Ultrasound-detected accelerated fat deposition in the vastus medialis as a marker for early knee osteoarthritis

Abstract

Importance: The absence of a reliable marker of early-stage knee osteoarthritis (KOA) represents a missed opportunity to develop interventions that restore joint integrity. The use of ultrasonography (US) to measure fat infiltration of muscle, which has been associated with incidence and progression of KOA, is one possible solution. Summarizing the trajectory of fatty infiltration during natural aging and KOA processes and establishing US-implementation as a tool for the early diagnosis of KOA represent essential first steps. Objective: (1) To summarize the alterations in quadriceps muscle quality during healthy aging (young vs. older) and in the setting of KOA (older vs. KOA) using computational approaches, and (2) to validate and translate these findings by applying US assessment of muscle quality in a clinical setting. Design, Setting, Participants: Systematic review with network meta-analysis integrated with a subsequent case-control validation study in an orthopedic clinic. Both analyses evaluated three groups: healthy young, healthy older, and individuals with KOA. Main outcome and Measures: Quadriceps muscle quality assessed by US. Results: Data from a total of 718 healthy aging individuals (young, n = 336; old, n = 382) and 1,046 individuals with KOA (old, n = 625; KOA, n = 421) were synthesized for meta-analyses. As determined by US, older adults displayed poor quadriceps muscle quality compared to young; this decline was significantly exacerbated when individuals had KOA. The network meta-analysis revealed that the presence of KOA significantly accelerated muscle fatty infiltration compared to natural aging. Notably, US findings were comparable to gold-standard imaging modalities of both MRI and CT for fat infiltration in skeletal muscle. The findings from these computational analyses were supported by an US-implemented validation study in a clinical setting, which also identified the vastus medialis as the most sensitive quadricep muscle to predict both the onset and development of KOA. Conclusions and Relevance: This study established accelerated fat deposition in the vastus medialis as a distinct marker for early KOA, as reliably identified by US. These findings expand opportunities for the early diagnosis and treatment for KOA in a clinical setting given the increased cost-efficiency and accessibility of the US system compared to MRI or CT. Trial registration: PROSPERO Identifier: CRD 42022380856