The effect of degenerative scoliosis and spinopelvic parameters on dislocation of hip hemiarthroplasty

Abstract

Background: Degeneration of the spine may affect pelvic parameters and hip mobility. This study aimed to evaluate the effects of degenerative scoliosis and spinopelvic parameters on hip hemiarthroplasty dislocations.

Methods: A retrospective analysis was conducted on patients who underwent hemiarthroplasty for intracapsular hip fracture over a twenty-year period. Demographic data, dislocation incidence, degenerative scoliosis (DS) status, type of hemiarthroplasty, surgical intervention to the hip, femoral head size, cement use, American Society of Anesthesiologists (ASA) score, body mass index (BMI), and in-hospital mortality were evaluated. The Cobb angle (CA), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), and thoracic kyphosis (TK) angles were measured and analyzed.

Results: A total of 284 patients were evaluated, with a mean age of 79.07 (±8.21) years. The frequency of hemiarthroplasty dislocation was 13% (n=37). Degenerative scoliosis was detected in 25.4% of the cases and was significantly more common in patients with degenerative scoliosis (p=0.001). Advanced age, higher BMI, higher ASA score, unipolar and cementless hemiarthroplasty, smaller femoral head size, and the posterior approach significantly increased dislocation frequency (p=0.004, p=0.001, p=0.03, p=0.001, p=0.001, and p=0.026, respectively). The mean PI, SS, PT, LL, and TK angles were significantly reduced in patients with dislocation and degenerative scoliosis (dislocation: p=0.001, p=0.001, p=0.001, p=0.003, p=0.048; degenerative scoliosis: p=0.001, p=0.001, p=0.001, p=0.001, p=0.001; respectively).

Conclusion: The presence of degenerative scoliosis and low pelvic incidence, sacral slope, pelvic tilt, thoracic kyphosis, and lumbar lordosis angles may increase the frequency of hemiarthroplasty dislocations. The posterior approach and small femoral head size may also elevate the risk of posterior dislocation.

Figure 1

Frontal whole spine radiograph. The Cobb angle (yellow lines) was measured at 4°.

Figure 2

Standing lateral whole spine radiograph. The pelvic incidence is formed by a line drawn from the midpoint of the femoral heads (red dot) to the midpoint of the superior endplate of S1 and a line drawn perpendicular to a line parallel to the superior endplate of S1 (blue line). The sacral slope is the angle created by a line drawn along the superior endplate of S1 (yellow line) and a line parallel to the floor (green line). Sacral slope plus pelvic tilt equals pelvic incidence. (In this patient: sacral slope 28°, pelvic tilt 15°, pelvic incidence 43°). The pelvic tilt is the angle formed between a line drawn from the midpoint of the femoral heads to the center of the superior endplate of the sacrum and a vertical line through the midpoint of the femoral heads (orange lines). (In this patient: pelvic incidence 43°, pelvic tilt 15°, sacral slope 28°). The lumbar lordosis is defined as the Cobb angle created by the intersection of lines drawn across the superior endplate of T12 and S1 (yellow lines). In this patient, lumbar lordosis is 48°. The thoracic kyphosis angle is created by drawing a line across the superior endplate of T4 and the inferior endplate of T12 (red lines). In this patient, thoracic kyphosis is 44°.