Iannotti and colleagues measured the normal humeral and glenoid articular surfaces and their spatial relationships in a representative population of shoulders.
140 shoulders: 96 measured in cadavera and 44 on MRI of living patients.
Methods
Specimens
96 cadaveric shoulders
44 shoulders on MRI of living patients
Measurements
Humeral head radius of curvature (coronal and axial)
Humeral head thickness
Glenoid superior‑inferior and anterior‑posterior dimensions
Glenoid radius of curvature
Lateral humeral offset
Height of articular surface above greater tuberosity
Key Findings
85% of humeral head sizes fell into just eight radius‑and‑thickness combinations set at 2‑mm steps.
Head radius correlated with height (R = 0.985) and differed by sex, averaging 25 mm in men vs 21 mm in women (p < 0.01).
The head was spherical centrally but elliptical at the periphery, with the axial radius 2 mm smaller than the coronal radius (ratio 0.92).
The glenoid's superior‑inferior radius of curvature exceeded the humeral head's by a mean of 2.3 ± 0.2 mm.
The glenoid was pear‑shaped, with its lower half wider than its upper half (lower to upper ratio 1:0.80 ± 0.01).
Lateral humeral offset, measured from the coracoid base to the most lateral greater tuberosity, correlated with head size (R = 0.998).
Board pearl
In every shoulder measured for this relationship, the top of the humeral articular surface sat above the top of the greater tuberosity.
Authors' conclusion
Our data show that reconstruction of the lateral humeral offset is important in optimization of the moment arm of the deltoid and rotator cuff and of the normal tension of the soft tissue after prosthetic reconstruction.
Iannotti and colleagues measured the normal humeral and glenoid articular surfaces and their spatial relationships in a representative population of shoulders.
140 shoulders: 96 measured in cadavera and 44 on MRI of living patients.
Methods
Specimens
96 cadaveric shoulders
44 shoulders on MRI of living patients
Measurements
Humeral head radius of curvature (coronal and axial)
Humeral head thickness
Glenoid superior‑inferior and anterior‑posterior dimensions
Glenoid radius of curvature
Lateral humeral offset
Height of articular surface above greater tuberosity
Key Findings
85% of humeral head sizes fell into just eight radius‑and‑thickness combinations set at 2‑mm steps.
Head radius correlated with height (R = 0.985) and differed by sex, averaging 25 mm in men vs 21 mm in women (p < 0.01).
The head was spherical centrally but elliptical at the periphery, with the axial radius 2 mm smaller than the coronal radius (ratio 0.92).
The glenoid's superior‑inferior radius of curvature exceeded the humeral head's by a mean of 2.3 ± 0.2 mm.
The glenoid was pear‑shaped, with its lower half wider than its upper half (lower to upper ratio 1:0.80 ± 0.01).
Lateral humeral offset, measured from the coracoid base to the most lateral greater tuberosity, correlated with head size (R = 0.998).
Board pearl
In every shoulder measured for this relationship, the top of the humeral articular surface sat above the top of the greater tuberosity.
Authors' conclusion
Our data show that reconstruction of the lateral humeral offset is important in optimization of the moment arm of the deltoid and rotator cuff and of the normal tension of the soft tissue after prosthetic reconstruction.