Head-Shaft Angle Influences Isometric Shoulder Strength Levels after Intramedullary Nailing of Proximal Humerus...

Area of Science:

• Orthopedic surgery
• Biomechanics
• Geriatric medicine

Background:

• Proximal humerus fractures are common in the elderly, potentially impairing shoulder function long-term.
• Intramedullary nailing is a standard surgical treatment with good patient-reported and clinical outcomes.
• Shoulder strength testing is an underutilized yet valuable and standardizable outcome measure.

Purpose of the Study:

• To evaluate isometric shoulder strength in relation to fracture morphology and postoperative reduction quality.
• To correlate shoulder strength with patient-reported outcomes after proximal humerus fracture treatment.

Main Methods:

• Isometric shoulder strength (abduction, flexion) and hand-grip strength were tested in 25 elderly patients at 4.5 years post-surgery.
• Pre- and postoperative radiographs were analyzed for fracture morphology and reduction quality.
• Patients completed the American Shoulder and Elbow Surgeons (ASES) and Cleveland Musculoskeletal Society (CMS) questionnaires.

Main Results:

• Patients showed significant strength deficits in abduction (-24.47%) and flexion (-25.30%) compared to the uninjured arm.
• Abduction strength was lower in three- and four-part fractures and negatively correlated with patient satisfaction.
• Varus humeral head angulation resulted in significantly lower abduction strength, unlike anatomical reduction.

Conclusions:

• Proximal humerus fractures lead to significant, measurable reductions in shoulder function, confirmed by strength testing.
• Avoiding varus head angulation is crucial for optimizing shoulder strength and function post-fracture.
• Isometric strength testing is a practical and valuable addition to shoulder assessment following these fractures.