Plane Alignment Research Articles

A gyroscope-based system for intraoperative measurement of tibia coronal plane alignment in total knee arthroplasty

Coronal plane alignment in total knee arthroplasty (TKA) is an important predictor of clinical outcomes including patient satisfaction and device longevity. Radiography and computer assisted navigation are the two primary technologies currently available to surgeons for intraoperative assessment of alignment; however, neither is particularly well-suited for use in this increasingly high volume procedure. Herein we propose a novel gyroscope-based instrument for intraoperative validation of tibia coronal plane alignment, and provide initial analytical and experimental performance assessments. The gyroscope-based alignment estimate is derived from simplified joint geometry and verified experimentally using a custom tibial trial insert containing a consumer-grade inertial measurement unit (IMU). Average accuracy of the gyroscope-based tibia coronal angle estimate was found to be within ±1° in mechanical leg jig and cadaver testing. These results indicate that the proposed gyroscope-based method shows promise for low cost, accurate intraoperative validation of limb alignment in TKA patients. Integrating IMU technology into the TKA surgical workflow via low-cost instrumentation will enable surgeons to easily validate implant alignment in real time, thereby reducing cost, operating room time, and future revision burden.

Pes varus correction in dachshunds with mini hybrid external skeletal fixators.

To evaluate the clinical and radiographic outcome of pes varus deformity correction in dachshunds managed with acute medial opening wedge osteotomy of the distal tibia and stabilised with a mini hybrid external skeletal fixator (HESF). Surgical correction involved a transverse osteotomy over the premeasured location at the distal tibia and application of a IMEX mini HESF. All corrections were evaluated using centre of rotation and angulation methodology. Medical records and radiographies of 20 dachshunds (28 pes varus corrections) were reviewed. All osteotomies healed and fixators were removed between 6 and 12 weeks. Lameness resolved in 18 dachshunds (90%) and significantly improved in two dachshunds (10%). Lateral patella luxation (LPL) was detected in 11/28 (39.2%) of the involved pelvic limbs, all of which resolved following pes varus correction. Mean frontal plane alignment (FPA) of the normal and abnormal tibiae were 12.3° valgus (range: 4°-18°) and 25° Varus (range: 16°-41°) respectively. Angular correction ranged between 30° and 50° (Mean: 39°) and the mean post-operative FPA was 13° valgus (range: 5°-21°). Pes varus deformity in dachshunds can be corrected by medial opening wedge osteotomy of the distal tibia stabilised by HESF. Single-session bilateral pes varus corrections can also be performed with minimal morbidity. LPL was commonly detected in dogs with pes varus deformity and all resolved spontaneously following pes varus correction alone.

The Sagittal Integral Morphotype in Male and Female Rowers.

The goal of this study was to describe the integrated spinal assessment of the sagittal morphotype in rowers to determine whether the intense practice of rowing causes a modification of the sagittal curvatures of the spine, its relationship with the rowing technique, and training background. The second goal was to analyse how the dorsal and lumbar curves behave in the three phases of the rowing gesture, and to determine which phases can be detrimental to the correct development of the spine during growth. We analysed the spine curvatures in the sagittal plane of 29 females and 82 males, which were measured with an inclinometer in standing, slump sitting, maximal trunk flexion and during rowing performance. The average value of thoracic kyphosis in the rowers was 30° (mean, 30 + 8.27°). Thoracic hyperkyphosis was found in only two rowers (1.8%). Lumbar lordosis was within normal range in 84.1% of the males (mean, 27 + 9.57°) and 75.9% of female rowers (mean, 33°). Functional thoracic hyperkyphosis was observed in 57.4% of the males and 17.1% of the females. Functional lumbar hyperkyphosis was observed in 28 of the 69 males (40.5%) and five of 22 females (17.2%). Rowing seems to provide adequate spine alignment in the sagittal plane on standing. The integrated spinal assessment of the sagittal morphotype showed that half or our rowers presented with functional thoracic hyperkyphosis, and 43.2% presented with functional lumbar hyperkyphosis. Spine behaviour during the rowing technique shows that the thoracic kyphosis (98.2%) and lumbar spine (91%) perform within normative ranges and could explain the adequate positioning of the spine in the sagittal plane on standing. Years of rowing training tend to reduce thoracic kyphosis in males.

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

BackgroundThe 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.MethodsWe 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), β 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 β 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.ResultsThe mean sFBA, cFBA, β 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 β 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.ConclusionsThe 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.

Alignment in Medial Fixed-Bearing Unicompartmental Knee Arthroplasty: The Limb Has a Leg Up on the Component.

To assess how implant alignment affects unicompartmental knee arthroplasty (UKA) outcome, we compared tibial component alignment of well-functioning UKAs against 2 groups of failed UKAs, revised for progression of lateral compartment arthritis ("Progression") and aseptic loosening ("Loosening"). We identified 37 revisions for Progression and 61 revisions for Loosening from our prospective institutional database of 3351 medial fixed-bearing UKAs performed since 2000. Revision cohorts were matched on age, gender, body mass index, and postoperative range of motion with "Successful" unrevised UKAs with minimum 10-year follow-up and Knee Society Score ≥70. Tibial component coronal (TCA) and sagittal (TSA) plane alignment was measured on postoperative radiographs. Limb alignment was quantified by hip-knee-ankle (HKA) angle on long-leg radiographs. In addition to directly comparing groups, a multivariate logistic regression examined how limb and component alignments were associated with UKA revision. In the Progression group, component alignment was similar to the matched successes (TCA 3.6° ± 3.5° varus vs 5.1° ± 3.5° varus, P= .07; TSA 8.4° ± 4.4° vs 8.8° ± 3.6°, P= .67), whereas HKA angle was significantly more valgus (0.3° ± 3.6° valgus vs 4.4° ± 2.6° varus, P < .001). Loosening group component alignment was also similar to the matched successes (TCA 6.1° ± 3.7° varus vs 5.9° ± 3.1° varus, P= .72; TSA 8.4° ± 4.6° vs 8.1° ± 3.9°, P= .68), and HKA was significantly more varus (6.1° ± 3.1° varus vs 4.0° ± 2.7° varus, P < .001). Using a multivariate logistic regression, HKA angle was the most significant factor associated with revision (P < .001). In this population of revised UKAs and long-term successes, limb alignment was a more important determinant of outcome than tibial component alignment. Level III case-control study.

Crystallographic Preferred Orientation (CPO) Development Governs Strain Weakening in Ice: Insights From High‐Temperature Deformation Experiments

AbstractStrain weakening leads to the formation of high‐strain shear zones and strongly influences terrestrial ice discharge. In glacial flow models, strain weakening is assumed to arise from the alignment of weak basal planes—the development of a crystallographic preferred orientation, CPO—during flow. However, in experiments, ice strain weakening also coincides with grain size reduction, which has been invoked as a weakening mechanism in other minerals. To interrogate the relative contributions of CPO development and grain size reduction toward ice strain weakening, we deformed initially isotropic polycrystalline ice samples to progressively higher strains between −4 and −30°C. Microstructural measurements were subsequently combined with flow laws to separately model the mechanical response expected to arise from CPO development and grain size reduction. Magnitudes of strain weakening predicted by the constitutive flow laws were then compared with the experimental measurements. Flow laws that only consider grain size do not predict weakening with strain despite grain size reduction. In contrast, flow laws solely considering CPO effects can reproduce the measured strain weakening. Thus, it is reasonable to assume that strain weakening in ice is dominated by CPO development, at least under high temperature ( ≥ 0.9) and high stress (&gt;1 MPa), like those in our experiments. We speculate that at high homologous temperatures ( ≥ 0.9), CPO development will also govern the strain weakening behavior of other viscously anisotropic minerals, like olivine and quartz. Overall, we emphasize that geodynamic and glaciological models should incorporate CPOs to account for strain weakening, especially at high homologous temperatures.

Is retrograde nailing superior to lateral locked plating for complete articular distal femur fractures?

IntroductionNonunion rates for distal femur fractures treated with lateral locked plating (LLP) remains as high as 18–22% despite significant advances with implant design and construct modulation. However, whether treatment of distal femur fractures with rIMN has improved outcomes compared to LLP has not been well characterized. The purpose of this study was to compare outcomes of complete articular distal femur fractures (AO/OTA 33-C) treated with either LLP or rIMN. Methods106 distal femur fractures in 106 patients between January 2014 and January 2018 were identified. Medical records were reviewed to collect patient age, gender, body mass index, sagittal and coronal plane alignment on immediate postoperative radiographs, time to union, incidence of nonunion, and incidence of secondary operative procedures for repair of a nonunion. ResultsOf 106 patients, 50 underwent rIMN and 56 underwent LLP. The mean age at the time of injury was 51 years (21 to 86 years) and there were 55 males. Average coronal alignment of 83.7° of anatomic lateral distal femoral angle (aLDFA) and sagittal alignment of <1° of apex anterior angulation in the rIMN group. In the LLP group there was an average of 87.9° of aLDFA and 1.9° of apex anterior angulation (p = .005 and p = .36). Average time to union in the rIMN group was 6 months and 6.6 months in the LLP group (p = .52). Incidence of nonunion in the rIMN group was 11.8% and 27.5% in the LLP group (p = .008). There were 8 secondary procedures for nonunion in the rIMN group and 18 in the LLP group (p = .43). ConclusionsOur results demonstrated a higher nonunion rate and coronal plane malalignment with LLP compared to rIMN. While prospective data is required, rIMN does appear to be an appropriate treatment for complete articular distal femur fractures with a potentially decreased rate of nonunion .

Theoretical and Experimental Research on Switching Optimization of No. 9 Single Turnout with 60-kg/m Rails

Based on the necessity of optimizing the structure of No. 9 single turnouts of 60-kg/m rails, we addressed the issues associated with existing turnout switching design methods. Based on finite element analysis, we established a refined calculation model for turnout switching. The model can determine the plane alignment of a switch rail separated from the stock rail based on the actual force acting upon the switch rail. The obtained plane alignment is consistent with the actual situation and is thus reliable. Based on the established turnout switching model, the minimum flangeway width and dynamics between the strokes of the first and second traction points under different conditions were analyzed by numerical simulations. Accordingly, we propose an optimized scheme that takes 160 mm and 85 mm as the stroke value for the first and second traction points, respectively. The scheme helps to meet the requirements for minimum flangeway width while making the deformation of the switch rail more even and therefore minimizing the traction power. Based on the proposed design, trial production and laying of the new No. 9 single turnout with a 60-kg/m rail was conducted, and a switching test was performed. The switching forces at the first and second traction points of the new No. 9 turnout were approximately 1200 and 2000 N, respectively, which were higher than those of existing No. 9 turnouts with 60-kg/m steel rails. Besides, the minimum flangeway width satisfies the requirement for safe vehicle passage with a safety margin of 3–5 mm. The test results proved the effectiveness of the proposed turnout switching design method and parameter optimization scheme.

Lower Limb Alignment in Indian Children: A Radiographic Analysis of Coronal Plane Parameters

Indian children are known to have variations in the tibiofemoral angle as compared to children of other ethnicities. There is no study describing radiographic angles in coronal plane in Indian children. Our aim was to evaluate coronal plane alignment in Indian children. Database of radiographs between January 2011 and December 2019 was searched. Full-length standing radiographs of patients younger than 16years with unilateral congenital or post-traumatic or post-infective deformity were included. The radiographs were measured for mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), tibiofemoral angle (TFA), hip-knee-ankle (HKA) angle, lateral distal tibial angle, mechanical axis deviation (MAD), and mechanical lateral proximal femoral angle. Analysis of 221 lower limbs of 177 children is presented. There were 103 (58.2%) boys and 74 (41.8%) girls. Mean age was 8years, 6months (range: 2years, 1month to 15years, 11months). The mean mLDFA remained constant between 87° and 88° after the age of 5years. The mean MPTA remained around 88° after 8years of age. The mean MAD remained within 4mm of the midpoint of the knee after the age of 8years. The adult value of TFA was achieved after 8years of age. The mLDFA, MPTA, and mLPFA are significant predictors of change in the TFA. The development of tibiofemoral angle in Indian children is slightly different than children of other ethnicities. We recommend using age-specific values for Indian children younger than 8years of age.

Nucleation retardation of cubic boron nitride films caused by the addition of oxygen in argon‑nitrogen sputtering gas

Cross-sectional transmission electron microscopy (TEM) was employed to study the effect of the additive oxygen gas on the microstructure of boron nitride (BN) films especially focusing on the intervening turbostratic BN (tBN) layer's behavior. Films in this study were deposited on diamond coated Si substrates, which were biased with negative voltages, using an unbalanced magnetron sputtering method with a boron carbide target. Various amounts of oxygen were added into argon‑nitrogen mixed sputtering gas. TEM showed that the tBN intervening layer was also observed to form prior to cubic BN (cBN) layer formation for all films, irrespective of oxygen addition. The tBN layer thickness increased with increasing oxygen content. This thickness increase implied that the addition of oxygen delayed cBN phase nucleation. On the other hand, the alignment of the hexagonal BN planes in the tBN layer, estimated from FTIR spectra, was observed to be enhanced with increasing oxygen content. Such alignment enhancement is considered as a result of oxygen adsorption on the tBN layer surface, which suppresses breaking sp2 bonds caused by Ar ion bombardments. The suppression of the sp2 bond breakage, consequently, causes the difficulty of forming sp3 bonds and delays the cBN phase nucleation.

Nailing distal tibial fractures: does entry technique affect distal alignment?

In treating distal third tibial fractures, restoration of the axial alignment and therefore accurate reduction of the distal fragment minimise the risk of tibiotalar joint malalignment. The aim of this study is to investigate whether there was a difference in accuracy of reduction and axial alignment, when nailing distal third tibial fractures using either the suprapatellar or the infrapatellar tibial nailing entry technique. This retrospective cohort study compared alignment of intramedullary nails performed for distal third tibial fractures between 2015 and 2018 through the suprapatellar and infrapatellar approach at a UK Level 1 trauma centre. It compared a consecutive series of 74 suprapatellar nails and 51 infrapatellar nails, with radiographic assessment of tibial alignment in the antero-posterior and sagittal planes. It included inter- and intra-observer analyses of radiographic measurements. In the coronal plane, mean malalignment in the suprapatellar technique group was 2.8 ± 0.7° and 4.7 ± 0.9° in the infrapatellar technique group (P < 0.01). In the sagittal plane, mean malalignment in the suprapatellar technique group was 4.0 ± 0.8° and 3.5 ± 0.9° in the infrapatellar technique group (P = 0.42). Intra- and inter-observer analysis showed strongly positive correlations between observers. We suggest that the suprapatellar technique may improve coronal plane alignment when intramedullary nailing distal tibial fractures. There was no significant difference in alignment in the sagittal plane. We conclude that the suprapatellar technique may be superior in preventing malalignment when treating distal third tibial fractures, potentially improving clinical outcome.

Achieving coronal plane alignment in total knee arthroplasty through modified preoperative planning based on long-leg radiographs: a prospective study

PurposeThis prospective study was undertaken to examine whether the desired coronal plane alignment of limb and prosthetic components in total knee arthroplasty (TKA) could be achieved precisely using conventional jig-based methods by modifying the preoperative planning of bone resection utilizing long-leg radiographs (LLRs).MethodsThe study included consecutive 245 TKA procedures. Pre- and postoperative radiological variables, i.e., the mechanical axis (hip-knee-ankle [HKA] axis), mechanical lateral distal femoral angle (mLDFA), and medial proximal tibial angle (MPTA), and their outliers were evaluated. Statistical analysis was performed using SPSS version 21.0.ResultsThe mean postoperative HKA axis, mLDFA and MPTA was 179.80 ± 1.81° (p < 0.01; 95% CI: 8.09–9.67), 90.35 ± 1.54° (p < 0.01; 95% CI: 1.33–2.02), and 90.26 ± 1.25° (p < 0.01; 95% CI: 4.41–5.20), respectively. The postoperative HKA axis on the coronal plane was 180 ± 3° in 235 knees (95.92%, 4.08% outliers). Femoral and tibial components were implanted in an acceptable position, withing 90 ± 3° of the mechanical axis of the femur and tibia on the coronal plane in 238 (97.14%, 2.86% outliers) and 243 (99.18%, 0.8% outliers) knees, respectively.ConclusionModified preoperative planning for TKA on LLRs is a reliable and consistent method to achieve the desired limb and component alignment on the coronal plane without adding financial or logistical costs.Level of evidenceII

A Systematic Review on Selected Complications of Open-Wedge High Tibial Osteotomy from Clinical and Biomechanical Perspectives.

Background The wedge opened during high tibial osteotomy defines the alignment correction in different body planes and alters soft tissue insertions. Although multiple complications of the surgery can be correlated to this, there is still a lack of consensus on the occurrence of those complications and their cause. The current study is aimed at clarifying this problem using a combined medical and biomechanical perspective. Methods We conducted a systematic review of the literature on selective complications of the surgery correlated with the angles of the opened wedge. Search topics covered tibial slope alteration, patellar height alteration, medial collateral ligament release, and model-based biomechanical simulations related to surgical planning or complications. Findings. The selection process with the defined inclusion/exclusion criteria led to the collection of qualitative and quantitative data from 38 articles. Medial collateral ligament tightness can be a valid complication of this surgery; however, further information about its preoperative condition seems required for better interpreting the results. The posterior tibial slope significantly increases, and the patellar height (using the Blackburne-Peel ratio) significantly decreases in the majority of the selected studies. Model-based biomechanical studies targeting surgical planning are mostly focused on the lower-limb alignment principles and tibiofemoral contact balancing rather than surgical complications. Interpretation. Increased posterior tibial slope, patellar height decrease, and medial collateral ligament tightness can occur due to alterations in different body planes and in soft tissue insertions after wedge opening. This study clarified that information about preoperative alignment in all body planes and soft-tissue conditions should be considered in order to avoid and anticipate these complications and to improve per surgery wedge adaptation. The findings and perspective of this review can contribute to improving the design of future clinical and biomechanical studies.

Optimal surgical component alignment minimizes TKR wear – An in silico study with nine alignment parameters

Currently, preclinical mechanical wear testing of total knee replacements (TKRs) is done using ideally aligned components using standardized TKR level walking under either force or displacement-control regimes. To understand the influence of implant alignment and testing control regime, we studied the effect of nine component alignment parameters on TKR volumetric wear in silico. We used a computational framework combining Latin Hypercube sampling design of experiments, finite element analysis, and a numerical model of polyethylene wear, to create a predictive model of how component alignment affects wear rate for each control regime. Nine component alignment parameters were investigated, five femoral variables and four tibial variables. To investigate perturbations of the nine implant alignment variables, two separate 300-point designs were executed, one for each control regime. The results were then used to generate surrogate statistical models using stepwise multiple linear regression. Wear at the neutral position was 4.5mm3/million cycle and 8.6mm3/million cycle for displacement and force-control, respectively. Stepwise multiple linear regression surrogate models were highly significant for each control regime, but force-control generated a stronger predictive model, with a higher R2, more included terms, and a lower RMSE. Both models predicted transverse plane rotational mismatch can lead to large changes in predicted wear; a transverse plane alignment mismatch of 15° can elicit a change in wear of up to 5mm3/million cycle, almost double that of neutral alignment. Therefore, transverse plane alignment is particularly important when considering failure of the implant due to wear.

Optimizing Whole-Body Kinematics During Single-Leg Jump Landing to Reduce Peak Abduction/Adduction and Internal Rotation Knee Moments: Implications for Anterior Cruciate Ligament Injury Risk.

Knee abduction/adduction moment and knee internal rotation moment are known surrogate measures of anterior cruciate ligament (ACL) load during tasks like sidestepping and single-leg landing. Previous experimental literature has shown that a variety of kinematic strategies are associated or correlated with ACL injury risk; however, the optimal kinematic strategies needed to reduce peak knee moments and ACL injury are not well understood. To understand the complex, multifaceted kinematic factors underpinning ACL injury risk and to optimize kinematics to prevent the ACL injury, a musculoskeletal modeling and simulation experimental design was used. A 14-segment, 37-degree-of-freedom, dynamically consistent skeletal model driven by force/torque actuators was used to simulate whole-body single-leg jump landing kinematics. Using the residual reduction algorithm in OpenSim, whole-body kinematics were optimized to reduce the peak knee abduction/adduction and internal/external rotation moments simultaneously. This optimization was repeated across 30 single-leg jump landing trials from 10 participants. The general optimal kinematic strategy was to bring the knee to a more neutral alignment in the transverse plane and frontal plane (featured by reduced hip adduction angle and increased knee adduction angle). This optimized whole-body kinematic strategy significantly reduced the peak knee abduction/adduction and internal rotation moments, transferring most of the knee load to the hip.

Alternative methods for measuring ankle-foot orthosis alignment in clinical care

Changes in gait due to an ankle foot orthosis (AFO) have been shown to be impacted by the sagittal plane alignment of the AFO, but there is variability in practice and lack of consensus as to how this alignment should be measured. The neutral angle is a measure of AFO alignment that has the potential to be used by various specialties that prescribe, provide, and analyze AFOs. Currently, a lack of validated measurement methods prevents the neutral angle from being used in various clinical settings. Two experimental neutral angle measurement methods are proposed to address this shortcoming: a portable low-cost method for use during AFO fabrication and fitting, and a laboratory-based method for use during dynamic three-dimensional gait analysis (3DGA). What is the concurrent validity of the two experimental neutral angle measurement methods against the gold standard? The gold standard neutral angle measurement (NAGOLD) was prospectively collected during a static 3DGA trial for 19 pediatric AFOs from 10 individuals. While NAGOLD was being collected, the neutral angle was simultaneously measured using digital differential inclinometers (NAINCL). Within the same 3DGA session, the neutral angle was also measured during the swing phase of gait (NASWING). The NAINCL and NASWING measurements were compared to NAGOLD using repeated measures ANOVA, ICC, and bootstrapped errors-in-variables regressions. Repeated measures ANOVA indicated no differences between measurement methods (p = 0.43) and ICC analysis indicated good absolute agreement (ICC(A-1) = 0.85). Mean absolute deviations between the NAINCL and NASWING with NAGOLD measurements were 2.4 ° and 1.9 °, with standard deviations of 2.9 ° and 2.7 °, respectively. Maximum observed differences were less than 7 °. The NAINCL and NASWING methods explained 74 % and 81 % of the variance in NAGOLD, respectively. The concurrent validity of two new neutral angle measurement methods provides alternative means to assess AFO alignment in the clinic.

Finite element analysis of the tibial component alignment in frontal and sagittal plane in total knee arthroplasty

Background. This study aims to analyze the tibial component using the finite element method by cutting the tibial in frontal and sagittal planes at an angle between 1.5° (valgus and anterior tilt) and -1.5° (varus and posterior tilt). Methods. This experimental study used the finite element method as an useful tool for simulating the positioning of the tibial component in order to create a personal pre-operative planning. For the finite element method analysis, a geometrical model of a tibia from a cadaver was three – dimensionally scanned and the tibial component, polyethylene and cement, were three-dimensionally shaped in Computer-Aided Design program using material data such as Young modulus (gigapascal – GPa) and the Poisson coefficient. The analysis determined the equivalent von Mises stress, the maximum displacement of the components and the equivalent von Mises deformation. The results showed that equivalent tension and deformation have higher values in the tibia and the polyethylene, which deform faster than cement and the tibial component. In our study, we chose to simulate the tibial resection at a cutting angle ± 1.5° from neutral positioning (which is represented in frontal plane by the perpendicular on the mechanical axis and in sagittal plane by the posterior slope of 7 degree) in frontal and sagittal plane in order to find the minimum threshold from which the tibial component malalignment may begin to determine unfavorable effects. Results. Our results have shown detrimental effects begin to appear for the polyethene component at -1.5° in frontal plane, and the rest of the components at 1.5° in sagittal plane. Conclusion. This finding leads us to propose preoperative planning based on personal calculus of predefined angles, which may show the surgeon the optimal implantation position of the tibial component.

Short-Term Complications and Outcomes of the Cadence Total Ankle Arthroplasty.

Total ankle arthroplasty (TAA) is an increasingly popular option for the operative treatment of ankle arthritis. The Cadence TAA entered clinical use in 2016 and was designed to address common failure modes of prior systems. We report early complications and radiographic and clinical outcomes of this total ankle system at a minimum of 2 years of follow-up. We performed a retrospective review of a consecutive cohort of patients undergoing primary Cadence TAA by a single surgeon from 2016 to 2017. Complications and reoperations were documented using the American Orthopaedic Foot & Ankle Society (AOFAS) TAA reoperation coding system. Patients completed the Foot and Ankle Ability Measure (FAAM) Activities of Daily Living (ADL) and Sport subscales, SF-12 Mental (MCS) and Physical (PCS) Component Summaries, and visual analog scale (VAS) pain rating (0-100). Radiographic evaluation was performed to assess postoperative range of motion (ROM) of the sole of the foot relative to the long axis of the tibia, alignment, and implant complications. Fifty-eight patients with a mean age of 63.3 years and mean body mass index of 31.9 kg/m2 were included. Twelve of 58 patients (20.7%) underwent an additional procedure(s) within 2 years, including 3 (5.2%) who required removal of one or both components, 2 for infection and 1 for osteolysis. Forty-three patients were followed for a minimum of 2 years with radiographic imaging; 1 patient's (2.3%) radiographs had signs of peri-implant osteolysis, with no cases demonstrating loosening or subsidence. FAAM-ADL, FAAM-Sport, SF-12 PCS, and VAS pain scores all improved at a mean of 27.4 months postoperatively, with mean score changes (± SD) of 16.3 (± 22.0), 25.3 (± 24.5), 6.0 (± 11.1), and -32.3 (± 39.8), respectively. Radiographic analysis revealed that average coronal alignment improved from 6.9 degrees from neutral preoperatively to 2.3 degrees postoperatively. The average ROM of the foot relative to the tibia was 36.5 degrees total arc of motion based on lateral radiographs. Early experience with this 2-component total ankle replacement was associated with a high component retention rate, improved coronal plane alignment, good postoperative ROM, radiographically stable implants, and improved patient function. Level IV, case series.

Finite element analysis of the tibial component alignment in a transverse plane in total knee arthroplasty.

The research aims to analyze the tibial component rotation using the finite element method by resecting the tibia in a transverse plane at an angle between 1.5° (external rotation) and -1.5° (internal rotation). We used a three-dimensional scanner to obtain the tibia's geometrical model of a cadaveric specimen. We then exported the surfaces of the tibial geometrical model through the Computer-Aided Three-dimensional Interactive Application (CATIA), which is a Computer-Aided Design (CAD) program. The CAD program three-dimensionally shaped the tibial component, polyethylene, and cement. Our analysis determined that the maximum equivalent stress is obtained in the case of proximal tibial resection at -1.5° angle in a transverse plane (internal rotation) with a value of 12.75 MPa, which is also obtained for the polyethylene (7.693 MPa) and cement (6.6 MPa). The results have shown that detrimental effects begin to occur at -1.5°. We propose the use of this finite element method to simulate the positioning of the tibial component at different tibial resection angles to appreciate the optimal rotation.

Spinal curvatures of yoga practitioners compared to control participants-a cross-sectional study.

PurposeThe angles of thoracic kyphosis and lumbar lordosis determine the spinal alignment in the sagittal plane. The aim of this study was to compare the thoracic kyphosis and lumbar lordosis of male and female yoga practitioners with non-practicing participants and to determine the possible dependencies between sagittal spinal curvatures and somatic parameters, time spent on yoga exercise, and undertaking other physical activities in yoga practitioners.MethodsThe study involved 576 women and 91 men ages 18–68 years (mean = 38.5 ± 9) who were practicing yoga, and 402 women and 176 men ages 18–30 years (mean = 20.2 ± 1.3) as a control group. The angles of thoracic kyphosis and lumbar lordosis were measured using a Plurimeter-V gravity inclinometer.ResultsThe two-way ANOVA demonstrated the influence of group (p < .0001) and sex (p = .03) on the angle of thoracic kyphosis, as well as the influence of group (p < .0001) and sex (p < .0001) on the angle of lumbar lordosis. It was noted that yoga practitioners had less pronounced thoracic kyphosis and lumbar lordosis and were more often characterized by normal or smaller thoracic kyphosis and lumbar lordosis than students from the control group. In yoga practitioners, the angle of thoracic kyphosis was positively correlated with age, body mass, BMI, and undertaking other forms of physical activity. The angle of lumbar lordosis was negatively correlated with body height and body mass.ConclusionsThe results suggest that yoga exercises can affect the shape of the anterior-posterior curves of the spine and may be an efficient training method for shaping proper posture in adults.