Femoral Bowing Research Articles

Clinical and genetic analysis of a child with Spondyloocular syndrome due to compound heterozygous variants of XYLT2 gene

To explore the clinical characteristics and genetic etiology of a child with Spondyloocular syndrome (SOS) in order to enhance the awareness and understanding of this disease. A 3.5-year-old boy with SOS who had presented at the Department of Medical Genetics of Hunan Children's Hospital on August 10, 2023 due to the repeated fractures for over 2 years and after binocular cataract surgery was selected as the study subject. Clinical data of his pedigree were collected, and peripheral venous blood samples were collected for the extraction of genomic DNA and subjected to trio-whole exome sequencing. Candidate variants were verified by Sanger sequencing and analyzed with bioinformatic software. This study was approved by the Medical Ethics Committee of Hunan Children's Hospital (Ethics No. KYAQ2022-263). The child had manifested repeated fractures, bilateral bowed femur, osteoporosis, cataract, atrial septal defect, and developmental delay. Ultrasonography has revealed fetal edema, peritoneal effusion, pleural effusion and polyhydramnios. Trio-whole exome sequencing and Sanger sequencing revealed that he has harbored compound heterozygous variants of the XYLT2 gene, namely c.1103_1104delAG (p.Gln368Argfs*8) and c.1238_1253delinsA (p.Val413_Pro418delinsGlu), which were inherited from his phenotypically normal father and mother, respectively. Neither variant was reported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG) and recommendations from the Clinical Genome Resource (ClinGen), the c.1103_1104delAG was predicted as a pathogenic variant (PVS1+PM2_Supporting+PP4), whilst the c.1238_1253delinsA was predicted as a likely pathogenic variant (PM4+PM3+PM2_Supporting+PP4). The c.1103_1104delAG and c.1238_1253delinsA compound heterozygous variants of the XYLT2 gene probably underlay the pathogenesis in this child. Above finding has enriched the phenotypic and mutational spectrum of SOS, and provided a basis for the clinical diagnosis, treatment, prognosis assessment and genetic counseling for this pedigree.

No single safe zone exists for the valgus cut angle to reproduce neutral mechanical alignment in the presence of femoral bowing in total knee arthroplasty.

The aim of this study is to report the prevalence of femoral bowing in the Egyptian arthritic knees as a representative of the middle eastern population and to study the correlation between the femoral bowing and the degree of arthritis, varus deformity and the distal femoral valgus cut angle (VCA). This is a single-center observational cross-sectional study. Out of 562 knees Scheduled for TKA, 124 knees were excluded leaving 438 knees eligible for the study. The following angles were measured by two independent orthopedic surgeons: Femoral bowing angle (FBA), HKA angle, LDFA, MPTA and VCA. Out of 438 knees, 21knees (4.8%) had medial bowing (< - 3°), 111 (25.3%) had normal bowing (+ 3° to - 3°) and 306 (69.9%) had LFB of which 111 (25.34%) had mild LFB (+ 3 to + 5°) and 195 (44.52%) had severe LFB (> + 5°) bowing. LFB was more in older age group (p = 0.005), in females (p < 0.001), and in grade 4 OA, (p < 0.001). Also, there was a significant positive correlation between FBA and age and increasing varus HKA, and with varus orientation of the distal femur and the tibial plateau. The mean and the 95% confidence interval of the VCA for the medial bowing group was 3.43 (3.01-3.85°), for the normal bowing group was 5.42 (5.15-5.68°), for the mild lateral bowing was 6.74 (6.47-7°), and for the severe bowing group was 9.23 (8.89-9.55°). There is no single safe zone for the VCA to reproduce postoperative neutral coronal alignment especially in cases of severe lateral femoral bowing in TKA. However, the VCA should be analyzed in term of how much femoral bowing exists. In other words, for each subset of femoral bowing there is a safe zone for the VCA.

Anterior Cortical Impingement With 240 mm Cephalo-Medullary Nail (PFN and PFNA-2) in Intertrochanteric Femur Fracture Fixation in the Indian Population: A Problem Statement.

Trochanteric fractures are common in the elderly population, and their incidence increases twice every decade after age 50. Intramural fixation has achieved good clinical efficacy in the treatment of unstable trochanteric fractures, but there have been complications reported in the literature in the Asian population. Most complications arise from a mismatch between the increase in the anterior femoral bow with advancing age and the proximal femoral nails (PFN) on the market, which still have straight designs on the sagittal plane. The non-anatomic shapes of the PFNs sometimes make the surgeries difficult or may lead to an inadvertent intraoperative fracture around the tip of the nail, particularly if they impinge on the anterior cortex of the femur. The entry point on the greater trochanter was divided into three equal parts, i.e., anterior 1/3rd, middle 1/3rd, and posterior 1/3rd on the lateral X-rays. Patients with posterior 1/3rd entry were excluded from the study as it is known that posterior positioning of nail entry can cause an increased incidence of anterior nail impingement. The AI was measured using the best available preoperative lateral roentgenogram of the femur using the incidence cortex (AI cortex) angle. This angle was measured using two tangential lines drawn parallel to the anterior cortex of the femur, proximal and distal to the most bowed point of the femur. We recommend that there is a need to introduce anterior curvature in the sagittal plane corresponding to the femoral bow in a 240 mm cephalomedullary nail to decrease complications. We also consider the use of either a short (i.e., 180 mm) or a long cephalomedullary nail in the Indian population, as the height of the population is shorter as compared to the western population, and the role of a 240 mm cephalomedullary nail is doubtful in the Indian population.

Brace based Mechanical axis deviation (MAD) of lower limb correction in a Pediatric patient with severe femoral and tibial bowing - A case based description

Genu varum is a Latin term used to describe bow legs. It is a common finding in the pediatric population with a large differential spectrum which includes but not limited to Blount’s disease, rickets, Post infective &amp; post traumatic physeal injuries and physiologic bowing of the legs. The femoral intercondylar distance between the two knees is increased in this condition and it can have a unilateral or bilateral involvement. In the case of genu varum, the mechanical axis falls more inside beyondthe middle ofthe knee joint and the joint undergoes an increased non-physiological stress which can affect both the articular cartilage of the knee and its ligaments. Here we present a case of a 3 year old girl with severe varus deformity of both lower legs which was successfully managed with Brace based correction technique in the lower limbs.

Cloaked bones in Mucolipidosis II - A periosteal reaction in newborns

On routine, antenatal ultrasound evaluation of a women at 35 weeks gestation showed a fetus (Case 1) with shortening of all the long bones (&lt;5th percentile) with bowing and fuzzy margins. The baby was delivered full term. On physical examination, the baby had a fragile skull, narrow thorax, and short angulated limbs. Postnatal infantogram showed short long bones, periosteal cloaking, fractures, and bell shaped thorax. Another fetus (Case 2) with antenatal ultrasound done elsewhere was suggestive of short and bowed femur. At birth, the baby had angulated limbs. The infantogram shows the periosteal cloaking (thick periosteal reaction) and short long bones similar to the above-mentioned case. Both babies were positive for the I-cell screening test for Mucolipidosis II. Case 1 was confirmed for the same with whole exome sequencing.

Three-Dimensional Bowing Measurement of Distal Femur at Actual Size and Clinical Implications of Total Knee Arthroplasty.

Background and Objectives: To assess femoral shaft bowing (FSB) in coronal and sagittal planes and introduce the clinical implications of total knee arthroplasty (TKA) by analyzing a three-dimensional (3D) model with virtual implantation of the femoral component. Materials and Methods: Sixty-eight patients (average age: 69.1 years) underwent 3D model reconstruction of medullary canals using computed tomography (CT) data imported into Mimics® software (version 21.0). A mechanical axis (MA) line was drawn from the midportion of the femoral head to the center of the intercondylar notch. Proximal/distal straight centerlines (length, 60 mm; diameter, 1 mm) were placed in the medullary canal's center. Acute angles between these centerlines were measured to assess lateral and anterior bowing. The acute angle between the distal centerline and MA line was measured for distal coronal and sagittal alignment in both anteroposterior (AP) and lateral views. The diameter of curve (DOC) along the posterior border of the medulla was measured. Results: The mean lateral bowing in the AP view was 3.71°, and the mean anterior bowing in the lateral view was 11.82°. The average DOC of the medullary canal was 1501.68 mm. The average distal coronal alignment of all femurs was 6.40°, while the distal sagittal alignment was 2.66°. Overall, 22 femurs had coronal bowing, 42 had sagittal bowing, and 15 had both. Conclusions: In Asian populations, FSB can occur in coronal, sagittal, or both planes. Increased anterolateral FSB may lead to cortical abutment in the sagittal plane, despite limited space in the coronal plane. During TKA, distal coronal alignment guides the distal femoral valgus cut angle, whereas distal sagittal alignment aids in predicting femoral component positioning to avoid anterior notching. However, osteotomies along the anterior cortical bone intended to prevent notching may result in outliers due to differences between the distal sagittal alignment and the distal anterior cortical axis.

Prenatal and neonatal phenotype of Larsen of La Réunion Island syndrome (B4GALT7-linkeropathy)

Larsen of La Réunion Island syndrome (LRS) is an autosomal recessive condition associated with multiple large joint dislocations, clubfeet, severe dwarfism, and distinctive facial features. LRS is caused by a recurrent homozygous variant in B4GALT7 gene with a founder effect in La Réunion population. Proteoglycans (PG) that are a major component of the extracellular matrix, are composed of a core protein connected to a glycosaminoglycans side chain via a tetrasaccharide linker region. B4GALT7 encodes galactosyltransferase I, one of the enzymes involved in the biosynthesis of the linker region. Conditions caused by pathogenic biallelic variants in genes implicated in the synthesis of the tetrasaccharide linker of PG are known as linkeropathies.Prenatal features are rarely described in this group of chondrodysplasias. We present a series of 12 unpublished patients having LRS and describe the perinatal phenotype. All the patients had a prenatal growth restriction with brevity of limbs. The other features revealed by ultrasounds were increased nuchal translucency at 10–12 weeks of gestation (50 %), feet abnormalities (clubfeet or metatarsus varus) (25 %), dislocation affecting at least one large joint (elbow, knee, wrist) (25 %). Bilateral bowing of femora was noted for two fetuses. Fibular hypertrophy was noted for one fetus. Prenatal helical computed tomography (CT) performed in three pregnancies showed additional data such as bowing of the forearm bones, proximal radio-ulnar synostosis, or dislocation of large joints. Prenatal sonographic and helical CT findings led to the prenatal diagnosis of LRS in four patients. We confirm that the neonatal clinical picture of LRS has an important overlap with that reported in patients with B4GALT7 deficiency outside La Réunion Island and other linkeropathies. The core of the phenotypic spectrum combines low birth height, micromelia, hypermobility, dislocation of at least one large joint, facial features with prominent eyes, microstomia, depressed nasal bridge, and midface hypoplasia. Other clinical features include clubfeet (33%), bifid thumb in one patient, and cardiac abnormalities in two patients. Radiological findings include radio-ulnar synostosis (75%), metaphyseal flaring, precocious carpal ossification, and a Swedish key appearance of the proximal femora. Finally, we also report radiological features rarely described in B4GALT7-linkeropathies, including bowing of the femora and fibular hypertrophy. Our results confirm the phenotypic continuum of LRS within linkeropathies with some additional findings, including a high frequency of clubfeet usually described in B3GALT6-linkeropathies, the presence of congenital heart diseases usually described in B3GAT3-linkeropathies, and a high frequency of metaphyseal flaring usually reported in B3GALT6 or XITLT1-linkeropathies.This is the first study that describes the perinatal phenotype in a cohort of patients with LRS. This study can help improve the prenatal diagnosis of the linkeropathies and add this group of conditions to the differential diagnosis of chondrodysplasias with multiple dislocations.In view of the founder effect for LRS in La Réunion Island, this disease should be suspected in fetuses with growth restriction and micromelia. Thus in case of LOH which include B4GALT7 identified in SNP-array, we recommend performing a targeted Sanger sequencing for the recurrent mutation c.808C > T; p. (Arg270Cys).

IS MEASURING FEMORAL LENGTHENING A RELIABLE TECHNIQUE FOR TRACKING HEIGHT GAIN IN COSMETIC INTRAMEDULLARY LENGTHENING PATIENTS?

IntroductionThe practice of limb lengthening using intramedullary nails has surged in popularity in recent years. Our study explores the relationship between femur lengthening and overall height gain in adults undergoing cosmetic limb lengthening with telescoping magnetic intramedullary lengthening nails (MILNs).Materials &amp; MethodsDemographic information, pre- and postoperative radiographic data, and secondary outcomes, such as mechanical angles and sagittal alignment, were analyzed for 42 adult femurs MILNs (PRECICE 2, NuVasive, Inc.). Height was assessed with a digital stadiometer. Limb lengthening was defined as the amount of nail distraction seen on a calibrated weight bearing X-ray at consolidation. mLDFA, mMPTA, MAD, AMA, and femoral sagittal bow were evaluated as secondary outcomes.ResultsMean starting height was 163.5 cm (SD 10.4, range 137–179) Post -lengthening mean height increased to 171.1 cm (SD 10.1, range 146.7–185.3). Average height gain was 7.5 cm (SD 1.3 cm, range 5.1–9.5). Average femoral lengthening was 7.3 cm (SD 1.14, range 4.1–10.1). There were no statistically significant difference between height gain and femur lengthening. Secondary outcomes showed reductions in femoral sagittal bow and AMA.ConclusionsWe conclude that measuring femur lengthening is a reliable and accurate method of measuring gained height in deformity-free patients undergoing limb lengthening. We further reason that straightening of both femoral and spinal sagittal bow counteracts potential lengthening loss over the anatomical axis, versus mechanical axis lengthening.

Analysis on association between sagittal stem alignment and early functional and radiological outcome following primary cementless total hip replacement.

Accurate reconstruction of hip anatomy and biomechanics is mandatory for achieving good clinical outcomes following total hip replacement (THR). Optimal stem alignment is essential to avoid impingement or loosening. This study aimed to evaluate sagittal stem position following cementless THR and its relationship with patient's functional outcome and post-operative radiological parameters. We performed analytical observational study with cross-sectional design on 71 hips (67 patients, ranged 18-85years old) that underwent primary cementless THR in two orthopedic centers in Jakarta, Indonesia. All hips were operated through either anterolateral or posterior approach using either extended/full-coating wedge-tapered stem or proximal-coated wedge-tapered stem. Clinical outcomes were evaluated at follow-up time using mHHS questionnaire, VAS level of thigh pain, and hip ROM. Stem sagittal alignment and other radiological parameters, including combined anteversion and offset, were measured from conventional radiograph. There were no significant differences on mHHS score, VAS level on thigh pain, and ROM between stem alignment groups. Post-operative anteversion and offset of the implant were not affected by the stem sagittal position. All influencing factors have significant effect on sagittal stem alignment. Linear regression test on femur morphology showed 0.69° increase in stem posterior tilt for every 1° increase in the anterior bowing (coeff. = 0.502). Stem tilting in sagittal plane did not affect patient's functional outcome or post-operative radiological parameters. In addition, for every degree of increased anterior femoral bowing, 0.69° increase in posterior stem tilting can be expected.

Constitutional varus knee due to tibial deformity is common and represents a good indication for high tibial osteotomy in Japanese population: Consideration of 1010 knees.

This study aimed to elucidate the characteristics of varus knee deformities in the Japanese population, prevalence of various around knee osteotomy proceduresand influence of femoral and tibial bowing. Varus knee deformity was defined as a weight-bearing line ratio of <50%. A total of 1010 varus knees were selected from 1814 varus knees with weight-bearing full-length radiographs, obtained at two facilities, based on exclusion criteria. Various parameters were measured, and around knee osteotomy simulations based on the deformity centre were conducted using digital planning tools. Bowing of the femoral and tibial shafts was measured, with bowing defined as follows: ≤ -0.6° indicating lateral bowing and ≥ 0.6° indicating medial bowing. Statistical analysis was performed to investigate age-related correlations and their impact on surgical techniques. The study revealed that the proximal tibia was the centre of deformity in Japanese varus knees (42.8%), and high tibial osteotomy was frequently indicated (81.6%). Age demonstrated a mild correlation with femoral shaft bowing (r = -0.29), leading to an increase in the mechanical lateral distal femoral angle and to a decrease in the hip-knee-ankle angle and weight-bearing line ratio (r = -0.29, 0.221, 0.219). The tibial shaft bowing was unaffected by age (r = -0.022). A significant proportion of Japanese individuals with varus knees exhibit a deformity centre located in the proximal tibia, making them suitable candidates for high tibial osteotomy. No age-related alterations were discerned in tibial morphology, indicating that the occurrence of constitutional varus knees is attributable to tibial deformities in the Japanese patient cohort. Level IV.

Off target of distal interlocking screw in short cephalomedullary nail fixation for intertrochanteric femur fractures

To analyze the causes and treatment of off target of the distal interlocking screws when short cephalomeduallry nails were installed through jig-guided targeting device, and to put forward the technical points to prevent off target. Retrospective analysis of 9 patients with intertrochanteric fractures treated between July 2014 and June 2023 was conducted, in which off target occurred during the insertion of the distal interlocking screw by jig-guided targeting device in short cephalomedullary nailling (<24 cm). There were 1 male and 8 females, with an average age of 82.7 years (range, 73-94 years). There were 3 cases of type A1, 5 cases of type A2, and 1 case of type A3 according to 2018-AO/Orthopaedic Trauma Association (AO/OTA) fracture classification. As for the misaligned distal interlocking screw, six parameters were collected and analyzed, including the time of finding, the position, the type of passing through the cortical bone, the special circumstances during operation (such as the need to remove the intramedullary nail for reaming the diaphysis, hammering, etc.), the treatment, and the patient follow-up results. In the 9 patients, the off target of the distal interlocking screw was found in 7 cases during operation and in 2 cases after operation; the locking screw was located behind the nail in 7 cases and in front of the nail in 2 cases; the off target locking screw was passing tangentially in transcortical patern in 6 cases and in bicortical pattern through the medullary cavity in 3 cases. Three cases were attributed to the mismatch between the nail and the femur, two of which were attributed to the narrow femoral medullary cavity, one of which was attributed to the large anterolateral femoral bowing, and the other 6 cases were attributed to technical errors such as the loosening of the jig-guided targeting device, the tension of the fascia lata, and the blunt of the drill. In the 7 cases found during operation, the misaligned interlocking screw was removed first and the screw hole was left vacant, then in 2 cases, the interlocking screw was not used further; in 1 case, the distal dynamic hole was successfully inserted with a dynamic guide frame, and in 4 cases, the interlocking screw was successfully put after 2-3 attempts, leaving a large hole in the lateral cortex. No special treatment was performed in 2 cases found after operation. One patient was out of bed early after operation, 7 patients were in bed for 1 month, and 1 patient deteriorated to A3 type after operation and was in bed for 3 months. All the 9 patients were followed up 6-12 months, with an average of 8 months. Fracture healing was achieved in 8 patients. One patient with vacant interlocking screw had a secondary spiral fracture of the femoral shaft 3 months later, and was refixed with a long cephalomedullary nail and circlage wiring. Distal interlocking screw off target is rare, but when it occurs, it leaves a large cortical hole in the osteoporotic femoral shaft, reducing bone strength; the use of precision instruments and attention to technical details can reduce this adverse phenomenon.

Navigation makes more accurate femur resection compared to conventional total knee arthroplasty in lateral femoral bowing greater than 5º.

There are many disagreements about the merits of navigation in total knee arthroplasty (TKA). We compared and analyzed the difference in the accuracy of femoral resection according to the degree of lateral femoral bowing in 2 surgical methods (conventional and navigation-assisted TKA). A total of 238 (100 who underwent navigation TKA and 138 who underwent conventional TKA from 2016 to 2021) were included in this study. The surgeon first performed TKA as the main operator in 2016. Most of the TKAs were navigation-assisted between 2016 and 2018, and most of the TKAs were conventional between 2019 and 2021. For more accurate distal femoral cutting in patients with lateral femoral bowing, a preoperative scanogram was used to set up the insertion point of the IM rod in conventional TKA. Femoral lateral bowing was divided into 3 groups based on the angle. Group 1 was divided into groups with negative values, group 2 into mild bowing of 0° to 5°, and group 3 into groups with moderate bowing of ≥ 5°. The postoperative mechanical hip knee ankle angle and mechanical lateral distal femoral angle (mLDFA) were aimed to be 0° and 90°. The allowable ranges of these values were set as 0° ± 3° and 90° ± 3°, respectively. The distribution of outliers of the mLDFA in the 3 groups divided according to lateral femoral bowing in the navigation-assisted group was not statistically significant difference (P = .59). On the other hand, the distribution of outliers of mLDFA was statistically significant difference in the conventional method group (P = .01). The odds ratio of the outlier occurrence of mLDFA in the conventional method was 2.50, which was statistically significant (P = .03). Also, when the lateral femoral bowing value was moderate; i.e., ≥5°, the odds ratio was 4.20, which was statistically significant (P = .003). In the case of navigation-assisted TKA, the accuracy of femur resection was consistent regardless of the degree of lateral femoral bowing. However, in conventional TKA, the outlier of femur resection increased as lateral femoral bowing increased. Especially, for patients with lateral femoral bowing >5°, navigation-assisted TKA allows for more accurate femur resection compared to conventional TKA.

Chronological Changes in Sagittal Femoral Bowing after Primary Cementless Total Hip Arthroplasty: A Comparative 3D CT Study.

Little is known about dynamic changes of femoral anatomy after total hip arthroplasty (THA), in particular about sagittal femoral bowing (SFB). A 3D CT study was designed to evaluate the chronological changes of SFB after cementless femoral stem implantation for primary THA. Ten patients who underwent unilateral primary THA with a cementless femoral stem, with 2 consecutive CT scans (extending from the fourth lumbar vertebra to the tibial plateaus), performed before THA and at least 3 years after THA, were enrolled. The 3D models of femurs were created using image segmentation software. Using the two CT scans, SFB values of the proximal and middle thirds were calculated on the replaced and untreated sides by two different observers. Eight anatomical stems and two conical stems were involved. The post-operative CT was performed at an average follow-up of 6.5 years after THA (range: 3-12.5). The measurements performed by the two observers did not differ in the proximal and middle regions. A significant difference between the pre-operative and post-operative SFB compared to the untreated side was found in the proximal femur segment (p = 0.004). Use of a cementless stem in THA induced chronological changes in SFB of the proximal femur, after a minimum timespan of 3 years.

Primer caso de displasia tanatofórica tipo 1 en los andes peruanos con variante patogénica en el gen FGFR3

Thanatophoric dysplasia type 1 is a form of lethal skeletal dysplasia, characterized by axial-appendicular skeletal disproportions as well as short stature, frontal bossing, cloverleaf skull, narrow chest, femoral bowing, and micromelia. These phenotypic characteristics are the result of pathogenic variants in the fibroblast growth factor receptor 3 (FGFR-3) gene, located on chromosome 4p16.3 For its study, obstetric ultrasound, physical examination and radiographic findings are important. However, the diagnosis must be confirmed by genetic study in order to discover new variants or associations, as well as to reveal its actual casuistry in a certain region.

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

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? 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. 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. 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.

How Do the Morphological Abnormalities of Femoral Head and Neck, Femoral Shaft and Femoral Condyle Affect the Occurrence and Development of Medial Knee Osteoarthritis.

At present, the main viewpoint is that tibial varus is the main reason of medial knee osteoarthritis (OA), and high tibial osteotomy (HTO) is also the main alignment correction method to correct medial knee OA. In contrast, the impact of the anatomical alignment of the femur on medial knee OA is often overlooked. We evaluated the increased risk for medial knee OA because a varus alignment could be attributed to the anatomical reasons that include hip anatomy, femoral shaft bowing (FSB) and femoral condylar dysplasia. The present research adopted a cross-sectional study method. We selected 62 patients with HTO in the Third Hospital of Hebei Medical University from June 2021 to March 2022 as the HTO group and 55 healthy volunteers as the control group. Femoral neck-shaft angle (NSA), lateral FSB, mechanical lateral distal femoral angle (mLDFA) and hip-knee-ankle (HKA) was radiographically examined within the two groups. The femoral neck length and offset were also measured, and the ratio is represented by the ratio of the femoral neck length to off-set (N/O). The 2-tailed Student t-test was used to compare the differences between groups when the data were in accordance with a normal distribution. Otherwise, the Mann-Whitney U tests was used to compare the differences between groups. Compared to the control group, the HTO group had a higher offset (p < 0.05), greater femoral neck length (p < 0.05), and decreased (more varus) NSA (p < 0.05). The HKA in the HTO group was 172.20 ° (3.50°), which was significantly lower than that of the control group 177.00° (3.05°), (p < 0.001), while the medial OA was associated with more varus HKA. The mean mLDFA was 89.10 ° (2.35°) and 87.50° (2.85°) in the HTO and control groups (p < 0.005), respectively. The mean lateral FSB values of the full-length radiographs were larger (p < 0.001) in the HTO group (4.24° ± 3.25°) than that in control group (1.16° ± 2.32°). The reduction of NSA (coxa vara) and the increase of the mLDFA can lead to medial knee OA, while the lateral FSB also affects medial OA. We believe that femoral deformity is also one of the cause of the medial knee OA. Therefore, it is necessary to evaluate the joint deformity of the femur and tibia before surgery in order to determine whether to use HTO alone to correct the lower limb alignment.

Frequency and pathogenesis of periprosthetic atypical femoral fractures associated with total knee arthroplasty: A multicenter prospective study with complementary histopathological and biomechanical analysis

IntroductionAlthough the diagnostic criteria for atypical femoral fracture (AFF) exclude periprosthetic fractures, reports of periprosthetic femoral fractures with characteristics of AFF are rapidly increasing. In this study, we investigated the frequency and pathogenesis of periprosthetic AFF associated with total knee arthroplasty (TKA) based on a theory of AFF subtypes that divides AFFs into two main types: fragility stress fractures of the bowed femoral shaft in the mid-shaft and “typical” subtrochanteric AFFs due to suppression of bone turnover (e.g., by bisphosphonates). Patients and MethodsThis multicenter prospective study of AFFs was conducted from 2015 through 2022. Clinical, pathological, and morphological characteristics were investigated in patients with periprosthetic AFFs associated only with non-stem TKA. Then, biomechanical investigation of the periprosthetic AFF was performed by computer tomography-based finite element analysis (CT/FEA) using two models with different load axes to examine how the correction of lower limb alignment by TKA influences the tensile stress distribution of the femur and the location of the AFF. ResultsFour of 61 AFFs (6.6%) were identified to be periprosthetic AFF (1 mid-shaft; 3 subtrochanteric). Periprosthetic AFFs had characteristics including mechanical stress due to bowing deformity and potentially suppressed bone turnover due to long-term exposure to specific drugs (e.g., bisphosphonates and glucocorticoids). Although 2 periprosthetic AFFs appeared to involve a bowed femur, one with both of the aforementioned characteristics occurred in the subtrochanteric region, which would be an unusual site for a bowed AFF, and it was demonstrated histologically to have biological activity at the fracture site, suggesting a stress fracture. Furthermore, CT/FEA revealed that tensile stress distribution changed proximally as load axis was shifted laterally according to correction of lower limb alignment by TKA. ConclusionOrthopedic surgeons should recognize the presence of TKA-associated periprosthetic AFF caused by various factors including specific drugs, bowing deformity, and lower limb alignment. X-rays of the full-length femurs should be checked regularly after TKA, especially in patients with bowed femurs or long-term exposure to specific drugs.

OA08 Atypical femoral fracture secondary to long term bisphosphonate use; are we doing enough to prevent it?

Abstract Introduction Atypical femoral fractures (AFF) are low energy subtrochanteric or femoral shaft fracture associated with long term use of bisphosphonates (BP). Although the absolute risk of AFF is low and ranges between 3.2-50 cases/100,000 person-years, this risk is said to double with prolonged use (&amp;gt;5 years). ROS and American Society for Bone and Mineral Research (ASBMR) recommends regular review of patient at 5 years for oral BP and 3 years for intravenous BP. We would like to share our experience with two AFF which was seen in our bone clinic over the last one year resulting from prolonged bisphosphonates use. Case description Case 1 A 76-year-old Caucasian lady was reviewed for follow-up appointment in bone clinic for the management of steroid induced osteoporosis. She was on AA for 13 years for primary prophylaxis. It was noted that she was experiencing discomfort in her right thigh for the last 8 months. Her initial femoral X-ray showed incomplete AFF of the right femur and she was referred to orthopaedics who suggested conservative management. 6 months later, she unfortunately had a fall resulting in right femur fracture which required intramedullary nailing. X-ray of the contralateral side shows periosteal thickening and she is waiting for prophylactic nailing. Case 2 79 year old white Caucasian presented to the hospital with a fall. She has been on long term steroids for PMR and was on alendronate for 20 years for primary prophylaxis. X-ray showed complete AFF of proximal right femur shaft which required intramedullary nailing, subsequently developed pain in left hip during physiotherapy and X-ray showed incomplete AFF of mid left femur which needed prophylactic nailing. She was then referred to our clinic for further risk stratification. Both the patients had their bisphosphonates stopped and was advised reduced weight bearing along with calcium and vitamin D supplementation. The table summarises the background history and investigations post presentation with AFF: Discussion Bisphosphonates are one of the mainstays for managing steroid induced osteoporosis and for patients with high risk fragility fractures. Despite the increasing awareness of long term complication, we still see patients with AFF who have missed the opportunity for review in primary and secondary care particularly among patients with primary prophylaxis with satisfactory DEXA scan. ROS and ASBMR recommends review of patients who are on oral bisphosphonates at 5 years and for patients on intravenous bisphosphonates at 3 years for further risk stratification to reduce the incidence of AFFs. It also recommends close monitoring in patients with prodromal pain in the hip, groin or thigh especially in those who have high risk factors such as long term glucocorticoid use, Asian race and femoral bowing. Cessation of bisphosphonates can result in 70% reduction of developing AFF. Hence a break in the treatment for approximately 18-24 months needs to be considered for patients who are at lower levels of risk for fragility fracture such as age &amp;lt;75years, no previous history of fragility fracture, DEXA T score more than −2.5 and low FRAX score. Yet, this is not happening in routine clinical practice both in primary and secondary care and patients fall out of safety netting resulting in AFF. We need robust pathway and safety netting for patients who are on long term treatment. This situation could have also been exacerbated by the COVID pandemic which has increased the waiting lists and cancelled appointments. Resulting in many elderly patients having no follow ups and DEXA assessments for risk stratification. Key learning points Following the COVID pandemic there has been a huge impact on the waiting list, which has further pushed follow-up review for patients on long term bisphosphonates. This has resulted in a missed opportunity to identify patients with low risk to have a break in the BPs treatment. We feel that with appropriate treatment pathways needs to be set at primary care and secondary care level to capture these patients on long bisphosphonates after 3 to 5 years of BP use; especially patients who are at higher AFF risk, including patients on glucocorticoids and patients of Asian ancestry. Steps must be put in place to ensure counselling and education is given to patients about risk of AFF and prodromal symptoms such as thigh or groin pain which are initial symptoms, so that they can seek appropriate review at primary care level. ROS and ASBMR Task Force 2013 need to be implemented locally to capture patients with long term BPs treatment. Also, if patients has AFF fracture, imaging of the other leg has to be considered for further evaluation as more than one fourth of the cases have contralateral lesion.

Referencing the center of the femoral head during robotic or computer-navigated primary total knee arthroplasty results in less femoral component flexion than the traditional intramedullary axis

BackgroundDuring robotic and computer-navigated primary total knee arthroplasty (TKA), the center of the femoral head is utilized as the proximal reference point for femoral component position rather than the intramedullary axis. We sought to analyze the effect on femoral component flexion–extension position between these two reference points. MethodsWe obtained CT 3D-reconstructions of 50 cadaveric intact femurs. We defined the navigation axis as the line from center of the femoral head to center of the knee (lowest point of the trochlear groove) and the intramedullary axis as the line from center of the knee to center of the canal at the isthmus. Differences between these axes in the sagittal plane were measured. Degree of femoral bow and femoral neck anteversion were correlated with the differences between the two femoral axes. ResultsOn average, the navigated axis was 1.4° (range, −1.4° to 4.1°) posterior to the intramedullary axis. As such, the femoral component would have on average 1.4° less flexion compared with techniques referencing the intramedullary canal. A more anterior intramedullary compared with navigated axis (i.e., less femoral flexion) was associated with more femoral bow (R2 = 0.7, P < 0.001) and less femoral neck anteversion (R2 = 0.5, P < 0.05). ConclusionComputer-navigated or robotic TKA in which the center of the femoral head is utilized as a reference point, results in 1.4° less femoral component flexion than would be achieved by referencing the intramedullary canal. Surgeons should be aware of these differences as they may ultimately influence knee kinematics.

Perturbations in fatty acid metabolism and collagen production infer pathogenicity of a novel MBTPS2 variant in Osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a heritable and chronically debilitating skeletal dysplasia. Patients with OI typically present with reduced bone mass, tendency for recurrent fractures, short stature and bowing deformities of the long bones. Mutations causative of OI have been identified in over 20 genes involved in collagen folding, posttranslational modification and processing, and in bone mineralization and osteoblast development. In 2016, we described the first X-linked recessive form of OI caused by MBTPS2 missense variants in patients with moderate to severe phenotypes. MBTPS2 encodes site-2 protease, a Golgi transmembrane protein that activates membrane-tethered transcription factors. These transcription factors regulate genes involved in lipid metabolism, bone and cartilage development, and ER stress response. The interpretation of genetic variants in MBTPS2 is complicated by the gene's pleiotropic properties; MBTPS2 variants can also cause the dermatological conditions Ichthyosis Follicularis, Atrichia and Photophobia (IFAP), Keratosis Follicularis Spinulosa Decalvans (KFSD) and Olmsted syndrome (OS) without skeletal abnormalities typical of OI. Using control and patient-derived fibroblasts, we previously identified gene expression signatures that distinguish MBTPS2-OI from MBTPS2-IFAP/KFSD and observed stronger suppression of genes involved in fatty acid metabolism in MBTPS2-OI than in MBTPS2-IFAP/KFSD; this was coupled with alterations in the relative abundance of fatty acids in MBTPS2-OI. Furthermore, we observed a reduction in collagen deposition in the extracellular matrix by MBTPS2-OI fibroblasts. Here, we extrapolate our observations in the molecular signature unique to MBTPS2-OI to infer the pathogenicity of a novel MBTPS2 c.516A>C (p.Glu172Asp) variant of unknown significance in a male proband. The pregnancy was terminated at gestational week 21 after ultrasound scans showed bowing of femurs and tibiae and shortening of long bones particularly of the lower extremity; these were further confirmed by autopsy. By performing transcriptional analyses, gas chromatography-tandem mass spectrometry-based quantification of fatty acids and immunocytochemistry on fibroblasts derived from the umbilical cord of the proband, we observed perturbations in fatty acid metabolism and collagen production similar to what we previously described in MBTPS2-OI. These findings support pathogenicity of the MBTPS2 variant p.Glu172Asp as OI-causative and highlights the value of extrapolating molecular signatures identified in multiomics studies to characterize novel genetic variants.