Histopathological correlation of cartilage swelling detected by magnetic resonance imaging in early experimental osteoarthritis

Cartilage Integrity: A Review of Mechanical and Frictional Properties and Repair Approaches in Osteoarthritis

Osteoarthritis (OA) is one of the most common causes of disability around the globe, especially in aging populations. The main symptoms of OA are pain and loss of motion and function of the affected joint. Hyaline cartilage has limited ability for regeneration due to its avascularity, lack of nerve endings, and very slow metabolism. Total joint replacement (TJR) has to date been used as the treatment of end-stage disease. Various joint-sparing alternatives, including conservative and surgical treatment, have been proposed in the literature; however, no treatment to date has been fully successful in restoring hyaline cartilage. The mechanical and frictional properties of the cartilage are of paramount importance in terms of cartilage resistance to continuous loading. OA causes numerous changes in the macro- and microstructure of cartilage, affecting its mechanical properties. Increased friction and reduced load-bearing capability of the cartilage accelerate further degradation of tissue by exerting increased loads on the healthy surrounding tissues. Cartilage repair techniques aim to restore function and reduce pain in the affected joint. Numerous studies have investigated the biological aspects of OA progression and cartilage repair techniques. However, the mechanical properties of cartilage repair techniques are of vital importance and must be addressed too. This review, therefore, addresses the mechanical and frictional properties of articular cartilage and its changes during OA, and it summarizes the mechanical outcomes of cartilage repair techniques.

An accelerated PETALUTE MRI sequence for in vivo quantification of sodium content in human articular cartilage at 3T

OBJECTIVE

In this work, we evaluate the sodium magnetic resonance imaging (MRI) capabilities of a three-dimensional (3D) dual-echo ultrashort echo time (UTE) sequence with a novel rosette petal trajectory (PETALUTE), in comparison to the 3D density-adapted (DA) radial spokes UTE sequence in human articular cartilage in the knee.

MATERIALS AND METHODS

We scanned five healthy subjects using a 3D dual-echo PETALUTE acquisition and two comparable implementations of 3D DA-radial spokes acquisitions, one matching the number of k-space projections (Radial - Matched Spokes) and the other matching the total number of samples (Radial - Matched Samples) acquired in k-space.

RESULTS

The PETALUTE acquisition enabled equivalent sodium quantification in articular cartilage volumes of interest (168.8 ± 29.9 mM, mean ± standard deviation) to those derived from the 3D radial acquisitions (171.62 ± 28.7 mM and 149.8 ± 22.2 mM, respectively). We achieved a 41% shorter scan time of 2:06 for 3D PETALUTE, compared to 3:36 for 3D radial acquisitions. We also evaluated the feasibility of further acceleration of the PETALUTE sequence through retrospective compressed sensing with 2 × and 4 × acceleration of the first echo and showed structural similarity of 0.89 ± 0.03 and 0.87 ± 0.03 when compared to non-retrospectively accelerated reconstruction.

CONCLUSION

We demonstrate improved scan time with equivalent performance using a 3D dual-echo PETALUTE sequence compared to the 3D DA-radial sequence for sodium MRI of articular cartilage.

Increased femoral cartilage thickness in acne patients using isotretinoin: could it be a sign of early osteoarthritis?

Vitamin A derivatives have inhibitory effects on cartilage tissue, such as decreasing chondrocyte proliferation and collagen synthesis, and increasing the loss of glycosaminoglycans and proteoglycans. Therefore, isotretinoin (a vitamin A derivative) may play a role in the pathogenesis of cartilage-related diseases like osteoarthritis by affecting the balance of cartilage tissue. The aim of this study was to evaluate the distal femoral cartilage thickness in acne patients under the systemic isotretinoin therapy and to determine whether it constitutes a risk factor for the development of osteoarthritis. The study included 52 patients (42 female, 10 male, mean age 23.31 ± 3.89 years) who were prescribed systemic isotretinoin for acne and completed at least 3 months of treatment, along with 45 healthy controls ((35 female, 10 male, mean age 23.85 ± 4.77 years). Bilateral distal femoral cartilage thickness was measured by ultrasonography before isotretinoin treatment and after the completion of the third month of treatment. After treatment, a statistically significant increase was found in the thickness of the right medial, right lateral, left medial, left lateral, and left intercondylar cartilage (p = 0.014, 0.012, 0.019, 0.027, 0.002, respectively). There was also an increase in the right intercondylar cartilage thickness, but this was not statistically significant (p = 0.1). Systemic isotretinoin seems to make cartilage thicker. The increase in femoral cartilage thickness observed after short-term isotretinoin treatment might be an indicator of very early-stage osteoarthritis. Extended follow-up studies with larger participant pools are necessary to substantiate this result.

Effects of different combinations of mechanical loading intensity, duration, and frequency on the articular cartilage in mice

BACKGROUND

Understanding how healthy articular cartilage responds to mechanical loading is critical. Moderate mechanical loading has positive effects on the cartilage, such as maintaining cartilage homeostasis. The degree of mechanical loading is determined by a combination of intensity, frequency, and duration; however, the best combination of these parameters for knee cartilage remains unclear. This study aimed to determine which combination of intensity, frequency, and duration provides the best mechanical loading on healthy knee articular cartilage in vitro and in vivo.

METHODS AND RESULTS

In this study, 33 male mice were used. Chondrocytes isolated from mouse knee joints were subjected to different cyclic tensile strains (CTSs) and assessed by measuring the expression of cartilage matrix-related genes. Furthermore, the histological characteristics of mouse tibial cartilages were quantified using different treadmill exercises. Chondrocytes and mice were divided into the control group and eight intervention groups: high-intensity, high-frequency, and long-duration; high-intensity, high-frequency, and short-duration; high-intensity, low-frequency, and long-duration; high-intensity, low-frequency, and short-duration; low-intensity, high-frequency, and long-duration; low-intensity, high-frequency, and short-duration; low-intensity, low-frequency, and long-duration; low-intensity, low-frequency, and short-duration. In low-intensity CTSs, chondrocytes showed anabolic responses by altering the mRNA expression of COL2A1 in short durations and SOX9 in long durations. Furthermore, low-intensity, low-frequency, and long-duration treadmill exercises minimized chondrocyte hypertrophy and enhanced aggrecan synthesis in tibial cartilages.

CONCLUSION

Low-intensity, low-frequency, and long-duration mechanical loading is the best combination for healthy knee cartilage to maintain homeostasis and activate anabolic responses. Our findings provide a significant scientific basis for exercise and lifestyle instructions.

Intra-Articular Injectable Biomaterials for Cartilage Repair and Regeneration

Osteoarthritis is a degenerative joint disease characterized by cartilage deterioration and subsequent inflammatory changes in the underlying bone. Injectable hydrogels have emerged as a promising approach for controlled drug delivery in cartilage therapies. This review focuses on the latest developments in utilizing injectable hydrogels as vehicles for targeted drug delivery to promote cartilage repair and regeneration. The pathogenesis of osteoarthritis is discussed to provide a comprehensive understanding of the disease progression. Subsequently, the various types of injectable hydrogels used for intra-articular delivery are discussed. Specifically, physically and chemically crosslinked injectable hydrogels are critically analyzed, with an emphasis on their fabrication strategies and their capacity to encapsulate and release therapeutic agents in a controlled manner. Furthermore, the potential of incorporating growth factors, anti-inflammatory drugs, and cells within these injectable hydrogels are discussed. Overall, this review offers a comprehensive guide to navigating the landscape of hydrogel-based therapeutics in osteoarthritis.

An Accelerated PETALUTE MRI Sequence for In Vivo Quantification of Sodium Content in Human Articular Cartilage at 3T

In this work, we demonstrate the sodium magnetic resonance imaging (MRI) capabilities of a three-dimensional (3D) dual-echo ultrashort echo time (UTE) sequence with a novel rosette petal trajectory (PETALUTE), in comparison to the 3D density-adapted (DA) radial spokes UTE sequence. We scanned five healthy subjects using a 3D dual-echo PETALUTE acquisition and two comparable implementations of 3D DA-radial spokes acquisitions, one matching the number of k-space projections (Radial-Matched Trajectories) and the other matching the total number of samples (Radial-Matched Samples) acquired in k-space. The PETALUTE acquisition enabled equivalent sodium quantification in articular cartilage volumes of interest (168.8 ± 29.9 mM) to those derived from the 3D radial acquisitions (171.62 ± 28.7 mM and 149.8 ± 22.2 mM, respectively). We achieved a shorter scan time of 2:06 for 3D PETALUTE, compared to 3:36 for 3D radial acquisitions. We also evaluated the feasibility of further acceleration of the PETALUTE sequence through retrospective compressed sensing with 2× and 4× acceleration of the first echo and showed structural similarity of 0.89 ± 0.03 and 0.87 ± 0.03 when compared to non-retrospectively accelerated reconstruction. Together, these results demonstrate improved scan time with equivalent performance of the PETALUTE sequence compared to the 3D DA-radial sequence for sodium MRI of articular cartilage.

Is seborrheic dermatitis associated with early-stage osteoarthritis?

Seborrheic dermatitis (SD) and osteoarthritis involve similar factors in their pathogenesis. Both of these diseases are associated with an increased frequency of metabolic syndrome and underlying systemic inflammation. This study evaluated the thickness of the distal femoral cartilage using ultrasonography in patients with SD. The study enrolled 60 patients with SD (19 females and 41 males, mean age: 34.07 ± 12.56 years) and 60 controls matched for age and sex (20 females and 40 males, mean age: 35.08 ± 12.78 years). Ultrasonography was used to measure the distal femoral cartilage thickness (FCT) of the right medial condyle, right lateral condyle, right intercondylar area, left medial condyle, left lateral condyle, and left intercondylar area. FCT values at all points were significantly higher in patients with SD than in the controls (P < .05). Further, all FCT values were significantly higher in patients with moderate SD than in those with mild SD (P < .001). A strong positive correlation was observed between disease severity and FCT measured at right medial condyle (r = .7, P < .001), right lateral condyle (r = .749, P < .001), right intercondylar area (r = .79, P < .001), left medial condyle (r = .624, P < .001), and left intercondylar area (r = .703, P < .001). Further, a moderately positive correlation was observed between disease severity and FCT measured at left lateral condyle (r = .581, P < .001). Increased FCT in patients with SD might be an early indicator of osteoarthritis. However, further studies, especially those evaluating older patients with SD, are required to support our findings.

Intra-articular administration of PLGA resveratrol sustained-release nanoparticles attenuates the development of rat osteoarthritis

Our previous studies have confirmed that resveratrol (RSV) can prevent the development of osteoarthritis through a variety of mechanisms, such as apoptosis inhibition, autophagy induction and SIRT 1 activation. However, the pharmaceutical application of RSV is mainly limited by its low bioavailability. Here, we designed and synthesized RSV-loaded poly (D, l-lactide-coglycolide acid) (PLGA)-nanoparticles (NPs). The average particle size, polydispersity index and positive charge of RSV-loaded PLGA NPs were 50.40 nm, 0.217 and 12.57 mV, respectively. These nanoparticles had marked encapsulation efficiency (92.35 %) and drug loading (15.1 %) for RSV. It was found that RSV-loaded PLGA NPs not only inhibited the apoptosis of chondrocytes induced by IL-1, but also rescued GAG loss in vitro. Pharmacokinetic data showed that RSV-loaded PLGA NPs demonstrated a significantly profound and prolonged concentration profile in joint tissues, with quantifiable RSV concentrations over 35 days. The therapeutic effects of RSV-loaded PLGA NPs were then examined in rat osteoarthritis models. In vitro magnetic resonance imaging results showed that RSV-loaded PLGA NPs treatment dramatically reduced both T1ρ and T2 relaxation times at 4, 8, 12 weeks during administration, implying that cartilage destruction was alleviated. Histological assessments showed that RSV-loaded PLGA NPs significantly improved osteoarthritis symptoms. Gene expression analysis revealed that osteoarthritis mediator genes were downregulated in rats treated with RSV-PLGA NPs. Mechanistic studies indicated that RSV-loaded PLGA NPs inhibit apoptosis and promote autophagy. Collectively, this study demonstrates that intra-articular delivery of RSV via PLGA NPs might be an effective therapeutic approach for osteoarthritis.

The effect of attending rehabilitation after traumatic knee joint injury on femoral articular cartilage morphology in collegiate rugby players with a history of intracapsular knee joint injury during two-year consecutive rugby seasons

Introduction

This present study aimed to compare ultrasonographic measures of femoral articular cartilage during two-year seasons between collegiate rugby players who have attended supervised rehabilitation following intracapsular knee joint injury and those without a history of knee injury.

Methods

Using a prospective observational study design, 12 male collegiate rugby players with a previous history of intracapsular knee joint injury who have received and completed supervised rehabilitation following their injury and 44 players without knee joint injury participated in this study. Ultrasonographic images were used to verify changes in femoral articular cartilage thickness and cross-sectional area (CSA) with or without a previous history of knee joint injury over two consecutive rugby seasons.

Results

Significant time main effects were observed for the lateral condylar thickness (p < 0.001), the intercondylar thickness (p = 0.001), the medial condylar thickness (p < 0.001), and CSA (p < 0.001). No significant interactions nor group main effects were identified for all femoral articular cartilage (p < 0.05).

Conclusions

Collegiate rugby players demonstrated a decrease in femoral articular cartilage thickness and CSA over two-year consecutive rugby seasons. These findings indicate that engaging in collegiate rugby induces alterations in femoral articular cartilage structure. Furthermore, there were no differences in all femoral cartilage outcome measures between rugby players with and without a previous history of traumatic knee joint injury. Therefore, attending supervised rehabilitation at the time of their knee joint injury appeared to reduce the impact of a previous history of intracapsular knee joint injury on the change in femoral articular cartilage thickness and CSA among active rugby players.

Mice heterozygous for an osteogenesis imperfecta-linked MBTPS2 variant display a compromised subchondral osteocyte lacunocanalicular network associated with abnormal articular cartilage

Missense variants in the MBTPS2 gene, located on the X chromosome, have been associated with an X-linked recessive form of osteogenesis imperfecta (X-OI), an inherited bone dysplasia characterized by multiple and recurrent bone fractures, short stature, and various skeletal deformities in affected individuals. The role of site-2 protease, encoded by MBTPS2, and the molecular pathomechanism underlying the disease are to date elusive. This study is the first to report on the generation of two Mbtps2 mouse models, a knock-in mouse carrying one of the disease-causative MBTPS2 variants (N455S) and a Mbtps2 knock-out (ko) mouse. Because both loss-of-function variants lead to embryonic lethality in hemizygous male mutant mice, we performed a comprehensive skeletal analysis of heterozygous Mbtps2+/N455S and Mbtps2+/ko female mice. Both models displayed osteochondral abnormalities such as thinned subchondral bone, altered subchondral osteocyte interconnectivity as well as thickened articular cartilage with chondrocyte clustering, altogether resembling an early osteoarthritis (OA) phenotype. However, distant from the joints, no alterations in the bone mass and turnover could be detected in either of the mutant mice. Based on our findings we conclude that MBTPS2 haploinsufficiency results in early OA-like alterations in the articular cartilage and underlying subchondral bone, which likely precede the development of typical OI phenotype in bone. Our study provides first evidence for a potential role of site-2 protease for maintaining homeostasis of both bone and cartilage.

Charting Aging Trajectories of Knee Cartilage Thickness for Early Osteoarthritis Risk Prediction: An MRI Study from the Osteoarthritis Initiative Cohort

Knee osteoarthritis (OA), a prevalent joint disease in the U.S., poses challenges in terms of predicting of its early progression. Although high-resolution knee magnetic resonance imaging (MRI) facilitates more precise OA diagnosis, the heterogeneous and multifactorial aspects of OA pathology remain significant obstacles for prognosis. MRI-based scoring systems, while standardizing OA assessment, are both time-consuming and labor-intensive. Current AI technologies facilitate knee OA risk scoring and progression prediction, but these often focus on the symptomatic phase of OA, bypassing initial-stage OA prediction. Moreover, their reliance on complex algorithms can hinder clinical interpretation. To this end, we make this effort to construct a computationally efficient, easily-interpretable, and state-of-the-art approach aiding in the radiographic OA (rOA) auto-classification and prediction of the incidence and progression, by contrasting an individual's cartilage thickness with a similar demographic in the rOA-free cohort. To better visualize, we have developed the toolset for both prediction and local visualization. A movie demonstrating different subtypes of dynamic changes in local centile scores during rOA progression is available at https://tli3.github.io/KneeOA/. Specifically, we constructed age-BMI-dependent reference charts for knee OA cartilage thickness, based on MRI scans from 957 radiographic OA (rOA)-free individuals from the Osteoarthritis Initiative cohort. Then we extracted local and global centiles by contrasting an individual's cartilage thickness to the rOA-free cohort with a similar age and BMI. Using traditional boosting approaches with our centile-based features, we obtain rOA classification of KLG ≤ 1 versus KLG = 2 (AUC = 0.95, F1 = 0.89), KLG ≤ 1 versus KLG ≥ 2 (AUC = 0.90, F1 = 0.82) and prediction of KLG2 progression (AUC = 0.98, F1 = 0.94), rOA incidence (KLG increasing from < 2 to ≥ 2; AUC = 0.81, F1 = 0.69) and rOA initial transition (KLG from 0 to 1; AUC = 0.64, F1 = 0.65) within a future 48-month period. Such performance in classifying KLG ≥ 2 matches that of deep learning methods in recent literature. Furthermore, its clinical interpretation suggests that cartilage changes, such as thickening in lateral femoral and anterior femoral regions and thinning in lateral tibial regions, may serve as indicators for prediction of rOA incidence and early progression. Meanwhile, cartilage thickening in the posterior medial and posterior lateral femoral regions, coupled with a reduction in the central medial femoral region, may signify initial phases of rOA transition.

Medial Meniscus Posterior Root Repair Reduces but Does Not Avoid Histologic Progression of Osteoarthritis: Randomized In Vivo Experimental Study in a Rabbit Model

BACKGROUND

The optimal treatment option for meniscus root tears is still challenging, and whether the meniscus root repair ultimately can arrest or delay osteoarthritic changes is still a concern.

PURPOSE/HYPOTHESIS

The purpose of this study was 2-fold: (1) to describe and compare histopathologic findings of 3 different therapeutic options for medial meniscus posterior root tear: nonoperative management, partial meniscectomy, and meniscus root repair; and (2) to test the hypothesis that meniscus root tears treated nonoperatively predispose to a lower risk of osteoarthritic progression compared with partial meniscectomy.

STUDY DESIGN

Controlled laboratory study.

METHODS

Posteromedial meniscus root tears were carried out in 39 New Zealand White rabbits. Animals were randomly assigned into 3 experimental groups: partial meniscectomy after root tear (PM; n = 13), root tears treated conservatively (CT; n = 13), and transtibial root repair (RR; n = 13). Contralateral limbs were used as healthy controls. The animals were euthanized at 16 weeks postoperatively; tissue samples of femoral and tibial articular cartilage were collected and processed for macro- and microscopic assessment to detect signs of early osteoarthritis (OA). Each sample was histopathologically assessed using the Osteoarthritis Research Society International grading and staging system.

RESULTS

Osteoarthritic changes were the hallmark in all 3 experimental groups. The RR group had the lowest scores for cartilage damage (mean, 2.5; range, 2-3), and the PM group exhibited higher and more severe signs of OA (mean, 16; range, 9-16) compared with the CT group (mean, 5; range, 4-6). The between-group comparison revealed significant differences, as the PM group showed a significantly higher rate of macro- and microscopic osteoarthritic changes compared with the RR (P < .001) and CT (P < .001) groups. The weightbearing area of the medial femoral condyle was the most severely affected, and tidemark disruption was evident in all tissue samples.

CONCLUSION

Meniscus root repair cannot completely arrest the histopathologic progression of knee OA but leads to significantly less severe degenerative changes than partial meniscectomy and nonoperative treatment. Partial meniscectomy leads to the most severe osteoarthritic progression, while stable radial tears left in situ have lower progression compared with partial meniscectomy.

CLINICAL RELEVANCE

Histologic assessment is an essential tool and metric for guiding and understanding osteoarthritic features, providing insight into the disease development and progression. This study provides histopathologic evidence on osteoarthritic progression after medial meniscus posterior root repair. This knowledge can help to set more realistic expectations and can lead to the future development of augmented techniques.

Physical Activity and Features of Knee Osteoarthritis on Magnetic Resonance Imaging in Individuals Without Osteoarthritis: A Systematic Review

OBJECTIVE

To systematically review all studies that have evaluated the association between physical activity (PA) levels and features of knee osteoarthritis (OA) on magnetic resonance imaging (MRI) for subjects without OA.

METHODS

The inclusion criteria for prospective studies were as follows: 1) subjects without OA; 2) average age 35-80 years; and 3) any self-reported PA or objective measurement of PA. The eligible MRI outcomes were OA-related measures of intraarticular knee joint structures. Exclusion criteria were evaluations of instant associations with transient structural changes after PA.

RESULTS

Two randomized controlled trials and 16 observational studies were included. One of 11 studies found that PA was harmfully related to cartilage volume or thickness, but 4 studies found a significant protective association. Four of 10 studies found that PA was harmfully related to cartilage defects, while others showed no significant associations. Two of 3 studies reported a significantly increased cartilage T2 value in individuals with more PA. All 3 studies reported no significant association between PA and bone marrow lesions. Two studies assessed the association between PA and meniscus pathology, in which only occupational PA involving knee bending was associated with a greater risk of progression.

CONCLUSION

Within the sparse and diverse evidence available, no strong evidence was found for the presence or absence of an association between PA and the presence or progression of features of OA on MRI among subjects without OA. Therefore, more research is required before PA in general and also specific forms of PA can be deemed safe for knee joint structures.

Ultrashort time-to-echo MR morphology of cartilaginous endplate correlates with disc degeneration in the lumbar spine

PURPOSE

Using ultrashort echo time (UTE) MRI, we determined prevalence of abnormal cartilaginous endplate (CEP), and the relationship between CEP and disc degeneration in human lumbar spines.

MATERIALS AND METHODS

Lumbar spines from 71 cadavers (age 14-74 years) were imaged at 3 T using sagittal UTE and spin echo T2 map sequences. On UTE images, CEP morphology was defined as "normal" with linear high signal intensity or "abnormal" with focal signal loss and/or irregularity. On spin echo images, disc grade and T2 values of the nucleus pulposus (NP) and annulus fibrosus (AF) were determined. 547 CEPs and 284 discs were analysed. Effects of age, sex, and level on CEP morphology, disc grade, and T2 values were determined. Effects of CEP abnormality on disc grade, T2 of NP, and T2 of AF were also determined.

RESULTS

Overall prevalence of CEP abnormality was 33% and it tended to increase with older ages (p = 0.08) and at lower spinal levels of L5 than L2 or L3 (p = 0.001). Disc grades were higher and T2 values of the NP were lower in older spines (p < 0.001) and at lower disc level of L4-5 (p < 0.05). We found significant association between CEP and disc degeneration; discs adjacent to abnormal CEPs had high grades (p < 0.01) and lower T2 values of the NP (p < 0.05).

CONCLUSION

These results suggest that abnormal CEPs are frequently found, and it associates significantly with disc degeneration, suggesting an insight into pathoetiology of disc degeneration.

DHA attenuates cartilage degeneration by mediating apoptosis and autophagy in human chondrocytes and rat models of osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease that usually occurs in the elderly, and docosahexaenoic acid (DHA) plays a therapeutic role in cardiovascular disease, diabetes, and rheumatoid arthritis (RA) with its anti-inflammatory and antioxidant effects. The objective of this study is to investigate the effect and mechanism of DHA on hypertrophic differentiation and senescence of OA chondrocytes to provide a theoretical basis for the effect of OA clinical treatment. A human OA chondrocyte model was established by IL-1β, and a rat model of OA was established by anterior cruciate ligament (ACL) transection and medial meniscectomy. The result showed DHA promoted chondrocyte proliferation and reduced apoptosis. Transmission electron microscopy (TEM) analysis showed that there were more autophagosomes in the cytoplasm under the treatment of DHA. Compared to the OA group, samples from the OA + DHA group showed thickened cartilage, reduced degeneration, and an increased rate of collagen II-positive cells, while the Mankin score was significantly lower. In addition, DHA decreased the expression of phosphorylated mammalian target of rapamycin (p-mTOR) and the ratio of light chain 3-I/II (LC3-I/II) and increased the expression of Beclin-1 and Bcl-2 measured by western blot analysis. Therefore, DHA promotes chondrocyte proliferation, reduces apoptosis, and increases autophagy in OA chondrocytes, a process that is accomplished by inhibiting the expression of mTOR, c-Jun N-terminal kinase (JNK), and p38 signaling pathways, providing new perspectives and bootstrap points for the prevention and treatment of OA.

Healthy and Osteoarthritis-Affected Joints Facing the Cellular Crosstalk

Osteoarthritis (OA) is a chronic, progressive, severely debilitating, and multifactorial joint disease that is recognized as the most common type of arthritis. During the last decade, it shows an incremental global rise in prevalence and incidence. The interaction between etiologic factors that mediate joint degradation has been explored in numerous studies. However, the underlying processes that induce OA remain obscure, largely due to the variety and complexity of these mechanisms. During synovial joint dysfunction, the osteochondral unit undergoes cellular phenotypic and functional alterations. At the cellular level, the synovial membrane is influenced by cartilage and subchondral bone cleavage fragments and extracellular matrix (ECM) degradation products from apoptotic and necrotic cells. These "foreign bodies" serve as danger-associated molecular patterns (DAMPs) that trigger innate immunity, eliciting and sustaining low-grade inflammation in the synovium. In this review, we explore the cellular and molecular communication networks established between the major joint compartments-the synovial membrane, cartilage, and subchondral bone of normal and OA-affected joints.

The effect of ferritin levels on distal femoral cartilage thickness in patients with beta thalassaemia major

INTRODUCTION

To the best of our knowledge, the present study is the first in the literature to assess distal femoral cartilage thickness and its relationship with ferritin levels in adult patients with beta thalassaemia major (BTM).

MATERIALS AND METHODS

45 patients with BTM and 45 healthy controls were included in the study. Ferritin and haemoglobin levels of the patient and healthy groups were determined by blood analysis and distal femoral cartilage thicknesses were measured via ultrasound. Then, the patient group was divided into subgroups according to whether their ferritin levels were below or above 2500 µg/L. They were then compared among themselves and with the healthy control group using the available data.

RESULTS

Distal femoral cartilage thickness values were statistically significantly lower in the BTM group compared to the healthy control group (p values < 0.001). Patients with a ferritin level below 2500 µg/L had statistically significantly higher right and left average distal femoral cartilage thickness values than the patients with a ferritin level above 2500 µg/L (p = 0.029 and p = 0.019, respectively). The right and left average distal femoral cartilage thickness values of the patient subgroup with low ferritin levels were statistically similar to the control group (p = 0.146 and p = 0.164, respectively).

CONCLUSION

Our study showed that thalassaemia patients are more likely to develop osteoarthritis (OA) than the normal population and possible OA development can be prevented by keeping the ferritin levels of these patients in the optimum range.

Contrast-enhanced micro-computed tomography of compartment and time-dependent changes in femoral cartilage and subchondral plate in a murine model of osteoarthritis

A lack of understanding of the mechanisms underlying osteoarthritis (OA) progression limits the development of effective long-term treatments. Quantitatively tracking spatiotemporal patterns of cartilage and bone degeneration is critical for assessment of more appropriately targeted OA therapies. In this study, we use contrast-enhanced micro-computed tomography (μCT) to establish a timeline of subchondral plate (SCP) and cartilage changes in the murine femur after destabilization of the medial meniscus (DMM). We performed DMM or sham surgery in 10-12-week-old male C57Bl/6J mice. Femora were imaged using μCT after 0, 2, 4, or 8 weeks. Cartilage-optimized scans were performed after immersion in contrast agent CA4+. Bone mineral density distribution (BMDD), cartilage attenuation, SCP, and cartilage thickness and volume were measured, including lateral and medial femoral condyle and patellar groove compartments. As early as 2 weeks post-DMM, cartilage thickness significantly increased and cartilage attenuation, SCP volume, and BMDD mean significantly decreased. Trends in cartilage and SCP metrics within each joint compartment reflected those seen in global measurements, and both BMDD and SCP thickness were consistently greater in the lateral and medial condyles than the patellar groove. Sham surgery also resulted in significant changes to SCP and cartilage metrics, highlighting a potential limitation of using surgical models to study tissue morphology or composition changes during OA progression. Contrast-enhanced μCT analysis is an effective tool to monitor changes in morphology and composition of cartilage, and when combined with bone-optimized μCT, can be used to assess the progression of degenerative changes after joint injury.

Developing an experimental model of early knee osteoarthritis after medial meniscus posterior root release: an in vivo study

Purpose

To develop a predictable and reproducible model of knee osteoarthritis after medial meniscus posterior root release.

Methods

Posteromedial meniscal root tears were created in 12 White New Zealand rabbit knees. The contralateral limbs were used as healthy controls. The animals were euthanized at 16 weeks postoperatively; tissue samples of femoral and tibial articular cartilage were collected and processed for macro and microscopic analyses to detect signs of early degeneration. Clinical evaluation of the weight-bearing status on the affected knee was conducted at 0-, 4-, 8-, and 16-weeks postoperatively.

Results

Early and severe osteoarthritic changes were the hallmark and the main findings after 16-weeks post-surgery. Macroscopically, extensive osteoarthritic changes were observed across the femoral condyle and tibial plateau. Microscopic finding included ulcerations, fissures, fibrillations, pitting, and loss of the superficial layer. Cellularity was diminished, the normal pattern of distribution in columns was lost, and subchondral bone exposure was also evident.

Conclusions

This study describes a novel model of knee osteoarthritis that may guide the development of tailored interventions to delay or prevent knee osteoarthritis. This knowledge could shift the current treatment paradigm toward more conservative and knee salvageable treatment options and increase surgeons’ awareness of this injury pattern. Such considerations may have a positive impact on clinical decision-making and subsequent patient-reported clinical outcomes.

Design

Controlled laboratory study.

Level of evidence

II.

Quadriceps muscle strength at 2 years following anterior cruciate ligament reconstruction is associated with tibiofemoral joint cartilage volume

PURPOSE

Quadriceps strength deficits following anterior cruciate ligament reconstruction (ACLR) are linked to altered lower extremity biomechanics, tibiofemoral joint (TFJ) space narrowing and cartilage composition changes. It is unknown, however, if quadriceps strength is associated with cartilage volume in the early years following ACLR prior to the onset of posttraumatic osteoarthritis (OA) development. The purpose of this cross-sectional study was to examine the relationship between quadriceps muscle strength (peak and across the functional range of knee flexion) and cartilage volume at ~ 2 years following ACLR and determine the influence of concomitant meniscal pathology.

METHODS

The involved limb of 51 ACLR participants (31 isolated ACLR; 20 combined meniscal pathology) aged 18-40 years were tested at 2.4 ± 0.4 years post-surgery. Isokinetic knee extension torque generated in 10° intervals between 60° and 10° knee flexion (i.e. 60°-50°, 50°-40°, 40°-30°, 30°-20°, 20°-10°) together with peak extension torque were measured. Tibial and patellar cartilage volumes were measured using magnetic resonance imaging (MRI). The relationships between peak and angle-specific knee extension torque and MRI-derived cartilage volumes were evaluated using multiple linear regression.

RESULTS

In ACLR participants with and without meniscal pathology, higher knee extension torques at 60°-50° and 50°-40° knee flexion were negatively associated with medial tibial cartilage volume (p < 0.05). No significant associations were identified between peak concentric or angle-specific knee extension torques and patellar cartilage volume.

CONCLUSION

Higher quadriceps strength at knee flexion angles of 60°-40° was associated with lower cartilage volume on the medial tibia ~ 2 years following ACLR with and without concomitant meniscal injury. Regaining quadriceps strength across important functional ranges of knee flexion after ACLR may reduce the likelihood of developing early TFJ cartilage degenerative changes.

LEVEL OF EVIDENCE

III.

Subchondral versus intra-articular orthobiologic injections for the treatment of knee osteoarthritis: a review

Recent perspectives suggest that osteoarthritis (OA) is a disease involving not only the articular cartilage but also the osteochondral unit, including the synovium, supportive cartilage and subchondral bone. Current conservative treatments for OA are symptomatic and do not prevent progression or reverse the disease process. Compelling data show that intra-articular orthobiologic injections, such as platelet-rich plasma and mesenchymal stromal cells, are effective in providing relief of OA symptoms. However, recent data suggest that injections of orthobiologics into the subchondral bone may be superior to intra-articular injections for the management of OA. This review highlights the rationale and current evidence for intra-articular and subchondral bone injections of orthobiologics for the treatment of OA.

Moving Beyond the Limits of Detection: The Past, the Present, and the Future of Diagnostic Imaging in Canine Osteoarthritis

Osteoarthritis (OA) is the most common orthopedic condition in dogs, characterized as the chronic, painful end-point of a synovial joint with limited therapeutic options other than palliative pain control or surgical salvage. Since the 1970s, radiography has been the standard-of-care for the imaging diagnosis of OA, despite its known limitations. As newer technologies have been developed, the limits of detection have lowered, allowing for the identification of earlier stages of OA. Identification of OA at a stage where it is potentially reversible still remains elusive, however, yet there is hope that newer technologies may be able to close this gap. In this article, we review the changes in the imaging of canine OA over the past 50 years and give a speculative view on future innovations which may provide for earlier identification, with the ultimate goal of repositioning the limit of detection to cross the threshold of this potentially reversible disease.

Light on osteoarthritic joint: from bench to bed

Osteoarthritis (OA) is one of the rapidly growing disability-associated conditions with population aging worldwide. There is a pressing need for precise diagnosis and timely intervention for OA in the early stage. Current clinical imaging modalities, including pain radiography, magnetic resonance imaging, ultrasound, and optical coherent tomography, are limited to provide structural changes when the damage has been established or advanced. It prompts further endeavors in search of novel functional and molecular imaging, which potentially enables early diagnosis and intervention of OA. A hybrid imaging modality based on photothermal effects, photoacoustic imaging, has drawn wide attention in recent years and has seen a variety of biomedical applications, due to its great performance in yielding high-contrast and high-resolution images from structure to function, from tissue down to molecular levels, from animals to human subjects. Photoacoustic imaging has witnessed gratifying potentials and preliminary effects in OA diagnosis. Regarding the treatment of OA, photothermal-triggered therapy has exhibited its attractions for enhanced therapeutic outcomes. In this narrative review, we will discuss photoacoustic imaging for the diagnosis and monitoring of OA at different stages. Structural, functional, and molecular parameter changes associated with OA joints captured by photoacoustics will be summarized, forming the diagnosis perspective of the review. Photothermal therapy applications related to OA will also be discussed herein. Lastly, relevant clinical applications and its potential solutions to extend photoacoustic imaging to deeper OA situations have been proposed. Although some aspects may not be covered, this mini review provides a better understanding of the diagnosis and treatment of OA with exciting innovations based on tissue photothermal effects. It may also inspire more explorations in the field towards earlier and better theranostics of OA.

Longitudinal Changes in Ultrasound-Assessed Femoral Cartilage Thickness in Individuals from 4 to 6 Months Following Anterior Cruciate Ligament Reconstruction

OBJECTIVE

Diagnostic ultrasound provides a valid assessment of cartilage health that has been used to observe cross-sectional cartilage thickness differences post-ACLR (anterior cruciate ligament reconstruction), but has not been used longitudinally during early recovery post-ACLR.

DESIGN

The purpose of this study was to assess longitudinal changes in femoral cartilage thickness via ultrasound in individuals at 4 to 6 months post-ACLR and compared to healthy controls. Twenty participants (50% female, age = 21.1 ± 5.7 years) completed testing sessions 4 and 6 months post-ACLR. Thirty healthy controls (57% female, age = 20.8 ± 3.8 years) without knee injury history completed 2 testing sessions (>72 hours apart). Femoral cartilage ultrasound images were captured bilaterally in ACLR participants and in the dominant limb of healthy controls during all sessions. Average cartilage thicknesses in the medial, intercondylar, and lateral femoral regions were determined using a semi-automated processing technique.

RESULTS

When comparing cartilage thickness mean differences or changes over time, individuals post-ACLR did not demonstrate between limb differences (P-range = 0.50-0.92), limb differences compared to healthy controls (P-range = 0.19-0.94), or changes over time (P-range = 0.22-0.72) for any femoral cartilage thickness region. However, participants demonstrated cartilage thickening (45%) or thinning (35%) that exceeded minimal detectable change (MDC) from 4 to 6 months post-ACLR, respectively.

CONCLUSIONS

Using MDC scores may help better identify within-subject femoral cartilage thickness changes longitudinally post-ACLR due to bidirectional cartilage thickness changes.

Knee Cartilage Imaging

Articular cartilage injury and degeneration represent common causes of knee pain, which can be evaluated accurately and noninvasively using MRI. This review describes the structure of cartilage focusing on its histologic appearance to emphasize that structure will dictate patterns of tissue failure as well as MR appearance. In addition to identifying cartilage loss, MRI can demonstrate signal changes that correspond to intrinsic structural abnormalities which place the cartilage at risk for subsequent more serious injury or premature degeneration, allowing for earlier intervention and treatment of important causes of pain and morbidity.

Biomechanics of the Femoral Head Cartilage and Subchondral Trabecular Bone in Osteoporotic and Osteopenic Fractures

This study aimed to investigate the relationship between the micro structural properties of the subchondral trabecular bone (STB) and the macro mechanical properties of the articular cartilage (AC) in patients with osteoporotic (OP) and osteopenic (OPE) fractures. Sixteen femoral head samples (OP;OPE, n = 8 each) were obtained from female patients who underwent hip hemiarthroplasty. STB and AC specimens were harvested from those heads. Bone specimens were scanned using µ-CT to determine the micro structural properties. In-situ nondestructive compressive tests were performed for the cartilages to obtain elastic properties. The finite element technique was implemented on STB models created from µ-CT data to compute apparent elastic modulus. In addition, dynamic cyclic destructive tests were performed on STB and AC specimens to assess failure cycles. The results demonstrated that STB specimens in OPE group have more interconnected structure and higher cyclic dynamic strength than those in OP group. Furthermore, bone mineral density, failure cycle, and trabecular number of STB were positively correlated with the cartilage failure cycle, which indicates that STB alteration may affect the macroscopic mechanical properties of AC. The findings suggest that STB loss correlates with a decrease in cartilage strength and that improving of bone quality may prevent cartilage weakness.

The Diagnostic Yield of Cone-Beam Computed Tomography for Degenerative Changes of the Temporomandibular Joint in Dogs

Degenerative changes of the temporomandibular joint (DTMJ) may be diagnosed via cone - beam computed tomography (CBCT). However, despite advancement in CBCT imaging, correlation of DTMJ features identified on CBCT with gross and histological findings is currently limited. This study aimed to correlate CBCT findings of DTMJ of dogs with gross and histopathologic changes. Temporomandibular joints (TMJ) (n = 38) from fresh cadaver heads of asymptomatic dogs (n = 19) were examined radiologically, macroscopically, and microscopically. Association of CBCT - detected DTMJ changes with gross and histological findings were statistically evaluated via kappa statistics and ordinal logistic mixed-effects models. The radiological changes observed on CBCT included joint space narrowing, subchondral/cortical bone changes (i.e., erosions or lysis), osteophytes, and subchondral bone sclerosis. Upon macroscopic evaluation, the majority of examined specimens had mild changes with cartilage defects and osteophytes affecting <10% of the total articular surface area. Histopathologic changes comprised splitting and degeneration of the fibrous cartilage layers, subchondral bone exposure, subchondral bone sclerosis, focal subchondral bone lysis, and occasional cell death. Subchondral sclerosis was the most prevalent finding radiologically and histologically with a fair to excellent agreement. Importantly, the more severe the TMJ degenerative changes, the higher the agreement between CBCT and histology. Based on the correlative results of statistical analysis, CBCT was found to be a suitable modality to evaluate DTMJ.

The role of TGF-β2 in cartilage development and diseases

Transforming growth factor-beta2 (TGF-β2) is recognized as a versatile cytokine that plays a vital role in regulation of joint development, homeostasis, and diseases, but its role as a biological mechanism is understood far less than that of its counterpart, TGF-β1. Cartilage as a load-resisting structure in vertebrates however displays a fragile performance when any tissue disturbance occurs, due to its lack of blood vessels, nerves, and lymphatics. Recent reports have indicated that TGF-β2 is involved in the physiological processes of chondrocytes such as proliferation, differentiation, migration, and apoptosis, and the pathological progress of cartilage such as osteoarthritis (OA) and rheumatoid arthritis (RA). TGF-β2 also shows its potent capacity in the repair of cartilage defects by recruiting autologous mesenchymal stem cells and promoting secretion of other growth factor clusters. In addition, some pioneering studies have already considered it as a potential target in the treatment of OA and RA. This article aims to summarize the current progress of TGF-β2 in cartilage development and diseases, which might provide new cues for remodelling of cartilage defect and intervention of cartilage diseases.

Diagnostic Role of Magnetic Resonance Imaging in Low Back Pain Caused by Vertebral Endplate Degeneration

Low back pain (LBP) is a common health issue worldwide with a huge economic burden on healthcare systems. In the United States alone, the cost is estimated to be $100 billion each year. Intervertebral disc degeneration is considered one of the primary causes of LBP. Moreover, the critical role of the vertebral endplates in disc degeneration and LBP is becoming apparent. Endplate abnormalities are closely correlated with disc degeneration and pain in the lumbar spine. Imaging modalities such as plain film radiography, computed tomography, and fluoroscopy are helpful but not very effective in detecting the causes behind LBP. Magnetic resonance imaging (MRI) can be used to acquire high-quality three-dimensional images of the lumbar spine without using ionizing radiation. Therefore, it is increasingly being used to diagnose spinal disorders. However, according to the American College of Radiology, current referral and justification guidelines for MRI are not sufficiently clear to guide clinical practice. This review aimed to evaluate the role of MRI in diagnosing LBP by considering the correlative contributions of vertebral endplates. The findings of the review indicate that MRI allows for fine evaluations of endplate morphology, endplate defects, diffusion and perfusion properties of the endplate, and Modic changes. Changes in these characteristics of the endplate were found to be closely correlated with disc degeneration and LBP. The collective evidence from the literature suggests that MRI may be the imaging modality of choice for patients suffering from LBP. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 3.

Primary Osteoarthritis Early Joint Degeneration Induced by Endoplasmic Reticulum Stress Is Mitigated by Resveratrol

Increasing numbers of people are living with osteoarthritis (OA) due to aging and obesity, creating an urgent need for effective treatment and preventions. Two top risk factors for OA, age and obesity, are associated with endoplasmic reticulum (ER) stress. The I-ERS mouse, an ER stress-driven model of primary OA, was developed to study the role of ER stress in primary OA susceptibility. The I-ERS mouse has the unique ability to induce ER stress in healthy adult articular chondrocytes and cartilage, driving joint degeneration that mimics early primary OA. In this study, ER stress-induced damage occurred gradually and stimulated joint degeneration with OA characteristics including increased matrix metalloproteinase activity, inflammation, senescence, chondrocyte death, decreased proteoglycans, autophagy block, and gait dysfunction. Consistent with human OA, intense exercise hastened and increased the level of ER stress-induced joint damage. Notably, loss of a critical ER stress response protein (CHOP) largely ameliorated ER stress-stimulated OA outcomes including preserving proteoglycan content, reducing inflammation, and relieving autophagy block. Resveratrol diminished ER stress-induced joint degeneration by decreasing CHOP, TNFα, IL-1β, MMP-13, pS6, number of TUNEL-positive chondrocytes, and senescence marker p16 INK4a. The finding, that a dietary supplement can prevent ER stressed-induced joint degeneration in mice, provides a preclinical foundation to potentially develop a prevention strategy for those at high risk to develop OA.

Towards understanding mechanistic subgroups of osteoarthritis: 8-year cartilage thickness trajectory analysis

Many studies have validated cartilage thickness as a biomarker for knee osteoarthritis (OA); however, few studies investigate beyond cross-sectional observations or comparisons across two timepoints. By characterizing the trajectory of cartilage thickness changes over 8 years in healthy individuals from the OA initiative data set, this study discovers associations between the dynamics of cartilage changes and OA incidence. A fully automated cartilage segmentation and thickness measurement method were developed and validated against manual measurements: mean absolute error = 0.11-0.14 mm (n = 4129 knees) and automatic reproducibility = 0.04-0.07 mm (n = 316 knees). The mean thickness for the medial and lateral tibia (MT, LT), central weight-bearing medial and lateral femur (cMF, cLF), and patella (P) cartilage compartments were quantified for 1453 knees at seven timepoints. Trajectory subgroups were defined per cartilage compartment such as stable, thinning to thickening, accelerated thickening, plateaued thickening, thickening to thinning, accelerated thinning, or plateaued thinning. For tibiofemoral compartments, the stable (22%-36%) and plateaued thinning (22%-37%) trajectories were the most common, with an average initial velocity (μm/month), acceleration (μm/month² ) for the plateaued thinning trajectories LT: -2.66, 0.0326; MT: -2.49, 0.0365; cMF: -3.51, 0.0509; and cLF: -2.68, 0.041. In the patella compartment, the plateaued thinning (35%) and thickening to thinning (24%) trajectories were the most common, with an average initial velocity, acceleration for each -4.17, 0.0424; 1.95, -0.0835. Knees with nonstable trajectories had higher adjusted odds of OA incidence than stable trajectories: accelerated thickening, accelerated thinning, and plateaued thinning trajectories of the MT had adjusted odds ratio (OR) of 18.9, 5.48, and 1.47, respectively; in the cMF, adjusted OR of 8.55, 10.1, and 2.61, respectively.

Polycystic ovary syndrome and (pre)osteoarthritis: assessing the link between hyperandrogenism in young women and cartilage oligomeric matrix protein as a marker of cartilage breakdown

INTRODUCTION

OBJECTIVES: Our aim was to analyze the link between hyperandrogenism and early clinical manifestations of osteoarthritis (OA), knee cartilage thickness, and serum cartilage oligomeric matrix protein (sCOMP) levels in patients with polycystic ovary syndrome (PCOS) and to compare them with healthy volunteers.

METHODS

Fifty-four PCOS patients who met the Rotterdam criteria with phenotypes A, B, and C were included. They were compared with 26 age- and body mass index (BMI)-matched controls. Detailed anthropometric measurements and clinical evaluation for hyperandrogenism were performed for all participants who also filled in the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Furthermore, laboratory tests including sCOMP and hormone quantification were performed in a fasting stage. Finally, an ultrasound assessment was carried out in randomly selected 56 study participants.

RESULTS

PCOS women reported more prominent knee-related symptoms (p = 0.035) and more impaired activities of daily living (ADL) (p = 0.001) than controls. Cartilage thickness of the left and right medial condyle and left lateral condyle was significantly greater in PCOS group (n = 41) than in control group (n = 15) (p = 0.05, p = 0.006, and p = 0.036, respectively). COMP correlated significantly and negatively with testosterone levels (p = 0.029, r =  - 0.297) in women with PCOS and the correlation remained significant after controlling for BMI.

CONCLUSIONS

Women with PCOS may experience knee-related symptoms and impaired ADL. They had greater knee femoral cartilage thickness. Although sCOMP levels did not significantly differ between the groups, lower levels of sCOMP may be inherent to PCOS patients with higher testosterone levels. Key Points • Although PCOS patients may experience more prominent knee related symptoms, their femoral cartilage of the knee joint is found thicker than controls. • PCOS patients did not have significantly elevated levels of sCOMP. • Lower sCOMP levels were related to higher testosterone levels.

Quantitative measures of bone shape, cartilage morphometry and joint alignment are associated with disease in an ACLT and MMx rat model of osteoarthritis

Multi-scale, subject-specific quantitative methods to characterize and monitor osteoarthritis in animal models and therapeutic treatments could help reveal causal relationships in disease development and distinguish treatment strategies. In this work, we demonstrate a reproducible and sensitive quantitative image analysis to characterize bone, cartilage and joint measures describing a rat model of post-traumatic osteoarthritis. Eleven 3-month-old male Wistar rats underwent medial anterior cruciate ligament (ACL) transection and medial meniscectomy on the right knee to destabilise the right tibiofemoral joint. They were sacrificed 6 weeks post-surgery and a silicon-based micro-bead contrast agent was injected in the joint space, before scanning with micro-computed tomography (microCT). Subsequently, 3D quantitative morphometric analysis (QMA), previously developed for rabbit joints, was performed. This included cartilage, subchondral cortical and epiphyseal bone measures, as well as novel tibiofemoral joint metrics. Semi-quantitative evaluation was performed on matching two-dimensional (2D) histology and microCT images. Reproducibility of the QMA was tested on eleven age-matched additional joints. The results indicate the QMA method is accurate and reproducible and that microCT-derived cartilage measurements are valid for the analysis of rat joints. The pathologic changes caused by transection of the ACL and medial meniscectomy were reflected in measurements of bone shape, cartilage morphology, and joint alignment. Furthermore, we were able to identify model-specific predictive parameters based on morphometric parameters measured with the QMA.

Setting up distinctive outcome measures for each osteoarthritis phenotype

Osteoarthritis (OA) is an evolving chronic joint disease with a huge global impact. Given the intricate nature of the etiopathogenesis and subsequent high heterogeneity in the clinical course of OA, it is crucial to discriminate between etiopathogenic endotypes and clinical phenotypes, especially in the early stages of the disease. In this sense, we propose that an OA phenotype should be properly assessed with a set of outcome measures including those specifically related to the main underlying pathophysiological mechanisms. Thus, each OA phenotype can be related to different and clinically meaningful outcomes. OA phenotyping would lead to an adequate patient stratification in well-designed clinical trials and the discovery of precise therapeutic approaches. A significant effort will be required in this field in light of inconclusive results of clinical trials of tissue-targeting agents for the treatment of OA.

Morphological MRI of knee cartilage: repeatability and reproducibility of damage evaluation and correlation with gross pathology examination

OBJECTIVE

To assess the performance of a morphological evaluation, based on a clinically relevant magnetic resonance imaging (MRI) protocol, in scoring the severity of knee cartilage damage. Specifically, to evaluate the reproducibility, repeatability, and agreement of MRI evaluation with the gross pathology examination (GPE) of the tissue.

METHODS

MRI of the knee was performed the day before surgery in 23 patients undergoing total knee arthroplasty. Osteochondral tissue resections were collected and chondral defects were scored by GPE according to a semi-quantitative scale. MR images were independently scored by four radiologists, who assessed the severity of chondral damage according to equivalent criteria. Inter- and intra-rater agreements of MRI evaluations were assessed. Correlation, precision, and accuracy metrics between MRI and GPE scores were calculated.

RESULTS

Moderate to substantial inter-rater agreement in scoring cartilage damage by MRI was found among radiologists. Intra-rater agreement was higher than 96%. A significant positive monotonic correlation between GPE and MRI scores was observed for all radiologists, although higher correlation values were obtained by radiologists with expertise in musculoskeletal radiology and/or longer experience. The accuracy of MRI scores displayed a spatial pattern, characterized by lesion overestimation in the lateral condyle and underestimation in the medial condyle with respect to GPE.

CONCLUSIONS

Evaluation of knee cartilage morphology by MRI is a reproducible and repeatable technique, which positively correlates with GPE. Clinical expertise in musculoskeletal radiology positively impacts the evaluation reliability. These findings may help to address limitations in MRI evaluation of knee chondral lesions, thus improving MRI assessment of knee cartilage.

KEY POINTS

• MRI evaluation of knee cartilage shows moderate to strong correlation with gross pathology examination. • MRI evaluation overestimates cartilage damage in the lateral condyle and underestimates it in the medial condyle. • Education and experience of the radiologist play a role in MRI evaluation of knee chondral lesions.

Effects of treadmill running and limb immobilization on knee cartilage degeneration and locomotor joint kinematics in rats following knee meniscal transection

OBJECTIVE

This study examined the effects of reduced and elevated weight bearing on post-traumatic osteoarthritis (PTOA) development, locomotor joint kinematics, and degree of voluntary activity in rats following medial meniscal transection (MMT).

DESIGN

Twenty-one adult rats were subjected to MMT surgery of the left hindlimb and then assigned to one of three groups: (1) regular (i.e., no intervention), (2) hindlimb immobilization, or (3) treadmill running. Sham surgery was performed in four additional rats. Voluntary wheel run time/distance was measured, and 3D hindlimb kinematics were quantified during treadmill locomotion using biplanar radiography. Rats were euthanized 8 weeks after MMT or sham surgery, and the microstructure of the tibial cartilage and subchondral bone was quantified using contrast enhanced micro-CT.

RESULTS

All three MMT groups showed signs of PTOA (full-thickness lesions and/or increased cartilage volume) compared to the sham group, however the regular and treadmill-running groups had greater osteophyte formation than the immobilization group. For the immobilization group, increased volume was only observed in the anterior region of the cartilage. The treadmill-running group demonstrated a greater knee varus angle at mid-stance than the sham group, while the immobilization group demonstrated greater reduction in voluntary running than all the other groups at 2 weeks post-surgery.

CONCLUSIONS

Elevated weight-bearing via treadmill running at a slow/moderate speed did not accelerate PTOA in MMT rats when compared to regular weight-bearing. Reduced weight-bearing via immobilization may attenuate overall PTOA but still resulted in regional cartilage degeneration. Overall, there were minimal differences in hindlimb kinematics and voluntary running between MMT and sham rats.

Tibiofemoral joint structural change from 2.5 to 4.5 years following ACL reconstruction with and without combined meniscal pathology

Background

People who have had anterior cruciate ligament reconstruction (ACLR) are at a high risk of developing tibiofemoral joint (TFJ) osteoarthritis (OA), with concomitant meniscal injury elevating this risk. This study aimed to investigate OA-related morphological change over 2 years in the TFJ among individuals who have undergone ACLR with or without concomitant meniscal pathology and in healthy controls. A secondary aim was to examine associations of baseline TFJ cartilage defects and bone marrow lesions (BML) scores with tibial cartilage volume change in ACLR groups.

Methods

Fifty seven ACLR participants aged 18–40 years (32 isolated ACLR, 25 combined meniscal pathology) underwent knee magnetic resonance imaging (MRI) 2.5 and 4.5 years post-surgery. Nine healthy controls underwent knee MRI at the ~ 2-year intervals. Tibial cartilage volume, TFJ cartilage defects and BMLs were assessed from MRI.

Results

For both ACLR groups, medial and lateral tibial cartilage volume increased over 2 years (P <  0.05). Isolated ACLR group had greater annual percentage increase in lateral tibial cartilage volume compared with controls and with the combined group (P = 0.03). Cartilage defects remained unchanged across groups. Both ACLR groups showed more lateral tibia BML regression compared with controls (P = 0.04). Baseline cartilage defects score was positively associated with cartilage volume increase at lateral tibia (P = 0.002) while baseline BMLs score was inversely related to medial tibia cartilage volume increase (P = 0.001) in the pooled ACLR group.

Conclusions

Tibial cartilage hypertrophy was apparent in ACLR knees from 2.5 to 4.5 years post-surgery and was partly dependent upon meniscal status together with the nature and location of the underlying pathology at baseline. Magnitude and direction of change in joint pathologies (i.e., cartilage defects, BMLs) were less predictable and either remained stable or improved over follow-up.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2687-9) contains supplementary material, which is available to authorized users.

Ultrasonographic Assessment of Femoral Cartilage in Individuals With Anterior Cruciate Ligament Reconstruction: A Case-Control Study

CONTEXT

Developing osteoarthritis is common after anterior cruciate ligament reconstruction (ACLR). Monitoring changes in femoral cartilage size after ACLR may be a way to detect the earliest structural alterations before the radiographic onset of osteoarthritis. Diagnostic ultrasonography (US) offers a clinically accessible and valid method for evaluating anterior femoral cartilage size.

OBJECTIVE

To compare the US measurements of anterior femoral cross-sectional area and cartilage thickness between limbs in individuals with a unilateral ACLR and between the ACLR limbs of these individuals and the limbs of uninjured control participants.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 20 volunteers with an ACLR (37.0 ± 26.6 months after surgery) and 28 uninjured volunteers.

MAIN OUTCOME MEASURE(S)

We used US to assess anterior femoral cartilage cross-sectional area and thickness (ie, medial, lateral, and intercondylar) in the ACLR and contralateral limbs of participants with ACLR and unilaterally in the reference limbs of uninjured participants.

RESULTS

The ACLR limb presented with greater anterior femoral cartilage cross-sectional area (96.68 ± 22.68 mm²) than both the contralateral (85.69 ± 17.57 mm², t₁₉ = 4.47; P < .001) and uninjured (84.62 ± 15.89 mm², t₄₆ = 2.17; P = .04) limbs. The ACLR limb presented with greater medial condyle thickness (2.61 ± 0.61 mm) than both the contralateral (2.36 ± 0.47 mm, t₁₉ = 2.78; P = .01) and uninjured limbs (2.22 ± 0.40 mm, t₄₆ = 2.69; P = .01) and greater lateral condyle thickness (2.46 ± 0.65 mm) than the uninjured limb (2.12 ± 0.41 mm, t₄₆ = 2.20; P = .03).

CONCLUSIONS

Anterior femoral cartilage cross-sectional area and thickness assessed via US were greater in the ACLR limb than in the contralateral and uninjured limbs. Greater thickness and cross-sectional area may have been due to cartilage swelling or hypertrophy after ACLR, which may affect the long-term health of the joint.

Progression of Post-Traumatic Osteoarthritis in rat meniscectomy models: Comprehensive monitoring using MRI

Knee injury often triggers post-traumatic osteoarthritis (PTOA) that affects articular cartilage (AC), subchondral bone, meniscus and the synovial membrane. The available treatments for PTOA are largely ineffective due to late diagnosis past the “treatment window”. This study aimed to develop a detailed understanding of the time line of the progression of PTOA in murine models through longitudinal observation of the femorotibial joint from the onset of the disease to the advanced stage. Quantitative magnetic resonance microimaging (µMRI) and histology were used to evaluate PTOA-associated changes in the knee joints of rats subjected to knee meniscectomy. Systematic longitudinal changes in the articular cartilage thickness, cartilage T₂ and the T₂ of epiphysis within medial condyles of the tibia were all found to be associated with the development of PTOA in the animals. The following pathogenesis cascade was found to precede advanced PTOA: meniscal injury → AC swelling → subchondral bone remodelling → proteoglycan depletion → free water influx → cartilage erosion. Importantly, the imaging protocol used was entirely MRI-based. This protocol is potentially suitable for whole-knee longitudinal, non-invasive assessment of the development of OA. The results of this work will inform the improvement of the imaging methods for early diagnosis of PTOA.

Advancing quantitative techniques to improve understanding of the skeletal structure-function relationship

Although all functional movement arises from the interplay between the neurological, skeletal, and muscular systems, it is the skeletal system that forms the basic framework for functional movement. Central to understanding human neuromuscular development, along with the genesis of musculoskeletal pathologies, is quantifying how the human skeletal system adapts and mal-adapts to its mechanical environment. Advancing this understanding is hampered by an inability to directly and non-invasively measure in vivo strains, stresses, and forces on bone. Thus, we traditionally have turned to animal models to garner such information. These models enable direct in vivo measures that are not available for human subjects, providing information in regards to both skeletal adaptation and the interplay between the skeletal and muscular systems. Recently, there has been an explosion of new imaging and modeling techniques providing non-invasive, in vivo measures and estimates of skeletal form and function that have long been missing. Combining multiple modalities and techniques has proven to be one of our most valuable resources in enhancing our understanding of the form-function relationship of the human skeletal, muscular, and neurological systems. Thus, to continue advancing our knowledge of the structural-functional relationship, validation of current tools is needed, while development is required to limit the deficiencies in these tools and develop new ones.

Collagen XI mutation lowers susceptibility to load-induced cartilage damage in mice

Interactions among risk factors for osteoarthritis (OA) are not well understood. We investigated the combined impact of two prevalent risk factors: mechanical loading and genetically abnormal cartilage tissue properties. We used cyclic tibial compression to simulate mechanical loading in the cho/+ (Col11a1 haploinsufficient) mouse, which has abnormal collagen fibrils in cartilage due to a point mutation in the Col11a1 gene. We hypothesized that the mutant collagen would not alter phenotypic bone properties and that cho/+ mice, which develop early onset OA, would develop enhanced load-induced cartilage damage compared to their littermates. To test our hypotheses, we applied cyclic compression to the left tibiae of 6-month-old cho/+ male mice and wild-type (WT) littermates for 1, 2, and 6 weeks at moderate (4.5 N) and high (9.0 N) peak load magnitudes. We then characterized load-induced cartilage and bone changes by histology, microcomputed tomography, and immunohistochemistry. Prior to loading, cho/+ mice had less dense, thinner cortical bone compared to WT littermates. In addition, in loaded and non-loaded limbs, cho/+ mice had thicker cartilage. With high loads, cho/+ mice experienced less load-induced cartilage damage at all time points and displayed decreased matrix metalloproteinase (MMP)-13 levels compared to WT littermates. The thinner, less dense cortical bone and thicker cartilage were unexpected and may have contributed to the reduced severity of load-induced cartilage damage in cho/+ mice. Furthermore, the spontaneous proteoglycan loss resulting from the mutant collagen XI was not additive to cartilage damage from mechanical loading, suggesting that these risk factors act through independent pathways. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:711-720, 2018.

Effects of habitual knuckle cracking on metacarpal cartilage thickness and grip strength

Joint cracking involves a manipulation of the finger joints resulting in an audible crack. This study aimed to determine whether habitual knuckle cracking (KC) leads to an alteration in grip strength and metacarpal head (MH) cartilage thickness. Thirty-five habitual knuckle crackers (cracking their joints ≥5times/day) (20 M, 15 F, aged 19-27 years) and 35 age-, gender-, and body mass index-matched non-crackers were enrolled in the study. MH cartilage thickness was measured with ultrasound and grip strength was measured with an analog Jamar hand dynamometer. Grip strength was similar between groups (P>0.05). Habitual knuckle crackers had thicker MH cartilage in the dominant and non-dominant hands than those of the controls (P=0.038 and P=0.005, respectively). There was no correlation between MH cartilage thickness and grip strength in both groups (P>0.05). While habitual KC does not affect handgrip strength, it appears to be associated with increased MH cartilage thickness.

Osteoarthritis in the Knee Joints of Göttingen Minipigs after Resection of the Anterior Cruciate Ligament? Missing Correlation of MRI, Gene and Protein Expression with Histological Scoring

Introduction

The Göttingen Minipig (GM) is used as large animal model in articular cartilage research. The aim of the study was to introduce osteoarthritis (OA) in the GM by resecting the anterior cruciate ligament (ACLR) according to Pond and Nuki, verified by histological and magnetic resonance imaging (MRI) scoring as well as analysis of gene and protein expression.

Materials and Methods

The eight included skeletally mature female GM were assessed after ACLR in the left and a sham operation in the right knee, which served as control. 26 weeks after surgery the knee joints were scanned using a 3-Tesla high-field MR tomography unit with a 3 T CP Large Flex Coil. Standard proton-density weighted fat saturated sequences in coronal and sagittal direction with a slice thickness of 3 mm were used. The MRI scans were assessed by two radiologists according to a modified WORMS-score, the X-rays of the knee joints by two evaluators. Osteochondral plugs with a diameter of 4mm were taken for histological examination from either the main loading zone or the macroscopic most degenerated parts of the tibia plateau or condyle respectively. The histological sections were blinded and scored by three experts according to Little et al. Gene expression analysis was performed from surrounding cartilage. Expression of adamts4, adamts5, acan, col1A1, col2, il-1ß, mmp1, mmp3, mmp13, vegf was determined by qRT-PCR. Immunohistochemical staining (IH) of Col I and II was performed. IH was scored using a 4 point grading (0—no staining; 3-intense staining).

Results and Discussion

Similar signs of OA were evident both in ACLR and sham operated knee joints with the histological scoring result of the ACLR joints with 6.48 ± 5.67 points and the sham joints with 6.86 ± 5.84 points (p = 0.7953) The MRI scoring yielded 0.34 ± 0.89 points for the ACLR and 0.03 ± 0.17 for the sham knee joints. There was no correlation between the histological and MRI scores (r = 0.10021). The gene expression profiles as well as the immunohistochemical findings showed no significant differences between ACLR and sham knee joints. In conclusion, both knee joints showed histological signs of OA after 26 weeks irrespective of whether the ACL was resected or not. As MRI results did not match the histological findings, MRI was obviously unsuitable to diagnose the OA in GM. The analysis of the expression patterns of the 10 genes could not shed light on the question, whether sham operation also induced cartilage erosion or if the degeneration was spontaneous. The modified Pond-Nuki model may be used with reservation in the adult minipig to induce an isolated osteoarthritis.

Comparison of T1rho and T2 Mapping of Knee Articular Cartilage in an Asymptomatic Population

Objective

To analyze subregional differences in T1rho (T1ρ) and T2 values and their correlation in asymptomatic knee cartilage, and to evaluate angular dependence with magic angles.

Materials and Methods

Six asymptomatic volunteers underwent knee MRI with T1ρ and T2 mapping. T1ρ and T2 values were measured by two radiologists independently, at nine subregions in the medial femoral condyle (MFC) cartilage, at angles of ± 0°, 15°, 35°, 55°, 75° respective to a vertical line (B0) bisecting the width of the distal femur, and at two locations in the patella. Subregional values of T1ρ and T2 were analyzed and significant differences in three divided portions of the MFC (anterior, central, and posterior) were statistically evaluated. Correlation between T1ρ and T2 and angular dependence with magic angles were also assessed for statistical significance.

Results

T1ρ values were lowest at +15° and highest at -55°. T2 values were lowest at +75° and highest at +35°. Both T1ρ and T2 were higher in superior patella than inferior patella. T1ρ showed significant differences in the three divided portions of the MFC, while T2 showed significant differences only between central and posterior portions. There was a weak correlation between T1ρ and T2 (r = 0.217, p = 0.127). T1ρ showed more angular dependence than T2.

Conclusion

T1ρ and T2 showed different subregional values and angular dependence in asymptomatic knee cartilage with a weak correlation. Awareness of these differences will aid in assessment of cartilage in a specific subregion of the knee.

Changes in the osteochondral unit during osteoarthritis: structure, function and cartilage-bone crosstalk

In diarthrodial joints, the articular cartilage, calcified cartilage, and subchondral cortical and trabecular bone form a biocomposite - referred to as the osteochondral unit - that is uniquely adapted to the transfer of load. During the evolution of the osteoarthritic process the compositions, functional properties, and structures of these tissues undergo marked alterations. Although pathological processes might selectively target a single joint tissue, ultimately all of the components of the osteochondral unit will be affected because of their intimate association, and thus the biological and physical crosstalk among them is of great importance. The development of targeted therapies against the osteoarthritic processes in cartilage or bone will, therefore, require an understanding of the state of these joint tissues at the time of the intervention. Importantly, these interventions will not be successful unless they are applied at the early stages of disease before considerable structural and functional alterations occur in the osteochondral unit. This Review describes the changes that occur in bone and cartilage during the osteoarthritic process, and highlights strategies for how this knowledge could be applied to develop new therapeutic interventions for osteoarthritis.

A low ratio of n-6/n-3 polyunsaturated fatty acids suppresses matrix metalloproteinase 13 expression and reduces adjuvant-induced arthritis in rats

Increased expression of matrix metalloproteinase 13 (MMP13) in chondrocytes contributes to the development of osteoarthritis. The hypothesis of this study was that diet with a low ratio of n-6/n-3 polyunsaturated fatty acids (PUFAs) is associated with reduced MMP13 expression in inflammatory chondrocytes in vitro and in vivo. Human chondrocytes were cultured with different ratios of linoleic acid (LA, n-6 PUFA) to α-linolenic acid (n-3 PUFA) from 1:1 to 10:1. Proliferation of chondrocytes, MMP13 protein and mRNA levels were detected, respectively. Sprague-Dawley rats (n=30) were fed diets containing different ratios of n-6/n-3 PUFA. Freund's complete adjuvant was injected to make the model of arthritis. Paw swelling rate was measured and all rats were euthanized after 6 weeks of treatment. Serum MMP13 and IL-1 were measured by enzyme-linked immunosorbent assay. Joint histological sections were stained with safranin-O Fast Green to evaluate cartilage damage. Low ratio of LA/α-linolenic acid decreased the mRNA and protein levels of MMP13 but did not affect chondrocytes proliferation. Ratios of PUFA such as 1:1 and 2:1 significantly reduced paw swelling rate, and serum MMP13 and IL-1 levels in a rat model. Histological staining showed that ratios of 1:1 and 2:1 PUFA significantly alleviated cartilage damage in adjuvant-induced arthritis. A ratio of n-6/n-3 PUFA of 1:1 showed the strongest inhibitory effect on MMP13. Our results indicate that a low ratio of n-6/n-3 PUFA at 1:1 significantly suppressed MMP13 expression both in vitro and in vivo and reduced adjuvant-induced arthritis in rats could be a means to control and reduce the symptoms of osteoarthritis.

Evaluation of the disco-vertebral junction using ultrashort time-to-echo magnetic resonance imaging: inter-reader agreement and association with vertebral endplate lesions

OBJECTIVE

To evaluate ultrashort time to echo (UTE) magnetic resonance (MR) morphology of the cartilaginous endplates (CEP) in cadaveric lumbar spines with bony vertebral endplate (VEP) lesions, to determine inter-reader agreement as well as associations between the CEP morphology and VEP lesions as well as other abnormalities.

MATERIALS AND METHODS

MR imaging of cadaveric lumbar spines from 10 donors was performed at 3T using a UTE MR sequence. Two musculoskeletal radiologists identified the location of vertebral endplate lesions in consensus. The morphology of the CEP overlying the lesions and in the adjacent normal regions was assessed individually. A total of 55 vertebral lesions and 55 normal regions were assessed. The presence of osteophytosis, morphological changes of the anterior and posterior longitudinal ligament, and intervertebral disc signal and morphology was also assessed. Agreement between observers was determined using Cohen's kappa analysis, and association between CEP and vertebral endplate lesions was determined using the chi square test.

RESULTS

Fifty-five vertebral endplate lesions were identified and the morphology of CEP evaluated by two readers was in substantial agreement with Cohen's kappa of 0.78. The presence of vertebral endplate abnormality was associated with the presence of osteophytes (39 out of 55 levels), altered morphology and signal of the anterior longitudinal ligament (23 out of 55 levels) and intervertebral discs (30 out of 55 levels).

CONCLUSION

UTE MRI enables evaluation of the CEP with substantial inter-reader agreement. Abnormal changes of the CEP may facilitate formation of lesions of vertebral endplate over time and are associated with degenerative changes of the lumbar spine.

Effect of Matching or Overconstraining Knee Laxity During Anterior Cruciate Ligament Reconstruction on Knee Osteoarthritis and Clinical Outcomes: A Randomized Controlled Trial With 84-Month Follow-up

BACKGROUND

The "initial graft tension" applied at the time of graft fixation during anterior cruciate ligament (ACL) reconstruction surgery modulates joint contact mechanics, which in turn may promote posttraumatic osteoarthritis (OA).

PURPOSE/HYPOTHESES

The study objectives were to compare clinical, functional, patient-reported, and OA imaging outcomes between 2 different initial laxity-based graft tension cohorts and a matched uninjured control group as well as to evaluate the effects of laxity-based graft tension on OA development at 84-month follow-up. The 2 laxity-based tension protocols were (1) to restore normal anteroposterior (AP) laxity at the time of surgery relative to the contralateral uninjured knee (low-tension group) or (2) to overconstrain AP laxity by 2 mm relative to the contralateral uninjured knee (high-tension group). The hypotheses were that (1) the high-tension group would have improved outcomes and decreased OA compared with the low-tension group after 84 months, and (2) the outcomes for the high-tension group would be equivalent to those for an age-, sex-, race-, and activity-matched group of control participants with uninjured knees.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Patients had their ACLs reconstructed with either a bone-patellar tendon-bone or 4-stranded hamstring autograft, and outcomes were compared with a matched control group. Outcomes were evaluated preoperatively and at 60 and 84 months postoperatively and included clinical (KT-1000 arthrometer AP laxity measurement and International Knee Documentation Committee [IKDC] examination score), functional (1-legged hop for distance and knee extensor torque), patient-reported (Knee injury and Osteoarthritis Outcome Score [KOOS], Short Form-36 [SF-36], and patient satisfaction survey), and OA imaging (measurement of joint space width [JSW], Osteoarthritis Research Society International [OARSI] radiographic score, and Whole-Organ Magnetic Resonance Imaging Score [WORMS]) components. Repeated-measures analyses of variance were used to evaluate differences in outcomes between the treatment groups and the control group.

RESULTS

There were significant differences between the 2 tension groups in 1 of 5 KOOS subscales (sports and recreation; P = .04) and 2 of 8 SF-36 subscales (vitality, mental health; P < .04) at 84 and 60 months, respectively. Both tension groups scored significantly worse than the control group in the IKDC examination (P < .001), 1-legged hop (P ≤ .017), KOOS quality of life and symptoms subscales (P < .03), and OARSI radiographic score (P ≤ .02) at 84 months. The low-tension group performed significantly worse than the control group on the KOOS pain subscale (P = .03), SF-36 general health and social functioning (P < .04), OARSI radiographic score (P < .001), and WORMS (P = .001), while the high-tension group had statistically different results than the control group in AP knee laxity (P < .001), radiographic JSW (P = .003), and OARSI radiographic score (P = .02) as well as significantly more subsequent knee injuries (P = .02) at 84 months.

CONCLUSION

The results do not support the hypotheses that the high-tension group would have improved outcomes when compared with the low-tension group after 84 months of healing or that the outcomes for the high-tension group would be equivalent to those for the matched control group. While there were minor differences in patient-reported outcomes between the 2 laxity-based tension groups, all other outcomes were similar.

REGISTRATION

NCT00434837.