Arthroscopic Posterior Bone Block Technique for Posterior Shoulder Instability With Glenoid Bone Loss

Abstract

Background: Posterior instability can be difficult to treat if there is associated bone loss and debate remains about the amount of bone loss that requires intervention. Indications: Arthroscopic posterior bone block technique is useful for recurrent posterior instability with bone loss. It is reserved for patients who have failed soft tissue stabilization with bone loss greater than 10%. Technique Description: After diagnostic arthroscopy, an anterior-superior portal is established. A 30° scope is utilized, although, a 70° scope can be used. The posterior labrum is elevated and dissection is carried along the posterior glenoid neck. If an anterior labral tear is encountered, labral repair is performed. The posterior glenoid is cleared to allow for bone block seating. A fresh, non-frozen distal tibial allograft is prepared to size. Fixation can include screw or button fixation. Other types of fixation can be utilized including tightrope-type fixation, but screws are our preference. We have not had any complications with screw fixation. The graft is predrilled and assembled to the delivery device. A posterior incision is made and dissection is carried under the capsule and labrum to allow for shuttling. The bone block is fixed using two 3.5-mm cannulated screws. After fixation, anchors are placed and remaining capsule and labrum are shifted up to overly the bone block. Postoperative immobilization can be utilized with a standard UltraSling or a gunslinger brace. We typically do not obtain a computed tomography (CT) scan prior to return to activity. Results: There is little literature on arthroscopic posterior bone block, but early results are promising. Distal tibia allograft use in anterior instability has good outcomes and rates of union. Open posterior procedures demonstrate a recurrent dislocation risk of 10%. Current literature supports a similar rate in arthroscopically. Furthermore, there is a learning curve. Complications are similar to open complications, including graft resorption, fixation failure, recurrent dislocation, continued shoulder pain, and glenohumeral arthritis. In our experience, we have not had any wound complications. Discussion/Conclusion: Arthroscopic posterior bone block augmentation presents a reliable technique for posterior instability with associated glenoid bone loss. The use of distal tibia allograft minimizes donor site morbidity. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.