Biomedical subjects
Publications and source records attributed to R H Walker.
Sjögren's syndrome (SS) is a common multisystem autoimmune disorder. As with other autoimmune disorders such as systemic lupus erythematosus (SLE), SS has been associated with a wide range of neurologic abnormalities. Parkinsonism has been reported previously in five SS patients. We present three additional cases of SS with parkinsonism.
One hundred ninety-nine patients who underwent primary total hip arthroplasty and used in hospital pneumatic compression stockings and aspirin as thromboembolic prophylaxis were screened for deep venous thrombosis using duplex ultrasonography on the fourth postoperative day. Of the initial 98 patients, 21 underwent noncemented arthroplasty, maintained touchdown weightbearing for 6 weeks after surgery, and then began progressive partial weightbearing. Of the subsequent 101 patients, 28 underwent noncemented arthroplasty and began progressive weightbearing immediately after surgery. All other patients underwent hybrid arthroplasty and began weightbearing to tolerance immediately after surgery. After duplex screening examination, patients with proximal deep venous thrombosis were given anticoagulation therapy, and patients with negative study results were observed clinically. The relative risk of proximal deep venous thrombosis after noncemented arthroplasty using delayed weightbearing was compared with that after noncemented arthroplasty using immediate progressive weightbearing. Of patients with noncemented arthroplasty, the prevalence of proximal deep venous thrombosis was significantly lower in those using progressive weightbearing immediately after surgery (none) than in those using delayed weightbearing rehabilitation (19%). This study showed that patients undergoing noncemented total hip arthroplasty with delayed weightbearing rehabilitation risk greater potential for deep venous thrombosis after hospital discharge. This study suggests consideration for continued thromboembolic prophylaxis or routine deep venous thrombosis surveillance, or both measures, after hospital discharge, unless more rapid progression of weightbearing is allowed.
Postoperative duplex ultrasonography screening after total hip arthroplasty has been shown to identify patients who may require treatment or additional monitoring for venous thromboembolic disease. The potential for manifestation of venous thromboembolic disease subsequent to screening remains a concern. The objective of this study was to determine the prevalence of symptomatic venous thromboembolic disease after total hip arthroplasty and after inhospital prophylaxis, inhospital screening with negative results for proximal deep venous thrombosis, and no posthospitalization venous thromboembolic disease prophylaxis. One hundred fifty patients undergoing primary hybrid total hip arthroplasty and using pneumatic compression stockings and aspirin as prophylaxis against venous thromboembolic disease were screened for deep venous thrombosis with duplex ultrasonography on the fourth day after surgery. Duplex ultrasonography screening revealed 17 (11.3%) patients with asymptomatic proximal deep venous thrombosis. In response to duplex ultrasonography screening, these patients with proximal deep venous thrombosis received therapeutic anticoagulation. Of 133 patients with a duplex screen with negative results for proximal deep venous thrombosis, 131 (98.5%) continued to have no symptoms of venous thromboembolic disease and two (1.5%) began to have symptoms for venous thromboembolic disease (one with proximal deep venous thrombosis, one with nonfatal pulmonary embolism) during 12 months of clinical followup after total hip arthroplasty. The overall prevalence of venous thromboembolic disease requiring anticoagulation was 19 of 150 (12.6%) patients. The remaining 131 (87.4%) were not exposed to the risks of postoperative anticoagulation and did not have subsequent symptomatic venous thromboembolic disease.
A common assumption among orthopedic surgeons is that cemented/hybrid total hip arthroplasty (THA) results in lower transfusion requirements than noncemented THA. The hypothesized mechanism to account for transfusion differences is that cement application, after polymerization, decreases perioperative blood loss. To evaluate this theory, a retrospective matched-pair study was performed to quantify perioperative, intraoperative, postoperative blood loss, and transfusion requirements among patients undergoing cemented/hybrid and noncemented THA. Twenty-five THA procedures were either cemented or hybrid and 25 were noncemented. Patients were matched with respect to age, gender, weight, and diagnosis. Six patients in the noncemented group and 10 in the cemented/hybrid group received autologous blood in the Post Anesthesia Care Unit. Among this subgroup, those in the cemented/hybrid group received a significantly greater volume of transfused blood (519.20 mL, versus 291.67 mL in the noncemented group, P < .017). After stratifying patients by gender, additional analysis revealed a greater total blood loss in the male population than in females (1848 mL versus 1464 mL, P < .004). Males also had a greater drain volume (548 mL versus 414 mL, P < .02). The female population utilizing hormone replacement therapy (HRT) was found to have a lesser blood loss (810 mL versus 1209 mL, P < .0107) and received a smaller amount of transfused blood (1164 mL versus 1377 mL) than those who were not on HRT. Other significant findings included a shorter length of stay in the cemented/hybrid group (6.85 versus 7.56 days, P < .012). Based on this matched-pair retrospective analysis of blood requirements, there is no indication that cemented/hybrid and noncemented THA procedures result in different blood requirements. However, differences were found in several areas when the population was stratified by gender. The information obtained from this study is important in its ability to solidify a foundation from which blood management decisions can be made.
This article describes a technique to aid in removal of polymethylmethacrylate during total hip arthroplasty revision. The technique is a modification of prior windowing techniques and requires no specialized instruments, offers substantial flexibility regarding cement removal and femoral prosthetic choice, and minimizes the amount and duration of stress on the femur. The technique involves making an oblong window in the anterior or anterolateral femur. Proximal and distal osteotomies are made with a crescentic oscillating saw and connected by straight beveled anterior and posterior longitudinal osteotomies using a straight oscillating saw. Once the intramedullary canal is prepared, either a nonecmented or cemented femoral prosthesis can be placed. The cortical window is replaced with a single cable used for fixation.
Two series of 100 consecutive primary total hip arthroplasties, each using a single design of noncemented or cemented femoral component (all 28 mm heads), were compared. One cemented and two noncemented stems underwent revision for aseptic loosening. Of unrevised hips, outcome data statistically favored cemented, rather than noncemented, stems. The data for cemented and noncemented stems, respectively, were: An excellent to good result in 97% versus 88%; thigh pain in 3% versus 40%; subsidence in 0% versus 22%; and endosteal cavitation in 6% versus 12%. For patients with 25 unrevised matched pairs, selected by gender, age, diagnosis, and weight, outcome data also statistically favored cemented over noncemented stems, respectively: an excellent or good result in 25 versus 20 hips; thigh pain in two versus eight hips; and subsidence in none versus six hips. Midterm followup data for these concurrent total hip arthroplasty series of a mid 1980s design revealed prevalence of mechanical failure of 1% for cemented stems and 4% for noncemented stems. Corroborating matched pair comparison neutralized selection bias as a causative factor for these differences. These data indicate contemporary cemented femoral stem fixation is superior to second generation noncemented femoral stem fixation. Controlled comparative studies at midterm to long term followup, such as in this report, are needed to define outcome and indications for current third generation noncemented stem fixation.
The use of modular components in total hip arthroplasty has been thought to contribute to accelerated polyethylene wear. Specifically, a modular femoral head with a flange extension and a longer neck may cause increased wear. The purpose of the current study was to evaluate the effect of a flange extension on polyethylene wear. Ninety-one patients who had had a total of 100 primary total hip arthroplasties were evaluated after an intermediate duration of follow-up. All of the acetabular components consisted of a hemispherical titanium-alloy fiber-mesh porous-coated shell with a nonelevated modular polyethylene liner; they were inserted without cement and with use of supplemental screws through the dome after so-called line-to-line reaming. All of the femoral components consisted of a modular head with a diameter of twenty-eight millimeters and either a long neck (with a flange extension) or a short or medium neck (without a flange extension). The study group comprised sixty-two patients (sixty-six hips) who had had radiographic evaluation that was adequate to allow the valid measurement of polyethylene wear. Thirty-two hips were in men, and thirty-four were in women. The mean age of the patients was fifty-six years, the mean weight was seventy-three kilograms, and the mean duration of follow-up was 6.1 years (range, four to eight years). The rate of polyethylene wear in the eleven hips in which the femoral component had a flange extension was significantly greater than that in the fifty-five in which the femoral component did not have a flange extension (mean, 0.17 compared with 0.11 millimeter per year; p = 0.009). Multivariate analysis showed that the presence of a flange extension was associated with increased polyethylene wear to a greater degree (F = 2.86) than were all other variables that were measured, including a younger age (F = 1.72), a more vertical angle of the acetabular component (F = 0.49), a heavier weight (F = 0.14), male gender (F = 0.11), and a smaller initial thickness of the polyethylene (F = 0.02). These data support an association between the presence of a modular femoral head with a flange extension and an accelerated rate of polyethylene wear. The presumed mechanism is an increase in peripheral, or so-called rim, impingement of the flange-reinforced neck on the acetabulum due to a decrease in the ratio between the diameters of the femoral head and neck.
This prospective study evaluates 100 consecutive Harris-Galante Porous (Zimmer, Warsaw, IN) noncemented femoral prostheses 4 to 8 years after surgery. Two femoral components were revised for aseptic loosening. The mean Harris hip score was 56 before surgery and 92 at final follow-up evaluation, with moderate thigh pain seen in 6%. Ingrowth was classified as bony (89%), stable fibrous (8%), and unstable (3%). A pedestal formed in 18%, measurable subsidence occurred in 22%, and endosteal erosion occurred in 12%. Patients with pedestal formation had a higher incidence of unstable growth pattern (P < .05). Patients with bony ingrowth had a lower mean subsidence (0.38 mm) than those with fibrous stable ingrowth (3 mm) and unstable ingrowth (7.5 mm) (P < .05). Thigh pain correlated with the type of ingrowth, and endosteal erosion with the linear polyethylene wear. Survival analysis was 97.5% at 8 years.
This article provides simple mathematical formulas for approximating values such as blood volume, red cell mass, and plasma volume. Additionally, other useful formulas and examples are given to estimate increments in hemoglobin, platelets, and factor VIII levels following the transfusion of blood components.
A retrospective review of 95 consecutive primary total hip arthroplasty patients was performed to assess the clinical outcome of two postoperative bladder management protocols. The first 49 patients (group 1) were treated with a pro re nata straight catheterization protocol. The next 46 patients (group 2) were treated with an indwelling catheterization protocol. There were no differences between the groups with respect to sex or age. The patients in group 2 had significantly lower incidences of urinary retention (P < .0005) and bladder distention (P < .0005) than those in group 1. Preoperative systemic diseases and urologic symptoms did not correlate with the occurrence of postoperative urinary retention or bladder distention. There were no infections in group 1. In group 2, one patient (2%) had bacteriuria and one patient (2%) had a urinary tract infection (P > .1). This trend of increased contamination in the catheterization group may be related to a mean catheterization duration of 72 hours.
The effectiveness, benefits, and potential risks of employing a total hip arthroplasty cemented femoral component distal centralizer were evaluated. First postoperative (6-week) radiographs of 100 primary hybrid total hip arthroplasties in consecutive groups of 50 patients without and 50 patients with a femoral stem distal centralizer were retrospectively reviewed. Femoral stems with a distal centralizer were more centralized within the femoral canal (center of stem tip to center of intramedullary canal: mean, 1.1 mm with a centralizer, 3.2 mm without; P<.0001) and more neutrally aligned (mean, 0.7 degrees valgus with a centralizer, 1.3 degrees valgus without; P < .01). Femoral stems with a distal centralizer were less likely to have a cement mantle with suboptimal thickness, that is, less than 2 mm at the medial distal femoral stem (3 of 50 stems with a centralizer, 22 of 50 stems without; chi-square, P<.0001). There were no complications, adverse effects on the cement mantle, radiographic evidence of loosening, or implant failures associated with the use of a distal centralizer, with a minimum follow-up period of 2 years.
One hundred cemented total hip arthroplasties (THAs) were evaluated regarding the potential benefit of THA femoral component distal stem centralization, specifically regarding cement mantle thickness. Factors potentially predictive of femoral component mechanical loosening, both relating (22 factors) and not relating (41 factors) to cement, were analyzed on initial postoperative radiographs. Nine THAs with femoral component mechanical failure (group 1) were compared to (1) 88 non-failed THAs (group 2) and (2) 9 matched-paired, nonfailed THAs (group 3). Significant differences were evident regarding minimum and maximum cement mantle thickness in Gruen zone 5 and combined zones 5/6 (groups 1 vs 2 and groups 1 vs 3), with failed femoral components having thinner cement mantles. Discriminate analysis determined minimum cement mantle thickness in zone 5 to be the factor most predictive of femoral component failure. These data indicate that a suboptimal (thin) cement mantle at the medial diaphysis (Gruen zones 5 and 6) contributed to femoral component mechanical loosening in this THA series. This relationship may not pertain to femoral stems of different materials or cross-sectional characteristics. Many THA systems currently provide for a method of centralization of the femoral component distal stem as a mechanism to ensure an adequate circumferential distal cement mantle. Continued investigation into techniques directed toward centralization of the distal femoral stem is warranted by the findings of this study.
One hundred consecutive patients had a primary unilateral total hip arthroplasty with use of a single design of the femoral component (Harris Precoat), inserted with a so-called third-generation cementing technique, between July 1985 and June 1987. There were seventy-four women and twenty-six men. The mean age at the time of the operation was seventy-one years (range, forty-one to ninety-two years) and the mean weight was seventy kilograms (range, forty-eight to 105 kilograms). Eleven of the 100 patients died during the follow-up period, all with the implant in place. Of the eighty-nine surviving patients, one had a revision arthroplasty for aseptic loosening. The mean duration of clinical follow-up for the remaining eighty-eight patients was seven years (range, six to eight years). The mean Harris hip score at the latest follow-up evaluation was 91 points (range, 68 to 97 points). Of the eighty-eight patients, eighty-five (97 percent) had a good or excellent result. Radiographic follow-up was performed for eighty-one patients; none had evidence of loosening of the stem, and five (6 percent) had endosteal cavitation but were asymptomatic. The rate of failure (loosening or revision) of the femoral component in the entire series was 1 per cent (one hip). The low rate of failure and the maintenance of good and excellent clinical and radiographic results during this period of follow-up are consistent with reports from other institutions. This strengthens the argument to retain or widen the existing indications for the insertion of a femoral stem with cement in primary total hip arthroplasty.
Duplex ultrasonography of the lower extremity was used for routine non-invasive screening for asymptomatic proximal and distal deep venous thrombosis, for monitoring of potential propagation of deep venous thrombosis from distal to proximal, and for confirmation of the resolution of proximal deep venous thrombosis after treatment. In the first part of the study, to substantiate the accuracy of duplex ultrasonography, 130 lower limbs (seventy-nine patients) were studied with that modality as well as with venography after a total hip or total knee arthroplasty. Compared with venography, duplex ultrasonography demonstrated 100 per cent sensitivity, specificity, and accuracy for the detection of proximal deep venous thrombosis and 88 per cent sensitivity, 98 per cent specificity, and 98 per cent accuracy for the detection of distal deep venous thrombosis. In the second part of the study, 100 patients who had had a total knee arthroplasty and had been managed with pneumatic stockings and aspirin for prophylaxis against deep venous thrombosis had screening of both lower extremities with duplex ultrasonography on the fourth postoperative day. Duplex ultrasonography demonstrated proximal deep venous thrombosis in seven patients and distal deep venous thrombosis in twenty-two patients; all twenty-nine patients were asymptomatic. The patients who had distal deep venous thrombosis had surveillance with serial duplex ultrasonography on the seventh and fourteenth postoperative days; five of these patients were found to have had propagation of the thrombosis to the proximal deep veins.(ABSTRACT TRUNCATED AT 250 WORDS)
Duplex ultrasonography was used to screen 273 consecutive patients, on the fourth day after a total hip or total knee arthroplasty, for the presence of a distal deep venous thrombosis. Patients who had a history of thromboembolic disease or who had an active neoplasm were excluded from the study. Of the 273 patients, twenty-four (9 per cent) were found to have a proximal deep venous thrombosis (a thrombosis involving the femoral or popliteal veins) and forty-one (15 per cent), a distal deep venous thrombosis (a thrombosis involving the veins of the calf). All of the thromboses were asymptomatic. The forty-one patients in whom a distal deep venous thrombosis had been detected with duplex screening subsequently had serial duplex examinations, on the seventh and fourteenth postoperative days. If a proximal deep venous thrombosis was detected, anticoagulation was begun immediately. If no proximal thrombosis was observed, the distal thrombosis was considered stable, the serial duplex examinations were terminated, and clinical observation was continued. Of the forty-one patients who had serial examinations, seven (17 per cent) had a proximal deep venous thrombosis in the ipsilateral limb by the fourteenth postoperative day; all seven were asymptomatic, and all were managed with anticoagulation. Thirty-four patients (83 per cent) were determined to have a stable distal deep venous thrombosis on the fourteenth postoperative day, and no additional duplex examinations were performed. Thirty-three (97 per cent) of these thirty-four patients remained asymptomatic for deep venous thrombosis thereafter; the remaining patient (3 per cent) had a proximal deep venous thrombosis in the ipsilateral limb eleven months postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)
Prophylaxis of venous thromboembolism can be categorized as primary prevention and secondary prevention. Primary prevention is the deterrence of a disease process before it begins. Secondary prevention is the detection and treatment of an asymptomatic disease process before it becomes symptomatic. This discussion deals with duplex ultrasonography as a method of secondary prevention of venous thromboembolism after total joint replacement. Routine screening by venography and by duplex ultrasonography has been advocated by several authors in cases of total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, compared with venography, duplex ultrasonography has the advantages of being portable, painless, noninvasive, without side effects, less expensive and, depending on the institution, reliable as a screening and surveillance tool for managing deep vein thrombosis (DVT). Part one of a three-part study was designed to substantiate reliability of duplex ultrasonography in detecting DVT after total joint replacement in the lower extremity at our institution (Scripps Clinic and Research Foundation in La Jolla, Calif). Parts two and three were designed to evaluate the utility of duplex ultrasonography for routine screening and surveillance of DVT after THA and TKA.
The use of duplex ultrasonography for routine noninvasive screening, monitoring, and management of deep venous thrombosis after total hip arthroplasty was evaluated. The reliability of duplex ultrasonography for detection of deep vein thrombosis was confirmed in an initial cohort of 51 total hip arthroplasty patients (102 lower extremities), demonstrating 91% sensitivity, 98% specificity, and 97% accuracy when compared with venography. A second cohort of 110 total hip arthroplasty patients using pneumatic compression stockings and aspirin as deep vein thrombosis prophylaxis underwent screening duplex ultrasonography of both lower extremities on postoperative Day 4. Duplex ultrasonography screening showed 10 (9.1%) patients with proximal deep vein thrombosis and 10 (9.1%) with distal deep vein thrombosis, all of whom were asymptomatic. The 10 patients with proximal deep vein thrombosis on duplex ultrasonography were prescribed therapeutic anticoagulation. Duplex ultrasonography subsequently confirmed resolution of proximal deep vein thrombosis in these patients before discontinuation of anticoagulation; none developed symptomatic pulmonary embolism through 12-month clinical followup. The 10 patients with distal deep vein thrombosis diagnosed by duplex ultrasonography were not treated with anticoagulation, but were monitored by serial duplex ultrasonography through postoperative Day 14 for propagation of distal to proximal deep vein thrombosis; none manifested symptomatic deep vein thrombosis or pulmonary embolism through 12-month clinical followup. The 90 patients with negative duplex ultrasonography results were followed clinically; 3 developed late symptomatic proximal deep vein thrombosis (1 of these later manifested pulmonary embolism). Therefore, duplex ultrasonography was used after total hip arthroplasty for the following: (1) to screen routinely in the hospital for asymptomatic proximal and distal deep vein thrombosis; (2) to monitor for potential propagation of distal to proximal deep vein thrombosis; (3) to minimize exposure to therapeutic anticoagulation by confirming the absence of proximal deep vein thrombosis in 97 of 110 patients; and (4) to demonstrate the effectiveness of mechanical and systemic deep vein thrombosis management by confirming the absence or resolution of deep vein thrombosis in all 110 patients.
Medium spiny neurons are the projection neurons of the striatum. They receive the majority of striatal afferents, and they make up the vast majority of all neurons in the striatum. These densely spiny cells thus constitute a major substrate for input-output processing in the striatum. In the experiments described here we analyzed the dendritic fields of spiny neurons in the squirrel monkey striatum and plotted their orientations with respect to the borders between striosomes and matrix. Medium-sized spiny neurons in the caudate nucleus were filled intracellularly in a fixed-slice preparation with the fluorescent dye Lucifer Yellow. Dendritic arbors were reconstructed following immunostaining of the injected neurons with antiserum to Lucifer Yellow and counterstaining for striosome/matrix compartments. A majority of the medium spiny neurons studied had dendritic arborizations that remained within their compartment of origin. Thus the striosome/matrix subdivision not only partitions neurotransmitter molecules and extrinsic striatal connections into two domains in the primate caudate nucleus, but also constrains the dendritic arbors of many projection neurons there. Other medium spiny neurons, however, in both striosomes and matrix, had dendrites that crossed from one compartment into the other. About a quarter of the spiny neurons reconstructed had at least one such crossing dendrite. These results suggest that compartmentalization of afferent and efferent processing by projection neurons in the primate striatum is not absolute. For a subpopulation of spiny neurons in striosomes and matrix, inputs to one compartment could have a direct influence on output cells of the other.