Myositis Ossificans (MO)
Myositis Ossificans is a complication that can occur after muscle injury, and is particularly prevalent in the athletic population and young adults. It is characterised by abnormal calcification/bone growth in healing muscle after injury and usually occurs in the larger muscle groups. Sports whose participants are particularly susceptible to developing MO include;
- contact sports where muscle contusion is common (e.g. rugby)
- sports that involve high velocity running (e.g. sprinting) where muscle tears are common
Myositis Ossificans is the most common form of Heterophic Ossification, the umbrella diagnosis for a group of conditions where there is formation of extraskeletal bone in soft tissues.
Clinical Presentation
- 46-year-old man
- Avid marathon runner
- Blunt trauma to left anterior thigh from fall on stairs 1 week ago
- DH – Nil anticoagulants. Nil else.
- PMH – Nil of note
- FH – Nil of note
- Examination left thigh
- Difficulty walking
- Large tense swelling
- No bruising
- Restricted range of knee flexion to 100 degrees
- Ultrasound in clinic demonstrated;
- Vastus Intermedius liquified haematoma
- No other muscle injury
- Patient had 60mls blood drained from haematoma on the same day and sent home with compression on thigh
Further injury and investigation
- Patient unfortunately sustained re-injury to quadriceps whilst walking the dog which resulted in fresh re-bleed and new calcification formation
- Range of knee flexion reduced further and now unable to flex beyond 80 degrees
- Repeat ultrasound and MRI show development of myositis ossificans in Vastus Intermedius
Imaging
- Top left – Preliminary Ultrasound showing haematoma pre-drainage
- Top right – Repeat Ultrasound after re-injury showing initial calcification deposits
- Bottom left – MRI after re-injury confirming location of deposits in VI
- Bottom right – X-ray thigh 2 months later showing mild resultant calcification
- MO collage-1

Management post re-injury
Medical;
- Patient started on Indomethacin 200mg daily immediately, taken for 2 weeks total
- New haematoma not amenable for repeat drainage as not liquified and increased risk of infection
Rehabilitation
- First 48 hours post-re-injury
- Tight compression throughout the length of the thigh
- Offload on crutches
- First 2 weeks
- Partial weight-bearing
- Quadricep length focused on in initial stages with passive prone knee bends
- Quadricep muscle activation using isometric squeeze exercises
- Muscle stimulation via compex
- Pool based activity and stretches
- Ongoing daily compression
- Weeks 2-4
- Return to normal walking unaided
- Gym based rehab with concentric and eccentric quadriceps, gluteal and hamstring activation
- Restoration of injured thigh muscle length (including hamstrings)
- Weeks 4-6
- Light jogging and continuation of strength and flexibility work
- Week 8 return to running
Key learning points – Myositis Ossificans
- Myositis Ossificans is a common condition in active people who exercise and are more susceptible to soft tissue injury
- It occurs when soft tissue bruising and haematoma, results in calcific deposits
- Recurrent muscle injury/bruising/haematoma increases the risk of MO
- It is more common in larger muscle groups e.g. quadriceps, hamstrings
- It is a radiology ‘DO NOT TOUCH’ lesion, i.e. should be diagnosed directly from x-ray or MRI
- This is to avoid unnecessary surgical intervention. Biopsy at early stage may be indistinguishable from Sarcoma.
- Investigation; X-ray is gold standard for detecting MO
- Management;
- No clear consensus on how to treat
- Reducing soft tissue swelling, bruising, haematoma collection can help prevent formation e.g. compression, drainage of fluid
- Indomethacin commonly used by sports medicine medical prescribers for a period of 2 weeks to prevent calcification
- Once calcification is present, babotage and shockwave can help break down deposits and improve function
- Novel therapies such as acetic acid solution administered via iontophoresis have mixed evidence
- Surgical intervention may prompt further MO development
- Rehabilitation;
- Goal is to regain as much range of movement and strength ASAP.
- Manual therapy and deep soft tissue around MO needs to be done with caution to prevent further spread
- Normal functionality of muscle can be achieved despite large MO deposits