The Dynamic Mobility of Vertebral Compression Fractures Volume 18:24-29, 2003 JBMR FERGUS McKIERNAN, RON JENSEN, TOM FRACISZEWSKI Marshfield Clinic, Wisconsin, USA Report: R3 范姜治澐 Supervisor: 李晏瑤主任

Introduction  Kyphoplasty Restore vertebral height Restore sagittal alignment Reduce chronic morbidity  Both vertebroplasty and kyphoplasty relieve fracture pain

Introduction  Dynamic mobility was seen in many vertebral compression fractures (VCFs)  Improve sagittal alignment can be also achieved during vertebroplasty  To define the magnitude and nature of dynamic mobility

Materials & methods  41 patients, 65 VCFs  Vertebral fracture pain (local knocking pain), impair activities, failure of medical therapy, technical feasibility, absent of contraindication

Pre-op evaluation  Standing A-P and lateral view centered on index vertebra  Supine cross-table lateral view  STIR-MRI 4-in foam bolster Index vertebra

Pre-op evaluation  Dynamic fracture mobility  Non-mobile  fixed compression fracture

Pre-op evaluation  Intravertebral clefts: low resistence, confluented reservoirs for PMMA Intravertebral gas Signal void PMMA fixation

Digitizing the lateral view  Hp: ab  Hm: cd  Ha: ef  Lateral vertebral area (LVA): ab x ae  Kyphotic angle (Ka): intersection of lines ae, bf

Pre-op evaluation  Fracture severity: Mild (20-25%) Moderate (25-40%) Severe (> 40%)

OP method  General anesthesia  Padded prone in extension  Mono- or bi-pedicular or para- pedicular  Barium-fortified PMMA  Kept supine 4h post-op  Dismissed the next day, follow-up 2 weeks later

Results  41 patients (28 F, 13 M)  46 procedures, 65 VCFs  Mean age: 75.4 y/o  Mean fracture age: 117 days  18 patients (44%) had at least one mobile VCF  23 mobile (35%), 42 non-mobile (65%)

Results  Bimodal distribution (midthoracic and T-L junction)  Fracture at T-L junction: 17 of 26 (65%) mobile  Intravertebral clefts presented in every mobile fracture, absent in every non-mobile (p<0.001) T-L junctionother Mobile17 (74%)6 Non-mobile9 (21%)33

Results  18 of 23 mobile fractures were severe, 5 were moderate Post-opAbsolute increaseP value Hp+ 15% Hm+ 93%P<0.001 Ha+ 106% (42%  70%)8.41 +/- 0.4mmP<0.001 LVA+ 67% (48%  80%)P<0.001 Ka+ 40% (-7.18°)P<0.001

Results  Mobile fractures underwent vertebroplasty earlier (89 vs 133 days) (p=0.15)  1.33 fractures per patient in patients with mobile fracture  1.83 fractures per patient in patients with only fixed fractures (p=0.29)

Results  Both mobile and non-mobile fractures reported significant pain relief post-op  No clinical adverse events  4 small intradiscal cement leaks, 1 leak into the anterior spinal venous plexus

Discussion  1/3 of all fractured vertebrae were mobile  Significant improvement in Ha, Hm, LVA and Ka  Most mobile fractures occurred at T-L junction (where bears greatest dynamic load)  Presence of intravertebral clefts

Implications  Fracture morphology (crush, biconcave, wedge) and severity need to accommodate the dynamic deformity  Vertebral height variance attributed to measurement error or “ rebound ”  Epidemiologic miscalculation and erroneous conclusions from therapeutic trials in which VCFs is the primary outcome

Discussion  Vertebral fracture mobility predicated on the “ permissive ” corticocancellous disruption, whether intrinsic or induced  More painful in mobile fractures (afferents from adjacent periosteum and ligment)

Discussion  Mechanisms of pain relief from vertebroplasty: Mechanical Neurolytic Thermal Chemical  Organization of hematoma and cicatrization of surrounding soft tissue result in early pain reduction

Discussion  Kummel ’ s disease Post-traumatic ischemic necrosis and collapse of vertebral body Osteoporotic elders with T-L junction fractures Risk for delayed ischemic necrosis Intravertebral vacuum cleft = Kummel ’ s sign Shared final pathway for certain high and low energy vertebral injuries

Limitation  Supine extension radiographic technique needs to be standardized  Limited patient numbers

Conclusion  Dynamic fracture mobility must be considered when performing vertebral augmentation, or any intervention that claims vertebral height restoration

 Thanks for your attention !!