In the past twenty years surgical advances have improved for the treatment of talar neck fractures, however there is still a risk of developing osteonecrosis of the talar body and/or posttraumatic arthritis.
The purpose of this study was to see if there is predictive value in the Hawkins Classifications of talar neck fractures for the long term outcomes in respect to osteonecrosis or arthritis. The researchers were also trying to improve on the classification system to better predict outcomes.
Traditionally the system used to describe talar neck fractures is the Hawkins Classification which is divided into the following categories: type I is a non displaced fracture; type II a displaced subtalar joint; and type III, a dislocated tibiotalar joint. The authors proposed further dividing the type II classification into IIA, subluxated subtalar joint and IIB, dislocated subtalar joint to better describe the amount of trauma and possible injury to the blood supply of the talus.
The study then retrospectively followed eighty patients with eighty-one fractures of the talus between 2001 and 2011. They were equally divided between men and women and the age range was from seventeen to seventy-two. A few patients did not return for their follow ups so the remaining sixty-three patients (sixty-four fractures) were followed for a mean of about one and a half years.
Osteonecrosis of the talar body occurred in twenty-five percent of the subjects and the mean time to appearance in radiographs was just under seven months. Forty-four percent of these cases had complete recovery of the vascular system in the talus without talar dome collapse. Within the classification system no patients with type I or type IIA developed osteonecrosis. Twenty-five percent of patients with type IIB classification developed osteonecrosis and forty-one percent of patients with type III classification developed osteonecrosis. These findings do suggest that a fracture with a subluxation or dislocation will increase the risk of developing osteonecrosis. This fits with their hypothesis that more trauma at the talar dome will have a the potential for increased disruption to the blood supply of the talus and subsequently increase likelihood of ostenecrosis. Interestingly no other factors such as age, medical comorbidites, or tobacco use were found to effect the development of osteonecrosis.
In addition to studying the risk of developing osteonecrosis this study also looked at the occurrence of posttraumatic arthritis. At the time of the most recent follow up, fifty-four percent of the patients had radiographic evidence of arthritis. This outcome was more likely with the type III injury, and in the presence of a talar body fracture eighty-three percent of cases developed arthritis. A fracture of the calcaneus or the tibial plafond also greatly increased the risk of developing arthritis to seventy-five percent.
The results of this study suggest that there is a higher likely hood of developing osteonecrosis if there is a type IIB or type III injury, however almost half of these patients had spontaneous revascularization of the talus (return to normal radiographs). This study also confirms that the most common complication following talar neck fracture is posttraumatic arthritis. The authors also suggest that this is the most common reason for secondary procedures such as removal of hardware, arthroplasty and arthrodesis. There is also the possibility that more of these cases will develop radiographic evidence of arthritis over time.