Paediatric Orthopaedics Flashcards
Growth Plates (Epiphyseal Plates)
Growth plates (epiphyseal plates) are found in the bones of children but not adults. They are the area at the ends of long bones that allow the bones to grow in length. They are made of hyaline cartilage and sit between the epiphysis and the metaphysis. Once the epiphysis and the metaphysis fuse during the teenage years, the growth plates become the epiphyseal lines.
The growth plate is generally stronger than the rest of the bone.
Bones in Children versus Adults
Children have growth plates, whereas adults do not. Children have more cancellous bone, which is the spongy, highly vascular bone in the centre of long bones. Adults have more cortical bone, which is the compact, hard bone around the outside. This makes children’s bones are more flexible but less strong. This makes children prone to “greenstick” fractures, where one side of the bone breaks whilst the other stays intact. Bones in children have very good blood supply and are able to heal much more quickly with less long term deformity compared with adults.
Fractures in Children versus Adults
The younger the child, the better and faster the healing of fractures. When bones fracture in children, they are more likely to break cleanly in two compared with adults.
Children are more likely to have greenstick fractures, where only one side of the bone breaks whilst the other side of the bone stays intact.
Children are more likely to have a buckle fracture (or torus fracture), due to less strength against compression.
Bone remodelling is the process where bone tissue is taken from areas of low tension and deposited in areas of high tension. This allows bone to change to the optimum shape for function. Bones in children have a high capacity for remodelling, which means that even if they are set at an incorrect angle, they will remodel over time to return to the correct shape.
Types of Fracture
Buckle (torus)
Transverse
Oblique
Spiral
Segmental
Salter-Harris (growth plate fracture)
Comminuted
Greenstick
Fractures at the growth plate
Fractures through the growth plate can cause issues with growth in that bone. Growth plate fractures are graded using the Salter-Harris classification. The higher the Salter-Harris grade, the more likely the fracture is to disturb growth.
Use the SALTR mnemonic to remember the types:
Type 1: Straight across
Type 2: Above
Type 3: BeLow
Type 4: Through
Type 5: CRush
Principles of managing fractures
Always keep safeguarding in mind when children present with fractures. Does the story make sense? Has this happened before? When there is doubt, discuss the case with a senior and consider a safeguarding referral.
The first principle is to achieve mechanical alignment of the fracture by:
Closed reduction via manipulation of the joint
Open reduction via surgery
The second principle is provide relative stability for a period of time, to allow healing. This can be done by fixing the bone in the correct position while it heals. There are various ways the bone can be fixed in position:
External casts
K wires
Intramedullary wires
Intramedullary nails
Screws
Plate and screws
Pain management in fractures
Pain management in children is slightly different than adults. The World Health Organisation have a pain ladder for children that has only two steps:
Step 1: Paracetamol or ibuprofen
Step 2: Morphine
If a child requires morphine they generally need admission for a serious illness.
TOM TIP: Examiners like to test your knowledge on the pain medications that are not used in children. Codeine and tramadol are not used in children as there is unpredictability in their metabolism, so the effects vary too greatly to make them safe and effective options. Aspirin is contraindicated in children under 16 due to the risk of Reye’s syndrome (except in certain circumstances such as Kawasaki disease).
Hip pain
Joint pain is a common paediatric presentation, particularly an acute limp.
Hip pain will present differently depending on the developmental age of the child. They may present with:
Limp
Refusal to use the affected leg
Refusal to weight bear
Inability to walk
Pain
Swollen or tender joint
TOM TIP: Examiners like to test your knowledge about the causes of hip pain in a child. It is worth being familiar with the differential diagnosis and distinguishing features of each cause.
Causes of Joint Pain
It is helpful to remember the differential diagnosis in the context of the age of the child. There is some overlap in ages.
0 – 4 years:
Septic arthritis
Developmental dysplasia of the hip (DDH)
Transient sinovitis
5 – 10 years:
Septic arthritis
Transient sinovitis
Perthes disease
10 – 16 years:
Septic arthritis
Slipped upper femoral epiphysis (SUFE)
Juvenile idiopathic arthritis
Red Flags for Hip Pain
Suspect serious pathology if there are red flags:
Child under 3 years
Fever
Waking at night with pain
Weight loss
Anorexia
Night sweats
Fatigue
Persistent pain
Stiffness in the morning
Swollen or red joint
Managing joint pain
Criteria for urgent referral for assessment in a limping child, adapted from NICE clinical knowledge summaries:
Child under 3 years
Child older than 9 with a restricted or painful hip
Not able to weight bear
Evidence of neurovascular compromise
Severe pain or agitation
Red flags for serious pathology
Suspicion of abuse
Management will focus on identifying the underlying cause. Investigations that can be useful include:
Blood tests including inflammatory markers (CRP and ESR) for JIA and septic arthritis
Xrays are used to diagnose fractures, SUFE and other boney pathology
Ultrasound can establish an effusion (fluid) in the joint
Joint aspiration is used to diagnose or exclude septic arthritis
MRI is used to diagnose osteomyelitis
Septic arthritis
Septic arthritis refers to infection inside a joint. This can occur at any age, but is most common in children under 4 years. Infection in a joint is an emergency, as the infection can quickly begin to destroy the joint and cause serious systemic illness. Septic arthritis has a mortality around 10%. Therefore, early recognition and management is essential.
Septic arthritis is a common and important complication of joint replacement. It occurs in around 1% of straight forward hip or knee replacements. This percentage is higher in revision surgery.
Presentation of septic arthritis
Septic arthritis usually only affects a single joint. This is often a knee or hip. It presents with a rapid onset of:
Hot, red, swollen and painful joint
Refusing to weight bear
Stiffness and reduced range of motion
Systemic symptoms such as fever, lethargy and sepsis
Septic arthritis can be subtle in young children, so always consider it as a differential when a child is presenting with joint problems.
Common bacterial causes of septic arthritis
Staphylococcus aureus is the most common causative organism.
Other bacteria:
Neisseria gonorrhoea (gonococcus) in sexually active teenagers
Group A streptococcus (Streptococcus pyogenes)
Haemophilus influenza
Escherichia coli (E. coli)
Differentials of septic arthritis
Transient sinovitis
Perthes disease
Slipped upper femoral epiphysis
Juvenile idiopathic arthritis
Managing septic arthritis
Have a low threshold for treating a patient for septic arthritis until it has been excluded with examination of the joint fluid. Be particularly cautious with immunosuppressed patients.
Patients with suspected septic arthritis require admission to hospital and involvement of the orthopaedic team.
The joint should be aspirated prior to giving antibiotics where possible. Send the sample for gram staining, crystal microscopy, culture and antibiotic sensitivities. The joint fluid may be purulent (full of pus). The gram stain will come back quite quickly and may give a clue about the organism. The full culture will take longer.
Empirical IV antibiotics should be given until the microbial sensitivities are known. Antibiotics are usually continued for 3 to 6 weeks in total when septic arthritis is confirmed. The choice of antibiotic depends on the local guidelines.
Patients may require surgical drainage and washout of the joint to clear the infection in severe cases.
Transient Synovitis
Transient synovitis is sometimes referred to as irritable hip. It is caused by temporary (transient) irritation and inflammation in the synovial membrane of the joint (synovitis). It is the most common cause of hip pain in children aged 3 – 10 years. It is often associated with a recent viral upper respiratory tract infection.
Children with transient synovitis typically do not have a fever. Children with joint pain and a fever need urgent management for septic arthritis.
Presentation of transient synovitis
Symptoms of transient synovitis often occur within a few weeks of a viral illness. They present with acute or more gradual onset of:
Limp
Refusal to weight bear
Groin or hip pain
Mild low grade temperature
Children with transient synovitis should be otherwise well. They should have normal paediatric observations and no signs of systemic illness. When other signs are present, consider alternative diagnoses.
Managing transient synovitis
General management of transient synovitis is symptomatic, with simple analgesia to help ease the discomfort. The challenge is to establish the correct diagnosis and exclude other significant pathology, particularly septic arthritis.
NICE clinical knowledge summaries provide guidance on managing transient synovitis: Children aged 3 – 9 years with symptoms suggestive of transient synovitis may be managed in primary care if the limp is present for less than 48 hours and they are otherwise well, however they need clear safety net advice to attend A&E immediately if the symptoms worsen or they develop a fever. They should also be followed up at 48 hours and 1 week to ensure symptoms are improving and then fully resolve.
Prognosis of transient synovitis
Typically there is a significant improvement in symptoms after 24 – 48 hours. Symptoms fully resolve within 1 – 2 weeks without any lasting problems. Transient synovitis may recur in around 20% of patients.
Perthes disease
Perthes disease involves disruption of blood flow to the femoral head, causing avascular necrosis of the bone. This affects the epiphysis of the femur, which is the bone distal to the growth plate (physis). The full name is Legg-Calvé-Perthes disease. It occurs in children aged 4 – 12 years, mostly between 5 – 8 years, and is more common in boys.
It is described as idiopathic, meaning there is no clear cause or trigger for the avascular necrosis. One theory suggests that repeated mechanical stress to the epiphysis may interrupt the blood supply.
Over time there is revascularisation or neovascularisation and healing of the femoral head. There is remodelling of the bone as it heals. The main complication is a soft and deformed femoral head, leading to early hip osteoarthritis. This leads to an artificial total hip replacement in around 5% of patients.
Presentation of Perthes disease
Perthes disease present with a slow onset of:
Pain in the hip or groin
Limp
Restricted hip movements
There may be referred pain to the knee
There will be no history of trauma. If the pain is triggered by minor trauma, think about slipped upper femoral epiphysis, particularly in older children.
Investigating Perthes disease
The initial investigation of choice in Perthes disease is an xray, however this can be normal.
Other investigations that can be helpful in establishing the diagnosis are:
Blood tests are typically normal, particularly inflammatory markers that are used to exclude other causes
Technetium bone scan
MRI scan
Managing Perthes disease
The severity of Perthes disease varies between patients.
Initial management in younger and less severe disease is conservative. The aim of management to maintain a healthy position and alignment in the joint and reduce the risk of damage or deformity to the femoral head. This is with:
Bed rest
Traction
Crutches
Analgesia
Physiotherapy is used to retain the range of movement in the muscles and joints without putting excess stress on the bone.
Regular xrays are used to assess healing.
Surgery may be used in severe cases, older children or those that are not healing. The aim is to improve the alignment and function of the femoral head and hip.
Slipped upper femoral epiphysis
Slipped upper femoral epiphysis (SUFE) is also known as slipped capital femoral epiphysis (SCFE). It is where the head of the femur is displaced (“slips”) along the growth plate.
It is more common in boys and typically presents aged 8 – 15 years, with the average age of 12 in boys. It presents slightly earlier in females, with an average age of 11 years. It is more common in obese children.
