Are the kinematics of the knee joint altered during the loading response phase of gait in individuals with concurrent knee osteoarthritis and complaints of joint instability? A dynamic stereo X-ray study

Asymmetric gap balancing improves knee kinematic following primary total knee arthroplasty

PURPOSE

The purpose of this study was to demonstrate closer-to-normal knee kinematics following primary total knee arthroplasty (TKA) performed establishing asymmetric gap balancing intraoperatively.

MATERIAL AND METHOD

Two age-, sex-, BMI-matched groups of patients underwent medially stabilized TKA because of isolated knee disease. Group A (12 patients) underwent "unrestricted" kinematic alignment (uKA) according to Howell while group B (15 patients) received robot-assisted "simplified" KA (sKA) with an alignment goal (Hip-Knee-Ankle axis-HKA) ± 5° respect to the mechanical axis. Intraoperatively, in group B, the flexion gap at 90° was first set at an average of 1.5 mm (0-5 mm; SD 4.4 mm) tighter in the medial compartment with respect to the lateral; in the same way, the extension gap was then set at an average of 2.0 mm (0-4.5 mm; SD 3.1 mm) tighter in the medial compartment with respect to the lateral. All patients, including a non-arthritic cohort (group C: 5 controls) underwent gait analysis using an instrumented treadmill (WalkerView-WV) equipped with an instrumented belt armed with a 3D video camera. The WV software evaluated multiple spatiotemporal and kinematic parameters, including: (1) contact time (s); (2) knee ROM during gait cycle; (3) step length percentage with respect to total gait (%) and pure step length (cm). Statistical analyses included t-Test and ANOVA and were conducted by using SPSS.

RESULTS

At the final FU, significant differences were noted during gait between the two TKA groups (uKA-sKA) and the controls. Both TKA groups showed superior mean contact time on the surgical knee (uKA 1 s; sKA 0.97 s) as compared to the controls (0.72 s) (P = 0.002) while no differences were found between them (P = 0.11). TKA groups showed a lower, maximum ROM in the surgical knee (mean uKA 36º; mean sKA 49º) relative to the controls (mean 57º) (P < 0.05) but a statistical difference was found between them (P = 0.003). Both TKA groups showed a higher step length percentage with respect to the total gait and a shorter step length on the surgical side (uKA: mean 8.28% and mean step length 35.5 cm; sKA: mean 8.38% and mean step length 34.6 cm) in comparison to the controls (mean 3.38%; mean step length 71.4 cm) (P < 0.05) while no statistical differences were found between them.

CONCLUSION

To our knowledge, this was the first study to exhibit the kinematic advantages of a slightly asymmetric gap balancing during KA TKA. Combining a medially-stabilized implant design and a surgical technique aiming to obtain a tighter medial compartment represents a promising approach to improve outcomes after TKA.

Three-dimensional volume and shape of the infrapatellar fat pad during quasi-static knee extension from 30° to 0°: comparisons of patients with osteoarthritic knees and young, healthy individuals

[Purpose] Previous studies suggest that the infrapatellar-fat-pad is affected by aging or knee osteoarthritis, and that the infrapatellar-fat-pad in knee osteoarthritis cases may be associated with limited mobility during knee movement. This study aimed to determine changes in the shape and volume of the infrapatellar-fat-pad between 30° and 0° of knee extension in knee osteoarthritis cases and in young, healthy individuals, and to characterize differences in patellar mobility, patellar tendon mobility, and length between the groups. [Participants and Methods] We created 3D models of the infrapatellar-fat-pad, the patellar tendon, and bones using sagittal MRI with the knee at 30° and 0°. The following four parameters were determined: (1) movement of the infrapatellar-fat-pad; (2) infrapatellar-fat-pad volume; (3) angle and surface length of the patellar tendon; and (4) patellar movement. [Results] Compared with the knee osteoarthritis group, the healthy group showed (1) reduced anterior movement of the infrapatellar-fat-pad; (2) smaller volume changes only in the infero-postero-lateral portion; and (3) no changes in the angle of the patellar tendon to the tibial plateau between 30° to 0°. [Conclusion] In conclusion, between 30° and 0°, (1) the infrapatellar-fat-pad in patients with knee osteoarthritis exhibited less anterior movement, and (2) the patellar tendon angle was diminished in patients with knee osteoarthritis compared with those of young-healthy knees.

Medial congruent polyethylene design show different tibiofemoral kinematics and enhanced congruency compared to a standard symmetrical cruciate retaining design for total knee arthroplasty-an in vivo randomized controlled study of gait using dynamic radiostereometry

PURPOSE

New total knee arthroplasty implant designs attempt to normalize kinematics patterns that may improve functional performance and patient satisfaction. It was hypothesized that a more medial congruent (MC) anatomic bearing design (1) influences the tibiofemoral kinematics and (2) enhances articular congruency compared to a standard symmetrical cruciate retaining (CR) bearing design.

METHODS

In this double-blinded randomized study, 66 patients with knee osteoarthritis were randomly included in two groups: MC (n = 31) and CR (n = 33). Clinical characteristics such as knee ligament lesions and knee osteoarthritis scores were graded on preoperative magnetic resonance imaging and radiography. At the 1-year follow-up, dynamic radiostereometric analysis was used to assess tibiofemoral joint kinematics and articulation congruency. Patient-reported outcome measures, Oxford Knee Score, the Forgotten Joint Score, and the Knee Osteoarthritis Outcome Score, were assessed preoperatively and at the 1-year follow-up.

RESULTS

Compared to the CR bearing, the MC bearing displayed an offset with approximately 3 mm greater anterior tibial drawer (p < 0.001) during the entire motion, and up to approximately 3.5 degrees more tibial external rotation (p = 0.004) from mid-swing to the end of the gait cycle at the 1-year follow-up. Furthermore, the congruency area in the joint articulation was larger during approximately 80% of the gait cycle for the MC bearing compared to the CR. The patient-reported outcome measures improved (p < 0.001), but there were no differences between groups. In addition, there were no differences in clinical characteristics and there were no knee revisions or recognized deep infections during follow-up.

CONCLUSION

The study demonstrates that the MC-bearing design changes tibiofemoral kinematics and increases the area of congruency towards more native knee kinematics than the CR bearing. In perspective this may contribute to a more stabilized knee motion, restoring the patient's confidence in knee function during daily activities.

The coronal inclination of the medial tibial plateau affects coronal gait kinematics for varus osteoarthritic knees

PURPOSE

This study aims to (1) measure the kinematics of lower extremity alignment and the bony position relative to the ground during walking, focusing on the coronal plane, and (2) determine the correlation between the kinematics and coronal inclination of the medial tibial plateau (coronal inclination) for healthy and varus knee osteoarthritis (OA).

METHODS

In this study, 43 women (non-OA, 9 knees; early OA, 13 knees; advanced OA, 21 knees; mean age 58 ± 17 years) were examined. The knee phenotypes in varus knee OA were varied. Three-dimensional (3D) knee kinematics were calculated in gait analysis by combining the motion capture system and the 3D lower extremity alignment assessment system via biplanar long-leg X-rays, applying the 3D-2D registration technique. The main parameters were the kinematics of the bony axes relative to the ground in the coronal plane during the stance phase of the gait. The differences in overall kinematics were assessed using repeated measures ANOVA with Tukey's post hoc test. The association between kinematic parameters and coronal inclination was evaluated by multiple linear regression after univariate analysis.

RESULTS

The tibia tilted laterally during the loading response, and a plateau area subsequently appeared until the terminal stance phase, whereas the femur slowly tilted laterally until the terminal stance phase. The dynamic alignment showed a relatively large varus angular change during the loading response in all groups. The trend of motion was similar among all groups (p = n.s.), although to varying degrees. The coronal inclination was the more dominant factor than the Kellgren-Lawrence (K-L) grades (β =  - 0.423, p = 0.005) when the change in dynamic alignment was determined.

CONCLUSIONS

The TAA plateau area after the loading response implies that the tibial articular surface may become horizontal. The femur slowly tilted laterally until the terminal stance phase in response to the tibial motion. Consequently, the dynamic alignment showed a varus angular change, in which coronal MCT was more involved than K-L grades.

Patients with knee osteoarthritis can be divided into subgroups based on tibiofemoral joint kinematics of gait - an exploratory and dynamic radiostereometric study

OBJECTIVE

Patients with advanced knee osteoarthritis (KOA) frequently alter their gait patterns in an attempt to alleviate symptoms. Understanding the underlying pathomechanics and identifying KOA phenotypes are essential to improve treatments. We investigated kinematics in patients with KOA to identify subgroups of homogeneous knee joint kinematics.

METHOD

A total of 66 patients with symptomatic KOA scheduled for total knee arthroplasty and 15 age-matched healthy volunteers with asymptomatic, non-arthritic knees were included. We used k-means clustering to divide patients into subgroups based on dynamic radiostereometry-assessed tibiofemoral joint kinematics. Clinical characteristics such as knee ligament lesions and KOA scores were graded by magnetic resonance imaging and radiographs, respectively.

RESULTS

We identified four clusters that were supported by clinical characteristics. The flexion group (n = 20) consisted primarily of patients with medial KOA. The abduction group (n = 17) consisted primarily of patients with lateral KOA. The anterior draw group (n = 10) was composed of patients with medial KOA, some degree of anterior cruciate ligament lesion and the highest KOA score. The external rotation group (n = 19) primarily included patients with medial collateral and posterior cruciate ligament lesions.

CONCLUSION

Based on tibiofemoral gait patterns, patients with advanced KOA can be divided into four subgroups with specific clinical characteristics and different KOA-affected compartments. The findings add to our understanding of how knee kinematics may affect the patient's development of different types of KOA. This may inspire improved and more patient-specific treatment strategies in the future.

Functional Evaluation of a Personalized Orthosis for Knee Osteoarthritis: A Motion Capture Analysis

Orthotic treatments for knee osteoarthritis (OA) typically rely on simple mechanisms such as three-point bending straps and single-pin hinges. These commonly prescribed braces cannot treat bicompartmental knee OA, do not consider the muscle weakness that typically accompanies the condition, and employ hinges that restrict the knee's natural biomechanics. Utilizing a novel, personalized joint mechanism in conjunction with magnetorheological dampers, we have developed and evaluated a brace which attempts to address these shortcomings. This process has respected three principal design goals: reducing the load experienced across the entire knee joint, generating a supportive moment to aid the thigh muscles in shock absorption, and interfering minimally with gait kinematics. Two healthy volunteers were chosen to test the system's basic functionality through gait analysis in a motion capture laboratory. Combining the collected kinematic and force-plate data with data taken from sensors onboard the brace, we integrated the brace and leg system into a single inverse dynamics analysis, from which we were able to evaluate the effect of the brace design on the subjects' knee loads and moments. Of the three design goals: a reduction in knee contact forces was demonstrated; increased shock absorption was observed, but not to statistical significance; and natural gait was largely preserved. Taken in total, the outcome of this study supports additional investigation into the system's clinical effectiveness, and suggests that further refinement of the techniques presented in this paper could open the doors to more effective OA treatment through patient specific braces.

Dispersion of knee helical axes during walking in young and elderly healthy subjects

Knee joint rotation center displacement can be estimated in vivo through the analysis of helical axis (HAs) dispersion. HAs can be analyzed during walking, providing information on joint stability. The study aim was to describe knee HAs dispersion during walking in dominant and non-dominant legs of young and elderly healthy subjects. Twenty young (YG: age 23.3 ± 2.4 years) and twenty elderly (EG: age 69.3 ± 4.6 years) healthy subjects were asked to walk on a treadmill at a self-selected speed with reflective markers placed bilaterally on thighs and shanks to detect HAs dispersion and knee kinematics with an optoelectronic system. HAs dispersion was described during the following four phases of gait cycle: (1) flexion from 95% of the previous gait cycle to 10% of the subsequent gait cycle, (2) extension from 10% to 40%, (3) flexion from 40% to 75% and (4) extension from 75% to 95% of the gait cycle. Mean Distance (MD) and Mean Angle (MA) were used as HAs dispersion indexes during each gait phase. Participants showed greater MD and MA in sagittal and frontal planes during the first and second phases. EG revealed higher MD (p = 0.001) and MA (p < 0.001) during the first phase and higher MA (p = 0.001) during the fourth phase in both dominant and non-dominant legs on the sagittal plane. HAs dispersion could be related to the amount of forces acting on knee (first two phases) and knee degeneration (elderly). These results may be used as reference data in further studies on HAs dispersion in presence of knee pathologies or after knee surgery or rehabilitation.

Tibio-femoral kinematics of the healthy knee joint throughout complete cycles of gait activities

Accurate assessment of 3D tibio-femoral kinematics is essential for understanding knee joint functionality, but also provides a basis for assessing joint pathologies and the efficacy of musculoskeletal interventions. Until now, however, the assessment of functional kinematics in healthy knees has been mostly restricted to the loaded stance phase of gait, and level walking only, but the most critical conditions for the surrounding soft tissues are known to occur during high-flexion activities. This study aimed to determine the ranges of tibio-femoral rotation and condylar translation as well as provide evidence on the location of the centre of rotation during multiple complete cycles of different gait activities. Based on radiographic images captured using moving fluoroscopy in ten healthy subjects during multiple cycles of level walking, downhill walking and stair descent, 3D femoral and tibial poses were reconstructed to provide a comprehensive description of tibio-femoral kinematics. Despite a significant increase in joint flexion, the condylar antero-posterior range of motion remained comparable across all activities, with mean translations of 6.3-8.3 mm and 7.3-9.3 mm for the medial and lateral condyles respectively. Only the swing phase of level walking and stair descent exhibited a significantly greater range of motion for the lateral over the medial compartment. Although intra-subject variability was low, considerable differences in joint kinematics were observed between subjects. The observed subject-specific movement patterns indicate that accurate assessment of individual pre-operative kinematics together with individual implant selection and/or surgical implantation decisions might be necessary before further improvement to joint replacement outcome can be achieved.

Association between stages of medial compartment osteoarthritis and three-dimensional knee alignment in the supine position: A cross-sectional study

BACKGROUND

Osteoarthritis (OA) of the knee causes changes in knee alignment. A detailed knowledge of knee alignment is needed for correct assessment of the extent of disease progression, determination of treatment strategy, and confirmation of treatment effectiveness. However, deterioration of knee alignment during progression of OA has not been adequately characterized. The aims of this study were to clarify the changes in three-dimensional static knee alignment as knee OA stage progressed and to lay a foundation for an optimal treatment strategy to prevent knee malalignment.

METHODS

A total of 106 knees of 81 patients ((men/women) 45/36; mean age 48.4 ± 19.9 years; body mass index (BMI) 25.7 ± 4.4 kg/m²) were enrolled in this cross-sectional study, comprising 34 (33/1) in Kellgren-Lawrence (KL) grade 0, 17 (8/9) in KL grade 1, 26 (5/21) in KL grade 2, 19 (4/15) in KL grade 3, and 10 (1/9) in KL grade 4. In all cases, computed tomography images were obtained with the subject in a reclined and relaxed position with the knee straight. Three-dimensional bone models were created from the images and knee alignment was calculated with six degrees-of-freedom. Then, 40 knees were selected consisting of 10 sex- and BMI-matched knees from each KL grade group: KL grade 1 (mean age 54.6 ± 8.4 years; BMI 23.3 ± 3.5 kg/m²), grade 2 (64.7 ± 10.9 years; 27.3 ± 3.2 kg/m²), grade 3 (69.2 ± 11.4 years; 27.1 ± 4.3 kg/m²), and grade 4 (71.9 ± 9.2 years; 27.2 ± 3.6 kg/m²). The Mann-Whitney U test with Bonferroni correction for multiple comparisons was used to analyze static alignment (α < 0.05/6).

RESULTS

Alignment of the knee in flexion was -4.0 [95% confidence interval (CI): -6.4, -1.5] degrees, -3.4 [-8.0, 1.3] degrees, -0.1 [-3.7, 3.5] degrees, and 0.4 [-0.9, 1.6] degrees in the order of KL grade 1 to 4. There were significant differences between KL grade 1 and 4 (p = 0.0081). Anterior tibial translation was 6.6 [4.6, 8.6] mm, 5.8 [1.9, 9.7] mm, 1.0 [-2.5, 4.5] mm, and 1.3 [-2.4, 5.1] mm in the order of grade 1 to 4. There were significant differences between KL grade 1 and 4 (p = 0.0081). There were no significant differences in lateral tibial translation nor tibial rotation.

CONCLUSIONS

The severely osteoarthritic knee joint was flexed and the tibia was displaced posteriorly with respect to the femur. Preventing these changes in alignment would assist in the prevention and treatment of knee OA.

The effectiveness of foot orthoses in the treatment of medial knee osteoarthritis: A systematic review

BACKGROUND

Knee osteoarthritis is a disease of the joint causing decreased function and pain. Currently, treatments range from medication to surgery, with the use of different insoles and footwear recommended. These methods are effective by either correcting the position of the knee or providing shock absorption. However, there is little understanding of the effective characteristics of these devices.

RESEARCH QUESTION

This paper aims to investigate this question and provide future areas of research to help better define treatment guidelines. Foot orthoses are an example of non-pharmacological conservative treatments mentioned in National Institute for Health and Care Excellence (NICE) guidelines to treat knee osteoarthritis (OA). These include lateral wedge insoles (LWI), developed with the intention of load reduction of the knee. Different footwear has also been shown to affect pain, biomechanical and functional outcomes in knee OA patients.

METHODS

To address what features of LWIs and footwear make them effective in the treatment of knee OA, scientific databases were used to search for papers on this topic and then selected to be included based on pre-defined criteria. Data were extracted and analysed from these studies to provide a basis for possible areas for future development of these foot orthoses, and research required to improve clinical treatment guidelines. Databases used were PubMed, Scopus and Web of Science.

RESULTS AND SIGNIFICANCE

Thirty-four out of 226 papers were included after application of inclusion and exclusion criteria. Regarding LWIs, the characteristics showing the most beneficial effect on either biomechanical, functional or pain outcomes were customisation, full-length, 5° elevation, shock absorption and arch support. For footwear, barefoot mimicking soles produced the most favourable biomechanics. Results also showed that insoles work in correcting the position of the knee, but it may or may not affect patients' pain and function.

Effect of altered sagittal-plane knee kinematics on loading during the early stance phase of gait

BACKGROUND

Individuals with knee osteoarthritis (OA) show various dynamic sagittal-plane changes during the early stance phase of gait. However, the effect of these kinematic alterations on knee load during the early stance remains poorly understood.

RESEARCH QUESTION

The purpose of this study was to examine the effect of altered sagittal- plane knee kinematics on knee load during the early stance.

METHODS

A total of 13 healthy adult men underwent gait analysis trials using four conditions (baseline and three altered conditions). The three altered conditions were defined as follows: 1) Less flexion (LF): a gait that decreased knee flexion excursion (KFE) owing to a reduced peak knee flexion angle compared to baseline. 2) Initial flexion (IF): a gait with decreased KFE owing to an increased knee flexion angle at initial contact, during which the peak knee flexion angle did not differ from baseline. 3) Flexion gait (FG): a gait that increased the knee flexion angle at initial contact but did not reduce KFE compared with the baseline. Data analyzed included peak external knee flexion moment (KFM), KFM impulse (impulse was an integral value from initial contact to peak value), peak vertical ground reaction force (VGRF), and maximum loading rate.

RESULTS

Both LF and IF conditions significantly decreased peak VGRF (p < 0.05) compared with the baseline. Peak KFM decreased in the LF condition and increased in the FG condition versus baseline (p < 0.05). A significantly increased KFM impulse was found in both IF and FG conditions when compared with baseline (p < 0.05).

SIGNIFICANCE

An increase in knee flexion angle during early stance increased knee loading. Interventions are likely required for improving excessive knee flexion during early stance phase of gait in individuals with knee OA.

Development and Assessment of a Microcomputed Tomography Compatible Five Degrees-of-Freedom Knee Joint Motion Simulator

Currently available knee joint kinematic tracking systems fail to nondestructively capture the subtle variation in joint and soft tissue kinematics that occur in native, injured, and reconstructed joint states. Microcomputed tomography (CT) imaging has the potential as a noninvasive, high-resolution kinematic tracking system, but no dynamic simulators exist to take advantage of this. The purpose of this work was to develop and assess a novel micro-CT compatible knee joint simulator to quantify the knee joint's kinematic and kinetic response to clinically (e.g., pivot shift test) and functionally (e.g., gait) relevant loading. The simulator applies closed-loop, load control over four degrees-of-freedom (DOF) (internal/external rotation, varus/valgus rotation, anterior/posterior translation, and compression/distraction), and static control over a fifth degree-of-freedom (flexion/extension). Simulator accuracy (e.g., load error) and repeatability (e.g., coefficient of variation) were assessed with a cylindrical rubber tubing structure and a human cadaveric knee joint by applying clinically and functionally relevant loads along all active axes. Micro-CT images acquired of the joint at a loaded state were then used to calculate joint kinematics. The simulator loaded both the rubber tubing and the cadaveric specimen to within 0.1% of the load target, with an intertrial coefficient of variation below 0.1% for all clinically relevant loading protocols. The resultant kinematics calculated from the acquired images agreed with previously published values, and produced errors of 1.66 mm, 0.90 mm, 4.41 deg, and 1.60 deg with respect to anterior translation, compression, internal rotation, and valgus rotation, respectively. All images were free of artifacts and showed knee joint displacements in response to clinically and functionally loading with isotropic CT image voxel spacing of 0.15 mm. The results of this study demonstrate that the joint-motion simulator is capable of applying accurate, clinically and functionally relevant loads to cadaveric knee joints, concurrent with micro-CT imaging. Nondestructive tracking of bony landmarks allows for the precise calculation of joint kinematics with less error than traditional optical tracking systems.

Objective parameters to measure (in)stability of the knee joint during gait: A review of literature

BACKGROUND

Instability of the knee joint during gait is frequently reported by patients with knee osteoarthritis or an anterior cruciate ligament rupture. The assessment of instability in clinical practice and clinical research studies mainly relies on self-reporting. Alternatively, parameters measured with gait analysis have been explored as suitable objective indicators of dynamic knee (in)stability.

RESEARCH QUESTION

This literature review aimed to establish an inventory of objective parameters of knee stability during gait.

METHODS

Five electronic databases (Pubmed, Embase, Cochrane, Cinahl and SPORTDiscuss) were systematically searched, with keywords concerning knee, stability and gait. Eligible studies used an objective parameter(s) to assess knee (in)stability during gait, being stated in the introduction or methods section. Out of 10717 studies, 89 studies were considered eligible.

RESULTS

Fourteen different patient populations were investigated with kinematic, kinetic and/or electromyography measurements during (challenged) gait. Thirty-three possible objective parameters were identified for knee stability, of which the majority was based on kinematic (14 parameters) or electromyography (12 parameters) measurements. Thirty-nine studies used challenged gait (i.e. external perturbations, downhill walking) to provoke knee joint instability. Limited or conflicting results were reported on the validity of the 33 parameters.

SIGNIFICANCE

In conclusion, a large number of different candidates for an objective knee stability gait parameter were found in literature, all without compelling evidence. A clear conceptual definition for dynamic knee joint stability is lacking, for which we suggest : "The capacity to respond to a challenge during gait within the natural boundaries of the knee". Furthermore biomechanical gait laboratory protocols should be harmonized, to enable future developments on clinically relevant measure(s) of knee stability during gait.

The assessment of instability in the osteoarthritic knee

Patient-reported instability is a common complaint amongst those with knee arthritis.

Much research has examined the assessment of self-reported instability in the knee; however, no definitive quantitative measure of instability has been developed.

This review focuses on the current literature investigating the nature of self-reported instability in the arthritic knee and discusses the possibilities of further investigation.

Cite this article: EFORT Open Rev 2019;4:70-76. DOI: 10.1302/2058-5241.4.170079

Analysis of Kneeling by Medical Imaging Shows the Femur Moves Back to the Posterior Rim of the Tibial Plateau, Prompting Review of the Concave-Convex Rule

BACKGROUND

Physical therapists assess joint movement by observation and palpation. New imaging technologies that enable vision of bones and joints during functional activities can be used to analyze joint kinematics and review traditional assumptions.

PURPOSE

The purpose was to measure relations between flexion, rotation, and translation at the knee and to validate these visually.

DESIGN

This was a prospective, observational study.

METHODS

Twenty-five healthy participants aged >45 years (13 males) knelt from upright kneeling to full flexion with the foot free. Fluoroscopy recorded movement at 30 frames per second of x-ray. A computed tomography scan provided 3-dimensional data, which were registered to the fluoroscopy frames to provide a moving model. Motion in 6 degrees of freedom was analyzed for coupling of movements.

RESULTS

Mean (standard deviation) flexion reached by participants was 142 (6)° in kneeling. Posterior femoral translation was coupled to flexion (r = 0.96). From 90° to 150° flexion, the femur translated posteriorly by 36 (3) mm to finish 23 (3) mm posterior to the center of the tibia at 150° flexion. From 90° to 150° flexion, the femur externally rotated from 8 (6)° to 16 (5)°. Flexion was coupled to rotation (r = 0.47). Abduction was <3° and lateral translation was <3 mm. Visually, the femur appeared to translate posteriorly until the femoral condyles rested on the posterior rim of the tibial plateau with concurrent external rotation so that the popliteal fossa aligned with the posterior margin of the medial tibial plateau.

LIMITATIONS

A limitation of the study is that knee flexion can include squat and lunge as well as kneeling.

CONCLUSION

Deep flexion requires femoral posterior translation and external rotation. These findings invite review of the concave-convex rule as it might apply to manual therapy of the knee.

Quantification of joint alignment and stability during a single leg stance task in a knee osteoarthritis cohort

BACKGROUND

Knee osteoarthritis alters joint stability but its kinematics during functional weight-bearing tasks remain unclear. We propose and validate an assessment technique for the quantification of knee alignment and stability in patients during a short single leg stance task.

METHODS

Three-dimensional knee kinematics were acquired non-invasively from 31 knee osteoarthritis patients (subdivided as moderate or severe) and 15 asymptomatic individuals during six short single-leg stance tasks. Data of participants achieving ≥3 trials were retained. From flexion-extension signals, a data treatment method compared the average between-trial root-mean-square error (RMSE) across trial triplets, and the average within-trial range of movement (RoM) for two data windows. From secondary knee motions (ab/adduction and int/external rotations, anteroposterior and mediolateral translations), we extracted measures characterizing alignments (mean), largest deviations (maximum, minimum), and extent of micro-adjustments (RoM, length of knee excursion). Their sensitivity to disease and severity was determined using an ANOVA, and between-trial repeatability using ICC_2,3.

RESULTS

Ninety-four percent of patients achieved ≥3 trials. The retained trial triplet and window reduced the RMSE (2.15 to 1.54) and RoM (4.9° to 1.77°) for flexion-extension. Mean, minimum, and maximum measures were sensitive to disease for anteroposterior translations, and to severity for ab/adduction (P < 0.05). High repeatability was found for those measures (ICC ≥0.84). RoM and length of knee excursion, although sensitive to disease for anteroposterior translations, had lower ICC.

CONCLUSION

The proposed technique is feasible and exposed measures of knee alignment sensitive to knee osteoarthritis, for instance, an anterior femoral shift and an increased adduction malalignment with greater severity.

Self-reported Instability in Knee Osteoarthritis: A Scoping Review of Literature

BACKGROUND

Knee Osteoarthritis (OA) is a disabling musculoskeletal condition among the elderly. Self-reported instability is one of the impairments associated with osteoarthritis. A complete understanding of the self-reported instability in knee OA is essential, to identify the best strategies for overcoming this impairment. The focus of this scoping review is to provide an overview of evidence supported information about the prevalence and other associated features of selfreported instability in Knee OA. A broad search of the database PubMed with keywords such as knee osteoarthritis and instability resulted in 1075 articles. After title abstract and full-text screening, 19 relevant articles are described in the review. Overall, there is less amount of published literature on this topic. Studies reported prevalence rates of more than 60% for self-reported instability in knee osteoarthritis, which causes functional deterioration and high fear of falls. The most probable causative factors for self-reported instability in knee OA were altered sensory mechanisms and decreased muscle strength.

CONCLUSION

To conclude, self-reported knee instability in knee OA requires thorough evaluation and directed treatment with further studies providing rationalistic evidence-based management strategies. The current literature regarding self-reported knee instability is summarized, highlighting the research gaps.

Effects of Salvia miltiorrhiza extract with supplemental liquefied calcium on osteoporosis in calcium-deficient ovariectomized mice

Background

Extracts from Salvia miltiorrhiza Bunge have been used in traditional Asian medicine to treat coronary heart disease, chronic renal failure, atherosclerosis, myocardial infraction, angina pectoris, myocardial ischemia, dysmenorrheal, neurasthenic insomnia, liver fibrosis and cirrhosis. The aim of the study was to investigate the anti-RANK signal effect of the combination of S.miltiorrhiza Bunge (SME) and liquefied calcium (LCa) supplement with ovariectomized (OVX-SML) mice, a osteoporosis animal model. Results were compared to 17β-estradiol (E₂) treatment.

Methods

A total of 70 female ICR strain mice (7 weeks) were randomly divided into 10 groups with 7 mice in each group as follows: (1) sham-operated control mice (sham) received daily oral phosphate-buffered-saline (PBS) of equal volumes through oral administration. (2) OVX mice received a daily oral administration of PBS (OVX). (3) OVX mice treated daily with 50 mg/kg b.w./ day of SME (4) with 100 mg/kg b.w./day of SME or (5) with 200 mg/kg b.w./day of SME via oral administration. (6) OVX mice treated daily with 50 mg/kg b.w./day of SML (7) with 100 mg/kg b.w./day of SML or (8) with 200 mg/kg b.w./day of SML via oral administration. (9) OVX mice treated daily with 10 ml/kg b.w./day of LCa (10) OVX mice received i.p. injections of 17β-estradiol (E₂) (0.1 mg/kg b.w./day) three times per week for 12 weeks.

Results

micro-CT analysis revealed that oral administration of SML inhibited tibial bone loss, sustained trabecular bone state, and ameliorated bone biochemical markers. In addition, SML administration compared to SEM and LCa reduced serum levels of RANKL, osteocalcin and BALP through increased serum levels of OPG and E₂ in OVX mice. SML also had more beneficial effects on protection of estrogen-dependent bone loss through blocking expression of TRAF6 and NFTAc1 and produces cathepsin K and calcitonin receptor to develop osteoclast differentiation.

Conclusion

These data suggest that S. miltiorrhiza Bunge combined with liquefied calcium supplement has an inhibitory activity in OVX mice. This result implies the possibility of a pharmacological intervention specifically directed toward a disease such as osteoporosis where decreased bone strength increases the risk of a broken bone.

Electronic supplementary material

The online version of this article (10.1186/s12906-017-2047-y) contains supplementary material, which is available to authorized users.

Wnt10b and Dkk-1 gene therapy differentially influenced trabecular bone architecture, soft tissue integrity, and osteophytosis in a skeletally mature rat model of osteoarthritis

AIMS

Our goals in the current experiments were to determine if (a) upregulation of Wnt signaling would induce osteoarthritis changes in stable stifle joints and (b) if downregulation of Wnt signaling in destabilized joints would influence the progression of OA.

METHODS

At 37 weeks of age, rats were injected in the stifle joint with a recombinant adeno-associated viral vector containing the Wnt-inhibitor Dkk-1 or a Wnt10b transgene. At 40 weeks of age, rats underwent surgical destabilization of the joint. At 50 weeks of age, stifle joints were submitted for micro-computed tomography and histopathological analysis.

RESULTS

Injection of either Wnt10b or Dkk-1 transgenes in stable joints improved bone architectural parameters, but worsened soft tissue integrity. Osteophytosis was decreased by Dkk-1, but unchanged by Wnt10b. Destabilization negatively influenced bone architecture, increased osteophytosis, and decreased soft tissue integrity. Dkk-1 exacerbated the negative effects of destabilization, whereas Wnt10b had little effect on these parameters. Osteophytosis was improved, whereas soft tissue integrity was worsened by both transgenes in destabilized joints.

CONCLUSIONS

The Wnt-inhibitor Dkk-1 does not appear to completely inhibit the effects of Wnt signaling on bone remodeling. In vivo upregulation of Wnt10b and its inhibitor, Dkk-1, can produce both parallel or contrasting phenotypic responses depending on the specific parameter measured and the fidelity of the examined joint. These observations elucidate different roles for Wnt signaling in stable versus destabilized joints and may help to explain the conflicting results previously reported for the role of Dkk-1 in joint disease.

Relationship between Kellgren-Lawrence score and 3D kinematic gait analysis of patients with medial knee osteoarthritis using a new gait system

Knee osteoarthritis (KOA) is reported to have characteristic kinematics during walking. However, the relationship between Kellgren-Lawrence (K/L) score and the 3D kinematic gait of patients with medial KOA remains unclear. Here, ninety-seven patients with medial KOA and thirty-eight asymptomatic participants were involved. Patients with medial KOA were divided into early, moderate, and severe KOA based on the K/L score. Through kinematic gait analysis, we found a relationship between K/L score and 3D kinematic gait for patients. All KOA knees had a significantly reduced range of motion. As the K/L score was increasing, the knee flexion at the heel strike and 50% of the stance phase increased while the peak knee flexion in the swing phase decreased. In addition, the adduction and femoral rotation increased internally at the heel strike, 50% of the stance phase, and maximum angle of the swing phase. Femoral translation increased anteriorly and distally at the heel strike and 50% of the stance phase. The severe group had more medial translation than the asymptomatic groups. Significant alterations of three-dimensional joint kinematics were identified in subjects suffering various severities in Chinese patients. This study provides an important reference for the treatment options, therapy assessment, and rehabilitation of KOA.

Kinematics of the Normal Knee during Dynamic Activities: A Synthesis of Data from Intracortical Pins and Biplane Imaging

Few studies have provided in vivo tibiofemoral kinematics of the normal knee during dynamic weight-bearing activities. Indeed, gold standard measurement methods (i.e., intracortical pins and biplane imaging) raise ethical and experimental issues. Moreover, the conventions used for the processing of the kinematics show large inconsistencies. This study aims at synthesising the tibiofemoral kinematics measured with gold standard measurement methods. Published kinematic data were transformed in the standard recommended by the International Society of Biomechanics (ISB), and a clustering method was applied to investigate whether the couplings between the degrees of freedom (DoFs) are consistent among the different activities and measurement methods. The synthesised couplings between the DoFs during knee flexion (from 4° of extension to −61° of flexion) included abduction (up to −10°); internal rotation (up to 15°); and medial (up to 10 mm), anterior (up to 25 mm), and proximal (up to 28 mm) displacements. These synthesised couplings appeared mainly partitioned into two clusters that featured all the dynamic weight-bearing activities and all the measurement methods. Thus, the effect of the dynamic activities on the couplings between the tibiofemoral DoFs appeared to be limited. The synthesised data might be used as a reference of normal in vivo knee kinematics for prosthetic and orthotic design and for knee biomechanical model development and validation.

Association of baseline knee sagittal dynamic joint stiffness during gait and 2-year patellofemoral cartilage damage worsening in knee osteoarthritis

OBJECTIVE

Knee sagittal dynamic joint stiffness (DJS) describes the biomechanical interaction between change in external knee flexion moment and flexion angular excursion during gait. In theory, greater DJS may particularly stress the patellofemoral (PF) compartment and thereby contribute to PF osteoarthritis (OA) worsening. We hypothesized that greater baseline knee sagittal DJS is associated with PF cartilage damage worsening 2 years later.

METHODS

Participants all had OA in at least one knee. Knee kinematics and kinetics during gait were recorded using motion capture systems and force plates. Knee sagittal DJS was computed as the slope of the linear regression line for knee flexion moments vs angles during the loading response phase. Knee magnetic resonance imaging (MRI) scans were obtained at baseline and 2 years later. We assessed the association between baseline DJS and baseline-to-2-year PF cartilage damage worsening using logistic regression with generalized estimating equations (GEE).

RESULTS

Our sample had 391 knees (204 persons): mean age 64.2 years (SD 10.0); body mass index (BMI) 28.4 kg/m² (5.7); 76.5% women. Baseline knee sagittal DJS was associated with baseline-to-2-year cartilage damage worsening in the lateral (OR = 5.35, 95% CI: 2.37-12.05) and any PF (OR = 2.99, 95% CI: 1.27-7.04) compartment. Individual components of baseline DJS (i.e., change in knee moment or angle) were not associated with subsequent PF disease worsening.

CONCLUSION

Capturing the concomitant effect of knee kinetics and kinematics during gait, knee sagittal DJS is a potentially modifiable risk factor for PF disease worsening.

The effect of orthotic devices on knee adduction moment, pain and function in medial compartment knee osteoarthritis: a literature review

Background Knee braces and foot orthoses are commonly used to improve knee adduction moment, pain and function in subjects with knee osteoarthritis (OA). However, no literature review has been performed to compare the effects of foot orthoses and knee braces in this group of patients. Purpose The aim of this review was to evaluate the effects of foot orthoses and knee braces on knee adduction moment, pain and function in individuals with knee OA. Study design Literature review. Method The search strategy was based on the Population Intervention Comparison Outcome method. A search was performed in PubMed, Science Direct, Google Scholar and ISI web of knowledge databases using the PRISMA method and based on selected keywords. Thirty-one related articles were selected for final evaluation. Results The results of the analysis of these studies demonstrated that orthotic devices reduce knee adduction moment and also improve pain and function in individuals with knee OA. Conclusion Foot orthoses may be more effective in improving pain and function in subjects with knee OA. Both knee braces and foot orthoses reduce the knee adduction moment in knee OA and consequently patients typically do not need to use knee braces for a long period of time. Also, foot orthoses and knee braces may be more effective for medial compartment knee OA patients due to the fact that this treatment helps improve pain and function. Implications for Rehabilitation Knee braces and foot orthoses are commonly used for improving knee adduction moment, pain and function in subjects with knee osteoarthritis (OA). Orthotic devices can reduce knee adduction moment, pain and improve function in knee OA. The combined use of a knee braces and foot orthoses can provide more improvement in knee adduction moment, reduced pain and increased function.

Knee joint contact mechanics during downhill gait and its relationship with varus/valgus motion and muscle strength in patients with knee osteoarthritis

OBJECTIVE

The objective of this exploratory study was to evaluate tibiofemoral joint contact point excursions and velocities during downhill gait and assess the relationship between tibiofemoral joint contact mechanics with frontal-plane knee joint motion and lower extremity muscle weakness in patients with knee osteoarthritis (OA).

METHODS

Dynamic stereo X-ray was used to quantify tibiofemoral joint contact mechanics and frontal-plane motion during the loading response phase of downhill gait in 11 patients with knee OA and 11 control volunteers. Quantitative testing of the quadriceps and the hip abductor muscles was also performed.

RESULTS

Patients with knee OA demonstrated larger medial/lateral joint contact point excursions (p < 0.02) and greater heel-strike joint contact point velocities (p < 0.05) for the medial and lateral compartments compared to the control group. The peak medial/lateral joint contact point velocity of the medial compartment was also greater for patients with knee OA compared to their control counterparts (p = 0.02). Additionally, patients with knee OA demonstrated significantly increased frontal-plane varus motion excursions (p < 0.01) and greater quadriceps and hip abductor muscle weakness (p = 0.03). In general, increased joint contact point excursions and velocities in patients with knee OA were linearly associated with greater frontal-plane varus motion excursions (p < 0.04) but not with quadriceps or hip abductor strength.

CONCLUSION

Altered contact mechanics in patients with knee OA may be related to compromised frontal-plane joint stability but not with deficits in muscle strength.

Manipulation of Ovarian Function Significantly Influenced Trabecular and Cortical Bone Volume, Architecture and Density in Mice at Death

Previously, transplantation of ovaries from young, cycling mice into old, postreproductive-age mice increased life span and decreased cardiomyopathy at death. We anticipated that the same factors that increased life span and decreased cardiomyopathy could also influence the progression of orthopedic disease. At 11 months of age, prepubertally ovariectomized and ovary-intact mice (including reproductively cycling and acyclic mice) received new 60-day-old ovaries. At death, epiphyseal bone in the proximal tibia and the distal femur and mid-shaft tibial and femoral diaphyseal bone was analyzed with micro-computed tomography. For qualitative analysis of osteophytosis, we also included mineralized connective tissue within the stifle joint. Prepubertal ovariectomy had the greatest influence on bone volume, ovarian transplantation had the greatest influence on bone architecture and both treatments influenced bone density. Ovarian transplantation increased cortical, but not trabecular bone density and tended to increase osteophytosis and heterotopic mineralization, except in acyclic recipients. These effects may have been dictated by the timing of the treatments, with ovariectomy appearing to influence early development and ovarian transplantation limited to influencing only the postreproductive period. However, major differences observed between cycling, acyclic and ovariectomized recipients of new ovaries may have been, in part due to differences in the levels of hormone receptors present and the responsiveness of specific bone processes to hormone signaling. Changes that resulted from these treatments may represent a compensatory response to normal age-associated, negative, orthopedic changes. Alternatively, differences between treatments may simply be the 'preservation' of unblemished orthopedic conditions, prior to the influence of negative, age-associated effects. These findings may suggest that in women, tailoring hormone replacement therapy to the patient's current reproductive status may improve therapy effectiveness and that beginning therapy earlier may help preserve trabecular bone mineral density that would otherwise be lost during perimenopause.

Altered gait characteristics in individuals with knee osteoarthritis and self-reported knee instability

STUDY DESIGN

Experimental laboratory study.

OBJECTIVE

To characterize the differences in lower extremity gait biomechanics in individuals who have knee osteoarthritis (OA) with and without self-reported knee instability.

BACKGROUND

Individuals with knee OA who experience episodes of knee instability often report gait difficulties that interfere with their daily lives. A better understanding of the alterations in gait biomechanics may help to mitigate symptomatic knee instability in this patient population.

METHODS

Seventeen participants with knee OA and self-reported knee instability and 36 participants with knee OA and no self-reported knee instability underwent instrumented gait analysis on level ground. Knee-specific symptoms and functional limitations were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index.

RESULTS

Knee instability was associated with greater odds of reporting moderate to severe gait-related pain (odds ratio = 6.0; 95% confidence interval: 1.2, 28.9) and moderate to severe difficulty when walking on flat surfaces (odds ratio = 10.7; 95% confidence interval: 1.7, 69.2). During early stance, the group with self-reported knee instability walked with a greater knee flexion excursion (P = .02) and a smaller lower extremity support moment (P<.01), due to reduced contributions from the hip extensors (P<.01) and ankle plantar flexors (P = .04). The group with self-reported knee instability also walked with a greater knee extensor contribution to the lower extremity support moment (P = .04) during the initial knee extension phase of gait compared to their counterparts with good knee stability.

CONCLUSION

These findings suggest that self-reported knee instability is associated with significant alterations in hip, knee, and ankle joint function during the stance phase of gait in individuals with knee OA.

No effects of a 12-week supervised exercise therapy program on gait in patients with mild to moderate osteoarthritis: a secondary analysis of a randomized trial

Background

It is unknown whether gait biomechanics in hip osteoarthritis patients with mild to moderate symptoms change following exercise therapy interventions. The aim of the present study was to compare stance phase gait characteristics in hip osteoarthritis patients with mild to moderate symptoms participating in a randomized trial with two different interventions; patient education only or patient education followed by a 12-week supervised exercise therapy program.

Results

The study was conducted as a secondary analysis of a single-blinded randomized controlled trial. Patients aged 40 to 80 years, with hip osteoarthritis verified from self-reported pain and radiographic changes, were included. The final material comprised 23 patients (10 males/13 females, mean (SD) age 58.2 (10.02) years) in the patient education only group, and 22 patients (9 males/13 females, mean (SD) age 60.2 (9.49) years) in the patient education + exercise therapy group. Three-dimensional gait analysis was conducted at baseline and at four month follow-up. Sagittal and frontal plane joint angle displacement and external joint moments of the hip, knee and ankle were compared from a one-way analysis of covariance between the groups at follow-up, with baseline values as covariates (p < 0.05). No group differences were observed at the four-month follow-up in gait velocity, joint angle displacement, or moments. As the compliance in the exercise therapy group was inadequate, we calculated possible associations between the number of completed exercise sessions and change in each of the kinematic or kinetic variables. Associations were weak to neglible. Thus, the negative findings in this study cannot be explained from inadequate compliance alone, but most likely also suggest the exercise therapy program itself to be insufficient to engender gait alterations.

Conclusions

Adding a 12-week supervised exercise therapy program to patient education did not induce changes in our selected biomechanical variables during the stance phase of gait, even when adjusting for poor compliance. Thus, we did not find evidence to support our exercise therapy program to be an efficacious intervention to induce gait alterations in this population of hip osteoarthritis patients.

Trial registration

NCT00319423 at ClinicalTrials.gov (registration date 2006-04-26).

Rigorous geometric self-calibrating bundle adjustment for a dual fluoroscopic imaging system

High-speed dual fluoroscopy is a noninvasive imaging technology for three-dimensional skeletal kinematics analysis that finds numerous biomechanical applications. Accurate reconstruction of bone translations and rotations from dual-fluoroscopic data requires accurate calibration of the imaging geometry and the many imaging distortions that corrupt the data. Direct linear transformation methods are commonly applied for performing calibration using a two-step process that suffers from a number of potential shortcomings including that each X-ray source and corresponding camera must be calibrated separately. Consequently, the true imaging set-up and the constraints it presents are not incorporated during calibration. A method to overcome such drawbacks is the single-step self-calibrating bundle adjustment method. This procedure, based on the collinearity principle augmented with imaging distortion models and geometric constraints, has been developed and is reported herein. Its efficacy is shown with a carefully controlled experiment comprising 300 image pairs with 48 507 image points. Application of all geometric constraints and a 31 parameter distortion model resulted in up to 91% improvement in terms of precision (model fit) and up to 71% improvement in terms of 3-D point reconstruction accuracy (0.3-0.4 mm). The accuracy of distance reconstruction was improved from 0.3±2.0 mm to 0.2 ±1.1 mm and angle reconstruction accuracy was improved from -0.03±0.55(°) to 0.01±0.06(°). Such positioning accuracy will allow for the accurate quantification of in vivo arthrokinematics crucial for skeletal biomechanics investigations.

Altered tibiofemoral joint contact mechanics and kinematics in patients with knee osteoarthritis and episodic complaints of joint instability

BACKGROUND

To evaluate knee joint contact mechanics and kinematics during the loading response phase of downhill gait in knee osteoarthritis patients with self-reported instability.

METHODS

Forty-three subjects, 11 with medial compartment knee osteoarthritis and self-reported instability (unstable), 7 with medial compartment knee osteoarthritis but no reports of instability (stable), and 25 without knee osteoarthritis or instability (control) underwent Dynamic Stereo X-ray analysis during a downhill gait task on a treadmill.

FINDINGS

The medial compartment contact point excursions were longer in the unstable group compared to the stable (P=0.046) and the control groups (P=0.016). The peak medial compartment contact point velocity was also greater for the unstable group compared to the stable (P=0.047) and control groups (P=0.022). Additionally, the unstable group demonstrated a coupled movement pattern of knee extension and external rotation after heel contact which was different than the coupled motion of knee flexion and internal rotation demonstrated by stable and control groups.

INTERPRETATION

Our findings suggest that knee joint contact mechanics and kinematics are altered during the loading response phase of downhill gait in knee osteoarthritis patients with self-reported instability. The observed longer medial compartment contact point excursions and higher velocities represent objective signs of mechanical instability that may place the arthritic knee joint at increased risk for disease progression. Further research is indicated to explore the clinical relevance of altered contact mechanics and kinematics during other common daily activities and to assess the efficacy of rehabilitation programs to improve altered joint biomechanics in knee osteoarthritis patients with self-reported instability.