A low-volume surgeon is an independent risk factor for leg length discrepancy after primary total hip arthroplasty: a case-control study

Leg length discrepancy risk differs between fit-and-fill and taper wedge stems across Dorr types

INTRODUCTION

The comparison between the cementless taper wedge stem and fit-and-fill stem in total hip arthroplasty (THA) for various proximal femoral morphological types has not been thoroughly assessed. This study aimed to compare the risk of leg length discrepancy (LLD) ≥ 10 mm between these two stem types in Dorr type A, B, and C femurs.

MATERIALS AND METHODS

From April 2015 through April 2021, we analyzed 1178 unilateral primary cementless THA procedures. We categorized all procedures into three groups: Dorr type A (N = 220, 18.7%), B (N = 875, 74.3%), and C (N = 83, 7.0%). Within each Dorr type, we compared the incidence and risk of postoperative LLD ≥ 10 mm between the two stem types. The factors considered in the multivariate regression analyses included stem type, age, sex, body mass index, diagnosis, canal flare index, femoral cortical index and stem alignment.

RESULTS

The taper wedge stem group had a higher overall incidence of LLD ≥ 10 mm (12.8% vs. 7.4%, P = 0.012) and in Dorr type A femurs (22.2% vs. 7.6%, P = 0.014), compared with the fit-and-fill stem group. In multivariate analysis, the taper wedge stem exhibited an increased risk of LLD ≥ 10 mm only in Dorr type A femurs (aOR: 3.449, 95% CI: 1.325-8.794). The incidence and risk of LLD ≥ 10 mm were not different between the two stems in Dorr type B and C femurs.

CONCLUSIONS

The taper wedge stem demonstrated an elevated risk of LLD ≥ 10 mm in Dorr type A femurs compared with the fit-and-fill stem, necessitating meticulous preoperative templating and intraoperative femoral canal preparation.

Radiographic study of direct anterior approach hip arthroplasty: a 10-15 year follow-up of Chinese patients

BACKGROUND

Controversy remains over whether different surgical approaches exert an impact on the component positioning in total hip arthroplasty. We conducted a retrospective study to reveal the long-term position of prostheses in the first group of patients in China who underwent direct anterior hip arthroplasty.

METHODS

Collected were data from 350 patients who underwent direct anterior hip arthroplasty between 2008 and 2013, including demographic information, imaging data, Harris hip scores, and surgical complications. Variables, measured radiographically or by CT, included hip offset, leg length discrepancy, component position, and stability within one week after surgery and at the last follow-up. The data were subjected to statistical analysis by using paired t-tests and Pearson chi-square tests.

RESULTS

Data were harvested by follow-up and self-reported questionnaires. The postoperative follow-up lasted for 13.1 years on average (minimum, 10 years; maximum, 15 years), and the overall survival rate of hip prostheses was 96.3%. The mean Harris score at the final follow-up was 91.8 points. After excluding patients with significant preoperative hip deformities, the incidence of postoperative limb inequality (> 5 mm) was 4.9% at the last follow-up, and the incidence of hip offset discrepancy (> 5 mm) was 14.6%. The overall proportion of the acetabular components located in the Lewinnek safe zone was 77.7%, whereas the proportion of femoral prostheses in the safe zone (< 3° inclination) was 94.0%. Based on the revised data and the last follow-up imaging, the total proportion of acetabular and femoral prostheses with a radiolucence of > 2 mm was 5.1%.

CONCLUSION

Direct anterior approach hip arthroplasty could achieve excellent component positioning and long-term prosthesis survival in patients without severe hip deformities.

Clinical application of artificial intelligence-assisted three-dimensional planning in direct anterior approach hip arthroplasty

PURPOSE

The objective of this study was to investigate the efficacy of an artificial intelligence-assisted 3D planning system (AIHIP) in total hip arthroplasty by direct anterior approach and assess the reliability of the AIHIP preoperative program in terms of both interobserver and intraobserver agreement.

METHODS

A retrospective analysis was conducted on patients who underwent unilateral primary THA via direct anterior approach from June 2019 to March 2022. Participants were randomly assigned to receive either the AIHIP system (n = 220) or the 2D template (control group) (n = 220) for preoperative planning. The primary outcome aimed to evaluate the correspondence between the prosthesis selected intro-operation and the one planned preoperatively, as well as to calculate the intraclass correlation coefficient (ICC). Secondary outcomes included operation time, intraoperative blood loss, fluoroscopy times, Harris hip score (HHS), lower limb length difference (LLD), femoral offset (FO), and bilateral femoral offset difference.

RESULTS

No significant differences were observed in gender, age, body mass index (BMI), aetiology, and American Society of Anesthesiologists (ASA) score between the two groups. Both planning methods exhibited good intraobserver agreement for component planning (ICC: 0.941-0.976). Interobserver agreement for component planning was comparable between the two methods (ICC: 0.882-0.929). In the AIHIP group, the accuracy of acetabular cup and femoral stem prosthetics planning significantly improved, with accuracies within the size range of ± 0 and ± 1 being 76.8% and 90.5% and 79.5% and 95.5%, respectively. All differences between two groups were statistically significant (p < 0.05). Patients receiving AIHIP preoperative planning experienced shorter operation times, reduced intraoperative blood loss, fewer fluoroscopy times, and lower leg length discrepancy (LLD) (p < 0.05). Moreover, they demonstrated a higher Harris hip score (HHS) at three days post-surgery (p < 0.05). However, no significant differences were found in femoral offset (FO), difference of bilateral femoral offsets, and HHS at 1 month after the operation.

CONCLUSION

Utilizing AIHIP for preoperative planning of direct anterior approach THA can significantly enhance the accuracy of prosthetic sizing with good reliability, decrease operation time, reduce intraoperative blood loss, and more effectively restore the length of both lower limbs. This approach has greater clinical application value.

Higher Annual Total Hip Arthroplasty Volume Decreases the Risk of Intraoperative Periprosthetic Femur Fractures

BACKGROUND

Periprosthetic femur fracture (PFF) is a complication of total hip arthroplasty (THA). These occur intraoperatively or postoperatively, and documented risk factors of PFFs include women, age greater than 65 years, cementless stems, and inflammatory arthropathies. The aim of this retrospective cohort study was to assess the relationship of years of surgical experience and surgeon annual THA volume on intraoperative and postoperative PFFs.

METHODS

Data were collected from a database query, and PFFs were identified as either intraoperative or postoperative. Intraoperative and postoperative PFFs were both compared to a control group of non-PFF patients. Years of surgical experience at the time of surgery and annual THA volume for the primary surgeon were calculated for all cases. Logistic regression analyses were used to calculate odds ratios for each of the surgeon variables when adjusted for patient demographics.

RESULTS

Thirty-seven intraoperative and 108 postoperative PFFs were identified and compared to 7,629 controls. From regression analyses, high-volume surgeons (≥50 THA/year) had lower odds of intraoperative PFF (adjusted odds ratio (aOR) = 0.40, P = .020) but not postoperative PFF (aOR = 1.02, P = .921). Surgeon experience (≥15 years since board certification at the time of surgery), was not significantly related to either PFF outcomes. For patient factors, age ≥65 years (aOR = 2.30, P < .001) and women (aOR = 2.69, P < .001) were both significant predictors of postoperative PFFs only.

CONCLUSION

Surgeons who performed 50 or more THAs per year had significantly fewer intraoperative PFFs than surgeons who did less than 50 THAs per year. Surgeon experience was not significantly related to PFFs.

Minimal pre-operative leg length discrepancy as a risk factor of post-operative leg length discrepancy after total hip arthroplasty: a retrospective study of patients with non-traumatic osteonecrosis of the femoral head

BACKGROUND

Leg length discrepancy (LLD) is one of the troublesome complications of total hip arthroplasty (THA). Previously, several risk factors have been suggested, but they were subjected to their inherent limitations. By controlling confounding variables, we hypothesized that known risk factors be re-evaluated and novel ones be discovered. This study aimed to analyze the independent risk factors for LLD after primary THA in patients with non-traumatic osteonecrosis of the femoral head (ONFH).

METHODS

We retrospectively reviewed patients with non-traumatic ONFH who underwent unilateral THA between 2014 and 2021. All patients were operated by one senior surgeon using a single implant. Demographic data, surgical parameters, and radiological findings (pre-operative LLD, Dorr classification, and femoral neck resection) were analyzed to identify the risk factors of ≥ 5 mm post-operative LLD based on radiological measurement and to calculate odds ratios by logistic regression analysis. Post hoc power analysis demonstrated that the number of analyzed patients was sufficient with 80% power.

RESULTS

One hundred and eighty-six patients were analyzed, including 96 females, with a mean age of 58.8 years at the time of initial THA. The average post-operative LLD was 1.2 ± 2.9 mm in the control group and 9.7 ± 3.2 mm in the LLD group, respectively. The LLD group tended to have minimal pre-operative LLD than the control group (-3.2 ± 5.1 mm vs. -7.9 ± 5.8 mm p = 2.38 × 10- 8). No significant difference was found between the groups in age, gender, body mass index, femoral cortical index, and implant size.

CONCLUSION

Mild pre-operative LLD is associated with an increased risk of post-operative LLD after primary THA in patients with ONFH. Thus, surgeons should recognize pre-operative LLD to achieve an optimal outcome and must inform patients about the risk of developing LLD.

The effectiveness and influencing factors of the "Y" line technique in reducing the leg length discrepancy after total hip arthroplasty

Objective

To introduce a surgical technique (the "Y" line technique) that will control leg length discrepancy (LLD) after total hip arthroplasty and to observe its effectiveness and influencing factors.

Methods

According to the inclusion and exclusion criteria, a total of 350 patients were selected in this study; 134 patients in whom used the "Y" line technique was used to control lower limb length were included in Group A and 166 patients treated with freehand methods to control lower limb length were included in Group B. A total of 50 patients in whom the standard anteroposterior x-ray of bilateral hips was taken preoperatively and in whom the "Y" line technique was used during the operation were included in Group C.

Results

The postoperative LLD of Group A was 4.74 mm (3.93), that of Group B was 5.85 mm (4.60), and that of Group C was 2 mm (1.00)-the difference was statistically significant (p < 0.001). There were significant statistical differences when comparisons were made between any two groups (p < 0.01). The distribution of postoperative LLD in Group A was better than that in Group B, and this factor was better in Group C than in Group A-the difference was statistically significant (p < 0.001). Severe unequal length rates of the lower extremities (LLD > 10 mm) were 5.97% (8/134) in Group A, 14.3% (24/166) in Group B, and 0% (0/50) in Group C-the difference was statistically significant (p < 0.001). There were significant differences between Group A and Group B and between Group B and Group C (p < 0.05), but there was no significant difference between Group A and Group C (p = 0.078).

Conclusion

The "Y" line technique, which does not increase the operating time and patient cost, can effectively reduce postoperative LLD. Insufficient internal rotation of the healthy lower extremity and the low projection position in the preoperative anteroposterior x-ray of the bilateral hips were important factors affecting the accuracy of the "Y" line technique.

The morphology of the proximal femur in cementless short-stem total hip arthroplasty: No negative effect on offset reconstruction, leg length difference and implant positioning

Background

Correct reconstruction of hip offset (HO) and leg length are important for clinical–functional outcome and patient satisfaction in total hip arthroplasty (THA). The morphology of the proximal femur can pose a risk for increased leg length difference (LLD) in cementless straight-stem THA. We therefore wanted to evaluate, if this is also applicable in THA with a cementless meta-diaphyseal short stem.

Methods

In a retrospective study, 106 patients (index surgery 2014–2019) with unilateral THA and a morphologically healthy hip as a reference (Kellgren–Lawrence ≤ 1) were included. The same cementless short stem with meta-diaphyseal fixation and cementless press-fit cup was implanted. The proximal femur was rated by Dorr’s classification, and subgroups were formed afterward. Measurements were carried out on preoperative and 3 months postoperative anterior–posterior radiographs of the pelvis. Kruskal–Wallis test, Fisher’s exact test and binary logistic regression were performed to evaluate the influence of the anatomical shape on postoperative leg length difference and offset reconstruction.

Results

The Dorr type did not show any significance influence on LLD (p = 0.532), or postoperative difference in femoral offset (p = 0.243), acetabular offset (p = 0.106) and hip offset (p = 0.698). Stem alignment (p = 0.705) and canal fill indices (CFI I: p = 0.321; CFI II: p = 0.411; CFI III: p = 0.478) were also without significant differences. Logistic regression did not show any significant increased risk for a LLD ≥ 5 mm or ≥ 10 mm as well as HO ≥ 5 mm or ≥ 10 mm.

Conclusion

Reconstruction of hip offset and postoperative leg length difference is not negatively influenced by Dorr type, canal flare index, cortical index and canal-to-calcar ratio in cementless short-stem THA. Implant positioning and canal fill are also not negatively affected by the anatomical shape of the proximal femur.

Level of evidence: Level IV.

Dislocation is a Leading Cause of Decreased Survival Rate in Primary Total Hip Arthroplasty Performed by Low-Volume Surgeons: Long-Term Retrospective Cohort Study

BACKGROUND

This study aimed to evaluate the complications and long-term survival of primary total hip arthroplasty (THA) performed by low-volume (LV) surgeons at a LV hospital. We also determined the relationship between complications and revisions.

METHODS

This retrospective cohort study included 220 THAs in 194 patients treated at our institution between 1998 and 2008, who received a minimum of a 10-year follow-up. The median annual THA volume at this hospital was 23 procedures (range, 11-32), and the annual volume per surgeon ranged from 1 to 19. We investigated the 90-day mortality and rates of periprosthetic joint infections, dislocations, and periprosthetic fractures up to the last visit (median follow-up, 11.8 years). Kaplan-Meier survival was calculated with revision as the end point.

RESULTS

Postoperative infections, dislocations, and fractures at any time during the follow-up period were reported for 1 hip (0.5%), 23 hips (9.8%), and 4 hips (1.8%), respectively. One death occurred within the first 90 days postoperatively. Fifteen hips required revision surgery, and the survival rate was 95.5% at 5 years and 94.1% at 10 years. Of 10 hips that required early revision surgery within 5 years after the index surgery, 9 were revisions to address recurrent dislocation.

CONCLUSION

The risk of dislocation was high. A high number of patients who underwent THA by LV surgeons required early revision because of dislocation. To achieve optimal long-term survivorship, LV surgeons should consider measures to reduce the risk of dislocation.

Cementless femoral stem fixation and leg-length discrepancy after total hip arthroplasty in different proximal femoral morphological types

PURPOSE

Leg-length changes at total hip arthroplasty (THA) may result from too proximal position of the femoral component, i.e. not being sunk deep enough into the femoral canal due to the size and shape of both medullary canal and implant. Some femoral implants are designed to achieve such fixation in the mediolateral dimension, while others also engage the bone anteroposteriorly. Our aim was to examine the relationship between proximal femoral morphology, osseointegration and leg-length equalization at THA. We asked whether the Dorr classification, femoral cortical index and canal flare index on preoperative radiographs had significant impact on THA aseptic loosening rates and post-operative leg-length discrepancy (LLD).

METHODS

Literature review included original articles on proximal femoral morphology with post-operative LLD and other clinical outcomes of THA, published in the last decade. Case reports and biomechanical studies without clinical data were excluded.

RESULTS

Higher femoral cortical index and/or canal flare index (corresponding to the Dorr type A) increases the risk of leg lengthening at THA. This is particularly notable in femoral stems with metaphyseal fixation, where high canal flare index has also been linked to osseointegration failure and implant loosening. On the other hand, lower canal flare index (corresponding to the Dorr type C) is more prevalent in the elderly population and increases late periprosthetic fracture rates and stress shielding. Even the most commonly used cementless femoral stems cannot offer optimal fit to intra-/extramedullary geometry or offset restoration in up to 30% of clinical cases.

CONCLUSIONS

Femoral morphology can have significant impact on post-operative LLD and osseointegration of cementless THA. Quantitative measurements of the proximal femoral canal may improve the choice of a particular implant and fixation method.