8 Indications and Techniques of BIO-RSA for Cuff Tear Arthropathy, Including Associated Soft Tissue Transfers for Loss of External Rotation



10.1055/b-0037-146569

8 Indications and Techniques of BIO-RSA for Cuff Tear Arthropathy, Including Associated Soft Tissue Transfers for Loss of External Rotation

Brian Seeto, Stefan Rahm, and Pascal Boileau


Abstract


Reverse shoulder arthroplasty (RSA) has been successfully utilized to restore active forward elevation in patients with a nonfunctional shoulder due to cuff tear arthropathy. Despite the success, concerns over scapular notching, limitations in mobility, stability, and cosmesis exist. In order to address these problems, modifications to the original Grammont RSA design have been proposed. One such example is increased glenoid component lateralization with a bone graft, named bony-increased offset RSA (BIO-RSA). In this chapter, the authors will describe (1) the concept of shoulder muscular balance in the vertical and horizontal plane; (2) the rationale, indications, and techniques for performing a BIO-RSA; and (3) the indications and techniques for performing a BIO-RSA in combination with a muscle transfer for patients with combined loss of activation elevation and external rotation.




8.1 Introduction


The shoulder is a complex joint affected by a variety of balanced muscular forces. The concept of glenohumeral force-couples emphasizes the presence of both a vertical and horizontal plane. 1 It is important to understand that, in its natural state, the shoulder is unbalanced in both of these planes (► Fig. 8.1). Vertically, the power of the deltoid exceeds that of the rotator cuff muscles. Likewise, in the horizontal plane, the number of internal rotators exceeds the number of external rotator muscles. 2 , 3 In a pathologic shoulder, the delicate balance is disrupted, leading to pain and/or a loss of function. Patients with a nonfunctional shoulder due to massive, irreparable cuff tears can generally be categorized into three groups: (1) those with an isolated loss of active elevation or shoulder pseudoparalysis; (2) those with an isolated loss of active external rotation (ILER); and (3) those with combined loss of elevation and external rotation (CLEER). It is critical for surgeons to be able to appropriately characterize and diagnose patients in order to choose the appropriate surgical therapy.

Fig. 8.1 Illustration of the fragile shoulder muscle balance in the vertical (a) and horizontal (b) planes. With aging, the rotator cuff muscles become weaker, whereas the deltoid remains strong. The external rotator muscles, already inferior in number, become weaker than the internal rotator muscles. D, deltoid; ER, external rotation; IR, internal rotation; O, center of rotation; RC, rotator cuff.


8.2 Vertical Muscle Balance and Cuff Tear Arthropathy


With aging, the rotator muscles weaken, whereas the deltoid muscle remains relatively strong. The balance between the head-elevating deltoid and head-depressing effect of the rotator cuff becomes disrupted. As the process continues, the rotator cuff tendons are compressed against the undersurface of the acromion, leading to anterosuperior cuff impingement and eventually cuff wear. Proximal retraction of the rotator cuff tear is followed by fatty infiltration and eventually proximal migration of the humeral head under the acromial arch. The shoulder gradually transforms into a constrained joint and becomes more like the hip, with acetabulization of the acromial arch (rounding of the acromion and ossification of the coracoacromial ligament) and femoralization of the humeral head (rounding of the greater tuberosity). This constrained joint may still be balanced and functional (► Fig. 8.2). This process may eventually lead to painful arthritis and/or a pseudoparalyzed shoulder if the shoulder becomes unbalanced. The five stages of cuff tear arthropathy described by Hamada and Fukuda 4 are defined as follows:

Fig. 8.2 An example of a well-balanced “shoulder-hip joint.” (a) Radiograph showing a massive rotator cuff tear, with demoralization of the proximal humerus and acetabulization of the acromion (Hamada stage 3). Clinically, the shoulder remains well balanced in the vertical plane (b) and the horizontal plane with normal external rotation (c).



  • Stage 1: a balanced cuff tear without proximal migration of the humeral head (acromiohumeral distance more than 6 mm).



  • Stage 2: upward migration of the humeral head without any secondary bony changes (acromiohumeral distance 5 mm or less).



  • Stage 3: remodeling of the subacromial space with erosion of the undersurface of the acromion and the greater tuberosity (acetabulization and femoralization).



  • Stage 4: glenohumeral narrowing in addition to stage 3, with predominantly superior erosion of the glenoid.



  • Stage 5: collapse of the humeral head in addition to stage 4.



8.3 Bony-Increased Offset Reverse Shoulder Arthroplasty


Since its introduction in the 1980s by Professor Paul Grammont, the traditional reverse ball-and-socket prosthesis has proven to be a successful surgical treatment for the treatment of cuff tear arthropathy. However, some problems and complications related to the medialized design have been encountered 5 , 6 , 7 : (1) inferior scapular notching, (2) limited shoulder rotation, and (3) prosthetic stability.


Inferior scapular notching of the humeral insert against the pillar of the scapula during adduction and rotation of the arm is responsible for bone erosion and polyethylene wear and has been observed in 50 to 96% of reverse shoulder arthroplasty (RSA) on postoperative radiographs. Likewise, anterior scapular impingement may restrict internal rotation and posterior impingement may restrict external rotation. Humeral medialization may also lead to prosthetic instability, which has been observed in 3 to 6%. 8 Finally, humeral medialization may raise a cosmetic concern given that some patients dislike the loss of their normal shoulder contour after an RSA. 2


In an effort to address these issues, changes to the traditional Grammont design have been suggested. A lateralized RSA, with an increase in the offset of the glenosphere or baseplate, has been proposed to reduce the risk of scapular notching, and improve stability and mobility in rotation, while restoring shoulder contour 8 , 9 and retensioning the remaining rotator cuff. 10 The net effect of lateralization, however, is increased torque and shear forces on the glenoid component. In a biomechanical study, Harman et al 11 demonstrated a fourfold increase in displacement of the glenoid component when comparing a 7-mm increased-offset baseplate to the traditional medialized Grammont design. In clinical practice, increased-offset RSAs have been associated with higher rates of glenoid component loosening and baseplate screw breakage. In the series of Frankle et al, 9 there was no scapular notching observed; however, eight baseplate failures in seven patients required revision (12% rate of glenoid loosening). In contrast, Guery et al 12 reported a 4% rate of glenoid component loosening between 5 and 10 years of follow-up.


In an effort to neutralize shear forces on the glenoid component, we prefer bony lateralization of the RSA compared to metallic lateralization. This is achieved by bone grafting the reamed glenoid surface with a disk of cancellous bone (usually humeral head autograft) under the glenoid baseplate. Our goal is to obtain bony lateralization of the prosthesis while maintaining the prosthetic center of rotation at the glenoid bone-prosthesis interface. Once the bone graft has healed to the native glenoid, the torque on the glenoid component should be minimal, protecting from glenoid loosening, while the problems related to medialization are prevented. We have named this bony increased-offset reverse shoulder arthroplasty or BIO-RSA.



8.4 Indications for BIO-RSA


The BIO-RSA can be offered as a treatment for patients presenting with a painful and pseudoparalytic or stiff shoulder related to rotator cuff deficiency, that is, disruption of the vertical muscular couple (► Fig. 8.3). Surgeons should be aware that a painful loss of active elevation should not be mistaken with a true pseudoparalyzed shoulder.

Fig. 8.3 Definitive vertical muscle balance results in an isolated loss of active elevation. (a) Preoperative AP radiograph of a massive cuff tear with decreased (< 7 mm) of acromiohumeral distance (two parallel lines). (b) Postoperative clinical photograph following failed attempt of arthroscopic repair of a massive, irreparable cuff tear and acromioplasty. Prior to surgery, the patient had active shoulder elevation. (c) Passive elevation is conserved, confirming that this is not a stiff shoulder but a shoulder with imbalance of the vertical muscular couple.


8.4.1 Cuff Tear Arthritis (Hamada Stage 3, 4, and 5)


Cuff tear arthritis is undoubtedly the best indication for the BIO-RSA.



8.4.2 Massive Cuff Tear without Osteoarthritis (Hamada Stage 1 and 2)


Massive cuff tear without osteoarthritis can be indicated in two circumstances: (1) when there is a persistent pseudoparalyzed shoulder (anterosuperior escape of the humerus when attempting to elevate or abduct the arm, i.e., dynamic instability) and (2) in cases of static anterior instability (with coracoid impingement) or static posterior instability.



8.4.3 Failed Cuff Repair


A failed cuff repair may be an indication for BIO-RSA in cases of persistent pseudoparalyzed shoulder or stiff shoulder related to rotator cuff deficiency. It is important to exclude infection as a cause of failure prior to attempting arthroplasty.



8.4.4 Primary Osteoarthritis


Primary osteoarthritis may also be an indication for BIO-RSA in three circumstances: (1) when there is an associated large or massive tear; (2) severe infiltration (Goutallier stage 3 or 4); and (3) in case of severe glenoid erosion with bone deficiency (Walch B2 or C glenoid). 13



8.4.5 Fracture Sequelae


This may be an indication if the humeral bone stock is conserved. In cases in which the humeral head bone stock is insufficient (humeral head necrosis, fracture sequelae type 4, revision arthroplasty, tumors), the BIO-RSA can be performed with an autologous iliac bone graft or allograft.



8.4.6 Acute Four-Part Fracture


Finally, a BIO-RSA can also be performed using the fractured humeral head as a bone graft.



8.5 Surgical Technique for BIO-RSA



8.5.1 Patient Positioning and Approach


The patient is positioned in the beach-chair position following administration of a combined general anesthetic and interscalene block. We perform all cases through a standard deltopectoral approach, moving the cephalic vein laterally. The long head of the biceps tendon is tenodesed to the transverse humeral ligament and the “three sisters” are ligated routinely. The subscapularis is peeled directly off of the medial border of the bicipital groove with the electrocautery and may be reattached at the end of the case if appropriate.

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May 24, 2020 | Posted by in ORTHOPEDIC | Comments Off on 8 Indications and Techniques of BIO-RSA for Cuff Tear Arthropathy, Including Associated Soft Tissue Transfers for Loss of External Rotation

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