Age‐related hypermineralization in the female proximal human femur

Hip fracture incidence increases exponentially with age in virtually every human population that has been studied. In spite of this, relatively few studies have examined age‐related changes in the metaphyseal cortex of the proximal femur. The present study investigates cortical aging changes in the female proximal femur, with particular reference to regions of hypermineralization. Thirty‐three femora from Caucasian females were obtained at autopsy and analyzed using backscattered electron imaging. Variations in hypermineralized tissue area, cortical bone area, and porosity were quantified with standard stereological methods. Cortical width was quantified with digital calipers. Gender differences were examined by statistical comparison with previously published results. Hypermineralized tissue volume was significantly (P < 0.001) greater in elderly individuals. Hypermineralized tissue preferentially appeared near ligamentous or tendinous insertion sites, suggesting the hypermineralized tissue may be a calcified fibrocartilage. Cortical width significantly (P < 0.001) decreased with age and porosity significantly (P < 0.001) increased with age, however the changes were site‐specific. The femoral neck and intertrochanteric cortices had a smaller change in cortical width and porosity with age than the diaphysis, but the femoral neck and intertrochanteric cortices had a larger increase in hypermineralized tissue. Comparison with previous data suggests that cortical aging in the proximal femur is similar between males and females and is unlikely to explain the higher incidence of fracture in females. However, the data strongly indicates that age‐related changes in the femoral diaphysis cannot be directly extrapolated to either the femoral neck or intertrochanteric cortices. Anat Rec 255:202–211, 1999. © 1999 Wiley‐Liss, Inc.     

Characteristics of femorotibial joint geometry in the trochlear dysplastic femur

The medial and lateral tibia plateau geometry has been linked with the severity of trochlear dysplasia. The aim of the present study was to evaluate the tibial slope and the femoral posterior condylar offset in a cohort of consecutive subjects with a trochlear dysplastic femur to investigate whether the condylar offset correlates with, and thus potentially compensates for, tibial slope asymmetry. Magnetic resonance imaging was used to assess the severity of trochlear dysplasia as well as the tibial slope and posterior offset of the femoral condyles separately for the medial and lateral compartment of the knee joint in 98 subjects with a trochlear dysplastic femur and 88 control subjects. A significant positive correlation was found for the medial tibial slope and the medial posterior condylar offset in the study group (r² = 0.1566; P < 0.001). This relationship was significant for all subtypes of trochlear dysplasia and was most pronounced in the severe trochlear dysplastic femur (Dejour type D) (r² = 0.3734; P = 0.04). No correlation was found for the lateral condylar offset and the lateral tibial slope in the study group or for the condylar offset and the tibial slope on both sides in the control group. The positive correlation between the medial femoral condylar offset and the medial tibial slope, that is, a greater degree of the medial tibial slope indicated a larger offset of the medial femoral condyle, appears to represent a general anthropomorphic characteristic of distal femur geometry in patients with a trochlear dysplastic femur.     

正常成人锁骨形态的CT影像学研究

目的 观察测量锁骨CT影像学形态,为锁骨骨折锁定接骨板的治疗及改进提供解剖学参考。方法 回顾性研究2014年3—12月南京鼓楼医院排除锁骨骨折及其他可影响锁骨形态疾病的32例行肺部或颈部CT扫描患者的影像学资料,其中男16例,女16例;年龄20~75岁,平均年龄41.4岁。通过CT扫描及3D重建,分别测量32例64侧投影位锁骨的长度,近端、中段和远端宽度,锁骨近端和远端的曲率半径,锁骨水平面、冠状面的两端最大宽度及中间最小宽度等,采用成组t检验,分别比较不同侧别及性别间测量数据的差异。结果 男性锁骨的平均长度为(153.9±7.5)mm、女性锁骨的平均长度为(135.4±7.6)mm。男女的锁骨近端曲率半径均明显较远端曲率半径大,垂直投影的锁骨中段最小宽度男性为(11.7±1.9)mm,女性为(9.3±1.0)mm。左右侧各观察测数据差异均无统计学意义(P值均>0.05);男女性别间比较,除中远段曲率半径、中近段角度、中远段角度、冠状面近端最大宽度、上缘曲度差异均无统计学意义(P值均>0.05),其他指标差异均有统计学意义(P值均<0.05)。结论 锁骨的形态存在较大的性别差异,表现为女性锁骨的总长度及各部分长度较短、水平面和冠状面近端最大宽度较小,有必要根据性别差异改进器械;此外,测量结果还可为锁定接骨板术前预弯提供依据。     

Age-related hypermineralization in the female proximal human femur.

Hip fracture incidence increases exponentially with age in virtually every human population that has been studied. In spite of this, relatively few studies have examined age-related changes in the metaphyseal cortex of the proximal femur. The present study investigates cortical aging changes in the female proximal femur, with particular reference to regions of hypermineralization. Thirty-three femora from Caucasian females were obtained at autopsy and analyzed using backscattered electron imaging. Variations in hypermineralized tissue area, cortical bone area, and porosity were quantified with standard stereological methods. Cortical width was quantified with digital calipers. Gender differences were examined by statistical comparison with previously published results. Hypermineralized tissue volume was significantly (P < 0.001) greater in elderly individuals. Hypermineralized tissue preferentially appeared near ligamentous or tendinous insertion sites, suggesting the hypermineralized tissue may be a calcified fibrocartilage. Cortical width significantly (P < 0.001) decreased with age and porosity significantly (P < 0.001) increased with age, however the changes were site-specific. The femoral neck and intertrochanteric cortices had a smaller change in cortical width and porosity with age than the diaphysis, but the femoral neck and intertrochanteric cortices had a larger increase in hypermineralized tissue. Comparison with previous data suggests that cortical aging in the proximal femur is similar between males and females and is unlikely to explain the higher incidence of fracture in females. However, the data strongly indicates that age-related changes in the femoral diaphysis cannot be directly extrapolated to either the femoral neck or intertrochanteric cortices.     

Stress and strain distribution in the intact canine femur: finite element analysis

Information regarding the stresses and strains in the canine femur during various activities is important for veterinary orthopaedic surgeons, engineers designing implants for dogs, and researchers of human orthopaedics who use dogs as models. Nevertheless, such information is currently unavailable. The objective of this study is to determine the stress and strain distribution in the canine femur during mid-stance, for two loading scenarios. Three-dimensional finite element models of the canine femur were created. Two loading cases were considered: the hip joint reaction force alone, and the hip joint reaction force with all muscle forces acting on the femur. Force directions and magnitudes were obtained from the literature. Analyses were performed with NASTRAN for Windows software. When all muscle forces were considered, stresses and strains were significantly reduced, peak compressive stresses were found to occur in the medial diaphysis, and peak tensile stresses occurred in the lateral diaphysis. While the canine femur seems to be loaded primarily in bending when only the hip joint reaction force is considered, the bending moment is significantly decreased when all muscle forces are considered as well. Further in vivo and in vitro experiments are needed to validate the results of the calculations described in this paper. It is expected that future studies will be carried out, in which the stress and strain distributions in femora with different types of implants and stems will be compared to those in the normal femur.     

Three-dimensional morphology of the distal femur based on surgical epicondylar axis in the normal elderly population

BackgroundWe aimed to analyze the surface morphology of the distal femur in three dimensions for the healthy elderly, based on the concept that the surgical epicondylar axis (SEA) is a better surrogate for the flexion–extension axis of the knee joint.MethodsWe studied 77 healthy elderly volunteers (40 males and 37 females; age, 68 ± 6 years). The medial and lateral contact lines were calculated three-dimensionally, using the highest points of the medial and lateral condyles in 201 cross-sectional planes around the SEA (every 1°, −60° (hyperextension) to 140° (flexion)). A piecewise fitting function consisting of two linear segments was applied to detect the inflection point of the constant radii in the sagittal plane. The main assessment parameters were knee flexion angle at the inflection point of the radius (inflection angle), mean radius from 0° to the inflection angle (constant radius), and coronal tilt angle of the contact line.ResultsThe inflection angles, constant radii, and coronal tilt angles were 78.2 ± 8.6°, 26.1 ± 2.3 mm, and −0.6 ± 3.2° and 65.6 ± 9.2°, 23.9 ± 2.2 mm, and 6.2 ± 3.2° in the medial and lateral condyles, respectively (all, P < 0.001). The coronal alignment was 88.7 ± 2.2°.ConclusionsThe medial and lateral femoral condyles showed asymmetrical morphologies with the almost ‘constant’ radius of sagittal curvature from 0° to around 80° and 65° of knee flexion, respectively.     

Mechanical Evaluation of Large-Size Fourth-Generation Composite Femur and Tibia Models

Composite analogue bone models provide consistent geometric and structural properties that represent a valuable asset in a range of biomechanical analyses and testing procedures. The objective of this study was to evaluate the diaphyseal structural properties of the large-size Fourth-Generation composite analogue femur and tibia models concentrated on mechanical behaviors under axial compression, bending and torsion. Thirty of each large-size composite analogue models (femora and tibiae) were tested under medial-lateral four-point bending, anterior-posterior four-point bending, axial compression and external rotational torque to evaluate flexural rigidity, axial stiffness, torsional rigidity and ultimate failure strength. The composite femur was tested under torsion at both the femoral neck and the mid-diaphyseal areas. Large-size Fourth-Generation composite replicate bones exhibited intra-specimen variations under 10% for all cases and was also found to perform within the biological range of healthy adult bones (age: <80 years old) range with respect to flexural rigidity (<8%) and torsional rigidity (<12%). The failure modes of these composite models were close to published findings for human bones (four-point bending: butterfly fragment fracture; torsional: spiral fracture; and compression: transverse fracture). The large-size composite analogue femur and tibia are close to ideal replicas for standardization in biomechanical analyses. One advantage of these analogue models is that their variability is significantly lower than that of cadaveric specimens for all loading regimens. Published results vary widely in cadaveric studies, which is likely due to the high anatomic variability among cadaveric specimens. This study evaluated and advanced our overall understanding of the capacity of composite analogue bone models mimic the structural properties of average healthy adult human bones.     

Decreased femoral diaphyseal mechanical strength mainly due to qualitative impairment of cortical tissue in growing rats with stress erythropoiesis

Stress erythropoiesis (SE) can be defined as a state of increased red cell production in response to an enhanced secretion of erythropoietin. Under normal conditions, erythropoiesis in the adult occurs in the erythropoietic tissue that is confined to the bone marrow within the skeleton. Hypertrophy of the erythropoietic marrow that occurs during SE must be accommodated in a larger space. The resulting expansion of the marrow space may induce bone resorption and could alter the biomechanical performance of bone. The present study was designed to estimate the effect of sustained SE on diaphyseal structure and biomechanics of rat femur by mechanically testing the diaphyseal stiffness and strength and calculating some indicators of bone material properties. Female Sprague–Dawley rats weighing 100.0 ± 5.2 g were divided in a control (C) and an experimental (E) group. E rats were biweekly injected with 60 mg/kg of phenylhydrazyne during 6 weeks to induce a haemolytic state. SE, in response to haemolysis, was estimated by reticulocyte count and erythrokinetic techniques, which were markedly increased. To assess bone mechanical properties, the right femur was tested in three-point bending test. Sections of the left femur were stained with haematoxylin–eosin. Body growth was not altered by treatment. Diaphyseal bone mass (CSA) was 13% lower in E than in C rats, while the cross-sectional bending moment of inertia (xCSMI) was significantly higher. The “load capacity” extrinsic properties of the femoral diaphysis were about 40% decreased in E rats when compared to C ones, while the bone material quality indicators (elastic modulus and yield stress of cortical bone tissue) were 54 and 38% lower, respectively. The histologic sections of E femora exhibited a marked thinning of cortical bone and the presence of woven bone in the medullary compartment. The results obtained in this study indicate that SE caused the impairment of the diaphyseal bone material properties (elastic modulus and elastic stress) but enhanced xCSMI over the control values. Neither this improvement in diaphyseal cross-sectional design nor the formation of woven bone could offset the impairment in the bone material stiffness. It is thus proposed that the biomechanical impact of SE upon the whole-bone stiffness should have been more determined by the negative effect on bone material quality than by the negative changes in the cortical area.     

雌性大鼠去势后股骨生物力学变化

３月龄ＳＤ大鼠去势６个月后，采用三点弯曲试验描记肢骨的负荷－变形曲线，计算肢骨最大负荷和致断应力，与对照组比较。反映股骨组成材料力学性能的致断应力，去势后显著降低。反映整根股骨力学性能的最大负荷，去势后虽有减小，但无显著性差异。结果表明：雌性大鼠去势后股骨组成材料的力学性能受到显著损害，而整根股骨的力学性能．因几何形状的优化，无明显变化。     

Anatomic variation in the elastic anisotropy of cortical bone tissue in the human femur

Experimental investigations for anatomic variation in the magnitude and anisotropy of elastic constants in human femoral cortical bone tissue have typically focused on a limited number of convenient sites near the mid-diaphysis. However, the proximal and distal ends of the diaphysis are more clinically relevant to common orthopaedic procedures and interesting mechanobiology. Therefore, the objective of this study was to measure anatomic variation in the elastic anisotropy and inhomogeneity of human cortical bone tissue along the entire length (15%–85% of the total femur length), and around the periphery (anterior, medial, posterior and lateral quadrants) of the femoral diaphysis, using ultrasonic wave propagation in the three orthogonal specimen axes. The elastic symmetry of tissue in the distal and extreme proximal portions of the diaphysis (15%–45% and 75%–85% of the total femur length, respectively) was, at most, orthotropic. In contrast, the elastic symmetry of tissue near the mid- and proximal mid-diaphysis (50%–70% of the total femur length) was reasonably approximated as transversely isotropic. The magnitudes of elastic constants generally reached maxima near the mid- and proximal mid-diaphysis in the lateral and medial quadrants, and decreased toward the epiphyses, as well as the posterior and anterior quadrants. The elastic anisotropy ratio in the longitudinal and radial anatomic axes showed the opposite trends. These variations were significantly correlated with the apparent tissue density, as expected. In summary, the human femur exhibited statistically significant anatomic variation in elastic anisotropy, which may have important implications for whole bone numerical models and mechanobiology.     

Morphological profile of atypical femoral fractures: age‐related changes to the cross‐sectional geometry of the diaphysis

The use of bisphosphonates for osteoporosis patients has markedly decreased the incidence of femoral neck or trochanteric fractures. However, anti‐osteoporosis drugs have been reported to increase the incidence of atypical femoral fractures, which involve stress fractures in the subtrochanteric region or the proximal diaphysis. In this study, the morphological characteristics of the cortical bone in human femoral diaphysis samples were analyzed from individuals who lived before bisphosphonate drugs were available in Japan. A total of 90 right femoral bones were arbitrarily selected (46 males and 44 females) from modern Japanese skeletal specimens. Full‐length images of these femurs were acquired using a computed tomography scanner. An image processing method for binarization was used to calculate the threshold values of individual bones for determining their contours. The range between the lower end of the lesser trochanter and the adductor tubercle of each femur was divided at regular intervals to obtain 10 planes. The mean value of cortical bone thickness, periosteal border length, and the cortical cross‐sectional area was evaluated for all planes. Moreover, the ratio of the area of the cortical bone to the total area of cross‐section at the mid‐diaphysis was calculated. A comparison between males and females demonstrated that most females had lower cortical bone area ratios at the mid‐diaphysis. The femoral outer shape did not differ markedly according to age or sex; however, substantial individual differences were observed in the shape of the inner surface of the cortical bone. The cortical bone thickness and the cross‐sectional area decreased with age in the femoral diaphysis; furthermore, in females, the decrease was higher for the former than for the latter. This may be due to a compensatory increase in the circumference of the femoral diaphysis. In addition, in about half of the subjects there was a discrepancy between the region with maximal value of the cortical bone thickness and that of the total cross‐sectional area. Biological responses to mechanical stresses to the femoral diaphysis are thought not to be uniform. Bisphosphonates inhibit bone resorption and may promote non‐physiological bone remodeling. Thus, a nonhomogeneous decrease in cortical thickness may be related to the fracture occurrence in the femoral diaphysis in some cases. Thus, long‐term administration of bisphosphonates in patients with morphological vulnerability in the femoral cortical bones may increase the occurrence of atypical femoral fractures.     

Drifting Diaphyses: Asymmetry in Diametric Growth and Adaptation Along the Humeral and Femoral Length

This study quantifies regional histomorphological variation along the human humeral and femoral diaphysis in order to gain information on diaphyseal growth and modeling drift patterns. Three thin sections at 40, 50, and 60% bone length were prepared from a modern Mexican skeletal sample with known age and sex to give a longitudinal perspective on the drifting cortex (12 adults and juveniles total, 7 male and 5 female). Point‐count techniques were applied across eight cross‐sectional regions of interest using the starburst sampling pattern to quantify percent periosteal and endosteal primary lamellar bone at each diaphyseal level. The results of this study show a posterio‐medial drift pattern in the humerus with a posterior rotational trend along the diaphysis. In the femur, we observed a consistent lateral to anteriolateral drift and an increase in primary lamellar bone area of both, periosteal and endosteal origin, towards the distal part of the diaphysis. These observations characterize drifting diaphyses in greater detail, raising important questions about how to resolve microscopic and macroscopic cross‐sectional analysis towards a more complete understanding of bone growth and mechanical adaptation. Accounting for modeling drift has the potential to positively impact age and physical activity estimation, and explain some of the significant regional variation in bone histomorphology seen within (and between) bone cross‐sections due to differing ages of tissue formation. More study is necessary, however, to discern between possible drift scenarios and characterize populational variation. Anat Rec, 298:1689–1699, 2015. © 2015 Wiley Periodicals, Inc.     

Can a semi-automated surface matching and principal axis-based algorithm accurately quantify femoral shaft fracture alignment in six degrees of freedom?

Accurate alignment of femoral shaft fractures treated with intramedullary nailing remains a challenge for orthopaedic surgeons. The aim of this study is to develop and validate a cone-beam CT-based, semi-automated algorithm to quantify the malalignment in six degrees of freedom (6DOF) using a surface matching and principal axes-based approach. Complex comminuted diaphyseal fractures were created in nine cadaveric femora and cone-beam CT images were acquired (27 cases total). Scans were cropped and segmented using intensity-based thresholding, producing superior, inferior and comminution volumes. Cylinders were fit to estimate the long axes of the superior and inferior fragments. The angle and distance between the two cylindrical axes were calculated to determine flexion/extension and varus/valgus angulation and medial/lateral and anterior/posterior translations, respectively. Both surfaces were unwrapped about the cylindrical axes. Three methods of matching the unwrapped surface for determination of periaxial rotation were compared based on minimizing the distance between features. The calculated corrections were compared to the input malalignment conditions. All 6DOF were calculated to within current clinical tolerances for all but two cases. This algorithm yielded accurate quantification of malalignment of femoral shaft fractures for fracture gaps up to 60 mm, based on a single CBCT image of the fractured limb.     

Comparative study of femoral diaphyseal morphometry in two male populations, in France and a French West Indies island: an example of clinical relevance of comparative anatomy for orthopedic practice

Our aim, through a comparative study of two populations, one European and the other Afro-Caribbean, was to find out whether there were differences in radiographic measurements of femoral diaphyseal canal diameter, thickness of the medial and lateral cortex, and global diaphyseal diameter. We studied the nailed femurs of adult males in a population of 54 Europeans and 52 Afro-Caribbeans. Both populations were comparable in terms of age, height and weight. The measurements were taken with a ruler on the narrowest area of the hourglass, the isthmus, on an antero-posterior radiograph. The diameter of the femoral canal was classified into three intervals: <13 mm, 13–14 mm and >14 mm. The femoral canal diameter was significantly larger in the European patients, 14.3 (11–19) versus 13.4 (11–15.6), while the thickness of the lateral cortex was significantly larger in the Afro-Caribbean patients, 8.50 (6–12) versus 7.72 (5.4–11.5). Patient distribution according to the intervals was different in both groups: 59% of the Afro-Caribbeans were in the average interval versus 24.1% of the Europeans. For nearly 53.7% of the Europeans, the diameter of the femoral canal fell in the last interval versus 15.4% of the Afro-Caribbeans. The fact that the femoral canal is narrower in the Afro-Caribbean population may be linked to a thicker lateral cortex. The diameters of the nails used were larger in the European population, 12.6 mm (10–15) versus 12.1 mm (11–14) in the Afro-Caribbean population. The global diameters of both populations’ femurs were similar (28.9 mm for the European sample vs. 29 mm). The present study may have an impact on the implants used in the orthopedic surgery (intramedullary nailing, arthroplasty implants). The range of usable implants must be complete and there must be precise pre-operative planning. A study of computed tomography scans could complement our measurements.     

人体下肢长骨负重关节软骨下松质骨显微硬度分布特征的研究

目的:探讨人体下肢长骨负重关节软骨下松质骨显微硬度的分布特征。方法:选取3具年龄大于40岁的新鲜冰冻尸体标本,取出所有标本的右侧股骨和胫骨,分别于股骨头、股骨内髁、股骨外髁、胫骨内髁、胫骨外髁、胫骨远端距负重区关节软骨面1 cm处,垂直于下肢机械轴切下3 mm厚松质骨样本。使用维氏显微硬度测量系统测量骨组织显微硬度。比...     

Anthropometric difference of the knee on MRI according to gender and age groups

The purpose of this study was to analyze the anthropometric data from MRI images that were obtained from the non-arthritic knees in Asian adults, and to identify the existence of morphologic differences between age groups. This cross-sectional study included knee MR images of 535 patients (273 males, 262 females) taken for the evaluation of soft-tissue injuries, excluding cases with cartilage defect and malalignment. The age, gender, height, and BMI were also assessed. The patients were grouped into three different 20-year age groups (20–39, 40–59, and 60–79). The MRI analysis was performed on the anthropometric parameters of distal femur and posterior tibial slope. Age-related differences were found in femoral width, distance from the distal and posterior cartilage surface to the medial/lateral epicondyle, medial posterior condylar offset (PCO), and posterior condylar angle (PCA) (all P < 0.001), but not in lateral PCO, and medial/lateral tibial slopes. In the analysis of covariance analyses, significant interaction between gender and age groups was found in most parameters, but not in PCA, distance from the posterior cartilage surface to the medial epicondyle, or medial tibial slope. We found anthropometric differences among age groups exist in most of distal femoral parameters, but not in posterior tibial slope. The results of this study can be used by manufacturers to modify prostheses to be suitable for the future Asian elderly population.     

An investigation of the anatomy of the infrapatellar fat pad and its possible involvement in anterior pain syndrome: a cadaveric study

The infrapatellar fat pad (IFP) is an extrasynovial, intracapsular, adipose body occupying the space in the knee joint between the inferior border of the patella, the femoral condyles, tibial plateau and patellar tendon. Little is known about the anatomy and normal function of the IFP, but it has been suggested to play a role in the aetiology of Anterior knee pain syndrome, including that associated with osteoarthritis. Forty-three knees from 11 male and 15 female embalmed cadavers (mean age 84 years; range 55–97 years) were investigated. The cadavers were donated and the study performed in compliance with the provisions of the UK Human Tissue Act (2004). The quadriceps tendon and the medial and lateral patellar retinacula were dissected from the patella, which was then reflected antero-distally. The IFP was carefully excised and details of its morphology and attachments to components of the knee joint were recorded, together with the presence of articular surface pathology on the patella and femoral condyles. The principal novel findings of the current study were that 81% of IFPs were attached to the superior border of the patella by supero-medial extensions and 65% were attached by supero-lateral extensions; the supero-medial extensions were larger than the supero-lateral extensions. The superior extensions of the IFP were always attached anteriorly to the patellar retinacula and in four individuals the extensions formed a full loop around the superior border of the patella. The volume of IFPs with attachments to the superior border of the patella was significantly greater (p = .007) than those without, and the IFP was attached to the medial meniscus in significantly (p = .009) more knees with IFP attachment to the superior border of the patella than those without. All IFPs were attached to the medial anterior horn of the meniscus and the medial Kaplan’s ligament. Ninety-seven per cent were attached to the lateral anterior horn of the meniscus and 97% to the lateral Kaplan’s ligament. The length of IFP attachment to the lateral meniscus was significantly longer (p = .004) than that to the medial meniscus. Ninety-seven per cent of IFPs were attached to the superior portion of the patellar tendon with the mean tendon attachment being 60%. Ninety-one per cent of IFPs were attached to the inferior border of the patella. Significantly fewer knees with patellar (p = .001) and femoral (p = .002) articular surface osteophytes exhibited superior IFP extensions and these extensions were significantly shorter in knees with patellar (p = .000) and femoral (p = .006) osteophytes, compared with those without. The IFP was attached to the medial meniscus in significantly fewer knees with femoral (p = .050) and patellar (p = .023) osteophytes than those without. All IFPs not attached to the anterior horn of the lateral menisci, medial Kaplan’s ligament, superior patella or inferior border of the patella, were in knees with articular surface osteophytes. This relationship between IFP morphology and knee joint pathology suggests a functional role for the IFP that requires further investigation.     

Understanding the undulating pattern of the distal femoral growth plate: Implications for surgical procedures involving the pediatric knee: A descriptive MRI study

IntroductionOperative procedures near the distal femoral physis can result in iatrogenic damage if one is not familiar with the complex anatomy of the growth plate. The purpose of this study was to use physeal-specific MRI sequences to delineate the anatomic dimensions of the distal femoral physis.Materials and methodsSixty patients underwent physeal-specific spoiled gradient 3-D fat saturated (SPGR) MRI analysis of a single knee. Three age groups (eight to 10, 11–13, and 14–16 years) comprised of equal numbers (n = 20) of boys and girls were evaluated. Using the SPGR coronal sequence, the distance of the physis to the femoral articular cartilage was recorded at the medial, mid-medial, notch, mid-lateral and lateral margins of the knee. Coronal measurements were recorded at four locations along the sagittal sequence, as the anteroposterior dimension of the knee was divided into equal quartiles.ResultsWhile little variation in shape was observed in the anterior quartile, the remaining quartiles demonstrated significant variability that increased moving posteriorly (p < .001), therefore reflecting a more concave shape in the posterior aspect of the femur. These observations were statistically significant for age at the posterior two quartiles.ConclusionThese MRI data suggest that while the physis is linear in the anterior part of the femur, it possesses a more concave shape in the posterior aspect of the medial and lateral condyles. Findings were preserved across gender and age. Ultimately, these data can aid in preoperative planning and should be considered when performing operative procedures in the skeletally immature knee.     

Robust QCT/FEA Models of Proximal Femur Stiffness and Fracture Load During a Sideways Fall on the Hip

Clinical implementation of quantitative computed tomography-based finite element analysis (QCT/FEA) of proximal femur stiffness and strength to assess the likelihood of proximal femur (hip) fractures requires a unified modeling procedure, consistency in predicting bone mechanical properties, and validation with realistic test data that represent typical hip fractures, specifically, a sideways fall on the hip. We, therefore, used two sets (n = 9, each) of cadaveric femora with bone densities varying from normal to osteoporotic to build, refine, and validate a new class of QCT/FEA models for hip fracture under loading conditions that simulate a sideways fall on the hip. Convergence requirements of finite element models of the first set of femora led to the creation of a new meshing strategy and a robust process to model proximal femur geometry and material properties from QCT images. We used a second set of femora to cross-validate the model parameters derived from the first set. Refined models were validated experimentally by fracturing femora using specially designed fixtures, load cells, and high speed video capture. CT image reconstructions of fractured femora were created to classify the fractures. The predicted stiffness (cross-validation R ² = 0.87), fracture load (cross-validation R ² = 0.85), and fracture patterns (83% agreement) correlated well with experimental data.