Figure 2. Bone mineral density Distribution of bone mineral density (BMD) in healthy women aged 30 –40 years [46]. ence population. This so-called T-score is the number of SDs that the bone den- sity isabove or below the average value for thereference population. Four general diagnostic categories have been distinguished: BMD can be differentiated into four categories normal: BMD equal to or more than –1 SD (T-score –1) osteopenia: BMD between –1 SD and –2.5 SD (T-score <–1) osteoporosis: BMD less than –2.5 SD (T-score <–2.5) severe osteoporosis: BMD less than –2.5 SD in the presence of one or more fragility fractures. For diagnosis, measurements of BMD at the hip and the lumbar spine are the gold standard. Besides the diagnostic use of bone densitometry, these measurements have an additional prognostic value with respect to fracture probability: the age-adjusted relative increase in risk (e.g., of vertebral fracture) is 2.3 for every one SD decrease in lumbar BMD [61]. Classification of Vertebral Body Compression Fractures Unlike traumatic fractures, osteoporotic vertebral body fractures can be difficult to diagnose on conventional radiographs. The fracture patterns often do not fit into fracture classifications known from spinal trauma [60]. For this purpose morphometric criteria were established for diagnosing incident fractures ( Fig. 3) [28, 68]. From the spine surgeon’s perspective, the assessment of an osteoporotic fracture includes c onsideration of the following criteria ( Fig. 4): From a surgical perspective, the differentiation of acute and old fractures is most important acute and subacute single level fractures fractures with persistent instability (multiple) fractures with progressive/creeping vertebral collapse and loss of sagittal balance and posture vertebral fractures with subsequent spinal stenosis/neural compression Osteoporotic Spine Fractures Chapter 32 929 Figure 3. Morphometric criteria Typical morphometric criteria for diagnosing incident fractures: Melton [68] defines a vertebral fracture as present if any of the ratios AH/PH, MH/ PH, PH/PH1, PH/Ph-1 of a vertebra are less than 85% of the mean ratio in normal women for that vertebral level. Semiquantitative evaluation describes a mild grade 1 deformity as a 20–25% reduction in anterior, middle and/or posterior height and a 10– 20 % reduction in area. A mod- erate grade 2 deformity is defined as a 25 – 40% reduction in any height and a 20–40% reduction in area, and a severe grade 3 deformity is defined as a 40 % reduction in any height and area [28]. ab c d Figure 4. Spectrum of osteoporotic vertebral fractures a Simple compression fracture with ongoing pain 2 months after onset. b Non-union 6 months after fracture of T11. The persisting instability causes pain during change of position. c Fractures of multiple vertebrae are responsible for loss of posture and neck pain in order to compensate for the deformed thoracic spine. d Fracture of T7 with concomitant spinal canal encroachment and compression of the spinal cord. Clinical Presentation History The medical history appears crucial for the clinical appraisal. However, the symptoms are often misinterpreted. Overall, only about one-third of all vertebral Less than 10 % of VBCFs necessitate in-hospital treatment fractures come to clinical attention and less than 10% necessitate admission to hospital.Theincidenceofvertebralfracturesisunderreported.Thelowrateof clinical vertebral fracture diagnosis may be related in part to the lack of a trau- matic precipitating event (only 25% of vertebral fractures result from falls), and 930 Section Fractures Figure 5. The scale of vertebral fractures Data according to Cooper et al. [16]. therefore the symptoms are often misinterpreted as muscle strain instead. Most clinically diagnosed fractures (84%) are detected during investigation for back pain; the remaining 16% without pain may be old fractures that are detected incidentally during a radiological work-up ( Fig. 5)[92]. Most VBCFs cause acute sharp localized pain The cardinal symptoms of acute osteoporotic vertebral fractures are: acute onset, often initially breathtaking sharp localized, girdle like pain sensation of a crack in the back Pain persistence indicates further collapse risk Fractures are most often associated with physical activity (lifting of weights). However, they can also occur spontaneously. In the majority of patients, the pain subsides spontaneously within a couple of weeks. Persisting pain is a hallmark of ongoing instability with progressive loss of vertebral body height. Severe positional pain indicates putative non-union Therefore, patients should be monitored carefully with repeated X-ray examina- tions. Severe mechanical back pain for weeks or even months during positional changes (e.g., getting up from the supine position) leads one to suspect a non-union with persisting instability. This can be verified by comparing the standing X-ray with an investigation taken with the patient in the supine position such as an MRI scan ( Fig. 6 ). However, a hyperextension cross table view depicts the difference between the standing and supine positions more accurately. Diffuse mechanical back pain of the whole thoracic or lumbarspine can be found in severe osteoporosis. More and more frequently, we observe patients complaining about claudica- tion like symptoms or sciatica after a VBCF. Usually, the symptoms subside while lying down and are accentuated in the upright position. If a narrowing of the spi- nal canal occurs, the patient can present with: radiculopathy claudication symptoms myelopathic symptoms with gait abnormalities and/or ataxia (thoracic frac- tures) Osteoporotic Spine Fractures Chapter 32 931 ab Figure 6. Positional differences Patient with persisting pain 6 months after a T11 fracture. The pain is severe during the change from supine to sitting position. a The radiograph shows a nearly complete collapse of T11 with a severe kyphotic deformity. b In the MRI scan there is some degree of spontaneous correction of the kyphosis in comparison to the standing X-ray, which demon- strates the segmental instability. The history should also include a search for risks of a new osteoporotic fracture ( Table 2)[45]. Table 2. Risk factors for VBCF Age previous fragility fracture low bone mineral density (BMD, T-score) glucocorticoid therapy high bone turnover family history of hip fracture poor visual acuity low body weight neuromuscular disorders cigarette smoking excessive alcohol consumption long-term immobilization low dietary calcium intake vitamin D deficiency According to Kanis [45] 932 Section Fractures Physical Findings The clinical examination is rarely helpful for the diagnosis of a VBCF The clinical examination is not conclusive in the majority of cases. Frequent but non-specific physical findings are: local tenderness painful motion examination painprovocationinflexionandrarelyinextension A thorough neurological exam is compulsory However, a thorough neurological examination is absolutely mandatory to rule out a neural compression syndrome. It is recommended to measure the body height of patients. This can be used as a reference in further follow-up controls. Thesagittalbalanceofthespineshouldbeassessedbecauseasagittaldecompen- sation indicates an increased risk of progressive kyphosis. Furthermore, a thor- ough general medical assessment is required to rule out secondary causes of the fracture and to establish a differential diagnosis. Diagnostic Work-up Imaging Studies Standard Radiographs Standard radiographs remain essential for diagnosis The investigation of choice remains a standing X-ray of the region of interest in two planes. If there is a concordance of the clinical and imaging investigations, no further examinations are needed. The comparison with older X-rays can be help- ful (patients may have had previous chest X-rays). If the fracture pattern or the patient’s history (red flags, see Chapter 6 ) is not clear, further imaging studies are necessary. “Instability” can be identified by comparing a standing X-ray with the MRI or CT scan taken with the patient in a supine position. Alternatively, a hyperextension cross table view can provide the same information ( Fig. 6). This provides further information about the potential for achieving some reduction when the patient is positioned prone during surgery [66]. Computed Tomography CT best depicts the bony anatomy A CT scan can be useful for assessment of the bony anatomy. If the exact fracture pattern is difficult to appraise, a CT scan with reformatted pictures in the sagittal and coronal planes should be performed. The evaluation of tumors with a CT scan shows the exact bony destruction and is recommended before cement rein- forcement is considered. Magnetic Resonance Imaging MRI differentiates acute and old fractures An MRI investigation is recommended if the findings on standard X-rays are not obvious, especially if there are preexisting fractures of which the age is not known. The MRI though allows fresh osteoporotic fractures to be iden- tified. MRI differentiates tumor and osteoporosis Also a metastatic lesion can be ruled out on the MRI scan. The T2-weighted (T2W) image can depict a bone marrow edema which can be verified further with a fluid sensitive sequence [e.g., short tau inversion recovery sequence (STIR), Fig. 7, Table 3]. An osteoporotic fracture is differentiated from another pathologic fracture if the pattern of signal change in the T1W and especially in the T2W image is not as homogeneous. A high signal intensity in T1W images (resembling fat) argues for an osteoporotic fracture. Sometimes imaging is not Osteoporotic Spine Fractures Chapter 32 933 Figure 7. Differential diagnosis Comparison of MR findings of a metastatic lesion (rhabdomyosarcoma) and an osteoporotic fracture with T1- and T2-weighted images as well as with STIR sequences (see Table 2). Table 3. MR findings Pathology MR sequence T1W T2W STIR Osteoporotic fracture Dark signal Clear signal, located close to the fractured endplate Clear signal involving the whole vertebra Metastatic lesion Different patterns depending on the underlying tumor Signal change includes the major part of the vertebra Clear signal of the whole vertebra able to give a definitive answer. In these cases, a CT-guided biopsy should be obtained prior to cement reinforcement. Radionuclide Studies Radionuclide studies are helpful in differentiating tumors and generalized bone disease When a tumorous lesion or another generalized bone disease is suspected, a bone scan is indicated. Furthermore, if a patient is not suitable for an MRI scan (e.g., pacemaker, claustrophobia), a bone scan can be performed to detect a fresh frac- ture. Of note, a bone scan shows a high sensitivity but is not specific. Densitometry If a patient presents with an osteoporotic spine, the BMD should be determined. There are two methods for the assessment of the BMD. 934 Section Fractures Dual-Energy X-ray Absorptiometry DEXA has become the modality of choice for BMD assessment Dual-energy X-ray absorptiometry (DEXA) determines the bone density per area measured (mg/cm 2 ). For diagnosis, measurements of BMD at the hip and the lumbar spine are the gold standard. The method is simple, fast and reliable. It became the standard assessment for osteoporosis and is especially helpful in monitoring the effect of medical treatment. Besides the diagnostic use of bone densitometry, these measurements have an additional prognostic value with respect to fracture probability. High-Resolution Quantitative Peripheral Computed Tomography High-resolution quantitative peripheral computed tomography (hrpQCT) is a more sophisticated method for the assessment of the BMD. It allows a volumetric measure of the bone density (mg/cm 3 ) and can differentiate between cancellous and cortical bone. Despite the higher sensitivity of this method compared to DEXA, which allows small changes of bone density and structure also to be detected, it did not gain widespread use in clinical practice and is of more impor- tance in the scientific field [19]. Bone Biopsy A bone biopsy is required in equivocal cases of a tumorous lesion A biopsy is indicated if the preexisting cause of a fracture cannot be determined in order to rule out a tumorous lesion. It is not performed routinely although the incidence of unexpected cases of plasma cell dyscrasia in a series of 142 patients undergoing a kyphoplasty procedure was 3% [96]. In rare instances, assessment of bone metabolism necessitates a biopsy. Laboratory Investigations The laboratory work aims to rule out secondary osteoporosis and to investigate the bone metabolism: alkaline phosphatase: Raised serum levels are found in the presence of an increased bone turnover or mineralization disorders. In osteoporosis, the valuesareusuallywithinthenormalrangeorslightlyraised. osteocalcin: plays a role in the mineralization of the osteoid. Increased levels are found in renal failure and during treatment with calcitriol. deso xypyridinoline: This substance is released during bone resorption and secreted by the kidneys and can be traced in the urine. Table 4 provides an overview of the specific laboratory parameters for the evalu- ation of different aspects of bone metabolism disorders. Table 4. Laboratory assessment Level 1 (exclusion of secondary osteoporosis): Ca, P, alkaline phosphatase, osteocalcin, creatinine, bilirubin, SGOT, SGPT, BSR, serum and urine immunoelectrophoresis, blood cell count, urine status Level 2 (clinical suspicion of secondary osteoporosis): 25(OH)D 3 (malabsorption), parathyroid hormone, T4, TSH, testosterone, 1,25(OH) 2 D 3 (renal osteodystrophy) Level 3 (dynamics of bone metabolism): Osteocalcin (bone formation parameter), desoxypyridinoline/creatinine ratio (bone resorp- tion parameter) Osteoporotic Spine Fractures Chapter 32 935 Non-operative Treatment Conservative Fracture Management Carefully monitor patients to avoid progressive kyphotic collapse and sagittal imbalance Treatment of VBCF is empirical. Only about one-third of all fractures come to clin- ical attention and less than 10% necessitate hospital admission ( Fig. 5 ) [16]. In the latter group, however, a high percentage become chronically painful due to non- union or spinal deformity [16, 92]. Bed rest for a few days and pain medication are the first measures of treatment. Bracing may be applied, but this is often not suit- able in the older age group and the effect is questionable [51]. The first aim of con- servative treatment is to monitor the patient and avoid a collapse of a vertebral body with consecutive kyphosis and loss of sagittal balance. Pain is the crucial parameter.If there is any doubt,serial radiographic controlsshould be performed. Medical Treatment Every patient with VBCF should be evaluated by an osteologist Patients with fractures after inadequate trauma are likely to be osteoporotic. Besides the treatment of the fracture, patients should be evaluated by an osteolo- gist with regard to a formal assessment of bone metabolism and adequate medi- cal treatment. Osteoporosis requires appropriate systemic medical treatment Treatment of osteoporosis focuses on agents that: prevent bone loss increase bone mass Themaingoalofconservativetreatmentistoreducethenumberoffragilityfrac- tures. Osteoporosis, however, is a multifactorial disease, and skeletal fragility results from various factors. Thus, achievement of optimal bone metabolism should be the aim throughout life, by age-specific non-pharmacological inter- vention first and adequate medication where needed. In the past 10 years, large double-blind placebo-controlled trials have been performed to assess the efficacy of medical treatment in postmenopausal women with incident vertebral and non-vertebral fractures as a primary endpoint ( Table 5). The treatment focuses on: restoration/maintenance of calcium and vitamin D metabolism inhibition of bone resorption by biphosphonates Therelativefractureriskisreduced30–60%bythesedrugs.Theabsoluterisk reductionisbetween5%and10%.Outof1000womenwithosteoporosis,about Table 5. Pharmacological treatment for fracture prevention Drug V ertebral fractures Non-vertebral fractures Alendronate +++ ++ Calcitonin (nasal) + 0 Etidronate + 0 Fluoride ± – Hormone replacement therapy a +0 Parathyroid hormone b +++ ++ Raloxifene +++ 0 Risedronate +++ ++ Vitamin D derivatives ± 0 +++ strong evidence, ++ good evidence, + some evidence for the efficacy of treatment to pre- vent fractures (in addition to the effects of calcium and/or vitamin D based on RCT [20]), ± equivocal, 0 no effects, – negative effects. a Evidence derived mainly from observational studies. b Effect on hip fractures not documented. 936 Section Fractures Table 6. Risk reduction for vertebral fractures (according to Delmas [20]) Drug Mean age (years) Number of patients randomized Fracture incidence (%) Risk reduction (%) Placebo Drug Rel. Abs. Alendronate 5–10 mg 71 2007 15 8 47 7 Calcitonin 200 IU 69 557 16 11 25 4 Raloxifene 60 mg 68 1539 21 15 29 6 Risendronate 5 mg 69 1 628 16 11 25 5 Risendronate 5 mg 71 815 29 18 38 11 Recombinant human 1 –34 PTH 20 μg 69 892 14 5 64 9 150 will show a VBCF within one year. With medical treatment the number of fractures will be about 80 (9%). The absolute risk reduction is 6%, and the relative Approximately 15 % of individuals continue to experience pain despite osteoporosis treatment risk reduction is 60 out of 150 (40%) [20] (Table 6). However, as many as one- third of patients continue to experience pain. Approximately 15% of individuals continue to sustain fractures despite therapy. Furthermore there is a consider- able number of non-responders and non-compliant patients [20, 24, 58, 83]. Medical treatment includes ( Tables 4, 5): calcium vitamin D bisphosphonates raloxifene hormone replacement parathormone A calcium intake of at least 1 g per day should be achieved and is supplemented if dietary intake is not sufficient. Vitamin D intake is about 200–400 IU per day. Operative Treatment General Principles The majority of VBCFs respond well to non-operative treatment. However, about one-third of vertebral fractures become chronically painful [16] and 10% need hospital admission [92]. However, the number of patients who need surgical treatment remains obscure. The indications for and the goals of surgical treat- ment are ( Table 7): Table 7. Indications and goals for surgical treatment Indication Goal Mechanical pain Stabilization of the spine/vertebra Claudication/sciatica Decompression of the spinal canal (Severe) deformity Restoration of anatomy Surgical Principles ThesurgicalprinciplesapplicableforthetreatmentofVBCFsdepend on: fracture location type of fracture number of involved vertebrae compromise of neural structures Osteoporotic Spine Fractures Chapter 32 937 The spectrum of surgical options includes: simple percutaneous cement reinforcement (vertebroplasty) restoration of vertebral body height by kyphoplasty or lordoplasty open surgical intervention with decompression and instrumentation combined procedures with internal fixation and cement reinforcement Vertebroplasty Over the last decade, the approach towards osteoporotic VBCF has changed. The possibility of percutaneous cement injection into the vertebral body offers a new and extremely efficient treatment option. The technique is rather simple from a spine surgeon’s perspective. However, the critical aspect of the treatment repre- sents cement leakage. Following the technical recommendations ( Tables 8, 9), the procedure can be performed safely. Vertebroplasty is indicated after failed non-operative treatment The indications and contraindications for vertebroplasty (VB) are listed in Tables 10 and 11. The main indication represents acute and subacute VBCF due to osteoporosis after non-operative treatment has failed. In this group of patients, percutaneous reinforcement provides a major pain improvement in more than 80% of cases and prevents the further vertebral col- Table 8. Key points of surgical technique high quality C-arm direct cement application with small syringes (1 cc, 2 cc) guidewire cement with high radiopacity large diameter cannulas (8G) Cement with high/adapted viscosity Table 9. Steps of surgical technique positioning and monitoring of patient, i.v. line image control previous to draping, marking of levels to be treated local anesthesia in line with the pedicle (unless general anesthesia is used) stab incision and preliminary placement of guidewire(s) readjustment and definitive placement of guidewire(s) placement of filling cannulas preparation of cement according to recommendations of producer, distribution into small syringes cement application with adequate viscosity, high viscous cement is inserted with the aid of 1 cc syringes or the trocar cannula removal after curing of the cement Table 10. Indications for vertebroplasty ongoing pain for more than 2 weeks after occurrence of a new fracture severe pain; patients remain bedridden for more than 4 days progressive compression fractures of one or multiple vertebrae with subsequent loss of posture non-union with persisting instability (Kummel-Verneuil disease) combined procedures with internal fixation in severe osteoporosis Table 11. Contraindications for vertebroplasty pain unlikely to be related to a fracture infection blood clotting disorders neurological compromise impaired visibility during surgery poor general state of patient, unable to stand in prone position if an open procedure appears more appropriate 938 Section Fractures . causes of the fracture and to establish a differential diagnosis. Diagnostic Work-up Imaging Studies Standard Radiographs Standard radiographs remain essential for diagnosis The investigation of. (mg/cm 2 ). For diagnosis, measurements of BMD at the hip and the lumbar spine are the gold standard. The method is simple, fast and reliable. It became the standard assessment for osteoporosis and is. incision and preliminary placement of guidewire(s) readjustment and definitive placement of guidewire(s) placement of filling cannulas preparation of cement according to recommendations of producer,