Gender differences in passive knee biomechanical properties in tibial rotation

The anterior cruciate ligament (ACL) is the most commonly injured knee ligament with the highest incidence of injury in female athletes who participate in pivoting sports. Noncontact ACL injuries commonly occur with both internal and external tibial rotation. ACL impingement against the lateral wall of the intercondylar notch during tibial external rotation and abduction has been proposed as an injury mechanism, but few studies have evaluated in vivo gender‐specific differences in laxity and stiffness in external and internal tibial rotations. The purpose of this study was to evaluate these differences. The knees of 10 male and 10 female healthy subjects were rotated between internal and external tibial rotation with the knee at 60° of flexion. Joint laxity, stiffness, and energy loss were compared between male and female subjects. Women had higher laxity (p = 0.01), lower stiffness (p = 0.038), and higher energy loss (p = 0.008) in external tibial rotation than did men. The results suggest that women may be at greater risk of ACL injury resulting from impingement against the lateral wall of the intercondylar notch, which has been shown to be associated with external tibial rotation and abduction. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:937–944, 2008     

Standardization of hemipelvis alignment for in vitro biomechanical testing

Although in vitro biomechanical tests are regularly performed, the definition of a suitable reference frame for hemipelvic specimens is still a challenge. The aims of the present study were to: (i) define a reference frame for the human hemipelvis suitable for in vitro applications, based on robust anatomical landmarks; (ii) identify the alignment of a hemipelvis based on the alignment of a whole pelvis (including right/left and male/female differences); (iii) identify the relative alignment of the proposed in vitro reference frame with respect to a reference frame commonly used in gait analysis; (iv) create an in vitro alignment procedure easy, robust and inexpensive; (v) quantify the intra‐operator repeatability and inter‐operator reproducibility of the procedure. A procedure to univocally identify the anatomical landmarks was created, exploiting the in vitro accessibility of the specimen's surface. Through the analysis on 53 CT scans (106 hemipelvises), the alignment of the hemipelvis based on the alignment of a whole pelvis was analyzed: differences between male/female and right/left hemipelvises were not statistically significant To overcome the uncertainty in the identification of the acetabular rim, a standard acetabular plane was defined. An alignment procedure was developed to implement such anatomical reference frame. The intra‐operator repeatability and the inter‐operator reproducibility were quantified with four operators, on male and female hemipelvises. The intra‐operator repeatability was better than 1.5°. The inter‐operator reproducibility was better than 2.0°. Alignment in the transverse plane was the most repeatable. The presented procedure to align hemipelvic specimens is sufficiently robust, standardized, and accessible. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1645–1652, 2018.

     

Comparison of Standard Suture vs Barbed Suture for Closing the Porcine Knee Joint: Evaluation of Biomechanical Integrity and Permeability

Background

This study aimed to compare the biomechanical strength and permeability of barbed vs traditional suture for closure of the porcine knee joint.

Biomechanical Characteristics of Biplane Multiplanar Tension-Side Fixation for Lapidus Fusion

Although plating on the plantar, tension-side of the metatarsocuneiform joint provides an inherent biomechanical advantage for Lapidus arthrodesis, it has not been widely adopted owing to the morbidity associated with plantar application. To overcome these limitations, a modification to 90-90 locked biplanar plating was developed to provide the biomechanical advantages of multiplanar fixation and tension-side fixation, allowing application through a conventional incision. We tested the hypothesis that biplanar plating with tension-side fixation (low-profile straight dorsal plate and anatomic medial-plantar plate) would demonstrate improved mechanical stability compared with a previously tested 90-90 biplanar construct (small straight plate dorsally and medially) under cyclic loading. Both constructs were tested in static load to failure (3 pairs) and cyclic loading (10 pairs) with plantar cantilever bending using surrogate anatomic bone models. With static ultimate failure, the biplanar plate construct with tension-side fixation failed at a significantly greater failure load than did the straight biplanar plate construct (247.3?±?18.4 N versus 210.9?±?10.4 N; p?=?.04). With cyclic failure testing, the biplanar plate construct with tension-side fixation endured a significantly greater number of cycles (206,738?±?49,103 versus 101,780?±?43,273; p?<?.001) and a significantly greater dynamic failure load (207.5?±?24.3 N versus 162.5?±?20.6 N; p?<?.001) compared with the straight biplanar plate construct. These results have demonstrated that under simulated static and cyclic Lapidus arthrodesis loading, biplanar plating with tension-side fixation provides superior strength compared with the straight biplanar construct. Thus, this construct shows promise for clinical application as a practical approach to tension-side fixation and an early return to weightbearing after Lapidus fusion.     

仿生脉冲电磁场对去卵巢骨质疏松大鼠骨生物力学性能的影响

目的观察仿生脉冲电磁场 (BEMF)对去卵巢大鼠腰椎和股骨生物力学性能的影响。方法 6月龄雌性未孕Wistar大鼠 40只随机分为模型组 (A组 ) ,假手术组 (B组 ) ,BEMF治疗组 (C组 ) ,雌激素治疗组 (D组 )。A组、C组、D组行双侧卵巢切除术 ,B组行假手术。术后 8w ,D组肌肉注射苯甲酸雌二醇 ,0 .5mg/kg ,1次 /2w ;C组暴露于BEMF治疗 ,1h/d ,1次 /d。A组、B组作为对照组。治疗 10w后 ,用CHALLENGER双能X线骨密度测定仪活体测定大鼠腰椎、股骨骨密度后处死各组实验动物 ,取出第 3腰椎、右侧股骨用INSTRON 10 11生物力学测试机测定生物力学指标。结果BEMF治疗后 ,大鼠腰椎、股骨的结构力学 (最大位移、最大载荷、最大能量吸收 )和材料力学 (最大应力、最大应变、弹性系数 )均有改善 (P <0 .0 5 )。结论BEMF可改善去卵巢大鼠腰椎和股骨的生物力学性能 ,增强抗骨折能力。     

离体脊柱生物力学测试的加载方法研究进展

离体脊柱标本三维运动载荷-位移特性的描述是脊柱生物力学研究的基础,如何准确地模拟在体脊柱的载荷与运动情况是脊柱生物力学研究的难点。国内外学者从测试理论与测试工具上都进行了大量的研究。目前脊柱三维运动测试按照控制方法主要分为载荷控制、位移控制和混合控制。基于不同的控制方法,测试工具也在不断的发展与完善之中。总结目前国内外研制的脊柱离体加载装置的工作原理,并分析其主要优缺点,为离体脊柱生物力学加载装置研究提供参考。     

Zinc supplementation can protect from enhanced risk of femoral neck fracture in male rats chronically exposed to cadmium

The aim of this study was to evaluate whether zinc (Zn) supplementation can protect from an enhanced risk of femoral neck fracture due to chronic exposure to cadmium (Cd). For this purpose, biomechanical properties of the neck and bone mineral density (BMD) at the proximal femur of rats receiving Cd (5 or 50 mg/l) or/and Zn (30 or 60 mg/l) in drinking water for 6 and 12 months were evaluated. The exposure to 5 and 50 mg Cd/l decreased the proximal femur BMD and affected biomechanical properties of the femoral neck. In the rats treated with 5 mg Cd/l, weakening of the femoral neck strength was observed after 12 months, whereas at higher exposure - already after 6 months. The supplementation with 30 and 60 mg Zn/l, enhancing its daily intake by 68% and 138%, respectively, compared to the standard diet, had beneficial influence on the femoral neck biomechanical properties during the exposure to Cd, but it had no impact on the proximal femur BMD. Zn administration during the 12-month exposure to 5 mg Cd/l totally prevented the weakening of the neck. Zn supplementation during the 6-month treatment with 50 mg Cd/l entirely prevented the Cd-induced decrease in the neck fracture strength; however, at the longer exposure to Cd the protective effect of Zn was only partial. The beneficial Zn influence was independent on its dose. The results allow the conclusion that an increase in the daily intake of Zn during moderate and relatively high exposures to Cd can reduce femoral neck susceptibility to fracture. Based on the findings, it seems that enhanced Zn consumption in subjects chronically exposed to Cd may, at least partly, protect from the enhanced risk of femoral neck fracture.     

Biomechanical evaluation of segmental instability in degenerative lumbar spondylolisthesis

Here we investigated the biomechanical properties of spinal segments in patients with degenerative lumbar spondylolisthesis (DLS) using a novel intraoperative measurement system. The measurement system comprised spinous process holders, a motion generator, a load cell, an optical displacement transducer, and a computer. Cyclic displacement of the holders produced flexion-extension of the segment with all ligamentous structures intact. Stiffness, absorption energy (AE), and neutral zone (NZ) were determined from the load-deformation data. Forty-one patients with DLS (M/F = 15/26, mean age 68.6 years; Group D) were studied. Adjacent segments with normal discs in six patients (M/F = 3/3, mean age 35 years) were included as a control group (Group N). Flexion stiffness was significantly lower in Group D than in Group N. The NZ, however, was significantly greater in Group D than in Group N. Thus, compared to normal segments, spinal segments with DLS had a lower flexion stiffness and a higher NZ. NZs in Group D were, however, widely distributed compared to those in Group N that showed NZ <2 mm/N in all cases, suggesting that the segment with DLS is not always unstable and that the segments with NZ >2 mm/N can be considered as unstable. A patent application for the intraoperative measurement system has been submitted.     

Influence of Drop-Landing Exercises on Bone Geometry and Biomechanical Properties in Prepubertal Girls: A Randomized Controlled Study

We conducted a 28-week school-based exercise trial of single-leg drop-landing exercise with 42 girls (Tanner stage 1, 6–10 years old) randomly assigned to control (C), low-drop (LD), or high-drop (HD) exercise groups. The LD and HD groups performed single-leg drop-landings (three sessions/week and 50 landings/session) from 14 and 28 cm, respectively, using the nondominant leg. Single-leg peak ground-reaction impact forces in a subsample ranged between 2.5 and 4.4 times body weight. Dependent variables were bone geometry and biomechanical properties using magnetic resonance imaging. No differences (P > 0.05) were found among groups at baseline for age, stature, lean tissue mass (DXA - Lunar 3.6-DPX), leisure-time physical activity, average daily calcium intake, or measures of knee extensor or flexor torque. A series of ANOVA and ANCOVA tests showed no within- or between-group differences from baseline to posttraining. Group comparisons assessing magnitude of change in side-to-side differences in geometry (area cm²) and cross-sectional moment of inertia (cm⁴) at proximal, mid, and distal sites revealed negligible effect sizes. Our findings suggest that strictly controlled unimodal, unidirectional single-leg drop-landing exercises involving low to moderate peak ground-reaction impact forces do not influence geometrical or biomechanical measures in the developing prepubertal female skeleton.