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Biomedical subjects

D Kohn

Publications and source records attributed to D Kohn.

At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

[Improved radiological imaging of acetabular screw socket].

The improved radiological representation of the cementless acetabular screw-socket at two levels is of fundamental importance for the postoperative determination of position as well as for the judgement of an aseptic loosening. To improve the radiological representation two special radiographic techniques in the anterior-posterior as well as in the axial view have been examined on a human preparation of pelvis and have been scrutinized on a great number of clinical patients. The a.-p. radiography with twenty degrees cranio-caudal prone view in the sagittal plane and the axial radiography with forty-five degrees caudo-cranial prone view in the coronal plane shows the best and fewest overlayed representation of the screw-socket. The position of inclination and anteversion could have been directly determined out of these two radiographs. Malpositions of the screw-socket, especially with regard to the anteversion are easily identifiable due to the special axial radiographic technique. Overprojection of adjoining bone areas, which were possible should be considered at the judgment of the implant-bone-contact. Radiographic technical and positioning problems were not observed in patients. Out of these examinations the a.-p. radiography with twenty degrees cranio-caudal prone view in the sagittal plane and the axial radiography with forty-five degrees caudo-cranial prone view in the coronal plane could be recommended to the radiological diagnosis after implantations of hip prosthesis.

Acetabulum↗
PubMedDate not supplied

[Intertrochanteric flexion osteotomy and allo-arthroplasty in femur head necrosis. A comparative retrospective study].

Intertrochanteric flexion osteotomy and total hip arthroplasty are the most frequent operative treatments of advanced osteonecrosis of the femoral head in adults. In a retrospective study the postoperative results of intertrochanteric osteotomy and total hip arthroplasty were determined in 68 cases. The evaluation was based on the modified Harris-Hip-Score, the clinical examination and the radiological classification of the ARCO. The patients after osteotomy showed significantly worse subjective results. After osteotomy an increase of the stage of osteonecrosis was found in 73% of the patients. There was no correlation between clinical result and radiological stage of osteonecrosis. In spite of a better preoperative situation the results after osteotomy compared to hip arthroplasty were disappointing in many cases. The postoperative result did not depend on the preoperative stage of the osteonecrosis. The new classification system of the ARCO, which includes the very important MRI, proved to be very suitable and practicable. Based on our results it seems to be reasonable, to restrict the indication for intertrochanteric flexion osteotomy to cases of low stage osteonecrosis and carry out cementless total hip arthroplasty primarily in all others.

Adolescent↗
PubMedDate not supplied

[Dislocation of total hip endoprosthesis with special reference to various techniques].

1238 primary total hip replacements for arthritis were performed in our hospital from 1980 until 1988. 26 dislocations (2.1%) were registered during this period. No differences became obvious regarding age, sex, type of prosthesis and different concepts of postoperative treatment. After the posterior approach dislocations occurred in 18 (3.1%) of the cases, 8 dislocations (1.2%) were found after the transgluteal approach. The dislocation rate was significantly higher for the posterior approach. Derotation braces were not able to decrease the risk of redislocation. Most of the dislocations happened during the first postoperative week. The most frequent occasions were rotation of the operated leg while lying in bed and deep sitting positions. Performing the posterior approach for primary total hip arthroplasty the surgeon has to realize the higher dislocation rate.

Aged↗
PubMedDate not supplied

[Comparison of knee ligament scores and rating systems].

The results of the treatment of knee instabilities are evaluated by different scoring systems including subjective and/or objective criteria. Because of their number and their different criteria a comparison between the scoring systems is still a problem. The aim of this study was to analyze 14 different scoring-systems and prove the comparison of the commonly used rating scales. 116 patients with anterior or anterior-medial knee instabilities were followed up at least 2 years postoperatively. The evaluation was performed according to the criteria of the used rating-scales. The Lysholm I scoring system showed the highest mean total score (92 points). The scales that gave the highest correlation were the Cincinnati and ARPEGE scoring system (r = 0.97). The Lysholm I Scale and the Barrack Scale correlated least well (r = 0.711). This study documents that a transfer of results from one scoring system to another is not possible. A comparison between these scoring systems is only possible after adjusting the total points, the quality and the quantity of each criterion and component of the scoring system. This can done by using a standardized rating scale like the IKDC-score.

Activities of Daily Living↗
PubMedDate not supplied

[Basic equipment for arthroscopic knee surgery].

Five hundred arthroscopic operations were carried out with a 10-part hand-operated instrument set since January 1984. The most frequent operation was meniscectomy (84%), followed by removal of free bodies (18%) and division of plicae (7%). In four cases, there were instrument-dependent complications. By simulation of the surgical work on the joint in a suitable model, undesired, automatic movements of various instruments could be demonstrated. They depended on the respective principle of construction. The reliable grasping of meniscus tissue and free bodies was often a critical phase of the operation. Traction experiments on meniscus preparations showed that the arthroscopic forceps offered are frequently not equivalent to conventional surgical clamps. Instrument breaks were reconstructed in bending experiments. With some materials, a few bending cycles were sufficient in order to bring about the break. The experience obtained in our operations as well as in the laboratory experiments mentioned are described. Criteria for selection and use of hand-operated instruments for arthroscopic knee surgery are enunciated.

Arthroscopes↗
PubMedDate not supplied

[Extracorporeal shockwave therapy in tendionosis calcarea of the rotator cuff: comparison of different treatment protocols].

AIM OF THE STUDY: Extracorporeal shock wave therapy (ESWT) is a new therapeutic procedure for chronically painful calcifying tendinitis of the rotator cuff. The therapy may vary with the number of applied impulses or with impulse energy. Shock waves with an energy of 0.04 to 0.12 mJ/mm2 define low-dose ESWT, in contrast to high-dose ESWT (> 0.12 mJ/mm2). The aim of the study was to verify the hypothesis that either high-dose or low-dose ESWT could be effective if the total amount of applied energy was similar. METHOD: Fifty patients were assigned at random to 2 groups. The treatment consisted of 3 x 5000 low-dose impulses without anesthesia (group 1) and 1 x 5000 high-dose impulses with intravenous analgesia (group 2). The patients were examined at 6 weeks, 3 and 6 months after treatment. X-rays were performed at each visit. RESULTS: The Constant Score improved from 64.5 to 77.5 (group 1) and from 67.2 to 79.4 (group 2) before and 6 months after treatment (p < 0.05). The values on the visual analog scale which ranges from 0 (no pain) to 100 (maximal pain) improved from 76.8 to 48.8 (group 1) and from 75.4 to 45.6 (group 2) before and 6 months after treatment respectively. The final results for both Constant Score and visual analog scale were obtained after 3 months. X-rays showed a complete or subtotal calcific resorption in 8 (group 1, 32%) and 12 (group 2, 48%) patients. CONCLUSION: Extracorporeal shock wave therapy may be an alternative treatment of calcifying tendinitis of the shoulder. Both treatment protocols gave equivalent results.

Adult↗
PubMedDate not supplied

[Material properties of meniscus tissue and the effect of the menisci on the compression behavior of the knee joint].

Specimens of meniscus tissue were taken from different locations of the medial and lateral meniscus. They were tested to failure in the tensometer and force elongation diagrams were recorded. 28 meniscus specimens (14 medial, 14 lateral) gained at autopsy were available for testing. The posterior third of the medial meniscus and the middle third of the lateral meniscus were the strongest and stiffest parts of the meniscus. Yet local differences within one meniscus were only subtle. One clinical significance of these data is, that for replacement of the medial and lateral meniscus the same homogeneous material can be employed. Six tests under compression were carried out using six knee specimens gained at autopsy. Knee compression tests yielded different results after radial cutting of the meniscus, whereas partial meniscectomy had no effect on deformation and hysteresis. These biomechanical results support the concept of partial meniscectomy and preservation of the meniscal periphery. But they cannot be related to the problem of possible degenerative arthritis after partial meniscectomy.

Adult↗
PubMedDate not supplied

[Stress relief of the hip joint by the Thomas splint].

The Thomas Splint is mainly administered to relieve weight from the hip joint. Theoretically the leg is bypassed by transmitting the body weight directly from the pelvis to the floor.--Load transmission via a Thomas Splint was measured with an orthosis strain gauged at the ischial interface area and at the foot plate. The results show, that about one half of the weight will bypass the joint through the orthosis. The Thomas splint ist unsuitable in cases when complete weight relief from the hip joint is necessary.--These results did not depend on whether the floor was flat or ascending, or whether stairs were climbed. The lateral bar never carried more then 25% of the force transmitted.

Adult↗
PubMedDate not supplied

[Vascular injuries in acetabular implantation and acetabular replacement surgery--case report, literature review and anatomical study].

Severe intraoperative bleeding during revision hip arthroplasty in one of our patients was the motive of the work reported here. A review of the literature and an anatomical cadaver study were carried out. The distance between the acetabular fossa and the intrapelvic blood vessels was measured in 15 specimens. The risk for the obturator artery is particularly high. The distance between this vessel and the acetabulum is 2 mm (1-5 mm) only. An account of previous complications and the vascular anatomy as pointed out in our report may help to prevent severe bleeding complications in hip surgery.

Acetabulum↗
PubMedDate not supplied

[Prosthesis for tumor of the hip joint (indications and results)].

Between 1972 and 1982 34 tumour prostheses (23 total replacements, 11 semitotal replacements) of various designs were implanted at the State Orthopedic Clinic in Munich-Harlaching and at the University Orthopedic Clinic in Grosshadern. The indications were primary and secondary malignant tumours, potentially malignant tumours, peritrochanteric pseudarthroses, and loosening of prostheses where bone conditions were poor. Since 1977 only the "Harlaching" femoral tumour prosthesis, a locally developed model, has been used. Its distinguishing feature is the modular or kit principle, which renders it possible to adapt the prosthesis and define its length accurately during surgery. On the basis of 13 long-term observations, in some cases extending over 8 years, it was established that this tumour prosthesis need not be regarded as merely a palliative intervention (this applies also to younger patients with a longer life expectancy); the slight and transitory complications and the relatively good long-term functional results are encouraging.

Bone Neoplasms↗
PubMedDate not supplied

[An in vitro model for producing femoral fractures and for the study of primary stability of cerclage].

PURPOSE: Intraoperative femoral fracture is a well recognized intraoperative complication of cementless total hip arthroplasty (THA). This study was designed to establish an in-vitro model for initiation of fractures of the femur in cementless THA and to assess the effect of fracture fixation by cerclage wiring using steel wire (Protasul). METHODS: Ten human femur specimens were studied. Longitudinal cracks were created by pressing a well fixed conical stem deeper into the femur in a material testing machine. RESULTS: The force necessary to propagate a longitudinal crack in the femur was 1915 N to 9288 N (median 6531 N). This forces are according to 3 to 15 times (median 11 times) body weight. There was no difference of force between left and right femurs from the same individual (U-test). The femoral cortex fractured in 5 cases ventrally, in 6 cases medially and in 1 case laterally. After monofile cerclage wire application the force required to press prosthesis 5 mm deeper into the medullary canal was 0.3 to 2.7 times body weight. After monofile cerclage wire application pressing in the prosthesis 30 mm needed 1.8 to 8.1 times body weight. CONCLUSIONS: During insertion of a conical stem the orthopaedic surgeon should look for fractures of the medial cortex of the femur which is the most frequent location for fractures. This in-vitro model provides a reproductable method for the initiation and propagation of longitudinal femoral fractures in press-fit noncemented THA system and to assess the effect of fracture fixation in the form of cerclage wiring.

Adult↗
PubMedDate not supplied

Epidural vs. intramuscular oxymorphone analgesia after thoracotomy in dogs.

Oxymorphone was administered epidurally (0.1 mg/kg) or intramuscularly (IM) (0.2 mg/kg) to 16 dogs undergoing thoracotomy, to compare the analgesic effectiveness. Heart rate, respiratory rate, systolic and diastolic blood pressure, and pain score were measured hourly. Arterial blood gases were measured at hour 1. A single dose of oxymorphone injected epidurally provided analgesia for up to 10 hours, whereas the IM route provided a comparable effect for less than 2 hours. There were statistically significant increases in heart rate, and systolic and diastolic blood pressures at hour 2 in the dogs treated IM over the dogs treated epidurally. We conclude that epidurally administered oxymorphone is highly effective in alleviating pain after thoracotomy in dogs and provides longer lasting analgesia than the IM route.

Analgesia, Epidural↗
PubMedDate not supplied

Primary stability of press-fit-implanted osteochondral grafts. Influence of graft size, repeated insertion, and harvesting technique.

The aim of this study was to evaluate the fixation strength of press-fit-implanted osteochondral grafts with respect to graft size (length and diameter), the effect of repeated insertion after pullout, and harvesting technique. Experiments were performed using the Osteochondral Autograft Transfer System on porcine femoral condyles. Failure loads of 10-mm-long grafts (mean, 47 N) were significantly lower than failure loads of 15-mm-long grafts (mean, 93 N) and 20-mm-long grafts (mean, 110 N) (all grafts, 11 mm in diameter). Reinsertion of the 15-mm-long grafts after initial pullout resulted in a significant reduction of failure loads (mean, 93 N versus 44 N). Failure loads of 8-mm-diameter grafts (mean, 41 N) were significantly lower than those of 11-mm-diameter grafts (mean, 92 N) (all 15 mm long). Levering of the tubular chisel during graft harvest significantly decreased press-fit stability as compared with simple turning of the chisel (mean, 32 N versus 52 N) (8-mm diameter and 15-mm length). These results suggest that primary fixation strength of press-fit-inserted osteochondral grafts depends on the size of the grafts and that repeated pullout and reinsertion of grafts as well as a nonoptimal harvesting technique (levering) will reduce primary stability.

Animals↗
PubMedDate not supplied

Reconstruction of the anterior cruciate ligament. A new positioning and fixation technique.

A new technique for ACL reconstruction is presented. The middle third of the patellar tendon is anchored to the inner surface of the lateral femoral condyle under direct visual control. The transplant is fixed tibially beneath a bone block removed from the ventral tibial head. Thirty-three patients were evaluated preoperatively and 27 months (range, 24 to 30 months) postoperatively. The mean preoperative function score (Lysholm scoring scale) was 72 +/- 14 points; the mean postoperative score was 84 +/- 13 points. The Lachman test was positive for all patients preoperatively, but the test results in the postoperative follow-up examination were negative--1+ in 31 knees and 2+ in 2 knees. All 33 knees elicited a definite "hard" end point. The postoperative KT-1000 measurement for anterior tibial displacement showed no significant difference between the operated versus the unoperated knee. Before their knee injury all patients had been engaged in sports. At the follow-up examination, 13 patients had made a full return to their former sports activities, 13 were restricted in their sports activities, and 7 patients no longer participated in sports.

Adult↗
PubMedDate not supplied

Primary stability of interference screw fixation. Influence of screw diameter and insertion torque.

Interference screw fixation is frequently used in anterior cruciate ligament reconstruction with the bone-patellar tendon-bone graft. There have been no data available about the influence of screw diameter and insertion torque on primary stability. We designed a cadaveric study using paired knees to analyze the comparative effectiveness of 20-mm long screws of different diameters (9 mm versus 7 mm) and the significance of torque during screw insertion. Testing to failure was performed in a tensiometer with a crosshead speed of 200 mm/min. After slippage of a bone peg in the 7-mm screw specimens, the experiment was repeated in each specimen with a 9-mm screw fixation. Maximum tensile force was greater at the femoral insertion than at the tibial site. Results of refixations with 9-mm screws were only slightly inferior to the original 9-mm screw fixation specimens. Our results further showed that the torque can be used as a predictor of the stability of the bone block but cannot be used as an indicator for the strength of the reconstruction. The 7-mm screws are not recommended for tibial fixation. Failed 7-mm screw fixations can be replaced by 9-mm screws and refixations were successful in our study model.

Adult↗
PubMedDate not supplied

Sports injuries in team handball. A one-year prospective study of sixteen men's senior teams of a superior nonprofessional level.

One hundred eighty-six players of 16 teams in 2 male team handball senior divisions were observed prospectively for 1 season to study the injury incidence in relation to exposure in games and practices. Ninety-one injuries were recorded. Injury incidence was evaluated at 2.5 injuries per 1000 player-hours, with a significantly higher incidence in game injuries (14.3 injuries per 1000 game-hours) compared with practice injuries (0.6 injuries per 1000 practice-hours). Practice injury incidence was higher in the lower performance level group, and game injury incidence was higher in the high-level group. The upper extremity was involved in 37% of the injuries, and the lower extremity in 54%. The knee was the most commonly injured joint, followed by the finger, ankle, and shoulder. Knee injuries were the most severe injuries, and they were more frequent in high-level players. There was an increase in the severity of injury with respect to performance level. The injury mechanism revealed a high number of offensive injuries, one-third of them occurring during a counterattack. The injury pattern showed certain variations with respect to player position and performance level. Prophylactic equipment was used by a majority of players at the higher performance level.

Adult↗
PubMedDate not supplied

America speaks. Was anyone listening?

Town meetings are a uniquely American political device intended to allow citizens to have a voice in the course of the local or even national policymaking process. On January 14, 1992, Democratic members of the U.S. House of Representatives conducted 140 such meetings to discuss health care reform. While the discussions ranged from the ridiculous to the sublime, Americans made it clear that they are fed up with a current system that they believe costs too much and provides too little. But a key question remains: Who, if anyone, was listening? House Democrats appear determined to avoid specifics and to pin President Bush with an "anti-health" label. The strategy is a risky one; a riled up populace could well turn against those who convinced them to be concerned in the first place.

Attitude to Health↗