Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Operative Treatment

For patients who fail nonoperative treatment, the procedure of choice is arthroscopic subacromial decompression (ASAD). The advantages of the arthroscopic approach include minimally invasive surgery without detachment of the deltoid.

This leads to a more comfortable postoperative recovery and the capability to accelerate rehabilitation. Arthroscopy also allows complete evaluation of the glenohumeral joint and the ability to address other pathology as identified.

As with the open procedure, general anesthesia is usually used. To decrease bleeding, the systolic blood pressure is kept below 100 mmHg unless there is a medical contraindication. Prior to final positioning, an examination under anesthesia is performed of both shoulders. This is done to detect any signs of occult instability as well as any palpable or audible signs of labral tears.

The ASAD procedure can be performed in the lateral decubitus or beach chair position. If conversion to an open procedure is necessary, this can be done easily from either position. With either position, care is taken to protect the patient’s head and neck during positioning. It is then firmly secured in a neutral position avoiding hyperflexion or extension.

We have generally used the lateral position and will describe our preferred technique. It is important to roll the patient back approximately 30 degrees from the perpendicular. If one starts with the patient too vertical, the shoulder tends to fall anterior and away from the surgeon.

The patient is stabilized with a beanbag and an axillary roll is appropriately positioned. The arm is placed in 30 degrees of abduction and 20 degrees of forward flexion. After prepping and draping, approximately 10 lbs of weight is applied to suspend the arm.

The osseous landmarks are clearly identified with a marking pen. The anterior, posterior, and lateral edges of the acromion, the clavicle, AC joint, and coracoid are clearly marked. This helps in establishing portals initially and more importantly later when shoulder swelling can make landmarks more difficult to identify.

The posterior portal is placed first. It is located at the soft spot 2 cm inferior and 2 cm medial to the posterolateral corner of the acromion. A pop will be felt as the cannula enters the capsule (Fig 11-7).

After in the glenohumeral joint complete diagnostic arthroscopy is carried out, a 14-gauge spinal needle can be placed anteriorly to allow for outflow. If no glenohumeral pathology is encountered, it may not be necessary to place an anterior cannula.

If an anterior portal is necessary, it can be established in the rotator interval with either an outside in technique following the path of the spinal needle or inside out using the cannula and blunt obturator to drive through the interval. Any glenohumeral surgery is carried out at this time with additional portals as needed.

Following this, one withdraws the arthroscope completely and, with the blunt obturator, redirects the cannula into the subacromial space. It may be helpful to drive the metal cannula through to the anterior portal and bring another cannula over the top. This clearly identifies your location and a shaver can be brought from the front. Under direct visualization, bursal tissue is removed and a space is created. It is important to maintain correct orientation to avoid inadvertent injury to the rotator cuff. The scope is positioned such that the acromion is superior and the cuff inferior throughout.

The lateral portal is placed next. It is positioned 1.5 to 2 cm inferior to the lateral border of the acromion. A spinal needle can be used to verify position prior to portal placement. The needle should be seen coming in parallel to the undersurface of the acromion and in line with the anterior portion of the acromion to be removed.

Correct position of this portal is necessary for correct bone resection. If the portal is misplaced in any direction, an angled cut of the undersurface of the acromion will result. If the portal is placed in such a way that a precise cut can not be done easily, it is better to make another portal than try to complete the resection from one that is poorly placed.

The shaver is used from the lateral portal to perform a partial bursectomy. A bipolar radiofrequency device is helpful to ablate the periosteum and fascia. The coracoacromial ligament is subperiosteally dissected off the acromion but is not resected. Adequate flow and pressure are maintained throughout the procedure.

Good visualization is essential. If any bleeding is encountered, it is addressed immediately with the radiofrequency device for coagulation. After the periosteum has been removed, the bony anatomy is clearly identified. A thorough examination of the rotator cuff’s bursal surface is critical to determine the presence of cuff pathology.

Bone resection is begun only after all soft tissue preventing visualization is removed. It is critical to expose the anterolateral corner to prevent inadequate resections. This is the site at which most contact pressure is applied to the rotator cuff during elevation and abduction.

An arthroscopic burr is brought in from the lateral portal and a step cut at the anterolateral corner is performed. The preoperative x-rays should be used to gauge how much resection is to be performed. The diameter of the burr is known and can be used to evaluate the depth of this initial resection. Generally we take 6 to 12 mm from the undersurface of the anterior acromion.

After the step cut is created and the appropriate amount of anterior resection is confirmed, we proceed to the rest of the acromion from lateral to medial. The anterior acromial resection is usually performed to keep the newly resected surface in line with the anterior surface of the AC joint. The initial step cut can always be used as a reference to ensure a flat line of resection. Care is taken to smooth the anterior surface and prevent detachment of the deltoid.

The entire procedure can be done working through the lateral portal, viewing from the posterior portal, and using the anterior portal for outflow. We do not employ a posterior cutting block technique. This technique is dependent on the morphology of the posterior acromion and has the potential for inadequate or excessive bone removal.

Following completion of decompression, the surgeon may want to place the arthroscope in the lateral portal to get an “outlet” perspective of what was done. Thorough irrigation should follow resection to remove all bony debris.

If distal clavicle resection is going to be performed, a bipolar radiofrequency device is again used to remove soft tissue and delineate the anatomic landmarks underneath the distal clavicle and AC joint. The arthroscopic Mumford procedure can then be performed with the burr brought in from the anterior portal.

A step cut is again helpful followed by completion of resection. If no AC surgery is to be performed we prefer not to violate or destabilize this area and do not perform a coplaning.

A pain pump can be placed into the subacromial space, particularly if concominant AC resection or rotator cuff repair is performed. The portals are closed and a sterile bulky dressing is applied. The patient is placed into a sling and usually discharged home within 2 hours. Neurovascular status is assessed and documented prior to discharge from the recovery room.

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