A new uncemented hydroxyapatite-coated femoral component for the treatment of femoral neck fractures: two-year radiostereometric and bone densitometric evaluation in 50 hips.

Our aim in this pilot study was to evaluate the fixation of, the bone remodelling around, and the clinical outcome after surgery of a new, uncemented, fully hydroxyapatite-coated, collared and tapered femoral component, designed specifically for elderly patients with a fracture of the femoral neck. We enrolled 50 patients, of at least 70 years of age, with an acute displaced fracture of the femoral neck in this prospective single-series study. They received a total hip replacement using the new component and were followed up regularly for two years. Fixation was evaluated by radiostereometric analysis and bone remodelling by dual-energy x-ray absorptiometry. Hip function and the health-related quality of life were assessed using the Harris hip score and the EuroQol-5D. Up to six weeks post-operatively there was a mean subsidence of 0.2 mm (-2.1 to +0.5) and a retroversion of a mean of 1.2° (-8.2° to +1.5°). No component migrated after three months. The patients had a continuous loss of peri-prosthetic bone which amounted to a mean of 16% (-49% to +10%) at two years. The mean Harris hip score was 82 (51 to 100) after two years. The two-year results from this pilot study indicate that this new, uncemented femoral component can be used for elderly patients with osteoporotic fractures of the femoral neck.

Patient-circumference-adapted dose regulation in body computed tomography. A practical and flexible formula.

PURPOSE: To illustrate that the attenuation formula based on monochromatic radiation in homogeneous objects may be used for dose regulation in body computed tomography (CT) based on patient circumference and using a simple cloth measuring tape. MATERIAL AND METHODS: Based on the attenuation formula for monochromatic radiation the following Microsoft Excel equation was derived: mAs(x) = mAs(n)*EXP((0.693/ HVT)*(O(x)-O(n))/PI()), where mAs(x) (milliampere second) in a patient with circumference O(x) is calculated based on the nominal mAs(n) set for a reference patient with the circumference O(n) with regard to indication, scan protocol, and available CT scanner. The HVT = half-value thickness (object thickness change in cm affecting mAs setting by a factor of 2) resulting in the least mAs difference compared with published studies investigating the mAs needed for constant image noise in abdominal CT phantoms at 80-140 kVp was evaluated. Clinically recommended HVT values were applied to 20 patients undergoing abdominal CT using 130 effective mAs and 94 cm circumference as nominal settings, and an HVT of 9 cm. RESULTS: The object-sized dependent mAs for constant image noise at 80-140 kVp in 10-47 cm diameter abdominal phantoms (31-148 cm in circumference) differed, with few exceptions, by no more than 10% from those obtained with our formula using an HVT of 3.2-3.8 cm. An HVT of 9 cm in the patient study resulted in the same image noise-patient circumference relation as a phantom study using a "clinically adapted mAs" resulting in an acceptable noise according to diagnostic requirements. Clinical experiences recommend an HVT of about 8 cm for abdominal CT and 12 cm in thoracic CT. Changing the kVp from 120 to 80, 100, or 140 requires a mAs change roughly by factors of 4, 2, and 0.6, respectively, for constant image noise. CONCLUSION: Until fully automatic automatic exposure control systems have been introduced, applying the formula in a computer program provides the radiologist with an easy, quick, flexible, and practical instrument for reasonably good patient-sized adjusted exposure levels in clinical practice.

Cauda equina syndrome as a postoperative complication in five patients operated for lumbar disc herniation.

STUDY DESIGN: A retrospective analysis of records and radiographs in five patients who developed acute cauda equina syndrome after surgery for lumbar disc herniation. OBJECTIVES: To postulate as a possible pathophysiologic mechanism the venous congestion caused by preexisting spinal stenosis and to present a management plan: extended decompression within 48 hours. SUMMARY OF BACKGROUND DATA: Cauda equina syndrome is reported as a sequela in 0.2%-1% of the surgeries for lumbar disc herniation. There is, however, no consensus on the possible pathophysiologic mechanism to the complication or to its management. METHODS: Preoperative investigations consisted of magnetic resonance imaging, or myelography and computed tomography. There was a good correlation between clinical appearance and radiographic findings in all patients. When the complication became apparent in four of the patients, they were investigated with magnetic resonance imaging and reoperated on within 48 hours with wide decompressions. RESULTS: The index operation was reported uneventful in all patients. Postoperative magnetic resonance imaging did not show the cause of the cauda equina syndrome, nor could this be established at the reoperation. Before surgery, all five patients had preexisting narrowing of the spinal canal. In no case was the lumbosacral disc the index level. Two patients recovered fully, whereas the other three experienced varying degrees of residual symptoms. There was no correlation between the end result and the delay until secondary decompression. CONCLUSION: Relative spinal stenosis may contribute to the development of cauda equina syndrome after surgery for lumbar disc herniation. A venous congestion can be triggered by postoperative edema, leading to nerve root ischemia. The treatment of choice seems to be extended decompression within 48 hours.

Urinary tract infection in patients with hip fractures.

We found that 23% of 435 patients treated for a femoral neck fracture in our department also were treated for a urinary tract infection during their hospital stay. The most common pathogen was Escherichia coli, sensitive for mecillinam in 98% of the cases. The most frequently used antimicrobial agent was a broad-spectrum antibiotic, fluoroquinolon, although the most reasonable choice would have been a non broad-spectrum agent such as mecillinam. Catheterization was not a predisposing factor for urinary tract infection, but a poor medical condition and female sex were. We did not find a higher mortality rate among patients with a urinary tract infection.

Acute spinal epidural abscess without concurrent spondylodiscitis. Successful closed treatment in 10 cases.

We performed a retrospective survey of the clinical records and radiological examinations of 10 patients with a diagnosis of spinal epidural abscess, without spondylodiscitis. All patients had an acute onset of fever and local or radiating back pain. 3 patients had mild, and 1 patient severe neurological symptoms. The diagnosis and subsequent regression of the abscess after treatment were verified by MRI. In all cases, the imaging findings included signs of septic arthritis in an adjoining facet joint. 7/10 abscesses were located in the lumbar region. Blood cultures showed Staphylococcus aureus as the etiological agent in 8/10 patients. In 2 cases, no agent was found, probably due to ongoing antibiotic therapy when the cultures were taken. All patients were treated successfully using antibiotics alone, with complete regression of the neurological symptoms.

Open-wedge osteotomy by hemicallotasis or the closed-wedge technique for osteoarthritis of the knee. A randomised study of 50 operations.

We describe the results of 50 operations carried out on 46 patients with medial osteoarthritis of the knee of Ahlbäck grade 1 to 3. Patients were randomised either to a closed-wedge high tibial osteotomy (HTO) or an open-wedge procedure based on the hemicallotasis technique (HCO). Their median age was 55 years (38 to 68). The preoperative median hip-knee-ankle (HKA) angle was 171 degrees (164 to 176) in the HTO group and 173 degrees (165 to 179) in the HCO group. After six weeks, the median HKA angle was 185 degrees (176 to 194) in the HTO group and 184 degrees (181 to 188) in the HCO group. In the HTO group, seven patients were within the range of 182 degrees to 186 degrees compared with 21 in the HCO group (p < 0.001). One year later, ten HTO patients were within this range while the HKA angulation in the HCO group was unchanged. At two years the numbers were 11 and 18, respectively. We evaluated the clinical results on the Hospital for Special Surgery, Lysholm and Wallgren-Tegner activity scores, and patients completed part of the Nottingham Health Profile questionnaire. An impartial observer at the two-year follow-up concluded that all scores had improved, but found no clinical differences between the groups.

Assessment of image post-processing and of measuring assistance tools in computed radiography. Evaluation of the weight-bearing knee.

PURPOSE: A system for the examination and measurement of the weight-bearing knee was adapted to computed radiography (CR) and to a picture archiving and communication system (PACS). The examination and measurement system was developed on examination equipment used for QUESTOR precision radiography (QPR). For an easier and more standardised localisation of bony landmarks on the screen, 4 measuring assistance tools (MATs) were developed. The aim of this study was to evaluate the usefulness of the tools developed and of image post-processing, specifically as magnification (zoom) and filtering (edge enhancement), by determining intra-observer variation in the measurement of angles and distances. MATERIAL AND METHODS: The original QPR measurement program, generating 19 angles and distances corrected for parallax and magnification, was converted and installed on a multi-modality workstation (Imtec Image 1200). A CR system (Fuji AC-2) was used for the generation of the related images and the measurements were made on the workstation. Four unilateral examinations of weight-bearing knees were undertaken. These examinations were measured twice under 5 different measurement conditions by 4 viewers. RESULTS AND CONCLUSIONS: The most important factor in reducing intra-observer variation was the ability to magnify (zoom) the images. The MATs also reduced variation. Filtering (edge enhancement), however, did not affect precision.

Serum albumin and deep infection in femoral neck fractures. A study of 437 cases followed for one year.

Four hundred and thirty-seven patients with femoral neck fractures were studied to determine the value of serum albumin estimations on admission. Serum albumin is a good predictor of mortality, and patients with low levels should be given additional nutritional support. We found that the serum albumin level is not useful in predicting deep wound infection. The infection rate of 3% does not justify the use of antibiotic prophylaxis in general.

Autologous blood transfusion in hip replacement. No effect on blood loss but less increase of plasminogen activator inhibitor in a randomized series of 80 patients.

80 patients underwent total hip replacement (THR) for primary coxarthrosis. In a randomized study, half of them donated 2 units of blood before operation. One unit was collected 4 weeks and one 2 weeks before the scheduled THR. All except 1 patient tolerated the predonations well. Total blood losses were similar in both groups. Additional bank blood was given in 7/38 in the predonation group, compared to 29/40 in the control group. Hemostatic parameters were studied in 10 consecutive patients in each group. Plasminogen activator inhibitor 1 (PAI-1), a possible risk parameter for thromboembolism, was significantly more increased postoperatively in the control group, which received only homologous blood. Platelet count, prothrombin complex, antithrombin III and von Willebrand factor antigen were significantly reduced and C reactive protein increased after surgery in both groups. We recommend predonation of 2 autologous units before a primary THR. In most cases, such predonation makes homologous blood transfusion unnecessary. The use of predonated blood causes no reduction of blood loss in THRs, but the increase in PAI-1 seen after homologous transfusions is avoided.

Monoclonal antibodies recognizing nitrite oxidoreductase of Nitrobacter hamburgensis, N. winogradskyi, and N. vulgaris.

Three monoclonal antibodies (MAbs) against nitrite oxidoreductase (NOR) of Nitrobacter hamburgensis were produced. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting analysis of the purified enzyme showed that the MAbs named Hyb 153.1 and Hyb 153.3 both recognized a protein with a molecular mass of 64,000 Da, while Hyb 153.2 recognized a protein with a molecular mass of 115,000 Da. The molecular masses of these proteins are in the same range as those of the proteins of the alpha (115,000-Da) or beta (65,000-Da) subunit of the NOR. By using the antibodies, the amount of NOR was shown to be dependent on the growth conditions. The highest level of NOR was observed in N. hamburgensis when cells were growing mixotrophically. Analysis of whole-cell extracts of N. hamburgensis, N. winogradskyi, and N. vulgaris indicated serological homology of the NORs from these species of the genus Nitrobacter. The immunological analysis enables detection of the key enzyme of the genus Nitrobacter.

Growth and viability of Alcaligenes eutrophus JMP134 in seawater as affected by substrate and nutrient amendment.

Growth and viability of Alcaligenes eutrophus JMP134 was studied in laboratory microcosms with 0.2 microns-filtered seawater prior to release in field-based mesocosms. In unamended systems JMP134 did not grow and viability, measured as direct viable counts combined with immunofluorescence microscopy, was 40-50%. Addition of a nitrogen + phosphorus nutrient mixture caused a greater growth response than amendment with a carbon substrate. Amendment with substrate and/or nutrients caused an increase in viability to ca 100% but only for a brief period coinciding with cell proliferation. Hence, Alc. eutrophus JMP134 has a limited survival potential in seawater unless it is supplied with additional nutrients.

Application of a strain-specific rRNA oligonucleotide probe targeting Pseudomonas fluorescens Ag1 in a mesocosm study of bacterial release into the environment.

Sequence analysis of domains 3 and 4 of 23S rRNA from Pseudomonas fluorescens Ag1 was carried out to allow the design of a strain-specific rRNA oligonucleotide probe targeting this strain. The specificity of the probe, Ps-Ag1, was assessed by dot blot analysis and whole-cell hybridization, and it was found to be specific for P. fluorescens Ag1. The correlation between the ribosomal content of P. fluorescens Ag1 and growth rate was determined during balanced growth conditions with generation times ranging from 1.2 to 31.8 h. Hybridization of the rRNA-targeting probes combined with charged coupled device-enhanced microscopy was used to determine the rRNA content. The total RNA content per cell was determined by staining with acridine orange and charged coupled device-enhanced microscopy. After 2 h under carbon starvation conditions, the rRNA content per cell decreased to 45% of the content of an exponentially growing cell. After 1 day of carbon starvation, the rRNA content had decreased to 20%. When cells were grown at different temperatures, it was found that the rRNA content per cell was only dependent on the substrate in the temperature range from 5 to 30 degrees C. P. fluorescens Ag1 was used in a mesocosm release experiment. The strain could be detected by use of the oligonucleotide probe targeting rRNA for 8 days in the water column and for 10 days on solid surfaces. The standard curve correlating growth rate with rRNA content was used to estimate the physiological activity of P. fluorescens Ag1 in the mesocosm experiment.

Air contamination during hip and knee arthroplasties. Horizontal laminar flow randomized vs. conventional ventilation.

In a randomized study 90 patients, operated on with a total hip or knee arthroplasty, were allocated to 1 of 3 different regimes, all including a reinforced single-use operating gown: (1) horizontal laminar flow ventilation and conventional clothes (cotton shirts and trousers) for all staff members, (2) horizontal laminar flow ventilation and occlusive garments (Klinidress) and (3) conventional ventilation and occlusive garments. Volumetric air sampling gave a low mean number of colony-forming units (< 10 cfu/m3) in the vicinity of the wound in all 3 groups. Laminar ventilation, with or without occlusive staff garments, resulted in less air contamination compared to conventional ventilation. During knee arthroplasty, the use of occlusive clothes in the laminar ventilation room, further reduced the number of airborne, bacteria-carrying particles to around 1 cfu/m3. No such reduction was seen during hip arthroplasty. We conclude that hip and knee arthroplasties can be performed in operating theaters with conventional ventilation when occlusive staff garments are used. However, laminar air flow ventilation in knee surgery, preferably in combination with occlusive garments, resulted in a substantially lower air contamination and should be preferred.

Grazing of nonindigenous bacteria by nano-sized protozoa in a natural coastal system.

Mesocosms (∼4.5 m(3)) situated in a closed bay area were used to investigate the effect of protozoan predation on nonindigenous bacteria. Pseudomonas fluorescens strain Agl was released into mesocosms as a single inoculum of 1 × 10(5) cells ml(-1) (final concentration) or as four inocula (same concentration each) at intervals of 3 days. Mesocosms that had received growth media corresponding to the inoculum served as controls. Numbers of P. fluorescens Ag1 decreased rapidly whether released as single or multiple inocula. Direct estimation of protozoan predation using fluorescently labeled P. fluorescens from log phase and starved cultures, respectively, revealed that natural populations of heterotrophic nanoflagellates consumed substantial amounts of the nonindigenous bacterial strain. The volume of fluorescently labeled cells prepared from starved cells was 68% of log phase cell volume, but the individual clearance of the small cells was five to seven times higher than that of the log phase bacteria. The natural populations of nanoflagellates consumed 34-62% of P. fluorescens Ag1 daily if starved bacteria were offered as food, and 3-13% if the cells were in the logarithmic growth phase. This suggests that the effect of protozoan predation on nonindigenous bacterial strains is substantial because cultured bacteria are likely to starve in natural environments. The addition of P. fluorescens Ag1 and the growth medium enhanced the abundance of natural bacteria, chlorophyll a, heterotrophic nanoflagellates, and ciliates, but it did not improve the growth conditions for the released strain. The effects on the indigenous populations were more pronounced after addition of fresh medium than following inoculation with cells, which possibly was due to the lower nutrient content of spent medium. However, these results, based on direct estimation of protozoan predation on log phase and starved nonindigenous bacteria, point to the conclusion that mortality induced by bacterivorous predators is the key factor determining removal of nonindigenous bacteria introduced in natural aquatic systems.

Biodegradable fixation of ankle fractures. A roentgen stereophotogrammetric study of 32 cases.

We performed a prospective randomized study comparing fixation with biodegradable polyglycolic acid (PGA) rods (n 15) or screws (n 17) in 32 selected displaced supination-eversion fractures. Immediate postoperative weight bearing in a walking cast was encouraged. An exact reconstruction of the ankle mortise was achieved in 26/32 ankles. Roentgen stereophotogrammetric analysis (RSA) revealed rather small movements in the ankle mortise during fracture healing. A better stability was achieved by using screws. After 6 months the clinical results did not differ. One case of sinus formation and one with local effusion occurred; both healed without impairing the clinical result. To compare the results with a nondegradable osteosynthesis technique, a reference group of supination-eversion fractures previously operated on with cerclage-wires, staples and pins was used. RSA showed better fracture stability with nondegradable fixation. The clinical results, however, did not differ.

Early postoperative ankle exercise. A study of postoperative lateral malleolar fractures.

Fifty-three patients with dislocated lateral malleolar fractures were randomly selected after operation for either active ankle movement and weight bearing in an orthosis or no ankle movement but weight bearing in a walking cast. At follow-up examinations after three, six, and 18 months, no differences were found between the groups except for a better linear analogue scale result at three months for the orthosis group. Active ankle movements do not improve the rehabilitation of surgically treated lateral malleolar fractures.

Early mobilization of operated on ankle fractures. Prospective, controlled study of 40 bimalleolar cases.

40 patients with dislocated bimalleolar and trimalleolar ankle fractures took part in this randomized study. All ankles were operated on using cerclage, staples and pins. Active ankle movement with weight bearing in an orthosis was compared with active ankle movement without weight bearing using a dorsal splint. Stereophotogrammetric analysis showed small movements in the ankle mortise in both groups but conventional radiography revealed no fracture redislocation. The clinical results did not differ. This study was designed as the second part of a consecutive project. In the first part, early and late weight bearing in a cast without ankle movements was compared (Ahl et al. 1987b). In comparing the first and the second parts of the study, a small but significant increase in fracture instability was observed in the early motion group. No lasting superior clinical result was achieved by early ankle movement. After operation on dislocated bimalleolar ankle fractures, early postoperative weight bearing in a walking cast is recommended.

Trabecular patterns of the calcaneum as an index of osteoporosis. A comparison using gamma-absorptiometry.

Measurements of bone mineral content in the calcaneum were made by gamma-absorptiometry in 77 patients with ankle fractures treated by operation, and compared with the calcaneal osteoporosis index. The index was calculated from plain lateral radiographs of the calcaneum. The bone mineral measurements showed a wide range, but there was only a narrow range of the index with exclusively high values. There was a weak correlation between the calcaneal index and the bone mineral content in the injured ankles, but no or only a very poor correlation in the uninjured ankles. We also found no correlation between the decline in index and loss of mineral content in the injured ankles.

Subclass distribution of salivary secretory immunoglobulin A antibodies to oral streptococci.

The ability of specific secretory immunoglobulin A (S-IgA) antibodies to inhibit bacterial colonization of mucosal surfaces may be neutralized by the activity of bacterial IgA1 proteases. Because of the resistance of the IgA2 subclass to these enzymes, the biological effect of IgA1 proteases in vivo may depend on the subclass distribution of the bacterium-specific antibodies. We have estimated the subclass distribution of S-IgA antibodies in saliva samples from 13 individuals against IgA1 protease-producing (Streptococcus sanguis and Streptococcus oralis) and nonproducing (Streptococcus gordonii and Streptococcus mitis bv. 2) oral streptococci. IgA1 was found to be the predominant subclass of antibodies against these four bacteria in most of the saliva samples, corroborating previous data suggesting a role of IgA1 proteases in plaque formation. However, variation in the subclass distribution of S-IgA antibodies against the same strain was observed. In one individual, IgA2 was the predominant subclass of antibodies against all four streptococci and of total salivary S-IgA, pointing to the possible significance of genetic variations. The study also addresses methodological problems related to the quantitation of salivary antibodies by solid-phase immunoassays.