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Biomedical subjects

D S Hungerford

Publications and source records attributed to D S Hungerford.

At least 163 records · Page 9Linked to original sources
PubMed1983

Pathogenesis of ischemic necrosis of the femoral head.

There are several potential pathways by which bone dies, one or more of which may be operative in any given case. However, the compartmental nature of its circulation renders bone vulnerable to ischemia from a primary elevation of BMP due to increase in any of the tissues within bone and outside the vessels. Furthermore, ischemia from other primary sources may be potentiated by a secondary increase in BMP. Findings of elevated BMP in the preradiologic and even preclinical stages of INFH support this pathogenetic hypothesis. The long-term results of core decompression reported by Professor Ficat lend further credence to these concepts.

Bone Marrow↗
PubMed1983

Rehabilitation of the knee in disorders of the patellofemoral joint: relevant biomechanics.

A knowledge of the biomechanics, anatomy, and contact pattern of the patellofemoral joint provides the basis for the selection of a highly individualized program of rehabilitation for those with patellofemoral disease. The program of choice is one that minimizes high impact loading activities and avoids the generation of greater than physiologic contact stress unit loads at articular surfaces. Recommended exercises for rehabilitating the patellofemoral joint include isometrics, terminal extension exercises, swimming, and cycling.

Athletic Injuries↗
PubMed1983

Preliminary experience with a total knee prosthesis with porous coating used without cement.

Preliminary results of implanting a total knee prosthesis with a porous coating without cement in 41 patients (46 knees) followed up for four to 25 months have shown no clinical interface failures. Radiographs show that intimate contact between bone and prosthesis is maintained for as long as two years. Instrumentation is particularly critical to cementless application but also important to all total knee arthroplasties. Prosthetic design may also be critical for cementless operations. An anatomic, minimally constrained resurfacing design has been shown to be successful in the short term and justifies continuation of clinical investigation of cementless total knee arthroplasty.

Biocompatible Materials↗
PubMed1982

Contact studies of the canine femoropatellar joint.

During development of a closed impact-trauma model, using the canine femoropatellar articulation, animal weight or other readily measured physical characters were correlated with surface area, location, and shape of femoropatellar contact at various femorotibial angulations. The information allows making reasonable predictions regarding femoropatellar contact just before delivery of calibrated closed impact-trauma to the patella. Femoropatellar contact area location, shape, and size were determined in the left pelvic limbs of 10 dogs, ranging in weight from 20.0 to 40.9 kg (mean 27.2 kg). Determinations were made at 90, 110, and 130 degrees femorotibial angulations, using a new casting technique and at 70, 90, 110, 130, and 150 degrees, using a previously described dye technique. Location and shape of the contact areas were relatively constant for a given femorotibial angulation. Bipartite areas of contact were seen on 3 specimens. Using data from the dye technique, a definitive correlation was established between antemortem animal weight and contact area size. Patellar dimensions also correlated well with contact surface area. An inverse relationship between contact area per unit body weight and total body weight was observed. Contact area size did not vary significantly with increasing compressive force resulting from changes in femorotibial angulation. These determinations allow making reasonable predictions of both location and size of articular contact area immediately preceding delivery of closed impact to the joint.

Animals↗
PubMed1982

Cartilaginous debris in the injured human knee. Correlation with arthroscopic findings.

Cytologic analysis of filtered synovial lavage was compared with the independent arthroscopic findings in 70 patients with knee pain secondary to injury. Correlation existed between the arthroscopic evaluation of the articular surfaces and the presence of cartilaginous fragments and their microscopic features. Study of the filtered lavage was carried out without knowledge of the patient's clinical status or arthroscopic findings. Patients with unblemished articular surfaces and normal menisci demonstrated essentially no fragments in the synovial lavage. Minimal fibrillation of the articular surface with normal menisci was associated with few cartilage fragments per sample. Patients with moderate to severe fibrillation of the articular surface requiring a surface altering procedure, demonstrated significantly more fragments per sample. Chondrocyte nuclei were visible in these fragments, often arranged in multicellular clusters. Isolated lesions of the meniscus were associated with cartilage fragments that did not contain chondrocyte nuclei. Microscopic analysis of synovial lavage may serve as a useful diagnostic adjunct in the evaluation of the painful knee and the study of the pathogenic role of cartilage fragments is osteoarthrosis.

Adolescent↗
PubMed1982

Bone blood flow in the femora of anesthetized and conscious dogs in a chronic preparation, using the radioactive tracer microsphere method.

The radioactive tracer microsphere method is applicable to the study of the hemodynamics of bone. As observed previously by others, areas of predominantly cancellous bone produce higher blood flow measurements than do areas of predominantly cortical bone. Bone containing fatty marrow has lower blood flow rates than does bone containing hematopoietic marrow. Blood flow to the femoral neck was the greatest measured (26.74 +/- 1.95 ml/min/100 gm), while the diaphyseal region was the area with the lowest flow (4.67 +/- 0.46 ml/min/100 gm). There was no significant difference between consecutive measurements using up to five differently labeled radioactive microspheres. This enabled observations of the effects of an experimental procedure on bone blood flow in the same animal. Additionally, there was no statistically significant differences between regional blood flows measured 40 days apart in the same animal. Bone blood flow measurements were slightly lower in anesthetized than in conscious dogs. The RTM method is the one most suitable for the estimation of bone blood flow under either acute or chronic conditions.

Anesthesia↗
PubMed1981

Late infection of total hip arthroplasty with Propionibacterium acnes: a case and review of the literature.

A 24-year-old woman had a Propionibacterium acnes infection of a total hip arthroplasty. The clinical course of an infection with this organism has been previously described in detail. The radiologic appearance of a well-circumscribed lytic defect in the femoral shaft is also an unusual if not unique presentation of late infection after total hip arthroplasty. Moreover, simple excision of this infected nidus coupled with antibiotic therapy achieved a complete clinical recovery, in sharp contrast to the more radical procedures generally required for other infections. The predominance of this organism in skin flora, as well as its presence as a contaminant in the operating room environment, implicates Propionibacterium acnes as a potential intraoperative pathogen.

Adult↗
PubMed1981

Hemodynamics of the femoral head.

UNLABELLED: We have determined the pressure-flow relationships of the canine femoral head during venous tamponade of the hip capsule. Intra-osseous pressures were determined before and after infusion of the joint with saline solution to a pressure of sixty-five centimeters of water. Femoral head blood flow was simultaneously determined by the indicator-dilution technique utilizing isotopically labeled microspheres. In puppies, pressure in the femoral head rose 248 per cent while flow dropped by 60 per cent after inflation of the capsule. In adults, no statistically significant change in either pressure or flow was seen. Thus, in the immature animal, venous tamponade results in increased pressure and decreased blood flow. In the mature animal, venous tamponade does not alter intra-osseous pressures or blood-flow rates due to the intact intramedullary venous drainage of the adult femoral head. CLINICAL RELEVANCE: In the immature individual, venous tamponade may well be involved in the development of Legg-Perthes disease. A bout of nonspecific synovitis may elevate intracapsular pressure sufficiently to obstruct venous outflow. This creates an increase in intra-osseous pressure and a decrease in femoral head blood flow. Hemodynamic changes of this magnitude have not been shown to induce Legg-Perthes disease; however, a strong suspicion exists that such alterations may be linked to the disease. In the adult, venous tamponade probably is not involved in the pathogenesis of avascular necrosis. The maintenance of intramedullary venous drainage of the epiphysis into the metaphysis may account for the fact that vascular necrosis of the femoral head rarely develops in adult patients with osteoarthritis or rheumatoid arthritis plus an inflammatory synovitis of the hip.

Animals↗
PubMed1981

Stress fracture of the pubis after total hip arthroplasty.

The occurrence of pain after total hip arthroplasty emphasizes the covert nature of acute stress fractures. In a 46-year-old woman, the lesion was not apparent on initial radiograms; cultures as well as gram stain of the joint fluid were also negative, and the initial ESR and white blood count were normal, effectively ruling out infection. An arthrogram, performed to demonstrate possible loosening, revealed stress fracture of the superior pubic ramus. Without evidence of active infection, it may therefore prove wise to postpone revision surgery for several weeks or until diagnosis of an occult fracture becomes radiologically apparent.

False Negative Reactions↗
PubMed1981

Pathogenetic considerations in ischemic necrosis of bone.

Many factors must be considered in the pathogenesis of ischemic necrosis of bone. Etiologic considerations deal with the heterogeneous disease categories that are associated with bone necrosis; these may affect bone circulation either directly or indirectly on either the arterial or the venous side. Moreover, the compartmental nature of bone makes it vulnerable to the direct effects of pathologic processes on the cellular elements of the intraosseous extravascular compartment. Once ischemia has been initiated, whether directly through influence on the circulatory tree or indirectly by the elevation of bone marrow pressure, the effects of ischemia are likely to be further potentiated because of the compartmental nature of bone blood flow. Once a critical level of ischemia is surpassed, it is possible that the condition becomes self perpetuating through increased bone marrow pressure leading to further ischemia. Interruption of this cycle by core decompression can be successful if extensive tissue death has not already occurred at the time of the intervention.

Arteries↗
PubMed1980

Ischemic bone necrosis in systemic lupus erythematosus. II. The early diagnosis of ischemic necrosis of bone.

It would appear from our experience thus far, that increased bone marrow pressure and altered venous drainage, as documented by venography, are present in all stages of ischemic necrosis of bone, including the pre-radiologic, and may be the earliest detectable changes in this disorder. This implies that any postulated pathogenetic mechanism must take into account the early appearance of significant venous derangement, although not necessarily indicating that the venous abnormalities are primary. The data indicate that the venous circulation participates in and undoubtedly contributes to the progression of the disorder. In addition the successful results of core decompression reported in Part II, lend support to such a pathogenetic sequence, and may well be due to the interruption of this vicious circle.

Adult↗
PubMed1979

Chondromalacia patellae: a system of classification.

Degeneration of the cartilage on the under surface of the patella is shown to be the most frequent cause of "internal derangement of the knee" (63%). The axial view of the patellofemoral joint in 4 angles of flexion constitutes the procedure of choice for diagnostic exploration of patellar cartilage with, perhaps, the restriction for the medial compartment where arthroscopy is probably preferrable. The information obtained from single contrast arthrography of the patellofemoral joint has contributed greatly to the understanding of the sometimes confusing problem of chondromalacia of the patella. It has given an anatomic basis to the patellar syndrome and has served as a basis for a precise typographic system of classification. From this, we have been able to correlate localization and etiology which has then allowed logical solutions to be proposed for each group, based upon biomechanical considerations in both the frontal and saggital planes of the knee.

Cartilage Diseases↗
PubMed1979

Biomechanics of the patellofemoral joint.

The patellofemoral joint contains 2 complex mechanisms for ameliorating forces transmitted across it, namely increasing extensor lever arm-r in the important range of flexion 30 degrees-70 degrees and increasing contact area with increasing flexion. In this range the patella bears sole responsibility for transmitting resultant flexion of quadriceps force to the femur. Here lies the thickest cartilage in the body and perhaps not surprisingly, the most frequent site of cartilage degeneration. The Q-angle and valgus vector explain the predominance of the pathologic lesions on the lateral side of the joint as well as the associated dislocations, subluxations, lateral pressure syndromes, and patellofemoral arthrosis. Extension exercises against resistance produce non-physiologic loading of patellar articular cartilage. Even relatively small loads which are commonly used in physical therapy departments produce pressures far in excess of normal activities, such as stair climbing or squatting. Patients who are placed on such exercise programs are often made worse and develop symptoms which they did not have before. Straight leg raising with weights, on the other hand, maximally stresses the quadriceps muscle without any patellofemoral compression since the patella is out of contact, proximal to the trochlea.

Adolescent↗