Biomedical subjects

Karsten Labs

Publications and source records attributed to Karsten Labs.

7 recordsLinked to original sources

PubMed2003

Acute arterial occlusion after total knee arthroplasty.

The duration of the ischemic time in total knee arthroplasty is currently considered to be an important predictor for the development of arterial thrombosis. In the following, we describe two patients with thrombotic occlusions of the popliteal artery. After the first one had been operated on under ischemic conditions, the ischemic time was limited to the cementing phase in the second case on the basis of this experience, but an arterial occlusion occurred in this case as well. In neither case did immediate vascular surgery lead to clinical restrictions. Our observation demonstrates that arterial thromboses can occur regardless of the duration of ischemia and that surgery should therefore be performed without ischemia if risk factors are present.

Aged↗

PubMed2003

Tumoral calcinosis revisited: pathophysiology and treatment.

In two renal failure patients, tumoral calcinoses were observed as a result of secondary hyperparathyroidism. The primary conservative therapy conducted with dietetic measures and phosphate-binding medication could not prevent the progression of the massive polytopic foci. Therefore, a subtotal parathyroidectomy was performed in one case, after which a rapid complete regression of the tumours was observed, with the exception of one location where the finding remained progressive. The second patient declined surgical intervention on the parathyroid gland. Therefore, the foci were only resected, whereby local recurrences were observed. Renal failure patients with tumoral calcinosis should undergo subtotal parathyroidectomy after initial conservative therapy. In view of the high risk of recurrence, local excision is a treatment procedure to be considered in exceptional cases only.

Adult↗

PubMed2003

The influence of walking speed on kinetic and kinematic parameters in patients with osteoarthritis of the hip using a force-instrumented treadmill and standardised gait speeds.

BACKGROUND: It is difficult to identify objective parameters for assessing the joint function when dealing with the evaluation of orthopaedic procedures, especially endoprosthetic hip replacement. Clinical gait analysis enables parameters of force and movement to be quantified. However, the influence of gait speed on these parameters has hardly been taken into consideration so far. The objective of the present study was therefore to investigate the effect of gait speed on gait parameters and to simplify the clinical conditions in patients with osteoarthritis of the hip by determining a standardised gait speed. METHODS: A total of 28 patients with severe unilateral osteoarthritis of the hip were investigated at different gait speeds. The gait analysis equipment used consisted of an infinitely adjustable treadmill with force plates and an infrared video system. A special control mechanism permitted adjustment of the treadmill speed to a patient's self-determined pace. RESULTS: The mean gait speed of all patients with osteoarthritis of the hip was set at 2.20 km/h (0.61 m/s). Eight of the 10 gait parameters assessed increased significantly with changing gait speed. Pathological changes in gait patterns were found at the three gait speeds investigated, with the changes more accentuated at higher speeds. CONCLUSIONS: Dependence of gait parameters on gait speed could be concluded for a group of patients and for control subjects. Use of a force-instrumented treadmill is necessary for the setting of a standard gait speed, which should be set as high as achievable by patients without inducing pain and problems of coordination or balance. With the usage of standardised speeds, clinical gait analysis becomes easier to perform. Furthermore, one can assess the expected biomechanical advantages of newer prostheses, thus providing the surgeon with a basis for further decisions.

Biomechanical Phenomena↗

PubMed2003

Rheumatoid arthritis of the shoulder joint: comparison of conventional radiography, ultrasound, and dynamic contrast-enhanced magnetic resonance imaging.

OBJECTIVE: To determine the role of ultrasound and magnetic resonance imaging (MRI) compared with conventional radiography in the detection of chronic and acute inflammatory manifestations of rheumatoid arthritis (RA) of the shoulder joint. METHODS: Forty-three consecutive patients with known RA prospectively underwent clinical examination, radiography, ultrasound, and MRI of the shoulder joints. Each patient was assigned a clinical/laboratory score consisting of 7 parameters, including measurements of shoulder mobility, the erythrocyte sedimentation rate, and C-reactive protein level. Conventional radiography was standardized and performed in 2 planes. Ultrasound was performed in 10 predefined planes using a 7.5-MHz linear transducer. MRI at 1.5T comprised transverse and oblique coronal T1- and T2*-weighted fast spin-echo, gradient-echo (GRE), and inversion-recovery sequences with a matrix size of up to 512 pixels. A dynamic T1-weighted GRE sequence was acquired with intravenous administration of contrast medium. Erosions were assessed using all 3 imaging techniques on a 4-point scale. Soft-tissue involvement was evaluated according to the presence of synovitis, tenosynovitis, and bursitis on ultrasound and MRI. The results in the study group were compared with those obtained in a control group of 10 patients with shoulder pain. RESULTS: In the study group, erosions of the humeroscapular joint were detected by conventional radiography in 26 patients, by ultrasound in 30 patients, and by MRI in 39 patients; the differences were statistically significant for the comparisons of conventional radiography with MRI and for ultrasound versus MRI (P < 0.0001). Conventional radiography detected 12 erosions of the scapula and MRI detected 15. Synovitis was demonstrated in 12 patients by ultrasound and in 27 patients by MRI (P = 0.0003). Tenosynovitis was observed in 15 patients by ultrasound and in 28 patients by MRI (P = 0.0064). Bursitis was detected in 13 patients by ultrasound and in 18 patients by MRI. The findings on dynamic contrast-enhanced MRI correlated significantly with the detection of synovitis by ultrasound and erosions by static MRI (P < 0.05). CONCLUSION: Ultrasound and MRI supplement conventional radiography in assessing the shoulder joint. Although conventional radiography can be used as the sole method of following up known joint destruction in RA, ultrasound and, preferably, MRI are recommended as additional techniques in the initial diagnostic evaluation when radiography yields negative results.

Adult↗

PubMed2003

Failed meniscus repair.

This report describes problems arising after an arthroscopic meniscal refixation using the biodegradable Clearfix screw system (Innovasive Devices, Marlborough, MA). A serious problem arose in the form of migration of a meniscal screw that had been inserted in accordance with the manufacturer's instructions. Dislocation of the screw led to pain on the medial aspect of the knee joint and irritation of the infrapatellar branch of the saphenous nerve. The case reported here is a first analysis of the potential complications associated with the use of this meniscal refixation system.

Absorbable Implants↗

PubMed2002

The biological and biomechanical effect of different graft tensioning in anterior cruciate ligament reconstruction: an experimental study.

The objective of the present animal experimental study was to determine the effect of initial graft tension (1 N, 7.5 N, 17.5 N) on the biomechanical and histological behavior of the anterior cruciate ligament (ACL) graft using a rabbit model. After 2, 8, and 32 weeks, the femur-ACL-tibia complex was removed, and biomechanical and histomorphometrical studies were performed. The morphometric parameters cellularity, cell nucleus volume, and vascularity increased up to the 8th postoperative week and showed significant differences between the study groups. The values obtained demonstrated that higher pretension had increased the pull-out force and stiffness. However, at 32 weeks postoperatively, the pull-out force was significantly below the values of the normal ACL (40.5% at 1 N, 45.1% at 7.5 N, and 50.8% at 17.5 N). In the present study, it was demonstrated that an intraoperatively selected initial tension of 17.5 N induces histomorphometric changes in the graft, which result in a higher biomechanical loading capacity. The results showed that higher initial graft tension resulted in improved histological and biomechanical parameters. Pathological changes in the graft such as an increased central necrosis rate or cartilage damage due to 'overconstraining' of the knee were not observed at the selected initial tensions.

Animals↗

PubMed2001

Revision acetabular arthroplasty using a pedestal cup in patients with previous congenital dislocation of the hip - four case reports and review of treatment.

Despite extensive acetabular bone defects as found in revisions of total hip arthroplasty for high hip dislocation, the ilium usually still provides secure fixation of the pedestal of the acetabular component. Four cases are presented in which reconstruction was performed using a newly developed, conical, titanium, ribbed shaft socket designed for cementless press-fit into the dorsocranial ilium to obtain primary stability. In each case the pedestal cup allowed restoration of the original centre of rotation. There were no complications. A Harris hip score of 85 points was achieved after an average of 28.5 months. All components were radiologically stable. While the findings demonstrate the short-term efficacy of the procedure, longer follow-ups and a larger number of patients are needed before the durability of this reconstructive technique can be assessed.

Adult↗