Associations between femoral 3D curvature and sagittal imbalance of spine.

Background: The sagittal imbalance (SI) of spine triggers compensatory mechanisms (CMs) of lower extremity (LE) to restore trunk balance. These CMs can cause long-period stress on the femur and may possibly alter the femoral morphology. This cross-sectional observational study aimed to answer the following questions: (a) Do SI subjects exhibit greater femoral bowing compared to subjects with sagittal balance? (b) Are there associations between femoral bowing and CMs of LE in SI subjects? Methods: Subjects who underwent biplanar full body radiographs with the EOS imaging system between January 2016 and September 2021 were recruited. Sagittal parameters included T1-pelvic angle (TPA), pelvic incidence (PI), pelvic tilt (PT), sacral slope, lumbar lordosis (LL), PI-LL, and PT/PI ratio. LE parameters were femoral obliquity angle (FOA), knee flexion angle (KA), and ankle dorsiflexion angle. Femoral bowing was quantified as 3D radius of femoral curvature (RFC). Associations between 3D RFC and the radiographic parameters were analyzed. Results: A total of 105 subjects were included, classified into balance group (TPA < 14°, n = 40), SI group (TPA ≥ 14° and KA <5°, n = 30), and SI with knee flexion group (TPA ≥ 14° and KA ≥ 5°, n = 35). 3D RFC was significantly lower in SI with knee flexion group compared to the other two groups (both p < 0.001). Stepwise linear regression showed that age, SI and knee flexion, femoral length (FL), FOA, and KA were independent predictors for 3D RFC. Conclusion: Greater femoral bowing is observed in subjects with SI and knee flexion compared to the balanced population. CM parameters, including KA and FOA, are associated with 3D RFC. Further longitudinal study is needed to investigate the cause-and-effect relationship between SI, CMs of LE, and femoral bowing.

Correlation between Femoral Neck Version, Sagittal Femoral Bowing Angle and Sagittal Offset of the Femoral Head from the Distal Femur Axis in an Osteological Collection.

Aim: Radiographic analysis of lower limb alignment is crucial for the planning and evaluation of deformity correction. Assessment in the sagittal plane is often overlooked compared with the coronal plane for a variety of reasons. We aimed to investigate the relationship between the femoral head in the sagittal plane and femoral neck version in the axial plane, and how sagittal femoral bowing angle (sFBA) may contribute. Materials and methods: Twenty-five each of high (1-2 standard deviations above mean), normal (2.5° below to 2.5° above the mean), and low (1-2 standard deviations below the mean) version femurs were randomly selected from an osteological collection database, photographed and measured for sFBA and sagittal offset of femoral head from the distal femur axis. Lines were drawn within the proximal and distal quartiles of the shaft to create sFBA. The offset of the distal quartile line and the femoral head was also measured. High intra- and inter-observer correlations were established. The relationship between parameters was assessed using the Pearson coefficient (r). Results: Sagittal offset of the femoral head from the distal femur axis was found to be highly correlated with sFBA (r = 0.78), and only mildly with femoral neck version (r = 0.52). Sagittal femoral bowing angle and femoral neck version share no relationship (r = 0.05). Conclusions: Neither the sFBA nor sagittal femoral head offset is strongly associated with femoral neck version. Clinical significance: Our data reinforce the need for long leg lateral films to include the femoral head in sagittal deformity analysis, as imaging limited to the knee will not account for the effect of bowing on femoral head position. How to cite this article: Ho D, Liu RW, Mcclure PK. Correlation between Femoral Neck Version, Sagittal Femoral Bowing Angle and Sagittal Offset of the Femoral Head from the Distal Femur Axis in an Osteological Collection. Strategies Trauma Limb Reconstr 2023;18(1):12-15.

Surgical strategy of the treatment of atypical femoral fractures.

The atypical femoral fracture (AFF) has been attracting significant attention because of its increasing incidence; additionally, its treatment is challenging from biological and mechanical aspects. Although surgery is often required to manage complete AFFs, clear guidelines for the surgical treatment of AFFs are currently sparse. We reviewed and described the surgical treatment of AFFs and the surveillance of the contralateral femur. For complete AFFs, cephalomedullary intramedullary nailing spanning the entire length of the femur can be used. Various surgical techniques to overcome the femoral bowing common in AFFs include a lateral entry point, external rotation of the nail, and the use of a nail with a small radius of curvature, or a contralateral nail. In the case of a narrow medullary canal, severe femoral bowing, or pre-existing implants, plate fixation may be considered as an alternative. For incomplete AFFs, prophylactic fixation depends on several risk factors, such as a subtrochanteric location, presence of a radiolucent line, functional pain, and condition of the contralateral femur; the same surgical principles as those in complete AFFs can be applied. Finally, once AFF is diagnosed, clinicians should recognize the increased risk of contralateral AFFs, and close surveillance of the contralateral femur is recommended.

Risk Factors Associated with Intraoperative Iatrogenic Fracture in Patients Undergoing Intramedullary Nailing for Atypical Femoral Fractures with Marked Anterior and Lateral Bowing.

Background and objectives: Iatrogenic fractures are potential complications during intramedullary (IM) nailing for atypical femoral fractures (AFFs). The risk factors associated with iatrogenic fractures remain unclear, although excessive femoral bowing and osteoporosis are hypothesized to be contributing factors. The present study aimed to determine the risk factors for the occurrence of iatrogenic fractures during IM nailing in patients with AFFs. Materials and Methods: This retrospective cross-sectional study evaluated 95 patients with AFF (all female; age range: 49-87 years) who underwent IM nailing between June 2008 and December 2017. The patients were divided into two groups: Group I (with iatrogenic fracture: n = 20) and Group II (without iatrogenic fracture: n = 75). Background characteristics were retrieved from medical records and radiographic measurements were obtained. Univariate and multivariate logistic regression analyses were performed to identify risk factors for the occurrence of intraoperative iatrogenic fractures. Receiver operating curve (ROC) analysis was conducted to determine a cut-off value for the prediction of iatrogenic fracture occurrence. Results: Iatrogenic fractures occurred in 20 (21.1%) patients. The two groups exhibited no significant differences regarding age and other background characteristics. Group I exhibited significantly lower mean femoral bone mineral density (BMD) and significantly greater mean lateral and anterior femoral bowing angles than Group II (all p < 0.05). There were no significant differences in AFF location, nonunion, and IM nail diameter, length, or nail entry point between the two groups. In the univariate analysis, femoral BMD and lateral bowing of the femur differed significantly between the two groups. On multivariate analysis, only lateral bowing of the femur remained significantly associated with iatrogenic fracture occurrence. The ROC analysis determined a cut-off value of 9.3° in lateral bowing of the femur for prediction of iatrogenic fracture occurrence during IM nailing for AFF treatment. Conclusions: The lateral bowing angle of the femur is an important predictive factor for intraoperative iatrogenic fracture occurrence in patients undergoing IM nailing for AFF treatment.

Influence of femoral bowing on stress distribution of the proximal femur: a three-dimensional finite element analysis.

BACKGROUND: Whether femoral bowing or its direction has a mechanical effect on the proximal femur is unclear. This study aimed to define the changes in stress distribution in the proximal femur associated with femoral bowing using finite element analysis. METHODS: We created four femoral models: original, entire lateral bowing, entire anterior bowing, and the middle of both (50% anterolateral bowing) from computed tomography data of women with standard bowing. Each model's stress distribution was compared by two-layering the stress distribution under loading conditions during walking. We also evaluated displacement vectors. RESULTS: In all directions of femoral bowing, the stress increased in the femoral neck and the femoral trochanter in the 50% anterolateral bowing. The direction of deformation of the vector for the femoral head increased anteroinferiorly in the 50% anterolateral bowing. CONCLUSIONS: This study showed that the stress distribution at the proximal femur shifted laterally. The high-stress area increased at the femoral neck or trochanter due to increasing femoral bowing. Femoral bowing also increases the anteroinferior vector in the femoral head. This study provides valuable insights into the mechanism of proximal femoral fractures in older adults.

Proximal external femoral torsion increases lateral femoral shaft bowing: a study based on 3D CT reconstruction models.

PURPOSE: Femoral bowing influences the genesis and management of knee osteoarthritis (OA). The aim of this study was to investigate the relationship between the femoral torsion angle (FTA) and femoral bowing angle (FBA) in a southern Chinese population. It was hypothesized that a greater FTA would lead to a greater lateral FBA. METHODS: A total of 381 lower extremities from 381 osteoarthritic patients (298 women, 83 men; 201 left, 180 right; mean age 66.5 ± 8.9 years) were retrospectively reviewed. Age, sex, body mass index (BMI), side, height, femoral length (FL), hip-knee-ankle angle (HKA) and FTA were set as FBA-related factors. The three-dimensional (3D) FBA, the angle between the anatomical axis of the proximal femur and the anatomical axis of the distal femur in the plane they form, and its projection on the coronal (lateral FBA) and sagittal (anterior FBA) planes were measured on 3D computed tomography (CT) models. The correlation of the 3D, lateral and anterior FBAs with each of the FBA-related factors was explored using multiple linear regression analysis. The correlation between the FBA and FTA was explored and verified after using propensity score matching to control for the other FBA-related factors. RESULTS: The mean lateral and anterior FBAs were 5.5°, with 53.5% greater than 5°, and 12.7°, with 70.3% greater than 11°, respectively. 3D FBA was positively correlated with age (Std.Co = 0.113, P < 0.05) and HKA (Std.Co = 0.129, P < 0.05). Lateral FBA was positively correlated with age (Std.Co = 0.118, P < 0.05), female sex (Std.Co = 0.206, P < 0.05), HKA (Std.Co = 0.184, P < 0.05) and FL (Std.Co = 0.220, P < 0.05). Anterior FBA was positively correlated with age (Std.Co = 0.108, P < 0.05) and male sex (Std.Co = 0.108, P < 0.05). When the related factors were balanced between the two groups (NS), FTA did not significantly affect 3D FBA or anterior FBA (NS), while FTA was positively correlated with lateral FBA (Std.Co = 0.165, P < 0.05). CONCLUSION: External torsion of the proximal femur increases the lateral FBA by twisting a partial anterior FBA into a lateral FBA, especially in the female population. If a patient is found to have a large lateral FBA preoperatively, one should be alert to the possibility of a concomitant large FTA, as there are implications for femoral orthopedics, TKA and patellofemoral pressure distribution. LEVEL OF EVIDENCE: III.

Coronal plane femoral bowing in Far East Asians: implications for the strategy of distal femoral resection in total knee arthroplasty.

BACKGROUND: The accuracy of distal femoral resection in intramedullary (IM) guided total knee arthroplasty (TKA) depends on femoral morphology and varies according to individual anatomy. This study aimed to characterise coronal plane femoral bowing in Far East Asians according to age, sex, and severity of varus deformity to identify optimal strategies for distal femoral resection in TKA. METHOD: Femoral anatomical parameters in 656 patients (M/F = 232:424) were assessed using standing long-leg anteroposterior radiography which was fulfilling strict standard. The femur was divided into three longitudinal segments to measure the segmental anatomical axial deviation from the mechanical axis and intersegmental bowing. Coronal plane femoral bowing pattern was categorised based on combined gross bowing and distal bowing. RESULTS: Mean hip-knee-ankle angle; neck-shaft angle; proximal, middle, and distal segmental axial differences; mechanical lateral distal femoral angle; and femur length were 6.7 ± 6.8°, 125.0 ± 5.5°, 5.9 ± 1.7°, 6.1 ± 1.1°, 5.3 ± 1.6°, 88.4 ± 2.6°, and 432.3 ± 23.9 mm in male and 8.4 ± 5.5°, 126.4 ± 5.6°, 5.4 ± 1.5°, 6.6 ± 0.9°, 5.6 ± 1.6°, 89.3 ± 2.6°, and 410.6 ± 23.3 mm in female, respectively. Mean proximal, distal, and gross femoral bowing was 0.3 ± 1.8°, - 0.8 ± 1.8°, and - 0.5 ± 2.9° in male and 1.2 ± 1.6°, - 1.0 ± 1.6°, and 0.2 ± 2.7° in female, respectively. CONCLUSIONS: Grossly straight femur with a straight distal part was the most common femoral bowing pattern in Far East Asians. Distal bowing was proved to be a key factor to choose method for distal femoral resection in TKA. Using IM-guide to achieve accurate distal femoral resection in the femora with distal segmental axial deviation between 4-8° and distal bowing less than ± 1° is considered feasible.

Surgical Transepicondylar Axis Is Not a Reliable Reference when there Was Lateral Femoral Bowing.

OBJECTIVE: The surgical transepicondylar axis (sTEA) is believed to be a consistent reference for femoral rotation axis, and the reliability of its orientation seriously affects the accuracy and outcome of total knee arthroplasty (TKA). This study was designed to investigate the relationship between the orientation of sTEA and femoral bowing angle (FBA) and posterior condylar line (PCL) using three-dimensional (3D) computed tomography (CT) reconstruction models to verify its reliability. METHODS: This study retrospectively collected lower extremity images of 443 southern Chinese osteoarthritic patients (347 women, 96 men; 234 left, 209 right; mean age 66.5 ± 9.3 years) from August 2016 to June 2018. The hip-knee-ankle angle (HKA) was measured on anteroposterior weight-bearing full lower extremity standing radiographs. Measurements on 3D CT models of the femurs included lateral angle between the femoral mechanical axis and sTEA coronal angle, angle between sTEA and distal joint line (distal condylar axis angle, DCA); angle between sTEA and PCL (sTEA axial angle); angle between anatomical axis of proximal femur and anatomical axis of distal femur in the plane they form (actual FBA) and its projection on the coronal (lateral FBA) and sagittal (anterior FBA) planes. The correlations between sTEA coronal angle, sTEA axial angle and actual FBA, lateral FBA, anterior FBA, HKA, DCA were explored using the Spearman correlation test. RESULTS: The mean value of actual FBA is (14.4 ± 3.6)°, of lateral FBA is (6.0 ± 4.0)°, and of anterior FBA is (12.7 ± 3.0)°. The mean value of sTEA coronal angle is (88.7 ± 3.6)°, of sTEA axial angle is (2.1 ± 2.8)°. The sTEA coronal angle was positively correlated with actual FBA (r = 0.320, P < 0.01), lateral FBA (r = 0.448, P < 0.01), anterior FBA (r = 0.113, P < 0.05), HKA (r = 0.482, P < 0.01) and DCA (r = 0.486, P < 0.01). The sTEA axial angle was positively correlated with DCA (r = 0.168, P < 0.01), but not significantly correlated with all FBAs and HKA (NS). CONCLUSION: The sTEA cannot be used as a stable reference when there was an obvious femoral bowing deformity. As the lateral femoral bowing increases, the orientation of sTEA becomes more varus, no matter the knee is varus or valgus.

The position of entry point in total knee arthroplasty is associate with femoral bowing both in coronal and sagittal planes.

Objective: To investigate the femoral entry point of the intramedullary (IM) guiding rod applied to total knee arthroplasty (TKA) in Chinese subjects and the relationship with femoral bowing in the coronal and sagittal planes through three-dimensional (3D) validation methods. Methods: Computed tomography (CT) images of 80 femurs in Chinese subjects were imported into Mimics 19.0 to construct 3D models. All operations were conducted by Rhinoceros software 5.0. The position of the IM rod entry point was assessed by calculating the distance between the entry point and the apex of the intercondylar notch (AIN) in the coronal and sagittal planes. The coronal femoral bowing angle (cFBA) and sagittal femoral bowing angle (sFBA) were also measured. Results: The average optimal entry point was 0.17 mm medial and 12.37 mm anterior to the AIN in males, while it was 0.02 mm lateral and 16.13 mm anterior to the AIN in females. There was a significant difference between males and females in the sagittal plane (t = -6.570, p = 0.000). The mean cFBA was 1.68 ± 2.29°, and the mean sFBA was 12.66 ± 1.98°. The sFBA was strongly correlated with the anterior distance of the proper entry point, and the cFBA was moderately correlated with the lateral distance of the proper entry point. Conclusions: There was a strong correlation between the position of the entry point and the femoral bowing angle in both the coronal and sagittal planes. Thus, to achieve better alignment, the position of the entry point should be measured individually based on femoral bowing.

The accuracy of an extramedullary femoral cutting system in total knee arthroplasty in patients with severe coronal femoral bowing: a radiographic study.

BACKGROUND: Intramedullary (IM) femoral alignment instrument is imprecise for the coronal alignment in total knee arthroplasty (TKA) in patients with severe lateral bowing of the femur, while the extramedullary (EM) alignment system does not depend on the structure of the femoral medullary cavity. The aim of this retrospective study was to compare the accuracy of postoperative limb alignment with the two femoral alignment techniques for patients with severe coronal femoral bowing. METHODS: From January 2017 to December 2019, patients with end-stage knee osteoarthritis and coronal femoral bowing angle (cFBA) ≥ 5° who underwent total knee arthroplasty TKA at our institution were enrolled in the study. The postoperative hip-knee-ankle (HKA) alignment, femoral and tibial component alignment between the IM group and the EM group were compared on 5° ≤ cFBA < 10° and cFBA ≥ 10°. RESULTS: In patients with 5° ≤ cFBA < 10°, no significant differences were observed in the EM group and IM group, including preoperative and postoperative parameters. However, when analyzing the patients with cFBA ≥ 10°, we found a significant difference in postoperative HKA (4.51° in the IM group vs. 2.23°in the EM group, p < 0.001), femoral component alignment angle (86.84° in the IM group vs. 88.46° in the EM group, p = 0.001) and tibial component alignment angle (88.69° in the IM group vs. 89.81° in the EM group, p = 0.003) between the two groups. Compared to the EM group, the IM group presents a higher rate of outliers for the postoperative HKA and femoral components. CONCLUSIONS: The study showed that severe lateral bowing of the femur has an important influence on the postoperative alignment with the IM femoral cutting system. In this case, the application of EM cutting system in TKA will perform accurate distal femoral resection and optimize the alignment of lower limb and the femoral component.

[Effectiveness analysis of lateral condyle sliding osteotomy in total knee arthroplasty for the treatment of lateral femoral bowing deformity].

OBJECTIVE: To investigate the effectiveness of lateral condyle sliding osteotomy (LCSO) in total knee arthroplasty (TKA) for the treatment of lateral femoral bowing deformity. METHODS: The clinical data of 17 patients with lateral femoral bowing deformity treated by LCSO during TKA between July 2018 and July 2020 was retrospectively analysed. There were 3 males and 14 females, with an average of 63.2 years (range, 58-68 years). The etiology of lateral femoral bowing deformity included 12 cases of femoral developmental deformity and 5 cases of femoral fracture malunion. Kellgren-Lawrence classification of knee osteoarthritis was 4 cases of grade Ⅲ and 13 cases of grade Ⅳ. The preoperative hip-knee shaft was 9.5°-12.5° (mean, 10.94°). The disease duration was 3-25 years (mean, 15.1 years). The mechanical lateral distal femur angle (mLDFA), hip-knee-ankle angle (HKA), and mechanical axis deviation (MAD) of the distal femur were measured before operation and at last follow-up to evaluate the correction of extra-articular deformities in the joints and the recovery of mechanical force lines of the lower extremities. The knee society score (KSS) knee score and function score, visual analogue scale (VAS) score, knee joint range of motion (ROM) were used to evaluate effectiveness. The knee varus/valgus stress test and osteotomy healing by X-ray films were performed to evaluate the joint stability and the safety of LCSO. RESULTS: All incisions of the patients healed by first intention after operation, and there was no early postoperative complication such as infection of the incision and deep vein thrombosis of the lower extremities. All 17 patients were followed up 12-36 months, with an average of 23.9 months. The osteotomy slices all achieved bony healing, and the healing time was 2-5 months, with an average of 3.1 months. After operation, the knee varus/valgus stress tests were negative, and there was no relaxation and rupture of the lateral collateral ligament, instability of the knee joint, loosening, revision and infection of the prosthesis occurred. At last follow-up, mLDFA, HKA, MAD, knee ROM, VAS score, KSS knee score and function score significantly improved when compared with preoperative ones ( P<0.05). CONCLUSION: LCSO is effective and safe in TKA with lateral femoral bowing deformity. Extra-articular deformities are corrected intra-articularly. The mechanical force line and joint balance of the lower extremities can be restored simultaneously in an operation.

Is the femoral component flexion affected by the sagittal femoral shaft bowing in conventional intramedullary guided TKA?

BACKGROUND: The aim of the present study was to investigate the influence of sagittal femoral bowing on sagittal femoral component alignment, and whether there was correlation between sagittal femoral component alignment and coronal femoral component alignment. METHODS: We retrospectively reviewed 77 knees in 71 patients who had undergone primary TKA for advanced osteoarthritis. All surgeries were performed by using a standard medial parapatellar approach. The osteotomy was performed with a conventional technique using an intramedullary rod for the femur and a mechanical extramedullary guiding system for the tibia. All patients enrolled in the study were evaluated with full-length lower extremity load-bearing standing scanograms, and the patients had preoperative and postoperative radiographs of the knees. Coronal femoral bowing angle (cFBA), sagittal femoral bowing angle (sFBA), and postoperatively, mechanical tibiofemoral angle of the knee (mTFA), ß angle (femoral component flexion angle) were measured. The radiographic results of both groups were compared using Student's t test. A two-sided Pearson correlation coefficient was obtained to identify the correlations between FBA in the coronal and sagittal planes, as well as FBA and age or BMI, sFBA and ß angle, cFBA and mTFA. Comparison of FSB incidence between different genders was made using Chi-square test. The p value < 0.05 indicates a statistically significant difference. RESULTS: The mean sFBA, cFBA, ß angle, mTFA were 9.34° ± 3.56°(range 1°-16°), 3.25° ± 3.79°(range - 7° to -17°), 3.91° ± 3.15°(range - 1° to -13°), 0.60° ± 1.95°(range - 3° to -6°), respectively. There was no correlation between age and sFBA (CC = 0.192, p = 0.194) or cFBA (CC = 0.192, p = 0.194); similarly, there was no correlation between age and sFBA (CC = 0.067, p = 0.565) or cFBA (CC = 0.069, p = 0.549). The sFBA was correlated with cFBA and ß angle (CC = 0.540, p < 0.01; CC = 0.543, p < 0.01, respectively), and the cFBA was correlated with mTFA (CC = 0.430, p < 0.01). There was no significant difference (p = 0.247) of cFBA between the patients with sFSB and the patients without sFSB. CONCLUSIONS: The current study showed that the sFBA was correlated with cFBA in the patients undergoing TKA and the patients with sFSB usually presented non-cFSB. We also found that sFSB could affect the femoral component alignment in the sagittal plane and cFSB could affect the femoral component alignment in the coronal plane. The sFBA or cFBA was not correlated with age, BMI, or gender.

Lateral Bowing of Femur Associated With Older Age, Shorter Stature, and Lower Bone Mineral Density.

We often encounter elderly patients with femur bowing. According to literature, femoral bowing is correlated with patient characteristics such as aging, race, atypical femoral fracture (AFF), and osteoporosis. However, the clear relationships between these factors and femoral bowing are still unknown. In addition, most previous reports have been based only on X-rays and may not provide accurate information due to femur rotation and inter-operator reliability when compared to the information obtained using computed tomography (CT) scans. The purpose of this study was to examine the factors associated with anterior and lateral bowing in detail, by using three-dimensional preoperative measurement software Zed Hip®ï¸Ž (LEXI Co. Ltd., Tokyo, Japan). A total of 364 patients with trochanteric hip or femoral neck fractures, or osteoarthritis, treated in our hospital were included in this study. Of these, 61 patients older than 50 years, who had complete CT volume data for the entire length of the femur on the healthy side and bone mineral density (BMD) measured by trunk dual-energy X-ray absorptiometry (DXA), were investigated. There were 13 males and 48 females, aged 53-97 years (mean 78.7±10.8 years). We defined the starting and ending points of the femoral diaphysis to measure anterior bowing (AB) and lateral bowing (LB) of the femoral diaphysis. The correlation between AB or LB with each patient's characteristics (age, height, weight, lumbar BMD, and femoral BMD) was examined retrospectively. AB did not correlate with any of the patient parameters. LB weakly positively correlated with age and was negatively correlated with height and femoral (greater trochanter) bone density. Weight was in no correlation with either AB or LB. A novel three-dimensional approach was used for measurements that may be more accurate than plain two-dimensional radiographs.

Notching is less, if femoral component sagittal positioning is planned perpendicular to distal femur anterior cortex axis, in navigated TKA.

PURPOSE: In navigated TKA, the risk of notching is high if femoral component sagittal positioning is planned perpendicular to the sagittal mechanical axis of femur (SMX). We intended to determine if, by opting to place the femoral component perpendicular to distal femur anterior cortex axis (DCX), notching can be reduced in navigated TKA. METHODS: We studied 171 patients who underwent simultaneous bilateral computer-assisted TKA. Femoral component sagittal positioning was planned perpendicular to SMX in one knee (Femur Anterior Bowing Registration Disabled, i.e. FBRD group) and perpendicular to DCX in the opposite knee (Femur Anterior Bowing Registration Enabled, i.e. FBRE group). Incidence and depth of notching were recorded in both groups. For FBRE knees, distal anterior cortex angle (DCA), which is the angle between SMX and DCX, was calculated by the computer. RESULTS: Incidence and mean depth of notching was less (p = 0.0007 and 0.009) in FBRE versus FBRD group, i.e. 7% versus 19.9% and 0.98 mm versus 1.53 mm, respectively. Notching was very high (61.8%) in FBRD limbs when the anterior bowing was severe (DCA > 3°) in the contralateral (FBRE) limbs. CONCLUSION: Notching was less when femoral component sagittal positioning was planned perpendicular to DCX, in navigated TKA. LEVEL OF EVIDENCE: Therapeutic level II.

Straight nail insertion through a laterally shifted entry for diaphyseal atypical femoral fractures with bowing: good indications and limitations of this technique.

PURPOSE: Inserting a straight (piriformis fossa entry) nail through the tip of the greater trochanter has been used for treating atypical femoral fractures (AFFs) with bowing. This study aimed to determine what degree of bowing can be successfully treated using a laterally shifted entry technique. METHODS: Twenty-three complete and six incomplete diaphyseal AFFs treated using the shifted entry technique were retrospectively analysed. Radiologic parameters and complications were evaluated. The complete AFFs were divided into two groups based on the severity of preoperative bowing: grade 0-II bowing and < 20° lateral bowing (minimal/moderate) and grade III bowing or ≥ 20° lateral bowing (severe). Comparison according to postoperative malalignment, a change of lateral or anterior bowing ≥ 5° was also performed. RESULTS: Three complete AFFs in the minimal/moderate group showed malalignment, as did all in the severe group (p < 0.001). The change of bowing was greater for the severe group in lateral and anterior bowing (p = 0.004 and 0.001, respectively). A greater fracture gap was found on AP and lateral radiographs in the severe group (p = 0.044 and 0.026, respectively). In the comparison according to postoperative malalignment, a significant difference was found for the percentage of severe deformity (p < 0.001). All incomplete AFFs were united without complication. CONCLUSION: Diaphyseal AFFs with grade 0-II bowing and < 20° anterior bowing were treated successfully by the shifted entry technique. However, postoperative malalignment was found in all cases of AFFs with severe bowing. Therefore, other techniques should be considered for AFFs with grade III bowing or ≥ 20° anterior bowing.

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.

Total knee arthroplasty in femoral bowing: does patient specific instrumentation have something to add? A randomized controlled trial.

BACKGROUND: Patient-specific instrumentation (PSI) proponents have suggested the benefits of improved component alignment and reduced outliers. In this randomized controlled trial, we attempted to assess the advantage of using PSI over conventional intermedullary (IM) guides for primary total knee arthroplasty (TKA) with bilateral severe femoral bowing (> 5°). A parallel trial design was used with 1:1 allocation. We hypothesize that PSI would support more accurate alignment of components and the lower-limb axis during TKA with severe femoral bowing in comparison with conventional IM guides. METHODS: Among 336 patients undergoing bilateral TKAs due to knee osteoarthritis, 29 patients with bilateral lateral femoral bowing of more than 5° were included in this study. Every patient was assigned randomly to PSI on one side and to conventional instrumentation lateralization of the entry point of the femoral IM guide was applied on the other with a goal of neutral mechanical alignment. The assessment of coronal alignment was completed by measuring the hip-knee-ankle (HKA) angle on preoperative and postoperative long film standing radiographs. Coronal and sagittal orientations of femoral and tibial components were assessed on weight-bearing radiographs. The rotational alignment of the femoral component was evaluated using computed tomography. RESULTS: The postoperative mean ± standard deviation (SD) HKA angle was varus 4.0° (± 2.7°) for conventional technique and varus 4.1° (± 3.1°) for PSI, with no differences between the two groups (p = 0.459). The component orientation showed no significant differences except with respect to the sagittal alignment of the femoral component (p = 0.001), with a PSI mean ± SD flexion of 5.8° (± 3.7°) and a conventional method mean ± SD flexion of 3.2° (± 2.5°), due to the intentional 3° flexion incorporated in the sagittal plane to prevent femoral notching in PSI planning. Computed tomography assessment for rotational alignment of the femoral components showed no difference between the two groups concerning the transepicondylar axis (p = 0.485) with a PSI mean ± SD external rotation of 1.5° (± 1.3°) and conventional mean ± SD external rotation of 1.5° (± 1.6°). CONCLUSION: PSI showed no advantage over lateralization of the femoral entry for IM guidance. LEVEL OF EVIDENCE: 1 TRIAL REGISTRATION: Registered on US national library of medicine ClinicalTrials.gov ( NCT02993016 ) on December 12th 2016.

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

INTRODUCTION: This study aimed to evaluate the clinical outcomes of using contralateral-side laterally bent intramedullary nails (IMNs) in bowed atypical femur fractures (AFFs). MATERIALS AND METHODS: 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. RESULTS: The average age was 76.8 years (range 67-86 years), 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 74.5 months 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 0.6 mm (0-1 mm), and the average medial gap was 1.6 mm (1-3 mm). All cases achieved bone union without secondary intervention. There were no intraoperative fractures or postoperative complications. The average bone union time was 22.0 weeks and 9.2 weeks 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 5.7 mm. CONCLUSION: 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.

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.

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

Dynamic skeletal deformation with ageing showed important signs of degenerative and osteoporotic diseases. We found that both femoral bowing and cortical thickness were correlated with ageing in a Chinese population. Further, femoral cortical index, an osteoporotic indicator, was negatively correlated with femoral bowing angle. Hence, more attention should be paid to these femoral morphological changes to avoid fragility fractures and failed internal fixation. PURPOSE: 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. METHODS: One hundred twenty patients (mean 50 years, range 18~104 years) 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. RESULTS: The mean age of the male and female participants was 46.95 ± 15.25 and 52.22 ± 15.61 years, 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 (ß = 0.304 and 0.308 respectively) and sFCI (ß = - 0.322 and - 0.414 respectively) were two independent predictors associated with sFBA and cFBA respectively. CONCLUSIONS: 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.