50. Jaffray D, Becker V, Eisenstein S (1992) Closing wedge osteotomy with transpedicular fixa- tion in ankylosing spondylitis. Clin Orthop Relat Res:122–6 51. Kawasaki T, Hukuda S, Katsuura A, Inoue K, Chano T (1996) Lumboperitoneal shunt for cauda equina syndrome in ankylosing spondylitis. J Spinal Disord 9:72–5 52. Kennedy LG, Edmunds L, Calin A (1993) The natural history of ankylosing spondylitis. Does it burn out? J Rheumatol 20:688–92 53. Kennedy LG, Will R, Calin A (1993) Sex ratio in the spondyloarthropathies and its relation- ship to phenotypic expression, mode of inheritance and age at onset. J Rheumatol 20: 1900–4 54. Khan MA (2000) HLA-B27 polymorphism and association with disease. J Rheumatol 27: 1110–4 55. Khan MA, Ball EJ (2002) Genetic aspects of ankylosing spondylitis. Best Pract Res Clin Rheumatol 16:675–90 56. Koh WH, Garrett SL, Calin A (1997) Cervical spine surgery in ankylosing spondylitis: is the outcome good? Clin Rheumatol 16:466–70 57. Koivikko MP, Kiuru MJ, Koskinen SK (2004) Multidetector computed tomography of cervi- cal spine fractures in ankylosing spondylitis. Acta Radiol 45:751–9 58. Lambrecht V, Vanhoenacker FM, Van Dyck P, Gielen J, Parizel PM (2005) Ankylosing spon- dylitis: what remains of the standard radiography anno 2004? JBR-BTR 88:25–30 59. Lange U, Pape HC, Bastian L, Krettek C (2005) [Operative management of cervical spine injuries in patients with Bechterew’s disease]. Unfallchirurg 108:63–8 60. Langeloo DD, Journee HL, Pavlov PW, de Kleuver M (2006) Cervical osteotomy in ankylos- ing spondylitis: evaluation of new developments. Eur Spine J 15:493–500 61. Langlois S, Cedoz JP, Lohse A, Toussirot E, Wendling D (2005) Aseptic discitis in patients with ankylosing spondylitis: a retrospective study of 14 cases. Joint Bone Spine 72:248 –53 62. Laval SH, Timms A, Edwards S, Bradbury L, Brophy S, Milicic A, Rubin L, Siminovitch KA, Weeks DE, Calin A, Wordsworth BP, Brown MA (2001) Whole-genome screening in anky- losing spondylitis: evidence of non-MHC genetic-susceptibility loci. Am J Hum Genet 68:918–26 63. Lazennec JY, Saillant G, Saidi K, Arafati N, Barabas D, Benazet JP, Laville C, Roy-Camille R, Ramare S (1997) Surgery of the deformities in ankylosing spondylitis: our experience of lumbar osteotomies in 31 patients. Eur Spine J 6:222–32 64. LeeYS,SchlotzhauerT,OttSM,vanVollenhovenRF,HunterJ,ShapiroJ,MarcusR,McGuire JL (1997) Skeletal status of men with early and late ankylosing spondylitis. Am J Med 103:233–41 65. Maillefert JF, Aho LS, El Maghraoui A, Dougados M, Roux C (2001) Changes in bone density in patients with ankylosing spondylitis: a two-year follow-up study. Osteoporos Int 12:605–9 66. Marker-Hermann E, Frauendorf E, Zeidler H, Sieper J (2004) [Pathogenesis of ankylosing spondylitis – mechanisms of disease manifestation and chronicity]. Z Rheumatol 63:187–92 67. Martindale J, Smith J, Sutton CJ, Grennan D, Goodacre L, Goodacre JA (2006) Disease and psychological status in ankylosing spondylitis. Rheumatology (Oxford) 68. Mau W, Zeidler H, Mau R, Majewski A, Freyschmidt J, Stangel W, Deicher H (1988) Clinical features and prognosis of patients with possible ankylosing spondylitis. Results of a 10-year followup. J Rheumatol 15:1109–14 69. Mau W, Zeidler H, Mau R, Majewski A, Freyschmidt J, Stangel W, Deicher H (1990) Evalua- tion of early diagnostic criteria for ankylosing spondylitis in a 10 year follow-up. Z Rheuma- tol 49:82–7 70. McMaster MJ (1997) Osteotomy of the cervical spine in ankylosing spondylitis. J Bone Joint Surg Br 79:197–203 71. McVeigh CM, Cairns AP (2006) Diagnosis and management of ankylosing spondylitis. BMJ 333:581–5 72. Min K, Hahn F, Leonardi M (2007) Lumbar spinal osteotomy for kyphosis in ankylosing spondylitis: the significance of the whole body kyphosis angle. J Spinal Disord Tech 20:149–53 73. Mummaneni PV, Mummaneni VP, Haid RW, Jr, Rodts GE, Jr, Sasso RC (2003) Cervical oste- otomy for the correction of chin-on-chest deformity in ankylosing spondylitis. Technical note. Neurosurg Focus 14:e9 74. Murrey DB, Brigham CD, Kiebzak GM, Finger F, Chewning SJ (2002) Transpedicular decom- pression and pedicle subtraction osteotomy (eggshell procedure): a retrospective review of 59 patients. Spine 27:2338–45 75. Nakstad PH, Server A, Josefsen R (2004) Traumatic cervical injuries in ankylosing spondyli- tis. Acta Radiol 45:222–6 76. Nikolaisen C, Nossent H (2005) Early histology in ankylosing spondylitis related spondylo- discitis supports its inflammatory origin. Scand J Rheumatol 34:396–8 77. Olerud C, Frost A, Bring J (1996) Spinal fractures in patients with ankylosing spondylitis. Eur Spine J 5:51–5 1084 Section Tumors and Inflammation 78. Payer M (2006) Surgical management of cervical fractures in ankylosing spondylitis using a combined posterior-anterior approach. J Clin Neurosci 13:73–7 79. Ramos-Remus C, Russell AS, Gomez-Vargas A, Hernandez-Chavez A, Maksymowych WP, Gamez-Nava JI, Gonzalez-Lopez L, Garcia-Hernandez A, Meono-Morales E, Burgos-Var- gas R, Suarez-Almazor ME (1998) Ossification of the posterior longitudinal ligament in three geographically and genetically different populations of ankylosing spondylitis and other spondyloarthropathies. Ann Rheum Dis 57:429–33 80. Rudwaleit M, Metter A, Listing J, Sieper J, Braun J (2006) Inflammatory back pain in anky- losing spondylitis: a reassessment of the clinical history for application as classification and diagnostic criteria. Arthritis Rheum 54:569–78 81. Rudwaleit M, Sieper J (2005) [Early diagnosis of spondyloarthritis with special attention to the axial forms]. Z Rheumatol 64:524–30 82. Ruf M, Wagner R, Merk H, Harms J (2006) [Preoperative planning and computer assisted surgery in ankylosing spondylitis]. Z Orthop Ihre Grenzgeb 144:52–7 83. Ryan PJ, Fogelman I (1995) The bone scan: where are we now? Semin Nucl Med 25:76–91 84. Schroder J, Liljenqvist U, Greiner C, Wassmann H (2003) Complications of halo treatment for cervical spine injuries in patients with ankylosing spondylitis – report of three cases. Arch Orthop Trauma Surg 123:112–4 85. Schroder R, Urbach H, Zierz S (1994) Cauda equina syndrome with multiple lumbar diver- ticula complicating long-standing ankylosing spondylitis. Clin Investig 72:1056–9 86. Scudese VA, Calabro JJ (1963) Vertebral wedge osteotomy. Correction of rheumatoid (ankylosing) spondylitis. JAMA 186:627–31 87. Sieper J, Rudwaleit M, Khan MA, Braun J (2006) Concepts and epidemiology of spondylo- arthritis. Best Pract Res Clin Rheumatol 20:401–17 88. Simmons EH (1977) Kyphotic deformity of the spine in ankylosing spondylitis. Clin Orthop Relat Res:65–77 89. SimsAM,BarnardoM,HerzbergI,BradburyL,CalinA,WordsworthBP,DarkeC,Brown MA (2007) Non-B27 MHC associations of ankylosing spondylitis. Genes Immun 8:115–23 90. Smith-Petersen M, Larson C, Aufranc O (1945) Osteotomy of the spine for correction of flexion deformity in rheumatoid arthritis. J Bone Joint Surg Br 27:1–11 91. Sturzenbecher A, Braun J, Paris S, Biedermann T, Hamm B, Bollow M (2000) MR imaging of septic sacroiliitis. Skeletal Radiol 29:439–46 92. Suk KS, Kim KT, Lee SH, Kim JM (2003) Significance of chin-brow vertical angle in correc- tion of kyphotic deformity of ankylosing spondylitis patients. Spine 28:2001–5 93. Timms AE, Crane AM, Sims AM, Cordell HJ, Bradbury LA, Abbott A, Coyne MR, Beynon O, Herzberg I, Duff GW, Calin A, Cardon LR, Wordsworth BP, Brown MA (2004) The inter- leukin 1 gene cluster contains a major susceptibility locus for ankylosing spondylitis. Am J Hum Genet 75:587–95 94. Toussirot E, Michel F, Wendling D (2001) Bone density, ultrasound measurements and body composition in early ankylosing spondylitis. Rheumatology (Oxford) 40:882–8 95. Urist MR (1958) Osteotomy of the cervical spine; report of a case of ankylosing rheumatoid spondylitis. J Bone Joint Surg Am 40-A:833–43 96. van der Heijden IM, Wilbrink B, Tchetverikov I, Schrijver IA, Schouls LM, Hazenberg MP, Breedveld FC, Tak PP (2000) Presence of bacterial DNA and bacterial peptidoglycans in joints of patients with rheumatoid arthritis and other arthritides. Arthritis Rheum 43: 593–8 97. van der Linden S, Valkenburg HA, Cats A (1984) Evaluation of diagnostic criteria for anky- losing spondylitis. A proposal for modification of the New York criteria. Arthritis Rheum 27:361–8 98. van Royen BJ, de Kleuver M, Slot GH (1998) Polysegmental lumbar posterior wedge osteo- tomies for correction of kyphosis in ankylosing spondylitis. Eur Spine J 7:104–10 99. Van Royen BJ, Kastelijns RC, Noske DP, Oner FC, Smit TH (2006) Transpedicular wedge resection osteotomy for the treatment of a kyphotic Andersson lesion-complicating anky- losing spondylitis. Eur Spine J 15:246–52 100. van Royen BJ, Slot GH (1995) Closing-wedge posterior osteotomy for ankylosing spondyli- tis. Partial corpectomy and transpedicular fixation in 22 cases. J Bone Joint Surg Br 77: 117–21 101. van Tubergen A, Hidding A (2002) Spa and exercise treatment in ankylosing spondylitis: fact or fancy? Best Pract Res Clin Rheumatol 16:653–66 102. Wanders A, Heijde D, Landewe R, Behier JM, Calin A, Olivieri I, Zeidler H, Dougados M (2005) Nonsteroidal antiinflammatory drugs reduce radiographic progression in patients with ankylosing spondylitis: a randomized clinical trial. Arthritis Rheum 52:1756–65 103. Wang YF, Teng MM, Chang CY, Wu HT, Wang ST (2005) Imaging manifestations of spinal fractures in ankylosing spondylitis. AJNR Am J Neuroradiol 26:2067–76 104. Webb JK (2006) Ankylosing spondylitis. In: Aebi M, Arlet V, Webb JK (eds) AO Spine Man- ual. Clinical applications, vol 2. Thieme, Stuttgart, pp 319–327 105. Weber U, Pfirrmann CW, Kissling RO, Hodler J, Zanetti M (2007) Whole body MR imaging Ankylosing Spondylitis Chapter 38 1085 in ankylosing spondylitis: a descriptive pilot study in patients with suspected early and active confirmed ankylosing spondylitis. BMC Musculoskelet Disord 8:20 106. Wilkinson M, Bywaters EG (1958) Clinical features and course of ankylosing spondylitis; as seen in a follow-up of 222 hospital referred cases. Ann Rheum Dis 17:209–28 107. Will R, Palmer R, Bhalla AK, Ring F, Calin A (1989) Osteoporosis in early ankylosing spon- dylitis: a primary pathological event? Lancet 2:1483–5 108. Willems KF, Slot GH, Anderson PG, Pavlov PW, de Kleuver M (2005) Spinal osteotomy in patients with ankylosing spondylitis: complications during first postoperative year. Spine 30:101–7 109. Zdichavsky M, Blauth M, Knop C, Lange U, Krettek C, Bastian L (2005) [Ankylosing spon- dylitis. Therapy and complications of 34 spine fractures]. Chirurg 76:967–75 110. Zochling J, van der Heijde D, Burgos-Vargas R, Collantes E, Davis JC, Jr, Dijkmans B, Dou- gadosM,GeherP,InmanRD,KhanMA,KvienTK,Leirisalo-RepoM,OlivieriI,PavelkaK, SieperJ,StuckiG,SturrockRD,vanderLindenS,WendlingD,BohmH,vanRoyenBJ, Braun J (2006) ASAS/EULAR recommendations for the management of ankylosing spon- dylitis. Ann Rheum Dis 65:442–52 1086 Section Tumors and Inflammation 39 Treatment of Postoperative Complications Martin Krismer, Norbert Boos Core Messages ✔ The best treatment for complications is their avoidance by careful preoperative planning ✔ Neurological complications are no more fre- quent in spinal than in musculoskeletal surgery ✔ Check risk factors for complications such as intraspinal pathology, previous surgery, aller- gies, medications and malnutrition ✔ Use standardized postoperative protocols to monitor the patient with regard to neurological and cardiopulmonary function as well as vascu- lar status (pulse oximetry) ✔ Try to stop bleeding from small lacerations of large veins by pressure and hemostatic agents ✔ Cover lacerations of the lungs with synthetic material ✔ Chylothorax is initially treated by parenteral nutrition ✔ Hypoliquorrhea syndrome usually occurs with tiny dural defects and not with large lacerations Frequency of Complications The rate of complications with spinal procedures is dependent on the type of sur- gery, the spinal pathology,the experience of the surgeon and confounding factors such as age and comorbidities. These factors have to be taken into account in the discussion of complications. Cervical Spine Surgery Postoperative deterioration must be anticipated in cases of preexisting myelopathy In 450 cases of anterior cervical discectomy, worsening of the preexisting cervi- cal myelopathy occurred in 3.3% and infection in 1.6%. Additional radiculopa- thy occurred in 1.6%, recurrent nerve palsy in 1.3%, and Horner’s syndrome in 1.1%. An epidural hematoma was seen in 0.9%. Furthermore, single cases of pharyngeal lesion, meningitis due to a dural leak, and an epidural abscess were found [9]. In decompression for ossification of the posterior longitudinal liga- ment the neurological complication rate was 3.6% [85]. In anterior fusion in 488 patients, a dural tear occurred in 0.2%, dysphagia in 1.4%, a fractured vertebra in 0.2%, and vocal paresis in 0.8% [48]. In a report on 185 corpectomies,thever- tebral artery was injured in four patients [31]. Complications Section 1087 ab cd Case Introduction A 38-year-old male underwent lumbar discectomy at the level of L5/S1 for a left-sided radiculopathy with a sensory and motor (MRC Grade IV) deficit of the S1 nerve root. The microsurgical procedure was completed uneventfully. The patient reported immediately after surgery a substantial pain relief and improvement of the muscle force for plantar flexion of the left foot. At discharge, the patient felt well and was almost pain free. At 2 weeks postoperatively the patient consulted his family practitioner because of intermittent headache. The patient was treated symptomatically with NSAIDs. The symptoms increased and the patient again developed some minor leg pain for which he was referred again. On presen- tation, the patient complained of position-dependent headache which got worse after 15 – 20 min in the upright posi- tion. An MRI scan demonstrated a fluid collection at the level of surgery ( a, b, d). A contrast-enhanced MR scan allowed the exclusion of a recurrent herniation ( d). A hypoliquorrhea syndrome was suspected and the patient was reviewed. Intraoperatively, a medium size (5 cm) arachnoidal cyst was discovered which was opened. At the base of the cyst, a tiny dura lesion was discovered under the lamina of S1. It was assumed that the lesion only injured the dura but left the arach- noidea intact. This injury was obviously unnoticed intraoperatively because no CSF leak occurred. The cyst was resected. The dura lesion was sutured with 5-0 Prolene and covered with Dura-Gen and fibrin clue. The patient completely recov- ered and was symptom free at 2 months follow-up. This case demonstrates that a hypoliquorrhea syndrome is most often observed not with large but with a tiny dura lesion which forms a valve mechanism. We recommend repairing all iatrogenic arachnoidal cysts when noticed intraoperatively to avoid this complication. 1088 Section Complications Anterior Spine Surgery Serious complications are rare In anterior approaches to the adult thoracic or lumbar spine, serious complica- tions are relatively rare. In two large studies (n=1223 [33], n =447 [77]), the major complications were: death: 0.3%, 0.4% paraplegia: 0.2%, 0.4% deep wound infection: 0.6%, 1.1% In a report on 205 disc prostheses enrolled in a prospective FDA study [11], the major complications were: death: 0.5% (anesthesia related) neurological deficit: 0% deep wound infection: 0% (superficial 6.3%) The overall complication rate for idiopathic scoliosis was 5.2% for anterior, 5.1% for posterior, and 10. 2 % for combined anterior and posterior procedures according to a study by the Scoliosis Research Society [21] based on 6334 cases submitted to the study in the years 2001, 2002, and 2003 ( Table 1). Table 1. Complications in adolescent idiopathic scoliosis surgery [21] Anterior Posterior Combined pulmonary 1.5% 1.0% 3.5% wound infection 0.2% 1.3% 1.4 % non-fatal hemorrhagic 0.3% 0.1 % 0.3 % implant related 1.4% 0.6 % 1.0 % neurological 0.3% 0.2% 0.1% dural tear 0.3% 0.2% 0.1% deep venous thrombosis 0.0% 0.1 % 0.0 % In a French deformity surgery cohort, 90% scoliosis, 10% kyphosis (n=3311), the overall complication rate was 21.3%. Infection occurred in 4.7% and neuro- logical complications in 1.8% [43]. Disc Herniation and Spinal Stenosis Several papers reported on complications in surgery for disc herniation [62], or posterior procedures, where decompression of disc herniation or of spinal steno- sis contributed to 84% of the cases, and where fractures, infections and malig- nant lesions were excluded [26]. In 27576 and 18122 operations death occurred in 0.5% (within 30 days) and 0.07%, respectively. Mortality depended strongly Perioperative mortality depends on age and comorbidities on age, being 0% up to the age of 40 years, and 0.6% at the age of 75 years and over [26]. Most deaths occur in elderly patients due to: cardiac infarction heart failure central nervous system complications septic shock The incidence of an iatrogenic neurological deficit was cited as 1.0% for disc her- niation and 1.8% for stenosis [85]. A dural leak occurred in 1.4%. The incidence of a leak decreased with increasing surgical experience from 3.1% (experience 1–6 years) to 1.1% (>15 years), whereas the surgeon’s experience did not influ- ence the rate of neurological complications. Treatment of Postoperative Complications Chapter 39 1089 Lumbar Spinal Fusion The overall early complication rate in a prospective randomized trial [38] on 211 patients was 6% in posterolateral fusion without instrumentation, 18% with posterior instrumentation, and 31% in circumferential fusion. The complica- tions consisted of: infection rate: 3.6% (5 of 140 posterior fusions) injury to the sympathetic trunk: 3.7% injury to iliac veins: 3.7% new nerve root pain: 7.1% Comparison of Complications Complications are no more frequent than in other musculoskeletal surgery Spine surgery is no more prone to complications than other major orthopedic interventions. Lethal and even neurological complications occur more often in hip, knee and shoulder arthroplasty than in spine surgery ( Table 2). Table 2. Complications in musculoskeletal surgery Death Neurological lesions Infection References spinal surgery 0.2% 1.1% 1.6% Coe et al. (2006) [21] hip arthroplasty 1.0% 1.3% 0.2% Mahomed et al. (2003) [73] Schmalzried et al. (1991) [102] knee arthroplasty 0.6% 1.3% 0.4 % Katz et al. (2004) Schnisky et al. (2001) [101] revision hip arthroplasty 2.6% 3.2% 1.0% Mahomed et al. (2003) [73] Schmalzried et al. (1991) [102] surgery for anterior glenohumeral instability – 1–8% – Boardman et al. (1999) [12] rotator cuff repair – 1–2% 1.8% Boardman et al. (1999) [12] Herrera et al. (2002) [54] shoulder arthroplasty 0.2–0.6% 1–4% 1.1% Boardman et al. (1999) [12] Farmer et al. (2006) [35] Sperling et al. (2001) [106] Preventive Measures Better avoid than treat complications It is self-evident that it is better to avoid complications than to treat them. Com- plications cannot be avoided completely, but the best conditions can be created to obtain a low complication rate. This goal is achieved by: preoperative identification of risk factors patient referral to a larger center (in case of insufficient surgical experience) optimal patient preparation (e.g., correction of malnutrition) standardization of procedures postoperative checks to detect neurological, pulmonary, and cardiovascular deterioration It is quite obvious that an experienced specialist will cause fewer complications. Buttobeclear,experienceiswhatwegetwhencomplicationsoccurwhichwe have to manage. The experienced surgeon and much more so the surgeon’s patients have to pay a price for this experience. The opportunity to gain experi- ence must be weighed against the risk. This should be kept in mind when rare cases are selected for surgery. 1090 Section Complications Screening of Risk Factors A screening investigation of major risk factors (Table 3) is recommended in order to identify the population at risk. The screening should encompass a full medical examination. Table 3. Risk factors for complications Complications Risk factors excessive blood loss neuromuscular deformities (hypotonia, osteoporosis) neurofibromatosis (abnormal vascular anatomy) drugs (platelet inhibitors, anticoagulants) scar formations (previous surgery) arteriosclerosis (smoking) thromboembolic complications previous thromboembolic episodes malignant tumor paraplegia kyphosis congenital deformity preoperative neurological deficit spinal cord compression general complications malnutrition previous cardiac infarction or stroke neuromuscular diseases Risk Factors for Vascular Complications A detailed preoperative search for risk factors for vascular complications can help to minimize the surgical risk. The preoperative assessment should consider: previous surgery (e.g., of vessels, thorax, abdomen, spine, thyroid gland) history of coronary heart disease, high blood pressure, diabetes mellitus, transient ischemic attacks, thromboembolism [41, 98] claudication symptoms [2] clinical examination of pulses (leg, foot, carotid arteries) Routine radiographs of the spine may show extensive arteriosclerosis which may caution one to perform mobilization and retraction of vessels. It is debatable whether Doppler sonography is routinely necessary but it is indispensable if the patient reports a previous history of transient ischemic attacks or a murmur. Some situations should definitely be avoided, e.g., a bleeding vertebral artery with no information on the function of the contralateral artery, or the presence of an abdominal scar without knowledge of the type of the previous surgery (e.g., vascular prosthesis). It is not clear whether information on the circle of Willis is routinely necessary, which would require angiography (MR or conventional) in cervical spine cases. However, in the case of a stenotic vertebral artery this may be important information. Cardiovascular Risk F actors Cardiac complications are mainly myocardial infarction and heart failure. Stroke is a rare complication. Most case reports of strokes in spinal surgery are related to iatrogenic vertebral artery injury. In a few, carotid occlusion occurred. Afterpreviousmyocardialinfarctionandafterstroke,electiveprocedures should not be done within a period of 6 months if not imperative. For endoscopic Elective surgery after a myocardial infarction should be postponed for 6 months procedures it was shown that complications from an intervention in the first 30 days were no higher than in those patients operated on 6 months after myocar- dial infarction [18]. No information is available with regard to major orthopedic procedures. Treatment of Postoperative Complications Chapter 39 1091 Pulmonary Risk Factors Inability to climb more than two floors increases the risk of pulmonary complications Risk factors are chronic obstructive pulmonary disease (COPD), often caused by smoking, and restrictive lung disease especially in deformities. The ability to climb stairs may be a good indicator, e.g., the ability to climb three floors without interruption indicates a sufficiently good lung function. In COPD, it is important for the patient to sit upright postoperatively. Especially in muscular dystrophy (Duchenne’s disease), respiratory muscle training may increase preoperative vital capacity. Nevertheless, the surgical intervention should not be delayed, and it was recently shown that the outcome is no different in patients with a vital capacity 30%incomparisontothosewithvitalcapacity>30%[50]. Malnutrition as Risk Factor Malnutrition is a frequently underestimated risk factor. It is therefore necessary to routinely assess the nutritional status well in advance of elective major sur- gery. The assessment of nutritional parameters should include: albumin prealbumin total protein transferrin absolute lymphocyte count It was shown in prospective randomized trials [59, 69] that parenteral nutrition after surgery can reduce postoperative infections such as pneumonia or urinary tract infections. Malnutrition is frequently present in: Malnutrition is a frequently underestimated risk factor elderly people patients with neuromuscular diseases patients with malignant tumors staged operations [27] A preoperative high protein diet may therefore be beneficial [69]. Medication Aspirin should be stopped 10 days prior to surgery Platelet aggregation inhibitors such as acetylsalicylate and clopidogrel can con- siderably increase bleeding. They should be stopped 10 days before the planned intervention, or they should be replaced directly by low molecular weight heparin (LMWH). Non-steroid anti-inflammatory drugs (NSAIDs) may increase the effect of anticoagulants. If high doses of NSAIDs are taken, a preoperative change to paracetamol (in the absence of liver disease), tramadol or other opioids should be considered, in order to reduce the bleeding risk. Hormone replacement ther- apy in menopause and oral contraceptives both increase the risk of venous throm- bosis. Metformin in therapy of diabetic patients may be related to ahigher periop- erative risk of lactic acidosis. Therapy should be changed 48 h prior to surgery. Intraspinal and Nerve R oot Pathology Nerve root anomalies are not uncommon Conjoined nerve roots (two nerve roots in one foramen), and connecting roots may require decompression by foraminectomy or resection of a pedicle. In a recent study, the rate of conjoined nerve roots was found to be 5% [104]. Coronal magnetic resonance imaging (MRI) is the best method to detect these abnormali- ties. Intraspinal malformations and tethered cord are not a risk per se. However, an intraspinal abnormality seen on MRI in combination with either an abnormal 1092 Section Complications neurological examination and/or abnormal evoked potentials at preoperative baseline spinal cord monitoring indicates a spinal cord at risk [72]. The most important pathological findings indicating unsuspected neurological disorders are asymmetric abdominal reflexes. Always search for absent abdominal reflexes Theprevalenceoftethered cord in a Turkish study on 5499 schoolchildren was 0.1% in all children, and 1.4% in enuretic children [4]. In juvenile scoliosis [29] and in cases of hemivertebrae [6], more than 20% of patients showed spinal cord abnormalities on MRI such as Arnold-Chiari malformation, syringomyelia, diastematomyelia, or a low conus. Enuresis, gait disturbances, dermatologic signs of dysraphism, spina bifida on plain X-rays, and congenital deformities are frequently associated with tethered cord and cord malformations. MRI is recom- mended in these cases, and also in left thoracic idiopathic scoliosis. Preoperative Planning Theoperativestrategyhastobeclearlydefinedbeforetheintervention,andis based on imaging. Surprising findings concerning the extent of a tumor, con- joined nerve roots, or vessels entrapped in a scar can be ruled out or can be con- firmed in advance. Especially in deformities the direction of pedicle screws can be determined in advance with the help of a CT scan, if navigation is not avail- able. The fusion level must be determined in advance. In this context, the land- marks to determine the correct fusion levels should be assessed, e.g.: Anatomic structures are not reliable enough to determine the correct level Are there only 11 ribs? Is the C6 transverse process also prominent? Are there 6 lumbar vertebrae? Especial caution is necessary if the indication is based only on MRI findings in the upper lumbar or thoracic spine, such as endplate (Modic) changes, which cannot be seen in the image intensifier. Perioperative measures ( Table 4)are helpful to prevent complications. Table 4. Perioperative measures to prevent complications Cerv ical anterior Thoracic anterior Lumbar anterior Posterior Deformity surgery identify population at risk ✔✔✔✔✔ sufficient imaging ✔✔✔✔✔ somatosensoryandmotorevokedpotentials~~~~✔ pulse oximeter left leg – – ✔ ~~ positioning avoiding compression of the vena cava – – – ✔✔ cell saver technique ~ ~ ~ ✔✔ autologous blood donation – ~~~~ Note: ✔ in any case; ~ in selected cases Timing of Surgery A same day anterior and posterior procedure saves time and the nutrition status is better. However, the longer the operation, the more tired the surgeon and the higher the blood loss. A staged procedure may have advantages in the case of: myelopathy [114] anticipated excessive blood loss (coagulation disorders) very long surgeries (exceeding the patient’s or surgeon’s tolerance) Otherwise, simultaneous surgery (two surgeons operating on two approaches at the same time) [25] or same day anterior and posterior [119] procedures are Treatment of Postoperative Complications Chapter 39 1093 . defects and not with large lacerations Frequency of Complications The rate of complications with spinal procedures is dependent on the type of sur- gery, the spinal pathology,the experience of the. where decompression of disc herniation or of spinal steno- sis contributed to 84% of the cases, and where fractures, infections and malig- nant lesions were excluded [26]. In 27576 and 18122 operations. days) and 0.07%, respectively. Mortality depended strongly Perioperative mortality depends on age and comorbidities on age, being 0% up to the age of 40 years, and 0.6% at the age of 75 years and over