The effect of femoral component position on the kinematics of total knee arthroplasty

In a laboratory study using seven fresh-frozen anatomic specimen knees, the effect of total knee arthroplasty on the three-dimensional kinematics of the patella, femur, and tibia were measured. Experiments were performed in the intact knee, after division of the anterior cruciate ligament (ACL), after total knee arthroplasty, and after 10 degrees internal rotation, 10 degrees external rotation, 5-mm medial shift, and 5-mm lateral shift of the femoral component on the femur. The presence of a high lateral ridge on the anterior surface of the femoral component effectively prevented patellar subluxation or dislocation, but displaced and tilted the patella medially. Internal rotation or medial displacement of the femoral component exaggerated this medial patellar displacement and shift. External rotation of the femoral component corrected it, except at flexion angles greater than 100 degrees, where the femur was shifted medially on the tibia and externally rotated 15 degrees. This combination produced a net 10-mm medial displacement of the patella relative to the tibia at 120 degrees knee flexion. Lateral placement of the femoral component compensated for the effect of the high lateral ridge and allowed more normal patellar tracking while allowing tibiofemoral motions similar to those seen after sectioning of the ACL. The kinematics of the patellofemoral and tibiofemoral joints were not reproduced with a total knee prosthesis that sacrifices the ACL. When using a prosthesis with a high lateral ridge, lateral placement of a femoral component prevented patellar dislocation and allowed patellar tracking patterns similar to those seen in the intact knee without further altering tibiofemoral motions.     

High-resolution three-dimensional magnetic resonance imaging for the investigation of knee joint damage during the time course of antigen-induced arthritis in rabbits

OBJECTIVE: To investigate the efficacy of high-resolution 3-dimensional magnetic resonance imaging (3-D MRI) with gadolinium contrast agent enhancement in monitoring soft tissue and hard tissue changes during the course of antigen-induced arthritis in rabbits, comparing the images with the final histologic outcome. METHODS: Arthritis was induced by intraarticular injection of methylated bovine serum albumin into rabbits that had been presensitized to the same antigen. MRI was carried out before and on predetermined days after the onset of inflammatory arthritis, up to day 60. At each time point, 3-D gradient-echo images were acquired. At the end of the study, the knee joints were processed for histologic study. RESULTS: Time-related inflammatory changes, such as soft tissue swelling, were seen initially, followed by a reduction in the acute swelling and a progression to hard tissue damage at later time points. The final 3-D data sets were then used to compare MR images with the histologic sections. The knee joints were sectioned in the sagittal, coronal, or transverse direction. Comparison of final images and histologic features at day 60 enabled a more complete interpretation of the MR images, allowing direct correlation of joint damage observed using the MRI technique with that seen in the final histologic analysis. CONCLUSION: Qualitative information derived from MR images correlated extremely well with histologic findings. These results indicate the great potential of MRI for noninvasive investigation of drug effects in this model of arthritis.     

Effect of skin movement on the analysis of skeletal knee joint motion during running

Olfactory thresholds for acetone and vanillin and the unpleasantness rating of concentrated acetone were measured in 20 migraine sufferers and 21 controls. The olfactory threshold for vanillin was lower in migraine sufferers than in controls. In addition, patients who reported that odours frequently seemed stronger during attacks of migraine were able to detect acetone at a lower concentration than most other patients. No differences were found between migraine sufferers and controls for ratings of the unpleasantness of concentrated acetone. These findings suggest that hyperacuity to odours persists between episodes of migraine. Sensitivity to odours could contribute to the migraine predisposition.     

Arthroscopy of the knee joint

A manual version and mechanized versions for several types of analyzers are described for the kinetic determination of glucose with glucose dehydrogenase. Results of glucose determinations with and without deproteinization of samples are discussed. The correlation of results with the hexokinase method is shown.     

Anatomic bases of a vascularized allogenic knee joint transplantation: arterial blood supply of the human knee joint

The reliable identification of tumor cells in populations of atypical cells occurring in body cavity effusions is a well-known diagnostic problem. In order to improve tumor cell detection and to predict disease progression, we developed a cell scoring strategy based on a combination of DNA cytophotometry and immunocytochemistry. For this purpose, morphologically atypical cells obtained from 33 effusion samples were submitted to DNA content analysis and tested for Ber-EP4 immunoreactivity. It turned out that elevated DNA content alone has a low specificity (true negative ratio) and sensitivity (true positive ratio) in predicting disease outcome, whereas Ber-EP4 immunoreactivity alone has a high specificity (100%) but a low sensitivity (56%). In contrast, the use of a scoring system combining the two techniques and relating scores to the previous disease state and the cytomorphology of the atypical cells results in highly specific and sensitive prediction of the disease outcome. We therefore suggest that this approach is a valuable tool for reliably identifying tumor cells in effusions containing populations of cytologically suspect cells.     

Total endoprosthesis of the knee joint

The results of conduction of 7 operations endoprosthetics of the knee joint using AGC-system of the "Biomet" concern are adduced. Details of operative procedure are enlightened, clinical cases and immediate results of operation are adduced.     

Primary chronic polyarthritis of the knee joint

Rheumatoid arthritis is a chronic, multisystemic disease. The characteristic feature is persistent inflammatory synovitis. The knee joint is commonly involved with synovial hypertrophy, chronic effusion, and frequently ligamentous laxity. Pain and swelling behind the knee may be caused by extension of inflamed synovium into the popliteal space (Baker's cyst). Plain radiographs of the knee joint remain the basic radiological procedure, although early in the disease they might not provide significant changes. Sonography sufficiently reveals synovial fluid and Baker cysts, but cannot be recommended for evaluation of synovial proliferations or pannus formation. Computer tomography has only limited indications and may be used for the evaluation of subtle erosive lesions or the quantitation of osteoporotic changes. Magnetic resonance imaging has shown excellent visualization of cartilage, fluid, synovium and soft tissues and is the method of choice for the demonstration of early affection and the evaluation of pannus activity and therapy control. With administration of contrast agents (gadolinium), dynamic studies may demonstrate inflammatory activity. Modern MR sequences, such as T1 SE "fat sat" or magnetization transfer, further improve the discrimination of cartilage, pannus and synovial fluid.     

Aspiration of the knee joint before revision arthroplasty

Sixty-four operative procedures were performed on 55 patients with knee arthroplasties for pain, loosening, instability, or suspicion of infection. Forty-three knees had a preoperative aspiration. In 19 knees, the aspiration showed growth on solid media, and in 18 of these knees the diagnosis of infection was confirmed by the intraoperative cultures. In 1 knee with an infected total knee replacement, the patient was receiving an intravenous antibiotic at the time of arthroscopic irrigation and debridement and the cultures showed no growth. In 23 of 24 knees with a negative preoperative aspiration, the intraoperative cultures showed no growth on solid media. In 1 knee with a preoperative aspiration that had negative results, a single intraoperative culture grew Staphylococcus epidermidis. However, the presenting symptoms, examination, preoperative radiographs, and intraoperative evaluation were consistent with aseptic loosening of a cemented total knee arthroplasty. Thus, the preoperative aspiration of the prosthetic knee joint had a sensitivity of 100%, specificity of 100%, and accuracy of 100%. The Westergren erythrocyte sedimentation rate, peripheral leukocyte count, and presenting symptoms correlated poorly with infection. Radiographs were also not helpful in the diagnosis of infection, with loosening of components, periostitis, focal osteolysis, and radiolucent lines frequently seen in infected and noninfected knees. Preoperative aspiration of the knee is the most helpful study for the diagnosis or exclusion of infection in a prosthetic knee joint.     

Hemangioma of the synovial membrane of the knee joint

The data on 15 patients with hemangioma of the synovial sheath of the knee joint are reported. It is the author's opinion that surgical removal of the tumor is the most radical method of treatment for hemangiomas. Among 15 patients such procedure was accomplished in 6, in the remainder biopsy or partial removal of the tumor followed by radiotherapy were performed. Late results were followed up in 9 patients.     

Hyperextension of the elbow joint: pathoanatomy and kinematics of ligament injuries

This study consisted of two experiments, one in rats and one in human volunteers, that used the identical progressive ratio (PR) operant procedure. In both experiments, responding was reinforced under a progressively increasing work requirement, and different groups of subjects received reinforcers that varied in sweetness. In experiment 1, rats were subjected to chronic mild stress, a well-validated animal model of depression. Performance under the PR schedule increased in subjects reinforced with conventional precision pellets (which contain 10% sucrose) or very sweet pellets, but not in subjects reinforced with sugar-free pellets. In experiment 2, volunteers were subjected to a depressive musical mood induction. Performance under the PR schedule increased in subjects reinforced with chocolate buttons, but not in subjects reinforced with with buttons made from the relatively unpalatable chocolate substitute carob. In experiment 2, depressive mood induction also increased chocolate craving, as measured by a novel questionnaire, and there were significant correlations between chocolate craving and chocolate-reinforced PR performance. These results suggest that performance under the PR schedule provides a measure of craving rather than reward, and that craving for sweet rewards is increased by depressive mood induction in both animal and human models. Implications for the interpretation of pharmacological studies using the PR procedure are also discussed.     

Loading of a unilateral temporomandibular joint prosthesis: a three-dimensional mathematical study

The load on the prosthetic side and the influence of the design on the remaining natural contralateral TMJ must be known before a unilateral temporomandibular joint (TMJ) prosthesis can be developed. The aim of the present study was to determine the maximum loading of the TMJ prosthetic side and the natural contralateral TMJ and to investigate the influence of the location of the center of rotation of the prosthesis on the maximum loading. For this purpose, a mathematical model of the mandible with a unilateral TMJ prosthesis with a fixed center of rotation (CR) was developed. The location of the CR of the TMJ prosthesis was varied from the middle of the natural mandibular condyle to 15 mm inferior to this location. Although the maximum joint reaction forces changed as a result of a unilateral TMJ prosthesis, the trend of the loading curves was similar to that of an intact mandible. A unilateral TMJ prosthesis resulted in a 50% higher loading of the prosthetic side, while the load on the natural contralateral TMJ remained within normal limits. The maximum load on the prosthetic side occurred during molar bites and could reach 100 N in the cranial direction, 30 N in the ventral direction, and 25 N in the medio-lateral direction. The location of the CR did not have a significant influence on the loading of the TMJ prosthesis and the natural contralateral TMJ.     

Effect of a neoprene sleeve on knee joint position sense during sitting open kinetic chain and supine closed kinetic chain tests

The primary objective of the present study was to compare the effect of a neoprene sleeve on knee joint position sense during a sitting open kinetic chain test and a supine closed kinetic chain test. Young (24 +/- 2 years old), healthy subjects (18 men and 18 women) performed knee joint angle replication tests during open kinetic chain knee extension (sitting) and closed kinetic chain leg press (supine with an axial load of 15% body weight) before and after application of a neoprene sleeve over the dominant knee. The improvement in ability to replicate joint angles after application of the sleeve (sleeve effect) was significantly less during the supine closed kinetic chain test (0.3 degree +/- 1.4 degrees) than during the sitting open kinetic chain test (1.2 degrees +/- 1.1 degrees). The sleeve effect was inversely related to subjects' performance without the sleeve during both the sitting open kinetic chain and supine closed kinetic chain tests, suggesting that some people may derive greater benefit from the sleeve than others. Although the sleeve effects were small, particularly during the supine closed kinetic chain test, 72% of subjects felt that the sleeve improved their overall test performance. Future research is needed to establish the functional relevance of the small sleeve effects observed and to identify the characteristics of people who might derive greatest benefit from sleeve use.     

Analgesic effect of intra-articular bupivacaine or diamorphine after arthroscopic surgery of the knee joint in day-case patients

A prospective, randomized, double-blind, controlled study was conducted to assess the efficacy of intra-articular bupivacaine and diamorphine. Ninety-six day-case patients were allocated randomly to receive intra-articular injections of either 20 mL 0.9% saline (control, n = 35), 20 mL 0.5% plain bupivacaine (n = 31), or 20 mL 0.9% saline with 5 mg diamorphine (n = 30) prior to tourniquet release. Visual analogue scales (VAS) were completed at 1 h, 3 h (discharge) and 24 h, and supplementary analgesia noted. Intra-articular analgesics conferred a noticeable improvement in patient comfort. First, the quantity of supplementary analgesia required prior to discharge was significantly reduced (P = 0.016); second, patients reported a less disturbed night's sleep (P = 0.034).