Medial Tibiofemoral Research Articles

Acute Effects of Barefoot and Minimalist Footwear on Medial Tibiofemoral Compartment Loading During Running: A Statistical Parametric Mapping Approach.

The current investigation examined the effects of running barefoot and in minimalist footwear on medial tibiofemoral compartment loading, compared to conventional running trainers. Fifteen male runners ran over a force platform in five different footwear conditions (barefoot, Vibram five-fingers (Footwear A), Inov-8 (Footwear B) Nike-Free (Footwear C), and running trainer) whilst lower extremity kinematics were examined using a three-dimensional camera system. Medial compartment loading during the stance phase was explored using the knee adduction moment (KAM). In addition, the KAM instantaneous load rate was also calculated. Differences between footwear across the entire stance phase were examined using 1-dimensional statistical parametric mapping, whereas differences in discrete parameters were explored using one-way repeated measures ANOVA. Statistical parametric mapping revealed that Footwear B was associated with a significantly larger KAM compared to the running trainer from 15-20 and 25-30% of the stance phase and also Footwear C from 15-20% of the stance phase. The KAM instantaneous load rate was significantly larger in the barefoot (210.69 Nm/kg/s), Footwear A (200.23 Nm/kg/s) and Footwear B (186.03 Nm/kg/s) conditions in comparison to Footwear C (100.88 Nm/kg/s) and running trainers (92.70 Nm/kg/s). The findings from this study indicate that running barefoot and in minimalist footwear with the least midsole interface may place runners at increased risk of medial compartment knee OA, although further exploration using habitual barefoot / minimalist footwear users is required.

Quadriceps Weakness and Risk of Knee Cartilage Loss Seen on Magnetic Resonance Imaging in a Population-based Cohort with Knee Pain.

To determine whether baseline quadriceps weakness predicts cartilage loss assessed on magnetic resonance imaging (MRI). Subjects aged 40-79 with knee pain (n = 163) were recruited from a random population sample and examined for quadriceps weakness with manual isometric strength testing, using a 3-point scoring system (0 = poor resistance, 1 = moderate resistance, 2 = full resistance), which was dichotomized as normal (grade 2) versus weak (grade 0/1). MRI of the more symptomatic knee was obtained at baseline and at mean of 3.3 years. Cartilage was graded 0-4 on MRI. Exponential regression analysis was used to evaluate whether quadriceps weakness was associated with whole knee cartilage loss, and in secondary analyses with compartment-specific cartilage loss, adjusted for age, sex, body mass index, Western Ontario and McMaster Universities Osteoarthritis Arthritis Index pain score, and baseline MRI cartilage score. Of 163 subjects, 54% were female, with a mean age of 57.7 years. Quadriceps weakness was seen in 11.9% of the subjects. Weakness was a predictor of whole knee cartilage loss (HR 3.48, 95% CI 1.30-9.35). Quadriceps weakness was associated with cartilage loss in the medial tibiofemoral (TF) compartment (HR 4.60, 95% CI 1.25-17.02), while no significant association was found with lateral TF (HR 1.53, 95% CI 0.24-9.78) or patellofemoral compartment (HR 2.76, 95% CI 0.46-16.44). In this symptomatic, population-based cohort, quadriceps weakness predicted whole knee and medial TF cartilage loss after 3 years. To our knowledge, this is the first study to show that a simple clinical examination of quadriceps strength can predict the risk of knee cartilage loss.

Compartmental distribution of osteoarthritic features amongst people with chronic knee pain: a magnetic resonance imaging study

Purpose: To explore the prevalence of osteoarthritic features identified on magnetic resonance imaging (MRI), in the compartments of the knee amongst people with chronic knee pain. Methods: 304 MRI scans from people aged 45 to 75 years with chronic knee pain participating in a randomised clinical trial evaluating dietary supplements were assessed. The MRIs were evaluated by the primary investigator (SK) using the MRI Osteoarthritis Knee Score (MOAKS). Bone marrow lesions (BML) size, cartilage loss and osteophytes were assessed on sagittal, axial and coronal plane scans. The knee was divided into the patellofemoral (PF), medial tibiofemoral (TF) and lateral TF compartments. Weighted kappa was used to assess intra-rater reliability. Frequency and vend diagrams were used to assess prevalence patterns of OA features in the compartments. Results: For all severities of BML size and full thickness cartilage loss, isolated PF involvement was the most common pattern (BML: 7.9–15.1%; cartilage loss: (13.2–20.7%). Tricompartmental patterns (14.8–22.4%) were the most common for osteophytes, followed by combined PF joint and medial TF joint involvement (13.8%) for mild osteophytes. Conclusions: Amongst a cohort of people with chronic knee pain, there was more involvement in the PF joint than the TF joint. Management strategies for knee OA should target risk factors for the PF joint.

The Clinical Significance of Osteophytes in Compartments of the Knee Joint With Normal Articular Cartilage.

The purpose of this study is to determine whether marginal osteophytes in compartments with normal cartilage would be more frequently observed in knees with cartilage lesions and osteophytes in other compartments. This retrospective study reviewed 500 consecutive knee MRI examinations performed within 6 months of arthroscopic knee surgery conducted for 497 patients with symptoms (289 male patients and 208 female patients; age range, 17-74 years; median age, 43 years). The highest grade of cartilage lesion detected at MRI and arthroscopy was recorded. Marginal osteophytes were graded on MRI with use of a standardized scoring system, with grade 0 denoting no osteophyte; grade 1, small osteophyte; grade 2, medium-size osteophyte; and grade 3, large osteophyte). The frequency of false-positive osteophytes, defined as osteophytes present in compartments (the patellofemoral, medial tibiofemoral, and lateral tibiofemoral compartments) with normal cartilage observed on MRI and arthroscopy, was calculated. The Goodman and Kruskal gamma statistic was used to test the association of osteophyte size between compartments. Logistic regression was used to test the association between osteophyte size and the severity of the cartilage lesions. Marginal osteophytes were seen in compartments with normal cartilage on MRI and arthroscopy in 60.5% of knees (75 of 124) with cartilage lesions and osteophytes in other compartments and accounted for all false-positive grade 2 and grade 3 osteophytes. Marginal osteophytes were seen in 12.7% of knees (13 of 102) that had no cartilage lesions in any compartment on MRI or arthroscopy, and all of these were grade 1 osteophytes. The presence of larger sized osteophytes in the compartments with cartilage lesions was associated with the presence of larger sized osteophytes in the compartments with normal cartilage. More severe cartilage lesions were associated with larger osteophyte size. Compartments with marginal osteophytes and normal cartilage are commonly seen in knees that have other compartments with osteophytes and cartilage lesions.

The effects of posterior cruciate ligament deficiency on posterolateral corner structures under gait- and squat-loading conditions: A computational knee model.

ObjectivesThe aim of the current study was to analyse the effects of posterior cruciate ligament (PCL) deficiency on forces of the posterolateral corner structure and on tibiofemoral (TF) and patellofemoral (PF) contact force under dynamic-loading conditions.MethodsA subject-specific knee model was validated using a passive flexion experiment, electromyography data, muscle activation, and previous experimental studies. The simulation was performed on the musculoskeletal models with and without PCL deficiency using a novel force-dependent kinematics method under gait- and squat-loading conditions, followed by probabilistic analysis for material uncertain to be considered.ResultsComparison of predicted passive flexion, posterior drawer kinematics and muscle activation with experimental measurements showed good agreement. Forces of the posterolateral corner structure, and TF and PF contact forces increased with PCL deficiency under gait- and squat-loading conditions. The rate of increase in PF contact force was the greatest during the squat-loading condition. The TF contact forces increased on both medial and lateral compartments during gait-loading conditions. However, during the squat-loading condition, the medial TF contact force tended to increase, while the lateral TF contact forces decreased. The posterolateral corner structure, which showed the greatest increase in force with deficiency of PCL under both gait- and squat-loading conditions, was the popliteus tendon (PT).ConclusionPCL deficiency is a factor affecting the variability of force on the PT in dynamic-loading conditions, and it could lead to degeneration of the PF joint.Cite this article: K-T. Kang, Y-G. Koh, M. Jung, J-H. Nam, J. Son, Y.H. Lee, S-J. Kim, S-H. Kim. The effects of posterior cruciate ligament deficiency on posterolateral corner structures under gait- and squat-loading conditions: A computational knee model. Bone Joint Res 2017;6:31–42. DOI: 10.1302/2046-3758.61.BJR-2016-0184.R1.

Gender Differences in Knee Joint Congruity Quantified from MRI: A Validation Study with Data from Center for Clinical and Basic Research and Osteoarthritis Initiative.

Objective Gender is a risk factor in the onset of osteoarthritis (OA). The aim of the study was to investigate gender differences in contact area (CA) and congruity index (CI) in the medial tibiofemoral (MTF) joint in 2 different cohorts, quantified automatically from magnetic resonance imaging (MRI). Design The CA and CI markers were validated on 2 different data sets from Center for Clinical and Basic Research (CCBR) and Osteoarthritis Initiative (OAI). The CCBR cohort consisted of 159 subjects and the OAI subcohort consisted of 1,436 subjects. From the MTF joint, the contact area was located and quantified using Euclidean distance transform. Furthermore, the CI was quantified over the contact area by assessing agreement of the first- and second-order general surface features. Then, the gender differences between CA and CI values were evaluated at different stages of radiographic OA. Results Female CAs were significantly higher than male CAs after normalization, male CIs were significantly higher than female CIs after correcting with age and body mass index ( P < 0.05), consistent across the 2 data sets. For the OAI data set, the gender differences were present at all stages of radiographic OA. Conclusion This study demonstrated the gender differences in CA and CI in MTF joints. The higher normalized CA and lower CI values in female knees may be linked with the increased risk of incidence of radiographic OA in females. These differences may help further understand the gender differences and/or to establish gender specific treatment strategies.

Clinical Impact of Coexisting Patellofemoral Osteoarthritis in Japanese Patients With Medial Knee Osteoarthritis.

To evaluate the clinical impact in knee osteoarthritis (OA) of coexisting patellofemoral (PF) joint OA (PFOA) in Japanese patients with medial tibiofemoral (TF) joint OA (TFOA). Patients with medial knee OA (n = 143) were enrolled. The radiographic severity of the TF and PF joints, anatomic axis angle of the TF joint, patellar alignment, trochlear morphology, patellar height, and passive range of motion (ROM) of the painful knee were evaluated. Additionally, the Japanese Knee Osteoarthritis Measure (JKOM) was used to investigate the association between the presence of PFOA and clinical symptoms. PFOA was present in 98 of 143 patients (68.5%) with medial knee OA. Quantile regression analysis revealed that coexisting PFOA was associated with the pain-related subcategory of the JKOM. Furthermore, multiple logistic regression analysis showed that coexisting PFOA was associated with higher odds of reporting knee pain on using stairs while ascending (odds ratio [OR] 4.81 [95% confidence interval (95% CI) 1.73, 14.3]) and descending (OR 3.86 [95% CI 1.44, 10.8]). A more varus knee alignment and lower knee flexion ROM, which are features of patients with coexisting PFOA, were associated with knee pain while ascending/descending stairs. However, patellar alignment, trochlear morphology, and patellar height were not significantly associated with knee pain. PFOA coexisting with medial knee OA was associated with worse clinical symptoms, particularly while ascending/descending stairs, although patellar alignment did not contribute to reporting knee pain. Further studies that include evaluation of the PF joint are warranted to develop a basis for an optimal intervention based on compartmental involvement.

Does knee malalignment predict the efficacy of realignment therapy for patients with knee osteoarthritis?

Realignment therapies, including knee braces, foot orthoses and shoes are prescribed to patients with medial knee osteoarthritis (OA) with the goal of unloading the medial tibiofemoral (TF) compartment. It is uncertain whether realignment therapies have different effects in those with knee malalignment. We studied whether the efficacy of realignment therapy for pain and function in persons with medial TF OA is predicted by the severity of the baseline knee malalignment. The baseline characteristics of 48 participants with moderate to severe medial knee OA were collected. Participants' pain and function were measured using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale before and after 12weeks of realignment therapy using a valgus unloader knee brace plus bilateral neutral foot orthoses and motion control shoes. Anatomical axis (AA) was measured on weight-bearing knee radiographs by a blinded reader and knee malalignment was categorized as either varus malaligned (moderate or severe) or neutral according to the AA angle. We assessed for differences in response to treatment according to alignment category. General linear statistical models were generated to determine which of the measured alignment variables and covariates predicted change in the pain outcome. Anatomical axis knee alignment was not a significant predictor of pain or function change with active treatment. Baseline WOMAC scores were the best predictor of change in WOMAC (P<0.01 and P=0.06 for pain and function, respectively). Baseline knee alignment did not predict the efficacy of 12weeks realignment therapy in participants with medial tibiofemoral OA. [Correction added on 27 August 2015, after first online publication: 'did predict' has been corrected to 'did not predict' in the conclusions of the abstract section.].

Cartilage health in high tibial osteotomy using dGEMRIC: Relationships with joint kinematics

PurposeThe aims of this study are to determine how opening-wedge high tibial osteotomy (HTO) affects cartilage health in the tibiofemoral (TF) joint and patella, and to explore relationships between TF and patellofemoral (PF) joint kinematics and cartilage health in HTO. Methods14 knees (13 subjects) with medial TF osteoarthritis (OA) were examined before HTO and 6 and 12months after HTO using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) to evaluate cartilage health at the TF joint and patella. They were also examined using a validated 3D MR knee kinematics measurement to obtain 11 rotations and translations at both TF and PF joints. ResultsNo statistically significant differences in overall TF or patellar dGEMRIC score were found at 6 or 12months after HTO. However three subjects had large decreases (mean 105ms) in TF dGEMRIC at 6months that recovered at 12months. Kinematics for these subjects were compared to subjects who did not have decreases in TF dGEMRIC at 6months (n=5). Differences were observed between groups with HTO in anterior and proximal tibial translation (mean differences 3.05mm and 1.35mm), and patellar flexion (mean difference 3.65°). These changes were consistent between 6 and 12months, despite recovery of TF dGEMRIC values. ConclusionsWe did not find significant differences in TF or patellar dGEMRIC before and after HTO with all subjects, however there were differences in kinematics between subjects who had a decrease in TF dGEMRIC at 6months and those who did not. This suggests a link between joint kinematics and cartilage health in HTO. Clinical relevanceThe effect of opening-wedge high tibial osteotomy on cartilage GAG concentration may be linked to specific changes in knee kinematics following surgery

A subject-specific musculoskeletal modeling framework to predict in vivo mechanics of total knee arthroplasty.

Musculoskeletal (MS) models should be able to integrate patient-specific MS architecture and undergo thorough validation prior to their introduction into clinical practice. We present a methodology to develop subject-specific models able to simultaneously predict muscle, ligament, and knee joint contact forces along with secondary knee kinematics. The MS architecture of a generic cadaver-based model was scaled using an advanced morphing technique to the subject-specific morphology of a patient implanted with an instrumented total knee arthroplasty (TKA) available in the fifth "grand challenge competition to predict in vivo knee loads" dataset. We implemented two separate knee models, one employing traditional hinge constraints, which was solved using an inverse dynamics technique, and another one using an 11-degree-of-freedom (DOF) representation of the tibiofemoral (TF) and patellofemoral (PF) joints, which was solved using a combined inverse dynamic and quasi-static analysis, called force-dependent kinematics (FDK). TF joint forces for one gait and one right-turn trial and secondary knee kinematics for one unloaded leg-swing trial were predicted and evaluated using experimental data available in the grand challenge dataset. Total compressive TF contact forces were predicted by both hinge and FDK knee models with a root-mean-square error (RMSE) and a coefficient of determination (R2) smaller than 0.3 body weight (BW) and equal to 0.9 in the gait trial simulation and smaller than 0.4 BW and larger than 0.8 in the right-turn trial simulation, respectively. Total, medial, and lateral TF joint contact force predictions were highly similar, regardless of the type of knee model used. Medial (respectively lateral) TF forces were over- (respectively, under-) predicted with a magnitude error of M &lt; 0.2 (respectively &gt; -0.4) in the gait trial, and under- (respectively, over-) predicted with a magnitude error of M &gt; -0.4 (respectively &lt; 0.3) in the right-turn trial. Secondary knee kinematics from the unloaded leg-swing trial were overall better approximated using the FDK model (average Sprague and Geers' combined error C = 0.06) than when using a hinged knee model (C = 0.34). The proposed modeling approach allows detailed subject-specific scaling and personalization and does not contain any nonphysiological parameters. This modeling framework has potential applications in aiding the clinical decision-making in orthopedics procedures and as a tool for virtual implant design.

Arthroscopic Release of the Deep Medial Collateral Ligament to Assist in Exposure of the Medial Tibiofemoral Compartment

Arthroscopy of the knee is a widely used surgical procedure for addressing intra-articular pathology. In assessing the intra-articular structures, visualization is of paramount importance. The medial tibiofemoral compartment is often difficult to fully visualize in tight knees in which limited access can compromise surgical efficacy. Poor visualization can increase the possibility of a residual meniscal tear after attempted partial meniscectomy, as well as the possibility of iatrogenic chondral injury from arthroscopic instruments. We describe a technique that allows improved medial tibiofemoral visualization with release of the deep medial collateral ligament. We use standard arthroscopic portals, without the need for further incisions or stab holes and with minimal additional patient morbidity. This procedure allows easier exposure of the medial knee chondral surfaces and meniscus and easier use of arthroscopic instrumentation in the medial compartment.

Outcomes of bicompartmental knee arthroplasty: a review

Introduction Isolated unicompartmental knee arthroplasty (UKA) and patellofemoral arthroplasty (PFA) are effective for localized arthritis. It becomes more controversial if the arthritis is present in two compartments of the knee.Total knee arthroplasty (TKA) offers high survival and high functional scores when arthritis is affecting the three compartments of the knee; however, TKA does not preserve the bone stock and the ligaments and these points can represent theoretical disadvantages, particularly for young patients with higher demand and higher risk for potential revision . BKA is a type of resurfacing surgery where two of the three compartments of the knee (medial tibiofemoral, lateral tibiofemoral or patellofemoral) joint are replaced with preservation of the third. Smaller implant sizes, less operative trauma, preservation of both cruciate ligaments and bone stock, and a more ‘‘physiological’’ knee are reported advantages over TKA. bicompartmental knee arthroplasties have been proposed to bridge the gap between UKA and TKA. There are two philosophically different BKA femoral component designs, modular unlinked components or single monolithic with a fixed relationship between the patello- and tibiofemoral components. Early clinical results of BKA have shown excellent pain relief, knee function, restoration of appropriate knee alignment, less bloodloss, shorter hospital stay and rapid return to normal activity. But opponents stated that these advantages do not persist after 1 year postoperatively.The younger, more active patient may be eligible for this type of resurfacing surgery: is a minimally invasive surgery because it is a tissue sparing knee surgery with multiple goals, such as avoid complications (fat embolism, blood loss), use smaller incisions, shorter hospital stay, lower risk of infection, lower risk of venous thromboembolism (VTE), faster return to daily activity, improving range of motion, obtain faster rehabilitation, less pain, obtain a highly functional implant and easier revision surgery, if required, at a later date. This review discuss the clinical results, the kinematics, the proprioceptive function, the revision rate and the survivorship curve of BKA. METHODS A systematic literature search was conducted during May and June 2014. The electronic databases searched were: MEDLINE and Cochrane Library. No language or data restrictions were used. The search keyword was bicompartmental knee artroplasty, BKA, unicompartmental knee arthroplasty AND patellofemoral arthroplasty, unicompartmental knee arthroplasty AND patellofemoral joint, UKA AND PFJ, which appeared in the title, abstract or keyword fields. Initially, 129 articles were found: based on abstract and after removal of duplicates, 102 articles remained. The full text of each of these articles was read and another 13 articles were considered non-relevant and removed. The final number of articles included in this review was 89. Conclusion. advantages of a bone-sparing, ligament-sparing, such as BKA, are clearly evident. It seems intuitive that a knee reconstruction that maintains the proprioceptive and kinematic benefits of retaining the cruciate ligaments would be ideal for the treatment of advanced OA of the medial and patellafemoral compartments. Choice of monolithic or modular components remains in debate but the use of single femoral components can lead to early revision. There is a need for a prospective, randomized, long-term outcomes studies comparing BKA with TKA before definitive treatment recommendations can be made.

OP0063 Associations between Abnormal Infrapatellar FAT PAD Quality and Knee Osteoarthritic Changes in Older Adults: A Cohort Study

BackgroundInfrapatellar fat pad (IPFP), an intracapsular but extrasynovial structure, is situated in the knee under the patella, between the patellar tendon, femoral condyle and tibial plateau, and is structurally similar...

Osteoarthritis of the knee: multicompartmental or compartmental disease?

Knee OA has been conceptualized as a multicompartmental disease, as a compartmental disease or as a combination of these two disease processes. The aim of this study was to determine the associations between four radiographic features (joint space narrowing, osteophyte formation, sclerosis and cysts) across and within the three knee compartments (medial tibiofemoral, lateral tibiofemoral and patellofemoral compartment) in knee OA. Data from the Amsterdam OA Cohort were used. In 298 patients diagnosed with knee OA, radiographic features were examined in three knee joint compartments. Radiographic features were scored according to standardized scoring methods. Factor analysis was used to examine associations between the four radiographic features across and within compartments. A bifactor model showed a general multicompartmental factor: 10 of 12 radiographic features across the entire joint were associated with the general factor. The bifactor model also showed three compartmental factors-one for each compartment: joint space narrowing, sclerosis and to a lesser extent osteophyte formation were associated with these compartmental factors. These findings suggest a multicompartmental disease process in the knee, characterized by associations among features across the entire joint, as well as compartmental disease processes in each knee compartment, characterized by associations among features within specific compartments. Longitudinal studies are needed to explore the possibility of the development from a compartmental disease to a multicompartmental disease and the impact of contributing factors on the development.

Relationship between knee alignment and radiographic markers of osteoarthritis: a cross‐sectional study from a Korean population

The purpose of this paper was to investigate the relationship between static varus knee alignment and the radiographic markers of knee osteoarthritis (OA), including joint space narrowing (JSN) and Kellgren-Lawrence (K-L) grading scale. Knee alignment was measured by mechanical axis from weight-bearing anteroposterior (AP) radiographs of 251 symptomatic knees with radiological signs of OA (K-L grade ≥1). Linear correlation between knee varus alignment and variables, including joint space width (JSW) and K-L grades of tibiofemoral (TF) joint in extension or 45° flexion and patellofemoral (PF) joints were investigated. Multiple linear regression analyses were also performed to examine independent associations between varus knee alignment and JSW. Analysis of covariance (ancova) was performed to analyze the difference in knee alignment among K-L grade category groups adjusted for physical variables. Varus knee alignment was negatively correlated with JSW of medial TF joint in extension AP (r=-0.460, P=0.0001) and 45° flexion PA views (r=-0.476, P=0.0001) and PF JSN (r=-0.168, P=0.008). Multiple linear regression analysis adjusted for physical variables showed that the varus knee alignment was negatively associated with the JSW of medial TF joint in extension AP (P=0.0001) and 45° flexion PA view (P=0.0001). ancova adjusted for physical variables showed that knees in K-L grade 4 had significantly greater varus alignment than those in K-L grades 1-3 in AP (P=0.0001), 45° flexion PA view (P=0.0001), and PF joint (P=0.0001~0.001). Varus knee alignment is associated with the radiographic measures of knee OA severity.

OP0317 Infrapatellar Fat Pad Area is Associated with Reduced Knee Symptomatic and Structural Abnormalities in Older Adults: A Cross-Sectional Study

BackgroundRecent studies consider infrapatellar fat pad (IPFP) as an active joint tissue in the initiation and progression of knee OA, as inflammatory cells from IPFP can produce inflammatory mediators [1]....

Reliability of a uni-compartmental scale for the radiographic evaluation of knee arthritis: data from the multicenter osteoarthritis study

Reliability of a uni-compartmental scale for the radiographic evaluation of knee arthritis: data from the multicenter osteoarthritis study

Paper 144: Effect of Opening-wedge High Tibial Osteotomy on Three-dimensional Knee Kinematics

Medial opening-wedge high tibial osteotomy (HTO) is a treatment for medial tibiofemoral osteoarthritis caused by varus malalignment. This malalignment shifts the line of action of the ground reaction force relative to the centre of the knee, which increases load in the medial compartment. This increased load is widely believed to be the cause of medial tibiofemoral (TF) OA. HTO restores the line of action to a neutral or slightly lateral position. Consensus has emerged on an optimal range of varus/valgus angular correction, however achieving this correction does not guarantee good clinical results. A key limitation of current assessment that may explain this is that the current standard for assessing tibiofemoral alignment, a standing radiograph, provides a poor assessment of the mechanics of the joint. Three-dimensional measurements of tibiofemoral and patellofemoral kinematics in vivo have recently become available but the effect of opening-wedge high tibial osteotomy on knee kinematics is not clear. Our research question was: how does opening-wedge HTO affect 3D tibiofemoral and patellofemoral kinematics? Three-dimensional tibiofemoral and patellofemoral kinematics were assessed in four subjects before HTO surgery and at 6 months follow-up using a validated MR imaging method (1Fellows R.A. et al.J Biomech. Aug 2005; 38: 1643-1652Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar, 2Fellows R.A. et al.J Magn Reson Imaging. 2005; 22: 145-153Crossref PubMed Scopus (34) Google Scholar). Ethics board approval was granted and informed consent was obtained from all subjects for this study. Titanium surgical hardware was used for minimum artifact in the images. For each assessment, the subject lay supine in the MR scanner. A high-resolution T1-weighted mulitslice scan of the knee was performed in a relaxed position. Low resolution images of the knee were then obtained at six flexion angles (10°–60°) while the subject loaded his/her knee using a specially designed loading rig. Bone was segmented from the MR images using Analyze. Surfaces (high-res) and contours (low-res) were then imported into MATLAB. The high-resolution models were shapematched to the low-resolution data sets using an iterative closest points algorithm. Anatomical axes were assigned to each bone using anatomical landmarks. Kinematic parameters (rotations and translations) with respect to femur for both tibia and patella were output. Linear best fits were calculated for each parameter with respect to tibial flexion. Slope and intercept were examined using a paired t-test. HTO significantly shifted the tibia anteriorly through the range of flexion (p<0.05). The average change at 30 degrees was 6.5 mm. Correlation coefficients for the linear fits were r^2 = 0.73-0.98. HTO significantly shifted the patella distally through the range of flexion (p<0.05). The average change at 30 degrees was 1.9 mm. Correlation coefficients for the linear fits were r^2 = 0.92-0.99. Other kinematic parameters were changed following surgery, but the changes were not statistically significant in this small group: tibial adduction, patellar spin, patellar tilt, tibial proximal translation, and patellar flexion. Changes were evident in the patellar parameters spin and tilt, however the r^2 values for the linear fits were low. If there is a consistent pattern in these kinematic parameters, it may be best represented by a higher-order polynomial fit. HTO decreased tibiofemoral adduction (up to 10 degrees) in three subjects, while it remained similar in one subject. Tibial anterior translation with surgery is clinically important because it suggests that the contact centers in the tibiofemoral joint may have shifted posteriorly, an outcome thought to be related to changes in tibial slope (3Rodner C.M. et al.52nd ORS. 2006; (Paper No. 0250)Google Scholar). Anterior translation in this case is not due to a major change in tibial slope: for three subjects direct confirmation was obtained showing tibial slope change was less than 3 degrees.

Joint kinematics following bi-compartmental knee replacement during daily life motor tasks

In many cases knee osteoarthritis leads to total knee replacement surgery (TKR) even if the lateral compartment is not involved. More recently, a bicompartmental knee replacement system (BKR) (Journey Deuce, Smith & Nephew Inc., Memphis, TN, USA) has been developed that only replaces the medial tibiofemoral and the patellofemoral compartments, thus preserving both cruciate ligaments with its associated benefits. However information on the effect of BKR on in vivo knee joint kinematics is not widely available in the literature.Therefore, this study analyzed full three-dimensional knee joint kinematics in 10 postoperative BKR-subjects for a broad spectrum of relevant daily life activities: walking, walking followed by a cross-over or sidestep turn, step ascent and descent, mild squatting and chair rise. We analyzed to what extent normal knee motion is regained through comparison with their non-involved limb as well as a group of matched controls. Furthermore, coefficients of multiple correlation were calculated to assess the consistency of knee joint kinematics both within and between subject groups.This analysis demonstrated that, despite the presence of differences indicative for retention of pre-operative motion patterns and/or remaining compensations, knee joint kinematics in BKR limbs replicate, for a large range of daily-life motor tasks, the kinematics of the contra-lateral non-affected limbs and healthy controls to a similar extent as they are replicated within both these control groups.

The Acute Effect of Running on Knee Articular Cartilage and Meniscus Magnetic Resonance Relaxation Times in Young Healthy Adults

Background: Understanding the acute response of healthy knee cartilage to running may provide valuable insight into functional properties. In recent years, quantitative magnetic resonance (MR) imaging techniques (T1ρ and T2 relaxation measurement) have shown tremendous potential and unique ability to noninvasively and quantitatively determine cartilage response to physiologic levels of loading occurring with physiologic levels of exercise. Purpose: To measure the short-term changes in MR T1ρ and T2 relaxation times of knee articular cartilage and meniscus in healthy individuals immediately after 30 minutes of running. Study Design: Descriptive laboratory study. Methods: Twenty young healthy volunteers, aged 22 to 35 years, underwent 3T MR imaging of the knee before and immediately after 30 minutes of running. Quantitative assessment of the cartilage and menisci was performed using MR images with a T1ρ and T2 mapping technique. After adjusting for age, sex, and body mass index, repeated-measures analysis of variance was used to determine the effects of running on MR relaxation times. Results: The post-run T1ρ and T2 measurement showed significant reduction in all regions of cartilage except the lateral tibia when compared with the pre-run condition. The medial tibiofemoral (T1ρ: 9.4%, P < .0001; T2: 5.4%, P = .0049) and patellofemoral (T1ρ: 12.5%, P < .0001; T2: 5.7%, P = .0007) compartments experienced the greatest reduction after running. The superficial layer of the articular cartilage showed significantly higher change in relaxation times than the deep layer (∆T1ρ: 9.6% vs 8.2%, P = .050; ∆T2: 6.0% vs 3.5%, P = .069). The anterior and posterior horns of the medial meniscus (9.7%, P = .016 and 11.4%, P = .001) were the only meniscal subregions with significant changes in T1ρ after running. Conclusion: Shorter T1ρ and T2 values after running suggest alteration in the water content and collagen fiber orientation of the articular cartilage. Greater changes in relaxation times of the medial compartment and patellofemoral joint cartilage indicate greater load sharing by these areas during running.