Definitions
Acute leg pain is a subjective, unpleasant sensation felt somewhere in the lower limb. Referred pain is the perception of pain in an area remote from the site of origin of the pain, e.g. leg pain from lumbar disc herniation, knee pain from hip pathology. Cramps are involuntary, painful contractions of voluntary muscles. Sciatica is a nerve pain caused by irritation of the sciatic nerve roots characterized by lumbosacral pain radiating down the back of the thigh, lateral side of the calf and into the foot.
- May be due to pathology arising in any of the tissues of the leg.
- Constant or lasting pain suggests local pathology.
- Transient or intermittent pain suggests referred pathology.
- Systemic symptoms or upset suggests inflammation.
Important Diagnostic Features
Infection
- Infection of skin (cellulitis): painful, swollen, red, hot leg, associated systemic features – pyrexia, rigors, anorexia, commonly caused by Streptococcus pyogenes. May be associated lymphangitis (inflammation of lymphatics).
- Acute osteomyelitis: staphylococcal infection, affects metaphyses, acute pain, tenderness and oedema over the end of a long bone, common in children, may be history of skin infection or trauma.
Trauma
- Muscle: swollen, tender and painful, pain worse on attempted movement of the affected muscle.
- Bone: painful, tender. Swelling, deformity, discoloration, bruising and crepitus suggest fracture.
- Joints: painful, limited movement, deformity if dislocated, locking and instability with knee injury.
Degenerative
- Gout: first MTP joint (big toe), males, associated signs of joint inflammation.
- Disc herniation (sciatica): pain in distribution of one or two nerve roots, sudden onset, back pain and stiffness, lumbar scoliosis due to muscle spasm.
- Ruptured Baker’s cyst: pain mostly behind the knee, previous history of knee arthritis, calf may be hot and swollen.
Tumours
Bone: deep pain, worse in morning and after exercise, overlying muscle tenderness, pathological fractures, primary (e.g. osteosarcoma, osteoclastoma) or secondary (e.g. breast, prostate, lung metastasis).
Vascular
DVT: calf pain, swelling, redness, prominent superficial veins, tender on calf compression, low-grade pyrexia.
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