Effect of placement of acetabular prosthesis on hip joint function after THA

Impact of Offset and Leg Length on Functional Outcomes Post-Total Hip Arthroplasty: How Accurate Should Coronal Reconstruction Be?

BACKGROUND

Accurate hip reconstruction is associated with improved biomechanical behavior following total hip arthroplasty (THA). However, whether this is associated with improved patient-reported outcome measures (PROs) is unknown.

HYPOTHESIS/PURPOSE

This study aimed to: 1) Describe the ability to reconstruct coronal geometry during THA without advanced technology; 2) Assess whether restoration of global offset (GO) and leg length (LL) is associated with improved PROs; and 3) Investigate whether increased femoral offset (FO) to compensate for reduced acetabular offset (AO) influences PROs.

METHOD

This was a prospective, multi-center, consecutive cohort study of 500 patients treated with primary THA without robotics or navigation. The Oxford Hip Score (OHS) was obtained pre-operatively and at 1-year follow-up. Supine anteroposterior (AP) pelvic radiographs were analyzed to determine AO, FO, GO, and LL relative to the native contralateral side. Contour plots for ΔOHS based on ΔLL and ΔGO were created, and ΔOHS was calculated within and outside various ranges (± 2.5, ± 5, or ± 10 mm).

RESULTS

The mean GO and LL differences between sides were 0 ± 7 mm and 0 ± 8 mm, respectively. In the operated hip, mean FO increased to 3 ± 6 mm (range, -16 to 27), while AO decreased to 2 ± 4 mm (range, -17 to 10). The contour graph for ± 2.5 mm zones showed the best outcomes (ΔOHS > 25) with GO and LL centered on 0 ± 2.5 mm (P < 0.01). However, only 10% achieved such reconstruction. When GO and LL differences were within ± 10 mm, ΔOHS was superior when both AO and FO were within ± 5 mm (mean: 24 ± 10; range, -5 to 40) compared to when FO was above 5 mm to compensate for a reduction in AO (mean: 22 ± 11; range, -10 to 46; P = 0.040).

DISCUSSION

Mean GO and LL reconstruction were both 0 mm, with a precision of 7 and 8 mm, respectively, using manual techniques. The PROs were associated with biomechanical reconstruction, and the best clinical improvement can be expected when GO and LL differences are both within 2.5 mm. Maintenance of AO is important, as compensation by increasing FO is associated with inferior OHS.

The influence of prosthetic positioning and proximal femoral morphology on leg length discrepancy and early clinical outcomes of cementless total hip arthroplasty

BACKGROUND

Leg length discrepancy (LLD) is a common complication of total hip arthroplasty (THA). However, the relationship between femoral prosthesis filling, proximal femoral morphology, and acetabular prosthesis positioning with postoperative LLD and clinical outcomes is unclear. The aims of this study were to investigate the influence of canal flare index (CFI), canal fill ratio (CFR), center of rotation (COR), and femoral offset (FO) on (1) postoperative LLD; and (2) clinical outcomes in the two stem designs with different coating distribution.

METHODS

The study cohort included 161 patients who underwent primary cementless THA between January 2021 and March 2022 with either proximal coating or full coating stems. Multivariate logistic regression was used to assess the effect of CFI, CFR, COR, and FO on postoperative LLD, and linear regression to assess their effect on clinical outcomes.

RESULTS

No statistical difference was found in clinical outcomes or postoperative LLD between the two groups. High CFI (p = 0.014), low ΔVCOR (p = 0.012), and Gender (p = 0.028) were found independent risk factors for LLD one day postoperative. High CFI was also an independent risk factor for postoperative subjectively perceived LLD (p = 0.013). CFR at the level of 2 cm below the LT (p = 0.017) was an independent risk factor for Harris Hip Score.

CONCLUSIONS

Proximal femoral morphology and acetabular prosthesis positioning but not femoral prosthesis filling affected the LLD. High CFI was an independent risk factor for postoperative LLD and subjectively perceived LLD, and low ΔVCOR was also an independent risk factor for postoperative LLD. Women were susceptible to postoperative LLD.

Coordinate value of the femoral head center estimated using those of the tip of the greater trochanter and lesser trochanter

Several studies have reported estimating the femoral head center (FC) from reference points on the pelvis; however, none have reported estimates obtained from those on the femur. In this cross-sectional study, we investigated the estimated point of FC from the coordinate value of the tip of the greater trochanter (GT) and lesser trochanter (LT) using a formula with a three-dimensional measurement technique. We used data from 92 healthy Japanese subjects without any back or knee symptoms and no abnormalities in the hip, knee, or spine on plain radiographs. In our study, the difference in the anteroposterior direction was larger than that in the other directions. We speculate that the accuracy of defining the tip of the LT is difficult in the anteroposterior direction. Moreover, the correlation coefficients were larger for women. The reason for this was unclear because the variation in the proximal femur may be similar in women. We found that the average difference between the actual and calculated values was approximately 2 mm. We considered that the coordinate value of the FC from the tip of the GT could be estimated more accurately using the regression equation compared to previous methods based on pelvic reference points.

John Charnley Award: Deep Learning Prediction of Hip Joint Center on Standard Pelvis Radiographs

BACKGROUND

Accurate hip joint center (HJC) determination is critical for preoperative planning, intraoperative execution, clinical outcomes after total hip arthroplasty, and commonly used classification systems in primary and revision hip replacement. However, current methods of preoperative HJC estimation are prone to subjectivity and human error. The purpose of the study was to leverage deep learning (DL) to develop a rapid and objective HJC estimation tool on anteroposterior (AP) pelvis radiographs.

METHODS

Radiographs from 3,965 patients (7,930 hips) were included. A DL model workflow was created to detect bony landmarks and estimate HJC based on a pelvic height ratio method. The workflow was utilized to conduct a grid-search for optimal nonspecific, sex-specific, and patient-specific (using contralateral hip) pelvic height ratios on the training/validation cohort (6,344 hips). Algorithm performance was assessed on an independent testing cohort for HJC estimation comparison.

RESULTS

The algorithm estimated HJC for the testing cohort at a rate of 0.65 seconds/hip based on features in AP radiographs alone. The model predicted HJC within 5 mm of error for 80% of hips using nonspecific ratios, which increased to 83% with sex-specific and 91% with patient-specific pelvic height ratio models. Mean error decreased utilizing the patient-specific model (3.09 ± 1.69 mm, P < .001).

CONCLUSION

Using DL, we developed nonspecific, sex-specific, and patient-specific models capable of estimating native HJC on AP pelvis radiographs. This tool may provide clinical value when considering preoperative component position in patients planned to undergo THA and in reducing the subjective variability in HJC estimation.

LEVEL OF EVIDENCE

Diagnostic, level IV.

PFNA-II Internal Fixation Helps Hip Joint Recovery and Improves Quality of Life of Patients with Lateral-Wall Dangerous Type of Intertrochanteric Fracture

Objective

To analyze the effect of PFNA-II internal fixation on hip joint recovery and quality of life (QOL) in patients with lateral-wall dangerous type of intertrochanteric fracture.

Methods

One hundred and twelve patients with lateral-wall dangerous type of intertrochanteric fracture who underwent surgical treatment in our hospital from May 2017 to May 2019 were selected as the participants of the study. Based on the treatment method, all the enrolled patients were divided into two groups: proximal femoral nail antirotation (PFNA group; n = 59) who received closed reduction and minimally invasive PFNA internal fixation and dynamic hip screw group (DHS; n = 53) who received internal fixation. The clinical indicators, curative effect, hip function score, pain degree, postoperative QOL score, and complications were compared between the two groups.

Results

The operation time, intraoperative blood loss, postoperative drainage volume, and the incidence of postoperative complications in PFNA group were statistically lower than those in DHS group (P < 0.05). The curative effect in PFNA group was notably better than that in DHS group. There were no significant differences in scores of hip function, visual analogue scale (VAS), and QOL between the two groups before operation (P > 0.05). However, the hip function score and QOL score increased in both groups after surgery, and the increase was more significant in the PFNA group, while the VAS score decreased in both groups, and the decrease in PFNA group was more significant (P < 0.05).

Conclusion

PFNA internal fixation for the treatment of lateral-wall dangerous type of intertrochanteric fracture has the advantages of short operation time, less intraoperative blood loss, effective improvement of hip joint function, and fewer postoperative complications, which is worthy of clinical application.