SMW Supplementum 193 - Swiss Medical Weekly

25 S SWiSS Med Wkly 2012;142(Suppl 193) · www.smw.ch Free communications
patients (30%) showed a poor Merle d’Aubigné Score, of which three
had to undergo THA (10%) because of acetabular erosion (grade 3
in two patients, grade 2 in one patient). All patients showed mild
migration of the femoral head (Baker grade 1) due to the cartilage
erosion, whereas erosion of the bony acetabulum (Baker grade
2 and 3) was only seen in 3 patients (10%).
Conclusion: Hemiarthroplasty in patients younger than 65 years
leads to unsatisfactory results. One third of the patients had to be
converted to THA or had a poor functional outcome after 10 years.
This may be due to the erosion of the acetabular cartilage seen in all
patients, suggesting that cartilage erosion is an early event. However,
erosion of the bony acetabular roof is rare (10%) in this relatively
young patient group.
FM96
The Critical Shoulder Angle: A New Radiological Tool
in the Assessment of Patients with Degenerative
Shoulder Pathologies
Beat Moor1 , Samy Bouaicha2 , Dominique A. Rothenfluh1 ,
Atul Sukthankar1 , Christian Gerber1 1Uniklinik Balgrist; 2Division of Trauma Surgery,
University Hospital of Zurich
Background: The role of bony geometry for the development of
degenerative disorders of the shoulder remains unclear. Some
radiographic parameters have been studied as predictive factors
for rotator cuff tears (RCT), but anatomical predictors for primary
osteoarthritis (OA) have not been identified. We hypothesized that the
combination of a wide acromion with an upward tilted glenoid fossa
would be particularly prone to supraspinatus tears whereas a short
lateral extension with an inferiorly inclined glenoid would lead to
osteoarthritis of the glenohumeral joint. This hypothesis was tested
using the so-called critical shoulder angle (CSA), a new radiographic
parameter, which represents a measurement of the combination of
glenoid inclination and lateral extension of the acromion.
Methods: The CSA was measured in 94 asymptomatic shoulders
with normal radiographs and sonograms, in 102 shoulders with
documented RCTs without OA and in 102 shoulders with primary
OA and absence of RCTs.
Results: The mean CSA was 33.1 ± 2.0° in the control group, 38.0 ±
2.7° in the RCT group and 28.1 ± 3.3° in shoulders with OA. These
differences were all significant (p