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Tardy Spinal Cord Compression without Bone Cement Leakage after Kyphoplasty: A Report of 3 Cases

STUDY DESIGN: This is a case report. OBJECTIVE: We report here on three cases of late spinal cord compression without bone cement leakage after kyphoplasty from the view point of the common characteristics, the suspected etiologies and the performed treatments, and we propose a technique to prevent this kind of complication. SUMMARY OF THE LITERATURE REVIEW: Kyphoplasty is widely accepted as an effective and safe treatment for osteoporotic vertebral compression fracture (VCF). Complicated compression fractures and even bursting fractures with a compromised spinal canal are currently indicated for kyphoplasty. The wide spread application of kyphoplasty may be mainly due to reducing the complication rates associated with cement leakage and possible restoration, even though partially, of a vertebral kyphotic deformity. MATERIALS AND METHODS: we experienced three cases of newly emerged complications that caused delayed neurologic compromise after uneventful kyphoplasty without any immediate neurologic deficits. MR imaging was done to find the pathologic regions and surgical treatment was performed. RESULTS: Refracture of an augmented vertebra at the conus medullaris level can cause late occurring spinal cord compression without compromising the spinal canal. Posterior instrumentation and posterior fusion with posterior decompression were effective treatments. CONCLUSION: The anatomical peculiarity of the conus medullaris and the dynamic irritation of the spinal cord by a bone cement mass after refracture of an augmented vertebral body can be the causes of late spinal cord compression after kyphoplasty. The neurologic symptoms were treated by posterior decompression and fusion. This kind of complication can be prevented by injecting a sufficient amount of bone cement with a shape to support both endplates.

Lower-Pressure Percutaneous Vertebroplasty Using Larger-Diameter Bone-Cement Fillers

STUDY DESIGN: This is a retrospective, case-controlled study. OBJECTIVE: We wanted to evaluate the efficacy of lower-pressure percutaneous vertebroplasty (LP-PVP) using larger-diameter cement fillers for treating osteoporotic vertebral compression fracture (VCF). SUMMARY OF THE LITERATURE REVIEW: Despite the popularity of conventional PVP(C-PVP), critical complications associated with cement leakage have been widely reported due to the inadequate viscosity of flabby cement. MATERIALS AND METHODS: With excluding Kummell's disease, 23 VCF's were treated with LP-PVP using 2.8mm-diameter cement fillers, 51 VCF's were treated with kyphoplasty(KP) using the same size of cement fillers and 19 VCF's were treated with C-PVP using 1.4mm-diameter biopsy needles. The clinical and radiographic results along with the complications were investigated for more than one year. RESULTS: The visual analogue scale (VAS) was improved in all the groups. The infused cement volume was 5.9+/-1.6ml for the LP-PVP, 5.9+/-1.9ml for the KP and 3.5+/-1.0ml for the C-PVP (p=0.000). The collapsed vertebral height was restored by 10.8+/-10.3%, 13.0+/-12.7% and 4.7+/-7.6%, respectively, in each group (p=0.000) with a reduction loss of 2.1+/-1.8%, 1.1+/-1.4% and 5.9+/-4.2%. respectively, in each group (p=0.000) at follow-up. These was a reduction of the vertebral kyphotic angle by 3.0+/-4.0degrees, 3.7+/-4.4degrees and 4.2+/-4.4degrees, respectively, in each group (p=0.528) with reduction loss of 1.0+/-0.9degrees, 0.1+/-1.7degrees and 3.5+/-2.8degrees, respectively, in each group (p=0.000). There was a reduction of the regional Cobb's angle by 4.3+/-2.6degrees, 3.1+/-4.7degrees and 2.9+/-3.8degrees, respectively, in each group (p=0.184) with a reduction loss of 3.6+/-4.5degrees, 0.1+/-1.5degrees and 1.0+/-4.1degrees, respectively, in each group (p=0.000). Extravasation of cement was noticed in 6 cases (26.1%) of LP-PVP, in 14 cases (27.5%) of KP and 4 cases (26.1%) of C-PVP (p=0.689). No cases of additional VCF happened for the LP-PVP, eight cases of additional VCF happened (15.7%) for the KP and one case of additional VCF happened (5.3%) for the C-PVP (p=0.030). CONCLUSION: The LP-PVP showed clinically and radiologically results that were similar to those of KP with a higher amount of infused cement volume compared to that of C-PVP. LP-PVP is thought to be effective for the clinical and radiolographic aspects and to have fewer complications for the treatment of osteoporotic VCF.

The Efficacy of Kyphoplasty on Osteoporotic Vertebral Compression Fracture : A 1-Year Follow-up Study / 대한척추외과학회지

STUDY DESIGN: This is a retrospective study. OBJECTIVE: We wanted to evaluate the efficacy of kyphoplasty for treating osteoporotic VCF and we wanted to determine the risk factors for additional VCF. SUMMARY OF THE LITERATURE REVIEW: Successful pain relief with performing kyphoplasty for VCF has been well documented. However, unsatisfactory reduction and additional VCF are remained problems for kyphoplasty. MATERIALS AND METHODS: Sixty-three patients who underwent kyphoplasty were followed up for more than 1 year. The degree of reduction of the collapsed vertebral height, the vertebral kyphotic angle, the regional Cobb's angle and the overall sagittal alignment, the visual analogue scale (VAS), the fracture configuration, the bone mineral density (BMD), the presence of intradiscal cement leakage and additional VCF were investigated. The risk factors for additional VCF were analyzed. RESULTS: In terms of deformity correction, the collapsed vertebral height were restored (67.3+/-15.6% to 82.5+/-11.8%), the vertebral kyphotic angle was improved (12.1+/-6.9degrees to 8.1+/-5.3degrees ), the degree of the regional Cobb's angle was reduced (3.1+/-4.5degrees ) and the overall sagittal balance was improved (1.7+/-5.3 cm to 0.5+/-3.9 cm) with clinical satisfaction (VAS: 6.9+/-1.3 points to 2.3+/-0.9 points). But less than 40% of the patients reached the expected reduction criteria (the vertebral height > 90%, the vertebral kyphotic angle and regional Cobb's angle reduction > 5degrees ). Additional VCF occurred in 10 patients (15.9%). The average BMD in the additional VCF group was T-score of -3.8 and that for the no-additional VCF group was T-score of -3.0 (p=0.025). The degree of reduction under general anesthesia was twice more than that under local anesthesia. Eleven cases (17.5%) of intradiscal cement leakages were noticed, but this showed no relevance to the fracture configurations and additional VCF. The overall sagittal alignment and cement volume showed no relevance to additional VCF. CONCLUSION: Kyphoplasty was excellent for pain reduction, but it was unsatisfactory for correcting deformity. Vertebral height correction was more effectively performed under general anesthesia. Additional VCF was caused by severe osteoporosis.

Mechanical Properties of Blood-mixed PMMA in Percutaneous Vertebroplasty / 대한척추외과학회지

STUDY DESIGN: This is a mechanical study of polymethylmetacrylate(PMMA) mixed with blood as a filler. OBJECTIVE: We tried to change the properties of PMMA so that it is more suitable to use for percutaneous vertebroplasty (PVP). SUMMARY OF THE LITERATURE REVIEW: The mechanical changes by adding a filler into PMMA were expected to decrease the Young's modulus, the polymerization temperature and the setting time. These changes of PMMA were considered to be more suitable and adaptable conditions for PVP for treating osteoporotic vertebral compression fracture. MATERIALS AND METHODS: Porous PMMA was produced by mixing 2 ml (B2), 4 ml (B4) and 6 ml (B6)-blood as a filler, and the mechanical properties were investigated in comparison with regular PMMA(R) in view of Young's modulus, the polymerization temperature, the setting time and the optimal passing-time within the injectable viscosity (20~50N-needed) through a 2.8mm-diameter cement-filler tube. Porosity was inspected by performing microcomputated tomography (micro-CT). RESULTS: Young's modulus was decreased from 919.5 MPa (R) to 701 MPa (B2), 693.5 MPa (B4) and 545.6 MPa (B6) in each group. The polymerization temperature decreased from 74.2degrees C (R) to 59.8degrees C (B2), 54.2degrees C (B4) and 47.5degrees C(B6), respectively. The setting time decreased from 1065sec (R) to 624sec (B2), 678sec(B4) and 606sec (B6), respectively, and the optimal passing-time decreased from 75.6sec (R) to 46.6sec (B2), 65.0sec (B4) and 79.0sec(B6), respectively. The porosity increased from 4.2%(R) to 27.6%(B2), 27.5%(B4) and 29.5%(B6), respectively. A homogenous microstructure with very fine pores was seen on inspection of all the blood-mixed PMMAs. CONCLUSION: Blood mixed with PMMA was considered as an excellent filler that was easy to make and had good biocompatibility. The 6ml blood-mixed PMMA (B6) showed more suitable mechanical properties, including a decreased elastic modulus due to more porosity, less heating and a retarded optimal passing-time by the serum barrier, which diminished the friction between the PMMA and a cement-filler tube.

Precautions Against Infection Following Posterior Spinal Fusion Based on Types of Infection and Risk Factors / 대한척추외과학회지

STUDY DESIGN: This is a retrospective preparative study and prospective study OBJECTIVE: We instituted and verified the precautions against postoperative spinal infection. SUMMARY OF THE LITERATURE REVIEW: Postoperative infection comes from contamination during the operation and various strategies have been recommended to prevent it. MATERIALS AND METHODS: 583 cases that underwent instrumented posterior spinal fusion during two years (group I), were reviewed to discover the risk factors, and intraoperative cultures were done to detect the contamination routes and the causative microorganisms for the next 4 months. Six precautions, based on the results, were instituted. We analyzed 354 cases that underwent operation in the following year (group II) using the precautions. RESULTS: Twenty cases (3.4%) were infected in group I and the types of infection were superficial wound infection (4 cases), deep wound infection (4 cases), osteomyelitis around the interbody space (7 cases), osteomyelitis around the pedicle screws (4 cases) and a combination of wound infection and osteomyelitis around the pedicle screws (1 case). Infections happened more frequently in the cases of interbody fusion (p=0.034), revision (p=0.087) and those done in the summer season (p=0.025). S. epidermidis, as the causative bacteria, was cultured from both the operation environments and wounds. Six precautions based on the preliminary results were instituted as follows; irrigation method reformation, delayed opening of instruments, turning-off local air conditioners, changing of gowns before instrumentation, local bone irrigation and limited indications for interbody fusion. After implementation, two cases (0.6%) of infection developed in group II (p=0.002, odds ratio=0.160; 95% confidence interval = 0.037 to 0.688). CONCLUSION: Wounds, grafted bones or instruments can be contaminated under longer-time exposure to operating room air and so produce interbody or pedicle osteomyelitis without wound infection. The precautions were effective to decrease the postoperative infection rates following posterior spinal fusion.

Mechanical Properties of Blood-Mixed Polymethylmetacrylate in Percutaneous Vertebroplasty

STUDY DESIGN: Mechanical study of polymethylmetacrylate (PMMA) mixed with blood as a filler. PURPOSE: An attempt was made to modify the properties of PMMA to make it more suitable for percutaneous vertebroplasty (PVP). OVERVIEW OF LITERATURE: The expected mechanical changes by adding a filler into PMMA included decreasing the Young's modulus, polymerization temperature and setting time. These changes in PMMA were considered to be more suitable and adaptable conditions in PVP for an osteoporotic vertebral compression fracture. METHODS: Porous PMMA were produced by mixing 2 ml (B2), 4 ml (B4) and 6 ml (B6) of blood as a filler with 20 g of regular PMMA. The mechanical properties were examined and compared with regular PMMA(R) in view of the Young's modulus, polymerization temperature, setting time and optimal passing-time within an injectable viscosity (20-50 N-needed) through a 2.8 mm-diameter cement-filler tube. The porosity was examined using microcomputed tomography. RESULTS: The Young's modulus decreased from 919.5 MPa (R) to 701.0 MPa (B2), 693.5 Mpa (B4), and 545.6 MPa (B6). The polymerization temperature decreased from 74.2degrees C (R) to 59.8degrees C (B2), 54.2degrees C (B4) and 47.5degrees C (B6). The setting time decreased from 1,065 seconds (R) to 624 seconds (B2), 678 seconds (B4), and 606 seconds (B6), and the optimal passing-time decreased from 75.6 seconds (R) to 46.6 seconds (B2), 65.0 seconds (B4), and 79.0 seconds (B6). The porosity increased from 4.2% (R) to 27.6% (B2), 27.5% (B4) and 29.5% (B6). A homogenous microstructure with very fine pores was observed in all blood-mixed PMMAs. CONCLUSIONS: Blood is an excellent filler for PMMA. Group B6 showed more suitable mechanical properties, including a lower elastic modulus due to the higher porosity, less heating and retarded optimal passing-time by the serum barrier, which reduced the level of friction between PMMA and a cement-filler tube.

Posterior Lumbar Interbody Fusion with Cage and Local Bone Graft in Spondylolisthesis: Unilateral-caged versus Bilateral-caged / 대한척추외과학회지

STUDY DESIGN: Retrospective, controlled study OBJECTIVE: To compare one and two-caged posterior lumbar interbody fusion (PLIF) with local bone grafting for spondylolisthesis. SUMMARY OF LITERATURE REVIEW: Even though there are many reports on PLIF using cages and local bone grafting, Studies comparing one and two-caged PLIFs are rare. MATERIALS AND METHODS: Sixty-three patients who underwent pedicle screw fixated PLIF using cages and local bone grafts were followed for more than 1 year. Twenty-five patients had one cage (group I), and 38 patients had two cages (group II). Sampling error, disc height, sagittal Cobb angle, coronal Cobb angle, fusion rate, Oswestry disability index (ODI), operation time, blood loss, and neurologic complications were assessed. RESULTS: There was no sampling error between the two groups, except with regard to diagnosis: degenerative spondylolisthesis, 15 cases in group I and 9 cases in group II; spondylolytic spondylolisthesis, 10 cases in group I and 29 cases in group II (p=0.004). Fusion rates were 87.5% and 88.2% for groups I and II, respectively (p=1.000). More disc height loss occurred in group I (0.6 mm) than in group II (0.0 mm) (p=0.041). Over-3mm-disc height-losses were noted more frequently in group I (20%) than in group II (2.6%) (p=0.022). ODI improved from 28.1 to 12.3 (72.1% improvement) in group I and from 29.2 to 12.7 (79.3% improvement) in group II. There were no significant differences in operation time, amount of blood loss, or neurologic complications between the two groups. CONCLUSION: Unilateral one-caged PLIF with local bone grafting and posterior instrumentation was no different from bilateral two-caged PLIF with regard to fusion rates or radiologic or clinical results. The statistically significant differences in disc height seemed to be clinically insignificant. Disc height loss of greater than 3 mm was much more common in group I, with one-caged PLIF.

The Result of Early Decompression of Progressive Neurologic Deficit after Spine Surgery: A Case Report / 대한척추외과학회지

Two percent of neurological complications after spine surgery for various reasons have been reported. Most are static or improve with time. We encountered two cases of newly developed, progressive neurological deficits with severe pain radiating along the exiting root after posterior decompression, adhesiolysis, posterior lumbar interbody fusion (PLIF) with a cage for spinal stenosis after previous lumbar spine surgery. When explored, the severely tightened and less movable, edematous exiting root was entrapped by a pedicle without evidence of pedicle violation, direct injury, epidural hematoma or iatrogenic foraminal stenosis. A wider decompression with a resection of the pedicle reduced the root course and made it more movable. Immediately, the severe radiating pain subsided and the neurological deficit recovered. A progressive neurological deficit after spinal surgery for spinal diseases with foraminal stenosis can develop as a result of the inordinate manipulation of the root, which may provoke root edema, root self-entrapment around a pedicle and local ischemia. An image test and exploration should be performed immediately in cases of progressive single root neurological deficits immediately after spine surgery. Total decompression, even with a pedicle resection, should be considered to resolve the neurological deficits.