Stephanie Muh, MD
Read complete study: Radiographic changes and clinical outcomes associated with an adjustable diaphyseal press-fit humeral stem in primary reverse shoulder arthroplasty
The use of press-fit humeral components for reverse shoulder arthroplasty has become more common in shoulder replacement surgery. Historically, humeral fixation was achieved with cementation techniques. However, due to increased operating time for cementation and added difficulty with higher complications in revisions during humeral component removal, surgeons have increasingly transitioned to press-fit humeral stems.
This article is a retrospective review of primary reverse shoulder replacements implanted with a modular diaphyseal press-fit humeral stem. Total hip literature has shown that distal press-fit stems obtain control through the medullary canal. The torsional stress is then transferred to proximal fixation and leads to increased stress shielding proximally with corresponding bone loss. This seems to be demonstrated in this study as well. With only a short-term follow-up, the authors found minimal radiolucent lines around distal fixation. However, 97% of radiographs demonstrated radiolucent lines around the smooth metaphyseal component. Additionally, the authors found progression of these radiolucent lines during the first two years. The authors claim the radiolucent line progression stabilizes after two years, however their mean follow up was 42 months (three and a half years). I do not believe this is sufficient time to truly access whether evidence of radiolucent lines has stabilized.
The evidence of proximal humeral bone loss is concerning and brings up an interesting clinical question. How do we revise shoulders with massive proximal bone loss? Continue reading
Thomas Wright, MD
Read complete study: Risk of insufficient internal rotation after bilateral reverse shoulder arthroplasty: clinical and patient reported outcome in 57 patients.
This study focused on the effects and risks of bilateral reverse shoulder arthroplasty (rTSA) on internal rotation (IR) in 57 patients. Data was recorded up to two years after the second surgery. The study found that only 15 percent of patients had insufficient IR in both shoulders after 12 months and 5 percent after 24 months. Patients who had insufficient baseline IR in their second shoulder and insufficient IR 12 month post op after their first shoulder had a 100 percent risk of having insufficient IR in both shoulders. The conclusion of this article is a recommendation to use staged bilateral rTSA over the use of a hemiathroplasty. The authors found that the majority of patients would undergo the surgery again, as it does provide benefits, like reduction in pain, regardless of the issues with IR.
The authors of this study focused on the risks of staged bilateral rTSA on internal rotation. I agree with their concern, as bilateral decreased IR could result in difficulties with toileting. In my practice, I stage my bilateral cases; however the timing is up to the patient. I will proceed with the second surgery no sooner than 12 weeks, but I do not recommend waiting as long as a year. In 2014, we published an article on bilateral rTSA1 in which we found all patients eventually had enough IR to allow toileting with at least one shoulder. I agree with the authors and do not recommend using a hemiarthroplasty in the second shoulder, based on the positive results that we had with rTSA.
Although the article showed a 100 percent failure rate in achieving sufficient IR in the second shoulder when it comes to patients who have both insufficient baseline IR and insufficient IR 12 months post op in their first shoulder, we have not noted that to be a problem.
One example is a 79 year old male with symptomatic cuff tear arthropathy on the right and a failed total shoulder arthroplasty (TSA) on the left due to rotator cuff insufficiency.Because of the predictable nature of performing an rTSA as a primary, the right side was addressed first. At three months post-op he had IR to L5.
79 year old male, cuff tear arthropathy on the right side, 3 months post op