Sir,
Deep venous thrombosis (DVT) is a common medical problem with potentially fatal consequences.
Development of thrombi in proximal or distal veins is a characteristic feature of
DVT. Such emboli can travel from the lower limbs to the lungs resulting in pulmonary
embolism. Symptoms of pulmonary embolism include tachypnea, chest pain and at times
sudden death. Therefore it is essential that physicians have a high index of suspicion
for the signs of DVT.
Though DVT may be clinically silent, few clinical signs have been described to rule
it out. Pain or discomfort in calf, development of edema and distension of limb veins
preclude development of DVT. Perhaps for the diagnosis of DVT, no sign is more famous
than the Homan’s Sign.
1
Elicitation of the Homan’s sign involves forced dorsiflexion of the respective ankle
in the suspected limb.
However, the sign is not very reliable and often non-invasive diagnostic modalities
are necessary to confirm the diagnosis of DVT. Such modalities include ultrasonography
and venography of the affected limb.
The utility and use of the Homan’s sign has gradually waned down over the course of
time. Here we attempt to chronicle the history and the clinical significance of the
Homan’s sign.
The pathophysiology of the sign has been explained as follows. Passive, abrupt and
forced ankle dorsiflexion in concert with superadded knee flexion causes mechanical
traction on the posterior tibial vein. This traction stimulates the pain sensitive
structures in the lower limb.2, 3
Differential diagnosis of conditions that demonstrate a positive Homan’s sign include
intervertebral disc herniation, ruptured Baker’s cyst, neurogenic claudication, gastrocnemius
spasm, and cellulitis.
4
Another interesting phenomenon is seen in women who after chronically wearing high
heels start wearing flat shoes. In these women, sometimes due to mechanical traction
in the lower limb, a positive Homan’s sign can be demonstrated.5, 6
Significance of the Homan’s sign
Several studies have been conducted to ascertain the predictive value of Homan’s sign
for DVT.7, 8, 9, 10, 11, 12, 13
In one study involving control subjects and patients with lower limb thrombosis, phlebography
was used to evaluate certain clinical parameters, one of which was Homan’s sign. The
results showed that all the clinical signs were inconsistent. Homan’s sign was seen
in only 1/3rd of patients with actual thrombosis. On the other hand, it was seen in
21% of subjects without thrombosis as well.
10
Curiously, one study demonstrated that in patients with clinically suspected DVT,
Homan’s sign was more common in patients having a negative venogram than in patients
having a positive result.
12
Thus, after numerous studies, researchers and clinicians have reasonably come to the
conclusion that Homan’s sign is neither sensitive nor specific for the diagnosis of
DVT.
Reliable tests for diagnosing DVT
DVT is a serious condition with potentially fatal outcomes. As the efficacy of clinical
examination in ruling out DVT is fairly low, numerous diagnostic techniques using
both non-invasive and invasive instruments have been developed.
Impedance plethysmography calculates electrical impedance in the leg. Reduced impedance
correlates with venous occlusion and thrombosis. It is particularly helpful in diagnosing
proximal vein thrombi.
14
Compression ultrasonography is used to ascertain leg vein compressibility. Healthy
veins are compressible while thrombosed veins demonstrate reduced compressibility.
On comparison, compression ultrasonography has been shown to be slightly more reliable
than impedance plethysmography for diagnosis of DVT.
Venography is an invasive test and is extremely accurate for diagnosing DVT in proximal
as well as distal veins. It has been linked with causing DVT in 3% of patients.
15
An important study was conducted to ascertain the pretest probability of DVT using
a clinical evaluation model. This model categorizes patients into low-risk and high-risk
pretest probability groups.
16
Conclusion
DVT is a fairly important and common condition affecting numerous patients across
the globe. Since the complications of DVT are potentially fatal, its reliable diagnostic
modality is of utmost importance. A simple clinical exam and the Homan’s sign have
low sensitivity and specificity in diagnosing DVT; they can be of value if used in
addition to more accurate diagnostic procedures like ultrasonography and venography.
Homan’s sign though unreliable holds great historical importance and has been momentous
in our quest over the decades in achieving better diagnostic modalities for DVT. Thus
it continues to be practiced in medical colleges and private physician clinics across
the world because of its easy technique and simple demonstrability.
Conflicts of interest
None.
Disclosures
None.
Financial support
None.