Posterior shoulder instability in overhead athletes presents a unique and difficult challenge. Often, this group has an inherent capsular laxity and/or humeral retroversion to accommodate the range of motion necessary to throw. This adaptation makes the diagnosis of posterior capsulolabral pathology challenging, as the examiner must differentiate between adaptive capsular laxity and pathologic instability. Further complicating matters, the intraoperative surgeon must find the delicate balance of achieving stability while still allowing the necessary range of motion.
Key points
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Overhead-throwing athletes are at a risk for injury to the posterior glenolabral complex from repetitive microtrauma.
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The examiner must differentiate between adaptive capsular laxity and pathologic instability.
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Repair constructs using suture anchors improves the athlete’s prospect in returning to throwing activities.
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Knotless fixation should be used above the glenoid equator to minimize iatrogenic humeral head abrasion from suture knots.
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The overhead athlete’s kinetic chain and throwing mechanics must be analyzed and corrected to decrease the risk of reinjury.
Introduction
Overhead, or throwing, athletes are a distinct group of patients with unique injuries to the shoulder. Much attention has been placed on superior labral anterior to posterior tears and undersurface rotator cuff tears in the overhead athlete. Posterior shoulder instability in throwers, although less common than the previously mentioned conditions, can lead to similar symptoms as well as decreased performance.
Three general etiologies of posterior instability of the shoulder exist: acute traumatic, repetitive microtrauma, and atraumatic or ligamentous laxity. In athletes, the most common cause of posterior instability is from repetitive microtrauma to the posterior capsulolabral complex. This is especially well documented in football lineman, weight lifters, and rowers. Recent studies have shown these athletes return to preinjury level of competition following arthroscopic capsulolabral reconstruction.
Posterior shoulder instability in overhead athletes presents a unique and difficult challenge. Often, this group has an inherent capsular laxity and/or humeral retroversion to accommodate the range of motion (ROM) necessary to throw. This adaptation makes the diagnosis of posterior capsulolabral pathology challenging, as the examiner must differentiate between adaptive capsular laxity and pathologic instability. Further complicating matters, the intraoperative surgeon must find the delicate balance of achieving stability while still allowing the necessary ROM. To our knowledge, there have been only 2 studies documenting the results of arthroscopic posterior capsulolabral reconstruction in overhead athletes.
Introduction
Overhead, or throwing, athletes are a distinct group of patients with unique injuries to the shoulder. Much attention has been placed on superior labral anterior to posterior tears and undersurface rotator cuff tears in the overhead athlete. Posterior shoulder instability in throwers, although less common than the previously mentioned conditions, can lead to similar symptoms as well as decreased performance.
Three general etiologies of posterior instability of the shoulder exist: acute traumatic, repetitive microtrauma, and atraumatic or ligamentous laxity. In athletes, the most common cause of posterior instability is from repetitive microtrauma to the posterior capsulolabral complex. This is especially well documented in football lineman, weight lifters, and rowers. Recent studies have shown these athletes return to preinjury level of competition following arthroscopic capsulolabral reconstruction.
Posterior shoulder instability in overhead athletes presents a unique and difficult challenge. Often, this group has an inherent capsular laxity and/or humeral retroversion to accommodate the range of motion (ROM) necessary to throw. This adaptation makes the diagnosis of posterior capsulolabral pathology challenging, as the examiner must differentiate between adaptive capsular laxity and pathologic instability. Further complicating matters, the intraoperative surgeon must find the delicate balance of achieving stability while still allowing the necessary ROM. To our knowledge, there have been only 2 studies documenting the results of arthroscopic posterior capsulolabral reconstruction in overhead athletes.
Indications and contraindications
Initial nonoperative management consists of cessation of throwing activities for a minimum of 4 to 6 weeks. This is followed by intensive muscle strengthening about the shoulder, along with analyzing and correcting throwing mechanics and deficits along the kinetic chain.
For patients who fail nonoperative treatment, wish to continue overhead athletics, and are willing to adhere to the lengthy postoperative rehabilitation protocol, arthroscopic posterior capsulolabral reconstruction is indicated.
Surgical technique
Preoperative Planning
At our institution, we generally use magnetic resonance arthrography (MRA) to aid in the diagnosis as well as for preoperative planning. MRA allows the surgeon to identify anatomic pathologies, namely posterior labral tears, patulous posterior capsule, and, on rare occasions, posterior humeral avulsion of the glenohumeral ligament. We find MRA especially useful in the diagnosis of incomplete and concealed posterior labral tears (Kim lesion) that would otherwise appear benign on diagnostic arthroscopy.
Patient Positioning
Following administration of general anesthesia, the patient is positioned in the lateral decubitus position. An inflatable beanbag is used to hold the patient in place. All bony prominences are well padded and an axillary gel roll is placed under the nonoperative arm.
A lateral arm positioner is used on the operative arm and 10 pounds of traction is added. The arm is then positioned in 45° of abduction and 20° of forward flexion.
Diagnostic arthroscopy
We begin with a standard diagnostic arthroscopy from the posterior portal. This portal, which later becomes a working portal, is slightly lateral than the traditional portal, allowing a less acute trajectory to the posterior glenoid.
An anterior portal is then made within the rotator interval and a 6-mm cannula (Arthrex, Naples, FL) is placed. The arthroscope is then placed through the anterior cannula to evaluate the posterior capsulolabral complex. We typically use a 70°arthroscope to aid in visualization ( Fig. 1 ) and place an 8.25-mm cannula (Arthrex).
Glenoid and labrum preparation
Once the labral tear has been identified, the labrum is sharply lifted off the glenoid using an elevator from the posterior portal ( Figs. 2 and 3 ). We then perform a meticulous glenoid preparation, using a combination of a shaver, bur, and rasp to produce a fresh, bleeding surface for the labrum to heal to ( Fig. 4 ).
Zone-specific repair
Once the labrum and glenoid are adequately prepared, we use a zone-specific capsulolabral reconstruction centered around the glenoid equator ( Fig. 5 ). Below the equator (9 o’clock to 6 o’clock), we use 2.4-mm SutureTak anchors (Arthrex), securing the labrum to the glenoid via suture knots.
Superior to the equator, we use knotless labral fixation with 2.9-mm Short PushLock anchors and 1.5-mm LabralTape (Arthrex). The advantage of knotless fixation above the equator include minimizing the potential risk of postoperative iatrogenic humeral head chondral injury from suture knot abrasion. The broader surface area of the LabralTape versus traditional suture may also have a biomechanical advantage, with a larger maximum load to failure.
Subequatorial repair
A percutaneous posterolateral portal at the 7 o’clock position is confirmed with a spinal needle. This portal is typically 2 cm lateral to the posterolateral acromion. A stab incision is made and followed by the insertion of the 2.4-mm SutureTak anchor ( Figs. 6 and 7 ). If placement of a second anchor is anticipated, the drill guide should not be removed to prevent multiple iatrogenic holes into the capsule.
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