Head Joint Research Articles

Early Postoperative Activities of Daily Living Do Not Adversely Affect Joint Torques or Translation Regardless of Capsular Condition: A Cadaveric Study

To evaluate the impact of capsular management on joint constraint and femoral head translations during simulated activities of daily living (ADL). Using 6 (n= 6) cadaveric hip specimens, the effect of capsulotomies and repair was then evaluated during simulated ADL. Joint forces and rotational kinematics associated with gait and sitting, adopted from telemeterized implant studies, were applied to the hip using a 6-degrees of freedom (DOF) joint motion simulator. Testing occurred after creation of portals, interportal capsulotomy (IPC), IPC repair, T-capsulotomy (T-Cap), partial T-Cap repair, and full T-Cap repair. The anterior-posterior (AP), medial-lateral (ML), and axial compression DOFs were operated in force control, whereas flexion-extension, adduction-abduction, and internal-external rotation were manipulated in displacement control. Resulting femoral head translations and joint reaction torques were recorded and evaluated. Subsequently, the mean-centered range of femoral head displacements and peak signed joint restraint torques were calculated and compared. During simulated gait and sitting, the mean range of AP femoral head displacements with respect to intact exceeded 1% of the femoral head diameter after creating portals, T-Caps, and partial T-Cap repair (Wilcoxon signed rank P < .05); the mean ranges of ML displacements did not. Deviations in femoral head kinematics varied by capsule stage but were never very large. No consistent trends with respect to alterations in peak joint restrain torques were observed. In this cadaveric biomechanical study, capsulotomy and repair minimally affected resultant femoral head translation and joint torques during simulated ADLs. The tested ADLs appear safe to perform after surgery, regardless of capsular status, because adverse kinematics were not observed. However, further study is required to determine the importance of capsular repair beyond time-zero biomechanics and the resultant effect on patient-reported outcomes.

Evaluation of the relationship between the attachment type of lateral pterygoid muscle and the position of temporomandibular joint disc in patients with temporomandibular joint disorders based on wireless amplified MRI detector high resolution imaging

Objective: To explore the correlation between the attachment type of lateral pterygoid muscle (LPM) and the position of temporomandibular joint (TMJ) disc in patients with temporomandibular disorders (TMD) by using wireless amplified magnetic resonance imaging detector (WAND) coupled with conventional head and neck joint coil for high resolution imaging of TMJ. Methods: Eighty-five patients with TMD diagnosed by oral and maxillofacial surgeons of Guizhou Provincial People's Hospital from October 2019 to January 2022 were collected. A total of 160 TMJ were included. There were 16 males and 69 females, aged (32.7±14.2) years. All patients were scanned with open, closed oblique sagittal and coronal WAND coupled head and neck coils with bilateral TMJ. Based on TMJ and LPM high resolution imaging, to explore the correlation between LPM attachment types and the position of TMJ disc in TMD patients, and to evaluate the potential clinical value of LPM attachment types in TMD patients. χ2 test and Pearson correlation analysis were used to evaluate the correlation between LPM attachment type and TMJ disc location. Results: There were three types of LPM attachment: type Ⅰ in 51 cases [31.9% (51/160)], type Ⅱ in 77 cases [48.1% (77/160)] and type Ⅲ in 32 cases [20.0% (32/160)]. There was a significant correlation between the type of LPM attachment and the position of articular disc (χ2=28.20, P=0.002, r=0.776). There was no statistical significance between the type of LPM attachment and the reversible displacement of articular disc (χ2=0.24, P=0.887, r=0.825). Conclusions: There is a correlation between the attachment type of LPM and the position of the disc in TMD patients. WNAD coupled with conventional head and neck joint coil TMJ high resolution scan can provide reliable imaging evidence for TMD patients in evaluating the type of LPM attachment and the location of disc.

Finite element analysis of unreinforced masonry walls with different bond patterns

Masonry is the oldest building material, yet it is also the least understood due to the non-linear and composite nature of masonry, which consists of brick units, mortar, and unit-mortar contact. In this paper, the response of a two-dimensional masonry wall with a window opening subjected to an in-plane lateral pushover loading is simulated by varying the interface properties of brick such as crushing, elastic, cracking, and shear properties. The simplified micro-modeling technique with the Engineering Masonry model for bricks and linear stiffness properties for the interfaces in the bed and head joints is employed to investigate the geometric nonlinear behavior of the masonry wall. The pushover curves obtained from the numerical simulations indicate that there is a significant influence on the lateral load response of the wall due to elastic, crushing, and shear parameters while the cracking parameters have less impact on the ductile capacity of the structure. Moreover, the study is also extended to examine the effect of bond patterns such as English, Stretcher, Flemish, and Header bond with varied aspect ratios of 1,1.5 and 0.75. In all four bond patterns, it was observed that the walls with lower aspect ratios exhibited higher strength. Further, in comparison to the other bond patterns, walls with the Flemish bond pattern demonstrated higher strengths at both lower and higher aspect ratios.

Revamp of masonry structures using bio-additive infused air lime mortar as an applicator

Lime masonry walls have been the initial type of masonry wall construction in the construction era. The minimally processed limestone extracted from the lime quarries gives a lesser carbon footprint than any other present-day construction material, making it superior to other construction materials in the construction industry and is the need of the hour. In this study, naturally fermented Bio-Additives, Jaggery and kadukkai were used to make lime mortar for the masonry prisms and walls, and the strength performance was investigated. The bio-additive and the lime powder combination were studied using a pH meter and pH strips to confirm their acidic/basic nature. The lime mortar was experimented with for its flexural strength using a beam specimen. The masonry prism study was initially made with stacked prisms and wall panels (English bond and Flemish bond) for testing compressive strength. The lime mortar thicknesses were varied into two for all the specimens of 10 mm and 15 mm for both the head and bed joints of the masonry. The experimental analysis revealed that a mortar thickness of 10 mm masonry increased the wall’s strength more than mortar of 15 mm thickness in the masonry, disproving the myth that higher mortar thickness in masonry increases the strength of the masonry. The mineralogical characterization of the mortar was carried out by SEM-EDAX to know the internal composition and morphological reactions, FTIR for the changes in the organic composition, and DSC-TGA to know the thermal properties of the mortar matrix. This study justifies the use of bio-additives-infused lime mortar for contemporary masonry projects.

Guidelines on offloading foot ulcers in persons with diabetes (IWGDF 2023 update).

Offloading mechanical tissue stress is arguably the most important of multiple interventions needed to heal diabetes-related foot ulcers. This is the 2023 International Working Group on the Diabetic Foot (IWGDF) evidence-based guideline on offloading interventions to promote healing of foot ulcersin persons with diabetes. It serves as an update of the 2019 IWGDF guideline. We followed the GRADE approach by devising clinicalquestions and important outcomes in the PICO (Patient-Intervention-Control-Outcome) format, undertaking a systematic review and meta-analyses, developing summary of judgement tables and writing recommendations and rationales for each question. Each recommendation is based on the evidence found in the systematic review, expert opinion where evidence was not available, and a careful weighing of GRADE summary of judgement itemsincluding desirable and undesirable effects, certainty of evidence, patient values, resources required, cost effectiveness, equity, feasibility, and acceptability. For healing a neuropathic plantar forefoot or midfoot ulcer in a person with diabetes, use a non-removable knee-high offloading device as the first-choice offloading intervention. If contraindications or patient intolerance to non-removable offloading exist, consider using a removable knee-high or ankle-high offloading device as the second-choice offloading intervention. If no offloading devices are available, consider using appropriately fitting footwear combined with felted foam as the third-choice offloading intervention. If such a non-surgical offloading treatment fails to heal a plantar forefoot ulcer, consider an Achilles tendon lengthening, metatarsal head resection, joint arthroplasty, or metatarsal osteotomy. For healing a neuropathic plantar or apex lesser digit ulcer secondary to flexibile toe deformity, use digital flexor tendon tenotomy. For healing rearfoot, non-plantar or ulcers complicated with infection or ischaemia, further recommendations have been outlined. All recommendations have been summarised in an offloading clinical pathway to help facilitate the implementation of this guideline into clinical practice. These offloading guideline recommendations should help healthcare professionals provide the best care and outcomes for persons with diabetes-related foot ulcers and reduce the person's risk of infection, hospitalisation and amputation.

Erratum to “Development of an elastic storage-release prosthetic foot that mimics the metatarsal bone head and midtarsal joint”

Acknowledgment was not stated in the original article.

Development of an elastic storage-release prosthetic foot that mimics the metatarsal bone head and midtarsal joint

Development of an elastic storage-release prosthetic foot that mimics the metatarsal bone head and midtarsal joint

Seismic performance of stone supported traditional timber frames with or without cap beams

Traditional timber frames in East Asia rest on stone bases, and are uncapped or capped with flat timber beams on their top. This study quantified the influence of the cap beam on the seismic performance of stone supported traditional timber frames. Four column foot and head joints were half-scale fabricated and reversed cyclically tested. Typical damage modes of the joints were identified. Methods were proposed to characterize the joints' rotational behavior. Finite element models of stone supported traditional timber frames with or without cap beams were developed. Lateral performance analysis was conducted on typical full-scale frames based on the developed models; fragility analysis was further performed to evaluate the full-scale frames' seismic performance. The tests indicated that the column foot joints were self-centering and had minor residual parallel to grain deformation. However, the column head joints were found with the embedment deformation at the cap beams, resulting to the pinching of their moment-rotation hysteretic curves. By use of existing hysteretic models in OpenSess whose parameters expressed by the theoretical maximum moment and elastic rotational stiffness, the joints’ rotational behavior was well captured. The numerical study indicated that the cap beam significantly increased the lateral performance and deformability of a frame. The elastic stiffness, lateral load-resisting capacity and cumulative energy dissipation of the frame increased by 77%, 81% and 42%, respectively. Fragility analysis indicated that the cap beam increased more than 33% and 23% of the PGAs corresponding to 50% probability exceedance under life safety drift limit and collapse prevention drift limit, respectively.

Experimental characterisation of flexural bond behaviour in brick masonry

The brick-to-mortar bond often represents the weakest link leading to cracking and failure of masonry structures. For this reason, the in-situ characterization of masonry’s flexural bond behaviour (here defined as flexural bond strength and flexural bond fracture energy), is essential for the assessment of existing buildings. Among masonry bond properties, the flexural bond strength is commonly determined on-site, given the minimal invasiveness of the so-called bond wrench test. However, often the reliability of the results is questioned inputting their large variability to the operator. The present study discharges this assumption by comparing the accuracy of various testing set-ups (manually-operated vs computer-controlled set-ups). Additionally, the influence of the specimen’s type (with/without head joints and couplets vs wallet) on the flexural bond strength assessment is studied providing preliminary correlation factors that can be of help for the in-situ measurement on single-wythe masonry. In addition, to obtain a complete description of the bond behaviour, a new test set-up able to determine the post-peak response is presented. Considerations regarding the dissipated bond fracture energy and its relation to the tensile fracture energy are provided with the support of literature data.

Transient dynamic response of brick masonry walls under low velocity repeated impact load

An experimental and numerical investigation have been carried out on the clay brick masonry walls against repeated impact load in order to estimate the transient dynamic response. The experiments were carried out on 110 mm thick masonry walls against 60 kg mass impactor with hemisphere nose shape with the velocity of 1.98 m/s. In the first phase, the experiment on the wall of 1.2 × 1.2 m (height (h) x breadth (b)) was conducted considering the bed (W1) and head (W2) joint of walls parallel to the boundary in order to verify the conservative design of the joint interface. It was observed that the W2 found resistance up to 3 hits whereas W1 offered resistance up to 11 hits and it was concluded that the W2 found to be sensitive. In the second phase, the aspect ratio of sensitive wall W2 was varied by reducing the breadth from 1.2 to 0.25 m, corresponding aspect ratio (h/b), 1.33 – 4.8 (W3-W6) whereas, the height of the wall remains constant, i.e. 1.2 m. It was observed that the aspect ratio was found to have marginal effect on the peak force however it changes the failure pattern significantly. In the third phase, the influence of mortar strength has been studied and it was observed that the mortar strength does not impart any stiffness into the wall. As a fourth phase, the response of W2, W3 and W4 walls was studied under repeated loading and the resistance offered up to 2, 3 and 2 hits by W2, W3 and W4 walls, respectively. Further, numerical simulations on W1, W2, W3 and W4 walls were carried out using ABAQUS and the Drucker Prager model and traction separation law were used to simulate the brick and interface joints, respectively. The results thus predicted were compared with the experimental results and found in good agreement however, a maximum deviation of 14% on the prediction of peak force. Further, the sensitive parameters were identified which are sensitive to the qualitative numerical results. It was concluded that the parameters such as cohesion, fracture energy, friction and penalty stiffness found to affect the numerical results significantly. Further, wall W2 with externally bonded engineered cementitious composite (ECC) layers has been studied in order to estimate the resistance of wall with backing plate. It was concluded that the ECC backing plate was found to enhance the response of masonry wall in terms of contact force, damage and failure pattern, significantly.

The development of sand erosion induced by shield-tunnel joint leakage

Sand erosion induced by shield-tunnel joint leakage is one of the most frequent catastrophes, causing ground collapses and tunnel failures. In this paper, a self-designed test device that considers differences in water head, burial depth and leaky joint characteristics was used to investigate sand erosion and void development. The experimental results show that the development of sand erosion has obvious temporal and spatial evolution characteristics. In the temporal dimension, sand erosion development can be divided into four stages: vertical erosion, cavity formation, coarse-particle skeleton distribution (CPSR) and steady seepage. In the spatial dimension, it can be divided into three regions: the stable zone, slip surface and eroded zone shape. It is found that the erosion zone can be described by a rotating ellipsoid and the scope of the erosion zone increases with increasing water head, whereas the influence of the burial depth is not significant. The influence of the invert leakage on the volume flow rate is also determined to be larger than that of the vault leakage and the volume flow rate rapidly increases when the size of the leaky joint exceeds the critical outlet size. Finally, a theoretical model based on the test results is proposed to predict the volumetric flow rate of sand erosion.

Результаты экспериментального лечения кроликов с асептическим некрозом головки бедренной кости

The aim of the study was to cause aseptic necrosis of the femoral head in rabbits in an experiment by administering drugs that worsen blood supply in the femoral head and hip joint. The drugs were administered to rabbits distributed in two groups. X-ray, biochemical and morphological studies were carried out. Then a surgical operation was performed aimed at removing part of the femoral head by resection arthroplasty at different times before the restoration of limb functions.

Comparing Ultra-hypofractionated Proton versus Photon Therapy in Extremity Soft Tissue Sarcoma.

Recent single institution, phase II evidence has demonstrated the feasibility and efficacy of ultra-hypofractionated, preoperative photon therapy in 5 fractions for the treatment of soft tissue sarcoma (STS). Our purpose was to evaluate the dosimetric benefits of modern scanning beam proton therapy compared with conventional photon radiation therapy (RT) for the neoadjuvant treatment of adult extremity STS. Existing proton and photon plans for 11 adult patients with STS of the lower extremities previously treated preoperatively with neoadjuvant RT at our center were used to create proton therapy plans using Raystation Treatment Planning System v10.A. Volumes were delineated, and doses reported consistent with International Commission on Radiation Units and Measurements reports 50, 62, and 78. Target volumes were optimized such that 100% clinical target volume (CTV) was covered by 99% of the prescription dose. The prescribed dose was 30 Gy for PT and RT delivered in 5 fractions. For proton therapy, doses are reported in GyRBE = 1.1 Gy. The constraints for adjacent organs at risk (OARs) within 1 cm of the CTV were the following: femur V30Gy ≤ 50%, joint V30Gy < 50%, femoral head V30Gy ≤ 5 cm3, strip V12 ≤ 10%, and skin V12 < 50%. Target coverage goals, OAR constraints, and integral dose were compared by Student t test with P < .05 significance. A minimum 99% CTV coverage was achieved for all plans. OAR dose constraints were achieved for all proton and photon plans; however, mean doses to the femur (10.7 ± 8.5 vs 16.1 ± 7.7 GyRBE), femoral head (2.0 ± 4.4 vs 3.6 ± 6.4 GyRBE), and proximal joint (1.8 ± 2.4 vs 3.5 ± 4.4 GyRBE) were all significantly lower with PT vs intensity-modulated radiation therapy (IMRT) (all P < .05). Integral dose was significantly reduced for proton vs photon plans. Conformity and heterogeneity indices were significantly better for proton therapy. Proton therapy maintained target coverage while significantly reducing integral and mean doses to the proximal organs at risk compared with RT. Further prospective investigation is warranted to validate these findings and potential benefit in the management of adult STS.

Assessment of The Effects of Edentulousness on Temporomandibular Components by Using Cone Beam Computed Tomography

Objective: The aim of this study is to evaluate the effects of edentulousness on the temporomandibular joint using cone beam computed tomography (CBCT). Methods: In this study, CBCT images were evaluated in a total of 48 patients (24 dentulous, 24 edentulous). Ninety-six temporomandibular joint CBCT images were examined. Eminence inclination, condyle head widths and joint space were measured and statistically compared between the edentulous and dentulous groups. Results: The articular eminence inclination value the mediolateral width of the condyle and the anteroposterior width of the condyle were found significantly higher in the dentulous group than in the edentulous group. There was no significant difference between the dentulous and edentulous groups in terms of the anterior, superior and posterior joint space. Conclusion: In the edentulous patients, the articular eminence inclination value, mediolateral and anteroposterior widths of the condyle head were found to lower in comparison to the dentulous patients

Experimental Analysis of Surface Application of Fiber-Reinforced Polymer Composite on Shear Behavior of Masonry Walls Made of Autoclaved Concrete Blocks

This paper presents the results of an experimental study of the shear behavior of masonry walls made of aero autoclaved concrete (AAC) blocks strengthened by externally bonded fiber-reinforced polymer (FRP) composites. Fifteen small wall specimens were constructed and tested in a diagonal compression scheme. Two types of composite materials—carbon- and glass-reinforced polymers—were arranged in two configurations of vertical strips, adopted to the location of the unfilled head joints. The effect of the strengthening location and strengthening materials on changes in the strength and deformability parameters are discussed and the failure process of unstrengthened walls is also presented. The placement of the composite on unfilled head joints proved to be a better solution. Carbon-fiber-reinforced polymer (CFRP) strips provided a threefold increase in stiffness, a 48% increase in load-bearing capacity and a high level of ductility in the post-cracking phase. Glass-fiber-reinforced polymer (GFRP) strips offered a 56% increase in load-bearing capacity but did not change the stiffness of the masonry and provided relatively little ductility. Placing the composite between unfilled joints was only reasonable for CFRP composites, providing a 35% increase in load-bearing capacity but with negligible ductility of the masonry.

Multiplexed tape-stabilized cryohistology of mineralized large animal specimens.

Tape-stabilized cryohistology is a powerful histological method to reinforce tissue samples during and after sectioning, enhancing the overall image quality. This technique has widely been applied to section mineralized small animal (i.e., mice, rat, rabbit) specimens, but has only been sparsely implemented for large animal samples that have a greater tendency to tear due to their increased surface area. Here, we present an optimized protocol for tape-stabilized cryohistology of undecalcified minipig vertebral body, femoral head, and temporomandibular joint samples. This protocol further develops a pipeline for sequential staining and imaging of the tape-stabilized cryosections. Images from multiple rounds of staining (endogenous bone mineral labels, aligned collagen (polarized light), tartrate resistant phosphatase (TRAP), alkaline phosphatase (AP), and toluidine blue) are overlaid to provide insight into dynamic bone remodeling. Overall, the established multiplexed tape-stabilized cryohistology protocol provides step-by-step instructions and guidance to cryosection large, mineralized tissues, and maximize data output from a single histological section.

Advantages of CT Versus MRI for Preoperative Assessment of Osteochondritis Dissecans of the Capitellum

Background: Magnetic resonance imaging (MRI) is considered to be the gold standard for imaging of osteochondritis dissecans (OCD). Purpose/Hypothesis: The purpose was to determine the additional value of a preoperative computed tomography (CT) scan in adolescent patients with capitellar OCD of the elbow. Consistent with the fact that OCD is a lesion involving the subchondral bone, the hypothesis was that CT would be superior to MRI for imaging OCD of the capitellum. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: All patients being treated surgically for an OCD of the capitellum between 2006 and 2016 at one institution were reviewed for preoperative imaging. A total of 28 patients met the inclusion criteria. Corresponding MRI and CT scans were compared retrospectively. Multiple parameters were recorded, with special emphasis on OCD lesion size, fragmentation, and tilt as well as joint surface integrity, loose bodies, and osteophytes. Results: The OCD lesions were best seen on CT scans, whereas MRI T1-weighted images overestimated and T2-weighted images underestimated the size of defects. A subchondral fracture nonunion was found on CT scans in 18 patients, whereas this was seen on MRI T1-weighted images in only 2 patients (P < .001) and MRI T2-weighted images in 4 patients (P < .001). Fragmentation of the OCD fragment was found on CT scans in 17 patients but on MRI scans in only 9 patients (P = .05). Osteophytes as a sign of secondary degenerative changes were seen on CT scans in 24 patients and were seen on MRI scans in 15 patients (P = .02). Altogether, only 51 of 89 secondary changes including loose bodies, effects on the radial head and ulnohumeral joint, and osteophytes that were seen on CT scans were also seen on MRI scans (P = .002). Conclusion: OCD fragmentation and secondary changes were more often diagnosed on CT. These factors indicate OCD instability or advanced OCD stages, which are indications for surgery. In an adolescent who is considered at risk for OCD (baseball, gymnastics, weightlifting, tennis) and who has lateral elbow joint pain with axial or valgus load bearing, CT is our imaging modality of choice for diagnosing and staging OCD of the capitellum.

Screw placement in arthroscopically assisted osteosynthesis of radial head fractures using a reference k-wire in the radiocapitellar joint: a cadaveric study

PurposeThe optimal screw placement in arthroscopically assisted fixation of radial head fractures is still an issue and no guiding methods have been evaluated in the recent literature. The study hypothesis was that using a “reference k-wire” percutaneously inserted in and parallel to the radiocapitellar joint would enable to achieve a trajectory more parallel to the radial head articular surface as compared to a free-hand k-wire placement.MethodsArthroscopically assisted placement of a k-wire in the radial head was performed in seven fresh-frozen human cadaver specimens by three surgeons. Three different techniques were evaluated: freehand drilling (technique A), placement using a “reference” k-wire in the radiocapitellar joint as a reference without (technique B), and with the AO parallel k-wire guide (technique C). Radiographs from all procedures were obtained and the inclination angle “α” between the k-wire and the articular surface of the radial head was measured and compared among the techniques.ResultsAngles of 84 radiographs were obtained and showed a mean α angle of 30.1° ± 13° for technique A, 5.7° ± 4.5° for technique B, and 5.4° ± 3.7° for technique C. The angle α was significantly higher with technique A as compared to B (p < 0.0001) and C (p < 0.0001). There was no difference between methods B and C (n.s.). No difference was observed among the surgeons for all three methods (p = 0.66).ConclusionWith the use of an additional “reference” k-wire placed in the radiocapitellar joint, the guiding k-wire for screw drilling can be placed almost parallel to the radial head joint line with limited variability and a good reproducibility during arthroscopically assisted radial head fracture fixation.Clinical relevanceThe here-presented method of an additional, percutaneous introduced “reference” k-wire is easily applicable and helpful to achieve parallel screw placement during arthroscopically assisted radial head fracture fixation.Level of evidenceIV, biomechanical cadaver study

Combined YOLOv5 and HRNet for High Accuracy 2D Keypoint and Human Pose Estimation

Abstract Two-dimensional human pose estimation has been widely applied in real-world applications such as sports analysis, medical fall detection, human-robot interaction, with many positive results obtained utilizing Convolutional Neural Networks (CNNs). Li et al. at CVPR 2020 proposed a study in which they achieved high accuracy in estimating 2D keypoints estimation/2D human pose estimation. However, the study performed estimation only on the cropped human image data. In this research, we propose a method for automatically detecting and estimating human poses in photos using a combination of YOLOv5 + CC (Contextual Constraints) and HRNet. Our approach inherits the speed of the YOLOv5 for detecting humans and the efficiency of the HRNet for estimating 2D keypoints/2D human pose on the images. We also performed human marking on the images by bounding boxes of the Human 3.6M dataset (Protocol #1) for human detection evaluation. Our approach obtained high detection results in the image and the processing time is 55 FPS on the Human 3.6M dataset (Protocol #1). The mean error distance is 5.14 pixels on the full size of the image (1000 × 1002). In particular, the average results of 2D human pose estimation/2D keypoints estimation are 94.8% of PCK and 99.2% of PDJ@0.4 (head joint). The results are available.

Modeling of dilatancy effect in layered rock with rough interfaces using micropolar continuum

Rock formation such as shale normally has a layered structure where the rock blocks interact with each other by their interfaces like head joints and bed joints. In practical geological conditions, such interfaces are often rough and able to result in dilatancy and volume change of the overall geological structure. The dilatancy can be an important effect and cannot be neglected in determining the practical mechanical behavior of the layered rock. The purpose of this paper is to study the dilatancy effect on the mechanical behavior of layered rock structures with rough interfaces. Interfaces with various roughness are defined to evaluate the dilatancy effect. To estimate the stiffness properties of rough surfaces, a dilatancy model known as the contact density model is used. The current problem involves the size effect of the interface which must not be neglected, thus, a homogenized micropolar continuum is taken into consideration. According to the principle of energy equivalence, a homogenization method is used to get the constitutive parameters of the micropolar model. The present problem is analyzed by using finite element numerical codes to show the validity of the dilatancy models in combination with micropolar theory for a layered rock structure.