EpistemisAtrophy of the quadriceps muscle
Specialty: Musculoskeletal.
Why it occurs
- Arthrogenic muscle inhibition secondary to chronic knee pain or effusion (e.g., severe osteoarthritis, chronic ligament rupture)
- Femoral nerve injury (due to entrapment in the inguinal ligament or surgical iatrogenesis)
- Severe compressive lumbar radiculopathy L2-L3-L4
- Prolonged immobilization in knee extension
- Inclusion body myositis (autoimmune myopathy with a predilection for the quadriceps)
- Limb girdle muscular dystrophy or corticosteroid-induced myopathy
Initial workup
Electromyography (EMG) of the vastus medialis and rectus femoris muscles | Magnetic resonance imaging of the lumbar spine and thigh | Analysis with creatine kinase (CK) and aldolase levels.
red flags
Severe asymmetric atrophy of the quadriceps of rapid progression that is accompanied by loss of the ipsilateral patellar reflex, marked weakness in knee extension that causes frequent falls and low back pain radiating to the anterior aspect of the thigh (massive L3-L4 radiculopathy or proximal femoral nerve injury).
Standard management
- There are no drugs that reverse disuse atrophy — the fundamental pillar is the isometric quadriceps strengthening exercise); in case of inflammatory myopathy documented by biopsy: Prednisone (1 mg/kg/day orally with a progressive descending regimen
- Azathioprine (100 mg daily orally as an immunosuppressant).
Educational guidance for study. It is NOT a prescription recommendation. The actual choice depends on the cause, the patient, and current guidelines.
- Area
- Musculoskeletal
- Listed causes
- 6
- Treatment options
- 2