What is Hemarthrosis?
Hemarthrosis is bleeding into a joint space, most commonly affecting the knee, ankle, and elbow, characterized by an unusual sensation ("aura"), pain, swelling, warmth over the joint, and decreased range of motion or loss of function compared to baseline 1.
Clinical Features
According to the International Society on Thrombosis and Haemostasis (ISTH) guidelines, an acute joint bleed (hemarthrosis) presents with some or all of the following 1:
- "Aura" - an unusual sensation in the joint that often precedes other symptoms
- Pain - increasing discomfort in the affected joint
- Swelling - visible joint enlargement
- Warmth - increased temperature over the joint surface
- Decreased range of motion - progressive loss of movement compared to baseline
- Loss of function - difficulty using the limb
In infants and young children, reluctance to use the limb alone may indicate hemarthrosis 1.
Pathophysiology and Consequences
Blood in the joint is harmful to joint tissues. The presence of blood leads to chondrocyte apoptosis (cartilage cell death) and chronic synovitis, which eventually results in joint degeneration and arthropathy 2. Heme breakdown products and pro-inflammatory mediators have deleterious interactions with cartilage and synovium, accelerating degenerative changes 3, 4.
Common Causes
- Hemophilia - the most classic cause, where hemarthrosis is the clinical hallmark 2
- Trauma - joint injuries, particularly with ACL tears
- Spontaneous bleeding - rare, most prevalent in elderly patients with osteoarthritis, often from peripheral arteries supplying the posterior horn of the lateral meniscus 5
Distinguishing from Arthritis
In patients with advanced arthropathy, distinguishing acute hemarthrosis from arthritis-related pain can be challenging. Key differentiators include 1:
- Rapid resolution of pain following factor concentrate infusion suggests acute hemarthrosis
- Improvement of pain with rest after activity suggests chronic arthritis
Clinical Significance
Hemarthrosis requires prompt recognition and treatment to prevent long-term joint damage and the development of post-traumatic osteoarthritis 3, 4. Subclinical hemarthroses (bleeding without obvious symptoms) can occur and still lead to arthropathy, especially in the ankles 2.