Monday, May 25, 2015

Reverse total shoulder results and complications

The reverse total shoulder offers a treatment option for a problem that previously had none: the unstable, cuff deficient shoulder. There are now substantial reports of the use of this type of prosthesis to manage a wide range of pathologies, including rotator cuff deficiency without arthritis (see example below in which pseudoparalysis after an attempted tuberosity and cuff repair was treated with a reverse total shoulder)

 

rotator cuff tear arthropathy, rheumatoid arthritis, failed anatomic arthroplasties, arthritis with glenoid bone deficiency, fractures and post traumatic arthritis (as shown in the example below - not that cement was required because the humeral shaft did not allow a secure press fit) 


 


There are several important failure modes after reverse total shoulder. Infection is one of the more common and is probably related to the fact that many reverse total shoulders are performed as revisions after multiple prior surgeries coupled with the dead space created when the humerus is displaced distally by the procedure. As with anatomic shoulders, Propionibacterium is a frequently cultured organism from failed reverse total shoulders, which can present with loosening in the absence of the usual clinical signs of infection 

The infection with Propionibacterium in the x-ray on the left was treated with a single stage exchange to a long stem prosthesis. The patient is currently asymptomatic six years after the revision. 



Instability can result from falls, suboptimal component selection, component malposition, bulky tissues in the posterior shoulder, leverage of the humeral component against the glenoid , or lack of sufficient compressive effect by the deltoid. 

 



Early closed reduction can be successful. Recurrent or chronic instability may require surgical revision. The case below shows a failed anatomic prosthesis for fracture with anterosuperior escape that was treated with a reverse that dislocated recurrently. 

 

 The prosthesis was revised to a hemiarthroplasty that was unsatisfactory. Finally a successful revision was accomplished by the removal of posterior scar tissue and revision to a reverse with a 40 mm set of components.
 
Shown below is another example where stability was restored by changing to a larger diameter of curvature and increasing the thickness of the polyethylene and humeral cup.

 


The risk of humeral fracture is increased in revision surgery, by falls and when the humeral component fixation results in an abrupt transition between a cemented or press fit diaphyseal stem tip and osteopenic bone distal to the prosthetic tip These fractures deserve a trial at closed management.

 

in that surgical revision can be very complex

 

Scapular and acromial fractures can result from excessive deltoid tension producing a fatigue fracture or from bone weakened by screw placement. These fractures are preferably treated non-operatively.

Scapular notching is a prominent complication, particularly common in prosthetic designs that medialize the humerus or when the glenoid component is positioned high on the glenoid bone.

 


The issues with notching are not so much the ‘notch’ in the scapula but the radiographically unseen damage to the polyethylene of the humeral component


 and to glenoid component fixation 



Notching may also be associated with unwanted bone formation that limits the range of motion 


Humeral component failure may result from dissociation of the cup from the stem



Glenoid failure may result from glenosphere-baseplate dissociation,


glenoid fracture,


or failure of fixation


While some cases can be reconstructed, others require salvage conversion to a hemiarthroplasty after glenoid component removal; the clinical results of this conversion are generally poor.

Neurologic lesions can result from dissection, retraction or over lengthening of the arm. Finally, there has been some concern about loss of active external rotation with reverse total designs that medialize the tuberosity, prompting consideration of latissimus dorsi transfers; this problem seems less of an issue with those designs that maintain ‘East-West” tensioning of the residual cuff posteriorly.

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You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'


Will I be able to return to hang gliding after my bilateral open repairs for shoulder dislocation?

While repairs for shoulder instability are no longer a major part of our practice, we still receive follow-ups from folks from years back. One interesting cases is that of a physician in his late 40's who had bilateral shoulder dislocations that were a problem - especially when he landed his hang glider. He had bilateral open Bankart repairs. It is great to see him catch a thermal at the end of this video clip.


video

This is what you'd like to avoid if you are a hang glider - an inflight dislocation!


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Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'


Reverse total shoulder technique

The surgical keys to a successful reverse total shoulder arthroplasty are (1) immediate secure glenoid and humeral component fixation, (2) absence of unwanted contact between the medial proximal humeral component and the scapula, (3) preservation of humeral and glenoid bone stock, (4) stability throughout the range of motion, and (5) a functional range of motion.

The patient positioning, anesthetic, prophylactic antibiotics, skin preparation, and skin and subscapularis incision are identical to those for an anatomic arthroplasty. A deltopectoral approach is used with careful attention to protect the deltoid and the axillary nerve. Care is taken to identify, preserve and protect the subscapularis. The intrinsic stability of the reverse arthroplasty allows the adhesions and scar tissue to be completely removed. In that anterior instability can be a complication, it is important to perform sufficient posterior soft tissue releases to accommodate the prosthesis and prevent unwanted anterior pressure on the back of the humeral component. This can be a particular challenge in revision of anteriorly unstable anatomic prostheses and in small individuals. It is also important to release the contracted inferior capsule, which is frequently present when the humerus has been chronically displaced upwards.


In performing the humeral resection, three priorities exist: (1) leaving as much of the tuberosities as possible for rotational control of the prosthesis, (2) resecting enough bone so that the glenoid arthroplasty can be done well, and (3) enabling reconstruction at the proper length. We begin with a very conservative cut to keep our options open. Osteophytes and other unwanted bony prominences are removed. 


Further humeral preparation is delayed until after the glenoid arthroplasty to avoid weakening the humerus and risking fracture during the glenoid part of the arthroplasty.

A complete circumferential release of the soft tissues from around the glenoid allows excellent visualization. The glenoid is curetted free of cartilage and the inferior lip of the glenoid fossa is smoothed so that it is flush with the glenoid face. The starting point for the glenoid drill is selected so that the base plate will cover the inferior glenoid where the best bone support exists. Excessive inferior positioning of the glenosphere is avoided. While some advocate an inferior inclination of the glenoid, we prefer to orient the baseplate squarely on the face of the glenoid to optimize the quality and quantity of the bone supporting the baseplate; minimal glenoid reaming allows for the preservation of the denser bone at the glenoid surface.

The glenoid bone surface is reamed by hand only to the point where the surface is flat,  minimizing the removal of the important subchondral cortex.


The baseplate is fixed securely using the central screw that engages the strong bone of the subscapularis fossa.

After the peripheral screws are inserted, it is critical to remove all bone from around the periphery of the base plate once it is inserted. Special reamers may be helpful in this regard, but it is still essential to verify that the entire baseplate is clear.


Our default glenosphere is the 36 neutral and it is usually inserted at this point of the procedure.


Once the glenosphere is inserted and vigorously impacted into place, traction and rotation are applied using the insertion handle to assure that the Morse taper of the glenosphere has securely engaged the baseplate.



Attention is then directed to the humerus. The medullary canal is conservatively reamed to remove cancellous but retain cortical bone. The humeral metaphysis is reamed to 42 mm to accommodate the metaphyseal aspect of the humeral component 


A trial component is inserted to assure that reduction can be accomplished, that the joint is stable, and that there is no unwanted contact between the prosthesis and the scapula. Impaction grafting is carried out with an impactor of the same size and shape of the monoblock humeral component.


Drill holes are placed in the lesser tuberosity for reattachment of the subscapularis if sufficient tendon is available. The wound is thoroughly irrigated. The humeral prosthesis is driven into the impaction grafted canal, assuring a snug fit and rotational stability.


The joint is reduced; range of motion and stability are again verified. The subscapularis is repaired to the previously placed sutures. A standard wound closure is followed by the application of dry sterile dressings. 

Postoperative rehabilitation consists of the use of a sling for comfort and support for 6 weeks. Gentle activities of daily living are allowed during this period. After six weeks progressive increase in active use of the shoulder is encouraged; stretching exercises are usually unnecessary.

Here are the post operative radiographs from two case examples of the technique.


 

 


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Reverse total shoulder - choosing a prosthesis

The reverse total shoulder is considered for shoulders with pseudoparalysis and anterosuperior escape – findings that are evident on physical examination and often on plain x-rays.





The reverse total shoulder, like the anatomic total shoulder, achieves stability by concavity compression. The glenoid component manages the compressive force applied to it by a combination of compressive and tensile loading of the glenoid bone. As long as the net glenohumeral joint reaction force is contained within the humeral socket, the articulation is stable.



 If the net glenohumeral joint force is not contained within the humeral socket, the joint is unstable.




The ideal implant (1) enables a relatively anatomic reconstruction in contrast to those that result in distal displacement of the humerus with the associated increased risk of fracture of the acromion (shown below)


or neurologic injury from lengthening the arm; (2) preserves glenoid bone stock; (3)  provides immediate glenoid fixation with a screw that engages the cortex of the subscapularis fossa compressing the baseplate against the prepared glenoid bone without having to wait for tissue ingrowth; (4) has enough lateral offset to prevent unwanted contact between the medial aspect of the humeral component and the glenoid without the need for bone graft interposed between the baseplate and the glenoid to achieve this offset;  and (5) allows for fixation of a monoblock humeral stem with impaction graftingavoiding the stress riser that would otherwise exist between the end of the cement or press fit stem tip and the often weak bone distal to that point (as shown below)



and obviating the risk of failure at the juncture between the metaphyseal and diaphyseal parts of the humeral implant (as shown below).



So this is the type of reverse prosthesis that we find most attractive.


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Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'