Binary and analogue markers of skeletal maturity: Clinical utility of the thenar and plantar sesamoids

Abstract

PurposeWe investigate the thenar and plantar sesamoids as markers of skeletal maturity, and grade appearance using two scales, a binary system (absent or present), and an analogue system that relies upon judging regular changes in morphological appearance.MethodsWe studied 94 healthy children (49 female and 45 male patients) between ages three and 18 years who had approximately 700 serially acquired sets of radiographs and physical examinations. The children had at least annual radiographs taken of the left hand and left foot. Velocity of growth was calculated and curves were fit to a cubic spline model to determine age of maximum height velocity, or peak height velocity (PHV). Appearance of the plantar and thenar sesamoids was recorded using a binary system classifying the sesamoids as absent or present and an analogue system classifying the sesamoid as absent, present as a small ossification centre or larger than a small ossification centre.ResultsThe plantar sesamoids appear 1.67 years before PHV and reach mature size 1.02 years after PHV. The thenar sesamoids appear 0.32 years before PHV and reach mature size 2.25 years after PHV. The plantar sesamoids are present and thenar sesamoids are absent at a mean 1.5 years prior to PHV. No patients had the thenar sesamoids present while the plantar sesamoids were absent.ConclusionAs binary markers, when the plantar and thenar sesamoids are considered together it is possible to localize maturity. As analogue markers, they offer more information. The sesamoids also allow clarification of the calcaneal and Sanders stages.Level of EvidenceNot Applicable.

The More the Merrier: Integrating Multiple Models of Skeletal Maturity Improves the Accuracy of Growth Prediction

“…Systems that rely on analog markers of maturity, such as the GP Atlas and the Sanders Hand Classification, require clinicians to interpret morphologic changes at various ossification centers. 16 Given the subjectivity of these interpretations, prediction models relying on analog markers are prone to intraobserver and interobserver variability. [16][17][18] Cundy et al 17 examined the interpretation of 60 hand radiographs using the GP Atlas by 4 separate radiologists and found that half were assigned a skeletal age that differed by > 1 year and 10% varied by > 2 years between radiologists.…”

“…To improve the objectivity in estimating bone age, other systems primarily utilize binary markers of osteologic maturity and assess whether a radiographic feature is present or absent. 16 The Shorthand Bone Age Assessment (SBA), for example, incorporates the presence of the hook of the hamate ossific nucleus, as well as the presence of the thumb sesamoid ossific nucleus, among other criteria to provide an estimate of bone age. 19 Given the more definitive nature of the skeletal assessment, systems utilizing binary markers have proven to have lower intraobserver and interobserver variability in comparison to systems composed primarily of analog markers.…”

“…Analog markers are indiscrete and often demonstrate interobserver disagreement whereas binary markers are discrete and exhibit minimal interobserver disagreement. Systems that rely on analog markers of maturity, such as the GP Atlas and the Sanders Hand Classification, require clinicians to interpret morphologic changes at various ossification centers 16. Given the subjectivity of these interpretations, prediction models relying on analog markers are prone to intraobserver and interobserver variability 16–18.…”

“…To improve the objectivity in estimating bone age, other systems primarily utilize binary markers of osteologic maturity and assess whether a radiographic feature is present or absent 16. The Shorthand Bone Age Assessment (SBA), for example, incorporates the presence of the hook of the hamate ossific nucleus, as well as the presence of the thumb sesamoid ossific nucleus, among other criteria to provide an estimate of bone age 19.…”