Diego Soza MD1, Montserrat García‐Portabella MD2, Lledó Batalla MD2 and Josep Massons MD PhD3 1Orthopaedic Surgery and Traumatology Department, Vall d’Hebron Hospital, Barcelona, Spain 2Clínica Corachan, Barcelona, Catalonia, Spain 3Vall d’Hebron University Hospital, Barcelona, Catalonia, Spain Shoulder arthroplasty is a widely used procedure. In the United States, the frequency of both primaries and revisions are continually increasing.1,2 As with most orthopedic interventions, preoperative planning is essential to achieving favorable results in shoulder arthroplasty.3 In arthroplasty, restoration of correct alignment is the primary objective. When correction of the glenoid version is not achieved, the risk of posterior humeral head displacement increases, causing asymmetric wear of the polyethylene (PE)4 and consequent risk of prosthetic loosening.5–10 Abnormal glenoid morphologies have been well described. In most cases, glenoid bone loss is multiplanar, requiring correction in more than one plane. However, to simplify surgical pre‐planning, it is useful to classify these morphologies by the characteristics of the predominant glenoid loss. Four basic patient profiles, with four corresponding deficit patterns, have been described.11 The first of these profiles is the osteoarthritic patient with a horizontal defect, as described and classified by Walch et al.12 The second is the patient with inflammatory arthritis, with a central defect and secondary joint‐line medialization, as described by Lévigne and Franceschi.13 The third is the patient with cuff‐tear arthropathy (CTA) with a vertical‐plane defect, as described and classified by Lévigne et al.14 The fourth profile is the patient who requires revision surgery, with a combined and irregular defect pattern, as described and classified by Williams and Iannotti.15 In cases of glenoid bone loss with secondary retroversion or inclination, it can be difficult to achieve correct orientation, increasing the risk of premature loosening.16 For this reason, careful evaluation of bone stock, glenoid version, and inclination is imperative for achieving proper glenoid component implantation. Literature addressing investigations into shoulder arthroplasty preoperative planning is widely varied, offering only level III–V evidence. Most papers describe case series or cohort studies. No randomized trials have been reported. Despite the value of the latest imaging technologies, plain x‐ray images remain necessary for preoperative planning.17 There are several useful projections: In planning revision surgeries, it can be helpful to have radiographs of both the glenohumeral joint and the entire humerus, in order to appreciate shortening or medialization at the glenohumeral joint level.19 The CT is considered the gold standard for the imaging of bone defects. It offers extensive information on both inclination of the glenoid surface and possible bone defects. However, despite the advantages a CT can offer, potential variability has been described regarding measurements obtained by this system, as a function of scapular rotation in the coronal plane.20 Seidl et al. described the importance of obtaining images in the scapular plane, to execute an accurate study of the glenoid surface.11 In an effort to avoid variability, corrective systems have been described, based on the main plane of the scapula. Friedman et al. studied 20 shoulders in 13 patients (10 with osteoarthritis, 10 with inflammatory arthritis). Their study compared these 20 shoulders with 63 controls. They defined the transverse axis of the scapula as a line drawn from the midpoint of the glenoid fossa to the medial end of the scapula.21 Use of 3D CT for preoperative planning has been validated, both in clinical and cadaver studies.22–25 This system allows deeper study of glenoid morphology, inclination, version, and available bone stock. Preoperative planning using 3D reconstruction has been shown to improve the precision of implant orientation.3 Glenohumeral stability is determined by dynamic compressive forces of the humeral component on the glenoid component. Minor displacements of as little as 2.5° can lead to subluxation of the humeral component.26 Failure in correction of glenoid version, with a retroversion of >15°, may lead to osteolysis, posterior translation of the humeral head, and eccentric PE wear of the prosthesis.27 There are multiple options for managing glenoid retroversion secondary to bone defect, depending on defect location and type. These therapeutic options can be grouped generally as: implantation of an anatomical prosthesis, implantation of an inverted prosthesis, associating such implants with eccentric reaming, augmented or personalized implants, and resorting to bone grafts. Careful consideration of the potential benefits and disadvantages of each option is essential to arriving at a customized decision for each patient. Before addressing rTSA, it is necessary to outline the other treatment alternatives. There is no clear consensus on the optimal management of retroversion in this patient profile. One of the most frequently chosen options for patients with relatively minor retroversion is eccentric reaming. However, the technique has many detractors. Gillespie and colleagues concluded that in the presence of a retroversion of greater than 15° the probability of successful correction was 50%.28 Subchondral bone reduction can increase the risk of implant loosening, as well as the risk of excessive medialization.11,29–32 Other authors, however, argue that this is a good option when retroversion is minor. Nyffeler et al. reported favorable results, with a good capsulolabral release and adequate mobilization of the musculotendinous subscapularis unit.18 Augmented or customized implants have been proposed as an alternative to eccentric reaming or bone grafting. Studies to date report controversial results. Sabesan and colleagues report favorable corrections of glenoid retroversion with augmented implants, in cases of less than 16°. When retroversion is greater than 16°, the same authors recommend the use of bone grafts.30 They concur with the view that it is a difficult and demanding technique. Incorrect implantation can foster a predisposition to micro‐movements and consequent loosening.30,33 The quality of the literature on appropriate investigations into rTSA for glenoid loss management is widely varied, and offers only level IV–V evidence. The majority of outcome papers are case series or retrospective cohort studies. There are no randomized trials reported. The usefulness of rTSA in treatment of osteoarthritis in the context of CTA has been widely described.34–36
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Management of Glenoid Bone Loss
Clinical scenario
Top three questions
Question 1: In patients with glenoid bone loss, does computed tomography (CT), compared to other imaging modalities, perform better diagnostically?
Rationale
Clinical comment
Available literature and quality of evidence
Findings
Plain radiography
Computerized tomography (CT)
Three‐dimensional computed tomography (3D CT)
Resolution of clinical scenario
Question 2: In patients with glenohumeral bone loss, does reverse total shoulder arthroplasty (rTSA), compared to other treatment options, result in better outcomes?
Rationale
Clinical comment
Eccentric reaming and implantation of anatomical prosthesis
Augmented or customized implants
Available literature and quality of evidence
Findings
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