Arthroskopische J-Span-Implantation bei knöchernem Glenoiddefekt

The Effect of Scapula Tilt and Best-Fit Circle Placement When Measuring Glenoid Bone Loss in Shoulder Instability Patients

PURPOSE

To analyze the effect of lack of standardization on the reliability of current measurement techniques for glenoid bone loss in clinical practice.

METHODS

Ten consecutive patients with anterior glenoid bone loss due to recurrent anterior shoulder instability and available computed tomographic (CT) scans of the affected shoulder were included in this study. One hundred seventy 3-dimensional en-face view images of the 10 glenoids with up to 20° degrees of tilt in the anterior, posterior, superior, and inferior direction were rendered. Three independent observers first identified the en-face view images and subsequently performed measurements of the defect surface and diameter as well as the glenoid surface and diameter on all 170 images. Measurements were completed based on the conventional best-fit circle technique using the edge of the visible glenoid bone as reference and additionally based on the so-called spoon technique, which places the best-fit circle on the edge of the visible glenoid concavity.

RESULTS

The overall agreement regarding en-face view image selection between the observers was 30% (K-alpha = 0.10, 95% confidence interval 0.02-0.22). Tilt of the en-face view in any direction resulted in significant alterations of all 4 measurement parameters as well as the relative defect area and diameter (P < .05). The conventional and the spoon techniques rendered significantly different results regarding all 4 measurement parameters as well as the relative defect area (P < .05).

CONCLUSION

Impreciseness of scapula positioning for creation of an en-face view of the glenoid as well as varying best-fit circle placement significantly alter glenoid defect size measurement results.

CLINICAL RELEVANCE

Because the glenoid defect size plays an important role in the choice of treatment for anterior shoulder instability, measurement techniques need to be as precise as possible.

The "triple dislocation fracture": anterior shoulder dislocation with concomitant fracture of the glenoid rim, greater tuberosity and coracoid process-a series of six cases

BACKGROUND

A combined fracture of the glenoid rim, greater tuberosity, and coracoid process after anterior shoulder dislocation is a rare event. Only 1 patient has been reported in the literature.

METHODS

All patients with a first-time traumatic anterior shoulder dislocation in a level A trauma center were retrospectively reviewed. Among the 2068 patients treated between 1998 and 2013, we identified 6 patients (0.3%; 1 female, 5 male) with "triple dislocation fracture" (anterior shoulder dislocation with concomitant fracture of the glenoid rim, greater tuberosity, and coracoid process). All patients underwent surgery and had computed tomography scans before surgery and the first postoperative day. Mean follow-up time was 59 months. Clinical and radiographic evaluation, Constant-Murley Score, Simple Shoulder Test, and Subjective Shoulder Value were performed at the final follow-up.

RESULTS

Surgery was determined individually according to the radiologic findings, patient's age, and personal demands. Glenoid reconstruction was performed in all 6 patients, greater tuberosity refixation in 4 patients, and coracoid process refixation in 3. Two patients needed revision surgery due to loss of reduction. At the final follow-up, mean abduction was 133°, mean anterior flexion was 138°; the mean Constant-Murley Score was 72 points; the mean Simple Shoulder Test was 9 points; and the mean Subjective Shoulder Value was 72%. No recurrent instability occurred.

CONCLUSIONS

A "triple dislocation fracture," especially coracoid process fractures, can easily be overlooked in radiographs. Computed tomography scans are strongly recommended in patients with a first-time traumatic shoulder dislocation. Because recurrent joint instability and secondary arthropathy are serious complications after anterior shoulder dislocation, surgery should be considered and provides satisfying to excellent results.