Case Reports

Arthroscopically-Guided, Cannulated, Headless Compression Screw Fixation of the Symptomatic Os Acromiale

Publish date: September 26, 2018

References

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SURGICAL TECHNIQUE

A standard diagnostic shoulder arthroscopy was performed using anterior, posterior and direct lateral portals. The rotator cuff was evaluated, and no evidence of a tear was found. The undersurface of the acromion was exposed, and the os acromiale was identified arthroscopically (Figure 3). This was found to be unstable under direct digital pressure.

We then elected to repair the unstable fibrous os acromiale (Figures 4A-4D). The fibrous nonunion was first debrided to bleeding bone with a 4.0-mm round burr aligned with the os using the direct lateral portal (Smith & Nephew Endoscopy). Through the anterior portal, two Acutrak^TM guide wires (Acumed) were placed under arthroscopic visualization from the anterior margin of the acromion, across the os site, and into the posterior acromion. A 1-cm counter incision was made at the level of the posterior acromion to allow confirmation of the guide wire position and to permit placement of a large, pointed reduction clamp, used to reduce the mesoacromial fragment to the stable portion of the acromion. The calibrated, cannulated drill bit was passed over each guide wire to a depth of 34 mm, according to standard technique, and viewed arthroscopically from the subacromial space. Two 34-mm Acutrak^TM cannulated headless compression screws (Acumed) were then placed across the defect. Direct arthroscopic visualization confirmed reduction and complete intraosseous placement of the screws (Figure 5). Screw position was also assessed with image intensification. Fluoroscopic views showed the repair to be stable when the shoulder was taken through range of motion. The os site was never exposed directly through an incision. The surgery was performed on an outpatient basis.

POSTOPERATIVE COURSE

The patient was maintained in a sling and small abduction pillow (Ultrasling III^TM, DonJoy). She was kept non-weight-bearing but was permitted unrestricted motion through the elbow, wrist, and hand for the first 6 weeks. She was permitted supine passive external rotation of the shoulder to 30° and forward flexion to 45° for the first 2 weeks, and 90° through 6 weeks. At her initial postoperative visit 2 weeks later, she noted minimal pain in the shoulder, much improved from her preoperative pain. She was no longer taking any pain medicine, including NSAIDs. Radiographs showed no change in fixation.

At her second visit (6 weeks), she was completely pain free. Clinical examination showed no tenderness at the acromion, healed incisions, and pain-free passive ROM. Radiographs demonstrated early evidence of consolidation and no sign of fixation failure (Figures 6-8). Her Single Assessment Numeric Evaluation (SANE) score was 85%, and her Simple Shoulder Test (SST) score was 3/12. She was permitted to discontinue the sling, to begin using the arm actively at the side, and progress with unloaded use above shoulder height over the next 6 weeks.

She was seen in follow-up at 4 months, where she was found to have no pain but had not yet returned to sports. At her 6-month follow-up, she showed continued improvement with no limitation of activity. At 1-year follow-up, her SANE score improved from 85% at 6 weeks postoperatively to 100%, and her SST improved from 3/12 at 6 weeks to 12/12. She demonstrated full function of her shoulder with no evidence of hardware loosening. At that time, her os acromiale had completely fused radiographically.

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