Biomedical subjects

S S Kelley

Publications and source records attributed to S S Kelley.

At least 19 recordsLinked to original sources

PubMed2004

Two mechanical devices for prophylaxis of thromboembolism after total knee arthroplasty. A prospective, randomised study.

The optimal characteristics of pneumatic compression for mechanical prophylaxis of thromboembolism after total knee arthroplasty (TKA) are not known. Our study compared two methods of calf compression, with the hypothesis that the device which provided a larger increase in peak venous velocity would produce a lower rate of thromboembolism. We performed a prospective, randomised study on 423 patients (472 knees). Duplex ultrasonography was carried out by experienced technicians who were blinded to the device used. Overall, 206 patients (232 knees) used a rapid inflation, asymmetrical compression (RIAC) device and 217 (240 knees) a sequential circumferential compression device (SCD). The rate of venous thromboembolism was 6.9% with the RIAC device compared with 15% for the SCD device (p = 0.007). The incidence of thrombi with unilateral primary TKA was 8.4% for the RIAC compared with 16.8% for the SCD device (p = 0.03). In 47 patients with a bilateral TKA, the incidence of thrombi was 4% for the RIAC compared with 22.7% for the SCD device (p = 0.05 per knee). There was a low rate of mortality and pulmonary embolism when using mechanical prophylaxis for thromboembolism after TKA. Our findings show that the use of rapid inflation, asymmetrical calf compression gave a significantly lower rate of thromboembolism.

Adult↗

PubMed2001

ATP induces Ca(2+) signaling in human chondrons cultured in three-dimensional agarose films.

OBJECTIVE: In vivo, chondrocytes are surrounded by an extracellular matrix, preventing direct cell-to-cell contact. Consequently, intercellular communication through gap junctions is unlikely. However, signaling at a distance is possible through extracellular messengers such as nitric oxide (NO) and nucleotides and nucleosides, adenosine triphosphate (ATP), uridine triphosphate (UTP), or adenosine diphosphate (ADP). We hypothesized that chondrons, chondrocytes surrounded by their native pericellular matrix, increase their intracellular calcium concentration ([Ca(2+)]ic) in response to ATP and other signaling molecules and that the source of Ca(2+) is from intracellular stores. The objectives of this study were to determine if chondrons in a 3-D gel respond to ATP by increasing [Ca(2+)]ic through a purinoceptor mechanism and to test whether chondrons in whole tissue samples would respond to ATP in a similar fashion. DESIGN: Human chondrons, cultured in a three-dimensional agarose gel or in whole cartilage loaded with Fura-2AM, a calcium sensitive dye, were stimulated with 1, 5 and 10 microM ATP. A ratio-imaging fluorescence technique was used to quantitate the [Ca(2+)]ic. RESULTS: ATP-stimulated chondrons increased their [Ca(2+)]ic from a basal level of 60 nM to over 1000 nM. Chondrons incubated in calcium-free medium also increased their [Ca(2+)]ic in response to ATP, indicating the source of Ca(2+) was not extracellular. ATP-induced calcium signaling was inhibited in chondrons pre-treated with suramin, a generic purinoceptor blocker. In addition, UTP and adenosine 5'-O-(3-thiotriphosphate) (ATPgammas) induced a calcium response, but 2-methylthio-ATP (2-MeSATP), ADP, and adenosine did not induce a significant increase in [Ca(2+)]ic, substantiating that the P2Y2 purinoceptor was dominant. Chondrons in whole cartilage increased [Ca(2+)]ic in response to ATP. CONCLUSIONS: We conclude that chondrons in 3-D culture respond to ATP by increasing [Ca(2+)]ic via P2Y2 receptor activation. Thus, ATP can pass through the agarose gel and the pericellular matrix, bind purinoceptors and increase intracellular Ca(2+) in a signaling response.

Adenosine Diphosphate↗

PubMed2001

Infected joint replacements in HIV-positive patients with haemophilia.

Joint replacement in HIV-positive patients remains uncommon, with most experience gained in patients with haemophilia. We analysed retrospectively the outcome of 102 replacement arthroplasties in 73 HIV-positive patients from eight specialist haemophilia centres. Of these, 91 were primary procedures. The mean age of the patients at surgery was 39 years, and the median follow-up was for five years. The overall rate of deep sepsis was 18.7% for primary procedures and 36.3% for revisions. This is a much higher rate of infection than that seen in normal populations. A total of 44% of infections resolved fully after medical and/or surgical treatment. The benefits of arthroplasty in haemophilic patients are well established but the rates of complications are high. As this large study has demonstrated, high rates of infection occur, but survivorship analysis strongly suggests that most patients already diagnosed with HIV infection at the time of surgery should derive many years of symptomatic relief after a successful joint replacement. Careful counselling and education of both patients and healthcare workers before operation are therefore essential.

Adult↗

PubMed2000

The incidence of enlarged chondrons in normal and osteoarthritic human cartilage and their relative matrix density.

OBJECTIVE: To quantitate changes in the pericellular matrix in osteoarthritic (OA) articular cartilage. DESIGN: Chondrons were enzymatically isolated from normal and OA human cartilage. The cross-sectional area of the chondrons were measured. After immunolabeling for keratan sulfate, type VI collagen and type II collagen, the relative matrix density was determined for different size classes of chondrons with quantitative fluorescence microscopy. RESULTS: For individual chondrons, the average cross-sectional area (344+/-28 microm(2), mean+/-SE) for the normal specimens was significantly smaller than the average area (439+/-30 microm(2)) for the OA specimens. Using 496 microm(2) (mean+2 SD of the normal area) as the cut-off for enlarged chondrons, 33% of individual OA chondrons were enlarged compared to 16% for the normal. Chondrons under 300 microm(2) had a significantly higher density of keratan sulfate and type VI collagen than larger chondrons, while chondrons over 400 microm(2) had similar matrix densities. CONCLUSIONS: There is a higher incidence of enlarged chondrons in OA cartilage than in normal cartilage. The enlargement may initially be due to hydrodynamic swelling but further increases in size are due to increased matrix deposition.

Adult↗

PubMed2000

Early failure of revision total hip arthroplasty with cemented precoated femoral components: comparison with uncemented components at 2 to 8 years.

This is a retrospective analysis of 2 methods of fixation of the femoral component in 86 consecutive revision arthroplasties, for which all clinical and radiographic data were recorded prospectively. There were 56 cemented revisions using precoated femoral components followed for 2 to 8 years (mean, 4 years) and 30 uncemented, proximally porous-coated femoral revisions followed for 2 to 6 years (mean, 4 years). Of the 56 cemented hips, 31 (55%) had a good or excellent clinical result. Rerevision has been performed in 10 hips, and revision of 3 loose femoral components is pending (23%). Radiographic review of 56 femoral components showed that 16 (29%) had probable or definite loosening. Of 30 cementless hips, 24 (80%) had a good or excellent clinical result. There was radiographic bone ingrowth in 22 of 30 hips (73%). Seven hips (23%) had nonprogressive subsidence, and 3 hips (10%) had progressive subsidence or loosening. Rerevision has been performed in only 2 hips (7%). The high rate of loosening (29%) and rerevision (23%) at a mean follow-up of only 4 years suggests that a precoated femoral component may place increased stress at the already damaged bone-cement interface.

Adult↗

PubMed2000

Open reduction and cementation for femoral head fracture secondary to avascular necrosis: preliminary report.

Current treatment for femoral head avascular necrosis has shown good results in early stages of disease, but are not as impressive after progression to collapse. We treated 19 patients (20 hips) with Stage III avascular necrosis (AVN) by open reduction augmented by methylmethacrylate cementation. Follow up ranges from 6 months to 2 years (average = 8.7 months). We followed patient progress with pre- and post-operative Harris Hip Scores, Womac Osteoarthritis Index and a Health Status Questionnaire (SF36). All patients realized immediate post-operative pain relief and improvement in function. Harris Hip, Womac Osteoarthritis Index and SF36 physical health scores improved significantly from 54.0 to 79.5 (p < 0.05), 54.3 to 29.8 (p < 0.05) and 28.4 to 42.4 (p < 0.05), respectively. Three patients had a conversion to total hip arthroplasty. Cementation is technically simple, burns no bridges and enables patients a rapid recovery. The long term results, in regards to progression of disease and secondary arthritis, are unknown.

Activities of Daily Living↗

PubMed1999

Alterations in the Young's modulus and volumetric properties of chondrocytes isolated from normal and osteoarthritic human cartilage.

The mechanical environment of the chondrocyte is an important factor that influences the maintenance of the articular cartilage extracellular matrix. Previous studies have utilized theoretical models of chondrocytes within articular cartilage to predict the stress-strain and fluid flow environments around the cell, but little is currently known regarding the cellular properties which are required for implementation of these models. The objectives of this study were to characterize the mechanical behavior of primary human chondrocytes and to determine the Young's modulus of chondrocytes from non-osteoarthritic ('normal') and osteoarthritic cartilage. A second goal was to quantify changes in the volume of isolated chondrocytes in response to mechanical deformation. The micropipette aspiration technique was used to measure the deformation of a single chondrocyte into a glass micropipette in response to a prescribed pressure. The results of this study indicate that the human chondrocyte behaves as a viscoelastic solid. No differences were found between the Young's moduli of normal (0.65+/-0.63 kPa, n = 44) and osteoarthritic chondrocytes (0.67+/-0.86 kPa, n = 69, p = 0.93). A significant difference in cell volume was observed immediately and 600 s after complete aspiration of the cell into the pipette (p < 0.001), and the magnitude of this volume change between normal (11+/-11%, n = 40) and osteoarthritic (20+/-11%, n = 41) chondroctyes was significantly different at both time points (p < 0.002). This finding suggests that chondrocytes from osteoarthritic cartilage may have altered volume regulation capabilities in response to mechanical deformation. The mechanical and volumetric properties determined in this study will be of use in analytical and finite element models of chondrocyte-matrix interactions in order to better predict the mechanical environment of the cell in vivo.

Adult↗

PubMed1999

Knee arthroplasty in hemophilic arthropathy.

Twenty-three total knee arthroplasties in 15 patients with severe hemophilia were performed between February 1974 and September 1988. Thirteen patients had Factor VIII deficiency and two had Factor IX deficiency. The mean followup period was 7.5 years, with a minimum of 4 years for patients who were alive (eight) at the time of this review. Seven patients had died before this report, and all were seropositive for the human immunodeficiency virus. Using the Hospital for Special Surgery knee scoring system, the result was excellent in one knee, good in three, fair in two, and poor in 17. One patient was seropositive for the human immunodeficiency virus at the time of the index procedure, and 12 were seropositive at the most recent followup; the human immunodeficiency status of three patients was unknown. There were two early and two late deep infections, all in patients who were seropositive for the human immunodeficiency virus. The most recent postoperative radiographs for all knees were reviewed using the Knee Society radiographic scoring system. Ten femoral components were well fixed, 11 were possibly loose, and two were probably loose. Eight tibial components were well fixed, 10 possibly loose, three probably loose, and two definitely loose. One knee had been revised for aseptic loosening. There are few published studies of the long term results of total knee arthroplasties in patients with hemophilia. In this series of 23 knees, there was a high rate of loosening and infection. Total knee arthroplasty may be a useful treatment for the relief of pain attributable to end stage hemophilic arthropathy, but there is a high rate of complications, especially in patients who are seropositive for the human immunodeficiency virus.

Adolescent↗

PubMed1999

Efficacy of prophylaxis against thromboembolism with intermittent pneumatic compression after primary and revision total hip arthroplasty.

BACKGROUND: Thromboembolism is a common and important complication after total hip arthroplasty. A variety of pharmacological and mechanical measures have been proposed for prophylaxis. The purpose of the present study was to evaluate the efficacy of intermittent pneumatic compression as prophylaxis against thromboembolism following total hip arthroplasty. METHODS: The prospective study involved a consecutive series of 425 patients in whom a total of 502 (324 primary and 178 revision) total hip arthroplasties had been performed by two surgeons. The patients were managed intraoperatively and postoperatively with use of thigh-high elastic compression stockings and thigh-high intermittent pneumatic compression sleeves. Experienced vascular technologists performed venous duplex ultrasonography on both lower extremities of all patients at a mean of six days (range, two to fifteen days) postoperatively. All patients were followed for at least one year in order to detect late thromboembolism. RESULTS: An asymptomatic deep-vein thrombosis was noted on the scans made after twenty-three (4.6 percent) of the 502 procedures. Nineteen (3.8 percent) of the arthroplasties were followed by the development of a proximal thrombosis and four (0.8 percent), a distal thrombosis. Nineteen of the thromboses were ipsilateral (eighteen were proximal and one, distal), and four were contralateral (one was proximal and three, distal). No symptomatic deep-vein thrombosis developed in the hospital. In addition, three (two proximal and one distal) symptomatic ipsilateral deep-vein thromboses (a prevalence of 0.6 percent) developed three to twenty-three weeks after postoperative scans revealed negative findings and the patients were discharged from the hospital. Three symptomatic pulmonary embolisms (a prevalence of 0.6 percent) were confirmed by ventilation-perfusion scanning while the patients were in the hospital. There were no symptomatic pulmonary embolisms after discharge, and there were no fatal pulmonary embolisms. With the numbers available, we were unable to detect an association between deep-vein thrombosis and age (p = 0.76), gender (p = 0.13), body-mass index (p = 0.12), type of arthroplasty (primary or revision) (p = 0.12), operative approach (p = 0.37), duration of the operation (p = 0.21), type of anesthesia (general or regional) (p = 0.51), units of blood transfused (autologous, p = 0.79; homologous, p = 0.57), blood type (p = 0.18), or the presence of a so-called classic risk factor for the development of thrombosis (p = 0.22). Five arthroplasties (1.0 percent) were followed by the development of a wound hematoma, but only one hematoma necessitated operative drainage. CONCLUSIONS: The use of intraoperative and postoperative thigh-high intermittent pneumatic compression, combined with duplex ultrasonography performed by experienced vascular technologists, is effective for prophylaxis against thromboembolism after both primary and revision total hip arthroplasties. The low prevalence of deep-vein thrombosis (4.6 percent) and symptomatic pulmonary embolism (0.6 percent) is comparable with that associated with pharmacological prophylaxis.

Arthroplasty, Replacement, Hip↗

PubMed1999

Cortical strut allografts for the treatment of femoral fractures and deficiencies in revision total hip arthroplasty.

Thirty-three hips had revision total hip arthroplasty, using an average of three cortical strut allografts fixed to the femur with cables and followed-up for a mean of 4 years. The indications for strut allografts were ectatic femurs or segmental defects of the femoral diaphysis (22 hips), femoral fractures (10 hips), and severe proximal femoral osteolysis (1 hip). Twenty-one hips had an excellent or good clinical result, 6 had a fair clinical result, and 6 had a poor clinical result. Reoperation was done in six hips, but in only two hips was reoperation related to failure of the allograft. Nine of the 10 femoral fractures repaired with allograft struts healed by 3 to 6 months. Radiographs showed partial or complete bridging of the allograft to host bone with peripheral remodeling and minimal resorption in 30 of 33 hips. Strut allografts, fixed with multiple cables, are an important adjunct to femoral component revision for the restoration of deficient femoral bone stock and in the treatment of periprosthetic femur fractures.

Adult↗

PubMed1998

Relationship of femoral head and acetabular size to the prevalence of dislocation.

Two clinical studies, one prospective randomized and one retrospective, were performed to evaluate the relationship of femoral head size and acetabular component outer diameter to the prevalence of dislocation of the modular total hip replacement. Between October 1995 and April 1996, 31 primary total hip arthroplasties in 30 patients were randomized to a femoral head diameter of 22 mm or 28 mm, for two groups of acetabular components of outer diameters of 56 mm or larger and 54 mm or smaller. Head size (22 mm) and acetabular component outer diameter (> or = 56 mm) were found to increase the risk of dislocation. From December 1984 to January 1994, 308 primary total hip arthroplasties were performed through a posterior approach by one surgeon using a modular 28 mm femoral head and one type of uncemented acetabular component. The rate of dislocation for acetabular components with an outer diameter of 62 mm or larger was increased significantly (five of 36 hips, 14%) compared with those with an outer diameter of 60 mm or smaller (11 of 272 hips, 4%).

Acetabulum↗

PubMed1998

The value of serial postoperative radiographs of total knee arthroplasties.

In a prospective study of 35 cemented press fit condylar knees, we studied the prevalence of radiolucent lines 1 mm wide or wider using two methods of detection: conventional (plain) and fluoroscopically-guided radiographs. All films were evaluated in accordance with the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. A total of 12 radiolucencies were detected in nine knees (26% of all knees) using conventional radiographs versus 25 radiolucencies in 13 knees (37% of all knees) using fluoroscopically-guided radiographs. This was a statistically significant difference and suggests that the true prevalence of periprosthetic radiolucencies will be underestimated if conventional radiographs are used to evaluate the bone-prosthesis interfaces and questions the value of routine postoperative plain film radiographs to evaluate the results of knee arthroplasty.

Aged↗

PubMed1997

Isolated chondrons: a viable alternative for studies of chondrocyte metabolism in vitro.

OBJECTIVE: To develop and test a simple enzymatic procedure for isolating chondrons, which consist of the chondrocytes and their surrounding pericellular microenvironment. DESIGN: Chondrons were obtained by digesting adult human articular cartilage with a mixture of dispase and collagenase. Chondrons and chondrocytes were cultured in alginate beads, immunofluorescence labeled and examined by confocal microscopy. RESULTS: Comparison of freshly isolated chondrons with cryostat sections of cartilage revealed that type VI collagen, type II collagen and aggrecan were retained, but fibronectin and a unique chondroitin sulfate epitope recognized by the antibody, 7D4, were lost. Comparison of enzymatic and mechanical homogenization methods revealed subtle changes in chondron morphology and retention of fibronectin in mechanically isolated chondrons. Average yield of enzyme-isolated chondrons was slightly lower than that of chondrocytes isolated by pronase and collagenase digestion, but was much greater than that reported for mechanically isolated chondrons. Enzyme-isolated chondron viability was greater than 80% 1 day after isolation, and continued to be above 80% through 7 weeks of alginate bead culture. Viability of isolated chondrocytes was initially greater than 80% but fell to 60-80% with time in culture. Chondrons and isolated chondrocytes had a similar division rate except osteoarthritic chondrons were significantly slower after 2 weeks in culture. Cell division was more rapid for nonosteoarthritic chondrons than for osteoarthritic ones. CONCLUSIONS: Enzymatic isolation of chondrons is relatively simple, gives better yield and viability than mechanical isolation, but comparable yield and viability of traditional chondrocyte isolation. Enzymatic chondron isolation allows the effect of the in vivo-formed pericellular matrix on chondrocyte metabolism to be studied in vitro.

Adolescent↗

PubMed1997

The influence of patient-related factors and the position of the acetabular component on the rate of dislocation after total hip replacement.

The senior one of us performed 438 primary and 181 revision total hip arthroplasties with use of so-called modern prostheses between July 1983 and January 1994. Fifty-three patients, who had had forty-seven primary procedures and twelve revisions, either died or were lost to follow-up less than two years after the operation and were excluded from the study. The results for the remaining 446 patients (391 primary procedures and 169 revisions) were analyzed to determine the influence of patient-related and operative factors and the position of the acetabular component on the rate of dislocation. Dislocation occurred after thirty-two (6 per cent) of the 560 total hip arthroplasties: seventeen (4 per cent) of the 391 primary procedures and fifteen (9 per cent) of the 169 revisions (p = 0.046). There was no relationship between the variables of age, gender, obesity, or preoperative diagnosis and dislocation after either primary or revision arthroplasty. Seven (23 per cent) of the thirty arthroplasties in the patients who had a history of excessive intake of alcoholic beverages (more than 2.1 liters [seventy-two ounces] of beer or more than 0.2 liter [six ounces] of other alcoholic beverages a day) were followed by a dislocation compared with twenty-five (5 per cent) of the 530 arthroplasties in the patients who did not have such a history. This difference was significant for the patients who had had a revision arthroplasty (p = 0.00005), but with the numbers available we could not detect a difference for those who had had a primary arthroplasty (p = 0.264). Radiographic analysis was performed for thirty-two hips that had dislocated and thirty-two that had not (seventeen primary procedures and fifteen revisions in each group), matched exactly according to the type of prosthesis and the operative approach (but not age). We detected no association between either the version or the abduction angle of the acetabular component (within the range of 39 to 56 degrees for the primary prostheses and 38 to 57 degrees for the revision prostheses) and the risk of dislocation. Thirty of the thirty-two hips in each group had an abduction angle of the acetabular component that was in the so-called safe range of 30 to 50 degrees.

Acetabulum↗

PubMed1996

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.

Adult↗

PubMed1996

Total hip replacement for coxarthrosis secondary to congenital dysplasia and dislocation of the hip. Long-term results.

Between 1970 and 1982, sixty-six total hip replacements were performed with cement, without bone-grafting, in fifty-three patients who had congenital dysplasia and dislocation of the hip. Preoperatively, the patients had had Crowe type-II, III, or IV subluxation. Current information was available for fifty-nine hips in forty-six patients after an average duration of follow-up of sixteen years (range, ten to twenty-one years). The average age of the patients at the time of the operation was fifty-three years (range, twenty-three to seventy-three years). The average Harris hip score at the most recent examination was 92 points (range, 61 to 100 points). Eight hips were revised. The reason for the revision was infection in two hips, fracture of the femoral stem in two, and loosening of the acetabular component in four. The rate of revision for aseptic loosening, therefore, was 10 per cent (six hips). In the unrevised hips for which radiographs were available, the rate of radiographic loosening of the femoral component was 5 per cent (two hips) and that of the acetabular component was 32 per cent (twelve hips). We did not find a relationship between the amount of horizontal or vertical displacement of the center of the femoral head and the rate of loosening. Kaplan-Meier survivorship analysis with revision as the end point predicted a rate of survival of 85 per cent (95 per cent confidence interval, 75 to 95 per cent) at fifteen years. With radiographic loosening as the end point, the predicted rate of survival was 68 per cent (95 per cent confidence interval, 54 to 81 per cent) at fifteen years. We concluded that, for patients who have Crowe type-II, III, or IV congenital dysplasia of the hip, good long-term results can be obtained with insertion of a femoral stem with cement. The high rate of loosening of cemented acetabular components is a concern.

Adult↗

PubMed1995

A simple technique for insertion of distal screws into interlocking nails.

Placement of distal interlocking screws into femoral and tibial nails is an exacting technique. Many techniques are described, each with their advantages and disadvantages. We describe an alternative technique using the "third point in space." This method has been successfully used in > 30 cases. It is universal, reproducible, and inexpensive, avoiding the use of distal targeting guides, expensive radiolucent drills, or visual estimations of alignment.

Biometry↗

PubMed1995

Techniques for the removal of broken small-diameter tibial nails: a report of two cases.

The availability of small-diameter interlocking nails for unreamed applications has expanded the indications for intramedullary nailing of open tibial shaft fractures. Smaller diameter nails that are inserted without reaming are mechanically weaker than the larger-diameter nails that are inserted after intramedullary reaming. Potentially, nails with a smaller diameter will fail at a higher rate, creating unique difficulties associated with their removal. This article presents two cases that illustrate solutions to those problems.

Adult↗