Validation study of the Thumb Ossification Composite Index (TOCI) in idiopathic scoliosis – a stage to stage correlation with Classic Tanner Whitehouse and Sander’s Simplified Skeletal Maturity System (SSMS)
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AbstractPurpose: The new simplified thumb ossification composite index (TOCI) based on thumb epiphyses
ossification and adductor sesamoid has been shown to be simple, reliable and accurate inpredicting skeletal
maturity in idiopathic scoliosis (IS) comparable to the Tanner-WhiteHouse (TW3) derived Sanders’ SSMS
system. To further improve the understanding and clinical applicability of TOCI , we conducted the study with
the objective to validate in detail the stage to stage correlation of TOCI with the TW3 and SSMS systems
throughout peri-pubertal period.
Methods: Hand radiographs of 125 pre-menarche newly diagnosed IS girls (mean age 11.3) followed at 6
monthly interval longitudinally until skeletal maturity confirmed with completed radius physeal fusion)
.Ossification pattern of all small hand bone digital epiphyses were scored simultaneously with the TW3 staging
(from F to I), TOCI and SSMS system. The TOCI score were then compared stage to stage with the TW3 and
SSMS and correlated with timing of the peak height velocity (PHV). Correlations were analysed with Chisquare
test, Spearman, Cramer’s V and Somer’s delta correlation.
Results: 645 hand radiographs (average 5 from each AIS girl) and 11517 epiphyses were scored. The
concordance rate of TW3 stage F, G, I in thumb PP epiphysis versus all epiphyses of the 4 ulnar digits were
72.5%, 72.5%, 90% respectively. The overall concordance rate (including all epiphyses) was 71.3% with high
Cramer’s V correlation and statistical significance (p<0.01)[Table 1]. TOCI is highly correlated with SSMS
(r=0.92, p<0.05). For the important peripubertal periods, excellent stages correlations was found for Pre-PHV
period (TOCI 3 &4 vs SSMS 2); PHV period (TOCI 5 vs SSMS 3); post-PHV period (TOCI 8 vs SSMS 7) with
overall concordance rate of 54%, 90.8% and 88% respectively , and further supported by the high Somer’s delta
correlation (>0.8) with statistical significance (p<0.05)[Figure 1].
Conclusions: By focusing the assessment on two thumb epiphyses and sesamoid bone i.e. 3 instead of 19 of
the small hand bones, the TOCI system was found to provide a reliable stage to stage comparability and
interchangeability with the SSMS . In addition, TOCI has the advantages of showing finer predictability of
skeletal maturity in the pre-PHV period, higher sensitivity to predict PHV timing and late phase of growth
remaining period.
Significance: TOCI could serve as a new practical system to simplify further the interpretation and staging of
the skeletal maturity status with improved precision based on the thumb related epiphyses ossification pattern in
the busy clinic setting.
All Author(s) ListAlec Hung, Simon Chow, Wai Wang Chau, Tsz Ping Lam, Bobby Ng, Jack Cheng
Name of Conference2018 Annual Meeting of Pediatric Orthopaedics Society of North America (POSNA)
Start Date of Conference09/05/2018
End Date of Conference12/05/2018
Place of ConferenceAustin, Texas
Country/Region of ConferenceUnited States of America
Proceedings TitleThe Proceedings of 2018 Annual Meeting of Pediatric Orthopaedics Society of North America (POSNA)
LanguagesEnglish-United Kingdom

Last updated on 2018-12-06 at 15:47