| 1. |
- Ghandour, Salim, et al.
(författare)
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An ex-vivo model for the biomechanical assessment of cement discoplasty
- 2022
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Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media S.A.. - 2296-4185. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Percutaneous Cement Discoplasty (PCD) is a surgical technique developed to relieve pain in patients with advanced degenerative disc disease characterized by a vacuum phenomenon. It has been hypothesized that injecting bone cement into the disc improves the overall stability of the spinal segment. However, there is limited knowledge on the biomechanics of the spine postoperatively and a lack of models to assess the effect of PCD ex-vivo. This study aimed to develop a biomechanical model to study PCD in a repeatable and clinically relevant manner. Eleven ovine functional spinal units were dissected and tested under compression in three conditions: healthy, injured and treated. Injury was induced by a papain buffer and the treatment was conducted using PMMA cement. Each sample was scanned with micro-computed tomography (CT) and segmented for the three conditions. Similar cement volumes (in %) were injected in the ovine samples compared to volumes measured on clinical PCD CT images. Anterior and posterior disc heights decreased on average by 22.5% and 23.9% after injury. After treatment, the anterior and posterior disc height was restored on average to 98.5% and 83.6%, respectively, of their original healthy height. Compression testing showed a similar stiffness behavior between samples in the same group. A decrease of 51.5% in segment stiffness was found after injury, as expected. The following PCD treatment was found to result in a restoration of stiffness—showing only a difference of 5% in comparison to the uninjured state. The developed ex-vivo model gave an adequate representation of the clinical vacuum phenomena in terms of volume, and a repeatable mechanical response between samples. Discoplasty treatment was found to give a restoration in stiffness after injury. The data presented confirm the effectiveness of the PCD procedure in terms of restoration of axial stiffness in the spinal segment. The model can be used in the future to test more complex loading scenarios, novel materials, and different surgical techniques.
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| 2. |
- Karlsson, Thomas, et al.
(författare)
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Decompression alone or decompression with fusion for lumbar spinal stenosis : a randomized clinical trial with two-year MRI follow-up
- 2022
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Ingår i: The Bone & Joint Journal. - : The British Editorial Society of Bone & Joint Surgery. - 2049-4394 .- 2049-4408. ; 104B:12, s. 1343-1351
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Tidskriftsartikel (refereegranskat)abstract
- Aims: The aims of this study were first, to determine if adding fusion to a decompression of the lumbar spine for spinal stenosis decreases the rate of radiological restenosis and/or proximal adjacent level stenosis two years after surgery, and second, to evaluate the change in vertebral slip two years after surgery with and without fusion.Methods: The Swedish Spinal Stenosis Study (SSSS) was conducted between 2006 and 2012 at five public and two private hospitals. Six centres participated in this two--year MRI follow--up. We randomized 222 patients with central lumbar spinal stenosis at one or two adjacent levels into two groups, decompression alone and decompression with fusion. The presence or absence of a preoperative spondylolisthesis was noted. A new stenosis on two--year MRI was used as the primary outcome, defined as a dural sac cross--sectional area = 75 mm2 at the operated level (restenosis) and/or at the level above (proximal adjacent level stenosis).Results: A total of 211 patients underwent surgery at a mean age of 66 years (69% female): 103 were treated by decompression with fusion and 108 by decompression alone. A two--year MRI was available for 176 (90%) of the eligible patients. A new stenosis at the operated and/or adjacent level occurred more frequently after decompression and fusion than after decompression alone (47% vs 29%; p = 0.020). The difference remained in the subgroup with a preoperative spondylolisthesis, (48% vs 24%; p = 0.020), but did not reach significance for those without (45% vs 35%; p = 0.488). Proximal adjacent level stenosis was more common after fusion than after decompression alone (44% vs 17%; p < 0.001). Restenosis at the operated level was less frequent after fusion than decompression alone (4% vs 14%; p = 0.036). Vertebral slip increased by 1.1 mm after decompression alone, regardless of whether a preoperative spondylolisthesis was present or not.Conclusion: Adding fusion to a decompression increased the rate of new stenosis on two--year MRI, even when a spondylolisthesis was present preoperatively. This supports decompression alone as the preferred method of surgery for spinal stenosis, whether or not a degenerative spondylolisthesis is present preoperatively.
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| 3. |
- Lewin, Susanne, et al.
(författare)
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Low-Modulus PMMA Has the Potential to Reduce Stresses on Endplates after Cement Discoplasty
- 2022
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Ingår i: Journal of Functional Biomaterials. - : MDPI. - 2079-4983. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Cement discoplasty has been developed to treat patients with advanced intervertebral disc degeneration. In discoplasty, poly(methylmethacrylate) (PMMA) bone cement is injected into the disc, leading to reduced pain and certain spinal alignment correction. Standard PMMA-cements have much higher elastic modulus than the surrounding vertebral bone, which may lead to a propensity for adjacent fractures. A PMMA-cement with lower modulus might be biomechanically beneficial. In this study, PMMA-cements with lower modulus were obtained using previously established methods. A commercial PMMA-cement (V-steady(R), G21 srl) was used as control, and as base cement. The low-modulus PMMA-cements were modified by 12 vol% (LA12), 16 vol% (LA16) and 20 vol% (LA20) linoleic acid (LA). After storage in 37 degrees C PBS from 24 h up to 8 weeks, specimens were tested in compression to obtain the material properties. A lower E-modulus was obtained with increasing amount of LA. However, with storage time, the E-modulus increased. Standard and low-modulus PMMA discoplasty were compared in a previously developed and validated computational lumbar spine model. All discoplasty models showed the same trend, namely a substantial reduction in range of motion (ROM), compared to the healthy model. The V-steady model had the largest ROM-reduction (77%), and the LA20 model had the smallest (45%). The average stress at the endplate was higher for all discoplasty models than for the healthy model, but the stresses were reduced for cements with higher amounts of LA. The study indicates that low-modulus PMMA is promising for discoplasty from a mechanical viewpoint. However, validation experiments are needed, and the clinical setting needs to be further considered.
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| 4. |
- Pazarlis, Konstantinos A., et al.
(författare)
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Lumbar Spinal Stenosis with Degenerative Spondylolisthesis Treated with Decompression Alone. A Cohort of 346 Patients at a Large Spine Unit. Clinical Outcome, Complications and Subsequent Surgery
- 2022
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Ingår i: Spine. - : Ovid Technologies (Wolters Kluwer Health). - 0362-2436 .- 1528-1159. ; 47:6, s. 470-475
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Tidskriftsartikel (refereegranskat)abstract
- Study Design. Cohort study. Objective. To study the clinical outcome, complications and subsequent surgery rate of DA for lumbar spinal stenosis (LSS) with DS. Summary of Background Data. There is still no consensus regarding the treatment approach for LSS with DS. Methods. We performed a retrospectively designed cohort study on prospectively collected data from a single high productive spine surgical center. Results from the Swedish Spine Registry and a local register for complications were used for the analyses. Patients with LSS and DS (>3 mm) who underwent DA during January 2012 to August 2017 were included. Patient reported outcome measures at baseline and 2 years after surgery were analyzed. Complications within 30 days of surgery and all subsequent surgery in the lumbar spine were registered. Results. We identified and included 346 patients with completed 2-year follow-up registration. At 2-year follow-up there was a significant improvement in all outcome measures. The global assessment success rate for back and leg pain was 68.3% and 67.6% respectively. Forty-one patients had at least 1 intra- or postoperative complication (11.9%). Nine patients (2.6%), underwent subsequent surgery within 2 years of the primary surgery whereof 2 underwent fusion. During the whole period of data collection, that is, as of June 2020, 28 patients had undergone subsequent surgery (8.1%) whereas 8 of them had had 2 surgeries. Fifteen patients underwent fusion. Conclusion. DA provides good clinical outcome at 2-year follow-up in patients with LSS and DS with low rate of intra- and postoperative complications and subsequent surgery. Our data supports the evidence that DA is effective and safe for LSS with DS.
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