Abstract
We present a novel all-arthroscopic technique of posterior shoulder stabilization that uses suture anchors for both bone block fixation and capsulolabral repair. The bone graft, introduced inside the glenohumeral joint through a cannula, is fixed with 2 suture anchors. The associated posteroinferior capsulolabral repair places the bone block in an extra-articular position. In this article we present the detailed arthroscopic technique performed in a consecutive series of 15 patients and report the early results. We also report the positioning, healing, and remodeling of the bone block using postoperative 3-dimensional computed tomography. The benefits of this new technique are as follows: (1) it is all arthroscopic, preserving the posterior deltoid and posterior rotator cuff muscles; (2) it is accurate, resulting in appropriate bone block positioning; (3) it is efficient, allowing for consistent bone graft healing; (4) it is anatomic, both restoring the glenoid bone stock and repairing the injured posterior labrum; and (5) it is safe, limiting hardware-related complications and eliminating the risk of injury to vital structures associated with drilling or screw insertion from posterior to anterior. We believe that this technique is advantageous because it does not use screws for fixation and may be safer for the patient.
Arthroscopic soft-tissue repairs allow for stabilization of the shoulder in many cases of post-traumatic recurrent involuntary posterior instability. However, when instability is associated with posterior glenoid deficiency, iliac crest bone block autograft can be mandatory to restore the glenoid bone stock and enlarge the glenoid cavity.1-5 Classically, this procedure is performed in an open manner and the bone graft is fixed with screws. This procedure has proven successful, with a low rate of recurrent instability, infrequent complications, and high patient satisfaction.4 Recently, some authors have proposed performing this procedure arthroscopically while continuing to use 2 screws for bone graft fixation.2,3,6 The downside of this fixation method is that screws can be a source of complications, and great care must be taken to ensure that the orientation and length of the screws do not result in anterior or posterior soft-tissue impingement, penetration of the glenoid articular surface, or posterior impingement between the humeral head and screw head.1
Several authors have shown that it is possible to obtain bone healing of anterior glenoid fractures using arthroscopic suture anchor fixation.7-10 On the basis of this experience, the senior author developed a similar approach for arthroscopic posterior stabilization, using suture anchors for both posterior bone block fixation and posterior capsulolabral repair. The purpose of this article is (1) to describe our new all-arthroscopic technique and (2) to report our results regarding bone block positioning, healing, and remodeling using postoperative 3-dimensional computed tomography (CT) scans.
Surgical Technique
Surgery is performed with the patient in the beach-chair position but can also be performed with the patient in the lateral decubitus position. A bicortical iliac crest bone graft (20 to 25 mm long × 9 mm wide × 9 mm thick) is harvested. Two 2.4-mm holes are drilled through the graft transversely from the cortical side to the cancellous side for later suture passage. Video 1 and Table 1 outlines each step of the operation.
Table 1.
Key Steps and Tips for Each Step of Procedure
| Technique | Key Steps | Pearls |
|---|---|---|
| Glenoid preparation | Perform labral detachment and glenoid preparation. | A traction stitch helps with retraction of soft tissue; burr down bone sufficiently for good apposition with graft. |
| Anchor insertion | Use a posterolateral portal, and place anchors in the posteroinferior quadrant of the glenoid. | Position anchors at the 6- to 10-o'clock position; an angle of 45° avoids articular damage. |
| Bone graft delivery | Pass each suture through predrilled holes in the graft (superior and inferior holes). | Be sure to use a sufficiently large cannula to allow for graft passage. |
| Fixation | We prefer a Nice knot for fixation, created by tying 1 suture to another suture, and passage with a knot pusher. | Use a grasper or switching stick to secure the orientation of the bone graft during this step. |
| Posterior Bankart repair | Place anchors and pass suture through the capsulolabral structures. | The traction stitch helps any instrument pierce these structures in a more facile fashion. |
Step 1: Glenoid Preparation
Standard posterior and anterior portals (lateral to coracoid process) are created, and a diagnostic arthroscopy is performed. With the arthroscope in the anterior portal, a spinal needle is used to localize the posterolateral (working) portal, typically located 2 fingerbreadths (3 cm) lateral to the posterior portal and 2 fingerbreadths inferior to the posterolateral corner of the acromion. Appropriate portal positioning should allow an appropriate angle for anchor insertion (45° medial) and access to the posteroinferior capsulolabral tissues. A threaded 10-mm cannula (Smith & Nephew, Andover, MA) is inserted into the joint. The posteroinferior labrum is completely detached with a radiofrequency device (VAPR; DePuy Mitek, Raynham, MA). Two “traction sutures” are passed percutaneously with a BirdBeak device (Arthrex, Naples, FL) through the detached labrum: 1 at the 6-o'clock position and 1 at the 11-o'clock position. Traction on the 2 sutures creates space between the labrum and posterior glenoid, allowing debridement with a shaver and burr to create a bleeding cancellous surface.
Step 2: Anchor Insertion
Two double-loaded, metallic suture anchors (Fastin; DePuy Mitek) are inserted through the posterolateral cannula: 1 at the 7-o'clock position and 1 at the 9-o'clock position (for a right shoulder). The distal anchor is inserted first, and all 4 suture limbs are held under tension while the second anchor is inserted. The anchors are placed 1 mm under the glenoid rim with a 45° descendant angle. The goal is a bone graft that will lie flush with, or slightly overhanging, the glenoid rim and is centered on the posteroinferior quadrant of the glenoid (between the 6- and 10-o'clock positions for a right shoulder) (Fig 1).
Fig 1.
Drawings showing desired placement of bicortical bone graft on posterior aspect of glenoid and its extra-articular position after reattachment of posterior labrum.
Step 3: Intra-Articular Delivery of Bone Graft
Outside of the joint, the 2 sutures (1 blue and 1 purple) from the inferior anchor are passed through the inferior hole of the graft, and the 2 sutures (1 blue and 1 purple) from the superior anchor are passed through the superior hole. The bone graft is then inserted longitudinally into the cannula and is pushed into the joint by use of the cannula trocar or knot pusher. The graft is positioned against the glenoid rim with traction on the sutures, and a probe is introduced through the posterior portal (Fig 2).
Fig 2.
The posterior bone block is delivered inside the glenohumeral joint through a cannula and fixed by 2 suture anchors; the arthroscopic view shows that the graft is lying flush to the articular surface.
Step 4: Bone Graft Fixation and Knot Tying
Outside of the joint, 1 of the 2 purple suture strands from the superior anchor is tied to 1 of the 2 purple suture strands from the inferior anchor with a “figure-of-8” locking knot (king sling knot); this allows one to create a suture loop. This purple suture loop is then tied with the 2 remaining purple suture strands, building a doubled-suture Nice knot.11 The grasper, introduced through the posterior portal, is used to control the rotation of the bone block while the knot is tightened. The same procedure is repeated with the blue sutures to obtain a second point of fixation.
Step 5: Posteroinferior Capsulolabral (Bankart) Repair
The arthroscopic posterior Bankart repair is then performed with 2 or 3 suture anchors (JuggerKnot; Biomet, Warsaw, IN). The anchors are placed on the glenoid rim at the 7-, 8-, and 9-o'clock position for a right shoulder. This allows re-tensioning of the capsulolabral tissue and positions the bone graft extra-articularly (Fig 3). Postoperatively, a neutral rotation brace is worn for 4 weeks, and formal rehabilitation with a physiotherapist is then started.
Fig 3.
Arthroscopic views of a right shoulder (seen from anterior portal) showing posterior Bankart repair with small suture anchors allowing reconstruction of a solid posterior bumper and complete coverage of the bone block, which becomes extra-articular.
Series
We performed our novel arthroscopic procedure in 15 patients (12 male and 3 female patients) who had recurrent posterior shoulder instability. The mean age at surgery was 27 years (range, 14 to 58 years). In all cases imaging showed a fracture and/or erosion of the posterior glenoid rim. Postoperatively, 1 patient complained of persistent iliac crest pain. There were no other complications noted, and no patient required an additional procedure. Five patients with more than 12 months' follow-up (mean follow-up, 17.6 months) were evaluated regarding functional results. None of these patients had recurrence of instability or apprehension postoperatively. At last follow-up, the Rowe score was 87 points and the Walch-Duplay score was 89 points.
CT scans were performed in all patients 2 weeks after surgery to assess the bone block positioning and 6 months postoperatively to judge the graft healing and remodeling. In the vertical plane, the bone block was judged to be subequatorial (correct graft position) in 14 cases (Fig 4) and equatorial (25% of bone block over equator line) in 1 case. In the horizontal plane, the bone block was judged to be flush with the glenoid or to have a slight lateral overhang (correct graft position) in 14 cases and to be excessively lateral (10 mm lateral to glenoid rim) in 1 case. In no case was the graft judged to be too medial (5 mm medial to glenoid rim); there was no violation of the articular surface by the anchors. The bone graft healed in all cases with relative resorption of the superior portion of the graft and restoration of the pear shape of the glenoid observed on the most recent CT scan (Fig 5).
Fig 4.
Early CT images (at 2 weeks) showing correct bone graft positioning: in the vertical plane, the graft is subequatorial, whereas in the horizontal plane, it is flush or slightly overhanging laterally.
Fig 5.
CT images showing bone graft healing and remodeling with time in the same patient. The 3-dimensional CT scan image of the initial posterior bone graft at 1 month of follow-up (left), 3-dimensional CT scan image at 20 months' follow-up (middle), and axial cut image (right) show healing and late remodeling of the bone graft with recreation of a pear-shaped glenoid.
Discussion
Our technique is the first to use suture anchors as a means of graft fixation for the posterior bone block procedure. With this arthroscopic procedure, we address both components of posterior instability: posterior glenoid bone deficiency and posteroinferior capsulolabral deficiency. Though limited by short-term follow-up, this novel all-arthroscopic posterior bone block procedure using anchor fixation is safe and reproducible. It allows accurate positioning and healing of the posterior bone block, and it reduces the risk of injury to the anterior neurovascular structures, the posterior musculotendinous structures, and the cartilage of the humeral head and glenoid. Achieving fixation without the use of screws has several benefits. Not only does it eliminate the risk to the anterior structures associated with drilling or screw insertion,3,12 but it limits hardware complications, such as screw loosening or back-out, that could require hardware removal. The humeral head cartilage is also protected because there are no screw heads on which to impinge and no uneven surfaces with which to articulate because the bone block is placed extra-articularly.
One could argue that suture anchor fixation does not provide enough compression to obtain healing of the iliac crest bone graft. Our study shows that healing of the bone graft is regularly obtained because no bone block nonunions were observed. Our experience is similar to bony Bankart fixation using suture anchors for anterior shoulder instability.7,9,10,13 The graft remodeling observed with delayed CT imaging shows restoration of the pear shape of the glenoid and is similar to what we have previously observed with open techniques1,4 and arthroscopic techniques.3 Our hypothesis is that this remodeling is related to the relatively higher loads placed on the subequatorial portion of the graft by the humeral head (Wolff's law).
Footnotes
The authors report the following potential conflict of interest or source of funding: P.B. receives support from Smith & Nephew, DePuy Mitek, and Tornier.
Supplementary Data
Each step of operation is outlined.
References
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Associated Data
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Supplementary Materials
Each step of operation is outlined.