Medial Loading Research Articles

The Estimation of Knee Medial Force with Substitution Parameters during Walking and Turning.

Knee adduction, flexion moment, and adduction angle are often used as surrogate parameters of knee medial force. To verify whether these parameters are suitable as surrogates under different walking states, we investigated the correlation between knee medial loading with the surrogates during walking and turning. Sixteen healthy subjects were recruited to complete straight walk (SW), step turn (ST), and crossover turn (CT). Knee joint moments were obtained using inverse dynamics, and knee medial force was computed using a previously validated musculoskeletal model, Freebody. Linear regression was used to predict the peak of knee medial force with the peaks of the surrogate parameters and walking speed. There was no significant difference in walking speed among these three tasks. The peak knee adduction moment (pKAM) was a significant predictor of the peak knee medial force (pKMF) for SW, ST, and CT (p < 0.001), while the peak knee flexion moment (pKFM) was only a significant predictor of the pKMF for SW (p = 0.034). The statistical analysis showed that the pKMF increased, while the pKFM and the peak knee adduction angle (pKAA) decreased significantly during CT compared to those of SW and ST (p < 0.001). The correlation analysis indicated that the knee parameters during SW and ST were quite similar. This study investigated the relationship between knee medial force and some surrogate parameters during walking and turning. KAM was still the best surrogate parameter for SW, ST, and CT. It is necessary to consider the type of movement when comparing the surrogate predictors of knee medial force, as the prediction equations differ significantly among movement types.

The Effect of First Metatarsal Shortening and Sagittal Displacement on Forefoot Pressure in Minimally Invasive Hallux Valgus Correction.

Minimally invasive (MIS) treatment of hallux valgus (HV) deformity is increasing in popularity. A 2-mm diameter burr is used to create a distal first metatarsal osteotomy prior to capital fragment translation and fixation. The metatarsal will shorten by the burr's diameter (2 mm). Plantar or dorsal capital fragment displacement may also cause load transference and possibly transfer metatarsalgia. The purpose of this study is to examine the effect of MIS HV on forefoot loading mechanics with respect to metatarsal shortening and sagittal plane displacement. Four lower-limb cadaveric specimens were studied. A pedobarography pressure-sensing mat was used to record forefoot plantar pressure in a controlled weight-bearing stance position. Control and postosteotomy measurements were obtained with the capital fragment fixated in 3 possible positions: 0 mm, 5 mm dorsal, and 5 mm plantar displacement. Pedobarography data yielded pressure data within measurable graphical depictions. Raw mean contact pressure measurements were taken under the first and fourth metatarsal heads to establish medial and lateral forefoot loading pressure ratios. An a priori power analysis was performed based on previous peer-reviewed pedobarographic data, and our study was adequately powered. Around 40 measurements were recorded, and ratios of medial-to-lateral forefoot loading were constructed. Medial forefoot pressure control versus 0 mm displacement, and control versus dorsal displacement were not found to be statistically significant (p = 0.525, p = 0.55, respectively). Medial pressure significantly increased when comparing control versus plantar displacement (P = .006). Lateral pressure significantly increased with dorsal displacement of the osteotomy (P = .013). Our study found that MIS HV correction did not cause an increase in lateral forefoot pressure loading when sagittal plane displacements were controlled. Plantar displacement increased medial loading, and dorsal displacement increased lateral loading. It may be valuable for surgeons to consider metatarsal head position postosteotomy, as a decrease in medial loading and subsequent increase in lateral loading may lead to lateral forefoot pain and transfer metatarsalgia. IV.

Medial cortical bone thickness of the tibial diaphysis in osteoarthritis is related to lower extremity alignment and tibial morphology

BackgroundThe purpose of this study was to clarify (1) the differences in cortical bone thickness (CBT) of the tibial diaphysis between healthy and osteoarthritic knees and (2) the influences of the femorotibial angle (FTA) and inclination of the medial compartment of the proximal tibia (MCT) on tibial CBT.MethodsThe study assessed 60 subjects with varus knee osteoarthritis (OA) (22 males and 38 females; mean age, 74 ± 7 years) and 53 healthy elderly subjects (28 males and 25 females; mean age, 70 ± 6 years). Three-dimensional estimated CBT of the tibial diaphysis was automatically calculated for 2752–11,296 points using high-resolution measurements from CT. The standardized CBT was assessed in 24 regions by combining six heights and four areas. Additionally, the association between the CBT, each FTA, and MCT inclination was investigated.ResultsThe OA group showed a thicker CBT in the medial areas than in the lateral areas of the proximal tibia, while the healthy group had a thicker lateral CBT. The medial-to-lateral ratio of the proximal tibia was significantly higher in the OA group than in the healthy group. The proximal-medial CBT correlated with FTA and MCT inclinations in the OA group.ConclusionsThis study demonstrated that varus osteoarthritic knees showed a different trend of proximal-medial CBT with associations in FTA and MCT inclination from healthy knees, possibly due to medial load concentration.

Differences in ankle and knee muscle architecture and plantar pressure distribution among women with knee osteoarthritis.

The aim of this study was to compare the plantar pressure distribution and knee and ankle muscle architecture in women with and without knee osteoarthritis (OA). Fifty women with knee OA (mean age=52.11±4.96years, mean Body mass index (BMI)=30.94±4.23kg/m2) and 50 healthy women as a control group (mean age=50.93±3.78years, mean BMI=29.06±4.82kg/m2) were included in the study. Ultrasonography was used to evaluate knee and ankle muscles architecture and femoral cartilage thickness. The plantar pressure distribution was evaluated using the Digital Biometry Scanning System and Milleri software (DIASU, Italy). Static foot posture was evaluated using the Foot Posture Index (FPI), and pain severity was assessed using the Visual Analog Scale. The OA group exhibited lower muscle thickness in Rectus Femoris (RF) (p=0.003), Vastus Medialis (VM) (p=0.004), Vastus Lateralis (p=0.023), and Peroneus Longus (p=0.002), as well as lower Medial Gastrocnemius pennation angle (p=0.049) and higher Fat thickness (FT) in RF (p=0.033) and VM (p=0.037) compared to the control group. The OA group showed thinner femoral cartilage thickness (p=0.001) and higher pain severity (p=0.001) than the control groups. FPI scores were higher (p=0.001) in OA group compared to the control group. The plantar pressure distribution results indicated an increase in total surface (p=0.027), total load (p=0.002), medial load (p=0.005), and lateral load (p=0.002) on dominant side in OA group compared to the control group. Knee and ankle muscle architecture, knee extensor muscle FT, and plantar pressure distribution in the dominant foot differed in individuals with knee OA compared to the control group.

The Effect of First Metatarsal Shortening and Sagittal Displacement on Forefoot Pressure in MIS Hallux Valgus Correction

Introduction/Purpose: Minimally invasive surgical (MIS) treatment of hallux valgus (HV) deformity is increasing in popularity. A 2mm-diameter burr is used to create a distal first metatarsal osteotomy prior to capital fragment translation and fixation. The metatarsal will shorten by the burr’s diameter (2mm). Plantar or dorsal capital fragment displacement may also cause load transference and possibly transfer metatarsalgia. In this study, we examine the effect of MIS HV on forefoot loading mechanics with respect to metatarsal shortening and sagittal plane displacement. Methods: Four lower-limb cadaveric specimens were studied. A pedobarography pressure-sensing mat was used to record forefoot plantar pressure in a controlled weightbearing stance position.10 Control and post-osteotomy measurements were obtained with the capital fragment fixated in 3 possible positions: 0mm, 5mm dorsal, and 5mm plantar displacement. Pedobarography data yielded pressure data within measurable graphical depictions. Raw mean contact pressure measurements were taken under the first and fifth metatarsal heads to establish medial and lateral forefoot loading pressure ratios. A priori power analysis was performed based on previous peer-reviewed pedobarographic data and our study was adequately powered. Results: 40 measurements were recorded and ratios of medial-to-lateral forefoot loading were constructed. Medial forefoot pressure change control versus 0mm displacement, and control versus dorsal displacement was not found to be statistically significant (p=0.525, p=0.55 respectively). Significant medial pressure increase was identified comparing control versus plantar displacement (p=0.006). Lateral pressure increased significantly with dorsal displacement of the osteotomy (p=0.013). Conclusion: MIS hallux valgus correction does not appear to cause increase in lateral forefoot pressure loading when sagittal plane displacements are controlled. Plantar displacement increases medial loading, and dorsal displacement increases lateral loading. The clinician must consider metatarsal head position post-osteotomy, as decrease in medial loading and subsequent increase in lateral loading may lead to lateral forefoot pain and transfer metatarsalgia.

An evaluation of subtalar titanium screw arthroereisis for the treatment of symptomatic paediatric flatfeet - early results

BackgroundIdiopathic flexible flatfoot is a common condition in children which typically improves with age and remains asymptomatic. However, the condition can sometimes be more severe, and cause mechanical impairment or pain. The aim of the study was to perform a prospective clinical, radiological, podoscopic and pedobarographic assessment (static and dynamic) of subtalar titanium screw arthroereisis for the treatment of symptomatic, idiopathic, flexible flatfeet.MethodsA prospective, consecutive, non-controlled, cohort, clinical follow-up study was performed. In total, 30 patients (41 feet), mean age 10 (6 to 16 years), were evaluated. Clinical and standing radiological assessments, static and dynamic pedobarography, as well as podoscopy, were performed before surgery and at final follow-up.ResultsTreatment was associated with significant improvements in heel valgus angle, radiographic parameters (lateral and dorso-planar talo-first metatarsal angle, calcaneal inclination angle, talar declination angle, longitudinal arch angle) and podoscopic parameters (Clark’s angle, Staheli’s arch index and Chippaux-Smirak index). Significant increases were noted for lateral loading, forefoot contact phase and double support / swing phase, and reduced medial loading (dynamic pedobarography), as well as lateral midfoot area and loading, but decreased were observed for medial forefoot loading (static pedobarography). Four patients reported persistent pain in the sinus tarsi region (six feet), and in one case, the implant was replaced for a larger one due to undercorrection. No overcorrections or infection complications were noted in the study group.ConclusionsSubtalar arthroereisis is a minimally-invasive and effective surgical method for treating symptomatic, idiopathic, flexible flatfeet; it has an acceptable complication rate with good early clinical results.Level of evidenceII b.

The Unloading Effect of Supramalleolar Versus Sliding Calcaneal Osteotomy for Treatment of Osteochondral Lesions of the Medial Talus: A Biomechanical Study.

In patients with osteochondral lesion, defects of the medial talus, or failed cartilage surgery, a periarticular osteotomy can unload the medial compartment. To compare the effects of supramalleolar osteotomy (SMOT) versus sliding calcaneal osteotomy (SCO) for pressure redistribution and unloading of the medial ankle joint in normal, varus-aligned, and valgus-aligned distal tibiae. Controlled laboratory study. Included were 8 cadaveric lower legs with verified neutral ankle alignment (lateral distal tibial angle [LDTA] = 0°) and hindfoot valgus within normal range (0°-10°). SMOT was performed to modify LDTA between 5° valgus, neutral, and 5° varus. In addition, a 10-mm lateral SCO was performed and tested in each position in random order. Axial loading (700 N) of the tibia was applied with the foot in neutral alignment in a customized testing frame. Pressure distribution in the ankle joint and subtalar joint, center of force, and contact area were recorded using high-resolution Tekscan pressure sensors. At neutral tibial alignment, SCO unloaded the medial joint by a mean of 10% ± 10% or 66 ± 51 N (P = .04) compared with 6% ± 12% or 55 ± 72 N with SMOT to 5° valgus (P = .12). The achieved deload was not significantly different (ns) between techniques. In ankles with 5° varus alignment at baseline, SMOT to correct LDTA to neutral insufficiently addressed pressure redistribution and increased medial load by 6% ± 9% or 34 ± 33 N (ns). LDTA correction to 5° valgus (10° SMOT) unloaded the medial joint by 0.4% ± 14% or 20 ± 75 N (ns) compared with 9% ± 11% or 36 ± 45 N with SCO (ns). SCO was significantly superior to 5° SMOT (P = .017) but not 10° SMOT. The subtalar joint was affected by both SCO and SMOT, where SCO unloaded but SMOT loaded the medial side. SCO reliably unloaded the medial compartment of the ankle joint for a neutral tibial axis. Changes in the LDTA by SMOT did not positively affect load distribution, especially in varus alignment. The subtalar joint was affected by SCO and SMOT in opposite ways, which should be considered in the treatment algorithm. SCO may be considered a reliable option for beneficial load-shifting in ankles with neutral alignment or 5° varus malalignment.

Cofactorial herniotransformation peculiarities of midline abdomen

Relevance. Recently, much attention has been paid to the study of the role of various risk factors in the pathogenesis of herniation along the midline of the abdomen. The question of their interrelation with another equally important predictor of herniogenesis - connective tissue insufficiency remains understudied. The aim of the present study is to investigate the severity of connective tissue dysplasia and peculiarities of its interaction with other risk factors in different variants of midline abdominal herniotransformation. Materials and Methods. The examined group included 150 (89.2%) patients with postoperative median hernias of various sizes and 18 (10.8%) patients with primary hernias of the white line of the abdomen. In 12 (8%) cases, relapses of postoperative hernial protrusions were noted. In 12 (10.5 %) cases, relapses of postoperative hernial protrusions were noted. The surveyed group included 109 (64.8 %) women and 59 (35.2 %) men. Risk factors for median herniogenesis were evaluated in the opposite sense relative to the severity of connective tissue pathology. Results and Discussion. We evaluated the risk factors of median herniogenesis in the opposite value and direction with regard to the severity of connective tissue pathology in the observation groups. It was found out that the leading role in herniotransformation of the medial abdominal line belongs to the suppuration of postoperative medial wounds, relaparotomy and heavy physical load with the role efficiency of 66.6 %, 56.2 % and 54.5 % respectively. The lowest level of connective tissue dysplasia was observed in the groups where the risk factors of median herniogenesis were the age of patients, the presence of relaparotomy in the history and heavy physical activity. Only in the observation group, where pregnancy and childbirth in the anamnesis were the predictors, the patients with white line hernias had less severe connective tissue insufficiency by 27,9 % in comparison with the patients with postoperative median hernias. In patients with recurrent midline hernias in all risk factors, the severity of connective tissue dysplasia always reached the maximum score. Conclusion. At any predictor of hernia formation or their combined effect, the severity of connective tissue dysplasia always remained severe, which confirms one of the leading roles of connective tissue pathology in the formation of medial abdominal hernias.

Track Running Shoes: A Case Report of the Transition from Classical Spikes to “Super Spikes” in Track Running

Research on high-tech running shoes is increasing but few studies are available about the use of high-tech track spike shoes (super spikes), despite their growing popularity among running athletes. The aim of this case study was to investigate kinematics, kinetics, and plantar pressures of an Olympic running athlete using two different types of shoes, to provide an easy and replicable method to assess their influence on running biomechanics. The tested athlete performed six running trials, at the same speed, wearing a pair of normal spikes shoes (NSS) and a super spikes shoe (SSS), in random order. SSS increased contact time, vertical impact, and swing force (Effect Size 3.70, 7.86, and 1.31, respectively), while it reduced foot-strike type and vertical ground reaction force rate (Effect Size 3.62 and 7.21, respectively). Moreover, a significant change was observed in medial and lateral load, with SSS inducing a more symmetrical load distribution between the left and right feet compared to the NSS (SSS left medial load 57.1 ± 2.1%, left lateral load 42.9 ± 1.4%, right medial load 55.1 ± 2.6%, right lateral load 44.9 ± 2.6%; NSS left medial load 58.4 ± 2.6%, left lateral load 41.6 ± 2.1%, right medial load 49.2 ±3.7%, right lateral load 50.8 ± 3.7%). The results of this case study suggest the importance of using individual evaluation methods to assess shoe adaptations in running athletes, which can induce biomechanical modifications and should be considered by coaches to ensure optimal running performance.

Effects of Attrition Shoes on Kinematics and Kinetics of Lower Limb Joints During Walking.

Shoe attrition is inevitable as wearing time increases, which may produce diverse influences on kinematics and kinetics of lower limb joints. Excessive attrition may change support alignment and lead to deleterious impacts on the joints. The study identifies the biomechanical influences of aging shoes on lower limb joints. The shoes in the experiment were manually worn in the lateral heel. Nineteen healthy participants, including thirteen males and six females, were recruited to conduct walking experiments wearing attrition shoes (AS) and new shoes (NS) with a random order. A Vicon motion analysis system was used to collect kinematic data and ground reaction force. Kinematic and kinetic parameters of the hip, knee, and ankle joints were calculated using the Anybody Musculoskeletal Model and compared between the two conditions, AS and NS. The results showed that wearing an attrition shoe decreased the plantarflexion angle and plantarflexion moment of the ankle joint, while significantly increasing the magnitude of the first peak of the knee adduction moment and hip abduction moment and hip internal rotation moment (p < .05). The results of the study implied that wearing attrition shoes is not recommended for those people with knee problems due to increase in medial loading.

Walking Pole Gait to Reduce Joint Loading post Total Knee Athroplasty: Musculoskeletal modeling Approach.

Excessive knee contact loading is precursor to osteoarthritis and related knee ailment leading to knee athroplasty. Reducing contact loading through gait modifications using assisted pole walking offers noninvasive process of medial load offloading at knee joint. In this paper, we evaluate the efficacy of different configuration of pole walking for reducing contact force at the knee joint through musculoskeletal (MSK) modeling. We have developed a musculoskeletal model for a subject with knee athroplasty utilizing in-vivo implant data and computed tibio-femoral contact force for different pole walking conditions to evaluate the best possible configuration for guiding rehabilitation, correlated with different gait phases. Effect of gait speed variation on knee contact force, hip joint dynamics and muscle forces are simulated using the developed MSK model. Results indicate some interesting trend of load reduction, dependent on loading phases pertaining to different pole configuration. Insights gained from the simulation can aid in designing personalized rehabilitation therapy for subjects suffering from Osteoarthritis.

Effect of biomechanical correction of tibia on medial joint space loading, varus deformity and functional tasks in patients with medial tibiofemoral joint osteoarthritis: a two-group pre-test, post-test randomized clinical trial study protocol

BACKGROUND/OBJECTIVES: Knee osteoarthritis (KOA) is the most prevalent chronic disease of joints. There are various biomechanical factors which affect the alignment of the knee joints resulting in the varus or valgus deformities, which leads to unequal loading on the joints structures. The primary aim of the study is to determine the biomechanical corrections on tibia and varus deformity in Medial Tibiofemoral Knee Joint Osteoarthritis (MTKJOA). Secondary aim is to see the improvement in physical functions of the patients. METHODOLOGY/DESIGN: A Two Group Pretest-Posttest Equivalent Randomized Clinical Trial. Total ‘52’ patients will be included between the age of 35 to 80 years with medial tibiofemoral joint osteoarthritis. Subjects will be divided in the biomechanical correction group (Mobilization with movement in addition with conventional physiotherapy treatment). Conventional physiotherapy group which include electrotherapy and exercise therapy. For measuring the pain, the Numeric Pain Rating Scale (NPRS) will be taken, for range of motion goniometer will be taken, Western Ontario McMaster Universities Arthritis Index (WOMAC) will be taken for assessing the physical performance and TraumaCaD Software will be used to determine the alignment of the affected limb. In both the groups, conventional physiotherapy treatment will be given for 9 days. Total 9 sessions will be in given in three weeks and in each week 3 sessions will be given on alternative days. The outcome will be measured at baseline. TRIAL REGISTRATION: Clinical Trials Registry – India. (NCT04324931). UNIVERSAL TRIAL NUMBER: U1111-1249-3661. DISCUSSION: To our knowledge this study will be the first to correct the biomechanical axis of knee joints. After Biomechanical Correction, the weight bearing distribution will be adjusted and progression of deformity can be reduced which will help to improve the functional tasks and prevent to undergo early Total Knee Arthroplasty (TKA).

High-strength mechanical joints under combined mechanical and medial loads

This paper introduces a test method for joined hot-dip galvanized steelwork test specimens. The specimens joined by means of a lock bolt system were subjected to a simultaneously combined mechanical and medial loading. This was achieved by combining a vibration testing machine and a condensation chamber that was expanded by an electrolyte dosing unit. The electrolyte was dosed on one side of the specimen in the area around the lock bolt head. The zinc dissolution is locally accelerated in the area around the joining element possibly due to superimposed bimetal and crevice corrosion. In addition, the electrolyte enters the space between the joined steel sheets and initiates corrosion processes there, too. Besides the expected zinc ions, potassium ions were also detected in the collected electrolyte by means of elemental analysis. These are originally part of the friction-increasing coating.

Anatomical pelvic loading of a monoblock polyethylene acetabular component.

Uncemented metal acetabular components show good osseointegration, but material stiffness causes stress shielding and retroacetabular bone loss. Cemented monoblock polyethylene components load more physiologically; however, the cement bone interface can suffer fibrous encapsulation and loosening. It was hypothesized that an uncemented titanium-sintered monoblock polyethylene component may offer the optimum combination of osseointegration and anatomical loading. A total of 38 patients were prospectively enrolled and received an uncemented monoblock polyethylene acetabular (pressfit) component. This single cohort was then retrospectively compared with previously reported randomized cohorts of cemented monoblock (cemented) and trabecular metal (trabecular) acetabular implants. The primary outcome measure was periprosthetic bone density using dual-energy x-ray absorptiometry over two years. Secondary outcomes included radiological and clinical analysis. Although there were differences in the number of males and females in each group, no significant sex bias was noted (p = 0.080). Furthermore, there was no significant difference in age (p = 0.910) or baseline lumbar bone mineral density (BMD) (p = 0.998) found between any of the groups (pressfit, cemented, or trabecular). The pressfit implant initially behaved like the trabecular component with an immediate fall in BMD in the inferior and medial regions, with preserved BMD laterally, suggesting lateral rim loading. However, the pressfit component subsequently showed a reversal in BMD medially with recovery back towards baseline, and a continued rise in lateral BMD. This would suggest that the pressfit component begins to reload the medial bone over time, more akin to the cemented component. Analysis of postoperative radiographs revealed no pressfit component subsidence or movement up to two years postoperatively (100% interobserver reliability). Medial defects seen immediately postoperatively in five cases had completely resolved by two years in four patients. Initially, the uncemented monoblock component behaved similarly to the rigid trabecular metal component with lateral rim loading; however, over two years this changed to more closely resemble the loading pattern of a cemented polyethylene component with increasing medial pelvic loading. This indicates that the uncemented monoblock acetabular component may result in optimized fixation and preservation of retroacetabular bone stock. Cite this article: Bone Joint J2021;103-B(5):872-880.

Sensor Use in Cruciate-Retaining Total Knee Arthroplasty Compared with Posterior-Stabilized Total Knee Arthroplasty: Load Balancing and Posterior Femoral Rollback.

The purpose was to investigate the proportion of severe load imbalance after appropriate conventional gap balancing and analyze the intraoperative kinematics after load balancing in cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasties (TKAs). In total, 45 sensor-assisted CR and 45 PS TKAs using NexGen prosthesis were prospectively evaluated. After appropriate conventional gap balancing, the loads at 10, 45, and 90 degrees of knee flexion were evaluated with a wireless load sensor placed in trial implants. The proportion of severe load imbalance (medial load-lateral load >75 lbs) was investigated. After load balancing, location of the femorotibial contact point was investigated at each flexion angle to analyze femorotibial kinematics. The proportion of the severe load imbalance was significantly higher in CR TKAs at the 10 degrees knee flexion (37.8 vs. 15.6%, p = 0.031). This proportion was higher in CR TKAs than in PS TKAs at the 45 and 90 degrees knee flexion angles, but without statistical significance (31.1 vs. 15.6%, p = 0.134 and 33.3 vs. 15.6%, p = 0.085, respectively). After load balancing, consistent posterior femoral rollback occurred in medial and lateral compartments during 90 degrees flexion in CR TKAs (p < 0.001), but not in PS TKAs. Medial pivot kinematics was not observed in both TKA designs. The sensor was more beneficial in CR TKAs for achieving appropriate load balancing and consistent posterior femoral rollback compared with PS TKAs. Further studies are required to identify target load distribution to restore ideal knee kinematics after TKA. This study shows level of evidence II.

Relationships between tibial acceleration and ground reaction force measures in the medial-lateral and anterior-posterior planes

Peak vertical tibial accelerations during running have shown strong correlations with vertical ground reaction force loading rates and some associations with injury. However, little attention has been given to tibial accelerations along the medial–lateral and anterior-posterior axes. Therefore, our purpose was to examine the correlation between peak tibial accelerations and ground reaction force loading rates in the medial–lateral and posterior directions. Eighteen recreational runners were recruited who ran with a rearfoot strike pattern (10 men/ 8 women, mean age (yrs) = 33 ± 11). Tibial accelerations and ground reaction forces were collected while participants ran on an instrumented treadmill at a self-selected speed. Correlations were developed for: a) peak medial and lateral accelerations with lateral and medial loading rates, respectively, b) peak anterior tibial accelerations and posterior loading rates. Significant correlations were found between tibial accelerations and loading rates in all planes. Peak medial tibial accelerations were correlated with lateral loading rates (Rs = 0.86, p < 0.001) and peak lateral tibial accelerations were correlated with peak medial loading rates (Rs = 0.91, p < 0.001). A lower correlation was found between anterior accelerations and posterior loading rates (Rs = 0.51, p = 0.030). Tibial accelerations in the medial–lateral plane seem to be a valid surrogate for the respective ground reaction force measures during running on a treadmill, explaining 74–83% of the variance in loading rates. However, with only 26% of the variance explained, the same may not be true for anterior tibial accelerations and posterior loading rates.

The correlation between osteoarthritis stage and the effect of the lateral wedge insole for 3 months on medial meniscus extrusion in the knee joint

BackgroundMedial meniscus extrusion (MME) leads to symptomatic knee osteoarthritis (OA) due to increased mechanical stress. MME increases with weight-bearing, and the difference in MME between non-weight-bearing and weight-bearing status (ΔMME) is a factor that causes greater MME. The lateral wedge insole (LWI) is an ideal approach for decreasing the amount of ΔMME associated with the reduction of medial loading stress in the early stage of knee OA. However, the effect of the LWI for 3 months on the ΔMME and its response to OA stage have not been elucidated. ObjectiveTo investigate the effects of the LWI for 3 months on MME and the ΔMME in each stage of OA. MethodsParticipants were divided into three groups: no intervention with the LWI (control group; n = 9) and intervention with the LWI in early OA (early OA group: Kellgren–Lawrence (K/L) stage = 2, n = 17) and late OA (late OA group: K/L stage > 2, n = 13). MME was evaluated using ultrasound, and the ΔMME was obtained as the difference in MME from non-weight-bearing and weight-bearing conditions. These measurements were performed at two time points: the initial office visit as a baseline and post-3 months. ResultsThe weight-bearing MME and ΔMME values post-3 months were significantly decreased compared with those at baseline in the early OA group but not in the control or late OA groups. ConclusionsThe use of the LWI for 3 months decreased weight-bearing MME and ΔMME values, and its effectiveness was more pronounced in the early stage of knee OA.

Raman spectroscopy reveals creep and wear rate of e-beam-sterilized conventional UHMWPE tibial inserts

We measured wear and creep in conventional tibial inserts retrieved after total knee arthroplasty by using Raman spectroscopy. The Raman spectra of thirteen tibial inserts retrieved after total knee arthroplasty with a mean in vivo time of 34.3 months were confocally measured along their bearing subsurface, and then from bearing surface to backside after cutting. The amounts of creep, wear, and wear rate in the medial and lateral load zone were computed from the full-width at half-maximum of a selected Raman band as a characteristic parameter related to strain. In all retrievals, the strain was higher than that of pristine samples at the bearing subsurface, and we observed a correlation between full-width at half-maximum and body weight/body mass index in both load zones. The amount of total penetration, creep, and wear were 0.27 ± 0.21, 0.082 ± 0.031, 0.19 ± 0.18 mm in the medial load zone and 0.22 ± 0.18, 0.080 ± 0.040, 0.14 ± 0.14 mm in the lateral load zone, respectively. The amount of wear in both load zones was strongly correlated with the in vivo time. The wear rate in eleven retrievals excluding an extremely short excised sample was 0.055 ± 0.020 mm/year in the medial load zone and 0.041 ± 0.020 mm/year in the lateral load zone. Raman spectroscopy proved very useful in separating creep and wear components of thickness reduction, thus revealing the wear rate of the UHMWPE material.

A Cadaveric Load Analysis of the Supramalleolar Osteotomy In The Setting of an Osteochondral Pseudolesion: Quantifying Chondral Off-loading

Category:Ankle, Ankle ArthritisIntroduction/Purpose:The supramalleolar osteotomy (SMO) serves as a means to alter joint load transmission and shield damaged areas of cartilage within the tibiotalar joint. The aim of this study was to directly measure the changes in pressure attributed to varying degrees of SMOs (varus and valgus); with and without an osteochondral (OCD) pseudolesion, and in multiple ankle alignments (Dorsiflexion, neutral, and plantarflexion). We hypothesize measurement metrics to be reduced with increasing degrees of SMO.Methods:6 cadaver specimens were in included in the biomechanical study (sectioned at the mid-tibia). A pressure sensor was used to measure load, load area, and peak pressure within the tibiotalar joint. SMOs of 3,6,9, and 12 degrees in varus or valgus were performed. A servohydraulic machine was used to transmit 400 and 800 N through the specimens; in 10 degrees of dorsiflexion, neutral, or in 10 degrees of plantarflexion during load transmission. Measurements were performed in undisturbed joints, followed by re-measurement in the presence of a created 9 mm diameter pseudolesion.Results:Load was not changed (only significant changes reported) in the presence of a lesion. For the load, it was more influenceable at 800 N, changes were observed in higher degree SMOs, and changes were only observed in neutral and dorsiflexion. Changes in area were only observed when 12 degrees of varus or valgus SMOs were used. Peak Pressure was the only modifiable metric in the presence of a pseudo-lesion, reductions were more common at 800 N, and in the absence of a pseudolesion there was an incremental reduction in medial peak pressure when increasing varus SMOs were performed (dorsiflexion).Conclusion:Medial peak pressure tended to decrease with varus SMOs in neutral and dorsiflexion. Medial load tended to decrease with varus osteotomies in 10 degrees of dorsiflexion. A 12 degree varus SMO was the only SMO to influence a pseudolesion.

Load imbalances existed as determined by a sensor after conventional gap balancing with a tensiometer in total knee arthroplasty.

To evaluate intercompartmental load intraoperatively with a sensor after conventional gap balancing with a tensiometer during total knee arthroplasty (TKA). Fifty sensor-assisted TKA procedures were performed prospectively between August and September 2018 with a cruciate-retaining prosthesis. After applying a modified measured resection technique, conventional balancing between resected surfaces was achieved. The equal and rectangular flexion-extension gaps were confirmed using a tensiometer at 90° and 5°-7° (due to posterior tibial slope) of knee flexion. Then, the load distribution was evaluated intraoperatively with a sensor placed on trial implants in the positions of knee flexion (90° flexion) and extension (10° flexion). The proportion of coronal load imbalance (medial load - lateral load ≥ ± 15lb) was 56% in extension and 32% in flexion (p = 0.023). The proportion of sagittal load imbalance (extension load - flexion load ≥ ± 15lb) was 36% in the medial compartment and 4% in the lateral compartment (p < 0.001). An additional procedure for load balancing was performed in 74% of knees. Coronal and sagittal load imbalances existed as determined by the sensor even after the achievement of appropriate conventional gap balance. The additional rebalancing procedure was performed for balanced loads in 74% of the knees after conventional balancing. The use of an intraoperative load sensor offers the advantage of direct evaluation of the load on TKA implants. IV.