Development of a Magnetic Resonance Imaging-Based Definition of Knee Osteoarthritis: Data From the Multicenter Osteoarthritis Study

Serum levels of hydroxylated metabolites of arachidonic acid cross-sectionally and longitudinally predict knee pain progression: an observational cohort study

OBJECTIVE

To examine associations between serum oxylipins, which regulate tissue repair and pain signalling, and knee pain/radiographic osteoarthritis (OA) at baseline and knee pain at 3 year follow-up.

METHOD

Baseline, and 3 year follow-up, knee pain phenotypes were assessed from 154 participants in the Knee Pain in the Community (KPIC) cohort study. Serum and radiographic Kellgren and Lawrence (KL) and Nottingham line drawing atlas OA scores were collected at baseline. Oxylipin levels were quantified using liquid chromatography coupled with mass spectrometry. Associations were measured by linear regression and receiver operating characteristics (ROC).

RESULTS

Serum levels of 8,9-epoxyeicosatrienoic acid (EET) (β(95% confidence intervals (CI)) = 1.809 (-0.71 to 2.91)), 14,15-dihydroxyeicosatrienoic acid (DHET) (β(95%CI) = 0.827 (0.34-1.31)), and 12-hydroxyeicosatetraenoic acid (HETE) (β(95%CI) = 4.090 (1.92-6.26)) and anandamide (β(95%CI) = 3.060 (1.35-4.77)) were cross-sectionally associated with current self-reported knee pain scores (numerical rating scale (NRS) item 3, average pain). Serum levels of 9- (β(95%CI) = 0.467 (0.18-0.75)) and 15-HETE (β(95%CI) = 0.759 (0.29-1.22)), 14-hydroxydocosahexaenoic acid (β(95%CI) = 0.483(0.24-0.73)), and the ratio of 8,9-EET:DHET (β(95%CI) = 0.510(0.19-0.82)) were cross-sectionally associated with KL scores. Baseline serum concentrations of 8,9-EET (β(95%CI) = 2.166 (0.89-3.44)), 5,6-DHET (β(95%CI) = 152.179 (69.39-234.97)), and 5-HETE (β(95%CI) = 1.724 (0.677-2.77) showed positive longitudinal associations with follow-up knee pain scores (NRS item 3, average pain). Combined serum 8,9-EET and 5-HETE concentration showed the strongest longitudinal association (β(95%CI) = 1.156 (0.54-1.77) with pain scores at 3 years, and ROC curves distinguished between participants with no pain and high pain scores at follow-up (area under curve (95%CI) = 0.71 (0.61-0.82)).

CONCLUSIONS

Serum levels of a combination of hydroxylated metabolites of arachidonic acid may have prognostic utility for knee pain, providing a potential novel approach to identify people who are more likely to have debilitating pain in the future.

Diagnostic Accuracy of Candidate Magnetic Resonance Imaging Knee Osteoarthritis Definitions Versus Radiograph in an Acute Anterior Cruciate Ligament Injury Cohort

OBJECTIVE

We tested the diagnostic accuracy of previously proposed magnetic resonance imaging (MRI) osteoarthritis (OA) definitions in a cohort after acute anterior cruciate ligament (ACL) injury.

METHODS

We studied participants with posteroanterior and lateral knee radiographs and MRI 5 years after ACL injury, scored using the Anterior Cruciate Ligament Osteoarthritis Score. Radiographic OA (ROA) was defined using Osteoarthritis Research Society International scoring of osteophytes and joint space narrowing considering medial/lateral tibiofemoral and patellofemoral compartments. We tested three candidate MRI OA definitions that performed well in an older adult cohort. "Multicenter Osteoarthritis Study (MOST) simple" required cartilage score ≥2 (range 0-6) and osteophyte score ≥2 (0-7); "MOST optional" included cartilage score ≥2, osteophyte score ≥2, and either bone marrow lesions (BMLs) ≥1 (0-3) or synovitis ≥2 (0-3). The third, a Delphi panel definition, included nonzero scores for cartilage, osteophyte, BMLs, meniscus, and other structures. We calculated sensitivity and specificity with 95% confidence intervals (95% CIs) for each MRI definition versus ROA.

RESULTS

We included 113 participants (mean age 26 years, 26% female). At 5 years, 29 participants (26%) had ROA. "MOST simple" had a sensitivity of 52% (95% CI 33%-71%), and specificity of 76% (95% CI 66%-85%). Sensitivity and specificities for "MOST optional" were 28% (95% CI 29%-67%) and 83% (95% CI 74%-91%), respectively. The Delphi panel definition had a sensitivity of 48% (95% CI 29%-67%) and specificity of 77% (95% CI 67%-86%).

CONCLUSION

Simple MRI-based OA definitions requiring at least cartilage damage and an osteophyte have low sensitivity and high specificity in young persons after knee injury.

Two-year MRI-defined structural damage and patient-reported outcomes following surgery or exercise for meniscal tears in young adults

OBJECTIVE

To investigate potential differences in structural knee joint damage assessed by MRI and patient-reported outcomes (PROMs) at 2-year follow-up between young adults randomised to early surgery or exercise and education with optional delayed surgery for a meniscal tear.

METHODS

A secondary analysis of a multicentre randomised controlled trial including 121 patients (18-40 years) with an MRI-verified meniscal tear. For this study, only patients with 2-year follow-up were included. The main outcomes were the difference in worsening of structural knee damage, assessed by MRI using the Anterior Cruciate Ligament OsteoArthrits Score, and the difference in change in the mean score of four Knee Injury and Osteoarthritis Outcome Score (KOOS4) subscales covering pain, symptoms, function in sport and recreation, and quality of life, from baseline to 2 years.

RESULTS

In total, 82/121 (68%) patients completed the 2-year follow-up (39 from the surgical group and 43 from the exercise group). MRI-defined cartilage damage had developed or progressed in seven (9.1%) patients and osteophytes developed in two (2.6%) patients. The worsening of structural damage from baseline to 2-year follow-up was similar between groups. The mean (95% CI) adjusted differences in change in KOOS4 between intervention groups from baseline to 2 years was -1.4 (-9.1, 6.2) points. The mean improvement in KOOS4 was 16.4 (10.4, 22.4) in the surgical group and 21.5 (15.0, 28.0) in the exercise group. No between group differences in improvement were found in the KOOS subscales.

CONCLUSIONS

The 2-year worsening of MRI-defined structural damage was limited and similar in young adult patients with a meniscal tear treated with surgery or exercise with optional delayed surgery. Both groups had similar clinically relevant improvements in KOOS4, suggesting the choice of treatment strategy does not impact 2-year structural knee damage or PROMs.

TRIAL REGISTRATION NUMBER

NCT02995551.