Study suggests basing SE4 ankle fracture treatment on size of medial clear space

SAN DIEGO — When clinicians wrestle with the question of whether to cast or perform surgery for stress positive supination-external rotation (SE) type 4 ankle fractures, their decision-making may be easier if they focus on the amount of medial clear space and location of the fracture, a study presented at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons revealed.

“We had stress positive SE4 fractures that had minimal medial clear space [MCS] widening that healed in good position with cast treatment. Greater displacements were treated with an operation. Try to think about where you are on this spectrum and offer your patients all reasonable options,” Paul Tornetta III, MD, of Boston, told meeting attendees.

He and his colleagues found syndesmotic incompetence rates of nearly 40% in their retrospective study.

Tornetta told Orthopedics Today, “This study demonstrated that a protocol of shared decision-making with patients led to anatomic union in all. Also, it is the first study to demonstrate there is a similar incidence of syndesmotic injury in stress [positive] SE pattern ankle fractures as in those that present with talar subluxation or dislocation.”

Retrospective review

Paul Tornetta III

To determine which treatment led to anatomic union in patients with isolated SE (Weber B) fibular fractures that demonstrated talar shift with stress examination, Tornetta and colleagues reviewed 114 fractures in adults aged 19 to 76 years. Fifty-four fractures were casted and 60 fractures were treated with open reduction internal fixation (ORIF), as all presented with an intact mortise, the groups had identical MCS measurements upon presentation.

Tornetta and his partner sought to identify the radiographic characteristics that led to treatment in a cast or ORIF in a shared decision-making scheme. To determine whether fracture characteristics affected their decision-making, they reviewed the MCS in all cases on radiographs at presentation, under stress and following reduction.

Based on the results, stress radiograph MCS measurements differed significantly between the two groups.

Investigators also evaluated fibular displacement at presentation and after reduction in the casted group.

No nonunions

Patients selected the treatment they would receive following an in-depth discussion of the pros and cons of both of them with Tornetta or his partner.

“In the series, all the fractures healed,” with accurate reductions, no nonunions in the ORIF group and no fractures healing in a subluxated position, Tornetta said.

Among patients they operated on, 45% had intraoperative syndesmotic instability, which investigators defined as MCS widening on radiographs and talar subluxation following fibular fixation.

“Of big interest to me was 45% of the patients who went to the operating room had syndesmotic instability,” Tornetta said.

Ultimately, investigators defined instability as greater than 4 mm MCS and more than 1 mm larger than the superior joint space, which Tornetta said was conservative while not putting any patients at added risk of malunions from missed syndesmotic injury. – by Susan M. Rapp

Reference:

• Tornetta P, Axelrad TW, Creevy WR. Treatment of the stress positive SE4 ankle fracture: Incidence of syndesmotic injury decision making. Paper #46. Presented at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons. Feb. 15-19. San Diego.

• Paul Tornetta III, MD, can be reached at 850 Harrison Ave., 3rd Floor, Boston, MA 02118; 617-414-5212; e-mail: ptornetta@gmail.com.
• Disclosure: Tornetta is a consultant for and receives royalties from Smith & Nephew.

Dr. Tornetta and his colleagues present a detailed analysis of their experience treating distal fibular fractures associated with medial clear space widening on either static or external rotation stress views. The authors highlight the particularly important finding of a 45% incidence of residual syndesmotic instability in the operative group after fracture fixation. This reinforces the importance of intra-operative evaluation of the syndesmosis in patients with SER-4 or Weber B injuries as fixation of the syndesmosis will frequently be required.

— Nelson F. SooHoo, MD
Associate Professor
UCLA Department of Orthopaedic Surgery
Los Angeles
Disclosure: He has no relevant financial disclosures.