A Specific Anteversion of Cup and Combined Anteversion for Total Hip Arthroplasty Using Lateral Approach

Abstract

Objective To determine the implant orientation, especially the combined anteversion measurements in total hip arthroplasty (THA) using lateral approach, and to compare with implant orientation using posterior‐lateral (P‐L) approach. The secondary goal was to identify the factors associated with implant orientation. Methods Five hundred and one patients (545 hips) who underwent primary THA with the modified Hardinge approach between January 2016 and November 2019 by one senior surgeon in our department in a retrospective study were followed up. A survey to inquire about the history of dislocation of the hip after THA was designed and responses were gathered by telephone, WeChat software, and outpatient follow‐up. The mean age of the patients was 61.97 ± 11.72 years, and there were 254 males and 247 females. The average follow‐up time was 25.2 ± 13.7 months (range, 3.2–49.7 months). Among the patients who were followed up, 97 patients (104 hips) underwent computed tomography (CT) scans from L4 to the tuberosity of the tibia. The implant orientation, including the anteversion and inclination of the cup, anteversion of the stem, combined anteversion, and pelvic tilt were measured based on CT scans of these patients. The results were compared with the implant orientation reported in previous reports measured by CT. Factors that may be associated with implant orientation were investigated, including the patient's age, sex, body mass index (BMI), and diagnosis; size of the cup; diameter of the femoral head component; and pelvic tilt. Data and statistical analyses were performed using SPSS 20.0. Results No cases of dislocation were found in the 501 patients (545 hips) who underwent primary THA during this period. The mean inclination and anteversion of the cups were 38.83° ± 5.04° (24.5°–53.1°) and 9.26° ± 11.19° (−15°–48°), respectively. The mean anteversion of the stem was 13.83° ± 10.7° (−10.2°–42.3°). The combined anteversion was 23.1° ± 13.4° (−7.4°–54.6°). Compared with the reported combined anteversion and anteversion of the cup, the mean anteversion of the cup and combined anteversion using the lateral approach were much lower than the reported values in the literature using the P‐L approach. Pelvic tilt was found to be the only independent factor for cup anteversion. Factors including age, sex, BMI, diagnosis, cup size, and diameter of the femoral head component were not associated with implant orientation. Conclusion THA using the lateral approach yields smaller cup anteversion and combined anteversion values than using the P‐L approach. Pelvic tilt is the only predictor for cup anteversion.

A Comparison of Radiographic Outcomes after Total Hip Arthroplasty between the Direct Lateral Approach and Posterior Lateral Approach with EOS 2D/3D X‐Ray Imaging System

“…Using PP as a reference plane, 51.7% of THA patients on DLA and 39.3% of THA patients on PLA were inside the Lewinnek safe zone. 7 This DLA result is similar to the 52.9% distribution rate obtained by Li et al 19 but lower than that (57%) measured by Timothy et al 21 using CT. This difference may be due to the biological reasons for the different positions in CT and EOS examinations.…”

“…We also found that gender and femoral head diameter were factors influencing acetabular cup anteversion (Table 3). Hartel's study also showed that gender is a small but significant factor in acetabular cup anteversion in THA, 38 differing from previous studies 19 . This may be caused by chance, as there was no difference in patient gender or femoral head diameter.…”

“…Hartel's study also showed that gender is a small but significant factor in acetabular cup anteversion in THA, 38 differing from previous studies. 19 This may be caused by chance, as there was no difference in patient gender or femoral head diameter. To place the acetabular cup in the proper position, a relatively fixed plane for preoperative planning is crucial.…”

“…Fujishiro et al 24 measured the THA with PLA by CT and found that the cup anteversion, cup inclination, and combined anteversion were 24.7° ± 11.3°, 41.0° ± 6.2°, and 65.0° ± 15.7°, respectively. Li et al 19 measured the THA with DLA using CT and found that the cup anteversion, femoral stem anteversion, cup inclination, and combined anteversion were 9.26° ± 11.19°, 13.38° ± 10.7°, 38.83° ± 5.04°, and 23.1° ± 13.4°, respectively. Using EOS, we found a significantly smaller femoral stem anteversion (17.71° ± 15.15°) and combined anteversion (42.37° ± 18.85°) with PLA, and greater cup anteversion (21.33° ± 17.31°) and cup inclination (41.60° ± 6.66°) with DLA than their results.…”

“…In the DLA group, the operation was performed using a modified Hardinge approach. The gluteus medius and minimus muscles were bluntly separated in the anterior middle 1/3 of the gluteus medius 19 . The hip was flexed and externally rotated to create anterior dislocation of the hip joint.…”