Approach to Suspected Physeal Fractures in the Emergency Department.

Growth plate (physeal) fractures are defined as a disruption in the cartilaginous physis of bone with or without the involvement of epiphysis or metaphysis. These represent around 15-18% of all pediatric fractures. It is important to diagnose physeal injury as early as possible, as misdiagnosis or delay in diagnosis may result in long term complications. Physeal injuries may not be initially obvious in children who present with periarticular trauma, and a high index of suspicion is important for diagnosis. Differential diagnosis for a Salter-Harris fracture includes a ligamentous sprain, acute osteomyelitis, or an extraphyseal fracture such as a Torus fracture. Salter-Harris I & Salter-Harris II growth plate fractures commonly are commonly managed by closed manipulation, reduction & immobilization. These are relatively stable injuries and can be retained by adequate plaster. Salter-Harris III & Salter-Harris IV fractures require anatomical reduction with the maintenance of congruity of joint. Physeal fractures can have many complications such as malunion, bar formation, acceleration of growth of physis, posttraumatic arthritis, ligament laxity and shortening of the bone. The key to well-healing fractures is successful anatomic reduction and patients must have regular follow-up for these injuries. Copyright:

INTRODUCTION

Growth plate (physeal) fractures are defined as a disruption in the cartilaginous physis of bone with or without the involvement of epiphysis or metaphysis.[1] These represent around 15%–18% of all pediatric fractures.[2] Other common types of fractures in childhood are torus fractures, greenstick fractures, and plastic deformities.[3]

The ligaments surrounding the growth plates are five times stronger than the growth plate itself, thus making the growth plate more susceptible to disruption which is in contrast to similar injuries in adults. Physeal injuries can be differentiated from sprains or ligament injuries by eliciting point tenderness – physeal tenderness will be present at bone; however, ligamentous tenderness will be present at the joint line.

Physeal fractures are not equal to any other adult articular or periarticular fractures because of acceptability criterion, remodeling potential, different fixation devices, and alignment goals as well as different follow-up protocols.[4] Bone age assessment using Greulich–Pyle atlas and charts can give an idea about growth remaining. If surgery is required, then any delay will worsen the prognosis.

BURDEN OF DISEASE

The true burden of physeal injury is unknown, and studies reveal that 30% of all fractures involved the physis,[3] with ~44% involving the distal radius.[5] Males are twice more affected than females and consistent with maturity of the bones, females are affected during younger age (11–12 years) than males (12–14 years). Injuries in the upper extremities are more common than the lower extremities, which is the same for both male and female. In children, ligaments are stronger and more compliant than in adults. Therefore, ligaments tolerate mechanical forces better than the physes. Epiphyseal fractures or apophyseal detachments are much more common than ligamentous injuries during childhood.

PEDIATRIC SKELETAL ANATOMY AND PHYSIOLOGY

There may be two growth plates present in the immature skeletal, namely horizontal (physis) and spherical growth plate (for epiphyseal growth). The horizontal growth plate is also mentioned as cartilaginous growth plate, physis, or epiphyseal plate. The epiphysis and epiphyseal plates are not synonyms. The area of a bone between the physis and the joint directly adjacent to it is the epiphysis. The epiphyseal plate is part of the metaphysis and is a hyaline cartilage plate where new growth takes place.

STRUCTURE OF PHYSIS

Basically, there are three zones in every physis: the resting zone or reserve zone, the proliferative zone, and the zone of hypertrophy.

The zone of hypertrophy can further be divided into the maturation zone, the degeneration zone, and the provisional calcification zone.

RESERVE/RESTING ZONE

This zone is immediately next to the epiphysis and consists of irregularly scattered chondrocytes. This layer supplies chondrocytes for proliferation and stores materials like lipid, glycogen, and proteoglycan. Injuries to this layer can cause cessation of growth.

PROLIFERATIVE ZONE

This zone is responsible for the number of chondrocytes. The cells are arranged in well-defined columns and provide a matrix for future growth.

HYPERTROPHIC ZONE

This zone is neighboring the metaphysis and subdivided into maturation, degeneration, and provisional calcification. Degeneration of cells releases calcium from matrix vesicles. The metaphyseal blood vessels penetrate this layer which allows for the growth of chondroblasts and osteoblasts. Finally, this leads to bone formation. This zone is the vulnerable part of the physis structure and is typically a source of fractures or adjustments (i.e. widening of physis in rickets).

PERIPHERY OF PHYSIS

There are two components of the periphery of physis:

Groove of Ranvier

Peripheral ring (of LaCroix).

Ranvier's groove is the wedged-shaped zone of cells that passes through the epiphysis. It provides the cells to the periphery of physis so that bone can grow in width. The peripheral ring is responsible for the overall stability of physis.[6]

The perichondral artery is the major source of nutrition of the growth plate.

BIOMECHANICS

The physeal fractures occur through various layers which depend upon the type of load applied: [7]

Compression force leads to fractures in the provisional calcification portion of the zone of hypertrophy

Shear force leads to disruption in the zone of hypertrophy

Tension force leads to fractures in the proliferative zone.

ETIOLOGY

The causes of physeal injuries include trauma, either acute or overuse injury, infection, burns, tumor, or irradiation.

Among these, traumatic injuries are most common. The prognosis of these fractures is not only dependent on the fracture pattern but also upon the age of the patient, health of surrounding tissues, method and reduction quality, immobilization method and length, and the involvement of physis.[8]

CLASSIFICATION

The most prevalent classification was proposed by Robert Salter and W. Robert Harris (1963), which is commonly known as Salter–Harris Classification.[9] It subdivides the physeal injuries into following:

Type I – In this injury, the fracture line traverses through the hypertrophic layer of physis, separating epiphysis from the metaphysis. These fractures are more common in younger patients, who have a thicker physis.[2] Clinical findings suggesting this injury can be more evident than radiological findings. Soft tissue swelling and tenderness may be the only evidence of injury. Sometimes, enlargement or new bone formation along the anatomical margins will be found in radiographs. The prognosis for these injuries is generally excellent

Type II – In this injury, a fracture will split the physis partially and will include a small piece of the metaphysis. This metaphyseal fragment is known as a Thurston Holland fragment. The fragmentary periosteum is always intact, which makes it easier to reduce. This type of physeal injury is the most common (75%). The prognosis of these injuries is good

Type III – This type of injury demonstrates a fracture line traversing through physis and extending into the joint through the epiphysis. This may lead to articular discontinuity, posttraumatic arthritis, and growth arrest.[2] The most common example of this type of injury is a Tillaux fracture in skeletally immature patients. The prognosis of these injuries is poor unless reduced anatomically

Type IV – This fracture goes obliquely through the metaphysis, passes through the physis, and goes into the joint through the epiphysis. The Thurstan Holland sign (fragment) is also seen in this fracture pattern. Medial malleolus fractures in children are commonly Type IV fractures

Type V – This type of fracture is typically a compression or crush injury to the physis. It is frequently challenging to diagnose this pattern. Follow-up and reexamination may demonstrate asymmetric Park–Harris growth lines showing a portion of physis growing normally; however, the opposite side showing impairment of growth. It is a rare type of injury pattern that has the worst prognosis.

A mnemonic “SALTER” has been used to help remember SH Types I–V.(I) S = straight across, (II) A = above, (III) L = lower or below, (IV) T = through, and (V) ER = erasure of growth plate or “crush.”

LIMITATIONS OF SALTER–HARRIS CLASSIFICATION

Thawrani et al.[10] examined the intra- and interobserver reliability of categorizing distal tibial fractures and establishing varying rates of intraobserver reliability and legitimately robust rates of interobserver reliability. Another limitation to the Salter–Harris classification system is that it cannot be used as an independent predictor of fracture prognosis.[2] Tzavellas et al.[11] observed moderate interobserver reliability that was improved with greater rater's experience. The Type II and Type III fractures were the best scored regardless of the rater's experience. Type I, IV, and V when in doubt require additional imaging.

SALTER TYPE VI

This type is typically not included in Salter–Harris Classification. It describes an injury to peripheral physis. It may lead to peripheral bony bridge formation, further leading to considerable angular deformity. Some authors refer to this type of injury as a Kessel fracture.[12]

Ogden[13] added three more types of fractures to Salter–Harris Classification:

Ogden VII – Epiphyseal fracture that does not involve the physis

Ogden VIII – Metaphyseal fracture affecting later growth

Ogden IX – Periosteal damage affecting later growth.

In an epidemiological study of physeal injuries, Peterson[14] maintains Salter–Harris I to IV as Peterson II to V and further supplements two more types:

Peterson I – Metaphyseal fractures that extend up to physis

Peterson VI – Articular and epiphyseal loss.

Briefly, there is also the AO pediatric comprehensive classification of long bone fractures which defines fractures as simple, wedge, and complex.

DIAGNOSIS

Clinical findings

It is important to diagnose physeal injury as early as possible, as misdiagnosis or delay in diagnosis may result in long-term complications. These children present with point tenderness following traumatic injury. Local swelling may be present, as well as loss of function of the extremity. Ligamentous laxity may not be diagnostic of physeal injury. If the child has localized tenderness at bone or physeal area, this injury can be indicative of physeal injury. If there is ligamentous tenderness or tenderness over the joint line, this may be more suggestive of a sprain.

Radiologic findings

A high degree of clinical suspicion is needed to diagnose physeal injury. In the presence of clinical suspicion, but with negative oblique radiographs or opposite side comparison radiographs, computer tomography (CT) or magnetic resonance imaging (MRI) is indicated for further diagnosis. It is typically recommended to image the joint above and the joint below the fracture to avoid missing associated injuries. In children <6 months of age, high-resolution ultrasound may be used to diagnose physeal disruption. A study of 163 children with suspected fractures found that ultrasound was the most reliable for the detection of simple humeral and femoral diaphyseal fractures.[15] It was also found to be reliable for fracture of the forearm. Ultrasound was found to be less dependable as a study for nondisplaced epiphyseal fractures such as Salter–Harris Type I, fractures of small bones of the hand and foot, and compound injuries. It can also differentiate physeal injury from ligamentous injury. CT may also be indicated to study fracture patterns requiring fixation. Bone scans are not of much help in making the diagnosis of physeal injuries.[161718] Advanced imaging (including CT and MRI) shows greater average displacement than plain radiographs.[19]

DIFFERENTIAL DIAGNOSIS

Differential diagnosis for a Salter–Harris fracture includes a ligamentous sprain, acute osteomyelitis, or an extraphyseal fracture such as a Torus fracture. A ligamentous sprain may have similar presentation and the patient may be unable to bear weight. However, the patient should not have bony point tenderness. A patient who has osteomyelitis may have other symptoms such as fever, swelling, and elevated laboratories such as a sed rate or C-reactive protein. They should also lack a history of an acute injury. A Torus fracture is a type of extraphyseal fracture that as the name suggests, does not involve the growth plate.

MANAGEMENT

Primary management

All patients must be assessed in emergency department as per or Advanced Trauma Life Support Protocol. In the secondary survey, one must try to rule out physeal injury in all pediatric injured patients.

Conservative

Very frequently, physeal fractures can be treated nonoperatively. The factors affecting decisions about modalities are the following: [20]

Age of patient

Site of injury

Mechanism of injury

Fracture pattern

Growth potential of involved physis

Plane of deformity

Condition of surrounding soft tissue.

SH I and SH II growth plate fractures are commonly used to manage closed manipulation, reduction, and immobilization. These are relatively stable injuries and can be retained by adequate plaster. Often, periosteal flaps and soft tissue covering the fracture can also interfere, making it challenging to reduce absolutely. This condition may require surgical intervention. To assess the efficacy of the reduction, these injuries must be reevaluated within seven to 10 days.[21]

Manipulation with closed reduction and traction must be made very carefully and gently in a fully relaxed patient to avoid any iatrogenic secondary injury. Repeated reduction attempts that can damage the germinal physis layer are preferable, however, to less than adequate reductions. More emphasis should be on traction rather than a forceful reduction to avoid crushing of physis. Absolute contraindications for reduction of displaced growth plate fractures are few. Relative contraindications for growth plate fracture reduction would be Salter–Harris I and II fractures with clinically insignificant displacement. Furthermore, fractures with greater displacement with late presentation (more than 1 week) should not be manipulated.[19] SH III and SH IV fractures require anatomical reduction with the maintenance of congruity of joint. Any malreduction may lead to malunion resulting in the disruption of the biomechanics of joint.

More serious injuries, particularly with intra-articular fractures, involve anatomical management with open reduction and internal fixation, which may avoid the physis crossover. If surgery is required, the treating surgeon must be aware of the remodeling potential of fracture, different surgical approaches for children than adults, need to use smooth K-wires in place of screws, and the appropriate times required for healing.[4] Preferably smooth pins should be parallel to physis in epiphysis and metaphysis. The oblique wires should only be passed if stability is compromised. Periosteal stripping should be avoided. Forceful manipulation must be avoided.

PROGNOSIS

The prognosis of physeal injury depends on:

Physeal damage severity

Skeletal patient age (as per SH)

Fracture site.

Children still growing with the potential for remodeling have a better prognosis. If the deformity is along the line of movements of joints, then the remodeling will be better. The site of fracture also influences remodeling. The distal femoral, proximal femoral, and proximal tibial physeal injuries have a greater rate of complications (as high as 40%).

RECENT ADVANCES

Tissue engineering

Many cartilage regeneration studies have been focused on joint cartilage, but some of these studies may also refer to cartilage plate growth. Some strategies such as implantation of chondrogenic cells may be a viable option for physeal injury. The future promises unique intracellular signaling solutions to posttraumatic growth plate disturbances.

Growth plate transplantations

Several materials (fat, fascia, silicon, bone cement) have been used to fill the gaps in physis after bar excision, but cartilage may prove ideal for this purpose.[22] Experiments have been conducted to evaluate its efficacy in physeal injury cases.

Physis distractions

Some studies are being conducted to study the role of physeal distraction to stimulate physis in physeal fractures.[23]

COMPLICATIONS

There can be several complications related to physeal injury. Some of these are:

Physeal fractures may lead to bar formation or malunion if not treated well. This may result in growth discrepancy or angular deformities. Barmada et al. found that the incidence of premature physis closure (PPC) occurred on SH I and II fractures with a physitic residual gapping of more than 3 mm following reduction was 60%; however, the incidence of a PPC in the gap of <3 mm was 17%. When residual gapping was reduced visibly, in most cases, the periosteum was kept within the physis. Another study, Rohmiller et al. found that the rate of PPC in distal tibial fractures varied based on the mechanism of injury. In supination-external-rotation type injury, the rate of PPC was 35% compared to 54% rate of PPC in pronation-abduction type injuries.[24] A study done by Cottalorda et al. showed that 48 children who had Type III or Type IV distal tibial and medial malleolus fractures underwent arthrotomy to achieve anatomical reduction if the displacement was >1 mm, and they had no ankle stiffness at follow-up[25]

In a small percentage of patients, there can be an acceleration of growth of physis resulting in apparent lengthening[25]

Hardware-related complications

Iatrogenic damage of physis

Arthrofibrosis resulting in stiffness of joint

Secondary posttraumatic arthritis of the joint can occur, especially from Salter–Harris Type III fractures if left untreated[26]

Possible shortening of the bone and ligament laxity can occur. A study by Torg et al. demonstrated two patients with Salter–Harris Type III fractures of the medial femoral condyle with minimal femoral shortening and anterior cruciate ligament laxity status post fracture reduction.[27]

Follow-up and Rehabilitation

SH 1 and 2 should be immobilized for 3–6 weeks

SH 3 and 4 should be immobilized for 4–8 weeks.

A patient can start unrestricted physical activities only after 4–6 weeks of implant removal. Follow-up radiographs are done at 6 months and 12 months (which may be done at 2 years as well).

SPECIAL SITUATIONS

Any fracture in a nonmobile, nonweight-bearing, or nonambulatory child should raise suspicion for child abuse.

CONCLUSION

Physeal injuries may not be obvious in children presenting with periarticular trauma. A high index of suspicion during evaluation is most important. Successful anatomic reduction is the key to healing. Regular follow-up of these injuries is a must to deal with any long-term complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.