Spencer and colleagues cut single ligaments in cadaver specimens to identify which structure chiefly limits forward and backward movement of the clavicle at the sternoclavicular joint.
Cadaver study of 24 unpaired specimens, 6 per sectioned ligament.
Methods
Model
Clavicles and first 3 ribs obtained from 32 fresh‑frozen cadavers (mean age 71.6, 14 male, 18 female)
24 unpaired specimens tested in a custom fixture
Constructs
Intact joint tested first, then retested after one randomly chosen structure was cut
Anterior capsule (6 specimens)
Posterior capsule (6 specimens)
Interclavicular ligament (6 specimens)
Costoclavicular ligament (6 specimens)
Loading
Sub‑failure test load of 133.5 N in the anterior and posterior directions, set near the lower bound of the failure‑load 95% CI
Outcome measures
Anterior clavicular translation (mm) before and after sectioning
Posterior clavicular translation (mm) before and after sectioning
Key Findings
Sectioning the posterior capsule significantly increased clavicular translation in both directions, making it the primary restraint both anteriorly and posteriorly.
Posterior translation more than doubled after the posterior capsule was cut, from a mean 3.67 mm to 7.58 mm.
Cutting the anterior capsule significantly increased anterior translation, by a mean 3.28 mm.
Cutting the costoclavicular or interclavicular ligament changed translation by less than 1 mm in either direction, and their effects on anterior translation did not differ (p = 0.67).
The authors suggest reconstructions should restore the posterior capsule in every unstable joint and add the anterior capsule for anterior instability.
Testing used sub‑failure loads in a neutral position on elderly specimens, so a traumatic dislocation may recruit other structures.
Board pearl
In this cadaver model, the posterior capsule was the primary restraint to sternoclavicular translation in both directions, while the costoclavicular ligament contributed little.
Authors' conclusion
The posterior capsule is the most important restraint for anterior and posterior translation of the sternoclavicular joint. The anterior capsule is another important restraint for anterior translation. The costoclavicular and interclavicular ligaments have little effect on anterior or posterior translation of the sternoclavicular joint.
Spencer and colleagues cut single ligaments in cadaver specimens to identify which structure chiefly limits forward and backward movement of the clavicle at the sternoclavicular joint.
Cadaver study of 24 unpaired specimens, 6 per sectioned ligament.
Methods
Model
Clavicles and first 3 ribs obtained from 32 fresh‑frozen cadavers (mean age 71.6, 14 male, 18 female)
24 unpaired specimens tested in a custom fixture
Constructs
Intact joint tested first, then retested after one randomly chosen structure was cut
Anterior capsule (6 specimens)
Posterior capsule (6 specimens)
Interclavicular ligament (6 specimens)
Costoclavicular ligament (6 specimens)
Loading
Sub‑failure test load of 133.5 N in the anterior and posterior directions, set near the lower bound of the failure‑load 95% CI
Outcome measures
Anterior clavicular translation (mm) before and after sectioning
Posterior clavicular translation (mm) before and after sectioning
Key Findings
Sectioning the posterior capsule significantly increased clavicular translation in both directions, making it the primary restraint both anteriorly and posteriorly.
Posterior translation more than doubled after the posterior capsule was cut, from a mean 3.67 mm to 7.58 mm.
Cutting the anterior capsule significantly increased anterior translation, by a mean 3.28 mm.
Cutting the costoclavicular or interclavicular ligament changed translation by less than 1 mm in either direction, and their effects on anterior translation did not differ (p = 0.67).
The authors suggest reconstructions should restore the posterior capsule in every unstable joint and add the anterior capsule for anterior instability.
Testing used sub‑failure loads in a neutral position on elderly specimens, so a traumatic dislocation may recruit other structures.
Board pearl
In this cadaver model, the posterior capsule was the primary restraint to sternoclavicular translation in both directions, while the costoclavicular ligament contributed little.
Authors' conclusion
The posterior capsule is the most important restraint for anterior and posterior translation of the sternoclavicular joint. The anterior capsule is another important restraint for anterior translation. The costoclavicular and interclavicular ligaments have little effect on anterior or posterior translation of the sternoclavicular joint.