Homans sign is a physical examination technique historically linked with the detection of deep vein thrombosis (DVT). This sign involves observing for discomfort or pain behind the knee or in the calf when the foot is forcibly bent upwards, known as dorsiflexion. It was first described by American surgeon John Homans, who later refined his definition to include increased resistance or involuntary knee flexion as positive responses, not just discomfort.
Purpose and Limitations
Homans sign was traditionally used to help identify the presence of deep vein thrombosis, a condition where blood clots form in the deep veins, often in the legs. The idea was that stretching the calf muscles and veins during dorsiflexion would cause pain if a clot were present, due to mechanical traction on the posterior tibial vein. However, modern medical understanding has significantly diminished its role as a reliable diagnostic tool for DVT.
The test has low sensitivity, meaning it frequently misses DVT when it is actually present. Its specificity is also low, indicating it can yield a positive result even when no DVT exists, due to other conditions like muscle strain, cellulitis, or a Baker’s cyst. Consequently, Homans sign alone cannot definitively diagnose or rule out DVT and is no longer considered a stand-alone diagnostic method in contemporary medical practice.
Performing the Maneuver
To perform Homans sign, the individual lies on their back with their leg extended. The examiner then gently lifts the affected leg, usually to about 10 degrees from the surface. While maintaining the knee in a straightened position, the examiner will then passively and abruptly bend the patient’s foot upward towards the shin.
During this motion, the examiner may also gently squeeze the calf muscle with their other hand. This maneuver elicits deep calf pain or tenderness. It is important to ensure the patient’s knee remains fully extended during the dorsiflexion to properly stretch the calf and posterior tibial vein.
Interpreting Findings and Next Steps
A “positive” Homans sign occurs when dorsiflexion of the foot causes pain or discomfort in the calf or behind the knee. Conversely, a “negative” Homans sign means no pain or discomfort is experienced during the maneuver. A positive Homans sign can also be caused by other conditions unrelated to DVT, such as muscle soreness, a pulled muscle, or sciatica. If DVT is suspected based on other symptoms, such as unexplained leg pain or tenderness, swelling, warmth, or redness in one leg, immediate medical attention is necessary. A healthcare professional will likely recommend more accurate diagnostic tools, such as a D-dimer blood test, or imaging like a duplex ultrasound of the affected limb, to confirm or rule out DVT.