Purpose: To quantify how well the physical examination of the shoulder predicts patient-reported functional outcome in a cohort of patients with previous proximal humerus fractures.
Method: Potential subjects were identified from a recent study cohort of proximal humerus fracture patients treated within the past six years. The cohort consisted of all fracture types and treatment modalities. Participants underwent a focused physical examination of their injured shoulder containing the components of the Constant-Murley shoulder score: range of motion for forward flexion, abduction, internal rotation, external rotation, and abduction strength measured by an IsoBex muscle strength analyzer. Participants also completed the following patient-reported functional outcome questionnaires: Disabilities of Arm, Shoulder, Hand (DASH), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), Simple Shoulder Test (SST), and Oxford Shoulder Score (OSS). Forward- and backward-stepwise linear regression was used to assess the relationship between the functional outcomes and the physical exam measurements.
Results: Thirty-one subjects with a mean age of 70 ± 8 years participated. Sixteen patients were previously treated with ORIF and 15 were treated with sling immobilization. The mean physical examination measures were: flexion 117° ± 31°, abduction 117° ± 37°, internal rotation 7° ± 2°, external rotation 7° ± 4°, and strength 6 ± 5 Newtons. The mean functional outcome scores were: DASH 21 ± 19, ASES 82 ± 17, SST 8 ± 3, and Oxford 20 ± 8. Using linear regression, adjusted R-squared statistics suggest components of the physical exam can explain 38% of the Oxford, 50% of the DASH, 58% of the SST, and 70% of the ASES variance. Abduction strength was a significant predictor for all functional outcomes. Combinations of flexion, abduction, or internal rotation were also significant predictors depending on the outcome instrument being modeled.
Conclusion: Physical exam of the shoulder accounts for differing amounts of patient-reported functional outcome variance. Abduction strength is the most consistent predictor of functional outcome within this cohort of proximal humerus fracture patients.
