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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Is rTSA the Solution to Every Patient’s Problem?

Howard Routman, DO

Read the complete study: Causes of poor postoperative improvement after reverse total shoulder arthroplasty

This study reviewed comorbidities and results for higher baseline American Shoulder and Elbow Surgeons (ASES) scores that are correlated with poor post-operative improvement. The study collected data from a total of 150 patients who underwent reverse total shoulder arthroplasty (rTSA) from 2007-2013. A minimum of two-year post-operative ASES scores were included, and poor post-op improvement was defined as a change of ASES score of less than 12 points. Out of the 150 patients, male gender, presence of an intact rotator cuff at the time of surgery, depression, a higher baseline ASES score and higher total number of medical comorbidities were associated with poor post-operative improvement after rTSA. Neither patient age, nor indication for surgery, was found to correlate with poor improvement after rTSA. In general, the study population was older, with an average age of 71.6 +/- 8.8, and the majority of patients were female.

Literature Review:

It should be noted that as the number of rTSAs continues to grow rapidly—due to its success in improving pain and function in most patients—some patients fail to improve clinically. Interestingly, the article also mentioned that patient satisfaction is now frequently linked to hospital and physician reimbursements. This study emphasizes reasons for poor post-operative improvement throughout with baseline pulled  from ASES scores and patient data. Physical examination findings were not a focused component of the analysis.

The temptation to view the rTSA as a panacea that can fix everything is high.  We need to temper our enthusiasm and ensure that we select our patients wisely.

When managing expectations with higher pre-operative ASES scores, I don’t really look at an ASES score pre-operatively as a screening tool, but I appreciate the concept of the ‘delta’ of improvement before surgery.  If a patient’s radiograph shows a classic cuff tear arthropathy, and the patient has maintained overhead elevation and mild pain, the change in function and pain that can be provided with a perfect reverse is minimal.  Ideally, patient selection can help us identify who best benefits from rTSA.  By limiting the indications to patients who cannot elevate beyond 90⁰, and who identify themselves has having quality-of-life-altering pain, we can skew our delta favorably.  The article referenced a study by Wall et al that noted patients who underwent rTSA for primary osteoarthritis had much smaller improvements in range of motion compared with patients who underwent rTSA for rotator cuff tear arthropathy or massive tears. Current expectations for improving post-operative function versus outcomes in patients with high levels of pre-operative function are to be noted.

In a cohort of 31 of my rTSA patients, the average post op ASES score was 82.68 (+/- 18.4), compared to 76 +/- 16.7 as mentioned in the study. Continue reading