Biomedical subjects

F J Dorey

Publications and source records attributed to F J Dorey.

At least 55 records · Page 3Linked to original sources

PubMed1994

Morphometry of the prostate: I. Distribution of tissue components in hyperplastic glands.

OBJECTIVES: Morphometry, or quantitative image analysis, offers great promise in characterizing the various histologic types of benign prostatic hyperplasia (BPH), but to date, a systematic study of the tissue components is lacking. Thus we employed morphometry to examine the distribution of primary BPH tissues throughout whole human prostates. METHODS: The prostate glands of 20 men with BPH were removed for low-volume carcinoma and subjected to a uniform, comprehensive, systematic quantification of the primary BPH tissue components using the technique of digitization and point-count morphometry. RESULTS: We found the following average volumes among the 20 glands: epithelium, 19.9% (S.D. 5.1%, range 11.7% to 30.8%); fibromuscular stroma, 50.4% (S.D. 9.4%, range 32.2% to 74.4%); glandular lumina, 29.7% (S.D. 8.9%, range 11.9% to 47.5%). Within the individual prostates, we found symmetry in primary BPH tissue distribution, except that the outer prostate was on average 25% richer in epithelium than the inner prostate (p < 0.05). When tissue composition was determined in simulated biopsy specimens, corrected for radial (ie, inner vs outer gland) orientation, the correlation with whole-organ composition was statistically significant for "percentage epithelium" (r = 0.72, p < 0.01) and for "stromal/epithelial ratio" (r = 0.63, p < 0.01). CONCLUSIONS: Major differences in primary tissue composition may separate different hyperplastic prostates. Primary BPH tissues are rather symmetrically distributed within individual prostates. Quantitative histologic differences between prostates, potentially important in clinical decision-making may be accurately diagnosed by morphometry of radially oriented biopsy specimens.

Aged↗

PubMed1994

151 endoprosthetic reconstructions for patients with primary tumors involving bone.

As part of the UCLA limb salvage program, 151 patients received 151 endoprostheses for primary tumors involving bone. Follow-up of all patients was to death (56), revision (21), or a minimum two years for the 74 additional survivors (range: 24-114 months; mean: 52 months). Endoprosthetic replacements were of the distal femur (81), proximal femur (19), proximal humerus (13), proximal tibia (11), scapula (11), total femur (8), total humerus (4), intercalary prostheses (2), and one each of the distal humerus and the pelvis. There were three soft tissue sarcomas, five benign bone lesions, and 143 primary malignant tumors of bone. MSTS function was good-excellent in 78%. There were 64 local complications in 55 patients (36%). Mechanical failure occurred in 24 patients (15.9%), local recurrence occurred in ten (6.6%), minor wound healing problems in nine (5.9%), and infection in eight (5.3%). Few systemic complications were reported. Function appeared to be location dependent. All of the 29 patients with benign or low grade malignant tumors (parosteal, IA, IB) have survived. Of the 116 patients with stage IIA and IIB disease, 59% survived three years, and a Kaplan-Meier analysis projects that 56% are expected to survive at five years. Only 17 (11%) of these 151 endoprostheses have been revised; an additional four (3%) eventually came to amputation. The Kaplan-Meier analysis revealed that 91% of the prostheses survived three years and 83% survived five years. The Cox Proportional Hazards model revealed that for patients with stage IIA and IIB disease, the risk of death is four times the risk of the need for revision at five years. Although endoprosthetic reconstructions have their own unique complications, they have proven durable in this series of patients. Local problems usually can be managed without amputation, and patient satisfaction is high.

Bone Neoplasms↗

PubMed1994

Inter- and intraobserver variation in staging patients with proven avascular necrosis of the hip.

Diagnosis and treatment of avascular necrosis of the hip has long been predicated on the evaluation of plain radiographs, though other modalities (such as magnetic resonance imaging) are being increasingly used to aid in this evaluation. The Ficat classification is commonly used to assess plain radiographs and to help determine what treatment is appropriate for a given patient. It also is used to help evaluate patient outcome after surgical or nonsurgical treatment. This study was designed to evaluate the adequacy of plain radiographs in the evaluation of avascular necrosis of the hip. The plain radiographs of 25 hips with avascular necrosis were analyzed on 3 occasions by 6 readers (450 total readings). A clinically significant difference in radiographic staging was defined as a Stage I or II reading of the radiographs of a given hip on 1 reading and a separate reading of the same radiographs as Stage III or IV. By this definition, interobserver variability for the first reading resulted in clinically significant differences in 10 (40%) of the 25 hips. Intraobserver variability resulted in clinically significant differences for 10 (40%) of the 25 hips as well. The most experienced readers in the study (a total joint specialist and a musculoskeletal radiologist) were consistent internally in their readings in 90% of cases, and had a clinically significant difference in only 1 case (1%); however, these same 2 readers disagreed with one another on the staging of 9 (36%) of 25 hips, with 4 (16%) of 25 hips having a clinically significant difference in readings.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗

PubMed1994

Heterotopic ossification prophylaxis following operative treatment of acetabular fracture.

Eighty seven patients with 88 fractures were retrospectively reviewed to assess the effect of postoperative prophylaxis on the formation of heterotopic ossification (HO). Sixty eight patients with 69 acetabular fractures were followed for an average of 21 months (range, 3-98 months). The grade of HO was assessed using the Brooker classification system. Thirty four fractures had no prophylactic treatment, 30 were treated prophylactically with indomethacin, two with radiation therapy, and three with both indomethacin and radiation. Twenty (59%) of 34 untreated fractures developed HO, of which nine (26%) were Grade III or IV. Thirteen (43%) of 30 fractures treated with indomethacin developed HO, of which 5 (16%) were Grade III and none were Grade IV. Twenty one of 24 fractures were stabilized through the extended iliofemoral approach; 13 of these had no prophylaxis. Eleven of the 13 developed HO; eight were Grade III or IV (62%). Seven of eight fractures treated with indomethacin following the extended iliofemoral approach developed HO; one was Grade III (13%) and non Grade IV. There was no significant difference between 13 patients who were not treated prophylactically and 18 indomethacin treated patients stabilized through the Kocher-Langenbeck approach. Only one of 11 patients had HO (Grade I) following an ilioinguinal approach. Postoperative radiation therapy, with or without indomethacin, resulted in three patients with Grade 0 HO (all radiated 1-4 days post surgery), one with Grade II (radiated postoperative Day 8), and one with Grade III HO (significant delay in surgery with preoperative Grade III HO of the hip).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetabulum↗

PubMed1994

The effects of diuretics on posttraumatic joint stiffness and limb swelling in a rabbit periarticular fracture model.

Periarticular long bone fractures usually result in soft-tissue swelling because of edema and hemorrhage, as well as progressive, often permanent joint stiffness. The authors evaluated the effects of chlorothiazide, a commonly used diuretic, and acetazolamide, a weaker diuretic with a different mechanism of action, on joint stiffness and swelling using an established rabbit hindlimb model. Bilateral distal tibial fractures were produced in 30 adolescent New Zealand white rabbits. Twelve rabbits served as age-matched controls and received no treatment, 11 were treated with chlorothiazide, and seven were treated with acetazolamide, each for five days at doses adjusted for body weight but equivalent to human dosing. Eleven limbs were excluded from study because of fracture angulation in excess of 10 degrees. The mean stiffness ratios, comparing preoperative stiffness with stiffness at the end of the three-week study period, for diuretic-treated rabbits were significantly less than those in the control rabbits; there was no difference between the two treated groups. The total swelling and time to peak swelling did not differ among the three groups; however, peak swelling was least in the chlorothiazide group, the strong diuretic, when compared with the control and acetazolamide groups. The marked effect of diuretics on joint stiffness and their minimal effect on limb swelling were unexpected results and, taken in conjunction with previous treatment modalities tested in this model, indicate a complex, still poorly understood sequence of events leading to joint stiffness after periarticular injury.

Acetazolamide↗

PubMed1993

Multiple imputation for threshold-crossing data with interval censoring.

Medical statistics often involve measurements of the time when a variable crosses a threshold value. The time to threshold crossing may be the outcome variable in a survival analysis, or a time-dependent covariate in the analysis of a subsequent event. This paper presents new methods for analysing threshold-crossing data that are interval censored in that the time of threshold crossing is known only within a specified interval. Such data typically arise in event-history studies when the threshold is crossed at some time between data-collection points, such as visits to a clinic. We propose methods based on multiple imputation of the threshold-crossing time with use of models that take into account values recorded at the times of visits. We apply the methods to two real data sets, one involving hip replacements and the other on the prostate specific antigen (PSA) assay for prostate cancer. In addition, we compare our methods with the common practice of imputing the threshold-crossing time as the right endpoint of the interval. The two examples require different imputation models, but both lead to simple analyses of the multiply imputed data that automatically take into account variability due to imputation.

Data Interpretation, Statistical↗

PubMed1993

Extramedullary porous coating to prevent diaphyseal osteolysis and radiolucent lines around proximal tibial replacements. A preliminary report.

Nineteen patients who had a primary malignant bone tumor of the proximal end of the tibia were managed with wide resection and implantation of a tibial endoprosthesis with cement, combined with a rotating-hinge knee replacement. In the first ten patients, a ring of porous coating was applied to the part of the tibial replacement that was just proximal to the intramedullary portion of the stem, to encourage ingrowth of bridging bone. No growth of bone into these porous rings occurred, and the rings were not applied to the next nine endoprostheses. During the subsequent follow-up period, progressive osteolysis (resorption of more than two millimeters of the proximal end of the remaining tibial cortex) developed in only one patient (who had a deep infection) in the group of ten patients who had a porous ring, compared with five of the nine patients who did not have a porous ring but in whom osteolysis developed. This difference was significant (p < 0.001). In addition, the tibial osteolysis was associated with the subsequent development of progressive periprosthetic radiolucent lines at the bone-cement interfaces (p = 0.001). We postulated that, in the patients who had an extramedullary porous ring, the periprosthetic fibrous capsule that formed around the extramedullary portion of all the implants became firmly adherent to the ring, thereby sealing off the part of the capsule that was distal to the ring. The particulate wear debris that was contained within the articular portion of the capsule could not reach the distal tibial bone surrounding the prosthetic stem, and debris-incited osteolysis, which leads to loosening, did not develop. If this mechanism is confirmed, it could have important implications for the design of implants that are used in joint replacement.

Adolescent↗

PubMed1992

Nitric oxide as a mediator of relaxation of the corpus cavernosum in response to nonadrenergic, noncholinergic neurotransmission.

BACKGROUND: Nitric oxide has been identified as an endothelium-derived relaxing factor in blood vessels. We tried to determine whether it is involved in the relaxation of the corpus cavernosum that allows penile erection. The relaxation of this smooth muscle is known to occur in response to stimulation by nonadrenergic, noncholinergic neurons. METHODS: We studied strips of corpus cavernosum tissue obtained from 21 men in whom penile prostheses were inserted because of impotence. The mounted smooth-muscle specimens were pretreated with guanethidine and atropine and submaximally contracted with phenylephrine. We then studied the smooth-muscle relaxant responses to stimulation by an electrical field and to nitric oxide. RESULTS: Electrical-field stimulation caused a marked, transient, frequency-dependent relaxation of the corpus cavernosum that was inhibited in the presence of N-nitro-L-arginine and N-amino-L-arginine, which selectively inhibit the biosynthesis of nitric oxide from L-arginine. The addition of excess L-arginine, but not D-arginine, largely reversed these inhibitory effects. The specific liberation of nitric oxide (by S-nitroso-N-acetylpenicillamine) caused rapid, complete, and concentration-dependent relaxation of the corpus cavernosum. The relaxation caused by either electrical stimulation or nitric oxide was enhanced by a selective inhibitor of cyclic guanosine monophosphate (GMP) phosphodiesterase (M&B 22,948). Relaxation was inhibited by methylene blue, which inhibits cyclic GMP synthesis. CONCLUSIONS: Our findings support the hypothesis that nitric oxide is involved in the nonadrenergic, noncholinergic neurotransmission that leads to the smooth-muscle relaxation in the corpus cavernosum that permits penile erection. Defects in this pathway may cause some forms of impotence.

Adult↗

PubMed1992

Applications of crude incidence curves.

Crude incidence curves display the cumulative number of failures of interest as a function of time. With competing causes of failure, they are distinct from cause-specific incidence curves that treat secondary types of failures as censored observations. After briefly reviewing their definition and estimation, we present five applications of crude incidence curves to show their utility in a broad range of studies. In some of these applications it is helpful to model survival-time distributions with use of two different time metameters, for example, time from diagnosis and age of the patient. We describe how one can incorporate published vital statistics into the models when secondary types of failure correspond to common causes of death.

Antineoplastic Agents↗

PubMed1992

Intra-articular corticosteroid reduces joint stiffness after an experimental periarticular fracture.

Early care after surgery or trauma to the extremities often includes a period of immobilization. The resultant joint stiffness may require extensive rehabilitation and may permanently limit function of the limb. Posttraumatic joint stiffness is particularly vexing in the small joints. In an experimental model, we tested the effects of intra-articular corticosteroid injections on stiffness in a joint at risk of posttraumatic joint stiffness. Triamcinolone was injected into ankle joints of rabbits after distal tibial fractures. Three weeks after injury, joint stiffness increased 34% in ankles injected with the steroid. Stiffness in ankles injected with saline solution and in ankles treated with no injection increased 133% and 224%, respectively. Limb swelling and tibial torsional strength to failure were not significantly affected by either of the treatments.

Animals↗

PubMed1992

Double-stem silicone implant arthroplasty of all metatarsophalangeal joints in patients with rheumatoid arthritis.

Double-stem silicone implants have been used to reconstruct destroyed hallux metatarsophalangeal joints (MTPJ) for many years. When smaller implants became available, they were used to reconstruct the lateral four MTPJ. An arthroplasty of all MTPJ was performed using these implants in 44 patients (72 feet) with rheumatoid arthritis (RA). The mean age of patients was 46 years (range, 21 to 66) and 84% were female. Previous surgery had been performed on 28% of the feet. All patients were followed prospectively for an average of 67 months (range, 36 to 111). The patients were evaluated clinically and radiographically; results were recorded on a standardized foot form that allowed computer analysis of the data. The results showed improvement in the hallux valgus angle from 41.6 degrees to 16.1 degrees postoperatively, with no loss of correction over time. Similarly, other forefoot deformities, such as plantar callus and lateral toe abnormalities, all improved both clinically and radiographically. The pain, walking, and function scores all improved, with the greatest improvement being pain relief. Radiographic analysis showed some evidence of fracture in seven hallux (9.7%) and nine lateral toe (3%) implants. Only three toes with implant fracture had some pain at follow-up examination. Three other lateral toe implants were removed for pain. There was no evidence of deep infection or silicone synovitis. Other complications included superficial infection, delayed wound healing, and second surgery for heterotopic bone excision.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Acetabular reconstruction with a threaded prosthesis for failed total hip arthroplasty.

The MEC-Ring threaded acetabular component was used in 35 patients for revision of failed cemented hip arthroplasties, and 32 have been observed for two to four years (mean, 2.5 years). With only a short-term follow-up period, 44% of patients have already required revision for failure of the MEC-Ring acetabular component. Patients with especially poor acetabular bone stock that had had structural bone graft had a significantly higher rate of failure. The authors developed a technique of supine oblique roentgenograms that allowed better visualization of the component-bone interface. Eighty-six percent of patients had radiolucencies, and 67% of these were progressive. The presence of progressive radiolucencies, component migration, or both was associated with a higher failure rate. Progressive radiolucencies were also associated with a worse pain score in patients whose arthroplasties have not failed. The MEC-Ring threaded component is not recommended for revision hip arthroplasty, especially in cases with poor acetabular bone stock.

Acetabulum↗

PubMed1992

A comparison of total hip arthroplasty and hemiarthroplasty for treatment of acute fracture of the femoral neck.

One hundred sixty-six acute, nonpathologic displaced femoral neck fractures in elderly patients were treated with either unipolar hemiarthroplasty (122 operations; 77 cemented, 45 uncemented) or total hip arthroplasty (THA) (44 operations; all cemented). The average age, (75.2 years of age in the THA group 76.2 years of age in the hemiarthroplasty group), anesthesia risk classification, in-hospital mortality, early complications, and dislocation rates were comparable in each treatment group. In an average long-term follow-up period of 56 months, pain, walking, and function scores were higher with THA than with cemented or uncemented hemiarthroplasty. Revision rates were 2.2% after THA, versus 7.9% for cemented hemiarthroplasty and 13% for uncemented hemiarthroplasty. Hemiarthroplasty is recommended for the older patient, who may be occasionally active outside of the household. The healthy, active patient, however, may benefit from THA rather than hemiarthroplasty.

Acute Disease↗

PubMed1992

Etiology of deep sepsis in total hip arthroplasty. The significance of hematogenous and recurrent infections.

Between January 1970 and August 1986, 3051 total hip arthroplasties (THAs) were performed at the authors' institution. Forty-seven hips in 43 patients developed deep infection. Using clinical and laboratory criteria, patients were classified into four modes of infection: (1) surgical contamination, which included hips (N = 13) with a suspicious clinical course (e.g., persistent elevation of sedimentation rate, early radiographic signs of loosening) without another identifiable source; (2) hematogenous spread, which included septic hips (N = 19) with a temporally related infectious source and an organism consistent with that source; (3) recurrent sepsis, septic failure in a previously infected hip (N = 13); and finally, (4) infection from direct or contiguous spread, which occurred in an additional two patients. Thus the majority of infections were nonsurgical. Patients with surgically acquired infections tended to present earlier, were less likely to require a Girdlestone procedure for salvage, and were more likely to be reimplanted (p = 0.024). The incidence of surgical infections decreased with the use of improved antiseptic techniques. The incidence of hematogenous infection, however, increased during the time that a cohort was followed. Additionally, in a previously septic hip, septic failure may occur as late as seven years after THA.

Bacteria↗

PubMed1991

Incidence of deep sepsis in total hip arthroplasty. Survivorship analysis over 17 years from one hospital.

Of 3,051 total hip arthroplasties (THA) performed between January 1970 and August 1986, 47 hips in 43 patients developed deep periprosthetic infection. This population was divided temporally into three groups based on changes in our perioperative antiseptic technique. Using survivorship analysis, a significant decrease in the sepsis rate in primary THA was seen in the period since 1974 (P less than .03). Comparing all surgeries in the most recent cohort (1980-1986) to others by a Cox Proportional Hazards model (which accounts for differences in follow-up results), indicates that the relative risk of sepsis has decreased by half in this latest group. Contemporary perioperative antiseptic techniques have lowered the risk of infection in THA. Further significant decreases in sepsis incidence will likely require a reduction in the incidence of infection acquired outside the operating room.

Anti-Infective Agents, Local↗

PubMed1991

Patient activity, sports participation, and impact loading on the durability of cemented total hip replacements.

Patients with either cemented surface replacements or cemented stemmed hip prostheses and who regularly participate in sporting activities or heavy labor after total joint arthroplasty are at twice the long-term risk of requiring revision surgery for loosening as patients who are less active. For patients with surface replacement total hip arthroplasty (THA), the adverse effects of activity are greatest in patients with preoperative diagnoses other than osteoarthritis, and were seen by the sixth year postsurgery. For patients with conventional stemmed prostheses, the effects of patient activity are not seen until about ten years postsurgery. For resurfacing THA for osteoarthritis, the long-term of loosening is primarily in patients who participate in high impact activities.

Bone Cements↗

PubMed1991

Nerve palsy associated with total hip replacement. Risk factors and prognosis.

We reviewed the results of 3126 consecutive total hip replacements and identified postoperative neuropathy in the ipsilateral lower extremity after fifty-three (1.7 per cent) over-all and after 1.3 per cent of the primary arthroplasties. The prevalence was 5.2 per cent after the primary arthroplasties that had been done for congenital dislocation or dysplasia of the hip and 3.2 per cent after the revisions (all diagnoses). Thus, these two types of operations were risk factors (p less than 0.01). Limb-lengthening only partially accounted for the increased prevalence of neuropathy after these procedures. The sciatic nerve was involved in all but five extremities. The cause of the palsy was unclear or unknown in thirty (57 per cent) of the extremities. When the patients were last seen, at a minimum of one year and a maximum of sixteen and one-half years after the operation, seven extremities were normal neurologically, thirty-three had a mild neurological deficit, and thirteen had a major deficit. All patients who had complete recovery of neurological function had it by twenty-one months. Of thirty-six extremities that were evaluated at a minimum of twenty-four months after the operation, seven were neurologically normal, twenty-three had a mild persistent deficit, and six had a major persistent deficit. The ability to walk decreased for all patients who had a nerve palsy. The greatest disability was in the patients who had been forty-eight years old or less and had had a primary total hip replacement (p = 0.037). The prognosis for neurological recovery was related to the degree to which the nerve was damaged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Endoprosthetic replacement for stage IIB osteosarcoma.

Over an eight-year period, 100 patients with IIB osteosarcoma have been managed. Eighty-one were treated with limb-salvage procedures, 78 of which involved reconstruction utilizing endoprostheses. Only 19 patients received amputation as the primary treatment for local control. Since 1984, all patients received preoperative and post-operative adjuvant chemotherapy. Those patients who received chemotherapy had a statistically significant improvement in five-year survival over those who did not (57% and 32%, respectively, p = 0.014). The functional results were good overall, with excellent results seen in distal femoral reconstruction. Twenty-eight of the 78 patients treated with endoprosthetic reconstruction experienced 30 complications (36%). Mechanical failure was the most common complication (10%) but was generally correctable. The local recurrence rate was 5% and the infection rate was 3%. Local complications were manageable. A statistical analysis revealed that the relative risk of patient death was 2.5 times higher than prosthesis failure for the 78 patients with endoprosthetic reconstruction. The intermediate-term results, with a median follow-up period of 43 months, remains encouraging.

Adolescent↗