Mary Allen
Salter-Harris fractures: Surgical treatment of intra-articular fractures at the elbow.
In juveniles, intra-articular fractures pose a particular risk because the involvement of the epiphyseal plates can result in marked growth retardation and consequent joint incongruity and limb shortening. In miniature breeds, in particular, the elbow is so fragile that even falling off the sofa can lead to catastrophe. What is then important is a quick diagnosis and an optimal reduction and tissue-sparing but stable fixation of the fracture.
The article shows the difficulties of radiological diagnosis and the different variants of surgical treatment.
Most fractures of the distal humerus occur between the fourth and eighth months of life because the stability of this area is reduced by the growth plate and the supratrochlear foramen. Between the 9th and 12th months of life, the distal humeral epiphyseal plates ossify in most dog breeds. After that, there is no longer any growth in length. The Salter-Harris system was developed in human medicine and transferred to domestic animals for orientation on fractures involving the joint. The prognosis for recovery of joint function decreases from type 1 to type 5.
Classification and Occurrence
Type 1 describes the fracture above the epiphyseal plate, the cartilage line of maximum growth. X-rays show increased width of the growth plate, and the epiphysis may be dislocated. The cartilage tissue is usually not significantly injured, after the restoration of the connection growth proceeds undisturbed. Growth retardation is rare. Crepitation is common on physical examination. But it can also just be painful. When dislocated, the ends of the bones can move significantly apart. There is then no longer any crepitation, but there is considerably increased mobility. This type is most common distal to the femur in the knee and cranial to the femur in the femoral head epiphysis with subsequent femoral head necrosis. In the knee, the prognosis is very good with stable fixation.
Type 2 is a fracture above the epiphysis with a detachment of parts of the diaphysis. After reconstruction, there may be a slight shortening of the limbs, which is well compensated for by adjusting the angles. This type is most common, particularly distal to the femur. Type 3 runs above the epiphysis. At the same time, the trochlea is also injured. This damages the growth plate. The articular surface is involved in the fracture. During the reconstruction, care must be taken to restore the articular surface step-free.
Type 4 fractures are diaphyseal and transverse the growth plate and articular surface in the trochlear fracture.
Consequently, the epiphysis, diaphysis, and metaphysis are affected. There is a high risk of joint incongruity. In addition, postoperative growth disorders occur. Type 3 and 4 fractures are common and almost exclusively affect the elbow.
Type 5 fractures result from compression of the growth plate. There is no disconnection, but the damage to the cartilage zone always leads to premature epiphyseal closure and growth arrest. The diagnosis is difficult because, apart from unclear pain, there are no clinical or radiological signs of the fracture. The presence of this fracture is usually found later, taking into account the unremarkable X-ray and the medical history. It occurs most frequently on the ankle and carpal joints (distal ulna, more rarely distal radius) and on the distal tibia.
Damage to the growth plate can lead to significant growth disorders. After growth is complete, there can be a 20-25% difference in length compared to a healthy limb. This is often compensated by the steeper angulation in the elbow, knee, or tarsal joint.
Therapy
Due to the sensitivity of the growth zones, the surgical treatment must be carried out very quickly and extremely gently. Steps in the joint surface should be avoided. Type 1 and 2 fractures can be treated with pins in most cases. A lag screw is used to repair the articular surface in type 3 and 4 fractures. In the case of very small dogs, however, this treatment would lead to injury to the growth plate, since it would almost always lie in the drill hole. These animals (usually lighter than 2 kg) should be carefully treated with the most precise reduction of the articular surface completely epiphyseal or diaphyseal with small Kirschner wires that are not crossed in the line of the trochlear fracture. Stability is ensured by thicker wires in the metaphysis. The epiphyseal plate has to be drilled through twice. Since the wires stabilize the fracture without any compression, the bone can grow undisturbed during the healing phase.
The joint should not be shut down during the follow-up treatment. The dog is kept in a small room or box and only led outside on a leash. Early remobilization is a crucial part of therapy.
The sensitivity of the area explains why early diagnosis is so important. If a Salter-Harris fracture is suspected, a diagnosis should only be made if optimally positioned, good-quality radiographs in two planes are available. The changes are often very subtle. However, because primary care is only successful for a short time, the veterinarian does not get a second chance with this injury!