PubMed Health⌕ Search

Biomedical subjects

L H Riley

Publications and source records attributed to L H Riley.

At least 19 recordsLinked to original sources
PubMed1989

Considerations in the comparison of cemented and cementless total hip prostheses.

Based on conservative models of the revision rates for cemented and uncemented hip arthroplasties, the required number of patients for a study to show significant uncemented superiority was determined using standard statistical techniques. A review of the literature was done to ascertain the revision rates for cemented total hip arthroplasties. Patients with osteoarthritis who were older than 50 years had an average revision rate of 1% per year, while those younger than 50 years had revision rates in excess of 2% per year. Specific conditions of the hip were also associated with increased failure rates, most notably the implantation of a revision arthroplasty for a previously failed total hip arthroplasty. Assuming that the uncemented hip had a long-term revision rate of 0.5% per year and an early lack of biologic fixation in 1% of patients, it was found that a 5-year study would have to include at least 2,800 patients (1,400 in each group) if the study population had a cemented failure rate of 1% per year and a total of 230 patients in those having a cemented failure rate of 2% per year. The patients needed for a 10-year evaluation would be 700 and less than 100, respectively. Altering the long- or short-term revision rate for uncemented total hip arthroplasty had relatively little effect on the study size. This analysis indicates that a comparison study would be best done in patients who have high failure rates with cemented total hip arthroplasties. Multicenter trials involving younger patients or those undergoing revision surgery are ideally suited for such an investigation.

Follow-Up Studies↗
PubMed1989

A method of tack fixation of tibial bone grafts in total knee arthroplasty.

A simple and secure method of bone graft fixation using a tack is described for reconstruction of peripheral tibial defects during cemented and uncemented total knee arthroplasties. In use since 1985, this method facilitates minimization of tibial bone resection and provides an intrinsically stable platform for tibial component seating. This method is technically simple to perform with routine primary total knee arthroplasty equipment and is especially helpful for intermediate-sized grafts, which are too small to be handled conveniently with screws.

Aged↗
PubMed1989

Advanced three-dimensional evaluation of acetabular trauma: volumetric image processing.

Volumetric image processing is a new approach to generating simulated three-dimensional images from transaxial CT data. The major advantages compared to conventional surface-rendering 3D technique include: preservation of every pixel of CT data for increased accuracy of rendered image; tissue layer translucency allowing appreciation of multiple tissue layers on each image; simulation of real-time rotation in varying axes for optimal appreciation of abnormalities; and a high-speed, high-capacity computer setup which generates high-quality images rapidly, giving the system sufficient flexibility for these complicated functions while remaining user friendly and fast.

Accidents, Traffic↗
PubMed1987

Three-dimensional imaging of acetabular trauma.

Computed tomography (CT) scanning is widely used in evaluation of acetabular fractures. Three-dimensional (3D) images of the pelvis can be created from CT scan data. This article reports two studies, each employing one type of 3D imaging in acetabular trauma cases. The first was a study of 21 patients utilizing surface-rendered 3D images, the second, a study of 19 patients using volume-rendered 3D images. Both types of 3D images were clinically helpful and can be used in lieu of conventional plain films as a supplement to CT examination. Advantages of volume-rendered images are described.

Acetabulum↗
PubMed1987

Volumetric rendering techniques: applications for three-dimensional imaging of the hip.

Volumetric rendering is a new approach to three-dimensional (3D) imaging that overcomes many of the drawbacks of currently available surface-rendering systems. Its application on the Pixar Imaging System in two cases of acetabular fracture was assessed to illustrate the features of the technique. The fast-computing architecture and large memory of this system allow rapid generation of a series of high-quality 3D images in each plane of rotation (x or spinal axis, z or somersaulting axis) that can be viewed as independent static images or as an animated real-time video loop. Editing to remove the normal contralateral hemipelvis enhances appreciation of acetabular abnormalities. Every pixel of computed tomographic data is preserved, allowing representation of both soft tissue and bone as translucent overlap. The presentation of data also allows detection of subtle abnormalities and features and minimizes the artifact generation common in surface-rendered images.

Computers↗
PubMed1987

The anterior retropharyngeal approach to the upper part of the cervical spine.

Since 1959, we have used a superior extension of the anterior approach to the cervical spine of Robinson and Smith in a consecutive series of seventeen patients. This approach provided anterior access to the neural elements from the clivus to the body of the third cervical vertebra, without the need for posterior dissection of the carotid sheath or entrance into the hypopharynx or oral cavity. It also provided adequate exposure for the insertion of iliac or fibular strut grafts, which was necessary in thirteen patients. The approach gave excellent exposure for anterior intralesional excision of a tumor in ten patients, marginal excision of an osteochondroma, two corpectomies of the second cervical vertebra combined with removal of the odontoid process, corpectomy of the second cervical vertebra for the treatment of fixed atlanto-axial subluxation, removal of a bullet anterior to the clivus, reduction of a dislocation of the second on the third cervical vertebra secondary to an unstable fracture of the pedicles of the second cervical vertebra, and anterior débridement for treatment of pyogenic vertebral osteomyelitis. In contrast to the reported results of transmucosal approaches to the atlas and axis, there were no infections or iatrogenic neurological deficits of the spine in the present series. Twelve patients who were followed for two years or more had a solid anterior fusion and no subsequent loss of cervical stability. Pain in the neck was relieved in all of the patients who had had a pathological or traumatic fracture.

Adolescent↗
PubMed1987

Pyogenic osteomyelitis of the occiput, the atlas, and the axis. A report of five cases.

Pyogenic osteomyelitis rarely affects the first and second cervical vertebrae, and when it does it can progress to abscess formation, compressing the spinal cord. If the process is unrecognized, it can be fatal. The cases of five patients are reported. Two patients were treated by anterior débridement and posterior cervical-occipital arthrodesis; one, by transoral drainage; one, by posterior cervical-occipital arthrodesis; and the fifth, by posterior atlanto-axial arthrodesis. The causative organism was Staphylococcus aureus in four patients and Pasteurella multocida in one. In all patients, intravenous antibiotics were used, followed by prolonged administration of oral antibiotics. All five patients recovered.

Aged↗
PubMed1987

A histologic comparison of aseptic loosening of cemented, press-fit, and biologic ingrowth prostheses.

The histology of interface membranes from aseptic loosened prostheses of various types including cemented, press-fit, and biologic ingrowth varieties was compared. Pseudosynovial implant-facing surfaces were present in specimens from all types. The remaining portions of these membranes showed distinct characteristics as well. Cemented implant membranes contained many macrophages and giant cells and evidenced frequent granuloma formation. Press-fit membranes consisted of poorly vascularized, dense fibrous tissue within the loosened press-fit membrane. Macrophages and giant cells were rare, except in one specimen containing ceramic debris particles. Biologic ingrowth membranes were the most vascular and contained loosely organized connective tissue and islands of woven bone. Macrophages were common. One out of six specimens from patients with rheumatoid arthritis contained massive numbers of lymphocytes and plasma cells but not mast cells. The greatest numbers of mast cells were present in membranes from patients with osteoarthritis and in all cases were associated with the presence of stainless steel and/or chrome cobalt particles.

Arthritis, Rheumatoid↗
PubMed1986

High tibial valgus osteotomy. A clinical review.

Thirty-one consecutive high tibial valgus osteotomies for varus gonarthrosis performed by one surgeon using one technique were evaluated to determine correction of deformity, functional result, subjective impression, and subsequent surgery for the same problem. Twenty-five patients had satisfactory follow-up evaluations. Preoperative tibiofemoral angulation averaged 7 degrees varus. Postoperative tibiofemoral angulation averaged 5 degrees valgus. Ninety-two percent had excellent or good results, according to Coventry's criteria and the H.S.S. knee score. Eighty-eight percent claimed postoperative improvement, 8% were unchanged, and one patient was worse. Eighty-eight percent had had no further surgery. Excellent/good results deteriorated from 92% at two years to 88% at five years, to 91% at seven years, and to 80% at nine years. This is a smaller rate of deterioration than noted in other series. Analgesic and antiinflammatory drug use was significantly reduced after operation. No significant differences were noted in patients older than or younger than 60 years of age at the time of surgical correction. Factors contributing to success included careful patient selection; correction of the limb to the mechanical axis; and precise surgical technique. Osteotomy proved a successful alternative to total knee replacement for treatment of varus gonarthrosis in a carefully selected group of patients.

Adult↗
PubMed1985

Focal lytic lesions associated with femoral stem loosening in total hip prosthesis.

Focal lytic lesions may occur in the proximal femur associated with loosening of the femoral component of a total hip prosthesis. During long-term follow-up of 62 patients with total hip prostheses, five such lesions developed. Histologically the lesions appear to be a histiocytic response to fragmented methylmethacrylate. Radiographically the lesions may suggest infection or neoplasm. Pathologic fracture may occur through large lesions. Experience in one case suggests that thorough removal of the tissue at the time of revision may be necessary to prevent recurrence. The recent reports of several malignant neoplasms developing in association with the femoral components of total hip replacements makes recognition of these benign focal lytic lesions even more important.

Aged↗
PubMed1979

Skeletal changes during prolonged external irradiation: alterations in marrow, growth plate and osteoclast populations.

This report describes hematologic and skeletal changes in young mice subjected to continuous external whole body irradiation (45 rads/day) for 4 days to 12 weeks. Irradiation caused a rapid depletion of hematopoietic stem cells, marrow aplasia and pancytopenia, all of which persisted during the period of irradiation but resolved afterward. In spite of suppressed cellular proliferation and disarray of cartilage cell columns in metaphyseal plates, linear bone growth appeared to continue at physiologic rates. Histologic and morphometric studies provided no evidence of impaired osteoblast function, but the presence of thickended trabeculae beneath the growth plate and of cartilagenous islands within cortical shafts of long bones indicated that bone remodeling was deficient. Direct osteoclast counts demonstrated that marrow aplasia was followed by a progressive decline that could not be reversed by parathormone injections or infusions with mature macrophages and lymphocytes but that resolved once the bone marrow recovered following cessation of irradiation. Therefore, the altered bone remodeling probably resulted from radiation injury to osteoclast precursors in the hematopoietic compartment.

Animals↗
PubMed1978

Geometric total knee replacement for treatment of the rheumatoid knee.

The results of fifty-four geometric total knee arthroplasties in forty-four patients with definite or classic rheumatoid arthritis were analyzed twenty-four to sixty-four months after the surgical procedure. There were no operative deaths, no postoperative infections, and no known pulmonary emboli. Three patients required additional operative procedures on the knee: one, a patellectomy for pain one year after arthroplasty; the second, resection of tibial bone and reinsertion of the tibial component to correct a flexion contracture; and the third, replacement of the tibial component because of loosening. The relief of pain and increase in ability to carry out the activities of daily living were dramatic in these patients, who, because of the limitations imposed by their rheumatoid arthritis, applied minimum stress on the prosthetic knees. Postoperatively, the average arc of knee flexion was 104 degrees.

Activities of Daily Living↗
PubMed1978

Continuous transphyseal traction: experimental observations.

Observations of canine tibias lengthened by continuous transphyseal distraction (without osteotomy) reveals an acute fracture through the metaphyseal zone of primary trabeculae and rapid osseous healing. Long-term follow-up demonstrates normal subsequent growth.

Animals↗
PubMed1977

Application of the free vascularized bone graft in the treatment of malignant or aggressive bone tumors.

Although recent advances in clinical microsurgery have made free tissue transfer a clinical reality, the value of free bone transfers in the reconstructive tumor surgery of long bones has not been reported to our knowledge. Two patients with malignant or aggressive bone tumors who underwent en bloc resection of their tumors and reconstruction with free vascularized bone grafts are presented. In the first case, a giant cell tumor of the distal radius was resected, and a 10 cm free vascularized fibular graft was performed as a reconstructive procedure; in the second case a chondrosarcoma of the femur was excised and replaced by a 20 cm segment of free vascularized fibula. Postoperatively, these patients were followed with arteriograms and sequential bone scans. The indications for the procedure and the operative technique are discussed. A comparison of the merits of free rib versus free fibular transfers is presented with emphasis on bony architecture, vessel characteristics, dissection required and the options available for reconstructive surgery. The advantages and disadvantages of free vascularized bone grafts with respect to conventional methods and the potential applicability of this technique are discussed.

Arteries↗
PubMed1976

Continuous trans-physeal traction: a simple method of bone lengthening.

Leg length increments utilizing continuous traction across the epiphyseal plate of growing puppies produces a cleavage fracture at the level of the primary metaphyseal trabeculae which neither anatomically nor physiologically alters the growth plate. These fractures heal readily and growth resumes following removal of the traction device. This method is relatively atraumatic to the extremity. It does not require an open operation and the controlled distraction rate has not caused neurological or vascular complications. The study was designed to determine the anatomic site of fracture; no attempt was made to achieve maximal leg length increments.

Bone Lengthening↗
PubMed1976

The evolution of total knee arthroplasty.

The current status of knee replacement surgery suggests that high density polyethylene and chrome cobalt alloy or stainless steel are acceptable materials for use in the intra-articular environment of the knee; that prosthetic components of knee units can be firmly fixed in bone with methylmethacrylate; and that a wide range of prosthetic units are available which will provide acceptable clinical results if used within the limits for which they have been designed. The indications for total knee arthroplasty have been designed. The indications for total knee arthroplasty have become reasonably simple and straightforward. Contraindications for the use of the various units available are relatively obscure and very seldom stressed. Each unit available will fail, however, if used under conditions of bone loss, deformity, and ligamentous instability for which it was not designed. The importance of the surgeon understanding and respecting the limitations of the total knee unit he chooses, and skillfully adapting it to the pathologic anatomy and pathophysiology of the patient's knee cannot be overemphasized.

Arthroplasty↗
PubMed1976

Steroid induced avascular necrosis of bones in eighteen sites: a case report.

A patient with idiopathic thrombocytopenia purpura who was treated with high dosage corticosteroids for ten years, developed 18 separate lesions of avascular necrosis in 12 different bones. Despite spontaneous revascularization of many of the lesions, subchrondral collapse caused symptomatic secondary degenerative arthritis in many joints. Pathological examination of both resected femoral heads showed no intravascular thrombosis.

Adult↗