How Do I Manage Glenoid Bone Loss?

Read complete study: Bone Graft Augmentation for Severe Glenoid Bone Loss in Primary Reverse Total Shoulder Arthroplasty

Kaveh R. Sajadi, MD

Following the legacy of hip and knee replacements in relieving pain and improving function for patients with arthritis, shoulder replacements are now the fastest growing joint replacement. Shoulder replacements reliably improve the quality of life for most patients and approximately 85% are still in place 15 years later. The leading cause of failure is loosening of the component on the glenoid side of the shoulder. Minimizing this improves longevity and outcomes.

Shoulder arthritis is often characterized by significant glenoid bone loss. Classically, primary arthritis is associated with posterior glenoid wear, while rotator cuff tear arthropathy leads to superior glenoid wear. To minimize the risk of glenoid loosening, it is important to restore glenoid alignment and version and obtain secure fixation. The surgeon may be faced with managing diminished bone stock or significant deformity to achieve these goals. The primary options for managing bone loss on the glenoid side are eccentric reaming, bone grafting, and augmented glenoid implants.

In “Bone Graft Augmentation for Severe Glenoid Bone Loss in Primary Reverse Total Shoulder Arthroplasty,” Dr. Lorenzetti and his coauthors have reported their outcomes with one of these approaches, bone grafting, in conjunction with reverse shoulder arthroplasty.  The authors had two goals: first, to determine the outcome of reverse arthroplasty when bone grafting was performed as part of a primary procedure; second, to correlate outcomes with the amount of native bone support at implantation. They conducted a retrospective of 57 patients with minimum 2-year follow up who had this procedure done.

In addition, they used CT scans preoperatively and plain radiographs postoperatively to measure the degree of bone loss and the amount of native bone support under the glenoid baseplate. Replacements were performed for rotator cuff tear arthropathy, rheumatoid arthritis, osteoarthritis, and chronic dislocations. Due to the diversity of diagnoses, the wear pattern varied.  ASES, Simple Shoulder Test, VAS pain and function scores, and patient satisfaction were assessed at minimum 2-year follow up.

Intraoperative decision making determined that if at least 80% of contact could not be achieved between the baseplate and native glenoid, bone grafting was utilized. When available and of sufficient quality, humeral head autograft was preferentially used. Otherwise, femoral head allograft was chosen. Virtual models of the bone and implant were created based on preoperative CT and postoperative x-rays and used for virtual implantation to determine the baseplate contact with native bone, which was reported as a percentage of total surface area available. A previously performed cadaveric study was used as a validation for this virtual technique.

The authors reported significant improvements in ASES scores, patient satisfaction, simple shoulder test, range of motion, and pain scores. Further, they documented graft incorporation in 98% of patients. The mean contact area percentage of the implant on native bone was 17%. They did not find an association of outcome with bone contact area.

I commend the authors on their technique and outcomes. Their high incorporation rate and low failure rate show that bone grafting for significant glenoid defects is a successful technique. It is important to consider some factors not specifically mentioned though.

First, restoration of normal glenoid alignment is an important goal of reverse arthroplasty, and the authors do not report pre- or postoperative version. Second, graft preparation and sizing should optimize this restoration and shaping the glenoid bone graft can be challenging. Finally, although contact with native bone is measured, the amount of fixation of the implant into native bone is not described. The implant must make significant purchase, generally a centimeter or more, in the native glenoid, often through the graft, to achieve stable fixation. Having a long central post/cage or screw facilitates this.

I have performed this technique with success as well. The pictures below are of a 71-year-old gentleman with a Walch B2 glenoid with approximately 25 ° of posterior glenoid wear. I chose to use humeral head autograft with a long central post implant to insure fixation in native bone. Preoperative and postoperative imaging are included.

Pre-op

Post-op

While this paper describes one particular method, it is important to remember there are other ways to manage glenoid bone loss.  Continue reading

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Patient-Specific Guides with a Custom Implant: Is This a Practical Solution?

Joseph Zuckerman, MD

Read complete study: A patient Specific guide for Optimizing custom made glenoid implantation in cases of severe glenoid defects.

These authors studied the ability to implant a custom glenoid component in 10 cadaver glenoids with glenoid defects using patient-specific guides and traditional non-guided techniques. The use of the patient-specific guide reduced angular deviations from the plan and significantly improved the position and length of the screw placements when used to implant the custom made glenoid components.

Literature Review:

The authors have focused on a well-known challenge in shoulder arthroplasty – treatment of the deformed glenoid during anatomic or reverse shoulder arthroplasty. There is no doubt that two approaches canbe developed to address this issue. The first is the use of patient-specific guides (or intraoperative positioning devices) to improve the accuracy of component placement. We all recognize that a properly placed glenoid component will have longer-term survival than a malpositioned component. The second approach is to have non-standard glenoid components available to address the deformity. These can be either custom-made implants specific for the patient being treated or augmented “off the shelf” implants that address the common deformities encountered.

I have found that using non-custom or “off the shelf” augmented glenoid components have addressed many of the bone-loss issues I have encountered.

The authors actually combine both approaches – they use a custom implant with a specimen-specific guide. This could be perceived as the “best of both” but in actuality it is quite impractical from a cost perspective. The incremental cost of a custom implant combined with a CT-generated, patient-specific guide would add significant incremental cost. In 2016, regardless of where the surgery is being performed in the world, it is a surgeon’s responsibility to consider cost, especially in the context of cost vs. potential benefit. In addition, the FDA has been very strict on the use of custom implant components, which leaves us surgeons limited options for this approach. Continue reading