Radiographic evaluation of reactive osteitis in traumatic injury of sacroiliac joints

After traumatic Sacroiliac (SI) joint injury, follow up radiographic imaging can demonstrate subchondral bone resorption resembling inflammatory sacroiliitis. No studies have described the incidence of marginal SI post-traumatic osteitis, the probable temporal relationship to the initial traumatic injury, or the possible effect of unilateral hardware fixation on the contralateral SI joint.

A Level 1 trauma center imaging database was queried to identify patients with pelvic bony trauma between 2005 and 2017 with CT baseline preserved SI cortication and unilateral/bilateral traumatic SI diastasis. Serial radiographs were retrospectively evaluated by 2 musculoskeletal-trained radiologists at initial, 6 weeks, 3 months and 6 months following trauma, with documentation of diastasis, subchondral resorption, and operative fixation.

206 SI joints in 106 total patients met inclusion criteria. There was a statistically significant association between injury and presence of resorption at 6 weeks post-trauma for the right SI joint only. There was no other statistically significant relationship between injury and presence of resorption at any other post-trauma evaluation. There was no statistical relationship between resorption and surgical fixation. There was a statistically significant increased incidence of resorption in the post-traumatic population when compared to an atraumatic population undergoing CT pelvis study for non-SI related indications as well as compared to the incidence of inflammatory sacroiliitis in a general population.

This study confirms an incidence of sub-acute subchondral bone resorption following traumatic joint injury above that expected for a general, non-traumatic population. Accurate interpretation of this traumatic finding minimizes inappropriate consultation and intervention for inflammatory sacroiliitis.