Clinical Effect of Transverse Process Hook with K-Means Clustering-Based Stratification of Computed Tomography Hounsfield Unit at Upper Instrumented Vertebra Level in Adult Spinal Deformity Patients

Objective@#: This study aimed to investigate the efficacy of transverse process (TP) hook system at the upper instrumented vertebra (UIV) for preventing screw pullout in adult spinal deformity surgery using the pedicle Hounsfield unit (HU) stratification based on K-means clustering. @*Methods@#: We retrospectively reviewed 74 patients who underwent deformity correction surgery between 2011 and 2020 and were followed up for >12 months. Pre- and post-operative data were used to determine the incidence of screw pullout, UIV TP hook implementation, vertebral body HU, pedicle HU, and patient outcomes. Data was then statistically analyzed for assessment of efficacy and risk prediction using stratified HU at UIV level alongside the effect of the TP hook system. @*Results@#: The screw pullout rate was 36.4% (27/74). Perioperative radiographic parameters were not significantly different between the pullout and non-pullout groups. The vertebral body HU and pedicle HU were significantly lower in the pullout group. K-means clustering stratified the vertebral body HU ≥205.3, <137.2, and pedicle HU ≥243.43, <156.03. The pullout rate significantly decreases in patients receiving the hook system when the pedicle HU was from ≥156.03 to < 243.43 (p<0.05), but the difference was not statistically significant in the vertebra HU stratified groups and when pedicle HU was ≥243.43 or <156.03. The postoperative clinical outcomes improved significantly with the implementation of the hook system. @*Conclusion@#: The UIV hook provides better clinical outcomes and can be considered a preventative strategy for screw-pullout in the certain pedicle HU range.

The Fate of Proximal Junctional Vertebral Fractures after Long-Segment Spinal Fixation : Are There Predictable Radiologic Characteristics for Revision surgery?

Objective@#: To investigate the radiographic characteristics of the uppermost instrumented vertebrae (UIV) and UIV+1 compression fractures that are predictive of revision surgery following long-segment spinal fixation. @*Methods@#: A total 27 patients who presented newly developed compression fracture at UIV, UIV+1 after long segment spinal fixation (minimum 5 vertebral bodies, lowest instrumented vertebra of L5 or distal) were reviewed retrospectively. Patients were divided into two groups according to following management : revisional surgery (group A, n=13) and conservative care (group B, n=14). Pre- and postoperative images, and images taken shortly before and after the occurrence of fracture were evaluated for radiologic characteristics @*Results@#: Despite similar degrees of surgical correction of deformity, the fate of the two groups with proximal junctional compression fractures differed. Immediately after the fracture, the decrement of adjacent disc height in group A (32.3±7.6 mm to 23.7±8.4 mm, Δ=8.5±6.9 mm) was greater than group B (31.0±13.9 mm to 30.1±15.5 mm, Δ=0.9±2.9 mm, p=0.003). Pre-operative magnetic resonance imaging indicated that group A patients have a higher grade of disc degeneration adjacent to fractured vertebrae compared to group B (modified Pfirrmann grade, group A : 6.10±0.99, group B : 4.08±0.90, p=0.004). Binary logistic regression analysis indicated that decrement of disc height was the only associated risk factor for future revision surgery (odds ratio, 1.891; 95% confidence interval, 1.121–3.190; p=0.017). @*Conclusion@#: Proximal junctional vertebral compression fractures with greater early-stage decrement of adjacent disc height were associated with increased risk of future neurological deterioration and necessity of revision. The condition of adjacent disc degeneration should be considered regarding severity and revision rate of proximal junctional kyphosis/proximal junction failures.

The Fate of Proximal Junctional Vertebral Fractures after Long-Segment Spinal Fixation : Are There Predictable Radiologic Characteristics for Revision surgery?

Objective@#: To investigate the radiographic characteristics of the uppermost instrumented vertebrae (UIV) and UIV+1 compression fractures that are predictive of revision surgery following long-segment spinal fixation. @*Methods@#: A total 27 patients who presented newly developed compression fracture at UIV, UIV+1 after long segment spinal fixation (minimum 5 vertebral bodies, lowest instrumented vertebra of L5 or distal) were reviewed retrospectively. Patients were divided into two groups according to following management : revisional surgery (group A, n=13) and conservative care (group B, n=14). Pre- and postoperative images, and images taken shortly before and after the occurrence of fracture were evaluated for radiologic characteristics @*Results@#: Despite similar degrees of surgical correction of deformity, the fate of the two groups with proximal junctional compression fractures differed. Immediately after the fracture, the decrement of adjacent disc height in group A (32.3±7.6 mm to 23.7±8.4 mm, Δ=8.5±6.9 mm) was greater than group B (31.0±13.9 mm to 30.1±15.5 mm, Δ=0.9±2.9 mm, p=0.003). Pre-operative magnetic resonance imaging indicated that group A patients have a higher grade of disc degeneration adjacent to fractured vertebrae compared to group B (modified Pfirrmann grade, group A : 6.10±0.99, group B : 4.08±0.90, p=0.004). Binary logistic regression analysis indicated that decrement of disc height was the only associated risk factor for future revision surgery (odds ratio, 1.891; 95% confidence interval, 1.121–3.190; p=0.017). @*Conclusion@#: Proximal junctional vertebral compression fractures with greater early-stage decrement of adjacent disc height were associated with increased risk of future neurological deterioration and necessity of revision. The condition of adjacent disc degeneration should be considered regarding severity and revision rate of proximal junctional kyphosis/proximal junction failures.

The Clinical and Radiological Effect of Abnormal Axis after Cervical Arthroplasty

OBJECTIVE: The clinical outcomes according to the radiological results after cervical total disc replacement (TDR) are not well established. Here, the authors reviewed the clinical results according to the asymmetry in radiographs. METHODS: This retrospective analysis included patients after TDR (Mobi-C(R) disc) with at least 12 months follow up, and the clinical and radiological data were obtained preoperatively and postoperatively for 12 months. Clinical outcome measures numerical rating scale (NRS) score for neck pain, visual analog scale (VAS) for arm pain, and the Oswestry disability index (ODI) value. The asymmetries of TDRs were evaluated on the anterior-posterior (AP) and the lateral radiographs, and the radiographic adjacent segment degenerations were evaluated for 12 months. RESULTS: A total of 24 patients (one level cervical TDR; 10 male and 14 female; aged 41.50+/-8.35 years) were included in this study. The clinical results including NRS for neck pain, VAS for arm pain, and ODIs were similar between the normal and asymmetrized TDRs in AP and lateral radiographs. The radiographic adjacent segment degenerations were significantly increased in deviated TDRs (AP>10 mm asymmetry and lateral>10 mm asymmetry). CONCLUSION: Asymmetrical location of TDR is not related to the clinical outcomes, but related to the risk of radiographic adjacent disc segment degeneration.

High-Intensity Focused Ultrasound as Salvage Therapy for Patients With Recurrent Prostate Cancer After Radiotherapy

PURPOSE: To evaluate the oncologic outcomes and postoperative complications of high-intensity focused ultrasound (HIFU) as a salvage therapy after external-beam radiotherapy (EBRT) failure in patients with prostate cancer. MATERIALS AND METHODS: Between February 2002 and August 2010, we retrospectively reviewed the medical records of all patients who underwent salvage HIFU for transrectal ultrasound-guided, biopsy-proven locally recurred prostate cancer after EBRT failure (by ASTRO definition: prostate-specific antigen [PSA] failure after three consecutive PSA increases after a nadir, with the date of failure as the point halfway between the nadir date and the first increase or any increase great enough to provoke initiation of therapy). All patients underwent prostate magnetic resonance imaging and bone scintigraphy and had no evidence of distant metastasis. Biochemical recurrence (BCR) was defined according to the Stuttgart definition (PSA nadir plus 1.2 ng/mL). RESULTS: A total of 13 patients with a median age of 68 years (range, 60-76 years) were included. The median pre-EBRT PSA was 21.12 ng/mL, the pre-HIFU PSA was 4.63 ng/mL, and the period of salvage HIFU after EBRT was 32.7 months. The median follow-up after salvage HIFU was 44.5 months. The overall BCR-free rate was 53.8%. In the univariate analysis, predictive factors for BCR after salvage HIFU were higher pre-EBRT PSA (p=0.037), pre-HIFU PSA (p=0.015), and short time to nadir (p=0.036). In the multivariate analysis, there were no significant predictive factors for BCR. The complication rate requiring intervention was 38.5%. CONCLUSIONS: Salvage HIFU for prostate cancer provides effective oncologic outcomes for local recurrence after EBRT failure. However, salvage HIFU had a relatively high rate of complications.

Endovascular Treatment of Symptomatic High-Flow Vertebral Arteriovenous Fistula as a Complication after C1 Screw Insertion

High-flow vertebral arteriovenous fistulas (VAVF) are rare complications of cervical spine surgery and characterized by iatrogenic direct-communication of the extracranial vertebral artery (VA) to the surrounding venous plexuses. The authors describe two patients with VAVF presenting with ischemic presentation after C1 pedicle screw insertion for a treatment of C2 fracture and nontraumatic atlatoaxial subluxation. The first patient presented with drowsy consciousness with blurred vision. The diffusion MRI showed an acute infarction on bilateral cerebellum and occipital lobes. The second patient presented with pulsatile tinnitus, dysarthria and a subjective weakness and numbness of extremities. In both cases, digital subtraction angiography demonstrated high-flow direct VAVFs adjacent to C1 screws. The VAVF of the second case occurred near the left posterior inferior cerebellar artery originated from the persistent first intersegmental artery of the left VA. Both cases were successfully treated by complete occlusion of the fistulous portion and the involved segment of the left VA using endovascular coil embolization. The authors reviewed the VAVFs after the upper-cervical spine surgery including C1 screw insertion and the feasibility with the attention notes of its endovascular treatment.