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Biomedical subjects

D Kohn

Publications and source records attributed to D Kohn.

At least 37 records · Page 2Linked to original sources
PubMed2001

The internal calcar septum (femoral thigh spur) in computed tomography and conventional radiography.

OBJECTIVE: The femoral "thigh spur", a cortical septum in the region of the lesser trochanter of the human femur, was first described and named by the German anatomist Merkel in 1874, but it was never examined in detail. To evaluate the frequency and the shape of this structure, a combined anatomical and radiological study was performed using saw-cuts from specimens, high-resolution CT and conventional radiography. DESIGN: Thirty human cadaveric femora of central European origin were analyzed by high-precision computed tomography (CT) using thin slices and high-resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of high-density bone formations and for three-dimensional imaging. Additionally three macerated femur specimens were cut exactly corresponding to the CT slices. The computed images were validated with the anatomical saw-cuts. RESULTS: A dense trabecular ridge protruding endosteally from the posteromedial cortex was found in all femora. This cortical septum reaching from the femoral neck to the distal part of the lesser trochanter separated the femoral cavity from the cancellous bone inside the lesser trochanter. On conventional radiography the femoral thigh spur could be visualized best in the frog-lateral view of the hip. CONCLUSION: The internal calcar septum is a constant cortical structure. It should be recognized when radiographs or CT images of the proximal femur are interpreted. It could be of importance for metaphyseal fitting of an endoprosthetic stem.

Aged↗
PubMed2001

Blood loss in anterior cruciate ligament (ACL) reconstruction with and without intercondylar notchplasty: does it affect the clinical outcome?

Blood loss is associated with any surgical procedure and should be reduced wherever possible. It was our impression that notchplasty adds to the amount of postoperative bleeding after anterior cruciate ligament (ACL) reconstruction. With posterior placement of the tibial tunnel, notchplasty is optional in many cases. This study aimed to quantify blood loss with and without notchplasty after arthroscopically assisted ACL reconstruction using bone-patellar tendon-bone autografts. We performed a prospective clinical study of 58 patients, who had undergone arthroscopically assisted autogenous patellar tendon ACL reconstruction. In group I, a notchplasty was necessary according to the local anatomical criteria (intraoperative impingement test). In group II, ACL replacement could be performed without notchplasty. Single and total day drainage volume, serum and suction drain hemoglobin (Hb) and hematocrit (Hct) levels were monitored. One year after surgery, the patients were reviewed to assess the outcome according to the IKDC and Lysholm scores and the KT-1000 arthrometer. The total drainage volume was 448 ml (range 150-550 ml) in group I and 299 ml (range 50-420 ml) in group II (p < 0.001). The serum hematocrit (Hct) decrease was 9.7% in group I and 7.4% in group II (p < 0.001). At 12 months after surgery, the IKDC and Lysholm score evaluations and the KT-1000 arthrometer measurements revealed no clinical differences between the notchplasty and non-notchplasty groups. Despite a 30% increase in blood loss, notchplasty has been shown to be a useful procedure to prevent graft impingement without negative side-effects.

Adult↗
PubMed2001

Fracture of the proximal tibia six months after Fulkerson osteotomy. A report of two cases.

The Fulkerson osteotomy has proved to be a reliable treatment for subluxation of the patella due to malalignment. Aggressive rehabilitation in the early postoperative period is unwise since the proximal tibia is weakened by the oblique osteotomy. Early weight-bearing and unrestricted activity have caused fractures in a few patients. Even late in the postoperative period the osteotomy may adversely influence the biomechanical properties of the proximal tibia. We describe two athletes who sustained a fracture of the proximal tibia, during recreational activities, six months after a Fulkerson osteotomy. Both had been bearing full weight for about ten weeks without complaint. Bony healing of the osteotomy had been demonstrated on plain radiographs at ten and at 12 weeks. After a Fulkerson osteotomy, jogging and activities which impose considerable impact force should be discouraged for at least nine to 12 months.

Adult↗
PubMed2001

[Birbeck granules in epidermal Langerhans cells of elderly patients with decubital ulcers].

UNLABELLED: Birbeck granules (Bg), known also as Langerhans cell (L) granules are special organelles found in the L cells' cytoplasm, which serve as a marker for their identification. These organelles have been studied in epidermal L cells in elderly patients with pressure sores and were compared to those found in epidermal L cells of healthy volunteers who served as controls. RESULTS: There was an increase of about 47% in the number of B granules in patients' L cells from sacral epidermis near lesion (p < 0.01) and an increase of about 68% of the number of B granules in patients' L cells from normal epidermis (p < 0.005) was found as compared to healthy control L cells. Part of the B granules in patients' L cells were of similar morphology to those of controls. They were found throughout the cytoplasm as simple rods or rackets. In addition, in patients' epidermis some irregularly shaped granules were observed, such as: racket structure common to two or more rod structures; rod shaped granules in direct continuity with mitochondria, and others with lysosomes. Moreover, B granules in continuity with the cell plasma membrane and groups of closely opposed rod shaped granules were observed. These two last shaped structures apparently reflected formative stages of B granules. It is suggested that an increase of the number of B granules indicated an active state of L cells in the epidermis of patients studied. It is not clear whether the morphologic alterations of B granules influence the L cell functions in antigen presentation. It is possible that they may be partly involved in infections which occur frequently in patients with decubital ulcers. It is also possible that the increase in the number of B granules and the altered structures found among them in patients' epidermis express a reaction of L cells to inflammation.

Aged↗
PubMed2000

Primary lumbosacral stability after open posterior and endoscopic anterior fusion with interbody implants: a roentgen stereophotogrammetric analysis.

STUDY DESIGN: After posterior stabilization of the spondylolytic lumbosacral level, mobility of the fused vertebrae could be studied before and after an additional anterior endoscopic interbody fusion using roentgen stereophotogrammetric analysis. OBJECTIVE: To determine the in vivo primary lumbosacral stability of additional anterior interbody fusion after transpedicular screw fixation. SUMMARY OF BACKGROUND DATA: In vitro studies indicate a significant decrease in segmental motion after pedicle screw fixation and additional anterior fusion. Roentgen stereophotogrammetric studies demonstrate the adequacy of transpedicular lumbar instrumentation in posterolateral fusions. There are no studies examining the effect of additional anterior interbody fusion after posterior instrumentation in vivo. METHODS: In this study, 15 patients with low-grade spondylolisthesis at L5-S1 underwent a two-stage open posterior and endoscopic anterior lumbar fusion using carbon fiber (Brantigan I/F) cages. At surgery, tantalum markers were implanted into the fifth lumbar (L5) and the first sacral (S1) vertebra. All the patients were examined by roentgen stereophotogrammetric analysis after the first and second surgical procedures. RESULTS: After implantation of the posterior pedicle system only, the mean intervertebral mobility determined by roentgen stereophotogrammetric analysis was 0.23 mm in the transverse (x), 0.54 mm in the vertical (y), and 1.2 mm in the sagittal (z) axes. After additional anterior endoscopic fusion with carbon cages, the remaining translation between the fused segment L5/S1 decreased to 0.17 mm in the x, 0.16 mm in the y, and 0.44 mm in the z axes. CONCLUSION: Anterior endoscopic lumbosacral fusion significantly increases the primary stability of the posterior fusion with a pedicle system in two axes of motion.

Biocompatible Materials↗
PubMed2000

[Strategies for interventional revisions in failed anterior cruciate ligament reconstruction].

Anterior cruciate revision reconstruction is gaining more and more importance. Postoperative infection, a painful knee, limited range of motion and instability may make a second operation necessary. Results after revision ACL reconstruction are worse than results after primary ACL reconstruction. Analysis of the causes of failure and a therapeutic concept that is tailored to the individual case are preconditions for a successful reintervention. Revision ACL reconstruction has to be performed by an experienced knee surgeon who masters all the necessary techniques, from arthroscopy to arthrotomy and should be carefully planned.

Anterior Cruciate Ligament↗
PubMed2000

[Donor site problems after anterior cruciate ligament reconstruction with the middle third of the patellar ligament].

In a retrospective study we examined the clinical and sonographic changes after anterior cruciate ligament reconstruction with lig. patellae. 51 patients were evaluated clinically and sonographically after arthroscopically assisted ACL-reconstruction with a bone-patella tendon 3-6 years (mean 4.3 years) postoperatively. Certainly 18 patients (35%) reported about an anterior knee pain, but only 2 patients (4%) complained about pain during activities of daily living and 3 patients (6%) about pain during slight sports activities. Retropatellar crepitations was found in 24 patients (47%) on the operated side and at 11 patients (22%) on the non operated side. Twenty nine patients (57%) complained about a discomfort or pain when kneeling on the operated side. In 13 patients (26%) sonography showed a shortening of the patella ligament by 4 mm or more. Only few patients are strongly limited in their activity by the anterior knee pain. Neither our results nor the literature give evidence, that the tendon defect is the underlying cause of this pain syndrome. However, the number of patients with pain during kneeling on the operated side was relatively high. The semitendinosus gracilis graft should be considered for patients who have to knee during working or recreational activities.

Anterior Cruciate Ligament↗
PubMed2000

[Osteonecrosis of the hip joint in adulthood. Significance of various corrective osteotomies].

The importance of osteotomies in treatment of osteonecrosis of the femoral head has decreased. However, with proper selection of the patient, osteotomies are still useful for small stage III or IV lesions in patients younger than 45 years, and with no ongoing causes for progressive osteonecrosis such as the use of high doses of corticosteroids, chemotherapy, and chronic alcoholism. For preservation of natural hip joint function, the necrotic segment is moved away from the load-transmitting area of the acetabulum, and weight-bearing forces are redistributed to articular cartilage that is supported by healthy bone. In addition to radiographic evaluation, MRI is most accurate for imaging of the stage, localization, and extent of osteonecrosis in planning and selecting osteotomy.

Adult↗
PubMed2000

[Knee endoprosthesis: aspects of surgical techniques].

The implantation of a condylar knee has remained a challenge for surgeons and the equipment of the hospital. In contrast to total hip arthroplasty, not only is the correct insertion of the implant crucial, but also the treatment of the surrounding soft tissues. Mediolateral soft tissue balance and balance between flexion and extension gaps, as well as centering the patella, have to be done carefully. The soft tissue envelope of the knee joint is thin and prone to necrosis after multiple incisions. Damage to the extension mechanism can make a total joint useless. Tearing the patellar ligament from the tibial tuberosity must therefore be avoided by all means during operation. Precise cutting of the distal femur is only possible if excellent equipment is used by a skillful surgeon. The same is true for orientating saw cuts related to the long leg axes. These tasks can probably be taken over by navigation systems and robots in the future. Because the definite choice of implants has to be made intraoperatively, a complete modular system has to be present in the hospital. Only hospitals that can properly equip their surgeons to manage upcoming soft tissue problems and bony deficiencies should offer treatment to patients requiring condylar knee arthroplasty.

Arthroplasty, Replacement, Knee↗
PubMed2000

Reliability and interobserver variability in radiological patellar height ratios.

This study evaluated the reliability and interobserver variability of five patellar height ratios as measured by two examiners on standard radiographs: Insall-Salvati (IS), modified Insall-Salvati (MIS), Blackburne-Peel (BP), Caton-Deschamps (CD), and Labelle-Laurin (LL). Plain lateral radiographs with a knee flexion angle of 20 degrees for IS, MIS, BP, and CD ratios and 90 degrees for the LL method of 22 knees of 21 patients with varying pathological knee conditions were analyzed. Statistical results revealed a low interobserver variability with high correlation coefficients (0.86 for IS, 0.82 for MIS, 0.86 for BP, 0.92 for CD, and 0.81 for LL; P > 0.3) and low mean interobserver errors. However, regarding the reliability of the radiographic results of the different methods for patella alta, baja, or norma we found varying results in 68% of the patients. In two patients the patellar height was classified as alta, norma, or baja depending on the ratio used. Regarding the definitions of patellar height used by the authors of these methods, we found the lowest number of normal patellae with the IS ratio and no patella alta for the CD ratio. The LL method revealed the highest number of patella alta. The BP ratio showed intermediate results for both patella alta and baja, being the most moderate method. This study showed that there was a good interobserver reliability for the evaluation of patellar height according to the common radiological ratios. However, the high frequency of differing results between the different radiographic ratios showed that patellar height classification as "alta," "norma," or "baja" depends heavily on the chosen index. The differing results were due mainly to the normative patellar height data and to anatomical differences. Based on these findings we recommend a ratio using the articular surface of the patella in relation to the joint line. We recommend the BP method because it revealed the lowest interobserver variability and discriminated best among the groups alta, norma, and baja.

Adolescent↗
PubMed2000

Extracorporal shock wave therapy in patients with tennis elbow and painful heel.

The aim of this study was to evaluate the effect of extracorporal shock wave therapy (ESWT) in tennis elbow and painful heel. Nineteen patients with tennis elbow and 44 patients with painful heel in which conservative treatment had failed underwent ESWT. Both groups received 3000 shock waves of 0.12 mJ/mm2 three times at weekly intervals. After a follow-up of 5 and 6 months respectively, pain measured on a visual analogue scale (VAS) decreased significantly in both groups. The success rate (excellent and good results) was 63% in tennis elbows and 70% in painful heels. ESWT seems to be a useful conservative alternative in the treatment of both conditions.

Adult↗
PubMed2000

Acute ulnar nerve compression syndrome in a powerlifter with triceps tendon rupture--a case report.

We report on the case of a bodybuilder and powerlifter who suffered from triceps tendon rupture complicated by acute ulnar nerve compression syndrome. The diagnosis was made clinically, radiologically, and sonographically. Ultrasound was helpful to demonstrate a large hematoma at the site of the injury. Early surgical intervention confirmed the presence of the hematoma compressing the ulnar nerve and led to a complete restoration of ulnar nerve and triceps muscle function. Few reports on distal triceps rupture have been published but its complication by acute ulnar nerve compression has not been reported on yet despite the close anatomical relationship of both structures.

Adult↗
PubMed2000

Effect of zinc supplementation on epidermal Langerhans' cells of elderly patients with decubital ulcers.

In the present study, Langerhans' cells (LCs) in the sacral epidermis, 8-10 cm from lesions of patients (mean age 71 years) with decubital ulcers, were compared ultrastructurally and morphometrically with those in the patients' own normal epidermis from the upper leg, before and after supplementation with 50 mg/day elementary zinc (in the form of a 220-mg tablet of Avazinc, administered once daily) for four months. Zinc intake resulted in from 80% to full healing of the decubital ulcers in the patients studied. The percentages of LCs were low in both perilesional sacral epidermis (2.07 +/- 0.71%) and in control leg epidermis (2.71 +/- 1.38%) before zinc supplementation and also afterward (2.12 +/- 0.16% and 2.59 +/- 0.88%, respectively). LCs demonstrated a more dendritic morphology after zinc supplementation: 68.15 +/- 9.28% and 77.0 +/- 3.45% of sacral and of control leg epidermal LCs, respectively, had dendrites before, and 91.52 +/- 3.43% and 84.15 +/- 3.64% of sacral and of control leg epidermal LCs, respectively, had dendrites after zinc supplementation. The LC section area in the sacral epidermis near the lesion as well as in the control leg epidermis and the number of LC granules in LC sections were not affected by zinc supplementation. The higher percentage of LCs having dendrites in the epidermis of patients with decubital ulcers after zinc supplementation may indicate that these LCs are in a more motile state, which might affect the healing process of the lesions.

Administration, Oral↗
PubMed2000

Gene therapy for adenosine deaminase deficiency.

The clinical gene therapy trials for adenosine deaminase (ADA) deficiency have defined both the potential benefits and the present limitations of gene therapy with hematopoietic stem cells (HSC). Current clinical results indicate that (a) both umbilical cord blood and neonatal bone marrow HSC can be transduced with murine retroviral-based vectors, (b) the transduced HSC can engraft in nonmyeloablated patients, (c) the frequency of HSC transduction/engraftment is low (1/10,000), (d) an in vivo selective advantage can exist for transduced T lymphoid progeny, and (e) the transduced ADA gene is not expressed in nondividing T lymphocytes. Improving the clinical results of gene therapy for ADA deficiency and other genetic diseases involving HSC will require (a) developing new vectors that express the transduced gene in nondividing cells and (b) increasing the frequency of stable HSC transduction.

Adenosine Deaminase↗
PubMed2000

The influence of avascularity on the mechanical properties of human bone-patellar-tendon-bone grafts.

Our aim was to analyse the effect of avascularity on the morphology and mechanical properties (tensile strength, viscoelasticity) of human bone-patellar-tendon-bone (BPTB) grafts in vitro. These were harvested at postmortem and stored submerged in denaturated human plasma at a constant pH, pO2, pCO2, temperature and humidity under sterile conditions. Mechanical testing was performed two and four weeks after removal of the graft. The mean ultimate strength was 1085.7 +/- 255.8 N (control), 1009.0 +/- 314.9 N (two weeks cultured) and 1076.8 +/- 414.8 N (four weeks cultured). There was no significant difference in linear stiffness or deformation to failure between the groups. There was a difference in viscoelasticity between the control group and the avascular grafts and the latter had significant lower peak load-to-load ratios after 15 minutes compared with the control group. After two and four weeks the graft contained viable fibroblasts. There was regular cellularity in the superficial layers and decreased cellularity in the midportion. The structure of the collagen including the crimp pattern appeared to be normal in polarised light. We conclude that avascularity does not significantly affect ultimate failure loads or stiffness of BPTB grafts. Slight changes in viscoelasticity were induced, but the significance of the increased stress relaxation is not fully understood.

Adult↗