Can generic knee joint models improve the measurement of osteoarthritic knee kinematics during squatting activity?

Knee joint kinematics derived from multi-body optimisation (MBO) still requires evaluation. The objective of this study was to corroborate model-derived kinematics of osteoarthritic knees obtained using four generic knee joint models used in musculoskeletal modelling – spherical, hinge, degree-of-freedom coupling curves and parallel mechanism – against reference knee kinematics measured by stereo-radiography. Root mean square errors ranged from 0.7° to 23.4° for knee rotations and from 0.6 to 9.0 mm for knee displacements. Model-derived knee kinematics computed from generic knee joint models was inaccurate. Future developments and experiments should improve the reliability of osteoarthritic knee models in MBO and musculoskeletal modelling.     

Can a finite set of knee extension in supine position be used for a knee functional examination?

The kinematic magnetic resonance imaging technique has been developed to provide a functional examination of the knee. Technical limitations require this examination to be performed in supine position, and the knee motion is represented by an assembly of static positions at different knee angles. However, the main knee function is to support the body weight and perform continuous motion, e.g. parallel squat. Our study quantified the knee kinematics of 20 healthy subjects in different motion conditions (finite and continuous) and in different mechanical conditions (continuous unloaded and continuous loaded). We evaluated the angular and localisation difference of a finite helical axis of the knee motion for parallel squat, continuous knee extension in supine position and the finite set of knee extension in supine position. We found large inter-individual dispersion. The majority of subjects had equivalent knee kinematics between continuous knee extension and the finite set of knee extension in supine position, but not between continuous knee extension in supine position and the parallel squat. Therefore, results from a functional examination of a finite set of knee extensions in supine position do not represent the knee motion in a parallel squat. Our results suggest that functional examination of the knee from magnetic resonance imaging do not necessarily reflect the physiological kinematics of the knee. Further investigation should focus on a new magnetic resonance imaging acquisition protocol that allows image acquisition during weight bearing or includes a special device which reproduces the loaded condition.     

Is the meniscus of the knee joint a fibrocartilage?

A histological analysis of the structure of intact knee joint menisci was carried out in adult dogs. By means of specific histochemical methods for the connective tissue and cartilage, it was found that the meniscus as a whole does not have a unique structure. The anterior and posterior horns are populated by round chondroid cells encircled by abundant interstitial substance and branched wavy connective fibers; blood vessels are present. The outer third of the meniscus is constituted of cross bundles of connective fibers, fibrocytes and spindle-like areas of loose connective tissue with blood vessels. The inner avascular two thirds of the meniscus are filled with parallel circumferentially oriented fascicles of connective fibers, ovally elongated chondroid cells, and a small quantity of chondroid interstitial substance. In some menisci, in the inner two thirds of the body, there are isles of typical cartilage, which show metachromasia of the beta type and rarely of the gamma type. The occurrence and way of the manifestation of cartilage are of an individual character. The structural duality of the knee meniscus is accounted for by its functional duality manifested in offering resistance to the forces of traction and pressure, the latter ones favoring the process of evolution of tissue from connective, through chondroid, to cartilaginous.     

A double blind,randomized, placebo controlled study of the efficacy and safety of 5-Loxin<Superscript>®</Superscript>for treatment of osteoarthritis of the knee

Introduction

5-Loxin^® is a novel Boswellia serrata extract enriched with 30% 3-O-acetyl-11-keto-beta-boswellic acid (AKBA), which exhibits potential anti-inflammatory properties by inhibiting the 5-lipoxygenase enzyme. A 90-day, double-blind, randomized, placebo-controlled study was conducted to evaluate the efficacy and safety of 5-Loxin^® in the treatment of osteoarthritis (OA) of the knee.

Methods

Seventy-five OA patients were included in the study. The patients received either 100 mg (n = 25) or 250 mg (n = 25) of 5-Loxin^® daily or a placebo (n = 25) for 90 days. Each patient was evaluated for pain and physical functions by using the standard tools (visual analog scale, Lequesne''s Functional Index, and Western Ontario and McMaster Universities Osteoarthritis Index) at the baseline (day 0), and at days 7, 30, 60 and 90. Additionally, the cartilage degrading enzyme matrix metalloproteinase-3 was also evaluated in synovial fluid from OA patients. Measurement of a battery of biochemical parameters in serum and haematological parameters, and urine analysis were performed to evaluate the safety of 5-Loxin^® in OA patients.

Results

Seventy patients completed the study. At the end of the study, both doses of 5-Loxin^® conferred clinically and statistically significant improvements in pain scores and physical function scores in OA patients. Interestingly, significant improvements in pain score and functional ability were recorded in the treatment group supplemented with 250 mg 5-Loxin^® as early as 7 days after the start of treatment. Corroborating the improvements in pain scores in treatment groups, we also noted significant reduction in synovial fluid matrix metalloproteinase-3. In comparison with placebo, the safety parameters were almost unchanged in the treatment groups.

Conclusion

5-Loxin^® reduces pain and improves physical functioning significantly in OA patients; and it is safe for human consumption. 5-Loxin^® may exert its beneficial effects by controlling inflammatory responses through reducing proinflammatory modulators, and it may improve joint health by reducing the enzymatic degradation of cartilage in OA patients.

Trail Registration

(Clinical trial registration number: ISRCTN05212803.)     

Does gender influence neuromotor control of the knee and hip?

Patellofemoral pain (PFP) is a common condition that occurs more frequently in females. Anatomical, hormonal and neuromuscular factors have been proposed to contribute to the increased incidence of PFP in females, with neuromuscular factors considered to be of particular importance. This cross-sectional study aimed to evaluate differences in the neuromotor control of the knee and hip muscles between genders and to investigate whether clinical measures of hip rotation range and strength were associated with EMG measures of hip and thigh motor control. Twenty-nine (16 female and 13 male) asymptomatic participants completed a visual choice reaction-time stair stepping task. EMG activity was recorded from vastus medialis oblique, vastus lateralis, anterior and posterior gluteus medius muscles. In addition hip rotation range of motion and hip external rotation, abduction and trunk strength were assessed. There were no differences in the timing or peak of EMG activation of the vasti or gluteus medius muscle between genders during the stepping task. There were however significant associations between EMG measures of motor control of the vasti and hip strength in both females and males. These findings are suggestive of a link between hip muscle control and vasti neuromotor control.     

Computation of the role of kinetics,kinematics, posterior tibial slope and muscle cocontraction on the stability of ACL-deficient knee joint at heel strike – Towards identification of copers from non-copers

Rupture of anterior cruciate ligament (ACL) undermines normal activity and function of the knee joint and places it at higher risk of re-injury and degeneration. ACL reconstruction surgery neither necessarily ensures return to pre-injury activities nor alleviates risk of long-term degeneration. Here in this computational investigation of a lower-extremity hybrid model at heel strike (HS) of gait, we search for factors that influence the stability of the joint and hence the distinct performances between post-ACL injury copers and non-copers. Due to the very unstable state of the joint under the mean gait input data, joint rotations-moments, posterior tibial slope (PTS), and cocontraction were altered within the reported data in the literature and the effects on the joint stability (anterior tibial translation (ATT) and critical muscle stiffness coefficient (q_cr)) were investigated. Results indicate that, in presence of both a small extension moment (0.1 or 0.2 Nm/kg) and a flexion rotation (∼5–8°), ACL-deficient (ACL-D) knee joint stability substantially improves to levels computed in the pre-injury intact joint. In addition, low cocontraction levels of 1–3% (in hamstrings and quads only and not in gastrocnemii) and reduced PTS (by 5°) further improve ACL-D joint stability. Therefore for a stable joint with ATT < 3 mm and q_cr < 25 similar to those in the intact knee at HS, higher flexion angles (>5°) and a small extension moment (∼0.1–0.2 Nm/kg) (i.e., higher activity in hamstrings than quads) are required. A lower posterior tibial slope (by 5°) and a small minimum cocontraction level (1–3%) in hamstrings and quads (but not in gastrocnemii) are also beneficial. These results identify mechanisms likely in play at HS in gait of copers when compared to non-copers.     

Characterization of caveolins from human knee joint cartilage: expression of caveolin-1, -2, and -3 in chondrocytes and association with integrin β1

Interactions between the extracellular matrix (ECM) and chondrocytes are of great importance for structure and function of cartilage. The present study was undertaken to answer the question whether caveolins take part in integrin-mediated cell–ECM interactions in the human cartilage. In samples of human knee joint cartilage, we detected the caveolin subtypes -1, -2, and -3 by immunohistochemical methods. Double-label experiments revealed a colocalization of caveolin with β1-integrin. Results of immunoprecipitation and immunoblotting assays show that β1-integrins associate with all three caveolin subtypes in human chondrocytes and indicate that they are part of the same complexes. Furthermore, immunoelectron microscopy shows the localization of β1-integrin in caveolae-like structures of the cell membrane. The data stimulate further investigations on the role of the caveolin–integrin complex for integrin-mediated signaling pathways in chondrocytes. Accepted: 17 December 1999     

Deformation of articular cartilage during static loading of a knee joint – Experimental and finite element analysis

Novel conical beam CT-scanners offer high resolution imaging of knee structures with i.a. contrast media, even under weight bearing. With this new technology, we aimed to determine cartilage strains and meniscal movement in a human knee at 0, 1, 5, and 30 min of standing and compare them to the subject-specific 3D finite element (FE) model. The FE model of the volunteer?s knee, based on the geometry obtained from magnetic resonance images, was created to simulate the creep. The effects of collagen fibril network stiffness, nonfibrillar matrix modulus, permeability and fluid flow boundary conditions on the creep response in cartilage were investigated. In the experiment, 80% of the maximum strain in cartilage developed immediately, after which the cartilage continued to deform slowly until the 30 min time point. Cartilage strains and meniscus movement obtained from the FE model matched adequately with the experimentally measured values. Reducing the fibril network stiffness increased the mean strains substantially, while the creep rate was primarily influenced by an increase in the nonfibrillar matrix modulus. Changing the initial permeability and preventing fluid flow through noncontacting surfaces had a negligible effect on cartilage strains. The present results improve understanding of the mechanisms controlling articular cartilage strains and meniscal movements in a knee joint under physiological static loading. Ultimately a validated model could be used as a noninvasive diagnostic tool to locate cartilage areas at risk for degeneration.     

Chronic oral or intraarticular administration of docosahexaenoic acid reduces nociception and knee edema and improves functional outcomes in a mouse model of Complete Freund’s Adjuvant–induced knee arthritis

Introduction

Clinical and preclinical studies have shown that supplementation with ω-3 polyunsaturated fatty acids (ω-3 PUFAs) reduce joint destruction and inflammation present in rheumatoid arthritis (RA). However, the effects of individual ω-3 PUFAs on chronic arthritic pain have not been evaluated to date. Thus, our aim in this study was to examine whether purified docosahexaenoic acid (DHA, an ω-3 PUFA) reduces spontaneous pain-related behavior and knee edema and improves functional outcomes in a mouse model of knee arthritis.

Methods

Unilateral arthritis was induced by multiple injections of Complete Freund’s Adjuvant (CFA) into the right knee joints of male ICR adult mice. Mice that received CFA injections were then chronically treated from day 15 until day 25 post–initial CFA injection with oral DHA (10, 30 and 100 mg/kg daily) or intraarticular DHA (25 and 50 μg/joint twice weekly). Spontaneous flinching of the injected extremity (considered as spontaneous pain-related behavior), vertical rearing and horizontal exploratory activity (considered as functional outcomes) and knee edema were assessed. To determine whether an endogenous opioid mechanism was involved in the therapeutic effect of DHA, naloxone (NLX, an opioid receptor antagonist, 3 mg/kg subcutaneously) was administered in arthritic mice chronically treated with DHA (30 mg/kg by mouth) at day 25 post–CFA injection.

Results

The intraarticular CFA injections resulted in increasing spontaneous flinching and knee edema of the ipsilateral extremity as well as worsening functional outcomes as time progressed. Chronic administration of DHA, given either orally or intraarticularly, significantly improved horizontal exploratory activity and reduced flinching behavior and knee edema in a dose-dependent manner. Administration of NLX did not reverse the antinociceptive effect of DHA.

Conclusions

To the best of our knowledge, this report is the first to demonstrate DHA’s antinociceptive and anti-inflammatory effects as individual ω-3 PUFAs following sustained systemic and intraarticular administration in a mouse model of CFA-induced knee arthritis. The results suggest that DHA treatment may offer a new therapeutic approach to alleviate inflammation as well as a beneficial effect on pain-related functional disabilities in RA patients.     

Test–retest reliability of quadriceps muscle function outcomes in patients with knee osteoarthritis

Quadriceps muscle weakness and the underlying neuromuscular deficits have been increasingly studied over the last few years in patients with knee osteoarthritis, but the applied methodologies have never been validated for this specific population. The aim of this study was to investigate test–retest reliability of several quadriceps muscle function outcomes in patients with knee osteoarthritis both before and after knee arthroplasty surgery. Ten preoperative and 20 postoperative patients participated in two identical testing sessions. A series of voluntary and/or electrically stimulated contractions of the involved quadriceps with concomitant torque and electromyographic recordings were used to characterize muscle strength, muscle activation and muscle contraction properties. Vastus lateralis morphology (thickness and fascicle pennation angle) was also assessed using ultrasonography. Overall, good reliability scores were observed for the majority of the 13 assessed variables (nine variables with intraclass correlation coefficients >0.75, 12 variables with coefficients of variation <15%). The most reliable testing protocol for patients with knee osteoarthritis would entail the assessment of (1) isometric maximal voluntary torque for evaluating muscle strength, with (2) simultaneous vastus lateralis electromyographic activity for evaluating muscle activation, (3) potentiated (resting) doublet peak torque for evaluating muscle contractility, and (4) vastus lateralis thickness for evaluating muscle size.     

Gene–gene interactions of the Wnt/β-catenin signaling pathway in knee osteoarthritis

Molecular Biology Reports - This study was designed to investigate whether genetic polymorphisms of the Wnt/β-catenin signaling pathway and its interactions are involved in the development of...     

Taping the patella medially: a new treatment for osteoarthritis of the knee joint?

OBJECTIVE--To test the hypothesis that medial taping of the patella reduces the symptoms of osteoarthritis of the knee when the patellofemoral joint is affected. DESIGN--Randomised, single blind, crossover trial of three different forms of taping of the knee joint. Each tape (medial, lateral, or neutral) was applied for four days, with three days of no treatment between tape positions. SUBJECTS--14 patients with established, symptomatic osteoarthritis of the knee and both clinical and radiographic evidence of patellofemoral compartment disease. MAIN OUTCOME MEASURES--Daily visual analogue scale ratings for pain; patients'' rating of change with each treatment; and tape preference. RESULTS--Medial taping of the patella was significantly better than the neutral or lateral taping for pain scores, symptom change, and patient preference. The medial tape resulted in a 25% reduction in knee pain. CONCLUSION--Patella taping is a simple, safe, cheap way of providing short term pain relief in patients with osteoarthritis of the patellofemoral joint.     

Automated hexahedral meshing of knee cartilage structures – application to data from the osteoarthritis initiative

We propose a fully automated methodology for hexahedral meshing of patient-specific structures of the human knee obtained from magnetic resonance images, i.e. femoral/tibial cartilages and menisci. We select eight patients from the Osteoarthritis Initiative and validate our methodology using MATLAB on a laptop computer. We obtain the patient-specific meshes in an average of three minutes, while faithfully representing the geometries with well-shaped elements. We hope to provide a fundamentally different means to test hypotheses on the mechanisms of disease progression by integrating our patient-specific FE meshes with data from individual patients. Download both our meshes and software at http://im.engr.uconn.edu/downloads.php.     

Does acute whole-body vibration training improve the physical performance of people with knee osteoarthritis?

ABSTRACT: Salmon, JR, Roper, JA, and Tillman, MD. Does acute whole-body vibration training improve the physical performance of people with knee osteoarthritis? J Strength Cond Res 26(11): 2983-2989, 2012-The purpose of this study was to determine the effects of a single session of whole-body vibration training (WBVT) on the physical performance of individuals with knee osteoarthritis (OA) in 3 tests designed to simulate activities of daily living (ADLs). Fifteen individuals with symptomatic knee OA completed the Timed-Up-and-Go Test, step test, 20-m walk test, and visual analog scale (VAS) recordings of knee pain intensity. A main effect was detected for time to complete the step test (F[2,28] = 6.243, p = 0.006, (Equation is included in full-text article.)). Post hoc analyses revealed that the time to complete the step test at 5 minutes after WBVT improved significantly (p = 0.042) from that of the pretest. A moderate correlation (r = 0.465, p = 0.001) was found between the VAS scores and the time to complete the step test across all trials. A main effect was found for time to complete the walk test (F[2,28] = 4.370, p = 0.022, (Equation is included in full-text article.)). Post hoc analyses did not indicate significant improvements from pretest seen at 5 minutes after WBVT (p = 0.110) and 1 hour after WBVT (p = 0.224). The WBVT was well tolerated in nearly all the participants, and we observed that an acute bout of WBVT was effective in improving the ability of individuals with knee OA to perform a step test and 20-m walk test. Our findings suggest that WBVT may be an effective nonpharmacologic modality to treat some knee OA symptoms and improve ADLs.     

What is the clinical and ethical importance of incidental abnormalities found by knee MRI?

Introduction

Magnetic resonance imaging (MRI) is increasingly used to examine joints for research purposes. It may detect both suspected and unsuspected abnormalities. This raises both clinical and ethical issues, especially when incidental abnormalities are detected. The prevalence of incidental, potentially clinically significant abnormalities identified by MRI and their clinical significance in a population undergoing knee MRI in research studies are unknown.

Methods

We examined the prevalence of such lesions in healthy asymptomatic adults and those with symptomatic knee osteoarthritis (OA) undergoing knee MRI with limited sequences for the purpose of research. The MRI findings in 601 asymptomatic subjects and 132 with knee OA who underwent at least one limited knee MRI scan for cartilage volume measurement were examined by an MRI radiologist for the presence of potentially clinically significant abnormalities.

Results

These were present in 2.3% of healthy and 2.3% of OA subjects. All required further investigation to exclude non-benign disease, including four with bone marrow expansion (0.7%), requiring further investigation and management. A single potentially life-threatening lesion, a myeloma lesion, was identified in a subject with symptomatic knee OA on their second MRI scan in a longitudinal study.

Conclusion

As musculoskeletal MRI is increasingly used clinically and for research purposes, the potential for detecting unsuspected abnormalities that require further investigation should be recognized. Incorporating a system to detect these, to characterize unexpected findings, and to facilitate appropriate medical follow-up when designing studies using this technology should be considered ethical research practice.     

Infrapatellar fat pad in the knee: is local fat good or bad for knee osteoarthritis?

Introduction

Recent studies regarding the infrapatellar fat pad (IPFP) mainly focus on the roles of the cells derived from the IPFP. There have been few clinical or epidemiological studies reporting on the association between the IPFP and knee osteoarthritis (OA). Our objective is to generate hypotheses regarding the associations between IPFP maximum area and knee OA measures in older adults.

Methods

A total of 977 subjects between 50 and 80 years of age (mean, 62.4 years) participated in the study. Radiographic knee osteophyte and joint space narrowing (JSN) were assessed using the Osteoarthritis Research Society International atlas. T1- or T2-weighted fat suppressed magnetic resonance imaging (MRI) was utilized to assess IPFP maximum area, cartilage volume, cartilage defects, and bone marrow lesions (BMLs). Knee pain was assessed by self-administered Western Ontario McMaster Osteoarthritis Index (WOMAC) questionnaire.

Results

After adjustment for potential confounders, IPFP maximum area was significantly associated with joint space narrowing (odds ratio (OR): 0.75, 95% confidence interval (CI): 0.62 to 0.91 (medial), 0.77, 95% CI: 0.62 to 0.96 (lateral)) and medial osteophytes (OR: 0.52, 95% CI: 0.35 to 0.76), knee tibial and patellar cartilage volume (β: 56.9 to 164.9 mm³/cm², all P <0.001), tibial cartilage defects (OR: 0.58, 95% CI: 0.41 to 0.81 (medial), 0.53, 95% CI: 0.40-0.71 (lateral)), any BMLs (OR: 0.77, 95% CI: 0.63 to 0.94), and knee pain on a flat surface (OR: 0.79, 95% CI: 0.63 to 0.98). IPFP maximum area was negatively, but not significantly, associated with femoral cartilage defects, lateral tibiofemoral BMLs, and total knee pain or other knee pain subscales.

Conclusion

IPFP maximum area is beneficially associated with radiographic OA, MRI structural pathology and knee pain on a flat surface suggesting a protective role for IPFP possibly through shock absorption. Consequently, we must pay special attention to IPFP in the clinical settings, avoiding resection of normal IPFP in knee surgery.