Radiomic Modeling of Bone Density and Rib Fracture Risk After Stereotactic Body Radiation Therapy for Early-Stage Non-Small Cell Lung Cancer.

Purpose: Our purpose was to determine whether bone density and bone-derived radiomic metrics in combination with dosimetric variables could improve risk stratification of rib fractures after stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer (NSCLC). Methods and Materials: A retrospective analysis was conducted of patients with early-stage NSCLC treated with SBRT. Dosimetric data and rib radiomic data extracted using PyRadiomics were used for the analysis. A subset of patients had bone density scans that were used to create a predicted bone density score for all patients. A 10-fold cross validated approach with 10 resamples was used to find the top univariate logistic models and elastic net regression models that predicted for rib fracture. Results: A total of 192 treatment plans were included in the study with a rib fracture rate of 16.1%. A predicted bone density score was created from a multivariate model with vertebral body Hounsfield units and patient weight, with an R-squared of 0.518 compared with patient dual-energy x-ray absorptiometry T-scores. When analyzing all patients, a low predicted bone density score approached significance for increased risk of rib fracture (P = .07). On competing risk analysis, when stratifying patients based on chest wall V30 Gy and bone density score, those with a V30 Gy ≥30 cc and a low bone density score had a significantly higher risk of rib fracture compared with all other patients (P < .001), with a predicted 2-year risk of rib fracture of 28.6% (95% confidence interval, 17.2%-41.1%) and 4.9% (95% confidence interval, 2.3%-9.0%), respectively. Dosimetric variables were the primary drivers of fracture risk. A multivariate elastic net regression model including all dosimetric variables was the best predictor of rib fracture (area under the curve [AUC], 0.864). Bone density variables (AUC, 0.618) and radiomic variables (AUC, 0.617) have better predictive power than clinical variables that exclude bone density (AUC, 0.538). Conclusion: Radiomic features, including a bone density score that includes vertebral body Hounsfield units and radiomic signatures from the ribs, can be used to stratify risk of rib fracture after SBRT for NSCLC.

Recurrent Bilateral Basilar Joint Subluxation in a Teenage Boy.

Carpometacarpal (CMC) joint instability may be caused by either joint trauma or systemic ligamentous laxity in a setting of connective tissue disorders. Bilateral CMC joint dislocation is extremely rare and has only been described in 2 cases, both resulting from high-energy mechanisms in adults. Here, we present a case of recurrent, bilateral CMC joint subluxation and dislocation resulting from low-energy mechanisms in a pediatric patient with no diagnosable connective tissue disorder. Over a course of 4 years, the patient underwent 10 procedures, including bilateral closed reduction and immobilization, bilateral closed reduction and percutaneous pinning, bilateral tightrope placement, and eventual bilateral tightrope revision with anterior oblique ligament reconstruction. To date, the optimal treatment options for bilateral, low-energy CMC dislocations have not been well described, and these depend on the time from injury to closed reduction as well as postreduction joint stability. Tightrope placement and ligamentous reconstruction may be required in a setting of long-term instability.