Postoperative pain management in patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis: a narrative review

Posterior spinal fusion for adolescent idiopathic scoliosis is one of the most invasive surgical procedures performed in children and adolescents. Because of the extensive surgical incision and massive tissue trauma, posterior spinal fusion causes severe postoperative pain. Intravenous patient-controlled analgesia with opioids has been the mainstay of postoperative pain management in these patients. However, the use of systemic opioids is sometimes limited by opioid-related side effects, resulting in poor analgesia. To improve pain management while reducing opioid consumption and opioid-related complications, concurrent use of analgesics and analgesic modalities with different mechanisms of action seems to be rational. The efficacy of intrathecal opioids and nonsteroidal anti-inflammatory drugs as components of multimodal analgesia in scoliosis surgery has been well established. However, there is either controversy or insufficient evidence regarding the use of other analgesic methods, such as continuous ketamine infusion, perioperative oral gabapentin, acetaminophen, continuous wound infiltration of local anesthetics, a single dose of systemic dexamethasone, and lidocaine infusion in this patient population. Moreover, appropriate combinations of analgesics have not been established. The aim of this literature review is to provide detailed information of each analgesic technique so that clinicians can make appropriate choices regarding pain management in patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion.     

Adolescent idiopathic scoliosis: natural history and long term treatment effects

ABSTRACT : Adolescent idiopathic scoliosis is a lifetime, probably systemic condition of unknown cause, resulting in a spinal curve or curves of ten degrees or more in about 2.5% of most populations. However, in only about 0.25% does the curve progress to the point that treatment is warranted.Untreated, adolescent idiopathic scoliosis does not increase mortality rate, even though on rare occasions it can progress to the >100 degrees range and cause premature death. The rate of shortness of breath is not increased, although patients with 50 degrees curves at maturity or 80 degrees curves during adulthood are at increased risk of developing shortness of breath. Compared to non-scoliotic controls, most patients with untreated adolescent idiopathic scoliosis function at or near normal levels. They do have increased pain prevalence and may or may not have increased pain severity. Self-image is often decreased. Mental health is usually not affected. Social function, including marriage and childbearing may be affected, but only at the threshold of relatively larger curves.Non-operative treatment consists of bracing for curves of 25 degrees to 35 degrees or 40 degrees in patients with one to two years or more of growth remaining. Curve progression of >/= 6 degrees is 20 to 40% more likely with observation than with bracing. Operative treatment consists of instrumentation and arthrodesis to realign and stabilize the most affected portion of the spine. Lasting curve improvement of approximately 40% is usually achieved.In the most completely studied series to date, at 20 to 28 years follow-up both braced and operated patients had similar, significant, and clinically meaningful reduced function and increased pain compared to non-scoliotic controls. However, their function and pain scores were much closer to normal than patient groups with other, more serious conditions.Risks associated with treatment include temporary decrease in self-image in braced patients. Operated patients face the usual risks of major surgery, a 6 to 29% chance of requiring re-operation, and the remote possibility of developing a pain management problem.Knowledge of adolescent idiopathic scoliosis natural history and long-term treatment effects is and will always remain somewhat incomplete. However, enough is know to provide patients and parents the information needed to make informed decisions about management options.     

不同手术方式对腰椎间盘突出症治疗的效果比较分析

目的:探讨应用微创技术治疗腰椎间盘突出症的疗效.方法:对我院脊柱骨科自2005年l1月～2010年10月收治的128例腰椎间盘突出症患者应用不同手术方式进行治疗,其中应用APLD( automated percutaneous lumbar discectomy)治疗单纯腰椎间盘突出症48例;应用MED(microendoscopic discectomy)治疗复杂型腰椎间盘突出症42例;应用传统后路椎板开窗技术治疗单纯腰椎间盘突出症38例;比较各组手术时间、术中出血、术后住院时间、疗效及并发症.术后均随访8个月～3年,观察复发情况.结果:三组不同手术方式手术时间及优良率比较差异无统计学意义(P＞0.05),APLD及MED组术中出血量及术后住院时间与传统手术组比较,差异有显著性(P＜0.05);术后随访疼痛全部缓解,无复发.结论:在严格掌握适应症的基础上,采用微创技术和采用传统手术治疗腰椎间盘突出症疗效相当,但微创技术创伤小、术中出血量少,术后住院日短,恢复快,优于传统手术.     

Chirurgie de l’hyperparathyroïdie primaire en 2008

In recent years, different minimally invasive techniques of parathyroidectomy have been described. The concept of these limited explorations is based on the fact that 85% of patients will have a single-gland disease. Minimally invasive techniques are targeted on one specific parathyroid gland and in most cases the exploration of other glands is not performed. These interventions are today possible for three main reasons: the available imaging techniques permit to localize the diseased gland, the use of rapid intraoperative PTH assay can confirm the successful extirpation, new instrumentation and miniaturized cameras have been adapted for this kind of surgery. Not all patients presenting with primary hyperparathyroidism are candidate for this surgery. Contraindications are mainly due to a large goiter, previous surgery in the parathyroid vicinity, suspicious multiglandular disease and equivocal preoperative localization studies. Currently 60% of patients with primary hyperparathyroidism can benefit of these techniques. Studies comparing conventional parathyroid surgery to minimally-invasive techniques have shown a diminution of postoperative pain and better cosmetic results with minimally-invasive techniques. If early results are similar to those obtained with conventional parathyroidectomies, it is still too soon to evaluate what will be the recurrence rate of these new techniques. One can expect that minimally invasive and conventional parathyroid surgery will probably turn out to be complementary in the near future.     

Short-Term Effect of Unilateral Pedicle Screw Fixed Intervertebral Fusion in Treatment of Degenerative Disc Disease Via MAST QUADRANT Minimally Invasive System

To assess the short-term outcome of unilateral pedicle screw fixed intervertebral fusion surgery for degenerative disc disease via MAST QUADRANT minimally invasive system. Thirty patients with degenerative lumbar disease from September 2009 to September 2011 were enrolled and divided into two groups: (1) unilateral pedicle screw fixed intervertebral fusion via MAST QUADRANT system; and (2) conventional bilateral pedicle fixed intervertebral fusion via open surgery. The perioperative parameters (operation time, intraoperative blood loss, and length of stay) and the follow-up clinical curative effect parameters (VAS and ODI) were compared between two groups. All patients successfully completed surgery and were followed up for more than 1 year. The perioperative parameters of MAST QUADRANT system group were significantly better than the control group (P < 0.05). And the clinical curative effects were similar to conventional surgery (P > 0.05). Unilateral pedicle screw fixed intervertebral fusion via MAST QUADRANT system is a less invasive and safer surgical techniques. It offers a quick recovery and effective surgical option in the treatment of lumbar degenerative diseases.     

Minimally invasive surgery. Implications for hospitals,health workers,and patients.

Minimally invasive surgery is one of the great innovations of health care in the 20th century. It promises to revolutionise surgery by allowing many more operations to be performed with minimal hospitalisation. Pressure from patients has caused many techniques to spread rapidly before they have been adequately assessed. This must be resisted, and policy makers must pay more attention to minimally invasive surgery to ensure that good assessments are made. The widespread use of minimally invasive techniques has important implications for hospitals and health workers. As more patients are treated on an outpatient basis, fewer hospital beds will be needed, and traditional operating rooms will have to adapt to a greater turnover of patients. Surgeons will have to acquire new operating skills, possibly requiring formal training and accreditation, and, as different specialties fight for control of new technologies, surgery may eventually be merged with internal medicine so that specialists will deal with organ systems. Postoperative care will have to be carried out in the community rather than in hospitals, and policy makers will need to reorganise their health systems to cope with these developments.     

A retrospective analysis of health-related quality of life in adolescent idiopathic scoliosis children treated by anterior instrumentation and fusion

Background

Idiopathic scoliosis is the most common type of spinal deformity. Scoliosis is defined as a lateral curvature of the spine greater than 10° accompanied by rotation of the vertebrae. The treatment available for adolescent idiopathic scoliosis is observation, orthosis, and surgery. The surgical options include open anterior release and instrumentation, posterior instrumentation, and thoracoscopic approaches. The Scoliosis Research Society Questionnaire (SRS-30) is a specific instrument to measure health-related quality of life in patients with scoliosis, who had or had not undergone surgery. The purpose was to assess the post-operative functional outcome using SRS-30 in children who underwent anterior release, instrumentation, and fusion using autogenous rib graft for adolescent idiopathic scoliosis (AIS).

Methods

In a retrospective cohort study, 25 patients between the ages of 11 and 17 years, who underwent anterior release, instrumentation, and fusion using autogenous rib graft for adolescent idiopathic scoliosis (AIS) between 2008 and 2014, were included in the study.

Results

The total average score was 4.26 with a SD of 0.014 and had maximum average score 4.5 (for pain) and minimum average score 3.8 (for self-image).

Conclusion

Anterior release, instrumentation, and fusion using autogenous rib graft is having good functional outcome in all domains.

     

Association between adolescent idiopathic scoliosis prevalence and age at menarche in different geographic latitudes

Background

Age at menarche is considered a reliable prognostic factor for idiopathic scoliosis and varies in different geographic latitudes. Adolescent idiopathic scoliosis prevalence has also been reported to be different in various latitudes and demonstrates higher values in northern countries. A study on epidemiological reports from the literature was conducted to investigate a possible association between prevalence of adolescent idiopathic scoliosis and age at menarche among normal girls in various geographic latitudes. An attempt is also made to implicate a possible role of melatonin in the above association.

Material-methods

20 peer-reviewed published papers reporting adolescent idiopathic scoliosis prevalence and 33 peer-reviewed papers reporting age at menarche in normal girls from most geographic areas of the northern hemisphere were retrieved from the literature. The geographic latitude of each centre where a particular study was originated was documented. The statistical analysis included regression of the adolescent idiopathic scoliosis prevalence and age at menarche by latitude.

Results

The regression of prevalence of adolescent idiopathic scoliosis and age at menarche by latitude is statistically significant (p < 0.001) and are following a parallel declining course of their regression curves, especially in latitudes northern than 25 degrees.

Conclusion

Late age at menarche is parallel with higher prevalence of adolescent idiopathic scoliosis. Pubarche appears later in girls that live in northern latitudes and thus prolongs the period of spine vulnerability while other pre-existing or aetiological factors are contributing to the development of adolescent idiopathic scoliosis. A possible role of geography in the pathogenesis of idiopathic scoliosis is discussed, as it appears that latitude which differentiates the sunlight influences melatonin secretion and modifies age at menarche, which is associated to the prevalence of idiopathic scoliosis.     

Quadrant通道下MIS-TLIF与传统术式治疗单节段腰椎退变性疾病的疗效比较

目的:对比分析Quadrant通道下微创椎间孔椎间融合术(MIS-TLIF)与传统开放经椎间孔椎间融合术(TLIF)治疗单节段腰椎退变性疾病的临床疗效和安全性。方法:选取2012年3月至2015年3月120例我院收治的120例单节段腰椎退变性疾病患者,并将其随机分为对照组和微创(MIS)组,每组各60例。对照组患者给予TLIF治疗,微创组给予MIS-TLIF治疗。观察和比较两组患者的手术情况,手术前后的视觉模拟评分(VAS)、Oswestry功能障碍指数(ODI),肌酸磷酸激酶(CPK)水平、椎间植骨融合率及并发症的发生情况。结果:微创组患者的切口长度、出血量、射线照射时间、下地活动时间以及住院时间均显著低于或短于对照组(P0.05);术后1周、6个月,微创组患者的VAS、ODI评分均显著低于对照组(P0.05);术后,两组患者的CPK水平出现剧烈上升,随后又逐渐下降,但同一时段微创组患者的CPK水平明显低于对照组(P0.05);微创组的椎骨性融合率为93.33%(56/60),显著低于对照组(85.00%,P0.05),且其神经损伤、硬膜囊破裂的发生率均显著低于对照组(P0.05),感染的发生率比较差异无统计学意义(P0.05)。结论:Quadrant通道下微创椎间孔椎间融合术治疗单节段腰椎退变性疾病的临床疗效明显优于传统开放经椎间孔椎间融合术,且创伤更小,患者康复更快,安全性更高。     

Smart garment for trunk posture monitoring: A preliminary study

Background

Hueter-Volkmann's law regarding growth modulation suggests that increased pressure on the end plate of bone retards the growth (Hueter) and conversely, reduced pressure accelerates the growth (Volkmann). Literature described the same principle in Rat-tail model. Human spine and its deformity i.e. scoliosis has also same kind of pattern during the growth period which causes wedging in disc or vertebral body.

Methods

This cross sectional study in 150 patients of adolescent idiopathic scoliosis was done to evaluate vertebral body and disc wedging in scoliosis and to compare the extent of differential wedging of body and disc, in thoracic and lumbar area. We measured wedging of vertebral bodies and discs, along with two adjacent vertebrae and disc, above and below the apex and evaluated them according to severity of curve (curve < 30° and curve > 30°) to find the relationship of vertebral body or disc wedging with scoliosis in thoracic and lumbar spine. We also compared the wedging and rotations of vertebrae.

Results

In both thoracic and lumbar curves, we found that greater the degree of scoliosis, greater the wedging in both disc and body and the degree of wedging was more at apex supporting the theory of growth retardation in stress concentration area. However, the degree of wedging in vertebral body is more than the disc in thoracic spine while the wedging was more in disc than body in lumbar spine. On comparing the wedging with the rotation, we did not find any significant relationship suggesting that it has no relation with rotation.

Conclusion

From our study, we can conclude that wedging in disc and body are increasing with progression on scoliosis and maximum at apex; however there is differential wedging of body and disc, in thoracic and lumbar area, that is vertebral body wedging is more profound in thoracic area while disc wedging is more profound in lumbar area which possibly form 'vicious cycle' by asymmetric loading to spine for the progression of curve.     

CT and radiographic analysis of sagittal profile changes following thoracoscopic anterior scoliosis surgery

ABSTRACT: BACKGROUND: Previous studies report an increase in thoracic kyphosis after anterior approaches and a flattening of sagittal contours following posterior approaches. Difficulties with measuring sagittal parameters on radiographs are avoided with reformatted sagittal CT reconstructions due to the superior endplate clarity afforded by this imaging modality. METHODS: A prospective study of 30 Lenke 1 adolescent idiopathic scoliosis (AIS) patients receiving selective thoracoscopic anterior spinal fusion (TASF) was performed. Participants had ethically approved low dose CT scans at minimum 24 months after surgery in addition to their standard care following surgery. The change in sagittal contours on supine CT was compared to standing radiographic measurements of the same patients and with previous studies. Inter-observer variability was assessed as well as whether hypokyphotic and normokyphotic patient groups responded differently to the thoracoscopic anterior approach. RESULTS: Mean T5-12 kyphosis Cobb angle increased by 11.8 degrees and lumbar lordosis increased by 5.9 degrees on standing radiographs two years after surgery. By comparison, CT measurements of kyphosis and lordosis increased by 12.3 degrees and 7.0 degrees respectively. 95% confidence intervals for inter-observer variability of sagittal contour measurements on supine CT ranged between 5-8 degrees. TASF had a slightly greater corrective effect on patients who were hypokyphotic before surgery compared with those who were normokyphotic. CONCLUSIONS: Restoration of sagittal profile is an important goal of scoliosis surgery, but reliable measurement with radiographs suffers from poor endplate clarity. TASF significantly improves thoracic kyphosis and lumbar lordosis while preserving proximal and distal junctional alignment in thoracic AIS patients. Supine CT allows greater endplate clarity for sagittal Cobb measurements and linear relationships were found between supine CT and standing radiographic measurements. In this study, improvements in sagittal kyphosis and lordosis following surgery were in agreement with prior anterior surgery studies, and add to the current evidence suggesting that anterior correction is more capable than posterior approaches of addressing the sagittal component of both the instrumented and adjacent non instrumented segments following surgical correction of progressive Lenke 1 idiopathic scoliosis.     

Learning Curve of Full-Endoscopic Technique Through Interlaminar Approach for L5/S1 Disk Herniations

Although minimally invasive full-endoscopic (FE) spine surgery through the interlaminar approach has proved safe and effective for surgical treatment of lumbar disk herniation, the learning curve of the procedure has not been sufficiently established. The purpose of this study is to determine the learning curve for the FE surgery through interlaminar approach for treating the L5/S1 disk herniation. Thirty-six patients with lumbar disk herniation (L5/S1 segment) who underwent FE lumbar discectomy through the interlaminar approach between March 2011 and March 2012 were equally divided into Group A, B, and C by the study time of the surgeons. Clinical evaluation data included perioperative parameters (operative duration, intraoperative blood loss, and the amount of intraoperative bone and ligament excision), clinical curative effect index [visual analog scale (VAS) score for leg and back pain], complications, and the rate of conversion to open surgery. The operation duration, intraoperative bleeding, and the amount of bone and ligament excision were gradually and significantly reduced in the Groups A, B, and C (P < 0.01) and reflected in steep curves of proficiency suggesting that the rate of learning was fast. The VAS scores of leg and back pain were significantly improved (P < 0.01) and no symptomatic recurrence was noticed during the follow-up period (1–1.5 years). The outcomes the three groups were not significantly different. The clinical outcomes of the minimally invasive surgery for the treatment of L5/S1 segment disk herniation through the interlaminar approach were excellent suggesting of a satisfactory curative effect. The steep learning curves of perioperative parameters plotted against the number of surgeries conducted suggest that proficiency can be reached reasonably fast.     

Surgical Data and Early Postoperative Outcomes after Minimally Invasive Lumbar Interbody Fusion: Results of a Prospective,Multicenter, Observational Data-Monitored Study

Minimally invasive lumbar interbody fusion (MILIF) offers potential for reduced operative morbidity and earlier recovery compared with open procedures for patients with degenerative lumbar disorders (DLD). Firm conclusions about advantages of MILIF over open procedures cannot be made because of limited number of large studies of MILIF in a real-world setting. Clinical effectiveness of MILIF in a large, unselected real-world patient population was assessed in this Prospective, monitored, international, multicenter, observational study. Objective: To observe and document short-term recovery after minimally invasive interbody fusion for DLD. Materials and Methods: In a predefined 4-week analysis from this study, experienced surgeons (≥30 MILIF surgeries pre-study) treated patients with DLD by one- or two-level MILIF. The primary study objective was to document patients’ short-term post-interventional recovery (primary objective) including back/leg pain (visual analog scale [VAS]), disability (Oswestry Disability Index [ODI]), health status (EQ-5D) and Patient satisfaction. Results: At 4 weeks, 249 of 252 patients were remaining in the study; the majority received one-level MILIF (83%) and TLIF was the preferred approach (94.8%). For one-level (and two-level) procedures, surgery duration was 128 (182) min, fluoroscopy time 115 (154) sec, and blood-loss 164 (233) mL. Time to first ambulation was 1.3 days and time to study-defined surgery recovery was 3.2 days. Patients reported significantly (P < 0.0001) reduced back pain (VAS: 2.9 vs 6.2), leg pain (VAS: 2.5 vs 5.9), and disability (ODI: 34.5% vs 45.5%), and a significantly (P < 0.0001) improved health status (EQ-5D index: 0.61 vs 0.34; EQ VAS: 65.4 vs 52.9) 4 weeks postoperatively. One adverse event was classified as related to the minimally invasive surgical approach. No deep site infections or deaths were reported. Conclusions: For experienced surgeons, MILIF for DLD demonstrated early benefits (short time to first ambulation, early recovery, high patient satisfaction and improved patient-reported outcomes) and low major perioperative morbidity at 4 weeks postoperatively.     

An energy approach describes spine equilibrium in adolescent idiopathic scoliosis

Biomechanics and Modeling in Mechanobiology - The adolescent idiopathic scoliosis (AIS) is a 3D deformity of the spine whose origin is unknown and clinical evolution unpredictable. In this work, a...     

A reduced-order model of the spine to study pediatric scoliosis

Biomechanics and Modeling in Mechanobiology - The S-shaped curvature of the spine has been hypothesized as the underlying mechanical cause of adolescent idiopathic scoliosis. In earlier work, we...     

Anthropometric parameters as predictors for iliopsoas muscle strength in healthy girls and in girls with adolescent idiopathic scoliosis

In this study iliopsoas muscle strength was measured by portable dynamometer and it was explored to what extent independent predictors (age, body weight, body height and body mass index) affect iliopsoas strength in healthy subjects and in subjects with adolescent idiopathic scoliosis. The study population was consisted of 183 girls (90 healthy girls and 93 girls with adolescent idiopathic scoliosis). Student t test analysis showed no differences in maximal voluntary isometric contraction between healthy girls and girls with scoliosis. Independent variables predicted significantly iliopsoas strength in healthy group (r=0.96, p<0.01) and in scoliosis group (r=0.94, p<0.001). Separate analysis with respect to types of scoliosis demonstrated that independent variables significantly predict iliopsoas strength in right thoracic (r=0.97, p<0.01), left thoracic (r=0.98, p=0.004), right thoracic lumbar (r=0.97, p<0.01) and left lumbar (r=0.96, p<0.01) scoliosis subgroups. In healthy girls iliopsoas strength was mostly predicted by body weight, followed by body height and body mass index. In girls with scoliosis body weigth was the strongest predictor of iliopsoas strength and was followed by curvature angle degree.     

微创腰椎后路减压融合术与传统全椎板切除术治疗老年腰椎管狭窄的疗效对比分析

目的:对老年腰椎管狭窄的两种治疗方式,微创腰椎后路减压融合术和传统全椎板切除术的治疗疗效进行比较,以及研究其临床应用价值。方法:选取2009年7月至2013年1月来我院治疗的76例老年腰椎管狭窄症患者,其中43例采用微创腰椎后路减压融合术(A组),33例患者接受全椎板切除手术(B组)。对所有患者进行术后随访6个月~2年,平均随访时间1年零7个月。比较分析两组的手术情况、术后不良反应发生率及JOA评分情况。结果:A组的患者手术切口小,术中出血量少及住院时间缩短,并且较B组差异有统计学意义(P0.05);两组患者发生不良反应的情况差异无统计学意义(P0.05);A组患者的JOA评分明显优于B组患者,说明A组疗效优于B组。结论:老年腰椎管狭窄患者采用微创腰椎后路减压融合手术方法创口小,术中出血量少,降低术后不良反应发生的风险,疗效明显,值得推广应用。     

The Vestibular-Evoked Postural Response of Adolescents with Idiopathic Scoliosis Is Altered

Adolescent idiopathic scoliosis is a multifactorial disorder including neurological factors. A dysfunction of the sensorimotor networks processing vestibular information could be related to spine deformation. This study investigates whether feed-forward vestibulomotor control or sensory reweighting mechanisms are impaired in adolescent scoliosis patients. Vestibular evoked postural responses were obtained using galvanic vestibular stimulation while participants stood with their eyes closed and head facing forward. Lateral forces under each foot and lateral displacement of the upper body of adolescents with mild (n = 20) or severe (n = 16) spine deformation were compared to those of healthy control adolescents (n = 16). Adolescent idiopathic scoliosis patients demonstrated greater lateral displacement and net lateral forces than controls both during and immediately after vestibular stimulation. Altered sensory reweighting of vestibular and proprioceptive information changed balance control of AIS patients during and after vestibular stimulation. Therefore, scoliosis onset could be related to abnormal sensory reweighting, leading to altered sensorimotor processes.     

Use of a radiopaque localizer grid to reduce radiation exposure

Background

Minimally invasive spine surgery requires placement of the skin incision at an ideal location in the patient's back by the surgeon. However, numerous fluoroscopic x-ray images are sometimes required to find the site of entry, thereby exposing patients and Operating Room personnel to additional radiation. To minimize this exposure, a radiopaque localizer grid was devised to increase planning efficiency and reduce radiation exposure.

Results

The radiopaque localizer grid was utilized to plan the point of entry for minimally invasive spine surgery. Use of the grid allowed the surgeon to accurately pinpoint the ideal entry point for the procedure with just one or two fluoroscopic X-ray images.

Conclusions

The reusable localizer grid is a simple and practical device that may be utilized to more efficiently plan an entry site on the skin, thus reducing radiation exposure. This device or a modified version may be utilized for any procedure involving the spine.     

Comparative study of Mm. Multifidi in lumbar and thoracic spine.

Imbalance of Mm. Multifidi may play a role in spinal disorders such as scoliosis in the thoracic spine, and lumbar disc herniation and lower back pain in the lumbar spine. Even though changes in these muscles are related to the etiology of these disorders, their anatomy is still poorly understood, especially in the upper regions of the spine. With the aim of gaining a better understanding of the anatomy of Mm. Multifidi in the lumbar and thoracic spine, 12 fresh and two embalmed cadavers were dissected. Our results indicate that Mm. Multifidi present differences in lumbar and thoracic spines concerning their deepness, fibre trajectory, muscle length, muscle mass and tendinous tissue. In the lumbar spine Mm. Multifidi are a superficial, thick and fleshy mass, and their fibres are more vertical in relation to the spinous processes. In the thoracic spine Mm. Multifidi are deeper, thinner, and their fibres are more tendinous and oblique than in the lumbar spine. These differences have implications on Mm. Multifidi architecture and consequently for their function in these two regions of the spine.