Femoral Bowing Research Articles

Population-based, three-dimensional analysis of age- and sex-related femur shaft geometry differences.

The changes in femur geometry that occur with aging and lead to fragility or insufficiency fracture remain unclear. The role of the lower limb geometry, including the femur and femoral bowing, has become a point of discussion, especially in atypical femur fracture. This study aimed to analyze femur shaft geometry using three-dimensional skeletonization. We acquired computed tomography images of both femurs obtained. A total of 1400 age- and sex-stratified participants were enrolled and were divided into subgroups according to age (by decade) and sex. The computed tomography images were used to produce 3-dimensional samplings of anatomical elements of the human femur using reconstruction and parametrization from these datasets. The process of skeletonization was conducted to obtain compact representation of the femur. With the skeletonization, we were able to compare all parameters according to age and sex. The femur length was 424.4 ± 28.6mm and was longer in men (P < 0.001). The minimum diameter of the medullary canal was 8.9 ± 2.0mm. The radius of curvature (ROC) was 906.9 ± 193.3mm. Men had a larger femur length, femur outer diameter, and the narrowest medullary diameter (P < 0.001, respectively). Women had significantly smaller ROC (P < 0.001). ROC decreased by 19.4% in men and 23.6% in women between the ages of 20 to 89years. Femur width increased over life by 11.4% in men and 24.5% in women. Between the ages of 50 and 89years, the medullary canal appears to have increased by 32.7% in women. This geometry analysis demonstrated that femoral bowing and femoral width increased related to aging, and that the medullary canal widened after the age of 50years in women. This cross-sectional study revealed important age- and sex-related differences in femur shaft geometry that occur with aging.

A Novel Surgical Method for Treating Symptomatic Incomplete Atypical Femoral Fracture using Percutaneous Elastic Intramedullary Nailing.

Purpose:To introduce the principles and procedure of percutaneous elastic intramedullary nailing (PEIN) as a treatment for symptomatic incomplete atypical femoral fracture (SIAFF).Methods:From October 2014 to April 2019, 6 cases of SIAFF were treated with PEIN. Two pre-bent 4-mm stainless-steel nails were used to apply compressive force to the fracture site. The antegrade method was used for proximal fractures and the retrograde method for middle and distal femoral fractures. The femoral bowing angle in the coronal and sagittal planes, and the time required for callus formation and union, were evaluated on plain radiographs in both planes. Thigh pain, tenderness, and complications were also assessed.Results:The mean operating time was 65.00 ± 22.64 min. No case progressed to complete atypical fracture. In one case, fracture occurred around the point of nail entry after the patient fell from a chair on postoperative day 7. The incomplete fracture lines were united in 5 cases, after excluding one case with a complication. The time taken to confirm endocortical callus formation, fracture line disappearance, and clinical union was 2.11 ± 0.53, 6.45 ± 4.10, and 6.45 ± 3.65 months, respectively.Conclusions:PEIN is a quick, simple but effective treatment for SIAFF that considers the fracture mechanism and is applicable to cases with severe femoral bowing.Level of evidence:Level IV, case series.

The Case of Periprosthetic Femoral Fracture with Severe Femoral Bowing which Required Osteotomy to Insert a Femoral Nail

The Case of Periprosthetic Femoral Fracture with Severe Femoral Bowing which Required Osteotomy to Insert a Femoral Nail

Lateral Coronal Bowing of Femur and/or Tibia Amplifies the Varus Malalignment of Lower Limb as well as Increases Functional Disability in Patients with Knee Osteoarthritis.

In the present study, we aimed at assessing the effect of femoral and tibial coronal bowing on varus malalignment and Oxford knee score (OKS) at different grades of knee osteoarthritis (OA). This prospective observational study was conducted at a tertiary referral centre in New Delhi, India. Consecutive patients presenting to the "knee OA" outpatient clinics were invited to take part in the study conducted over a 12-month period. All consented patients underwent long-leg standing alignment radiographs using standardised technique and patient reported knee pain and function were recorded using Oxford knee score. The following radiological parameters were measured from weight-bearing long-leg radiographs of 824 varus aligned limbs via a morphometric software (Matlab R2009a) (1) hip-knee-ankle angle (HKAA), (2) femoral bowing, (3) tibial bowing. The knees were graded according to Kellegren and Lawrence grade (K&L) and OKS was recorded. 3 groups of HKAA were made based on the angle, A (0° to - 3°), B (- 3° to - 10°) and C (< - 10°). Both the femoral and tibial bow were also categorized into three groups depending upon the angle; in-range (- 2° to + 2°), varus (< - 2°), valgus (> + 2°). The mean (± SD) of HKAA, femoral bow and tibial bow of the whole cohort was - 6.97° ± 5.64°, - 1.54° ± 4.31° and - 1.96° ± 3.5°, respectively. An increase in the lateral bow of both femur and tibia was seen with an increase in the severity of OA. A consequent increase in the varus malalignment was observed with an increase in the lateral bow of both femur as well as the tibia at all grades of OA, with significant correlation observed between HKAA with Femoral bowing and HKAA with tibial bowing. The mean OKS for femoral bow, in-range, varus and valgus was 30.6 ± 11.5, 21.3 ± 11.5 and 35.3 ± 11.4, respectively, and for tibial bow, in-range, varus and valgus was 27.6 ± 11.5, 26. ± 11.5 and 28 ± 11.4, respectively. The difference in the mean OKS was observed to be significant when the varus bow group was compared to in range as well as valgus group (p < 0.01) for both femur and tibia for all the grades of OA. The present study shows a significant correlation between varus malalignment and the bowing of extremities. Varus coronal bowing of both femur and tibia were seen to have significantly lower mean OKS as compared to valgus bowing or in-range bowing at all grades of knee OA.

Influence of Intraoperative Medial Collateral Ligament Bony Avulsion Injury on the Outcome of Primary Total Knee Arthroplasty

BackgroundThe purpose of this study is (1) to find the clinical and radiological outcome of intraoperative bony avulsion of medial collateral ligament (MCL) treated with screw and washer construct and (2) to predict the preoperative factors which may contribute to the avulsion-type MCL injury during primary total knee arthroplasty (TKA). MethodsIntraoperative MCL avulsion injury occurred in 46 (0.8%) of the 4916 consecutive primary TKA from January 2011 to December 2015. After exclusion, the 41 knees were matched 1:2 with controls without MCL injury and compared for the various clinical, radiological, and functional parameters. The clinical parameters analyzed were age, gender, body mass index, preoperative diagnosis like osteoarthritis or rheumatoid arthritis, range of motion, sagittal deformity, and vitamin D levels. The radiological parameters calculated were coronal deformity, proximal tibial varus angle, distal femur valgus angle, joint line congruence angle, posterior tibial slope, “cup and saucer” morphology, presence or absence of knee subluxation, tibia vara, and femoral bowing. The preoperative and postoperative Knee Society Score and Knee Society Functional Score were analyzed. Complications or revisions, if any, were noted during the follow-up. Multivariate logistic regression analysis was used to predict the preoperative risk factors for MCL avulsion injury. ResultsAt a mean follow-up of 58.4 ± 19.3 months, there were no radiological or physical examination findings of instability. Compared to the preoperative disability, there was a statistically significant improvement in clinical scores (Knee Society Score and Knee Society Functional Score) in the final follow-up (P < .001) in both cases and the control group. The mean preoperative coronal deformity was 170.6 ± 6.96 in the study group and 167.7 ± 4.3 in the control group (P = .021). The mean preoperative tibial slope was 10.5 ± 4.9 in the study group and 7.91 ± 4.15 in the control group (P = .003). The preoperative knee subluxation was present in 48.8% knees (P < .001) and “cup and saucer” morphology in 68.3 knees (P < .001) in the study group. The adjusted odds of MCL avulsion injury were greater for severe varus deformity (odds ratio [OR] 1.462, 95% confidence interval [CI] 1.15-1.86), knee subluxation (OR 39.78, 95% CI 3.78-418.86), and “cup and saucer” morphology (OR 33.11, 95% CI 5.69-192.66). ConclusionIntraoperative MCL bony avulsion injury can be managed successfully with screw and washer construct without the need for increased prosthetic constraint in primary TKA. The presence of severe varus deformity, knee subluxation, and “cup and saucer” morphology tend to have an increased chance of MCL avulsion injury.

Age-related dynamic deformation of the femoral shaft and associated osteoporotic factors: a retrospective study in Chinese adults.

The purpose of this study was to determine whether morphological parameters of the femoral shaft are in age-related deformation and identify correlations between parameters of femoral cortical thickness and femoral shaft bowing. One hundred twenty patients (mean 50years, range 18~104years) who had received standard long-standing anteroposterior and femoral lateral radiographs from October 2016 to October 2019 were included in this retrospective study. The sagittal femoral bowing angle (sFBA), sagittal femoral cortical index (sFCI), coronal femoral bowing angle (cFBA), and coronal femoral cortical index (cFCI) were measured by two orthopaedists separately. All the participants' demographic data, including age, sex, body laterality, height, and weight, were collected. The Student's t test, Mann-Whitney U test, two-way ANOVA, Pearson correlation, and multiple linear regression were used in the statistical analysis. The mean age of the male and female participants was 46.95 ± 15.25 and 52.22 ± 15.61years, respectively. Two-way ANOVA revealed that females had a significantly lower sFCI than males at the right side (P < 0.05). There were no significant interactions between sex or body laterality and the sFBA, cFBA, sFCI, and cFCI groups (P > 0.05). Pearson correlation revealed that sFCI was strongly correlated with sFBA (r = - 0.535, P < 0.05) and cFBA (r = - 0.535, P < 0.05). Multiple linear regression analysis demonstrated that both age (β = 0.304 and 0.308 respectively) and sFCI (β = - 0.322 and - 0.414 respectively) were two independent predictors associated with sFBA and cFBA respectively. The femoral shaft bowing of the Chinese population was positively correlated with ageing, whereas the sagittal femoral cortical thickness negatively correlated with ageing. A high FBA occurred in femoral shafts with a low sFCI, which revealed that femoral shaft bowing was associated with femoral cortical thickness. During femur-related surgery in older patients, more attention should be paid to these femoral morphological changes.

Femoral Bowing and Femoral Neck-Shaft Angle Evaluation Can Reduce Atypical Femoral Fractures in Osteoporotic Patients: A Scientific Report.

Bisphosphonates (BPs) are the mainstay of osteoporosis treatment due to their safety and efficacy. There is evidence that BPs medication may be complicated by atypical femoral fractures (AFFs). Prolonged administration of BPs is even more strongly associated with AFFs. AFF is a relatively rare complication of BPs when taking into account the huge population worldwide that benefits from this pharmacotherapy. AFF is, however, a serious complication of BPs treatment, which includes prolonged healing time and high revision rate when operative treatment is required. Less frequently, AFFs occur even without BPs administration, while these fractures have all the characteristics of “stress” or “insufficiency” fractures. The critical point of view in AFFs pathogenesis seems to be not only the biology of cortical bone, but also the mechanical issue. It has been proven that BPs, glucocorticoids and proton pump inhibitors (PPIs) can cause bone turnover suppression and affect the biological parameter of AFFs pathogenesis. Specific mechanical femoral bone properties predispose to AFFs pathogenesis. Several studies have already reported that increased femoral bowing > 5.250 degrees or decreased femoral neck-shaft angle <125 degrees, are associated with increased risk for diaphyseal and subtrochanteric AFFs respectively, regardless of BPs uptake. If these two parameters are simultaneously present, the probability for AFFs occurrence increases dramatically. Our scientific report, which is based on the current evidence about AFFs, is that if both femoral bowing angle and femoral neck-shaft angle are evaluated before BPs administration, this intervention may reduce the incidence of AFFs. Thus, in cases with excessive lateral femoral shaft bowing or very small femoral neck-shaft angle, the prescription of another anti-osteoporotic treatment than BPs should be recommended. If, however, BPs can’t be avoided, clinicians should be aware of the fact that long-term administration may be implicated with AFFs occurrence. In these cases, short term BPs administration with timely drug holiday between three and five years may be reasonable. Finally, roentgenographic evaluation of both femurs every six months and medical reference in case of any emerging thigh pain are also logical interventions to prevent and reduce AFFs.

The Influence of Demographic Factors on the Location of Bisphosphonate-related Atypical Femoral Fractures.

The location of bisphosphonate-related atypical femoral fractures (AFFs) is related to the femoral bow. Other factors that might also be related to the distribution of AFFs are not well studied. In this study, we attempt to define the demographic factors that influence the distribution AFFs in our local population. The medical records of all the patients diagnosed with AFFs treated in our institution between 2008 and 2017 were retrospectively reviewed and divided based on fracture location into subtrochanteric and mid-shaft groups. Demographic data were collected and compared between the two groups. Independent factors affecting the location of AFFs were identified via multivariate analysis. Seventy-nine AFFs in 71 patients were included. Thirty-two fractures occurred at the subtrochanteric region and 47 occurred at the mid-shaft. Age, bone density, anterior femoral bow and lateral femoral bow were significantly different between the two groups, whereas height, weight, body mass index, presence of prodromal symptoms, type and duration of bisphosphonates were not significantly different. Multivariate analysis showed anterior femoral bow was the only independent factor associated with the location of AFFs. Anterior femoral bow is the only factor that can predict the location of AFFs. In our population, other demographic factors were not found to be predictive.

Clinical outcomes of using contralateral-side laterally bent intramedullary nails in atypical femur fractures with femoral bowing.

This study aimed to evaluate the clinical outcomes of using contralateral-side laterally bent intramedullary nails (IMNs) in bowed atypical femur fractures (AFFs). We retrospectively reviewed bowed AFFs treated with contralateral-side laterally bent IMNs. In total, 20 patients with 25 cases of AFFs were included. Surgical outcomes including bone union time, complications, femoral bowing, and leg length discrepancy (LLD) were evaluated. We evaluated the surgical safety of performing contralateral-side intramedullary nailing with its intraoperative and postoperative complications and compared the LLD. The average age was 76.8years (range 67-86years), and all of patients were female. There were 10 cases of complete AFFs and 15 cases of incomplete AFFs. Fourteen patients (70%) had a history of bisphosphonate (BP) use with an average of 74.5months of its use. In the complete AFF cases, reduction of the fractures was tried to restore the patients' normal anatomical geometry. The average lateral gap was 0.6mm (0-1mm), and the average medial gap was 1.6mm (1-3mm). All cases achieved bone union without secondary intervention. There were no intraoperative fractures or postoperative complications. The average bone union time was 22.0weeks and 9.2weeks in complete and incomplete AFFs, respectively. The average preoperative femoral bowing seen in the coronal and sagittal planes was 10.1° and 16.1°, respectively, while the average postoperative bowing was 6.6° and 11.3°, respectively. The average change of angle was 3.5° in the coronal plane and 4.8° in the sagittal plane. The mean change of LLD was 5.7mm. The use of contralateral-side laterally bent IMNs in treating bowed femurs showed excellent clinical outcomes without complications. In severely bowed femurs, this technique can be safe and useful.

Revision arthroplasty with rotating hinge systems for total knee arthroplasty instability.

Restoring stability after total knee arthroplasty (TKA) and improving joint function using acemented rotating hinge system. Ligament instability and/or osseous defects (including Anderson Orthopaedic Research Institute [AORI] classification typeII defects) after primary TKA or TKA revision surgery. Distal femoral or proximal tibial bowing requiring implant systems that provide femoral or tibial offset stems. Persistent periprosthetic infection. Poor therapeutic compliance. AORI typeIII defects. Medial arthrotomy. Femoral and tibial component removal with small saw blades and chisels. Intramedullary alignment for the tibial and femoral cuts. Debridement and removal of membranes and cement remnants. Reconstruction of joint line and correct TKA alignment. Trial reduction. Cement fixation. Unrestricted range of motion, partial weight bearing for 4weeks. Between 2012 and 2013, 18patients suffering from ligament insufficiency after TKA were revised using the described system and included in aprospective study protocol. The mean follow-up was 37months (range 30-46months). There was asignificant improvement of the Oxford Knee Score (OKS) from 19 (range 7-29) preoperatively to 29 (range 10-45) postoperatively (p = 0.004). The Knee Society Score (KSS) knee assessment subscore improved from 35 (range 9-70) to 67 (range 35-97) (p = 0.002) and the pain score from 7 (range 0-50) to 24 (range 0-50) (p = 0.008).

Biological activity is not suppressed in mid-shaft stress fracture of the bowed femoral shaft unlike in "typical" atypical subtrochanteric femoral fracture: A proposed theory of atypical femoral fracture subtypes.

We have investigated mid-shaft stress fractures of the bowed femoral shaft (SBFs), well before the first report of an association between suppression of bone turnover and atypical femoral fractures (AFFs). Although all cases of SBF meet the criteria for AFF, SBFs can also occur in patients with no exposure to bone turnover suppression-related drugs (e.g., bisphosphonates). Using bone morphometry and biomechanical analyses, we devised a theory of AFF subtypes, dividing AFFs into fragility SBFs in the mid-shaft and "typical" subtrochanteric AFFs caused by suppressed bone turnover. The aim of this multicenter prospective study was to provide evidence for this novel concept in terms of biological activity. The study was conducted at 12 hospitals in Japan from 2015 through 2019. Thirty-seven elderly women with AFF were included and classified according to location of the fracture into a mid-shaft AFF group (n=18) and a subtrochanteric AFF group (n=19). Patient demographics and clinical characteristics were investigated to compare the two groups. The main focus was on histological analysis of the fracture site, and bone metabolism markers were evaluated to specifically estimate biological activity. All patients in the subtrochanteric AFF group had a history of long-term (>3years) exposure to specific drugs that have been reported to cause AFF, but 5 of the 18 patients in the mid-shaft AFF group had no history of exposure to such drugs. Femoral bowing was significantly greater in the mid-shaft AFF group (p<0.001). In the histological analysis, active bone remodeling or endochondral ossification was observed in the mid-shaft AFF group, whereas no fracture repair-related biological activity was observed in the majority of patients in the subtrochanteric AFF group. Levels of tartrate-resistant acid phosphatase-5b and undercaroxylated osteocalcin were significantly lower in the subtrochanteric AFF group (p<0.05). The possibility of our devised AFF subtype theory was demonstrated. Biological activity tends not to be suppressed in mid-shaft SBFs unlike in "typical" subtrochanteric AFFs involving bone turnover suppression. Although validation of the proposed theory in other populations is needed, we suggest that the pathology and treatment of AFFs be reconsidered based on its subtype.

Factors Influencing the Valgus Cut Angle-during Total Knee Arthroplasty-in Indian Population.

The number of total knee arthroplasties performed in India and the world is increasing exponentially. The valgus cut angle (VCA) of the distal femur decides the final alignment achieved in the coronal plane. Little data are available regarding the ideal value for an Indian population and there is little consensus whether to use a single value for all knees or to individualize the angle for each patient. The parameters that can influence the value of this angle have not been evaluated thoroughly.Standard long leg X-ray (orthoscanogram) was used to calculate the VCA in 302 lower limbs (160 patients). Only Indian patients were included in the study; knees with bowed femurs were excluded. VCA, femoral length, medial hip offset, neck shaft angle, and hip knee ankle angle were measured manually. Demographic data such as gender, height, and weight were extracted from hospital charts. The correlation of VCA with the various parameters was evaluated using Pearson's correlation and its significance assessed using the independent Student's 't' test.The average VCA was 7.4 degrees (range: 4-11 degrees). Age, gender, height, hip knee ankle angle (alignment) and body mass index (BMI) had no influence on the VCA. The neck shaft angle (r = -0.520, p = < 0.0001) and hip medial offset (r = 0.223, p = < 0.0001) were the only two parameters significantly and independently influencing the value of VCA. There is a wide variation in the value of VCA in the Indian population. Choosing a fixed VCA will lead to significant number of knees aligned outside the ideal 0- to 3-degree hip knee ankle angle. The neck shaft angle and the medial hip offset are the only two factors that influence the VCA. The patients' height, preoperative deformity, gender, and BMI had no influence on the VCA.

Gender difference in bowing of the sagittal femoral morphology measurement using magnetic resonance imaging.

The importance of femoral sagittal bowing on total knee arthroplasty (TKA) has not been actively discussed. Femoral sagittal bowing can lead to cortex damage, fractures, or femoral malalignment. Therefore, the purpose of this study was to evaluate femoral sagittal bowing at different segments of the femur in the Korean population, and to discuss the implications on total knee arthroplasty. Differences in the morphology of femoral sagittal bowing for 978 patients-829 women and 148 men-were evaluated using magnetic resonance imaging. The angle between the femoral mechanical axis and the anterior cortex line was measured for all the patients. In addition, the gender difference in femoral sagittal bowing was investigated. The angle of femoral sagittal bowing with the mechanical axis was 2.8˚ ± 2.2˚. The angles for femoral sagittal bowing were 2.9˚ ± 2.2˚ and 2.3˚ ± 2.6˚ for females and males, respectively. Thus, a gender difference was found in the femoral sagittal bowing (p < 0.05). Excessive sagittal bowing of the femur can affect the final sagittal position of the femoral component, and this has implications for implant design selection. We recommend that surgeons accurately perform pre-operative evaluation of femoral bowing to prevent potential malalignment, rotation, and abnormal stresses between the femur and implant.

MON-060 P-450 Oxidoreductase Deficiency with Antley Bixler Phenotype: A Novel Mutation

IntroductionWe present first case of 46 XY Disorder of Sex Development (DSD) from India due to P-450 Oxidoreductase Deficiency with Novel variant (p.Ala541Thr) in a heterozygous state.Case Discussion6 months old boy presented with ambiguous genitalia since birth. No history of neonatal crisis, failure to thrive and pigmentation of skin, maternal virilisation or drug ingestion during pregnancy. On examination: weight 6.2 Kg (3rd centile), height 64 cm (3rd centile), MPH-170 (25-50th centile), head circumference 38 cm (−2.7 SD), vitals stable, trigonocephaly with fused anterior and posterior fontanelle, prominent pointed forehead, midfacial hypoplasia, up slanting eyes, hypertelorism and low set ears were present. Genitalia: 1.5 cm phallus like structure with foreskin, chordee, single perineal opening in form of peno-scrotal hypospadias, bifid scrotum with poor rugosity and poor pigmentation and both gonads (1 ml) were palpable in labio-scrotal fold with external masculinization score (EMS), 6/12 and Prader stage 4.Investigations showed normal electrolytes and blood sugar, High basal ACTH, post stimulation cortisol 14mcg/dl, Basal 17-OHP was 8.6 ng/ml and post stimulation 12ng/ml, with low DHEAS 36.4 mcg/dl and androstenedione 0.42 ng/ml, LH 16.09 mIU/ml (elevated), FSH 2.97 mIU/ml (normal) and low Testosterone for his age. T/DHT 9.6 (normal<10) and Testosterone /Androstenedione ratio 0.95 (normal >0.8). Abdominal and Pelvic imaging showed normal adrenal glands and absent female internal genitalia, bilateral testis in labio-scrotal fold (right testis-6x6.5x11 mm, left testis-6.6x7x10 mm), corpora cavernosa and bifid scrotum. NCCT Head showed metopic craniosynostosis with trigonocephaly and hypotelorism. Skeletal survey showed bowing of femora. 20 cell Karyotype of peripheral blood lymphocyte was 46 XY. NGS was done of the POR gene, which revealed a heterozygous missense variation in exon 13 of the POR gene variant (p.Ala541Thr) which has not been reported yet.The patient was initiated hydrocortisone, fludrocortisone, DHT gel and corrective surgery is planned.Clinical learningAlthough in PORD classically the inheritance is generally autosomal recessive, but manifesting heterozygotes are not uncommon1. This case also shows the value of Next gen sequencing and the role it can play in DSD1. Scott RR, Gomes LG, Huang N, Van Vliet G, Miller WL. Apparent manifesting heterozygosity in P450 oxidoreductase deficiency and its effect on coexisting 21-hydroxylase deficiency. J Clin Endocrinol Metab. 2007;92:2318–2322

The advantage of navigation for knee with lateral femoral bowing in total knee arthroplasty.

We have analyzed the surgical outcomes of primary total knee arthroplasty (TKA) using computer-assisted (CA) navigation in terms of postoperative coronal alignment depending on preoperative lateral femoral bowing. We conducted a retrospective study of patients who have undergone navigated primary TKA from January 2016 through January 2020. Two hundred and ninety-nine cases with lateral femoral bowing of 3° or less were assigned to group 1, 95 cases of lateral femoral bowing between 3° and 5° were assigned to group 2, and 89 cases with lateral femoral bowing of more than 5° were assigned to group 3. The postoperative mechanical hip-knee-ankle (mHKA) angle was measured from scanograms, which were taken 3 months after surgery. The appropriate range of coronal alignment was set as 0 ± 3°. The number of outliers of mHKA occurred was 31 cases (10.4%) in group 1, 17 cases (17.9%) in group 2, and 17 cases (19.1%) in group 3. There was a significant correlation between the degree of lateral femoral bowing and the occurrence rate of mHKA outliers. Multiple variables logistic regression analysis showed occurrence rate of outliers in group 3 to be 2.04 times higher than group 1. After adjusting the patient's age, sex, body mass index, and preoperative HKA deformity, the occurrence rate of outliers in group 3 was still 1.96 times higher than group 1. The benefit of CA navigation during TKA in obtaining coronal alignment within 0 ± 3° may be lessened when the preoperative lateral femoral bowing is severely advanced.

Coronal shaft bowing of the femur affects varus inclination of the surgical transepicondylar axis in varus knee osteoarthritis.

This study investigated the relationship between femoral shaft bowing and the orientation of the surgical transepicondylar axis (TEA) in the coronal plane in varus knee osteoarthritis (OA). A total of 82 knees scheduled to undergo total knee arthroplasty (TKA) for the treatment of varus knee OA were enrolled. The hip-knee-ankle angle (HKA) was measured preoperatively on anteroposterior whole-leg standing radiographs. The lateral angle between the TEA and the mechanical axis of the femur (MA-TEA) was measured in the coronal plane from preoperative computed tomography (CT) images. Femoral shaft bowing was measured on CT images. Pearson's correlation coefficient was used to examine the correlation of the MA-TEA with the HKA and femoral shaft bowing. The MA-TEA correlated negatively with the HKA (r = - 0.321, P < 0.01) and positively with femoral shaft bowing (r = 0.415, P < 0.01). The TEA changed to varus as femoral shaft bowing increased in patients with varus knee OA. This suggests that the TEA is not always the centre of the rotational axis of the femur after TKA. In addition, the TEA may not be useful as a consistent parameter in the coronal plane in patients with increasing femoral shaft bowing. III.

Preoperative planning of constitutional varus alignment in patients with varus knees and coronal femoral lateral bowing

Objective: To investigate the preoperative constitutional varus alignment (CA) inpatients withvarus osteoarthritic knees and coronal femoral lateral bowing (FLB) by comparing the femoral axis of the patients and volunteers' with straight femoral shaft (SFS) and healthy knees, which would be used to guide the selection of valgus correction angle(VCA) of distal femur in total knee anthroplasty (TKA). Methods: From January 2018 to December 2018, 45 nonconsecutive patients (90 knees) with varus osteoarthritic knees and obvious FLB (>5°) received primary TKA,and 50 limbs with healthy knees and SFS in 25 volunteers were studied at Xinqiao Hospital.The medial proximal femoral angle (MPFA) and anatomic lateral distal femoral angle (a-LDFA) were measured and compared between the two groups.The VCA formed by distal femoral mechanical axis (DMA) and distal femoral anatomic axis (DAA) in patients and the VCA based on neutral mechanical axis (NMA) in volunteers were also compared. The Pearson's correlation analysis was performed between the angle of bowing (α) and the VCA based on NMA in patients. The measurement data was compared with t test between the two groups. Results: The results showed that the MPFA and the a-LDFA were not significantly different between the volunteers with SFS and patients with FLB (MPFA:84.9°±3.7° vs 85.6°±1.8° and a-LDFA:81.7°±1.7° vs 81.2°±1.6°, t=1.26, 1.70, both P>0.05). The VCA based on NMA in volunteers with SFS was 5.5°±0.6°(4.5°-7.4°), the preoperative DAA-DMA angle was 5.3°±0.7°(4.3°-7.8°) in patients with FLB, there was no significant difference between the two groups (t=1.70, P=0.09). The angle of bowing (α) was 7.9°±2.9° (6°-16°), the VCA based on NMA was 8.4°±1.5°(5°-10°), there was a significantly positive correlation between VCA and α (R=0.607, P<0.01). Conclusion: There is no significantly proximal or distal femoral deformity in patients with varus osteoarthritic knee and FLB (>5°), the degree of the DMA-DAAangle based on the DMA doesn't change with the increasing angular deformity of the bowing, then the bowing would be reserved if the distal femur is cut based on DMA in TKA and the preoperative CA should be restored successfully.

Correlation between cortical thickness and bowing of the femoral diaphysis in healthy elderly people

Purpose: The cortical thickness of the femoral diaphysis is presumed to change with aging due to various mechanical factors, such as bony structure (e.g., femoral bowing, neck anteversion, and condyle shape), lower limb alignment, body weight, load bearing due to movement, and mechanical stimulation by muscles. Above all, the femoral bowing is assumed to be important as one of the mechanical factors correlating with the cortical thickness of the femoral diaphysis. The purpose of this study is to examine the correlation between cortical thickness and bony bowing of the femoral diaphysis, measured three-dimensionally (3D), with high accuracy from CT data of healthy elderly people. Methods: This study was performed based on a protocol approved by the institutional review board of our university. The lower extremities of 54 elderly Japanese volunteers (29 men and 25 women) were included in this study. The average ± SD (range) of age and body mass index (BMI) were 70 ± 5.9 years (60 to 83 years) and 21.6 ± 2.4 kg/m2 (17 to 27 kg/m2), respectively. The participants were not obese and had no history of trauma or other diseases that influence cortical thickness, such as osteometabolic diseases except for primary osteoporosis. They were classified into Kellgren-Lawrence grades 0-1, with no radiographic knee OA. The cortical thickness of the femoral diaphysis was calculated automatically in a 3D space by using Stradwin software (version 5.3; Medical Imaging Group, Machine Intelligence Laboratory, Cambridge Engineering Department, Cambridge, UK), which is available for free download and is a new tool with a demonstrated sub-voxel accuracy in assessing cortical bone properties using routine low-resolution CT [Figure 1]. As the accuracy, it was reported that cortical bone thickness estimates were accurate up to 0.3 mm. The number of measurement points per subject was 5000-8000, depending on femur length. An anatomical coordinate system for the femur was constructed using original software. Twelve assessment regions were created by combining three heights (proximal: 54%-71%; central: 37%-54%; distal: 20%-37%) and four areas of the axial plane (xy-plane) at 90° (medial, anterior, lateral, and posterior) [Figure 2]. The assessment parameter was the average of the cortical thickness data from 200-800 points in each region in the femoral diaphysis, divided by each height and area. When the data were analyzed, standardized values divided by the femoral length (cortical thickness / femoral length), not actual values, were applied. The other evaluation parameter was femoral bowing in the coronal plane and sagittal plane in a 3D space. To accurately define femoral bowing in 3D space, an axial center (AC) was automatically calculated for the 10 respective cross-sectional planes that divide the femoral diaphysis into 11 equal sections in the femoral bony coordinate system. Line A is defined as the line connecting the top of the AC with its bottom. Line B is a perpendicular line from the AC of the maximum bowing point to line A. Femoral bowing in the coronal plane (lateral bowing) is defined by the following equation: Length of line B/length of line A × 100 (%), projected on the XZ plane. Femoral bowing in the sagittal plane (anterior bowing) is defined by the following equation: Length of line B/length of line A × 100 (%), projected on the YZ plane [Figure 3]. To examine the correlation between cortical thickness and femoral bowing, Pearson's correlation coefficient was calculated. The probability level accepted for statistical significance was set at p < 0.05 (version 21; SPSS, Inc., Chicago, IL, USA). Results: The average values of anterior and lateral bowing were 3.19 ± 0.49% and 0.75 ± 0.45%, respectively. The anterior bowing showed a low positive correlation with the posterior area of the proximal diaphysis [Correlation coefficient (CC) = 0.269, p = 0.049], the anterior area of the central diaphysis (CC = 0.372, p = 0.006), the posterior area of the central diaphysis (CC = 0.343, p = 0.011), and the posterior area of the distal diaphysis (CC = 0.351, p = 0.009). The lateral bowing was negatively correlated with the lateral area of the central diaphysis (CC = -0.317, p = 0.019) and the lateral area of the distal diaphysis (CC = -0.342, p = 0.011). Conclusions: In healthy elderly people, the femoral bowing was predominantly confirmed in the sagittal plane. While the anterior and lateral bowing showed a correlation with femoral cortical thickness, the trends were reverse (anterior bowing - positive correlation; lateral bowing - negative correlation). In Curry ’s rule, the periosteum side and medullary cavity side are the compression side and tension side, respectively. The balance of remodeling between “bone formation by compression” and “bone resorption by extension” was different depending on the region, and may be related to cortical thickness and bowing of the femoral diaphysis.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Secular evolution of femoral morphology from a clinical perspective.

Intramedullary nailing is the surgical method of choice for the treatment of proximal femur or femoral shaft fractures. Implant manufacturers aim to design implants fitting for the broadest possible population segment. As complete morphological data sets of long bones are not widely available, anatomical collections of historical dry bone specimens may represent abundant additional sources of morphological three-dimensional (3D) data for implant design, provided they are consistent with present populations. This study aims to investigate secular trends and age-related changes of femoral morphology of the Caucasian population over the past 800 years. Computer graphical measurements of 3D-datasets of right and left femora derived from computed tomography (CT) scans, representative of the present Caucasian population, were compared to computer graphical measurements of 3D-datasets of right and left femora derived from CT scans of specimens from a historical medieval European bone collection. Clinically relevant parameters of historical medieval European femora were found mostly consistent with correlative data of the present Caucasian population. Additionally, for some of the evaluated parameters, particularly anteversion, morphological differences significantly correlated to individual age and sex could be identified, whereas other parameters such as caput-collum-diaphyseal angle or radius of anterior femoral bowing were not correlated to individual age or sex. The findings suggest that more recent historical specimen collections may be a convenient and easily accessible source of new 3D morphological data, as well as to complement existing data, to be used by researchers and manufacturers for the development of intramedullary femoral nails.

Coronal Alignment of the Lower Extremity: A Gender-Based Radio-Graphic Analysis in Indian Patients.

Variation in the shape of the femur and tibia has been shown to influence hip-kneeankle-axis angle (HKAA) and bears a role in reconstructive surgeries such as total knee arthroplasty (TKA). However, data on the axial alignment of the lower extremity specific to sex largely remains unavailable. Thus, we conducted a study with an aim to measure alignment and calculate differences in both the sexes in Indian population. The following radiological parameters were measured from weight-bearing long leg radiographs of 966 limbs of Indian subjects via a morphometric software (Matlab R2009a) (1) Hip-Knee-Ankle angle (HKAA), (2) femoral bowing, (3) tibial bowing, (4) condylar plateau angle (CPA). The knees were classified according to the Kellegren and Lawrence grading and the differences between both the sexes were calculated with appropriate statistical tests. 56.04% of the subjects were female. An increase in the mean age was observed for both the genders with an increase in the severity of OA. Height did not show any significant association with the alignment of the limb. The mean HKAA observed was - 5.88° ± 0.35° in females and - 4.99° ± 0.41° in males. The overall mean femoral bow and tibial bow was - 1.26° ± 0.24°, - 1.60° ± 0.18° in females and - 1.09 ± 0.28, - 1.47° ± 0.21° in males. The mean condylar plateau angle was higher in females - 2.67 ± 0.34 as compared to males - 2.35° ± 0.39°. A greater lateral bow was seen in males at higher grades of OA for femur and at lower grades of OA for tibia. This study provides gender-based differences in the various axial radio-graphic parameters in a long leg radio-graphs in Indian population which might help in a better understanding of the etiopathogenesis of osteoarthritis and also help planning and execution of reconstructive surgeries such as TKA.