In a prospective study we assessed the accuracy of 3D-CT in defining the acetabular deficiency in developmental dysplasia of the hip (DDH), comparing pre-operative 3D-CT with plain radiographs, intraoperative stability testing and intraoperative acetabular morphology.

Twenty children (25 hips) with DDH who had open reduction and/or pelvic osteotomy from 1999 to 2001 were studied. On 3C-CT the morphology of the deficiency was described as normal, anterolateral deficient (overlapping shadows), lateral (increased acetabular index only) and global (double acetabulum). At open reduction, the position in which the hip was most stable with axial loading was assessed (Zadeh and Caterall, 2001). The surgeon’s assessment of the acetabular morphology intraoperatively was the standard against which the other modalities were tested. One hip was normal, five had a global and 19 an anterolateral deficiency.

3D-CT correlated well with the acetabular morphology (84%). Plain radiography correlated poorly, especially with the global type (60%). Mid-superior appearance on 3D-CT and lateral appearance on plain radiograph equated with an anterolateral deficiency morphologically. In the global type the hip was unstable in all positions, while the anterolateral type, while in the anterolateral type the hip was always stable in flexion and abduction and in only 31% of hips stable also in abduction and internal rotation.

The mean age at surgery was 3 years (1 to 7). The one hip with a normal acetabulum required open reduction only, the five global types an acetabuloplasty (Tonnis), and the 19 hips with anterolateral deficiency a redirectional (Salter) osteotomy.

3D-CT is helpful in appropriate osteotomy for a specific type of acetabular deficiency in DDH.

We retrospectively reviewed the results of 21 patients (22 shoulders) who had surgery for os acromiale.

The mean age of the 6 men and 15 women was 52 years. The dominant side was involved in 10 patients. The duration of symptoms ranged from one month to 13 years. Ten patients had a history of recent trauma. All presented with tenderness over the site of the os and signs of impingement. In three patients, signs of weakness suggested a rotator cuff tear, and three patients had tenderness over the acromioclavicular joint. Rotator cuff tears, four partial and eight full thickness, were present in 12 cases.

Surgery included excision of the os in nine cases and fixation in 13. Ancillary procedures included acro-mioclavicular joint excision (eight), rotator cuff repair (eight), cuff debridement (three) and biceps tenodesis (one).

At follow-up, which ranged from 5 months to 6 years, Constant and American Shoulder and Elbow Surgeons’ scores were assessed. The presence of a deltoid defect was noted and deltoid strength was measured. The mean Constant score at follow-up was 77. Deltoid strength was notably reduced in abduction but not in forward flexion. There were no cases of sepsis. Five cases required further surgery. In three, this involved removal of metal, but persistent pain necessitated one subsequent rotator cuff repair and one arthroscopic debridement of the subacromial space.

The outcome of both fixation and excision was satisfactory, but the reoperation rate was higher in patients who underwent fixation. We advise arthroscopic excision of meso-acromion in the absence of a full thickness rotator cuff tear.

To determine the radiological signs and the ease of diagnosis on different views, we reviewed true antero-posterior, axillary and supraspinatus outlet views of 26 shoulders with os acromiale.

The anteroposterior view shows sclerosis and ‘double oval’. The supraspinatus outlet view shows a ‘double’ acromion. The axillary view demonstrates the site of the pseudarthrosis and size of the os.

The os acromiale was visible on the anteroposterior view in 25 cases, on the supraspinatus outlet in 20 cases and on the axillary view in 17 cases. It was visible in at least two views in 25 of the cases. The os was more often evident on the anteroposterior view, but more clearly seen on the axillary. A radiologist reported on 13 of the X-rays and missed the diagnoses in nine cases. In two cases, the surgeon missed the radiological diagnosis. There were 20 meso-acromions and two pre-acromions.