Hemophilia

Hemophilia is an X-linked recessive bleeding disorder affecting males.

Imaging Findings in Hemophilic Arthropathy

View larger

Hemophilia causes "joint AND muscle bleeds" — the muscle bleeds are their own orthopaedic emergencies and must not be forgotten alongside the hemarthroses.

• Iliopsoas hematoma - the great mimic. A spontaneous bleed into the iliopsoas presents with groin, lower-abdominal or hip pain, the hip held flexed and externally rotated, and pain on extension — mimicking a septic hip, an acute abdomen or appendicitis. Expansion in the iliacus compartment can compress the femoral nerve (quadriceps weakness, lost patellar reflex, anterior-thigh numbness). Diagnose with ultrasound or CT; treat with urgent factor replacement, rest and graded mobilisation — NOT primarily surgery.
• Compartment syndrome from a muscle bleed. A bleed into a closed fascial compartment (forearm, calf) can raise pressure enough to cause an acute compartment syndrome; the flexor-forearm bleed is the hemophilic route to a Volkmann ischaemic contracture. Treat with immediate factor correction; fasciotomy is reserved for an established compartment syndrome and only under full factor cover.
• Why it matters. These are the muscle counterparts of the hemarthrosis — treat with factor first, image second — and recognise the femoral-nerve palsy of the iliopsoas bleed and the contracture risk of an untreated forearm/calf bleed.

Hemophilia A vs B:

A swollen, painful joint in a young male is not always hemophilic hemarthrosis. The key orthopaedic discriminator is the bleeding history and coagulation profile.

The topic repeatedly quotes target factor levels (100% pre-op, 50-80% post-op) — here is the pharmacology that turns a target into a dose.

• The FVIII rule. 1 IU/kg of factor VIII raises the plasma level by about 2%. So to correct a severe patient (baseline near 0%) to 100%, give roughly 50 IU/kg. FVIII half-life is about 8-12 hours, so it is redosed roughly every 8-12 hours (or by continuous infusion) to hold the level.
• The FIX rule. 1 IU/kg of factor IX raises the level by about 1% (FIX distributes into the extravascular space, so more is needed) — roughly 100 IU/kg to reach 100%. FIX half-life is longer (about 18-24 hours), allowing less frequent dosing.
• Worked target. Major orthopaedic surgery: correct to ~100% immediately pre-op, then hold 50-80% for the first 1-2 weeks (tapering as healing progresses); minor procedures need lower peaks and shorter duration.
• The caveat. These arithmetic rules apply only to standard factor concentrates — they do NOT translate to emicizumab (not measured in factor units, and it interferes with one-stage FVIII assays) or to a patient with inhibitors (where bypassing agents, not factor arithmetic, are used). Always confirm the plan with haematology and a recovery study.

Global Epidemiology:

• Hemophilia A affects approximately 1 in 5,000 male births; Hemophilia B approximately 1 in 30,000 male births
• Hemophilia A accounts for roughly 80-85% of cases worldwide; Hemophilia B for 15-20%
• The World Federation of Hemophilia (WFH) Annual Global Survey identifies over 200,000 people with hemophilia, but case identification remains far below expected prevalence in low-income regions
• Around 30% of cases arise from de novo mutations with no family history

Side-by-Side Guidelines:

• Optimal prophylaxis target. Traditional regimens aim for troughs above 1%, but breakthrough bleeds still occur at this level. There is ongoing debate about individualised, higher-trough or pharmacokinetic-guided dosing versus fixed regimens, balanced against cost and venous access.
• Role of emicizumab in non-inhibitor patients. Non-factor therapy dramatically lowers bleeding rates, but long-term joint-protection data and its interaction with breakthrough bleeds requiring factor or bypassing agents are still maturing.
• Joint aspiration in acute hemarthrosis. Aspiration may relieve a tense effusion and reduce iron load, but carries infection and re-bleed risk; indications remain debated and it should never precede factor cover.
• Timing and choice of synovectomy. Radiosynovectomy, arthroscopic and open synovectomy all reduce bleeding, but comparative long-term superiority and the threshold for intervention are not firmly established; radionuclide availability drives practice regionally.
• Implant choice in arthroplasty. The balance between cemented vs cementless fixation and constrained vs less-constrained knee implants in young, often osteopenic hemophilic patients with deformity is unresolved.
• VTE prophylaxis after major surgery. Hemophilia is not fully protective against venous thromboembolism, especially with factor correction; whether and how to give chemical thromboprophylaxis perioperatively is genuinely uncertain and individualised with haematology.
• Gene therapy durability. AAV-mediated factor gene transfer can achieve sustained factor expression, but durability, hepatotoxicity, immune responses and long-term joint outcomes remain under active study.