Screw Length vs Quantity in rTSA

Jay J. King, MD

Read complete study: Impact of screw length and screw quantity on reverse total shoulder arthroplasty glenoid fixation for 2 different sizes of glenoid baseplates

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.

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Clinical Studies Validate the Accuracy of GPS in Targeting Implant Placement in Anatomic and Reverse Shoulder Arthroplasty

Moby Parsons, MD

Read complete study: Computer navigation re-creates planned glenoid placement and reduces correction variability in total shoulder arthroplasty: an in vivo case-control study

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.

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Is patient-specific instrumentation better than standard instruments in shoulder arthroplasty?

Stephanie Muh, MD

Read complete study: Accuracy of patient-specific instrumentation in shoulder arthroplasty: a systematic review and meta-analysis

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).

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Opioid-Free Shoulder Arthroplasty: Are We There Yet?

Thomas Obermeyer, MD

Read complete study: Opioid-free shoulder arthroplasty: a prospective
study of a novel clinical care pathway

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.

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The Effect of Glenoid Component Lucency on Outcomes

Kaveh Sajadi, MD

Read complete study: Glenoid component lucencies are associated with poorer patient-reported outcomes following anatomic shoulder arthroplasty

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).

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Navigated Ream and Run Procedure with ExactechGPS

Moby Parsons, MD

The Ream and Run shoulder replacement is a great option for younger patients with shoulder arthritis who have failed conservative treatment yet wish to maintain a high level of activity. Because the weak link in shoulder replacement is the plastic socket implant, avoiding the insertion of this reduces the risk of failure, particularly for patients who intend to subject their shoulder to moderate stress over a long period of time. The Ream and Run resurfaces the ball, removes the bone spurs, releases the contracted tissues and reshapes the worn socket to a smooth and conforming concavity to mate with the ball.

While partial shoulder replacement (hemiarthroplasty) has historically gotten a bad reputation for having inferior results to total shoulder replacement, the results cannot be generalized to all cases. Many glenoids (socket) have substantial wear and erosion from the arthritic process. If such wear is not addressed at the time of hemiathroplasty, patients are at high risk of continued pain and abnormal joint mechanics. The Walch classification shows the different patterns of wear with the B1, B2 and B3 being both common and problematic. In these patterns, the ball shifts to the back of the arthritic socket and results in progressive erosion of the posterior glenoid. Failure to recenter and reshape the head into a single concavity will result in failure of hemiarthroplasty.

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PRP: Should I Be Using It?

Kaveh Sajadi, MD

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PRP, platelet-rich plasma, is touted by some to be a revolutionary treatment with the potential to heal or alleviate any number of ailments, from arthritis to tendinopathies to tendon tears or ruptures. The idea is to use the body’s own “healing” system to repair damaged tissue by amplifying it–increasing the concentration of platelets and their accompanying growth factors, which is then injected into the diseased or injured area.

Platelets are typically activated when a blood vessel is damaged. When the platelet is activated to clot, it also releases many growth factors which are contained within the alpha granules in the platelet. The growth factors present include PDGF (platelet-derived growth factor), important in wound healing, VEGF (vascular endothelial growth factor), which recruits the body to form new blood vessels, as well as many other signaling factors and cytokines.

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Stress Fractures After rTSA. Not Every Onlay is Created Equal.

Ian Byram, MD

Read complete study: Increased scapular spine fractures after reverse shoulder arthroplasty with a humeral onlay short stem: an analysis of 485 consecutive cases

Since its FDA clearance in 2003, reverse shoulder arthroplasty (RSA) has become increasingly utilized for the treatment of arthritis, fractures, and rotator cuff failures in the United States. Initial reports demonstrated a high rate of complications, including instability, impingement, scapular notching, and subsequent implant failure.Many implant designs have been successfully modified to minimize these problems. While scapular notching seen with the initial Grammont style prosthesis has decreased with modern lateralized implant designs, scapular spine fractures have become more prevalent.

The authors of this study analyzed a series of RSA cases utilizing a short stem, 145° neck-shaft inclination prosthesis hoping to shed light on implant features that may lead to scapular spine fractures. In a retrospective review of 485 consecutive arthroplasties, they reported 21 (4.3%) scapular spine fractures that were diagnosed at a mean of 8.6 months after surgery. Comparing those patients with matched controls, patients with fractures demonstrated significantly worse Constant scores and forward flexion. They concluded that utilization of a lateralized “onlay” convertible humeral design creates increased stress on the deltoid and acromion, resulting in an undesirable rate of scapular spine and acromial fractures.

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Scapular Fractures After RSA – The Bane of Our Existence

Stephanie Muh, MD

Read complete study: Scapular fracture in reverse shoulder arthroplasty (Grammont Style): prevalence, functional, and radiographic results with minimum 5-year follow up

The development of postoperative scapular spine or acromial base fractures remains a difficult problem to treat. With a reported incidence of 1-10% in the literature, there has been no consensus on the best treatment, and most authors report poor post-fracture functional outcomes.1-3 Both operative and nonoperative management of these fractures have been advocated with variable outcomes.2,3

This retrospective study presents data from a large cohort of patients with a single prosthetic design (Grammont style with medialized center of rotation and medialized humerus with inlay prosthesis). The authors found an overall prevalence of 1.3% scapular fractures in 1,953 implants. This seems to correlate with other literature where the incidence ranged from 1-10%.1-4 When evaluating the functional results with a minimum of five years follow-up, 19 fractures were identified with an overall improved range of motion and Constant score. It is important to note, however, the patients with fractures did not improve as greatly as those without fractures. While the postoperative Constant score improved from 25.6 to 47 postoperatively, the authors note the average postoperative Constant score in a non-fracture group is 70. They did not directly compare the fracture group range of motion to non-fracture group which I think would have added valuable information. It would have been interesting if the authors presented initial improvement postoperatively and compared this to post-fracture outcomes and commented if there was function.

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To Repair, or Not to Repair, That is the Question…

Kaveh Sajadi, MD

Read complete study: The effect of subscapularis repair on dislocation rates in reverse shoulder arthroplasty: a meta-analysis and systematic review

Whether ‘tis nobler in the mind to bear the slings and arrows of our colleagues…

The role of the subscapularis in reverse total shoulder arthroplasty (rTSA) continues to be debated. Reverse TSA is most commonly performed via a deltopectoral approach, which often requires takedown of an intact, though possibly degenerated or atrophic, subscapularis tendon. Surgeons debate the importance of its repair at the conclusion of the surgery. This debate centers on the importance and role of the subscapularis in stability of the prosthesis, range of motion (both internal and external rotation), and outcomes. Those in favor of repair cite studies indicating lower dislocation rates with repair and better internal rotation; those opposed express concern about it potentially limiting external rotation and possibly opposing the deltoid in elevating the arm.1 This meta-analysis and systematic review sought to compare the dislocation rates and outcomes in rTSA with and without subscapularis tendon repair using the highest level of data available.

This meta-analysis and systematic review sought to compare the dislocation rates and outcomes in rTSA with and without subscapularis tendon repair using the highest level of data available.

It is important to clarify some descriptions used in the study. Since the introduction of the original Grammont style reverse prosthesis in the late 1980s and early 1990s, many different design modifications have been introduced.2 The primary differentiating characteristic between implant designs is the location of the center of rotation (COR) of the new glenohumeral articulation. By their very nature, all reverse designs medialize the COR compared with the native shoulder. However, systems with the COR at the glenoid face, as the original Grammont design, are considered medialized and those with the COR lateral to the glenoid are referred to in this paper as lateralized designs. Furthermore, the implant can have a medialized humerus (Grammont) or a lateralized humerus. Routman HD, et al, proposed a classification to standardize the nomenclature, dividing implants into the medial glenoid/medial humerus (Grammont), lateral glenoid/medial humerus, and medial glenoid/lateral humerus.2,3 Some of the implants in this study, classified as lateralized glenoids by the authors, are classified as medial glenoid/lateral humerus by Routman.

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