Biomedical subjects

S Aunoble

Publications and source records attributed to S Aunoble.

9 recordsLinked to original sources

PubMed2006

Total disc arthroplasty: consequences for sagittal balance and lumbar spine movement.

This in vivo biomechanical study was undertaken to analyze the consequences for sagittal balance and lumbar spine movement in three different lumbar disc prostheses. A total of 105 patients underwent total disc replacement in three different centers. The Maverick prosthesis was used in 46 patients, the SB Charité device was used in 49 patients and the Prodisc device was utilized in 10 patients. The analysis was computer assisted, using Spineview and Matlab softwares. The intra and inter-observer reliability and measurement uncertainty was performed. The analysis of lateral X-ray films in flexion-extension allowed to measure the prosthesis positioning, the range of motion (ROM), the localization of the mean center of rotation (MCR), the vertebral translation and the disc height, for each prosthesis device. The sagittal balance was analyzed on a full spine film. The parameters studied were described by Duval-Beaupère. The results were compared to the data found in literature, and compared to 18 asymptomatic volunteers, and 61 asymptomatic subjects, concerning the sagittal balance. The prostheses allowed an improvement of the ROM of less than 2 degrees. The ROM of L5-S1 prostheses ranged from 11.6 to 15.6% of the total lumbar motion during flexion-extension. At L4-L5 level, the ROM decreased when there was an arthrodesis associated at the L5-S1 level. There was no difference of ROM between the three prostheses devices. The MCR was linked to the ROM, but did not depend on the prosthesis offcentering. The disc height improved for any prosthesis, and decreased in flexion or in extension, when the prosthesis was offcentered. An increase of translation indicated a minor increase of the ROM at L4-L5 level after Maverick or SB Charité implantation. The L5-S1 arthrodesis was linked with an increase of the pelvic tilt. The lumbar lordosis curvature increased between L4 and S1, even more when a prosthesis was placed at the L3-L4 level. Total disc arthroplasty is useful in the surgical management of discogenic spinal pathology. The three prostheses studied allowed to retorate the disc height, the ROM, without disrupting the sagittal balance, but induced modification of the lumbar curvature.

Arthroplasty, Replacement↗

PubMed2006

[Anatomic variations of the ilio-caval junction encountered in disk prosthesis implantation].

PURPOSE OF THE STUDY: The retroperitoneal mini-invasive anterior approach to the lumbar spine is widely used for disc excision and insertion of a prosthetic disc. A large operating window is needed. Venous wounds constitute one of the most serious complications. We analyzed the angle and position of the iliocaval on the preoperative angio-MRI in search for correlations with the intraoperative findings. Our aim was to determine whether the preoperative angio-MRI gives indications concerning the operative difficulty and the best strategy for prosthesis fitting. MATERIAL AND METHOD: This prospective study included 35 consecutive patients who underwent surgery for implantation of a Maverick disc prosthesis. Average patient age was 46.7 years. The indication for surgery was isolated degenerative discopathy with invalidating chronic low back pain without alteration of the muscle masse or facet joints. A preoperative angio-MRI was performed with T1 spin-echo sequences for the coronal slices and T2 axial slices passing through the upper extremity of the L5-S1 disc. We searched for correlations between the MRI and operative findings. Elements studied were those used in the Capellades classification: height of the iliocaval junction (high, very high, low, very low), position of the common iliac vein (lateral, intermediate, medial), angle formed by the two common iliac veins. RESULTS: The lateral position was the most frequent (31.5%). The average junction angle was 65 degrees). The only position where it was not possible to "pass" under the iliocaval junction was for a very low medial localization with a narrow angle (45 degrees). DISCUSSION: Our series included a homogenous group comparable with other series in the literature. The junction angle for very low medial localizations is of considerable importance because it is impossible to fit the implant in the L5-S1 under the iliocaval junction if the angle is over 60 degrees. CONCLUSION: The position of the iliocaval junction, and particularly its angle, are of considerable importance for insertion of an L5-S1 disc prosthesis. The preoperative angio-MRI provides information on the potential difficulty of the insertion. In addition, with this preoperative information, the patient can be warned that it may not be possible to insert the implant so that a therapeutic alternative may be proposed.

Adult↗

PubMed2006

[Evaluation of an articulated spacer for two-stage reimplantation for infected total knee arthroplasty: 28 cases].

PURPOSE OF THE STUDY: Two-stage reimplantation remains the most popular solution for infected total knee arthroplasty. We have used articulated spacers since their introduction in 2000. We evaluated tolerance, joint motion under general anesthesia before reimplantation and also the infectious and functional long-term outcome. MATERIAL AND METHODS: Between June 2000 and April 2003, we implanted an articulated spacer in 28 patients who required revision of their total knee arthroplasty. Postoperatively, contact weight bearing was allowed with unlimited knee motion depending on pain control. Mean time between implant removal and reimplantation was eight weeks (range 6-16 weeks). RESULTS: There was one dislocation due to excessive play between the two components. Passive joint motion before reimplantation was 53 degrees (range 5-80 degrees ). At last follow-up, 24 patients were free of overt infection and all antibiotic regimens had been discontinued for at least 20 months (20-48 months). Two patients required a second two stage revision. One had an arthrodesis and in one only suppressive antibiotic therapy was possible. DISCUSSION: Spacer removal appears easy at reimplantation. Good knee flexion (greater than 40 degrees in ten patients and greater than 60 degrees in eight) facilitated exposure, avoiding the need for tilting of the tibial tuberosity in seven patients. Functional and infectious outcomes were similar to those reported in the literature. CONCLUSION: The spacer appears to improve patient comfort between the two operations. It also facilitates the reimplantation procedure because of the easier exposure and greater knee flexion compared with a mono-bloc spacer or an external fixator. There must however be enough bone stock to hold the articulated spacer in place.

Arthroplasty, Replacement, Knee↗

PubMed2005

The effect of single-level, total disc arthroplasty on sagittal balance parameters: a prospective study.

A prospective radiographic study of the influence of total disc replacement on spinal sagittal balance. The goal of this study was to prospectively determine the effect of a single-level, total disc replacement on the sagittal balance of the spine, especially on sacral tilt (ST), pelvic tilt (PT), and lumbar lordosis. It has been shown that lumbar fusion may deleteriously alter the sagittal balance of the spine, including a decrease in the ST and lumbar lordosis. Clinically, postfusion pain has been shown to be significantly related to a decreased ST, increased PT, and decreased lumbar lordosis, independent of other factors such as pseudoarthrosis. To our knowledge, the influence of total disc replacement on spinal sagittal balance has not yet been reported in the literature. This is a prospective study of 35 patients who received a single level disc replacement using the Maverick Total Disc Arthroplasty system (Medtronic Sofamor Danek, Memphis, Tennessee) by a single surgeon at one institution from March 2002 to September 2003. The preoperative and postoperative radiographic evaluation included standing anteroposterior and lateral full spine films that included the femoral heads. The parameters studied were ST, PT, global and segmental lordosis, and global kyphosis. The average age of the 35 patients studied was 44.3 years (range 35-57). There were 18 females and 17 males. The disc arthroplasty was performed at the L4-L5 level in 19 patients and at the L5-S1 level in 16 patients. The average follow-up was 14 months (range 6-22 months). The preoperative values of global lordosis, ST, and PT were 51.5 degrees , 37.8 degrees , 16.9 degrees and, at last follow-up, they were 51.4 degrees , 37.4 degrees , and 17.5 degrees , respectively. These changes were not significantly different. When the groups were separated according to the level operated, there was still no statistical difference with regard to the overall lordosis, ST, PT or kyphosis from pre- to postoperative period or when the two groups were compared with each other. The level above the prosthesis has always significantly less lordosis. In the present study with use of a motion-preserving Maverick prosthesis, it appears that the patient is able to maintain the preoperative sagittal balance. The prosthesis has enough freedom of motion to allow the patient to maintain the natural sagittal and spinopelvic balance needed to prevent potential undue stress on the muscles and the sacroiliac joint. Although the number of patients is small, this is the first study to our knowledge that evaluates the sagittal balance after motion-preserving total disc arthroplasty.

Adult↗

PubMed2005

Clinical results of Maverick lumbar total disc replacement: two-year prospective follow-up.

Disc prosthesis is the new treatment for degenerative disc disease in the lumbar spine. Key to assessing the interest in this new motion technique is evaluating the results in terms of functional and radiologic outcomes. This prospective study reports the outcome of 64 Maverick devices implanted between January 2002 and November 2003. The degree of improvement was equivalent to that obtained with anterior fusion cages using the mini-invasive technique. Radiographic follow-up in this series showed a degree of mobility close to normal. The technique is safe because the intra- and postoperative complication rate is low. The Oswestry score improved for 75% of patients. This improvement is significantly correlated with facet arthrosis and muscle fatty degeneration.

Adult↗

PubMed2005

[Video-assisted mini-thoracotomy for surgical treatment of thoracolumbar junction fractures].

PURPOSE OF THE STUDY: There are several solutions for the treatment of fractures of the thoracolumbar junction (classical anterior, posterior, combined approaches). The advent of video-assisted minimally invasive techniques has helped minimize complications. The aim of this work was to analyze the clinical and radiological outcome in a prospective series of 20 patients who underwent video-assisted mini-thoracotomy for the treatment of thoracolumbar junction fractures. MATERIAL AND METHODS: This prospective study included 20 patients, mean age 43.3 years, with at least one year follow-up. All patients presented a normal neurological examination (Frankel E). Fractures were classified Magerl A (n = 19) and B (n = 1). Corporectomy/correction (aided with an endodistractor in the last nine cases) was performed with grafting and osteosynthesis. Perioperative and postoperative complications were noted. Focal kyphosis and regional angulation were noted before and after the operation and at last follow-up using the Stagnara system. RESULTS: The arthrodesis had fused at last follow-up in all patients. There were three cases of alelectasia which regressed in two months. Overall outcome showed satisfactory angular correction which was maintained at last follow-up. The gain in focal kyphosis was 13.71 degrees on average in the immediate postoperative period and persisted at last follow-up (13.31degrees). The gain in corrected regional angulation was 14 degrees in the immediate postoperative period and 14 degrees at last follow-up. The gain in focal kyphosis and regional angulation was two-fold greater with the endodistractor than with external maneuvers. DISCUSSION: The complication rate was very low. Corrections obtained were comparable with those reported in the literature and persisted over time. CONCLUSION: Bearing in mind the learning curve, there are fewer complications with the video-assisted minimally invasive approach than with classical thoracotomy or anterior surgery. This is true for perioperative and early and late postoperative complications. The correction achieved is satisfactory and lasting. A specific ancillary is essential for the reduction and for fitting the anterior graft without lost of correction. This technique combines the best results achieved with thoracotomy (Onimus) with a limited rate of complications.

Adolescent↗

PubMed2004

Dislocations with intervertebral disc prosthesis: two case reports.

To date, only three cases of artificial disc prosthesis dislocation have been reported in the literature. We present in detail two additional cases of prosthesis dislocation and discuss the surgical interventions undertaken that resulted in a good clinical outcome in both patients.

Adult↗

PubMed2003

Vertebroplasty for osteoporotic spine fracture: prevention and treatment.

There is a relatively high prevalence of osteoporotic vertebral compression fractures (VCFs) in the elderly population, especially in women aged 50 or older. The result of these VCFs is increased morbidity and mortality in the short and long term. Medical treatment of these fractures includes bed rest, orthotics, analgesic medication and time. Percutaneous vertebroplasty (PVP) consists of percutaneous injection of biomaterial, such as methylmethacrylate, into the VCF to produce stability and pain relief. Biomechanical testing has shown that PVP can restore strength and stiffness of the vertebral body to the pre-fracture levels. Clinical results show immediate and maintained pain relief in 70-95% of the patients. Possible major complications include cement leakage into the spinal canal or into the venous system. Additionally, percutaneous vertebroplasty may alter the normal loading behavior of the adjacent vertebral body, and there is an increased risk of adjacent segment VCF. Kyphoplasty is a new technique, which introduces a balloon into the vertebral body transpedicularly to reduce the VCF while creating a cavity for the cement injection. This technique has the benefit of kyphosis reduction as well as less cement leakage. Research continues into the development of injectable biomaterials that are resorbable and allow for new bone formation. Vertebroplasty and kyphoplasty are safe and effective in the treatment of osteoporotic VCFs. They may allow for a faster return to function, and thus avoid the morbidity associated with medical treatment.

Administration, Cutaneous↗

PubMed2001

Minimally invasive endoscopic approach to the cervicothoracic junction for vertebral metastases: report of two cases.

The anterior cervicothoracic junction is difficult to expose and many techniques have previously been described. Most of them require an extensile exposure, which can lead to significant morbidity. The aim of this study is to present a less invasive approach, allowing the same exposure on the spine as a larger one. The approach begins with the same incision as the Smith-Robinson technique: a blunt dissection of the posterior face of the manubrium is performed with the finger. An endoscope is inserted through 10-mm trocars, one above the manubrium and the second through the second rib space. The upper mediastinal space is exposed; the dissection is performed on the left side, between the esophagus and trachea medially, between the innominate vein and brachio-cephalic artery distally, and between the left common carotid and internal jugular vein laterally. The recurrent nerve must be protected. Two patients with spine metastases underwent this new approach. A strut graft was fixed anteriorly after decompression of the spinal cord. Levels T1-T3 can be well exposed through this approach, allowing complete vertebral body removal at level T1 or T2. After body removal, the posterior longitudinal ligament is well exposed, allowing complete release of the spinal cord. The use of the endoscope is the key to providing a good view of the spine without an extensile exposure. This new approach is technically feasible. The exposure is sufficient for vertebral body resection and reconstruction by strut graft. The procedure is less aggressive and painful than sternotomy.

Cervical Vertebrae↗