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Novel Solution for Massive Glenoid Defects in Shoulder Arthroplasty: A Patient-Specific Glenoid Vault Reconstruction System

Am J Orthop. 2017 March;46(2):104-108

Complex glenoid deformities present the most difficult challenges in shoulder arthroplasty. These deformities may be caused by severe degenerative or congenital deformity, posttraumatic anatomy, tumor, or, in most cases, bone loss after glenoid failure in anatomical total shoulder arthroplasty. Methods of treating severe bone loss have included inlay and onlay bone-graft options with augmented fixation and, in severe cases, salvage hemiarthroplasty with limited goal expectations. Unfortunately, none of these methods has provided consistently satisfactory reproducible results. In fact, each has had high rates of failure and complications. Borrowing from hip and knee arthroplasty surgeons’ experience in using CAD/CAM (computer-aided design/computer-aided manufacturing) patient-specific implants to fill significant bony defects, Dr. D. M. Dines developed a glenoid vault reconstruction system (VRS) in conjunction with the Comprehensive Shoulder Arthroplasty System (Zimmer Biomet) to treat severe glenoid bone deficiency. The VRS is patient-specific; each case involves making a preoperative plan based on 3-dimensional reconstruction of a 2-dimensional computed tomography scan. The patient-specific implant and instrumentation that are created are used to reconstruct the deformed glenoid in an anatomical position without the need for additional bone graft. In this article, we describe the implant and its indications, technical aspects of production, and surgical technique.

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References

1. Walch G, Badet R, Boulahia A, Khoury A. Morphologic study of the glenoid in primary glenohumeral osteoarthritis. J Arthroplasty. 1999;14(6):756-760.

2. Chan K, Knowles NK, Chaoui J, et al. Characterization of the Walch B3 glenoid in primary osteoarthritis [published online January 11, 2017]. J Shoulder Elbow Surg. doi:10.1016/j.jse.2016.10.003.

3. Bercik MJ, Kruse K 2nd, Yalizis M, Gauci MO, Chaoui J, Walch G. A modification to the Walch classification of the glenoid in primary glenohumeral osteoarthritis using three-dimensional imaging. J Shoulder Elbow Surg. 2016;25(10):1601-1606.

4. Sears BW, Johnston PS, Ramsay ML, Williams GR. Glenoid bone loss in primary total shoulder arthroplasty: evaluation and management. J Am Acad Orthop Surg. 2012;20(9):604-613.

5. Kocsis G, Thyagarajan DS, Fairbairn KJ, Wallace WA. A new classification of glenoid bone loss to help plan the implantation of a glenoid component before revision arthroplasty of the shoulder. Bone Joint J. 2016;98(3):374-380.

6. Antuna SA, Sperling JW, Cofield RH, Rowland CM. Glenoid revision surgery after total shoulder arthroplasty. J Shoulder Elbow Surg. 2001;10(3):217-224.

7. Seebauer L, Walter W, Keyl W. Reverse total shoulder arthroplasty for the treatment of defect arthropathy [in English, German]. Oper Orthop Traumatol. 2005;17(1):1-24.

8. Iannotti JP, Frangiamore SJ. Fate of large structural allograft for treatment of severe uncontained glenoid bone deficiency. J Shoulder Elbow Surg. 2012:21(6):765-771.

9. Hill JM, Norris TR. Long-term results of total shoulder arthroplasty following bone-grafting of the glenoid. J Bone Joint Surg Am. 2001;83(6):877-883.

10. Steinmann SP, Cofield RH. Bone grafting for glenoid deficiency in total shoulder replacement. J Shoulder Elbow Surg. 2000;9(5):361-367.

11. Hsu JE, Ricchetti ET, Huffman GR, Iannotti JP, Glaser DL. Addressing glenoid bone deficiency and asymptomatic posterior erosion in shoulder arthroplasty. J Shoulder Elbow Surg. 2013;22(9):1298-1308.

12. Gunther SB, Lynch TL. Total shoulder replacement surgery with custom glenoid implants for severe bone deficiency. J Shoulder Elbow Surg. 2012;21(5):675-684.

13. Chammaa R, Uri O, Lambert S. Primary shoulder arthroplasty using a custom-made hip-inspired implant for the treatment of advanced glenohumeral arthritis in the presence of severe glenoid bone loss. J Shoulder Elbow Surg. 2017;26(1):101-107.

Take-Home Points

With more shoulder arthroplasties being performed on younger patients, we can expect more revisions in the future.
Many of these revision cases will have profound glenoid bone loss.
Bone grafting the glenoid defects in shoulder arthroplasty has been less successful especially with significant vault defects.
Based on the CAD-CAM success in total hip and knee replacement surgery, a patient-specific glenoid vault reconstruction system has been developed by Zimmer Biomet to deal with profound glenoid bone loss and cuff insufficiency.
Early results of this vault reconstruction system have been promising in these most difficult clinical situations.

Early results of this vault reconstruction system have been promising in these most difficult clinical situations. Complex glenoid deformities present the most difficult challenges in shoulder arthroplasty (SA). These deformities may be caused by severe degenerative or congenital deformity, posttraumatic anatomy, tumor, or, in most cases, bone loss after glenoid failure in anatomical total SA.

Walch and colleagues¹ described the pathologic glenoid lesions seen in progressive degenerative arthritis and some congenital defects. The most severe were initially characterized as Walch B2 and Walch C deformities. These lesions have been further classified to include Walch B3 posteroinferior glenoid deformities.^2,3 Each of these deformities can result in severe glenoid vault deficiency.

In some revision cases and in severe rheumatoid cases, these deformities can present as cavitary lesions with or without failure of the glenoid rim or wall resulting in significant compromise of glenoid vault lesions.^4,5 In these cases, the degree of “medialization” of the native glenohumeral joint line and the amount of peripheral bone loss can have profound effects on the amount of bone available for fixation and on the ability to allow component positioning for best surgical and biomechanical outcomes.

Other bone loss deformities, which have been described by Antuna and colleagues⁶ and Seebauer and colleagues,⁷ often accompany disease processes with severe cuff deficiency. These deformities historically have been treated with intercalary-type bone grafts in 1- or 2-stage revision of reverse SA or in salvage to hemiarthroplasty. Treatment of these pathologies with the technique described produced only fair results in short-term to midterm follow-up. The most commonly reported complications have been component loosening, bone graft failure, infection, and instability.^8-11Borrowing from hip and knee arthroplasty surgeons’ experience in using CAD/CAM (computer-aided design/computer-aided manufacturing) patient-specific implants to fill significant bony defects, Dr. D. M. Dines and Dr. Craig developed a patient-specific glenoid vault reconstruction system (VRS) in conjunction with the Comprehensive Shoulder Arthroplasty System (Zimmer Biomet). For a number of years, the Food and Drug Administration allowed this patient-specific glenoid VRS component to be made available only as a custom implant. Recently, however, full 510K clearance was granted to use the VRS in reverse SA patients with severe soft-tissue deficiency and significant glenoid bone loss.

In this article, we describe the implant and its indications, technical aspects of production, and surgical technique.

Vault Reconstruction System

Severe glenoid bone loss often requires an implant that specifically matches the patient’s anatomy. The patient-specific glenoid VRS (Figure 1) is made from a 3-dimensional reconstruction of a 2-dimensional computed tomography image.

CAD/CAM reconstruction allows for preoperative planning, visualization, and development of patient-specific implants. The patient-specific images used for the glenoid VRS detail implant position, orientation, and size to create a more normal glenohumeral center of rotation. The model allows for the planning, placement, size, and trajectory of the central and peripheral screws, ensuring the best possible fixation (Figures 2A, 2B).

Most important, the model is used to create patient-matched implants that fill bone voids with porous plasma spray–coated titanium, which provides high strength and flexibility and allows for biological fixation. This system can accommodate a bone loss envelope of about 50 mm × 50 mm × 35 mm based on evaluation of all implants created in the custom scenario.

In some cases in which the bone is sufficient to enhance fixation in the deficient glenoid vault, a custom boss may be added to the implant, as well as a custom guide matching the implant.

The implant model, the bone model, and the custom boss reaming guide are all constructed from a sterilizable material and are intended to be single-use disposable instruments as well as tools for the initial plan review (Figures 3A, 3B).

Glenoid Exposure

In most cases of severe glenoid bone loss, the associated soft-tissue deficiency allows for easier glenoid exposure. In this implant system, however, maximal peripheral en face exposure of the glenoid is required. In addition, it is mandatory to avoid disturbing the remaining glenoid bone surfaces, which often are thin or fragile, because the patient-specific implant is referenced to this anatomy. Bone that is not maintained changes the orientation of the patient-specific guide and ultimately the fixation of the component. Using the correct retractors and meticulously excising soft-tissue scar tissue are crucial for success.

Novel Solution for Massive Glenoid Defects in Shoulder Arthroplasty: A Patient-Specific Glenoid Vault Reconstruction System

References

Take-Home Points

Vault Reconstruction System

Glenoid Exposure

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