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Biomedical subjects

D Kohn

Publications and source records attributed to D Kohn.

At least 19 recordsLinked to original sources
PubMed2001

[Hip arthroscopy. Minimal invasive diagnosis and therapy of the diseased or injured hip joint].

Arthroscopy of the hip joint has developed into a useful tool for the hip surgeon. Hip joint anatomy, however, makes special demands of the arthroscopist. He needs to be familiar with the arthroscopic anatomy of the hip and its variations. Moreover, he should have practical training in the technique of hip arthroscopy prior to his first intraoperative experience in order to avoid complications. A complete arthroscopic inspection of the hip can be achieved by using a combined procedure: whereas the central hip compartment can be scoped only by distraction of the joint, the periphery can be better seen without traction. Whether to place the patient supine or lateral is dependent on personal experience. No matter which position is used, the positioning technique has to be exact. The literature has shown that most complications are related to traction. Before the first portal is placed, the joint vacuum force should be broken by distension of air or fluid. This leads to maximum distraction of the joint and reduces the risks of damage to labrum and cartilage during first access to the joint. For a diagnostic round through the central compartment, at least two portals have to be placed. The use of a 3-portal technique increases the range of inspection. Due to the relatively thin soft tissue mantle and greater distance to neurovascular structures, the anterolateral or lateral portal should be used as the first portals to the central compartment. In addition, the anterolateral portal is the standard portal to the periphery of the hip. The posterolateral or anterior portal should be used as a supplementary portal. The following indications have been described for an arthroscopic procedure of the hip: loose bodies, labral lesions, synovial diseases such as chondromatosis and pigmented villonodular synovitis, associated lesions in underlying osteoarthritis, ruptures of the teres ligament, malorientation of the acetabulum and proximal femur and, last but not least, "idiopathic" hip pain. The use of hip arthroscopy in infectious arthritis, avascular necrosis of the femoral head, Perthes' disease, osteochondrosis dissecans and complications after total hip replacement is less frequent. Here, in addition to its diagnostic value, operative arthroscopy of the hip offers removal of loose bodies, resection of the labrum and ligaments, synovial biopsy, partial synovectomy, microfracturing, lavage and placement of intraarticular drainage. The first results of arthroscopic procedures in the hip are promising. In addition to its diagnostic value and contribution to the understanding of intraarticular anatomy and pathology, recent studies have demonstrated the advantages of the arthroscopic treatment of the hip.

Arthroscopy↗
PubMed2001

[Meniscus reconstruction. Established and innovative methods].

After the first description of meniscus repairs in the literature it took nearly a century until they were routinely performed in orthopaedic surgery. The scientific basis for meniscus reconstruction needed to be elaborated, including the study of the anatomy, and for instance the vascularisation and the function of the meniscus. After the first experiences with open repair, several arthroscopic techniques have been developed. It has been shown that several factors could influence the healing rate of meniscus lesions. One of the major factors is knee stability. Meniscus repairs performed in conjunction with reconstruction of the anterior cruciate ligament (ACL) have shown higher healing rates (generally > 75%) than isolated repairs, either in stable (50-75% healing rate) or in unstable knees (< 50% in some studies). The localization of the tear is probably the most important factor influencing the healing rate of meniscus repairs. Peripheral tears which are located in the vascular zone of the meniscus heal better than centrally located tears in the avascular area. Many efforts have been provided to enhance the vascularity in this part of the meniscus. None of the proposed techniques have been proven to be definitively effective, or they are too demanding for routine use. Conventional meniscus suture techniques are time-consuming, technically demanding and necessitate incisions at risk for neurovascular structures. In order to simplify meniscus repair several new implants have been developed. They have different forms and are made of different materials among which some are biodegradable. The first clinical results with these techniques are encouraging. However, some new complications have been described. Their incidence and the fate of intraarticular biodegradable devices still has to be defined, especially in the long-term. The present study describes the actual knowledge of meniscus repair and presents the new techniques. It also shows that several questions concerning meniscus repair still need to be answered, and points out the need for further controlled studies.

Anterior Cruciate Ligament↗
PubMed2001

[Effect of various suture strength factors on behavior of meniscus sutures in cyclic loading conditions].

The aim of this study was to analyze meniscal sutures under cyclic loading conditions for different suture types (vertical and horizontal mattress sutures) and suture materials (absorbable monofilament sutures: PDS 2-0; PDS-0, and PDS-1 USP). Testing was performed on medial porcine menisci, using a well-established biomechanical testing model with a complete longitudinal tear 3 mm from the periphery of the meniscus. Sixty specimens were used. One suture was tested at a time. During cyclic testing 100 load cycles were applied with a crosshead speed of 50 mm/min. Three different maximum loads (10 N, 20 N, and 40 N) were used. The preload was set at 5 N. After cyclic loading, the specimens were loaded until failure. During cyclic loading, a gap appeared between the two parts of the meniscus, and partial tissue failures were observed at the surface of the meniscus. Gapping was more marked with higher loads and with the weaker suture material (p < 0.001). Using PDS 0 and PDS 1 sutures, less partial tissue failures were observed compared to PDS 2-0 (p < 0.001). The ultimate failure loads after cyclic loading were higher with PDS-0 and PDS-1 sutures. With these suture materials vertical sutures were stronger than horizontal sutures (p < 0.05). Using PDS 2-0 this difference could not be found. These results show that the primary strength of meniscal sutures depends on the suture material. The frequency and the amount of gapping and partial tissue failures, which can be observed under cyclic loading, are less distinct with PDS-0 and PDS-1 compared to PDS 2-0. From a biomechanical point of view, PDS 0 and PDS 1 sutures are recommended for meniscal sutures to guarantee a high primary stability, a small amount of gapping, and few partial tissue failures.

Animals↗
PubMed2001

[Approach to open treatment of osteochondral lesions of the talus].

Arthroscopic techniques still represent the treatment of choice in osteochondral lesions of the talus (OLT). Open techniques may be used as an alternative or may be complementary to arthroscopic treatments. They are especially indicated in cases of large osteochondral lesions, difficult localisations and in cases of recurrent interventions. In addition to the type of treatment for the lesion itself, the choice of an ideal surgical approach is of paramount importance. Indications, operative technique, possible complications and rehabilitation are described in detail for each approach. Anterolateral, anteromedial, posterolateral and posteromedial soft-tissue approaches as well as medial and lateral malleolar osteotomies are discussed. If a distraction is not desired with arthroscopy, posteromedial and posterolateral soft-tissue approaches offer a good alternative for the treatment of posterior OLT. Osteotomy of the (medial) malleolus offers good visualisation of the medial talar dome. With the introduction of new techniques of osteochondral transplantations, the use of this approach is becoming more popular. However, it is an invasive technique and the risk of secondary osteoarthritis after malleolar osteotomy still needs to be determined.

Ankle Injuries↗
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↗
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↗