Walking Difficulty and Leg Swelling

Walking difficulty and leg swelling are among the most common presenting complaints in Australian general practice and emergency departments. The differential diagnosis spans neurological, musculoskeletal, vascular, and systemic causes, and a structured approach to history and examination is essential to avoid missing serious pathology such as septic arthritis, deep vein thrombosis (DVT), or malignancy.

In Australia, falls and mobility limitations affect approximately 30% of adults aged over 65, making gait assessment a core component of the annual 75+ health assessment (MBS Item 707). Among children, an acute limp accounts for roughly 4 per 1,000 emergency presentations per year, with transient synovitis the most common cause (up to 80%) but septic arthritis (2–5%) requiring urgent exclusion.

Leg swelling as a presenting complaint carries significant diagnostic breadth. Venous thromboembolism (VTE) affects approximately 30,000 Australians annually, with incidence increasing with age, obesity, and hospitalisation. Lymphoedema is estimated at over 500,000 Australians, with primary forms presenting in younger adults and secondary forms commonly following cancer treatment. Chronic venous disease affects up to 30% of the adult population.

This article provides a comprehensive clinical guide to the assessment, investigation, and management of walking difficulty — including the major gait abnormalities and the paediatric limp — and leg swelling, with a focus on Australian clinical practice, PBS-listed medications, MBS-relevant investigations, and specific consideration for Aboriginal and Torres Strait Islander communities.

Gait assessment is a fundamental clinical skill. The pattern of abnormality provides immediate localisation of pathology. Observe the patient walking at normal pace, on heels, on toes, and tandem (heel-to-toe) walking. Note cadence, stride length, arm swing, trunk stability, and foot clearance.

Cerebellar Gait — Detailed Assessment

A wide-based ataxic gait with lateral sway and inability to perform tandem walking strongly suggests cerebellar dysfunction. The patient cannot stand with feet together (Romberg test is negative — they fall even with eyes open). Distinguish from sensory ataxia (positive Romberg — worsens with eyes closed, due to posterior column or large-fibre peripheral neuropathy).

Investigations: MRI brain (gold standard for posterior fossa pathology), FBC, UEC, LFTs, TFTs, vitamin B12/thiamine, blood alcohol level, urine drug screen. Consider genetic testing if family history of spinocerebellar ataxia.

Spastic Gait — Detailed Assessment

Spastic gait reflects upper motor neuron (UMN) pathology. The leg is held stiffly in extension and adduction, with circumduction during swing phase. Tone is increased (clasp-knife), reflexes are brisk, and plantar responses are extensor (Babinski positive). If unilateral, consider stroke; if bilateral, consider spinal cord pathology (compressive myelopathy, MS, hereditary spastic paraplegia).

Urgent MRI of the brain (if unilateral) or full spine (if bilateral or level unclear) is the investigation of choice. Do not delay MRI if cord compression is suspected — dexamethasone 8 mg IV/PO BD should be initiated immediately as a holding measure.

Foot Drop (Steppage Gait)

Foot drop results from weakness of ankle dorsiflexion (tibialis anterior). The patient compensates by excessive hip and knee flexion during swing phase to clear the foot. Test ankle dorsiflexion (L4–L5), great toe extension (L5), and eversion (L5–S1). Examine sensation over the dorsum of the foot (superficial peroneal nerve) and lateral shin (common peroneal nerve distribution).

Determine the level of the lesion:

• Peripheral nerve (common peroneal): Check for fibular head tenderness, history of leg crossing, plaster cast, or prolonged lithotomy position. EMG/NCS confirms localised conduction delay.
• L5 radiculopathy: Associated back pain, dermatomal sensory loss over dorsum of foot and lateral leg, weakness of hip abduction (gluteus medius). MRI lumbosacral spine confirms.
• Peripheral neuropathy: Often bilateral, stocking distribution sensory loss, distal weakness. Check HbA1c, B12, serum protein electrophoresis, nerve conduction studies.
• Central (UMN): Spasticity, brisk reflexes, extensor plantars — consider stroke, MND, MS.

Management: Ankle-foot orthosis (AFO) — available through public hospital orthotics departments or NDIS-funded services. Treat underlying cause. Physiotherapy for gait retraining.

Trendelenburg Gait

Weakness of the gluteus medius and minimus (hip abductors) results in inability to stabilise the pelvis during single-leg stance. The pelvis drops on the contralateral side. In a compensated Trendelenburg gait, the patient leans the trunk over the affected hip to shift the centre of gravity and reduce the abductor demand — this may be mistaken for a "waddle."

Causes include hip osteoarthritis (pain inhibition), superior gluteal nerve injury (post-hip surgery or misplaced intramuscular injection — always inject into the upper outer quadrant), L5 radiculopathy, and muscular dystrophy (fascioscapulohumeral, limb-girdle).

Investigations: X-ray pelvis (AP, frog-leg lateral) for hip OA or DDH; MRI hip for labral tear, tendinopathy; MRI lumbosacral spine for L5 radiculopathy; CK and EMG if myopathy suspected.

A child presenting with a limp is a common but potentially serious presentation. The approach must be systematic, age-appropriate, and mindful that young children may not localise pain accurately (referred hip pain often presents as knee pain).

Age-Based Differential Diagnosis

Clinical Assessment Algorithm

Distinguishing Transient Synovitis from Septic Arthritis

This is the most critical clinical decision in the limping child. Use the Kocher criteria to stratify risk:

Investigations for the Limping Child

Leg swelling has a broad differential diagnosis. The first clinical distinction is between unilateral and bilateral swelling, which immediately narrows the differential. The second distinction is between pitting (compressible, leaving an indent — oedema) and non-pitting (firm, brawny — lymphoedema, myxoedema).

Unilateral vs Bilateral Causes

Clinical Approach to Leg Oedema

Wells Score for DVT

Score interpretation: ≤1 = DVT unlikely (prevalence ~5%) — perform D-dimer. ≥2 = DVT likely (prevalence ~17–50%) — proceed directly to compression duplex ultrasound.

Septic Arthritis

Septic arthritis is a joint infection requiring urgent diagnosis and treatment. In Australia, Staphylococcus aureus (including CA-MRSA, which accounts for 30–50% of community S. aureus isolates in some regions) is the most common pathogen in adults. Neisseria gonorrhoeae should be considered in sexually active young adults. In children, S. aureus, Streptococcus pyogenes, and Kingella kingae (under 4 years) predominate.

Diagnosis

• Joint aspiration: synovial fluid WBC >50,000/mm³ (highly suggestive), >100,000/mm³ almost diagnostic
• Synovial Gram stain positive in ~50% of non-gonococcal septic arthritis
• Blood cultures positive in ~40% of cases
• CRP typically >100 mg/L; ESR >40 mm/hr; procalcitonin may be elevated

Empirical Antibiotic Therapy

Perthes Disease (Legg-Calvé-Perthes)

Perthes disease is avascular necrosis of the femoral head in children, typically aged 4–10 years. It is more common in boys (M:F 4:1). Presentation is insidious — atraumatic limp with hip or referred knee pain, limited hip abduction and internal rotation. Bilateral in ~10–15% of cases (if bilateral and symmetric, consider multiple epiphyseal dysplasia).

Investigation and Staging

• X-ray pelvis AP + frog-leg lateral: Initial radiograph may be normal (weeks 1–3). Early signs: lateral subluxation (increased medial joint space), subchondral fracture (crescent sign), femoral head sclerosis.
• MRI with gadolinium: Most sensitive for early diagnosis. Assess for femoral head viability and extent of involvement.
• Staging (Waldström / Catterall / Herring lateral pillar): Guides prognosis and management. Herring B and C involvement have worse long-term outcomes.

Management

• Containment principle: The femoral head must be contained within the acetabulum to remodel concentrically. Options: physiotherapy, Petrie casting, femoral osteotomy, Salter innominate osteotomy.
• Physiotherapy: Maintain hip range of motion (abduction, internal rotation). Avoid weight-bearing if painful (crutches).
• Surgical indication: Herring B/C border or C involvement in children >6 years. Refer to paediatric orthopaedic surgeon.
• Prognosis: Most children <6 years with Herring A/B do well with conservative management. Older children and those with extensive head involvement are at risk for premature hip OA.

Bone Tumours — Red Flags and Referral

Primary bone tumours are rare but must be considered in any child or young adult with persistent bone pain, especially if worse at night, associated with a mass, or not explained by trauma. In Australia, the most common primary malignant bone tumours in children and adolescents are osteosarcoma (peak 10–25 years) and Ewing sarcoma (peak 5–20 years).

Initial Workup

• X-ray of the affected area in two planes (AP + lateral)
• If suspicious → urgent referral to orthopaedic oncology within 72 hours
• Staging CT chest, whole-body MRI or PET-CT, and biopsy performed at the specialist centre
• FBC, UEC, LFTs, ALP (bony isoenzyme), LDH, calcium, phosphate

Benign Bone Lesions Presenting with Leg Swelling or Pain

DVT management has been transformed by direct oral anticoagulants (DOACs), which are now first-line for most patients with confirmed DVT. Initial anticoagulation should be commenced as soon as DVT is confirmed (or strongly suspected) while awaiting imaging results in high-risk patients.

Duration of Anticoagulation

Cellulitis is a common cause of unilateral leg swelling and erythema. It is a clinical diagnosis — there is no single confirmatory test. It must be distinguished from DVT (which can coexist), gout, and necrotising fasciitis (surgical emergency).

Clinical Features

• Erythema, warmth, swelling, tenderness with poorly defined borders
• Often preceded by breaks in skin (tinea pedis, wounds, insect bites, venous eczema)
• Regional lymphadenopathy (inguinal nodes for lower limb)
• Systemic features: fever, malaise, raised inflammatory markers

Red Flags Requiring Urgent Admission

Empirical Antibiotic Therapy for Cellulitis

Prevention of Recurrent Cellulitis

• Treat tinea pedis (terbinafine cream or oral terbinafine 250 mg daily for 2 weeks)
• Emollient to dry/cracked skin (barrier protection)
• Compression stockings (if chronic venous insufficiency)
• Prophylactic antibiotics: phenoxymethylpenicillin 250 mg PO BD or erythromycin 250 mg PO BD for 12 months (PBS Authority Required) — indicated after ≥2 episodes per year
• Lymphoedema management (compression, manual lymphatic drainage, skin care)

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