Predictors of Perioperative Vancouver B Periprosthetic Femoral Fractures Associated With the Direct Anterior Approach to Total Hip Arthroplasty

Perioperative periprosthetic femur fracture associated with direct anterior total hip arthroplasty using metaphyseal fit and fill stem

INTRODUCTION

This study aims to identify radiographic and clinical risk factors of perioperative periprosthetic femur fracture associated with the direct anterior approach (DAA) using a metaphyseal fit and fill stem. We hypothesize stem malalignment with this femoral implant places increased stress on the medial calcar region, which leads to an increased risk of periprosthetic fracture.

METHODS

We compared patients with periprosthetic femur fractures following DAA total hip arthroplasty (THA) utilizing the Echo Bi-Metric Microplasty Stem (Zimmer Biomet, Warsaw, IN) to a cohort of patients who did not sustain a periprosthetic fracture from five orthopedic surgeons over four years. Postoperative radiographs were evaluated for stem alignment, neck cut level, Dorr classification, and the presence of radiographic pannus. Univariate and logistic regression analyses were performed. Demographic and categorical variables were also analyzed.

RESULTS

Fourteen hips sustained femur fractures, including nine Vancouver B2 and five AG fractures. Valgus stem malalignment, proud stems, extended offset, and patients with enlarged radiographic pannus reached statistical significance for increased fracture risk. Low femoral neck cut showed a trend toward statistical significance.

CONCLUSION

Patients undergoing DAA THA using a metaphyseal fit and fill stem may be at increased risk of perioperative periprosthetic fracture when the femoral stem sits proudly in valgus malalignment with extended offset and when an enlarged pannus is seen radiographically. This study identifies a specific pattern in the Vancouver B2 fracture cohort with regard to injury mechanism, time of injury, and fracture pattern, which may be attributed to coronal malalignment of the implant.

Is the Direct Anterior Approach for Total Hip Arthroplasty Effective in Obese Patients? Early Clinical and Radiographic Results from a Retrospective Comparative Study

Background and objectives: Total hip arthroplasty (THA) in obese patients (BMI > 30) is considered technically demanding, and it is associated with higher rates of general and specific complications including infections, component malpositioning, dislocation, and periprosthetic fractures. Classically, the Direct Anterior Approach (DAA) has been considered less suitable for performing THA surgery in the obese patient, but recent evidence produced by high-volume DAA THA surgeons suggests that DAA is suitable and effective in obese patients. At the authors' institution, DAA is currently the preferred approach for primary and revision THA surgery, accounting for over 90% of hip surgeries without specific patient selection. Therefore, the aim of the current study is to evaluate any difference in early clinical outcomes, perioperative complications, and implant positioning after primary THAs performed via DAA in patients who were divided according to BMI. Material and methods: This study is a retrospective review of 293 THA implants in 277 patients that were performed via DAA from 1 January 2016 to 20 May 2020. Patients were further divided according to BMI: 96 patients were normal weight (NW), 115 were overweight (OW), and 82 were obese (OB). All the procedures were performed by three expert surgeons. The mean follow-up was 6 months. Patients' data, American Society of Anesthesiologists (ASA) score, surgical time, days in rehab unit, pain at the second post-operative day recorded by using a Numerical Rating Scale (NRS), and number of blood transfusions were recorded from clinical charts and compared. Radiological evaluation of cup inclination and stem alignment was conducted on post-operative radiographs; intra- and post-operative complications at latest follow-up were recorded. Results: The average age at surgery of OB patients was significantly lower compared to NW and OW patients. The ASA score was significantly higher in OB patients compared to NW patients. Surgical time was slightly but significantly higher in OB patients (85 ± 21 min) compared to NW (79 ± 20 min, p = 0.05) and OW patients (79 ± 20 min, p = 0.029). Rehab unit discharge occurred significantly later for OB patients, averaging 8 ± 2 days compared to NW patients (7 ± 2 days, p = 0.012) and OW patients (7 ± 2 days; p = 0.032). No differences in the rate of early infections, number of blood transfusions, NRS pain at the second post-operative day, and day of post-operative stair climbing were found among the three groups. Acetabular cup inclination and stem alignment were similar among the three groups. The perioperative complication rate was 2.3%; that is, perioperative complication occurred in 7 out of 293 patients, with a significantly higher incidence of surgical revisions required in obese patients compared to the others. In fact, OB patients showed a higher revision rate (4.87%) compared to other groups, with 1.04% for NW and 0% for OW (p = 0.028, Chi-square test). Causes for revision in obese patients were aseptic loosening (2), dislocation (1), and clinically significant post-operative leg length discrepancy (1), with a revision rate of 4/82 (4.87%) during follow-up. Conclusions: THA performed via DAA in obese patients could be a solid choice of treatment, given the relatively low rate of complications and the satisfying clinical outcomes. However, surgical expertise on DAA and adequate instrumentation for this approach are required to optimise the outcomes.

A smaller femoral stem is needed for asian females

BACKGROUND

Current femoral implants are manufactured based on Western anatomical structures and may be too large for smaller physiques, such as those of Asian females. This study reviewed the femoral stem size distribution used in a high-volume total hip arthroplasty (THA) practice and evaluated malalignment in patients receiving a size one implant.

MATERIALS AND METHODS

A consecutive cohort of female patients self-reported as Asian (257 patients, 331 hips) or Caucasian (158 patients and 190 hips) were retrospectively evaluated. A single femoral stem type was used in all cases, performed by a single surgeon. Global hip offset (GHO) and leg length difference (LLD) were measured before and 6 weeks following THA. Differences between races were evaluated through Mann-Whitney U tests and chi-squared tests for continuous and categorical variables, respectively.

RESULTS

The proportion of size one implants was higher amongst Asian patients (20.5%) than Caucasian patients (2.6%) (p < 0.001). A LLD greater than 6 mm was noted in 24.6% of size one patients and 11.4% of all other sizes (p = 0.010). Varus malalignment occurred in 47.9% of size one patients and 22.1% of all other sizes (p < 0.001). No fractures occurred in size one patients, and nine fractures (one intraoperative and eight post-operative) occurred in all other sizes (p = 0.258).

CONCLUSION

The high proportion of size one stems required in Asian females and the higher incidence of LLD > 6 mm and varus malalignment suggest a distinct need for smaller femoral implants, especially for Asian females.

Varus malalignment of short femoral stem not associated with post-hip arthroplasty fracture

INTRODUCTION

Periprosthetic femoral fractures are an increasingly common post-operative complication of total hip arthroplasty (THA). Though varus malalignment is known to increase fracture risk in standard-length femoral stems, varus malalignment is not as well studied in short stems. Therefore, the purpose of this study was to determine if varus malalignment contributes to early periprosthetic fracture risk in a cementless taper-wedged, short femoral stem.

MATERIALS AND METHODS

This retrospective review included 366 consecutive patients (441 THAs) having undergone THA via anterior approach by a single surgeon between July 2014 and December 2016. All patients received the same short, cementless femoral stem. Femoral component angle was measured on 6-week post-THA weight-bearing radiographs, with malalignment defined as a femoral component angle exceeding 0° ± 3°. Periprosthetic femoral fracture and aseptic loosening occurring within 2 years post-THA were recorded.

RESULTS

The final data analysis included 426 hips with a mean follow-up time of 32.9 ± 10.2 months. Varus and neutral alignment occurred in 84 (19.6%) and 342 (79.9%) of stems, respectively. Three (0.7%) periprosthetic femoral fractures occurred within 2 years, all occurring in patients with neutrally aligned femoral stems. One (0.2%) stem failed due to aseptic loosening and was malaligned.

CONCLUSION

Despite nearly 20% of stems placed in varus alignment, three of the four early complications occurred in a neutrally aligned stem. Based on these results, forceful intraoperative realignment of a short femoral stem with good initial fixation may present an unnecessary increased risk of intraoperative fracture.

Can We Predict Fracture When Using a Short Cementless Femoral Stem in the Anterior Approach?

BACKGROUND

Short cementless femoral stems may allow for easier insertion with less dissection. The use of short stems with the anterior approach (AA) may be associated with a considerable perioperative fracture risk. Our aim was to evaluate whether patient-specific femoral and pelvic morphology and surgical technique, influence the perioperative fracture risk. Furthermore, we sought to describe important anatomical thresholds alerting surgeons.

METHODS

A single-center, multi-surgeon retrospective, case-control matched study was performed. Thirty nine periprosthetic fractures (3.4%) in 1,145 primary AA THAs using short cementless stems were identified. These were matched with 78 THA nonfracture controls for factors known to increase the fracture risk. A radiographic analysis using validated software measured femoral (canal flare index [CFI], morphological cortical index [MCI], and calcar-calcar ratio [CCR]) and pelvic (Ilium-ischial ratio [IIR], ilium overhang, and anterior superior iliac spine [ASIS] to greater trochanter distance) morphologies and surgical techniques (% canal fill). A multivariate and Receiver-Operator Curve (ROC) analysis was used to identify fracture predictors.

RESULTS

CFI (3.7 ± 0.6 vs 2.9 ± 0.4, P < .001) and CCR (0.5 ± 0.1 vs 0.4 ± 0.1, P = .006) differed. The mean IIR was higher in fracture cases (3.3 ± 0.6 vs 3.0 ± 0.5, P < .001). Percent canal fill was reduced in fracture cases (82.8 ± 7.6 vs 86.7 ± 6.8, P = .007). Multivariate and ROC analyses revealed a threshold CFI of 3.17 which was predictive of fracture (sensitivity: 84.6%/specificity: 75.6%). The fracture risk was 29 times higher when patients had CFI >3.17 and II ratio >3 (OR: 29.2 95% CI: 9.5-89.9, P < .001).

CONCLUSION

Patient-specific anatomical parameters are important predictors of a fracture-risk. A careful radiographic analysis would help identify those at a risk of early fracture using short stems, and alternative stem options should be considered.

Clinical Outcomes and Survivorship of Hybrid Total Hip Arthroplasty Performed Through the Anterior Approach

INTRODUCTION

There is growing evidence that cemented femoral stems have lower complication rates in the elderly due to lower rates of periprosthetic fracture. The main objective of this study was to analyze the survival rate of a hybrid total hip arthroplasty (THA) construct utilizing a taper-slip femoral stem implanted through the anterior approach (AA). Secondary outcome measures were the complication rate, the rate of aseptic loosening, coronal plane alignment of the stem, and the grade of the cement mantle.

METHODS

Patients who underwent AA hybrid THA from 2013 to 2020 were included. Indications for a cemented stem were age over 70 or patients with poor bone quality. Descriptive statistics were calculated for patient characteristics. Serial radiographs were reviewed for component alignment and for evidence of implant loosening. The survival of the femoral stem was recorded, with failure defined as femoral stem revision for any reason or radiographic evidence of implant loosening.

RESULTS

A total of 473 hybrid THA in 426 patients were identified, with a mean age of 76 years. Mean follow-up was 38 months. Femoral stem survival was 99.2%. There were no cases of aseptic loosening of the femoral component. Mean coronal stem alignment was 0.2 degrees varus, and all were within 5 degrees of neutral. Cement mantle grade was either A or B in 94% of cases.

CONCLUSION

AA hybrid THA is an excellent option in elderly patients, or patients with poor bone quality, with a femoral stem survival rate of 99.2% and a 0% rate of aseptic loosening.

The influence of calcar collar and surface finish in the cemented femoral component on the incidence of postoperative periprosthetic femoral fracture at a minimum of five years after primary total hip arthroplasty

INTRODUCTION

Cemented femoral component design including its mechanical behavior in total hip arthroplasty (THA) has influenced the occurrence of postoperative periprosthetic femoral fracture (PPFF). The main aim of this study was to investigate the influence of the calcar collar and surface finish in the cemented femoral component on the risk of PPFF.

MATERIALS AND METHODS

This retrospective review was undertaken of 1082 primary THAs in 912 patients using cemented femoral components followed for a minimum of five years (mean, 9.4 years; range, 5-24 years). The incidence of PPFF, patients' demographics and surgical details were evaluated. Kaplan-Meier survivorship analysis was performed for four different outcomes: any PPFF, revision of the femoral component for PPFF, aseptic loosening, and for any reason.

RESULTS

The overall incidence of PPFFs was 1.0% (n = 11): 1.4% (n = 10) in the collarless polished (CLP) group, none in the collared polished (CP) group and 0.6% (n = 1) in the collared non-polished (CNP) group (p > 0.05). Kaplan-Meier survival analysis for the femoral component at 12 years with PPFF as the end point was 97.4% (95% confidence interval [CI], 94.9 to 99.8) in the collarless group and 99.7% (95% CI, 99.1 to 100) in the collared group (p = 0.048). With revision of the femoral component for aseptic loosening as the end point, survivorship was 100.0% in the CLP and CP groups, and 98.1% (95% CI, 95.9 to 100) in the CNP group (CLP vs CP, p > 0.999; CLP vs CNP, p = 0.001; CP vs CNP, p = 0.112).

CONCLUSION

This study demonstrated that the calcar collar in the cemented femoral component could play an important role to reduce the incidence of PPFF. The surface finish in the cemented femoral components influenced the incidence of femoral component revision for aseptic loosening over 5-12 years. Surgeons should consider not only the geometry and the mechanical function of the femoral components based on different design philosophies, but also potential complications associated with different designs that may require revision arthroplasty.

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.

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.