RESUMO
BACKGROUND: We aimed to establish values and parameters using multislice reconstruction in axial computerized tomography (CT) in order to quantify the erosion of the glenoid cavity in cases of shoulder instability. METHODS: We studied two groups using CT. Group I had normal subjects and Group II had patients with shoulder instability. We measured values of the vertical segment, the superior horizontal, medial and inferior segments, and also calculated the ratio of the horizontal superior and inferior segments of the glenoid cavity in both normal subjects and those with shoulder instability. These variables were recorded during arthroscopy for cases with shoulder instability. RESULTS: The mean values were 40.87 mm, 17.86 mm, 26.50 mm, 22.86 mm and 0.79 for vertical segment, the superior horizontal, medial and inferior segments, and the ratio between horizontal superior and inferior segments of the glenoid cavity respectively, in normal subjects. For subjects with unstable shoulders the mean values were 37.33 mm, 20.83 mm, 23.07 mm and 0.91 respectively. Arthroscopic measurements yielded an inferior segment value of 24.48 mm with a loss of 2.39 mm (17.57%). The ratio between the superior and inferior segments of the glenoid cavity was 0.79. This value can be used as a normative value for evaluating degree of erosion of the anterior border of the glenoid cavity. However, values found using CT should not be used on a comparative basis with values found during arthroscopy. CONCLUSIONS: Computerized tomographic measurements of the glenoid cavity yielded reliable values consistent with those in the literature.
RESUMO
For hemiarthroplasty reconstruction of a proximal humeral fracture, accurate restoration of humeral head position is challenging, and incorrect prosthetic placement is associated with a poor outcome of surgical treatment. The purpose of this study was to validate the pectoralis major tendon as a reproducible landmark for accurate restoration of humeral length with hemiarthroplasty reconstruction. We dissected 20 cadavers (40 shoulders), and the distance between the upper border of the pectoralis major tendon insertion on the humerus and the top of the humeral head was measured (PMT). The PMT averaged 5.6 +/- 0.5 cm (with a confidence level of 95%). In only 4 of 40 shoulders did this distance exceed 6.0 cm, and there was no correlation between the size of the patient and this measurement. The PMT is a useful landmark that will aid in accurate restoration of humeral length when reconstructing complex proximal humeral fractures where landmarks are otherwise lost because of fracture comminution.
