Physeal injuries

In children, the physes are bio mechanically weaker than ligaments or their insertions. Consequently, the physes are the most vulnerable to failure.

Classification

Salter-Harris classification system

• Type I - Complete fracture through the hypertrophic zone of the physis, completely separating the epiphysis from the metaphysis. Nondisplaced Salter-Harris type I fractures are difficult to diagnose radiographically due to the normal radiolucent physis, and therefore, a clinical exam is paramount to making the correct diagnosis.
• Type II  - Type I fracture with a metaphyseal spike attached to the Epiphyseal fragment on the compression side of the fracture. This metaphyseal spike is referred to as the Thurston-Holland sign.
• Type III - Through the physis and extending through the epiphysis, thus disrupting the articular surface.
• Type IV - Fracture traversing the metaphysis, physis, and epiphysis.
• Type V - Compression fracture involving only the physis. A type V fracture is difficult to diagnosis prospectively secondary to the lack of displacement of the normally radiolucent physis but has the highest prevalence of growth plate disturbance. Consequently, type V injuries are usually diagnosed retrospectively when a growth disturbance is recognized in a patient with an appropriate history.

Treatment

The goal of physeal fracture management is to achieve anatomic reduction of the physis without further injuring the physis to minimize the likelihood of physeal growth arrest.

If anatomic reduction of the physeal cartilage is not achieved, there is increased likelihood that a bone bridge will form across the physis, resulting in a tether. A tether in the centre of the physis may lead to limb length inequality, whereas a peripheral tether may result in angular deformity. Anatomic reduction of displaced physeal injuries should be achieved as atraumatically as possible to minimize further injury to the physeal cartilage.

If cast immobilization alone is inadequate for a given physeal fracture, internal fixation techniques are utilized, which minimize hardware crossing the physis. Ideally, hardware is placed such that fixation occurs in the epiphysis and metaphysis, but not crossing the physis. Unfortunately, certain fractures require hardware crossing the physis.  When hardware is placed across a physis, smooth pins are preferable to threaded pins or screws, and central hardware placement is preferable to hardware placement in the physeal periphery. The peripheral regions of the physis are less tolerant to injury and hardware placement than is the central region.

Delayed reduction

Most authors recommend prompt reduction of displaced physeal fractures because each day of displacement will make reduction more difficult. The recommended time after injury at which one can attempt a reduction of a displaced physeal fracture varies from 5 to 10 days, with a few recommending attempting treatment of Salter 1 or 2 physeal fractures more than 7 days after injury. Exceptions are made for intraarticular fractures presenting late, and most recommend attempting late treatment of type 3 and 4 physeal fractures.

Deciding on the appropriate treatment of a displaced physeal fracture that presents late is often difficult. Reduction attempts to improve the alignment of the limb may cause damage to the growth plate, leading to more severe problems in the future. The clinician is then faced with the decision to attempt a reduction in hopes of improving alignment but risking physeal injury, or to let the fracture heal in a malunited position and hope for remodelling. Repeated efforts at reduction may do nothing more than grate the plate away.

Despite these warnings about attempting reduction of physeal fractures that present late, only isolated case reports of problems with delayed reduction of physeal fractures leading to growth arrest are present in he literature..

In an animal study of Type I fractures, immediate reduction of physeal fractures of the proximal tibia of rats gave the least residual angular deformity and the least leg-length discrepancy of any group. Late reduction of physeal fractures did not cause growth arrest in this model; however, it also did not improve the angular alignment of the limb compared with those animals whose fracture was left unreduced.

Wattenbarger, J. Michael. Gruber, Helen E. Phieffer, Laura S. Physeal Fractures, Part I: Histologic Features of Bone, Cartilage, and Bar Formation in a Small Animal Model. Journal of Paediatric Orthopaedics. 22(6):703-709, November/December 2002.

 Egol, Kenneth A. Karunakar, Madhav. Phieffer, Laura/ Meyer, Ralph. Wattenbarger, J. Michael. Early Versus Late Reduction of a Physeal Fracture in an Animal Model. Journal of Paediatric Orthopaedics. 22(2):208-211, March/April 2002.

Last updated 11/09/2015