The etiology of sacroiliac joint (SIJ) degeneration has not been fully elucidated, and there has been almost no report on the relevance between SIJ degeneration and hip osteoarthritis secondary to developmental dysplasia of the hip (DDH). We investigated factors associated with SIJ degeneration, specifically its laterality in patients with end-stage hip osteoarthritis secondary to unilateral DDH.
We included 152 patients with end-stage unilateral hip osteoarthritis secondary to DDH who underwent primary THA between January 2008 and November 2015. SIJ degeneration was classified (type 0, no degenerative change, to type 3, ankyloses) using preoperative axial computed tomography. SIJ degeneration of the DDH (shorter leg) and contralateral (longer leg) sides was compared; differences in patient demographics and radiological parameters between SIJ degeneration of type 0 or 1 versus type 2 or 3 for the shorter and longer leg sides were analyzed.
SIJ on the longer leg side showed more degenerative changes (p < 0.001). Substantial SIJ degeneration or ankylosis (type 2 or 3) was observed on 62.5% of longer leg sides and 33.6% of shorter leg sides. Factors significantly associated with SIJ degeneration severity were percent hip subluxation and leg length discrepancy for the longer leg side and body weight and body mass index (BMI) for the shorter leg side. Patients with worse degeneration on the shorter leg side (9.9%) had significantly larger BMI and longer sagittal vertical axis, whereas patients with worse degeneration on the longer leg side (46.7%) had significantly longer leg length discrepancy.
Severe SIJ degeneration was common in patients with end-stage hip osteoarthritis secondary to unilateral DDH. Patients with worse SIJ degeneration on the longer leg side had more hip subluxation, whereas patients with worse SIJ degeneration on the shorter leg (DDH) side tended to have sagittal spinal imbalance and greater body weight with larger BMI.