Three-dimensional Bone Models Research Articles

Influence of Axial Rotation Between the Femoral Neck and Ankle Joint on Kinematics in Normal Knees: A Cross-Sectional Study.

The effect of axial rotation between the femoral neck and ankle joint (total rotation [TR]) on normal knees is unknown. Therefore, this study aimed to investigate the TR effect on normal knee kinematics. Volunteers were divided into groups large (L), intermediate (I), and small (S), using hierarchical cluster analysis based on TR in the standing position. TR was measured using three-dimensional (3D) bone models generated from CT. A two-dimensional to 3-dimensional registration technique was used to assess the spatial position and femur and tibia orientation during squat. The axial rotation, varus-valgus alignment, and anterior-posterior translation of the femur relative to the tibia were evaluated. Group L had the highest TR, whereas group S had the lowest TR (L: 36.6° ± 6.0°, I: 23.2° ± 3.0°, and S: 13.8° ± 5.1°). Above 50° of flexion, femoral external rotation was greater in group S than in groups L and I. From 40° to 110°, the medial side was more anterior in group L than in groups I and S, whereas the lateral side was more posterior in group S than in groups L and I. Individuals with larger TR had more femur anterior-medial translation relative to the tibia.

Computed-tomography-based three-dimensional analysis of bilateral differences in phalanges.

Three-dimensional analysis of bones, especially for preoperative planning of corrective osteotomy in fracture malunion, assumes that the bilateral extremities exhibit a symmetrical mirror image when projected onto each other. No studies are available for phalanges. Three-dimensional bone models of all phalanges of 20 healthy participants (40 hands) were created from computed tomography data. For each phalanx, the difference between the left and right sides were assessed with respect to axis of rotation, ulnoradial deviation, flexion-extension and bone length. The average absolute side difference was small, but with significant differences of extension-flexion (mean 1.1°), supination-pronation (mean 1.8°), ulnoradial deviation (mean 0.9°) and translation (mean 0.2 mm). All left proximal phalanges were significantly pronated in comparison to the right side. The differences are likely unimportant, especially in corrective osteotomy using advanced 3D techniques.

Optimal angles for independent femoral tunnel drillings to prevent damage to anatomic structures in single-bundle anterior cruciate ligament reconstruction

PurposeTo determine the optimal angles for independent femoral tunnel drillings in single-bundle anterior cruciate ligament reconstruction (ACLR) in different races and genders with the aim of preventing damage to lateral femoral anatomic structures (LFAS), posterior cortex and medial femoral condyle.MethodsThis study included 180 volunteers, including 90 Caucasian and 90 matched Chinese. Magnetic resonance imaging (MRI) was used to scan the knees to create three-dimensional bone models, the ACL femoral footprint centre and the LFAS. In each femur model, femoral tunnels were established using a set of 16 distinct angular combinations: 15°, 30°, 45°, and 60° in the axial plane, as well as 15°, 30°, 45°, and 60° in the coronal plane. The minimum distance from the tunnel exit to the LFAS was evaluated, and the tunnel length, posterior cortex damage and medial femoral condyle injury were assessed.ResultsAmong the 180 patients with simulated ACL femoral tunnels, there was damage to the anatomical structure in parts of the model. According to the Cochran Q test results (P < 0.001), the percentage of safe tunnels varied significantly among the 16 different drilling angle combinations. The overall occurrence of the tunnel exit causing injury to LFAS were 8.3% and 8.1% in Chinese and Caucasian groups (P = 0.786). The means for tunnel length in Caucasians was 40.1 ± 7.9 mm, respectively; for Chinese, the results was 38.8 ± 6.6 mm (P < 0.001). Females had significantly shorter femoral tunnels than males in both Chinese and Caucasian (P < 0.001). The overall invasion rate of the posterior cortex and medial femoral condyle were 32.6% and 7.4% for Chinese; 31.0% and 7.4% for Caucasians, respectively.ConclusionTo reduce risks of injury to anatomical structures, such as the LFAS, posterior cortex and medial femoral condyle, specific angle combinations of 30°/45°, 45°/30°, 45°/45°, 45°/60°, 60°/30°, 60°/45° and 60°/60° should be used when creating the femoral tunnel in single-bundle ACLR. The selected drilling angles are critical for optimizing femoral tunnel placement.

Hybrid Closing-Wedge Distal Tuberosity Tibial Osteotomy Using Patient-Specific Instrumentation (PSI) in Post-fracture Malunion. A technical note

BackgroundHigh tibial osteotomy (HTO) is an effective treatment option for deformity correction after fracture. However, performing precise corrective osteotomy for cases with a severe varus deformity and a significant posterior slope poses a significant challenge. Three-dimensional (3D) bone model construction and patient-specific instrumentation (PSI) created from preoperative Computed tomography (CT) may be useful tools in achieving successful outcome for such cases. The present technique describes a hybrid closing-wedge distal tuberosity tibial osteotomy (Hybrid CWDTO) using two PSIs.MethodsPreoperative planning was performed in 3D with reference to the contralateral normal lower extremity CT taken preoperatively, which was then mirrored for analysis. A full-scale bone model and two PSIs were constructed based on this plan to allow for complex correction. During surgery, osteotomy was performed using these sterilized PSIs as guides.ResultsRadiographic imaging showed that medial proximal tibial angle (MPTA) improved from 68 to 84 degrees and posterior tibial slope (PTS) improved from 19 to 6 degrees. The standing leg radiograph showed a mechanical varus alignment improvement from 12 to 3 degrees. The 2011 Knee Society Scoring system (2011 KSS) improved from 31 to 95 in objective knee indicators, from 10 to 24 in symptoms, from 14 to 40 in patient satisfaction and from 51 to 95 in activities.ConclusionHybrid CWDTO using PSIs is a useful surgical technique for alignment correction post-malunion while also achieving high patient satisfaction. This can assist surgeons in treating complex deformities that are otherwise difficult to treat.

High variability exists in 3D leg alignment analysis, but underlying principles that might lead to agreement on a universal framework could be identified: A systematic review.

To (1) investigate the hypothesis that there is high variability in the reported methods to derive axes and joint orientations from three-dimensional (3D) bone models to (a) perform 3D knee-related leg alignment analysis and (b) define coordinate systems for the femur, tibia and leg and (2) identify underlying principles that might lead to agreement on a universal 3D leg alignment analysis framework. A systematic review of the literature between January 2006 and June 2024 was performed. Articles explicitly reporting methods to derive axes and joint orientations from CT-based 3D bone models for alignment parameters and/or coordinate systems of the femur, tibia and leg were included. Study characteristics and reported methods were extracted and presented as a qualitative synthesis. A total of 93 studies were included. There was high variability in the reported methods to derive axes and joint orientations from 3D bone models. Nevertheless, the reported methods could be categorized into four groups, and several underlying principles of the four groups could be identified. Furthermore, the definitions of femoral and tibial coordinate systems were most frequently based on the mechanical axis (femoral, 13/19 [68%]; tibial, 13/26 [50%]) and a central medial-lateral axis (femoral, 16/19 [84%]; tibial, 12/26 [46%]); no leg coordinate system was reported. Interestingly, of the included studies that reported on leg alignment parameters (76/93, 82%), only a minority reported expressing these in a complete coordinate system (25/76, 33%). There is high variability in 3D knee-related leg alignment analysis. Therefore, universal 3D reference values for alignment parameters cannot yet be defined, and comparison of alignment parameter values between different studies is impossible. However, several underlying principles to the reported methods were identified, which could serve to reach more agreement on a future universal 3D framework for leg alignment analysis. Level I (1).

The influence of talus size and shape on in vivo talocrural hopping kinematics.

Talus morphology (shape and size) plays a pivotal role in talocrural joint function. Despite its importance, the relationship between talus morphology, particularly the talar dome, and dynamic, in vivo talocrural function is poorly understood. Understanding these form-function relationships in a healthy cohort is essential for advancing patient-specific treatments aimed at restoring function. Nine participants (five females) hopped on one leg while biplanar videoradiography and ground reaction forces were simultaneously collected. Three-dimensional bone models were created from computed tomography scans. Helical axes of motion were calculated for the talus relative to the tibia (rotation axes), and a cylinder was fitted through the talar dome (morphological axis). Bland-Altman plots and spatial angles were used to examine the level of agreement between the rotation and morphological axes. A shape model of 36 (15 females) participants was established, and a cylinder fit was morphed through the range of ±3 standard deviations. The rotation and morphological axes largely agree regarding their orientation and location during hopping. The morphological axes were consistently oriented more anteriorly during landing than the rotation axes. Some shape components affect talar dome orientation and curvature independent of size. This suggests that besides bone size, the shape of the talar dome might influence the movement pattern during locomotion. Our findings may further inform talocrural joint arthroplasty design.

Design and Implementation of Gesture Music Composition System based on RealSense and Recurrent Neural Network

Aiming at the problems of slow human-computer interaction and low accuracy of hand gesture recognition (HGR) in music composition systems such as human-computer interaction, gesture recognition, and algorithmic composition, this paper designs an HGR music composition system based on real-sense technology and recurrent neural network. The system uses an Intel RealSense 3D camera to shoot the user's hand and extract the information on the hand joint points with Smart Wearable Biosensors (SWBSs). The joint points are used to construct a three-dimensional model of the hand bone, and the joint points' equivalent distance and joint deflection are calculated by the joint point information to match the corresponding Curwen HGR. The matching music data is input into the recurrent neural network. GRU is combined with the Markov chain algorithm to complete the composition and avoid the phenomenon of gradient disappearance or gradient explosion. The HGR recognition function and composition algorithm are simulated and tested to verify the method's feasibility. Cohort verification investigations and efficacy evaluations of wearable biosensors are essential to support their clinical acceptability. The research results show that the HGR music composition system based on real-sense technology and recurrent neural networks can effectively identify the tester's HGRs and assist the tester in completing the composition using intelligent biosensors. The composition mode is close to the professional composition process.

The Three-Dimensional Relationship of the Axes of the Capitate and Third Metacarpal

We quantified the morphology and angulation of the third metacarpal (MC3) relative to the capitate using three-dimensional computed tomography data to inform surgical procedures such as total wrist arthroplasty and wrist arthrodesis. Specifically, we report the three-dimensional location of the intersections of the long axis of MC3 axis with the capitate cortical surface, the sagittal and coronal angles between the MC3 and capitate axes, and the MC3 shaft angle in the sagittal plane. We tested the hypothesis that these metrics did not differ between women and men. Three-dimensional bone models of the capitate and MC3 were analyzed in 130 subjects (61M and 69F). Long axes of the MC3 and capitate were computed. The intersection of the metacarpal long axis with the cortical surface of the capitate, the angle between the metacarpal-capitate axes, and metacarpal shaft angle were calculated and compared between men and women. The long axis of the MC3 intersected the capitate at two locations on the outer cortical surface of the capitate. The proximal intersection was located near the midportion of the capitate, whereas the distal intersection was typically located within the capitate-MC3 articulation. The angle between the axes of the capitate and MC3 in the sagittal plane was a mean of 15°, ranging from 5° to 23°. The mean sagittal MC3 shaft angle was 166° and ranged from 158° to 173°.There were only subtle differences in these metrics between the sexes. The long axis of the MC3 penetrates the dorsal surface of the capitate about its midportion, but there is notable variation in this location as well as in the angular relationships. Three-dimensional measurements of the relationships between the third metacarpal and the capitate may serve as an important reference for the placement of intramedullary wires, plates, devices, and prosthetics.

Scapular morphology does not predict supraspinatus tendon tear propagation following an individualised exercise therapy programme.

To determine whether scapular morphology could predict isolated supraspinatus tendon tear propagation after exercise therapy. We hypothesised that a larger critical shoulder angle (CSA) and type III acromial morphology predict a positive change in tear size. Fifty-nine individuals aged 40-70 years with isolated symptomatic high-grade partial or full-thickness supraspinatus tendon tears were included. Individuals participated in a structured, individualised 12-week exercise therapy programme and underwent ultrasound to measure tear size at baseline and 12 months following therapy. Computed tomography images were segmented to create three-dimensional subject-specific bone models and reviewed by three trained clinicians to measure CSA and to determine acromion morphology based on the Bigliani classification. A binary logistic regression was performed to determine the predictive value of CSA and acromion morphology on tear propagation. The CSA was 30.0 ± 5.4°. Thirty-one individuals (52.5%) had type II acromial morphology, followed by type III and type I morphologies (25.4% and 22.0%, respectively); 81.4% experienced no change in tear size, four (6.8%) individuals experienced tear propagation and seven (11.9%) individuals had a negative change in tear size. No significant difference in tear propagation rates based on CSA or acromion morphology (not significant [NS]) was observed. The model predicted tear size status in 81.4% of cases but only predicted tear propagation 8.3% of the time. Overall, CSA and acromion morphology only predicted 24.3% (R 2 = 0.243) of variance in tear propagation (NS). CSA and acromion morphology were NS predictors of tear propagation of the supraspinatus tendon 12 months following an individualised exercise therapy programme. II.

Impact of arthroscopy on post-procedure intra-articular elbow injections: A cadaveric study.

To determine the influence of arthroscopy and injection volume on post-procedure intra-articular (IA) injection extravasation. Ex vivo prospective study. A total of 40 paired canine cadaver forelimbs. After radiographs and computed tomography (CT) scans with three-dimensional (3D) digital bone model reconstructions, elbows were randomly assigned to the arthroscopy or control group and randomly assigned to receive an IA injection of 2 or 4 mL of contrast. Elbow arthroscopy was performed on assigned specimens, followed by IA injections of contrast in all elbows, and imaging was repeated. 3D digital model volumes were compared. Images were interpreted and scored for extravasation by a radiologist unaware of treatment and volume assignments. Based on CT images and regardless of treatment group, IA injections of 4 mL resulted in a mean extravasation score of 2.25 (SD 0.97) versus 1.55 (SD 1.05) (p = .02) for 2 mL IA injections. The change in 3D model volumes after IA injections was a mean of 13.2 cm3 (SD 5.85) after 4 mL injections, compared to 6.97 cm3 (SD 6.28) (p = .003) after 2 mL injections. On radiographic evaluation, but not CT, the mean extravasation scores were 2.45 (SD 1.15) for the arthroscopy group and 1.25 (SD 0.79) for the control group (p < .001). A larger volume of IA injection resulted in higher CT extravasation scores and larger 3D volumes regardless of arthroscopic treatment. IA injections performed immediately after arthroscopy resulted in 50% or less extravasation, especially with a smaller IA injection volume.

Biomechanical Effects of Ti-Base Abutment Height on the Dental Implant System: A Finite Element Analysis.

This study aims to analyse, using a finite element analysis, the effects of Ti-base abutment height on the distribution and magnitude of transferred load and the resulting bone microstrain in the bone-implant system. A three-dimensional bone model of the mandibular premolar section was created with an implant placed in a juxta-osseous position. Three prosthetic models were designed: a 1 mm-high titanium-base (Ti-base) abutment with an 8 mm-high cemented monolithic zirconia crown was designed for model A, a 2 mm-high Ti-base abutment with a 7 mm-high crown for model B, and a 3 mm-high abutment with a 6 mm-high crown for model C. A static load of 150 N was applied to the central fossa at a six-degree angle with respect to the axial axis of the implant to evaluate the magnitude and distribution of load transfer and microstrain. The results showed a trend towards a direct linear association between the increase in the height of the Ti-base abutments and the increase in the transferred stress and the resulting microstrain to both the prosthetic elements and the bone/implant system. An increase in transferred stress and deformation of all elements of the system, within physiological ranges, was observed as the size of the Ti-base abutment increased.

Tibial spine volume is smaller in ACL-injured athletes compared to healthy athletes.

The aim of this study was to investigate whether the whole tibial spine volume and femoral intercondylar notch volume are risk factors for anterior cruciate ligament (ACL) injury. The hypothesis was that the whole tibial spine volume and femoral notch volume would be smaller in athletes who sustained ACL injury than in athletes with no history of ACL injury. Computed tomography scans of both knees were acquired and three-dimensionalbone models were created using Mimics to measure whole tibial spine volume and femoral notch volume. Tibial spine volume, femoral notch volumeand each of these volumes normalised by tibial plateau area were compared between the ACL-injured andthe ACL-intact group. Fifty-one athletes undergoing unilateral anatomical ACL reconstruction (17 female, 34 male: average age 22.0 ± 7.5) and 19 healthy collegiate athletes with no previous knee injury (eight female, 11 male: average age 20.1 ± 1.3) were included in this study. The whole tibial spine volume in the ACL-injured group(2.1 ± 0.5 cm3) was 20.7% smaller than in the ACL-intact group (2.7 ± 0.7 cm3) (p = 0.005). No differences were observed between the femoral notch volume in the ACL-injured group(9.5 ± 2.1 cm3) and the ACL-intact group (8.7 ± 2.7 cm3) (n.s.). The main finding of this study was that the whole tibial spine volume of the ACL-injured group was smaller than the ACL-intact group. A small tibial spine volume can be added to the list of anatomical risk factors that may predispose athletes to ACL injury. Level Ⅲ.

Evaluating Angled Abutments: Three-Dimensional Finite Element Stress Analysis of Anterior Maxillary Implants

Restorative dentistry is the repairing of damaged teeth and restoring oral health and function. Dental implants are typically placed within the cortical bone of the jaw to provide stability and support for prosthetic restorations. The successful restoration of complex anatomical features of the maxillary anterior is difficult for prosthodontists. Using a 3D slicer, CT scan images were used to create a detailed three-dimensional model of the maxilla bone. This study utilizes ANSYS Workbench, a finite element software program, to analyze the abutment angles, ranging from 0° to 25°, and the impact stress distribution within peri-implant bone. The outcomes of our studies align with and substantiate certain evidence in the literature documenting bone resorption, specifically at the level of the implant neck and near the cortical bone. The study aims to provide a comprehensive understanding of angled abutment stress patterns in the bone surrounding dental implants, offering valuable insights for clinical applications in critical areas of the mouth.

Effects of Scapular Angular Deviations on Potential for Rotator Cuff Tendon Mechanical Compression.

One proposed mechanism of rotator cuff disease is scapular motion impairments contributing to rotator cuff compression and subsequent degeneration. To model the effects of scapular angular deviations on rotator cuff tendon proximity for subacromial and internal mechanical impingement risk during scapular plane abduction. Descriptive laboratory study. Three-dimensional bone models were reconstructed from computed tomography scans obtained from 10 asymptomatic subjects and 9 symptomatic subjects with a clinical presentation of impingement syndrome. Models were rotated to average scapular orientations from a healthy dataset at higher (120°) and lower (subject-specific) humeral elevation angles to investigate internal and subacromial impingement risks, respectively. Incremental deviations in scapular upward/downward rotation, internal/external rotation, and anterior/posterior tilt were imposed on the models to simulate scapular movement impairments. The minimum distance between the rotator cuff insertions and potential impinging structures (eg, glenoid, acromion) was calculated. Two-way mixed-model analyses of variance assessed for effects of scapular deviation and group. At 120° of humerothoracic elevation, minimum distances from the supraspinatus and infraspinatus insertions to the glenoid increased with ≥5° changes in upward rotation (1.6-9.8 mm, P < .001) or external rotation (0.9-5.0 mm, P≤ .048), or with ≥10° changes in anterior tilt (1.1-3.2 mm, P < .001). At lower angles, ≥20° changes in most scapular orientations significantly increased the distance between the supraspinatus and infraspinatus insertions and the acromion or coracoacromial ligament. A reduction in scapular upward rotation decreases the distance between the rotator cuff tendon insertions and glenoid at 120° humerothoracic elevation. Interpretation is complicated for lower angles because the humeral elevation angle was defined by the minimum distance. These results may assist clinical decision making regarding the effects of scapular movement deviations in patients with rotator cuff pathology and scapular dyskinesia and may help inform the selection of clinical interventions.

Preoperative Simulation for Complication Control in Spinal Surgery

The craniovertebral junction not only contains anatomically important structures such as the medulla oblongata, upper cervical spinal cord, and vertebral artery, but also controls the dynamic movements of flexion, extension, and rotation of the head and neck. Consequently, instability and spinal deformities can easily occur in the craniovertebral region, and appropriate treatment should be selected based on the specificity of the lesion. Basilar invagination often involves bone and vascular anomalies and fusion surgery is often required. Therefore, careful pre-operative simulations are necessary. The creation and use of three-dimensional bone models, including image navigation, are useful for surgical simulation.

Bone deformity in sports-related elbow osteoarthritis: influence of osteochondritis dissecans of the capitellum-a cross-sectional study.

Sports activity can cause elbow osteoarthritis, which subsequently induces bone deformity. Osteochondritis dissecans (OCD) of the capitellum develops defects of articular surfaces and can exacerbate bone deformity. This study aimed to investigate whether OCD exacerbates deformities in sports-related elbow osteoarthritis. Twenty-one patients who underwent bilateral computed tomography preoperatively followed by surgery for sports-related elbow osteoarthritis were included. Patients were divided into two groups according to the presence or absence of an OCD history: OCD + (n = 6) and OCD- (n = 15). Bilateral three-dimensional bone models of the humerus, ulna, and radius were created using computed tomography data, and bone deformities were extracted by subtracting healthy mirror models from the affected models using a Boolean operation. Bone deformities were divided into 22 regions in the 3 bones. The volume of the deformity was estimated by correlating the anteroposterior and lateral diameters of the OCD and by comparing the two groups. The anteroposterior diameter of the OCD correlated with the articular surface of the medial trochlear notch, whereas the lateral diameter correlated with the whole ulna, medial gutter of the ulna, whole radius, and lateral side of the radial head. The deformities were 2.2 times larger in the whole humerus, 1.9 times larger in the whole ulna, and 3.0 times larger in the whole radius in the OCD + group than in the OCD- group. The deformities were significantly larger in the OCD + group than in the OCD- group in the radial fossa, posterior capitellum, medial gutter, and lateral gutter in the humerus, medial gutter in the ulna, and lateral, anterior, and posterior sides of the radial head. Larger OCD exacerbated deformity in elbow OA, and the presence of OCD exacerbated deformities in sports-related elbow OA. These results demonstrate the highlight of preventing OCD progression.

Elucidation of the radius and ulna fracture mechanisms in toy poodle dogs using finite element analysis.

Fractures occurring in the distal radius and ulna of toy breed dogs pose distinctive challenges for veterinary practitioners, requiring specialized treatment approaches primarily based on anatomical features. Finite Element Analysis (FEA) was applied to conduct numerical experiments to determine stress distribution across the bone. This methodology offers an alternative substitute for directly investigating these phenomena in living dog experiments, which could present ethical obstacles. A three-dimensional bone model of the metacarpal, carpal, radius, ulna, and humerus was reconstructed from Computed Tomography (CT) images of the toy poodle and dachshund forelimb. The model was designed to simulate the jumping and landing conditions from a vertical distance of 40 cm to the ground within a limited timeframe. The investigation revealed considerable variations in stress distribution patterns between the radius and ulna of toy poodles and dachshunds, indicating notably elevated stress levels in toy poodles compared to dachshunds. In static and dynamic stress analysis, toy poodles exhibit peak stress levels at the distal radius and ulna. The Von Mises stresses for toy poodles reach 90.07 MPa (static) and 1,090.75 MPa (dynamic) at the radius and 1,677.97 MPa (static) and 1,047.98 MPa (dynamic) at the ulna. Conversely, dachshunds demonstrate lower stress levels for 5.39 MPa (static) and 231.79 MPa (dynamic) at the radius and 390.56 MPa (static) and 513.28 MPa (dynamic) at the ulna. The findings offer valuable insights for modified treatment approaches in managing fractures in toy breed dogs, optimizing care and outcomes.

Finite element study on post-screw removal stress in toy poodle radius with different plate designs and screw arrangements.

The study employs finite element analysis to investigate stress distribution in the radius of toy poodles after screw removal. The examination focuses on the biomechanical implications of varied screw hole configurations using 1.5 and 2.0-mm locking compression plates (LCPs) with notched head T-Plates. To provide a noninvasive approach to analyzing the immediate consequences of screw removal from the radius bone in toy poodles. Specifically, it explores the impact of varied plate designs and screw arrangements on stress distribution within the forelimb bones. The study constructs a three-dimensional bone model of the toy poodle's forelimb based on computed tomography (CT) images. Simulations were designed to replicate jumping and landing from a 40 cm height, comparing stress distribution in the radius post-screw removal. The analysis reveals significant variations in stress distribution patterns between the two LCPs. The radius implanted with the 2.0-mm LCP displays a uniform stress distribution, contrasting with the 1.5-mm plates. Localized stress concentration is observed around the screw holes, while trabecular bone regions near the screw holes exhibit lower stress levels. The study highlights the plate designs and screw configurations that affect bone stress in toy poodle forelimbs post-screw removal. The findings provide valuable insights for veterinarians, aiding informed decisions in veterinary orthopedic practices.

How Does the Subchondral Bone Density Distribution of the Distal Humerus Change Between Early and Advanced Stages of Osteoarthritis?

The distribution of subchondral bone density in a joint represents stress that is applied to the joint. Knowing this information is important for understanding the pathophysiology of osteoarthritis (OA). In the elbow, however, this has not been studied before. (1) Is advanced-stage elbow OA associated with more radially distributed subchondral bone density than earlier stages? (2) What demographic (age and sex) and radiographic (osteophyte location and carrying angle) factors are associated with increased radial shift in subchondral bone density? Between March 2001 and December 2021, we treated 301 patients for elbow OA. We considered patients with plain radiographs and conventional CT scans as potentially eligible. Thus, 68% (206 patients) were eligible; a further 27% (80 patients) were excluded because of a history of any injury or surgery or known inflammatory joint disease, leaving 42% (126 patients) for analysis here. Their mean ± standard deviation age was 60 ± 10 years. Early OA with minimal joint space narrowing and osteophyte formation was found in 33% (42 of 126) of patients, and advanced OA was found in the remaining 67% (84 of 126). Three-dimensional distal humerus subchondral bone models were derived from CT images, and in the central intra-articulating portion, we measured the subchondral bone density in two different sites: where it articulates with the radius (SBD rad ) and with the ulna (SBD ulna ). We further defined the SBD ratio as the percent ratio of SBD rad to SBD ulna . We also evaluated osteophyte severity based on its size at the radiocapitellar and ulnotrochlear joints, and alignment through measuring the carrying angle on radiographs. To assess interobserver reliability, two orthopaedic surgeons took measurements independently from each other. All measurements had excellent intraoberver and interobserver reliabilities. Then, we compared the subchondral bone parameters between early and advanced OA and performed a multivariable analysis of the factors associated with subchondral bone parameters, including age, sex, osteophyte location, and carrying angle. Radial versus ulna subchondral bone density (SBD ratio ) was modestly higher in patients with advanced OA (118% ± 17%) than in patients with early OA (109% ± 17%, mean difference 9% [95% CI 2.3% to 15.3%]; p = 0.01). With increasing radial deviation in subchondral bone density, cubitus valgus had a modest association (β = 0.46 ± 0.23; p = 0.04) and severe osteophytes at the radiocapitellar joint had a large association (β = 9.51 ± 3.06; p = 0.002). According to subchondral bone density distribution, stress concentration was more radially deviated in patients with the advanced stages of elbow OA than in those with the early stages. We also found that an increase in carrying angle is associated with radial deviation of stress. A future study that examines longitudinal changes in the subchondral bone density might be required to confirm changes in stress concentration with OA progression. This study gives us insight into the potential pathophysiology of elbow OA in relation to elbow alignment. Although debridement of osteophytes in the ulnotrochlear joint is the most frequently performed procedure in patients with advanced elbow OA, our finding suggests that some patients with an increased carrying angle might benefit from management of the radiocapitellar joint as well, or from being informed of the future development of OA in the radiocapitellar joint, because stress at this site can be increased with the advancement of OA.

In Vivo Kinematic Analysis of the Axial Shoulder Rotation in the Standing and Supine Positions Using 3D/2D Registration and Electromyography.

Background There has been no report comparing shoulder kinematics and muscle activities during axial shoulder rotation in different positions. The purpose of this study was to investigate differences in shoulder kinematics and muscle activities during axial shoulder rotation in healthy subjects between standing and supine positions using three-dimensional/two-dimensional (3D/2D) registration techniques and electromyography (EMG). Methods Eleven healthy males agreed to participate in this study. We recorded the fluoroscopy time during active shoulder axial rotation with a 90° elbow flexion in both standing and supine positions, simultaneously recording surface EMG of the infraspinatus, anterior deltoid, posterior deltoid, and biceps brachii. Three-dimensional bone models were created from CT images, and shoulder kinematics were analyzed using 3D/2D registration techniques. Muscle activities were evaluated as a ratio of mean electromyographic values to 5-sec maximum voluntary isometric contractions. Results Scapular kinematics during axial shoulder rotation in the supine position showed similar patterns with those in the standing position. The scapula was more posteriorly tilted and more downwardly rotated in the supine posture than in standing (P < 0.001 for both). Acromiohumeral distance (AHD) in the supine posture was significantly larger than in standing. Muscle activities showed no significant differences between postures except for biceps (P < 0.001). Discussion Shoulder kinematics and muscle activities during axial rotation were similar in pattern between standing and supine postures, but there were shifts in scapular pose and AHD. The findings of this study suggest that posture may be an important consideration for the prescription of optimal shoulder therapy following surgery or for the treatment of shoulder disorders.