Comparison of Tri-Lock Bone Preservation Stem and the Conventional Standard Corail Stem in Primary Total Hip Arthroplasty

Increased stability of short femoral stem through customized distribution of coefficient of friction in porous coating

Stress shielding and aseptic loosening are complications of short stem total hip arthroplasty, which may lead to hardware failure. Stems with increased porosity toward the distal end were discovered to be effective in reducing stress shielding, however, there is a lack of research on optimized porous distribution in stem's coating. This study aimed to optimize the distribution of the coefficient of friction of a metaphyseal femoral stem, aiming for reducing stress shielding in the proximal area. A finite element analysis model of an implanted, titanium alloy short-tapered wedge stem featuring a porous coating made of titanium was designed to simulate a static structural analysis of the femoral stem's behavior under axial loading in Analysis System Mechanical Software. For computational feasibility, 500 combinations of coefficients of friction were randomly sampled. Increased strains in proximal femur were found in 8.4% of the models, which had decreased coefficients of friction in middle medial areas of porous coating and increased in lateral proximal and lateral and medial distal areas. This study reported the importance of the interface between bone and middle medial and distal lateral areas of the porous coating in influencing the biomechanical behavior of the proximal femur, and potentially reducing stress shielding.

Biomechanical Comparison of Impaction Techniques and Cross-Sectional Femoral Stem Shapes for Cementless Total Hip Arthroplasty

Introduction

Traditional mallet broaching and stem seating in cementless total hip arthroplasty (THA) can result in femoral stem misalignment, potentially reducing implant longevity. This study aimed to compare the pullout strength of cementless THA femoral stems with different cross-sectional designs achieved through the powered impactor method versus the traditional mallet method.

Methods

The authors utilized 24 polyurethane foam femurs and two femoral bone preservation stems with different proximal cross-sectional shapes (double taper: ACTIS®, size 5; flat taper: TRI-LOCK®, size 5). A single orthopedic surgeon broached each femur from size 0 to size 5 using either the powered impactor or mallet impaction methods. Broaching time and component implantation times were recorded. A load-to-failure pullout strength test was conducted, and the ultimate pullout load was recorded.

Results

The broaching time for the TRI-LOCK® stem showed a statistically significant difference between the two impaction methods (powered: 37±7 seconds, mallet: 75±29 seconds, F[3, 20] = 4.56, p = 0.002), but no statistically significant difference was detected for the ACTIS® stem between the two impaction methods (powered: 47±22 seconds, mallet: 59±9 seconds, F[3, 20] = 4.56, p = 0.304). There was a statistically significant difference in pullout strength between the two impaction groups, and this strength was influenced by the implant cross-sectional shape (ACTIS®: 774±75N versus 679±22N, F(3,20) = 16.38, p = 0.018; TRI-LOCK®: 616±57N versus 859±85N, F(3, 20) = 16.38, p <0.001).

Conclusions

The technique used for femoral bone preparation (powered impactor versus mallet) and the cross-sectional design of the cementless femoral stem are crucial factors that affect initial stem stability and operation time.

Alignment and mechanics evaluation for a compaction broach stem versus a blade style proximal press fit stem using 3-Dimensional planning

Three-dimensional (3D) preoperative planning tools can be used to help plan and compare component alignment scenarios for different total hip arthroplasty systems to ultimately improve postoperative outcomes and patient satisfaction. The objective of this study is to use 3D preoperative planning tools based on patient-specific bone models to compare two different stem designs, specifically a compaction broach stem and a proximal press fit stem. The planner uses patient-specific proximal femoral bone morphology to suggest a specific implant size and placement. The planner then allows for preoperative predictions of component head positioning, stem fit within the canal, and potential cortical bone reaming that must be done, as well as postoperative predictions of stability and mechanics. The stems were evaluated to determine the accuracy of stem placement, the theoretical volumetric bone removal/reaming required to achieve a desired fit, and the associated postoperative mechanics. This study demonstrated that there was a difference in component alignment and predicted postoperative mechanics between a compaction broach stem and a press fit stem, with the compaction broach stem allowing for more accurate alignment with less required bone removal, resulting in improved postoperative stability and mechanics. This study also demonstrated that much of the stem misalignment for both systems occurred in the anterior/posterior direction. Overall, 3D preoperative planning offers significant benefits and novel intraoperative insight, and the industry should continue to enhance their THA preoperative planning tools.

The compared study about femoral stem malalignment with or without the special curved rasp during DAA total hip arthroplasty

OBJECTIVE

To investigate whether the application of a curved rasp on the femoral side is effective in reducing the incidence of stem malalignment in total hip replacement with direct anterior approach (DAA-THA), followed by the analysis of the independent risk factors affecting stem malalignment.

METHODS

Retrospective analysis was carried out covering 160 patients undergoing DAA-THA from January 2019 to December 2021, with Tri-Lock (BPS, Depuy) stem applied in all 113 patients were screened according to inclusion and exclusion criteria. The data of gender, age, body mass index, preoperative diagnoses, Dorr classification, FAR ratio, pelvic morphology ratio, WOMAC scores, were analyzed to explore the independent factors influencing the malalignment of the femoral prosthesis implantation. Then data of patients were divided into group A and group B according to whether the curved rasp was taken during the operation. The chi-square test was performed to compare the incidence of femoral stem malalignment between the two groups.

RESULTS

There revealed two independent risk factors: BMI and FAR ratio that affected femoral stem malalignment. The increased BMI was associated with a higher probability of femoral stem malalignment (P<0.05), the probability of malalignment of femoral stem in FAR ratio<1 was 1.15 times higher than that in FAR>1(OR = 1.15, 95% CI: 1.03-1.28, P<0.05). Further grouping analysis showed that the incidence of femoral stem malalignment in patients with intraoperative application of curved rasp was 27%, while in patients without curved rasp, the incidence of femoral stem malalignment increased significantly to 48.7%(P<0.05). The placement angle of prosthesis in group A was significantly better than that in group B, especially mild femoral stem malalignment (0%) and severe femoral stem malalignment (2.70%), and the difference was statistically significant (P < 0.05). There found no significant difference in age, gander, intraoperative complications and last follow-up assessment of WOMAC scores between the two groups of patients.

CONCLUSIONS

In DAA-THA, BMI and FAR ratio act as the independent risk factors for femoral stem malalignment. Intraoperative use of a curved rasp significantly reduces the incidence of malalignment of the femoral stem.

Tri-Lock Bone Preservation Stem Versus Conventional Corail Stem in Primary Total Hip Arthroplasty via Direct Anterior Approach: A Short-Term, Retrospective, Comparative Study

BACKGROUND he present study was performed to evaluate the clinical efficacy of Tri-Lock bone preservation stems vs conventional Corail stems in primary total hip arthroplasty via direct anterior approach. MATERIAL AND METHODS In this retrospective analysis, patients receiving THA via DAA in a single-center hospital from January 2019 to March 2020 were assessed for eligibility and assigned to either a Tri-Lock BPS group or a Corail group based on the use of prostheses. Outcome measures for the efficiency evaluation of the 2 prostheses included perioperative outcomes, imaging results, Harris Hip Score, Western Ontario and McMaster University Osteoarthritis Index, and visual analog scale scores at 3, 6, 12, and 24 months postoperatively. RESULTS A total of 204 patients were included, including 98 patients (98 hips) in the Tri-Lock BPS group and 106 patients (106 hips) in the Corail group. Patients receiving Tri-Lock BPS exhibited better pain relief than those with Coral stems. Tri-Lock BPS had a higher safety profile vs Corail stems by significantly reducing the risk of complications (P=0.004). A markedly increased HHS score (84.42±16.27 vs 78.61±12.78, P=0.002) and a lower WOMAC score (25.08±15.39 vs 32.14±11.56, P=0.001) at 3 months postoperatively were observed in patients with Tri-Lock BPS vs those with Corail stems, indicating better restoration of hip function using Tri-Lock BPS. CONCLUSIONS During total hip arthroplasty via DAA, Tri-Lock BPS causes a smaller surgical wound, reduces the operative time and intraoperative bleeding, and produces less soft-tissue damage vs Corail stems, providing great benefits in femoral prosthesis placement.

Intermediate to Long-Term Outcomes of a Short, Tapered, Highly Porous, Proximally Coated Cementless Femoral Stem

BACKGROUND

Short cementless stems in total hip arthroplasty have gained increasing popularity, yet on-going studies of many of these implants are lacking. The aim of this study was to evaluate the minimum 5 year clinical and radiological results of a short, highly porous single tapered-wedge cementless femoral implant.

METHODS

A retrospective study of 281 hips in 256 patients who had a minimum 5-year follow-up and underwent primary total hip arthroplasty (THA) between 2010 and 2016 were evaluated. Clinical and radiological results, complications, and the presence of postoperative thigh pain were evaluated.

RESULTS

The mean follow-up was 8 years (range, 5 to 12 years). Clinically, patients had significant improvement in the average patient related outcome scores (PROMS) postoperatively (Harris Hip Score: pre 47 vs post 95, University of California Los Angeles (UCLA) activity scale: pre 4 vs post 6, Western Ontario and McMaster Universities Arthritis Index (WOMAC): pre 51 vs post 3, SF-12 Physical Component Summary (PCS): pre 32 vs post 52, SF-12 Mental Component Summary (MCS): pre 49 vs post 55 (P<0.001)). Radiographic signs of ingrowth were present in all hips. There were three patients (1.1%) who developed transient thigh pain postoperatively, all of which resolved with non-operative management.

CONCLUSION

This study provides the longest follow-up of this short, highly porous single tapered-wedge cementless femoral stem in the literature. This short single wedge stem with its highly porous coating demonstrated reproducible bone ingrowth in all patients, and significant functional improvement with a very low rate of transient thigh pain.

Comparison of Preoperative Computed Tomography and Intraoperative Estimation in Predicting the Version of a Single-Wedge Femoral Stem

Objective

Early prediction of stem version aids in optimization of combined version during total hip arthroplasty (THA). This study aimed to analyze the discrepancy between stem version and native femoral version measured by different methods, and to explore which method can better predict the stem version.

Methods

We retrospectively reviewed 26 patients (39 hips) treated with robot‐assisted THA in our hospital between September 2019 and December 2019. A straight, single‐wedge, cementless stem (Accolade II) was used in all cases. Preoperative femoral version was measured at three levels on computerized tomography (CT) scan from the top to the middle level of femoral neck (Level 1 to Level 3). During THA, the version on cutting surface was measured prior to femoral broaching based on two reference lines: mid‐cortical line and T line (trochanteric fossa to the middle of medial cortex). After femoral broaching, stem version was measured based on the femoral neck trial using Mako system (Stryker). In the statistical analysis, the difference and absolute discrepancy between stem version and femoral version measured with various methods were examined using paired t‐test, and the relationship between stem version and various femoral versions were examined using correlation analysis.

Results

Mean femoral neck version (Level 1) was 9.5° ± 2.6° (range, −16.8°‐42.5°), while mean stem version measured by Mako system was 19.9° ± 2.0° (range, −8.0°‐49.0°). Femoral version measured with each method showed a moderate correlation with stem version (p < 0.05). There was a significant difference between stem version and femoral version except at Level 3, with a mean difference of 0.8° ± 13.6° (p = 0.729). With regard to the intraoperative estimation, stem version significantly increased compared to the value based on mid‐cortical line, with a mean difference of 8.4° ± 13.1° (p < 0.001). However, the mean value of stem version was a little smaller than that of femoral version measured by reference to T line, but without statistical significance (p = 0.156). No postoperative dislocations occurred during the study period. No revision was required for any component.

Conclusions

The middle level of femoral neck on CT scan and T line on cutting surface are better references to measure femoral version for predicting postoperative stem version. However, the relationship between stem version and predictive value was flexible. Therefore, further three‐dimensional studies of postoperative CT are needed to validate the press‐fit fixation and rotational freedom of the single‐wedge stem.

Chronic Pseudoaneurysm and Anterior Dislocation After Total Hip Arthroplasty Complicated by Arterial Injury: A Case Report

CASE

A 64-year-old man presented 18 months after total hip arthroplasty complicated by vascular injury with a history of leg pain, inability to mobilize, and progressive chronic leg edema. It is presumed that there was persistent subtle bleeding over time with pseudoaneurysm formation and prosthetic hip dislocation secondary to the mass effect.

CONCLUSION

Physicians should consider pseudoaneurysm as a possible diagnosis when confronted with a large intra-articular mass in the hip after a relatively short follow-up period, particularly in the context of a prior vascular injury at the time of the index procedure.

Clinical and radiological results of high offset tri-lock bone preservation stem in unilateral primary total hip arthroplasty at a minimum follow-up of 3 years

Background

Although the high offset Tri-Lock bone preservation stem (BPS) was used widely, few studies explored the clinical and radiological results. The purpose of this study was to determine the clinical and radiological results of high offset Tri-Lock BPS in unilateral primary total hip arthroplasty (THA) at a minimum follow-up of 3 years.

Methods

55 patients who underwent cementless THA with high offset Tri-lock BPS from 2017 to 2018 were followed for a minimum follow-up of 3 years. Patients were assessed clinically for complications, Harris hip score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Oxford Hip Score (OHS). Femoral offset (FO), acetabular offset (AO), hip offset (HO), HO difference, and leg length discrepancy (LLD) were measured on the anteroposterior (AP) pelvic radiograph. Standard pelvic AP and lateral radiographs were used to evaluate for evidence of bone ingrowth, stem subsidence, stem alignment, radiolucent line around the stem, osteolysis, loosening, ectopic ossification, and femoral stress shielding.

Results

No patients reported complications during hospitalization nor the follow-up period. At a mean follow-up of 42.5 months, the mean HHS, WOMAC, and OHS scores showed a significant improvement from preoperative to the latest follow-up. No patients reported thigh pain. No revision nor sign of radiographic loosening had been detected. The high offset Tri-Lock BPS significantly improved the FO and HO postoperatively. HO difference and LLD were balanced postoperatively. No sign of stem subsidence, radiolucent line, osteolysis, loosening, ectopic ossification, nor severe stress shielding (more than grade 3–4) were observed at the latest follow-up.

Conclusion

The high offset Tri-Lock BPS demonstrated excellent clinical and radiographic outcomes at a minimum follow-up of 3 years. HO difference and LLD between legs decreased significantly and achieved balance postoperatively. Long-term follow-up is required for a definitive conclusion.