RESUMO
Objective:To observe the morphological characteristics of L 4, 5 facet joints in patients with degenerative lumbar spondylolisthesis (DLS) of different spinopelvic types based on Roussouly classification. Methods:We retrospectively analyzed 142 patients with DLS who visited the department of orthopaedics in the Affiliated Hospital of Southwest Medical University from August 2018 to May 2022. There were 33 males aged 65.0±10.7 years and 109 females aged 61.8±9.6 years. The following morphological parameters of the L 4, 5 facet joint were measured on the CT images: facet joint angle (FJA), pedicle facet angle (PFA), facet joint tropism (FT) and facet joint osteoarthritis (OA) degree; the sacral slope (SS), lumbar lordosis (LL) and percentage of L 4 slip distance (SDP) were measured on preoperative standing neutral lumbar radiographs. According to the Roussouly classification, the patients were divided into four groups (type I, type II, type III, and type IV). The differences of morphological parameters of the facet joints and SDP were compared among the four groups, and the correlation between the FJA and PFA was analyzed. Results:There were 142 patients, including 28 type I, 50 type II, 43 type III, and 21 type IV according to the Roussouly classification. The SDPs of type I, type II, type III, and type IV were 19.1%±3.4%, 18.6%±3.9%, 21.7%±3.9%, 25.0%±2.4%, respectively. Except for types I and II, there were statistically significant differences in pairwise comparison among all other types ( P<0.05). The FJAs in type I and type II (31.4°±6.3°, 35.2°±6.8°) were larger than those in type III (28.4°±5.6°) and type IV (23.4°±4.5°), and the FJA in type III was larger than that in type IV. Conversely, the FJA in type I was smaller than that in type II. These differences were statistically significant ( P<0.05). The PFAs in type I and type II (113.9°±4.9°, 111.3°±5.6°) were smaller than those in type III (116.3°±4.4°) and type IV (121.8°±3.5°), and the PFA in type III was smaller than that in type IV, while, the PFA in type I was larger than that in type II. These differences were statistically significant ( P<0.05). The degree of OA in both type I and type II was lower than that in type III and type IV, with statistically significant differences ( P<0.05). However, there were no statistically significant differences in the degree of OA between type I and type II and between type III and type IV ( P> 0.05). Additionally, there were no statistically significant differences ( F=0.40, P=0.752) in the FT values among type I, type II, type III, and type IV (5.8°±2.3°, 5.6°±2.4°, 6.1°±1.8°, 5.9°±1.9°). Pearson correlation analysis showed that FJA was negatively correlated with PFA ( r=-0.68, P<0.001). Conclusion:In the slip segment of DLS, the facet joint morphology was part of the joint configuration in different spinopelvic types, not just the result of joint remodeling after DLS. Morphological characteristics of the facet joints and DLS interacted with each other.