Femoral condyle curvature is correlated with knee walking kinematics in ungulates

Articular surface interactions distinguish dinosaurian locomotor joint poses

Our knowledge of vertebrate functional evolution depends on inferences about joint function in extinct taxa. Without rigorous criteria for evaluating joint articulation, however, such analyses risk misleading reconstructions of vertebrate animal motion. Here we propose an approach for synthesizing raycast-based measurements of 3-D articular overlap, symmetry, and congruence into a quantitative "articulation score" for any non-interpenetrating six-degree-of-freedom joint configuration. We apply our methodology to bicondylar hindlimb joints of two extant dinosaurs (guineafowl, emu) and, through comparison with in vivo kinematics, find that locomotor joint poses consistently have high articulation scores. We then exploit this relationship to constrain reconstruction of a pedal walking stride cycle for the extinct dinosaur Deinonychus antirrhopus, demonstrating the utility of our approach. As joint articulation is investigated in more living animals, the framework we establish here can be expanded to accommodate additional joints and clades, facilitating improved understanding of vertebrate animal motion and its evolution.

Variation in human limb joint articular morphology

OBJECTIVES

Synovial joints in human limbs strike a balance between mobility, stability, and articular fit, yet little is known about how these conflicting demands pattern intraspecific variation in articular shape. In this study, we use geometric morphometrics to establish the apportionment and magnitude of morphological variance of the articular surfaces of the human shoulder, elbow, hip, and knee. We hypothesize that variances will be comparable between articulating surfaces within a joint and will be larger in joints with smaller ranges of motion, given their plurality of functional demands.

MATERIALS AND METHODS

Three-dimensional landmarks were taken on the articular surfaces of the glenohumeral, humeroulnar, acetabulofemoral, and tibiofemoral joints from CT scans of 200 skeletons from the University of Tennessee Donated Skeletal Collection (84 females, 116 males). Root mean-squared distances between articulations calculated from Procrustes shape coordinates were used to determine variance distributions.

RESULTS

We found no difference in variances for each articular surface between the sexes or between left and right articular surfaces. A high range of motion is associated with greater morphological variance; however, this pattern is largely driven by the concave articular surfaces of each joint, which consistently exhibit statistically greater variance than their convex counterparts.

DISCUSSION

The striking pattern of differential variance between articulating morphologies points to potential disparities in development between them. Consistently higher variance in concave surfaces may relate to chondral modeling theory for the formation of joints. Establishing intraspecific morphological variance patterns is a first step in understanding coordinated evolution among articular features.

Covariance in human limb joint articular morphology

OBJECTIVES

Limb synovial joints exhibit complex shapes that must accommodate often-antagonistic demands of function, mobility, and stability. These demands presumably dictate coordination among joint articular shapes, but the structure of morphological covariance within and among joints is unknown. This study analyzes the human shoulder, elbow, hip, and knee to determine how articular covariance is structured in relation to joint structure, accessory cartilage, and function.

MATERIALS AND METHODS

Surface models were created from the CT scans of 200 modern skeletons from the University of Tennessee Donated Skeletal Collection. Three-dimensional landmarks were collected on the shoulder, elbow, hip, and knee joints. Two-block partial least squares were conducted to determine associations between surfaces of conarticular shapes, functionally analogous articulations, and articulations belonging to the same bone.

RESULTS

Except for the components of the shoulder, all conarticular pairs exhibit covariance, though the strength of these relationships appears unrelated to the amount of accessory cartilage in the joint. Only the analogous articulations of the humerus and femur exhibit significant covariance, but it is unlikely that this pattern is due to function alone. Stronger covariance within the lower limb than the upper limb is consistent broader primate patterns of within-limb integration.

DISCUSSION

With the exception of the elbow, complementary joint function does not appear to promote strong covariance between articulations. Analogous humeral and femoral surfaces are also serially homologous, which may result in the articular associations observed between these bones. Broadly, these patterns highlight the indirect relationship between joint congruence and covariance.

Length of metacarpal and metatarsal bones in five Iranian sheep breeds and their associations with ungula measurements

Background

This study aimed to measure the length of metacarpal and metatarsal bones in five Iranian sheep breeds and to correlate the length of the bones with ungula measurements. Thoracic and pelvic limbs of 2-year-old, previously untrimmed, pastured Afshari, Moghani, Kurdi, Makoui, and Lori–Bakhtiari ewes, (n = 20 ewes per breed) were collected after slaughter. The following lengths were recorded in the metacarpal and metatarsal bones: from the margo proximalis lateralis to the lateral (L1) and medial (D1) cartilago physialis; from the margo proximalis lateralis to the margo abaxialis of the lateral (L2) and medial (D2) caput; from the cartilago physialis lateralis to the margo abaxialis of the lateral caput (X1); from the cartilago physialis medialis to the margo distalis of the caput ridge (X2) and from the margo axialis of cartilago physialis to the margo axialis of the lateral caput (X3). Additionally, measurements of the ungula including pars dorsalis length, pars mobilis lateralis and medialis height, pars dorsalis height to the ground and to the solea cornea, thickness of the solea in the pars dorsalis, pars mobilis lateralis and medialis, solea cornea length and angulus dorsalis were recorded in the medial and lateral digits of the thoracic and pelvic limbs. Data on length of the metatarsal and metacarpal bones were analysed using mixed model equations while Pearson correlations were calculated between metacarpal and metatarsal bones and ungula measurements.

Results

Lori- Bakhtiari and Moghani ewes had greater L1, L2, and D1 and D2 while X1, X2 and X3 was greater in Kurdi ewes (P < 0.05). Measurements such as L1, L2, D1 and D2 were greater in the metatarsal than in metacarpal bones (P < 0.05) and the opposite was observed for X1, X2 and X3 (P < 0.05). No asymmetry was observed between the lateral and medial measurements (P > 0.05). Low to moderate correlations were observed between bone and ungula measurements (P < 0.05).

Conclusion

Under the conditions of this study, differences in metacarpal and metatarsal bone measurements were observed between breeds but no asymmetry was observed between lateral and medial bones. Results indicate an association between metacarpal and metatarsal bones ungula measurements. This could provide baseline information for the development and/or improvement of current ungula health protocols in the studied sheep breeds.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03076-5.

Articular Geometry Reconstruction for Knee Joint with a Wearable Compliant Device

Nonlinear articular geometries of biological joints have contributed to highly agile and adaptable human-body motions. However, human–machine interaction could potentially distort natural human motions if the artificial mechanisms overload the articular surfaces and constrain biological joint kinematics. It is desired to better understand the deformable articular geometries of biological joints in vivo during movements for design and control of wearable robotics. An articular geometry reconstruction method is proposed to measure the effective articular profile with a wearable compliant device and illustrated with its application to knee-joint kinematic analysis. Regarding the joint articulation as boundary constraints for the compliant mechanism, the equivalent articular geometry is constructed from the beam deformations driven by knee motions, where the continuous deformations are estimated with strain data from the embedded sensors. Both simulated analysis and experimental validation are presented to justify the proposed method.

Is Microfracture Necessary? Acetabular Chondrolabral Debridement/Abrasion Demonstrates Similar Outcomes and Survival to Microfracture in Hip Arthroscopy: A Multicenter Analysis

BACKGROUND

Hip arthroscopy is becoming more advanced and commonly performed. However, significant controversy exists regarding whether high-grade acetabular cartilage lesions should be treated with debridement/abrasion or microfracture. In addition, patients treated with microfracture are subject to extended protected weightbearing rehabilitation to mitigate risk of subchondral plate fracture and to protect fibrocartilage tissue formation.

PURPOSE

To determine the midterm patient-reported outcomes and failure rate of patients with grade 3 and 4 acetabular labrum articular disruption (ALAD) lesions managed with debridement/abrasion or microfracture.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Primary arthroscopic labral repair cases at 2 centers from November 2008 to April 2016 were reviewed for patients aged <55 years with unipolar ALAD grade 3 and 4 chondrolabral acetabular delamination. Patients undergoing microfracture and debridement/abrasion were compared using the visual analog pain scale (VAS), modified Harris Hip Score (mHHS), and Hip Outcome Score-Sports-Specific Subscale (HOS-SSS) to determine predictors of outcomes and failure.

RESULTS

A total of 113 hips in 110 patients (66 males, 44 females; mean age, 34.5 ± 1.1 years) undergoing debridement/abrasion (n = 82) or microfracture (n = 31) were followed for a mean of 4.9 years (range, 2.0-8.5 years). Lesion size was not statistically different between the debridement/abrasion (1.3 ± 1.0 cm²) and microfracture cohorts (1.4 ± 1.0 cm²) ( P = .47). Patients undergoing debridement/abrasion achieved 3.6-point mean improvements in VAS ( P < .01), 21.2-point improvements in mHHS ( P < .01), and 25.4-point improvements in HOS-SSS ( P < .01), which were not significantly different from those observed in microfracture patients ( P≥ .20). The 5-year rate of survival free of revision surgery was 84.0% in the debridement/abrasion group and 85.6% in the microfracture group ( P = .78). The cartilage treatment technique was found not to be predictive of revision risk during both univariate (hazard ratio [HR], 1.01; P = .98) and multivariate (HR, 0.93; P = .90) analysis accounting for patient age, lesion grade, and acetabular coverage.

CONCLUSION

Patients undergoing debridement/abrasion of high-grade unipolar acetabular cartilage lesions demonstrate similar outcome scores and revision rates compared with those of patients undergoing microfracture. These outcomes support the consideration of preferential debridement/abrasion at the discretion of the treating surgeon to optimize recovery while maintaining established positive outcomes after hip arthroscopy.

Out on a limb: bandicoot limb co-variation suggests complex impacts of development and adaptation on marsupial forelimb evolution

Marsupials display far less forelimb diversity than placentals, possibly because of the laborious forelimb-powered climb to the pouch performed by most marsupial neonates. This is thought to result in stronger morphological integration (i.e., higher co-variance) within the marsupial forelimb skeleton, and lower integration between marsupial fore- and hind limbs, compared to other mammals. Possible mechanisms for this constraint are a fundamental developmental change in marsupial limb patterning, or alternatively more immediate perinatal biomechanical and metabolic requirements. In the latter case, peramelid marsupials (bandicoots), which have neonates that climb very little, should show lower within-limb and higher between-limb integration, compared to other marsupials. We tested this in four peramelid species and the related bilby, using partial correlation analyses of between-landmark linear measurements of limb bones, and Procrustes-based two-block partial least-squares analysis (2B-PLS) of limb bone shapes using the same landmarks. We find extensive between-limb integration in partial correlation analyses of only bone lengths, consistent with a reduction of a short-term biomechanical/allocation constraint in peramelid forelimbs. However, partial correlations of bone proportions and 2B-PLS reveal extensive shape divergence between correlated bone pairs. This result contradicts expectations of developmental constraints or serial homology, instead suggesting a function-driven integration pattern. Comparing visualizations from cross-species principal components analysis and 2B-PLS, we tentatively identify selection for digging and half-bounding as the main driver of bandicoot limb integration patterning. This calls for further assessments of functional versus developmental limb integration in marsupials with a more strenuous neonatal climb to the pouch.