Tibiofemoral articular cartilage composition differs based on serum biochemical profiles following anterior cruciate ligament reconstruction

Chondrocalcin: Insights into its regulation and multi-function in cartilage and bone

Type Ⅱ collagen (COLⅡ) is the primary constituent of the cartilage matrix, specifically present in vitreous bodies, cartilage, bone, and other skeletal elements. Therefore, the normal expression of COLⅡ is crucial for the normal development, linear growth, mechanical properties, and self-repairing ability of cartilage. Chondrocalcin, the C-propeptide of type Ⅱ procollagen, is not only a marker of COLⅡ synthesis but also one of the most abundant polypeptides in cartilage. This work examines the pivotal role of chondrocalcin in the synthesis of COLⅡ, comprehensively examining its regulation and multi-functions in cartilage and bone related diseases. Our findings suggest that mutations in the chondrocalcin-encoding domain of COL2A1 affect cartilage and bone development in clinical conditions.

Investigating the Impact of Preoperative Kinesiophobia and Pain on Postoperative Gait Biomechanics Following Anterior Cruciate Ligament Injury

Background

Aberrant gait biomechanics-ie, lower knee abduction moment (KAM) impulse- are linked to the development of posttraumatic osteoarthritis after anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR). There is a clinical need to identify modifiable factors, such as kinesiophobia and pain, that may contribute to aberrant gait development after ACLR to advance multimodal rehabilitation strategies.

Purpose/Hypothesis

This study aimed to determine associations between preoperative kinesiophobia and pain and gait biomechanics linked to posttraumatic osteoarthritis development at 2 and 4 months after ACLR. We hypothesized that worse preoperative kinesiophobia and pain would be associated with lower KAM impulses in the ACLR limb but not the uninjured limb at 2 and 4 months after ACLR.

Study Design

Cohort study; Level of evidence, 2.

Methods

Patients within 6 weeks of ACL injury and planning to undergo ACLR with bone-patellar tendon-bone autografts were recruited for the study. Preoperatively, participants completed the Tampa Scale of Kinesiophobia (TSK-11) and Knee injury and Osteoarthritis Outcome Score Pain (KOOS Pain) subscale surveys to assess kinesiophobia (ie, psychological component to pain) and knee pain, respectively. Participants returned at 2 and 4 months after ACLR to complete a 3-dimensional gait biomechanics analysis. KAM impulses during the stance phase were calculated (N*m*s/N*m) for both limbs. Associations of preoperative TSK-11 and KOOS Pain scores with KAM impulses in ACLR and uninjured limbs were analyzed using separate linear regressions.

Results

A total of 36 participants (58% women; mean age, 21.4 ± 4.31 years; body mass index, 24.1 ± 3.59 kg/m2 ) completed 3 study visits. Higher preoperative kinesiophobia was associated with lower KAM impulses in the ACLR limb (R 2 = 0.14; P = .02) but not the uninjured limb (R 2 = 0.01; P = .58) at 4 months after ACLR. Preoperative KOOS Pain scores were not associated with KAM impulses in the ACLR and uninjured limbs at 2 and 4 months after ACLR (ΔR 2 range, <0.01-0.02; P range = .53-.90).

Conclusion

Preoperative kinesiophobia, but not pain, was weakly associated with lower KAM impulses during early to midphases of clinical recovery at 4 months after ACLR.

The Role of Biomarkers in Predicting Outcomes of Anterior Cruciate Ligament Reconstruction: A Systematic Review

Background

Anterior cruciate ligament (ACL) injury is frequently associated with injuries to other parts of the knee, including the menisci and articular cartilage. After ACL injury and reconstruction, there may be progressive chondral degradation. Biomarkers in blood, urine, and synovial fluid can be measured after ACL injury and reconstruction and have been proposed as a means of measuring the associated cellular changes occurring in the knee.

Purpose

To systematically review the literature regarding biomarkers in urine, serum, or synovial fluid that have been associated with an outcome measure after ACL reconstruction.

Study Design

Systematic review; Level of evidence, 3.

Methods

This review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The MEDLINE, Embase, CINAHL, and Web of Science databases were searched to identify studies published before September 2023 that reported on patients undergoing ACL reconstruction where a biomarker was measured and related to an outcome variable. Of 9360 results, 16 studies comprising 492 patients were included. Findings were reported as descriptive summaries synthesizing the available literature.

Results

A total of 45 unique biomarkers or biomarker ratios were investigated (12 serum, 3 urine, and 38 synovial fluid; 8 biomarkers were measured from >1 source). Nineteen different outcome measures were identified, including the International Knee Documentation Committee Subjective Knee Form, Knee injury and Osteoarthritis Outcome Score, numeric pain scores, radiological outcomes (magnetic resonance imaging and radiography), rates of arthrofibrosis and cyclops lesions, and gait biomechanics. Across the included studies, 17 biomarkers were found to have a statistically significant association (P < .05) with an outcome variable. Serum interleukin 6 (s-IL-6), serum and synovial fluid matrix metalloproteinase-3 (s-MMP-3 and sf-MMP-3), urinary and synovial fluid C-terminal telopeptide of type 2 collagen (u-CTX-II and sf-CTX-II), and serum collagen type 2 cleavage product (s-C2C) showed promise in predicting outcomes after ACL reconstruction, specifically regarding patient-reported outcome measures (s-IL-6 and u-CTX-II), gait biomechanical parameters (s-IL-6, sf-MMP-3, s-MMP-3, and s-C2C), pain (s-IL-6 and u-CTX-II), and radiological osteoarthritis (ratio of u-CTX-II to serum procollagen 2 C-propeptide).

Conclusion

The results highlight several biomarkers that have been associated with clinically important postoperative outcome measures and may warrant further research to understand if they can provide meaningful information in the clinical environment.

Association of Serum Biochemical Biomarker Profiles of Joint Tissue Inflammation and Cartilage Metabolism With Posttraumatic Osteoarthritis-Related Symptoms at 12 Months After ACLR

BACKGROUND

Anterior cruciate ligament injury and anterior cruciate ligament reconstruction (ACLR) are risk factors for symptomatic posttraumatic osteoarthritis (PTOA). After ACLR, individuals demonstrate altered joint tissue metabolism indicative of increased inflammation and cartilage breakdown. Serum biomarker changes have been associated with tibiofemoral cartilage composition indicative of worse knee joint health but not with PTOA-related symptoms.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine associations between changes in serum biomarker profiles from the preoperative sample collection to 6 months after ACLR and clinically relevant knee PTOA symptoms at 12 months after ACLR. It was hypothesized that increases in biomarkers of inflammation, cartilage metabolism, and cartilage degradation would be associated with clinically relevant PTOA symptoms after ACLR.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Individuals undergoing primary ACLR were included (N = 30). Serum samples collected preoperatively and 6 months after ACLR were processed to measure markers indicative of changes in inflammation (ie, monocyte chemoattract protein 1 [MCP-1]) and cartilage breakdown (ie, cartilage oligomeric matrix protein [COMP], matrix metalloproteinase 3, ratio of type II collagen breakdown to type II collagen synthesis). Knee injury and Osteoarthritis Outcome Score surveys were completed at 12 months after ACLR and used to identify participants with and without clinically relevant PTOA-related symptoms. K-means cluster analyses were used to determine serum biomarker profiles. One-way analyses of variance and logistic regressions were used to assess differences in Knee injury and Osteoarthritis Outcome Score subscale scores and clinically relevant PTOA-related symptoms between biomarker profiles.

RESULTS

Two profiles were identified and characterized based on decreases (profile 1: 67% female; age, 21.4 ± 5.1 years; body mass index, 24.4 ± 2.4) and increases (profile 2: 33% female; age, 21.3 ± 3.2 years; body mass index, 23.4 ± 2.6) in sMCP-1 and sCOMP preoperatively to 6 months after ACLR. Participants with profile 2 did not demonstrate differences in knee pain, symptoms, activities of daily living, sports function, or quality of life at 12 months after ACLR compared to those with profile 1 (P = .56-.81; η2 = 0.002-0.012). No statistically significant associations were noted between biomarker profiles and clinically relevant PTOA-related symptoms (odds ratio, 1.30; 95% CI, 0.23-6.33).

CONCLUSION

Serum biomarker changes in MCP-1 and sCOMP within the first 6 months after ACLR were not associated with clinically relevant PTOA-related symptoms.

Interactions of cumulative load with biomarkers of cartilage turnover predict knee cartilage change over 2 years: data from the osteoarthritis initiative

The purpose was to investigate relationships of cumulative load and cartilage turnover biomarkers with 2-year changes in cartilage in knee osteoarthritis. From participants with Kellgren-Lawrence (KL) grades of 1 to 3, cartilage thickness and transverse relaxation time (T2) were computed from 24-month (baseline) and 48-month magnetic resonance images. Cumulative load was the interaction term of the Physical Activity Scale for the Elderly (PASE) and body mass index (BMI). Serum cartilage oligomeric matrix protein (COMP) and the nitrated form of type II collagen (Coll2-1 NO2) were collected at baseline. Multiple regressions (adjusted for baseline age, KL grade, cartilage measures, pain, comorbidity) evaluated the relationships of cumulative load and biomarkers with 2-year changes. In 406 participants (63.7 (8.7) years), interactions of biomarkers with cumulative load weakly predicted 2-year cartilage changes: (i) COMP × cumulative load explained medial tibia thickness change (R2 increased 0.062 to 0.087, p < 0.001); (ii) Coll2-1 NO2 × cumulative load explained central medial femoral T2 change (R2 increased 0.177 to 0.210, p < 0.001); and (iii) Coll2-1 NO2 × cumulative load explained lateral tibia T2 change (R2 increased 0.166 to 0.188, p < 0.001). Moderate COMP or Coll2-1 NO2 at baseline appeared protective. High COMP or Coll2-1 NO2, particularly with high BMI and low PASE, associated with worsening cartilage. Moderate serum concentrations of cartilage turnover biomarkers, at high and low physical activity, associated with maintained cartilage outcomes over 2 years. In conclusion, high concentrations of cartilage turnover biomarkers, particularly with high BMI and low physical activity, associated with knee cartilage thinning and increasing T2 over 2 years. Key Points • Higher quality cartilage may be better able to tolerate a larger cumulative load than poor quality cartilage. • Among participants enrolled in the Osteoarthritis Initiative Biomarkers Consortium Project, a representation of cumulative load exposure and its interaction with cartilage turnover biomarkers were weakly related with 2-year change in knee cartilage. • These findings suggest that cartilage turnover is a factor that modifies the relationship between loading exposure and cartilage loss in knee OA.

Gill M, Page GL, Pope A, Measom GJ, Hager RL, Seeley MK. Serum Cartilage Oligomeric Matrix Protein Concentration Increases More After Running Than Swimming for Older People

BACKGROUND

Knee osteoarthritis is common in older people. Serum cartilage oligomeric matrix protein (sCOMP) is a biomarker of knee articular cartilage metabolism. The purpose of this study was 2-fold: to (1) determine acute effects of running and swimming on sCOMP concentration in older people; and (2) investigate relationships between sCOMP concentration change due to running and swimming and measures of knee health in older people.

HYPOTHESES

Running would result in greater increase in sCOMP concentration than swimming, and increase in sCOMP concentration due to running and swimming would associate positively with measures of poor knee health.

STUDY DESIGN

Cross-sectional.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 20 participants ran 5 km and 19 participants swam 1500 m. sCOMP concentration was measured immediately before, immediately after, and 15, 30, and 60 minutes after running or swimming. sCOMP concentration change due to running and swimming was compared. Correlations between sCOMP concentration change due to running and swimming, and other measures of knee health were evaluated, including the Tegner Activity Scale and Knee injury and Osteoarthritis Outcome Score.

RESULTS

sCOMP concentration increased 29% immediately after running, relative to baseline, but only 6% immediately after swimming (P < 0.01). No significant relationship was observed between acute sCOMP change due to running and swimming, and observed measures of knee health (P > 0.05). Participants with clinically relevant knee symptoms exhibited greater sCOMP concentration before and after running and swimming (P = 0.03) and had greater body mass (P = 0.04).

CONCLUSION

Running results in greater acute articular cartilage metabolism than swimming; however, the chronic effects of this are unclear. Older people with clinically relevant knee symptoms possess greater sCOMP concentration and are heavier, independent of exercise mode and physical activity level.

CLINICAL RELEVANCE

These results describe the effects of exercise (running and swimming) for older physically active persons, with and without knee pain.

Relationships Between Running Biomechanics and Femoral Articular Cartilage Thickness and Composition in Anterior Cruciate Ligament Reconstruction Patients

BACKGROUND

Although individuals with anterior cruciate ligament reconstruction (ACLR) are at high risk for posttraumatic osteoarthritis, mechanisms underlying the relationship between running and knee cartilage health remain unclear.

OBJECTIVE

We aimed to investigate how 30 min of running influences femoral cartilage thickness and composition and their relationships with running biomechanics in patients with ACLR and controls.

METHODS

Twenty patients with ACLR (time post-ACLR: 14.6 ± 6.1 months) and 20 matched controls participated in the study. A running session required both groups to run for 30 min at a self-selected speed. Before and after running, we measured femoral cartilage thickness via ultrasound imaging. A MRI session consisted of T2 mapping.

RESULTS

The ACLR group showed longer T2 relaxation times in the medial femoral condyle at resting compared with the control group (central: 51.2 ± 16.6 vs. 34.9 ± 13.2 ms, p = 0.006; posterior: 50.2 ± 10.1 vs. 39.8 ± 7.4 ms, p = 0.006). Following the run, the ACLR group showed greater deformation in the medial femoral cartilage than the control group (0.03 ± 0.01 vs. 0.01 ± 0.01 cm, p = 0.001). Additionally, the ACLR group showed significant negative correlations between resting T2 relaxation time in the medial femoral condyle and vertical impulse (standardized regression coefficients = -0.99 and p = 0.004) during running.

CONCLUSIONS

Our findings suggest that those who are between 6 and 24 months post-ACLR have degraded cartilage composition and their cartilage deforms more due to running vGRF.

Delayed cartilage oligomeric matrix protein response to loading is associated with femoral cartilage composition post-ACLR

PURPOSE

To determine associations between immediate and delayed response of serum cartilage oligomeric matrix protein (sCOMP) to loading (i.e., 3000 walking steps) and femoral cartilage interlimb T1ρ relaxation times in individual's post-anterior cruciate ligament reconstruction (ACLR).

METHODS

This cross-sectional study included 20 individuals 6-12 months following primary ACLR (65% female, 20.5 ± 4.0 years old, 24.9 ± 3.0 kg/m2, 7.3 ± 1.5 months post-ACLR). Serum samples were collected prior to, immediately following, and 3.5 h following walking 3000 steps on a treadmill at habitual walking speed. sCOMP concentrations were processed using enzyme-linked immunosorbent assays. Immediate and delayed absolute sCOMP responses to loading were evaluated immediately and 3.5 h post-walking, respectively. Participants underwent bilateral magnetic resonance imaging with T1ρ sequences to calculate resting femoral cartilage interlimb T1ρ relaxation time ratios between limbs (i.e., ACLR/Uninjured limb). Linear regression models were fitted to determine associations between sCOMP response to loading and femoral cartilage T1ρ outcomes controlling for pre-loading sCOMP concentrations.

RESULTS

Greater increases in delayed sCOMP response to loading were associated with greater lateral (∆R2 = 0.29, p = 0.02) but not medial (∆R2 < 0.01, p = 0.99) femoral cartilage interlimb T1ρ ratios. Associations between immediate sCOMP response to loading with femoral cartilage interlimb T1ρ ratios were weak and non-significant (∆R2 range = 0.02-0.09, p range = 0.21-0.58).

CONCLUSION

Greater delayed sCOMP response to loading, a biomarker of cartilage breakdown, is associated with worse lateral femoral cartilage composition in the ACLR limb compared to the uninjured limb. Delayed sCOMP response to loading may be a more indicative metabolic indicator linked to deleterious changes in composition than immediate sCOMP response.

Interlimb differences in T1ρ MRI relaxation times linked with symptomatic knee osteoarthritis following anterior cruciate ligament reconstruction

BACKGROUND

Lower proteoglycan density, as estimated by greater T1ρ magnetic resonance imaging (MRI) relaxation times, may be an indicator of early osteoarthritis development. We examined associations between femoral cartilage inter-limb T1ρ MRI relaxation time ratios and clinically relevant knee symptoms at 12 months following anterior crucial ligament reconstruction (ACLR).

METHODS

Twenty-nine individuals completed the Knee Osteoarthritis Outcome Score (KOOS) and underwent MRI 12 months following ACLR for this cross-sectional study. Participants were categorized as symptomatic or asymptomatic for clinically relevant knee symptoms consistent with osteoarthritis based on a standard KOOS classification. T1ρ MRI relaxation times were segmented in the weightbearing regions of lateral and medial femoral condyle (LFC and MFC). Inter-limb T1ρ MRI relaxation time ratios were calculated by normalizing the ACLR to the uninjured knee. T-tests were used to compare LFC and MFC interlimb T1ρ relaxation time ratios between individuals with and without knee symptoms. A Receiver Operating Characteristic (ROC) Curve analysis was used to determine a critical inter-limb T1ρ relaxation time ratio identifying symptomatic patients. Odds ratios (OR) and 95% confidence intervals (CI) estimated the association between the critical value and clinically relevant knee symptoms.

RESULTS

Symptomatic individuals had significantly higher LFC inter-limb T1ρ MRI relaxation time ratios compared to asymptomatic individuals (p = 0.04). Individuals with an LFC inter-limb T1ρ MRI relaxation time ratio >1.11 were more likely to have symptoms (OR 8.5; 95%CI = 1.25-57.93).

CONCLUSION

Individuals with greater inter-limb LFC T1ρ MRI relaxation time ratios 12 months post-ACLR may be more likely to exhibit symptoms consistent with knee OA.

Sustained inhibition of CC-chemokine receptor-2 via intraarticular deposition of polymeric microplates in post-traumatic osteoarthritis

Posttraumatic osteoarthritis (PTOA) is mostly treated via corticosteroid administration, and total joint arthroplasty continues to be the sole effective intervention in severe conditions. To assess the therapeutic potential of CCR2 targeting in PTOA, we used biodegradable microplates (µPLs) to achieve a slow and sustained intraarticular release of the CCR2 inhibitor RS504393 into injured knees and followed joint damage during disease progression. RS504393-loaded µPLs (RS-µPLs) were fabricated via a template-replica molding technique. A mixture of poly(lactic-co-glycolic acid) (PLGA) and RS504393 was deposited into 20 × 10 μm (length × height) wells in a polyvinyl alcohol (PVA) square-patterned template. After physicochemical and toxicological characterizations, the RS504393 release profile from µPL was assessed in PBS buffer. C57BL/6 J male mice were subjected to destabilization of the medial meniscus (DMM)/sham surgery, and RS-µPLs (1 mg/kg) were administered intraarticularly 1 week postsurgery. Administrations were repeated at 4 and 7 weeks post-DMM. Drug free-µPLs (DF-µPLs) and saline injections were performed as controls. Mice were euthanized at 4 and 10 weeks post-DMM, corresponding to the early and severe PTOA stages, respectively. Knees were evaluated for cartilage structure score (ACS, H&E), matrix loss (safranin O score), osteophyte formation and maturation from cartilage to bone (cartilage quantification), and subchondral plate thickness. The RS-µPL architecture ensured the sustained release of CCR2 inhibitors over several weeks, with ~ 20% of RS504393 still available at 21 days. This prolonged release improved cartilage structure and reduced bone damage and synovial hyperplasia at both PTOA stages. Extracellular matrix loss was also attenuated, although with less efficacy. The results indicate that local sustained delivery is needed to optimize CCR2-targeted therapies.

Early ablation of Ccr2 in aggrecan-expressing cells following knee injury ameliorates joint damage and pain during post-traumatic osteoarthritis

OBJECTIVE

To investigate whether Ccr2 inactivation in aggrecan-expressing cells induced before post-traumatic OA (PTOA) onset or during progression, improves joint structures, synovial thickness and pain.

DESIGN

We induced a Ccr2 deletion in aggrecan-expressing cells (CCR2-AggKO) in skeletally mature mice using a tamoxifen-inducible Ccr2 inactivation. We stimulated PTOA changes (destabilization of medial meniscus, DMM) in CCR2-AggKO and CCR2+/+ mice, inducing recombination before DMM or 4 wks after DMM (early-vs late-inactivation). Joint damage was evaluated 2, 4, 8, 12 wks post-DMM using multiple scores: articular-cartilage structure (ACS), Safranin-O, histomorphometry, osteophyte size/maturity, subchondral bone thickness and synovial hyperplasia. Spontaneous (incapacitance meter) and evoked pain (von-Frey filaments) were assessed up to 20 wks.

RESULTS

Early aggrecan-Ccr2 inactivation in CCR2-AggKO mice (N=8) resulted in improved ACS score (8-12wk, P=0.002), AC area (4-12wk, P<0.05) and Saf-O score (2wks P=0.004, 4wks P=0.02, 8-12wks P=0.002) compared to CCR2+/+. Increased subchondral bone thickness was delayed only at 2 wks and exclusively following early recombination. Osteophyte size was not affected, but osteophyte maturation (cartilage-to-bone) was delayed (4wks P=0.04; 8 wks P=0.03). Although late aggrecan-Ccr2 deletion led to some cartilage improvement, most data did not reach statistical significance; osteophyte maturity was delayed at 12wks. Early aggrecan-Ccr2 deletion led to improved pain measures of weight bearing compared to CCR2+/+ mice (N = 9, 12wks diff 0.13 [0.01, 0.26], 16wks diff 0.15 [0.05, 0.26], 20wks diff 0.23 [0.14, 0.31]). Improved mechanosensitivity in evoked pain, although less noticeable, was detected.

CONCLUSIONS

We demonstrated that deletion of Ccr2 in aggrecan expressing cells reduces the initiation but not progression of OA.

Construction and analysis of a lncRNA–miRNA–mRNA competing endogenous RNA network from inflamed and normal synovial tissues after anterior cruciate ligament and/or meniscus injuries

Background: Despite ample evidence demonstrating that anterior cruciate ligament (ACL) and meniscus tears are associated with posttraumatic osteoarthritis (PTOA) development, the contributing factors remain unknown. Synovial inflammation has recently been recognized as a pivotal factor in the pathogenesis of OA. However, there is a lack of data on synovial profiles after ACL or meniscus injuries, which may contribute to PTOA.

Methods: Twelve patients with ACL tears and/or meniscus injuries were recruited. During surgery, synovial tissues were obtained from the injured knees. The inflammation status of the synovium was characterized according to macroscopic criteria and histological synovitis grades. Then the synovial tissues were classified as control group or inflamed group. High-throughput RNA sequencing of the synovial samples (3 vs. 3) was conducted to identify differentially expressed (DE) RNAs. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and protein–protein interaction (PPI) analyses were performed to investigate DE mRNAs. Next, competing endogenous RNA (ceRNA) networks were constructed based on bioinformatics analyses. Associations of the identified DE genes (DEGs) with infiltrating immune cells were explored using Pearson correlation analysis.

Results: The results showed that 2793 mRNAs, 3392 lncRNAs and 211 miRNAs were significantly DE between two groups. The top 3 significantly upregulated GO terms and KEGG pathways were immune response, adaptive immune response and immune system process, systemic lupus erythematosus, haematopoietic cell lineage and cytokine–cytokine receptor interaction, respectively. In PPI networks, the top 10 hub genes were IL6, CCR7, C3, CCR5, CXCR3, CXCL8, IL2, CCR3, CCR2 and CXCL1. Seven mRNAs (EPHA5, GSN, ORC1, TLN2, SOX6, NKD2 and ADAMTS19), 4 lncRNAs (MIR4435-2HG, TNXA, CEROX1 and TMEM92-AS1) and 3 miRNAs (miR-486-5p, miR-199a-3p and miR-21-3p) were validated by quantitative real-time polymerase chain reaction and sub-networks were constructed. In correlation analysis, MMP9 correlated positively with M0 macrophages and plasma cells, NKD2 positively with CD8 T cells, and CCR7 and IL2RB positively with naive B cells.

Conclusion: Our study provides foundational synovial inflammation profiles following knee trauma. The ceRNA and PPI networks provide new insight into the biological processes and underlying mechanisms of PTOA. The differential infiltration profiles of immune cells in synovium may contribute to PTOA development. This study also highlights immune-related DEGs as potential PTOA treatment biomarkers.

Bone bruising severity after anterior cruciate ligament rupture predicts elevation of chemokine MCP-1 associated with osteoarthritis

Purpose

Anterior cruciate ligament rupture is associated with characteristic bone contusions in approximately 80% of patients, and these have been correlated with higher pain scores. Bone bruising may indicate joint damage that increases inflammation and the likelihood of posttraumatic osteoarthritis. We sought to characterize the severity of bone bruising following acute anterior cruciate ligament injury and determine if it correlates with synovial fluid and serum levels of the proinflammatory chemokine monocyte chemoattractant protein-1 associated with posttraumatic osteoarthritis.

Methods

This was a retrospective analysis of data collected prospectively from January 2014 through December 2016. All patients who sustained an acute ligament rupture were evaluated within 15 days of injury, obtained a magnetic resonance imaging study, and underwent bone-patellar-tendon-bone autograft reconstruction were offered enrollment. The overall severity of bone bruising on magnetic resonance imaging was graded (sum of 0–3 grades in 13 sectors of the articular surfaces). Serum and synovial fluid levels of monocyte chemoattractant protein-1 were measured within 14 days of injury, and serum levels were again measured 6 and 12 months following surgery. Separate univariate linear regression models were constructed to determine the association between monocyte chemoattractant protein-1 and bone bruising severity at each time point.

Results

Forty-eight subjects were included in this study. They had a mean age of 21.4 years and were 48% female. Median overall bone bruising severity was 5 (range 0–14). Severity of bone bruising correlated with higher synovial fluid concentrations of monocyte chemoattractant protein-1 preoperatively (R² = 0.18, p = 0.009) and with serum concentrations at 12 months post-reconstruction (R² = 0.12, p = 0.04).

Conclusions

The severity of bone bruising following anterior cruciate ligament rupture is associated with higher levels of the proinflammatory cytokine monocyte chemoattractant protein-1 in synovial fluid acutely post-injury and in serum 12-months following anterior cruciate ligament reconstruction. This suggests that severe bone bruising on magnetic resonance imaging after ligament rupture may indicate increased risk for persistent joint inflammation and posttraumatic osteoarthritis.

Level of evidence

III ― retrospective cohort study.

A Morphological Study of the Meniscus, Cartilage and Subchondral Bone Following Closed-Joint Traumatic Impact to the Knee

Post-traumatic osteoarthritis (PTOA) is a debilitating disease that is a result of a breakdown of knee joint tissues following traumatic impact. The interplay of how these tissues influence each other has received little attention because of complex interactions. This study was designed to correlate the degeneration of the menisci, cartilage and subchondral bone following an acute traumatic event that resulted in anterior cruciate ligament (ACL) and medial meniscus tears. We used a well-defined impact injury animal model that ruptures the ACL and tears the menisci. Subsequently, the knee joints underwent ACL reconstruction and morphological analyses were performed on the menisci, cartilage and subchondral bone at 1-, 3- and 6-months following injury. The results showed that the morphological scores of the medial and lateral menisci worsened with time, as did the tibial plateau and femoral condyle articular cartilage scores. The medial meniscus was significantly correlated to the medial tibial subchondral bone at 1 month (p = 0.01), and to the medial tibial cartilage at 3 months (p = 0.04). There was only one significant correlation in the lateral hemijoint, i.e., the lateral tibial cartilage to the lateral tibial subchondral bone at 6 months (p = 0.05). These data may suggest that, following trauma, the observed medial meniscal damage should be treated acutely by means other than a full or partial meniscectomy, since that procedure may have been the primary cause of degenerative changes in the underlying cartilage and subchondral bone. In addition to potentially treating meniscal damage differently, improvements could be made in optimizing treatment of acute knee trauma.