Continuing periosteal apposition. I: Documentation, hypotheses, and interpretation

Area of Science:

• Skeletal Biology
• Osteology
• Human Anatomy

Background:

• Continuing periosteal apposition (CPA) is the addition of new lamellar bone, leading to increased skeletal size in adults.
• This phenomenon has been observed in various adult cranial and postcranial bones.

Purpose of the Study:

• To review studies investigating age-related changes in skeletal dimensions.
• To examine hypotheses proposed to explain CPA.
• To address challenges in interpreting CPA due to small effect sizes and statistical power.

Main Methods:

• Systematic review of 42 studies published from 1964 onwards.
• Analysis of studies reporting significant and nonsignificant age-related changes in skeletal dimensions (length, diameter, width, area).
• Consideration of four postulated hypotheses for CPA: cohort effect, mechanical compensation, bone repair/response, and heterochrony.
• Power analysis of selected studies to assess statistical significance.

Main Results:

• Studies show varied age-related changes in skeletal dimensions, with some significant and others nonsignificant.
• The four hypotheses for CPA remain largely speculative due to a lack of rigorous testing.
• Small effect sizes in CPA research, often coupled with restricted sample sizes, limit statistical power.
• Power analysis revealed that studies reporting nonsignificant results had a low probability of detecting a true effect.

Conclusions:

• Interpreting age-related skeletal size changes like CPA is challenging due to statistical limitations.
• Distinguishing between statistical and biological significance requires careful consideration of effect size and study power.
• Further research with larger sample sizes and robust statistical methods is needed to validate hypotheses and confirm CPA.