Posterosuperior Tears (Irreparable): Arthroscopic Superior Capsular Reconstruction—Allograft

Alan M. Hirahara

INTRODUCTION

Superior capsular reconstruction (SCR) with a fascia lata autograft was first reported in the literature in 1993 by Hanada et al as an option to address massive irreparable rotator cuff tears.¹ Mihata et al later took up the research and published his biomechanical and clinical data. Using a graft to recreate the superior capsule, the humeral head is centered in the glenoid, allowing the larger muscles (ie, deltoid, latissimus dorsi, and pectoralis major) to function appropriately. Mihata et al have found that the SCR reduces glenohumeral superior translation and subacromial contact force.²^,³ Mihata et al described their SCR technique using a 6- to 9-mm fascia lata autograft.⁴ Hirahara and Adams modified this procedure to use a thinner, 3.5-mm dermal allograft (Figure 21-1).⁵ Many SCR techniques have been described in the literature since the publication of these two papers.⁶^, ⁷^, ⁸^, ⁹^, ¹⁰^, ¹¹^, ¹² ^and ¹³

FIGURE 21-1 Intraoperative arthroscopic view prior to graft introduction (A). The massive cuff tear (dashed blue arrow) can be seen torn off of the greater tuberosity. The solid yellow arrow indicates the humeral head. The glenoid (asterisk) can be seen in the background. Intraoperative arthroscopic view of the superior capsular reconstruction (B). The dermal allograft implant can be seen secured in place.

When the supraspinatus tears and retracts medially, the superior capsule is also disrupted and superior constraint is lost. With no superior restraint to the humerus, the humeral head migrates superiorly, causing a decrease in the acromial-humeral distance, dysfunction, and pseudoparalysis.²^,³^,¹³ Other treatments for massive rotator cuff tears—debridement and tenotomy, tendon transfers, and reverse shoulder arthroplasty—have yielded varying results and high complication rates.¹⁴

INDICATIONS

The indications for SCR with dermal allograft have evolved over the years. The first reports indicated the use of SCR with dermal allograft was for irreparable massive supraspinatus and/or infraspinatus tears. When the torn tendon cannot reach to the original footprint, the rotator cuff tear is defined by Mihata as an irreparable tear.³

With an SCR in place, a rotator cuff tear that was initially too tight or lacked robust tissue can sometimes be mobilized back to the tuberosity, improving the chance of healing. Most surgeons who perform SCR now see the main indication for massive and irreparable supraspinatus and/or infraspinatus tears that have a poor chance of healing.¹⁵^, ¹⁶ ^and ¹⁷ Other accepted indications are failed conservative management, intolerable shoulder pain, minimal glenohumeral arthritis, an intact or reparable subscapularis, subjectively unacceptable dysfunction, younger patients, and pseudoparalysis.⁴^,¹⁸^, ¹⁹ ^and ²⁰

CONTRAINDICATIONS

The contraindications to SCR with dermal allograft vary by the surgeon. Most surgeons will not perform the SCR with dermal allograft for patients who have moderate to severe glenohumeral arthropathy (Hamada 4 or greater); bone defects or changes; absence of subscapularis, deltoid, latissimus dorsi, teres minor, or pectoralis function; glenohumeral joint stiffness; a defect greater than 4 cm anterior to posterior; neurologic deficit or impairment affecting the glenohumeral joint; and infection.⁵^,¹²^,¹⁸^, ¹⁹ ^and ²⁰

Hamada grade 3 is a relative contraindication.⁷^,¹⁸^,¹⁹ The presence of the subscapularis and teres minor is critical to the success of the surgery. Anterior and posterior stability is needed for the SCR to complete the circle of stability for shoulder. Stiffness of the shoulder will not be improved with SCR and should be addressed separately from any cuff pathology. This could be related to adhesive capsulitis, nerve injury, primary muscular dysfunction, or glenohumeral arthritis with secondary stiffness. If the defect is greater than 4 cm, the re-creation of the superior constraint will be incomplete as the largest current dermal allograft available is 4 cm in width. Attachment to the posterior existing tissue is needed to prevent posterior subluxation of the humeral head.

PREOPERATIVE PREPARATION

History

Standard history should be taken from the patient, including patient age, occupation, and activity level. Important factors like the chief complaint (ie, pain or dysfunction), mechanism of injury, acuity and chronicity, duration of the complaints, the location of the pain and the severity, and past surgical repairs should be noted. A thorough search for reasons for past surgical failures can help with determination of treatment like infection, poor local biology (metal implants, cysts, sclerosis, cortisone injections, thin or absent cuff, failure at musculotendinous junction from previous surgery), or poor global biology (diabetes, obesity, smoking, prednisone or other medicine use, inflammatory arthropathies). If a patient has had prior surgery, obtaining the operative report and intraoperative pictures can sometimes help tremendously by getting a preview of what was previously there and done.

Physical Examination

Standard physical examination with appropriate special examinations should be done. The examination begins with inspection. Factors should be evaluated that pertain to potential outcomes of SCR. How the patient carries the arm, muscular atrophy, scapular symmetry, and humeral head prominence gives the sense of pain, guarding, strength, and general use. Previous surgical incisions should be evaluated for signs of inflammation, suggesting possible infection.

Glenohumeral movement, both active and passive, should be evaluated. Hiking of shoulder girdle should be noted. Restriction in both active and passive motion highly suggests adhesive capsulitis, glenohumeral osteoarthritis, or a dislocated shoulder. True stiffness must be identified as it could yield poor outcomes. However, pseudoparalysis, the definition of which has been debated but usually is when active forward elevation is less than 90° but retained passive motion, might be treated with an SCR procedure.

Strength testing is very important to determine the status of the rotator cuff. External rotation weakness is classic for rotator cuff tears. The deltoid can mask the weakness of forward elevation. Besides the general strength evaluation, specialized tests help assess the shoulder’s specific structures.

Supraspinatus Testing

The Jobe test is done by placing the arm in 90° of abduction, 30° of horizontal adduction, and full internal rotation and resisting downward force. This is considered positive when weak or painful; however, pain can be indicative of inflammation and partial or full tearing.
The full can test is done like the Jobe test except that the humerus is externally rotated 45°, as if the patient is holding a can.
The drop arm test is done with the patient’s arm actively abducted to 90° and then patient slowly lowers the arm. A positive test is when the patient cannot lower the arm slowly and instead drops the arm.

Posterior (Infraspinatus/Teres Minor) Testing

The external rotation test is done with the elbow in 90° of flexion, the arm by the side internally rotated 45° and then asking the patient to externally rotate the arm against resistance.
The Patte (Hornblower) test is done with the patient’s elbow in 90° of flexion with the arm abducted in the scapular plane while the patient externally rotates the arm against resistance. A positive test is when the patient cannot externally rotate against resistance.
The external rotation lag sign (dropping sign) is done with the patient’s elbow in 90° of flexion with the arm at the side and then externally rotating the arm 45°. The test is positive if the patient cannot hold the externally rotated position after the examiner lets go.

Subscapularis Testing

The belly press (Napoleon) test is done with the arm at the side and the elbow flexed to 90°, with the palm pressing into the abdomen while keeping the arm maximally internally rotated and the elbow forward. If the elbow or shoulder extends or the wrist flexes to maintain pressure against the belly, the test is positive.
The belly-off test is done with the arm in the same position as the belly press test but with the elbow of the patient supported by one hand of the examiner while the other hand brings the arm into maximum internal rotation with the palm of the patient on the abdomen. If the patient cannot maintain a straight wrist and maintain the internal rotation when the wrist is released, the test is positive.
The lift-off test is done with the hand on the back at the level of the mid-lumbar spine and the arm internally rotated, trying to lift the hand off the back. The test is positive if the patient cannot lift the arm off the back or if the hand lifts off the back by elbow or shoulder extension.
The bear hug test is done with the palm of the affected shoulder placed onto the opposite shoulder with the elbow held forward and the fingers extended, and the patient’s hand is pulled from the shoulder using an external rotation force. If the patient cannot hold the hand against the shoulder, then the test is positive.
The internal rotation lag sign is done by having the affected arm of the patient held by the examiner behind the back and placed into maximum internal rotation by lifting the patient’s hand away from the body before letting go of the patient’s hand and asking them to hold this position. If the patient cannot hold the position, the test is positive.
The internal rotation resistance test at abduction and external rotation is done with the shoulder at 90° of abduction and external rotation and with the elbow at 90° of flexion. The patient resists an external rotation force applied perpendicular to the forearm. If there is weakness, the test is positive.

The most important part of the physical examination for cuff pathology is the strength of the posterior segment. The strength of the posterior cuff will suggest what kind of outcome a patient may
have from the SCR procedure. If significant weakness exists and the patient requires posterior cuff strength, the patient may be disappointed with their outcomes from an SCR procedure.

Because cervical spondylosis and radiculopathy can cause shoulder pain and mimic rotator cuff pathology, evaluation for neurological and cervical pathology is necessary as it will affect the determination of treatment type. In the setting of neurologic deficiency, SCR may be an inappropriate treatment for a concurrent massive rotator cuff tear.

Imaging

Standard shoulder radiographs including an upright anteroposterior (AP), lateral, and axillary view should be performed to assess the acromiohumeral (AH) interval and level of arthritic changes as determined by the Hamada classification.²⁰ Bone wear or loss and subluxation should also be noted. Humeral head superior migration and decrease of the AH space indicate a massive rotator cuff tear. An AH space <7 mm is consistent with a rotator cuff tear, and a space <5 mm indicates a massive tear (Figure 21-2). Observation of other causes of pain like chondrolysis, loose anchors, and acromial fracture should be noted.

FIGURE 21-2 Preoperative anteroposterior radiograph (A). The decrease in the acromial-humeral distance (yellow line) is an indirect indication of a massive rotator cuff tear and disruption of the superior capsule. Corresponding radiograph of the same patient 13 months after surgery (B). The acromial-humeral distance (green line) can be seen to be increased compared with the preoperative image. This indicates the SCR is holding the humeral head centered in the glenoid.

Conventional arthrography and ultrasonography have little utility for massive rotator cuff tears. These modalities are useful for the determination of partial and full tears. They have limited utility for tears with retraction beyond the acromion, fatty infiltration of muscle, and AH distance.

Magnetic resonance imaging (MRI) should be done to evaluate supraspinatus and infraspinatus tear size and pattern, retraction, atrophy, and fatty infiltration. Fatty infiltration of the supraspinatus and infraspinatus muscle indicates chronic pathology and decreasing chance of reparability.¹⁵^, ¹⁶ ^and ¹⁷ Postoperative MRI is less accurate and can overdiagnose recurrent rotator cuff tears and poorly assesses recurrent tear size.²¹ MR arthrography should be considered.

Other Diagnostic Tests

Electrodiagnostic testing should be considered when one suspects neurologic injury or cervical radiculopathy. Inflammatory markers (ie, erythrocyte sedimentation rate and C-reactive protein) should be checked when suspecting postoperative infection, and consideration should be given to joint aspiration for cell count, Gram stain, and culture, and cultures should be retained for a minimum of 7 days.

TECHNIQUE

Numerous techniques with equal amounts of controversy exist regarding the best repair technique.⁴^, ⁵^, ⁶^, ⁷^, ⁸^, ⁹^, ¹⁰^, ¹¹ ^and ¹² Ultimately, the correct technique depends on the surgeon’s abilities, available hardware, size of defect attempting to cover, and status of residual tissue (

Video 21-1). No solitary technique will work for every case, and the surgeon must be prepared to adapt to the presenting situation. Failure will occur when trying to apply a single fix for every case.

View Quicktime Video

Video 21-1

Studies have shown a steep learning curve for SCR with a high failure rate in the surgeon’s earlier cases.²² This is commonly related to applying dogmatic principles of implantation like always cutting the graft to a specific size as opposed to measuring the distances between anchors with the arm in a patient-appropriate position (Table 21-1).

TABLE 21-1 Surgical Pearls/Key Points

Surgical Pearls/Key Points

Arm should be in neutral position for measurements

Span entirety of defect with graft

Accurately measure distance between anchors over curvilinear distance

Use a 3.5-mm-thick dermal allograft

Perform anterior and posterior margin convergences (if rotator interval tissue present)

Larger anchors can be used if significant bone defects present

Issues to Address When Determining the Technique

Issue 1: Spacer Versus Capsular Reconstruction

When deciding on capsular reconstruction, the principle to follow is to adequately tension the superior capsule to hold the head down. If the reconstruction is too loose, the graft will be useless and the head will continue to be unstable. If the reconstruction is too tight (ie, the graft is measured too small or the graft is placed with the arm in abduction), the patient will not have good function and will have increased pain and the construct will be at greater risk of failure. A third possibility is that the graft is placed asymmetrically tensioned, as can happen when a graft is measured then placed with the arm in too much internal rotation.

If a spacer effect is desired, then using a very thick (6-9 mm) device or tissue is required to hold the head down to prevent superior migration of the humeral head, recreating the normal AH distance in the native shoulder, as seen with the balloon spacer device.²³

Issue 2: Graft Type

Different graft types have differing characteristics. The fascia lata is a weak graft. Testing has shown the dermal graft to be more elastic than fascia lata, which can give diminished range of motion after implantation.²⁴ The fascia lata must also be harvested and has been shown in studies to be painful after harvest.²⁵

The 2 graft types are quite different, and when approaching the techniques of implantation, the surgeon must be cautious about applying research from one graft to the other. Dermal allograft elasticity will allow for greater deformation without failure; however, stability is compromised if the graft is too loose when implanted. Conversely, if the graft is implanted too tightly, overconstraint results in increased joint reaction forces, causing greater pain, failure of fixation, or failure of the graft.

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