Most studies on cutting have focused on the biomechanics of the knee and lower-limb muscle activation characteristics, with less consideration given to the influence of motor experience on control ...strategies at the joint level. This study aimed to investigate the differences in knee stability and inter-joint coordination between high- and low-level athletes when cutting at different angles.
A Vicon motion capture system and a Kistler force table were used to obtain kinematic and ground reaction force data during cutting. Joint dynamic stiffness and vector coding were used to assess knee stability and inter-joint coordination. Uncontrolled manifold analysis was used to clarify whether there was synergy among lower-limb joints to maintain postural stability during cutting.
During the load acceptance phase, skilled subjects had the smallest joint stiffness at 90° compared with novice subjects (P < 0.05). Compared with novice subjects, skilled subjects had smaller knee–hip ellipse areas at 90° and 135° (P < 0.05), but larger knee–ankle ellipse areas at 135° (P < 0.05). The synergy index in load acceptance was significantly higher (P < 0.05) for skilled subjects at 90° and 135°.
Advanced subjects can adjust joint control strategies to adapt to the demands of large-angle cutting on the change of direction. Advanced subjects can reduce knee stability for greater flexibility during cutting compared with novice subjects. By increasing the degree of synergy among the lower-limb joints, advanced athletes can maintain high postural stability.
Reverse shoulder arthroplasty biomechanics can be improved by modifying the placement of prosthesis. Biomechanical studies have quantified the impact of placement modifications on the mobility and ...stability of the reverse shoulder. While these studies have provided detailed insights, direct comparisons between their finding are obfuscated by their use of differing methodologies. The aim of our study was to develop an assessment framework which used musculoskeletal simulations to consistently evaluate the biomechanics of various placement modifications. We conducted musculoskeletal simulations of humeral elevations and rotations using 15 reverse shoulder models. For each model, these simulations were conducted for a reference configuration of the prosthesis, established using surgical guidelines, and 34 modified configurations, which were based on commonplace adaptations to the placement of the glenosphere and humeral tray. The effect of each modified configuration on deltoid elongation, deltoid moment arm (DMA), joint stability, and impingement‐free range of motion (IFROM) was determined relative to the reference configuration. We found that 16 of the 34 modified placements had an overall beneficial impact on reverse shoulder biomechanics. Within this subset, we identified two biomechanical trade‐offs. First, there is an antagonistic relationship between IFROM and both the DMA and joint stability. Second, functional requirements differ between humeral elevations and rotations. Furthermore, we found that posteromedial translation of the humeral tray had the most beneficial impact on joint stability and inferior translation of the glenosphere had the most beneficial impact on IFROM and DMA.
ObjectiveTo investigate the correlation between glenohumeral joint congruence and stability in recurrent shoulder dislocations. MethodsEighty-nine patients (89 sides) with recurrent shoulder ...dislocation admitted between June 2022 and June 2023 and met the selection criteria were included as study subjects. There were 36 males and 53 females with an average age of 44 years (range, 20-79 years). There were 40 cases of left shoulder and 49 cases of right shoulder. The shoulder joints dislocated 2-6 times, with an average of 3 times. The three-dimensional models of the humeral head and scapular glenoid were reconstructed using Mimics 20.0 software based on CT scanning images. The glenoid track (GT), inclusion index, chimerism index, fit index, and Hill-Sachs interval (HSI) were measured, and the degree of on/off track was judged (K value, the difference between HSI and GT). Multiple linear regression was used to analyze the correlation between the degree of on/off track (K value) and inclusion index, chimerism in
Bi-cruciate stabilized (BCS) total knee arthroplasty (TKA) was developed to approximate normal knee kinematics and is expected to improve clinical outcomes. However, the effects of soft tissue ...balance at the medial or lateral compartment on patient-reported outcome measures (PROMs) following BCS TKA are unclear. The purpose of this study was to clarify the relationship between the medial or lateral component gaps and PROMs following BCS TKA. One hundred seventeen knees with varus deformities which underwent BCS TKA were included in this study. They were divided into two groups according to the validated Japanese version of the Knee Injury and Osteoarthritis Outcome Score for each subscale of pain, symptoms, and activities of daily living (ADL) at 1 year postoperatively: group H consisted of patients with ≥90 points and group L consisted of patients with <90 points. Intraoperative medial and lateral joint laxities at 0°, 30°, 60°, 90°, and 120° flexion measured using a tensor device were compared between the two groups in each subscale. In the pain subscale, the medial joint laxities at 30° (
< 0.05) and 60° flexion (
< 0.05) in group H were significantly smaller than those in group L. In the ADL subscale, the medial joint laxity at 60° flexion in group H was significantly smaller than that in group L (
< 0.05). In the symptom subscale, the lateral joint laxity at 60° flexion in group H was significantly smaller than that in group L (
< 0.05). Surgeons should pay attention to the importance of both medial and lateral joint stabilities to achieve better postoperative PROMs following BCS TKA.
ABSTRACT
We measured the passive mechanical properties of intact, living human gracilis muscles (n=11 individuals, 10 male and 1 female, age: 33±12 years, mass: 89±23 kg, height: 177±8 cm). ...Measurements were performed in patients undergoing surgery for free-functioning myocutaneous tissue transfer of the gracilis muscle to restore elbow flexion after brachial plexus injury. Whole-muscle force of the gracilis tendon was measured in four joint configurations (JC1–JC4) with a buckle force transducer placed at the distal tendon. Sarcomere length was also measured by biopsy from the proximal gracilis muscle. After the muscle was removed, a three-dimensional volumetric reconstruction of the muscle was created via photogrammetry. Muscle length from JC1 to JC4 increased by 3.3±1.0, 7.7±1.2, 10.5±1.3 and 13.4±1.2 cm, respectively, corresponding to 15%, 34%, 46% and 59% muscle fiber strain, respectively. Muscle volume and an average optimal fiber length of 23.1±0.7 cm yielded an average muscle physiological cross-sectional area of 6.8±0.7 cm2 which is approximately 3 times that measured previously from cadaveric specimens. Absolute passive tension increased from 0.90±0.21 N in JC1 to 16.50±2.64 N in JC4. As expected, sarcomere length also increased from 3.24±0.08 µm at JC1 to 3.63±0.07 µm at JC4, which are on the descending limb of the human sarcomere length–tension curve. Peak passive muscle stress was 27.8±5.5 kPa in JC4 and muscle modulus ranged from 44.8 MPa in JC1 to 125.7 MPa in JC4. Comparison with other mammalian species indicates that human muscle passive mechanical properties are more similar to rodent muscle than to rabbit muscle. These data provide direct measurements of whole-human muscle passive mechanical properties that can be used in modeling studies and for understanding comparative passive mechanical properties among mammalian muscles.
The triangular fibrocartilaginous complex is made of multiple components, of which the palmar and dorsal radioulnar ligaments play an important role in distal radioulnar joint stability. The ulnar ...wrist ligaments may be injured during forearm and wrist trauma. There are several aspects of triangular fibrocartilaginous complex management that are still open to debate. The aim of the present study was to review the current concepts and discuss emerging trends to better elucidate and treat this important ligament complex.
V.
Highlights • Tibiofemoral contact forces increased from walking, to running, to sidestepping. • Tibiofemoral joint was stabilized primarily by muscle forces. • Sidestepping resulted in equal ...medial-to-lateral contact loading. • External measures were poor correlates of the tibiofemoral contact forces. • Relationships between external measures and contact forces were gait-task specific.
Background: The acetabular labrum provides a sealing function and a degree of hip joint stability. Limited, short-term follow-up studies suggest that labral refixation/preservation leads to superior ...outcomes compared with labral debridement/excision.
Purpose: To compare the results of labral refixation versus focal labral excision/debridement in a cohort of patients who underwent arthroscopic correction of femoroacetabular impingement (FAI).
Study Design: Cohort study; Level of evidence, 3.
Methods: We reported on patients who underwent labral debridement/focal labral excision during a period before the development of labral repair techniques. Patients with labral tears thought to be repairable with our current arthroscopic technique were compared with a cohort of patients who underwent labral refixation. To better match the 2 groups, only patients with labral pincer- or combined-type FAI were included. In the first 44 hips, the labrum was focally excised/debrided (group 1); in the next 50 hips, the labrum was refixed (group 2). Outcomes were measured with the modified Harris Hip Score (HHS), Short Form 12 (SF-12), and a visual analog scale (VAS) for pain preoperatively and postoperatively. Preoperative and postoperative radiographs were obtained to evaluate bony resection.
Results: The mean age was 32 years in group 1 and 28 years in group 2 with a mean follow-up of 42 months (range, 24-72 months). Preoperative mean subjective outcome scores were not significantly different between groups. At a mean 3.5 years’ follow-up, subjective outcomes were significantly improved (P < .01) for both groups compared with preoperative scores. The HHS (P = .001), SF-12 (P = .041), and VAS pain scores (P = .004) were all significantly better for the refixation group compared with the debridement group at the most recent follow-up. At a mean 3.5 years’ follow-up, good to excellent results were noted in 68% of the focal excision/debridement group and 92% of the refixation group (P = .004).
Conclusion: Although other factors may have influenced these results, labral refixation compared with an earlier cohort of focal labral excision/debridement resulted in better HHS, SF-12, and VAS pain outcomes and a greater percentage of good to excellent results at a mean 3.5-year follow-up.
Proprioception is an important element of shoulder dynamic stability. It has been shown to be affected in cases of capsular or labral injuries of the glenohumeral joint. Therefore, this study was ...conducted to investigate bilateral shoulder proprioception by active reproduction of joint position both in patients with post-traumatic recurrent unilateral shoulder instability and in normal healthy volunteers.
We compared 41 patients, comprising 11 female and 30 male patients with an average age of 25.6 years (range, 18-39 years), with post-traumatic unilateral anterior shoulder instability with a control group of 27 healthy volunteers with no history of shoulder problems and with normal shoulder function during examination. All patients were examined using a high-accuracy computer-controlled electronic goniometer (Propriometer). The error of active reproduction of joint position (EARJP) was measured in abduction, flexion, external rotation, and internal rotation in both shoulders.
We observed a significant deficit in the EARJP in the unstable shoulders within the instability group. Surprisingly, similar results were recorded for the contralateral, unaffected shoulders within this group of patients compared with the control group. Joint acuity increased with higher elevation of the arm position.
Unilateral shoulder injuries, resulting in instability, affect proprioception in both shoulders, as demonstrated by an increased EARJP. This is the first report of unilateral shoulder instability coexisting with inferior proprioception in both shoulders.
PDF
