Glenoid bone loss can be a challenging problem when revising
a shoulder arthroplasty. Precise pre-operative planning based on
plain radiographs or CT scans is essential. We have investigated
a new radiological classification system to describe the degree
of medialisation of the bony glenoid and that will indicate the
amount of bone potentially available for supporting a glenoid component.
It depends on the relationship between the most medial part of the
articular surface of the glenoid with the base of the coracoid process
and the spinoglenoid notch: it classifies the degree of bone loss
into three types. It also attempts to predict the type of glenoid reconstruction
that may be possible (impaction bone grafting, structural grafting
or simple non-augmented arthroplasty) and gives guidance about whether
a pre-operative CT scan is indicated. Inter-method reliability between plain radiographs and CT scans
was assessed retrospectively by three independent observers using
data from 39 randomly selected patients. Inter-observer reliability and test-retest reliability was tested
on the same cohort using Cohen's kappa statistics. Correlation of
the type of glenoid with the Constant score and its pain component
was analysed using the Kruskal-Wallis method on data from 128 patients.
Anatomical studies of the scapula were reviewed to explain the findings.Aims
Patients and Methods
Results: We found there is no significant difference between left (anterior: mean 2.92 mm, SD 1.15; posterior: mean 5.10 mm, SD 1.75; inferior: mean 3.08 mm, SD 1.00) and right (anterior: mean 3.07 mm, SD 1.14; posterior: mean 4.87 mm, SD 1.61; inferior: mean 2.91 mm, SD 0.99) shoulder in healthy players (P >
0.05). The comparison between the healthy shoulders (anterior: mean 3.00 mm, SD 1.15; posterior: mean 4.99 mm, SD 1.68; inferior: mean 3.00 mm, SD 1.00) from healthy players and the normal uninjured shoulder (anterior: mean 4.16 mm, SD 1.70; posterior: mean 6.16 mm, SD 3.04; inferior: mean 3.42 mm, SD 1.18) from injured players identified that players with unstable shoulders have a significantly higher shoulder translation in their normal shoulder than healthy players (P <
0.05). Conclusion: This is the first study looking at laxity and the risk of shoulder dislocations in sportsmen involved in a high contact sport. These results support the hypothesis that rugby players with “lax” shoulders are more likely to sustain a dislocation or subluxation injury to one of these lax shoulders in their sport. We believe pre-season screening and targeted training may play a role in identifying those at risk and may decrease the incidence of dislocations.