Question 1

I had a hip replacement 8 weeks ago and my hip is getting stiffer instead of better—could this be heterotopic ossification?

Accepted Answer

Quite possibly. The classic presentation of HO is progressive stiffness developing 4-12 weeks after hip replacement, when you'd normally expect to be improving. This is different from normal post-operative stiffness which gradually improves with physiotherapy. Red flags for HO: (1) Stiffness getting worse instead of better despite physiotherapy; (2) Firm, non-tender mass you can feel around your hip; (3) Hip motion decreasing over weeks (measured by physio at each session); (4) Warmth around hip (inflammation as bone forms). Your doctor should: (1) Examine hip range of motion and compare to measurements from early post-op period (declining motion suggests HO); (2) Order repeat X-rays (though may be negative if less than 3-4 weeks since onset); (3) Check alkaline phosphatase blood test (elevated if active HO forming); (4) Consider bone scan if diagnosis uncertain (most sensitive early test). If HO confirmed, treatment options depend on severity: Mild HO (some stiffness but still functional)—observation, gentle physio, may stabilize without intervention. Moderate-severe HO (significant functional limitation)—continue gentle motion, wait 12-18 months for bone to mature, then consider surgical excision. Don't panic if diagnosed—most patients with mild-moderate HO adapt well and don't need surgery. Surgical excision reserved for cases causing major disability (can't sit in car, can't put on shoes, can't perform work duties).

Question 2

If I have surgery to remove the heterotopic bone, what are the chances it will just grow back?

Accepted Answer

Recurrence is the major concern after HO excision, but can be minimized with proper timing and prophylaxis. Recurrence rates: WITHOUT prophylaxis: 50-70% recurrence (very high—prophylaxis essential). WITH prophylaxis (NSAIDs or radiation): 10-20% recurrence (much better). TIMING CRITICAL—excision before bone mature: 40-50% recurrence; excision after bone fully mature (12-18 months): 10-20% recurrence. Keys to minimizing recurrence risk: (1) Wait for maturity—don't rush to surgery just because you're frustrated with stiffness. Surgeon confirms maturity with: alkaline phosphatase blood test normalized, bone scan shows decreased activity, X-rays stable over 3-6 months. Typical wait is 12-18 months from HO onset; (2) Prophylaxis after excision—either indomethacin 25mg three times daily for 6 weeks starting day of surgery, OR single-dose radiation therapy within 24-48 hours after surgery (radiation slightly more effective, ~5% lower recurrence, but has theoretical cancer risk). Most surgeons use radiation for revision cases or very high-risk patients, NSAIDs for first-time excision; (3) Gentle early mobilization—physiotherapy started day 1-2 after surgery with active range of motion, avoiding aggressive manipulation which may stimulate HO. Even with perfect technique and prophylaxis, 10-20% develop some recurrent HO, though usually less severe than original. If recurrence occurs, most patients still have better function than before excision. Repeat excision possible but has higher recurrence risk (20-30%).

Medical Disclaimer

Bone Growing in Wrong Places (After Hip Surgery or Injury)

📖What is Bone Growing in Wrong Places (After Hip Surgery or Injury)?

🔬What Causes It?

⚠️Risk Factors

You may be at higher risk if:

🛡️Prevention