Primary stability of inferior tilt fixation of the glenoid component in reverse total shoulder arthroplasty: A finite element study

Glenoid component fixation with inferior tilt has been suggested as one of the surgical methods to decrease scapular notching and improve stability, but its clinically beneficial effect remains a concern. We evaluated the influence of inferior tilt fixation of the glenoid component on primary stability in reverse total shoulder arthroplasty by finite element analysis. Finite element models were constructed from cadaveric scapulae of females over the age of 60 years and glenoid components from reverse total shoulder arthroplasty. The relative micromotion at the bone–glenoid component interface, distribution of bone stress under the glenoid component and around the screws, contact area between the bone and screws, and cut surface area of the cancellous bone exposed after glenoid reaming were analyzed and compared between a neutral and 10° inferior tilt fixation of the glenoid component. The 10° inferior tilt fixation demonstrated greater relative micromotion and higher bone stress than the neutral tilt fixation. Eccentric reaming, which is done to produce the inferior tilt fixation of the glenoid component, increased glenoid cancellous bone exposure and decreased bone–screws contact area. Inferior tilt fixation of the glenoid component may adversely affect primary stability and longevity after reverse total shoulder arthroplasty. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1061–1068, 2016.     

Factors affecting fixation of the glenoid component of a reverse total shoulder prothesis

The semiconstrained design of the reverse arthroplasty allows loads from the humerus to challenge the fixation of the glenoid component to the scapula. We examined some of the factors affecting the quality of glenoid screw fixation, including the density of the material into which the screws are placed, the purchase of individual screws, and the direction of loading in relation to screw placement. Loads were applied by the humeral component to glenoid components with different conditions of fixation. The load to failure for each set of conditions was measured and compared statistically. Load to failure was less when the glenoid component was fixed to material of lesser density. Each screw contributed to the quality of fixation; the screw nearest the point of load application made the largest contribution. Load to failure was less when the load was colinear with a line through the nonlocking holes in the base plate compared to colinear with a line through the locking holes. In performing a reverse total shoulder, surgeons should emphasize secure intraosseous placement of the fixation screws in the best quality bone available. The placement of the inferior screw appears to be the most critical.     

Scapular notching: Danger ahead?

Scapular notching is a radiographic finding in patients that have had a reverse total shoulder arthroplasty. It has been linked to decreased range of motion, strength, and increased pain. It occurs most commonly in the early postoperative period but can be progressive. The incidence of scapular notching reported in the current literature ranges from 9.7% to 68%. This wide range can be attributed to the variable positioning of the glenosphere on the glenoid. To decrease the occurrence of scapular notching, it appears that the optimal positioning of the scapular component is inferior on the glenoid so the prosthesis will be anchored below the native glenoid. This prevents the humeral component from making contact with the glenoid neck and inferior bony pillar.     

The incidence of early radiolucencies about a pegged glenoid component using cement pressurization

Glenoid component loosening is the most common early mode of failure of total shoulder arthroplasty (TSA) We hypothesised that the use of a pegged glenoid component with a modern glenoid reaming system and an instrumented cement pressurization technique would achieve a low prevalence of early radiolucent lines. Of 81 patients having TSA with a cemented, all polyethylene, 3-peg glenoid component for primary glenohumeral osteoarthritis, 69 had high quality radiographs available for analysis. All preoperative and initial postoperative radiographs were reviewed and graded in a blinded manner using previously established criteria. When the radiolucency grade of cement fixation was converted to a numeric scale of 0 (no radiolucency) to 5 (grossly loose), the mean cementing score was 0.14 + 0.06. Of the 69 shoulders, 62 (90%) had no radiolucencies. These techniques to improve glenoid fixation resulted in a low incidence of early radiolucencies about the glenoid component in patients having TSA for primary glenohumeral osteoarthritis.     

The cemented humerus and non-cemented glenoid: The optimal hybrid solution for total shoulder arthroplasty

Hybrid fixation of total joint arthroplasty has been recognized as an accepted form of surgical approach in multiple joints. Principles of implant fixation should focus on durability and on providing secure long-term function. To date, there is no conclusive evidence that pressed-fit humeral stem fixation has an advantage over well-secured cemented humeral fixation. Although revision may require cement removal, a well-fixed bone—ingrowth implant may require slatting and osteotomy of the humerus. On the contrary, need for revision in arthroplasty due to inadequate implant fixation has almost universally revolved around the failure of cement fixation and loosening of the glenoid component. A case will be made based on 30 years of experience of a surgeon performing total shoulder arthroplasty using secure modern cement-fixation techniques of humeral components. More recently, over the past 10 years an extremely high rate of durable secure glenoid implant fixation has been achieved using press-fit tantalum porous anchorage of polyethylene glenoid components. This has resulted in no cases of loosening of glenoid fixation and only one case of glenoid component fracture with greater than 95% survivorship over a 10-year period. A combination of well-cemented humeral stem and trabecular metal anchorage of the glenoid has provided durable and long-lasting function in primary total shoulder arthroplasty.     

A novel method of image-based navigation in fracture surgery

The treatment of three- and four-part fractures of the humeral head is still controversially discussed. Some advocate primary arthroplasty while the results of primary fixation seem to be superior if no necrosis of the humeral head develops. Today navigation is used in orthopaedic surgery mainly for interventions on the spine, the pelvis and arthroplasty. In trauma surgery it is still rarely used and some technical problems need to be overcome. We report on a case of a three part fracture of the humeral head with mini-open reduction and fixation with image-based guided headless compression screws. For the fixation each screw was placed on the first trial, total radiation time was 60 s. At 12-month follow-up assessment radiographs showed a consolidated fracture, no loosening of the screws and a good glenohumeral articulation. The patient had free function of the shoulder and no pain, the constant score was 98 and the dash score 0. There is no evidence of a necrosis of the humeral head. The literature focuses on shoulder arthroplasty. There are no reports on the use of image-based guidance in shoulder traumatology so far. In conclusion, the described technique allows an accurate fixation of the humeral head fracture as the guidance system (Surgix) ensures the "first try first hit" screw positioning. The new system was integrated in the workflow and supports the surgeon as an aiming device. The role of navigation system in enhancing minimally invasive surgery of the shoulder should be further explored.     

Glenoid component failure in total shoulder arthroplasty

Glenoid component failure is the most common complication of total shoulder arthroplasty. Glenoid components fail as a result of their inability to replicate essential properties of the normal glenoid articular surface to achieve durable fixation to the underlying bone, to withstand repeated eccentric loads and glenohumeral translation, and to resist wear and deformation. The possibility of glenoid component failure should be considered whenever a total shoulder arthroplasty has an unsatisfactory result. High-quality radiographs made in the plane of the scapula and in the axillary projection are usually sufficient to evaluate the status of the glenoid component. Failures of prosthetic glenoid arthroplasty can be understood in terms of failure of the component itself, failure of seating, failure of fixation, failure of the glenoid bone, and failure to effectively manage eccentric loading. An understanding of these modes of failure leads to strategies to minimize complications related to prosthetic glenoid arthroplasty.     

Accuracy of patient-specific instrumentation in anatomic and reverse total shoulder arthroplasty

Purpose:Glenoid component malposition is associated with poor function and early failure of both anatomic and reverse total shoulder arthroplasty. Glenoid positioning is challenging particularly in the setting of bone loss or deformity. Recently, the use of computer assistance has been shown to reduce implantation error. The aim of this study is to evaluate the accuracy of patient-specific instrumentation in cases of anatomic and reverse shoulder replacement in vivo.Methods:Twenty patients underwent total shoulder arthroplasty using a computed tomography (CT)-based patient-specific instrumentation (PSI) system, ten anatomic and ten reverse. Preoperative three-dimensional digital templating of glenoid component position was undertaken and surgery then performed using a custom-made guide. Postoperative CT scans were used to compare final implanted component position to the preoperatively planned position in the same patient.Results:Final component position and orientation closely reflected the preoperatively templated position. Mean deviation in the glenoid version from planned was 1.8° ±1.9° (range, 0.1°–7.3°). Mean deviation in inclination was 1.3° ±1.0° (range, 0.2°–4.5°). Mean deviation in position on the glenoid face was 0.5 ± 0.3 mm (range, 0.0–1.3 mm) in the anteroposterior plane and 0.8 ± 0.5 mm (range, 0.0–1.9 mm) in the superoinferior plane. Actual achieved version was within 7° of neutral in all cases except for one where it was deliberately planned to be outside of this range.Conclusion:PSI in both anatomic and reverse shoulder arthroplasty is highly accurate in guiding glenoid component implantation in vivo. The system can reliably correct bony deformity.     

Evolution of the reverse total shoulder prosthesis

Over the last decade, reverse total shoulder arthroplasty has gained significant popularity due to its ability to address difficult reconstructive shoulder problems that could not be adequately treated in the past. The concept of the reverse shoulder prosthesis was introduced in the 1970s, but the initial attempts were associated with high complication and implant failure rates. The pioneering work of Paul Grammont (shifting the center of rotation medially and distally) and the development of the DELTA prosthesis have been fundamental to all subsequent reverse shoulder arthroplasty systems. These semiconstrained prostheses utilize the deltoid to improve function and stability of the shoulder joint by coupling a convex glenoid with a concave humeral component. Modern generations of reverse shoulder prosthesis continue to evolve on the fundamentals of Grammont. Though results of these new prosthesis demonstrate promising outcomes, many controversies and challenges continue to be refined. An historical review of the evolution of reverse shoulder arthroplasty is presented, as well as the currently expanding indications for its application.     

Anatomic total shoulder arthroplasty for severe glenoid bone loss: Still a viable option

Anatomic total shoulder arthroplasty has been the gold standard for glenohumeral osteoarthritis without rotator cuff tear. There is a subset of patients with severe glenoid bone loss and glenoid retroversion that have predictably worse outcomes with component loosing and posterior instability, making reverse shoulder arthroplasty an attractive solution. Although reverse shoulder arthroplasty solves many issues with glenoid component loosing, it has concerns of higher complication rates and reduced functional outcomes. With a deeper understanding of biomechanics, there are several strategies including augmented glenoid components to make anatomic total shoulder arthroplasty a more viable option for severe glenoid bone loss.     

Trabecular metal fixation: A new chemical concoction

Secure fixation of metal prosthesis to bone has always been a challenge. Bone cement has been a great help in achieving this goal, but there can be complications, such as cement loosening and breakage. Therefore, it is reasonable to consider types of coating on a metal surface that will allow bone ongrowth or a type of metal (tantalum) that will allow bone ingrowth as it is a porous scaffold. Furthermore the stiffness of tantalum is between subchondral bone and cortical bone, which also promotes ingrowth. This metal can be overlayed on other metal or used by itself as an implant. In primary osteoarthritis of the glenohumeral joint, it can be used for both the humeral and glenoid components allowing for a cementless prosthesis. Thus the complications from the use of bone cement can be avoided. Tantalum can also be used with a reverse prosthesis. It is especially important for the glenoid baseplate component as it will take away stress from the screws that are used for early fixation. Tantalum is also useful in the revision setting where there is bone loss and secure fixation is needed to the remaining bone. Tantalum has been used in the shoulder for more than 5 years successfully and longer in the hip and knee.     

Optimizing glenosphere position and fixation in reverse shoulder arthroplasty, Part Two: The three-column concept

Scapular geometry is complex, and a screw-placement technique for optimizing glenoid component fixation with an Aequalis Reversed Shoulder Prosthesis (Tornier, Inc., Edina, MN) has not yet been described. Ten cadaveric human scapulae were implanted with 2 types of reverse arthroplasty baseplates, 1 with fixed-angle locking screw holes and 1 with multidirectional locking screw holes. Optimal screw placement was defined as that which maximized screw length, accomplished far cortical fixation, and attained screw purchase in good bone stock. An anterior cruciate ligament drill guide was used to find the ideal trajectory for each screw. Trajectory angles of the screws relative to the face of the baseplate are presented for what we believe is best possible fixation. Awareness of the 3 major columns of scapular bone (the base of coracoid, the spine, and the pillar) and utilization of a baseplate with variable-angle locking screws will allow optimal initial fixation of the glenosphere.     

Clinical application of intraoperative O-arm navigation in reverse shoulder arthroplasty

BackgroundInaccurate fixation and positioning of the glenoid component using conventional techniques are problematic in reversed shoulder arthroplasty (RSA). Our objective was to investigate the accuracy of O-arm navigation of the glenoid component in RSA.MethodsThis retrospective case–control study comprised 2 groups of 25 patients who underwent reversed shoulder arthroplasty with or without intraoperative O-arm navigation. The intraoperative goal was to place the component neutrally in the glenoid in the axial plane and 10° inferiorly tilted in the scapular plane. Glenoid version angle and inclination were measured by computed tomography obtained preoperatively and a year postoperatively. Operative time, intraoperative bleeding, and the presence of postoperative complications were recorded.ResultsCompared with the ideal, the range of error for version was 7.3° (SD 3.6°) in the control group and 5.6° (SD 3.6°) in the navigated group (P = 0.278), and the range of error for inclination was 18.3° (SD 11.7°) in the control group and 4.9° (SD 3.8°) in the navigated group (P = 0.0004). The mean operative time was 164.6 (SD 21.2) min in the control group and 192.0 (SD 16.2) min in the navigated group (P = 0.001). The mean intraoperative bleeding was 201.0 (SD 37.0) mL in the control group and 185.3 (SD 35.6) mL in the navigated group (P = 0.300). There were no complications reported related to the intraoperative O-arm navigation.ConclusionO-arm navigation may be a useful tool for the placement with inferior tilt of the glenoid procedure in reversed shoulder arthroplasty.     

Bone preserving technique for reverse arthroplasty: The preferred management option for osteoarthritis with glenoid bone loss in patients 70 and older

Elderly patients with shoulder arthritis and glenoid bone loss represent a challenging patient population. Surgical treatment options include hemiarthroplasty, anatomic total shoulder arthroplasty (TSA) with bone grafting or augmentation, and reverse total shoulder arthroplasty (RSA). The RSA has multiple advantages compared to anatomic TSA, particularly in an older patient population with glenoid bone loss.RSA with an augmented glenoid baseplate is ideal for the treatment of patients who have glenoid bone loss. The augmented base plate has many advantages including bone preservation, longer central and peripheral screws, ability to dial the augment to match the region of bone deficiency, and lateralization to improve tensioning on the deltoid and rotator cuff. Additionally, a bone preserving RSA is possible with an augmented glenoid baseplate in patients with no glenoid bone loss.     

Metallosis‐Induced Conversion Shoulder Arthroplasty: A Unique Experience and Literature Review

Background

Total shoulder arthroplasty (TSA) can fail for several reasons, such as component loosening, periprosthetic fracture, instability, infection, soft tissue failure, or joint overstuffing. Severe metallosis without loose glenoid components after TSA may result in the need for revision to reverse TSA.

Case presentation

Four years before the current presentation, an 86-year-old woman suffered from right shoulder pain and swelling. The initial diagnosis was osteoarthritis of the shoulder joint, for which she underwent TSA. Four years later, she complained of shoulder joint pain, swelling, and limited range of motion. On sonography, subscapularis and supraspinatus tendon tears were identified. Plain radiographs and computed tomography (CT) scans showed metallosis around the shoulder joint. Due to the rocking horse mechanism, wear of the upper portion of the glenoid component and bearing caused a foreign-body reaction and severe metallosis around the joint. Due to a massive rotator cuff tear combined with glenoid component wear, the patient eventually underwent reverse TSA (RTSA) and was satisfied with the final results.

Conclusions

Severe metallosis due to glenoid component wear combined with a massive rotator cuff tear in TSA may cause the need for revision to RTSA.     

Long-term results of total shoulder arthroplasty following bone-grafting of the glenoid.

BACKGROUND: The marked loss of glenoid bone volume or alteration of glenoid version can affect glenoid component fixation in patients undergoing total shoulder arthroplasty. The purpose of this study was to evaluate the long-term results associated with the use of bone-grafting for restoration of glenoid volume and version at the time of total shoulder arthroplasty. METHODS: Twenty-one shoulders received an internally fixed, corticocancellous bone graft for the restoration of peripheral glenoid bone stock at the time of total shoulder arthroplasty between 1980 and 1989. Grafting was indicated when glenoid bone stock was insufficient to maintain adequate version or fixation of the prosthesis. Seventeen shoulders were available for follow-up; the average duration of follow-up for the thirteen shoulders that did not have prosthetic failure within the first two years was seventy months. Total shoulder arthroplasty was performed because of osteoarthritis in five shoulders, chronic anterior fracture-dislocation in five, capsulorrhaphy arthropathy in three, inflammatory arthritis in two, recurrent dislocation in one, and failure of a previous arthroplasty in one. All patients had some form of anterior or posterior instability preoperatively. There were five anterior and twelve posterior glenoid defects. Bone from the resected humeral head was used for grafting in fifteen shoulders, and bicortical iliac-crest bone was used in two. RESULTS: The average glenoid version after grafting was 4 degrees of retroversion, with an average correction of 33 degrees. The graft failed to maintain the original correction in three shoulders due to nonunion, dissolution, or shift. Five total shoulder replacements failed, necessitating glenoid revision at two to ninety-one months postoperatively. The failures were associated with recurrent massive cuff tears (one shoulder), persistent instability (two shoulders), improper component placement (one shoulder), and loss of graft fixation (one shoulder). There were no humeral component failures. According to the criteria of Neer et al., the functional result was rated as excellent in three shoulders, satisfactory in six, and unsatisfactory in eight. CONCLUSIONS: Despite the finding that eight shoulders had an unsatisfactory functional result at the time of longterm follow-up, corticocancellous grafting of the glenoid successfully restored glenoid version and volume in fourteen of the seventeen shoulders in the present study. Patients with glenoid deficiency often have associated glenohumeral instability, which may affect the results of total shoulder arthroplasty. Bone-grafting of the glenoid is a technically demanding procedure that can restore bone stock in patients with structural defects.     

Modification of the Traditional Open Latarjet Technique with the Use of Sutures and Cortical Buttons Instead of Screws

In this article we describe a modification of the open Latarjet technique, using sutures and cortical buttons, for the fixation of the coracoid. The transfer of the coracoid to the anterior glenoid is a popular technique used for complex shoulder instability. The technique is proven to be effective with consistently good results but complications have been reported related to the screws used for the fixation of the coracoid. Recent studies confirm that the suture-button technique for the fixation of the coracoid is biomechanically comparable to the screw fixation. The proposed technique combines the advantages of the open approach and avoids the use of metal screws, potentially minimizing hardware-related complications.     

Managing glenoid bone loss in total shoulder arthroplasty: Role of augmented patient-specific implants

Total shoulder arthroplasty has been shown to generate good to excellent results for patients with osteoarthritis and a functioning rotator cuff. However, a major complication after primary total shoulder arthroplasty is loosening of the glenoid component, which has been shown to be commonly associated with glenoid retroversion. This article highlights the importance of correcting the glenoid version and reviews various techniques, such as eccentric reaming, posterior bone grafting, reverse shoulder arthroplasty, and augmented glenoid implantation to address glenoid retroversion in the setting of total shoulder arthroplasty.     

CT scan evaluation of glenoid component fixation: a prospective study of 27 minimally cemented shoulder arthroplasties

Background

Glenoid component failure is the most common complication of total shoulder arthroplasty. It can be correlated with failure of the component itself to resist wear and deformation, failure of fixation or failure of the glenoid bone. Anchor Peg Glenoid component (Depuy^®) seems to have a higher bone fixation in biomechanical canine model: it is a all-polyethylene, concave component with one circumferentially fluted, central, interference-fit peg and three small cemented peripheral pegs.

Materials and methods

We realized a prospective study of Anchor Peg total shoulder arthroplasty, included 27 patients suffering from primary arthrosis or arthritis, without rotator cuff tear. A clinical and radiographic evaluation was performed at 3 months, 1 and 2 years; a CT scan was made in postoperative and analyzed central peg’s bone integration 1 year later.

Results

Improvement of postoperative Constant score and radiographic good results were correlated with satisfactory subjective results reported by patients. We observed radiolucent lines under glenoid component in 3 cases. Twenty-six CT scans were available at 1 year: it showed complete bone integration around the central peg in 21 cases and partial peripheral bone integration in four cases. Only one patient had any tissue integration around the peg, probably because of his implantation near cortical bone of scapular spine.

Discussion/conclusion

Long-term result of arthroplasty is correlated with glenoid durable fixation to underlying bone: this study shows higher fixation of glenoid component with bone integration of central peg. However, these results will have to be confirmed in a later revision.     

Glenoid Reconstruction in Revision Shoulder Arthroplasty

Failed shoulder arthroplasty associated with glenoid bony deficiency is a difficult problem. Revision surgery is complex with unpredictable outcome. We asked whether revision shoulder arthroplasty with glenoid bone grafting could lead to good outcome. We retrospectively reviewed 21 patients who underwent glenoid bone grafting using corticocancellous bone grafting or impaction grafting using cancellous bone graft. Three patients underwent revision TSA, five patients hemiarthroplasty, 10 patients hemiarthroplasty with biologic resurfacing of the glenoid, and three patients revision to reverse TSA. The patients had minimum 25 months followup (average, 45 months; range, 25-92 months). All patients had improvement in their range of motion and the Constant-Murley score. Most improvement occurred in patients with glenoid reimplantation. Patients who underwent revision reverse TSA had improvement in shoulder flexion but decrease in external rotation motion. We conclude revision shoulder arthroplasty with glenoid bone grafting can produce good short-term outcome and glenoid component reinsertion should be attempted whenever possible.