Myositis ossificans is when bone starts to form inside a muscle, usually after a deep muscle bruise or trauma. Instead of healing normally, the muscle starts to calcify (harden), creating a lump of bone in the soft tissue.

An analogy…

Imagine you accidentally drop cement into a sponge. Over time, that soft sponge becomes hard and crusty in parts, that’s similar to how muscle turns hard when myositis ossificans develops.

What causes myositis ossificans?

It usually develops after a severe contusion or muscle strain, especially if there’s bleeding into the muscle (like in a quadriceps or hamstring). If the muscle is massaged too hard, stretched too early, or reinjured during healing, the body can send the wrong signals and start depositing bone tissue in the muscle.

What are the signs and symptoms of myositis ossificans?

• Firm, painful lump in the muscle, usually developing a few weeks after an injury
• Ongoing pain or tightness that doesn’t improve as expected
• Limited range of motion or stiffness near the affected area
• Pain that increases with activity or stretching
• Bruising and swelling may have been present in the early stages
• Visible on X-ray as a cloudy or hardened area in the muscle (usually after 3–4 weeks)

What tests are used to diagnose myositis ossificans?

Palpation: A firm, tender lump is often felt in the injured muscle.

Range of motion testing: Pain or restriction in movement.

X-ray: Reveals bone formation within the muscle (after about 3 weeks).

How long does myositis ossificans take to heal?

• Mild cases can settle in 6–8 weeks
• Moderate to severe cases may take 3 to 6 months to fully resolve
• In rare cases, surgery may be needed if the bone growth causes ongoing pain or limits function

How does myositis ossificans happen?

• Deep muscle contusions
• Aggressive massage or stretching too soon after injury
• Returning to sport too early after a muscle strain or tear
• Repeated trauma to the same area
• Poor injury management, especially ignoring swelling or bleeding
• Overtraining without proper recovery

What treatment can help myositis ossificans?

• Rest and protect the affected area from further trauma
• Ice therapy
• Gentle range-of-motion and strengthening exercises
• Monitor with X-ray to check the size and progress of the bone formation
• Iontophoresis or shockwave therapy 

What exercises or stretches can I do for myositis ossificans?

• Gentle range of motion exercises within pain-free limits
• Gradual strength training for surrounding muscles
• Stretching
• Balance and control exercises
• Low-impact aerobic training

What products can help with myositis ossificans?

• KT Pilates Band Pack
• KT Trigger Ball