ab c d Figure 5. Multisegmental posterior wedge osteotomy This technique creates lordosis and is usually applied to one or multiple levels. a The spine is instrumented with pedicle screws two levels above and below the planned osteotomies. b The interspinous ligament and the adjoining spinous process are resected with a rongeur. The yellow ligament is removed and v-shaped bilateral osteotomies are carried out through the isthmus. c These osteotomies are directed laterocranially at an angle of 30 –40 degrees. The desired slot width of 5–7 mm is obtained by using appropriate rongeurs. If there is a scoliotic deformity, the osteotomies are made slightly larger on the convex side. d The rods are applied first cranially. The osteotomy gaps are closed by stepwise seg- mental compression and connection to the rods. A posterior spinal fusion is added. With one single osteotomy approxi- mately 10 degrees of correction can be achieved. 1074 Section Tumors and Inflammation Osteotomies can be per- formed at four to six levels monic bending of the spine. In contrast to a closing wedge osteotomy, the MPWO removes the posterior elements of a thoracic and/or lumbar level without the need for a wedge excision of the vertebral body ( Fig. 5). Osteotomies can be per- formed at four to six thoracic or lumbar levels depending on the extent and loca- tion of the spinal deformity [47, 98]. With one singular osteotomy approximately 10 degrees of correction can be achieved [98]. The results of this technique are satisfying [47] ( Table 7). Cervical Wedge Osteotomy Cervical closing wedge osteotomy corrects severe cervicothoracic kyphosis A fixed cervicothoracic kyphotic deformity is rare (Case Study 1). However, this deformity can cause a significant morbidity because of an impingement of the chin with the chest, making eating and drinking difficult. Furthermore, patients lose their horizontal gaze. A cervical corrective osteotomy was first described by Uristin1958[95].Theopening wedge osteotom y wasoriginallycarriedoutat the level of C7/T1 during local anesthesia. The osteotomy level is chosen at the cervi- cothoracic junction because the vertebral artery only enters the spine at the level of C6. With the advent of neuromonitoring, these interventions can today be per- formed with the patient under general anesthesia and with less stress for the patient. The disadvantage of the opening wedge osteotomy is the resulting ante- rior gap with potential instability and need for an additional anterior fusion ( Case Study 1). The correction of kyphosis can be balanced up to the level of lor- dosis and corrections have been reported up to 54° [70]. Webb advocates a clos- ing wedge osteotomy because of a better stability without the need for an uncon- trolled cracking of the spine to achieve the correction [104] ( Fig. 6). Method of choice is a closing wedge osteotomy with or without an anterior interbody fusion depending on the fusion status of the anterior column. Case reports of chin on chest deformities so far show excellent resolution of the deformity and solid fusion [73]. Retrospective studies show that cervical spine surgery in AS appears to have a fairly good clinical outcome [56] ( Table 7). However, this osteotomy is very demanding and carries a high risk of neurological injuries [60, 70]. Treatment for Fracture and Spondylodiscitis Fractures are most common at thoracic level and unstable Fractures in AS patients are most commonly localized at the thoracic spine and are very often unstable because they involve the anterior and posterior column [10, 34, 77, 84, 109]. In contrast to a healthy individual, AS patients sustain frac- tures more easily from minor trauma and experience fatigue fractures. These fractures often remain occult (see above) as clinical symptoms are masked by chronic pain. Not infrequently, the spine spontaneously corrects its kyphotic deformity within the fracture ( Case Study 2). Thirty to 75% of cases are associ- ated with severe neurological deficits [10, 34, 42, 77]. Instrumentation should be long rather than short in AS The general concepts of treatment also apply (see Chapters 30 , 31 , 36 )for spinal injuries in AS and aseptic spondylodiscitis (Andersson lesions). In con- trast to common fractures and spondylodiscitis, however, the stabilization should be long rather than short because of the risk of a secondary kyphotic deformity, implant failure and non-union. The degree of instability in AS deter- mines the use of long instrumentation over a minimum of two vertebral bodies above and below the lesion [59]. Laminectomy is indicated when defective posi- tionsorbonyhypertrophyleadstoconstrictionorstenosisofthespinalcanalor in the presence of epidural hematoma. Operative fracture stabilization is pre- ferred to allow for early mobilization of the patient. However, treatment of spinal fracture causing paralysis is difficult and controversial and is associated with a high risk of complications [4, 10, 34, 42, 77, 78, 109]. Surgical management Ankylosing Spondylitis Chapter 38 1075 ab c d e fg Case Study 1 A 58-year-old male was diagnosed with ankylosing spondylitis, which had been present for over 20 years. The patient was severely handi- capped by his inability to look straight ahead ( a). The standing lat- eral radiograph demonstrated a sag- ittal well balanced spine with the deformity located at the cervicotho- racic junction ( b, c). A cervical open- ing wedge osteotomy at C7 was done ( d). The spine was stabilized with facet joint screws at C4 and C5 and pedicle screw fixation at T1 ( e). In a second stage, an anterior inter- corporal fusion and plate/screw fixa- tion was added to close the gap and additionally stabilize the spine ( f). Postoperative photograph (g)shows an excellent correction of the posi- tion of the head. 1076 Section Tumors and Inflammation ab cd Figure 6. Cervical closing wedge osteotomy For this osteotomy the patient is positioned prone within a Mayfield headrest. Sensorimotor potentials should be obtained prior to surgery as a baseline measurement. a The spine is exposed from C4 to T3. Pedicle screws are inserted three levels above and below the osteotomy. In the cervical spine, facet joint screws can be used as an alternative to pedi- cle screws because of a lower risk of neurovascular injuries. The lamina of C7 and the hemilaminae of C6 and T1 are resected. Care has to be taken to completely liberate the nerve roots C6 –8. b The articular processes of C7 are completely removed including the C7 pedicles. The vertebral body of C7 is decancellated with curettes and the posterior wall osteomized with a Kerrison rongeur. c Both rods are inserted and locked in the cervical screws. d The Mayfield head- rest is loosened by an assistant who continues to manually hold the head during the correction. The rods are slowly levered to the thoracic screws and locked. Great care has to be taken that the head extension does not result in a com- promise of the nerve roots. A posterior spinal fusion completes the operation. Treatment of fracture causing paralysis is associated with a high risk of complications of fractures or lesions in AS should be done in specialized interdisciplinary clinics. The reasons are the high rate of complications (e.g., neurological fail- ure, loss of fixation, wound infections, respiratory failure) and mortality post- operatively. Ankylosing Spondylitis Chapter 38 1077 ab cd e f Case Study 2 a A 59-year-old male who had suffered from ankylosing spondylitis for three decades was well adapted to his disease. He sustained a fall on the stairs and complained of weakness in his legs. At hospital admission the patient had a mild paraparesis sub-L1 with decreased sensation and mild weakness in both legs (MRC Grade 4). CT reformatted image ( b) shows a luxation fracture at L1 with significant posterior angulation of the spine. T1 and T2W MRI scans ( c, d) demonstrate the luxation fracture and significant canal enchroachment. The previously ankylosed kyphotic spine corrected at the level of the fracture. After decompression of the spinal canal, the patient was instrumented with a pedicle screw system in the corrected position. Fusion was added at the site of the frac- ture ( e). At one year follow-up visit, the patient had completely recovered and was very satisfied with the correction of the trunk position, which had bothered him for many years prior to his fracture ( f). 1078 Section Tumors and Inflammation Table 7. Surgical results of correction osteotomies Author Cases Localiza- tion Design Technique Complications/outcome Conclusions Langeloo et al. (2006) [60] 16 cervical retro- spective C7 correction osteotomy (OT) with internal fixa- tion from C2–C6 to T1–T6 9 transient paresthesia 1 irreversible neurological complication 2 deep wound infection 2 major general complica- tion C7 correction osteotomy is a reliable technique. At the cervical level neuromonito- ring (TES-MEP) is manda- tory McMaster et al. (1997) [70] 15 cervical retro- spective C7/T1 extension OT with (n =3) and without (n= 12) internal fixation 2 transient paresthesia 2 irreversible neurological complication 1 deep wound infection 4 subluxation 1 major general complica- tion cervical osteotomies are dif- ficult techniques. Subluxa- tion at the osteotomy site is associated with non-union Willems et al. (2005) [108] 105 cervical- thoracic and lumbar retro- spective cervical-thoracic OT (n= 22), lumbar closing- wedge OT (n=62), polysegmental lumbar OT (n= 20), anterior- posterior lumbar OT (n=11) 8 transient paresthesia 9 irreversible neurological complication 11 deep wound infection 12 major general complica- tion correction osteotomies in AS show high complication rates. Reasons are a difficult surgery and a complex dis- ease. AS surgery should be carried out in specialized interdisciplinary centers Danisa et al. (2000) [33] 11 thoracic and thora- columbar retro- spective “eggshell” osteo- tomy 5 transient paresthesia 0 irreversible neurological complication 0 deep wound infection 1 major general complica- tion an “eggshell” osteotomy shows lower complication ratesthanwithopenwedge osteotomies. Main goal of this procedure is to restore sagittal balance Van Royen et al. (1998) [98] 21 thoracic and thora- columbar retro- spective polysegmental lumbar OT 4 transient paresthesia 0 irreversible neurological complication 7 deep wound infection 2 major general complica- tion polysegmental lumbar oste- otomies are associated with high complication rates. Only in the mild phase of AS should a polysegmental lumbar osteotomy be used Hehne et al. (1990) [47] 177 thoracic and thora- columbar retro- spective polysegmental lumbar OT 19 transient paresthesia 4 irreversible neurological complication 6 deep wound infection 4 major general complica- tion the technique results in a harmonious spinal correc- tion. And reduces the potential of severe compli- cations. Most patients are pain free after polysegmen- tal lumbar OT Bradford et al. (1987) [14] 21 thoracic and thora- columbar retro- spective open wedge OT (n= 8), two stage osteotomy (ante- rior and posterior) (n=8) 2 transient paresthesia 0 irreversible neurological complication 0 deep wound infection 0 major general complica- tion a neurological monitoring with a wake-up test is nec- essary. A correction of sagit- tal balance seems to be associated with decreased risk of loss of correction Lazennec et al. (1997) [63] 31 lumbar retro- spective open wedge OT (n= 19) vs. close wedge OT ( n= 12) 4 transient paresthesia 2 irreversible neurological complication 3 reoperations (non- union) vs. 3 transient paresthesia 0 irreversible neurological complication 1 reoperation (non-union) the level of lumbar osteo- tomy is very important, because sagittal translation is a basic mechanism for correcting sagittal imbal- ance Ankylosing Spondylitis Chapter 38 1079 Complications Surgical interventions for AS most often represent major surgery and are techni- cally demanding. Not infrequently patients exhibit malnutrition and are prone to infections. The morbidity and mortality rate can be decreased by careful surgical planning, new operating techniques, new implants and improved intensive care [26, 28, 29, 47, 60, 63, 72, 82, 86, 92, 100]. Complications after ankylosing surgery include [28, 60, 98, 100, 108]: transient paresthesia (0–45%) postoperative infections (0–33%) implant failure (2–33%) loss of correction (5–40°) irreversible neurological deterioration (0–10%) major general complications (0–10%) non-unions (<5%) Surgery for AS is prone to complications Theseinterventionsarerelatedtoalongoperativetime,highlossofbloodanda high rate of peri- and postoperative complications. Therefore, indications need to be discussed on an individual basis and patients have to be consulted exten- sively. Recapitulation Epidemiology. Ankylosing spondylitis (AS) is a sys- temic seronegative inflammatory rheumatic disor- der belonging to the group of spondyloarthritis. AS is associated with sacroiliitis and inflammatory alteration at the axial skeleton. The male:female ra- tio is about 2–7:1. Prevalence estimates vary be- tween 0.2 and 1.2/100000. The peak age of onset is 15– 35 years. The diagnosis is delayed by up to 10 years, because of its insidious nature. Pathogenesis. The pathogenesis is still unclear. There is increasing evidence that AS is genetically determined. AS has a strong association with HLA- B27 and 90 % of all patients are HLA-B27 positive. However, 80–90 % of all HLA-B27 carriers do not de- velop AS. It is therefore widely assumed that addi- tional genetic factors are involved. An infection- triggered onset has recently been added to the ex- isting hypothesis. This concept involves a preced- ing bacterial infection with subsequent autoim- mune responses. The pathological changes of the vertebral column due to AS occur in three consecu- tive stages: inflammation, proliferation and anky- losis. Clinical presentation. Patient complaints are non- specific and difficult to distinguish from general chronic back pain. Cardinal symptoms are inflam- matory back pain, typical arthritis pain (pain at night and stiffness in the morning), progressive spinal stiffness and the inability to look straight ahead. Additional symptoms are enthesis, uveitis, pulmonary, cardial and bowel inflammation as well as reduced chest expansion. Diagnostic work-up. Early diagnosis of AS can be difficult due to unspecific symptoms and diagnos- tic findings of the spinal column. In the case of sus- picion of AS, the diagnosis should be enforced. The diagnostic work-up includes a thorough clinical ex- amination, laboratory investigations (infection pa- rameter, HLA-B27) and imaging studies. The goal is todetectASintheearlydiseasesoastocommence therapy in good time. In the early disease stage, MRI is the state-of-the-art diagnostic tool. Charac- teristic findings on MRI suggestive of AS are discitis, erosions with zones of subchondral sclerosis with- out increased signal after use of a contrast agent, periarticular fat accumulation and syndesmophy- tes. Alternatively, a bone scan can be of further di- agnostic use. Radiographs and computed tomog- raphy are suitable tools for monitoring chronic in- flammatory progression. Furthermore the CT can be utilized for preoperative planning. Following a trauma and suspicion of lesion or fracture radio- graphs, CT and MRI of the whole spine should be performed. 1080 Section Tumors and Inflammation Non-operative treatment. The non-operative phar- macological therapy is the mainstay of care in con- junction with physical exercises. Goal of the treat- ment is the reduction of clinical symptoms, inflamma- tion and delay of disease. The pharmacological ther- apy includes non-selective and selective cyclooxyge- nase (COX) inhibitors (NSAIDs), analgesics, disease modifying antirheumatic drugs (e.g. sulfasalazine, methotrexate) and TNF- inhibitors. Physiotherapy and patient education are in parallel to medical treat- ment cornerstones of AS therapy. Operative treatment. Surgery is of value when con- servative therapy fails, i.e., in the case of massive kyphotic deformity or severe pain. Absolute indica- tions forsurgeryareunstablespinalfractures,kypho- sis-related progressive myelopathy and progressive spondylodiscitis. Surgical correction in AS patients is prone to a high peri- and postoperative complication rate (such as neurological deficits, deep wound infec- tions, failure of implants). However, the morbidity and mortality rate can be decreased by careful surgi- cal planning, new operating techniques, new im- plants and improved intensive care. An important aspect is the perioperative anesthesia. Patient posi- tioning and intubation are often very difficult due to kyphotic deformation. Intraoperative neuromonito- ring is nowadays regarded as indispensable for a safe deformity correction. The ultimate goal of surgical techniques of osteo- tomies is to rebalance the spine and correct the chin-brow angle to an extent that the patient is again able to look straight ahead. The most com- mon technique is a closing wedge osteotomy in the lumbar spine. The underlying concept is to achieve a monosegmental extension while keeping the anterior longitudinal ligament intact. The aim of multisegmental posterior wedge osteotomy is to address deformities predominantly located in thethoracicspineandtoallowforaharmonic bending of the spine. Four to six thoracic or lumbar levels can osteotomized depending on the extent and location of the spinal deformity. Corrections at the level of the cervical spine are performed at the C7/T1 level. The procedure of choice is a closing or opening wedge osteotomy in combination with an instrumented fusion. Cervical spine surgery in AS appears to have a fairly good clinical outcome, although it is a very demanding operational procedure with a potentially high risk of neurological injuries. Fractures in AS patients can already appear after minimal trauma and are often overlooked. Most often, fractures appear in the thoracic spine and are frequently unstable because they involve the ante- rior and posterior spinal column. In 30 –75 % of cases there is an association of severe neurological deficits. In contrast to common fractures, however, the stabili- zation should be long rather than short because of the risk of a secondary kyphotic deformity. Key Articles van Royen BJ (1995) Closing-wedge posterior osteotomy for ankylosing spondylitis. Partial corpectomy and transpedicular fixation in 22 cases. J Bone Joint Surg Br 77: 117 – 121 This retrospective study with closing wedge osteotomy at lumbar level L4 shows that this surgical procedure is effective in addressing the kyphotic deformity. Murrey DB (2002) Transpedicular decompression and pedicle subtraction osteotomy (eggshell procedure): a retrospective review of 59 patients. Spine 27(21):2338 – 45 The eggshell procedure was described and analyzed retrospectively in 59 patients with deformity (n=37) and tumor or infection (n = 22). This surgical procedure is safe and predictable for complex spine deformities. Hehne HJ (1990) Polysegme ntal lumbar osteotomies and transpedicled fixation for cor- rection of long-curved kyphotic deformities in ankylosing spondylitis. Report on 177 cases. Clin Orthop Relat Res 258:49 – 55 This is a retrospective study with a high number of polysegmental lumbar osteotomies in patients with AS. 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Early diagnosis of AS can be difficult due to unspecific symptoms and diagnos- tic findings of the spinal column. In the case of sus- picion of AS, the diagnosis should be enforced allow for early mobilization of the patient. However, treatment of spinal fracture causing paralysis is difficult and controversial and is associated with a high risk of complications [4, 10, 34,. Following a trauma and suspicion of lesion or fracture radio- graphs, CT and MRI of the whole spine should be performed. 1080 Section Tumors and Inflammation Non-operative treatment. The non-operative