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[Age-related characteristics of the human acromioclavicular joint]
Insights
The acromioclavicular joint
Area of Science:
- Anatomy
- Histology
- Developmental Biology
Background:
- The acromioclavicular (AC) joint's development involves osseous and cartilaginous components.
- Articular surface morphology and area ratios change significantly from birth through adulthood.
Purpose of the Study:
- To detail the developmental changes in the AC joint's articular surfaces and cartilage.
- To correlate structural changes with functional loading and aging.
Main Methods:
- Descriptive analysis of anatomical and histological changes.
- Age-based comparison of articular surface morphology, area, and cartilage composition.
Main Results:
- Significant differences in articular surface area ratios occur between 1-3, 13-17, and 21-30 years.
- Hyaline cartilage in the clavicle transitions to fibrous cartilage by 17 years; in the acromion, this occurs after 23-24 years.
- Unequal cartilage thickness suggests differential functional loading, with involutional changes noted by the fourth decade.
Conclusions:
- The AC joint undergoes significant structural remodeling throughout life.
- Cartilage type transformation and differential loading patterns are key features of AC joint development and aging.
Abstract:
By birth in the acromioclavicular joint the acromial end of the clavicle is osseous, and the acromion of the scapula is cartilaginous. The most intensive formation of the relief and configuration of the articular surfaces of the joint occurs from 1 to 3 years of age. In mature persons the form of the articular surface of the acromial end of the clavicle is often oval and that of the acromion of the scapula--ellipsoid. In newborns the areas of the articular surfaces are nearly equal. The area of the articular surface of the acromial end of the clavicle is significantly more than that of the acromion of the scapula during the periods from 1 to 3, from 13 to 17 and from 21 to 30 years of age. The articular cleft is revealed in the roentgenograms by 17 years of age, when synostosis process of the acromion of the scapula is completed. The thickness of the articular cartilage at different poles of the articular surfaces from birth up to 70 years of age is not equal and therefore it is possible to judge about nonequivalent functional loading on different areas of the articular cartilage. The articular cartilage of the acromial end of the clavicle from birth to 16 years of age is hyaline, after 17 years of age, they acquire the structure of the fibrous cartilage. In the articular cartilage of the acromion of the scapula, this rearrangement is realized more slowly: its fibrous structure is revealed after 23-24 years of age. Involutional changes in the joint are revealed during the fourth decade.(ABSTRACT TRUNCATED AT 250 WORDS)