In middle-aged persons with mostly mild radiographic OA, structural features changed little over a year and weight loss was not associated with effects on structural changes.

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Objective Massive weight loss leads to marked knee pain reduction in individuals with knee pain, but the reason for the reduction in pain is unknown. This study was undertaken to quantify the contribution of magnetic resonance imaging (MRI)–evidenced changes in pain‐sensitive structures, bone marrow lesions (BMLs), and synovitis, and changes in pain sensitization or depressive symptoms, to knee pain improvement after substantial weight loss. Methods Morbidly obese patients with knee pain on most days were evaluated before bariatric surgery or medical weight management and at 1‐year follow‐up for BMLs and synovitis seen on MRI, the pressure pain threshold (PPT) at the patella and the right wrist, depressive symptoms (using the Center for Epidemiologic Studies Depression scale [CES‐D]), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain survey. Natural‐effects models were used to quantify the extent that achieving a minimum clinically important difference (MCID) of ≥18% on the WOMAC pain scale could be mediated by weight loss–induced changes in BMLs, synovitis, PPT, and depressive symptoms. Results Of 75 participants, 53.3% lost ≥20% of weight by 1 year. Of these, 75% attained the MCID for pain improvement, compared with 34.3% in those who had <20% weight loss. Mediation analyses suggested that, in those with at least 20% weight loss, the odds of pain improvement increased by 62%, 15%, and 22% through changes in patella PPT, wrist PPT, and CES‐D, respectively, but pain improvement was not mediated by MRI changes in BMLs or synovitis. Conclusion Weight loss–induced knee pain improvement is partially mediated by changes in pain sensitization and depressive symptoms but is independent of MRI changes in BMLs and synovitis.

The Buchwald-Hartwig C-N coupling reaction has found widespread applications in organic synthesis.O ver the past two decades or so,m any improved catalysts have been introduced, allowing various amines and aryl electrophiles to be readily used nowadays.However,there lacks aprotocol that could be used to couple awide range of chiral amines and aryl halides,w ithout erosion of the enantiomeric excess (ee). Reported in this article is am ethod based on molecular Ni catalysis driven by light, which enables stereoretentive C-N coupling of optically active amines,amino alcohols,and amino acid esters with aryl bromides,w ith no need for any external photosensitizer.T he method is effective for aw ide variety of coupling partners,i ncluding those bearing functional groups sensitive to bases and nucleophiles,t hus providing av iable alternative to accessing synthetically important chiral N-aryl amines,amino alcohols,and amino acids esters.Its viability is demonstrated by 92 examples with up to 99 %ee. Scheme 1. Metal catalyzed C-N coupling of aryl halides for the synthesis of chiral N-aryl amines and amino acid esters.

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