Degenerative spondylolisthesis: A significant risk factor for adverse spinopelvic mobility and impingement in patients undergoing total hip arthroplasty.

Background: Analysing the hip‒spine relationship allows the identification of risk factors for adverse spinopelvic mobility or impingement, including degenerative lumbar pathologies. Spondylolisthesis prevalence appears to increase with age, but the association of spondylolisthesis with pelvic mobility has not been studied.

Hypothesis: Our hypothesis was that the presence of a degenerative spondylolisthesis on the preoperative lateral spine radiograph analysis before total hip arthroplasty was associated with a higher rate of adverse spinopelvic mobility, and that this exposed patients to a greater risk of prosthetic impingement when using a systematic implant positioning strategy.

Methods: The clinical data of 605 consecutive patients who underwent total hip arthroplasty were retrospectively analysed. We evaluated the presence of degenerative spondylolisthesis on lateral lumbar spine radiographs, its potential associations with adverse spinopelvic mobility (Δspinopelvic tilt (SPT) ≥20 °), and the risk factors associated with a ΔSPT ≥20 ° in the overall population. Secondarily, we analysed the in-silico risk of impingement with the standard orientation of the cup at 40/20 ° and the safe zone without impingement.

Results: The ΔSPT ≥20 ° rates were 40% and 15% in patients with and without spondylolisthesis, respectively (odds ratio (OR) = 3.76; confidence interval (CI) [2.13; 6.64]; p < 0.001). In the multivariable analysis, the following independent predictors of ΔSPT ≥20 ° were identified: SPT ≤-15 ° (OR = 3.9, [1.58; 9.65], p = 0.003), PI-LL ≥20 ° (OR = 3.14, [1.34; 7,34], p = 0.008), low PI/low lordosis and distal apex of lumbar lordosis (OR = 2.08, [1.24; 3.48], p = 0.005) and spondylolisthesis OR = 4.16, [2.31; 7.51], p < 0.001). The impingement rates with an orientation of the cup at 40 ° and 20 ° were 49,3% and 24.35%, respectively, in patients with and without spondylolisthesis (OR = 3.2; [1.91; 5.37]; p < 0.001). The median anteversion safe zone was 17.0 (interquartile range (IQR) = 25.0) in patients with spondylolisthesis and 27.0 (IQR = 17.0) in patients without spondylolisthesis (median Δ = -10.0; p < 0.001). A total of 23.88% patients with a spondylolisthesis had no anteversion safe zone, compared with 9.12% of patients without spondylolisthesis (OR = 3.12; [1.66; 5.89]; p = 0.001).

Conclusion: Degenerative spondylolisthesis, a common degenerative condition, is a risk factor for adverse spinopelvic mobility and prosthetic impingement in patients undergoing total hip arthroplasty. The identification of spondylolisthesis on lateral spine radiographs should prompt adjustments in implant orientation.

Level of evidence: IV; retrospective study.