Myositis Ossificans of the Quadriceps

Original Editor - Elout Witterzeel, Wouter Vervaet, Mathieu Van Durme and Pieter Van Den Bossche Top Contributors - Hardik Bhatt, Annelies Noppe, Kim Jackson, Karen Wilson, Wanda van Niekerk, WikiSysop and Lucinda hampton

Introduction

Myositis Ossificans is a benign, meta-plasmatic, mostly self-limiting process in which bone or bone-like tissue formation takes place in skeletal muscle. It occurs mostly in large skeletal muscles such as quadriceps,brachialis & adductor of thigh.It may arise with or without trauma.But its common in young active athlete after a single traumatic injury.

These different causes of myositis ossificans (MO)divide the disorder into two subgroups:

• -Myositis Ossificans Traumatica (MOT) also called the non-hereditaryy myositis ossificans(associated with burns, haemophilia and neurological disorders)
• -Myositis Ossificans Progressiva (MOP), also called Fibroplasia Ossificans Progressiva (FOP).

Epidemiology /Etiology

MOP resulting from a direct blow or repeated injury is the most common representing 60-75% of total cases.

Post-traumatic MO occurs in about 20% of cases reported with large muscle hematoma associated with contusion or trauma. It lasts for an average of 1.1 years.It may also occur due to repetitive injury to the same area.

It's found in both contacts as well as non-contact sports. Its exact cause is unknown but mostly it's an error in the healing process where normal muscle cells known as fibroblast are replaced by immature bone cells.

Characteristics/Clinical Presentation

1. Pain;-Aching type of pain lasting for more time than in case of a simple muscle contusion.
2. Swelling;-Localised swelling on the anterior thigh or in some cases it may be in the whole limb.
3. Decrease ROM;-Gradual loss of ROM(Range of motion

Along with the above symptoms,a careful history of injury gives an indication to diagnose MO

Differential Diagnosis

Malignant tumors of thigh such as lymphoma, osteosarcoma and rhabdomyosarcoma have similar symptoms.

Diagnostic Procedures

• MRI is a gold standard investigation for any soft tissue mass,it helps to identify early developing cases.
• Earlier Ultrasonography also helps to detect calcifying hematoma.
• Plain Radiograph shows calcified mass only in the advanced stage.CT scan or bone scans can also be performed to differentiate myositis ossificans from other conditions.

Outcome Measures

Lower Extremity Functional Scale (LEFS),may be used as outcome measure for condition.

Examination

History

As MO can only be accurately diagnosed about two weeks after onset and generally requires investigation beyond a standard clinical examination, Consequently, initial presentation may follow that of a quadriceps contusion. Following acute injury the following signs & symptoms may be noted:

• Anterior thigh pain
• Sharp pain during activity (particularly when kicking, jumping, or changing directions in athletes)
• Localized swelling and loss of motion

MO should be suspected under the following circumstances:

• Worsening of symptoms after 2-3 weeks accompanied by loss of knee flexion
• Persistent swelling

Physical Examination

As ossifying lesions mature, physical examination can reveal noteworthy findings. The table below matches parts of the clinical examination with possible findings related to MO :

Testing Domain	Findings
Observation	Swelling, increased thigh circumference
Palpation	Painful soft tissue mass, usually with no signs of inflammation
Range of Motion	Restricted knee flexion, pain with passive stretching
Strength	Decreased quadriceps strength with pain during static & dynamic contraction

Medical Management

Most cases of MO can be successfully managed with conservative treatment. This typically includes the prescription of NSAIDs, rest, and exercise therapy. Operative removal of the ossification is only indicated for progressive disease or persistent cases in which conservative treatment has not been successful.

Physical Therapy Management

Physiotherapy can be used to guide patients through a supervised rehabilitation program. Given the rarity of MO of the quadriceps, little evidence exists to guide treatment. Many case studies and reviews advocate an initial period of stretching, range of motion & gentle exercise (ex. isometric quadriceps contraction and terminal knee extension) followed by the addition of more aggressive strengthening, proprioceptive retraining, aerobic conditioning, and return to activity.

A small number of case studies suggest that Extracorporeal Shockwave Therapy (ESWT) may be an effective adjunct to traditional conservative measures.