Musculoskeletal clinical case of the month – Myositis Ossificans

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