A new angle and its relationship with early fixation failure of femoral neck fractures treated with three cannulated compression screws

Morphological characteristics of femoral neck fractures in young and middle-aged population: a retrospective descriptive study

BACKGROUND

A understanding of morphological characteristics are important to femoral neck fractures (FNFs) resulting in high rates of complications in the young and middle-aged adults and the detailed data is lack in the literature. We aimed to report on the detailed morphological characteristics and the relationship between them in young and middle-aged adults with femoral neck fractures (FNFs).

METHODS

The postoperative CT images of one hundred and fifty-two adults with FNFs were retrospectively reviewed. After image standardization, morphological characteristics including fracture orientation, cortex comminution, and intraosseous bone defects were measured and analyzed. Additionally, the distribution and correlation of these morphological features were analyzed using Pauwels classification, the right angle of the neck axis (VNA) classification, and the anteromedial oblique angle (AMA).

RESULTS

Pauwels III fractures accounted for approximately half (55.2%) of the FNFs analyzed. Pauwels II and III could be detected in all four VNA types, and the distribution of the Pauwels types in VNA classification showed significant differences (χ2 = 106.363, p < 0.001). The VNA (9.0° ± 12.1) showed positive correlation with the neck-shaft angle (139.5° ± 6.3) and modified Pauwels angle (49.8° ± 10.6) (r = 0.441, r = 0.855, all p < 0.001). Cortical comminutions were commonly observed in the posterior (86.7%) and the inferior (80.7%). AMAs within the cases without posterior and inferior cortex comminutions were significantly larger than those with comminution (t = 2.594, 2.1196; p = 0.01, 0.036), but no difference could be detected after the AMA being divided into three groups (< 85°, 85°-95°, > 95°). The MPA, VNA and AMA of the group with an intraosseous defect were significantly different compared with those without (t = 2.847, 2.314, 2.268; p = 0.005, 0.022,0.025). The incidence of intraosseous defects within the groups with coronal and axial cortex comminutions were significantly higher than those within the groups without comminutions (χ2 = 34.87, 25.303; p < 0.001).

CONCLUSIONS

The present study highlights the morphological diversity and complexity within FNFs in young and middle-aged adults, which allows for more accurate simulation of FNF patterns in the future biomechanical studies.

Compressive buttress compared with off-axial screw fixation for vertical femoral neck fractures in young adults: a prospective, randomized controlled trial

BACKGROUND

To compare the clinical outcomes of compressive buttress screw (CBS) fixation, a novel screw fixation strategy, to off-axial screw fixation (off-axial partial threaded cannulated screw, OPTCS) for vertical femoral neck fractures (FNFs) in young adults.

METHODS

A total of 146 adults younger than 55 years old with high-energy Pauwels type III FNFs were randomized to receive CBS fixation or OPTCS fixation. Primary outcomes were complication rates, including fixation failure, fracture nonunion, and avascular necrosis of the femoral head (ANFH) at 24 months after treatment. Fixation loosening, femoral neck shortening and varus collapse, patient function and quality of life using the Harris hip score (HHS), and EuroQol-5 dimensional-5 levels (EQ-5D-5L) questionnaire (including EQ-5D-5L and EQ-VAS) were assessed as secondary outcomes at 24 months.

RESULTS

CBS and OPTCS fixation groups were similar with regard to demographics at baseline. At 24 months, patients in the CBS fixation cohort had a significantly lower rate of fixation failure (10.5% vs. 25.0%, p = 0.041) and fracture nonunion (1.8% vs. 18.3%, p = 0.003) compared with patients who received OPTCS fixation. There was no difference in rate of ANFH (7.0% vs. 11.7%, p = 0.389) between groups. Additionally, patients managed with CBS fixation showed significantly less fixation loosening (19.3% vs. 58.3%, p < 0.001), less severe femoral neck shortening and varus collapse (10.5% vs. 25.0%, p = 0.007), higher HHS (93 vs. 83, p = 0.001) and more excellent grade (68.4% vs. 36.7%, p = 0.008), higher EQ-5D-5L (0.814 vs, 0.581, p < 0.001) and EQ-VAS (85 vs. 80, p = 0.002).

CONCLUSION

CBS screw fixation confers significantly lower complication rate in addition to higher functional and quality of life outcomes for young adults with high-energy FNF compared with OPTCS fixation.

TRIAL REGISTRATION

This prospective, randomized controlled trial was approved by the institutional review board of our center, Ethics Committee of Shanghai sixth people's Hospital, and registered at www.chictr.org.cn (Approval Number: ChiCTR1900026283; Registered 29 September 2019-Retrospectively registered, https://www.chictr.org.cn/showproj.html?proj=43164 ).

Factors associated with early failure of the femoral neck system (FNS) in patients with femoral neck fractures

BACKGROUND

Femoral neck system (FNS) is a new type of internal fixation system which has been widely used for treating femoral neck fractures (FNFs).Compared with other internal fixation methods, FNS is minimally invasive and stable, and often achieves satisfactory short-term efficacy.Early failure of FNS (EFFNS) is not uncommon, however, there are few literatures and reports on factors associated with EFFNS.This study aimed to survey the prevalence and risk factors of EFFNS.

METHODS

We retrospectively analysed 62 patients with FNFs and underwent FNS fixation between 2019 and 2021. Demographic data, clinical characteristics, radiographic features and treatment process were described. Multifactor logistic regression analysis was used to analyse the different influencing factors.

RESULTS

Out of the 62 FNFs patients, 10 patients (16.1%) developed EFFNS, including 6 cases of severe femoral neck shortening, 2 cases of screw-out, 1 case of avascular necrosis of the femoral head and 1 case of nonunion. In the failure group, all patients were younger than 65 years old, which was significantly higher than 59.6% in the healing group (P = 0.012). There were no significant differences in sex(P = 0.490), BMI (P = 0.709), injured side (P = 0.312), injury mechanism (P = 0.617), reduction method(P = 0.570),femoral neck-shaft angle(P = 0.545), Pauwels classification (P = 0.564) and Garden classification (P = 0.195). Moreover, we not found that Garden classification (P = 0.464) and age (P = 0.128) were statistically significant risk factors for EFFNS at multivariate analysis.

CONCLUSION

In this study, sex, BMI, injury side, injury mechanism, reduction method, Pauwels angle, femoral neck-shift angle, Pauwels classification and Garden classification were excluded as EFFNS risk factors. Moreover, our study demonstrated that age and Garden classification were not significant risk factors at multivariate analysis.

TRIAL REGISTRATION

ChiCTR, ChiCTR2100051360. Registered on 21 September, 2021. https://www.chictr.org.cn/index.aspx .

Complications and associated risk factors after surgical management of proximal femoral fractures

Aims

This work aimed at answering the following research questions: 1) What is the rate of mechanical complications, nonunion and infection for head/neck femoral fractures, intertrochanteric fractures, and subtrochanteric fractures in the elderly USA population? and 2) Which factors influence adverse outcomes?

Methods

Proximal femoral fractures occurred between 1 January 2009 and 31 December 2019 were identified from the Medicare Physician Service Records Data Base. The Kaplan-Meier method with Fine and Gray sub-distribution adaptation was used to determine rates for nonunion, infection, and mechanical complications. Semiparametric Cox regression model was applied incorporating 23 measures as covariates to identify risk factors.

Results

Union failure occured in 0.89% (95% confidence interval (CI) 0.83 to 0.95) after head/neck fracturs, in 0.92% (95% CI 0.84 to 1.01) after intertrochanteric fracture and in 1.99% (95% CI 1.69 to 2.33) after subtrochanteric fractures within 24 months. A fracture-related infection was more likely to occur after subtrochanteric fractures than after head/neck fractures (1.64% vs 1.59%, hazard ratio (HR) 1.01 (95% CI 0.87 to 1.17); p < 0.001) as well as after intertrochanteric fractures (1.64% vs 1.13%, HR 1.31 (95% CI 1.12 to 1.52); p < 0.001). Anticoagulant use, cerebrovascular disease, a concomitant fracture, diabetes mellitus, hypertension, obesity, open fracture, and rheumatoid disease was identified as risk factors. Mechanical complications after 24 months were most common after head/neck fractures with 3.52% (95% CI 3.41 to 3.64; currently at risk: 48,282).

Conclusion

The determination of complication rates for each fracture type can be useful for informed patient-clinician communication. Risk factors for complications could be identified for distinct proximal femur fractures in elderly patients, which are accessible for therapeutical treatment in the management.

Reliability of Modified Pauwels Angle in Preoperative Plain X-ray and Intraoperative Fluoroscope in Young Femoral Neck Fracture Fixation

Purpose

This research aims to evaluate the reliability of modified Pauwels angle in preoperative plain X-ray and intraoperative fluoroscope.

Method

This study included 48 male and 18 female patients with an average age of 36.95 years. Seven observers contributed to this study by measuring the modified Pauwels types and angles on 66 anterior-posterior (AP) views from preoperative radiographs and intraoperative fluorography. Intra-observer and inter-observer reliability was calculated using Fleiss's kappa and intraclass correlation coefficient (ICC).

Results

The results showed that the intra-observer reliability for the modified Pauwels type using Kappa coefficient in preoperative and intraoperative assessments was 0.584 and 0.823, respectively. The inter-observer reliability for preoperative and intraoperative evaluations was 0.467 and 0.753 for all observers, 0.647 and 0.783 for specialized trauma orthopedists, and 0.41 and 0.752 for the residents. The modified Pauwels angle assessment in intra-observers using ICC was 0.804 preoperatively and 0.943 intraoperatively. The inter-observer for preoperative and intraoperative assessments was 0.675 and 0.834 for all observers, 0.977 and 0.982 for specialized trauma orthopedists, and 0.622 and 0.823 for residents. The difference between preoperative and intraoperative modified Pauwels angles was 9.75 ± 6.76 (p < 0.05). Eleven patients had their modified Pauwels type changed, which altered the implant selection in 8 patients.

Conclusion

The modified Pauwels angle together with type assessment has excellent reliability for implant selection when implemented intraoperatively, and at least two specialized trauma orthopedists should evaluate the fracture lines.

Prediction Model of Osteonecrosis of the Femoral Head After Femoral Neck Fracture: Machine Learning-Based Development and Validation Study

BACKGROUND

The absolute number of femoral neck fractures (FNFs) is increasing; however, the prediction of traumatic femoral head necrosis remains difficult. Machine learning algorithms have the potential to be superior to traditional prediction methods for the prediction of traumatic femoral head necrosis.

OBJECTIVE

The aim of this study is to use machine learning to construct a model for the analysis of risk factors and prediction of osteonecrosis of the femoral head (ONFH) in patients with FNF after internal fixation.

METHODS

We retrospectively collected preoperative, intraoperative, and postoperative clinical data of patients with FNF in 4 hospitals in Shanghai and followed up the patients for more than 2.5 years. A total of 259 patients with 43 variables were included in the study. The data were randomly divided into a training set (181/259, 69.8%) and a validation set (78/259, 30.1%). External data (n=376) were obtained from a retrospective cohort study of patients with FNF in 3 other hospitals. Least absolute shrinkage and selection operator regression and the support vector machine algorithm were used for variable selection. Logistic regression, random forest, support vector machine, and eXtreme Gradient Boosting (XGBoost) were used to develop the model on the training set. The validation set was used to tune the model hyperparameters to determine the final prediction model, and the external data were used to compare and evaluate the model performance. We compared the accuracy, discrimination, and calibration of the models to identify the best machine learning algorithm for predicting ONFH. Shapley additive explanations and local interpretable model-agnostic explanations were used to determine the interpretability of the black box model.

RESULTS

A total of 11 variables were selected for the models. The XGBoost model performed best on the validation set and external data. The accuracy, sensitivity, and area under the receiver operating characteristic curve of the model on the validation set were 0.987, 0.929, and 0.992, respectively. The accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve of the model on the external data were 0.907, 0.807, 0.935, and 0.933, respectively, and the log-loss was 0.279. The calibration curve demonstrated good agreement between the predicted probability and actual risk. The interpretability of the features and individual predictions were realized using the Shapley additive explanations and local interpretable model-agnostic explanations algorithms. In addition, the XGBoost model was translated into a self-made web-based risk calculator to estimate an individual's probability of ONFH.

CONCLUSIONS

Machine learning performs well in predicting ONFH after internal fixation of FNF. The 6-variable XGBoost model predicted the risk of ONFH well and had good generalization ability on the external data, which can be used for the clinical prediction of ONFH after internal fixation of FNF.

Osteosynthesis of non-displaced femoral neck fractures in the elderly population using the femoral neck system (FNS): short-term clinical and radiological outcomes

Background

Femoral neck fractures (FNF) are frequent in the elderly population, and surgical management is indicated in the vast majority of cases. Osteosynthesis is an alternative to arthroplasty for non-displaced FNF. Triple screw construct (TS) and the dynamic hip screw system (DHS) are considered gold standards for osteosynthesis. The newly available femoral neck system (FNS) currently lacks evidence as to whether it is a valid alternative to TS and DHS. The purpose of this study was to evaluate the short-term clinical and radiological outcomes after non-displaced (Garden I and II) FNF osteosynthesis using TS, DHS, and FNS.

Methods

All the patients of the author’s institution aged ≥ 75 years with a non-displaced (Garden I and II) FNF eligible for osteosynthesis between November 2015 and December 2019 were included in this single-center retrospective non-randomized study. Patients were treated with either TS, DHS, or FNS depending on the surgeon’s preference. Clinical data (age, gender, ASA score, duration of surgery, need for blood transfusion and number of packed red blood cells transfused, surgical site complications, length of stay, discharge location, postoperative medical complications and readmission within 30 days, and mortality within 3 months) were extracted from the patients’ charts. The radiological analysis assessed the fracture classification, fracture impaction, and proximal femur shortening at 3 and 6 months using the institutional imaging software.

Results

Baseline characteristics in the TS (n = 32), DHS (n = 16), and FNS (n = 15) groups were similar with respect to age (mean 85 years), gender (female to male ratio 4:1), and ASA score. There were no significant differences across the groups for the need for blood transfusion, surgical site complications, length of stay, postoperative medical complications and readmission within 30 days, discharge location, and mortality within 3 months. The duration of surgery was significantly lower in the FNS group (43.3 vs 68.8 min; p < 0.001). The radiological assessment found similar impaction (5.2 mm ± 4.8) and shortening (8.6 mm ± 8.2) in all groups that did not seem to progress after 3 months.

Conclusion

The FNS appears to be a valid alternative implant for FNF osteosynthesis and is associated with a shorter operative time than TS and DHS. Short-term clinical and radiological outcomes of FNS are similar to TS and DHS implants. Further long-term multicenter randomized studies are however necessary to confirm these first results.

Decreased complications but a distinctive fixation loosening mechanism of fully threaded headless cannulated screw fixation for femoral neck fractures in young adults

BACKGROUND

Despite being a commonly encountered injury in orthopedic practice, controversy surrounds the methods of optimal internal fixation for femoral neck fractures (FNF) in young patients. The objective of the present study is to compare complication rates and failure mechanisms for surgical fixation of FNF using fully threaded headless cannulated screws (FTHCS) versus partial threaded cannulated screws (PTS) in young adults.

METHODS

A total of 75 patients (18-65 years old) with FNF were prospectively treated with close reduction and internal fixation using three parallel FTHCS and compared to a historical control case-matched group (75 patients) with FNF treated by PTS fixation. After 2 years follow-up, rates of fixation failure (including varus collapse, fracture displacement, and femoral neck shortening), nonunion, and avascular necrosis of the femoral head (ANFH) were compared between the two cohorts. The demographic, follow-up information, and radiological images were assessed by independent blinded investigators.

RESULTS

Patient demographics and fracture patterns were similar in the two patient groups. The overall fixation failure rates were 8% (6/75) in the FTHCS cohort, which was significantly lower than the 25.3% (19/75) seen in the PTS group. Rates of nonunion and ANFH were significantly lower in the FTHCS group when compared to the PTS control group. When stratified by injury severity (high-energy vs. low-energy fractures), the rate of fixation failure was significant lower with the use of FTHCS when compared with PTS for high-energy fractures while there was no difference in the rates of nonunion or ANFH for high or low-energy fracture patterns. Unique to the FTHCS cohort was an atypical screw migration pattern with varus collapse (6/75, 8%).

CONCLUSIONS

The results show that FTHCS fixation could significantly reduce the complication rate of young patients with FNF, especially in high-energy fracture patterns (Garden III-IV, Pauwels III, or vertical of the neck axis (VN) angle ≥ 15°). There was also confirmation that the modes of fixation loosening in the FTCHS group, including screw "medial migration" and superior cutout, were different from the screw withdrawal pattern seen in the PTS cohort.

TRIAL REGISTRATION

The study was retrospectively registered at www.Chictr.org.cn ( ChiCTR-IPR-1900025851 ) on September 11, 2019.

A Study on the Evaluation of a Risk Score of Osteonecrosis of the Femoral Head Based on Survival Analysis

BACKGROUND

This study aimed at developing a risk score predicting the probability of developing an osteonecrosis of the femoral head (ONFH) in patients with femoral neck fracture within 3 years after closed reduction internal fixation and evaluating its performance, clinical utility, and internal validity.

METHODS

A retrospective follow-up study of 378 newly injured femoral neck fracture patients treated with 3 partially threaded parallel cannulated screws in 3 hospitals in Shanghai from March 2013 to January 2017 was performed. The patients were divided into development (n = 284) and validation (n = 94) cohorts. The risk score was constructed by Cox regression analysis in a form of nomogram. The performance and clinical utility were illustrated by box plots, calibration plots, and decision curve analysis.

RESULTS

Eighty-three of 378 patients had developed ONFH within 3 years. Garden alignment index, time to surgery, preoperative displace, impaction, and postoperative malposition were used as predictors to construct the risk score in a form of nomogram. In the development and validation cohort, the concordance index was 0.96 and 0.94, respectively; the discrimination slope was 0.51 and 0.47, respectively. In both cohorts, the calibration slopes and intercepts were 1 and 0, respectively. The risk score was clinically useful between the risk threshold of 0% and 88%. The performance and utility in the validation data illustrated good repeatability.

CONCLUSION

The risk score had satisfactory discrimination and calibration performance and demonstrated clinical utility with good internal validity. It managed to distinguish high-risk groups for post-traumatic ONFH.

Comparison of Ordinary Cannulated Compression Screw and Double-Head Cannulated Compression Screw Fixation in Vertical Femoral Neck Fractures

Background

The treatment of vertical femoral neck fractures in young patients remains a challenge. This study is aimed at comparing ordinary cannulated compression screw (OCCS) and double-head cannulated compression screw (DhCCS) fixation in vertical femoral neck fractures both clinically and biomechanically.

Materials and Methods

Clinically, the radiographs of 81 patients with Pauwel's III femoral neck fractures, including 54 fractures fixed with three parallel OCCSs and 27 fractures fixed with three parallel DhCCSs, were reviewed retrospectively. Complications consisting of fixation failure (screw loosening, obvious fracture displacement, varus deformity, or femoral neck shortening), bony nonunion, and avascular necrosis (AVN) were determined. Biomechanically, twenty synthetic femur models of vertical femoral fractures with an 80° Pauwel's angle were divided into two groups and subsequently fixed with three parallel OCCSs or DhCCSs. All specimens were tested for axial stiffness, load to 5 mm displacement, and a maximum load to failure with a loading rate of 2 mm/min.

Results

Clinically, 22 fractures in the OCCS group experienced fixation failure, including 19 screw loosening, 18 femoral neck shortening, 14 varus deformities, and 8 obvious fracture displacements, whereas only 4 fractures experienced fixation failure in the DhCCS group, including 3 screw loosening, 3 femoral neck shortening, 3 varus deformities, and 1 obvious fracture displacement. Additionally, 11 fractures in the OCCS group exhibited nonunion, whereas only 3 in the DhCCS group exhibited nonunion. Nine fractures with AVN were noted in the OCCS group, whereas only 1 was observed in the DhCCS group. Biomechanically, the axial stiffness of the DhCCS group was greater than that of the OCCS group (154.9 ± 6.81 vs. 128.1 ± 7.41 N/mm), and the load to 5 mm displacement was also significantly greater in the DhCCS group (646.1 ± 25.87 vs. 475.8 ± 21.46 N). Moreover, the maximum load to failure in the DhCCS group exhibited significant advantages compared with that of the OCCS group (1148 ± 39.47 vs. 795.9 ± 51.39 N).

Conclusion

Our results suggested that using three DhCCSs improved the outcome of vertical femoral neck fractures compared to three OCCSs, offering a new choice for the treatment of femoral neck fracture.

Eliminating projection error of measuring Pauwels' angle in the femur neck fractures by CT plane manipulation

OBJECTIVES

The aim for the present study was to determine whether projection error of measuring Pauwels' angle in young femur neck fracture could be eliminated by CT plane manipulation.

METHODS

Clinical data of displaced femur neck fractures in young adults aged 20 to 64years old (13 females and 17 males) were retrospectively analyzed. Their average age was 47.9years (range: 22-64years; SD: 11.3). Using modified measurement method for Pauwels' angle using central line of the shaft as a guideline, the angle of a conventional coronal CT image was measured. CT images were imported into Mimics® software. The scanning plane was then reformatted parallel to the neck axis to eliminate projection error of injured limb. Measured angles were classified into three types (I<30°; II, 30-50°; and III>50°) and differences were analyzed.

RESULTS

Average Pauwels' angle was 52.9° (range: 28.6-68.3°; SD: 9.9; type II, 17 cases; type III, 13 cases) for conventional CT images and 68.7° (range: 29.8-91.2°; SD: 13.4; type II, 1 cases; type III, 29 cases) for reformatted CT images. Difference between these two measurements on average was 15.7° (range: 1.2-34.9°; SD: 7.3).

CONCLUSIONS

Reformatting CT scanning plane by manipulating the proximal fragment to be parallel with the neck axis of the distal neck-shaft fragment is a convenient and reliable technique for eliminating the projection error of measuring Pauwels' angle in the femur neck fractures.

LEVEL OF EVIDENCE

IV, cohort study.

Poor results of functional treatment of Garden-1 femoral neck fracture in dependent patients

INTRODUCTION

Variable results are reported after functional treatment for Garden-1 femoral neck fracture, with no definite factors for failure, particularly in the absence of selection for risk. It seems well indicated in frail and/or dependent patients with comorbidities, but this has not been specifically assessed, and failure is frequent in this target population. We therefore performed a retrospective study to: (1) assess results of functional treatment for Garden-1 impacted femoral neck fracture in dependent patients, and (2) analyze survival in terms of complications and death, and related factors.

HYPOTHESIS

Functional treatment for Garden-1 fracture in dependent patients gives poor results, with a high rate of surgical revision.

MATERIAL AND METHODS

A retrospective analysis was made of Garden-1 femoral neck fracture in dependent patients (Parker score≤5), with a minimum 2 years' follow-up. One hundred and forty-six patients were included: mean age, 81.3±8.7 years (range, 55.7-99.6 years). The endpoint was survival in terms of complications requiring surgery, secondary displacement requiring surgery, excessive pain requiring surgery, non-union or femoral head osteonecrosis. Secondary endpoints were overall mortality and mortality related to complications.

RESULTS

Mean follow-up was 4.2±2.6 years (range, 2.0-10.3 years). Ninety-one of the 146 patients (62.3%) required secondary surgery: 79 (54.1%) early (<3 months post-fracture), with 77 (52.7%) secondary displacements and 2 cases (1.4%) of excessive pain; and 12 (8.2%) late (162.2±132.3 days; range, 90-454 days), with 8 (5.4%) non-unions and 4 (2.7%) osteonecroses. Mean time to onset of secondary displacement was 13.6±11.8 days (range, 0-67.0 days). Two-year survival in terms of revision surgery was 34.1% [95% CI: 26.0-42.4]. At last follow-up, 91 patients (62.3%) had died; 2-year survival in terms of death was 69.9% [95% CI: 62.4-77.3]. Survival analysis in terms of complications revealed greater mortality in absence of complications: 42 of the 55 patients (76.3%) without complications requiring surgery died, versus 49 of the 91 (53.8%) with complications requiring surgery (p=0.012); relative risk of death in absence of complications requiring surgery was 1.42 [95% CI: 1.33-5.77].

DISCUSSION

Functional treatment for Garden-1 fracture in dependent patients gave poor short- and medium-term results. Surgery is therefore recommended in this specific population; the present findings should improve survival.

LEVEL OF EVIDENCE

IV, retrospective study.

Three-dimensional morphological analysis of the femoral neck torsion angle-an anatomical study

Background

The femoral neck torsion angle (FNTA) is an important but often neglected parameter in assessments of the anatomical morphology of the femoral neck, which is often confused with the femoral neck anteversion angle (FNAA) in the current literature. Currently, the measurement methods reported in the literature all adopt the naked eye or two-dimensional (2D) visualization method, and the measurement parameters and details are not clearly defined. The objection of this research was to provide a reliable 3D method for determining the femoral neck axis, to improve the measurement method of the FNTA, and to analyze the anatomical and clinical significance of the results.

Methods

Computed tomography (CT) data of 200 patients who received a lower extremity CT angiography examination were selected, and the bilateral femurs were reconstructed with three dimensional CT (3D CT). First, the 3D axis of the femoral neck was built. Second, the long axis of the cross section the femoral neck isthmus (FNI) and femoral neck basilar part (FNB) were confirmed by the “inertia axes” method, and the plane consisting of the long axis of the cross-section and the center of the femoral head was defined as the long axial plane. Third, the coronal plane of the proximal femur was determined through the long axis of the proximal femur and the femoral coronal. Finally, the FNTAs (the angles between the long axial planes and the coronal plane of the proximal femur) of FNI and FNB were measured. The size of FNTA was compared between the sexes and sides and different locations, the correlation between the parameters and age, height, and weight were evaluated.

Results

The difference in FNTA was statistically significant between the isthmus and the basilar part (isthmus 30.58 ± 8.90° vs. basilar part 23.79 ± 3.98°; p < 0.01). Significant difference in the FNTA was observed between the sexes (males 31.99 ± 9.25° vs. females 27.49 ± 7.19°; p < 0.01). The increase in FNTA from the basilar part to the isthmus was 6.79 ± 8.06°, and the male (7.87 ± 8.57°) was greater than the female (4.44 ± 6.23°, p < 0.01). However, no significant difference in the values was observed between sides. Height exerted the greatest effect on the FNTA according to the correlation analysis (r = 0.255, p< 0.001).

Conclusions

This study found a reliable 3D method for the determination of the femoral neck axis improved the measurement method of the FTNTA and made it more accurate and repeatable. The results provided a methodological basis and theoretical support for the research and development of internal fixation device for femoral neck fracture and the spatial configuration of implants in treatment. And the optimal opening point of the femoral medullary cavity was recommended to locate at the posterior position of the top of the femoral neck cross-section during hip replacement.

Early mechanical complications following fixation of proximal femur fractures: From prevention to treatment

Proximal femur fractures have significant functional repercussions in both older adults (sometimes life-threatening) and younger adults (socioeconomic). This study will review the early mechanical complications (EMC) associated with the fixation of femoral neck (FNF) and trochanteric (TF) fractures. What is the nature of these complications? They consist of incorrect fracture fixation, secondary displacement and/or fixation failure (FNF: 3-10%; TF: 5-7%), and more rarely, secondary fractures distal to the implant. What are the risk factors and how can they be controlled? They are related to the patient (osteoporosis), to the type of fracture (FNF: posterior comminution, magnitude of displacement, vertical fracture line, fracture of calcar/TF: comminution of calcar, lesser trochanter fracture, metaphyseal comminution, lateral cortex fracture, greater trochanter comminution), to the chosen treatment (FNF: triple screw fixation or screw-plate are preferable/TF: all implants suitable for simple fractures, cervicomedullary implants for complex fractures), and to the surgical technique (quality of reduction, implant positioning). How should they be treated? Early revision of internal fixation can be difficult and increases the infection risk. Inter- or subtrochanteric valgus osteotomy leads to satisfactory results but is difficult to carry out. Secondary arthroplasty, which is the preferred option in older adults, leads to good outcomes but is technically more difficult, and has a higher complication rate in EMC of trochanteric fractures. LEVEL OF EVIDENCE: V.

Femoral neck shortening after internal fixation of Garden I fractures increases the risk of femoral head collapse

BACKGROUND

Arthroplasty has not been proven superior over internal fixation for the treatment of non-displaced femoral neck fractures. However, internal fixation has been followed by high rates of revision for mechanical complications and of femoral neck impaction within the first postoperative year. The objective of this study was to determine whether femoral neck impaction was associated with avascular necrosis (AVN).

HYPOTHESIS

Fracture healing with femoral neck shortening by impaction after internal fixation of a femoral neck fracture is associated with AVN.

MATERIAL AND METHODS

A single-centre retrospective study in patients with Garden I fractures managed by screw fixation was performed to compare outcomes in the groups with and without femoral neck impaction. Follow-up radiographs were assessed for evidence of the femoral neck impaction during fracture healing. The occurrence of AVN was the primary evaluation criterion. The secondary evaluation criteria were risk factors for impaction and complications.

RESULTS

Of the 75 included patients, 9 (12%) experienced AVN. Impaction was significantly associated with AVN (p=0.02; relative risk, 4.38). Significant risk factors for impaction were a higher body mass index (p=0.0003) and valgus-impacted fracture reduction between the radiographs at baseline and immediately after surgery (p=0.0001).

DISCUSSION

Femoral neck impaction was a significant risk factor for AVN after screw fixation of Garden I fractures. Valgus-impacted fracture reduction must receive careful attention during fixation. We suggest static internal fixation if the impaction is reduced on a traction table and advise caution when using parallel screws. The diagnostic and therapeutic strategy proposed here deserves to be evaluated in a prospective study.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Non-operative treatment is a reliable option in over two thirds of patients with Garden I hip fractures. Rates and risk factors for failure in 298 patients

BACKGROUND

Non-operative treatment for impacted femoral neck fractures is a now rarely used strategy whose indications are controversial. No outcome predictors have been convincingly identified, in part due to the small sizes of available studies. We conducted a large retrospective study with the following objectives: (1) to evaluate the percentage of patients older than 65 years of age with non-operatively treated Garden I femoral neck fractures who experience secondary displacement, (2) to identify predictors of secondary displacement, and (3) to determine the frequency of non-operative treatment failure due to any cause and requiring joint replacement surgery.

HYPOTHESIS

Non-operative treatment is reliable in patients older than 65 years of age with Garden I femoral neck fractures.

MATERIAL AND METHODS

Approval was obtained from the French data protection authority to conduct a retrospective observational study of information in the Marseille university hospitals database. Consecutive patients who were older than 65 years of age at traumatology department admission for Garden I femoral neck fractures managed non-operatively between January 2007 and December 2017 were included. Non-operative treatment consisted in a walking test on day 1 followed by radiographs on days 2, 7, 14, 21, and 45 and after 3 and 12 months. Patients with secondary displacement underwent hip arthroplasty. Demographic data, cognitive performance, and radiological parameters were collected for each patient. We evaluated the rates of secondary displacement avascular necrosis, and non-union.

RESULTS

We included 298 patients with a mean age of 82 years (range, 65-101). Mean follow-up was 5±3 years. Secondary displacement occurred in 91 (30%) patients, at a mean of 16 days (range 2-45 days) after the fracture. Avascular necrosis of the femoral head developed in 13 (4.3%) patients and non-union in 11 (3.7%) patients. Secondary displacement was significantly associated with hypnotic treatment (OR, 4.1; 95%CI, 2.2-7.5; p=0.039), institutionalisation (OR, 6.7; 95%CI, 3.1-14.8; p=0.028), a history of repeated falls (OR, 13.5; 95%CI, 6.3-8.4; p<0.0001), having three or more comorbidities (OR, 3.2; 95%CI, 1.7-5.8; p=0.046), and having dementia (OR, 3.5; 95%CI, 1.7-6.9; p=0.0003). Secondary displacement occurred in 18 (12%) of the 151 community-dwelling patients with normal cognition and no history of repeated falls compared to 37 (75%) of the 50 institutionalised patients with dementia.

DISCUSSION

Non-operative treatment was effective in 196 (66%) of 298 patients with Garden I femoral neck fractures. Significant risk factors for secondary displacement were dementia, institutionalisation, hypnotic treatment, multiple comorbidities, and a history of repeated falls. Of 151 community-dwelling patients with normal cognition and no repeated falls, 133 (88%) achieved a full recovery with non-operative treatment alone.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

[Comparative study of proximal femoral shortening after the third generation of Gamma nail versus proximal femoral nail anti-rotation in treatment of intertrochanteric fracture]

Objective

To explore the difference of the proximal femoral shortening (PFS) between the third generation of Gamma nail (TGN) and the proximal femoral nail anti-rotation (PFNA) in treating intertrochanteric fracture of femur.

Methods

The clinical data of 158 patients with intertrochanteric fracture of femur who were treated with TGN internal fixation or PFNA internal fixation between January 2014 and December 2015 were retrospectively analysed. The patients were divided into TGN group (69 cases) and PFNA group (89 cases) according to surgical operation. There was no significant difference in gender, age, bone mineral density, causes of injury, AO/Association for the Study of Internal Fixation (AO/ASIF) classification, accompanied disease, and the time from injury to operation between 2 groups ( P>0.05). The result of fracture reduction was divided into 3 types: positive medial cortex support, neutral position cortex support, and negative medial cortex support according to the method of Chang et al. At 18 months postoperatively, bilateral hip anteroposterior X-ray films were taken to measure horizontal PFS values (marked as X), vertical PFS values (marked as Y), and calculate the total PFS values (marked as Z). The PFS values were divided into 4 grades according to the criteria (≤1.0 mm, 1.0-4.9 mm, 5.0-9.9 mm, and ≥10.0 mm), and the constituent ratio was calculated and compared between 2 groups. The X, Y, and Z values and the collodiaphyseal angles of 2 groups at 18 months postoperatively were compared. The X, Y, and Z values of 2 groups of patients with failed fixation and normal healing within 18 months after operation were recorded and compared. The X, Y, and Z values of 2 groups of the patients with different cortex support types were also compared.

Results

There were 34 cases of positive medial cortex support, 30 cases of neutral position cortex support, and 5 cases of negative medial cortex support in TGN group, and there were 45, 33, and 11 cases in PFNA group respectively, showing no significant difference between 2 groups ( Z=-1.06, P=0.29). All patients were followed up 18 months after operation. At 18 months after operation, the constituent ratios of PFS values (X, Y, Z) had significant differences between 2 groups ( P<0.05). The patients of shortening of 1.0-4.9 mm and 5.0-9.9 mm were obviously more in TGN group than in PFNA group; the patients of shortening of ≥10.0 mm were obviously more in PFNA group than in TGN group. There were significant differences in X, Y, and Z values between 2 groups ( P<0.05), but no significant difference of the collodiaphysial angle was found between 2 groups ( t=0.47, P=0.64). Six cases of internal fixation failed in TGN group and PFNA group respectively within 3 months after operation, and there was no significant difference of X, Y, and Z values between failed fixation and normal healing patients within 2 groups ( P>0.05). When the reposition effect was the positive medial cortex support, the X, Y, and Z values were significantly lower in TGN group than in PFNA group ( P<0.05); but no significant difference was found between 2 groups when the reposition effect was the neutral position cortex support or negative medial cortex support ( P>0.05). At 18 months after operation, the X, Y, and Z values of the negative medial cortex support patients were significantly higher than those of the positive medial cortex support or the neutral position cortex support patients within 2 groups ( P<0.05).

Conclusion

PFS is a common complication of the intertrochanteric fracture of the femur after internal fixation. During operation, the selection of internal fixation should be based on the results of intraoperative reduction. TGN should be applied to reduce PFS if positive medial cortex support happened.