Biomedical subjects
Publications and source records attributed to J Parvizi.
Arthritis of the hip in the young adult can be a disabling condition. Recent years have witnessed extensive research related to the management of this condition. This article reviews the current status with regard to aetiology, diagnosis and treatment of arthritis of the hip in the young adult.
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In a study of thioflavin S-stained serial sections from the entire brainstem, we found that the inferior and superior colliculi and the autonomic, monoaminergic, cholinergic, and classical reticular nuclei were affected with varying degrees of severity and frequencies in 32 patients with Alzheimer's disease, whereas no changes were seen in the brainstems of 26 control subjects. The majority of the affected nuclei in patients with Alzheimer's disease exhibit either neurofibrillary tangles or senile plaques, and only a few display both. However, when sections were immunostained with the antibodies 10D5 and AT8 or ALZ50, both beta-amyloid and hyperphosphorylated epitopes of tau protein were found to be present in various concentrations in all the affected nuclei. Our findings suggest that each brainstem nucleus has a distinct vulnerability to Alzheimer's disease-related pathological changes. Given that each nucleus has idiosyncratic neuroanatomical connections and prevailing neurochemical characteristics, the heterogeneous collection of brainstem nuclei can be considered a suitable anatomical ground for further investigation of selective vulnerability in Alzheimer's disease. The finding of severe pathological changes in some brainstem nuclei also raises the possibility that the dysfunction of these nuclei may contribute to the cognitive defects and increased rates of morbidity and mortality in patients with Alzheimer's disease.
In the first part of this article we summarize a theoretical framework and a set of hypotheses aimed at accounting for consciousness in neurobiological terms. The basic form of consciousness, core consciousness is placed in the context of life regulation; it is seen as yet another level of biological processing aimed at ensuring the homeostatic balance of a living organism; and the representation of the current organism state within somato-sensing structures is seen as critical to its development. Core consciousness is conceived as the imaged relationship of the interaction between an object and the changed organism state it causes. In the second part of the article we discuss the functional neuroanatomy of nuclei in the brainstem reticular formation because they constitute the basic set of somato-sensing structures necessary for core consciousness and its core self to emerge. The close relationship between the mechanisms underlying cortical activation and the bioregulatory mechanisms outlined here is entirely compatible with the classical idea that the reticular formation modulates the electrophysiological activity of the cerebral cortex. However, in the perspective presented here, that modulation is placed in the setting of the organism's homeostatic regulation.
Patients with pathological laughter and crying (PLC) are subject to relatively uncontrollable episodes of laughter, crying or both. The episodes occur either without an apparent triggering stimulus or following a stimulus that would not have led the subject to laugh or cry prior to the onset of the condition. PLC is a disorder of emotional expression rather than a primary disturbance of feelings, and is thus distinct from mood disorders in which laughter and crying are associated with feelings of happiness or sadness. The traditional and currently accepted view is that PLC is due to the damage of pathways that arise in the motor areas of the cerebral cortex and descend to the brainstem to inhibit a putative centre for laughter and crying. In that view, the lesions 'disinhibit' or 'release' the laughter and crying centre. The neuroanatomical findings in a recently studied patient with PLC, along with new knowledge on the neurobiology of emotion and feeling, gave us an opportunity to revisit the traditional view and propose an alternative. Here we suggest that the critical PLC lesions occur in the cerebro-ponto-cerebellar pathways and that, as a consequence, the cerebellar structures that automatically adjust the execution of laughter or crying to the cognitive and situational context of a potential stimulus, operate on the basis of incomplete information about that context, resulting in inadequate and even chaotic behaviour.
The current study evaluated the results of total knee arthroplasty for the treatment of isolated patellofemoral degenerative arthritis. Between 1980 and 1997, 31 total knee arthroplasties were done in 24 patients with advanced, isolated patellofemoral arthritis. The average followup was 5.2 years (range, 2-12 years). There was a significant improvement in the mean preoperative Knee Society pain and function scores. Twenty-one knees required a lateral retinacular release and three knees required additional formal proximal realignment at the time of the total knee arthroplasty. There were three reoperations in this series including, manipulation for poor motion in one patient; revision of a loose patellar component in one patient; and extensor mechanism realignment in the third patient. At midterm followup, total knee arthroplasty proved to be reliable and durable in alleviating pain and improving function in this group of patients with isolated, advanced patellofemoral arthritis. Surgeons should be made aware, however, that resurfacing of the patella and balancing the extensor mechanism for patients with isolated patellofemoral arthritis can be demanding technically as evidenced by the high rate of asymmetrically resurfaced patellas, the high rate of lateral retinacular release, and formal realignment procedures.
BACKGROUND: Rotator cuff disease or injury is one of the most frequently seen orthopaedic conditions, and surgical repair of rotator cuff tears is a common procedure. A prospective analysis of the operation, with consistent assessment of patient characteristics, variables associated with the rotator cuff tear and repair techniques, and outcome factors, was performed. METHODS: One hundred and five shoulders with a chronic rotator cuff tear underwent open surgical repair and acromioplasty between 1975 and 1983. The patients were followed for an average of 13.4 years (range, two to twenty-two years). There were sixteen small tears, forty medium tears, thirty-eight large tears, and eleven massive tears. The tears were repaired directly (seventy-two tears), by V-Y plasty (twelve), by tendon transposition (twenty), or by reinforcement with a fascia lata graft (one). The long head of the biceps had been previously torn in eleven shoulders and was tenodesed in three other shoulders. In fifty-six shoulders, the distal part of the clavicle was excised for treatment of degenerative arthritic changes, often associated with osteophyte formation. RESULTS: Satisfactory pain relief was obtained in ninety-six shoulders (p < 0.0001). There was significant improvement in active abduction (p < 0.001) and external rotation (p < 0.007) as well as in strength in these directions of movement (p < 0.03 and p < 0.002, respectively). At the latest follow-up evaluation, the result was rated as excellent for sixty-eight shoulders, satisfactory for sixteen, and unsatisfactory for twenty-one. Tear size was the most important determinant of outcome with regard to active motion, strength, rating of the result, patient satisfaction, and need for a reoperation. Older age, less preoperative active motion, preoperative weakness, distal clavicular excision, and a transposition repair technique were all associated with larger tear size. There were eight reoperations; five were for rerepair of a persistent or recurrent rotator cuff tear. CONCLUSIONS: Standard tendon repair techniques combined with anterior acromioplasty, postoperative limb protection, and monitored physiotherapy can produce consistent and lasting pain relief and improvement in range of motion. Improving the results of this procedure will depend upon the development of new techniques to address the active motion and strength deficiencies following repair of massive rotator cuff tears.
BACKGROUND: There have been sporadic reports on perioperative mortality associated with total knee arthroplasty. The purpose of this study was to determine risk factors for such mortality. METHODS: A computer-assisted review of the records of 22,540 consecutive patients who had undergone total knee arthroplasty between 1969 and 1997 was performed to identify all patients who had died within thirty days after the procedure. A detailed analysis of the medical, surgical, anesthetic, and pathological records of the patients was performed, and the mortality was determined according to age, gender, diagnosis, and fixation method. RESULTS: The rate of mortality within thirty days after the operation was 0.21% (forty-seven of 22,540). All deaths occurred in the group of 18,810 patients who had received a cemented implant, and no deaths occurred among the 3730 patients who had received an uncemented implant (p < 0.0001). The mortality rate was 0.24% (forty-three of 18,165) after primary arthroplasty and 0.09% (four of 4375) after revision arthroplasty (p < 0.0003). Three patients (0.01%) died during the operation. Forty-three of the forty-seven patients who died had a history of preexisting cardiovascular and/or pulmonary disease. Simultaneous bilateral total knee arthroplasty was associated with a significantly higher rate of perioperative mortality (p < 0.002). CONCLUSIONS: Factors that were associated with a significantly increased mortality after total knee arthroplasty included an age of more than seventy years, primary (as compared with revision) knee surgery, use of a cemented prosthesis, preexisting cardiopulmonary disease, and simultaneous bilateral arthroplasty.
BACKGROUND: Ankylosing spondylitis is a seronegative spondyloarthropathy that primarily affects the sacroiliac joints, spine, hips, and, less commonly, the knee joints. The purpose of this study was to evaluate the results in a consecutive group of patients with ankylosing spondylitis who underwent total knee arthroplasty. METHODS: The results of thirty total knee arthroplasties in twenty patients with ankylosing spondylitis were reviewed. There were seventeen men and three women, with an average age of fifty-five years (range, twenty-eight to sixty-seven years) at the time of the arthroplasty. The diagnosis of ankylosing spondylitis was established preoperatively with use of the New York criteria. All patients received a cemented condylar-type implant. The average duration of follow-up was 11.2 years (range, three to sixteen years). RESULTS: The average Knee Society pain score improved from 14 points preoperatively to 76.3 points at the time of the latest follow-up. The improvement in the average Knee Society function score was less impressive, with an increase from 16.3 points preoperatively to 58.7 points at the time of the latest follow-up. The average arc of motion was 84.8 degrees prior to the arthroplasty and 86.7 degrees at the time of the final follow-up. Six knees (20%) had heterotopic bone formation. Three knees required manipulation under anesthesia because of poor motion postoperatively. There was one revision, due to loosening of a patellar component. All other components were radiographically stable at the time of the latest follow-up. CONCLUSIONS: Total knee arthroplasty with cement in patients with ankylosing spondylitis provided excellent pain relief and durable fixation at an average of 11.2 years postoperatively. However, patients with ankylosing spondylitis are at increased risk for the development of stiffness and heterotopic bone formation.
BACKGROUND: Previous reports on perioperative mortality associated with hip arthroplasty have not documented, to our knowledge, patient characteristics and surgical factors that increase the likelihood of death. The purpose of this study was to determine the prevalence of and associated risk factors for perioperative death after elective hip arthroplasty. METHODS: The records of 30,714 consecutive patients who had undergone elective hip arthroplasty at our institution from 1969 to 1997 were retrospectively reviewed to identify patients who had died within thirty days after the procedure. Mortality rates were determined according to age, gender, diagnosis, implant type, and fixation mode. RESULTS: Ninety deaths occurred within thirty days after elective total hip arthroplasty, for an overall mortality rate of 0.29% (ninety of 30,714). The thirty-day mortality rate was significantly higher for patients with preexisting cardiovascular disease (p < 0.0001), male patients (p < 0.0001), and patients who were seventy years of age or older (p < 0.0002). The mortality rate was slightly, but not significantly, higher for patients with an underlying diagnosis of rheumatoid arthritis (p < 0.36) and those receiving cemented implants (p < 0.57). There was no difference in the thirty-day mortality rate for revision as compared with primary hip arthroplasty (p < 0.92). CONCLUSIONS: Factors that are associated with an increased risk of mortality within thirty days after elective hip arthroplasty include an older age, male gender, and a history of cardiorespiratory disease. There has been a significant decline in the thirty-day mortality rate after elective hip arthroplasty in the last decade (p < 0.0002); during the 1990s, the overall rate at our institution was 0.15% (twenty-three of 14,989).
OBJECTIVE: To identify and assess the impact of postoperative complications in patients with unrecognized or known obstructive sleep apnea syndrome (OSAS) undergoing hip replacement or knee replacement compared with control patients undergoing similar operations. Although OSAS is a risk factor for perioperative morbidity, data quantifying the magnitude of the problem in patients undergoing non-upper airway operations are limited. PATIENTS AND METHODS: This retrospective, case-control study from a single academic medical institution included patients diagnosed as having OSAS between January 1995 and December 1998 and undergoing hip or knee replacement within 3 years before or anytime after their OSAS diagnosis. Patients with OSAS were subcategorized as having the diagnosis either before or after the surgery and also, regardless of time of diagnosis, by whether they were using continuous positive airway pressure (CPAP) prior to hospitalization. Matched controls were patients without OSAS undergoing the same operation. Interventions were defined specifically as administration of a particular treatment in the context of each complication, eg, supplemental oxygen, implementation of additional monitoring such as oximetry for hypoxemia, or transfer to the intensive care unit (ICU) for cardiac ischemia concerns. Postoperative complications were assessed for all patients in the different categories and included respiratory events such as hypoxemia, acute hypercapnia, and episodes of delirium. Serious complications were noted separately, including unplanned ICU days, reintubations, and cardiac events. The length of hospital stay was also tabulated. RESULTS: There were 101 patients with the diagnosis of OSAS in this study and 101 matched controls. Thirty-six patients had their joint replacement before OSAS was diagnosed, and 65 had surgery after OSAS was diagnosed. Of the latter 65 patients, only 33 were using CPAP at home preoperatively. Complications were noted in 39 patients (39%) in the OSAS group and 18 patients (18%) in the control group (P=.001). Serious complications occurred in 24 patients (24%) in the OSAS group compared with 9 patients (9%) in the control group (P=.004). Hospital stay was significantly longer for the OSAS patients at a mean +/- SD of 6.8 +/- 2.8 days compared with 5.1 +/- 4.1 days for the control patients (P<.007). CONCLUSION: Adverse postoperative outcomes occurred at a higher rate in patients with a diagnosis of OSAS undergoing hip or knee replacement compared with a group of matched control patients.
In a series of [15O]PET experiments aimed at investigating the neural basis of emotion and feeling, 41 normal subjects recalled and re-experienced personal life episodes marked by sadness, happiness, anger or fear. We tested the hypothesis that the process of feeling emotions requires the participation of brain regions, such as the somatosensory cortices and the upper brainstem nuclei, that are involved in the mapping and/or regulation of internal organism states. Such areas were indeed engaged, underscoring the close relationship between emotion and homeostasis. The findings also lend support to the idea that the subjective process of feeling emotions is partly grounded in dynamic neural maps, which represent several aspects of the organism's continuously changing internal state.
The results of 20 total hip and knee arthroplasties performed in patients with morbid obesity who were treated with bariatric surgery before arthroplasty are reviewed. Bariatric surgery was successful in reducing the Quetelet ratio (weight in kilogram divided by height in square meters) of patients from a mean of 49 kg/m(2) (range, 38-56 kg/m(2)) to a mean of 29 kg/m(2) (range, 25-32 kg/m(2)). The average time from bariatric surgery to arthroplasty was 23 months (range, 7-65 months). The cumulative Knee Society score had improved significantly from a mean of 103.6 (range, 45-165) before arthroplasty to a mean of 148.9 (range, 66-185) at final follow-up in 12 knees undergoing total knee arthroplasty (P<.01). The Harris hip score also had increased significantly from a prearthroplasty mean of 40 (range, 25-55) to 67.5 (range, 50-95) at final follow-up in 8 hips receiving total hip arthroplasties (P<.05). All but 1 patient with continuing patellofemoral pain were satisfied with the result of the arthroplasty at final follow-up. One hip was revised at 5 years for aseptic loosening of the femoral component; no knee revisions were required. All other prostheses were stable with no evidence of radiographic loosening or wear at final surveillance. Morbidly obese individuals, with severe degenerative joint disease, who are considered unsuitable for arthroplasty because of excess weight should be considered for bariatric surgery. Total joint arthroplasty after surgical treatment of obesity has an excellent outcome with an acceptable complication rate.
The orbitofrontal cortex has been examined in Alzheimer's disease (AD) from the viewpoint of neurofibrillary tangle (NFT) pathology, its laminar distribution and topography. NFT pathology in the orbitofrontal cortex is extensive in AD. In cases with extensive cortical pathology, NFTs extend from the pole of the frontal lobe to the orbitoinsular junction. In lesser affected cases, the anterior granular part of the orbital cortex is less invested by NFTs. Layers III and V contain the greatest density of NFTs and these are most dense in the dysgranular areas, posterior to the transverse orbital sulcus. Posterior and medial orbitofrontal areas, forming area 13 and the posterior tip of the paraolfactory gyrus, are the most severely damaged, as are the smaller agranular fields that surround the olfactory tract and cortex. The widespread orbitofrontal damage in AD affecting projection neurons suggests that this pathology may contribute heavily to the many non-memory-related behavior changes observed in this disorder.
BACKGROUND: Recurrent instability of the hip in the absence of an identifiable cause is a challenging problem. It has been proposed that bipolar hip arthroplasty may have a role in the treatment of these complex cases. The purpose of our study was to evaluate the results of bipolar hip arthroplasty for the treatment of recurrent instability of the hip in a series of patients at our institution. METHODS: We reviewed the records of twenty-seven patients who had undergone bipolar hip arthroplasty as a salvage procedure for the treatment of recurrent instability of the hip after total hip replacement. All patients had undergone at least two, and a mean of three, stabilizing operative procedures on the hip prior to the bipolar arthroplasty. The mean duration of follow-up was five years (range, two to twelve years), with no patient lost to follow-up. There were six deaths, of unrelated causes. RESULTS: Bipolar arthroplasty prevented redislocation in twenty-two hips (81 percent). At the time of final follow-up, twenty-five patients (93 percent) had a stable hip. Five patients (19 percent) had had episodes of subluxation or dislocation following the bipolar arthroplasty. Two of these patients had only a single episode of dislocation that was treated successfully by immobilization. Two of the remaining three patients required a reoperation because of the instability. The hip was stabilized with the use of a constrained cup prosthesis in one of these patients, and the other patient eventually required resection arthroplasty. The third patient had continuing instability but improved function and pain relief, and a reoperation was not performed. There were a total of seven reoperations; these included revision because of disassembly of the cup in one hip, revision bipolar arthroplasty because of continuing instability in two, resection arthroplasty because of deep infection in two, revision arthroplasty because of recalcitrant groin pain in one, and revision arthroplasty because of deep infection and superior migration of the implant in one. The Harris hip score improved significantly, from a mean of 24 points (range, 5 to 45 points) preoperatively to a mean of 55 points (range, 35 to 80 points) postoperatively (p < 0.05). CONCLUSIONS: We believe that, despite some potential problems, bipolar hip arthroplasty can have a role in the salvage management of recurrent instability of the hip in patients in whom other stabilization procedures have failed.
The periaqueductal gray matter (PAG) is a major neuroanatomical component of the brainstem and has pivotal roles in autonomic functions, behavior, and cognition, most notably in the processing of emotions and feelings. In a study of 32 brains obtained from patients with Alzheimer's disease (AD), thioflavin S-stained sections from the PAG contained major pathological changes in 81% of cases. These changes were absent in all 26 control brains (13 from normal subjects and 13 from non-AD patients). In the AD cases, both sides of the PAG were affected symmetrically; in 72%, there were only senile plaques, but there were both senile plaques and neurofibrillary tangles in 9%. Using immunohistochemical methods with 10D5, ALZ-50, and AT8 antibodies, we also established the presence of beta-amyloid peptide and abnormally phosphorylated tau protein in the PAG. Furthermore, we found that the type and density of pathological changes were expressed differently in different PAG regions and correlated with gender and the duration of dementia. These findings constitute a first step in documenting the selective changes of PAG in AD. The compartmentalized pattern of AD changes in PAG also reveals for the first time the columnar organization of PAG in human subjects.
We evaluated the effect of low intensity-pulsed ultrasound stimulation on rat chondrocytes in vitro using two different 1.0-MHz ultrasound signals with spatial and temporal average intensities of 50 or 120 mW/cm2. The pulses had a duration of 200 microseconds and were repeated every millisecond, with corresponding average peak-pressure amplitudes of 230 or 360 kPa, respectively. Cells were stimulated one, three, or five times for 10 minutes each day starting the third day after plating. One group of cells was exposed to sham ultrasound as a control. The cultures were evaluated for cell proliferation (by [3H]thymidine incorporation and DNA measurement), steady-state mRNA levels of alpha1(I) and alpha1(II) procollagens and aggrecan (by Northern blotting), and proteoglycan synthesis (by [35S]sulfate incorporation). The results revealed that ultrasound causes increases in the level of aggrecan mRNA (p < 0.05) and in proteoglycan synthesis (p < 0.03) after three and five treatments. Expression of mRNA for alpha1(II) procollagen increased over time, but ultrasound had no stimulatory effect. Expression of mRNA for alpha1(I) procollagen was initially low and remained unchanged with time. Although cell proliferation increased with time in both groups, there was no statistically significant difference between the cultures treated with ultrasound and the controls (p = 0.1). The in vitro results support our previous in vivo findings that low-intensity ultrasound stimulates aggrecan mRNA expression and proteoglycan synthesis by chondrocytes, which may explain the role of ultrasound in advancing endochondral ossification, increasing the mechanical strength of fractures, and facilitating fracture repair.