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1.
Clin Orthop Surg ; 16(4): 570-577, 2024 Aug.
Article in English | MEDLINE | ID: mdl-39092300

ABSTRACT

Background: Increased load bearing across the patellofemoral and tibiofemoral articulations has been associated with total knee arthroplasty (TKA) complications. Therefore, the purpose of this study was to quantify the biomechanical characteristics of the patellofemoral and tibiofemoral joints and simulate varying weight-bearing demands after posterior cruciate ligament-retaining (CR) and posterior-stabilized (PS) TKAs. Methods: Eight fresh-frozen cadaveric knees (average age, 68.4 years; range, 40-86 years) were tested using a custom knee system with muscle-loading capabilities. The TKA knees were tested with a CR and then a PS TKA implant and were loaded at 6 different flexion angles from 15° to 90° with progressively increasing loads. The independent variables were the implant types (CR and PS TKA), progressively increased loading, and knee flexion angle (KFA). The dependent variables were the patellofemoral and tibiofemoral kinematics and contact characteristics. Results: The results showed that at higher KFAs, the position of the femur translated significantly more posterior in CR implants than in PS implants (36.6 ± 5.2 mm and 32.5 ± 5.7 mm, respectively). The patellofemoral contact force and contact area were significantly greater in PS than in CR implants at higher KFAs and loads (102.4 ± 12.5 N and 88.1 ± 10.9 N, respectively). Lastly, the tibiofemoral contact force was significantly greater in the CR than the PS implant at flexion angles of 45°, 60°, 75°, and 90° KFA, the average at these flexion angles for all loads tested being 246.1 ± 42.1 N and 192.8 ± 54.8 N for CR and PS implants, respectively. Conclusions: In this biomechanical study, CR TKAs showed less patellofemoral contact force, but more tibiofemoral contact force than PS TKAs. For higher loads across the joint and at increased flexion angles, there was significantly more posterior femur translation in the CR design with a preserved posterior cruciate ligament and therefore significantly less patellofemoral contact area and force than in the PS design. The different effects of loading on implants are an important consideration for physicians as patients with higher load demands should consider the significantly greater patellofemoral contact force and area of the PS over the CR design.


Subject(s)
Arthroplasty, Replacement, Knee , Posterior Cruciate Ligament , Weight-Bearing , Humans , Aged , Biomechanical Phenomena , Aged, 80 and over , Weight-Bearing/physiology , Middle Aged , Posterior Cruciate Ligament/surgery , Adult , Male , Female , Cadaver , Knee Joint/surgery , Knee Joint/physiology , Knee Prosthesis , Patellofemoral Joint/surgery , Patellofemoral Joint/physiology , Range of Motion, Articular
2.
Physiol Rep ; 12(15): e16168, 2024 Aug.
Article in English | MEDLINE | ID: mdl-39090666

ABSTRACT

It is not clear as to whether weight bearing and ambulation may affect bone growth. Our goal was to study the role of mechanical loading (one of the components of ambulation) on endochondral ossification and longitudinal bone growth. Thus, we applied cyclical, biologically relevant strains for a prolonged time period (4 weeks) to one tibia of juvenile mice, while using the contralateral one as an internal control. By the end of the 4-week loading period, the mean tibial growth of the loaded tibiae was significantly greater than that of the unloaded tibiae. The mean height and the mean area of the loaded tibial growth plates were greater than those of the unloaded tibiae. In addition, in female mice we found a greater expression of PTHrP in the loaded tibial growth plates than in the unloaded ones. Lastly, microCT analysis revealed no difference between loaded and unloaded tibiae with respect to the fraction of bone volume relative to the total volume of the region of interest or the tibial trabecular bone volume. Thus, our findings suggest that intermittent compressive forces applied on tibiae at mild-moderate strain magnitude induce a significant and persistent longitudinal bone growth. PTHrP expressed in the growth plate appears to be one growth factor responsible for stimulating endochondral ossification and bone growth in female mice.


Subject(s)
Growth Plate , Parathyroid Hormone-Related Protein , Tibia , Weight-Bearing , Animals , Female , Parathyroid Hormone-Related Protein/metabolism , Parathyroid Hormone-Related Protein/genetics , Tibia/metabolism , Tibia/growth & development , Tibia/diagnostic imaging , Growth Plate/metabolism , Growth Plate/growth & development , Mice , Weight-Bearing/physiology , Stress, Mechanical , Mice, Inbred C57BL , Bone Development , Osteogenesis/physiology
4.
BMC Musculoskelet Disord ; 25(1): 576, 2024 Jul 24.
Article in English | MEDLINE | ID: mdl-39049016

ABSTRACT

BACKGROUND: Developmental dysplasia of the hip causes secondary osteoarthritis. Finite element analysis suggests high hip joint contact pressure in patients with hip dysplasia and a reduction in contact pressure after periacetabular osteotomy. However, few biomechanical studies have examined the load distribution in the hip joint. This study aimed to investigate the biomechanical properties of load distribution in porcine hip joints at different acetabular coverages. METHODS: Six porcine hip joints were analyzed using three models: 1) neutral coverage, 2) 15° under-coverage (defined as dysplasia model), and 3) 15° over-coverage created by varying the acetabular coverage. The load distribution was assessed using a pressure-mapping sensor system after applying a loading force of 100 N to the hip joint. RESULTS: In the dysplasia model, the load was concentrated at the acetabular rim; in the neutral and over-coverage models, it was dispersed. The average contact pressure was significantly higher in the dysplasia model than in the neutral coverage model ([0.42 vs. 0.3 MPa]; p = 0.004). The contact area was significantly smaller in the dysplasia model than in the neutral coverage model ([250.7 vs. 345.0 mm2]; p = 0.004). No significant differences were observed in contact pressure or area between the neutral and over-coverage models. CONCLUSIONS: Insufficient acetabular coverage in the dysplasia model demonstrated higher contact pressure and smaller contact area than the neutral model. Conversely, the contact pressure and area in the over-coverage model did not differ significantly from those in the normal model. Therefore, surgeons should note that acetabular coverage overcorrection has limited effect; normalization is crucial during periacetabular osteotomy.


Subject(s)
Acetabulum , Hip Joint , Weight-Bearing , Animals , Acetabulum/surgery , Acetabulum/physiopathology , Biomechanical Phenomena/physiology , Weight-Bearing/physiology , Swine , Hip Joint/surgery , Hip Joint/physiopathology , Finite Element Analysis , Developmental Dysplasia of the Hip/surgery , Developmental Dysplasia of the Hip/physiopathology , Pressure
5.
J Orthop Trauma ; 38(8S): S12-S13, 2024 Aug 01.
Article in English | MEDLINE | ID: mdl-39007634

ABSTRACT

VIDEO AVAILABLE AT: https://ota.org/education/ota-online-resources/video-library-procedures-techniques/lateral-tibial-plateau.


Subject(s)
Ilium , Tibial Fractures , Weight-Bearing , Humans , Ilium/transplantation , Ilium/surgery , Tibial Fractures/surgery , Autografts , Transplantation, Autologous/methods , Bone Transplantation/methods , Plastic Surgery Procedures/methods , Male , Tibia/surgery
6.
PLoS One ; 19(7): e0304606, 2024.
Article in English | MEDLINE | ID: mdl-38990910

ABSTRACT

OBJECTIVE: To compare whole-body kinematics, leg muscle activity, and discomfort while performing a 10-min carrying task with and without a passive upper-body exoskeleton (CarrySuitⓇ), for both males and females. BACKGROUND: Diverse commercial passive exoskeletons have appeared on the market claiming to assist lifting or carrying task. However, evidence of their impact on kinematics, muscle activity, and discomfort while performing these tasks are necessary to determine their benefits and/or limitations. METHOD: Sixteen females and fourteen males carried a 15kg load with and without a passive exoskeleton during 10-min over a round trip route, in two non-consecutive days. Whole-body kinematics and leg muscle activity were evaluated for each condition. In addition, leg discomfort ratings were quantified before and immediately after the task. RESULTS: The gastrocnemius and vastus lateralis muscle activity remained constant over the task with the exoskeleton. Without the exoskeleton a small decrease of gastrocnemius median activation was observed regardless of sex, and a small increase in static vastus lateralis activation was observed only for females. Several differences in sagittal, frontal, and transverse movements' ranges of motion were found between conditions and over the task. With the exoskeleton, ROM in the sagittal plane increased over time for the right ankle and pelvis for both sexes, and knees for males only. Thorax ROMs in the three planes were higher for females only when using the exoskeleton. Leg discomfort was lower with the exoskeleton than without. CONCLUSION: The results revealed a positive impact on range of motion, leg muscle activity, and discomfort of the tested exoskeleton.


Subject(s)
Exoskeleton Device , Leg , Muscle, Skeletal , Humans , Male , Female , Biomechanical Phenomena , Adult , Muscle, Skeletal/physiology , Leg/physiology , Young Adult , Range of Motion, Articular/physiology , Electromyography , Weight-Bearing/physiology
7.
BMC Musculoskelet Disord ; 25(1): 533, 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-38992608

ABSTRACT

BACKGROUND: The purpose of this study was to perform a biomechanical analysis to compare different medial column fixation patterns for valgus pilon fractures in a case-based model. METHODS: Based on the fracture mapping, 48 valgus pilon fracture models were produced and assigned into four groups with different medial column fixation patterns: no fixation (NF), K-wires (KW), intramedullary screws (IS), and locking compression plate (LCP). Each group contained wedge-in and wedge-out subgroups. After fixing each specimen on the machine, gradually increased axial compressive loads were applied with a load speed of one millimeter per minute. The maximum peak force was set at 1500 N. Load-displacement curves were generated and the axial stiffness was calculated. Five different loads of 200 N, 400 N, 600 N, 800 N, 1000 N were selected for analysis. The specimen failure was defined as resultant loading displacement over 3 mm. RESULTS: For the wedge-out models, Group-IS showed less displacement (p < 0.001), higher axial stiffness (p < 0.01), and higher load to failure (p < 0.001) than Group-NF. Group-KW showed comparable displacement under loads of 200 N, 400 N and 600 N with both Group-IS and Group-LCP. For the wedge-in models, no statistical differences in displacement, axial stiffness, or load to failure were observed among the four groups. Overall, wedge-out models exhibited less axial stiffness than wedge-in models (all p < 0.01). CONCLUSIONS: Functional reduction with stable fixation of the medial column is essential for the biomechanical stability of valgus pilon fractures and medial column fixation provides the enough biomechanical stability for this kind of fracture in the combination of anterolateral fixation. In detail, the K-wires can provide a provisional stability at an early stage. Intramedullary screws are strong enough to provide the medial column stability as a definitive fixation. In future, this technique can be recommended for medial column fixation as a complement for holistic stability in high-energy valgus pilon fractures.


Subject(s)
Bone Plates , Tibial Fractures , Humans , Biomechanical Phenomena , Tibial Fractures/surgery , Tibial Fractures/diagnostic imaging , Tibial Fractures/physiopathology , Bone Screws , Fracture Fixation, Internal/methods , Fracture Fixation, Internal/instrumentation , Ankle Fractures/surgery , Ankle Fractures/diagnostic imaging , Ankle Fractures/physiopathology , Bone Wires , Male , Weight-Bearing , Female , Adult , Middle Aged
8.
Int Wound J ; 21(7): e14957, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38994923

ABSTRACT

Prolonged mechanical loading of the skin and underlying soft tissue cause pressure ulceration. The use of special support surfaces are key interventions in pressure ulcer prevention. They modify the degree and duration of soft tissue deformation and have an impact on the skin microclimate. The objective of this randomized cross-over trial was to compare skin responses and comfort after lying for 2.5 h supine on a support surface with and without a coverlet that was intended to assist with heat and moisture removal at the patient/surface interface. In addition, physiological saline solution was administered to simulate an incontinence episode on the mattress next to the participants' skin surface. In total, 12 volunteers (mean age 69 years) with diabetes mellitus participated. After loading, skin surface temperature, stratum corneum hydration and skin surface pH increased, whereas erythema and structural stiffness decreased at the sacral area. At the heel skin area, temperature, erythema, and stratum corneum hydration increased. These results indicate occlusion and soft tissue deformation which was aggravated by the saline solution. The differences in skin response showed only minor differences between the support surface with or without the coverlet.


Subject(s)
Beds , Cross-Over Studies , Heel , Pressure Ulcer , Humans , Aged , Pressure Ulcer/prevention & control , Male , Female , Middle Aged , Weight-Bearing/physiology , Aged, 80 and over , Skin Temperature/physiology
9.
Adv Skin Wound Care ; 37(8): 434-439, 2024 Aug 01.
Article in English | MEDLINE | ID: mdl-39037098

ABSTRACT

ABSTRACT: Offloading is a key principle to healing diabetic foot ulcers. Nonremovable knee-high offloading devices are considered the criterion standard for offloading plantar forefoot ulcers. However, patients exhibit a limited tolerance for these devices, which contributes to a lack of use. In this case series describing two patients, the authors share two alternative offloading modalities for the treatment of diabetic plantar forefoot ulcers. One patient was managed using a football offloading dressing, and the other was managed with a modified felted football dressing. The football and modified felted football offloading dressings provide a cost-effective, less time-consuming application and often are a better-tolerated alternative to nonremovable knee-high offloading devices. Clinical findings support further investigation into dressing options tolerated by patients with improved adherence and optimal healing outcomes.


Subject(s)
Diabetic Foot , Wound Healing , Humans , Diabetic Foot/therapy , Male , Middle Aged , Wound Healing/physiology , Female , Bandages , Aged , Forefoot, Human , Weight-Bearing , Treatment Outcome
10.
Med Sci Monit ; 30: e944383, 2024 Jul 23.
Article in English | MEDLINE | ID: mdl-39039768

ABSTRACT

BACKGROUND The evidence on use of supplementary titanium cable cerclage (TCC) in treating femoral subtrochanteric fractures (FSF) remains scarce. Therefore, this study aimed to investigate the potential therapeutic effects for FSF patients using TCC. MATERIAL AND METHODS A retrospective study of 68 FSF patients treated by a long intramedullary (IM) nailing with (Observation group, n=41) or without (Control group, n=27) TCC was conducted from January 2020 to December 2021. The primary outcome measure was time to postoperative full weight-bearing. Secondary outcome measures were operation time, intraoperative blood loss, number of blood transfusions needed, varus angle loss, excellent and good rate of fracture reduction, Harris score, and survival rate. RESULTS Patients were followed up for 13 to 36 months. The excellent and good rate of fracture reduction was 100% in the Observation group versus 92.6% in the Control group (P=0.013), and the varus angle loss and time to postoperative full weight-bearing in the Observation group were significantly less than in the Control group (P<0.05). The intraoperative blood loss in the Observation group was significantly higher than in the Control group (P<0.001). No differences were noted between groups for Harris scores and survival rates at last follow-up. CONCLUSIONS TCC fixation combined with IM nailing can improve the excellent and good rate of fracture reduction and reduce varus angle loss, as well as shorten the time to full weight-bearing and promote early functional exercise, which offers an effective treatment option for FSF patients who have failed closed reduction.


Subject(s)
Bone Nails , Fracture Fixation, Intramedullary , Hip Fractures , Titanium , Humans , Female , Retrospective Studies , Male , Fracture Fixation, Intramedullary/methods , Aged , Hip Fractures/surgery , Treatment Outcome , Middle Aged , Femoral Fractures/surgery , Aged, 80 and over , Weight-Bearing
11.
BMC Musculoskelet Disord ; 25(1): 527, 2024 Jul 09.
Article in English | MEDLINE | ID: mdl-38982445

ABSTRACT

BACKGROUND: This study investigated the effects of changes in motor skills from an educational video program on the kinematic and kinetic variables of the lower extremity joints and knee ligament load. METHODS: Twenty male participants (age: 22.2 ± 2.60 y; height: 1.70 ± 6.2 m; weight: 65.4 ± 7.01 kg; BMI: 23.32 ± 2.49 [Formula: see text]) were instructed to run at 4.5 ± 0.2 m/s from a 5 m distance posterior to the force plate, land their foot on the force plate, and perform the cutting maneuver on the left. The educational video program for cutting maneuvers consisted of preparatory posture, foot landing orientation, gaze and trunk directions, soft landing, and eversion angle. The measured variables were the angle, angular velocity of lower extremity joints, ground reaction force (GRF), moment, and anterior cruciate ligament (ACL) and medial collateral ligament (MCL) forces through musculoskeletal modeling. RESULTS: After the video feedback, the hip joint angles increased in flexion, abduction, and external rotation (p < 0.05), and the angular velocity increased in extension (p < 0.05). The ankle joint angles increased in dorsiflexion (p < 0.05), and the angular velocity decreased in dorsiflexion (p < 0.05) but increased in abduction (p < 0.05). The GRF increased in the anterior-posterior and medial-lateral directions and decreased vertically (p < 0.05). The hip joint moments decreased in extension and external rotation (p < 0.05) but increased in adduction (p < 0.05). The knee joint moments were decreased in extension, adduction, and external rotation (p < 0.05). The abduction moment of the ankle joint decreased (p < 0.001). There were differences in the support zone corresponding to 64‒87% of the hip frontal moment (p < 0.001) and 32‒100% of the hip horizontal moment (p < 0.001) and differences corresponding to 32‒100% of the knee frontal moment and 21‒100% of the knee horizontal moment (p < 0.001). The GRF varied in the support zone at 44‒95% in the medial-lateral direction and at 17‒43% and 73‒100% in the vertical direction (p < 0.001). CONCLUSIONS: Injury prevention feedback reduced the load on the lower extremity joints during cutting maneuvers, which reduced the knee ligament load, mainly on the MCL.


Subject(s)
Knee Joint , Motor Skills , Weight-Bearing , Humans , Male , Young Adult , Weight-Bearing/physiology , Knee Joint/physiology , Biomechanical Phenomena/physiology , Motor Skills/physiology , Video Recording , Hip Joint/physiology , Ankle Joint/physiology , Adult , Running/physiology , Lower Extremity/physiology
12.
Appl Ergon ; 120: 104340, 2024 Oct.
Article in English | MEDLINE | ID: mdl-38964218

ABSTRACT

Augmented reality (AR) environments are emerging as prominent user interfaces and gathering significant attention. However, the associated physical strain on the users presents a considerable challenge. Within this background, this study explores the impact of movement distance (MD) and target-to-user distance (TTU) on the physical load during drag-and-drop (DND) tasks in an AR environment. To address this objective, a user experiment was conducted utilizing a 5× 5 within-subject design with MD (16, 32, 48, 64, and 80 cm) and TTU (40, 80, 120, 160, and 200 cm) as the variables. Physical load was assessed using normalized electromyography (NEMG) (%MVC) indicators of the upper extremity muscles and the physical item of NASA-Task load index (TLX). The results revealed significant variations in the physical load based on MD and TTU. Specifically, both the NEMG and subjective physical workload values increased with increasing MD. Moreover, NEMG increased with decreasing TTU, whereas the subjective physical workload scores increased with increasing TTU. Interaction effects of MD and TTU on NEMG were also significantly observed. These findings suggest that considering the MD and TTU when developing content for interacting with AR objects in AR environments could potentially alleviate user load.


Subject(s)
Augmented Reality , Electromyography , Movement , Muscle, Skeletal , Task Performance and Analysis , Upper Extremity , User-Computer Interface , Humans , Upper Extremity/physiology , Male , Young Adult , Muscle, Skeletal/physiology , Female , Movement/physiology , Adult , Workload , Weight-Bearing/physiology , Virtual Reality
13.
J Biomech Eng ; 146(11)2024 Nov 01.
Article in English | MEDLINE | ID: mdl-38949883

ABSTRACT

This study sought to evaluate the effects of prolonged cyclic loading on the tissue-level mechanical properties of the spinal annulus fibrosus. Functional spinal units (FSUs) were obtained from porcine cervical spines at the C3-C4 and C5-C6 levels. Following a 15-min preload of 300 N of axial compression, the FSUs were split into three groups: the cyclic loading group cycled between 0.35 MPa and 0.95 MPa for 2 h (n = 8); the static loading group was compressed at 0.65 MPa for 2 h (n = 10); and a control group which only underwent the 300 N preload (n = 11). Following loading, samples of the annulus were excised to perform intralamellar tensile testing and interlamellar 180 deg peel tests. Variables analyzed from the intralamellar test were stress and strain at the end of the toe region, stress and strain at initial failure (yield point), Young's modulus, ultimate stress, and strain at ultimate stress. Variables evaluated from the interlamellar tests were lamellar adhesion strength, adhesion strength variability, and stiffness. The analysis showed no significant differences between conditions on any measured variable; however, there was a trend (p = 0.059) that cyclically loaded tissues had increased adhesion strength variability compared to the static and control conditions. The main finding of this study is that long-duration axial loading did not impact the intra- or interlamellar mechanical properties of the porcine annulus. A trend of increased adhesion strength variability in cyclically loaded samples could indicate a potential predisposition of the annulus to delamination.


Subject(s)
Annulus Fibrosus , Stress, Mechanical , Weight-Bearing , Animals , Annulus Fibrosus/physiology , Swine , Biomechanical Phenomena , Mechanical Tests , Materials Testing , Tensile Strength , Elastic Modulus/physiology
14.
J Orthop Surg Res ; 19(1): 418, 2024 Jul 20.
Article in English | MEDLINE | ID: mdl-39033286

ABSTRACT

BACKGROUND: Clinical repair of critical-sized bone defects (CBDs) in the tibial diaphysis presents numerous challenges, including inadequate soft tissue coverage, limited blood supply, high load-bearing demands, and potential deformities. This study aimed to investigate the clinical feasibility and efficacy of employing 3D-printed prostheses for repairing CBDs exceeding 10 cm in the tibial diaphysis. METHODS: This retrospective study included 14 patients (11 males and 3 females) with an average age of 46.0 years. The etiologies of CBDs comprised chronic osteomyelitis (10 cases) and aseptic non-union (4 cases), with an average defect length of 16.9 cm. All patients underwent a two-stage surgical approach: (1) debridement, osteotomy, and cement spacer implantation; and (2) insertion of 3D-printed prostheses. The interval between the two stages ranged from 8 to 12 weeks, during which the 3D-printed prostheses and induced membranes were meticulously prepared. Subsequent to surgery, patients engaged in weight-bearing and functional exercises under specialized supervision. Follow-up assessments, including gross observation, imaging examinations, and administration of the Lower Extremity Functional Scale (LEFS), were conducted at 3, 6, and 12 months postoperatively, followed by annual evaluations thereafter. RESULTS: The mean postoperative follow-up duration was 28.4 months, with an average waiting period between prosthesis implantation and weight-bearing of 10.4 days. At the latest follow-up, all patients demonstrated autonomous ambulation without assistance, and their LEFS scores exhibited a significant improvement compared to preoperative values (30.7 vs. 53.1, P < 0.001). Imaging assessments revealed progressive bone regeneration at the defect site, with new bone formation extending along the prosthesis. Complications included interlocking screw breakage in two patients, interlocking screw loosening in one patient, and nail breakage in another. CONCLUSIONS: Utilization of 3D-printed prostheses facilitates prompt restoration of CBDs in the tibial diaphysis, enabling early initiation of weight-bearing activities and recovery of ambulatory function. This efficacious surgical approach holds promise for practical application.


Subject(s)
Diaphyses , Osteomyelitis , Printing, Three-Dimensional , Tibia , Humans , Male , Female , Middle Aged , Osteomyelitis/surgery , Osteomyelitis/diagnostic imaging , Retrospective Studies , Adult , Tibia/surgery , Tibia/diagnostic imaging , Diaphyses/surgery , Diaphyses/diagnostic imaging , Fractures, Ununited/surgery , Fractures, Ununited/diagnostic imaging , Plastic Surgery Procedures/methods , Plastic Surgery Procedures/instrumentation , Aged , Follow-Up Studies , Prosthesis Design , Prostheses and Implants , Osteotomy/methods , Weight-Bearing , Feasibility Studies
15.
Medicina (Kaunas) ; 60(7)2024 Jul 17.
Article in English | MEDLINE | ID: mdl-39064584

ABSTRACT

Background and Objectives: Osteoporosis renders the use of traditional interbody cages potentially dangerous given the high risk of damage in the bone-implant interface. Instead, injected cement spacers can be applied as interbody devices; however, this technique has been mainly used in cervical spine surgery. This study aimed at investigating the biomechanical behavior of cement spacers versus traditional cages in lumbar spine surgery. Materials and Methods: Destructive monotonic axial compression testing was performed on 20 human cadaveric low-density lumbar segments from elderly donors (14 f/6 m, 70.3 ± 12.0 y) treated with either injected cement spacers (n = 10) or traditional cages (n = 10) without posterior instrumentation. Stiffness, failure load and displacement were compared. The effects of bone density, vertebral geometry and spacer contact area were evaluated. Results: Cement spacers demonstrated higher stiffness, significantly smaller displacement (p < 0.001) and a similar failure load compared to traditional cages. In the cage group, stiffness and failure load depended strongly on bone density and vertebral height, whereas failure displacement depended on vertebral anterior height. No such correlations were identified with cement spacers. Conclusions: Cement spacers used in lumbar interbody stabilization provided similar compression strength, significantly smaller failure displacement and a stiffer construct than traditional cages that provided benefits mainly for large and strong vertebrae. Cement stabilization was less sensitive to density and could be more beneficial also for segments with smaller and less dense vertebrae. In contrast to the injection of cement spacers, the optimal insertion of cages into the irregular intervertebral space is challenging and risks damaging bone. Further studies are required to corroborate these findings and the treatment selection thresholds.


Subject(s)
Bone Cements , Cadaver , Lumbar Vertebrae , Humans , Lumbar Vertebrae/surgery , Lumbar Vertebrae/physiology , Biomechanical Phenomena , Bone Cements/therapeutic use , Male , Aged , Female , Middle Aged , Aged, 80 and over , Bone Density , Compressive Strength , Weight-Bearing/physiology , Osteoporosis
16.
J Mech Behav Biomed Mater ; 157: 106631, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38986216

ABSTRACT

Fall-related hip fractures are a serious public health issue in older adults. As most mechanistic hip fracture risk prediction models incorporate tissue tolerance, test methods that can accurately characterize the fracture force of the femur (and factors that influence it) are imperative. While bone possesses viscoelastic properties, experimental characterization of rate-dependencies has been inconsistent in the whole-femur literature. The goal of this study was to investigate the influence of experimental paradigm on loading rate and fracture force (both means and variability) during mechanical tests simulating lateral fall loadings on the proximal femur. Six pairs of matched femurs were split randomly between two test paradigms: a 'lower rate' materials testing system (MTS) with a constant displacement rate of 60 mm/s, and a hip impact test system (HIT) comprised of a custom-built vertical drop tower utilizing an impact velocity of 4 m/s. The loading rate was 88-fold higher for the HIT (mean (SD) = 2465.49 (807.38) kN/s) compared to the MTS (27.78 (10.03) kN/s) paradigm. However, no difference in fracture force was observed between test paradigms (mean (SD) = 4096.4 (1272.6) N for HIT, and 3641.3 (1285.8) N for MTS). Within-paradigm variability was not significantly different across paradigms for either loading rate or fracture force (coefficients of variation ranging from 0.311 to 0.361). Within each test paradigm, significant positive relationships were observed between loading rate and fracture force (HIT adjusted R2 = 0.833, p = 0.007; MTS adjusted R2 = 0.983, p < 0.0001). Overall, this study provides evidence that energy-based impact simulators can be a valid method to measure femoral bone strength in the context of fall-related hip fractures. This study motivates future research to characterize potential non-linear relationships between loading rate and fracture threshold at both macro and microscales.


Subject(s)
Accidental Falls , Femur , Materials Testing , Weight-Bearing , Humans , Femur/physiology , Aged , Male , Mechanical Tests , Female , Biomechanical Phenomena , Femoral Fractures/physiopathology , Aged, 80 and over , Stress, Mechanical , Proximal Femoral Fractures
17.
J Biomech ; 172: 112223, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38986275

ABSTRACT

During forward flexion, spine motion varies due to age and sex differences. Previous studies showed that lumbar/pelvis range of flexion (RoF) and lumbo-pelvic ratio (L/P) are age/sex dependent. How variation of these parameters affects lumbar loading in a normal population requires further assessment. We aimed to estimate lumbar loads during dynamic flexion-return cycle and the differences in peak loads (compression) and corresponding trunk inclinations due to variation in lumbar/pelvis RoF and L/P. Based on in vivo L/P (0.11-3.44), temporal phases of flexion (early, middle, and later), the lumbar (45-55°) and hip (60-79°) RoF; full flexion-return cycles of six seconds were reconstructed for three age groups (20-35, 36-50 and 50+ yrs.) in both sexes. Six inverse dynamic analyses were performed with a 50th percentile model, and differences in peak loads and corresponding trunk inclinations were calculated. Peak loads at L4-L5 were 179 N higher in younger males versus females, but 228 N and 210 N lower in middle-aged and older males, respectively, compared to females. Females exhibited higher trunk inclinations (6°-20°) than males across all age groups. Age related differences in L4-L5 peak loads and corresponding trunk inclinations were found up to 415 N and 19° in males and 152 N and 13° in females. With aging, peak loads were reduced in males but were found non-monotonic in females, whereas trunk inclinations at peak loads were reduced in both sexes from young to middle/old age groups. In conclusion, lumbar loading and corresponding trunk inclinations varied notably due to age/sex differences. Such data may help distinguishing normal or pathological condition of the lumbar spine.


Subject(s)
Lumbar Vertebrae , Weight-Bearing , Humans , Male , Female , Adult , Middle Aged , Lumbar Vertebrae/physiology , Weight-Bearing/physiology , Standing Position , Range of Motion, Articular/physiology , Models, Biological , Biomechanical Phenomena , Age Factors , Sex Characteristics , Posture/physiology , Young Adult , Aging/physiology , Spine/physiology , Pelvis/physiology
18.
J Biomech ; 172: 112229, 2024 Jul.
Article in English | MEDLINE | ID: mdl-39004041

ABSTRACT

The success of surgical treatment for fractures hinges on various factors, notably accurate surgical indication. The process of developing and certifying a new osteosynthesis device is a lengthy and costly process that requires multiple cycles of review and validation. Current methods, however, often rely on predecessor standards rather than physiological loads in specific anatomical locations. This study aimed to determine actual loads experienced by an osteosynthesis plate, exemplified by a standard locking plate for the femoral shaft, utilizing finite elements analysis (FEA) and to obtain the bending moments for implant development standard tests. A protocol was developed, involving the creation and validation of a fractured femur model fixed with a locking plate, mechanical testing, and FEA. The model's validation demonstrated exceptional accuracy in predicting deformations, and the FEA revealed peak stresses in the fracture bridging zone. Results of a parametric analysis indicate that larger fracture gaps significantly impact implant mechanical behavior, potentially compromising stability. This study underscores the critical need for realistic physiological conditions in implant evaluations, providing an innovative translational approach to identify internal loads and optimize implant designs. In conclusion, this research contributes to enhancing the understanding of implant performance under physiological conditions, promoting improved designs and evaluations in fracture treatments.


Subject(s)
Femoral Fractures , Femur , Finite Element Analysis , Stress, Mechanical , Humans , Femur/physiology , Femur/surgery , Femoral Fractures/surgery , Femoral Fractures/physiopathology , Bone Plates , Weight-Bearing/physiology , Fracture Fixation, Internal/methods , Fracture Fixation, Internal/instrumentation , Models, Biological , Biomechanical Phenomena
19.
Microsurgery ; 44(5): e31209, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38970406

ABSTRACT

BACKGROUND: Instep flaps are commonly used for the reconstruction of weight-bearing areas of the foot. However, in cases of large defects or damage to the instep area, non-instep flaps such as reverse sural flaps (RSF) or free anterolateral thigh flaps (ALTF) can be employed. Previous studies have primarily focused on heel reconstruction when comparing different flaps, without considering the forefoot. This study aims to verify the clinical outcomes of these flaps and determine the appropriate donor site for weight-bearing areas of the foot including forefoot reconstruction. METHODS: In a retrospective study, 39 patients who had undergone flap reconstruction of weight-bearing area defects in the foot with a follow-up period of ≥1 year were included. The patients were categorized into two groups: Group A (n = 19) using instep flaps, and Group B (n = 20) using non-instep flap including RSFs and ALTFs. Surgical outcomes were assessed based on the success of the flap, the presence of partial necrosis, the number of additional surgeries, and complications related to the donor site. Clinical evaluation included visual analogue scale (VAS) and American Orthopedic Foot and Ankle Society (AOFAS) score, and the occurrence of ulcers. RESULTS: All flaps were successful, while partial necrosis occurred in one case in Group B. There were three reclosures after flap border debridement in both groups and one donor site debridement in Group A. The VAS scores during weight-bearing were 2.0 ± 1.1 and 2.2 ± 1.5 for Groups A and B, respectively (p = .716). The AOFAS scores were 52.8 ± 6.8 and 50.2 ± 12.7 for Groups A and B, respectively (p = .435). The occurrence of ulcers was 0.4 ± 0.9 times for Group A and 0.3 ± 0.7 times for Group B, with no significant difference between the two groups (p = .453). CONCLUSION: There was no difference in clinical outcomes between the types of flaps after reconstruction of the forefoot and hindfoot. Therefore, it is recommended to choose the appropriate flap based on factors such as the size of the defect, its location, and vascular status rather than the type of flap.


Subject(s)
Foot Injuries , Forefoot, Human , Heel , Plastic Surgery Procedures , Weight-Bearing , Humans , Retrospective Studies , Female , Male , Middle Aged , Plastic Surgery Procedures/methods , Heel/surgery , Heel/injuries , Adult , Foot Injuries/surgery , Forefoot, Human/surgery , Surgical Flaps/transplantation , Soft Tissue Injuries/surgery , Aged , Free Tissue Flaps/transplantation , Treatment Outcome , Young Adult
20.
Bone Joint J ; 106-B: xxx, 2024 Jul 09.
Article in English | MEDLINE | ID: mdl-38979634

ABSTRACT

Aims: Weightbearing instructions after musculoskeletal injury or orthopaedic surgery are a key aspect of the rehabilitation pathway and prescription. The terminology used to describe the weightbearing status of the patient is variable; many different terms are used, and there is recognition and evidence that the lack of standardized terminology contributes to confusion in practice. Methods: A consensus exercise was conducted involving all the major stakeholders in the patient journey for those with musculoskeletal injury. The consensus exercise primary aim was to seek agreement on a standardized set of terminology for weightbearing instructions. Results: A pre-meeting questionnaire was conducted. The one-day consensus meeting, including patient representatives, identified three agreed terms only to be used in defining the weightbearing status of the patient: 1) non-weightbearing; 2) limited weightbearing; and 3) unrestricted weightbearing. Conclusion: This study represents the first and only exercise in standardizing rehabilitation terminology in orthopaedics, as agreed by all major stakeholders in the patient pathway and the patients themselves. The standardization of language allows for higher-quality and more accurate research to be conducted, and is one small part of the bigger picture in increasing the mobility of patients after orthopaedic injury or surgery.


Subject(s)
Terminology as Topic , Weight-Bearing , Humans , Consensus , Orthopedic Procedures , Surveys and Questionnaires
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