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Biomedical subjects

J L Knight

Publications and source records attributed to J L Knight.

At least 37 records · Page 2Linked to original sources
PubMed1997

Early failure of the porous coated anatomic cemented unicompartmental knee arthroplasty. Aids to diagnosis and revision.

Unicompartmental knee arthroplasty (UKA) is performed less frequently than total (tricompartmental) knee arthroplasty (TKA). This study examined the range of presenting symptoms and usefulness of diagnostic tests to determine the failure mode; the outcome of surgical revision of failed UKA is also reported. From a consecutive prospective series of 43 Porous Coated Anatomic (Howmedica, Rutherford, NJ) UKAs performed between 1985 and 1992 and followed for an average of 64 months, 12 cases have come to revision surgery (28%). The average time to failure was 37 months. Symptoms preceded revision surgery by an average of 10 months. The most common presenting symptom was pain (100%), followed by swelling (92%), reduced range of motion (42%), instability (42%), and clicking (17%). Failure was caused by polyethylene wear in 50%, loosening of the femoral component in 42%, and progression of patellofemoral arthritis in one patient. The combination of single leg standing anteroposterior radiographs and supine lateral radiographs detected most causes of UKA failure. A bone scan was confirmatory in every case of suspected loosening of the femoral component. Arthroscopy diagnosed polyethylene wear in two cases and progression of joint arthritis in one case and was not helpful in one case. Revision surgery was done with primary TKA components, and follow-up periods averaged 27 months. Bone stock deficiency was found in 58%, but required bone-grafting in only one case. Revision surgery successfully restored pain-free function and range of motion in all cases. Two-year postrevision Hospital for Special Surgery scores are equal to those for primary TKA. Survivorship analysis showed a 33% failure rate at 57 months after Porous Coated Anatomic UKA when revision was the endpoint and a 41% failure rate when unsatisfactory clinical status was the endpoint. Regular follow-up evaluation is suggested for the Porous Coated Anatomic UKA.

Aged↗
PubMed1997

Clinical results of the modular porous-coated anatomic (PCA) total knee arthroplasty with cement: a 5-year prospective study.

Our study examines the clinical, radiographic, and patient satisfaction outcome of the cemented Modular Porous-Coated Anatomic (PCA) total knee arthroplasty with a minimum 5-year follow up. All data were gathered prospectively and consecutively. Patient satisfaction was assessed with a self-administered survey. Statistical analysis examined the effect of 17 patient factors, 19 surgical factors, and postoperative continuous passive motion use on range of motion (ROM) and HSS scores at 2 years. Seventy-eight Modular PCA arthroplasties performed by 9 orthopedic surgeons on 71 patients between January 1988 and November 1989 are reported in this study. Preoperative HSS scores averaged 51.2 and improved to an average of 89 at 1 and 2 years, and 86 at 5 years after surgery (90% good or excellent). ROM changed after surgery through improvement in preoperative knee flexion contracture, but not in increased knee flexion. One patient underwent reoperation for patellar instability, and one patient's arthroplasty was revised at 53 months for late instability. The total reoperation rate for any reason was 7.7%. Zonal analysis for progressive radiolucency at the bone-cement interface showed increasing frequency of narrow (< 1 mm) radiolucencies concentrated on the anterior and medial aspect of the tibial tray. Ninety-eight percent of patients responded to an outcome questionnaire, and 96% rated themselves improved. The Kaplan-Meier probability of an implant surviving without loosening at 5 years was 100%. The Modular PCA TKA has a low incidence of patellofemoral problems, is clinically successful, and results are stable at a minimum 5-year follow-up examination.

Activities of Daily Living↗
PubMed1995

Tibial polyethylene failure after primary porous-coated anatomic total knee arthroplasty. Aids to diagnosis and revision.

Recognizing and providing effective treatment for polyethylene failure after total knee arthroplasty (TKA) are challenging problems. The range of presenting symptoms and the usefulness of diagnostic tests are examined, and the outcome of surgical treatment of patients with tibial polyethylene failure is reported. From a consecutive series of 209 Primary Porous-Coated Anatomic (Howmedica, Rutherford, NJ) TKAs performed between 1984 and 1987, 18 cases (9%) required revision surgery. No patient experienced polyethylene failure prior to 48 months, and the average time to revision was 81 months after index TKA. The follow-up period after revision surgery averaged 24 months. Symptoms began after a period of good function, and preceded revision by an average of 8 months. The most common presenting symptom was swelling (89%), followed by stiffness (72%), pain (67%), and clicking (38%) or instability (22%). Single leg standing anteroposterior radiographs were most effective, demonstrating polyethylene failure by a change to increasing varus and narrowing of the polyethylene space in 16 of 18 cases. Arthroscopic evaluation confirmed the diagnosis in two cases. Five cases required tibial tubercle osteotomy for exposure, and 15 required complete synovectomy. Exchange of the damaged heat-pressed polyethylene insert with a machined insert was performed in 14 cases, exchange plus tibial tray revision in 3 cases, and complete knee revision in 1 case. Revision surgery successfully restored pain-free function and improved range of motion in 16 of 18 cases. Survivorship analysis showed an 11% failure rate at 8 years after index procedure. Regular follow-up evaluation for the Primary Porous-Coated Anatomic TKA is suggested.

Aged↗
PubMed1995

Aortic ring abscess and mitral valve aneurysm in aortic valvular endocarditis: enhanced diagnosis with transesophageal echocardiography.

Aortic ring abscess and mitral valve aneurysms complicating infective endocarditis have previously been described as surgical or autopsy findings. More recently, transesophageal echocardiography has been shown to be more sensitive than standard transthoracic echocardiography or other imaging modalities in detecting each of these complications. Since aortic ring abscess and mitral valve aneurysms virtually mandate surgical intervention, their early detection may be crucial. This report describes a 35-year-old male with congenitally abnormal aortic valve which became infected and in whom both an aortic ring abscess and mitral valve aneurysm occurred. These findings are discussed and the pertinent literature is reviewed.

Abscess↗
PubMed1993

Bone-grafting for acetabular deficiency during primary and revision total hip arthroplasty. A radiographic and clinical analysis.

The use of bone-graft to augment the deficient acetabulum in primary and revision total hip arthroplasty (THA) is controversial. To identify factors affecting cup loosening in patients who received a bone-graft during THA, two orthopaedic surgeons retrospectively examined sequential radiographs. The surgeons also obtained independent computer measurements of hip center and cup abduction migration from preoperative, initial, and latest postoperative radiographs. Variables studied included host factors, graft factors, and technique factors. All conclusions were based on Kaplan-Meier log-rank analysis to account for differing lengths of follow-up periods among the cases. The authors report a series of 74 consecutive cases with a minimum 24-month follow-up period (mean, 40 months). All grafts appeared to unite. The clinicians found 80% stable cups, 8% possibly loose cups, and 12% (n = 9) definitely loose cups. In retrospect, technical errors were seen in six loose cups. Five revisions for loosening (6.7% of cases) were performed. Computer measurement found cup loosening in a higher percentage of cases than detected by the clinicians and did so an average of 18 months sooner. Acetabular cup loosening was associated with the American Academy of Orthopaedic Surgeons type III defects, use of allograft versus autograft, and initial cup abduction of 50 degrees or more. Kaplan-Meier survivorship analysis found 31% of cups radiographically loose and 15% revised at 5 years or more since surgery. Acetabular bone-grafting is technically demanding and should be employed when alternative reconstructions will not give a durable result.

Acetabulum↗
PubMed1992

Preoperative planning for total hip arthroplasty. Quantitating its utility and precision.

This study evaluated the usefulness and accuracy of preoperative planning for cemented and cementless total hip arthroplasty (THA). The authors conducted a prospective study of 110 consecutive primary cases in which surgeons recorded the preoperative plan and what occurred in each case. Measured variables included estimated magnification, acetabular cup and femoral stem size, planned lengthening, and anticipated problems. Preoperative estimates of magnification frequently differed from actual magnification, and in 17% of cases it affected choice of implant size. Preoperative bone morphology did not correlate with type of femoral stem fixation. Implant sizing was predicted from the preoperative plan for 62% of acetabular cups, 78% of cemented stems, and 42% of the cementless stems. Leg-length equalization was a goal in only 70% of cases. Anticipated problems focused on anatomic variations, but intraoperative problems involved technique and equipment. The authors conclude that surgeons need better methods to estimate magnification and bone morphology from preoperative radiographs. Preoperative planning may not reduce intraoperative complications, which can arise from unanticipated technique and equipment mishaps.

Aged↗
PubMed1992

Bronchogenic cyst masquerading as a chronic post-traumatic pseudoaneurysm of the aortic isthmus.

The serious nature of false aneurysms that develop in the aortic isthmus after blunt chest trauma is well known. The authors describe the case of a 33-year-old woman who presented with symptoms of chronic post-traumatic pseudoaneurysm of the aorta 3 months after blunt chest trauma. Radiologic investigations could not substantiate an aortic disruption. A bronchogenic cyst masquerading as a false aneurysm of the aorta was identified at thoracotomy. Bronchogenic cysts are one of the most common causes of primary mid-mediastinal masses and should be considered as potential causes of mid-mediastinal enlargement. However, this consideration should not delay urgent surgery if vascular damage cannot be ruled out.

Adult↗
PubMed1992

Blunt traumatic avulsion of an intercostal artery: an unusual case of thoracic aortic injury.

The aortic isthmus is the most commonly injured part of the thoracic aorta in patients who survive blunt deceleration injury to that vessel long enough to reach a hospital. Occasionally, avulsion of the brachiocephalic arteries from the aortic arch is seen. The authors describe an unusual form of intrathoracic vascular injury in which mediastinal hemorrhage occurred secondary to avulsion of an intercostal artery from the descending thoracic aorta as a result of a vertical deceleration injury.

Accidental Falls↗
PubMed1992

Cardiac tamponade secondary to haemophilus pericarditis: a case report.

Pyogenic pericarditis is encountered uncommonly in clinical practice. The majority of cases of clinically apparent pericarditis are viral in origin. When bacterial infection of the pericardial space does occur the causative organism is usually Staphylococcus or Streptococcus species. Isolation of an haemophilus organism from the pericardial space in this condition is distinctly unusual. There are only 10 previously reported cases in the literature of pericarditis secondary to Haemophilus influenzae. This report describes the case of a 36-year-old woman who presented with haemophilus empyema and purulent pericarditis progressing to cardiac tamponade. There are isolated reports of successful treatment of pyogenic pericarditis with closed drainage and antibiotics. In the absence of clear evidence demonstrating the efficacy of this approach the authors favour open exploration of the pericardial space.

Adult↗
PubMed1991

Risk factors for death in patients admitted to hospital with asthma: a follow-up study.

Hospital records of patients with asthma admitted to teaching hospitals in Perth, Western Australia between 1976 and 1980 were examined retrospectively to identify characteristics of the illness which were associated with subsequent death. From 5722 admissions there were 195 deaths to December 1982, 186 of whom had records available (cases); 452 of the surviving subjects were used for comparison (controls). There was no difference in age of onset of asthma or cigarette smoking habits between the two groups, but ischaemic heart disease as an associated condition was significantly more frequent in cases. On admission to hospital an arterial PCO2 less than 45 mmHg was more frequent in those who died, but there were no differences in arterial PO2, lowest pH, highest or lowest FEV1 and FVC. Cases more frequently used home nebulisers and were more frequently prescribed corticosteroids, antibiotics and sedatives or tranquilizers prior to admission, corticosteroids and sedatives or tranquilisers during admission and sedatives or tranquilisers on discharge. These results suggest that cases had more severe asthma in that they were more often treated with home nebulisers, corticosteroids and antibiotics, but with the exception of PaCO2 the commonly used measurements of severity of asthma did not identify those at risk of death. The prescription of sedatives or tranquillisers appears to be associated with an increased risk of death in subjects with asthma.

Adolescent↗
PubMed1991

A precision guide-pin technique for wedge and rotatory osteotomy of the femur and tibia.

Intraoperative guide-pin placement for the performance of wedge-type and rotatory osteotomy of the femur and tibia provides the desired angle of correction from single-leg, weight-bearing roentgenograms. A template is used as a guide for pin placement. The accuracy of this technique was evaluated by comparing the preoperative goal with the correction achieved immediately after surgery and after bone healing one year postoperatively. Forty-seven osteotomies, 37 in the tibia and ten in the femur, were reviewed. Eighty-five percent of the cases were within +/- 3 degrees of the operative goal immediately after surgery, and 81% one year postoperatively. Four osteotomies (9%) were considered failures, two because of technique and two because of errors in postoperative patient activity level. With appropriate preoperative planning, the technique makes accurate osteotomy possible in a standard operating room equipped with a C-arm fluoroscope.

Bone Nails↗
PubMed1987

Left thoracotomy and femoro-femoral bypass for reoperative revascularization of the posterior coronary circulation.

Left thoracotomy and femoro-femoral cardiopulmonary bypass has been used for reoperation in five patients requiring coronary bypass graft into the inferolateral surface of the heart. Five patients had refractory angina pectoris and angiographic occlusion of lateral wall native vessels or previous occluded vein grafts and all had positive exercise test. Four of the five had patent internal mammary to the LAD. Following supine positioning and removal of the saphenous vein and isolation of the femoral artery and femoral vein, a left fifth interspace thoracotomy was made, the patient heparinized and cannulated for cardiopulmonary bypass, the pericardium opened, the heart dissected free, and either the internal mammary artery dissected off the left chest wall or saphenous vein grafts used to bypass the appropriate lesions. The proximal inflow was the descending thoracic aorta making tunnels for the vein grafts through the posterior pericardium. All of the patients did well in the postoperative period. This technique is recommended for reoperations in patients with documented inferolateral ischemia as the primary cause of symptomatology with mitigating circumstances against an anterior approach.

Adult↗
PubMed1982

Impact of personality and intelligence on job satisfaction of assembly line and bench work - an industrial study.

A study of the impact of machine-paced (M/P) and self-paced (S/P) work on job satisfaction of 28 female industrial assembly workers was evaluated in which M/P work was confounded with simplified work and the S/P job was confounded with enriched tasks. Results indicated the following: 1. Over three-quarters of workers were more satisfied in S/P jobs, while only less than one-quarter were more satisfied in M/P jobs. 2. The 16PF personality test effectively predicts (0.88 multiple correlation) the satisfaction ratios of M/P to S/P jobs.

Journal Article↗