Reduced Incidence of Intraoperative Femur Fracture With a Second-Generation Tapered Wedge Stem

Increased risk of intraoperative and early postoperative periprosthetic femoral fracture with compaction compared with broaching in cementless THA: a single-center study of 6,788 hips

BACKGROUND AND PURPOSE

 Periprosthetic femoral fracture (PFF) is a significant complication of total hip arthroplasty (THA). Although biomechanical studies have indicated that the technique by which the femoral canal is prepared plays a role, few clinical studies have reported on how this might affect the fracture risk. This study compares the fracture risk between compaction and broaching with toothed instruments in cementless THA.

METHODS

Prospectively collected data from the quality register of a high-volume hospital was used. All primary arthroplasties using the Corail stem (DePuy Synthes) were included. All femoral fractures occurring within the first 90 days after the operation were included in the analysis. We determined the relative risk of sustaining PFF with compaction compared with broaching and adjusted for confounders (sex, age group, BMI, and use of a collared stem) using multivariable Poisson regression.

RESULTS

 6,788 primary THAs performed between November 2009 and May 2023 were available for analysis. 66% were women and the mean age was 65.0 years. 129 (1.9%) fractures occurred during the first 90 days after the operation, 92 (2.3%) in the compaction group and 37 (1.3%) in the broaching group. The unadjusted relative risk of fracture in the compaction group compared with the broaching group was 1.82 (95% confidence interval [CI] 1.25-2.66), whereas the adjusted relative risk was 1.70 (CI 1.10-2.70).

CONCLUSION

Compaction was associated with more periprosthetic fractures than broaching (2.3% versus 1.3%) within 90 days after surgery.

What features of stem increase the risk of intraoperative femoral fracture during cementless primary hip arthroplasty?

INTRODUCTION

Cementless fixation has become increasingly popular in hip arthroplasty due to its shorter operation time, easier technique, biologic fixation, and avoidance of bone cement implantation syndrome compared to cemented fixation. However, intraoperative periprosthetic femoral fracture (IOPFx) is a disconcerting complication during cementless hip arthroplasty. Our purpose was to identify the features of cementless stem that increase the risk of IOPFx during primary hip arthroplasty.

MATERIALS AND METHODS

We retrospectively reviewed all 4806 hip arthroplasties that was performed in a single institution from May 2003 to December 2020. Age at the index arthroplasty, sex, body mass index, physical status, ambulatory function, side of the operation, operational history, cause of the index arthroplasty, type of arthroplasty, surgical approach, surgeon, implant information, and events during the operation were investigated. The shoulder geometry and length of stem were also reviewed. The event of interest was narrowed down to IOPFx among various records of intraoperative events.

RESULTS

We found IOPFx of 2.6% among all the hips operated with cementless stem. In the multivariable analysis, female (OR = 1.52), childhood hip disease (OR = 2.30), stove-pipe femur (OR = 2.43), combined approach (OR = 2.60), and standard length of stem (OR = 1.59) were found to be significant risk factors of IOPFx.

CONCLUSIONS

In conclusion, a stem with a standard length is significantly associated with risk of IOPFx compared to a shortened stem. These findings highlight the importance of careful consideration in terms of the risk of IOPFx when standard length cementless stem is chosen.

Intraoperative Periprosthetic Femur Fracture - When is the Cerclage Enough?

BACKGROUND AND PLANNING

Intraoperative periprosthetic femoral fractures are among the most serious complications in both primary and revision arthroplasty. They are often not detected, despite intraoperative radiological control. Since an unnoticed intraoperative fracture often requires revision surgery, which has been associated with increased mortality rates, intraoperative diagnosis and corresponding direct and sufficient treatment are crucial. There are patient-, surgery-, and implant-specific risk factors that increase the possibilities of intraoperative fractures. The most common risk factors on the patient side are age, gender, and various pre-existing conditions, such as osteoporosis or rheumatic diseases. A minimally invasive approach and a cementless press-fit fixation are the most significant surgery- and implant-specific risk factors. The Vancouver classification or the modified Mallory classification are available for the classification of intraoperative periprosthetic femoral fractures. Based on these classifications, treatment recommendations can be derived. Different strategies are available for fracture management.

THERAPY

Generally, if the stem is stable, osteosynthesis can be performed with preservation of the implant. This procedure can be applied to the majority of cases with non-displaced fractures by using cerclages as fixation. An unstable implant may require replacement of the stem. In higher grade fractures, stabilisation by using plate osteosynthesis may be necessary. The aim is to achieve the most anatomical reposition possible for the best possible bony consolidation. The ultimate goal is high implant stability and restoration of the biomechanics.

Evaluation of Proximal Femoral Bone Mineral Density in Cementless Total Hip Arthroplasty: A 3-Arm Prospective Randomized Controlled Trial

BACKGROUND

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long-term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in 3 morphologically different uncemented femoral stem designs to investigate whether any particular design resulted in better preservation of BMD.

METHODS

A total of 119 patients were randomized to receive a proximally coated collarless dual-taper wedge stem, a proximally coated collarless anatomic stem, or a fully coated collarless triple-taper stem. All surgeries were performed via the posterior approach, with mobilization on the day of surgery. Dual x-ray absorptiometry scans (Lunar iDXA, GE Healthcare) assessed BMD across the 7 Gruen zones preoperatively and at 6 weeks and 2 years postoperatively; if available, the native contralateral femur was also assessed as a control. Patient-reported outcomes of pain, function, and health were also assessed at these follow-ups.

RESULTS

Averaged across all stems, BMD increased in zones 1 (2.5%), 2 (17.1%), 3 (13.0%), 5 (10%), and 6 (17.9%) at 2 years. Greater preservation of BMD was measured on the lateral cortex (zone 2) for both the dual-taper wedge and anatomic stems (p = 0.019). The dual-taper wedge stem also demonstrated preservation of BMD in the medial calcar (zone 7), while the anatomic and triple-taper stems declined in this region; however, the difference did not reach significance (p = 0.059). Averaged across all stems, BMD decreased in the mid-diaphysis region, distal to the stem tip (zone 4). All stems performed similarly at the time of final follow-up with respect to the patient-reported outcomes.

CONCLUSIONS

This study demonstrated maintenance of femoral BMD after use of 3 different cementless femoral stem designs, with all achieving excellent improvements in patient-reported outcomes. The stems designed to load the proximal metaphyseal region resulted in higher BMD in that region. No significant stress-shielding was observed; however, longer follow-up is required to elucidate the impact of this finding on implant survivorship.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Femoral Bowing Increases Early Postoperative Stress around the Femoral Stem in Humans: A Finite Element Analysis

Background

This study aimed to clarify the characteristics of stress distribution caused by the placement of tapered wedge stems in bowed femurs compared with that in normal femurs and the effect of varus stem placement.

Methods

Models with normal and enhanced bowing were created from the right-side computed tomography data of a 17-year-old woman with the least bowing among 40 participants who underwent anterior cruciate ligament reconstruction or operative treatment for trauma in our hospital between January 2017 and May 2018. Finite element analysis was performed, assuming the tapered wedge stem was placed in the neutral and varus positions.

Results

Varus stem placement on a femur with normal bowing showed a deviation and increase of von Mises stresses in the medial femur. Stem placement on a bowed femur, even when placed in the neutral position, increased stress across the periprosthetic bone. When the stem was placed in the varus position, von Mises stress across the periprosthetic bone increased. Zone 7, with strong bowing, demonstrated 3.6-fold increased stress compared with normal femurs. The maximum tensile principal stress was greatest in zone 6 and increased in zones 3 and 4.

Conclusions

Surgeons should assess femoral bowing preoperatively and pay particular attention to intraoperative stem alignment for femurs with high bowing.

Undetected Intraoperative Periprosthetic Femoral Fractures in Patients Undergoing Primary Total Hip Arthroplasty: A Retrospective Case Series and Literature Review

OBJECTIVE

Periprosthetic fracture in total hip arthroplasty (THA) can be catastrophic, and early detection and appropriate management are vital to the overall prognosis. This study aimed to describe and summarize the features of undetected intraoperative periprosthetic femoral fractures (IPFFs) in primary THA patients and treatment measures and to review the relevant literature.

METHODS

We reviewed a total of 6350 primary THAs performed at our institution between January 2013 and December 2020 and screened all IPFFs. Of 138 IPFFs, 24 were undetected and met the inclusion criteria. We recorded and compared basic patient and operative information and measured some parameters to evaluate canal morphologies based on preoperative radiographs. We also compared fracture line characteristics using postoperative radiographs to summarize the features of intraoperative fractures and propose treatment strategies. The Kolmogorov-Smirnov test was used to test the normality of the variable distributions. Measured parameters in all groups were analyzed using one-way analysis of variance and compared using Dunnett's test. The χ² and Fisher exact tests were used to compare reoperation rates across the groups. Interrater and intrarater reliability were evaluated by intraclass correlation coefficients.

RESULTS

Among the 24 hips, there was no significant difference in patient demographics, basic operative information or morphology. The incidence of IPFFs in primary THA patients was 2.17%, and up to 17.4% of IPFFs were undetected until postoperative fluoroscopy. The incidence of undetected IPFFs among all primary THA patients was 0.38% and varied by stem type, with the highest incidence in femurs with either anatomical (1.04%, 4/385) or modular stems (0.90%, 9/1003). Femurs with anatomical stems had a higher reoperation rate. The distal periprosthetic (Gruen zone 4) fracture line of femurs with tapered stems was more prone to involve the medial or lateral bone cortex, which could cause instability.

CONCLUSION

An undetected IPFF is most likely in femurs fitted with a prosthesis of an inappropriate size or type. Anatomical stems will most likely cause unstable fractures; thus, it is recommended to use them with caution and note the possibility of medial distal femoral fracture. Improper modular stem type or size selection results in longitudinal fractures of the distal femur, and prophylactic cerclage wire binding is recommended in dysplastic hips. Incorrect use of tapered stems in well-ossified femurs may cause distal femoral fractures involving the medial or lateral bone cortex. Intraoperative fluoroscopy after implantation may help detect hidden fractures.

Effectiveness of prophylactic double-looped wiring in cementless Hip arthroplasty: A biomechanical study in osteoporotic bone model using impaction simulation system

BACKGROUND

Periprosthetic femoral fracture (PFF) is well-known complication in cementless hip arthroplasty (HA), especially in the elderly with osteoporosis. To prevent intraoperative PFFs during HA, prophylactic cerclage wiring on the calcar area during femoral broaching and implant insertion is recommended. However, biomechanical data on the benefits of cerclage wiring in osteoporotic bone during impaction are limited and controversial. This study aimed to assess the efficacy of prophylactic double-looped cerclage wiring (PDLCW) during femoral broaching in the osteoporotic bone model with an impaction simulation system.

METHODS

Fifteen osteoporotic femur models were prepared and allocated to three groups; control group (no cerclage), PW group (received PDLCW), and CC+PW group (prepared as having calcar crack and received PDLCW). All femurs were broached under impaction force that sequentially increased until the visible fracture or calcar crack propagation was visible. The primary outcomes were mallet impaction force (MIF-CF) and mallet velocity (MV-CF) at the time of calcar fracture. The secondary outcomes were calcar fracture pattern and subsidence during calcar fracture (S-CF).

RESULTS

PW group showed a significant increase in average MIF-CF, by 40.4% and 120.2% (p<0.001) compared to the control and CC+PW groups, respectively. The average MV-CF in PW group was also significantly greater, 13.1% and 64.6% (p<0.001), compared to the control and CC+PW groups, respectively. Control group revealed significantly greater incidence of complete calcar fracture (60% vs. 0% vs. 0%, p = 0.024), and the highest S-CF compared to those in the PW and CC+PW groups (10.6 ± 6.0 mm, 6.7 ± 4.4 mm, and 1.3 ± 2.0 mm, p = 0.020).

CONCLUSIONS

This study showed that PDLCW significantly improved hoop stress resistance by increasing the calcar fracture threshold related to mallet impaction, decreasing the risk of complete calcar fracture.

Reduction of Periprosthetic Proximal Femur Fracture in Direct Anterior Total Hip According to Stem Design

The direct anterior approach (DAA) is gaining popularity in primary total hip arthroplasty (THA). Although DAA has demonstrated many advantages over other surgical approaches, periprosthetic femur fractures (PPFF) rates continue to be higher. Femoral stem designs that allow for easier insertion via a DAA may contribute to the higher rates of fracture seen in this approach. Certain stem designs and fixation methods may reduce the risk of PPFF via a DAA in primary THA.

Diagnosis and Management of Intraoperative Fractures in Primary Total Hip Arthroplasty

Intraoperative periprosthetic fractures are challenging complications that may affect implant stability and survivorship. Periprosthetic acetabular fractures are uncommon and infrequently are the focus of studies. Acetabular fractures are occasionally recognized after patients report unremitting groin pain weeks postoperatively. The widespread use of cementless acetabular cups might lead to higher number of fractures than is clinically detectable. Conversely, the incidence of intraoperative periprosthetic femoral fractures are more common and encompass a broad spectrum, ranging from a small cortical perforation to displaced fractures with an unstable prosthesis. Appropriate recognition, including mindfulness of preoperative patient and surgical risk factors, is critical to the successful management of acetabular and femoral complications. This comprehensive review article focuses on the incidence, patient and surgical risk factors, diagnosis, management, and clinical outcomes associated with intraoperative acetabular and femur fractures in primary total hip arthroplasty.

Outcomes of Cerclage Cabling for Intraoperative Calcar Cracks in Cementless Total Hip Arthroplasty Using Broach-Only, Tapered Wedge Stems

BACKGROUND

Intraoperative femoral fractures are well-known but often overlooked complications in total hip arthroplasty (THA). We examined outcomes of cerclage cabling for intraoperative calcar cracks in THA with cementless tapered wedge stems.

METHODS

In total, 4928 primary THAs were performed using broach-only, tapered wedge stems between January 2007 and November 2017 in a single institution. Of these, we identified 71 intraoperative calcar cracks (69 patients) managed by 2-mm cerclage cables. Clinical outcomes, amount of stem subsidence, and implant survivorship of the calcar crack group (68 THAs) were compared with those of the matched control group (68 THAs) without intraoperative fractures. Multivariate analysis was performed to identify potential risk factors for stem subsidence >3 mm.

RESULTS

The mean stem subsidence was greater in the calcar crack group (2.0 vs 1.2 mm, P = .021), whereas revision-free survivorships of THA were similar between groups at 6 years (98.5% vs 98.4%; log-rank, P = .987). In the calcar crack group, a Dorr type C femur and the absence of cabling proximal to the lesser trochanter (LT) were identified as independent risk factors for stem subsidence >3 mm. For the subgroup with 42 calcar cracks managed by a single cable applied proximal to the LT, revision-free survivorship of THA was 100% at 6 years. There was no complete radiolucency to indicate aseptic stem loosening in either group.

CONCLUSION

The application of a single cable proximal to the LT of the femur for intraoperative calcar cracks demonstrated 100% revision-free survivorship with lower stem subsidence in THA with tapered wedge stems.

Outcomes with Two Tapered Wedge Femoral Stems in Total Hip Arthroplasty Using an Anterior Approach

Background

The majority of hip arthroplasties in the United States utilize cementless acetabular and femoral components. Despite their similarities, stem geometry can still differ. The purpose of this study is to compare the clinical results of two wedge-type stem designs.

Methods

A retrospective study of patients who underwent primary THA utilizing a direct anterior approach between January 2016 and January 2017. Two cohorts were established based on femoral stem design implanted. Descriptive patient characteristics and surgical and clinical data was extracted which included surgical time, length of stay (LOS), presence of pain (categorized as groin, hip, or thigh pain) at the latest follow-up, and revisions. Immediate postoperative radiographs were compared with the latest follow-up radiographs to assess limb length discrepancies, stem alignment, and stem subsidence.

Results

A total of 544 patients were included. 297 patients received the Group A stem (morphometric) and 247 patients received the Group B stem (flat-tapered). A significantly higher proportion of Group B stems subsided ≥3 mm and were in varus alignment than the Group A design. Additionally, a significantly greater number of patients who received the Group B stem reported postoperative hip and thigh pain. The logistic regression found that the Group B stem was 2.32 times more likely to subside ≥3 mm than the Group A stem.

Conclusion

Our study suggests modestly improved radiographic and clinical outcomes and fewer instances of thigh pain, subsidence, and varus alignment in the patients who received the Group Ahip stem. Further studies are warranted to assess long-term significance.

Hemiarthroplasty for Femoral Neck Fractures in the Elderly: A Comparison of Cemented and Uncemented Femoral Stems

The incidence of displaced femoral neck fractures among elderly patients is increasing as the population ages.Historically, the preferred treatment for displaced femoral neck fractures in elderly patients has been hemiarthroplasty with use of cemented fixation of the implant. However, there is evidence that this technique may be associated with fat embolization and subsequent cardiopulmonary arrest in the early postoperative period. Cementing techniques are also associated with increased operative time when compared with cementless techniques.There is increasing evidence that, among elderly patients, the use of uncemented hemiarthroplasty has equivalent functional outcomes and overall mortality rates when compared with the use of hemiarthroplasty with cemented fixation. The main complication associated with uncemented hemiarthroplasty is intraoperative periprosthetic fracture.

Preferred Single-Vendor Program for Total Joint Arthroplasty Implants: Surgeon Adoption, Outcomes, and Cost Savings

BACKGROUND

In total joint arthroplasty, variation in implant use can be driven by vendor relationships, surgeon preference, and technological advancements. Our institution developed a preferred single-vendor program for primary hip and knee arthroplasty. We hypothesized that this initiative would decrease implant costs without compromising performance on quality metrics.

METHODS

The utilization of implants from the preferred vendor was evaluated for the first 12 months of the contract (September 1, 2017, to August 31, 2018; n = 4,246 cases) compared with the prior year (September 1, 2016, to August 31, 2017; n = 3,586 cases). Per-case implant costs were compared using means and independent-samples t tests. Performance on quality metrics, including 30-day readmission, 30-day surgical site infection (SSI), and length of stay (LOS), was compared using multivariable-adjusted regression models.

RESULTS

The utilization of implants from the preferred vendor increased from 50% to 69% (p < 0.001), with greater use of knee implants than hip implants from the preferred vendor, although significant growth was seen for both (from 62% to 81% for knee, p < 0.001; and from 38% to 58% for hip, p < 0.001). Adoption of the preferred-vendor initiative was greatest among low-volume surgeons (from 22% to 87%; p < 0.001) and lowest among very high-volume surgeons (from 61% to 62%; p = 0.573). For cases in which implants from the preferred vendor were utilized, the mean cost per case decreased by 23% in the program's first year (p < 0.001), with an associated 11% decrease in the standard deviation. Among all cases, there were no significant changes with respect to 30-day readmission (p = 0.449) or SSI (p = 0.059), while mean LOS decreased in the program's first year (p < 0.001).

CONCLUSIONS

The creation of a preferred single-vendor model for hip and knee arthroplasty implants led to significant cost savings and decreased cost variability within the program's first year. Higher-volume surgeons were less likely to modify their implant choice than were lower-volume surgeons. Despite the potential learning curve associated with changes in surgical implants, there was no difference in short-term quality metrics.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Incidence, Classification, and Risk Factors for Intraoperative Periprosthetic Femoral Fractures in Patients Undergoing Total Hip Arthroplasty With a Single Stem: A Retrospective Study

BACKGROUND

The collum femoris preserving (CFP) stem was a specially designed femoral neck preserving component. The incidence, classification, and risk factors for intraoperative periprosthetic femoral fractures with this special stem remain unclear.

METHODS

This was a retrospective study. We analyzed the clinical and radiological data of all patients who underwent primary hip arthroplasty with a CFP stem in our hospital between January 2006 and November 2018. Demographic characteristics and radiological features were obtained from the medical records and the Picture Archiving and Communication System, respectively. The incidence, Vancouver classification, and risk factors for intraoperative periprosthetic femoral fractures were identified.

RESULTS

A total of 1633 hips were included. The incidence rate of periprosthetic femoral fractures in patients undergoing total hip arthroplasty with a CFP stem was 3.2%. According to the Vancouver classification, there were 24 patients (45.3%) with Vancouver type A fractures, 27 patients (50.9%) with Vancouver type B fractures, and 2 patients (3.8%) with Vancouver type C fractures. Five independent risk (protective) factors were found, including surgical history (odds ratio [OR] = 3.275, 95% confidence interval [CI] = 1.192-8.997), neck-shaft angle (OR = 1.104, 95% CI = 1.058-1.152), neck length preserved (OR = 0.913, 95% CI = 0.850-0.980), canal flare index (OR = 0.636, 95% CI = 0.413-0.980), and bone mineral density (OR = 0.083, 95% CI = 0.016-0.417).

CONCLUSION

The detailed characteristics of intraoperative periprosthetic femoral fractures in patients who received a CFP stem were identified in this study. Cracks of the femoral neck and fractures on the front side of the proximal femur were more common in patients with CFP stems. As a kind of a femoral neck preserving stem, the anatomical features (eg, neck-shaft angle, preserving length) of the remaining femoral neck might influence the incidence and characteristics of intraoperative periprosthetic femoral fractures in patients with CFP stems.

Differentiating Nutrient Artery Canals of the Femur versus Fracture Lines in Patients with Total Hip Arthroplasty on Plain Radiographs

BACKGROUND

Nutrient artery canals of the femur are often visible on plain radiographs as radiolucent lines which may mimic fracture lines. The purpose of this study was to distinguish nutrient artery canals from fracture lines on plain radiographs.

MATERIALS AND METHODS

Ninety-three patients (102 hips) with an average age of 65.6 years were included in the study. We retrospectively analyzed nutrient artery canals of the femur on pre and postoperative anteroposterior (AP) and cross-table lateral (CTL) hip radiographs in patients with cementless total hip arthroplasty. The shape, number, location, direction of obliquity, length of nutrient artery canal, and the distance between the tip of the greater trochanter and the proximal end of the nutrient artery canal were measured.

RESULTS

Nutrient artery canals were determined in 54 hips (53.0%) on preoperative radiographs. The numbers of nutrient artery canals were entirely found to be one for each hip. The nutrient artery canals of the femur were the most frequently seen in the cortex on CTL radiographs with 32 hips (31.4%), whereas nutrient artery canals were not seen at all in the cortex on AP radiographs. All nutrient artery canals in the cortex on CTL radiographs coursed upward obliquely. Comparing to fracture lines, nutrient artery canals show less radiolucency, smaller diameter, and blunted ends in both the cortex and medullary cavity, show sclerotic walls in the cortex and have the less straight course in the medullary cavity.

CONCLUSIONS

Based on the results of this study, there are clearly distinguishable differences between nutrient artery canals of the femur and fracture lines on plain radiographs.