Abstract: Using a computer-based quality assurance program, we analysed peri-operative data on 160 patients undergoing one-stage bilateral hip or knee arthroplasties under regional anaesthesia with routine anaesthetic monitoring and only using peripheral intravenous access for peri-operative safety. We monitored defined intra-operative adverse events such as hypotension, myocardial ischaemia, arrhythmias, hypovolaemia, hypertension and early post-operative complications. We also determined post-operative hip and knee function, and patient satisfaction with different aspects of the anaesthetic management. Those patients undergoing one-stage bilateral arthroplasties were matched according to a cross-stratification which used three variables (American Society of Anesthesiologists' physical status scoring system, age and joint replaced) to patients undergoing unilateral hip or knee arthroplasties. Serious intra-operative adverse events were, with the exception of intra-operative hypotension, very infrequent in patients undergoing bilateral (nine adverse events) as well as unilateral arthroplasties (five adverse events). Early post-operative complications were also infrequent in both groups. However, the risks of receiving a heterologous blood transfusion (odds ratio 2.5; 95% confidence interval (CI) 1.3 to 5.0, estimated by exact conditional logistic regression) or vasoactive drugs (odds ratio 3.9; 95% CI 2.0 to 7.8) were significantly greater for patients undergoing bilateral operations. Patient satisfaction with anaesthesia was high; all patients who underwent the one-stage bilateral operation would choose the same anaesthetic technique again.

Abstract: Intramedullary implants, such as the proximal femur nails (PFN), are inserted for the treatment of per-, inter- and subtrochanteric fractures. The initial experiences with these PFN, carried out by AO/ASIF in 1996, have been published. PATIENTS AND METHODS: This study makes a systematic examination of the complications and clinical treatment results from 133 patients treated at our clinic from December 1997-2001 with 139 PFN in per-, inter- and subtrochanteric femur fractures. The mean age at the time of surgery was 78.4 years. All fractures were classified according to the AO system. The most frequent injuries were 31 A2.3 fractures (61.2%). All intraoperative image-converter images and all radiographs from the total period of treatment were evaluated retrospectively in accordance with 28 criteria. The degree of osteoporosis was estimated using the Singh classification. RESULTS: A total of 44 (31.7%) complications arose in 31 (23.3%) patients. On 11 occasions, hip screw cut-out was observed. Of these, two cases involved a Z-effect and one an inverted Z-effect. Two patients suffered a femoral neck fracture following removal of the hip screws. There were 38 (27.3%) reoperations required with 13 changes in procedure. In autumn 2002, clinical follow-up examinations were carried out on 65 (48.9%) patients who were assessed according to the Merle d'Aubigné score. A total of 51 (38.3%) patients had died at the time of follow-up. Normal ambulation was achieved by 33.8% of patients, while 64.6% were free of pain. CONCLUSIONS: The PFN is an appropriate implant in cases of per-, inter- and subtrochanteric femur fractures. Anatomical resetting and correct implant positioning are the keys to successful osteosynthesis. The risk of implant failure is highest in the case of multi-fragmentary per- and intertrochanteric fractures in which medial strengthening has been degraded in patients aged over 80 years. The clinical results in elderly patients are unsatisfactory.

Abstract: The need for supplementary screw fixation in acetabular revisions is still widely debated. We carried out 439 acetabular revisions over an eight-year period. In 171 hips with contained or small segmental defects, the Morscher press-fit cup was used. These revisions were followed prospectively. No screws were used for additional fixation. A total of 123 hips with a mean follow-up of 7.4 years (5 to 10.5) were available for clinical and radiological review. There was no further revision of a press-fit cup for aseptic loosening. Radiological assessment revealed osteolysis in three hips. Of the original 171 hips there was cranial and medial migration of up to 6 mm at two years in 44 (26%). No further migration was seen after the second post-operative year. Acetabular revision without screws is possible with excellent medium-term results in well selected patients.

Abstract: PURPOSE OF THE STUDY: The key problem of implant fixation in THR is stress distribution, i.e. load transmission between bone and implant. The closer the load transfer is to the original physiological situation, the easier the adaptation of the periprosthetic bone to the new biomechanical conditions after implantation of the cup and the safer is its longlasting fixation. The aims of the studies were 1) to get information about the physiological load transfer in the normal hip joint, 2) to get information about the load transfer between acetabulum and acetabular sockets and vice versa, 3) to measure the periacetabular pelvic bone deformation as the stimulator of the remodelling process (third stage of osseointegration) in the normal hip joint and in hip joints fitted with different acetabular cups, 4) to study the morphological stages of osseointegration of a non-cemented press-fit cup and to compare the morphological structure of the periacetabular bone with the biomechanical data obtained by the in vitro studies and finally, 5) to compare the clinical and radiological outcome of follow-up studies of the senior author's "Press-Fit cup" with the theoretical hypotheses according to the experimental observations. MATERIAL AND METHODS: Load transfer between the acetabular bone and the femoral head on one side and press-fit cups has been determined by strain gauge measurements, finite element studies, pressure sensitive Fuji prescale films, CT-osteoabsorptiometry and telemetric measurements. Periacetabular deformation has been measured by Imetric Markers. Osseointegration of the senior author's press-fit cup and, thus, the remodelling process of the bony structures adjacent to the cup have been studied in autopsy specimens of THRs which have been in situ for several years. RESULTS: Load transfer measurements have shown that the main load in the original acetabulum as well as in the acetabulum fitted with a press-fit cup is transmitted to the periphery, especially to the acetabular cortical rim whereas the subchondral bone is exposed to lower, predominantly meridional (tension) stresses. Direct measurements of the periacetabular deformation under load revealed an increase of the peripheral press-fit with increasing stability of a (oversized) press-fit cup. Both the normal as well as the acetabulum fitted with a non-cemented cup deforms in a postero-medial direction. The histo-morphology of the periacetabular bone of autopsy specimens showed excellent bony in- and ongrowth of a porous titanium coating (SULMESH) and bone formation, especially at the periphery in zone 1 and 3 according to DeLee and Charnley. CONCLUSION: The studies have shown that the subchondral bone plate of the acetabulum has very little supportive function for non-cemented press-fit cups. For the preparation of the acetabulum it is, therefore, more important to ream the sclerotic subchondral bone until there is a well vascularized, well bleeding bone bed to facilitate osseointegration of a non-cemented acetabular socket than to preserve the subchondral bone plate as is the case in cement fixation. A non-cemented press-fit socket must transmit load predominantly to the cortical bone of the acetabular rim. Therefore, a too far medial positioning of the cup, and therefore loosing contact to the cortical rim, must be avoided under all circumstances. The clinical experience with acetabular revisions and with conversions of hip arthrodeses into a THR (where there is no subchondral bone at all) have shown the superiority of a well vascularized over a sclerotic (even mechanically stronger) bone bed. Furthermore, it has been shown that the additional use of screws for fixation of an acetabular cup is not only unnecessary but can be deleterious and causes complications including osteolysis and aseptic loosening.

Abstract: To improve the longevity of endoprostheses, the main goal is to reduce wear. Polyethylene together with metal or ceramic is currently the most frequently used combination. Their clinical success is well documented in the literature. Many attempts to improve polyethylene in the past have failed. Materials successful in the laboratory have failed in clinical use. The most recent competitors of ultra-high molecular weight polyethylene (UHMWPE) are the highly cross-linked polyethylenes (HCLPE) and the hard-on-hard couplings such as metal-on-metal or ceramic-on-ceramic. Advantages and downsides regarding particle generation and higher standards of precision in positioning the components are discussed.

Abstract:

Abstract: Several different defect classifications have been published. The most commonly used are described. For clinical practice, differentiation between "contained" and "noncontained" or segmental defects has proven useful. If the acetabular rim provides support, press-fit cups can be used without screws. With an appropriate reaming technique, it is possible to create a sufficiently supportive bed for the implant in many cases. This allows the use of a press-fit acetabular component over a wide range of defects as long as a tilting of the cup can be avoided. Between 1988 and 1995, 439 acetabular cups were revised at the Orthopedic University Clinic in Basel, 171 of them using the Morscher press-fit cup. After a mean follow-up of 7.1 years, not a single cup had to be revised for aseptic loosening. The 9.5% dislocations were due to abductor insufficiencies because of trochanteric pathologies or muscular alterations from former approaches.

Abstract: At the Orthopaedic Department of the University of Basel, a total of 540 cemented Müller titanium alloy (Ti6Al7Nb) Straight Stems were inserted between 1989 and 1993. A cohort of 120 consecutive patients (66 women, 54 men) with 126 prostheses operated on between March and December 1989 were followed clinically and radiologically in a prospective manner for a mean observation time of 9.1 years. In all cases, the Müller titanium alloy Straight Stem was combined with the senior author's (E.W.M.) Press-Fit Cup. The mean age of the patients at surgery was 66 (range 43-93) years. Fourty patients (41 hips) died, 9 were interviewed by telephone, none was 'lost to follow-up'. Seventy-one patients with 76 hip replacements were available for the follow-up. Four hips had been revised: two of them due to aseptic loosening of the femoral component, one because of a late infection--all after 9 years--and one owing to a periprosthetic fracture after 6 years. The 9-year overall survivorship is 96.8%, and for aseptic loosening of the stem 98.4%. None of the cups had to be revised for aseptic loosening. The clinical result (according to Merle d'Aubigné) was excellent and good in 88%, moderate in 8%, and poor in 4%. The radiological analysis showed no osteolysis or radiolucent lines in 59 prostheses (78%). Nine stems (12%) showed a radiolucent line. Focal osteolysis was detected in 8 cases (10%) in one or more Gruen zones. The distribution of the osteolyses shows that predominantly zones VII, VI, V, and II are affected in decreasing frequency. No osteolysis was detected on the acetabular side. Our results do not confirm the high rate of osteolysis and revisions with the Müller titanium alloy Straight Stem presented by some other institutions. The verdict on a specific endoprosthetic implant must be made by combined assessment of the design, the implant surface condition, the material, the cement, the cementing procedure and the operative technique. The statement made in earlier publications that cemented titanium alloy should not be used as a femoral stem prosthesis should be reconsidered.

Abstract: Bone cement (polymethylmethacrylate, PMMA) removal during revision hip arthroplasty can be a tedious, time-consuming process. The usual methods of removing cement include high-speed drills, chisels, saws, and reamers, which are often associated with fracture or perforation of the femoral shaft. An alternative very promising method is cement removal with ultrasound. We present an ultrasonic device for rapid cement removal with minimum risk of trauma to the fragile femoral bone. The technique of cement removal with ultrasound is described and problems and risks are addressed.

Abstract: The goal of every hip revision is to restore as much function as possible. Frequent problems are defects of the load-carrying bony substance and functional deficits due to trochanteric avulsions, abductor insufficiencies, and lesions of the superior gluteal nerve. Disturbed functions of these important structures may lead to unsatisfactory results with high dislocation rates and limping. Various femoral defect classifications differ in their description of the lesion as well as in their proposed therapeutic approach. Significant differences exist in the field of allograft use. Among others, the AAOS, SO.F.C.O.T, and Paprosky's classifications are described. Our own easy to use alternative classification is introduced which takes into consideration the fixation principle of the new stem. It thus helps to select the type of implant and offers a guideline for technical modalities. A Type 1 defect allows a revision with a component suitable for a primary case. Type 2 defects can be treated with a short revision stem exceeding the length of the revised stem. Type 3 defects are treated with a "load-sharing" concept where an optimized metaphyseal fill and a cylindrical shape distally share the axial and torsion loads. Type 4 defects are reconstructed with a combination of a revision stem and an allograft.

Abstract:

Abstract: The deformity in severe spondylolisthesis consists of two components: the parallel anterocaudad slip of the spondylolisthetic vertebra, and its tilt into kyphotic malposition. The influence of the two components is very different: the anterocaudad slippage has not much impact on the sagittal profile of the spine and is easily compensated for by a slight increase in lumbar lordosis. The kyphotic deformity has a high impact on trunk imbalance and the sagittal profile. There are two compensation mechanisms: hyperlordosis of the lumbar spine to its anatomical extremes and-if that is not sufficient-verticalisation of the sacral bone, performed by contracture of the hamstrings and uprighting of the pelvis around the hip joints. The latter mechanism is followed by functional disadvantages. Therefore, correction of the kyphosis of L5 may be considered during operative treatment if the lumbosacral kyphosis (angle delta) is less than 85 degrees and the sacral inclination less than 35 degrees.

Abstract: The Lequesne algofunctional indices for the knee and the hip require a physician interview. We adapted the Lequesne indices for the German language and tested the metric properties, test-retest reliability and validity of a self-report questionnaire-format in 51 patients with hip or knee OA. The symptom and function components as well as the global indices had a high test-retest reliability (intraclass correlation coefficient knee: 0.87/0.92 and 0.86, hip: 0.96/0.85 and 0.94). The symptom component showed an insufficient internal consistency (Cronbach's coefficient alpha knee: 0.55; hip: 0.63). Also, the symptom component was not or only weakly associated with radiological OA-severity and the limitations of range-of-motion. The most likely explanation is the grading of the Lequesne symptom questions which addresses such different concepts as pain presence, pain on movement, duration of pain and appearance of pain after a certain period of time. Because of the insufficient internal consistency and questionable validity the tested self-report German-version of the Lequesne algofunctional indices may not be recommended for use in clinical research and practice.

Abstract: A total of 524 knees underwent a primary PCA knee arthroplasty between 1982 and 1989. Of these 415 suffered from osteoarthritis (OA) and 61 from rheumatoid arthritis (RA). They were analyzed for differences regarding the outcome. Neither survivorship analysis nor number or type of revisions revealed statistical differences among these two groups. The knee score rose in the OA group from a median of 28 to 89 points after 1 year and then dropped to 87 points between 54 and 118 months. In the RA group the median of the knee score rose from a preoperative value of 21 points to 90 points after 1 year but then dropped to 77 points at the most recent follow-up. This development was probably the result of general progression of the disease. Even in the RA group the rating was still "good" at the latest follow-up. Regarding the benefit of such a procedure in a polyarticular disease and its preservation over a long period of time, total knee arthroplasty can be recommended for patients with RA, and preferably the cemented version.

Abstract: Quantitative computed tomography was used to investigate the three-dimensional architecture and the density distribution of the cancellous structures of the proximal femur. We examined 10 femora from the cadavera of 10 individuals, 47-83 years old at the time of death. Three anatomic elements could be distinguished: the epiphysis, the epiphyseal scar, and the metaphysis. Although these elements constitute a functional unit, their individual cancellous patterns revealed significant structural differences. The epiphyseal segment had a more reticulate cancellous appearance, whereas the metaphysis demonstrated a more longitudinally oriented trabecular distribution. The three-dimensional reconstruction of the densest epiphyseal trabecular groups showed two different patterns: a dumbbell type (found in eight bones) and a hemispheric type (found in two bones). The epiphyseal scar was a clearly recognizable high-density structure found in all 10 bones. The epiphyseal scar-diaphysis angle was 13-26 degrees higher than the center column-diaphysis angle. The scar appeared as a tray supporting the epiphyseal cancellous structures, supported itself by the metaphyseal intersection of the main compressive and the arcuate trabecular systems. This intersection always occurred in a relatively small band-shaped zone under the central third of the epiphyseal scar. These three discrete anatomical segments within the proximal femur may reflect developmental and functional adaptations determined by joint incongruity or eccentric muscular activity. The present data will serve as a reference for future studies in which the cancellous patterns are used to help with the early diagnosis of states of disease.

Abstract: Normal use places stress on the femur from different directions and with variable intensity. All these forces are introduced as pressure forces through the cartilage in a trajectory framing cancellous structure whose elements are primarily charged axially with tension and pressure. The effects of these forces on these structures were analyzed with different methods. Often we only looked for single aspects of the introduction the of force or worked with experimentally acquire approximations. To analyze the conditions for an authentic femur, we examined the trabecular structures of a proximal femur with computed tomography. We had some indications that the trabecular structures are not built linearly, as shown by von Meyer, Wolff, Goss and Singh. In our study we found a significant deviation of the epiphyseal trabeculae from the metaphyseal alignment. This makes us believe that even later the area of the former epiphysis plays a certain role in the distribution of supporting structures beneath the charged surface meaning to adapt to the effective stress.

Abstract: We introduce a simple method of sonographic determination of femoral neck anteversion in children with which the even difficult angels in terms of measurement, those up to 70 degrees, can be measured with sufficient reliability: The examination was done with a defined internal 40 degree rotation of the legs reached by a supporting wedge. We proved this method on 55 children's hips of which we already had an existing radiologic determination of the anteversion angle. Compared to the radiological results we found an average deviation of 3.6 degrees (standard deviation = 3.2).

Abstract: In young patients with advanced necrosis of the femoral head, the short- and medium-term results of total prosthesis arthroplasty are the most satisfactory. However, the prospect of aseptic loosening hangs over such arthroplasties like Damocles' sword. Reports from the literature suggest that, in addition to the age of the patient, there is also an endogenous factor that can be responsible not only for the etiology and pathogenesis of the necrosis, but also for the early loosening of the prosthesis. We have followed up 54 patients (73 hip joints) who had total hip replacement as a result of necrosis of the femoral head between 1976 and 1988. Altogether, 3 acetabular and 5 femoral shafts had to be replaced (7 patients). This corresponds to a loosening rate of 10% after an average of 4.9 years. Hence, the prosthesis changing rate is lower than that reported by other authors, but is still higher than in patients with coxarthrosis. Only 2 of 52 cemented shaft prostheses had to be replaced; the average age of these patients was 61.4 years. Of the 21 cement-free shaft implantations, 3 had to be replaced, the average age of these patients being 42.9 years. The fact that the average age of the latter patients was lower may be the reason for the revision rate not being significantly higher for the non-cemented shafts. In view of the fact that necrosis of the femoral head can rapidly result in the patient becoming an invalid if it is allowed to follow its natural course, hip joint prostheses should also be offered to younger patients.

Abstract: A prospective, controlled, double-blind, randomized multicenter trial including 12 Swiss hospitals with 358 patients was carried out. The aim of the study was to investigate whether a single-dose prophylaxis with 5 g mezlocillin given immediately before surgery can reduce not only the incidence of wound infections but other bacterial complications as well. Of the 324 correct protocols, 165 belonged to the placebo and 159 to the mezlocillin group. The two groups are comparable in all regards. The incidence of wound infections was 10% in the control and 4% in the treated group (p less than 0.05). The number of other infectious complications could not be reduced. No side effects due to the prevention were observed. Single-dose prevention with mezlocillin is proposed for all patients undergoing biliary tract surgery.

Abstract: A prospective, controlled, double-blind, randomized multicentre trial in Switzerland has been conducted to investigate the effectiveness of 5 g mezlocillin given during induction of anesthesia for prevention of infectious complications in biliary tract surgery. All adults undergoing elective or emergency surgery were included. Single-dose prevention reduces the incidence of wound infections from 10% to 4%, but does not reduce other kinds of infectious complications. The incidence of wound infections in the control group in Switzerland is only about half that in other countries. It is concluded that administration of single-dose mezlocillin to all patients in this type of surgery is justified. On the basis of risk factors it is impossible to predict reliably the patients who do not need protection.

Abstract: We have evaluated the case histories of all patients who underwent surgery of the biliary tract in 1979. In that year every surgeon was able to administer antibiotics postoperatively whenever he considered it necessary. Of the 71 patients, 39% received postoperative antibiotic treatment. In 1980, 50 patients over the age of 50 received a 36-hour course of mezlocillin prophylaxis when they underwent surgery of the biliary tract, either as an elective or emergency operation. Only 8% of these patients required antibiotics postoperatively. In comparison to the 39% from 1979, this difference is highly significant statistically. This pilot study justifies further investigations to determine whether single-dose mezlocillin prophylaxis is able to reduce the incidence of infectious complications, the duration of the hospital stay and the total amount of antibiotics administered.