A new classification of glenoid bone loss to help plan the implantation of a glenoid component before revision arthroplasty of the shoulder

A scapular statistical shape model can reliably predict premorbid glenoid morphology in conditions of severe glenoid bone loss

BACKGROUND

Knowledge of premorbid glenoid parameters at the time of shoulder arthroplasty, such as inclination, version, joint line position, height, and width, can assist with implant selection, implant positioning, metal augment sizing, and/or bone graft dimensions. The objective of this study was to validate a scapular statistical shape model (SSM) in predicting patient-specific glenoid morphology in scapulae with clinically relevant glenoid erosion patterns.

METHODS

Computed tomography scans of 30 healthy scapulae were obtained and used as the control group. Each scapula was then virtually eroded to create 7 erosion patterns (Walch A1, A2, B2, B3, D, Favard E2, and E3). This resulted in 210 uniquely eroded glenoid models, forming the eroded glenoid group. A scapular SSM, created from a different database of 85 healthy scapulae, was then applied to each eroded scapula to predict the premorbid glenoid morphology. The premorbid glenoid inclination, version, height, width, radius of best-fit sphere, and glenoid joint line position were automatically calculated for each of the 210 eroded glenoids. The mean values for all outcome variables were compared across all erosion types between the healthy, eroded, and SSM-predicted groups using a 2-way repeated measures analysis of variance.

RESULTS

The SSM was able to predict the mean premorbid glenoid parameters of the eroded glenoids with a mean absolute difference of 3° ± 2° for inclination, 3° ± 2° for version, 2 ± 1 mm for glenoid height, 2 ± 1 mm for glenoid width, 5 ± 4 mm for radius of best-fit sphere, and 1 ± 1 mm for glenoid joint line. The mean SSM-predicted values for inclination, version, height, width, and radius were not significantly different than the control group (P > .05).

DISCUSSION

An SSM has been developed that can reliably predict premorbid glenoid morphology and glenoid indices in patients with common glenoid erosion patterns. This technology can serve as a useful template to visually represent the premorbid healthy glenoid in patients with severe glenoid bony erosions. Knowledge of the premorbid glenoid preoperatively can assist with implant selection, positioning, and sizing.

Yoke procedure as a salvage treatment option for failed reverse total shoulder arthroplasty with irreconstructible glenoid

BACKGROUND

Glenoid bone loss is a known challenge in primary and revision reverse total shoulder arthroplasty. In severe deficiency, even placing the baseplate in alternative centerline or using an augmented baseplate may be insufficient. This study reports on the use of a soft tissue resurfacing technique using Achilles tendon allograft, coined Yoke procedure, for salvage treatment of glenoid deficient shoulder requiring reconstruction.

MATERIALS AND METHODS

All patients who underwent the Yoke procedure between 2014 and 2020 by a single surgeon at a single academic center were identified and had their charts retrospectively reviewed. Demographics and surgical information were recorded. Preoperative X-rays and 3D-computed tomography scans were reviewed to classify patient glenoid types, evaluate glenoid medialization, and measure shoulder angles. Preoperative and postoperative range of motions and patient-reported outcome scores were evaluated, including anterior elevation, external rotation, internal rotation, visual analog scale, subjective shoulder value score, Simple Shoulder Test, and American Shoulder and Elbow Surgeons (ASES) scores. Postoperative radiographs and follow-up notes were reviewed to evaluate postoperative complication profiles at 1 year.

RESULTS

Seven patients with a median age of 69 years (range, 54-77 years) underwent Yoke procedure and had a median 12-month follow-up (range, 9-56 months). All patients were female and had a median of 2 prior shoulder surgeries (range, 0-13). Of all the patients, the most common comorbidity was osteoporosis (6) followed by rheumatoid arthritis (3). Of the 5 patients who had previous arthroplasty, the most common indications were baseplate failure (4), followed by instability (3) and infection (3). The median visual analog scale score improved from 8 (range, 3-9) to 2 (range, 1-4). The median Simple Shoulder Test improved from 8% (range, 0%-42%) to 33% (range, 17%-83%). The median ASES score improved from 15 (range, 5-38) to 52 (range, 40-78). The median anterior elevation and external rotation improved from 20° (range, 0°-75°) to 100° (range, 40°-145°) and 10° (range, 0°-20°) to 20° (range, 0°-55°), respectively. There was no change in median internal rotation. As of the last follow-up, one patient reported postoperative complications of anterior-superior implant escape, heterotopic ossification, and scapular notching.

CONCLUSION

The Yoke procedure is a promising salvage treatment that can offer patients consistent pain reduction and moderate functional improvements at short-term follow-up. In the setting of poor bone quality and severe glenoid deficiency, glenoid baseplate implantation may not be absolutely necessary for a pain-relieving, functionally acceptable outcome.

Pyrocarbon hemiprostheses show little glenoid erosion and good clinical function at 5.5 years of follow-up

BACKGROUND

The success of traditional shoulder hemiarthroplasty (HA) with cobalt-chromium heads is limited by painful glenoid erosion with problematic bone loss. Hemiprostheses with pyrolytic carbon (PyC) heads have shown reduced glenoid erosion in experimental laboratory studies. Few in vivo data are available.

METHODS

We performed a single-center consecutive cohort study of 31 of 34 patients (91%) who underwent PyC HA between September 2013 and June 2018. In 11 of these patients, concentric glenoid reaming was additionally performed. The mean follow-up period was 5.5 years (range, 3.5-7 years). Standardized radiographs were taken, and clinical function (Constant score) and pain (visual analog scale score) were recorded. Anteroposterior radiographs were analyzed according to an established method by 2 independent observers: A line parallel to the superior and inferior glenoid rim was translated to the most medial point of the glenoid surface. A further parallel line was placed on the spinoglenoid notch. The distance between these 2 lines was measured. Measurements were scaled using the known diameter of the implanted humeral head component. To assess eccentric erosion, anteroposterior and axial images were classified according to Favard and Walch, respectively.

RESULTS

Mean medial glenoid erosion measured 1.4 mm at an average of 5.5 years of follow-up. In the first year, 0.8 mm of erosion was observed, significantly more than the average erosion per year of 0.3 mm (P < .001). Mean erosion per year was 0.4 mm in patients with glenoid reaming vs. 0.2 mm in those without reaming (P = .09). An evolution of glenoid morphology was observed in 6 patients, of whom 4 had a progression of the erosion grade. The prosthesis survival rate was 100%. The Constant score improved from 45.0 preoperatively to 78.0 at 2-3 years postoperatively and 78.8 at latest follow-up (5.5 years postoperatively) (P < .001). The pain score on a visual analog scale decreased from 6.7 (range, 3-9) preoperatively to 2.2 (range, 0-8) at latest follow-up (P < .001). There was a weak correlation (r = 0.37) between erosion and pain improvement (P = .039) and no correlation between erosion and change in Constant score (r = 0.06).

CONCLUSION

PyC HA caused little glenoid erosion and a sustained improvement in clinical function in our cohort at mid-term follow-up. PyC demonstrates a biphasic development of glenoid erosion, with a reduced rate after the first year. PyC HA should therefore be considered as an alternative to cobalt-chromium HA and to anatomical total shoulder arthroplasty for patients with a high risk of glenoid component complications.

A review of custom implants for glenoid bone deficiency in reverse shoulder arthroplasty

Reverse Total Shoulder Arthroplasty is being increasingly performed, with indications in both elective and trauma settings. Accordingly, there are an increasing number of revision cases where glenoid bone loss is a concern. There are well recognised surgical techniques for dealing with mild to moderate glenoid wear, including eccentric reaming and impaction grafting. In cases of severe wear or uncontained glenoid defects these may not be suitable, and the surgeon may look to a customised implant to deal with such bone loss. There are several implant manufacturers who currently market and produce patient specific instrumentation and customised glenoid baseplates to achieve the best possible fixation in cases of severe bone loss. This article outlines some examples of custom implants currently available to surgeons, and the process by which they may be procured and used. Implant and surgical considerations, and key aspects of surgical technique are also covered. Literature on outcomes and complications following custom shoulder arthroplasty shows promising results, but at present is limited to relatively small case series with no long-term outcome data.

[Bony glenoid reconstruction in revision arthroplasty]

Glenoid pathologies are one of the main indications for shoulder arthroplasty revisions. In most cases, the glenoid bone defect is associated with insufficiency of the rotator cuff, so that only reverse total shoulder arthroplasty can be considered as a revision implant. For stable permanent fixation of the reverse glenoid component, to avoid inferior glenoid notching, and to achieve optimal function, physiological restoration of three-dimensional glenoid anatomy is necessary. In order to approach the individual glenoid pathologies in a differentiated and optimal manner, it is important to classify the defects. A basic distinction must be made between centric contained and eccentric uncontained defects. Combinations often occur. It is also important to consider the severity, depth, and three-dimensional orientation of the defect. Therefore, a CT analysis of the glenoid is essential preoperatively. The data obtained should serve as the basis for computer-assisted planning to determine the optimal position of the glenoid baseplate and the type and shape of the bone graft for the reconstruction. For patients with good bone quality, we recommend defect reconstruction with autologous iliac crest. The type of graft configuration and fixation and the decision between a one- and two-stage procedure depend on the type and severity of the defect. With technically correct reconstruction and proper prosthesis implantation, sufficient integration of the bone graft and durable fixation of the glenoid component can be expected with satisfactory clinical results. After bony reconstruction of the defects, repeated treatment with a reverse arthroplasty is possible in the long term in the event of renewed glenoid problems.

[Metal glenoid augmentation in revision arthroplasty]

Glenoid implantation in revision arthroplasty of the shoulder remains a technical challenge in the case of severe bone loss. Metal glenoid augmentation and patient-specific glenoid implants represent new treatment options with great potential. Virtual planning techniques allow a differentiated evaluation of the extent of the bone loss and the planning of different augmentation options. Although not clearly defined so far, a patient-specific implant can be indicated if adequate fixation of the base plate in the native bone appears questionable. The planning is carried out with the support of the prostheses manufacturer and the stability is simulated using finite element analysis. A high level of primary stability is achieved by an optimized fitting of the implant into the bony defect. The short-term results are promising. However, in the absence of long-term results and limited options in case of revision, the use of a custom-made glenoid warrants a strict indication.

Clinical and Radiological Outcomes after Total Shoulder Arthroplasty Using Custom-Made Glenoid Components: A Systematic Review

Reverse total shoulder arthroplasty presents itself sometimes as challenging when it comes to addressing massive bone loss, either in primary or revision settings. Custom components recently have made their way into shoulder prosthetics and are meant to help in the case of extensive glenoid bone destruction. Because of strict indication and the fairly recent introduction of these implants, the usage of custom-made glenoid implants is not very common yet. However, the early results are promising. The purpose of this review was to summarize and analyze the available literature. Therefore, a systematic review was performed according to PRISMA guidelines. A comprehensive search of the databases PubMed, Cochrane, and Livivo was performed to screen for studies reporting on clinical and radiological outcomes of custom glenoid implants. Four studies with a total of 46 shoulders were included in this review. The mean patient age was 68.8 years and the mean time of follow-up was 24.3 months. The weighted means showed an increase in CMS (32.7 points), in ASES (39.8 points), in anteversion (67.4 degrees), and in abduction (51.9 degrees) and a decrease in VAS (5.4 points). Custom-made glenoid implants are therefore a viable option in cases of large combined glenoid bone loss, both in primary and revision shoulder arthroplasty.

Functional and Radiological Outcomes after Treatment with Custom-Made Glenoid Components in Revision Reverse Shoulder Arthroplasty

Glenoid implant position and fixation are challenging in severe glenoid defects in reverse total shoulder arthroplasty (rTSA). Custom-made glenoid implants are metal augmented implants that are specially produced for a certain defect. They provide the restoration of the joint line and proper fixation. This retrospective data analysis investigated the clinical and radiological outcomes after revision using custom-made glenoid implants. Between 2018 and 2020, nine patients (10 shoulders) with severe glenoid defects underwent revision rTSA using a custom-made glenoid implant (Materialise Glenius or Lima ProMade). The pre- and postoperative Constant Murley Score (CMS), UCLA Score and Subjective Shoulder Value (SSV) were assessed. Postoperative CT scans and X-rays in two planes were available. The minimum follow-up was 12 months, with a mean follow-up of 23.1 months. The mean preoperative CMS, UCLA Score and SSV were 10.9, 4.1 and 11.0, respectively. The mean postoperative CMS, UCLA Score and SSV showed significant increases of 51.7 (<0.001), 22.9 (<0.001) and 52.0 (<0.001), respectively. There were no signs of loosening implants or scapular notching, and no revision was necessary. This trial showed promising clinical and radiological short-term outcomes for custom-made glenoid components in revision rTSA.

Distal clavicle autograft augmentation for glenoid bone loss in revision shoulder arthroplasty: results and technique

BACKGROUND

Structural bone graft for reconstruction of glenoid bone stock is often necessary in the setting of revision shoulder arthroplasty. This study introduces a new structural autograft technique using the distal clavicle for treatment of glenoid bone loss in the setting of revision shoulder arthroplasty.

METHODS

This is a retrospective, single-surgeon study of patients with significant glenoid bone loss requiring revision shoulder arthroplasty with autologous distal clavicle bone grafting to the glenoid. Twenty patients with failed shoulder arthroplasty who underwent revisions of their glenoid components between 2015 and 2019 were retrospectively identified. Sixteen patients were available with follow-up of greater than 1 year. Patient records and radiographs were reviewed for intraoperative and postoperative complications. Preoperative and postoperative function were evaluated by physical examination and patient-reported outcome surveys.

RESULTS

There were no observed intraoperative complications relating to the distal clavicle autograft harvest or placement. There were no iatrogenic nerve injuries or intraoperative instability. One of the 16 patients developed postoperative loosening and subsequent failure of the glenoid baseplate, requiring revision. One additional patient demonstrated increased elevation of the coracoclavicular interval postoperatively, likely related to the distal clavicle autograft harvest. At a mean follow-up of 25 months, 15 of 16 glenoid implants remained well fixed (93.4%), with no evidence of infection, or impingement demonstrated radiographically or clinically. Average patient age was 69 years at the time of surgery. Forward elevation improved from 76° to 123° at final follow-up (P = .0002). The American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score improved from an average of 35.8 to 67.8 at mean follow-up (P = .001). The visual analog scale score improved from an average of 5.9 to 2 at mean follow-up, though not statistically significant (P = .068). There was no significant change in external rotation following surgery (P = .319).

CONCLUSION

Osteolysis and bone loss of the glenoid poses a challenging problem in revision shoulder arthroplasty. Distal clavicle autograft augmentation is a viable and reproducible technique to manage structural glenoid defects.

Automated quantification of glenoid bone defects using 3-dimensional measurements

BACKGROUND

Assessment of glenoid bone defects is important to select the optimal glenoid component design during shoulder arthroplasty planning and implantation. This study presents a fully automated method to describe glenoid bone loss using 3-dimensional measurements without the need for a healthy contralateral reference scapula.

METHODS

The native shape of the glenoid is reconstructed by fitting a statistical shape model (SSM) of the scapula. The total vault loss percentage, local vault loss percentages, defect depth, defect area percentage, and subluxation distance and region are computed based on a comparison of the reconstructed and eroded glenoids. The method is evaluated by comparing its results with a contralateral bone-based reconstruction approach in a data set of 34 scapula and humerus pairs with unilateral glenoid bone defects.

RESULTS

The SSM-based defect measurements deviated from the contralateral bone-based measurements with mean absolute differences of 5.5% in the total vault loss percentage, 4.5% to 8.0% in the local vault loss percentages, 1.9 mm in the defect depth, 14.8% in the defect area percentage, and 1.6 mm in the subluxation distance. The SSM-based method was statistically equivalent to the contralateral bone-based method for all parameters except the defect area percentage.

CONCLUSION

The presented method is able to automatically analyze glenoid bone defects using 3-dimensional measurements without the need for a healthy contralateral bone.

Characterization of the dysplastic Walch type C glenoid

Aims

The Walch Type C dysplastic glenoid is characterized by excessive retroversion. This anatomical study describes its morphology.

Patients and Methods

A total of 29 shoulders with a dysplastic glenoid were analyzed. CT was used to measure retroversion, inclination, height, width, radius-of-curvature, surface area, depth, subluxation of the humeral head and the Goutallier classification of fatty infiltration. The severity of dysplasia and deficiency of the posterior rim of the glenoid were recorded.

Results

A type C glenoid occurred in 1.8% of shoulders referred to our tertiary centres. The mean retroversion, inclination, height, width, radius-of-curvature, surface area, and depth of the glenoid were 37°, 3°, 46 mm, 30 mm, 37°, 1284 mm3, and 16 mm, respectively. The mean posterior subluxation was 90%. The Goutallier class was < 2 in 25 shoulders (86%). Glenoid dysplasia was mild in four, moderate in 14, and severe in 11 shoulders. The typical appearance of the posterior glenoid rim had a rounded or ‘lazy J’ morphology. The glenoid neck was deficient in 18 shoulders (62%).

Conclusion

A dysplastic Type C glenoid characteristically has a uniconcave retroverted morphology, a deficient posteroinferior rim and scapular neck, and a reduced depth. These findings help to define the unique anatomical variations and may aid the planning of surgery and the development of components for these patients. Cite this article: Bone Joint J 2018;100-B:1074–9.

Virtual reconstruction of glenoid bone defects using a statistical shape model

BACKGROUND

Description of the native shape of a glenoid helps surgeons to preoperatively plan the position of a shoulder implant. A statistical shape model (SSM) can be used to virtually reconstruct a glenoid bone defect and to predict the inclination, version, and center position of the native glenoid. An SSM-based reconstruction method has already been developed for acetabular bone reconstruction. The goal of this study was to evaluate the SSM-based method for the reconstruction of glenoid bone defects and the prediction of native anatomic parameters.

METHODS

First, an SSM was created on the basis of 66 healthy scapulae. Then, artificial bone defects were created in all scapulae and reconstructed using the SSM-based reconstruction method. For each bone defect, the reconstructed surface was compared with the original surface. Furthermore, the inclination, version, and glenoid center point of the reconstructed surface were compared with the original parameters of each scapula.

RESULTS

For small glenoid bone defects, the healthy surface of the glenoid was reconstructed with a root mean square error of 1.2 ± 0.4 mm. Inclination, version, and glenoid center point were predicted with an accuracy of 2.4° ± 2.1°, 2.9° ± 2.2°, and 1.8 ± 0.8 mm, respectively.

DISCUSSION AND CONCLUSION

The SSM-based reconstruction method is able to accurately reconstruct the native glenoid surface and to predict the native anatomic parameters. Based on this outcome, statistical shape modeling can be considered a successful technique for use in the preoperative planning of shoulder arthroplasty.