in General Glenohumeral and Subacromial Space Procedures

Fig. 2.1

(a) AP radiograph of a patient with a critical shoulder angle (CSA) auf 33°. (b) Y-view showing the significant spur formation at the anterolateral acromion edge. The calculated resection is about 10 mm aiming to create a type 1 acromion. (c) Postoperative AP view: Due to the conventional acromioplasty (cutting block technique) with resection of the spur the CSA is reduced to 28°. (d) The undersurface of the acromion has been shaped to be plane

2.1.1 Pre Operative Complications (Indication)

The unavoidable first condition indicating acromioplasty is the clinical evidence of subacromial impingement symptoms using the established tests. Thereby it is essential to exclude diagnoses causing similar complaints. In the clinical routine the most often confounded diagnosis is the initial state of an adhesive capsulitis. An effective test to differentiate between both pathologies is to examine the patients for painless external rotation in neutral abduction. This maneuver will cause pain and/or will be restricted in patients with adhesive capsulitis. Further rare diagnosis like a thoracic outlet syndrome (Fig. 2.2), a suprascapular nerve compression caused by a ganglion cyst or an os acromiale as a morphological anomaly (Fig. 2.3) should be kept in mind. If the clinical diagnosis is made an, an MRI scan and X-ray diagnostics should be performed. While the MRI is needed to rule out alternative pathologies, X-rays are necessary to plan procedure. If an instable symptomatic os acromiale is detected, this can be fixed using compression screw osteosynthesis to decompress the subacromial space and stabilize the deltoid muscle origin (Fig. 2.3). In such cases an acromioplasty should be strictly avoided to prevent further weakening of the acromion.

../images/437034_1_En_2_Chapter/437034_1_En_2_Fig2_HTML.jpg — Fig. 2.2

DSA of a patient who suffered from right shoulder pain for 12 years and had been treated twice by surgery (First time: acromioplasty, Second time: Revision surgery with ACJ resection) without relief. After proof of a positive Adson-Test the angiography showed a dynamic compression of the subclavian artery under the clavicle during abduction and retroversion of the affected arm (b). In the neutral position (a) the filling of the artery is normal

../images/437034_1_En_2_Chapter/437034_1_En_2_Fig3_HTML.jpg — Fig. 2.3

Patient with persistent subacromial bursitis and complaints after an arthroscopic subacromial decompression procedure. (a) The axial radiograph shows a large os acromiale (Mesoacromion), with was found to be instable and painful. (b) Further the subacromial space was narrowed by angulation of the os acromiale. Postoperative axial X-ray (c) and 3D CT (d) after arthroscopic assisted screw fixation of the os acromiale

In cases with a well marked subacromial spur formation and corresponding rotator cuff pathology (Fig. 2.4) the amount of acromioplasty should be planned based on AP and lateral radiographs (Fig. 2.1a, b).

../images/437034_1_En_2_Chapter/437034_1_En_2_Fig4_HTML.jpg — Fig. 2.4

(a) MRI scan of a typical supraspinatus tendon lesion (“impingement lesion”) evoked by a subacromial spur (upper arrow). The tendon lesion involves the bursal layer and is located medial to the rotator cuff footprint (b). During arthroscopy the friction mechanism of the lesion could be verified

2.1.2 Per Operative Complications

The major complication during surgery is the insufficient realization of the preoperative planning. This means the resection of the anterolateral undersurface of the acromion is either overestimated or underestimated. A typical reason for the under-resection is the insufficient preparation of the anterior edge of the acromion. To properly visualize the spur formation, the coracoacromial ligament needs to be at least partially released (Fig. 2.5a). To prevent an excessive resection of the acromion a reference at the anterolateral acromion edge should be made with a burr corresponding to the preoperative planning (Fig. 2.5a). Thereby the deltoid insertion and the fascia of the deltoid should be kept intact. A detachment of the deltoid fascia could impair visualization of the rotator cuff, if the subdeltoid space collapses. To realize a straight and smooth undersurface of the acromion (Type 1 acromion) the finish of the acromioplasty should be performed in line with the undersurface of the posterior acromion viewing from an anterolateral portal (cutting block technique) (Fig. 2.5b, c). If there is no symptomatic acromioclavicular joint (ACJ) arthritis, a violation of the ACJ capsule should be avoided to prevent a valve gear mechanism.

../images/437034_1_En_2_Chapter/437034_1_En_2_Fig5_HTML.jpg — Fig. 2.5

(a) Arthroscopic view on the anterolateral undersurface of the acromion form a posterior portal. The coracoacromial ligament (CAL) has been released from the acromion. With regard to the colour of the bone one might differentiate between the spur and the native acromion. A burr (5.5 mm) is introduced through a anterolateral portal to create a resection reference. (b) In the second step of the procedure the resection is completed with the arthroscope in the anterolateral portal and the burr in the posterior portal. The undersurface of the anterolateral acromion is shaped to be in line with the posterior part of the acromion (c)

2.1.3 Immediate Postoperative Complications

There may be general complications like hematoma and infection.

2.1.4 Middle Term Complications

The most relevant complication after isolated acromioplasty is persistent pain. Basically, there are three possible reasons for persistent complaints, which should be systematically reassessed. First, the indication for acromioplasty was incorrect. For instance, the symptoms may have been caused by functional problems (scapula dyskinesia, posterior shoulder instability, unstable painful shoulder), which is typical problem in young patients with chronic shoulder disability. As mentioned, adhesive capsulitis in its initial stadium is a second typical differential diagnosis, which is frequently missed.

Second, the indication has been made correct but the procedure has been performed insufficiently (persisting subacromial spur, persisting bursitis). In such cases revision surgery should be considered if the “revision target” can be clearly named. In patients reporting continuous pain a low grade infection should be further ruled out.

Third, concomitant shoulder pathology has not been treated. Therefore, typical pathologies like ACJ arthritis, lesions of the biceps tendon (SLAP-, pulley), partial supraspinatus tendon tear, calcific tendinitis and perilabral ganglion cysts should be re-evaluated.

Further a secondary adhesive capsulitis may occur caused by the “surgical trauma” or provoked by postoperative immobilization.

2.1.5 Long Term Complications

There are no typical long term complications reported in the literature [8]. If acromioplasty was performed to treat a rotator cuff tear without a repair of the tendon, 74% of the patients were reported to develop cuff tear arthropathy at a mean follow up of 22 years [9].

2.2 AC-Joint Resection

Osteoarthritis of the acromioclavicular joint (ACJ) is a common condition causing anterosuperior shoulder pain, especially with cross-body and overhead activities. It most commonly occurs in middle-aged individuals with high level physical activity. The diagnosis can be challenging and relies on history, physical examination, imaging and diagnostic injection if applicable.

2.2.1 Pre Operative Complications (Indication)

The indication for surgery is based on a necessary (sine qua non) and a sufficient condition. Thereby the verification of ACJ arthritis in the MRI displays the necessary condition. According to the current literature, the predictive relevance of different criteria is inconclusive. However, most studies detected a bone marrow edema of the distal clavicle as well a superior and inferior capsular distension (cutoff value: 2 mm) as the most predictive parameters [10, 11] to discriminate between symptomatic and asymptomatic ACJ arthritis. In addition to the MRI characteristics, the patient needs to present distinct symptoms of ACJ arthritis to indicate a symptomatic ACJ arthritis. Currently such symptoms have been combined to develop a severity score for ac-joint arthritis [12]. The most typical complaints are local tenderness on palpation, local pain with crossbody action, a “high painful arc” with end range of motion elevation, pain during night and pain lying on the affected shoulder. As a differential diagnosis, patients with a trauma history should be evaluated for low grade ACJ instability (Rockwood I-II), distal clavicle fracture and posttraumatic osteolysis of the distal clavicle. Infrequently an aseptic or septic osteolysis of the distal clavicle may be the reason for ACJ complaints.

In symptomatic cases of ACJ arthritis an arthroscopic distal clavicle resection or symmetric ACJ resection can be performed if conservative therapy has failed. For this procedure good to excellent results have been reported in the midterm and longterm follow up [13, 14]. On the other hand, it has been shown that a preventive arthroscopic distal clavicle resection in patients with a rotator cuff tears and radiological (but asymptomatic) ACJ arthritis seems not beneficial [15]. Even for patients with symptomatic ACJ arthritis there was no benefit found for distal clavicle resection in the course of rotator cuff repair 2 years after surgery [16]. However, there may be a positive effect of distal clavicle resection after 2 years [17].

2.2.2 Per Operative Complications

The aim of arthroscopic distal clavicle resection is to decompress to ACJ (resection arthroplasty) for pain relief without substantial destabilization. During the procedure care should be taken to keep the posterior and superior ACJ capsule intact, because they have been shown to be the basic restraints against vertical and horizontal instability. Regarding the capsule and ligament insertions the safe zone for resection has been shown to be 3–4 mm for the distal clavicle and 2–3 mm of the medial acromion [18]. Further it has been shown that a 5 mm distal clavicle resection is effective for eliminating bone contact in the ACJ [19]. To minimize detachment of the ACJ capsule at the distal clavicle currently bipolar symmetric resection techniques of the distal clavicle and the medial acromion are recommended [20–22].

The most frequent intraoperative complication of ACJ resection is an insufficient bony decompression. There may be several technical reasons:

There was no adequate view on the resection surface of the distal clavicle resulting in an insufficient resection the anterosuperior and posterosuperior quadrant.
The individual joint line of the ACJ was not respected. The joint line and accordingly the plane of the distal clavicle can be oblique ascending. If the resection line in such cases is performed perpendicular to the undersurface of the clavicle, this will result in an underresection of the lower quadrants.
There are still bony remnants at the superior resection surface (commonly arch-shaped in contact with the superior capsule) (Fig. 2.6).
The resection surface has become irregular, with a “central cavity” and a proud cortical ring of the distal clavicle.

../images/437034_1_En_2_Chapter/437034_1_En_2_Fig6_HTML.png — Fig. 2.6

(a) Preoperative AP radiograph of a patient with symptomatic ACJ arthritis. (b) Postoperative X-ray after distal clavicle resection, when the patient presented with persistent complaints. (c) The postoperative Zanca-view showed a posterosuperior bony remnant as the reason for persisting pain

To avoid these possible pitfalls, some technical advices should be respected. First, the ac-jointline should be checked in the MRI scans in the coronar view (straight, oblique: “overriding clavicle”, oblique: “underriding clavicle”) and axial view (convex, straight). According to this information the resection line and portal placement can be planned. For optimization of the arthroscopic view, osteophytes at the medial acromial border should be resected in the first step. The anterior working portal should be created in an outside-in-technique exactly in line with the native ACJ to prevent an oblique resection line caused by incorrect portal placement. Afterwards the inferior part of the distal clavicle should be prepared to get an orientation of the joint line (Fig. 2.7). Then a reference of the resection depth should be prepared in the anteroinferior quadrant of the clavicle using a burr (Fig. 2.7b). The resection is then sequentially completed from anterior to posterior and from inferior to superior. Finally the posterosuperior quadrant should be resected. If the resection has been planned oblique according to the native joint line, this should be respected during resection. To create a good view of the posterior aspect of the ACJ the creation of an anterolateral viewing portal may be useful, if a 30°-arthroscope is used (Fig. 2.7c). After the resection process the resection line should be checked switching the arthroscope to the anterior portal (former working portal). This steps enables 3D imaging of the created “joint space”. Especially a sufficient resection of the posterior quadrants is checked again. Further, a spinal needle can be used the check the superior resection surface for bony remnants at the ACJ capsule (Fig. 2.7d).

../images/437034_1_En_2_Chapter/437034_1_En_2_Fig7_HTML.jpg — Fig. 2.7

Technique of arthroscopic ACJ resection. En face view on the lateral clavicle from a lateral viewing portal (a). Osteophytes at the medial acromion border have been resected and inferior capsule is opened to visualize the anteroinferior aspect of the distal clavicle. A resection depth reference is marked in the anteroinferior quadrant (b). The obliquity of the resection line is checked and revised looking from anterolateral viewing portal (c). Finally the superior compartment is checked for bony remnants using a spinal needle (d)

As a second relevant intraoperative complication an iatrogenic ACJ instability caused by an extensive distal clavicle resection may occur [23]. In such cases the ACJ instability is typically caused by bone loss of the distal clavicle and detachment of the ACJ capsule. This complication can be effectively prevented with creation of resection depth reference at the start of the procedure. Further “blind resection” of the upper quadrants should be avoided to prevent weakening of the superior capsule.

2.2.3 Immediate Postoperative Complications

There may be general complications like hematoma and infection. If there is suspicion that persistent pain may be explained by iatrogenic AC-capsule violation, the affected arm should by be immobilized in a sling for 3–4 weeks. Further, heavy working activities should be avoided for 6–8 weeks enabling for soft tissue consolidation.

2.2.4 Middle Term Complications

The most frequent complication is persisting ACJ associated pain [24]. In such cases radiographs including a Zanca-view of the ACJ should be conducted (Fig. 2.6c). Thereby under-resection or incomplete resection can by evaluated. Further heterotopic ossification of the AC-capsule can be verified, which has rarely been reported [25, 26]. As another option, a joint effusion or persistent bone marrow edema of the distal clavicle may be possible reasons for continuous pain. Such pathologies should be reassessed with an MRI and if appropriate treated with a local corticoid injection.

On the other hand, instability of the ACJ should be evaluated, if there is evidence of extensive distal clavicle resection (Fig. 2.8a). In such cases especially Alexander-view images are useful to quantify the horizontal displacement of the lateral clavicle [27] (Fig. 2.8b). If a symptomatic iatrogenic ACJ instability is evident (most of the cases are classified as “painful Rockwood type II” without violation of the coracoclavicular ligaments), surgical revision with an ACJ-capsuloplasty using a free tendon graft (Gracilis) and is recommended [23] (Fig. 2.9).