McCance 46 - from notes- Musculoskeletal Development

Musculoskeletal Development

• Bone formation begins around the sixth week of gestation
• Bone cell precursors are delivered to formation sites
• These cells aggregate at primary ossification centers

Types of Bone Formation

• Intramembranous bone formation occurs within the mesenchyme
• It forms flat bones like the cranium and clavicles
• Mesenchyme vascularization leads to osteoblast aggregation
• Solid bone formation occurs in intramembranous bone formation
• Endochondral bone formation develops new bone from cartilage
• Mesenchymal tissue forms a cartilage anlage
• Blood vessel invasion brings osteoprogenitor cells
• Primary calcification centers develop

Bone Growth

• Long bone length increases at the physeal plate
• This occurs through endochondral ossification
• Cartilage cells multiply on the epiphyseal side
• Growth hormone stimulates the growth plate
• Regulatory peptides affect the growth plate
• Cell interactions and the extracellular matrix also influence bone growth
• Nutrition and hormones also factor into bone growth

Skeletal Development

• The axial skeleton changes shape during growth
• Newborns have a kyphosed spine
• The cervical spine develops a lordotic curve as head control is gained
• The lumbar spine's lordotic curve develops with sitting
• The appendicular skeleton grows faster than the axial skeleton in childhood

Musculoskeletal Alterations

• Can be congenital, hereditary, or acquired

Congenital Defects

• Syndactyly involves webbing of fingers
• It is the most common upper extremity congenital defect
• Simple webbing is surgically corrected between 6 months and 1 year
• Complex cases may involve bone and nail fusion
• Developmental Dysplasia of the Hip (DDH) involves abnormal development of the proximal femur and/or acetabulum
• Risk factors for DDH include family history, female gender, and breech presentation
• Clinical signs of DDH include asymmetry of gluteal folds
• Limited hip abduction can also indicate DDH
• The Barlow and Ortolani maneuvers are diagnostic tools
• Treatment for DDH includes a Pavlik harness for infants younger than 6 months
• Congenital foot deformities are found in approximately 4% of newborns

Foot Deformities

• Metatarsus Adductus involves forefoot adduction deformity
• Mild cases of metatarsus adductus often self-correct
• Severe cases may require serial casting
• Clubfoot (Equinovarus Deformity) involves the foot turning inward and downward
• Treatment for idiopathic equinovarus includes the Ponseti casting technique
• Pes Planus (Flatfoot) is common in babies
• Asymptomatic flexible flatfoot does not require treatment

Abnormal Bone Density or Modeling

• Osteogenesis Imperfecta (OI) is a collagen-related bone dysplasia
• OI causes increased fracture rate and bone deformation
• The Sillence classification categorizes OI based on inheritance and clinical presentation
• Evaluation for OI is based on clinical signs
• OI can be diagnosed prenatally
• Rickets involves failure of growing bone to mineralize
• It leads to soft bones and skeletal deformity
• Rickets is due to insufficient vitamin D
• Symptoms include hypotonia and muscle weakness
• Scoliosis is a rotational spine curvature
• Scoliosis can be nonstructural or structural
• Most structural scoliosis cases are idiopathic
• Diagnosis is by radiographic examination

Bone Infection

• Osteomyelitis is a bone infection
• It often affects children ages 3-12
• Bacteria enters through the bloodstream and lodges in the medullary cavity
• The causative microorganism varies with age

Rheumatologic Disorders

• Juvenile Idiopathic Arthritis (JIA) is the most common childhood rheumatologic disorder

Avascular Diseases of Bone

• Osteochondrosis involves insufficient blood supply to growing bones
• Legg-Calvé-Perthes (LCP) Disease involves interrupted blood supply to the femoral head
• Osgood-Schlatter Disease involves tendinitis of the anterior patellar tendon and osteochondrosis of the tibial tubercle

Cerebral Palsy

• Cerebral Palsy (CP) causes nonprogressive movement and posture disorders
• It results from injury or malformation of the developing central nervous system

Neuromuscular Disorders

• Involve Inherited disorders causing progressive muscle fiber loss
• Duchenne muscular dystrophy (DMD) is a prevalent neuromuscular disorder
• Spinal muscular atrophy (SMA) is also a common neuromuscular disorder