Fractures About the Knee

Preoperative Complications of Physeal Fractures About the Knee

Vascular compromise represents the most consequential complication of physeal fractures around the knee, occurring in roughly 2% of patients. The popliteal artery and geniculate branches are more intimately tethered to the posterior tibia at the level of the physis, and posterior displacement of either the epiphyseal fragment (flexion type injuries) or metaphyseal fragment (extension injuries) can lead to arterial injury, thrombosis, and/or compartment syndrome ( Fig. 12.1 ).

Vascular injury can also occur with or without direct injury to the associated vessels. One case series identified popliteal artery spasm on angiography in 4 out of 151 patients sustaining distal femoral physeal injuries. Although two patients recovered without long-term morbidity, two others developed ischemic contractures resulting in significant disability.

Wider displacement and higher-energy mechanisms are associated with a higher risk of injury. However, even nondisplaced proximal tibial physeal fractures should be evaluated for vascular injury, with a published incidence as high as 10%. The risk of compartment syndrome and/or vascular injury must be considered because the diagnosis can become complicated and missed in the presence of associated nerve palsies, distracting injuries, or altered mental status. In the setting of suspected or confirmed compartment syndrome, wide fasciotomies should be performed emergently ensuring release of the lateral, anterior, superficial posterior, and deep posterior compartments. Given the robust healing potential in children, compartment release should be performed even in cases of delayed presentation or diagnosis. If inadequate perfusion of the limb is present, a vascular surgery consultation should be obtained. These children should be admitted to the hospital to monitor for compartment syndrome and signs of vascular injury.

Isolated peroneal nerve palsies without vascular compromise can be seen in this patient population as well. In a single series, all cases had complete recovery of nerve function at final follow-up following fracture reduction and treatment.

Complications With Nonoperative Treatment

Minimally displaced Salter-Harris I or II fractures of the proximal tibia may be amenable to closed reduction and casting with the knee in slight flexion; however, they must be monitored closely for subsequent loss of reduction. In the distal femur, only stable, nondisplaced Salter-Harris I or II fractures may be treated nonoperatively, as even minimally displaced Salter-Harris I or II fractures have an unacceptably high risk of early loss of reduction without internal fixation. Graham et al. reported loss of reduction within 2 weeks in 5 of 10 patients with distal femoral physeal fractures treated with hip spica casting and/or application of traction. In that series, 9 of 10 patients proceeded to develop some form of angular deformity or limb length discrepancy within 6 months. Any patient treated nonoperatively should be followed closely in the acute period to inspect for loss of reduction and need to convert to surgical treatment should follow-up imaging demonstrate interval displacement of the fracture.

Intraoperative Complications of Physeal Fractures About the Knee

For displaced physeal fractures about the knee, treatment should be gentle closed or open reduction under general anesthesia. Multiple or excessively forceful attempts at closed reduction have been associated with higher rates of growth disturbances in other areas. When reduction is unable to be obtained, periosteal entrapment is commonly found to be the source. Persistent physeal widening seen after reduction of the distal femoral or proximal tibial physis should be considered an indication for open surgical reduction. The need for removal of interposed tissue has been suggested as a marker of a higher-energy injury with an increased likelihood of subsequent growth disturbance. Anatomic reduction can lessen the likelihood of but not eliminate the occurrence of a physeal disturbance.

Following closed or open reduction of the physis, internal fixation should be used to maintain reduction until bony healing. In cases where a Thurston-Holland or metaphyseal fragment is present, screws parallel to the physis should be utilized to avoid additional physeal injury, as fixation crossing the growth plate has demonstrated trends toward increased rates of long-term complications. In cases where it is necessary to cross the physis to achieve fixation, crossing smooth Kirschner wire fixation is preferred, with extracapsular entry points to reduce the risk of seeding the joint and potential septic arthritis.

Injuries to neurovascular structures have been described following violation of the posterior cortex with Kirschner wires. The surgeon must be careful with the depth of penetration of fixation in this area.

Postoperative Complications of Physeal Fractures About the Knee

The most common postoperative complication of a distal femoral or proximal tibial physeal fracture is postoperative growth disturbance, which can occur in as many as 60% of patients following distal femoral physeal arrest and up to 25% of patients with proximal tibial physeal injuries ( Fig. 12.2 ). Higher-energy injuries, more displacement, and higher Salter-Harris classification have been associated with a higher risk of clinically significant growth disturbance. There has been conflicting evidence with regards to whether transphyseal fixation with k-wires leads to higher rates of physeal arrest.

Avoidance of significant growth deformity in this population begins with close monitoring for physeal bar formation or growth arrest for at least 2 years or until skeletal maturity. Most patients experiencing a growth arrest will have radiologic changes within 1 year. More than 50% of patients with a growth arrest of the distal femur have been found to require operative intervention. Surgical treatment is needed in cases of growth disturbance with significant growth remaining. These procedures typically include physeal bar resection, epiphysiodesis, or osteotomy. Treatment is based on growth remaining, size of physeal disturbance, and magnitude of deformity.

Limitations in knee function should be expected following physeal injuries around the knee. One large systematic review comprising 15 studies of 466 patients with distal femoral physeal fractures reported a 12% incidence of limitation in range of motion, 5% incidence of ligamentous laxity, and 9% incidence of quadriceps atrophy at final follow-up. Following fracture healing the provider should focus on encouraging range-of-motion and quad-strengthening exercises, utilizing physical therapy when available. In cases of persistent instability or mechanical symptoms, it is important to consider concomitant intra-articular pathology, especially in cases of intra-articular fracture. Case series have described up to a 12% incidence of concomitant anterior cruciate ligament (ACL) rupture or meniscus tear in patients with Salter-Harris III epiphyseal fractures of the distal femur.

Rarer complications include pin site infection, which can occur in as many as 5% of patients. Septic arthritis can occur if a pin tract infection is associated with an intra-articular pin. While these fractures reliably heal, nonunion has been described in some patients. Malunions can occur if adequate reduction is not obtained and maintained. Insufficient remodeling may occur in the setting of older patients or those with physeal disturbances. Osteotomy is required in patients in whom a malunion has resulted in a significant deformity.