The accuracy of digital templating in cementless total hip arthroplasty in dysplastic hips

Background Total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH) is a complex procedure due to associated anatomical abnormalities. We studied the extent to which preoperative digital templating is reliable when performing cementless THA in patients with DDH. Methods We templated and compared the pre- and postoperative sizes of the acetabular and femoral components and the center of rotation (COR), and analysed the postoperative cup coverage, leg length discrepancy (LLD), and stem alignment in 50 patients (56 hips) with DDH treated with THA. Results The implant size exactly matched the template size in 42.9% of cases for the acetabular component and in 38.2% of cases for the femoral component, whereas the templated ±1 size was used in 80.4 and 81.8% of cases for the acetabular and femoral components, respectively. There were no statistically significant differences between templated and used component sizes among different DDH severity levels (acetabular cup: p = 0.30 under the Crowe classification and p = 0.94 under the Hartofilakidis classification; femoral stem: p = 0.98 and p = 0.74, respectively). There were no statistically significant differences between the planned and postoperative COR (p = 0.14 horizontally and p = 0.52 vertically). The median postoperative LLD was 7 (range 0–37) mm. Conclusion Digital preoperative templating is reliable in the planning of cementless THA in patients with DDH.

Relations between the Crowe classification and the 3D femoral head displacement in patients with developmental dysplasia of the hip

Background The purpose of this study was to investigate the relationship between the three dimensional (3D) femoral head displacement in patients with developmental dysplasia of the hip (DDH) and Crowe classification. Methods Retrospectively, CT scans of 60 DDH patients and 55 healthy demography-matched healthy control subjects were analyzed. Using the anterior pelvic plane a pelvic anatomic coordinate system was established. The center coordinates of the femoral heads of both the DDH patients and control subjects were quantified relative to the pelvic coordinate system and were mapped proportionally to a representative normal pelvis for comparison. Results In the anteroposterior (AP) direction, the center of the femoral head was significantly more anterior in the DDH patients (type I, II, and III, respectively45.0 ± 5.5, 42.9 ± 7.1, and 43.9 ± 4.6 mm) when compared to the controls (50.0 ± 5.2 mm) (p < 0.001 for all). In the medial-lateral (ML) direction, the center of the femoral head was significantly more lateral in the DDH patients (type I, II, and III =103.5 ± 8.6, 101.5 ± 6.6, 102.1 ± 11.2 mm) when compared to the controls (87.5 ± 5.1 mm) (p < 0.001 for all). In the superior-inferior (SI) direction, the center of the femoral head was significantly more proximal in the DDH patients (type I, II, and III =62.4 ± 7.3, 50.0 ± 6.3, and 43.2 ± 6.6 mm) when compared to the controls (66.0 ± 6.2 mm) (p < 0.001 for all). Conclusions The severity of DDH using the Crowe classification was related to the degree of the femoral head displacement in the SI direction, but not in the ML or AP directions. By assessing the 3D femoral head displacement in DDH patients, individualized component positioning might benefit surgical outcome.

Changes in acetabular component alignment due to screw fixation in patients with hip dysplasia

Introduction: Adequate initial stability of the acetabular cup is essential for total hip arthroplasty (THA). However, changes in the alignment of the acetabular component caused by screw fixation are concerning in patients with inadequate bone stock. This study aimed to investigate the effects of screw fixation on the alignment of the acetabular component in THA patients with hip dysplasia. Methods: We retrospectively examined 256 hips (range 28–87 years) that underwent THA using a navigation system. Patients were divided into 2 groups based on the presence or absence of changes in the alignment of the intraoperative acetabular cup, and univariate and multivariate analyses were performed to identify factors that were predictive of changes in acetabular component alignment after screw fixation in 2 dimensions: inclination and anteversion. Results: Screw fixation led to a mean change in inclination of 1.6° (range 0–10°) and a mean change in anteversion of 1.4° (range 0–14°). The Crowe classification, the presence of bone cysts, and the use of an inferior quadrant screw were identified as factors that correlated with acetabular cup alignment changes in inclination (odds ratios, 6.01, 5.94 and 0.03, respectively). Only the Crowe classification was identified as a factor that correlated with intraoperative alignment changes in anteversion (odds ratio, 2.08). Conclusions: Screw fixation altered the acetabular cup alignment. The inclination changes were related to the extent of the dysplasia, and the risk was reduced when the inferior quadrant screw was used. Surgeons should use caution during screw fixation in THAs performed on severely dysplastic hips.

Risk factors associated with complications following total hip arthroplasty using the two-incision technique

Background: The frequency of the complications following total hip arthroplasty (THA) using the two-incision technique is well documented. However, few reports have analyzed the preoperative patient–related factors associated with the complications. The purpose of this study was to estimate the incidence of early complications following primary two-incision THA and to define the risk factors associated with perioperative complications. Materials and Methods: The subjects of this retrospective study were 1218 consecutive patients who underwent primary two-incision THA. The incidence of hip dislocation, stem subsidence, intraoperative femoral fracture, and nontraumatic postoperative femoral fracture was evaluated. The association between complications and preoperative patient–related factors, including gender, obesity, Crowe classification, age, body mass index (BMI), and morphological parameters of the proximal femoral medullary cavity, were investigated. Results: The incidences of complications were dislocation (1.1%), stem subsidence (0.9%), intraoperative femoral fracture (1.2%), and postoperative femoral fracture (0.7%). Obesity (BMI > 30) influenced the occurrences of stem subsidence and postoperative femoral fractures ( p = 0.0001, p = 0.019). Crowe classification significantly correlated with intraoperative femoral fractures (Grade II: odds ratio (OR) 4.63, 95% confidence interval (CI), 1.32–15.6; Grade III and IV: OR 8.96, 95% CI, 2.2–34.94). Additionally, the outer diameter of the femur 10 cm below the lesser trochanter tended to be small in patients who developed a femoral fracture. Conclusions: The early complication rate was comparable to other methods used in uncemented THA. It is necessary for patients with risk factors revealed in this study to pay careful attention or consider other surgical approaches to avoid complications. Further studies considering femur morphology are required.