Total knee arthroplasty implanted with and without kinematic navigation.
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Between September 2000 and February 2002 we inserted 120 total knee arthroplasties. In 60 patients we used the standard technique, and in 60 patients we used the OrthoPilot navigation system. Postoperatively all patients had standing long radiographs of the lower extremity from the hip joint to the ankle. We considered the ideal value of the anatomic lateral tibiofemoral angle (LTFA) to be 174 degrees. In the standard group the mean value of LTFA was 174.9 degrees and in the navigation group 174.3 degrees. A deviation between 0 degrees and 2 degrees from the ideal value was seen in 42 cases in the standard group and in 53 cases in the navigation group. In the standard group 18 cases had a deviation of more than 2.1 degrees, whereas there were only seven cases in the navigation group with a deviation exceeding 2.1 degrees. There were no complications related to the use of the navigation system. The system affords a possibility to place femoral and tibial components precisely with less axis deviation than with the conventional technique. (+info)
Preoperative localization and radioguided parathyroid surgery.
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Clinical or subclinical hyperparathyroidism is one of the most common endocrine disorders. Excessive secretion of parathyroid hormone is most frequently caused by an adenoma of >or=1 parathyroid gland. Unsuccessful surgery with persistent hyperparathyroidism, due to inadequate preoperative or intraoperative localization, may be observed in about 10% of patients. The conventional surgical approach is bilateral neck exploration, whereas minimally invasive parathyroidectomy (MIP) has been made possible by the introduction of (99m)Tc-sestamibi scintigraphy for preoperative localization of parathyroid adenomas. In MIP, the incision is small, dissection is minimal, postoperative pain is less, and hospital stay is shorter. Localization imaging techniques include ultrasonography, CT, MRI, and scintigraphy. Parathyroid scintigraphy with (99m)Tc-sestamibi is based on longer retention of the tracer in parathyroid than in thyroid tissue. Because of the frequent association of parathyroid adenomas with nodular goiter, the optimal imaging combination is (99m)Tc-sestamibi scintigraphy and ultrasonography. Different protocols are used for (99m)Tc-sestamibi parathyroid scintigraphy, depending on the institutional logistics and experience (classical dual-phase scintigraphy, various subtraction techniques in combination with radioiodine or (99m)Tc-pertechnetate). MIP is greatly aided by intraoperative guidance with a gamma-probe, based on in vivo radioactivity counting after injection of (99m)Tc-sestamibi. Different protocols used for gamma-probe-guided MIP are based on different timing and doses of tracer injected. Gamma-probe-guided MIP is a very attractive surgical approach to treat patients with primary hyperparathyroidism due to a solitary parathyroid adenoma. The procedure is technically easy, safe, with a low morbidity rate, and has better cosmetic results and lower overall cost than conventional bilateral neck exploration. Specific guidelines should be followed when selecting patients for gamma-probe-guided MIP. (+info)
Anatomic stereotactic catheter ablation on three-dimensional magnetic resonance images in real time.
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BACKGROUND: Targets for radiofrequency (RF) ablation of atrial fibrillation, atrial flutter, and nonidiopathic ventricular tachycardia are increasingly being selected on the basis of anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures and is associated with radiation risk, other approaches to mapping may be beneficial. METHODS AND RESULTS: An electromagnetic catheter positioning system was superimposed on 3D MR images using fiducial markers. This allowed the dynamic display of the catheter position on the true anatomy of previously acquired MR images in real time. In vitro accuracy and precision during catheter navigation were assessed in a phantom model and were 1.11+/-0.06 and 0.30+/-0.07 mm (mean+/-SEM), respectively. Left and right heart catheterization was performed in 7 swine without the use of fluoroscopy, yielding an in vivo accuracy and precision of 2.74+/-0.52 and 1.97+/-0.44 mm, respectively. To assess the reproducibility of RF ablation, RF lesions were created repeatedly at the identical anatomic site in the right atrium (n=8 swine). Average distance of the repeated right atrial ablations was 3.92+/-0.5 mm. Straight 3-point lines were created in the right and left ventricles to determine the ability to facilitate complex ablation procedures (n=6 swine). The ventricular lesions deviated 1.70+/-0.24 mm from a straight line, and the point distance differed by 2.25+/-0.63 mm from the pathological specimen. CONCLUSIONS: Real-time display of the catheter position on 3D MRI allows accurate and precise RF ablation guided by the true anatomy. This may facilitate anatomically based ablation procedures in, for instance, atrial fibrillation or nonidiopathic ventricular tachycardia and decrease radiation times. (+info)
Intraoperative ultrasonographically guided excisional biopsy or vacuum-assisted core needle biopsy for nonpalpable breast lesions.
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OBJECTIVE: To compare duration and rates of underestimation and complete excision for nonpalpable breast lesions using either intraoperative ultrasonographically guided excisioned biopsy (IUGE) or directional vacuum-assisted biopsy (DVAB). SUMMARY BACKGROUND DATA: Percutaneous ultrasonography-guided core needle biopsy is preferable to stereotactic biopsy for treatment of nonpalpable breast lesions; however, underestimation and false-negative results can occur, and rebiopsy may be required. To date, however, there has been no comparison of these two procedures in terms of diagnostic accuracy and duration. METHODS: For 4 consecutive years, IUGE was performed for 104 nonpalpable breast lesions and DVAB for 128 lesions at Chang Gung Memorial Hospital. Of the DVAB cases, the handheld mammotome was used for 53 procedures, with all lesions removed as completely as possible. The duration of the two procedures was calculated from initial skin incision until completion of wound closure. Most of the patients with benign pathology underwent ultrasonographic examination at 3 months after surgery, with a follow-up examination at 1 year. Surgery was performed subsequently for all of the malignancy cases. RESULTS: The average ages and mean tumor sizes for patients undergoing IUGE or DVAB were 46 and 47 years and 1.1 and 1.0 cm, respectively. The average IUGE and DVAB surgery durations for 88 benign tumors and 117 benign lesions were 44.3 and 21.5 minutes, respectively (P < 0.001), and 43.5 and 20.6 minutes for the malignant tumors (n = 16 and n = 11), respectively (P = 0.036). The IUGE and DVAB surgery durations for tumors <1 cm in diameter were 43.5 and 20.6 minutes, respectively, and 44.2 and 23.6 minutes for tumors over that size (P < 0.001). An older-model mammotome was used for 75 patients, with an average duration of 24 minutes in comparison to 18 minutes for the handheld variant (P < 0.001). No false-negative results were noted and, except in the case of the malignant tumors, there was no need for reexcisional biopsy. Further, there were no underestimates of the disease for the 4 cases of atypical ductal hyperplasia and the 12 of noninvasive carcinoma. No further ultrasonographic evidence of tumors was noted for 95% of the benign pathologies, with no residual abnormality detected for 13 of the 27 malignant tumors after IUGE or DVAB. CONCLUSIONS: For treatment of nonpalpable breast lesions, both IUGE and DVAB eliminate false-negative results, underestimates, and the requirement for reexcisional biopsies. In comparison to IUGE, DVAB is more convenient and time efficient for excisional biopsy of nonpalpable breast lesions. (+info)
Refractory occipital neuralgia: preoperative assessment with CT-guided nerve block prior to dorsal cervical rhizotomy.
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BACKGROUND AND PURPOSE: Occipital neuralgia syndrome can cause severe refractory headaches. In a small percentage of people, these headaches can be devastating and debilitating, with the potential for complete relief following surgical rhizotomy. We describe CT fluoroscopy-guided percutaneous C2-C3 nerve block for the confirmation of diagnosis of occipital neuralgia and for demonstrating to patients the sensory effects of intradural cervical dorsal rhizotomy before the definitive surgical procedure. METHODS: Seventeen patients with occipital neuralgia underwent 32 CT fluoroscopy-guided C2 or C2 and C3 nerve root blocks. Of the 17 patients, nine had occipital neuralgia following prior neck or skull base surgeries. On the basis of the positive results of the nerve blocks in terms of temporary pain relief, all 17 patients underwent unilateral (n = 16) or bilateral (n = 1) intradural C1 (n = 9), C2 (n = 17), C3 (n = 17), or C4 (n = 7) dorsal rhizotomies. All patients were followed up for a mean of 20 months (range, 5-37 months) for assessment of pain relief. Sixteen patients were assessed for degree of satisfaction with and functional state after surgery. RESULTS: All patients had temporary relief of symptoms after percutaneous CT-guided block (positive result) and felt that occipital numbness was an acceptable alternative to pain. Immediately after surgery, all patients had complete relief from pain. At follow-up, 11 patients (64.7%) had complete relief of symptoms, two (11.8%) had partial relief, and four (23.5%) had no relief. Seven of eight (87.5%) patients without prior surgery had complete relief of symptoms and one (12.5%) patient had partial relief, as opposed to complete relief in four of nine (44.4%), partial relief in one of nine (11.2%), and no relief in four of nine (44.4%) patients with a history of prior surgery. Because of the small number of patients, this difference was not statistically significant (P =.110). Eleven of 16 (68.8%) patients stated that the surgery was worthwhile. Eight of 16 (50%) patients felt they were more active and functional after surgery, whereas 25% felt they were either unchanged or less functional than before surgery. None of the patients without a history of prior surgery reported a decreased sense of functional activity following rhizotomy. CONCLUSION: CT fluoroscopy-guided percutaneous cervical nerve block is useful for the confirmation of occipital neuralgia, for demonstrating to patients the sensory effects of nerve sectioning, and possibly as a guide for selection of patients for intradural cervical dorsal rhizotomy. Although not statistically significant, there was a trend toward better response to rhizotomy in patients without prior head or neck surgery. (+info)
CT-guided percutaneous biopsy of thoracic and lumbar spine: A new coaxial technique.
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Herein we describe the technique of CT-guided lumbar or thoracic bone biopsy performed with a larger bore needle and coaxial system. The use of the external sheath cannula as a coaxial system led to an accurate diagnosis in all 19 patients who underwent the procedure. Bleeding at the biopsy site occurred in two patients and was controlled by insertion of Gelfoam. No other complications were encountered. We suggest that our procedure is more effective, reliable, safe, and rapid than the traditional technique. (+info)
Computer-assisted posterior instrumentation of the cervical and cervico-thoracic spine.
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Posterior instrumentation of the cervical spine has become increasingly popular in recent years. Dissatisfaction with lateral mass fixation, especially at the cervico-thoracic junction, has led spine surgeons to use pedicle screws. The improved biomechanical stability of pedicle screws and transarticular C1/2 screws allows for shorter instrumentations and improves the repositioning possibilities. Nevertheless, there are potential risks of iatrogenic damage to the spinal cord, nerve roots or the vertebral artery with both techniques. Therefore, the aim of this study was to evaluate whether C1/2 transarticular screws and transpedicular screws can be applied safely and with high accuracy in the cervical spine and the cervico-thoracic junction using a computer-assisted surgery system (CAS system). Posterior instrumentation was performed using the Brainlab VectorVision System (BrainLAB, Heimstetten, Germany) in 19 patients. Surface matching was used for registration. We placed 22 transarticular screws C1/2, 31 cervical pedicle screws, 10 high thoracic pedicle screws and one lateral mass screw C1. The screw position was evaluated postoperatively using CT with multiplanar reconstruction in the screw axis of each screw. None of the transarticular screws or pedicle screws was significantly (>2 mm) misplaced and no screw-related injury to vascular, neurogenic or bony structures was observed. No screw revision was necessary. The mean operation time was 144 min (90-240 min) and the mean blood loss was 234 ml (50-800 ml). C1/2 transarticular screws, as well as transpedicular screws in the cervical spine and the cervico-thoracic junction, can be applied safely and with high accuracy using a CAS system. Computer-assisted instrumentation is recommended especially for pedicle screws at C3-C6. (+info)
Intraoperative MRI in neurosurgery: technical overkill or the future of brain surgery?
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The development of image-guided neurosurgery represents a substantial improvement in the microsurgical treatment of tumors, vascular malformations and other intracranial lesions. Despite the wide applicability and many fascinating aspects of image-guided navigation systems, a major drawback of this technology is they use images, mainly MRI pictures, acquired preoperatively, on which the planning of the operative procedure as well as its intraoperative performance is based. As dynamic changes of the intracranial contents regularly occur during the surgical procedure, the surgeon is faced with a continuously changing intraoperative field. Only intraoperatively acquired images will provide the neurosurgeon with the information he needs to perform real intraoperative image-guided surgery. A number of tools have been developed in recent years, like intraoperative ultrasound and dedicated moveable intraoperative CT units. Because of its excellent imaging qualities, combined with the avoidance of ionizing radiation, MRI currently is and definitely will be in the future for the superior imaging method for intraoperative image guidance. In this short overview, the development as well as some of the current and possible future applications of MRI-guided neurosurgery is outlined. (+info)