Leg Pain - Differential Diagnosis Framework



Bone/Joint Causes of Leg Pain:

 • Fracture

 • Arthritis

 • Gout/pseudogout

 • Trauma

 • Osteomyelitis

 • Patellofemoral pain syndrome

 • Arthritis

 • Popliteus tendinitis

 • Malignancy: Osteosarcoma, Ewing sarcoma

 • Legg-Calve-Perthes disease

 • Slipped capital femoral epiphysis

 • Bursitis

 • IBD

 • Psoriasis

 • Hepatitis

 • Hematoma



Venous Causes of Leg Pain:

 • DVT

 • Varicose veins

 • Superficial thrombophlebitis



Skin Causes of Leg Pain:

 • Infection: Cellulitis, Abscess, Necrotizing fasciitis

 • Inflammation: Wounds/ulcers, Edema



Arterial Causes of Leg Pain:

 • PAD

 • Limb ischemia

 • Aortic/Iliac artery aneurysms



Nerve Causes of Leg Pain:

 • Neuropathy (DM, Vit B12, B6, Cu deficiency etc)

 • Spinal stenosis/nerve compression

 • Sciatica

 • Tarsal tunnel syndrome, peroneal neuropathy

 • Sural nerve entrapment

 • Infections causing nerve damage:

	- Epidural abscess

	- Herpes zoster

	- HIV

	- Lyme disease



Muscle Causes of Leg Pain:

 • Rhabdomyolysis

 • Compartment syndrome

 • Myositis/pyomyositis

 • Cramps (electrolyte imbalance)

 • Tendinitis

 • Repetitive strain injury

 • Iliotibial band syndrome

 • Shin splints

 • Hamstring strain

 • Piriformis syndrome



Leg Pain Red Flags:

 • Trauma

 • Crush injury

 • DVT (Risks: Recent surgery, Smoking, Contraceptive pill, Immobilization)

 • Acute limb ischemia/cyanosis

	- Cool extremity

	- Prolonged capillary refill

	- Poor pulses

	- Hair loss- feet and legs

	- Brittle nails

	- Skin ulcers

	- Shiny skin

 • Inflammation/cellulitis/abscess

 • Compartment syndrome

	- History of blunt trauma, crush

	- Rigorous exercise

	- Excessive training

	1) Pain

	2) Pallor-bruising

	3) Paralysis

	4) Paresthesia

	5) Pulselessness

	6) Poikilothermia

 • Septic arthritis

	- Rapid onset

	- Intense joint pain/swelling

	- Fever/chills

	- Inability to move the joint



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