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The importance of complete screening for amyloid fibril type and systemic disease in patients with amyloidosis in the respiratory tract.

BACKGROUND: Patients with symptomatic thoracic involvement by amyloidosis are virtually all of AL-type, and have historically been divided into systemic and localised disease, a subdivision that helps predict outcome and aids management. Assessment and classification of amyloid has evolved in recent years to include a variety of tests, including radiolabelling of the serum amyloid P component (SAP scan) to assess anatomical distribution and immunohistochemical studies to assess fibril subtypes. Furthermore, CT scanning is now a frequent investigation for the diagnosis of thoracic disease. We wished to determine the value of these investigations on the management of such patients with amyloidosis. METHODS: Clinicopathological data, including immunohistochemical analysis, CT scans and SAP scan results, were retrospectively reviewed from patients presenting with amyloidosis in the respiratory tract. These were then analysed to determine their impact on classification and prognosis. RESULTS: Seventeen patients over ten years were identified, one case being related to metastatic medullary carcinoma of the thyroid. Of the remaining 16 cases, one was shown to have hereditary amyloid of transthyretin-type (TTR) on immunohistochemistry, altering management. The remaining 15 cases were AL-type, with 6 cases being classified as localised and 9 cases as systemic, after evaluation for serum and/or urine monoclonal products, cardiac involvement via echocardiography, plasma cell abnormalities on bone marrow examination, CT scan and SAP scan. 3/3 patients with localised AL-type disease had a negative SAP scan, whilst 3/5 patients with systemic AL-type disease had a positive scan. SAP scan of the patient with TTR-type disease provided information on extent of disease and supported the diagnosis by the pattern of distribution. Using CT scans to discriminate between localised and systemic disease showed a significant association with mortality at 2 years (p = 0.03). CONCLUSION: Although the majority of symptomatic patients with pulmonary amyloidosis have AL-type disease, immunohistochemical confirmation is necessary in order not to miss rarer subtypes with completely different treatment regimes. Furthermore, a comprehensive evaluation, including SAP scan and CT scan of the thorax, in conjunction with echocardiography, bone marrow, serum and urine studies, needs to be undertaken in order to achieve maximum accuracy with regard to localised and systemic disease.

Aged↗

Severe nonfluency in aphasia. Role of the medial subcallosal fasciculus and other white matter pathways in recovery of spontaneous speech.

The relationship between location and extent of lesion on CT scan and limitation in spontaneous speech was examined. The severity of spontaneous speech ranged from cases with no speech or only verbal stereotypies (first major group) to those with reduced, hesitant, poorly articulated, agrammatic speech (nonfluent Broca's aphasia, second major group). CT scan analysis revealed no single neuroanatomical area that contained an extensive lesion which could be used to discriminate the most severe cases from the least severe. The two groups were separable, however, on the basis of the CT scan when the extent of the lesion in two subcortical white matter areas were combined: (1) the most medial and rostral portion of the subcallosal fasciculus plus (2) the periventricular white matter near the body of the lateral ventricle, deep to the lower motor/sensory cortex area for the mouth. The most rostral portion of the medial subcallosal fasciculus, located in the lateral angle of the frontal horn (extremely deep to Broca's area), contains projections from the cingulate gyrus (area 24) and the supplementary motor area, to the caudate nucleus. We suggest that one explanation for the more severe limitation in spontaneous speech in the first group is the extensive white matter lesion in these two subcortical pathways had interrupted a large number of connections for (1) initiation and preparation of speech movements, and limbic aspects of speech (lesions in the medial subcallosal fasciculus), and (2) motor execution and sensory feedback for spontaneous speech (lesions in periventricular white matter deep to the motor/sensory cortex area for the mouth). Extensive lesion in only one of these two white matter pathway areas, alone was not sufficient to produce long-lasting severe limitation in spontaneous speech and could not be used to discriminate the two groups on the basis of the CT scans. The patients with less severe limitation in spontaneous speech (nonfluent Broca's aphasia) had less extensive lesion within these two white matter areas combined, and had interrupted a smaller number of these subcortical connections. The sites of the lesions in subcortical white matter in CT scans in Broca's original case who could only produce a verbal stereotypy are similar to those in our first group with the most severe limitation in spontaneous speech. The presence or absence of hemiplegia was not related to severity or recovery of spontaneous speech. Careful examination of lesion extent in these two areas of subcortical white matter on CT scanning appears to be relevant in predicting potential for recovery of spontaneous speech in some stroke patients.

Adult↗

Low-grade gliomas in children: tumor volume response to radiation.

Object. The authors conducted a retrospective review to examine and document the frequency, degree, and timing of the radiologically confirmed response to radiotherapy of low-grade gliomas in children. Methods. Between 1963 and 1995, 80 patients 17 years of age or younger were referred to the London Regional Cancer Centre in London, Ontario, after diagnosis of a low-grade glioma. All patients underwent surgical resection or biopsy procedures and 47 underwent radiotherapy (40 postoperatively and seven at the time of tumor progression). Nineteen patients with residual measurable lesions who received radiation therapy were selected for volumetric analysis of tumor response to this treatment. The extent and timing of response to radiation were determined by the process of comparing postoperative, preirradiation computerized tomography (CT) scans with postirradiation, follow-up CT scans. For one patient the comparison was made by using serial magnetic resonance images. Residual tumor was found on postoperative CT scans in all cases. The mean preradiotherapy tumor volume was 17.1 cm(3), and the postradiotherapy volume was reduced to a mean of 11.5 cm(3). A reduction in tumor was demonstrated in eight patients by the time of their first postirradiation follow-up CT scan and in two patients a slower reduction in volume over time was shown, bringing the total number of "responders" to 10. In five of these 10 patients the tumor had shown a maximum response by the time of the first postirradiation CT scan; the median time to response was 3.3 months. A 25% or greater reduction in tumor volume was seen in eight (42%) of the 19 patients. A 50% or greater reduction was noted in five (26%) of the patients. A complete response was demonstrated at 7, 12, and 15 months, and 5 years, respectively, in four patients (21%). One responder's tumor eventually increased in size after radiotherapy and he died of his disease. The magnitude of the radiographically demonstrated response to radiation did not correlate significantly with clinical outcome (that is, survival or symptom improvement). Conclusions. On the basis of this CT scan analysis of the response of low-grade gliomas in children to radiotherapy, the authors suggest that these lesions respond to radiation, as demonstrated by tumor shrinkage on serial imaging. Major or complete responses occur occasionally. However, low-grade gliomas in children mimic other benign brain tumors such as pituitary adenomas and meningiomas in that, although growth is frequently arrested after radiotherapy, residual tumor can persist for many years, illustrating that tumor shrinkage may not be a good measure of treatment efficacy. Nevertheless, radiation therapy can result in improvement of clinical symptomatology in association with or independent of visible tumor reduction. As radiation treatment techniques become increasingly conformal and because studies indicate that lower doses of radiation may be equally effective, improvement of symptoms may be an important consideration when weighing treatment options, particularly in patients with residual or unresectable disease.

Journal Article↗

Low-grade gliomas in children: tumor volume response to radiation.

OBJECT: The authors conducted a retrospective review to examine and document the frequency, degree, and timing of the radiologically confirmed response to radiotherapy of low-grade gliomas in children. METHODS: Between 1963 and 1995, 80 patients 17 years of age or younger were referred to the London Regional Cancer Centre in London, Ontario after diagnosis of a low-grade glioma. All patients underwent surgical resection or biopsy procedures and 47 underwent radiotherapy (40 postoperatively and seven at the time of tumor progression). Nineteen patients with residual measurable lesions who received radiation therapy were selected for volumetric analysis of tumor response to this treatment. The extent and timing of response to radiation were determined by the process of comparing postoperative, preirradiation computerized tomography (CT) scans with postirradiation, follow-up CT scans. For one patient the comparison was made by using serial magnetic resonance images. Residual tumor was found on postoperative CT scans in all cases. The mean preradiotherapy tumor volume was 17.1 cm3, and the postradiotherapy volume was reduced to a mean of 11.5 cm3. A reduction in tumor volume was demonstrated in eight patients by the time of their first postirradiation follow-up CT scan and in two patients a slower reduction in volume over time was shown, bringing the total number of "responders" to 10. In five of these 10 patients the tumor had shown a maximum response by the time of the first postirradiation CT scan; the median time to response was 3.3 months. A 25% or greater reduction in tumor volume was seen in eight (42%) of the 19 patients. A 50% or greater reduction was noted in five (26%) of the patients. A complete response was demonstrated at 7, 12, and 15 months, and 5 years, respectively, in four patients (21%). One responder's tumor eventually increased in size after radiotherapy and he died of his disease. The magnitude of the radiographically demonstrated response to radiation did not correlate significantly with clinical outcome (that is, survival or symptom improvement). CONCLUSIONS: On the basis of this CT scan analysis of the response of low-grade gliomas in children to radiotherapy, the authors suggest that these lesions respond to radiation, as demonstrated by tumor shrinkage on serial imaging. Major or complete responses occur occasionally. However, low-grade gliomas in children mimic other benign brain tumors such as pituitary adenomas and meningiomas in that, although growth is frequently arrested after radiotherapy, residual tumor can persist for many years, illustrating that tumor shrinkage may not be a good measure of treatment efficacy. Nevertheless, radiation therapy can result in improvement of clinical symptomatology in association with or independent of visible tumor reduction. As radiation treatment techniques become increasingly conformal and because studies indicate that lower doses of radiation may be equally effective, improvement of symptoms may be an important consideration when weighing treatment options, particularly in patients with residual or unresectable disease.

Adolescent↗

Symptomatological characteristics distinguish between frontotemporal dementia and vascular dementia with a dominant frontal lobe syndrome.

OBJECTIVE: Our hypothesis was that patients with vascular dementia and a dominating frontal lobe syndrome have a symptomatology that reflects a more widespread lesion compared with patients with frontotemporal dementia. DESIGN: Patients with vascular dementia and a dominating frontal lobe syndrome (VAD-F; N = 11) were compared with regard to clinical symptoms and imaging features on CT scans of the brain with patients with frontotemporal dementia (FTD; N = 21). SETTING: A neuropsychiatric diagnostic ward. PATIENTS: Thirty-two inpatients, aged 48-78 years, with frontotemporal dementia or vascular dementia. MEASURES: Relatives were questioned about the initial symptoms. At the clinical investigation, mental and neurological symptoms and signs were recorded using the STEP method (stepwise comparative status analysis). CT scan features of the brain were evaluated by a trained neuroradiologist. The GBS-i (Gottfries-Bråne-Steen, intellectual variables) scale was used to measure the degree of dementia. RESULTS: At the onset of dementia, loss of memory (p < 0.001), sudden onset (p < 0.001), confusion (p < 0.05) and unspecified neurological signs (p < 0.05) had been significantly more frequent in the VAD-F group. At the time of the clinical investigation, lack of social awareness and presence of primitive reflexes were more frequent in the FTD group (p < 0.01 and p < 0.05, respectively) and visuospatial deficits more frequent in the VAD-F group (p < 0.05). CT of the brain showed that, apart from brain infarcts (present only in the VAD-F group), paraventricular leukoaraiosis was significantly more pronounced in the VAD-F group (p < 0.05). The groups did not differ with respect to age, age at onset or level of dementia. CONCLUSION: The findings support our hypothesis.

Age of Onset↗

Radiologic and pathologic characteristics of mixed dust pneumoconiosis.

Modern radiologic technology has to led to increased diagnostic efficacy and accuracy in demonstrating pulmonary changes secondary to occupational dust exposure. This article presents three cases of typical and two cases of atypical silicosis with rounded atelectasis as seen in computed radiographic (CR), computed tomographic (CT), and scintigraphic images and autopsied lung specimens. Chest radiographs revealed both small rounded and small irregular opacities. Small irregular opacities on chest radiographs often proved to be reticular or honeycomb patterns on CT scans. Irregular opacities seen on CR and CT images represented interstitial fibrotic or mixed dust fibrotic changes associated with the accumulation of birefringent particles and emphysematous change, as noted at histologic analysis. CT scans and scintigrams were useful for visualizing parenchymal abnormalities, especially fibrotic change, emphysematous change, and pleural abnormalities.

Aged↗

B-scan ultrasonography in Graves' orbitopathy.

Diagnosing and monitoring of Graves' Orbitopathy (GO) can be supported by use of Ultrasonography (USG) and Computerized Tomography (CT); they provide supplementary information. In this retrospective study we describe 107 clinical GO patients evaluated by B-scan USG and 27 clinical GO patients evaluated by CT scan. Analysis of 236 B-scan USG included measurements of medial, inferior and lateral rectus muscles. The presence of muscle enlargement and increased orbital fat were noted by the radiologist on 27 CT scans. Sensitivity of both B-scan USG and CT scan were calculated. We suggest that B-scan USG has a high sensitivity, which is equal or better than CT scan sensitivity in diagnosing GO. Furthermore USG A and B scan combination is an effective, accurate tool in diagnosing GO, and optic neuropathy, but it also provides essential information about the GO disease activity.

Female↗

Allosaurus, crocodiles, and birds: evolutionary clues from spiral computed tomography of an endocast.

Because the brain does not usually leave direct evidence of its existence in the fossil record, our view of this structure in extinct species has relied upon inferences drawn from comparisons between parts of the skeleton that do fossilize or with modern-day relatives that survived extinction. However, soft-tissue structure preservation may indeed occasionally occur, particularly in the endocranial space. By applying modern imaging and analysis methods to such natural cranial "endocasts," we can now learn more than ever thought possible about the brains of extinct species. I will discuss one such example in which spiral computed tomography (CT) scanning analysis has been successfully applied to reveal preserved internal structures of a naturally occurring endocranial cast of Allosaurus fragilis, the dominant carnivorous dinosaur of the late Jurassic period. The ability to directly examine the neuroanatomy of an extinct dinosaur, whose modern-day relatives are birds and crocodiles, has exciting implications about Allosaurus' behavior, its adaptive responses to its environment, and its eventual extinction.

Alligators and Crocodiles↗

Preoperative grading of glioma malignancy with thallium-201 single-photon emission CT: comparison with conventional CT.

PURPOSE: To compare thallium-201 single-photon emission CT with conventional CT in grading the malignancy of gliomas and to determine the reliability of each in tumor assessment. METHODS: We studied 37 patients who had gliomas (31 high grade and 6 low grade) and compared the CT findings with the thallium-201 index, which we defined as tumor uptake relative to the uptake in the contralateral hemisphere. RESULTS: Among the high-grade gliomas, we observed a significant correlation between breakdown volume of the blood-brain barrier and thallium-201 uptake. However, 8 of the high-grade gliomas had low thallium-201 uptake, in the same range as the low-grade gliomas. Of these, 2 were nonenhancing and the other 6 showed ring enhancement on CT scans. Analysis of variance showed no significant difference in thallium-201 indexes between low-grade gliomas and highly malignant (grade II-III) gliomas. Accuracy of thallium-201 imaging was lower (78%) than that of CT (84%) in identifying high-grade gliomas. CONCLUSIONS: Damage to the blood-brain barrier is a prerequisite for uptake of thallium-201 in gliomas. Tumors with central necrotic areas and moderate ring enhancement tend to be underestimated when evaluated by means of thallium-201 scintigraphy. The results indicate a need for caution when interpreting findings on images obtained with thallium-201 single-photon emission CT in preoperative evaluation of brain tumors.

Adolescent↗

[Endovascular treatment of isthmic aortic rupture: use of second generation stent grafts].

OBJECTIVE: Prospective analysis of endovascular management of traumatic isthmic rupture with second generation stent grafts. STUDY DESIGN: Prospective analysis and follow-up. PATIENTS: Ten consecutive multiple injured patients presenting an acute isthmic traumatic rupture who underwent an endovascular repair with second generation stent grafts. METHODS AND RESULTS: The aortic injury was diagnosed by spiral computed tomography scan. The appropriate time to repair was decided according to multidisciplinary decision after analysis of associated injuries status and mediastinal lesions evolution. Endovascular repair was successfully completed in all patients under general anaesthesia without requirement of haemodynamic manipulations. Despite a prolonged length of stay related to associated injuries, all patients were discharged from hospital without migration of devices or complication related to the endovascular procedure. After a 20 months follow-up (range 6 - 38 months), all patients were alive with a satisfactory CT scan analysis. CONCLUSION: The immediate availability of the second generation of stents-grafts allowed the endovascular treatment of isthmic rupture without haemodynamic manipulations or massive heparinization. The analysis of this selected series reinforces the interest of this non-invasive technique for anaesthetists especially in polytraumatized patients.

Adult↗

Endoscopic and CT-scan evaluation of rhinosinusitis in cystic fibrosis.

In order to obtain an accurate evaluation of nasal and paranasal sinus disease in cystic fibrosis patients, 75 patients with a proven cystic fibrosis diagnosis have been investigated using the following standard techniques: questionnaire, ENT examination, endoscopical examination, sinus X-rays, and in 31% of the cases a CT scan. The analysis of results shows that nasal obstruction is the most frequent symptom (32%) and that nasal polyps are present in 43% of the cases. Endoscopic examination seems to be of great interest in giving a more accurate picture of nasal and paranasal sinus disease. Analysis of CT scan images leads the authors to describe a new and specific entity in nasal and paranasal sinus disease in cystic fibrosis patients: the pseudomucocele. In this report, the authors discuss the various aspects of pseudomucocele, attaching particular importance to the CT scan results.

Adolescent↗

High resolution CT scan of temporal bone fractures: association of facial nerve paralysis with temporal bone fractures.

This radiologic study analyzed high resolution computed tomographic (CT) scans of 22 patients with temporal bone fractures. There were 19 males and three females. Fifteen of 22 had clinical evidence of facial nerve injury ranging from mild paresis to complete paralysis. The high resolution CT scan analysis identified a characteristic fracture of the temporal bone in every patient with facial nerve injury. A high percentage of these fractures (68%) could be classified as mixed and did not fall into a longitudinal or transverse fracture category. The characteristic fracture extends from the petrotympanic fissure at the glenoid fossa to the anterior inferior aspect of the medial bony external auditory canal. It resumes at the superior aspect of the external auditory canal (scutum) extending laterally along the external canal wall. If the vector force of the fracture is projected medially, it will cross the facial nerve in its horizontal portion. Often, the evaluation of trauma patients with routine CT scans for central nervous system (CNS) (brain) evaluation is inadequate for evaluation of temporal bone fractures. A high resolution CT scan should be performed when clinical criteria warrant its use. It is recognized that the incidence of facial nerve injury may be higher in this select population.

Adolescent↗

Posterior maxillary anatomy: implications for Le Fort I osteotomy.

The most common site of haemorrhage in maxillary osteotomies is the posterior maxilla. Better understanding of the anatomy in this region may minimize possible vascular complications. The aim of the study was to study the osteology of the posterior maxillary region and establish clinical safety guidelines for the Le Fort I osteotomy Thirty human dry skulls were selected and assessed by a combination of direct inspection, computerized imaging and computed tomography (CT) scan analysis. Results showed that the presence of maxillary third molars influenced the transverse angulation of the posterior vertical cut. Synostosis of the pterygomaxillary junction was noted in 12% of samples. The mean length of the medial sinus wall from the piriform rim to the descending palatine canal at the Le Fort I level was 34 mm. The three-dimensional CT-reconstructed descending palatine canal ran at 60 degrees anteroinferiorly to the palatine plane and slightly medially to the exit through the greater palatine foramen.

Adult↗

CT scan modification in the treatment of mediastinal Hodgkin's disease.

Seventy-one patients with Hodgkin's disease who were initially treated at Johns Hopkins with radiation or radiation-chemotherapy from 1975--1980 had a five-year cumulative disease-free survival of I-A--100% (12 patients); II-A--85% (33 patients); II-B--83% (seven patients); III-A--75% (ten patients); and III-B--66% (nine patients). Fifty patients with mediastinal masses at the time of treatment demonstrated no marginal misses, two mediastinal recurrences (96% local control), and three lung disseminations. CT scan data yielded stage and treatment modification in 60% (9/15) of recent patients with mediastinal Hodgkin's disease. This demonstrates the need for routine thoracic scans and individual treatment planning in all mediastinal cases. Recommendations for combination treatment in early stage disease are made only for pericardial or extrathoracic chest wall extension based on CT scan findings, our low failure rates, radiation organ tolerances, and available relapse data in the literature, not arbitrary size designations from upright chest radiographs. It can be concluded that patients with mediastinal Hodgkin's disease require CT scan analysis to identify unusual patterns of presentations, sites at risk, and to allow for proper application of radiation portals and/or chemotherapeutic management.

Drug Therapy, Combination↗

A SPECT study of wandering behavior in Alzheimer's disease.

BACKGROUND: Among behavior disturbance during Alzheimer's disease (AD), wandering is one of the most common. Different psychological processes have been suggested to explain the wandering behavior. The aim of this study was to examine whether wandering during AD was associated with cerebral perfusion patterns measured by (99 m)Tc-labeled bicisate (ECD) brain SPECT. METHODS: We compared SPECT scans of 13 AD subjects with wandering behavior (sex ratio M/F, 4/9; age, 73.1 years, SD 7.4; Mini Mental Status Examination score, median 20 interquartile range [16-23]), 13 AD subjects without wandering behavior (matched for age [ +/- 2 years], sex and MMSE score [ +/- 2 points]) and 13 healthy controls (matched for age [ +/- 2 years] and sex) without cognitive impairment. Wandering was defined on the Neuro-Psychiatric Inventory. Score of leukoaraiosis, assessed with the scale of Blennow and number of lacuna infarction were compared on CT scan. SPECT imaging was compared using statistical parametric mapping (SPM 2). RESULTS: There were no significant differences between the groups in term of educational level and CT scan analysis. SPECT imaging was consistent with the diagnosis of AD in both wanderers and AD subjects without wandering behavior. Despite similar clinical dementia severity, wanderers had more severely reduced regional cerebral blood flow (rCBF) in the left parietal-temporal lobe than AD subjects without wandering behavior. CONCLUSION: Wandering behavior could be facilitated by a specific patterns of cerebral blood flow. Wandering, as a physical activity, could also enhance the recruitment of the cortical network.

Aged↗

Adenocarcinoma of the ethmoid sinus.

BACKGROUND: Carcinoma of the paranasal sinuses is rare. The majority of these originate in the maxillary sinus with primary ethmoid carcinomas occurring in up to 20% of cases. Adenocarcinomas comprise up to 50% of the ethmoid malignancy. The relative rarity of tumors originating in this area has led to their inclusion in series that consist mainly of maxillary antral tumors. METHODS: A retrospective chart review of all patients presenting with primary ethmoid adenocarcinoma at West Virginia University Hospitals between 1988 and 1993 was undertaken. Only patients whose epicenter was believed to be in the ethmoids were included in this analysis. CT scans, MRIs, operative notes, pathology, and final outcome were all analyzed. RESULTS: Eight patients with primary ethmoid adenocarcinoma were treated during this time span. The male to female ratio was 1:1 with a mean age of 50 years. Symptoms had been present from 3 to 18 months (mean 8 months). All patients underwent craniofacial resection with 5 patients receiving postoperative radiotherapy. Pathologically 4 patients had cribriform plate erosion, 2 had dural involvement, and 1 had extension into the sphenoid sinus. With a mean follow-up of 45 months (9-71 months) 7 patients are disease free and 1 patient has died of disease. CONCLUSIONS: Obtaining clear margins by craniofacial resection is essential to the management of adenocarcinoma of the ethmoid sinuses. Radiotherapy is reserved for positive margins, cribriform plate penetration, dural invasion, and high-grade lesions that are close to the cribriform plate. Local control was obtained in 87% of our patients.

Adenocarcinoma↗

Blood monoamine oxidases and CT scans in subgroups of chronic schizophrenics.

An assay method for monoamine oxidase (MAO) employing whole blood samples is described. With this method, whole blood samples collected from three subgroups of chronic schizophrenic patients were assayed directly for MAOb activity without the need for prior isolation of platelets. Our results support previous findings from assays with platelets that chronic paranoid schizophrenics have decreased blood MAOb activity compared to chronic non-paranoid schizophrenics or normal controls. The level of MAOb activity in the blood of the non-paranoid schizophrenics was also linearly correlated with ventricular size (i.e. ventricular brain ratio, VBR) as determined by CT scan analysis. This correlation was not true for the paranoid group. The MAOb data in conjunction with the VBR data were sufficient to divide without overlap our schizophrenic patient population into two clinically defined subgroups.

Adult↗

Differences between extramedullary, intramedullary, and computer-aided surgery tibial alignment techniques for total knee arthroplasty.

Traditionally, intramedullary and extramedullary tibial alignment techniques are used to obtain neutral alignment during total knee arthroplasty. Computer-assisted techniques are available to aid in obtaining alignment intraoperatively. This study analyzed the difference in tibial alignment using intramedullary and extramedullary techniques, and compared them to the resulting tibial axis as determined by a computer navigation system. The tibial alignment standard measure was determined by a spiral computed tomography (CT) study of each lower extremity. Intramedullary techniques resulted in a 1.3 degrees +/- 1.4 degrees of varus alignment and 4 degrees +/- 2.1 degrees increase in posterior slope while the extramedullary techniques resulted in 1.5 +/-1.8 degrees of valgus alignment and 1.8 degrees +/-1.1 degrees increase in posterior slope compared to the navigation system alignment. Direct measurement of metal markers on CT-scan analysis using the navigation system resulted in <0.5 degrees difference from the navigation data. Although the traditional alignment techniques are within a few degrees, the addition of the errors in all planes gives a much higher degree of error. Direct measurement of the mechanical axis using computer-guided surgical techniques for the tibia give a greater degree of accuracy compared to traditional alignment techniques.

Arthroplasty, Replacement, Knee↗