Spinal Instability Neoplastic Score (SINS) Evaluation

Introduction to SINS

The American College of Radiology recommends using the Spinal Instability Neoplastic Score (SINS) to evaluate spinal instability in patients with metastatic spine disease, with a total score of 0-18 points, classifying lesions as stable (0-6), potentially unstable (7-12), or unstable (13-18) 1, 2, 3

The SINS score is a composite score that combines clinical and radiographic data to evaluate spinal stability in patients with metastatic spine disease, with components including location of the lesion, character of pain, bone quality, spinal alignment, degree of vertebral body collapse, and posterior involvement 1, 4
Junctional and mobile spine locations have a higher risk of instability 1, 2
Mechanical or postural pain is associated with a higher score 5
MRI T1-weighted and STIR sequences are optimal for evaluating bone quality and spinal alignment 1, 5
Subluxation or translation is associated with a higher score 6
De novo deformity (kyphosis or scoliosis) is associated with a moderate score 2

A SINS score of 0-6 indicates stability, 7-12 indicates potential instability, and 13-18 indicates instability 1, 2, 3
Patients with a SINS score of 13-18 have a higher risk of fracture or progression of fracture after radiation therapy 2

Non-contrast MRI sequences (T1-weighted and STIR) are best for delineating intraosseous disease 1, 5
Contrast-enhanced MRI is helpful for evaluating epidural, foraminal, and paraspinal disease 1, 5

SINS is used by spine oncology surgeons and radiation oncologists for treatment planning, including vertebral augmentation, percutaneous ablation, radiation therapy, or systemic chemotherapy 1, 5
Patients with a SINS score of 10-12 have a higher odds ratio for surgical management compared to those with a score of 7-9 1, 5

The SINS classification system divides spinal metastases into three categories that directly determine physical therapy eligibility, with patients having SINS 0-6 considered stable, SINS 7-12 considered potentially unstable, and SINS ≥13 considered unstable 7
Patients with SINS 7-12 require careful clinical judgment, modified activity restrictions, and consideration for neurosurgical referral, as they are at higher risk of instability 7

Pain character, such as mechanical or postural pain, is an important factor in determining SINS scores, with higher scores indicating greater instability 7

For patients with SINS 7-12, individualized assessment is required, with specific attention to pain character, and potentially requiring bracing or corset support before physical therapy 7

Post-operative physical therapy after surgical stabilization should include fractionated radiotherapy to prevent prosthesis failure and reduce need for subsequent surgery, as recommended by the European Society for Medical Oncology 8

For patients with SINS 7-12, clinical correlation with pain character, patient performance status, and multidisciplinary input is necessary, as SINS alone is not sufficient for determining physical therapy eligibility 7