Arthroscopic Posterior Stabilization of the Shoulder Using a Percutaneous Knotless Mattress Suture Technique

Abstract

Posterior shoulder instability is far less common than anterior instability, and its arthroscopic treatment can be technically demanding. We describe a percutaneous arthroscopic technique for posterior shoulder stabilization using mattress sutures and knotless anchors. Spinal needles are used to pass the sutures percutaneously in a mattress fashion. Knotless anchors are used to secure the sutures under the labrum. These anchors can be used without cannulas, giving easier access to the posterior glenoid. This procedure is simple, cost-effective, and safe, avoiding the presence of both knots and suture strands in contact with the humeral head.

Posterior shoulder instability is a relatively rare condition, accounting for only 5% of all the patients with shoulder instability.¹ The cause can be traumatic or atraumatic, and posterior shoulder instability can occur in isolation or as part of a multidirectional pathology. It may also be associated with capsular laxity.²

Surgical management can be challenging, particularly because access to the posterior aspect of the shoulder can be difficult. Several open posterior stabilization techniques have been described, but significant complications such as axillary nerve injury, hematoma, infection, muscular weakness, shoulder stiffness, and glenohumeral arthritis have all been reported.³ Arthroscopic techniques have also been described^2,4-6 and purport to offer better visualization and identification of the pathology, as well as the option of treating multidirectional instability if necessary. Tjoumakaris and Bradley⁷ reviewed the results of open versus arthroscopic posterior stabilization and showed marked reduction in recurrence with the arthroscopic techniques. Such techniques are technically demanding; there is little room for cannulae, suture management can be problematic, and it is difficult to place knots in locations where they will not be in contact with the humeral head.

We describe a new technique for arthroscopic posterior stabilization using mattress sutures and knotless anchors. The technique does not require the use of cannulae.

Surgical Technique

In our institution the procedure is routinely performed with the patient under general anesthesia and an interscalene brachial plexus block (Video 1, Table 1). The patient is placed in the lateral position with the arm suspended through a shoulder traction system with 3.5 to 5 kg, holding the arm at 30° of abduction and 10° of flexion. The flexion can be increased to improve the exposure of the posterior glenoid, and this is usually performed once viewing from the anterior portal. The shoulder is prepared and draped in standard fashion.

Table 1.

Tips, Pearls, Pitfalls, Key Points, Indications, Contraindications, and Risks

Tips

Position the patient more prone than usual and flex the arm more because this will increase the exposure of the posterior joint.

Treat the FiberStick suture carefully. If the stiffened portion is damaged, it will not work and must be discarded.

Plan the needle position carefully so that both limbs can be created without undue force on the needle.

Pearls

Have a grasping retriever and a loop retriever available for the first limb and second limb, respectively.

Use the grasping suture to draw additional suture into the joint before withdrawing it.

Complete each repair before passing the next suture.

Pitfalls

If the spinal needles are forced, they will bend, making further use very difficult.

Preparing the glenoid with the shaver can be difficult; ensure that the suction is off to avoid damage to the labrum.

Key points

Carefully check all access with a spinal needle before starting and adjust the arm position accordingly.

Carefully plan needle position before passing the suture.

Ensure that there is sufficient suture in the joint before withdrawing to avoid fraying in the needle bevel.

Pay attention to suture management to avoid soft-tissue bridges.

Indications

Symptomatic posterior labral detachment.

Contraindications

Evidence of muscle patterning instability or significant bone loss.

If more than a small capsular shift is required, the technique will need to be modified.

Risks

The risks are similar to those of knotless anterior shoulder stabilization. There is relative proximity to the axillary nerve when using the spinal needle.

A standard posterior portal is used, and a 30° arthroscope is inserted. An anterior portal through the rotator interval is created with an outside-in technique by use of a spinal needle. With the use of a switching stick, the arthroscope is inserted through the anterior portal to allow better visualization of the posterior labrum, and the posterior portal is used as an operative portal.

Throughout the procedure, an 18-gauge spinal needle is used to identify optimum access points. It is usually necessary to make 1 additional portal inferior and anterior to the standard first portal, directing the instruments almost perpendicular to the glenoid face. This creates the “working” portal for labral elevation, suture retrieval, and anchor insertion. The posterior labrum is then released and elevated with an arthroscopic periosteal elevator, and the glenoid rim is decorticated with a burr.

An 18-gauge spinal needle is used to identify the optimum suture position. The needle is advanced through the posterior capsule and then passed through the labrum to emerge underneath, parallel to the face of the glenoid. A FiberStick with No. 2 FiberWire (Arthrex, Naples, FL) is passed through the needle. The suture strand is then grasped with a suture retriever and pulled out through the accessory posterolateral portal (Fig 1). To facilitate the withdrawal of the suture, it is important to introduce as much suture as possible into the joint; this reduces the risk of the suture fraying as it passes over the bevel of the needle. The needle is then withdrawn through the labrum but kept inside the joint. The needle is repositioned to create a mattress suture and passed again through the labrum to emerge on the underside. If the needle is then withdrawn slightly, a small suture loop is created, making retrieval easier. The second suture strand is retrieved through the accessory portal with the suture retriever, allowing the suture to slide (Fig 2). The sutures are then managed to ensure that both are exiting through the same accessory portal with no soft-tissue bridge. This step usually involves taking both limbs out through the primary portal together and then out through the accessory portal together.

Fig 1.

The first suture limb is inserted through a spinal needle from a low posterior position and is then grasped with a suture retriever through the accessory working portal (patient in lateral decubitus position, viewing from anterior portal in right shoulder).

Fig 2.

Sliding retrieval of the second suture limb through the accessory portal (patient in lateral decubitus position, viewing from anterior portal in right shoulder).

If a small capsular shift is required, this can be achieved by positioning the sutures inferiorly on the glenoid face relative to the selected position for the anchor. Large shifts are usually not possible. If a capsular plication is required, the needle must be passed through the posterior capsule to form a “pleat” before it passes under the labrum.

By use of the accessory portal, a pilot hole is made in the posterior glenoid rim. A 2.9-mm BioComposite PushLock anchor (Arthrex) is loaded with the 2 strands of the FiberStick. The anchor is “railroaded” down the sutures and driven into the pilot hole while gentle tension of the 2 suture limbs is maintained (Fig 3). The 2 limbs are then cut flush by use of a suture cutter (Arthrex). Further mattress sutures and relative anchors are then placed as required.

Fig 3.

Percutaneous insertion of knotless anchor from accessory working portal and final appearance after sutures have been cut (patient in lateral decubitus position, viewing from anterior portal in right shoulder).

The wounds are closed and the arm is placed in a sling for 3 weeks, during which elbow, wrist, and hand mobilization and external rotation are permitted, with no internal rotation or flexion beyond the horizontal for a total of 6 weeks.

Discussion

Posterior shoulder instability is a rare condition, and its management has always been a challenge. Open surgical procedures have been described, but all of them are technically demanding and have a high risk of complications. The described arthroscopic techniques have better recurrence rates but can also be technically demanding and have a long learning curve. The posterior labrum is difficult to reach, and the lack of space between the labrum and the posterior capsule, combined with the presence of the humeral head, does not allow easy cannula positioning.

The technique described in this report has a number of advantages over both the open and current arthroscopic techniques. Nho et al.,³ in a cadaveric study, did not show any biomechanical superiority of a mattress configuration over a single-suture configuration for posteroinferior capsular plication. Kim et al.⁸ showed that even if knots are placed away from the humeral head, it is possible for them to migrate into a position in which they would make repeated contact.

The use of mattress sutures and knotless anchors placed under the labrum reduces the possibility of suture contact with the humeral head. The use of knotless anchors also removes the requirement to manipulate knots through the tissues. Although it is technically possible to tie knots without a cannula, it is difficult and not recommended. Provided that the sutures have been managed appropriately, it is a simple step to slide the BioComposite PushLock anchor down the sutures percutaneously.

The use of spinal needles without cannulas means that portal position is not restricted and there is easy access to the posterior labrum without the risk of the cannula impinging on and damaging the articular surface (as is evident in some of the published techniques).

Finally, there are also time and cost implications. The described technique uses only spinal needles and FiberStick with no need for cannulae or suture passers, not only saving on equipment but also reducing the number of steps involved and therefore the operating time.

As with all procedures, there are some limitations. The spinal needles do not allow for the creation of a capsular shift, and the technique would have to be modified in these cases. The needles are also relatively soft and can bend if care is not taken. If this happens, it can be difficult to reposition the needle satisfactorily, and we would recommend using a new needle for each suture. Because this procedure does not use cannulae, careful suture management is essential if soft-tissue bridges are to be avoided. The same is true when the anchor is being introduced. Some tension has to be applied to the sutures during introduction to enable the track to be followed.

We recommend the described technique as a simple and safe solution to what can be a difficult surgical problem.

Supplementary Data

Video 1

Percutaneous mattress knotless posterior labral repair of right shoulder with patient in lateral decubitus position.