Clinical characteristics and risk factors of periprosthetic femoral fractures associated with hip arthroplasty: A retrospective study

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.

Long-term survival and complication rate of cementless prosthetic stems in primary total hip arthroplasty categorized by types according to Mont classification: a regional registry-based study on 53,626 implants

INTRODUCTION

The purpose of this retrospective registry-based study is to assess survival and causes of failure of cementless stem implants used in total hip arthroplasty (THAs), to ascertain if there are differences when these are categorized according to the six types described by Mont.

METHODS

Data collected from the regional registry regarding all primary THAs performed from 2000 to 2019 were analyzed. Femoral prosthetic stems were divided into the six types of Mont classification. For each stem type, number of implants, survival and causes of failure were evaluated and compared.

RESULTS

The most frequently implanted stem type was the 3c type (53.4%). Type 1 had the lowest stem failure rate (1.6%), and type 6 showed the highest (3.9%). Periprosthetic fracture was the most frequent complication in type 6, accounting for 34.5% of failures. Aseptic loosening was the main complication in type 2 stems, accounting for 36.4% of failures. Pairwise comparisons showed significant higher survival of type 1 compared to type 3c (p = 0.000026) and type 6 (p = 0.000076), and between type 3a compared to type 3c (p = 0.03) and type 6 (p = 0.026).

CONCLUSION

Significant variations in implant survival rates were found among the six Mont-types of cementless stems. These findings emphasize the paramount importance of stem design and fixation area in determining long-term survival, providing a guidance for orthopedic surgeons in the selection of the most appropriate stem for primary THA, contributing to our understanding of cementless stem performance, presenting invaluable insights to further improve patient outcomes in THA surgery.

The Effect of Cerclage Banding Distally to a Clamshell Fracture Pattern in Total Hip Arthroplasty-A Biomechanical Study

OBJECTIVES

As currently there is no existing biomechanical work on the topic of interest, the aim of the current study was to investigate the effect of cerclage banding distally to an intraoperatively occurring proximal periprosthetic femoral clamshell fracture versus a non-fractured femur after total hip arthroplasty.

METHODS

A diaphyseal anchoring stem was implanted in twenty paired human cadaveric femora, assigned to a treatment and a control group. In the treatment group, each specimen was fitted with a cerclage band placed 3 mm distally to a clamshell fracture, created with an extent of 40% of the anchoring length of the stem. The resulting fragment was not treated further. The contralateral specimens were left with the stems without further fracture creation or treatment. All constructs were tested under progressively increasing cyclic axial loading until failure. Relative bone-implant movements were monitored by motion tracking.

RESULTS

Number of cycles and the corresponding load at stem loosening, defined as 1 mm displacement of the stem along the shaft axis, were 31,417 ± 8870 and 3641.7 ± 887 N in the control group, and 26,944 ± 11,706 and 3194.4 ± 1170.6 N in the treatment group, respectively, with no significant differences between them, p = 0.106.

CONCLUSION

From a biomechanical perspective, cerclage banding distally to an intraoperative clamshell fracture with an extent of 40% of the anchoring length of the stem demonstrated comparable resistance against hip stem loosening versus a non-fractured femur. It may therefore represent a valid treatment option to restore the full axial stability of a diaphyseal anchoring stem. In addition, it may be considered to keep the medial wall fragment unfixed, thus saving operative time and minimizing associated risks.

Use of Short Stems in Revision Total Hip Arthroplasty: A Retrospective Observational Study of 31 Patients

Background and Objectives: Implantation of a short femoral stem in revision total hip arthroplasty (rTHA) could reduce the perioperative time, soft tissue damage, and preserve the bone stock of the proximal femur. The objective of this study was to describe the clinical and radiographic outcomes after the use of short stems in rTHA with a follow-up of 1 to 5 years. Materials and Methods: This retrospective, single center, and observational study analyzed the data of 31 patients (12 female, 19 male) with a median (interquartile range) age of 68.2 years (61.2-78.4) and BMI of 26.7 kg/m2 (24.6-29.4) who received an uncemented short femoral stem in rTHA between 2015 and 2020. Clinical outcomes were extracted from medical reports and assessed using the modified Harris Hip Score (mHHS), the numerical rating scale (NRS) for pain and satisfaction, and the UCLA Physical Activity Score. Radiographs were analyzed for stem subsidence, fixation, and bone parameters. The Wilcoxon test was used for pre-post rTHA differences (p < 0.05); clinical relevance was interpreted based on effect sizes according to Cohen's d. Results: All the clinical outcome measures improved significantly (p ≤ 0.001) at follow-up compared to preoperative status, with large effect sizes (Cohen's d) ranging from 2.8 to 1.7. At the last follow-up, the median (interquartile) mHHS was 80.9 (58.6-93.5). Stem fixation was stable in all cases. Complications included stem subsidence of 3 mm (n = 1) and 10 mm (n = 1), heterotopic ossification Brooker stage III (n = 2), intraoperative femur perforation (n = 1), periprosthetic fracture Vancouver type A (n = 1), and dislocation (n = 2). Conclusions: The good clinical results in our selective study population of patients with mild to moderate bone deficiency, supported by large effect sizes, together with a complication rate within the normal range, support the consideration of short stems as a surgical option after a thorough preoperative analysis.

Cementless femoral stem revision in total hip arthroplasty: The periprosthetic clamshell fracture. A biomechanical investigation

To biomechanically evaluate the stability of a diaphyseal anchored, cementless stem in presence of a proximal periprosthetic femoral medial wall defect compared to the stability of the same stem in an intact femur. Twenty-two paired human cadaveric femora were pairwise assigned either to a fracture group, featuring a proximal medial wall defect involving 40% of the stems medial anchorage distance, or a control group with native specimens. The specimens were tested under a monotonically increasing cyclic axial loading protocol. Load, cycles, and multiples of the respective body weight at implant loosening was measured. Mean initial stiffness was 2243.9 ± 467.9 N/mm for the intact group and 2190.1 ± 474.8 N/mm for the fracture group. Mean load to loosening in the intact group was 3210.5 ± 1073.2 N and 2543.6 ± 576.4 N in the fracture group, with statistical significance. Mean cycles to loosening in the intact group were 27104.9 ± 10731.7 and 20431.5 ± 5763.7 in the fracture group, with statistical significance. Mean multiples of the resulting body weight at loosening in the intact group was 548.3 ± 158.5% and 441.4 ± 104% in the fracture group, with statistical significance. A medial wall defect involving 40% of the medial anchorage distance significantly decreases the axial stability of a diaphyseal anchored stem. However, mechanical failure occurred beyond physiological stress. At loosening rates of about 4 multiples of the body weight in the fracture group, a "safe zone" remains of a 0.5-fold body weight for maximum loads and twofold body weights for average loads.

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.

Risk factors affecting the incidence of postoperative periprosthetic femoral fracture in primary hip arthroplasty patients: a retrospective study

The purpose of this study was to identify the characteristics and risk factors for postoperative periprosthetic femoral fracture (PFF). This was a retrospective cohort study of 108 patients with and 432 control patients without postoperative PFF. Demographic characteristics, surgery-related information (primary hip disease diagnosed, fixation, femoral stem, method of operation, and bone resorption of the proximal femur), and postoperative patient outcomes (hip function, treatment history, and patients' lifestyle behaviors) were recorded and compared between the groups. PFF characteristics, such as the classification, time, and cause, were also documented, and a Cox regression model was built to identify the independent risk factors for postoperative PFF in these patients. Six independent risk factors for postoperative PFF were identified, namely, advanced age (hazard ratio (HR) = 1.026, 95% confidence interval (CI) = 1.007-1.045), femoral neck fracture as the primary disease (HR = 4.536, 95% CI = 2.955-6.961), osteoporosis (HR = 2.043, 95% CI = 1.234-3.383), hemiarthroplasty (or HA, HR = 2.173, 95% CI = 1.327-3.558), bone resorption of the proximal femur (HR = 1.627, 95% CI = 1.090-2.430), and a standard- or long-stem femoral prosthesis (HR = 2.996, 95% CI = 1.480-6.067). The predictive values for a low risk (estimated incidence ≤ 50%), moderate risk (estimated incidence 51%-89%), and high risk (estimated incidence ≥ 90%) of PFF were ≤ 3.0 points, 3.0-10.0 points, and ≥ 10.0 points, respectively. Most patients with postoperative PFF had Vancouver type B fractures. Six independent risk factors for postoperative PFF were identified: advanced age, hip fracture as the primary disease, osteoporosis, HA, bone resorption of the proximal femur, and a long femoral stem.

Biomechanical Characteristics of the Femoral Isthmus during Total Hip Arthroplasty in Patients with Adult Osteoporosis and Developmental Dysplasia of the Hip: A Finite Element Analysis

Objective

This study investigated the underlying mechanisms of high fracture incidence in the femoral isthmus from a biomechanical perspective.

Methods

We retrospectively analyzed a total of 923 primary total hip arthroplasty (THA) patients and 355 osteoporosis (OP) patients admitted from January 2010 to January 2018. Through a series of screening conditions, 47 patients from each group were selected for inclusion in the study. The datasets on the unaffected side and affected side of the patients with unilateral developmental dysplasia of the hip (uDDH) were respectively classified as the normal group (Group I) and he tDDH group (Group II), and that of patients with osteoporosis were classified as the OP group (Group III). In this study, first, we collected computed tomography (CT) images and measured geometric parameters (inner and outer diameters) of the isthmus. Thereafter, to study biomechanical properties, we established six finite element models and calculated values of von Mises stress for each group with the methods of data conversion and grid processing.

Results

Compared with those of patients in the normal group, the values of the inner and outer diameters of femoral isthmus of patients in the DDH group were significantly lower (P < 0.001), while the inner diameters of patients in the OP group were significantly higher (P < 0.001) and the outer diameters of patients in the OP group showed no significant difference (P> 0.05). The cortical rates of patients in the normal group and the DDH group appeared insignificant (P > 0.05), and those of patients in normal group were significantly higher than those of patients in the OP group (P < 0.001). Moreover, patients in the DDH group showed a higher von Mises stress value than patients in the normal group (P < 0.001), but statistically speaking the values between patients in the OP and normal groups were insignificant (P > 0.05).

Conclusions

The relatively shorter inner and outer diameters of the isthmus in DDH resulted in intensive von Mises stress under the torque of the hip location, and induced a high fracture incidence. However, in patients in the OP group, the geometric morphology exhibited no anatomical variation, and the fracture was not due to the intensity of von Mises stress.

Management of Periprosthetic Acetabular Fractures: A Critical Analysis and Review of the Literature

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Periprosthetic acetabular fractures are uncommon and infrequently the focus of studies.

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Acetabular fractures are occasionally recognized postoperatively when patients report unremitting groin pain weeks after surgery.

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The widespread use of cementless acetabular cups might lead to a higher number of fractures than are clinically detectable.

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Appropriate recognition, including mindfulness of preoperative patient and surgical risk factors, is critical to the successful management of acetabular complications.

The race for the classification of proximal periprosthetic femoral fractures : Vancouver vs Unified Classification System (UCS) - a systematic review

Background

Periprosthetic femoral fractures (PFFs) represent a major cause for surgical revision after hip arthroplasty with detrimental consequences for patients. The Vancouver classification has been traditionally used since its introduction in 1995. The Unified Classification System (UCS) was described in 2014, to widen the spectrum by aiming for a more comprehensive approach. The UCS also aimed to replace the Vancouver classification by expanding the idea of the Vancouver classification to the whole musculoskeletal apparatus. After introduction of the UCS, the question was raised, whether the UCS found its place in the field of analysing PFFs. Therefore, this systematic review was performed to investigate, the use of the UCS compared to the established Vancouver classification.

Methods

Medline was searched for reports published between 1 January 2016 and 31 November 2020, without language restriction. Included were original articles, irrespective of the level of evidence and case reports reporting on a PFF and using either the Vancouver or the UCS to classify the fractures. Excluded were reviews and systematic reviews.

Results

One hundred forty-six studies were included in the analysis. UCS has not been used in a single registry study, giving a pooled cohort size of 3299 patients, compared to 59,178 patients in studies using the Vancouver classification. Since 2016, one study using UCS was published in a top journal, compared to 37 studies using the Vancouver classification (p=0.29). During the study period, the number of yearly publications remained stagnant (p=0.899).

Conclusions

Despite valuable improvement and expansion of the latter UCS, to date, the Vancouver system clearly leads the field of classifying PFFs in the sense of the common use.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05240-w.

Cause-Specific Stem Revision Risk in Primary Total Hip Arthroplasty Using Cemented vs Cementless Femoral Stem Fixation in a US Cohort

BACKGROUND

We sought to evaluate the cause-specific revision risk following hybrid (cemented stem mated to a cementless acetabular implant) vs cementless total hip arthroplasty (THA) in a US cohort.

METHODS

Primary elective THA for osteoarthritis was identified using Kaiser Permanente's Total Joint Replacement Registry (2001-2018). Multivariable Cox regression was used to evaluate cause-specific revision, including aseptic loosening, infection, instability, and periprosthetic fracture (PPF), for hybrid vs cementless THA. Analysis was stratified by age (<65, 65-74, and ≥75 years) and gender.

RESULTS

The study cohort comprised 88,830 THAs, including 4539 (5.1%) hybrid THAs. In stratified analysis, hybrid THA had a higher revision risk for loosening in females in all 3 age subgroups. A lower risk of revision for PPF was observed following hybrid THA in females aged ≥75 years. For females ≥75 years, cementless THA had an excess PPF risk of 0.9% while hybrid THA had an excess loosening risk of 0.2%, translating to a theoretical prevention of 10 PPF revisions but a price of 3 loosening revisions per 1000 hybrid THAs. No difference in revision risk was observed in males.

CONCLUSION

We observed differences in cause-specific revision risks by method of stem fixation which depended upon patient age and gender. Although the trend toward all cementless fixation continue, there may be a role for hybrid fixation in females ≥75 years to mitigate risk for revision due to PPF at the potential cost of a slight increase in longer term aseptic loosening.

LEVEL OF EVIDENCE

Level III.

Risk Factors for Intraoperative Periprosthetic Femoral Fractures in Patients with Hip Dysplasia Undergoing Total Hip Arthroplasty with Uncemented Prostheses

OBJECTIVES

To determine the potential risk factors for intraoperative periprosthetic femoral fractures in patients with developmental dysplasia of the hip (DDH) undergoing total hip arthroplasty (THA).

METHODS

This was a retrospective study. Patients who were diagnosed with DDH and undergoing THA (by artificial joint replacement) at our hospital from January 1999 to December 2019 were included in this study. Clinical and radiological factors were obtained from their medical records, such as age, sex, Crowe classification, morphological features of proximal femur, and features of surgical procedure. The outcome of interest was the occurrence of intraoperative periprosthetic femoral fracture, which was recorded and classified according to the Vancouver classification system. According to the fracture status, the patients were divided into two groups: the fracture group and the non-fracture group. Multivariate logistic regression model was built to identify the risk factors for these fractures.

RESULTS

A total of 1252 hips were finally included. Intraoperative periprosthetic femoral fractures were identified in 62 hips. The incidence of intraoperative periprosthetic femoral fractures in patients with DDH undergoing THA was 4.95%. There were 22 patients (proportion = 35.48%, incidence = 1.76%) with Type A fractures, 38 (proportion = 61.29%, incidence = 3.04%) with Type B fractures, and two (proportion = 3.23%, incidence = 0.16%) with Type C fractures. Six independent risk factors for intraoperative periprosthetic femoral fractures were identified: osteoporosis (OR = 3.434; 95% CI, 1.963-6.007), previous surgical history (OR = 4.797; 95% CI, 2.446-9.410), Dorr Type A canal (OR = 3.025; 95% CI, 1.594-5.738), retained femoral neck length (OR = 1.121; 95% CI, 1.043-1.204), implanted metaphyseal-diaphyseal fixation stems (OR = 3.208; 95% CI, 1.562-6.591), and implanted stem with anteversion design (OR = 2.916; 95% CI, 1.473-5.770).

CONCLUSIONS

The overall incidence of intraoperative periprosthetic femoral fractures in patients with DDH undergoing THA was 4.95%, which was at a moderate level compared to patients with other diseases undergoing THA. Six independent risk factors were identified: osteoporosis, previous surgical history, Dorr Type A canal, insufficient neck osteotomy level, implantation of metaphyseal-diaphyseal fixation stem, and implantation of a stem with an anteversion design. Comprehending these risk factors might help surgeons prevent the occurrence of these intraoperative periprosthetic femoral fractures in patients with DDH.

Does Femoral Component Cementation Affect Costs or Clinical Outcomes After Hip Arthroplasty in Medicare Patients?

BACKGROUND

Bundled payment initiatives were introduced to reduce costs and improve quality of care. Cemented vs cementless femoral fixation is a modifiable variable that may influence the cost and quality of care. New bundled payment data from the Centers for Medicare and Medicaid Services allowed us to study the influence of femoral fixation strategy on (1) 90-day costs; (2) readmission rates; (3) reoperation rates; (4) length of stay (LOS); and (5) discharge disposition for Medicare patients undergoing total hip arthroplasty.

METHODS

We retrospectively studied 1671 primary total hip arthroplasty Medicare cases, comparing 359 patients who received cemented femoral fixation to 1312 patients who received cementless fixation. Centers for Medicare and Medicaid Services cost data as well as clinical data were reviewed. Demographic differences were present between the 2 cohorts. Statistical analyses were performed, including multiple regression models to adjust for baseline differences.

RESULTS

Controlling for cohort differences, cemented patients were significantly more likely to be discharged home compared to cementless patients. Cemented patients also demonstrated trends toward lower costs, lower readmission rates, and shorter LOS compared to cementless patients. All reoperations within the early postoperative period occurred in patients managed with cementless femoral fixation.

CONCLUSION

Among Medicare patients, cemented femoral fixation outperformed cementless fixation with respect to discharge disposition and also trended toward superiority with regards to LOS, readmission, cost of care, and reoperation. Cemented femoral fixation remains relevant and useful despite the rising popularity of cementless fixation.

The location of the fracture determines the better solution, osteosynthesis or revision, in periprosthetic femoral fractures

Purpose

Periprosthetic femoral fractures are difficult to treat, but few reports have included many periprosthetic femoral fractures. The purpose of this study was to investigate the trends and characteristics of a large number of periprosthetic femoral fractures and to determine the best treatment strategy for such fractures.

Methods

The fracture type according to the Vancouver classification, the stem fixation style of previous surgery, the elapsed time from previous surgery, and the treatment method for periprosthetic fractures of 51 patients with periprosthetic femoral fractures who were seen between 2006 and 2018 were investigated.

Results

The types of fractures according to the Vancouver classification were: type A 5.9%, type B1 47%, type B2 20%, type B3 2.0%, and type C 25%. Of the previous surgeries, 76% were cementless fixation, and 24% were cemented fixation. The mean duration from previous surgery to periprosthetic femoral fracture was 8 years and 7 months (1-358 months), and injury within 1 year from previous surgery was most commonly observed (24%). As treatment for periprosthetic femoral fractures, conservative treatment was performed in 8%, and surgery was performed in 92%. Of the surgery cases, 53% underwent osteosynthesis, and 39% underwent revision surgery. Of type B1 surgery cases, 58% were treated with osteosynthesis, and 33% underwent revision surgery, although type B1 had no stem loosening.

Conclusion

Many periprosthetic femoral fractures occurred within 1 year after the previous surgery. Therefore, preventive measures for periprosthetic femoral fractures should be started immediately after total hip replacement. In addition, revision surgery was performed even if the stem was not loosened in cases where it was judged that sufficient osteosynthesis could not be performed.

Relationships between the femoral neck-preserving ratio and radiologic and clinical outcomes in patients undergoing total-hip arthroplasty with a collum femoris-preserving stem

The femoral neck-preserving ratio is crucial in arthroplasty with a collum femoris-preserving (CFP) stem. The aim of our study was to analyze the relationships between the neck-preserving ratio and the short-term radiologic and clinical outcomes of patients who underwent total-hip arthroplasty (THA) with a CFP stem.The data of 325 hips from January 2015 to December 2016 were retrospectively reviewed. The demographic and radiologic data before and after surgery were obtained from patients. The neck-preserving ratio was defined as the ratio of the preserved femoral neck length to the preoperative femoral neck length. Correlations between the neck-preserving ratio and the radiologic and clinical outcomes of patients were analyzed.The mean neck-preserving ratio was 66.38 ± 6.91% in the current study. We divided patients into 3 groups according to the neck-preserving ratio: group A (neck-preserving ratio ≤60.00%), group B (60.00% < neck-preserving ratio < 70.00%), group C (neck-preserving ratio ≥70.00%). Radiologic features, including the neck-shaft angle ratio (0.96 ± 0.05), canal fill ratio (0.64 ± 0.07), anterior-posterior offset ratio (1.04 ± 0.10), and lateral offset ratio (2.55 ± 1.56) (ratios of the postoperative values to the preoperative values), and the prevalence of complications was significantly different among the groups (χ = 21.173, P < .001). In the correlation analysis, we found a moderate negative correlation between the neck-preserving ratio and neck-shaft angle ratio (r = -0.308, P < .001) and a slight positive correlation of the neck-preserving ratio with the anterior-posterior offset ratio (r = 0.415, P < .001) and the lateral offset ratio (r = 0.164, P = .003). In the linear regression analyses, the neck-preserving ratio was significantly linearly correlated with the neck-shaft angle ratio (B = -0.232, 95% confidence interval [CI] = -0.311 to -0.154, P < .001), anterior-posterior offset ratio (B = 0.589, 95% CI = 0.447-0.730, P < .001), and lateral offset ratio (B = 3.693, 95% CI = 1.256-6.131, P = .003). However, there was no significant linear correlation between the neck-preserving ratio and the canal fill ratio (B = 0.073, 95% CI = -0.033 to 0.180, P = .174). Logistic regression analyses also showed that a sufficient neck-preserving ratio was a protective factor for periprosthetic femoral fractures (odds ratio [OR] = 0.924, 95% CI = 0.859-0.994, P = .035), dislocations (OR = 0.892, 95% CI = 0.796-0.999, P = .048), and thigh pain (OR = 0.886, 95% CI = 0.818-0.960, P = .003).For CFP stems, an insufficient neck-preserving ratio is significantly correlated with poor radiologic and clinical outcomes. Therefore, surgeons should be cognizant to preserve a sufficient femoral neck length during surgery to improve the outcomes for patients undergoing THA with CFP stems.

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.

Medical resource utilization and costs for intraoperative and early postoperative periprosthetic hip fractures following total hip arthroplasty in the medicare population: A retrospective cohort study

This study assessed the impact of intraoperative and early postoperative periprosthetic hip fractures (PPHFx) after primary total hip arthroplasty (THA) on health care resource utilization and costs in the Medicare population.This retrospective observational cohort study used health care claims from the United States Centers for Medicare and Medicaid Standard Analytic File (100%) sample. Patients aged 65+ with primary THA between 2010 and 2016 were identified and divided into 3 groups - patients with intraoperative PPHFx, patients with postoperative PPHFx within 90 days of THA, and patients without PPHFx. A multi-level matching technique, using direct and propensity score matching was used. The proportion of patients admitted at least once to skilled nursing facility (SNF), inpatient rehabilitation facility (IRF), and readmission during the 0 to 90 or 0 to 365 day period after THA as well as the total all-cause payments during those periods were compared between patients in PPHFx groups and patients without PPHFx.After dual matching, a total 4460 patients for intraoperative and 2658 patients for postoperative PPHFx analyses were included. Utilization of any 90-day post-acute services was statistically significantly higher among patients in both PPHFx groups versus those without PPHFx: for intraoperative analysis, SNF (41.7% vs 30.8%), IRF (17.7% vs 10.1%), and readmissions (17.6% vs 11.5%); for postoperative analysis, SNF (64.5% vs 28.7%), IRF (22.6% vs 7.2%), and readmissions (92.8% vs 8.8%) (all P < .0001). The mean 90-day total all-cause payments were significantly higher in both intraoperative ($30,114 vs $21,229) and postoperative ($53,669 vs $ 19,817, P < .0001) PPHFx groups versus those without PPHFx. All trends were similar in the 365-day follow up.Patients with intraoperative and early postoperative PPHFx had statistically significantly higher resource utilization and payments than patients without PPHFx after primary THA. The differences observed during the 90-day follow up were continued over the 1-year period as well.

Femoral Stem Survivorship in Dorr Type A Femurs After Total Hip Arthroplasty Using a Cementless Tapered Wedge Stem: A Matched Comparative Study With Type B Femurs

BACKGROUND

There is a lack of understanding on relationship between the femoral geometry and outcomes of total hip arthroplasty (THA). We investigated clinical and radiographic outcomes of THA using a cementless tapered wedge stem in patients with Dorr type A proximal femoral morphology and compared with those of type B femurs at a minimum follow-up of 5 years.

METHODS

We analyzed 1089 hips (876 patients) that underwent THA using an identical cementless tapered wedge stem. We divided all femurs into 3 types (Dorr type A, B, and C). Type A and B femurs were statistically matched with age, gender, body mass index, and diagnosis by using propensity score matching. Clinical, radiographic results, and stem survivorship were compared between the matched 2 groups.

RESULTS

A total of 611 femurs (56%) were classified as type A, 427 (39%) as type B, and 51 (5%) as type C. More radiolucent lines around femoral stems were found in type A femurs (7.8%) than in type B femurs (2.5%) (P < .001). Patients with radiolucency showed worse Harris Hip Score (86.2 points) compared with those without radiolucency (93.0 points) (P < .001). The stem survivorship of type A femur (97.8%) was lower than that of type B femur (99.5%) (P = .041). The reasons for femoral revision in type A femurs were periprosthetic fracture (67%), aseptic loosening (22%), and deep infection (11%).

CONCLUSIONS

This study showed a higher rate of complications after THAs using a cementless tapered wedge stem in Dorr type A femurs than those performed in type B femurs.

Cumulative Long-Term Incidence of Postoperative Periprosthetic Femoral Fractures Using an Uncemented Tapered Titanium Hip Stem: 26- to 32-Year Results

BACKGROUND

Although falling is becoming a major problem in the elderly, little is known about the long-term incidence of postoperative periprosthetic femoral fractures (PFF) after total hip arthroplasty (THA) using uncemented stems with a minimum follow-up of 26 years postoperatively.

METHODS

In a consecutive series, the cumulative incidence of PFF after uncemented THA using a straight, collarless, tapered titanium stem was retrospectively reviewed in 354 hips (326 patients). After a mean follow-up of 28 (26-32) years postoperatively, 179 hips had died and 5 hips had been lost to follow-up. Kaplan-Meier survival analysis was used to estimate cumulative percentage probability of PFF.

RESULTS

At final follow-up, a total of 27 fractures in 27 patients had occurred. In 15 hips, the stem had to be revised, and in 10 the fracture was treated by open reduction and internal fixation. Two patients declined further surgery. The cumulative percentage probability of PFF was 1.6% (95% confidence interval, 0.7 to 3.8) at 10 years and 13.2% (95% confidence interval, 8.5 to 20.2) at 29 years after primary THA. There was no association between the occurrence of fracture and gender, age at primary THA, cup revision, or canal fill index.

CONCLUSION

Our findings indicate that PFF is the major mode of failure in the long term after uncemented THA using a tapered titanium stem. More research is needed to evaluate the reasons and risk factors for PFF after THA, thus providing better prophylaxis for those at risk and to compare the long-term incidence using different fixation methods and implants.

LEVEL OF EVIDENCE

IV.

Risk factors for post-operative periprosthetic fractures following primary total hip arthroplasty with a proximally coated double-tapered cementless femoral component

AIMS

The aim of this study was to identify patient- and surgery-related risk factors for sustaining an early periprosthetic fracture following primary total hip arthroplasty (THA) performed using a double-tapered cementless femoral component (Bi-Metric femoral stem; Biomet Inc., Warsaw, Indiana).

PATIENTS AND METHODS

A total of 1598 consecutive hips, in 1441 patients receiving primary THA between January 2010 and June 2015, were retrospectively identified. Level of pre-operative osteoarthritis, femoral Dorr type and cortical index were recorded. Varus/valgus placement of the stem and canal fill ratio were recorded post-operatively. Periprosthetic fractures were identified and classified according to the Vancouver classification. Regression analysis was performed to identify risk factors for early periprosthetic fracture.

RESULTS

The mean follow-up was 713 days (1 to 2058). A total of 48 periprosthetic fractures (3.0%) were identified during the follow-up and median time until fracture was 16 days, (interquartile range 10 to 31.5). Patients with femoral Dorr type C had a 5.2 times increased risk of post-operative periprosthetic fracture compared with type B, while female patients had a near significant two times increased risk over time for post-operative fracture.

CONCLUSION

Dorr type C is an independent risk factor for early periprosthetic fracture, following THA using a double tapered cementless stem such as the Bi-Metric. Surgeons should take bone morphology into consideration when planning for primary THA and consider using cemented femoral components in female patients with poor bone quality. Cite this article: Bone Joint J 2017;99-B:451-7.

Periprosthetic fractures: epidemiology and current treatment

Periprosthetic fractures are becoming increasingly frequent due to aging population and growing number of total joint replacements involving joints different from hip and knee, such as shoulder and elbow. The treatment of these fractures still represents one of the major challenges for the orthopedic surgeon. Despite all efforts to understand and treat these patients, high rate of failure and mortality are still reported. In this review, the epidemiology of periprosthetic fractures, risk factors and results of surgical treatment are disclosed. Moreover, we propose a treatment algorithm based on the findings of the New Unified Classification System.

Hip revision arthroplasty for failed osteosynthesis in periprosthetic Vancouver type B1 fractures using a cementless, modular, tapered revision stem

Aims

To evaluate the hypothesis that failed osteosynthesis of periprosthetic Vancouver type B1 fractures can be treated successfully with stem revision using a transfemoral approach and a cementless, modular, tapered revision stem with reproducible rates of fracture healing, stability of the revision stem, and clinically good results.

Patients and Methods

A total of 14 patients (11 women, three men) with a mean age of 72.4 years (65 to 90) undergoing revision hip arthroplasty after failed osteosynthesis of periprosthetic fractures of Vancouver type B1 were treated using a transfemoral approach to remove the well-fixed stem before insertion of a modular, fluted titanium stem which obtained distal fixation. These patients were clinically and radiologically followed up for a mean 52.2 months (24 to 144).

Results

After a mean of 15.5 weeks (standard deviation (sd) 5.7) all fractures had healed. No stems subsided and bony-ingrowth fixation had occurred according to the classification of Engh et al. The mean Harris Hip Score increased from a pre-operative score of 22.2 points (sd 9.7) to 81.5 points (sd 16.8) 24 months post-operatively. All hips had obtained an excellent result according to the classification of Beals and Tower.

Conclusions

The technique described here for stem revision provides reproducibly good results in the treatment of failed osteosynthesis for Vancouver types B1 periprosthetic fractures of the hip. Cite this article: Bone Joint J 2017;99-B(4 Supple B):11–16.