Femoral neck cross-sectional geometry and exercise loading

Comparing Methods for Calculating Cross-Sectional Properties From High-Resolution CT Scans in Dry Bone: The Case of the Non-Adult Femoral Midneck

OBJECTIVE

This paper explores the various protocols for deriving endosteal and periosteal contours of the femoral midneck cross-section in non-adult individuals using EPmacroJ.

MATERIALS AND METHODS

We analyzed femoral midneck cross-sectional contours in a total sample of 55 femora belonging to medieval individuals ranging in age between 2 and 20 years. Femoral midneck cross-sections were taken on high-resolution CT images and analyzed by EPJMacro in FIJI. Cross-sectional properties were obtained from periosteal and endosteal contours derived by manual, automatic, spline, and ellipse techniques. Agreement between the manual and the other techniques was evaluated using percent prediction error (%PE) and following the Bland-Altman approach.

RESULTS

All the evaluated techniques used for deriving the periosteal and endosteal contours at the femoral midneck cross-section in non-adult individuals have proven to be interchangeable with manual processing, except for the spline technique for the endosteal contour. The narrowest limits of agreement were obtained for the total area, moderate limits of agreement were found for the cortical and medullary areas, and the widest limits of agreement were observed in the section moduli.

DISCUSSION

The automatic processing of the periosteal and endosteal contours shows a high level of agreement with the manual processing of both contours. Semi-automatic approaches (spline and ellipse) provide less agreement, especially in section moduli. This suggests that inaccuracies in deriving the endosteal contour significantly affect section moduli. The best approach for extracting the geometric properties of femoral midneck cross-sections is a combination of automatic and manual methods, although automatic methods alone are also effective.

Exploring developmental changes in femoral midneck cross-sectional properties

This research delves deeper into previous works on femoral cross-sectional properties during ontogeny by focusing for the first time on the human femoral midneck. The ontogenetic pattern of cross-sectional properties at femoral midneck is established and compared with those at three different femoral locations: the proximal femur, the midshaft, and the distal femur. The study sample includes 99 femora (70 non-adults and 29 adults) belonging to archaeological specimens. Cross-sectional properties were extracted from computed tomographic scans and analyzed with the MomentMacro plugin of ImageJ. Ontogenetic trends of these variables were assessed using locally estimated scatterplot smoothing and segmented regressions, along with Wilcoxon post hoc tests for all possible age group pairings. Our results show that the femoral midneck exhibits a unique growth pattern. Area variables showed rapid growth until adolescence, followed by a more gradual increase leading into adulthood. Nonetheless, the relative cortical area does not demonstrate any significant drops or rise during growth. The morphology of the midneck section of the femur remains stable during ontogeny, with early adolescence and the onset of adulthood marking two periods of significant change. In contrast to the femoral diaphysis, the acquisition of a mature bipedal gait does not appear to constitute a period of significant morphological change at the femoral midneck cross section.

Safe range of femoral neck system insertion and the risk of perforation

BACKGROUND

Internal fixation of the femoral neck carries a risk of perforation due to the presence of the isthmus of the femoral neck. At present, there are few studies on the safe and risk zones of the femoral neck system (FNS) implantation. This study aimed to recommend the safe range of injection of FNS in the lateral wall of the proximal femur, parallel to the axis of the femoral neck, during FNS treatment of femoral neck fracture (FNF).

METHODS

Femoral computed tomography (CT) data of 80 patients (male: 40; female: 40) who met the inclusion criteria were collected. Mimics 21.0 software was used to complete the modeling. 3-Matic 13.0 software was used to establish the axis of the femoral neck and its vertical plane, perform the cutting of the femoral neck, and project it on the vertical plane of the femoral neck axis. After matching a rectangle for each projection map, all sample sizes (80 cases) were standardized and superimposed to obtain gradient maps of the safe zone (SZ) and dangerous zone (RZ), thereby securing edge key points and safe FNS insertion range.

RESULTS

In the 80 samples, the mean diameter of the smallest femoral neck section was 33.87 ± 2.32 mm for men and 29.36 ± 1.92 mm for women. All 80 femoral necks had safe and risky areas. The SZ/S × 100% was 77.59 (± 2.22%), and the RS/S × 100% was 22.39% (± 2.22%). The risk area was composed of four parts: (1), (2), (3), and (4), respectively, corresponding to 3.45 ± 1.74%, 5.51 ± 2.63%, 6.22 ± 1.41%, and 7.22 ± 1.39%. Four marginal key points, perforation risk, and safe ranges (SR) of FNS were analyzed on the lateral wall of the femoral neck.

CONCLUSIONS

The SR of FNS placement was recommended by digital simulation. In addition, Regions (3) and (4) posed a higher risk of penetrating the cortex. Using the gradient map of RZ for preoperative evaluation is recommended to avoid iatrogenic perforation.

Effect of fall direction on the lower hip fracture risk in athletes with different loading histories: A finite element modeling study in multiple sideways fall configurations

Physical loading makes bones stronger through structural adaptation. Finding effective modes of exercise to improve proximal femur strength has the potential to decrease hip fracture risk. Previous proximal femur finite element (FE) modeling studies have indicated that the loading history comprising impact exercises is associated with substantially higher fracture load. However, those results were limited only to one specified fall direction. It remains thus unclear whether exercise-induced higher fracture load depends on the fall direction. To address this, using magnetic resonance images of proximal femora from 91 female athletes (mean age 24.7 years with >8 years competitive career) and their 20 non-athletic but physically active controls (mean age 23.7 years), proximal femur FE models were created in 12 different sideways fall configurations. The athletes were divided into five groups by typical loading patterns of their sports: high-impact (H-I: 9 triple- and 10 high-jumpers), odd-impact (O-I: 9 soccer and 10 squash players), high-magnitude (H-M: 17 powerlifters), repetitive-impact (R-I: 18 endurance runners), and repetitive non-impact (R-NI: 18 swimmers). Compared to the controls, the FE models showed that the H-I and R-I groups had significantly (p < 0.05) higher fracture loads, 11-17% and 22-28% respectively, in all fall directions while the O-I group had significantly 10-11% higher fracture loads in four fall directions. The H-M and R-NI groups did not show significant benefit in any direction. Also, the analyses of the minimum fall strength (MFS) among these multiple fall configurations confirmed significantly 15%, 11%, and 14% higher MFSs in these impact groups, respectively, compared to the controls. These results suggest that the lower hip fracture risk indicated by higher fracture loads in athletes engaged in high impact or repetitive impact sports is independent of fall direction whereas the lower fracture risk attributed to odd-impact exercise is more modest and specific to the fall direction. Moreover, in concordance with the literature, the present study also confirmed that the fracture risk increases if the impact is imposed on the more posterolateral aspect of the hip. The present results highlight the importance of engaging in the impact exercises to prevent hip fractures and call for retrospective studies to investigate whether specific impact exercise history in adolescence and young adulthood is also associated with lower incidence of hip fractures in later life.

A Novel Technique to Detect Femoral Shaft Perforation during Direct Anterior Total Hip Arthroplasty

Despite its popularity, the direct anterior approach for hip arthroplasty is not without complications. Intraoperative femoral shaft perforation using this approach ranges from 0.8% to 7%. A missed perforation can lead to fracture with the need for further surgery if not detected intraoperatively. We describe a reproducible and cost-effective technique using a plastic Yankauer suction handle to help identify proximal femoral perforations during direct anterior total hip arthroplasty. Careful attention to the visual, tactile, and auditory feedback provided by the suction handle can help ensure the cortical continuity of the proximal femur. Familiarity with relevant surgical anatomy, improving surgical technique, and scrutinizing implant positioning helps minimize the risk of complications during the direct anterior approach.

Do bone geometric properties of the proximal femoral diaphysis reflect loading history, muscle properties, or body dimensions?

OBJECTIVES

The aim of this study was to investigate activity-induced effects from bone geometric properties of the proximal femur in athletic vs nonathletic healthy females by statistically controlling for variation in body size, lower limb isometric, and dynamic muscle strength, and cross-sectional area of Musculus gluteus maximus.

METHODS

The material consists of hip and proximal thigh magnetic resonance images of Finnish female athletes (N = 91) engaged in either high jump, triple jump, soccer, squash, powerlifting, endurance running or swimming, and a group of physically active nonathletic women (N = 20). Cross-sectional bone geometric properties were calculated for the lesser trochanter, sub-trochanter, and mid-shaft of the femur regions. Bone geometric properties were analyzed using a general linear model that included body size, muscle size, and muscle strength as covariates.

RESULTS

Body size and isometric muscle strength were positively associated with bone geometric properties at all three cross-sectional levels of the femur, while muscle size was positively associated with bone properties only at the femur mid-shaft. When athletes were compared to nonathletic females, triple jump, soccer, and squash resulted in greater values in all studied cross-sections; high jump and endurance running resulted in greater values at the femoral mid-shaft cross-section; and swimming resulted in lower values at sub-trochanter and femur mid-shaft cross-sections.

CONCLUSIONS

Activity effects from ground impact loading were associated with higher bone geometric values, especially at the femur mid-shaft, but also at lesser and sub-trochanter cross-sections. Bone geometric properties along the femur can be used to assess the mechanical stimuli experienced, where ground impact loading seems to be more important than muscle loading.

Obtuse triangle screw configuration for optimal internal fixation of femoral neck fracture: an anatomical analysis

OBJECTIVES:

To identify the optimal screw configuration for internal fixation of femoral neck fractures based on anatomic analysis on radiologic imaging.

METHODS:

30 proximal femurs of 15 adults were constructed by CT. 3 femoral neck sections (FNS), the subcapital, medial, and the fundus, were projected on to the lateral femoral trochanteric wall. The simulated 3 screw configurations in the projection of FNS include: 2 inverted equilateral triangles symmetrised to the axis of the FNS (IET-FNS group) or the coronal axis of the proximal femur (IET-PR group) and an obtuse triangle (OT group). The distance between the screws, the distance between the centre of the FNS and the screws, and the area ratio of the triangle/FNS were calculated.

RESULTS:

The projection of the FNS on to the lateral femoral trochanteric wall is displayed as a rotating forward ellipse. Measurements of distance between screws, distance between the centre of the FNS to the screws, and the area ratio of triangle/FNS were significantly larger in the OT group than in the IET-FNS and IET-PF groups ( p < 0.05). The values of the 3 parameters in the IET-FNS group were also larger than those in the IET-PF group ( p < 0.05).

CONCLUSIONS:

The obtuse triangle screw configuration displayed advantages with respect to the parameters of distance between screws, distance between the centre of FNS to screws, and the triangle area. Therefore, the obtuse triangle screw configuration may be the ideal pattern for internal fixation of femoral neck fractures (Pauwels I and II). This needs to be corroborated with biomechanics testing.

Impact loading history modulates hip fracture load and location: A finite element simulation study of the proximal femur in female athletes

Sideways falls impose high stress on the thin superolateral cortical bone of the femoral neck, the region regarded as a fracture-prone region of the hip. Exercise training is a natural mode of mechanical loading to make bone more robust. Exercise-induced adaptation of cortical bone along the femoral neck has been previously demonstrated. However, it is unknown whether this adaption modulates hip fracture behavior. The purpose of this study was to investigate the influence of specific exercise loading history on fall-induced hip fracture behavior by estimating fracture load and location with proximal femur finite element (FE) models created from magnetic resonance images (MRI) of 111 women with distinct exercise histories: 91 athletes (aged 24.7 ± 6.1 years, >8 years competitive career) and 20 women as controls (aged 23.7 ± 3.8 years). The athletes were divided into five groups based on typical loading patterns of their sports: high-impact (H-I: 9 triple-jumpers and 10 high jumpers), odd-impact (O-I: 9 soccer and 10 squash players), high-magnitude (H-M: 17 power-lifters), repetitive-impact (R-I: 18 endurance runners), and repetitive non-impact (R-NI: 18 swimmers). Compared to the controls, the H-I, O-I, and R-I groups had significantly higher (11-26%, p < 0.05) fracture loads. Also, the fracture location in the H-I and O-I groups was significantly more proximal (7-10%) compared to the controls. These results suggest that an exercise loading history of high impacts, impacts from unusual directions, or repetitive impacts increases the fracture load and may lower the risk of fall-induced hip fracture.

Ricci-flow based conformal mapping of the proximal femur to identify exercise loading effects

The causal relationship between habitual loading and adaptive response in bone morphology is commonly explored by analysing the spatial distribution of mechanically relevant features. In this study, 3D distribution of features in the proximal femur of 91 female athletes (5 exercise loading groups representing habitual loading) is contrasted with 20 controls. A femur specific Ricci-flow based conformal mapping procedure was developed for establishing correspondence among the periosteal surfaces. The procedure leverages the invariance of the conformal mapping method to isometric shape differences to align surfaces in the 2D parametric domain, to produce dense correspondences across an isotopological set of surfaces. This is implemented through a multi-parametrisation approach to detect surface features and to overcome the issue of inconsistency in the anatomical extent present in the data. Subsequently, the group-wise distribution of two mechanically relevant features was studied – cortical thickness and surface principal strains (simulation results of a sideways fall). Statistical inferences over the surfaces were made by contrasting the athlete groups with the controls through statistical parametric mapping. With the aid of group-wise and composite-group maps, proximal femur regions affected by specific loading groups were identified with a high degree of spatial localisation.

Exercise loading history and femoral neck strength in a sideways fall: A three-dimensional finite element modeling study

Over 90% of hip fractures are caused by falls. Due to a fall-induced impact on the greater trochanter, the posterior part of the thin superolateral cortex of the femoral neck is known to experience the highest stress, making it a fracture-prone region. Cortical geometry of the proximal femur, in turn, reflects a mechanically appropriate form with respect to habitual exercise loading. In this finite element (FE) modeling study, we investigated whether specific exercise loading history is associated with femoral neck structural strength and estimated fall-induced stresses along the femoral neck. One hundred and eleven three-dimensional (3D) proximal femur FE models for a sideways falling situation were constructed from magnetic resonance (MR) images of 91 female athletes (aged 24.7±6.1years, >8years competitive career) and 20 non-competitive habitually active women (aged 23.7±3.8years) that served as a control group. The athletes were divided into five distinct groups based on the typical loading pattern of their sports: high-impact (H-I: triple-jumpers and high-jumpers), odd-impact (O-I: soccer and squash players), high-magnitude (H-M: power-lifters), repetitive-impact (R-I: endurance runners), and repetitive non-impact (R-NI: swimmers). The von Mises stresses obtained from the FE models were used to estimate mean fall-induced stresses in eight anatomical octants of the cortical bone cross-sections at the proximal, middle, and distal sites along the femoral neck axis. Significantly (p<0.05) lower stresses compared to the control group were observed: the H-I group - in the superoposterior (10%) and posterior (19%) octants at the middle site, and in the superoposterior (13%) and posterior (22%) octants at the distal site; the O-I group - in the superior (16%), superoposterior (16%), and posterior (12%) octants at the middle site, and in the superoposterior (14%) octant at the distal site; the H-M group - in the superior (13%) and superoposterior (15%) octants at the middle site, and a trend (p=0.07, 9%) in the superoposterior octant at the distal site; the R-I group - in the superior (14%), superoposterior (23%) and posterior (22%) octants at the middle site, and in the superoposterior (19%) and posterior (20%) octants at the distal site. The R-NI group did not differ significantly from the control group. These results suggest that exercise loading history comprising various impacts in particular is associated with a stronger femoral neck in a falling situation and may have potential to reduce hip fragility.

The cross-sectional area of the gluteus maximus muscle varies according to habitual exercise loading: Implications for activity-related and evolutionary studies

Greater size of the gluteus maximus muscle in humans compared to non-human primates has been considered an indication of its function in bipedal posture and gait, especially running capabilities. Our aim was to find out how the size of the gluteus maximus muscle varies according to sports while controlling for variation in muscle strength and body weight. Data on gluteus maximus muscle cross-sectional area (MCA) were acquired from magnetic resonance images of the hip region of female athletes (N=91), and physically active controls (N=20). Dynamic muscle force was measured as counter movement jump and isometric knee extension force as leg press. Five exercise loading groups were created: high impact (triple-jumpers and high-jumpers), odd impact (soccer and squash players), high magnitude (power-lifters), repetitive impact (endurance runners) and repetitive non-impact (swimmers) loadings. Individuals in high impact, odd impact or high-magnitude loading groups had greater MCA compared to those of controls, requiring powerful hip extension, trunk stabilization in rapid directional change and high explosive muscle force. Larger body size and greater muscle strength were associated with larger MCA. An increase in dynamic force was associated with larger MCA, but the strength of this relationship varied with body weight. Thus, gluteal adaptation in humans promotes powerful lower limb movements required in sprinting and rapid changes in direction, as well as maintenance and stabilization of an erect trunk which also provides a platform for powerful motions of the upper limbs. These movements have likely evolved to facilitate food acquisition, including hunting.

Exercise, nutrition and managing hip fracture in older persons

PURPOSE OF REVIEW

Lifestyle factors play a role in both the genesis and recovery from fragility fracture. The purpose of this review is to summarize recent evidence for exercise and nutrition in the management of hip fracture.

RECENT FINDINGS

Recent randomized controlled trials of exercise have primarily consisted of isolated resistance training or multimodal home-based programs. More robust, long-term, or supervised training is generally associated with greater clinical benefits, including muscle strength, mobility, and function. Recent nutritional interventions have included multinutrient supplements, nutritional counseling and support, and vitamin D/calcium supplementation. Isolated nutritional interventions have not consistently shown significant impact on long-term outcomes after hip fracture, although improvements in body weight, biochemical indices, complication rates, and mobility have been reported. Overall, there is marked heterogeneity in the robustness of responses seen to hip fracture treatment studies. Few large, long-term, multicomponent interventions with clinically relevant outcomes of functional independence, need for residential care, mortality, and quality of life have been reported.

SUMMARY

Evidence-based approaches to hip fracture should include comprehensive risk-factor assessment and treatment for sarcopenia/dynapenia, balance impairment, undernutrition of protein, energy, vitamin D and calcium, depression, cognitive impairment, sensory impairment, social isolation, and comorbid illness with exercise, nutrition and other modalities.

Is bone tissue really affected by swimming? A systematic review

Background

Swimming, a sport practiced in hypogravity, has sometimes been associated with decreased bone mass.

Aim

This systematic review aims to summarize and update present knowledge about the effects of swimming on bone mass, structure and metabolism in order to ascertain the effects of this sport on bone tissue.

Methods

A literature search was conducted up to April 2013. A total of 64 studies focusing on swimmers bone mass, structure and metabolism met the inclusion criteria and were included in the review.

Results

It has been generally observed that swimmers present lower bone mineral density than athletes who practise high impact sports and similar values when compared to sedentary controls. However, swimmers have a higher bone turnover than controls resulting in a different structure which in turn results in higher resistance to fracture indexes. Nevertheless, swimming may become highly beneficial regarding bone mass in later stages of life.

Conclusion

Swimming does not seem to negatively affect bone mass, although it may not be one of the best sports to be practised in order to increase this parameter, due to the hypogravity and lack of impact characteristic of this sport. Most of the studies included in this review showed similar bone mineral density values in swimmers and sedentary controls. However, swimmers present a higher bone turnover than sedentary controls that may result in a stronger structure and consequently in a stronger bone.