Elsevier

The Journal of Hand Surgery

Volume 34, Issue 6, July–August 2009, Pages 1037-1043
The Journal of Hand Surgery

Scientific article
Using Computed Tomography to Assist With Diagnosis of Avascular Necrosis Complicating Chronic Scaphoid Nonunion

https://doi.org/10.1016/j.jhsa.2009.02.016Get rights and content

Purpose

The primary aim of our study was to investigate use of long axis computed tomography (CT) in predicting avascular necrosis of the proximal pole of the scaphoid and subsequent fracture nonunion after internal fixation. In addition, we describe a new technique of measuring the position of a scaphoid fracture and provide data on its reproducibility.

Methods

Thirty-one patients operated on by the senior author for delayed union or nonunion of scaphoid fracture were included. Preoperative CT scans were independently assessed for increased radiodensity of the proximal pole, converging trabeculae, degree of deformity, comminution, and fracture position. Intraoperative biopsies of the proximal pole were obtained and histologically assessed for evidence of avascular necrosis. The radiologic variables were statistically compared with the histologic findings. The presence of avascular necrosis was also compared with postoperative union status, identified on longitudinal CT scans.

Results

Preoperative CT features that statistically correlated with histologic evidence of avascular necrosis were increased radiodensity of the proximal pole and the absence of any converging trabeculae between the fracture fragments. The radiologic changes of avascular necrosis and the histologic confirmation of avascular necrosis were associated with persistent nonunion.

Conclusions

Preoperative longitudinal CT of scaphoid nonunion is of great value in identifying avascular necrosis and predicting subsequent fracture union. If avascular necrosis is suspected based on preoperative CT, management options include vascularized bone grafts and bone morphogenic protein for younger patients and limited wrist arthrodesis for older patients.

Type of study/level of evidence

Diagnostic II.

Section snippets

Materials and Methods

Ethics approval for this study was obtained from the relevant research ethics committees.

From 1994 to 2007, 31 consecutive patients with established scaphoid fracture nonunion or delayed union were identified and surgically treated by the senior author (G.I.B.) and prospectively followed up. The diagnosis of delayed union or nonunion was established using a longitudinal CT scan. All 31 patients also had preoperative plain wrist radiographs. Patients with wrist radiographs displaying marked

Results

Of the 31 patients in the series, 28 were male and 3 were female. The mean age at time of injury was 29 years (range, 15–61 years). In the series, there were 7 proximal-third fractures, 23 middle-third fractures, and only 1 distal-third fracture.

The median time from injury to CT scan was 6 months (range, 3 months to 25 years). The median time from injury to surgery was 6 months (range, 3 months to 25 years).

Discussion

Radiologic diagnosis of avascular necrosis is typically made with MRI, and a number of studies have shown that MRI has a high correlation with intraoperative findings.8, 9 However, MRI has limited accessibility, is troublesome for patients who suffer from claustrophobia, and is expensive. CT is commonly used for assessing fracture anatomy prior to surgical intervention and has the added advantages of availability, low cost, and patient tolerance while giving more detailed imaging of bony

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    No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.

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