Growth plate fractures and disorders Flashcards

1
Q

Growth plate function

A

Growth plate is the site of longitudinal bone growth

Longitudinal bone growth occurs via endochondral ossification

Anything that interferes with growth plate function before growth plate closure can have an impact on overall bone length and/or alignment

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2
Q

Two main types of growth plate

A

Pressure growth plates – found at the ends of long bones responsible for most of bone growth e.g. distal radial growth plate

Traction growth plates – found where muscles insert or originate & these contribute little to bone growth e.g. tibial tuberosity

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3
Q

Which is more likely to occur in immature animals - physeal fractures or luxations?

A

The physis is 3-5 times weaker than the attachment of ligaments & joint capsule to bone so physeal fractures are much more likely in immature animals than luxations.

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4
Q

Salter Harris classification

A

Classified injuries of the ‘pressure’ physes in man to give prognostic information.

The classification is not very useful in prognosticating the outcome in small animals.

Instead each injury should be evaluated individually and a guarded prognosis given until evidence for continued growth is seen radiographically

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5
Q

Type I physeal fractures

A

Physeal separation – metaphysis displaced from epiphysis

Transverse fracture through growth plate (physis).
Account for close to 40% of physeal fractures in dogs and cats.

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6
Q

Type II physeal fractures

A

Small corner of metaphysis fractured

Fracture through the growth plate and the metaphysis that spares the epiphysis.

Account for close to 40% of physeal fractures in dogs and cats.

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7
Q

Type III physeal fractures

A

Fracture through epiphysis and physis. Metaphysis unaffected.

Around 3% of physeal fractures are type III.

Rare

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8
Q

Type IV physeal fracture

A

Fracture through epiphysis, physis extending into metaphysis.

Accounts for 19% of physeal fractures in dogs and cats.

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9
Q

Type V physeal fracture

A

Compression or crush injury of growth plate

Resulting in a decrease in the perceived space between the epiphysis and the diaphysis on x-ray.

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10
Q

Type VI physeal frcture

A

Bony bridge across growth plate – angular deformity

Rare

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11
Q

Principles for repair of physeal fractures

A

Early surgery is important

Warn O about risk of complications

More important that articular suface integrity is maintained than function of physis

Fragments often small and delicate - careful surgery, especially with epiphyseal fragment (most germinal cells remain there)

Some can be managed by external coaptation

Should repair using implants that minimally disrupt physis - small smoot k wires perpendicular to physis is ideal

Should affect <10% SA of the growth plate

Implants that cross the physis should be avoided e.g. bone plates or lag screws

Removal of implants once fracture has healed

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12
Q

Proximal Humeral Growth plate fractures

A

Rare

Salter Harris type I & II (commonest) - the distal humerus displaces in a caudoproximal direction. Check neurological function. Reduce and repair with a single IM pin or Kwire.

Salter Harris type III (very rare) - may involve both the humeral head and the greater tubercle. These are articular fractures and need ORIF with K wire and lag screws.

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13
Q

Distal Radial & Ulna Physeal Fractures

A

Fractures through the growth plate are occasionally seen in immature animals.

The fracture is usually a Salter Harris type I or II.

More importantly there may be a concurrent Type V ulna growth plate injury that will not be recognised on early radiographs and may result in premature closure of the distal ulna growth plate and subsequent angular deformity.

Owners should always be warned of the likelihood or possibility of growth plate damage and subsequent angular limb deformity in any immature animals suffering limb trauma

Treatment – cross pins or open reduction and external coaptation. In minimally displaced fractures with an intact ulna external coaptation alone may be used.

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14
Q

Distal Tibial Physeal fractures

A

The physeal fragment is often very small and usually not big enough to apply a T plate, therefore fracture is usually stabilised with cross pins.

Reduction of the fracture can be difficult so early repair is recommended.

As only small weak implants can be used to repair the small fragments (adaptation osteosynthesis) some post operative support – a cast or splint - is needed until repair has been documented radiographically.

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14
Q

Femoral head fractures

A

These are not uncommonly seen in both dogs and cats.

Fractures can occur through the growth plate of the femoral head. These fractures will commonly result in disruption to the blood supply of the femoral head.

Signalment
* Cats or dogs usually skeletally immature – from 3-10mths of age
* Males or females of any breed affected

Early repair is imperative

Surgical approach – craniolateral or by osteotomy of the greater trochanter

Techniques for repair – parallel K wires or lag screws or a combination of both.

FHNE – last resort treatment.

Post operative care – restricted exercise until there is radiographic evidence of fracture healing

Radiography – a classic ‘apple coring’ of the femoral neck occurs which is a result of remodelling and resorption of bone during the healing phase. This is evident radiographically as a narrowing of the femoral neck at approximately 4 weeks post op – these changes should gradually resolve.

Prognosis – slightly guarded as the growth plate will often close prematurely resulting in a short femoral neck and coxa vara. Non union will occur if the fracture repair is unstable. If fracture repair fails then a FHNE should be performed (or possibly a THR)

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15
Q

Femoral neck fractures

A

These have a better prognosis than femoral head fractures as the growth plate is unaffected and the blood supply to the femoral head is less damaged.

Repair – lag screws (and Kirschner wires).

16
Q

Premature physeal arrest

A

may occur if there is injury to the germinal cells or blood supply to the physis.

Compression damage or fractures traversing the growth plate are more likely to cause growth arrest than epiphyseal fractures

Not just Salter Harris type V and VI injuries which result in premature growth plate closure, all physeal injuries can lead to premature closure and owners should be warned accordingly at the time of the initial injury.

17
Q

Magnitude of problem of premature growth plate closure

A

Age: 95% of growth is complete by 7 months of age so an injury in a 7 month old dog will have much less effect than a similar injury in a 3 month old animal

Which growth plate is affected: premature closure of the distal ulna physis will have a greater affect than premature closure of the distal humerus due to the intimate relationship between the radius and ulna.
The different growth plates at the opposite ends of each bone are often responsible for different percentages of the total growth.
For example the proximal radius is responsible for approximately 40% of total growth and the distal for 60%, the proximal ulnar physis is responsible for 15% of total ulna growth and the distal ulnar physis for 85%.

18
Q

Principles for corrective surgery for premature growth plate closure/angular limb deformity

A

Restore joint congruity

Restore paw to a functional position

Correct rotational deformity

Correct angular deformity

Restore limb length

19
Q

Osteotomy

A

an elective surgical division of the bone.

20
Q

Ostectomy

A

resection of a piece of bone

21
Q

Common angular deformities

A

Premature closure of the distal ulna growth plate - radius curvus

Premature Closure of The Distal Radial Growth Plate

Premature Closure of the Distal Radius and Ulna Growth Plates

Premature Closure of the Distal Femoral And / Or the Proximal Tibial Growth Plate

Premature Closure of The Caudal Proximal Tibial Growth Plate

Premature Closure of The Distal Tibial Growth Plate

22
Q

Premature closure of the distal ulna growth plate

A

The distal ulna growth plate is the most commonly affected of all the growth plates.

The conical shape of the distal ulnar physis is unique to the dog - in all other animals the radial and ulnar physes are flat and predisposed to shearing fractures.

The canine distal ulnar physis is unable to shear so shear forces are transformed into compressive forces.

Large dogs seem to be most frequently affected, often bilaterally and there may not be a history of trauma.

Cessation or slow growth is ’normal’ in some chondrodystrophic breeds such as Basset Hounds, Dachshunds or Skye Terriers.

Retained cartilage cores occasionally seen in Giant and large Breeds may also lead to premature closure.

Affected animals present with Radius Curvus.

The radius continues to grow while the ulna acts as a bowstring.

23
Q

Radius curvus

A

Cranial & then medial bowing of the radius

Carpal valgus

External rotation of the foot (supination) and

Subluxation of the humeroulnar joint and radiocarpal bone

24
Q

Presenting complaint for radius curvus

A

either for lameness due to elbow subluxation or because owners have noticed the angular deformity.

25
Q

Diagnostic imaging for radius curvus

A

Must include the whole antebrachium including the elbow and carpal joints. Both limbs should be radiographed for comparison and to check for bilateral problems.

26
Q

Treatment options for radius curvus

A

Young dog (< 6 months with residual growth potential)
i. Cut ‘bow-string’ and stop growth - Partial ulna ostectomy with temporary transepiphyseal bridging (TTB) of the craniomedial aspect of the distal radial growth plate. Use staples or 2 screws and a figure of 8 wire for the TTB.
ii. Cut ‘bow-string’ - Removal of the distal ulna growth plate with part of the distal ulna

Skeletally mature dog:
i. Definitive correction - Ulna osteotomy and corrective osteotomy of radius. Corrective radial osteotomy may involve either a cuneiform osteotomy or an oblique osteotomy.