Humeral bone deficiencies can contribute both to instability of the joint and to instability of fixation of the revision implant.
1. Joint instability
The stability of the reverse total shoulder depends on concavity compression: the compression of the glenosphere into the concavity of the humeral liner by the deltoid and other scapulohumeral muscles.
Post-revision glenohumeral instability of the reverse total shoulder can be caused by inadequate restoration of humeral length and/or soft tissue attachments to the proximal humerus. Loss of humeral length reduces the tension in the deltoid, and thereby decreases its ability to provide the compressive force that stabilizes the joint. Compromised insertions of subscapularis, coracobrachialis, latissimus dorsi / teres major and pectoralis major can also contribute to insufficient joint compression.
2. Implant instability.
Instability of the humeral component is often manifested by inadequate rotational stability of the implant in the humerus. The non-circular cross section of the metaphyseal canal provides the best opportunity for obtaining rotational stability.
Some of the steps that are helpful in optimizing (1) the stability of the joint and (2) the stability of the humeral component in revision reverse total shoulder include
1. Assessing the quantity, quality and pathoanatomy at each level of the humeral bone.
Humeral Bone Loss in Revision Total Shoulder Arthroplasty: the Proximal Humeral Arthroplasty Revision Osseous Insufficiency (PHAROS) Classification System characterized the bone loss in three regions (epiphysis (1), metadiaphysis above the deltoid insertion (2), and diaphysis below the deltoid insertion (3)) as well as the bone quality in terms of cortical thinning of greater (A) or less than 50% (B) of the expected thickness. Epiphyseal bone loss can isolated compromise of the medial calcar (C) or greater tuberosity (G).
Some examples are shown below. The authors recommend that grade 2B and 3 bone loss be treated with allograft-prosthetic composites (APC) or a humeral replacement mega-prosthesis.
2) Determining whether residual cement is securely attached to bone and of possible use of cement-within-cement fixation of a new humeral implant
The example below shows an intact cement mantle without radiographic signs of loosening at the bone-cement interface. The revision was performed with a cement-in-cement revision and resulted in stable fixation at 4 years after surgery.
The example below shows a cement mantle fracture and radiolucency at the bone-cement interface that raises concern about the applicability of a cement-in-cement revision
3) Evaluation of the risk of infection (serum WBC, ESR, CRP, frozen sections, joint fluid for cell count, frozen sections, as well as submission of tissue explant specimens for culture). Often a course of postoperative antibiotics is used until the results of the intraoperative cultures become available.
4) Restoring humeral length to optimize soft tissue tension
One approach to restoring humeral length is to utilize contralateral films as guide to the desired humeral length as shown below.
Another approach is to determine the added length necessary to restore soft tissue tension as detailed by the authors of Revision Arthroplasty with Use of a Reverse Shoulder Prosthesis-Allograft Composite
5) Achieving secure fixation of the implant to healthy host bone, such as purchase in a length of healthy diaphysis exceeding two cortical diameters (see Evaluation and treatment of postoperative periprosthetic humeral fragility fractures)
6) Assuring robust rotational control of implant, for example through plate fixation of APC to host bone.
7) Retaining or restoring critical soft tissue attachments, such as deltoid, pectoralis major, remaining rotator cuff and subscapularis
Example below from Ben Sharareh, past UW Shoulder Fellow
8) Minimizing stress risers at distal end of APC, especially in osteoporotic bone (avoid ending plate and stem at same level, “protecting the whole bone”). Example below from Jonah Hebert-Davies, UW Shoulder Faculty.
8) Minimizing stress risers at distal end of APC, especially in osteoporotic bone (avoid ending plate and stem at same level, “protecting the whole bone”). Example below from Jonah Hebert-Davies, UW Shoulder Faculty.
9) Optimizing stability of glenohumeral articulation (selection of glenosphere diameter of curvature and lateral offset, tensioning using polyethylene liner of appropriate thickness, avoiding unwanted contact between humerus and scapula (neck, acromion).
The example below shows a glenosphere exchange to a larger diameter, inferior offset at a revision for humeral loosening with massive humeral bone loss. The new glenosphere optimizes soft tissue tension and compression.
Below are some of the relevant articles on revision reverse total shoulder arthroplasty in shoulders with loss of humeral bone.
Below are some of the relevant articles on revision reverse total shoulder arthroplasty in shoulders with loss of humeral bone.
2009 Revision Arthroplasty with Use of a Reverse Shoulder Prosthesis-Allograft Composite recommended allograft-prosthesis composites in cases with humeral defects ranging from 3.5 to 15.0 cm.
2013 Revision surgery of reverse shoulder arthroplasty points to the association of bone loss with humeral loosening, lack of rotational stability, and infection.
2014 The metaphyseal bone defect predicts outcome in reverse shoulder arthroplasty for proximal humerus fracture sequelae found that the clinical outcome was influenced by a metaphyseal bone defect of more than 3 centimeters and degenerative changes of the teres minor.
2016 Long-term analysis of revision reverse shoulder arthroplasty using cemented long stems emphasized the importance of sufficient quantity and quality of distal humeral bone in obtaining fixation with long stem cemented humeral components.
2017 Large diaphyseal-incorporating allograft prosthetic composites: when, how, and why : Treatment of advanced proximal humeral bone loss found that well-fixed humeral stems could be treated with short metaphyseal allografts in most cases. Loose stems required longer diaphyseal-incorporating allografts. Noncemented stems required diaphyseal grafts in most cases, compared to cemented stems which required larger grafts in one-third of cases.
2018 Humeral Bone Loss in Revision Shoulder Arthroplasty indicated proximal humeral allograft for revisions of shoulders with 5 cm or more proximal humeral bone loss).
2019 Clinical outcomes following reverse shoulder arthroplasty-allograft composite for revision of failed arthroplasty associated with proximal humeral bone deficiency: 2- to 15-year follow-up."
2019 Humeral Bone Loss in Revision Total Shoulder Arthroplasty: the Proximal Humeral Arthroplasty Revision Osseous Insufficiency (PHAROS) Classification System divided bone loss into three regions (epiphysis, metadiaphysis above the deltoid insertion, and diaphysis below the deltoid insertion) and bone quality by cortical thinning of greater or less than 50% of the expected thickness. Epiphyseal bone loss is subdivided into isolated compromise of the medial calcar or greater tuberosity. The authors provided radiographic examples of each degree of bone loss.
2023 Humeral bone defects in revision shoulder arthroplasty divided bone loss based on the involvement of five segments of the humerus, as shown below This classification helps accounts for loss of bone in regions of stabilizing muscle attachments.
2023 Humeral bone defects in revision shoulder arthroplasty divided bone loss based on the involvement of five segments of the humerus, as shown below This classification helps accounts for loss of bone in regions of stabilizing muscle attachments.
This post was prepared with the great help and direction from Mihir Sheth, M.D., UW shoulder fellow.
You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link.
Follow on twitter: https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/
Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).
Follow on twitter: https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/
Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).
