Spinal Disorders: Fundamentals of Diagnosis and Treatment Part 65 pptx

ab c d ef g Figure 3. Standard radiography a Compensated double major curve. b Decompensated thoracic curve. c Risser sign I–II (arrows). d Sagittal profile with a flat back. e, f Thoracic and lumbar side bending views. g Silhouette radiograph demonstrating a rib cage deformity. Idiopathic Scoliosis Chapter 23 633 ab cd Figure 4. Radiographic assessments a Cobb measurement. b Risser sign. c Vertebral rotation according to Nash/Moe: the more rotated the vertebra, the more the pedicle at the convexity passes towards and beyond the midline and the pedicle at the concavity disappears. d Verte- bral rotation according to Perdriolle: the radiograph of the target vertebra is superimposed by a torsionometer. The intersection of the pedicle at the convexity with the respective line of the torsionometer determines the rotation. cation of the apophysis of the iliac crest [185]. This apophysis first appears ante- rosuperiorly of the iliac crest and progresses towards posterior before it fuses with the iliac spine. According to Risser, the iliac crest is divided into four quar- ters in the anteroposterior radiograph. If none of the quarters is calcified, Risser stage is 0; if one quarter is calcified Risser stage is 1 and so on. If the complete apophysis is fused with the iliac crest, Risser stage is 5. 634 Section Spinal Deformities and Malformations Two methods are commonly used to assess vertebral rotation on standard ante- roposterior radiographs: Nash/Moe method Perdriolle method The technique by Nash and Moe determines vertebral rotation according to the pedicles into five grades [150] ( Fig. 4c). In grade 0 (neutral) both pedicles show a symmetric distance from the lateral borders of the vertebral bodies. In grade I and II the pedicle on the convex side translates towards the middle line of the ver- tebralbodywhereastheoneontheconcavesidebeginstodisappear.IngradeIII the pedicle of the convex side lies in the midline of the vertebral body and in grade IV and V it passes the midline towards the concave half of the vertebral body.Inthesetwogradesthepedicleoftheconcavesideisnolongervisible. Vertebral rotation is measured by the method of Nash and Moe or Perdriolle The method of Perdriolle (Fig. 4d)allowstheangleofrotationtobeestimated by using a specific transparent torsionometer which is laid on the radiograph [175, 176]. The angle of rotation can then be read off the torsionometer according to the projection of the pedicle on the convex side. The rib-vertebral angle (RVA) is construed by a midvertebral vertical line and a line centered through the rib head. Progression or resolution of infantile idio- pathic scoliosis may be predicted by the RVA difference. Mehta described this method which combines the difference of the rib-vertebra angles of the convex and the concave curve side as the so-called “phase of the rib head” [137]. Two phasesmaybedistinguished.InPhase1theribheadoftheconvexriboftheapi- cal vertebra shows no overlap with the apical vertebra. In Phase 2 there is an over- lap to be found. Radiographic curve assessments in the lateral view ( Fig. 3d) include the deter- mination of the following parameters [36]: thoracic and lumbar profile (angle of kyphosis/lordosis) sagittalspinalbalance other abnormalities: spondylolysis/-listhesis The intraobserver error in Cobb measurements ranges between 3° and 10° For the assessment of the sagittal thoracic profile, the upper endplate of T1 and the lower endplate of T12 are used to determine the Cobb angle of kyphosis or lordo- sis, respectively. If T1 is not distinguishable on the radiograph due to overprojec- tion of the shoulder, the upper endplate of T4 or T5 is usually used. For the assess- ment of the sagittal lumbar profile, the upper endplates of L1 and S1 are used. According to inter- and intraobserver reliability studies of the Cobb method in juvenile and adolescent idiopathic scoliosis, a change of between 5° and 10° [30, 62,94,121,122,180]betweentwomeasurementsisconsideredtobeatruechange of curvature. In congenital scoliosis, the variability in measurement of the Cobb angle is largely due to skeletal immaturity and incomplete ossification. However, it is important always to compare the actual with the baseline radiographs. Side bending supine images are necessary to determine curve rigidity When a surgical correction of the deformity is considered, additional antero- posterior supine side-bending views are necessary ( Fig. 3e, f)toassesstherigid- ity of the curves (i.e., extent of curve correction). The films are taken with the patient supine on the X-ray table with maximal passive side bending. The rib hump can be radiologically assessed by a silhouette radiograph taken from pos- terior with the patient inclined horizontally ( Fig. 3g) [94]. Magnetic Resonance Imaging The purpose of preoperative MRI is to detect intraspinal pathologies. Possible pathologies include syringomyelia, Arnold-Chiari malformation, tethered spinal cord ( Fig. 5a–c) or intraspinal tumors. Several studies have documented the risk Idiopathic Scoliosis Chapter 23 635 ab c Figure 5. Magnetic resonance imaging a Standard radiograph showing an atypical left thoracic curve. b MRI of this patient reveals an Arnold-Chiari malforma- tion Type I (arrows)andasyrinx(arrowheads). c MRI of the thoracolumbar spine with a tethered cord demonstrated by a low conus at the level of L4. of neurological complications in scoliosis correction surgery with concomitant syringomyelia [91, 159, 160, 167]. There is a broad consensus on performing preoperative MRI of the complete spine in patients presenting with atypical idiopathic scoliosis, i.e.: infantile and juvenile onset [61, 119] painful scoliosis [9, 192] left convex thoracic curves [9, 231] neurological abnormalities (e.g., absent abdominal reflexes) [192, 237] Preoperative MRI is mandatory in atypical scoliosis There is an ongoing controversy in the literature whether to routinely perform pre- operative MRI in adolescent idiopathic scoliosis [49, 68, 86, 163]. Some authors only recommend performing MRI in the aforementioned cases [49, 92, 195, 231]. We pre- fer routine MRI in all patients scheduled for operative scoliosis treatment [68, 86]. Computed Tomography For severe curves, CT may be helpful for surgical planning Computed tomography is not routinely used in the preoperative assessment of idiopathic scoliosis. In selected cases, however, preoperative CT scans may be of value to precisely assess vertebral deformation and rotation. CT may be used to assess pedicle size and shape before using spinal instrumentation. In juvenile idi- opathic scoliosis, it may be necessary to assess pedicle size before performing surgery because the pedicle diameter may be too small for a pedicle screw inser- tion affording alternative instrumentation methods [71]. 636 Section Spinal Deformities and Malformations Injection Studies In adult idiopathic scoliosis, injection studies are helpful in identifying the source of the pain (see Chapter 10 ). Provocative discography may be used to identify symptomatic disc degeneration. This test is only helpful if the typical pain can be provoked at the target level without pain provocation at adjacent MR normal levels [118, 191]. Selective nerve root blocks or facet joint blocks may be useful in identifying nerve root compromise and symptomatic facet joint arthri- tis, respectively [73, 118]. Neurophysiologic Evaluation Neurophysiologic evaluation is recommended to detect a subclinical pathology A thorough neurophysiologic evaluation is necessary in clinically suspicious patients. In a study on 100 patients with typical right convex idiopathic adoles- cent curve and normal neurologically, 56% showed alterations in the neurophys- iologic evaluation of somatosensory evoked potentials (SSEPs) [86]. Preopera- tive pathologic differences between left and right were found in 17% of the cases although no clinical signs could be detected. This indicates that by neurophysio- logic evaluation subclinical pathologies may be detected and that this method may be used for preoperative screening. It was also found that in uneventful sco- liosis surgery pre- and postoperative SSEPs were found to be similar and that the influence of anesthesia on intraoperative SSEPs becomes quite predictable when using a standardized anesthesia protocol [205]. Treatment General Considerations Idiopathic scoliosis does not usually present with severe symptoms (i.e., no pain or neurological deficits) before adulthood. In this age group, the general objec- tives of treatment are ( Table 2): Table 2. General objectives of treatment arrest progression correct spinal deformity maintain or restore sagittal and coronal balance maintain or restore sagittal and coronal balance preserve function of lower lumbar motion segments allow for further growth of the spine (only infantile and juvenile scoliosis) When deciding on the most appropriate therapy, the key questions are whether the individual curve exhibits the potential of progression and with what conse- quences. The fact that patients with idiopathic scoliosis usually present early in life and adverse consequences may only occur decades later makes patient selec- tion a challenge. The knowledge of the natural history is therefore a prerequisite for a counselling of an appropriate treatment. Natural History Infantile Idiopathic Scoliosis Only few cases of infantile scoliosis progress rapidly to severe deformities Infantile scoliosis was found to usually develop in the first months of life affecting more males than females (ratio 3:2) [95, 96, 120, 193]. The majority of structural curves in this age group resolved partly or completely and remained stable there- after. However, a minority of patients exhibited rapid progression and developed Idiopathic Scoliosis Chapter 23 637 severe curves when left untreated. Especially girls with right sided curves were foundtobeatahighriskofdeterioration[215]. A feature that may help to predict progression or resolution of infantile idio- pathic scoliosis is the RVAD as described by Mehta [137]. In Phase 1,anRVAD of more than 20° is associated with progression of the curve in 84 % whereas an RVAD of less than 20° is associated with resolving of the curve in 83%. In Phase 2, all curves progressed independently of the RVAD [137]. These findings Double major curves are likely to progress were supported by Ferreira and James [64]. The appearance of a double curve was found to be correlated with progression by Ceballos et al. [32]. These curves must therefore be followed closely. Juvenile Idiopathic Scoliosis Spinal growth during the age between 3 and 10 years is rather steady [172]. Regression of the curve may occur [136] but usually curves in this group are char- acterized by slow to moderate progression [65, 95, 106, 179]. Early onset curves are at higher risk for severe progression. The reported necessity for surgery varies between 30% [136, 216] and 56% [65]. Right thoracic and double major curves are the predominant curve patterns. In approximately 20% of patients in this age group, scoliosis is associated with an intraspinal abnormality and it is strongly recommended that curves larger than 20° should be evaluated by MRI [77, 119]. Adolescent Idiopathic Scoliosis Several studies postulated that less than 10% of individuals exhibiting curves larger than 10° require treatment [23, 125, 188, 228]. Several studies have explored the natural history of progression in idiopathic scoliosis during adoles- cence. Risk factors for curve progression are: young age at onset [187] premenarchal status [25, 125] physical immaturity (Risser sign, Tanner stages) [185, 211] larger curves [25, 125, 220] female gender [25] Thoracic curves (>50°) tend to progress even after skeletal maturity Progression is influenced by the curve type with double major curves being at highest progression risk [25, 125]. Larger curves generally have a higher progres- sion risk than smaller ones [25, 125, 220] and progression is more frequent in female patients [5, 25, 56, 221, 222]. Curve progression has also been found to occurafterskeletalmaturity,especiallyinthoraciccurveslargerthan50°[5,179, 222]. Curves that were smaller than 30° at skeletal maturity did not tend to pro- gress during adulthood. Health related quality of life in patients with AIS is comparable to healthy controls Early studies on the natural history of scoliosis included mixed types of scolio- sis and reported higher mortality rates, more back pain and psychosocial adverse effectssuchasalowerrateinmarriedwomenorareducedabilitytowork[148, 156]. More recent selective studies on adolescent idiopathic scoliosis did not show such unsatisfactory outcomes. Collis and Ponsetti [39] found that most of their 215 investigated patients with non-operated AIS led normal and active lives, were productive, worked, married and showed similar activities compared to the normal population. They did not find a higher mortality rate in scoliosis patients. However, they found back pain to occur more frequently than in the normal pop- ulation. Similar findings were reported by Weinstein et al. [222]. Danielsson et al. [43] found that health-related quality of life in patients with adolescent idio- pathic scoliosis was about the same as in the general population after more than 638 Section Spinal Deformities and Malformations 20 years of follow-up. However, the scoliosis patients exhibited slightly reduced physical function (SF-36) and more disability (Oswestry Score) compared to healthy controls. The prevalence of back pain and physical disability seems higher in scoliosis patients than in healthy controls Similar findings were found by Haefeli et al. [79] in a 10- to 60-year follow-up of conservatively treated patients who exhibited a similar quality of life com- pared to healthy controls according to the WHOQOL-Bref. assessment. Whereas Danielsson et al. [43] and Weinstein et al. [220] found no correlation between Cobb angle and disability or pain, Haefeli et al. [79] detected slightly but signifi- cantly higher pain levels in patients with curves of more than 45°. In contrast to the earlier studies mentioned above, Danielsson et al. [42] and Weinstein [220] did not find differences regarding rates of marriages, childbear- ing and sexual function in women 22–50 years of age regardless of treatment. Respiratory and cardiac failure may occur in large (>70°) thoracic curves This data suggests adolescent idiopathic scoliosis to be a rather benign spinal disorder especially in cases of small to moderate curve sizes. On the other hand, it has been shown that thoracic curves bigger than 70° exhibit an increased risk of chronic respiratory or cardiac failure [11]. Non-operative Options Considering the relatively benign natural history of idiopathic scoliosis, surgical treatment is reserved for progressive large curves. The vast majority of remain- ing cases can be treated non-operatively. Conservative measures consist of: physiotherapy bracing electrotherapy So far, there is no evidence for the efficacy of electrotherapy [117]. Physiotherapy Physiotherapy does not arrest curve progression Non-operative treatment generally consists of observation and physiotherapy in curves smaller than 25° [123]. A recent review of the effectiveness of physiother- apy in the treatment of scoliosis has identified 11 studies [151]. The methodolog- ical quality of the retrieved studies was found to be very poor. Therefore, the lit- erature fails to provide solid evidence that physical exercises influence the natu- ral history. Nevertheless, physiotherapy is a helpful adjunct to reduce symptoms related to muscle imbalance and to improve or preserve back function [224, 225]. The limitations of physiotherapy with regard to curve progression have to be clearly communicated to the patient and their parents prior to treatment. Patients having physiotherapy remain under surveillance with regard to curve progression. Casts and Bracing Infantile and Juvenile Idiopathic Scoliosis Progression risk is high in early onset scoliosis In early onset (<6 years), scoliosis therapy is dominated by the progression risk. Curves that are expected to resolve may be simply observed every 4–6 months. Active treatment should be initiated at a progression of 10°. Patients whose curvesresolveshouldbefolloweduntilmaturitytoruleoutanyprogressiondur- ing the growth spurt [2]. In resolving curves plaster-bed treatment showed no advantage over physiotherapy with regard to the time of resolution or functional outcome after 25 years [48]. When progression is documented treatment should be started. Initial therapy consists of serial molded body casts that have to be Idiopathic Scoliosis Chapter 23 639 changed every 6–12 weeks until maximum correction is achieved. Then, full- time bracing is started for at least 2 years and until there is no further progression to be observed [2]. Prognosis is good if total correction is achieved before the prepubertal growth spurt [138]. If no full correction may be achieved, progres- sion may occur, possibly necessitating surgery. Adolescent Idiopathic Scoliosis The choice of therapy depends on the severity of the curve and the potential for progression In adolescent idiopathic scoliosis with curves between 25° and 40° in a skeletally immature (<Risser 3) patient, bracing is indicated [123]. However, it must be borne in mind that the primary goal is to prevent curve progression through bracing ( Fig. 6). The treatment is considered successful if the initial curve size at treatment entry can be preserved at the end of bracing. Often an improvement occurs during therapy but is lost after brace cessation [31, 139, 227]. In the pres- ence of a true thoracic lordosis (>5° to 10°), bracing may be impossible as any positioning of the thoracic pad will increase thoracic lordosis and thus make cor- rection impossible. The possible psychological distress of a long-term therapy such as bracing and the efficacy of the treatment must carefully be considered [63, 135, 157, 165, 219]. There is limited evidence for the effectiveness of bracing The effectiveness of conservative treatment modalities has been the subject of several studies [117]. The only study that found a significant difference in favor of bracing compared to observation and overnight electrical stimulation was presented by Nachemson and Peterson for curves ranging from 25° to 35° in female patients [149]. In the same study, no difference was found between brac- ing and physiotherapy. Other studies found no significant differences for bracing versus natural history [158]. A recent survey among members of the Scoliosis Research Society and of the Pediatric Orthopaedic Society of North America revealed a high degree of variability with regard to the opinion of the effective- ness of brace treatment [52]. Based on the current literature, there seems to exist only limited evidence for the effectiveness of bracing. a b cd Figure 6. Thoracolumbar brace a, b Thoracolumbar brace. c, d Patients should wear the brace for a minimum of 23 h daily to achieve a treatment effect. 640 Section Spinal Deformities and Malformations Operative Treatment The risks and benefits of surgery must be carefully weighed against the natural history when the scoliosis is left untreated. Intensive counselling of the patients and their parents is necessary to explain the pros and cons of the intervention, risks and potential outcome. The indications for surgery for idiopathic scoliosis depend on: risk for progression skeletal maturity curve type curve magnitude cosmetic appearance failure of conservative treatment Intraoperative neuromonito- ring is the standard of care Surgeryhastobewellplannedinadvanceandrequiresadedicatedteamtaking care of children and adolescents. Intraoperative neuromonitoring has become the standard of care to control spinal cord function during correcting surgery [67, 131, 168, 173] (see Chapters 12 , 15 ). The use of intraoperative somatosen- sory evoked potential (SSEP) recording has been found to reduce the incidence of postoperative neurological deficits [161, 166]. Combined monitoring of motor and somatosensory potentials has even been found to be superior compared to single mode monitoring by increased sensitivity [174]. Indications for Surgery Indications for surgery are somewhat different for the specific age group and are discussed under each type of scoliosis accordingly. Infantile and Juvenile Idiopathic Scoliosis In these young patients, surgery is preserved for those curves that are severe and progressing despite conservative treatment. Lungs, thorax and spine are still incompletely developed and usually prohibit multisegmental spinal fusion in Spinal instrumentation without fusion is the surgi- cal treatment of choice for infantile and juvenile curves patients younger than 5–6 years. Spinal instrumentation without fusion may be indicated in large progressive curves allowing the spine still to grow.Different systems are in use but all have a high risk of complications that may necessitate several revision operations [66, 105, 183]. If the curve deteriorates despite instru- mentation, definitive fusion of the spine should be considered. In this age group, the surgical treatment of scoliosis is usually difficult, prone to complications and requires multiple surgeries. Adolescent Idiopathic Scoliosis Progressive adolescent curves (>40 –50°) are con- sidered surgical candidates Progressive curves (>40–50°) in skeletally immature patients (Risser Grade 3 or less) are usually considered candidates for surgery. It should be taken into account that large curves may progress even after skeletal maturity [5, 179, 222]. Cosmetic aspects may also play a role in the indication of surgery, especially in the presence of a substantial rib hump or shoulder asymmetry [81]. Adult Idiopathic Scoliosis Indications for surgery in adult idiopathic scoliosis depend on the predominant problem [1, 15], i.e. Idiopathic Scoliosis Chapter 23 641 back and/or leg pain radiculopathy claudication symptoms curve progression spinal imbalance The surgical indication in adult curves is determined by the secondary degeneration A thorough diagnostic work-up must be done to reveal the specific problem and potential pain sources. In cases of adult scoliosis with predominant degenerative alterations, similar principles apply as for de novo scoliosis (see Chapter 26 ). Accordingly, selective decompression of neural structures and/or spinal fusion with or without deformity correction is indicated [16]. General Principles Approach The choice of the surgical approach, i.e., posterior, anterior or combined anterior and posterior, depends on: curvetypeandsize curve rigidity skeletal maturity spinal instrumentation surgical skills Posterior Approach The posterior approach addresses the deformity by fixing rods to the posterior structures of the spine, i.e., the pedicles, the transverse processes, or the laminae ( Fig. 7). This approach necessitates detachment of the posterior paraspinal mus- cles. Only little is known about the extent of muscle detachment in scoliosis sur- gery but it does not seem to interfere significantly with the spinal muscle func- tion after 3–6 months [53]. Harrington introduced the first instrumentation for posterior scoliosis correction in the 1960s [85]. In general, long term outcome in terms of quality of life, disability and patient satisfaction were found to be quite satisfactory after the Harrington operation [38, 74, 154, 169, 170]. In the 1970s, Luque introduced segmental spinal fixation using sublaminar wires [132]. The so-called third generation instrumentations were introduced in the 1980s. These modern implant systems allowed for a segmental instrumentation by the use of contourable rods that are fixed to the spine by lamina hooks, pedicle hooks, transverse process hooks, and pedicle screws. The instrumentation sys- tems of Cotrel Dubousset [40], the Texas Scottish Rite Hospital (TSRH) and the ISOLA were the most frequently used implants at that time which allowed for more correction and preservation of lower lumbar motion segments compared to the Harrington system [114]. Despite the advances of the third generation Correction of vertebral rotation remains a challenge instrumentations, correction of vertebral rotation is limited even with the use of pediclescrews.Inyoungpatientswithalargegrowthpotentialthereisariskof continuing anterior growth of the spine despite a solid posterior fusion, which leads to the so-called crankshaft phenomenon (see below). Anterior Approach Anterior scoliosis correction allows for a better derota- tion and shorter fusion Dwyer introduced the anterior approach for scoliosis correction in 1969 [57]. Ten years later, Zielke first introduced the concept of anterior derotation spon- dylodesisusingvertebralbodyscrewsconnectedbyarod[238].Hereportedon 642 Section Spinal Deformities and Malformations . members of the Scoliosis Research Society and of the Pediatric Orthopaedic Society of North America revealed a high degree of variability with regard to the opinion of the effective- ness of brace treatment. overprojec- tion of the shoulder, the upper endplate of T4 or T5 is usually used. For the assess- ment of the sagittal lumbar profile, the upper endplates of L1 and S1 are used. According to inter- and intraobserver. al. [42] and Weinstein [220] did not find differences regarding rates of marriages, childbear- ing and sexual function in women 22–50 years of age regardless of treatment. Respiratory and cardiac failure