Journal CME June 2026: Predictors of wrist extensor muscle recovery following acute traumatic spinal cord injury: A model systems replication study-PM R - 2025 - Johnson - Predictors of wrist extensor muscle recovery following acute traumatic spinal cord injury A model

PM R - 2025 - Johnson - Predictors of wrist extensor muscle recovery following acute traumatic spinal cord injury A model

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This retrospective replication study tested three classic clinical rules for predicting recovery of wrist extensor strength after acute high cervical spinal cord injury (SCI): preserved C5 sharp-dull discrimination, at least antigravity C5 motor strength, and trace C6 motor strength. Using the large SCI Model Systems database, the authors identified 219 eligible cases from 123 patients with C4 or C5 neurological level injuries and initial wrist extensor weakness.<br /><br />The main outcome was recovery to antigravity wrist extension (3/5) at 1 year. The study found that all three historical predictors were less accurate in real-world data than reported in the original small 1993 study. Positive predictive values were only moderate: 57% for C5 sharp-dull discrimination, 61% for C5 antigravity strength, and 74% for trace C6 strength. Negative predictive values were 66%, 82%, and 74%, respectively. Among the individual predictors, absent antigravity C5 strength was the best rule for predicting failure to recover, while trace C6 strength was the best predictor of recovery.<br /><br />A subanalysis of patients with early AIS B injuries showed slightly better predictive performance, but still not strong enough for sole clinical reliance. When combined, the three variables improved discrimination, with an overall ROC AUC of 0.78. The authors therefore created an updated branched nomogram to provide more nuanced prognostic guidance.<br /><br />Overall, the study concludes that the old rules should not be used with high certainty to predict who will regain useful wrist extension after SCI. Clinicians should interpret them cautiously and use the updated nomogram for better individualized prognosis.

Keywords

spinal cord injury

wrist extensor recovery

cervical injury

C5 motor strength

C6 motor strength

sharp-dull discrimination

predictive accuracy

retrospective replication

ROC AUC

prognostic nomogram