Morphological Parameters of the Thoracic Pedicle in an Asian Population: A Magnetic Resonance Imaging-Based Study of 3324 Pedicles.

STUDY DESIGN: A cross-sectional magnetic resonance imaging (MRI)-based anatomical study. OBJECTIVES: Instrumentation of the thoracic spine may be challenging due to the unique pedicle morphology and the proximity of vital structures. As prior morphological studies have mostly been done in Caucasians, our study aims to determine the optimal pedicle screw size for transpedicular fixation in an Asian population. METHODS: A retrospective analysis of 400 patients who had undergone MRI of the thoracic spine was performed. A total of 3324 pedicles were included. Pedicle morphology was graded qualitatively based on the size of its cancellous channel, and quantitatively with the following parameters: pedicle transverse diameter, pedicle screw path length, and pedicle angle. Subgroup analysis based on gender was performed. RESULTS: Mean pedicle transverse diameter was the narrowest at the T4 (2.9 ± 1 mm) and T5 (3.1 ± 1.1 mm) level. The mean pedicle screw path length progressively increased from T1 (34 ± 4.6 mm) to T12 (47 ± 4.6 mm). The mean pedicle angle was the largest at T1 (34° ± 7.9°) and decreased caudally, to 9.4° ± 3.8° at the T12 level. Females had significantly lower mean pedicle diameter and screw path length than males at every vertebral level; however, they had a larger pedicle angle at T8 to T10. The most common size of the pedicle cancellous channel was more than 4 mm. CONCLUSION: Morphological differences in the Asian pedicle suggest that caution needs to be taken during thoracic spine instrumentation, particularly in Asian females who have significantly smaller pedicles. In such cases, the use of alternative techniques or intraoperative navigation may be useful.

The Oblique Corridor at L4-L5: A Radiographic-Anatomical Study Into the Feasibility for Lateral Interbody Fusion.

STUDY DESIGN: Cross-sectional radioanatomical study. OBJECTIVE: The aim of this study was to analyze the prevalence, size, and location of the oblique corridor (OC), and the morphology of the psoas muscle at the L4-L5 disc level. SUMMARY OF BACKGROUND DATA: Lateral lumbar interbody fusion via the OC has the advantage of avoiding injury to the psoas muscle and lumbar plexus. However, the varying anatomy of major vascular structures and the iliopsoas may preclude a safe oblique access to the L4-L5 level. METHODS: Five hundred axial magnetic resonance images of the L4-L5 disc level were shortlisted. OCs were categorized into four grades: Grade 0 = no corridor, Grade 1 = small corridor (≤1 cm), Grade 2 = moderate corridor (1-2 cm) and Grade 3 = large corridor (>2 cm). OC location was labeled as antero-oblique, oblique, or oblique-lateral. Psoas morphology was categorized based on a modified Moro's classification, where the anterior section was further subdivided into types AI-AIV. Oblique approach was considered nonviable either when there was no corridor due to vascular obstruction (Grade 0) or when the psoas was high-rising (Types AII-AIV). RESULTS: 10.5% of the selected 449 patients had no measurable OC (grade 0) at the L4-L5 level. There were 35% and 37.2% patients with a grade 1and 2 OC, respectively. The location of the OC was anterior oblique, oblique, and oblique lateral in 3.7%, 89.6%, and 6.7%, respectively. According to the modified Moro's classification, 19.4% had a high-rising psoas. Predominantly, psoas was either in line with the disc (Type I; 30.7%) or low-rising (Type AI; 47.4%). CONCLUSION: Twenty-five percent of the patients did not have an accessible OC either due to obstruction by vascular structures or due to a high-rising psoas. Hence, proper evaluation of the relevant anatomy preoperatively is recommended for early adopters of this technique, as varying anatomy precludes universal suitability of oblique lateral interbody fusion for the L4-L5 level. LEVEL OF EVIDENCE: 3.

Radiologic Findings in Polyarticular Amyloid Arthropathy and Myopathy in Multiple Myeloma: A Case Report.

BACKGROUND Amyloid arthropathy and myopathy are complications of amyloidosis that can be associated with non-specific imaging findings, which may be challenging to interpret. The report is of a case of polyarticular amyloid arthropathy and myopathy in a 56-year-old man with multiple myeloma and includes a description of the radiographic, computed tomography (CT), and magnetic resonance imaging (MRI) findings. CASE REPORT A 56-year-old man with multiple myeloma presented with chronic polyarticular pain and swelling. Soft tissue thickening of the wrist and knee were found on MRI to be of intermediate T1 weighted imaging (T1WI) and low to intermediate T2 weighted imaging (T2WI) signal intensity. Denervation muscle edema seen in the thenar muscles on the MRI of the right wrist were associated with carpal tunnel syndrome secondary to amyloid deposition. Soft tissue lesions in the periarticular regions of both hip joints were contiguous with subchondral bone lesions. Diffusely scattered myeloma lesions were shown as hyperintense on short tau inversion recovery (STIR) MRI imaging throughout the appendicular and axial skeleton, with vertebral compression fractures. Bilateral iliopsoas involvement with hypertrophy and abnormal surrounding fat reticulated signal intensity was consistent with amyloid myopathy. The patient had a pathological fracture of the right femoral neck and underwent surgical fixation. Histology of the right femoral head confirmed amyloid deposits. CONCLUSIONS Because the clinical presentation and imaging findings of musculoskeletal amyloidosis can be nonspecific, they can result in delay in diagnosis and treatment. Early radiologic identification of polyarticular amyloid arthropathy and myopathy should prompt confirmatory biopsy to confirm the diagnosis.

Torsion of the greater omentum: A rare preoperative diagnosis.

Torsion of the greater omentum is a rare acute abdominal condition that is seldom diagnosed preoperatively. We report the characteristic computed tomography (CT) scan findings and the clinical implications of this unusual diagnosis in a 41-year-old man, who also had longstanding right inguinal hernia. Awareness of omental torsion as a differential diagnosis in the acute abdomen setting is necessary for correct patient management.