Böcker et al. 2026 state the trabecular>cortical turnover premise as a single unqualified sentence, citing Parfitt 2002 (ref 21) with no site, age, or method caveat

space-medicineaerospace-physiologybone-densitytrabecular-corticalbone-turnoververification

Böcker et al. 2026 introduce the turnover-rate mechanism beneath their bed-rest / spaceflight comparison in one sentence: "Trabecular bone exhibits a higher turnover rate than cortical bone21. However, the results of previous studies showed contrary results regarding the losses of the specific bone tissues." The superscript 21 anchors the premise to reference 21 — A.M. Parfitt's 2002 Bone commentary "Misconceptions (2): turnover is always higher in cancellous than in cortical bone" — and the sentence carries no qualification: no skeletal site, no age range, no measurement method, no remodeling-versus-surface-area distinction. The premise is stated as a general physiological fact and immediately pivots into the compartment-disagreement discussion that claim-bocker-refs-support-bedrest-cortical-spaceflight-trabecular-dissociation confirms is genuine at the level of bed-rest versus spaceflight outcomes.

This note records only how Böcker frames the premise and what it is cited to — a fact fully grounded in Böcker's own open-access text (the same document, sha256 c280147b…, whose reference list confirms ref 21 = Parfitt, A.M., Bone 30, 807–809, 2002). It does not assert that the premise is true, nor that Parfitt's paper supports it. Whether Parfitt 2002 actually endorses an unconditional "trabecular turns over faster" reading is unresolved and tracked at question-parfitt-2002-trabecular-cortical-turnover-premise; the paper's own title reads like a caution against exactly the "always" that Böcker's unqualified phrasing supplies. The mechanistic frame here also underwrites the derived-rate note claim-bocker-tibial-losses-match-stavnichuk-only-at-epiphyseal-sites.