fbpx
Find a Surgeon
Patient & Caregivers

Augmented Baseplates: A Game-Changer in Glenoid Deformity Management

Contributor

Kaveh R. Sajadi, MD, FAAOS

A blog commentary on the article “Augmented baseplates yield optimum outcomes when compared with bone graft augmentation for managing glenoid deformity during reverse total shoulder arthroplasty: a retrospective comparative study” by Colasanti, et al. JSES 

The development of the reverse shoulder prosthesis revolutionized shoulder arthroplasty and introduced a successful option to improve pain and function in patients with rotator cuff tear arthropathy. Its indications have since expanded. Many modifications of the original design have been developed, with the goal of optimizing function and minimizing complications such as scapular notching, instability, acromial/scapular spine fractures and glenoid looseningIn this commentary, we will explore the findings of this retrospective study comparing the outcomes and complications of the use of metallic augmented glenoid baseplates with the use of structural glenoid bone grafts.

In this study, the authors utilized an international, multicenter registry of a single-platform reverse shoulder prosthesis. They reviewed patients from 2010-2018 who underwent primary reverse total shoulder arthroplasty (rTSA) with either glenoid bone grafting behind the baseplate or an augmented glenoid baseplate. In this system, three metallic augments are available: 80 posterior augment, 100 superior augment, and a combined 100 superior/80 posterior. All patients underwent plain radiographs as well as CT scans which were reformatted and uploaded to computer-planning software. The choice of augment or bone graft was made by the individual surgeon to best achieve a goal of orienting the glenoid implant to within 100 of neutral version. Execution of the plan was by use of cannulated drill guides and computer-assisted navigation. Demographic data as well as preop and postop patient-reported outcome measurements (PROMs), including Simple Shoulder Test, UCLA shoulder scale, ASES score, Constant-Murley Shoulder Outcomes Score, Shoulder Arthroplasty Smart (SAS) score, and Shoulder Pain and Disability Index (SPADI). Range of motion was also recorded pre- and post-operatively, and postoperative radiographs were obtained at latest follow-up. Statistical comparisons were then performed between the augment and bone graft groups.

The study included 47 patients in the bone graft group and 520 patients in the augment group. All PROM scores were statistically significantly better in the augmented baseplate group at minimum 2-year follow-up, along with postoperative active range of motion in abduction, forward elevation, and external rotation (p < .05). Internal rotation was not significantly different.  Patient satisfaction was higher as well in the augmented group (p = .006). Intraoperative data showed an approximately 50% less operative time, an almost 1/3 lower blood loss, and a shorter length-of-stay in the hospital. Statistical significance is one thing, but substantial clinic benefit (SCB) is even more meaningful. More patients in the augment group reached the SCB in all ROM and PROMs, but was only statistically significant in ASES and SPADI scores. With regards to complications, there was more scapular notching in the bone graft group and the adverse event rate and revision rate were significantly higher in the bone graft group. The highest rate of aseptic loosening was seen in the bone graft group.

The authors of this study are to be commended for this significant addition to the shoulder literature, and have shed light on the advantages of using augmented baseplates in managing glenoid deformity during rTSA. The results unequivocally favored augmented baseplates, showcasing their ability to deliver optimum outcomes in glenoid deformity management. Some of the key benefits of augmented baseplates include:

  1. Improved Stability and Fixation: The use of augmented baseplates allows for a larger contact area between the glenoid component and the native glenoid, leading to improved load distribution and decreased risk of loosening. This advantage translates into better long-term implant survival rates and reduced revision surgery.2,3
  2. Restored Glenoid Anatomy: Augmented baseplates make it easier to accurately restore the glenoid implant to a relatively neutral alignment. With bone graft augmentation, achieving precise anatomical reconstruction can be challenging due to the difficulties in shaping the graft. In addition, graft resorption and loss of fixation can occur over time. In contrast, augmented baseplates provide a reproducible fit, resulting in improved joint mechanics and reducing the likelihood of glenoid component malposition.1
  3. Simplified Surgical Technique: The utilization of augmented baseplates simplifies the surgical technique by eliminating the need for bone graft harvesting and fixation. Bone graft augmentation requires additional surgical steps, including graft preparation, shaping, and fixation, which can increase operative time. This was shown in the almost 50% longer time in the bone graft cohort. Augmented baseplates streamline the procedure, saving valuable surgical time and reducing the risk of associated complications.1

The study does have a few limitations. First, the choice of augment or bone graft was made by the individual surgeon without specific objective criteria. This may introduce bias, including selection bias. The bone graft cohort may have had significantly greater deformity than these augments could restore, possibly leading to worse outcomes. Additionally, as the authors have noted, this was a single arthroplasty system and may not apply to others.

This study convincingly demonstrates the advantages of augmented baseplates over bone graft augmentation in the management of glenoid deformities. The benefits include improved stability and fixation, accurate restoration of glenoid anatomy, and simplified surgical technique. Moreover, this study should prompt further research into augmented baseplates, encouraging the development of augment options for greater deformity.

References:

  1. Colasanti CA, Lin CC, Ross KA, Luthringer T, Elwell JA, Roche CP, Virk MS, Simovitch RW, Routman HD, Zuckerman JD. Augmented baseplates yield optimum outcomes when compared with bone graft augmentation for managing glenoid deformity during reverse total shoulder arthroplasty: a retrospective comparative study. J Shoulder Elbow Surg. 2023 May;32(5):958-971. doi: 10.1016/j.jse.2022.10.015. Epub 2022 Nov 16. PMID: 36400341.
  2. Hsu JE, Richetti ET, Huffman GR, Ianotti JP, Glaser DL. Addressing glenoid bone deficiency and asymmetric posterior erosion in shoulder arthroplasty. J Shoulder Elbow Surg. 2013 June;22(9):1298-1308 https://doi.org/10.1016/j.jse.2013.04.014
  3. Lanhma NS, Peterson JR, Ahmed R, Pearsall C, Jobin CM, Levine WN. Comparison of glenoid bone grafting vs. augmented glenoid baseplates in reverse shoulder arthroplasty: a systematic review. J Shoulder Elbow Surg. 2023 April;32(4):885-891 https://doi.org/10.1016/j.jse.2022.11.017