By John W. Aldridge, MD, F.A.A.O.S.
Stemless joint replacements, a promising innovation that utilizes press fit/bone technology first developed in hip surgery, are beginning to transform total shoulder arthroplasties.
This option conserves more of the patient’s natural bone by replacing only the damaged ball of the shoulder and a small segment of the humeral head. That compares to coring out the humerus bone to insert a metal stem, after dissecting the deltopectoral interval for access.
In stemless procedures, a cone-like structure is press-fit into the top of the humerus, without using cement. The prothesis instead contains a three-dimensional porous coating that promotes bony ingrowth.
The anticipated advantages are clear, particularly for younger, more active and more muscular patients, or for most anyone with good bone health. The surgery tends to involve smaller incisions and implants and less muscle dissection, as well as no violation of the humeral canal.
In my experience over the past six months, patients experience less post-operative pain and bleeding as compared to the traditional approach. Anecdotally, they also have recovered their natural shoulder function and mobility more quickly.
The stemless option, generally done on an outpatient basis, reduces the risk of an intra or postoperative fracture and removes the threat of stem-related complications. Additionally, patients are left with more natural bone should they require a revision in the future.
This fast-growing alternative, part of a movement toward minimally invasive surgeries and already prominent in Europe, now represents about 30 to 40 percent of total shoulder arthroplasty cases in my practice.
This figure should steadily increase as orthopaedists treat more younger patients, along with older adults who have remained active and retained good bone density. Stemless prostheses also can be beneficial in posttraumatic reconstruction cases, in which bone deformities can complicate or even preclude use of a humeral stem.
To sound a note of caution, not all patients are candidates for a stemless joint replacement. In particular, those who have osteoporosis, osteonecrosis or another bone disorder often don’t have the skeletal structure required to support a press-fit design.
Still, the development has followed a similar path to smaller femoral replacements in total hip arthroplasty, which reduce the diaphyseal disruption of the femur. As in hip cases, shoulder stems first grew progressively shorter, especially during the past five years, until the press-fit stemless option gained more widespread acceptance.
While long-term data is not yet available, stemless shoulder prostheses theoretically would be less prone to loosen, as the body’s own bone should grow into them for stable anchoring. Traditional shoulder prosthetics typically last 10 to 20 years, and there have been some issues with stability and longevity using shortened metal stems.
Early studies on stemless implants have demonstrated comparable outcomes to the latest standard procedures after about a decade, with a significant improvement in patient satisfaction. I expect more such positive data to accumulate in future years.
I am happy that this effective alternative for many shoulder patients has arrived in Hampton Roads, and I am looking forward to helping people return as quickly as possible to their normal daily lives and the activities they love.
Dr. Aldridge is a Board certified orthopaedic surgeon who specializes in minimally invasive total joint replacement and muscle-sparing spinal surgery. hrosm.com
