On-track Hills-Sachs defect

Case contributed by Dr Mohamed Saber

Presentation

Trauma to the shoulder 20 days ago followed by dislocation, relocation done on the emergency room

Patient Data

Age: 20 years
Gender: Male
MRI

MRI study shows an abnormal anterior glenoid labrum seen involved with an abnormal signal (intermediate in T2 and STIR) likely injured.

Localized cortical impaction is seen involving the posterolateral aspect of the humeral head consistent with a Hill Sachs defect.

No evidence of glenoid bony loss

Annotated image

The Hill- Sachs interval measures 19 mm.

The glenoid track measures 20.75 mm.

Case Discussion

The glenoid track refers to the area of contact between the humeral head and glenoid and is defined as ~83% of glenoid width. A Hill-Sachs defect that is smaller than the track ("on-track") will maintain contact and is at lower risk of engagement and instability during full range shoulder movement especially abduction. Conversely, a Hill-Sachs defect that is larger than the glenoid track ("off-track") will be at increased risk of engagement and instability (i.e. is an "engaging Hill-Sachs defect"). 

Evaluation of the glenoid track status should be done routinely in the cross-sectional imaging assessment of the shoulder joint in cases of anterior instability. Determination if the lesion is on-track or off-track can greatly affect management including different operative approaches if surgery is required 1.

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Case information

rID: 89240
Published: 21st May 2021
Last edited: 24th May 2021
Inclusion in quiz mode: Included
Institution: Faculty of medicine Al-Azhar University

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