Limb deformity

Limb deformity is an abnormal shape, alignment, length or rotation of a limb or part of a limb, noted at birth or developing later. It may reflect trauma (acute fracture or dislocation, or malunion), congenital or developmental disease, metabolic bone disease, infection, tumour, neuromuscular disease or inflammatory arthritis. The age of the patient and the tempo of onset direct the diagnosis.

Clinical relevance. Acute deformity after injury is an orthopaedic emergency when neurovascular compromise or an open wound is present. Chronic deformity impairs gait, function and cosmesis, and many causes in children are treatable only within windows of growth.

Anatomy and physiology. Longitudinal growth occurs at physes, and alignment is determined by the mechanical axis through the hip, knee and ankle. Normal alignment varies by age: physiological varus in infants, maximal genu varum by about 18 months, a valgus phase peaking at 3 to 4 years, and adult alignment (about 5 to 7 degrees of valgus) by 7 to 8 years.

Classification by plane. Angular (varus, valgus, procurvatum, recurvatum), rotational (torsional), length discrepancy, translational, and combined.

Classification by cause.

• Traumatic: acute fracture or dislocation, malunion, nonunion, growth plate arrest after physeal injury.
• Congenital and developmental: clubfoot, developmental dysplasia of the hip, congenital pseudarthrosis of the tibia, limb deficiency, polydactyly, syndromes.
• Metabolic and endocrine: rickets and osteomalacia, hyperparathyroidism, renal osteodystrophy, hypophosphatasia, fibrous dysplasia, Paget disease.
• Skeletal dysplasia and genetic: achondroplasia, osteogenesis imperfecta, multiple hereditary exostoses, Ollier disease, Marfan syndrome.
• Infective and inflammatory: osteomyelitis with growth arrest, septic arthritis, rheumatoid arthritis, juvenile idiopathic arthritis.
• Neuromuscular: cerebral palsy, spina bifida, polio, muscular dystrophy, Charcot joint, peripheral nerve injury.
• Neoplastic: bone and soft tissue tumours with pathological fracture.
• Acquired soft tissue: contracture, Volkmann ischaemic contracture, Dupuytren disease.

Key distinctions. Symmetric, gradual bowing in a toddler is usually physiological, but asymmetric, progressive or short stature with bowing suggests Blount disease or rickets. Acute deformity with pain, swelling and loss of function is a fracture or dislocation until proved otherwise.

History.

• Age at onset, tempo (acute, progressive, static), symmetry, and associated pain, swelling, fever, trauma, limp, function loss and developmental milestones.
• Birth history, prematurity, family history of deformity, short stature or bone disease, and consanguinity.
• Diet and sun exposure (vitamin D, calcium), breastfeeding without supplementation, malabsorption, kidney or liver disease, anticonvulsant use, and corticosteroid use.
• Previous injuries, surgery, infections, and neurological symptoms.
• In children with unexplained fractures or deformity: injury history inconsistent with the injury, delayed presentation, multiple injuries of different ages, and social concerns.

Examination.

• Observe the standing, walking and sitting alignment, from front, back and side. Measure leg lengths (true: anterior superior iliac spine to medial malleolus; apparent: umbilicus to medial malleolus), thigh and calf circumference, and joint range of motion.
• Angular measurements: intercondylar and intermalleolar distances, thigh foot angle, hip rotation, foot progression angle, and tibiofemoral angle.
• Palpate bones for tenderness, swelling, masses and crepitus. Examine joints for effusion and instability. Spine for scoliosis. Skin for café au lait spots (neurofibromatosis), scars, ulcers, and signs of rickets (rachitic rosary, frontal bossing, widened wrists).
• Neurovascular examination: pulses, capillary refill, sensation, power, reflexes and tone.
• General: height and weight on centile charts, dysmorphic features, hypermobility, blue sclerae and dentition.

Red flags.

• Acute deformity after trauma with absent pulses, pallor, paraesthesia, paralysis or tense swelling (neurovascular injury, compartment syndrome).
• Open wound over the deformity (open fracture).
• Fever, swelling, warmth and refusal to bear weight (osteomyelitis or septic arthritis).
• Rapidly growing mass, night pain, weight loss or pain not related to activity (tumour).
• Unexplained fractures, multiple injuries, or injury inconsistent with the story in a child (non-accidental injury).
• Progressive neurological deficit, bowel or bladder dysfunction.
• Limp or hip pain in an adolescent with obesity (slipped capital femoral epiphysis).
• Hip asymmetry or limited abduction in an infant (developmental dysplasia).
• Hypocalcaemia symptoms: tetany, seizures, stridor (rickets).

Special groups. Children need growth and developmental assessment and consideration of non-accidental injury. Older adults with new deformity need assessment for fragility fracture, Paget disease and tumour. Pregnancy limits imaging and vitamin D doses.

Acute traumatic. Fracture, dislocation, ligament and tendon rupture (for example Achilles, quadriceps), growth plate injury, traumatic amputation, open fracture, compartment syndrome with swelling. Congenital and developmental (infancy and childhood).

• Clubfoot (congenital talipes equinovarus), vertical talus, metatarsus adductus, calcaneovalgus foot.
• Developmental dysplasia of the hip, congenital femoral deficiency, proximal focal femoral deficiency.
• Congenital pseudarthrosis of the tibia (neurofibromatosis type 1), fibular hemimelia, tibial hemimelia, amniotic band syndrome.
• Polydactyly, syndactyly, radial and ulnar longitudinal deficiency, congenital dislocation of the knee or patella.
• Physiological bowing and knock knees, tibial torsion and femoral anteversion.

Growth disorders. Blount disease (tibia vara), rickets (nutritional, hypophosphataemic, renal), achondroplasia and other skeletal dysplasias, multiple hereditary exostoses, Ollier disease, osteogenesis imperfecta, fibrous dysplasia, McCune-Albright syndrome, physeal arrest (post infection, trauma, radiotherapy), Perthes disease, slipped capital femoral epiphysis, Scheuermann disease.

Metabolic and acquired bone disease (adolescents and adults). Osteomalacia, Paget disease of bone, hyperparathyroidism, renal osteodystrophy, osteoporosis with vertebral collapse, osteonecrosis, fluorosis.

Neuromuscular and neurological. Cerebral palsy, spina bifida, muscular dystrophy, poliomyelitis sequelae, peripheral nerve palsy (drop foot, claw hand), stroke, Charcot neuroarthropathy, hereditary motor sensory neuropathy.

Inflammatory and degenerative. Rheumatoid arthritis (ulnar deviation, swan neck, boutonniere, hallux valgus), osteoarthritis (genu varum, hip contracture), gout, psoriatic arthritis, juvenile idiopathic arthritis, Dupuytren contracture, joint contracture.

Infective. Osteomyelitis with growth disturbance, septic arthritis sequelae, tuberculosis of bone and joint (Pott disease, gibbus, hip involvement), leprosy, yaws.

Neoplastic and vascular. Primary bone sarcoma, metastasis with pathological fracture, soft tissue tumour, vascular malformation with overgrowth, lymphoedema, Klippel-Trenaunay syndrome.

Non-accidental and iatrogenic. Non-accidental injury, malunion after treatment, post amputation, Volkmann ischaemic contracture.

Step 1. Establish age, tempo and symmetry. For acute deformity, assess neurovascular status and the airway, breathing and circulation before imaging.

Step 2. Imaging.

• Plain radiographs in two planes including the proximal and distal joints for any acute deformity. Weight bearing full length (hip to ankle) radiographs for lower limb alignment, with measurement of mechanical axis deviation, mechanical lateral distal femoral angle and medial proximal tibial angle.
• Scanogram or full length standing film for leg length discrepancy. CT for rotation, complex fractures, physeal bars and tarsal coalition. MRI for physeal injury, tumour, infection, osteonecrosis and soft tissue. Ultrasound for infant hips and soft tissue.
• Bone age (left hand and wrist) when growth prediction is needed. Skeletal survey in suspected non-accidental injury and in skeletal dysplasia.
• Bone scan or PET for multifocal disease and tumour staging.

Step 3. Laboratory tests when metabolic or inflammatory disease is suspected:

• calcium, ionised calcium, phosphate, alkaline phosphatase (raised in rickets, osteomalacia, Paget disease), magnesium, parathyroid hormone
• 25 hydroxyvitamin D (under 30 nmol/L deficient, 30 to 50 nmol/L insufficient)
• creatinine and eGFR, urinary calcium, tubular phosphate reabsorption and TSH
• FBC, ESR and CRP for infection and inflammation
• genetic testing (collagen genes, FGFR3, PHEX) for skeletal dysplasia and osteogenesis imperfecta
• rheumatoid factor and anti-CCP for suspected rheumatoid arthritis

Step 4. Tissue and procedures: joint aspiration and culture for suspected infection, and biopsy planned with a bone tumour team for a suspected sarcoma (not before imaging).

Interpretation. Rickets shows widened, cupped and frayed metaphyses with raised alkaline phosphatase and low or normal calcium. Blount disease shows a metaphyseal beak and a metaphyseal diaphyseal angle over 11 degrees. Physiological bowing resolves by 2 to 3 years.

Limitations. Radiographs underestimate early physeal and cartilage injury. Normal vitamin D does not exclude hypophosphataemic rickets. Standing films in young children may be unreliable.

Acute traumatic deformity.

• Primary survey, control of external bleeding, and neurovascular checks before and after every manoeuvre.
• Analgesia: paracetamol 1 g orally or IV every 6 hours (maximum 4 g daily; 3 g daily if weight under 50 kg, malnutrition, alcohol excess or liver disease). In children, 15 mg/kg every 4 to 6 hours with a maximum of 60 mg/kg daily.
• Morphine 0.05 to 0.1 mg/kg IV titrated every 5 minutes (2 mg boluses in adults, with sedation and respiratory rate monitoring and a lower dose in older adults).
• Intranasal fentanyl 1.5 micrograms/kg (maximum 100 micrograms) in children when IV access is absent.
• Ibuprofen 400 mg orally every 8 hours (maximum 1.2 g daily) once bleeding and kidney risk are excluded. In children, 10 mg/kg every 6 to 8 hours with a maximum of 40 mg/kg daily.
• Splint in the position found or after gentle realignment of a grossly deformed pulseless limb (one attempt, with traction in line), elevate, ice, and nil by mouth if surgery is likely. Remove rings and tight clothing.
• Open wounds: cover with saline soaked sterile dressing, give antibiotics within 1 hour (cefazolin 2 g IV every 8 hours; maximum 6 g daily; for CrCl 10 to 34 mL/min give half the dose every 12 hours), tetanus cover, and urgent orthopaedic review.
• Absent pulses after realignment: urgent vascular surgical assessment and CT angiography, with ischaemia time under 6 hours.
• Reduction under sedation or regional block for dislocations and displaced fractures by trained staff, with post reduction imaging and neurovascular checks.

Developmental and congenital deformity.

• Clubfoot: serial manipulation and casting (weekly casts for about 5 to 6 weeks) from the first weeks of life, Achilles tenotomy when needed, then abduction bracing for 3 to 4 years.
• Developmental dysplasia of the hip: Pavlik harness for 6 to 12 weeks from detection to about 6 months, with ultrasound follow up; closed or open reduction after that.
• Physiological bowing and knock knees: reassure and review every 6 months. Refer for asymmetry, progression after 2 years (varus) or 7 years (valgus), severe deformity, short stature or pain.
• Blount disease: brace for children under 3 years and surgical correction (osteotomy or growth modulation by hemiepiphysiodesis) when older or progressive.
• Leg length discrepancy: shoe raise for up to 2 cm, epiphysiodesis (timed to growth) for 2 to 5 cm, and lengthening for larger discrepancy.

Rickets and osteomalacia (nutritional).

• Children aged 1 month to 11 years: colecalciferol 3000 IU orally once daily for 8 to 12 weeks (or a single high dose of 150,000 to 300,000 IU under specialist care), with dietary calcium 500 mg elemental daily or supplementation.
• Adolescents 12 to 17 years and adults: colecalciferol 50,000 IU orally once weekly for 6 to 8 weeks, or 3000 to 6000 IU daily for 8 to 12 weeks. Then 800 to 2000 IU daily maintenance (maximum 4000 IU daily without monitoring), with calcium 500 to 1000 mg elemental daily.
• Monitor calcium, phosphate, alkaline phosphatase and 25 hydroxyvitamin D at 4 weeks and 3 months. Stop vitamin D if calcium is over 2.60 mmol/L. Avoid in sarcoidosis, hypercalcaemia and renal stones without specialist advice.
• Check calcium before starting in suspected hypoparathyroidism, and treat severe hypocalcaemia first with calcium gluconate 10% 10 to 20 mL IV over 10 minutes with ECG monitoring.
• Refer hypophosphataemic, renal and vitamin D resistant forms to endocrinology and nephrology (phosphate and calcitriol or burosumab under specialist direction).

Metabolic and other acquired causes. Treat hyperparathyroidism, renal bone disease, and Paget disease (zoledronic acid 5 mg IV once; check calcium, vitamin D and creatinine first; avoid if CrCl under 35 mL/min; monitor alkaline phosphatase at 3 to 6 months).

Infection. For suspected bone or joint infection, obtain cultures and start antibiotics within hours.

• Cefazolin 2 g IV every 8 hours (maximum 6 g daily; half the dose every 12 hours for CrCl 10 to 34 mL/min).
• Add vancomycin 25 mg/kg IV loading dose (maximum 3 g) when MRSA is likely.
• Orthopaedic review for aspiration and washout.

Children need weight based doses.

Neuromuscular deformity. Physiotherapy, orthoses, botulinum toxin injections and surgery by the specialist team.

Spasticity management: baclofen 5 mg orally three times daily, increased every 3 days to a maximum of 80 mg daily in adults, with withdrawal over 1 to 2 weeks. Reduce in kidney impairment and monitor sedation.

Suspected non-accidental injury. Document injuries, perform skeletal survey and safeguarding referral without delay, and admit for protection.

Monitoring. Serial clinical and radiographic measurement at 3 to 6 month intervals during growth, neurovascular checks every hour after reduction in the first 24 hours, and biochemical monitoring during vitamin D treatment.

Referral and escalation. Orthopaedic surgery urgently for acute deformity with neurovascular compromise, open injury or suspected infection, and in routine clinics for chronic deformity. Paediatric orthopaedics for children. Endocrinology and nephrology for metabolic bone disease. Genetics for skeletal dysplasia. Oncology and bone tumour team for suspected tumour. Social care and child protection for suspected abuse.

Admission criteria. Neurovascular compromise, open fracture, unstable fracture or dislocation needing reduction or fixation, suspected infection, suspected non-accidental injury, severe hypocalcaemia, and uncontrolled pain.

Discharge and safety netting. Discharge stable deformities with a clear follow up plan. After splinting, patients return for increasing pain, swelling, numbness, pallor, blue or cold fingers or toes, or cast tightness.