In the revision setting, after removal of an existing humeral component, proximal humeral bone loss may result. Such loss may result in early loosening of a revision prosthesis. Dr Mark Frankle and co-authors have reported on the favorable impact of a prosthesis-allograft composite in such cases when proximal humeral bone loss extends beyond the area of the normal rotator cuff insertion. This article is attached below. Restoring this bone can facilitate cuff reattachment, and diminish risk of loosening.
A previous cement mantle is often encountered in the revision setting, and when there is proximal humeral bone loss this mantle may need to be removed to facilitate placement and cementation of a long-stem implant. Alternatively, a proximal humeral allograft may be used to
provide sufficient structural and rotational support for the humeral component. In the absence of infection, the allograft prosthesis composite can be cemented within the preexisting cement mantle in the proximal part of the humerus and serves to lateralize the line of pull of the deltoid muscle. This increases the total resultant force of the deltoid as a pulley and provides additional bone stock should future reconstructions become necessary. Additionally, the allograft serves to maintain the height of the prosthesisbone construct, thus helping to optimize deltoid tension. In patients with poorly compliant soft tissue, however, the addition of an allograft may overtension the available soft-tissue envelope and should not be used.
Moving to the glenoid----glenoid bone loss continues to present a challenge in shoulder arthroplasty. Much of the literature
regarding glenoid bone loss has been in the setting of conventional, unconstrained total shoulder arthroplasty, for which various strategies for glenoid component reimplantation have been described. The consequences of not accounting for glenoid bone loss during reverse shoulder arthroplasty implantation have been linked to compromised outcomes as well. I have attached a recent article from Dr mark Frankle et al which has advanced the way we manage glenoid defects during Reverse shoulder arthroplsty This, also, is one indication for electing to use the DJO RSP design as opposed to a classic "Grammont" design---since the screww fixation allows one to select a spine centerline as opposed to a classic centerline perpendicular to the face of the glenoid. Outcomes in Dr Frankle's report below were satisfactory even with defects--this may be due to several factors inherent in the reverse shoulder arthroplasty design that increase the constraint of the shoulder relative to that of an anatomic total shoulder replacement and
make stability and proper soft-tissue tension attainable. Greater surface contact area between the glenosphere and socket in conjunction with the reversal of the articulation neutralizes the destabilizing force of the deltoid. This neutralization enables the baseplate to be relatively anteverted in
order to accommodate for glenoid bone loss. Despite this anteversion, no shoulder had a dislocation. Additionally, in the setting of acquired
glenoid bone defects, initial fixation of the baseplate is of paramount importance in the surgeon’s ability to successfully implant a glenoid component. By implanting the baseplate in the scapular body along the spine centerline, it is possible toachieve stable fixation even when bone loss is present. However, preoperative identification of the level and location of bone loss is an important part of surgical planning. Identification of glenoid bone defects on standard shoulder radiographs should prompt further imaging, including a computed tomography scan with three-dimensional reconstruction. These images can help to guide placement of the central screw (the central axis of the baseplate) into adequate
bone for initial fixation. Both the standard glenoid centerline and spine centerline axis should be identified and the proper alignment selected for the baseplate to allow for maximal central screw fixation. Additionally, identification of segmental bone loss, which may prevent sufficient contact with the backside of the baseplate, can be anticipated preoperatively.
A previous cement mantle is often encountered in the revision setting, and when there is proximal humeral bone loss this mantle may need to be removed to facilitate placement and cementation of a long-stem implant. Alternatively, a proximal humeral allograft may be used to
provide sufficient structural and rotational support for the humeral component. In the absence of infection, the allograft prosthesis composite can be cemented within the preexisting cement mantle in the proximal part of the humerus and serves to lateralize the line of pull of the deltoid muscle. This increases the total resultant force of the deltoid as a pulley and provides additional bone stock should future reconstructions become necessary. Additionally, the allograft serves to maintain the height of the prosthesisbone construct, thus helping to optimize deltoid tension. In patients with poorly compliant soft tissue, however, the addition of an allograft may overtension the available soft-tissue envelope and should not be used.
Moving to the glenoid----glenoid bone loss continues to present a challenge in shoulder arthroplasty. Much of the literature
regarding glenoid bone loss has been in the setting of conventional, unconstrained total shoulder arthroplasty, for which various strategies for glenoid component reimplantation have been described. The consequences of not accounting for glenoid bone loss during reverse shoulder arthroplasty implantation have been linked to compromised outcomes as well. I have attached a recent article from Dr mark Frankle et al which has advanced the way we manage glenoid defects during Reverse shoulder arthroplsty This, also, is one indication for electing to use the DJO RSP design as opposed to a classic "Grammont" design---since the screww fixation allows one to select a spine centerline as opposed to a classic centerline perpendicular to the face of the glenoid. Outcomes in Dr Frankle's report below were satisfactory even with defects--this may be due to several factors inherent in the reverse shoulder arthroplasty design that increase the constraint of the shoulder relative to that of an anatomic total shoulder replacement and
make stability and proper soft-tissue tension attainable. Greater surface contact area between the glenosphere and socket in conjunction with the reversal of the articulation neutralizes the destabilizing force of the deltoid. This neutralization enables the baseplate to be relatively anteverted in
order to accommodate for glenoid bone loss. Despite this anteversion, no shoulder had a dislocation. Additionally, in the setting of acquired
glenoid bone defects, initial fixation of the baseplate is of paramount importance in the surgeon’s ability to successfully implant a glenoid component. By implanting the baseplate in the scapular body along the spine centerline, it is possible toachieve stable fixation even when bone loss is present. However, preoperative identification of the level and location of bone loss is an important part of surgical planning. Identification of glenoid bone defects on standard shoulder radiographs should prompt further imaging, including a computed tomography scan with three-dimensional reconstruction. These images can help to guide placement of the central screw (the central axis of the baseplate) into adequate
bone for initial fixation. Both the standard glenoid centerline and spine centerline axis should be identified and the proper alignment selected for the baseplate to allow for maximal central screw fixation. Additionally, identification of segmental bone loss, which may prevent sufficient contact with the backside of the baseplate, can be anticipated preoperatively.
