Biomechanical Causes Research Articles

Lower-limb inter-joint coordination during balance recovery after trips

BackgroundTrips are one of the most common external perturbations that can lead to accidental falls. Knowledge about postural control attributes of balance recovery after trips could help reveal the biomechanical causes for trip-induced falls and provide implications for fall prevention interventions. Research questionThe objective of the present study was to examine coordinated lower-limb movements during balance recovery after trips. MethodsOne hundred and twenty-three volunteers participated in an experimental study. They were tripped unexpectedly by a metal pole when walking on a linear walkway at their self-selected speed. Lower-limb inter-joint coordination quantified by continuous relative phase measures, including the mean of the absolute relative phases (MARP) and the deviation phase (DP), was analyzed during the execution of the first recovery step after unexpected trips. ResultsCompared to unsuccessful balance recovery, smaller MARPknee-ankle and DPknee-ankle of successful recovery were observed with distal inter-joint coordination on the swing side. Inter-joint coordination of the stance limb did not significantly differ between successful and unsuccessful recovery conditions. These findings indicate that the control of the swing limb’s distal joints is crucial for regaining balance after trips. SignificanceAn implication derived from this study is that greater in-phase coordination and smaller coordination variability in distal joints of the swing limb could be considered as potential targets for interventions aimed at preventing trip-induced accidental.

Characterization of mechanical stress in the occurrence of cortical opacification in age-related cataracts using three-dimensional finite element model of the human lens and RNA-seq

Cataract is the leading cause of blindness across the world. Age-related cataract (ARC) is the most common type of cataract, but its pathogenesis is not fully understood. Using three-dimensional finite element modeling combining experimental biotechnology, our study demonstrates that external forces during accommodation cause mechanical stress predominantly in lens cortex, basically matching the localization of opacities in cortical ARCs. We identified the cellular senescence and upregulation of PIEZO1 mRNA in HLECs under mechanical stretch. This mechano-induced senescence in HLECs might be mediated by PIEZO1-related pathways, portraying a potential biomechanical cause of cortical ARCs. Our study updates the fundamental insight towards cataractogenesis, paving the way for further exploration of ARCs pathogenesis and nonsurgical treatment.

Strain concentration drives the anatomical distribution of injury in acute and chronic traumatic brain injury.

Brain tissue injury caused by mild traumatic brain injury (mTBI) disproportionately concentrates in the midbrain, cerebellum, mesial temporal lobe, and the interface between cortex and white matter at sulcal depths 1-12. The bio-mechanical principles that explain why physical impacts to different parts of the skull translate to common foci of injury concentrated in specific brain structures are unknown. A general and longstanding idea, which has not to date been directly tested in humans, is that different brain regions are differentially susceptible to strain loading11,13-15. We use Magnetic Resonance Elastography (MRE) in healthy participants to develop whole-brain bio-mechanical vulnerability maps that independently define which regions of the brain exhibit disproportionate strain concentration. We then validate those vulnerability maps in a prospective cohort of mTBI patients, using diffusion MRI data collected at three cross-sectional timepoints after injury: acute, sub-acute, chronic. We show that regions that exhibit high strain, measured with MRE, are also the sites of greatest injury, as measured with diffusion MR in mTBI patients. This was the case in acute, subacute, and chronic subgroups of the mTBI cohort. Follow-on analyses decomposed the biomechanical cause of increased strain by showing it is caused jointly by disproportionately higher levels of energy arriving to 'high-strain' structures, as well as the inability of 'high strain' structures to effectively disperse that energy. These findings establish a causal mechanism that explains the anatomy of injury in mTBI based on in vivo rheological properties of the human brain.

Foot surgery for internal offloading in diabetic foot syndrome (DFS) - therapy and prevention

Offloading for DFS must not mean immobilisation. The independence of those affected must not be significantly restricted by the treatment outside of emergency situations. Surgical options, which must be adapted to the degree of mobility of the affected person, can be helpful here. Entities are subgroups of DFS that are defined by their location. They provide easy access to the biomechanical causes of wounds, the prognosis and the surgical treatment concepts. There are often surgical alternatives to amputations and the fear of complications is not justified, as the main complication is usually the amputation itself. Neuropathy-related postoperative treatment cancellations during ulcer offloading must be safely ruled out.

Biomechanical causes for failure of the Physiomesh/Securestrap system

This study investigates the mechanical behavior of the Physiomesh/Securestrap system, a hernia repair system used for IPOM procedures associated with high failure rates. The study involved conducting mechanical experiments and numerical simulations to investigate the mechanical behavior of the Physiomesh/Securestrap system under pressure load. Uniaxial tension tests were conducted to determine the elasticity modulus of the Physiomesh in various directions and the strength of the mesh-tissue-staple junction. Ex-vivo experiments on porcine abdominal wall models were performed to observe the system's behavior under simulated intra-abdominal pressure load. Numerical simulations using finite element analysis were employed to support the experimental findings. The results reveal nonlinearity, anisotropy, and non-homogeneity in the mechanical properties of the Physiomesh, with stress concentration observed in the polydioxanone (PDO) stripe. The mesh-tissue junction exhibited inadequate fixation strength, leading to staple pull-out or breakage. The ex-vivo models demonstrated failure under higher pressure loads. Numerical simulations supported these findings, revealing the reaction forces exceeding the experimentally determined strength of the mesh-tissue-staple junction. The implications of this study extend beyond the specific case of the Physiomesh/Securestrap system, providing insights into the mechanics of implant-tissue systems. By considering biomechanical factors, researchers and clinicians can make informed decisions to develop improved implants that mimic the mechanics of a healthy abdominal wall. This knowledge can contribute to better surgical outcomes and reduce complications in abdominal hernia repair and to avoid similar failures in future.

Soft Tissue Lengthening for Flexion Dislocation of Patella.

Obligatory dislocation of the patella (also known as habitual dislocation) is a rare subset of patellofemoral instability in which the patella dislocates every time the knee is flexed. The problem arises due to contracture of the quadriceps muscles. Soft tissue lengthening procedures such as quadriceps tendon lengthening are the mainstay of treatment, in contrast to medial patellofemoral reconstruction (MPFL-R) for the more common recurrent lateral patellar dislocation. The current review explores the existing literature surrounding the pathophysiology and treatment strategies for this unique cause of knee instability. Flexion dislocation of the knee often presents in children when they begin to walk. It is also termed obligatory or habitual because the patella dislocates laterally with each flexion and extension cycle of the knee. In contrast to other forms of patellar dislocation, the displacement is painless in obligatory dislocation. Likewise, the underlying biomechanical cause of this issue is related to contracture of tissues lateral to the patella rather than disruption of medial soft tissues as seen in recurrent/traumatic dislocation or subluxation of the patella. A number of procedures have been described for management of obligatory dislocation of the patella, with the general consensus that a combination of procedures including release/lengthening of the proximal lateral soft tissues as a critical component for a successful outcome. Soft tissue release/lengthening has been performed for over 50years to treat obligatory dislocation of the patella. This procedure must be used in combination with other proximal and distal reconstructive with careful intraoperative assessment of knee flexion and patellar tracking for satisfactory outcomes. Further research using standardized outcome measures is needed to identify the optimal step-wise approach in treatment of obligatory patellar dislocation.

Shoulder Pain Biomechanics, Rehabilitation and Prevention in Wheelchair Basketball Players: A Narrative Review

Wheelchair basketball (WB) is an increasingly popular sport that guarantees numerous health benefits for people with disabilities who regularly practice it, such as an improved quality of life and psychophysical well-being. However, WB is a contact and high-stress sport, which exposes players to frequent overloads and injuries, mainly affecting the upper limbs. Therefore, shoulder pain (SP) is the most common musculoskeletal disorder among WB players, forcing them to suspend or abandon this sport activity. This narrative review aims to summarize all the known literature on this topic and to be a starting point for further research. Firstly, it explores the biomechanical causes that lead to SP and the underlying diseases, among which the most recurrent are rotator cuff tendinopathies. Furthermore, this overview deepens the most effective and specific rehabilitation programs for SP in WB players and it emphasizes the need for further studies to trial new rehabilitative protocols using novel technologies to make them faster and more personalized. In this regard, the general recommendation still remains to perform a combination of exercises such as strengthening, endurance and stretching exercises of various durations and intensities. To conclude, the most important prevention strategies are described, underlining the need for constant sport-specific training led by qualified personnel and suggesting some insights on possible new research aimed at improving wheelchair ergonomics, stressing the importance of a multidisciplinary team fully dedicated to the individual athlete.

Lower Extremity Considerations in the Pregnant Patient.

There remains a paucity of literature on musculoskeletal dysfunction, biomechanics, and pathologies of the lower extremity during pregnancy. There are a multitude of physiologic changes that affect a large percentage of patients throughout pregnancy. Podiatric pathologies observed during gestation can be debilitating for this population, ranging from musculoskeletal and biomechanical causes to traumatic injuries and thromboembolic events. This literature review aims to provide an updated review of lower extremity considerations during pregnancy. The authors seek to provide guidance to clinicians based on a review of the available evidence today, and we aim to address deficiencies in research involving the pregnant population.Levels of Evidence: Level V.

Effectiveness of Wearable Protection Equipment for Seated Pedestrians.

This study used finite element models to investigate the efficacy of seated pedestrian protection equipment in vehicle impacts. The selected safety equipment, a lap belt, an airbag vest, and a bicycle helmet, were chosen to mitigate the underlying biomechanical causes of seated pedestrian injuries reported in the literature. The impact conditions were based on the three most dangerous impact scenarios from a previous seated pedestrian impact study. Serious injury (AIS 3+) risks were compared with and without protective equipment. A 50th percentile male occupant model and two generic vehicle models, the family car (FCR) and sports utility vehicle (SUV), were used to simulate vehicle collisions. Three impact conditions were run with every combination of protective equipment (n = 24). The helmet reduced head and brain injury risks from the vehicle-head and ground-head contacts. The airbag reduced the head injury risk in the FCR vehicle-head contact but increased the brain injury risks in the SUV impacts from increased whiplash. The lap belt increased head injury risks for both the FCR and the SUV impacts because it created a stronger FCR vehicle-head contact and SUV ground-head contact. When the belt and airbag were used together the head injury risks dramatically decreased because the pedestrian body impacted the ground arm or leg first and slowly rolled onto the ground which resulted in softer ground-head contacts and in two instances, no ground-head contact. Only the helmet proved effective in all impact conditions. Future testing must be completed before recommending the belt or airbag for seated pedestrians.

Literature review of biomechanics of the ankle/ foot complex: changes in functional activities postoperatively for ankle fractures

The ankle plays an important role in daily life under the functional point of view. It is essential to perform basic movements such as walking, running, etc. The ankle joint complex is a part of the body most frequently injured of the musculoskeletal system. Orthopedic fractures in this joint may be classified as low trauma and high energy, the latter trauma, usually found in traffic accidents and falls from great heights are the most disabling. In the general context often this type of fracture compromises neighboring joints due to misalignment of the loading axis of the involved segment, emerging pain and progressive functional disability. In this context, this study aimed to review the literature of studies that were willing to analyze the biomechanical causes of the functional outcome of fractures of the complex orthopedic foot/ankle trauma generated by high and low energy. For this, a search was made in electronic databases indexing scientific articles, using the keyword search previously created. For better understanding we divided the literature review on topics: classification of ankle fractures, surgical treatment, no surgical indications and contraindications in cases of surgery, types of surgery with open reduction and internal fixation (ORIF), external and hybrid; wounds and complications consequences: amputation, obesity, arthritis and osteoarthritis, early motion, range of motion, gait pathology. From this review study, it is necessary that other publications in the field of physical therapy related biomechanical results of ankle fractures are carried out, since most studies were found in articles reporting on the medical surgeries.

Direction-dependency of the kinematic indices in upper extremities motor assessment of stroke patients.

Kinematic indices (KIs) are frequently used as objective measures to assess the upper extremities motor performance in post stroke patients. The clinimetric analysis of these indices has been mostly limited to their averaged values over different directions of reaching movements. Recent studies indicate direction dependencies of such motor performances due to neural and/or biomechanical causes. The direction dependencies of such indices and their clinimetric parameters remains to be investigated. An apparatus was built to perform and measure planar point-to-point reaching tasks in 8 directions using a virtual reality environment. 24 stroke and 18 healthy individuals participated in the study. 24 kinematic indices were calculated. Reliability (ICC), construct validity (Spearman correlation), and responsiveness (paired t-test pre and post intervention) were analyzed in each direction. The clinimetric parameters were found highly direction dependent. The reliability of the indices were strongest when moving away and towards the body. The validity (Spearman>0.75) and responsiveness (p<0.05) were most pronounced when moving in the NW-SE direction. These findings are in compliance with some previous neuro-musculoskeletal observations. While smoothness parameters are relatively uniform in all directions, speed and accuracy are direction dependent. The clinimetrics of the kinematic indices also depend on the direction and show stronger values in the NW-SE direction which is therefore proposed as the most accurate and responsive direction for kinematic assessment in stroke patients.

Not Simply a Structural Problem: Psychological Determinants of Headache in Patients with Tumors of the Sellar Region.

Headache in patients with tumors of the sellar region (TSR) has previously been attributed entirely to biomechanical causes. This study aimed to investigate the influence of psychological determinants for the occurrence of and disability due to headaches in patients with TSR. This was a cross-sectional single-center study with a logistic regression approach. Eighty-four patients (75%) with pituitary adenomas and 28 with other TSR prior to first-time neurosurgery were investigated. One-hundred and twelve patients received standardized questionnaires on personality, headache characteristics, and disability due to headache. Fifty-nine patients additionally filled in questionnaires about coping with stress and pain catastrophizing. Separate logistic regression models were used to predict the risk of headache occurrence and disability due to headache by personality, stress coping, and pain catastrophizing. Conscientiousness, neuroticism, and pain catastrophizing were significant predictors of headache occurrence. The amount of explained variance for both models predicting headache occurrence was comparable to that in primary headache. Neuroticism, pain catastrophizing, and humor as a coping strategy predicted disability due to headache with a high variance explanation of 20-40%. For the first time, we report data supporting a strong psychological influence on headache and headache-related disability in patients with TSR, which argue against purely mechanistic explanatory models. Physicians treating patients with TSR and headaches should adopt an integrative diagnostic and treatment approach, taking the biopsychosocial model of pain into account.

Dépistage et prévention des affections rhumatologiques en milieu de travail

Musculoskeletal disorders (MSDs) are the leading cause of occupational disease in France and in Europe and are responsible for serious economic and social consequences, at individual, company and country level. MSDs are of multifactorial origin, combining individual susceptibility factors and a range of biomechanical, psychosocial, organizational and managerial causes of the workplace. The prevention of MSDs requires a global and integrated approach, favoring the reduction of risks at source through action in the workplace, screening and early management of patient-workers suffering from these disorders and, if necessary, maintenance employed. Their management is based on an overall assessment of the clinical and socioprofessional situation. The coordination of medical, rehabilitative and professional care is a key element of professional prognosis and job retention.

Effectiveness of Sub – Occipital Release Technique for Non-Specific Neck Pain

The main objective of the study is to find the effectiveness of sub occipital release technique in neck pain reduction, improving range of movement of neck and improving quality of life. Neck pain has a greater prevalence and is increasing globally because of various causes such as faulty posture, biomechanical causes in cervical, thoracic and scapular region. Tightness in the muscle leads to pain and decreased range of movements. This would reduce the performance of the person in day to day life and slowly will become partially dependent, and this has to be rectified in earlier stage itself. Even though, many research has been performed, they were performed only in the older age group, but not in adult age group. Variability in tension produces impact on structure and functions of cervical muscles. When there is an increased tension in cervical group of muscles, it produces imbalance in tone of the cervical muscles, which leads to neck pain and disturbed daily activities. There are various studies which had proved different methods of treatment involving various modalities, medications, exercises for treating nonspecific neck pain, but the effect of sub-occipital release technique is little understood and practiced. Hence an intervention with low time consuming and evidence based technique is needed. Sub occipital release technique helps to reduce tension in the muscles, thereby helping to perform daily activities effectively. This was an experimental study with pre-post test 20 samples selected from 30 volunteers based on the inclusion criteria. Group A is treated with sub-occipital release technique for 4 weeks, 3 days / week 2 sessions / day (Frequency: 3 times in one session). Control group performs isometric exercise for 4 weeks, 3 days / week 2 sessions / day (Frequency: 3 times in one session). At the end of 30 days of treatment session, there was a significant reduction of neck pain and increased range of motion of neck Flexion from 31.9 to 36.6, Extension from39.2 to45.0, side flexion from13.8 to 18.2, rotation from39.7 to 45.5(mean values), the mean values of VAS and NDI of pretest is 1.4 and 4.94; post test value is1.6 and 2.41.The result concluded that Group A who underwent sub-occipital release technique had more effective treatment in reducing pain and improving range of movements and functional abilities for non-specific neck pain.

Hinge fractures reaching the tibial plateau can be caused by forcible opening of insufficient posterior osteotomy during open-wedge high tibial osteotomy.

The purpose of this study was to use the finite element method (FEM) to reproduce fracture lines that reach the lateral tibial plateau during open-wedge high tibial osteotomy (OWHTO) in patients with Type III lateral hinge fracture (LHF). It was hypothesized that the FEM could clarify biomechanical causes of Type III LHF, enabling prevention of adverse complications. This study used the nonlinear FEM to analyze the data of eight knees in eight patients (two males and six females) with Type III LHF among 82 patients who underwent OWHTO, as well as the data of eight individuals with no LHF. To predict the onset of Type III LHF, simulation models were also developed in which posterior osteotomy sufficiency varied from 50% to perfect, the latter defined as osteotomy reaching the hinge point. Real-life instances of Type III LHF caused by insufficient posterior osteotomy were reproduced in all patient-specific FEM models, and these models accurately predicted fracture types and locations. During opening of the osteotomy gap, the fracture line reached the lateral tibial plateau, and extended vertically from the end of the insufficient posterior osteotomy, avoiding the rigid proximal tibiofibular joint. In contrast, sufficient posterior osteotomy resulted in a lack of LHF. Posterior osteotomy extension ≥ 70% of the width of the osteotomy plane was the cut-off value to prevent Type III LHF. Forced opening of insufficient posterior osteotomy was found to be a biomechanical cause of Type III LHF that extended perpendicularly to the lateral tibial plateau, avoiding the proximal tibiofibular joint. The clinical significance of this study is that sufficient posterior osteotomy during OWHTO, defined as at least 70% of the width of the osteotomy plane, can prevent Type III LHF.

A Glymphatic System and New Etiopathogenic Hypothesis on Glaucoma Patients Who Underwent Osteopathic Manipulative Treatment: A Pilot Study

Purpose Malfunction of the lymphatic or glymphatic system recently shown in the brain, seems to play an important role in central neurodegenerative pathologies through a build-up of neurotoxins. Recent studies have shown functional links between aqueous humour and cerebrospinal fluid via the glymphatic system, offering new perspectives and unifying theories on the vascular, biomechanical and biochemical causes of chronic and openangle glaucoma (POAG). The aim of this randomized pilot study is to compare the variations in intraocular pressure between 20 cases of compensated POAG under pharmacological therapy and 20 glaucoma patients undergoing osteopathic treatment, hypothesizing that this manipulation can influence intraocular pressure. Materials and Methods The 40 patients under study, all covered by the Helsinki convention, were randomly divided into 2 groups (treated group or TG and control group or CG). The 40 patients were chosen from compensated glaucoma sufferers, who required neither changes in therapy nor operations which would affect their eye pressure which was measured both before and after manipulative osteopathic treatment scheduled into 4 sessions at intervals of 7.3 and 150 days, then compared with the control group (20 patients) who were undergoing pharmacological treatment only. Results The average IOP in the TG was compared with the CG throughout the entire treatment cycle showing a statistically inconclusive reduction in the right eye RE P-value (0.0561), while for the left eye a significant effect was shown LE (0.0073). The difference between the reduction in IOP between TG and CG was observable 10 months after the first session or rather 5 months after the last, and demonstrable during a check-up 13 months after the beginning of the study, or rather 8 months in absence of treatment with a highly significant statistical p-value (0.000434). Conclusions This study has shown that manipulative osteopathic treatment can affect intraocular pressure after each session and that the pressure is significantly lower even months after the last treatment session.

The Glymphatic System and New Etiopathogenic Hypotheses Concerning Glaucoma Based on Pilot Study on Glaucoma Patients Who Underwent Osteopathic Manipulative Treatment (OMT)

Purpose Malfunction of the lymphatic or glymphatic system recently shown in the brain, seems to play an important role in central neurodegenerative pathologies through a build-up of neurotoxins. Recent studies have shown functional links between aqueous humour and cerebrospinal fluid via the glymphatic system, offering new perspectives and unifying theories on the vascular, biomechanical and biochemical causes of chronic and open angle glaucoma (POAG). The aim of this randomized pilot study is to compare the variations in intraocular pressure between 20 cases of compensated POAG under pharmacological therapy and 20 glaucoma patients undergoing osteopathic treatment, hypothesizing that this manipulation can influence intraocular pressure. Materials and Methods The 40 patients under study, all covered by the Helsinki convention, were randomly divided into 2 groups (treated group or TG and control group or CG). The 40 patients were chosen from compensated glaucoma sufferers, who required neither changes in therapy nor operations which would affect their eye pressure which was measured both before and after manipulative osteopathic treatment scheduled into 4 sessions at intervals of 7.3 and 150 days, then compared with the control group (20 patients) who were undergoing pharmacological treatment only. Results The average IOP in the TG was compared with the CG throughout the entire treatment cycle showing a statistically inconclusive reduction in the right eye RE P-value (0.0561), while for the left eye a significant effect was shown LE (0.0073). The difference between the reduction in IOP between TG and CG was observable 10 months after the first session or rather 5 months after the last, and demonstrable during a check-up 13 months after the beginning of the study, or rather 8 months in absence of treatment with a highly significant statistical p-value (0.000434). Conclusions This study has shown that manipulative osteopathic treatment can affect intraocular pressure after each session and that the pressure is significantly lower even months after the last treatment session.

Walking Biomechanics and Spine Loading in Patients With Symptomatic Lumbar Spinal Stenosis.

Symptomatic lumbar spinal stenosis is a leading cause of pain and mobility limitation in older adults. It is clinically believed that patients with lumbar spinal stenosis adopt a flexed trunk posture or bend forward and alter their gait pattern to improve tolerance for walking. However, a biomechanical assessment of spine posture and motion during walking is broadly lacking in these patients. The purpose of this study was to evaluate lumbar spine and pelvic sagittal angles and lumbar spine compressive loads in standing and walking and to determine the effect of pain and neurogenic claudication symptoms in patients with symptomatic lumbar spinal stenosis. Seven participants with symptomatic lumbar spinal stenosis, aged 44–82, underwent a 3D opto-electronic motion analysis during standing and walking trials in asymptomatic and symptomatic states. Passive reflective marker clusters (four markers each) were attached to participants at T1, L1, and S2 levels of the spine, with additional reflective markers at other spinal levels, as well as the head, pelvis, and extremities. Whole-body motion data was collected during standing and walking trials in asymptomatic and symptomatic states. The results showed that the spine was slightly flexed during walking, but this was not affected by symptoms. Pelvic tilt was not different when symptoms were present, but suggests a possible effect of more forward tilt in both standing (p = 0.052) and walking (p = 0.075). Lumbar spine loading during symptomatic walking was increased by an average of 7% over asymptomatic walking (p = 0.001). Our results did not show increased spine flexion (adopting a trunk-flexed posture) and only indicate a trend for a small forward shift of the pelvis during both symptomatic walking and standing. This suggests that provocation of symptoms in these patients does not markedly affect their normal gait kinematics. The finding of increased spine loading with provocation of symptoms supports our hypothesis that spine loading plays a role in limiting walking function in patients with lumbar spinal stenosis, but additional work is needed to understand the biomechanical cause of this increase.

A cross-sectional analysis of persistent low back pain, using correlations between lumbar stiffness, pressure pain threshold, and heat pain threshold

IntroductionLittle is known about the underlying biomechanical cause of low back pain (LBP). Recently, technological advances have made it possible to quantify biomechanical and neurophysiological measurements, potentially relevant factors in understanding LBP etiology. However, few studies have explored the relation between these factors. This study aims to quantify the correlation between biomechanical and neurophysiological outcomes in non-specific LBP and examine whether these correlations differ when considered regionally vs. segmentally.MethodsThis is a secondary cross-sectional analysis of 132 participants with persistent non-specific LBP. Biomechanical data included spinal stiffness (global stiffness) measured by a rolling indenter. Neurophysiological data included pain sensitivity (pressure pain threshold and heat pain threshold) measured by a pressure algometer and a thermode. Correlations were tested using Pearson’s product-moment correlation or Spearman’s rank correlation as appropriate. The association between these outcomes and the segmental level was tested using ANOVA with post-hoc Tukey corrected comparisons.ResultsA moderate positive correlation was found between spinal stiffness and pressure pain threshold, i.e., high degrees of stiffness were associated with high pressure pain thresholds. The correlation between spinal stiffness and heat pain threshold was poor and not statistically significant. Aside from a statistically significant minor association between the lower and the upper lumbar segments and stiffness, no other segmental relation was shown.ConclusionsThe moderate correlation between spinal stiffness and mechanical pain sensitivity was the opposite of expected, meaning higher degrees of stiffness was associated with higher pressure pain thresholds. No clinically relevant segmental association existed.

A BIOMECHANICAL STUDY OF THE EFFECTS OF FLEXION ANGLE ON THE INDUCTION MECHANISM OF CERVICAL SPONDYLOSIS

Lesions in facet joints such as bone hyperplasia and degenerative changes in the intervertebral discs, can compress nerve roots and the spinal cord, leading to cervical spondylosis (CS). Lesions in these parts of the spine are commonly related to abnormal loads caused by bad posture of the cervical spine. This study aimed to understand the potential mechanical effects of load amplitude on cervical spine motion to provide a theoretical basis for the biomechanical causes of CS, and to provide a reference for preventing of the condition. In this study, a finite element model of the normal human cervical spine (C1-C7) was established and validated using an infrared motion capture system to analyze the effects of flexion angle on the stresses experienced by intervertebral discs, the anterior edge of the vertebral body, the pedicle, uncinate and facet joints. Our analysis indicated that the intervertebral disc load increased by at least 70% during the 20∘ to 45∘ flexion of the neck with 121% load increase in the vertebrae. In the intervertebral discs, the stress was largest at C4-C5, and the stress was moderate at C5-C6. These results are consistent with clinical CS prone site research. According to Wolff’s law, when bones are placed under large stresses, hyperplasia can result to allow adaptation to large loads. Increased cervical spine flexion angles caused the proliferation of bone in the above-mentioned parts of the spine and can accelerate accelerating the appearance of CS.