Lerebours et al. 2020, independent of both Böcker and Parfitt, cite Parfitt 2002 in both directions — as authority for the standard ~4x cortical/trabecular turnover gap and as caution against generalizing it

space-medicinebone-densitytrabecular-corticalbone-turnoververification

Lerebours, Weinkamer, Roschger and Buenzli (2020, Bone Reports) — a peer-reviewed modeling study of mineral-density differences between femoral cortical and trabecular bone, unaffiliated with either Böcker et al. or Parfitt — cite Parfitt 2002 five times, and put it to opposite purposes. First as standard-figure authority: "regions of femoral cortical bone of low porosity may be turned over roughly 4 times slower than trabecular bone (Eriksen et al., 2002; Parfitt, 1983, 2002)," grouping Parfitt 2002 with his own 1983 chapter and Eriksen et al. 2002 as joint support for the conventional several-fold gap. Second as a caution against generalizing that gap: discussing an alternative explanation for their own experimental findings, they attribute to Parfitt 2002 the "lack of reliable data about turnover rates depending on different skeletal sites and, in particular, different bone types (i.e., cortical vs. trabecular)," adding that if the two bone types "are turned over with more similar rates than what is usually assumed," the similarity in their mineral-density distributions is "less surprising."

The other three citations fall on either side of the same split: the Introduction's "Since turnover rates are normally lower in femoral cortical bone than in trabecular bone (Manolagas, 2000; Parfitt, 2002)" and Hypothesis 1's "the well-known difference in turnover between bone types (Parfitt, 2002)" use him for the direction, while the Discussion's "the natural variability of turnover across bone sites and individuals, which is expected to be much larger (Parfitt, 2002)" uses him for the variability caution again.

So an independent paper that itself relies on Parfitt 2002 treats it simultaneously as (a) a co-source for the standard "trabecular turns over several-fold faster" figure and (b) the specific citation for doubting that cortical/trabecular turnover differences are reliably characterized across sites at all. That pattern fits a paper whose title targets the word "always" — a caution against unconditional generalization — rather than a reversal of the comparison's direction. The claim here is one layer removed from Parfitt's own words: it is about how later literature uses Parfitt 2002, not a direct read of it, which remains owed at question-parfitt-2002-trabecular-cortical-turnover-premise.

This sharpens rather than resolves the premise beneath the compartment cluster. The unqualified form Böcker gives it (claim-bocker-2026-cites-parfitt-2002-unqualified-for-trabecular-turnover-premise) is the exact generalization Lerebours cite the same underlying paper to caution against — yet the general direction has independent support (Eriksen et al. 2002, Parfitt 1983). The turnover-rate mechanism under claim-bocker-refs-support-bedrest-cortical-spaceflight-trabecular-dissociation and claim-bocker-tibial-losses-match-stavnichuk-only-at-epiphyseal-sites is therefore best read as directionally corroborated but not settled at the unconditional, skeleton-wide resolution Böcker's sentence asserts. The compartment-level dissociation those notes confirm does not require the turnover explanation to be complete or unconditional — only directionally present. The load-bearing figure (~4x) rests on Tier 1 sources but is not independently verified against Parfitt's own text this session, so it is not recorded as a standalone quantitative claim-note here.