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Biomedical subjects

M Krismer

Publications and source records attributed to M Krismer.

At least 19 recordsLinked to original sources
PubMed2006

Cementless hemiarthroplasty in femoral neck fractures: evaluation of clinical results and measurement of migration by EBRA-FCA.

Aim of the present study was to evaluate migration rates of cementless primary hemiarthroplasty in acute femoral neck fractures. In a longitudinal, prospective study 46 patients were treated by cementless hemiarthroplasty. Clinical follow up was correlated with the EBRA-FCA method. In 30% of all patients stem migration amounted to more than 2 mm; further, these patients were seen to have a high level of activity. A high degree of migration in more than 30% of all patients requires critical scepticism toward further use of the investigated cementless stem as hemiarthroplasty. According to literature, migration of more than 2 mm suggests a high probability of early aseptic loosening. In patients with a low degree of activity good results could be observed; nevertheless, in patients with a high level of activity the combination of the investigated cementless stem with a solid fracture head cannot be recommended.

Aged↗
PubMed2006

Uncompromised quality of the cement mantle in Exeter femoral components implanted through a minimally-invasive direct anterior approach. A prospective, randomised cadaver study.

A complete cement mantle is important for the longevity of a total hip replacement. In the minimally-invasive direct anterior approach used at the Innsbruck University hospital, the femoral component has to be inserted into the femoral canal by an angulated movement. In a cadaver study, the quality and the extent of the cement mantle surrounding 13 Exeter femoral components implanted straight through a standard anterolateral transgluteal approach were compared with those of 13 similar femoral components implanted in an angulated fashion through a direct anterior approach. A third-generation cementing technique was used. The inner and outer contours of the cement mantles was traced from CT scans and the thickness and cross-sectional area determined. In no case was the cement mantle incomplete. The total mean thickness of the cement mantle was 3.62 mm (95% confidence interval 3.59 to 3.65). The mean thickness in the group using the minimally-invasive approach was 0.16 mm less than that in the anterolateral group. The distribution of the thickness was similar in the two groups. The mean thickness was less on the anteromedial and anterolateral aspect than on the posterior aspect of the femur. There is no evidence that the angulated introduction of Exeter femoral components in the direct anterior approach in cadavers compromises the quality, extent or thickness of the cement mantle.

Arthroplasty, Replacement, Hip↗
PubMed2005

EBRA-FCA for measurement of migration of the femoral component in surface arthroplasty of the hip.

Studies on the migration of an implant may be the only way of monitoring the early performance of metal-on-metal prostheses. The Ein Bild Roentgen Analyse--femoral component analysis (EBRA-FCA) method was adapted to measure migration of the femoral component in a metal-on-metal surface arthroplasty of the hip using standard antero-posterior radiographs. In order to determine the accuracy and precision of this method a prosthesis was implanted into cadaver bones. Eleven series of radiographs were used to perform a zero-migration study. After adjustment of the femoral component to simulate migration of 3 mm the radiographs were repeated. All were measured independently by three different observers. The accuracy of the method was found to be +/- 1.6 mm for the x-direction and +/- 2 mm for the y-direction (95% percentile). The method was validated using 28 hips with a minimum follow-up of 3.5 years after arthroplasty. Seventeen were sound, but 11 had failed because of loosening of the femoral component. The normal (control) group had a different pattern of migration compared with that of the loose group. At 29.2 months, the control group showed a mean migration of 1.62 mm and 1.05 mm compared with 4.39 mm and 4.05 mm in the failed group, for the centre of the head and the tip of the stem, respectively (p = 0.001). In the failed group, the mean time to migration greater than 2 mm was earlier than the onset of clinical symptoms or radiological evidence of failure, 19.1 versus 32.2 months (p = 0.001) and 24.8 months (p = 0.012), respectively. EBRA-FCA is a reliable and valid tool for measuring migration of the femoral component after surface arthroplasty and can be used to predict early failure of the implant. It may be of value in determining the long-term performance of surface arthroplasty.

Adult↗
PubMed2005

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.

Acetabulum↗
PubMed2004

Radiographic evaluation of the Duraloc cup after 4 years.

We implanted 71 metal-backed, porous-coated, hemispheric, press-fit Duraloc-100 cups in 68 consecutive patients. In 61 patients, the femoral stem was a cementless Spotorno and in ten a cemented Lubinus SP II. A 28-mm Biolox ceramic head was used with both stems. After an average follow-up of 4 (3.7-5.9) years, we examined 67 hips. Radiolucencies were described in three zones according to DeLee and Charnley, and migration was measured on serial radiographs using the computer-assisted EBRA method. Total migration of more than 1 mm within the first 2 years occurred in 22/62 cups. Nine cups showed more than 1.5 mm total migration within the first 2 years and more than 2 mm within the whole period. The presence of post-operative radiolucencies correlated significantly with a total migration value of more than 2 mm within the first 2 years (p=0.02). Post-operative radiolucencies in zone 1 correlated with a total migration value of more than 2 mm within the first 2 years (p=0.027) and more than 2.5 mm within the whole period (p=0.051). These correlation values might reflect the quality of operative technique, particularly reaming, and implant selection.

Adult↗
PubMed2004

Comparison of conventional versus minimally invasive extraperitoneal approach for anterior lumbar interbody fusion.

The purpose of the study was to compare conventional versus minimally invasive extraperitoneal approach for anterior lumbar interbody fusion (ALIF). Fifty-six consecutive patients with spondylolisthesis, lumbar instability, or failed back syndrome were treated with ALIF between 1991 and 2001. The patients were retrospectively evaluated and divided in two groups: Group 1, consisting 33 patients, was treated with ALIF using the conventional retroperitoneal approach, and Group 2, consisting of 23 patients, was operated with the minimally invasive muscle-splitting approach for ALIF. The groups were comparable as regards age, indication of fusion, and diagnosis. All patients in both groups had fusion with autologous iliac crest grafts and posterior instrumentation with posterolateral fusion in the same sitting. Clinical evaluation was done by two questionnaires: the North American Spine Society (NASS) Lumbar Spine Outcome Assessment Instrument and the Nottingham Health Profile (NHP). Fusion rate was evaluated radiologically. Mean clinical follow-up was 5.5 years. There was no statistical difference in the occurrence of complications with both approaches nor with the fusion rates of 92% in group 1 and 84% in group 2 respectively. The minimally invasive extraperitoneal approach for ALIF was associated with significantly less intraoperative blood loss, operation time, and length of the skin incision. In addition, this approach showed significant improvement in postoperative back pain in comparison to the conventional approach for ALIF.

Adult↗
PubMed2003

Heat distribution and heat transport in bone during radiofrequency catheter ablation.

BACKGROUND: To assess the feasibility of percutaneous radiofrequency ablation in large bone tumours, the heat distribution in cortical bone and marrow around inserted electrodes was measured. METHODS: Fresh bovine cadaver tibial bones were locally heated through drill holes for a maximum of half an hour using water-cooled single radiofrequency electrodes (Radionics Instruments Inc) by pulsed energy. Temperatures were measured in the marrow canal as well as in cortical bone by thermocouples at various distances from the inserted probes. RESULTS: Perpendicular to the probe, hyperthermia of more than 50 degrees C could be created in bone marrow in a sphere of approximately 3 cm, and of approximately 1 cm in cortical bone. CONCLUSION: As irreversible cellular damage can be expected when increasing the temperature to 50 degrees C for a duration of 6 min, this method may be effective for the minimal invasive ablation of neoplasms within human bone in cigar-shaped regions of approximately 3-cm diameter.

Animals↗
PubMed2003

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.

Aged↗
PubMed2002

[Surgical treatment of idiopathic scoliosis and juvenile kyphosis].

Indication for operative treatment of idiopathic scoliosis and juvenile kyphosis is mainly cosmetic. There is also a higher incidence of pain in scoliosis patients, and reduced pulmonary function in severe deformity, especially in severe deformities present at the age of 5 years (early onset). Scoliotic curves of less than 30 degrees will not progress in adults, whereas curves of 50-75 degrees will further progress a mean of 25 degrees during 40 years. Progression in adults with juvenile kyphosis is not well documented. Operative treatment aims to stop progression, to control spinal growth, or to perform correction and fusion by spinal instrumentation and bone grafts. These goals can be achieved either by an anterior, a posterior, or a combined approach. Correction principles are compression, distraction, derotation and translation. The forces applied by correction are transferred by fixation devices (pedicle screws, anterior screws, hooks, sublaminar wires) to the spine. The higher correction forces are, the higher is the correction achieved, but also the risk of fracture and torn out implants. Mobilisation reduces rigidity and allows to achieve a better correction with equal forces. The best mobilisation techniques are disc excision, facet joint removal, and techniques to mobilise the thorax.

Adult↗
PubMed2001

Multiple previous surgeries, infection, and preoperative radiation: a cause for arterial rupture in closed reduction?

We report a patient who underwent revision hip arthroplasty with preoperative radiation after a septic loosening of the primary hip prosthesis. Subsequently the patient presented with a dislocation of the hip. During the closed reduction with general anesthesia, a rupture of the arteria profunda femoris occurred. The patient was treated by angiographic obliteration of the arteria profunda femoris followed by an open reduction and augmentation of the acetabular component.

Aged↗
PubMed2001

Excessive heat generation during cutting of cement in the Robodoc hip-revision procedure.

The ROBODOC system is a promising new method for removing cement with high-speed milling. Heat is generated during the milling process. This study was designed to measure temperatures in the cutting area, and to assess the risk of heat injury and the effectiveness of irrigation. We measured temperatures at the bone-cement cutting area in three experimental settings, two involving the proximal area comprising a cement mantle, and one the distal cement plug beneath the prosthesis. Without cooling facilities, a mean temperature of 94 degrees C was measured in proximal areas. However, this could effectively be reduced below 70 degrees C with irrigation. In the area of the distal cement plug, we measured a mean temperature of 172 degrees C without irrigation. In this area, the integrated irrigation system with an additional high-flow irrigation system could not guarantee cooling to an acceptable temperature of below 70 degrees C since the irrigation stream was impeded by the cutter in the narrow cavity. We need an integrated irrigation device that guarantees continuous cooling at the cutting interface in front of the cutter.

Arthroplasty, Replacement, Hip↗
PubMed2001

Knee pain caused by a fiducial marker in the medial femoral condyle: a clinical and anatomic study of 20 cases.

After 2-pin-based ROBODOC hip arthroplasty procedures, 10 of 18 patients reported persistent severe pain at the site of pin implantation in the medial femoral condyle. In a cadaver study, we found that the infrapatellar branch of the saphenous nerve, the saphenous nerve and the anterior cutaneous branches of the femoral nerve had been injured by the pins. At least one of these nerves was injured in 11 of the 20 specimens examined. Our findings indicate that the knee-pain may be partly caused by injuries to these nerves.

Aged↗
PubMed2001

Radiologic abnormalities and low back pain in elite skiers.

Lumbar radiographs of 120 adolescent elite skiers were evaluated for radiologic abnormalities by two independent observers. All athletes had no symptoms before the study. Radiographs were taken before enrollment of the students in elite level training. To determine the clinical significance of these abnormalities, all athletes were observed prospectively during the subsequent 2-year period for development of low back pain under high performance training. Anterior end plate lesions, Schmorl's nodes, posterior end plate lesions, spondylolysis, scoliosis, and spina bifida occulta were found. The depth of anterior end plate lesions showed a two-peak distribution, with peaks at 11% and 22% and a valley at 18% vertebral body height. The overall low back pain incidence was 12.5%. Students with severe anterior lesions (greater than 18% vertebral body height, n = 25) had significantly more low back pain (incidence, 32%) than did students without severe anterior lesions (incidence, 7.4%). Accordingly, students with severe anterior lesions had a significantly higher risk of having low back pain develop. Moderate end plate lesions and other abnormalities were not related to an increased incidence of low back pain. Adolescent students of elite sports with severe lumbar anterior end plate lesions have an increased risk of having low back pain develop under high performance training.

Adolescent↗
PubMed2001

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.

Computer Simulation↗
PubMed2001

[Videotape preparation of patients before hip replacement surgery improves mobility after three months].

Long-term follow-up investigations of the effect of psychological preparation on postoperative physical outcome measures have very rarely been done. In this study a three-month follow-up of a previous investigation of videotape preparation before hip replacement surgery is reported. 100 patients who previously participated in a randomized controlled study received physical examination and x-ray of the hip joint three months after the operation. The mobility of the replaced hip joint was recorded as well as ossifications of the joint. Prepared patients showed a significantly higher improvement of internal rotation, rotational range of motion, and abduction, compared to the controls. The effect sizes ranged between 21% and 32% and, thus, were of clinical relevance. Prepared patients showed less ossifications (15%) that controls (22%), this difference was not significant. For the first time it could be demonstrated that psychological preparation before surgery can not only improve short-term and psychosocial outcome parameters, but also long-term physical measures. The reason for this effect remains to be investigated.

Adaptation, Psychological↗
PubMed2000

Motion in lumbar functional spine units during side bending and axial rotation moments depending on the degree of degeneration.

STUDY DESIGN: Human lumbar spine specimens were tested in axial rotation and side bending. Motion was related to the grade of degeneration. OBJECTIVES: To determine the degree to which degeneration with fissure formation in the disc affects axial rotation of the lumbar functional spine unit. SUMMARY OF BACKGROUND DATA: There is controversy in the literature regarding the influence of severe degeneration and fissures of the disc on the range of axial rotation. METHODS: Thirty-six lumbar spine specimens were tested in axial rotation and side bending, by applying pure moments in an unconstrained setting. The motion in 6 df was recorded by dial gauges. The grade of degeneration was established by the grading schemes of Nachemson, Thompson, Adams, and Mimura. RESULTS: A significant increase of axial rotation and lateral translation under torque was found. This increase mainly took place between Grade 3 according to the schemes of Nachemson, Thompson, and Adams (no fissure formation) and the higher grades of degeneration (defined by fissure formation). Reduced disc height was always associated with fissures. CONCLUSIONS: A reduced lumbar disc height in radiographs seems to be associated with fissure formation in the disc. In this case, the range axial rotation after torque is increased in comparison with cases with less degeneration.

Adult↗
PubMed2000

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.

Adolescent↗