that the exact anatomical reposition and good operation technique should make this complication even more rare. The canal should always be drilled only to the line of the fracture, so that there is no canal for the screw to squeeze further. To prevent penetration some kind of cap fixed the lateral end of the screw could also be worth while.

MR imaging in tibial shaft fractures. A potential method for early visualization of delayed union.

PURPOSE: To evaluate the relationship between MR findings at the fracture site during the healing process and the outcome of patients with tibial shaft fracture. MATERIAL AND METHODS: Twelve consecutive patients with an uncomplicated tibial fracture treated conservatively were imaged by MR 1 to 3 days, 1 week, 3 weeks, 6 weeks and 12 weeks after the trauma. MR imaging consisted of sagittal/coronal T1-weighted, T2-weighted, proton density, short-tau inversion recovery, and contrast-enhanced T1-weighted spin-echo images. The images were analysed for the extent of signal pathology in the bone marrow adjacent to the fracture, the extent of soft tissue oedema, and the intensity and homogeneity of the contrast enhancement of the callus. RESULTS: The differences between normal (n=7) and delayed union (n=5) were observed within 3 to 6 weeks after the trauma, mainly in the homogeneity of the callus in T2-weighted and contrast-enhanced images. CONCLUSION: MR imaging is a potentially valuable method for early visualization of delayed union in tibial shaft fractures.

A proximal fixed anatomic femoral stem reduces stress shielding.

In 24 patients with total hip replacement using a short anatomic femoral stem, bone mineral density (BMD) was measured after a 7-year follow-up using dual-energy X-ray absorptiometry. The contralateral side was used as a control. The BMD on the side of the prosthesis was lower by a mean of 7% than that on the control side. The difference was greatest in the area of the calcar and laterally and proximally around the stem. BMD at the metaphyseal and diaphyseal areas were the same as on the contralateral side. The bone loss around the proximal aspect of the stem may be related to the proximal porous coating. It is concluded that stress shielding can be diminished by appropriate design of the femoral component.

Noradrenaline content of the tissue and nerve in the rabbit ear after freezing injury.

The aim of this study was to investigate the development of the demarcation line in the rabbit ear upon injury by experimental freezing and thawing. For this purpose the sequential changes in noradrenaline (NA) content in the tissue and nerve of the ear were determined by liquid chromatography. Frostbite was inflicted with a glass bottle filled with liquid nitrogen and specimens were taken from the injured area, the probable demarcation line area and the healthy area 1, 3, and 7 days after frostbite. Control samples were taken from the normal contralateral ear. Tissue NA levels in the injured area and the probable demarcation line area were significantly lower than those in corresponding areas of the control ear after 1 day. Day 3 NA levels in the demarcation line area were 90% higher than those on Day 1 in this area and were not significantly different from Day 3 levels in the control ear. By Day 7, NA levels in the demarcation line area were down to 70% of the Day 3 levels. NA levels in the central nerve at the probable demarcation line were much higher than those in the control ear nerve and also showed a peak on Day 3. In conclusion, the results suggest that NA is released from the adrenergic nerves and the reaction at the probable demarcation line is strongest on the third day.

Enzyme histochemical reactions at the demarcation line in frostbite: an experimental study on rabbits.

Eleven frostbites were induced on the ears of seven New Zealand White rabbits and specimens were taken from the lesion after 1, 4 and 8 hours, and from ten further frostbites on the ears of six rabbits for examination 1, 3 and 7 days later. The specimens were taken at the border between the frozen and non-frozen skin. NADH-diaphorase, alkaline phosphatase and esterase were demonstrated histochemically in the sample, which was also studied by haematoxylin and eosin staining. Five ears served as controls. Some granulocytes could be seen accumulating in the vessels and in the dermis at the border of the frostbite area after only 1 hour, and other enzyme rich cells (macrophages) also began to appear. After 4 hours the inflammation was quite obvious with the enzyme reactions clearly observable in the sections. After 8 hours there was no marked difference compared with the 4-hour picture. It was only after 3 days that the line of demarcation between the normal and frostbite tissue could be seen clearly. This was oblique in some specimens and vertical in others. The degeneration in the lesion could best be demonstrated by the NADH-diaphorase and esterase reactions and the early inflammation by the alkaline phosphatase reaction.

Assessment of tissue viability by thermography after experimentally produced frostbite of the rabbit ear.

Since it is difficult and time-consuming to monitor the formation of a demarcation line in frostbite by visual inspection only, thermography was used to study experimental freezing injuries of the rabbit ear. In 8 rabbits, anesthetized with ketamine hydrochloride and xylazine hydrochloride, frostbite was induced by pressing the bottom of a glass bottle 2 cm in diameter, filled with liquid nitrogen against the shaved ear skin. Thermography was performed on both ears after 2, 24, and 48 hours, and one and 3 weeks. At 2 to 48 hours the frost-bitten area was clearly warmer than the surroundings, after one week there were ill-defined diffuse cold spots in the injured area, and after 3 weeks a cold area had become clearly demarcated with a warm zone between the cold area and the surroundings. Thermography is an easy, noninvasive method for monitoring thermal changes after experimental frostbite, but its clinical value is as yet unresolved.

Multiplanar and 3D CT of acetabular fractures.

PURPOSE: To establish a standard protocol for the multiplanar (MPR) and 3D shaded surface display (SSD) reconstruction of CT data on acetabular fractures, and to assess the usefulness of these reformats. MATERIAL AND METHODS: Acetabular fractures in 15 patients were imaged by means of plain radiographs, transaxial CT, MPR reformats, and SSD reformats. RESULTS: The classification of the acetabular fracture was revised in 7/15 cases when the transaxial CT images were read after the plain radiographs. Although the MPR and SSD reformats did not alter the classification, they did add to the degree of confidence in the diagnosis in 9/15 cases. In 2 patients, the MPR and SSD reformats indicated operative instead of conservative treatment. In the MPR reformats, the following views were considered essential in all cases: (a) along the anterior column; (b) along the posterior column; and (c) along both columns and the inferior ramus. In the SSD reformats, the following views were considered essential in all cases: (d) the latero-caudal en face view into the acetabulum; and 180 degrees opposite to this, (e) the medio-cranial view (facing the quadrilateral plate). In 10/15 cases, these views were all that was needed for classification. It was, however, essential to remove the femur from the images before reconstructing the SSD views. CONCLUSION: Complex acetabular fractures with displacement should be evaluated by means of transaxial CT and additional MPR and SSD reformats. The use of appropriate standard MPR and SSD views shortens the time required to produce the reformats and thereby maximizes the benefit gained.

A simple device for the stereoscopic display of 3D CT images.

We describe a simple device for creating true 3D views of image pairs obtained at 3D CT reconstruction. The device presents the images in a slightly different angle of view for the left and the right eyes. This true 3D viewing technique was applied experimentally in the evaluation of complex acetabular fractures. Experiments were also made to determine the optimal angle between the images for each eye. The angle varied between 1 degree and 7 degrees for different observers and also depended on the display field of view used.

Effect of perivascular sympathectomy on distal blood flow in the rabbit forepaw. A dynamic isotope experiment with Tc99m.

Perivascular sympathectomy, used for treating patients suffering from vasospastic disorders of the hand, is believed to cause an increase in the distal blood flow. Its effects were examined here by performing the operation on the metacarpal arteries of the left forepaw of ten New Zealand White rabbits, the right forepaw serving as a control. Blood flow was measured by Tc99m radionuclide angiography five days before the operation and three days and two and a half weeks after it. There was no statistically significant postoperative increase in blood flow in the distal parts, so that it may be concluded that at least in this experimental model, the distal sympathectomy did not have any such effect.