The reverse shoulder prosthesis was introduced in France in the 1980s and was FDA-approved for use in the United States in 2004. Since that time, it has revolutionized the field of shoulder replacement. The reverse shoulder prosthesis has a proven track record of providing predictable and sustainable pain relief and functional improvement for patients with a host of shoulder pathologies, ranging from osteoarthritis to rotator cuff arthropathy. The stability and functional improvements afforded by the reverse shoulder prosthesis are achieved, in part, by transitioning the large outer deltoid muscle of the shoulder into a mechanically advantaged motor of the arm. As a result of the forces generated by the deltoid muscle, high loads are transmitted to the site of origin of that muscle on the scapula leading to fractures in a rare cohort of patients. These so-called acromial fractures are not widely studied due to their infrequency and the relative heterogeneity of reverse shoulder prosthesis designs on the market. Improvements in understanding acromial fractures is important as their occurrence can impair the clinical outcome of the reverse shoulder prosthesis. A recent study by Routman et al.is, to date, the largest cohort of patients reported, which sheds light on the patient risk factors and prosthesis-related factors leading to this unfortunate and uncommon complication of reverse shoulder replacement.
When Dr. Paul Grammont introduced the reverse total shoulder arthroplasty (rTSA) in the late 1980s/early 1990s, it was a revolutionary treatment for a previously unsolved clinical condition, rotator cuff tear arthropathy. The original design had an unfortunately high complication rate which limited its use. Modern designs have significantly improved the complication rate as well as the success of the operation, and indications for rTSA have significantly increased. This increasing utilization has led some to coin the phrase “reversomania”, suggesting it is being done too often or perhaps too soon.
Clearly, complication rates for rTSA have decreased,1 and the rate of rTSAs performed have significantly increased with more rTSAs now being performed than anatomic shoulder arthroplasty (aTSA).2 The authors of the study, “A 10-year experience with reverse shoulder arthroplasty: are we operating earlier?”, sought to determine if, due to increased comfort and success with rTSA, surgeons are performing rTSA earlier in the disease process. In other words, has the “tipping point”, the point at which the patient’s symptoms are severe enough that the patient and surgeon elect to undergo rTSA changed, or has the threshold for performing surgery moved?
In 2013, Dr. Carlo Romano presented clinical evidence for InterSpace via a systematic review of globally accumulated literature. Five years later, in 2018, the data was updated to include new publications and 28 peer-reviewed papers found from more than 20 different sites. The review excluded case reports, clinical series with less than 10 patients, duplicate studies, and series with a mean follow-up of less than 24 months. The inclusion criteria left 19 papers for a total of 732 spacers implanted at 18 centers. This systematic review of the literature demonstrates the safe and effective use of InterSpace in overcoming complications associated with Periprosthetic Joint Infection (PJI).
Only 43 patients (5.9 percent) had a persistent infection that required a spacer exchange or resection arthroplasty
Seven hundred and nine (709) patients underwent the second-stage procedure
Of the 709, only 44 patients (6.2 percent) had an infection at the mean follow-up of 55 months.1
Today, the updated clinical results continue to show that the routine use of the InterSpace antibiotic spacers are validated. As a recent example of published clinical results, Patrick et al. from the University of Florida published “Management of infected shoulder arthroplasty: a comparison of treatment strategies” in the Journal of Shoulder and Elbow Surgery. Among the reviewed treatment modalities for infected shoulder arthroplasty, the InterSpace Shoulder was found to be an effective tool across various treatment strategies.
There is ample support in the literature that superior inclination of the glenoid baseplate in reverse total shoulder arthroplasty (rTSA) can lead to a higher risk of instability and premature implant failure. This is because a superiorly inclined baseplate experiences a greater shear vector imparted by the action of the deltoid muscle. Because cuff deficient arthritic shoulders often develop superior glenoid erosion, shoulder surgeons must carefully assess preoperative glenoid inclination when planning rTSA to avoid implant malposition. Preoperative planning platforms now allow surgeons virtually correct glenoid deformity while also optimizing implant fixation, backside contact with host bone, and avoidance of bone impingement such as scapular notching.
Boileau et al recently described a new measurement of glenoid inclination called the Reverse Shoulder Angle (RSA). Their contention is that referencing the more traditional ß-angle (the angle formed by a line connecting the superior and inferior glenoid face with a perpendicular to a line along the floor of the supraspinatus fossa) may inadvertently cause surgeons to superiorly incline small, flat-backed reverse baseplates when placed on the inferior half of the glenoid. Therefore, the RSA angle measures only the inferior half of the glenoid rather than the full glenoid face. This results in an average measured inclination of 25° + 8°, which is a 10° + 5° compared to the ß-angle. The authors note that Favard E1 glenoids with central erosion are at risk for baseplate malposition.
Accurate placement of the glenoid component in reverse total shoulder arthroplasty (rTSA) is important to reduce component loosening, scapular notching, instability and to maximize impingement-free range of motion. Initial stability of the implant is critical for bony in-growth and is dependent upon optimal screw placement and maximizing screw length. Glenoid exposure and anatomy can be difficult, and in the presence of glenoid wear or deformity, placement of the implant and screws may be challenging.
Computer navigation has been shown to improve the ability to place the central glenoid post/cage fully within the glenoid vault and to optimize screw placement and length (Nashikkar et al). Computer navigation has also been shown to improve accuracy in achieving correct version and inclination of the glenoid component (Nguyen et al; Verborgt et al; Kircher et al). Some surgeons may be concerned about the perception of increased surgical time associated with computer navigation as well as any learning curve that comes with adopting a new procedure. This study by Wang et al investigated the learning curve of computer navigated rTSA, the accuracy of implant placement, and the effect on surgical time.
This well-designed study was a prospective case-series of a single experienced shoulder surgeon evaluating his first 24 consecutive navigated rTSAs. Although he had extensive experience with the arthroplasty system, his only prior experience with this navigation system was a sawbone workshop, a single cadaveric case, and a single clinical case to allow himself and his surgical team to be familiar with the setup and workflow. All cases underwent preoperative planning using Blue Ortho CT protocol (Blue Ortho, Grenoble, France). The goal of planning was to attain a glenoid implant version as close to 00 as possible using reaming or augments, attain 00 of inferior inclination, maximize bone-implant contact, and keep the glenoid central cage fully contained in the glenoid vault. Preoperative planning took 3-5 minutes per patient, a step I would argue should be done whether navigation is planned or not.
Even though reverse total shoulder arthroplasty (rTSA) is becoming an increasingly commonly performed procedure throughout the world, studies are still needed in order to understand how we can maximize outcomes and minimize complications. While lack of glenoid baseplate fixation is not a common problem, loosening can occur1,2 and can lead to inferior outcomes and revision surgery. In addition, scapular spine stress fractures have been associated with glenoid screw placement in rTSA and also lead to inferior clinical outcomes.3,4 Understanding complications such as these are important for future surgeons so that they can be avoided.
Roche et al in their recent article in JSES Open Access entitled “Impact of screw length and screw quantity on reverse total shoulder arthroplasty glenoid fixation for 2 different sizes of glenoid baseplates” evaluated how the number and length of screws affect baseplate fixation in an osteoporotic bone-substitute model using the Exactech standard and the Exactech small glenoid baseplates. They evaluated shear and compressive cyclic loading in a biomechanical model looking at constructs with two, four, and six screws with different screw lengths (18, 30, 46mm). All scenarios tested showed that the baseplates remained well-fixed after cyclical loading of 10,000 cycles without catastrophic failure, but there was a difference in displacement between the constructs. Baseplate displacement was less for the constructs with four screws compared to the constructs with two screws. The addition of six screws in the large baseplate did not make a difference in displacement. In addition, constructs with the longest screws had the lowest amount of baseplate displacement after cyclical loading. Short screws (18mm) showed the most displacement in both the small and standard baseplates.
The incidence of shoulder arthroplasty continues to increase, and this has brought continued innovation in preoperative planning and implant design. Concurrently, with improved imaging techniques, our understanding of pathologic changes that affect the joint have begun to elucidate strategies to address glenoid wear. Durability of the glenoid implant remains the weak link of shoulder arthroplasty,2,10 and both clinical and biomechanical studies have demonstrated that excessive residual retroversion or inclination,7,9 excessive corrective reaming,4,5 recurrent humeral subluxation6 and insufficient implant contact1 with bone are all risk factors for component loosening or failure. While augmented anatomic and reverse glenoid implants are now widely available, their use remains fairly limited relative to the frequency of pathologic wear. Guidelines on their use have also yet to be established, and a surgeon’s ability to accurately place such implants in cases with significant to extreme glenoid wear are uncertain. Prior cadaveric studies examined surgeon accuracy in recreating a preoperative plan using conventional instruments with free-hand techniques. The studies demonstrated significant variability and an average error of + 6-10° relative to the planned correction.11 This indicates that “eyeballing” glenoid implant placement may lead to significant variation from the plan. Particularly in cases of moderate to severe pathologic wear, such as the Walch B2 or B3 glenoid. This inaccuracy can be the difference between long-term durability and mid-term failure.
CT-based preoperative planning is now widely available and increasingly popular as it allows surgeons to virtually plan implant selection and placement and optimize parameters such as correction of inclination and version, peg placement in the glenoid vault, backside contact and amount of corrective reaming. While this can provide a very quantitative method of glenoid reconstruction, planning alone does not guarantee proper bone preparation or implant placement without additional technology to assist surgeons in replicating the plan. While patient-specific instrumentation (PSI) can improve the accuracy of implant placement over free-hand techniques, it still has a margin of error of + 4° on average.3,12 As studies have shown increased stresses in the cement mantle over 10° of residual version, this amount of error could potentially lead to pathologic implant malposition. Furthermore, PSI does not allow surgeons to adjust the plan intraoperatively if needed.
One of the most difficult aspects of shoulder arthroplasty remains the ability to correct glenoid deformity with accurate reaming and positioning of the glenoid implant. Even with experienced surgeons, it remains a challenge to appreciate how much version and inclination is corrected intra-operatively. The success of patient-specific instrumentation (PSI) in total hip and knee arthroplasty has naturally led to the surge of growth of PSI in shoulder arthroplasty. However, the key question of whether PSI is better than standard instrumentation is unknown.
21 of the 22 articles required the assistance of a physical PSI component to be manufactured prior to surgery. It took an average of 10 days to 5 weeks for production once the preoperative plan was completed.
This meta-analysis attempts to determine whether PSI significantly improves implantation accuracy during shoulder arthroplasty. The authors review all the available literature on PSI in shoulder arthroplasty including both cadaveric and clinical studies looking at a variety of available industry manufactured components. A total of 22 articles were compared and all preoperative planning programs were predetermined with a goal of 0 degrees of version and 0 degrees of inclination for total shoulder arthroplasty (TSA) and 5-10 degrees of inferior inclination for rTSA. 21 of the 22 articles required the assistance of a physical PSI component to be manufactured prior to surgery. It took an average of 10 days to 5 weeks for production once the preoperative plan was completed. The authors found that in 91% of articles, the postoperative errors were found to be less than 5 degrees with the assistance of PSI compared to preoperative plans. However, there was only 18% of articles that found PSI significantly reduced glenoid component malposition compared to standard instrumentation. Meta-analysis that directly compared PSI to standard instrumentation was only available for 7 articles (2 clinical, 5 cadaveric). While analysis did demonstrate an improvement in accuracy with PSI, it did not demonstrate any significant difference in accuracy when comparing PSI to standard instruments when looking at differences in version error (3 degrees), inclination error (1 degree) and offset (0.22mm).
As the evolution of shoulder arthroplasty permits progressively shorter lengths of hospital stay and performance of these procedures in the ambulatory setting, pain management continues to receive increased attention from patients and physicians. Pain management is critical for timing of discharge, patient participation in early physical therapy, and is highly correlated with patient satisfaction. For some time, opioids have been a cornerstone of pain management, despite the opioid problem in the United States having achieved “epidemic” proportions with use, misuse and diversion. As a result, there is increased awareness of the benefits of limiting opioid exposure in the perioperative period surrounding elective orthopedic surgery. The authors of the study, “Opioid-Free Total Shoulder Arthroplasty” by Van Doren et al, reported on a series of properly selected patients undergoing total shoulder arthroplasty (TSA) who had satisfactory pain management using a multimodal pain approach without opioids. The study was an important demonstration that all providers performing shoulder replacement can make even minor modifications to pain protocols to move closer to eliminating the requirement for opioids, making these procedures increasingly safer for patients.
The study was an important demonstration that all providers performing shoulder replacement can make even minor modifications to pain protocols to move closer to eliminating the requirement for opioids…
The study was a prospective nonrandomized look at 65 patients with a mean age of 71 years undergoing a mix of primary and reverse arthroplasty; one group received opioid medications and the other group did not. Important exclusions were history of prior surgery, renal or liver disease (contraindicating NSAIDs), fractures, and inability to undergo regional anesthesia in the form of an interscalene nerve block. The observation group received interscalene block, intraoperative fentanyl and routine postoperative opioid medications with over the counter NSAIDs when recommended as needed. The intervention group received interscalene block, preoperative gabapentin and celecoxib, intraoperative acetaminophen, periarticular injection of liposomal bupivacaine, in-hospital use of ketorolac (Toradol), and post-discharge oral gabapentin and celecoxib prescriptions with oral acetaminophen as needed.
The volume of shoulder replacements performed has grown exponentially in the last decade due to its success in relieving pain and improving function with modern techniques and implants, but concerns regarding its longevity remain. The most common reason for failure in the long-term is loosening of the glenoid component. Progression of radiolucent lines is a worrisome sign that may suggest glenoid component loosening. However, the presence of radiolucent lines, as noted in the article, have been reported between 0-100% of the time with the lines frequently present on immediate postoperative radiographs. The presence of lines does appear to increase with longer follow up. The significance of these lines, aside from concern for loosening, is debated.
The authors of this study performed a retrospective review of all total shoulder arthroplasties (TSAs) over an 11-year period with all-polyethylene pegged or keeled glenoid components with a minimum 2-year followup. A multi-center research database was utilized. Glenoid lines were graded by the Lazarus scale, which grades lines on a scale from 0 (no lucency) to 5 (gross loosening or shift in component position). Demographic data was collected as well as patient-reported outcome (PRO) measures, including ASES score, Constant score, UCLA score, Simple Shoulder Test score, and Shoulder Pain and Disability Index score. Patients’ active range of motion was recorded as well. The authors only examined traditional all-polyethylene cemented implants, specifically excluding patients with a central in-growth peg as a previous study by Grey SG, et al, showed significantly reduced radiolucent lines with this prosthesis. This was recently confirmed in the study by Friedman RJ, et al, which showed a rate of lucent lines in 9% of patients with the hybrid cage glenoid versus 37.6% in all polyethylene pegged glenoids (p < .0001).