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Anterior Instability: Intraoperative and Postoperative Issues With Arthroscopic Repair
Introduction
Anterior glenohumeral instability is a common problem encountered by the orthopedic surgeon, particularly in young active patients. Young male contact-sport athletes with anterior shoulder instability who do not undergo surgical stabilization have particularly high rates of going on to develop recurrent anterior instability, with recurrence rates approaching 90%. , The critical lesion in over 90% of anterior glenohumeral instability cases is the Bankart lesion, in which the anteroinferior glenoid labrum is detached from the glenoid. , The surgeon must also be vigilant for other copathology, which must be appropriately addressed for successful treatment. Arthroscopic anterior labral repair of the Bankart lesion results in high rates of return to activities and sports with low rate of recurrent instability. , Arthroscopic anterior labral repair has become the predominant shoulder stabilization procedure in recent years, fueled in part by advances in technique and surgical instrumentation. Outcomes of arthroscopic repair are thought to be equivalent to those of open repair in patients without significant bone loss.
Preoperative considerations are critical in determining whether the patient is an appropriate candidate for arthroscopic anterior labral repair and are addressed in a separate chapter in detail. Briefly, history and examination must be detailed and include: determine patient mechanism of injury (traumatic versus atraumatic), patient age and activity level (including overhead, contact, and collision sports), pattern of instability (anterior, posterior, multidirectional), first-time versus recurrent instability, and subluxation versus dislocation. Examination of the shoulder is performed in detail and compared with the contralateral normal shoulder. A full examination is performed with focus on loss of motion, strength and neurologic status, and testing for instability in all directions. Proper imaging in the preoperative setting is also critical, including magnetic resonance imaging (MRI) to assess soft tissue copathology such as a humeral avulsion of anterior glenohumeral ligament (HAGL) and computed tomography (CT) with three-dimensional reconstructions for optimal assessment of bone loss on the glenoid and humeral head that predispose to recurrent instability after arthroscopic anterior labral repair. , Finally, detailed examination under anesthesia and diagnostic arthroscopy are essential for confirming the surgical plan, assessing direction and extent of instability, and addressing any copathology (e.g., engaging Hill–Sachs or HAGL).
The purpose of this chapter is to describe intraoperative and postoperative complications of arthroscopic anterior labral repair and discuss tips to prevent complications, as well as management strategies if they do occur.
Intraoperative Complications
Neurological Injury
Neurological injury is an uncommon complication of anterior stabilization, but with potentially devastating outcomes to the patient. It has been reported to occur among candidates for the American Board of Orthopaedic Surgery (ABOS) certification examination in 0.3% of arthroscopic anterior labral repairs, significantly lower than a 2.2% rate for open anterior stabilization procedures. The axillary nerve is at greatest risk of neurologic injury during arthroscopic anterior labral repair. It passes adjacent the inferior glenohumeral capsule, closest to the glenoid rim at the 6-o’clock position at an average distance of 1.2 cm. This places the axillary nerve at greatest risk during inferior labral mobilization, anchor placement, and suture passage near the 6-o’clock position. Accessory portal placement with 7-o’clock and 5-o’clock portals requires careful attention to surrounding neurovascular structures, with the axillary nerve reported to be 15 mm inferomedial to the 5-o’clock portal and 39 mm from the 7-o’clock portal. The suprascapular nerve was also 29 mm from the 7-o’clock portal.
Transient traction–related neuropraxia has been reported for 10% to 30% of lateral decubitus shoulder arthroscopies, thought to be because of traction on the brachial plexus and upper extremity nerves. Fortunately persistent neuropraxia is only encountered in very rare situations involving the musculocutaneous and ulnar nerves. Avoiding excessive traction weight and time during surgery is the primary method to avoid this complication, and our experience has been that efficient, reproducible surgical technique allows arthroscopic anterior labral repair to be performed without traction-related neuropraxia in the vast majority of cases. In addition, positioning of the patient’s contralateral arm, neck, and lower extremities must involve careful padding of prominences and placement in comfortable positions to avoid iatrogenic neuropraxia to other parts of the body.
Management of nerve injury involves careful postoperative assessment of neurological function, which is often not possible immediately after surgery because of interscalene block. Particular attention is paid to the axillary nerve. Most cases are neuropraxias that resolve spontaneously. If symptoms do not improve, electromyography (EMG) is obtained at 4 to 6 weeks postoperatively. Symptoms are monitored for 3 to 6 months to evaluate for signs of improvement. In some cases, repeat EMG may be performed to evaluate for signs of nerve recovery. If symptoms fail to resolve, open surgical exploration of the involved nerve can be considered, with possible nerve grafting or tendon transfers depending on the exact nerve injury; however, this is a salvage option with a poor prognosis in our experience.
Anchor-Related Complications
Perhaps the most common complication after arthroscopic anterior labral repair is iatrogenic anchor-related damage to the glenohumeral joint, although the exact incidence is difficult to quantify owing to underreporting. The ABOS data suggest that intraoperative implant failure occurs in 0.3% of cases, although other anchor-related complications are not reported. Early techniques of arthroscopic anterior labral repair with staples or bioabsorbable tacks included up to a 30% rate of implant-related complications. Anchor-related complications include pain, loss of range of motion, implant loosening or failure, glenoid osteolysis, chondrolysis, and synovitis. Poly-L-lactic acid implants were associated with macroscopic intraarticular debris in over half of patients, giant cell reaction in 84% of patients, and high-grade chondral damage in 70% of patients. Advances in surgical technique, as well as meticulous anchor insertion and avoiding prominent anchors, has helped to reduce these complications significantly with modern techniques and implants.
Anchor drilling at or near the 6-o’clock position can result in far cortex perforation, which can result in weaker anchor fixation and compromised labral repair, failure of anchor placement or anchor pull-out attributed to poor fixation, the need for additional drilling to achieve anchor fixation, or potential damage to structures beyond the opposite cortex. Several cadaveric studies have reported that accessory portals including the 5-o’clock transsubscapularis portal enable anchor placement at the inferior glenoid with a lower risk of opposite cortex perforation.
Proper visualization and portal placement are paramount to preventing iatrogenic damage during labral and glenoid preparation, anchor drilling, and anchor placement. We prefer the lateral decubitus position for improved glenohumeral joint distraction by way of balanced suspension that affords better visualization and instrumentation to the inferior glenoid compared with the beach chair position. , In addition, we use the accessory 7-o’clock posterolateral and 5-o’clock transsubscapularis portals to facilitate anchor placement and suture passage at the inferior glenoid, allowing a stable repair without perforation of the opposite cortex or iatrogenic damage. ,
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