Placement Of Glenoid Component Research Articles

Paper #5 - Three-dimensional preoperative planning and patients specific instrumentation improve glenoid component positioning

Introduction: The use of three-dimensional (3-D) preoperative planning and patient specific surgical instrumentation (PSI) have been shown to improve surgeon accuracy in achieving desired glenoid implant position during total shoulder arthroplasty (TSA). While a number of PSI tools are currently available for glenoid guide pin placement in TSA, no studies to date have compared technologies against each other. The purpose of this study is to evaluate the use of 3-D preoperative planning with and without the use of different PSI tools in TSA to compare the accuracy of glenoid component placement across groups and to historical controls using standard two-dimensional (2-D) imaging and standard instrumentation. We hypothesize that the use of PSI technology will improve accuracy compared to standard instrumentation with standard 2-D imaging or 3-D preoperative planning alone, particularly in cases with more severe preoperative glenoid pathology.

Is a generic targeting guide useful for glenoid component placement in shoulder arthroplasty?

This study compared postoperative glenoid component version using traditional instrumentation to a generic glenoid targeting guide during total or reverse total shoulder arthroplasty. Glenoid component version was measured on postoperative radiographs of 184 shoulders (traditional, 109; targeting guide, 75). Demographics, preoperative imaging, and operative technique were identified from medical records. Absolute deviation from neutral version and standard deviations (SDs) were calculated. Average mean ± SD deviation in component version for the traditional technique group was 10° ± 7° compared with 9° ± 6° for the targeting guide group (P=.37; SD P=.12). No significant difference was noted based on operation, body mass index, preoperative version, or operative indication. For the last 30 shoulders in the targeting group, the absolute mean deviation was 6° compared with 11° in the first 30 of that group (P<.01) and 10° in the entire traditional group (P=.01). The SD in the last 30 shoulders in the targeting group was 5° compared with 7° in the first 30 in that group (P=.04) and 7° in the traditional group (P<.01). No significant difference in component accuracy was noted between the 2 techniques. The narrower SD in the targeting group, although not statistically significant, suggests less glenoid placement in the extremes of version. A learning curve was noted with the targeting guide, with significantly improved accuracy in later patients.

Testing of a Novel Guiding Device for Glenoid Component Placement in Total Shoulder Arthroplasty

Testing of a Novel Guiding Device for Glenoid Component Placement in Total Shoulder Arthroplasty

Shoulder arthroplasty in the presence of posterior glenoid bone loss.

➤ Chronic osteoarthritis of the glenohumeral joint, traumatic injury, post-reconstruction arthropathy, and developmental conditions such as glenoid dysplasia can result in posterior glenoid bone loss and excessive retroversion of the glenoid. Shoulder replacement in this setting is technically challenging and characterized by higher rates of complications and revisions.➤ Current options that should be considered for managing glenoid bone loss that results in >15° of retroversion include bone-grafting, augmented glenoid components, and reverse total shoulder replacement.➤ Asymmetric reaming is commonly used to improve version but should be limited to correction of 10° to 15° of retroversion in order to preserve subchondral bone.➤ Bone-grafting of glenoid defects has had mixed results and has been associated with graft-related complications, periprosthetic radiolucencies, and glenoid component failure; however, it provides a biologic option for patients with severe bone loss.➤ Implantation of an augmented polyethylene glenoid component offers the potential to improve version while preserving subchondral bone, but the procedure is technically demanding and without clinical follow-up data at this point.➤ Reverse total shoulder arthroplasty offers improved fixation and stability compared with an anatomic prosthesis for elderly patients with severe glenoid bone loss but is associated with a high complication rate.➤ Glenoid dysplasia is defined as a deformity that results in >25° of glenoid retroversion. Advanced imaging needs to be obtained in order to ensure enough glenoid bone stock is present to allow anatomic glenoid component placement.

Patient-specific targeting guides compared with traditional instrumentation for glenoid component placement in shoulder arthroplasty: a multi-surgeon study in 70 arthritic cadaver specimens

The purpose of this study was to compare the accuracy of patient-specific guides for total shoulder arthroplasty (TSA) with traditional instrumentation in arthritic cadaver shoulders. We hypothesized that the patient-specific guides would place components more accurately than standard instrumentation. Seventy cadaver shoulders with radiographically confirmed arthritis were randomized in equal groups to 5 surgeons of varying experience levels who were not involved in development of the patient-specific guidance system. Specimens were then randomized to patient-specific guides based off of computed tomography scanning, standard instrumentation, and anatomic TSA or reverse TSA. Variances in version or inclination of more than 10° and more than 4 mm in starting point were considered indications of significant component malposition. TSA glenoid components placed with patient-specific guides averaged 5° of deviation from the intended position in version and 3° in inclination; those with standard instrumentation averaged 8° of deviation in version and 7° in inclination. These differences were significant for version (P = .04) and inclination (P = .01). Multivariate analysis of variance to compare the overall accuracy for the entire cohort (TSA and reverse TSA) revealed patient-specific guides to be significantly more accurate (P = .01) for the combined vectors of version and inclination. Patient-specific guides also had fewer instances of significant component malposition than standard instrumentation did. Patient-specific targeting guides were more accurate than traditional instrumentation and had fewer instances of component malposition for glenoid component placement in this multi-surgeon cadaver study of arthritic shoulders. Long-term clinical studies are needed to determine if these improvements produce improved functional outcomes.

Patient-specific Targeting Guides for Glenoid Component Placement in Shoulder Arthroplasty

Patient-specific Targeting Guides for Glenoid Component Placement in Shoulder Arthroplasty

Three-dimensional planning and use of patient-specific guides improve glenoid component position: an in vitro study

Glenoid component positioning is a key factor for success in total shoulder arthroplasty. Three-dimensional (3D) measurements of glenoid retroversion, inclination, and humeral head subluxation are helpful tools for preoperative planning. The purpose of this study was to assess the reliability and precision of a novel surgical method for placing the glenoid component with use of patient-specific templates created by preoperative surgical planning and 3D modeling. A preoperative computed tomography examination of cadaveric scapulae (N = 18) was performed. The glenoid implants were virtually placed, and patient-specific guides were created to direct the guide pin into the desired orientation and position in the glenoid. The 3D orientation and position of the guide pin were evaluated by performing a postoperative computed tomography scan for each scapula. The differences between the preoperative planning and the achieved result were analyzed. The mean error in 3D orientation of the guide pin was 2.39°, the mean entry point position error was 1.05 mm, and the mean inclination angle error was 1.42°. The average error in the version angle was 1.64°. There were no technical difficulties or complications related to use of patient-specific guides for guide pin placement. Quantitative analysis of guide pin positioning demonstrated a good correlation between preoperative planning and the achieved position of the guide pin. This study demonstrates the reliability and precision of preoperative planning software and patient-specific guides for glenoid component placement in total shoulder arthroplasty.

Application of the fulcrum axis to estimate the central scapular axis

Glenoid resurfacing can be a challenging component of total shoulder arthroplasty when significant glenoid retroversion or deformity is present. The purpose of this study was to determine whether a newly designed glenoid-targeting guide using the parallel relationship between glenoid version and an anatomic fulcrum axis could accurately estimate the central axis of the scapula. Three orthopaedic surgeons used a newly designed glenoid-targeting guide to place a guide pin into 6 normal Sawbones scapulae (Pacific Research Laboratories, Vashon Island, WA, USA), 6 retroverted Sawbones scapulae, 8 cadaveric scapular specimens, and 5 cadaveric shoulder specimens. Angles of deviation from the central scapular axis and from perpendicular to the fulcrum axis were measured. The mean pin deviation angle from the central scapular axis and the mean fulcrum deviation angle for the normal Sawbones scapulae were 1.7° (SD, 1.2°) and 2.1° (SD, 1.5°), respectively. For altered retroverted Sawbones scapulae, the mean deviation angles were 1.8° (SD, 1.2°) and 2.8° (SD, 1.6°), respectively. The combined mean pin deviation angle and mean fulcrum deviation angle for cadaveric shoulder specimens were 2.8° (SD, 3.3°) and 2.3° (SD, 2.3°), respectively. The surgeons' results did not differ significantly whether using Sawbones models, cadaveric scapular specimens, or cadaveric shoulder specimens. A glenoid-targeting guide based on the relationship of the fulcrum axis and glenoid version can be used to accurately estimate the central scapular axis. Such a tool can be accurate and reliable intraoperatively, aiding in glenoid component placement to within 5° of ideal version, irrespective of glenoid deformity.

Guidelines for the selection of optimal glenoid augment size for moderate to severe glenohumeral osteoarthritis

Total shoulder arthroplasty is technically demanding in regard to implantation of the glenoid component, especially in the setting of increased glenoid deformity and posterior glenoid wear. Augmented glenoid implants are an important and innovative option; however, there is little evidence accessible to surgeons to guide in the selection of the appropriate size augmented glenoid. Solid computer models of commercially available augmented glenoid components (+3, +5, +7) contained within the software allowed placement of the best fit glenoid component within the three-dimensional reconstruct of each patient's scapula. Peg perforation, amount of bone reamed, and amount of medialization were recorded for each augment size. There was strong correlation between the medialization of the joint line and the glenoid retroversion for each augmented component at neutral correction and correction to 6° of retroversion. At neutral, the range of retroversion that restored the anatomic joint line was -3° to -17° with use of the +3 augmented glenoid, -5° to -24° with the +5 augmented glenoid, and -9° to -31° with the +7 augmented glenoid. At 6° of retroversion, the range of retroversion that restored the anatomic joint line was -4° to -21° with use of the +3 augmented glenoid, -7° to -27° with the +5 augmented glenoid, and -9° to -34° with the +7 augmented glenoid. There was a strong correlation between glenoid retroversion and medialization for all augment sizes, supporting the recommendation for glenoid retroversion as the primary guide in selecting the amount of augmentation.

Decreased scapular notching with lateralization and inferior baseplate placement in reverse shoulder arthroplasty with high humeral inclination.

Background:Scapular notching is a radiographic finding of unknown clinical significance following reverse total shoulder arthroplasty (RTSA). The purpose of this study was to determine how baseplate position affects the incidence of scapular notching and measure the clinical outcomes.Hypothesis:We hypothesized that low base plate position on the glenoid and new prosthesis design with a higher humeral inclination angle would decrease the incidence of notching at 2 years follow-up.Materials and methods:A total of 54 patients with an average follow-up of 30 months met inclusion criteria and underwent radiographic analysis of scapular notching and radiographic measures to determine glenoid component placement. Clinical measures including visual analog score, American Shoulder and Elbow Surgeons (ASES) scores, and range of motion (ROM) were prospectively collected.Results:Thirty-nine of the 54 patients had no notching. 7 had Grade 1 notching, 7 had Grade 2 notching, one had Grade 3, and one had Grade 4 notching. Notching was associated with higher placement of the glenoid component as measured by peg-glenoid rim distance and base plate distance. All patients with no evidence of notching at 1-year, continued to have no notching after multi-year follow-up. Clinical outcome measures including ASES scores, ROM, and visual analog pain scores were improved at follow-up.Conclusion:We concluded that lower neck-shaft angle and low baseplate positioning led to a low incidence of significant scapular notching as only 6 out of 57 (16%) patients had notching Grade 2 and above. At short-term follow-up, this RTSA results in excellent clinical outcomes and a significantly lower scapular notching rate than traditional techniques.

Accuracy of Glenoid Component Placement in Total Shoulder Arthroplasty and Its Effect on Clinical and Radiological Outcome in a Retrospective, Longitudinal, Monocentric Open Study

BackgroundThe success of Total Shoulder Arthroplasty (TSA) is believed to depend on the restoration of the natural anatomy of the joint and a key development has been the introduction of modular humeral components to more accurately restore the patient’s anatomy. However, there are no peer-reviewed studies that have reported the degree of glenoid component mal-position achieved in clinical practice and the clinical outcome of such mal-position. The main purpose of this study was to assess the accuracy of glenoid implant positioning during TSA and to relate it to the radiological (occurrence of radiolucent lines and osteolysis on CT) and clinical outcomes.Methods68 TSAs were assessed with a mean follow-up of 38+/−27 months. The clinical evaluation consisted of measuring the mobility as well as of the Constant Score. The radiological evaluation was performed on CT-scans in which metal artefacts had been eliminated. From the CT-scans radiolucent lines and osteolysis were assessed. The positions of the glenoid and humeral components were also measured from the CT scans.ResultsFour position glenoid component parameters were calculated The posterior version (6°±12°; mean ± SD), the superior tilt (12°±17°), the rotation of the implant relative to the scapular plane (3°±14°) and the off-set distance of the centre of the glenoid implant from the scapular plane (6±4 mm). An inferiorly inclined implant was found to be associated with higher levels of radiolucent lines while retroversion and non-neutral rotation were associated with a reduced range of motion.Conclusionthis study demonstrates that glenoid implants of anatomic TSA are poorly positioned and that this malposition has a direct effect on the clinical and radiological outcome. Thus, further developments in glenoid implantation techniques are required to enable the surgeon to achieve a desired implant position and outcome.

Comparison of Patient-Specific Instruments with Standard Surgical Instruments in Determining Glenoid Component Position

Glenoid component malposition for anatomic shoulder replacement may result in complications. The purpose of this study was to define the efficacy of a new surgical method to place the glenoid component. Thirty-one patients were randomized for glenoid component placement with use of either novel three-dimensional computed tomographic scan planning software combined with patient-specific instrumentation (the glenoid positioning system group), or conventional computed tomographic scan, preoperative planning, and surgical technique, utilizing instruments provided by the implant manufacturer (the standard surgical group). The desired position of the component was determined preoperatively. Postoperatively, a computed tomographic scan was used to define and compare the actual implant location with the preoperative plan. In the standard surgical group, the average preoperative glenoid retroversion was -11.3° (range, -39° to 17°). In the glenoid positioning system group, the average glenoid retroversion was -14.8° (range, -27° to 7°). When the standard surgical group was compared with the glenoid positioning system group, patient-specific instrumentation technology significantly decreased (p < 0.05) the average deviation of implant position for inclination and medial-lateral offset. Overall, the average deviation in version was 6.9° in the standard surgical group and 4.3° in the glenoid positioning system group. The average deviation in inclination was 11.6° in the standard surgical group and 2.9° in the glenoid positioning system group. The greatest benefit of patient-specific instrumentation was observed in patients with retroversion in excess of 16°; the average deviation was 10° in the standard surgical group and 1.2° in the glenoid positioning system group (p < 0.001). Preoperative planning and patient-specific instrumentation use resulted in a significant improvement in the selection and use of the optimal type of implant and a significant reduction in the frequency of malpositioned glenoid implants. Novel three-dimensional preoperative planning, coupled with patient and implant-specific instrumentation, allows the surgeon to better define the preoperative pathology, select the optimal implant design and location, and then accurately execute the plan at the time of surgery.

Effect of glenoid deformity on glenoid component placement in primary shoulder arthroplasty

Malposition of the glenoid component can result in premature component loosening or instability. This study was designed to test the ability of an experienced shoulder surgeon to position the glenoid component using standard preoperative planning and surgical bone preparation. Thirteen patients having primary total shoulder arthroplasty were evaluated using 3-dimensional surgical simulator. Ideal version was considered to have version as close to perpendicular to the plane of the scapula, with complete contact of the back side of the component on glenoid bone and maintenance of the center peg of the component within bone. The average retroversion angle was 13° (mean, standard deviation [SD] 12°), with a range of 1-42°. In 7 of these 13 cases, preoperative glenoid retroversion was greater or equal to 10°. In 3 cases, the component was malpositioned with greater than 10° of ideal version. In cases with less than 10° of preoperative retroversion, the glenoid component was placed within 10° of ideal version in all cases. Traditional methods to correct moderate to severe glenoid deformity and place the glenoid component within 5° of the ideal position are not consistent. Optimal glenoid component placement can be achieved when there is minimal bone deformity. Retroversion greater or equal to 20° makes it difficult to place a pegged glenoid component perpendicular to the plane of the scapula by asymmetric reaming without center peg perforation.

Glenoid morphology in reverse shoulder arthroplasty: Classification and surgical implications

A great challenge in reverse shoulder arthroplasty is the wide variation in glenoid morphology that adds uncertainties in glenoid component placement. The purpose of this study was to classify glenoid morphology and examining its effect on possible glenoid component fixation. The morphology of 216 glenoids was classified into normal and abnormal with subgroups defined by erosion sites. Six anatomic and 2 surgical parameters were compared among the classified groups. Plain radiographs or 2-dimensional (2D) computed tomography (CT) scans showed 62.5% of glenoids were normal and 37.5% were abnormal, with further subclassification of abnormal in posterior (17.6%), superior (9.3%), global (6.5%), and anterior (4.2%) erosions using 3D CT models. The standard centerline became significantly shorter in abnormal (19.6 +/- 9.1 mm) than in normal (28.6 +/- 4.1 mm, P < .0001) glenoids. Alternatively, the spine centerline provided longer bony distance in abnormal glenoids (34.9 +/- 17.0 mm). Abnormal glenoid morphology also reduced peripheral screw placement area by 42% and limited it to the anterior and inferior quadrants. Glenoid morphology of the rotator cuff deficient shoulder can be reliably classified using this classification system consisting of normal and abnormal, which included 4 subgroups of posterior, superior, global, and anterior erosions. Abnormal glenoid morphology was shown to have a significant effect on anatomical and surgical factors which can necessitate adjustments in surgical technique for reverse shoulder arthroplasty. Basic Science Study.

Improved accuracy of computer assisted glenoid implantation in total shoulder arthroplasty: An in-vitro randomized controlled trial

Glenoid replacement is challenging due to the difficult joint exposure and visualization of anatomical reference landmarks. Improper positioning of the glenoid component or inadequate correction of the retroversion using currently available instrumentation may lead to early failure. The objective of this study was to evaluate a computer-assisted technique to achieve a more accurate placement of the glenoid component compared to traditional techniques. Sixteen paired cadaveric shoulders were randomized to either traditional or computer-assisted glenoid implantation. Preoperative planning consisting of CT scanning with 3-dimensional image modeling of the shoulder specimens and intraoperative tracking with real-time feedback provided to the surgeon was employed in the computer-assisted group. A validated, previously published, standardized protocol for tracking the orientation of the glenoid in space using 3 glenoid surface landmarks was employed. All phases of glenoid implantation (initial guide pin insertion, reaming, drilling of the peg holes, and final component implantation) were tracked and recorded by the computer. A post-implantation CT scan was performed in both groups to compare how accurately the implants were placed. The computer-assisted technique was more accurate in achieving the correct version during all phases of glenoid implantation and as measured on the post-implantation CT scan (P < .05). The largest errors with traditional glenoid implantation were observed during drilling and, more so, during reaming. The trend was to overly retrovert the glenoid. Computer assisted navigation results in a more accurate glenoid component placement relative to traditional techniques. Basic Science Study.

Projection of the Glenoid Center Point Within the Glenoid Vault

Correct identification of the center point of the glenoid surface guides glenoid component placement. It is unknown whether the center point on the glenoid surface corresponds to the center of the glenoid vault at the medial extent of the glenoid prosthesis. We reviewed 20 consecutive computed tomography scans obtained preoperatively in patients with primary osteoarthritis. A glenoid center point was chosen on the glenoid surface and then projected back into the glenoid vault along the scapular axis and perpendicular to glenoid inclination. The difference from the projection of the glenoid surface center point to the center point at a 1.5-cm depth into the glenoid vault was then measured. The mean deviation of the glenoid center point at a depth of 1.5 cm from the center point at the glenoid articular surface was 1.7 mm anterior and 3.9 mm inferior. The most common deviation of the center point of the glenoid vault at the projected medial limit of the glenoid prosthesis was slightly anterior and inferior to the center point on the glenoid surface. Identifying the center of the glenoid surface coupled with alignment of the glenoid prosthesis in neutral version and anatomic inclination provides a reliable means to guide placement of glenoid components.

Glenoid revision surgery after total shoulder arthroplasty

Forty-eight shoulders that underwent glenoid component revision surgery were reviewed at a mean of 4.9 years (range, 2 to 12 years). The indications for surgery were glenoid component loosening in 29 shoulders, glenoid implant failure in 14 shoulders, and glenoid component malposition or wear leading to instability in 5 shoulders. Seventeen shoulders had associated instability. Thirty shoulders underwent implantation of a new glenoid component and 18 underwent removal of the component and bone grafting for bone deficiencies. There was significant pain relief, improvement in active elevation and external rotation, and satisfaction with revision glenoid surgery (P < .05). Patients without a glenoid component were significantly less satisfied with the procedure than those patients who underwent reimplantation of a glenoid component (P = .01). Satisfactory pain relief was achieved in 86% of patients with a new glenoid component and 66% of patients who underwent glenoid component removal. Seven shoulders with a new glenoid component (2 for glenoid loosening) and 5 who underwent removal without reimplantation (3 for painful glenoid arthritis) required re-revision surgery. Eleven of the 17 patients with instability were stable at the most recent follow-up. The data from this study suggest that at the time of revision glenoid surgery, patients who have placement of a glenoid component have a higher degree of satisfaction than those undergoing glenoid component removal. Patients who continue to have pain after bone grafting without placement of a component may be candidates for glenoid component placement after graft consolidation. (J Shoulder Elbow Surg 2001;10:217-24.)