Background Clinical assessment of low back pain provides limited information on posture and movement behaviour during daily life. Wearable sensors can quantify free-living lumbar kinematics. This case series explored whether real-world lumbar posture differed between a day recorded before and two weeks after a personalised physiotherapy session, and what behaviour preceded naturally occurring pain on each day. Methods Five individuals with chronic, movement-evoked back pain were recruited. Lumbar posture was recorded with wearable sensors during a full day before and two weeks after a physiotherapy assessment and individualised postural advice, delivered by a physiotherapist blinded to sensor data, with pain events recorded in a diary. Within each participant, posture distributions were compared between days using the Wasserstein distance with block permutation tests, and time towards end-range flexion in the 5–15 min before pain was compared with random pain-free periods from the same day. Findings Whole-day posture differed between days in three participants, alongside marked differences in activity. Time towards end-range flexion changed in the direction of the postural advice in four of five participants. Pain was preceded by more time towards end-range flexion in three participants, matching the clinical assessment in two. Pain events fell in four participants, and all five reported reduced disability. Interpretation In this small case series, wearable sensors captured individual differences in real-world postural behaviour and in the behaviour preceding pain, which did not always match the clinical assessment. Without repeated baseline measurements, differences cannot be attributed to the intervention, and the findings are hypothesis-generating.
Background Pediatric posterior cruciate ligament (PCL) biomechanics remain poorly characterized, and validated computational models are limited. The purpose of this study was to evaluate whether pediatric knee finite element models could reproduce intact cadaveric posterior tibial translation under PCL-dominant loading. Methods Twenty-two pediatric knee models were generated from computed tomography scans using a previously established juvenile modeling workflow. Model predictions were benchmarked against published intact cadaveric data for two loading conditions: a 134 N posterior tibial load at 30° flexion and a coupled 100 N posterior tibial load with 5 Nm external rotation at 0° of flexion. Posterior tibial translation was compared using Welch's two-sample t-tests and confidence intervals. Findings Under isolated posterior loading at 30°, the models predicted 9.4 ± 1.4 mm of posterior tibial translation compared with 10.8 ± 3.7 mm in the cadaveric benchmark (p = 0.15). No significant difference was found under the coupled posterior loading with external rotation between the models predicted posterior translations of 6.9 ± 0.6 mm and the experimental translation at 6.5 ± 3.1 (p = 0.56). Interpretation These findings support the use of specimen-specific pediatric knee models as an externally benchmarked platform for studying PCL biomechanics. Accurate reproduction of cadaveric posterior laxity under clinically relevant loading provides a foundation for future analyses of pediatric injury mechanisms and surgical and rehabilitation strategies.
Background Rotator cuff syndrome (RCS) is a common cause of shoulder pain and functional limitation. This study compared muscle mechanical properties between affected and unaffected sides and with healthy controls, and examined their relationships with pain, disability, and kinesiophobia. Methods Thirty-four patients with RCS and 31 age- and sex-matched healthy adults were included. Dynamic stiffness, oscillation frequency, and logarithmic decrement of the upper trapezius, sternocleidomastoid (SCM), biceps brachii, triceps brachii, and deltoid were measured bilaterally using the MyotonPRO. Pain, shoulder disability, and kinesiophobia were assessed using the Visual Analog Scale (VAS), Shoulder Pain and Disability Index (SPADI), and Tampa Scale for Kinesiophobia (TSK). Non-parametric tests and Spearman correlations were used, with Holm correction. Findings Mechanical properties did not differ between patients and controls (p > 0.05). In patients, biceps brachii dynamic stiffness was higher on the affected side (difference 9.0 N/m, 95% CI 2.9 to 16.7; p = 0.007), but not after Holm correction (p = 0.102); triceps brachii showed no side difference (p = 0.99). SCM oscillation frequency correlated with activity VAS (ρ = 0.41, p = 0.016) and SPADI (ρ = 0.42, p = 0.018); these exploratory correlations did not survive correction for 75 tests. Interpretation Muscle mechanical properties were largely similar between patients with RCS and controls, and the small biceps brachii side difference did not survive correction for multiple testing. Associations with pain and disability were modest and exploratory, so a role for compensatory or psychosocial mechanisms cannot be inferred from these data.
