PubMed Health⌕ Search

Biomedical subjects

D Kohn

Publications and source records attributed to D Kohn.

At least 37 records · Page 2Linked to original sources
PubMed2002

Clinical characteristics of 13 solid organ transplant recipients with ganciclovir-resistant cytomegalovirus infection.

BACKGROUND: Ganciclovir-resistant (GCV-R) cytomegalovirus (CMV) is now being reported with increasing frequency in solid organ transplant recipients. OBJECTIVE: To describe the clinical characteristics and outcomes of all solid organ transplant patients with GCV-R CMV seen between 1990 and 2000 at a single center. METHODS: Patients with clinically suspected GCV resistance had viral isolates subjected to phenotypic analysis by plaque reduction assay, and also genotypic analysis. Medical records of the 13 patients with GCV-R CMV were reviewed for demographic, microbiologic, clinical, and pathologic data. RESULTS: Thirteen patients were identified, including 5 kidney, 1 heart, and 7 lung transplant recipients. All but one patient (92%) were CMV donor seropositive, recipient negative (D+/R-), and 11/13 (85%) had tissue-invasive CMV. CMV viremia was recurrent in 9/13 (69%); in 2 others, the first CMV episode was fatal. Overall, 9/13 (69%) of patients have died, all of CMV or its complications. Of the 10 who received foscarnet, only one survived. All patients had received GCV-based prophylactic regimens; 8/13 patients (62%) had received CMV hyperimmune globulin (CMVIG) as part of prophylaxis, 6/13 (46%) had received oral ganciclovir, and 5/13 (38%) had received intermittent (3 x/week) IV ganciclovir for prophylaxis. CONCLUSIONS: GCV-R CMV is associated with CMV D+/R- status, tissue-invasive disease, and high mortality even with foscarnet therapy. Exposure to less than fully therapeutic levels of GCV, in the form of oral or intermittent IV GCV, is common. The use of CMVIG in prophylaxis does not appear to prevent resistance. Further work remains to be done to elucidate the risk factors and optimal mode of prophylaxis and treatment for GCV-R CMV.

Cytomegalovirus↗
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

[Biomechanical properties of interference screw implantation in replacement of the anterior cruciate ligament with patellar and hamstring transplants. An experimental study using roentgen stereometry analysis (RSA)].

This experimental roentgen stereometric analysis (RSA) study was performed to measure micromotions between the graft and tunnel under submaximal load in anterior cruciate ligament (ACL) reconstruction. The aim was to evaluate the maximum load at failure, linear stiffness, and slippage of bone-patellar-tendon-bone (BPTB) grafts fixed with interference screws compared to quadrupled hamstring grafts fixed with interference screws. We used 15 porcine tibia specimens for the study. In the BPTB group, the 10 x 25-mm bone plugs were fixed in a tunnel with 10 mm in diameter using a 7 x 25-mm titanium interference screw (n = 5) or a biodegradable screw (n = 5). The five hamstring transplants were folded to a four-stranded graft and armed with a baseball stitch suture. The sutured side was fixed with a 7 x 25-mm biodegradable polylactide screw in an 8-mm tunnel. The tibial bones, tendon grafts, and interference screws were marked with tantalum beads. The grafts were mounted to a custom made load frame and loaded parallel to the axis under RSA control increasing the force in steps of 50 N. Micromotions between bone plug, screw, and tibia were measured with RSA. Accuracy of RSA for the in vitro study was evaluated as 0.05 mm. Hamstring grafts failed at significantly lower maximum loads (492 +/- 30 N) than BPTB grafts (658 +/- 98 N). Linear stiffness of the hamstring graft fixations was eight times lower compared to the BPTB grafts (403 +/- 141 N/mm vs 3500 +/- 1300 N/mm). There was no significant difference between the biodegradable and titanium screws in the BPTB group. Slippage of the graft started at 82 +/- 35 N load in the hamstring group and at 428 +/- 135 N in the BPTB group. Slippage of the graft at 75% of the maximum pull-out strength was measured as 0.36 +/- 0.25 mm in the BPTB and 2.58 +/- 1.08 mm in the hamstring group. The interference screw fixation of a quadrupled hamstring graft showed a lower linear stiffness and an earlier slippage compared to a patellar tendon bone plug. Slippage of the hamstring grafts at submaximal loads may result in fixation failure during rehabilitation.

Animals↗
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↗