Arthroscopic bone block with distal tibia allograft may aid posterior glenoid bone loss
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Posterior glenohumeral joint instability, while less common than anterior instability, presents its own unique set of challenges – first in diagnosis, but also in nonsurgical and surgical management.
While conservative management may provide adequate relief of symptoms for some patients, surgery is indicated for recurrent instability, with special attention paid toward patients with anatomy predisposing to failure of nonoperative treatment, including posterior Bankart lesions, excessive capsulolabral laxity, excessive glenoid or humeral retroversion and glenoid bone loss.
Source: Nikolas Sarac, MD; Grant L. Jones, MD; Julie Y. Bishop, MD
Options in surgical management include arthroscopic posterior Bankart repair, open posterior/interior capsular shift and glenoid or humeral osteotomies. In 2009, Matthew T. Provencher, MD, described the use of a distal tibia allograft for glenoid reconstruction in patients with significant glenoid bone loss. This was initially performed in an open manner. We will describe our arthroscopic posterior bone block technique using a fresh frozen distal tibia allograft for management of posterior bone loss.
Indications
Subcritical bone loss in regard to posterior glenohumeral joint instability may be defined as a value even less than that in anterior instability, with high failure rates seen after 11% of bone loss. As such, the ideal patient for this technique has posterior bone loss greater than this amount, which is suggestive of the need for bony procedures as opposed to soft tissue repair/reconstruction only. Patients with posterior bone loss benefit from the use of a bone block transfer to restore the normal glenoid arc. The distal tibia is a uniquely suited graft for this procedure due to similar curvature to the glenoid.
Traditionally, posterior bone block transfer has been done through the use of an open approach, but the arthroscopic approach minimizes morbidity and improves visualization. The following procedure was performed in an 18-year-old football player who complained of numerous posterior subluxation episodes despite extensive conservative treatment for 1 year. Preoperative imaging demonstrated a reverse Hill-Sachs lesion and significant posterior bone loss (Figure 1).
Technique
The patient underwent a regional anesthetic block followed by general anesthesia and instability examination. The patient was positioned in the lateral decubitus position and the arm was placed in a traction device with 15 pounds of traction. The procedure began with a standard diagnostic arthroscopy and a posterior portal was created in the usual manner. Anterior-superior and anterior-inferior portals were created under direct visualization.
Attention was turned to the posterior labrum which, consistent with preoperative imaging, demonstrated significant posterior bone loss with associated labral tearing (Figure 2). Any unstable chondral edges were debrided back to a stable border. The posterior labrum and joint capsule were elevated off the medial glenoid, allowing for visualization down the glenoid neck (Figure 3). Elevation 1 cm medial to the articular surface is usually sufficient. A burr was used to freshen the glenoid fragment and get down to a bleeding bony surface for the graft to sit. A traction suture was then placed along the posterior labrum to create additional room for the graft to sit (Figure 4). The defect was measured to help contour the graft. In this case, the defect was noted to be 2 cm from inferior to superior, 1 cm from medial to lateral and 1 cm from anterior to posterior (Figure 5). On the back table, the fresh frozen distal tibial allograft was cut to the above dimensions. A Mitek Latarjet guide (DePuy Synthes) was used to place K-wires through the graft, which are over-drilled and tapped and held with top hats.
An additional 3-cm incision was made medial to the posterior portal for graft placement. Blunt dissection was used through deltoid fascia, and the muscle was finger swept until the joint was reached. This was carefully done so as not to disturb the joint capsulolabral complex and so a capsulorrhaphy could be completed at the end of the procedure. The graft was placed through this accessory posteromedial incision and guided into the joint using the guide. The bone block was positioned level with the articular surface (Figure 6). The wires were then advanced to secure the graft in the posterior glenoid, measured for the appropriate length screws (in this case 32 mm in length superiorly and 34 mm in length inferiorly with 3.5-mm diameter cannulated screws), drilled and replaced with the appropriate length screws (Figure 7). This compressed the graft nicely to the glenoid and care was taken to position the graft such that there was no overhang.
Attention was then turned to the capsulolabral repair. An all-suture anchor (Arthrex) loaded with labral tape was placed first inferiorly at the 5 o’clock position (Figure 8) and passed through the inferior capsule and labrum to advance the labrum and capsule over top of the allograft (Figure 9). This was repeated more superiorly at the 1 o’clock position and provided a nice repair and allowed for the graft to become extra-articular. Final arthroscopic photos were taken and the procedure was complete (Figure 10).
Postoperative care
Postoperatively, the patient was placed in a sling, and for the first 6 weeks was allowed passive external rotation and forward elevation to 90°, but no internal rotation was permitted.
At the 6-week mark, active range of motion was allowed and passive range of motion restrictions were liberalized, including allowing for internal rotation. At 12 weeks, progressive strengthening began and gradual progression of activities was allowed until 24 weeks, with the goal of return to sport at 6 months postoperatively.
- References:
- Antosh IJ, et al. Sports Health. 2016;doi:10.1177/1941738116672446.
- Arner JW, et al. Am J Sports Med. 2021;doi:10.1177/03635465211016804.
- Provencher MT, et al. Arthroscopy. 2009;doi:10.1016/j.arthro.2008.10.017.
- For more information:
- Julie Y. Bishop, MD, Grant L. Jones, MD, and Nikolas Sarac, MD, are of the sports medicine and shoulder divisions at The Ohio State University Wexner Medical Center in Columbus, Ohio. Bishop’s email: julie.bishop@osumc.edu. Jones’s email: grant.jones@osumc.edu. Sarac’s email: nikolas.sarac@osumc.edu.
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