Reconstruction of the Medial Ulnar Collateral Ligament of the Elbow: The Docking Technique

Abstract

Background:

The medial ulnar collateral ligament (MUCL) is the primary restraint to valgus force on the elbow. Since the first description of MUCL reconstruction by Jobe et al in 1986, many technical advancements have been implemented to improve outcomes and reduce complications. The docking technique has emerged as one of the most commonly used techniques.

Indications:

Following repetitive stress on the elbow during the overhead throwing motion, the MUCL may become attenuated, insufficient, or rupture completely. Although nonoperative treatment with rest and therapy is often the initial treatment of choice, individuals who fail conservative measures may require MUCL reconstruction.

Technique Description:

The major steps of the procedure are (1) harvesting of palmaris longus autograft, (2) incision and exposure, (3) preparation of ulnar tunnel, (4) preparation of docking site on medial epicondyle, (5) graft passage, (6) graft tensioning and length determination, (7) final fixation, and (8) closure.

Results:

This procedure allows for reconstruction of the MUCL, restoration of valgus stability to the elbow, and return to play rates of 80% to 95%. The docking technique has advantages over previously described MUCL reconstruction techniques in that it minimizes injury to the flexor pronator mass, avoids the ulnar nerve, allows for robust graft tensioning, and reduces the amount of bone removed from the medial epicondyle.

Discussion/Conclusion:

The docking technique, as described in this video demonstration, is the most common MUCL reconstruction technique used today. When precise surgical steps are followed, complication rates are low and patient outcomes are favorable.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

Here is a brief overview of the procedure: As you all know, there have been a number of technical advances that have been made since Jobe et al initially described the procedure in the mid-1980s. In terms of indications, this is generally indicated for individuals who have failed conservative treatment of ulnar collateral ligament (UCL) injuries. For complete tears, usually a very short course of nonoperative treatment, typically about 6 weeks, may be trialed. For those with partial or incomplete tears, nonoperative treatment is typically 3 to 4 months before considering it a failure and moving on to UCL reconstruction. In terms of results, UCL reconstruction using the docking technique has a long track record of restoring valgus stability to the elbow and returning players back to play at an acceptably high rate in the 80% to 90% range. In conclusion, complication rates are relatively low, and patient outcomes are very favorable for UCL reconstruction using the docking technique.

The medial ulnar collateral ligament (MUCL) is the primary restraint to valgus stress at the elbow, and injury typically occurs during the late cocking and early acceleration phases of throwing. Multiple epidemiologic studies have demonstrated that injury and surgical rates continue to rise. Most patients typically present with medial elbow pain, decreased throwing velocity, and difficulty with control.

Preoperative planning begins in the clinical setting. After taking a history, proceed to a thorough physical examination of the elbow. Elbow range of motion is assessed. Then we look very carefully for any areas of tenderness to palpation which can be at the medial epicondyle, the sublime tubercle, or along the tendon itself. The moving valgus stress test is the primary physical examination maneuver of choice. Patients are also assessed for the presence of a palmaris longus. To do this, have them oppose the thumb and the fifth finger and flex the wrist. If they do not have the palmaris longus, then alternative grafts can be considered. In terms of imaging, typically we review radiographs and magnetic resonance images (MRIs) on all patients. If for some reason an MRI cannot be performed, a stress ultrasound may be done as well.

Here is a quick overview of the steps used for UCL reconstruction. The ulnar tunnel is created anterior and posterior to the sublime tubercle. Attention is then turned to the medial epicondyle where a large socket is created at the origin of the MUCL, and 2 small penetrating sockets are created on the anterior aspect of the medial epicondyle. Shuttling suture is then passed and used to shuttle the graft through the ulnar tunnel and dock into the medial epicondyle. The graft is then tensioned and cycled, length is determined, and the free end is then sutured and shuttled into the socket as well. Once again, the graft is tensioned, cycled, and tied for final fixation.

For surgery, the patient is positioned supine with the arm out on an arm board. It is important to prep the entire arm including the elbow and the anterior wrist.

For this case, we will demonstrate standard harvest for palmaris longus autograft. [Although the author’s preferred graft choice is ipsilateral palmaris longus, gracilis autograft or other allograft tendon can be used. Before beginning the surgery, the location and trajectory of the palmaris longus can be marked on the awake patient.] An incision is created in the proximal wrist crease, and very superficial dissection is performed to identify the palmaris longus autograft, which should be visible immediately below the skin. Great care is taken not to travel too deep to avoid injury to the neurovascular structures or other tendons of the wrist. [In addition, a counterincision on the proximal forearm to confirm identification of the palmaris longus can be used.] Once the palmaris longus tendon is isolated, it is then sutured using an 0 FiberWire suture in a running Krackow fashion. After the suture is placed, the graft is cut distal to the suture. Tenotomy scissors are then used to release any adhesions near the incision, and the sutures are loaded onto a small, standard tendon stripper or graft harvester. This is then passed in the direction toward the medial epicondyle, while traction is placed on the palmaris longus until it is released and freed.

Attention is then turned to the medial elbow where important anatomical landmarks are marked out, including the medial epicondyle and the ulnar nerve. [Care is taken to ensure that the incision does not cross the path of the ulnar nerve.] The typical incision ranges from 6 to 8 cm depending on the size of the patient, with two-thirds of the incision being distal to the medial epicondyle and one-third proximal. [If an ulnar nerve transposition is necessary, this can be done before MUCL reconstruction to minimize the risk of injury while drilling bone tunnels.] Electrocautery is used to dissect down to the fascia. Great care is taken to identify and preserve any branches of the medial antebrachial cutaneous nerve, [which is typically located between the subcutaneous fat and fascial layers,] when present. The fascia over the flexor carpi ulnaris is identified, and the posterior raphe is split in line with its fibers using a knife. The underlying muscle is then bluntly dissected using scissors and an elevator. Great care is taken to minimize any damage to this muscle. Continued blunt dissection down to the sublime tubercle allows the ligament to be easily identified. It is then split in line with its fibers, which allows visualization of the joint line. The joint can also be flushed at this time to remove any debris or loose bodies.

Attention is turned to the creation of the ulnar tunnel. A small area anterior and posterior to the sublime tubercle is debrided. The tunnel is typically placed 1 cm distal to the joint line. This can be done in a freehand fashion or using a V-shaped drill guide. In the case shown, 2 sockets are created that converge at their base. A curette is then used to remove any bony debris and to ensure that the tunnel is complete. It is helpful to insert the curette into one tunnel or one hole, and visualize it from the other. A small curved suture shuttle is then passed through the ulnar tunnel. This is then used to shuttle a free suture through the tunnel that is tagged, laid aside, and will be used for later graft passage.

Now, attention is turned to creating a socket on the humeral side. This is done at the origin of the MUCL, which is actually quite lateral on the medial epicondyle. A guide can be placed in the socket. The flexor pronator tendon is split in line with its fibers, and 2 small penetrating sockets are created with approximately a 1-cm bone bridge between the 2. These 2 converge at the base of the larger socket that was already created. A small skid can be placed in the socket, and a shuttle is used to shuttle a small wire through the penetrating sockets into the larger socket. A free suture is then shuttled. This is tagged and laid aside. The process is then repeated for the second small penetrating hole that was created in the anterior medial epicondyle. Again, a suture is passed, tagged, and laid aside.

A free suture is then used to reapproximate the capsule. This is the split that was previously created in line with the native ligament. This is done to tighten the medial structures, close the capsule, and ensure that the graft will be placed in an extra-articular fashion. This is tied at the end of the case. The shuttling stitch is then used to shuttle the graph through the ulnar tunnel. The sutured end of the graft is then shuttled into the socket, and tension is pulled to dock that end of the graft into the socket. The slack is then removed from the graft.

The graft is pulled tight and taken through an arc of flexion and extension to remove any creep. The spot where the graft intersects the opening of the large socket is marked. Once again, 0 FiberWire suture is used to suture the graft in a running, locking Krackow fashion. Excess graft is cut and discarded. This is done in such a way that it leaves the graft approximately 5 mm short of the bottom of the socket so that there is plenty of room to tension the graft without bottoming out the graft and losing your tension. It is then docked into the socket as well, joining the other end that has already been docked previously. Once again, the elbow is taken through a cycle of flexion and extension, while tension is applied to the graft to remove any creep. The sutures are tensioned and tied over the bone bridge on the anterior aspect of the medial epicondyle. This is done with the arm at approximately 30° of flexion and supination with a varus load applied. The suture that was previously placed in the capsule may then be tied over the top of the graft. This helps to unite the graft with the capsule and enclose the capsule to ensure that the graft stays in the extra-articular position. Excess suture can be cut. The split in the flexor pronator tendon is closed to minimize any irritation from the knot.

Postoperatively, the patient is placed in a splint for the first 2 weeks. They are transitioned to a hinged elbow brace working on range of motion from weeks 3 to 8 with the goal of full range of motion by weeks 6 to 8. Then strengthening is progressed as able, and an interval throwing program begins around week 16. [Mound throwing is initiated around 7 months postoperatively, once the patient is able to throw long toss at 120 feet consistently without difficulty. The overall goal is to return to competitive pitching by 1 year.]

Here is a list of potential complications that have been reported.

There are a number of pearls and pitfalls to be aware of. Some of the advantages of the docking technique are that there is no need for routine ulnar nerve exposure or transposition. However, if a patient does have ulnar nerve symptoms, the ulnar nerve can be decompressed and transposed to move it out of the way for the surgery. Other advantages include reduced bone loss compared with other techniques. The technique also minimizes damage to the flexor pronator origin using a muscle splitting approach. Also, this technique allows for precise control of tensioning of the graft. This technique has a historically high rate of returning athletes to throwing at an elite level of performance. There are a few potential limitations to be aware of. The ulnar nerve is not routinely visualized, so you must be aware of its location and try to protect it, particularly while drilling. As with any surgical technique, it requires precise knowledge of anatomical landmarks. Patients without a palmaris longus will require an alternative graft. It is important that you execute with technical precision particularly when drilling tunnels so that you ensure they coalesce at the appropriate locations. Finally, the loop suture or shuttling sutures can be difficult to pass if tunnel geometry is not appropriate or accurate.

When appropriate and meticulous surgical technique is followed, return to sport rate is quite high and complications are relatively infrequent. Accordingly, this has become one of the most common techniques used for MUCL reconstruction. Here are a few key references that you may find helpful.