Question

Liverpool football team. During practice, one player suffered a high impact collided with a team-mate and injured the anterior compartment of his thigh. As a result of the collision, his quadriceps femoris muscle were compressed against the femur, resulting in quadriceps contusion or ‘cork thigh’

1 In severe injuries of this type, a condition known as myositis ossificans can occur. Explain the processes involved in the development of this condition, and the resulting consequences if left untreated.

Answer 1

Myositis ossificans is a specific type of non neoplastic heterotrophic ossification (formation of new bone) occurs in soft tissue, most oftenly in response to a local trauma.

Precipitating factors:-

1. Single /Repetitive trauma

2. Neurological injury eg. Paraplegia

3. Severe thermal injury

It occurs mostly in large skeletal muscles such as quadriceps,brachialis & adductor of thigh.It is common in young active athlete after a single traumatic injury.

Pathophysiology :---

Inappropriate response of stem cells in the bone against the injury or inflammation causes inappropriate differentiation of fibroblasts into osteogenic cells.

When a skeletal muscle is injured, inflammatory cytokines (Bone morphogenetic protein 2, Bone morphogenetic protein 4 are released.

These cytokines stimulate the endothelial cells of the blood vessels to transform into mesenchymal stem cells, which differentiate into chondrocytes, and osteoblasts, resulting in bone formation in soft tissues.

Steps -

1. Bone morphogenic protein stimulate stem cells in soft tissue to form osteoblast

2. Organisation of haematoma

3. Fibroblastic hypoplasia

4. Osteoid formatio

Clinical features :---

1. Aching type of pain lasting for more time than in case of a simple muscle contusion.
2. Swelling;-Localised swelling on the anterior thigh (in case of quadriceps trauma)
3. Gradual loss of Range of motion

Complication if untreated

1. Permanent decrease in range of motion

2. Deformity of limb

3. Ankylosis (fusion) of joint if bone formation occurs near joint

4. Persistent pain