Medical School · Year 3 · Pediatrics · includes a quiz and discussion video

Seminar 12: Pediatric Musculoskeletal Disorders

Unit 3: Pediatrics Clerkship

Learning Objectives

1. Develop a systematic approach to evaluating limping and musculoskeletal pain in children using age-based differential diagnoses
2. Recognize developmental dysplasia of the hip through physical examination findings and select appropriate imaging modalities by age
3. Diagnose and differentiate between transient synovitis, Legg-Calve-Perthes disease, and slipped capital femoral epiphysis based on clinical presentation
4. Identify the clinical features of septic arthritis and osteomyelitis requiring urgent evaluation and management
5. Describe the classification, clinical features, and management principles of juvenile idiopathic arthritis
6. Recognize common pediatric fracture patterns including Salter-Harris classification and distinguish accidental from non-accidental trauma

Lecture Outline

Section 1: Approach to Limping

The evaluation of a limping child requires a systematic approach that considers the broad differential diagnosis across different age groups while maintaining vigilance for serious conditions requiring emergent intervention. Limping represents an abnormality in gait that may arise from pain, weakness, structural deformity, or neurologic dysfunction, and the underlying cause varies substantially based on the child's age and developmental stage. The approach to the limping child must efficiently identify those with serious conditions such as septic arthritis, osteomyelitis, or malignancy while avoiding excessive workup in children with benign self-limited conditions. A careful history, focused physical examination, and judicious use of imaging and laboratory testing guide diagnostic evaluation and management decisions.

The differential diagnosis of limping changes dramatically across pediatric age groups, making age one of the most important factors in clinical reasoning. In toddlers aged one to three years, transient synovitis, occult toddler's fractures of the tibia, developmental dysplasia of the hip, and infection represent the most common considerations. Children aged four to ten years most frequently present with transient synovitis, but Legg-Calve-Perthes disease becomes an important consideration during this period. Adolescents present unique diagnostic possibilities including slipped capital femoral epiphysis, Osgood-Schlatter disease, and stress fractures related to athletic activity. At any age, septic arthritis, osteomyelitis, and trauma require consideration, as these diagnoses carry significant morbidity if missed.

History taking in the limping child should systematically explore characteristics of the limp and associated symptoms that help narrow the differential diagnosis. The acuity of onset provides important clues, as acute onset suggests infection or trauma while chronic or progressive limping raises concern for inflammatory arthritis or malignancy. The location of pain deserves careful attention, with the caveat that hip pathology commonly presents as knee or thigh pain due to referred pain along shared nerve distributions. The presence of fever strongly suggests infectious etiology and mandates prompt evaluation. Morning stiffness lasting more than fifteen minutes characterizes inflammatory conditions such as juvenile idiopathic arthritis. Night pain unrelated to activity raises particular concern for malignancy and warrants thorough investigation.

Physical examination of the limping child combines gait observation with focused assessment of the musculoskeletal and neurologic systems. Gait should be observed from multiple angles, noting whether the child demonstrates an antalgic gait with shortened stance phase on the affected side or a Trendelenburg gait suggesting hip abductor weakness. Range of motion testing at each joint should assess for limitation, particularly internal rotation of the hip which is often the first motion affected in hip pathology. Each joint should be examined for swelling, warmth, and effusion. Point tenderness over bones suggests fracture or osteomyelitis. Neurovascular examination assesses pulses, capillary refill, sensation, and motor function. Specific red flags that warrant urgent evaluation include fever with limp suggesting septic joint, complete inability to bear weight indicating serious pathology, night pain raising concern for malignancy, and neurologic findings suggesting spinal cord pathology.

<image>Panel A: Series of photographs demonstrating normal gait cycle compared with antalgic gait showing shortened stance phase and Trendelenburg gait with hip drop. Panel B: Age-stratified differential diagnosis chart showing most common causes of limping in toddlers, school-age children, and adolescents. Panel C: Physical examination technique for assessing hip internal rotation with child supine and hip flexed to 90 degrees. Panel D: Clinical decision algorithm for evaluating the limping child with pathways based on presence of fever, ability to bear weight, and examination findings.</image>

Section 2: Developmental Dysplasia of the Hip

Developmental dysplasia of the hip encompasses a spectrum of abnormalities ranging from mild acetabular dysplasia to complete dislocation of the femoral head from the acetabulum. This condition affects approximately 1 to 3 per 1000 live births and represents one of the most important conditions identified through newborn examination and subsequent surveillance. Early detection and treatment during infancy typically results in normal hip development, while delayed diagnosis can lead to significant morbidity including chronic pain, gait abnormalities, and early degenerative joint disease. Understanding the risk factors, screening examination, and age-appropriate imaging allows pediatricians to optimize outcomes through timely identification and referral.

Several well-established risk factors increase the likelihood of developmental dysplasia of the hip and should heighten clinical suspicion during newborn examination. Female sex confers a four-to-one increased risk compared with males, attributed to increased ligamentous laxity in response to maternal relaxin. Breech presentation, particularly frank breech with extended legs, represents the most significant risk factor and warrants ultrasonographic screening even with normal examination findings in some guidelines. Positive family history of developmental dysplasia increases risk and should prompt careful examination. First-born infants experience higher rates, possibly related to decreased intrauterine space. The left hip is affected more commonly than the right, as the left hip typically lies against the mother's spine in the most common fetal positions. Oligohydramnios and other conditions reducing fetal movement also increase risk.

Newborn examination for developmental dysplasia of the hip employs the Ortolani and Barlow maneuvers, which assess hip stability and should be performed at every well-child visit during the first several months of life. The Ortolani maneuver tests whether a dislocated hip can be reduced; with the infant supine and hips flexed to ninety degrees, the examiner gently abducts the hip while applying anterior pressure over the greater trochanter. A positive test produces a palpable clunk as the dislocated femoral head reduces into the acetabulum. The Barlow maneuver tests whether a located hip can be dislocated; with the hip in the same position, the examiner applies posterior pressure while adducting the hip. A positive test indicates an unstable hip that subluxes or dislocates with this maneuver. Beyond the newborn period, limited hip abduction asymmetry and apparent leg length discrepancy become more useful examination findings as the Ortolani and Barlow maneuvers lose sensitivity.

Imaging modality selection for developmental dysplasia of the hip depends on the infant's age and the degree of proximal femoral ossification. Ultrasound represents the imaging modality of choice in infants younger than four to six months because the femoral head remains cartilaginous and invisible on plain radiographs during this period. Ultrasonography can assess both the morphology of the acetabulum and the stability of the hip with dynamic maneuvers. After four to six months of age, ossification of the femoral head makes radiography useful, with specific measurements including the acetabular index and Shenton line arc assessed. Treatment is guided by age at diagnosis and severity of dysplasia. Infants diagnosed before six months typically respond to Pavlik harness treatment, which maintains the hip in flexion and abduction to promote acetabular development. Infants diagnosed between six and eighteen months may require closed reduction under anesthesia followed by spica casting. Children diagnosed after eighteen months or those with failed conservative treatment require open surgical reduction. Early detection remains the key to optimal outcomes.

<image>Panel A: Demonstration of Ortolani maneuver technique with examiner hands positioned to apply anterior pressure during hip abduction while palpating for reduction clunk. Panel B: Demonstration of Barlow maneuver technique with examiner applying posterior and medial pressure during hip adduction to assess for instability. Panel C: Ultrasound image of infant hip showing normal alpha angle and acetabular coverage compared with dysplastic hip showing decreased coverage. Panel D: Infant positioned in Pavlik harness showing proper flexion and abduction positioning with straps correctly placed.</image>

Section 3: Hip Disorders

Hip pathology in children manifests with pain that may localize to the hip, groin, thigh, or knee, and the differential diagnosis varies substantially by age. Three important conditions affecting the pediatric hip span the childhood years with characteristic ages of presentation: transient synovitis primarily affects children aged three to ten years, Legg-Calve-Perthes disease peaks at four to ten years, and slipped capital femoral epiphysis occurs during adolescence. Understanding the clinical features that distinguish these conditions allows appropriate diagnosis and management while avoiding delays that could lead to permanent disability.

Transient synovitis, also known as toxic synovitis, represents the most common cause of hip pain and limp in young children, affecting primarily those aged three to ten years with peak incidence around six years. This self-limited inflammatory condition often follows a viral upper respiratory illness by one to two weeks and is thought to represent a post-infectious reactive phenomenon. Children typically present with acute onset hip or groin pain, limp or refusal to bear weight, and limited hip range of motion, particularly internal rotation. Fever is absent or low-grade, and laboratory inflammatory markers are normal or only mildly elevated. The critical clinical challenge is distinguishing transient synovitis from septic arthritis, which requires emergent surgical drainage. Rest, nonsteroidal anti-inflammatory medications, and symptomatic treatment lead to complete resolution within one to two weeks in essentially all cases.

Legg-Calve-Perthes disease results from idiopathic avascular necrosis of the femoral head, leading to a prolonged course of necrosis, fragmentation, reossification, and remodeling that spans two to four years. Boys are affected approximately four to five times more frequently than girls, with peak incidence between ages four and eight years. Affected children typically present with insidious onset limp and pain in the hip, groin, thigh, or knee, without systemic symptoms. Physical examination reveals limited hip range of motion, particularly internal rotation and abduction. Plain radiographs may be normal early in the disease course but progressively demonstrate increased density of the femoral head, fragmentation, and eventually remodeling with varying degrees of residual deformity. Treatment aims to maintain femoral head containment within the acetabulum during the remodeling phase, and may involve activity modification, physical therapy, bracing, or surgical intervention depending on age at presentation and severity of involvement.

Slipped capital femoral epiphysis represents displacement of the femoral head relative to the femoral neck through the physis and constitutes an orthopedic emergency requiring urgent stabilization. This condition predominantly affects overweight or obese adolescents during periods of rapid growth, with peak incidence at age twelve in girls and fourteen in boys. Patients typically present with hip, thigh, or knee pain and limp that may be chronic and progressive or acute following minor trauma. On examination, the affected leg rests in external rotation, and attempts at hip flexion result in obligate external rotation as the hip is brought forward. Radiographs including frog-leg lateral views demonstrate posterior and medial displacement of the femoral epiphysis relative to the metaphysis, classically described as ice cream falling off a cone. Classification as stable or unstable depends on ability to bear weight, with unstable slips carrying significantly higher risk of avascular necrosis. Treatment requires urgent surgical pinning in situ without attempts at reduction, as manipulation increases avascular necrosis risk.

<image>Panel A: Clinical photograph showing external rotation posturing of the lower extremity characteristic of slipped capital femoral epiphysis with comparison to normal contralateral limb. Panel B: Anteroposterior hip radiograph demonstrating Legg-Calve-Perthes disease with femoral head fragmentation and increased density compared with normal contralateral side. Panel C: Frog-leg lateral radiograph showing slipped capital femoral epiphysis with posterior displacement of epiphysis creating the ice cream falling off cone appearance. Panel D: Comparison chart of clinical features distinguishing transient synovitis, Perthes disease, and SCFE including typical age, onset, fever, and radiographic findings.</image>

Section 4: Septic Arthritis

Septic arthritis represents bacterial infection of a joint space and constitutes an orthopedic emergency requiring prompt diagnosis and surgical intervention to prevent permanent joint destruction. The incidence peaks in children younger than three years, with the knee and hip being the most commonly affected joints. Delayed diagnosis and treatment lead to cartilage destruction, growth disturbance, and chronic arthritis with significant long-term disability. Recognition of the clinical features, appropriate use of diagnostic tests, and understanding of management principles are essential for all clinicians caring for children.

The pathophysiology of pediatric septic arthritis most commonly involves hematogenous seeding of the joint space during transient bacteremia. Staphylococcus aureus is the most common causative organism across all age groups, followed by Streptococcus pyogenes and Streptococcus pneumoniae. In neonates, group B streptococcus and gram-negative organisms require consideration. Kingella kingae has emerged as an important pathogen in children younger than four years and may be difficult to culture with standard techniques, requiring specialized media or molecular testing for detection. In adolescents, Neisseria gonorrhoeae should be considered in the setting of appropriate risk factors. The hip joint deserves special attention because the capsule encloses the femoral neck, and increased intra-articular pressure can compromise blood supply to the femoral head, making urgent decompression critical.

Clinical presentation of septic arthritis typically includes fever, joint pain, swelling, and refusal to bear weight or move the affected extremity. The joint appears swollen, warm, and erythematous with severely limited range of motion due to pain. Children often hold the joint in the position that maximizes capsular volume and minimizes pressure, which for the hip is flexion, abduction, and external rotation. The Kocher criteria provide a validated clinical prediction tool for distinguishing septic arthritis of the hip from transient synovitis. The four criteria include temperature greater than 38.5 degrees Celsius, inability to bear weight, erythrocyte sedimentation rate greater than 40 mm/hour, and white blood cell count greater than 12,000 per microliter. The presence of all four criteria predicts septic arthritis with approximately 99% probability, while zero criteria reduce probability to less than 1%.

Diagnosis of septic arthritis requires joint aspiration for synovial fluid analysis, which serves both diagnostic and therapeutic purposes by decreasing intra-articular pressure. Synovial fluid in septic arthritis typically demonstrates white blood cell count greater than 50,000 per microliter with predominant neutrophils, although lower counts do not exclude infection. Gram stain and culture identify the causative organism, though cultures may be negative in up to 30% of cases, particularly with fastidious organisms like Kingella. Blood cultures should be obtained before antibiotic administration and are positive in 30-40% of cases. Management requires both surgical drainage and antibiotic therapy. The hip joint requires open surgical drainage or arthroscopy due to its anatomic complexity and risk of avascular necrosis, while other joints may be managed with repeated needle aspiration in some cases. Empiric antibiotic therapy should cover Staphylococcus aureus and typically consists of nafcillin or cefazolin, with addition of ceftriaxone in young children for Kingella coverage or in adolescents for gonococcal coverage. Antibiotic duration typically extends three to four weeks depending on clinical response and inflammatory marker normalization.

<image>Panel A: Clinical photograph of child with septic arthritis of the hip showing characteristic positioning with hip flexed, abducted, and externally rotated to maximize joint volume. Panel B: Diagram illustrating the Kocher criteria with probability percentages for septic arthritis based on number of criteria present. Panel C: Microscopy image of synovial fluid from septic joint showing dense neutrophilic infiltrate with gram-positive cocci visible. Panel D: Surgical photograph showing arthrotomy approach for hip joint drainage with purulent material being evacuated.</image>

Section 5: Osteomyelitis

Osteomyelitis represents bacterial infection of bone and predominantly affects children through hematogenous seeding of the metaphysis of long bones. The unique vascular anatomy of growing bone predisposes children to infection, as tortuous end-capillary loops in the metaphysis create sluggish blood flow that facilitates bacterial seeding. Prompt recognition and treatment with appropriate antibiotics prevents complications including chronic osteomyelitis, growth disturbance, and pathologic fracture. Understanding the clinical presentation, diagnostic approach, and treatment principles enables clinicians to optimize outcomes in affected children.

The epidemiology and microbiology of acute hematogenous osteomyelitis guide empiric antibiotic selection and diagnostic testing. Children younger than five years are most commonly affected, with boys more frequently than girls. The metaphysis of long bones represents the typical location, with the femur, tibia, and humerus most commonly involved. Staphylococcus aureus causes the majority of cases across all age groups, with both methicillin-sensitive and methicillin-resistant strains important depending on local prevalence. In neonates, group B streptococcus and gram-negative organisms require coverage. Kingella kingae represents an important pathogen in children younger than four years. Salmonella osteomyelitis occurs with increased frequency in children with sickle cell disease and should be considered in this population.

Clinical presentation of osteomyelitis typically includes fever, bone pain, and refusal to use the affected extremity. Point tenderness over the involved bone represents the most important physical examination finding, with overlying soft tissue swelling developing as infection progresses. Limp or refusal to bear weight accompanies lower extremity involvement. Laboratory studies reveal elevated inflammatory markers including white blood cell count, erythrocyte sedimentation rate, and C-reactive protein, with CRP being most useful for monitoring treatment response. Blood cultures are positive in 30-50% of cases and should always be obtained before antibiotic administration. Bone aspiration or biopsy provides tissue for culture and histopathology when blood cultures are negative or when alternative diagnoses require exclusion.

Imaging plays a crucial role in diagnosis and monitoring of osteomyelitis but must be interpreted in context of timing and clinical presentation. Plain radiographs are often normal in the first 10-14 days of infection before bone destruction becomes visible, limiting their utility for early diagnosis but establishing baseline for comparison. Magnetic resonance imaging represents the most sensitive imaging modality, detecting bone marrow edema, soft tissue involvement, and abscess formation early in the disease course. Bone scintigraphy provides an alternative when MRI is unavailable or multiple sites require evaluation. Treatment consists of intravenous antibiotics initially, with transition to oral therapy once the child is afebrile and inflammatory markers are improving. Total antibiotic duration typically extends four to six weeks based on clinical and laboratory response. Empiric coverage should include antistaphylococcal agents such as nafcillin or cefazolin, with vancomycin added when MRSA prevalence is high or clinical features suggest severe infection. Surgical debridement is indicated for abscess formation, sequestrum, or failure to improve with antibiotic therapy alone.

<image>Panel A: Diagram showing vascular anatomy of the pediatric metaphysis with tortuous end-capillary loops that predispose to bacterial seeding during bacteremia. Panel B: MRI images of the distal femur showing bone marrow edema, periosteal reaction, and surrounding soft tissue changes characteristic of osteomyelitis. Panel C: Plain radiograph showing chronic osteomyelitis with periosteal reaction, cortical destruction, and sequestrum formation. Panel D: Graph showing typical C-reactive protein response to treatment with expected decline over 7-10 days guiding transition to oral antibiotics.</image>

Section 6: Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis encompasses a group of chronic inflammatory arthritides beginning before age sixteen years and persisting for at least six weeks in the absence of other identifiable causes. This represents the most common rheumatic disease of childhood, affecting approximately 1 in 1000 children, and constitutes an important cause of chronic disability in the pediatric population. The classification system recognizes several distinct subtypes based on the pattern of joint involvement and associated systemic features, with each subtype carrying different clinical implications, treatment approaches, and prognoses.

The classification of juvenile idiopathic arthritis into subtypes provides a framework for understanding disease manifestations and guiding management decisions. Oligoarticular disease, affecting four or fewer joints during the first six months, is the most common subtype and predominantly affects young girls with high rates of positive antinuclear antibodies and significant uveitis risk. Polyarticular disease involves five or more joints and is further subdivided based on rheumatoid factor status, with rheumatoid factor positive disease resembling adult rheumatoid arthritis. Systemic juvenile idiopathic arthritis, also known as Still disease, presents with quotidian fevers, evanescent salmon-colored rash, and multisystem inflammation including hepatosplenomegaly, lymphadenopathy, and serositis, in addition to arthritis. Enthesitis-related arthritis affects older boys, is associated with HLA-B27 positivity, and involves inflammation at tendon and ligament insertions in addition to joints. Psoriatic arthritis includes joint disease associated with psoriasis or characteristic features such as dactylitis.

The clinical presentation of juvenile idiopathic arthritis includes both articular and extra-articular manifestations that help distinguish subtypes and guide evaluation. Morning stiffness lasting more than fifteen minutes represents a hallmark feature, typically improving with activity throughout the day, in contrast to mechanical pain that worsens with use. Affected joints appear swollen and warm but typically lack the intense erythema seen in septic arthritis. Joint involvement may affect growth, causing either overgrowth from chronic hyperemia or undergrowth from physeal damage. Uveitis represents the most important extra-articular manifestation, occurring most commonly in oligoarticular disease with positive antinuclear antibodies. Uveitis is often asymptomatic, making regular ophthalmologic screening essential to prevent permanent visual impairment.

Diagnosis of juvenile idiopathic arthritis requires exclusion of other causes and relies primarily on clinical criteria rather than specific laboratory tests. Inflammatory markers including erythrocyte sedimentation rate and C-reactive protein are elevated in many but not all patients. Antinuclear antibody positivity occurs commonly in oligoarticular disease and identifies children at highest uveitis risk but lacks specificity. Rheumatoid factor and anti-cyclic citrullinated peptide antibodies identify patients with polyarticular disease resembling adult rheumatoid arthritis. Treatment follows a step-wise approach beginning with nonsteroidal anti-inflammatory medications for symptom control. Intra-articular corticosteroid injections provide effective disease control for oligoarticular disease and specific joint flares. Disease-modifying antirheumatic drugs, particularly methotrexate, form the backbone of therapy for polyarticular disease and inadequately controlled oligoarticular disease. Biologic agents targeting tumor necrosis factor alpha and other inflammatory mediators have revolutionized treatment of refractory disease and are now used earlier in the disease course to prevent joint damage.

<image>Panel A: Clinical photograph showing knee swelling in juvenile idiopathic arthritis with comparison to normal contralateral knee demonstrating warmth and effusion without intense erythema. Panel B: Slit lamp examination photograph showing anterior uveitis with cells and flare in the anterior chamber requiring prompt treatment to prevent synechiae. Panel C: Radiograph of hand showing periarticular osteopenia and erosions in polyarticular juvenile idiopathic arthritis. Panel D: Algorithm for treatment approach in juvenile idiopathic arthritis starting with NSAIDs and escalating through intra-articular steroids, DMARDs, and biologics based on disease control.</image>

Section 7: Knee Disorders

Knee pain represents one of the most common musculoskeletal complaints in pediatric practice, with causes ranging from benign overuse conditions to serious pathology requiring urgent intervention. The evaluation requires consideration of the child's age, activity level, and associated symptoms to narrow the differential diagnosis efficiently. Several distinct conditions commonly affect the pediatric knee, each with characteristic presentations that allow clinical diagnosis with minimal imaging in typical cases.

Osgood-Schlatter disease represents traction apophysitis at the tibial tubercle and is the most common cause of anterior knee pain in active adolescents. The pathophysiology involves repetitive stress at the patellar tendon insertion causing microavulsion of the cartilaginous apophysis during periods of rapid growth. The condition typically affects children aged ten to fifteen years during the adolescent growth spurt, with increased prevalence in those participating in sports involving running and jumping. Patients present with activity-related anterior knee pain localized to the tibial tubercle, which appears prominent and tender to palpation. Pain worsens with activities that stress the extensor mechanism including running, jumping, kneeling, and climbing stairs. Radiographs are generally unnecessary for diagnosis but may show fragmentation or prominence of the tibial tubercle. Treatment focuses on activity modification, ice application, and nonsteroidal anti-inflammatory medications, with symptoms typically resolving over months as growth slows, though tubercle prominence may persist.

Patellofemoral pain syndrome represents another common cause of anterior knee pain, particularly in adolescent females. This condition involves pain arising from the patellofemoral compartment, often attributed to patellar maltracking, quadriceps weakness, or increased patellofemoral joint stress. Patients present with diffuse anterior knee pain exacerbated by activities that load the patellofemoral joint including stair climbing, squatting, and prolonged sitting with the knee flexed. Physical examination may reveal tenderness with patellar compression and crepitus with knee flexion. Treatment emphasizes physical therapy focusing on vastus medialis strengthening and lower extremity flexibility, with activity modification and nonsteroidal anti-inflammatory medications for symptom control.

Additional conditions affecting the pediatric knee include discoid meniscus, tibial torsion, and popliteal cysts. Discoid meniscus represents an anatomic variant in which the meniscus, typically the lateral, is disc-shaped rather than crescentic, predisposing to clicking, locking, and pain from mechanical dysfunction or tearing. Magnetic resonance imaging confirms the diagnosis, and surgical treatment with partial meniscectomy or saucerization is indicated for symptomatic cases. Tibial torsion refers to rotational variation of the tibia that causes in-toeing or out-toeing gait, with internal tibial torsion common in toddlers and typically resolving spontaneously by age four to six years without treatment. Popliteal cysts, also known as Baker cysts, arise from the gastrocnemius-semimembranosus bursa and present as painless posterior knee swelling, typically resolving spontaneously in children and requiring no intervention unless symptomatic.

<image>Panel A: Clinical photograph of adolescent with Osgood-Schlatter disease showing prominent tibial tubercle with surrounding soft tissue swelling compared with normal contralateral knee. Panel B: Lateral knee radiograph demonstrating fragmentation and irregularity of the tibial tubercle apophysis characteristic of Osgood-Schlatter disease. Panel C: Diagram illustrating normal crescentic meniscus shape compared with discoid meniscus covering the entire tibial plateau. Panel D: Physical therapy exercises for patellofemoral pain syndrome demonstrating vastus medialis strengthening and iliotibial band stretching techniques.</image>

Section 8: Foot and Spine

Congenital and developmental conditions affecting the foot and spine constitute important components of pediatric musculoskeletal medicine, with many identified at birth or during routine surveillance. Understanding the spectrum of normal variation, the natural history of common conditions, and the indications for treatment allows appropriate counseling of families and timely referral when intervention is necessary.

Clubfoot, or talipes equinovarus, represents a complex congenital deformity affecting approximately 1 in 1000 live births and involving four components remembered by the mnemonic CAVE: cavus (high arch), adductus (forefoot turned inward), varus (hindfoot inverted), and equinus (plantarflexion at the ankle). The deformity is apparent at birth and may be isolated or associated with syndromes including myelomeningocele and arthrogryposis. The Ponseti method has revolutionized treatment and consists of serial manipulation and casting performed weekly, gradually correcting the deformity over six to eight weeks. Following correction, percutaneous Achilles tenotomy is required in most cases to address residual equinus. Maintenance of correction requires full-time use of abduction bracing for several months followed by nighttime bracing for several years to prevent recurrence.

Metatarsus adductus represents inward deviation of the forefoot relative to the hindfoot, creating a bean-shaped or curved lateral foot border. This common condition occurs in approximately 1 per 1000 births and is thought to result from intrauterine positioning. Assessment of flexibility distinguishes mild from more severe cases, with passively correctable feet carrying excellent prognosis for spontaneous resolution. Most cases resolve without treatment by age one to two years, with serial casting reserved for rigid deformity persisting beyond six months. Flatfoot, or pes planus, describes absence of the medial longitudinal arch and exists along a spectrum from normal variation to pathologic conditions. Flexible flatfoot, in which the arch reconstitutes with toe-standing or non-weight-bearing, is common and rarely symptomatic, requiring no treatment. Rigid flatfoot suggests underlying pathology such as tarsal coalition or vertical talus and warrants orthopedic evaluation.

Scoliosis describes lateral curvature of the spine exceeding ten degrees measured by the Cobb angle on radiography and may be idiopathic, congenital, or neuromuscular in origin. Adolescent idiopathic scoliosis is most common, predominantly affecting girls during the growth spurt, and is detected through school screening programs or routine examination. The Adams forward bend test screens for scoliosis by having the patient bend forward at the waist while the examiner observes for asymmetric rib or paravertebral prominence. Scoliometer measurement of trunk rotation greater than five to seven degrees warrants radiographic evaluation. Management depends on skeletal maturity and curve magnitude: observation with serial radiographs is appropriate for curves less than twenty-five degrees, bracing is indicated for curves between twenty-five and forty-five degrees in skeletally immature patients, and surgical fusion is considered for curves exceeding forty-five to fifty degrees or progressive despite bracing. Early referral to orthopedics ensures appropriate monitoring and timely intervention when indicated.

<image>Panel A: Clinical photograph of infant with untreated clubfoot demonstrating all four CAVE components with foot in equinus, varus, adductus, and cavus position. Panel B: Serial photographs showing progressive clubfoot correction through Ponseti casting over six weeks culminating in corrected alignment. Panel C: Demonstration of Adams forward bend test with asymmetric rib prominence on the convex side of thoracic scoliosis curve. Panel D: Standing posteroanterior spine radiograph showing measurement of Cobb angle for scoliosis with lines drawn along endplates of maximally tilted vertebrae.</image>

Section 9: Fractures

Pediatric fractures differ fundamentally from adult fractures due to the unique properties of growing bone and the presence of growth plates, creating both distinct fracture patterns and special considerations for healing and remodeling. Understanding these differences allows appropriate diagnosis, treatment, and prognostication in children with skeletal injuries. Recognition of fracture patterns concerning for non-accidental trauma remains essential, as early identification of child abuse can prevent further injury.

The structural characteristics of pediatric bone produce fracture patterns not seen in adults. The thick periosteum of children's bones often remains intact during fracture, limiting displacement and creating incomplete fracture patterns. Buckle or torus fractures result from compressive forces causing one cortex to buckle without complete break, appearing as subtle cortical angulation on radiographs and healing rapidly with simple immobilization. Greenstick fractures involve one cortex breaking completely while the opposite cortex bends without breaking, analogous to breaking a green twig. Complete fractures through both cortices also occur in children and may be transverse, oblique, or spiral depending on the mechanism of injury.

The physis, or growth plate, represents the weakest structure in the growing skeleton and is susceptible to injury from forces that would produce ligamentous injury in adults. Salter-Harris classification describes physeal fracture patterns based on the path of the fracture line relative to the physis. Type I fractures pass directly through the physis without involving bone, producing widening of the growth plate on radiographs or sometimes normal appearance requiring clinical diagnosis. Type II fractures traverse the physis then exit through the metaphysis, creating a triangular metaphyseal fragment and representing the most common pattern. Type III fractures pass through the physis then through the epiphysis into the joint, requiring anatomic reduction to restore the articular surface. Type IV fractures cross the metaphysis, physis, and epiphysis, also requiring anatomic reduction due to both physeal and articular involvement. Type V injuries involve crush of the physis without visible fracture and may only be recognized retrospectively when growth disturbance develops. Higher Salter-Harris types carry greater risk of growth arrest and require more careful follow-up.

Certain fracture patterns raise concern for non-accidental trauma and mandate thorough evaluation for child abuse. Multiple fractures at different stages of healing indicate recurrent injury over time. Metaphyseal corner or bucket-handle fractures result from shearing forces across the physis and are highly specific for abuse, particularly in non-ambulatory infants. Posterior rib fractures result from squeezing forces and likewise carry high specificity for abuse. Fractures in unusual locations such as the scapula, sternum, and spinous processes suggest inflicted injury. The presence of fractures inconsistent with the reported mechanism or developmental capabilities, such as spiral femur fractures in pre-ambulatory infants, should prompt careful evaluation. Skeletal survey radiography is indicated in children younger than two years with any concern for abuse to identify occult fractures throughout the skeleton.

<image>Panel A: Comparison radiographs showing buckle fracture of the distal radius with subtle cortical angulation versus greenstick fracture with incomplete cortical break. Panel B: Diagram illustrating Salter-Harris classification types I through V with fracture line relationship to physis, metaphysis, and epiphysis. Panel C: Radiograph showing classic metaphyseal corner fracture of the distal femur highly specific for non-accidental trauma in an infant. Panel D: Complete skeletal survey image set demonstrating standard views obtained when evaluating for occult fractures in suspected child abuse.</image>

Section 10: Growing Pains and Benign Conditions

Growing pains and other benign musculoskeletal conditions represent common concerns that bring children to medical attention, requiring clinicians to provide appropriate reassurance while maintaining vigilance for serious diagnoses. These conditions share benign self-limited courses but cause sufficient discomfort to disrupt sleep, activities, and family dynamics. Understanding the typical presentations enables confident diagnosis without unnecessary testing while recognizing atypical features that warrant further evaluation.

Growing pains represent a common cause of limb pain in children aged three to twelve years, affecting up to one-third of children during this period. Despite the name, growing pains have no demonstrated relationship to growth and remain idiopathic, though various theories including muscle fatigue, hypermobility, and decreased pain threshold have been proposed. The characteristic presentation includes bilateral lower extremity pain, typically in the thighs, calves, or behind the knees, occurring in the evening or during the night and resolving completely by morning. Physical examination is entirely normal, with no joint swelling, tenderness, limp, or limitation of motion. The diagnosis is clinical, and laboratory or imaging studies are unnecessary when the history and examination fit the typical pattern. Treatment focuses on reassurance, massage, stretching, and acetaminophen or ibuprofen for comfort during painful episodes. The condition resolves spontaneously, typically by adolescence.

Nursemaid's elbow, or radial head subluxation, represents a common injury in children aged one to four years resulting from longitudinal traction on the extended pronated forearm. The classic mechanism involves a caregiver pulling upward on the child's hand during a fall or to hurry the child along, though the history may not always be recalled. The annular ligament slips over the radial head and becomes entrapped in the radiohumeral joint. Affected children present refusing to use the arm, which is held in slight flexion and pronation against the body. The forearm, wrist, and hand appear normal without swelling or deformity. Diagnosis is clinical, and radiographs are unnecessary when the history and examination are typical. Reduction is performed using supination-flexion or hyperpronation techniques, with the examiner feeling a click as the ligament reduces. Immediate use of the arm following reduction confirms success, and no immobilization is required.

Recognition of red flag features distinguishes benign conditions from serious pathology requiring evaluation. Morning stiffness that improves with activity suggests inflammatory arthritis rather than benign limb pain. Night pain that awakens the child from sleep raises concern for malignancy and warrants investigation. Fever accompanying musculoskeletal complaints suggests infection. Systemic symptoms including weight loss, fatigue, and pallor may indicate malignancy or chronic inflammatory conditions. Focal bony tenderness, rather than diffuse limb pain, suggests fracture or osteomyelitis. Abnormal findings on physical examination including joint swelling, limited motion, limp, and neurologic abnormalities preclude the diagnosis of growing pains and require further evaluation.

<image>Panel A: Diagram illustrating typical locations of growing pains in the bilateral lower extremities with shading indicating thighs, calves, and popliteal regions. Panel B: Demonstration of nursemaid's elbow reduction using supination-flexion technique with examiner's thumb over radial head to feel reduction click. Panel C: Child with nursemaid's elbow holding the affected arm in characteristic position of flexion and pronation against the body. Panel D: Comparison chart of clinical features distinguishing growing pains from concerning conditions requiring evaluation including morning stiffness, night pain, fever, and examination findings.</image>

Summary

• The differential diagnosis of limping varies by age: toddler's fracture and DDH in young children, transient synovitis and Perthes in school-age children, and SCFE and Osgood-Schlatter in adolescents, with infection and trauma possible at any age

• Developmental dysplasia of the hip is identified through Ortolani and Barlow maneuvers in newborns and limited abduction in older infants, with ultrasound used before 4-6 months and radiography after ossification of the femoral head

• Transient synovitis presents with hip pain and limp after viral illness in children 3-10 years, with low or absent fever and normal inflammatory markers, distinguishing it from septic arthritis using Kocher criteria

• Slipped capital femoral epiphysis affects overweight adolescents with hip or knee pain and externally rotated extremity, requiring urgent surgical pinning without reduction attempts to prevent avascular necrosis

• Septic arthritis is diagnosed using Kocher criteria and joint aspiration showing WBC greater than 50,000, requiring surgical drainage for the hip and intravenous antibiotics typically for 3-4 weeks

• Osteomyelitis presents with fever, point tenderness over bone, and elevated inflammatory markers, with MRI as the most sensitive imaging modality and treatment requiring 4-6 weeks of antibiotics

• Juvenile idiopathic arthritis is classified by joint involvement pattern with oligoarticular being most common, requiring regular ophthalmologic screening for uveitis and stepwise treatment from NSAIDs through biologics

• Osgood-Schlatter disease presents with anterior knee pain and tibial tubercle tenderness in active adolescents, treated with activity modification and resolving as growth slows

• Salter-Harris classification describes physeal fractures types I-V, with higher types carrying greater risk of growth disturbance

• Growing pains present with bilateral evening or nighttime leg pain and completely normal examination, resolving spontaneously with symptomatic treatment

Key Terms

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