Fuente
Este artículo es originalmente publicado en:
http://shoulderarthritis.blogspot.mx/2015/05/reverse-total-shoulder-results-and.html?utm_source=twitterfeed&utm_medium=twitter
De:
Frederick A. Matsen III, M.D.
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.
