[Interdisciplinary position paper "Perioperative pain management"]. / Interdisziplinäres Positionspapier "Perioperatives Schmerzmanagement".

Despite many positive developments, postoperative pain and its treatment is still not always given the necessary attention. Severe pain after surgical procedures affects a significant proportion of patients. This very fact is not only detrimental to the immediate recovery process, but can also form the basis for the development of chronic pain conditions.An adequate and effective management of perioperative pain requires appropriate organizational structures. This multidisciplinary paper which was initiated by the Austrian Society for Anaesthesiology and Intensive Care and the Austrian Pain Society and developed together with numerous specialist and professional societies dealing with the subject aims at supporting the organization of perioperative pain management structures and to make best use of proven concepts. Additional recommendations describe specific interventions for selected types of intervention.

Low-energy shock waves enhance the susceptibility of staphylococcal biofilms to antimicrobial agents in vitro.

Biofilm-associated infections in wounds or on implants are difficult to treat. Eradication of the bacteria is nearly always impossible, despite the use of specific antibiotics. The bactericidal effects of high-energy extracorporeal shock waves on Staphylococcus aureus have been reported, but the effect of low-energy shock waves on staphylococci and staphylococcal biofilms has not been investigated. In this study, biofilms grown on stainless steel washers were examined by electron microscopy. We tested ten experimental groups with Staph. aureus-coated washers and eight groups with Staph. epidermidis. The biofilm-cultured washers were exposed to low-energy shock waves at 0.16 mJ/mm(2) for 500 impulses. The washers were then treated with cefuroxime, rifampicin and fosfomycin, both alone and in combination. All tests were carried out in triplicate. Viable cells were counted to determine the bactericidal effect. The control groups of Staph. aureus and Staph. epidermidis revealed a cell count of 6 × 10(8) colony-forming units/ml. Complete eradication was achieved using the combination of antibiotic therapy (single antibiotic in Staph. aureus, a combination in Staph. epidermidis) and shock wave application (p < 0.01). We conclude that shock waves combined with antibiotics could be tested in an in vitro model of infection.

Revision rates after total joint replacement: cumulative results from worldwide joint register datasets.

In a systematic review, reports from national registers and clinical studies were identified and analysed with respect to revision rates after joint replacement, which were calculated as revisions per 100 observed component years. After primary hip replacement, a mean of 1.29 revisions per 100 observed component years was seen. The results after primary total knee replacement are 1.26 revisions per 100 observed component years, and 1.53 after medial unicompartmental replacement. After total ankle replacement a mean of 3.29 revisions per 100 observed component years was seen. The outcomes of total hip and knee replacement are almost identical. Revision rates of about 6% after five years and 12% after ten years are to be expected.

Reducing the risk of dislocation after total hip arthroplasty: the effect of orientation of the acetabular component.

Malposition of the acetabular component is a risk factor for post-operative dislocation after total hip replacement (THR). We have investigated the influence of the orientation of the acetabular component on the probability of dislocation. Radiological anteversion and abduction of the component of 127 hips which dislocated post-operatively were measured by Einzel-Bild-Röentgen-Analysis and compared with those in a control group of 342 patients. In the control group, the mean value of anteversion was 15 degrees and of abduction 44 degrees. Patients with anterior dislocation after primary THR showed significant differences in the mean angle of anteversion (17 degrees), and abduction (48 degrees) as did patients with posterior dislocation (anteversion 11 degrees, abduction 42 degrees). After revision patients with posterior dislocation showed significant differences in anteversion (12 degrees) and abduction (40 degrees). Our results demonstrate the importance of accurate positioning of the acetabular component in order to reduce the frequency of subsequent dislocations. Radiological anteversion of 15 degrees and abduction of 45 degrees are the lowest at-risk values for dislocation.

Migration of metal-on-metal versus ceramic-on-polyethylene hip prostheses.

In a prospective randomized study, 32 metal-on-metal prostheses and 29 ceramic-on-polyethylene prostheses of similar design were implanted in 59 patients. Radiolucency, cup migration, wear, and function were examined after a minimum of 2 years followup (followup rate, 87%). The purpose of the current study was to evaluate whether higher frictional torque of metal-on-metal will lead to a higher rate of early metal-on-metal cup loosening. A computer-assisted method was used for wear and migration measurements of the acetabular component. Metal-on-metal prostheses migrated in a craniocaudad direction significantly less than ceramic-on-polyethylene prostheses. The mean total migration for both types of prostheses exceeded 1.5 mm at 2 years. Clinically, no difference between the two prostheses regarding activity, pain, or range of motion was found at 2 years. As migration of metal-on-metal prostheses was not higher in comparison with ceramic-on-polyethylene prostheses, the expected higher frictional torque of metal-on-metal prostheses did not increase migration during short-term followup. The different debris produced by both bearings did not influence the short-term results of this study, but might cause different long-term results.

Evaluation of accuracy and precision of bone markers for the measurement of migration of hip prostheses. A comparison of conventional measurements.

Our aim was to determine whether tantalum m arkers improved the accuracy and/or precision of methods for the measurement of migration in total hip replacement based on conventional measurements without mathematical correction of the data, and with Ein Bild Roentgen Analyse - Femoral Component Analysis (EBRA-FCA) which allows a computerised correction. Three observers independently analysed 13 series of roentgen-stereophotogrammetric-analysis (RSA)-compatible radiographs (88). Data were obtained from conventional measurements, EBRA-FCA and the RSA method and all the results were compared with the RSA data. Radiological evaluation was also used to quantify in how many radiographs the intraosseous position of the bone markers had been simulated. The results showed that tantalum markers improve reliability whereas they do not affect accuracy for conventional measurements and for EBRA-FCA. Because of the danger of third-body wear their implantation should be avoided unless they are an integral part of the method.

Foot deformities in adolescents and young adults with spina bifida.

Spina bifida is generally accompanied by a high incidence of foot deformities. The goal of management is to achieve a plantigrade foot. Deformities are related to the level of the lesion. With thoracic lesions, the most frequent deformity is an equinus lesion (55%), a club foot with mid-lumbar lesion (87%) and a calcaneal foot with sacral lesions (34%). No deformity was present in 56% of feet in sacral lesion children. Club foot surgery before the age of 2 years entails a high rate of recurrence (78%), necessitating redo surgery. A calcaneo-valgus deformity developed in 45% of ambulating patients with sacral lesions requiring operative stabilization of the foot. Patients with sacral lesions were almost the only ones who remained ambulators. Ambulation was not seen to be related to foot deformities in adolescents and young adults.

Transfusion of buffy coat-depleted blood components and risk of postoperative infection in orthopedic patients.

BACKGROUND: Allogeneic blood transfusions have been reported to increase susceptibility to postoperative infection, but the findings were inconclusive. This study was designed to investigate the effect of buffy coat-depleted allogeneic and autologous transfusion on postoperative infection in patients undergoing orthopedic surgery. STUDY DESIGN AND METHODS: Patients (n = 385) undergoing elective orthopedic surgery (primary and revision joint replacement, spinal, or pelvic surgery) were included in a prospective observational study of the incidence of postoperative infection between April and December 1996. Infection rates in patients who received allogeneic buffy coat-depleted blood transfusions were compared with those in patients who received no transfusion or only autologous (buffy coat-depleted) blood. RESULTS: Patients without exposure to allogeneic blood (no blood or only autologous blood) had an infection rate of 3.9 percent, as compared to a rate of 12.2 percent for those with exposure to allogeneic blood (allogeneic blood, autologous plus allogeneic blood) (odds ratio 3.442; 95% CI, 1.349-10.40; p = 0.006). Of the 385 study patients, 309 underwent primary hip or knee replacement surgery. In this homogeneous subgroup, the postoperative infection rate was 4.6 percent after no transfusion or autologous transfusion and 11.9 percent after allogeneic transfusion (odds ratio 2.827; 95% CI 1.059-8.799; p = 0.036). Multivariate regression analysis confirmed buffy coat-depleted allogeneic blood transfusion as an independent variable associated with high risk for postoperative infection. CONCLUSION: Buffy coat-depleted allogeneic blood transfusion increases the incidence of postoperative infection in patients undergoing uncontaminated orthopedic surgery.

Cerclage fibreux in the treatment of hallux valgus.

Resection arthroplasty was performed in 62 feet, with follow-up at an average of 36 months (range, 17-68 months). All cases were performed using a combined cerclage fibreux. The mean age at operation was 61 years (range, 49-77 years). The mean score according to the hallux metatarsophalangeal-interphalangeal scale of the American Orthopaedic Foot and Ankle Society was 81 points (range, 25-100 points). Correction of the hallux valgus angle at follow-up averaged 23 degrees (range, 0-45 degrees). The first intermetatarsal angle had been corrected an average of 3 degrees (range, 0-14 degrees). Transfer metatarsalgia was encountered in eight patients. No hallux varus or cock-up deformity was detected.

Accuracy of EBRA-FCA in the measurement of migration of femoral components of total hip replacement. Einzel-Bild-Röntgen-Analyse-femoral component analysis.

Several methods of measuring the migration of the femoral component after total hip replacement have been described, but they use different reference lines, and have differing accuracies, some unproven. Statistical comparison of different studies is rarely possible. We report a study of the EBRA-FCA method (femoral component analysis using Einzel-Bild-Röntgen-Analyse) to determine its accuracy using three independent assessments, including a direct comparison with the results of roentgen stereophotogrammetric analysis (RSA). The accuracy of EBRA-FCA was better than +/- 1.5 mm (95% percentile) with a Cronbach's coefficient alpha for interobserver reliability of 0.84; a very good result. The method had a specificity of 100% and a sensitivity of 78% compared with RSA for the detection of migration of over 1 mm. This is accurate enough to assess the stability of a prosthesis within a relatively limited period. The best reference line for downward migration is between the greater trochanter and the shoulder of the stem, as confirmed by two experimental analyses and a computer-assisted design.

The prediction of failure of the stem in THR by measurement of early migration using EBRA-FCA. Einzel-Bild-Roentgen-Analyse-femoral component analysis.

We report the ten-year results for three designs of stem in 240 total hip replacements, for which subsidence had been measured on plain radiographs at regular intervals. Accurate migration patterns could be determined by the method of Einzel-Bild-Roentgen-Analyse-femoral component analysis (EBRA-FCA) for 158 hips (66%). Of these, 108 stems (68%) remained stable throughout, and five (3%) started to migrate after a median of 54 months. Initial migration of at least 1 mm was seen in 45 stems (29%) during the first two years, but these then became stable. We revised 17 stems for aseptic loosening, and 12 for other reasons. Revision for aseptic loosening could be predicted by EBRA-FCA with a sensitivity of 69%, a specificity of 80%, and an accuracy of 79% by the use of a threshold of subsidence of 1.5 mm during the first two years. Similar observations over a five-year period allowed the long-term outcome to be predicted with an accuracy of 91%. We discuss the importance of four different patterns of subsidence and confirm that the early measurement of migration by a reasonably accurate method can help to predict long-term outcome. Such methods should be used to evaluate new and modified designs of prosthesis.

Autogenic versus allogenic bone grafts in anterior lumbar interbody fusion.

Between 1987 and 1993, 94 consecutive patients with painful spondylolisthesis underwent combined anterior and posterior fusion. The average age at operation was 40 years (range, 16-65 years). Posterior fusion was performed in all patients using pedicle screw systems, and anterior fusion was accomplished with autogenic or allogenic bone grafts. Patients retrospectively were assigned to two groups. In Group 1, anterior fusion was performed with autogenic bone grafts harvested from the iliac crest (n = 65; 146 segments) and in Group 2 allogenic bone grafts were taken from femoral heads (n = 39; 86 segments). The incidence of pseudarthrosis was evaluated on lateral tomograms 24 months after surgery. The mean clinical followup time was 4 years (range, 3-8 years). Pseudarthrosis was found in seven fused levels (3%) managed with autogenic bone grafts (Group 1) and in seven patients (8%) managed with allogenic bone grafts (Group 2). This incidence of pseudarthrosis was not significantly different between the two groups. Considering the possible complications associated with harvesting iliac crest bone, the use of allogenic bone appears justified.

Migration of the Duraloc cup at two years.

We carried out 71 primary total hip arthroplasties using porous-coated, hemispherical press-fit Duraloc '100 Series' cups in 68 consecutive patients; 61 were combined with the cementless Spotorno stem and ten with the cemented Lubinus SP II stem. Under-reaming of 2 mm achieved a press-fit. Of the 71 hips, 69 (97.1%) were followed up after a mean of 2.4 years. Migration analysis was performed by the Ein Bild Rontgen Analyse method, with an accuracy of 1 mm. The mean total migration after 24 months was 1.13 mm. Using the definition of loosening as a total migration of 1 mm, it follows that 30 out of 63 cups (48%) were loose at 24 months.

Conservative treatment of tuberculous spondylitis: a long-term follow-up study.

A retrospective follow-up study was performed on 40 patients, in which tuberculous spondylitis was treated conservatively between 1969 and 1985 with orthotic supports for an average of 16 months (range, 10-30 months) and with anti-tuberculous agents. All had persistent back pain, but none had neurological deficits. The mean follow-up period was 17 years (range, 10-26 years). Diagnosis was confirmed histopathologically. The spinal segments involved ranged from T5 to L5. The kyphotic angle was calculated according to Cobb. At final follow-up, 22 patients were pain free, 11 had occasional pain, 6 complained of pain in the morning, and 1 had chronic pain and needed frequent analgesics. Solid bony union was found in 75% of patients. The kyphotic deformity occurred in the thoracic spine with a mean angle of 20 degrees (range, 13-28 degrees) and in the lumbar spine with a mean angle 12 degrees (range, 5-26 degrees). The long-term follow-up of conservative treatment showed only slightly increased kyphosis. Conservative treatment is an alternative to surgical intervention in cases with kyphosis < 35 degrees.

Measurement of factor VII and of activated factor VII in healthy individuals and in prothrombin complex concentrates.

We established reference ranges for factor VII clotting activity (FVII:C), factor VII amidolytic activity (FVII:AM), and activated factor VII (FVIIa) in 102 healthy individuals. The reference ranges were 65-160 U/100 ml, 70-165 U/100 ml, and 30-170 mU/ml, respectively (2.5 and 97.5 percentiles). Freezing and thawing of the plasma samples had no influence on the assay results. Due to the small sample size, the results were not influenced by gender, age, smoking habits, and oral contraceptive use. The plasma levels of FVII:C, FVII:AM, and FVIIa were significantly correlated with each other. The significant correlation between FVIIa and FVII:AM indicates that FVIIa is not completely independent of circulating FVII mass. There was also a significant, though weak, correlation between FVIIa and FVII:C/FVII:AM ratios. Sixteen batches of prothrombin complex concentrates (PCC) from 3 manufacturers were also analysed. FVIIa could be detected in all preparations, with considerable variations from batch to batch. In contrast to the results obtained in plasma from normal individuals, there was a close correlation between FVIIa and FVII:C/FVII:AM ratios. The preparations could be characterized by their FVII and FVIIa potencies and by their FVII:C/FVII:AM ratios. In PCC, FVII:C was very strongly correlated with FVIIa, whereas no significant correlation was observed between FVII:AM and FVII:C and between FVII:AM and FVIIa, respectively. These results demonstrate that the FVII:C assay used is sensitive for detecting FVIIa. Thus, we cannot confirm that FVIIa sensitivity of one-stage clotting assays for FVII:C is low when a rabbit thromboplastin and a non-adsorbed FVII-deficient plasma is used.

[Single-image roentgen analysis for the measurement of hip endoprosthesis migration]. / Einzel-Bild-Röntgen-Analyse (EBRA) zur Messung der Migration von Hüftendoprothesen.

A method to determine migration of hip endoprostheses is described. Migration is measured by means of standard AP radiographs and therefore can also be evaluated in retrospective studies. Measurement is conducted in X-ray studies displayed on a computer screen. Enhancement of bony structures by application of filters is available. The developed software can be used with common commercially available computers and X-ray scanners, and does not require special hardware. Several methods to determine accuracy are described. The accuracy of the described method is about 1 mm (95% confidence limit), which compares favourably with other methods, but is less accurate than roentgen stereophotogrammetry. For other methods, accuracy was not determined adequately. Two years after implantation, revision within the first 10 years of follow-up can be predicted with a sensitivity and specificity of more than 80%.

Results of the Müller acetabular reinforcement ring in revision arthroplasty.

Between April 1984 and December 1987 a Müller acetabular reinforcement ring was employed in 98 revision cases (94 patients). Twenty-two patients died before follow-up evaluation. Forty-seven (66%) of the remaining 72 patients (49 of 75 hips) were examined after a mean of 6.4 years (range 5-9 years). Excluding those who died, the postoperative outcome of 69 patients is known. Migration was measured according to Sutherland by means of a digitising table. Cup position was determined by a new angle (beta) between the sacroiliacal line and a reference line. The reference line connects the centre of the femoral head with the intersection between the sacroiliacal and obturator lines. Aseptic and septic loosening required revision surgery in 2 cases each (4%). The postoperative beta angle showed a high correlation with migration (P = 0.001) as well as with radiolucencies (P = 0.001). In cases which required further revision, beta amounted to 44 deg (craniolateral position), and in stable cases up to 60 deg. A lateral and cranial position of a Müller acetabular reinforcement ring leads to high loosening rates. The beta angle accurately describes cup position, and its postoperative value is highly predictive for loosening.

Factor VII and activated-factor-VII content of prothrombin complex concentrates. The PCC Study Group.

BACKGROUND AND OBJECTIVES: The aim of this study was to determine the potencies of factor VII (FVII) and of activated FVII (FVIIa) in prothrombin complex concentrates (PCC). MATERIALS AND METHODS: We examined 56 lots of PCC from 5 manufacturers. Three brands were licensed preparations, and 1 product series had been involved in thromboembolic complications. FVII and FVIIa were measured using a two-stage amidolytic assay and a specific clotting assay, respectively. We also quantified FVII clotting activity by a one-stage assay reflecting a mixture of FVII zymogen and FVIIa. RESULTS: All PCC contained substantial amounts of FVII, and FVIIa could be detected in all lots. There were marked differences between manufacturers and some significant variabilities between batches. The two lots involved in thromboembolic events contained considerably more FVIIa than the PCC still licensed. The lowest FVIIa potencies were observed in an experimental product series, indicating that PCC can be produced without activation of FVII during the manufacturing process. CONCLUSION: FVIIa is present in all PCC containing FVII. High FVIIa potencies may contribute to the thrombogenic potential of these preparations, and determination of FVIIa potencies should be included in the in vitro characterization of PCC.

Early migration predicts late aseptic failure of hip sockets.

We report a prospective, stratified study of 60 PCA-cups and 60 RM-polyethylene cups which have been followed for a median time of 90 months, with annual radiography. The radiological migration of cups was measured by the computer-assisted EBRA method. A number of threshold migration rates from 1 mm in the first year to 1 mm in five years have been assessed and related to clinically determined revision rates. A total of 28 cups showed a total migration of 1 mm or more within the first two years; 13 of these cups have required revision and been exchanged. The survival curves of cups which had previously shown early migration were considerably different from those without early migration. For cups with a migration of less than 1 mm within the first two years the mean survival at 96 months was 0.96 +/- 0.02; for migrating cups, it was 0.63 +/- 0.11 (log-rank test, p=0.0001; chi-square value=39.4). Early migration is a good predictor for late loosening of hip sockets.