Arthroscopic Distal Tibial Allograft for Posterior Glenoid Reconstruction.

Background: Posterior glenoid bone loss occurs in more than two-thirds of patients with posterior glenohumeral instability, with 14% to 22% having greater than subcritical bone loss (13.5%), a marker for potential need for bony augmentation versus soft tissue-only procedures. Several techniques are described to augment either the version or volume of the glenoid surface including osteotomies, autograft transfers, and allograft tibia transfers. Indications: Arthroscopic-assisted allograft distal tibia bone block augmentation to the posterior glenoid is indicated for revision posterior instability procedures with posterior bone loss and in primary cases of posterior instability with critical bone loss. Technique Description: Arthroscopic posterior glenoid reconstruction with allograft distal tibia and posterior labral repair in the lateral position is presented. This technique uses standard instrument sets and requires no patient repositioning. The preplanned tibial bone block is prepared on a back table either prior to, or concurrently with, arthroscopic procedure. After creation of high posterior portal and standard anterior portal, a sucker-shaver and burr are used to create a perpendicular edge for apposition of the allograft tibia. The bone block is introduced through a longitudinal incision and underdelivered to the prepared surface under the liberated labrum. The articular surface of the graft and glenoid are aligned and cannulated screws are used to compress the bone block against the native glenoid. The posterior labral tissue is then mobilized over the graft and repaired to the native glenoid. Results: Arthroscopic distal tibial allograft augmentation for posterior bone loss restored stability and function in a small cohort of patients. Patients reported improved stability in the immediate postoperative course, with restoration of motion by 2 months. Push-ups, pull-ups, and return to full active duty without restrictions is allowed at 6 months postoperatively. Imaging at 3 months postoperatively has shown excellent graft healing. Discussion: The benefits of allograft tibia augmentation for posterior instability with glenoid bone loss include an anatomic joint surface restoration including articular cartilage, lack of donor site morbidity, and a minimally invasive approach. When performed arthroscopically, this technique permits concurrent posterior labral repair and anatomic reconstruction.