Salter Harris Classification of Epiphyseal Injuries

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

GROWTH PLATE ANATOMY AND ITS FUNCTIONS

INTRODUCTION

The growth plate, also known as the physis, is the cartilaginous portion at the ends of long bones where longitudinal growth of the bone takes place.
This region of bone is characterized by high metabolic activity and is under the regulatory control of a wide variety of hormones and signalling compounds.
Hormonal regulation of the growth plate can be affected by trauma, medications, and other extrinsic variables causing growth plate abnormalities and subsequent growth disturbances

STRUCTURAL COMPOSITION

The maturation of chondrocytes in the physis is classically divided into five phases .

Resting phase
Proliferative phase
Prehypertrophic phase
Hypertrophic phase
Terminal phase

GERMINAL (RESTING) ZONE:

Contains chondrocytes in quisence
Replenishes proliferative zone
Injury causes cessation of growth

PROLIFERATIVE ZONE:

Contains chondrocytes in mitosis
Has abundant blood supply
Responsible for increase in bone length
Injury causes cessation of growth

HYPERTROPHIC (MATURATION) ZONE:

Cells accumulate glycogen/lipids
Weakest zone and site of physeal fractures

ZONE OF CALCIFICATION:

Mineralisation of matrix
Infiltration by metaphyseal blood vessels

PHYSEAL INJURY

Fracture through growth plate.
Unique to paediatric patients.
Prevalence – 10-30% of childhood fractures.
Age – bimodal peaks
Infancy, 10-12 years of age
commonest sites –
Distal femur
Distal tibia
Proximal tibia/fibula
Distal radius

ETIOLOGY

Trauma
Infection
Tumor
Vascular
Repetitive stress
Irradiation

CLINICAL PRESENTATION

History:
Pain/swelling around the affected joint
Upper limb – function limited by pain.
Lower limb – inability to bear weight on affected limb.
History of trauma.

On examination:

Swelling +
Deformity +/- (minimal if present)
Focal tenderness over physis +
Limited range of motion of joint

SALTER-HARRIS CLASSIFICATION (1963)

Type 1 – transverse fracture through the growth plate (6%)
Type 2 – fracture through the growth plate and metaphysis, sparing the epiphysis (75%
Type 3 – fracture through growth-plate and epiphysis, sparing the metaphysis (8%)
Type 4 – fracture through growth-plate, metaphysis and epiphysis (10%)
Type 5 – compression fracture of the growth plate(1%)

TYPE 1

A transverse fracture through the physis.
Physeal separation without any bony injury.
The growing zone is not injured, so growth disturbance is uncommon.
Clinically – point tenderness over the epiphyseal plate with swelling.
X-ray is normal, except widening of physeal plate.

TYPE 2

The most common type
Fracture occurs through the physis and metaphysis; epiphysis is spared.
The metaphyseal fragment is sometimes called the ‘Thurston-Holland fragment.
Limited growth disturbance; may cause minimal shortening.

TYPE 3

Fracture through the physis and epiphysis, metaphysis is spared.
Prone to chronic disability, because it extends into the articular surface of the bone.
However, rarely results in significant deformity.
Anatomic reduction (usually open) and stabilization.

TYPE 4

Involves all 3 elements of the bone, passing through the epiphysis, physis, and metaphysis.
An intra-articular fracture; thus, it can result in chronic disability.
Interfere with the growing layer of cartilage cells.
Can cause premature focal fusion of the involved bone leading to deformity of the joint.
Frequent around the medial malleolus, lateral condyle.
Anatomic reduction and adequate stabilization.

TYPE 5

A compression or crush injury of the physis, with no associated epiphyseal or metaphyseal fracture.
The clinical history is of paramount importance.
A typical history of an Axial load Injury.
X-ray at the time of injury shows no abnormality.
Usually diagnosed retrospectively. (Minimum 6 months)
Worst prognosis

MANAGEMENT

After thorough history and clinical examination.
X-ray:
It is difficult to assess as the physis is radiolucent and the epiphysis is incompletely ossified.
On x-ray:-
The physeal widening of the gap
Tilting of the epiphysis
Compare the injured side with the normal
Repeating x ray within few days

CT Scan:

To visualize fracture anatomy in severely comminuted fractures epiphysis and metaphysis

MRI Scan

Most accurate for fracture anatomy if done in acute period
Identifies formation of bony bridge earlier than x-rays

PLAN OF MANAGEMENT DEPENDS ON

Severity of the injury
Anatomic location of the injury
Classification of the fracture
Plane of the deformity
Patient age
Growth potential of the involved physis

TREATMENT

FOR TYPES 1 & 2

Closed reduction and immobilization in cast is done usually
Gentle reduction.
Never forceful and repeated. Reduce as soon as possible
Acute injuries must be immobilised in a slab, so as to allow some swelling from the fracture.
Repeat radiographs at weekly intervals to document
Maintenance of acceptable position until early bone healing.

SH type 1 injury managed with Percutaneous K-wires
SH type 2 managed with CC screws

SH type 3 managed with canulated screws
SH type 4 – Cannulated screw fixation

FOR TYPES 3 & 4:

Require anatomical realignment via ORIF
ORIF can be with lag screws or k-wires running parallel to physis

FOR TYPE 5:

Usually diagnosed retrospectively
However high index of suspicion must be maintained in high risk injuries

SURGICAL METHODS:

Bone bridge resection with fat interposition.
Bone bridge leads to angular deformity.
Interposition of fat prevents bone bridge formation.
Ipsilateral completion of arrest
Contralateral epiphysiodesis
Limb lengthening
Corrective osteotomy

BONE-BRIDGE RESECTION WITH FAT INTERPOSITION:-

Type V fractures are rarely diagnosed acutely, and unfortunately, treatment is often delayed until the formation of a Bony bar across the physis is evident.
Saucer and cup appearance.
Angular deformity.

Materials used for interposition are

Fat
Bone wax
Silicon rubber
Polymethylmethacrylate

FOLLOW UP

Check x-ray post-reduction.
Re-evaluated in the short term (7-10 days) to ensure maintenance of reduction.
Weekly follow-up till callus appears on x-ray.
After initial fracture healing has occurred, physeal fractures require additional follow-up x-rays 6 months and 12 months after injury to assess for growth disturbance.
May be extended up to 2 years.
2 phases:
ensuring bone healing
monitoring growth

REHABILITATION

Types 1 and 2 fractures are immobilized for 3 – 6 weeks
Types 3 and 4 fractures are immobilized for 4 – 8 weeks
Patient resumes unrestricted physical activities 4 – 6 weeks following removal of implants for fractures that required operative fixation.
Then gradually, ROM exercises are started.

PROGNOSIS