Total shoulder arthroplasty with an all-polyethylene pegged bone-ingrowth glenoid component: a clinical and radiographic outcome study

Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?

BACKGROUND

While glenoid retroversion and posterior humeral head decentering are common preoperative features of severely arthritic glenohumeral joints, the relationship of postoperative glenoid component retroversion to the clinical results of total shoulder arthroplasty (TSA) is unclear. Studies have indicated concern for inferior outcomes when glenoid components are inserted in 15° or more retroversion.

QUESTIONS/PURPOSES

In a population of patients undergoing TSA in whom no specific efforts were made to change the version of the glenoid, we asked whether at 2 years after surgery patients having glenoid components implanted in 15° or greater retroversion had (1) less improvement in the Simple Shoulder Test (SST) score and lower SST scores; (2) higher percentages of central peg lucency, higher Lazarus radiolucency grades, higher mean percentages of posterior decentering, and more frequent central peg perforation; or (3) a greater percentage having revision for glenoid component failure compared with patients with glenoid components implanted in less than 15° retroversion.

METHODS

Between August 24, 2010 and October 22, 2013, information for 201 TSAs performed using a standard all-polyethylene pegged glenoid component were entered in a longitudinally maintained database. Of these, 171 (85%) patients had SST scores preoperatively and between 18 and 36 months after surgery. Ninety-three of these patients had preoperative radiographs in the database and immediate postoperative radiographs and postoperative radiographs taken in a range of 18 to 30 months after surgery. Twenty-two patients had radiographs that were inadequate for measurement at the preoperative, immediate postoperative, or latest followup time so that they could not be included. These excluded patients did not have substantially different mean age, sex distribution, time of followup, distribution of diagnoses, American Society of Anesthesiologists class, alcohol use, smoking history, BMI, or history of prior surgery from those included in the analysis. Preoperative retroversion measurements were available for 11 (11 shoulders) of the 22 excluded patients. For these 11 shoulders, the mean (± SD) retroversion was 15.8° ± 14.6°, five had less than 15°, and six had more than 15° retroversion. We analyzed the remaining 71 TSAs, comparing the 21 in which the glenoid component was implanted in 15° or greater retroversion (mean ± SD, 20.7° ± 5.3°) with the 50 in which it was implanted in less than 15° retroversion (mean ± SD, 5.7° ± 6.9°). At the 2-year followup (mean ± SD, 2.5 ± 0.6 years; range, 18-36 months), we determined the latest SST scores and preoperative to postoperative improvement in SST scores, the percentage of maximal possible improvement, glenoid component radiolucencies, posterior humeral head decentering, and percentages of shoulders having revision surgery. Radiographic measurements were performed by three orthopaedic surgeons who were not involved in the care of these patients. The primary study endpoint was the preoperative to postoperative improvement in the SST score.

RESULTS

With the numbers available, the mean (± SD) improvement in the SST (6.7 ± 3.6; from 2.6 ± 2.6 to 9.3 ± 2.9) for the retroverted group was not inferior to that for the nonretroverted group (5.8 ± 3.6; from 3.7 ± 2.5 to 9.4 ± 3.0). The mean difference in improvement between the two groups was 0.9 (95% CI, - 2.5 to 0.7; p = 0.412). The percent of maximal possible improvement (%MPI) for the retroverted glenoids (70% ± 31%) was not inferior to that for the nonretroverted glenoids (67% ± 44%). The mean difference between the two groups was 3% (95% CI, - 18% to 12%; p = 0.857). The 2-year SST scores for the retroverted (9.3 ± 2.9) and the nonretroverted glenoid groups (9.4 ± 3.0) were similar (mean difference, 0.2; 95% CI, - 1.1 to 1.4; p = 0.697). No patient in either group reported symptoms of subluxation or dislocation. With the numbers available, the radiographic results for the retroverted glenoid group were similar to those for the nonretroverted group with respect to central peg lucency (four of 21 [19%] versus six of 50 [12%]; p = 0.436; odds ratio, 1.7; 95% CI, 0.4-6.9), average Lazarus radiolucency scores (0.5 versus 0.7, Mann-Whitney U p value = 0.873; Wilcoxon rank sum test W = 512, p value = 0.836), and the mean percentage of posterior humeral head decentering (3.4% ± 5.5% versus 1.6% ± 6.0%; p = 0.223). With the numbers available, the percentage of patients with retroverted glenoids undergoing revision (0 of 21 [0%]) was not inferior to the percentage of those with nonretroverted glenoids (three of 50; [6%]; p = 0.251).

CONCLUSION

In this small series of TSAs, postoperative glenoid retroversion was not associated with inferior clinical results at 2 years after surgery. This suggests that it may be possible to effectively manage arthritic glenohumeral joints without specific attempts to modify glenoid version. Larger, longer-term studies will be necessary to further explore the results of this approach.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Analysis of complication rates following perioperative transfusion in shoulder arthroplasty

BACKGROUND

Postoperative anemia requiring a blood transfusion is not uncommon following anatomic total shoulder arthroplasty (TSA) or reverse total shoulder arthroplasty (RTSA). However, the potential complications in patients undergoing transfusion after shoulder arthroplasty remain unclear. The goal of this study was to examine the postoperative outcomes of patients receiving blood transfusions following TSA and RTSA.

METHODS

Using the Medicare Standard Analytic Files database, we identified all patients undergoing TSA or RTSA between 2005 and 2010. Using International Classification of Diseases, Ninth Revision, Clinical Modification and Current Procedural Terminology codes, we identified the procedure, transfusion status, comorbidities, and postoperative complications of interest. Odds ratios and 95% confidence intervals were calculated.

RESULTS

We identified 7,794 patients who received a perioperative blood transfusion following TSA or RTSA, as well as 34,293 age- and gender-matched controls, during the study period. Patients who received a perioperative transfusion had statistically significantly higher rates of myocardial infarction, pneumonia, systemic inflammatory response syndrome or sepsis, venous thromboembolic events, and cerebrovascular accidents at all time points in question. Patients who received a blood transfusion also showed an increased incidence of surgical complications, including periprosthetic infection and mechanical complications, up to 2 years postoperatively.

CONCLUSION

To our knowledge, this represents the largest study to examine the relationship between the need for perioperative blood transfusion and postoperative medical and surgical outcomes following TSA and RTSA. The results observed in this study highlight the importance of preoperative counseling and medical optimization prior to shoulder arthroplasty, particularly in patients with preoperative anemia or multiple medical comorbidities.

A comparison of onlay versus inlay glenoid component loosening in total shoulder arthroplasty

BACKGROUND

Glenoid component loosening is common in total shoulder arthroplasty (TSA), often resulting from the mechanical interaction of glenohumeral components. This cadaveric study was performed to evaluate and to compare commercially available onlay and inlay glenoid prosthetic designs with respect to loading characteristics and loosening.

METHODS

Sixteen prescreened cadaveric shoulders (8 matched pairs) underwent either onlay or inlay TSA. We created a custom glenohumeral loading model and used cycles of 5 mm anterior-posterior humeral translation to simulate a rocking-horse loosening mechanism for all testing. Articular TekScan measurements were performed with 9.1 kg (88.9 N) of glenohumeral compression before and after TSA. Fatigue testing was performed with 34.0 kg (333.6 N) of glenohumeral compression using high-definition video to document gross glenoid loosening. Testing ended with gross loosening or a maximum of 4000 cycles. Mean contact area, pressure, and joint reaction force were used to compare the 2 glenoid designs.

RESULTS

In both implant types, contact area decreased and pressure increased after TSA (P < .0001). Force increased at the onlay component edge only (P = .0012) compared with native glenoid testing. Force was greater in the onlay vs. the inlay implants (P < .0001). During fatigue testing, all onlay glenoid components exhibited gross loosening at a mean of 1126 cycles (range, 749-1838), whereas none of the inlay glenoid components exhibited gross loosening (P < .0001).

CONCLUSION

The inlay glenoid implant exhibited biomechanical characteristics favoring stability and decreased loosening compared with the onlay glenoid implant in this cadaveric model.

Plication of the posterior capsule for intraoperative posterior instability during anatomic total shoulder arthroplasty

BACKGROUND

Restoration of soft tissue balance for intraoperative posterior instability during anatomic total shoulder arthroplasty (TSA) is particularly difficult. The effectiveness of posterior capsular plication (PCP) in restoring soft tissue balance is largely unknown. The purpose of this study was to report the outcomes, complications, and reoperations of primary TSA in which a PCP was performed to correct excessive intraoperative posterior subluxation.

METHODS

Thirty-eight shoulders (37 patients) underwent PCP for intraoperative posterior instability during anatomic TSA. The mean (standard deviation) age was 68 (10) years, and the median (range) clinical and radiographic follow-up periods were 60 (10-154) and 48 (1.5-154) months, respectively. A retrospective chart review was conducted to obtain clinical and radiographic data.

RESULTS

TSA resulted in significant improvements in pain and range of motion. The mean (standard deviation) Simple Shoulder Test and American Shoulder and Elbow Surgeons scores were 9.4 (2.7) and 81.1 (19.8), respectively. PCP resulted in restoration of soft tissue balance in 27 shoulders (71%). The remaining 11 shoulders had evidence of posterior subluxation, including posterior dislocation in 2 shoulders. Revision surgery was performed in only 3 shoulders (7.9%), all for instability. However, there was a high rate of radiographic glenoid component loosening (12 shoulders, 32%). Overall results were excellent in 24 (63.2%), satisfactory in 10 (26.3%), and unsatisfactory in 4 (10.5%) shoulders. Recurrence of posterior subluxation was associated with worse motion and strength as well as with a higher rate of glenoid loosening.

CONCLUSIONS

PCP seems to correct excessive intraoperative posterior subluxation in approximately two-thirds of the shoulders undergoing anatomic TSA. However, posterior subluxation does recur in the remaining third, and the overall rate of radiographic glenoid loosening is of concern.

Radiographic results of augmented all-polyethylene glenoids in the presence of posterior glenoid bone loss during total shoulder arthroplasty

BACKGROUND

Chronic osteoarthritis can result in glenohumeral subluxation and loss of posterior glenoid bone. This can alter normal glenohumeral biomechanics and affect the stress placed on the glenoid implant after total shoulder arthroplasty. This study evaluated the clinical and radiographic results of an augmented all-polyethylene glenoid for the treatment of glenoid osteoarthritis in the presence of posterior glenoid bone loss and determined whether any failures or complications occurred with short-term follow-up.

METHODS

During a 2-year period, 21 patients were treated with an augmented glenoid for an index diagnosis of osteoarthritis with a biconcave glenoid and average posterior glenoid bone loss of 4.7 mm. Clinical outcomes were recorded for the American Shoulder and Elbow Surgeons Shoulder Assessment, Simple Shoulder Test, and active motion. Radiographic analysis included glenoid version, humeral head subluxation, component seating, ingrowth, and loosening.

RESULTS

Significant improvements were demonstrated for American Shoulder and Elbow Surgeons Shoulder Assessment (52.3), Simple Shoulder Test (8.1), forward flexion (50°), external rotation (32°), and pain. Radiographic improvements were found for glenoid version (12°), humeral scapular alignment (23%), and humeral glenoid alignment (8%). Central peg ingrowth was demonstrated in all patients, and complete component seating was achieved in 19 patients. No complications were encountered, and no clinical or radiographic failures were identified.

CONCLUSION

Augmented polyethylene glenoid components demonstrated improved clinical outcome, without implant failure or complications, during short-term follow-up.

What Factors are Predictive of Patient-reported Outcomes? A Prospective Study of 337 Shoulder Arthroplasties

BACKGROUND

Although shoulder arthroplasties generally are effective in improving patients' comfort and function, the results are variable for reasons that are not well understood.

QUESTIONS/PURPOSES

We posed two questions: (1) What factors are associated with better 2-year outcomes after shoulder arthroplasty? (2) What are the sensitivities, specificities, and positive and negative predictive values of a multivariate predictive model for better outcome?

METHODS

Three hundred thirty-nine patients having a shoulder arthroplasty (hemiarthroplasty, arthroplasty for cuff tear arthropathy, ream and run arthroplasty, total shoulder or reverse total shoulder arthroplasty) between August 24, 2010 and December 31, 2012 consented to participate in this prospective study. Two patients were excluded because they were missing baseline variables. Forty-three patients were missing 2-year data. Univariate and multivariate analyses determined the relationship of baseline patient, shoulder, and surgical characteristics to a "better" outcome, defined as an improvement of at least 30% of the maximal possible improvement in the Simple Shoulder Test. The results were used to develop a predictive model, the accuracy of which was tested using a 10-fold cross-validation.

RESULTS

After controlling for potentially relevant confounding variables, the multivariate analysis showed that the factors significantly associated with better outcomes were American Society of Anesthesiologists Class I (odds ratio [OR], 1.94; 95% CI, 1.03-3.65; p = 0.041), shoulder problem not related to work (OR, 5.36; 95% CI, 2.15-13.37; p < 0.001), lower baseline Simple Shoulder Test score (OR, 1.32; 95% CI, 1.23-1.42; p < 0.001), no prior shoulder surgery (OR, 1.79; 95% CI, 1.18-2.70; p = 0.006), humeral head not superiorly displaced on the AP radiograph (OR, 2.14; 95% CI, 1.15-4.02; p = 0.017), and glenoid type other than A1 (OR, 4.47; 95% CI, 2.24-8.94; p < 0.001). Neither preoperative glenoid version nor posterior decentering of the humeral head on the glenoid were associated with the outcomes. The model predictive of a better result was driven mainly by the six factors listed above. The area under the receiver operating characteristic curve generated from the cross-validated enhanced predictive model was 0.79 (generally values of 0.7 to 0.8 are considered fair and values of 0.8 to 0.9 are considered good). The false-positive fraction and the true-positive fraction depended on the cutoff probability selected (ie, the selected probability above which the prediction would be classified as a better outcome). A cutoff probability of 0.68 yielded the best performance of the model with cross-validation predictions of better outcomes for 236 patients (80%) and worse outcomes for 58 patients (20%); sensitivity of 91% (95% CI, 88%-95%); specificity of 65% (95% CI, 53%-77%); positive predictive value of 92% (95% CI, 88%-95%); and negative predictive value of 64% (95% CI, 51%-76%).

CONCLUSIONS

We found six easy-to-determine preoperative patient and shoulder factors that were significantly associated with better outcomes of shoulder arthroplasty. A model based on these characteristics had good predictive properties for identifying patients likely to have a better outcome from shoulder arthroplasty. Future research could refine this model with larger patient populations from multiple practices.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Total shoulder arthroplasty for glenohumeral arthritis associated with posterior glenoid bone loss: results of an all-polyethylene, posteriorly augmented glenoid component

BACKGROUND

Posterior glenoid bone loss is commonly encountered in total shoulder arthroplasty (TSA). The purpose of our study is to report the clinical and radiographic findings of patients with a minimum of 2 years' follow-up treated with an all-polyethylene, augmented glenoid component.

METHODS

Twenty-two shoulders with posterior glenoid bone loss were treated by a single surgeon. All underwent primary TSA using a posteriorly augmented, all-polyethylene, stepped glenoid component. Outcome data included visual analog scale, Western Ontario Osteoarthritis of the Shoulder index, and Short Form 36 scores. Radiographic analysis was performed to evaluate bone-cement interface lucency, implant seating, and osseous integration of the central peg.

RESULTS

The mean follow-up period was 36 months. Average preoperative retroversion measured with computed tomography scan was 23.5°. In addition to statistically significant increases in forward flexion and external rotation, the visual analog scale score, Western Ontario Osteoarthritis of the Shoulder score, and Short Form 36 physical component summary score all improved significantly (P < .001). Twelve shoulders had osseous integration between the central-peg flanges, 6 had bone adjacent to the central-peg flanges but without identifiable osseous integration, and 1 showed osteolysis. The mean Lazarus score was 0.5. All glenoids had perfect seating scores. Two patients sustained a total of 3 episodes of prosthetic instability.

CONCLUSIONS

Early results of a posteriorly augmented, all-polyethylene, stepped prosthetic glenoid component to address posterior glenoid loss in TSA are encouraging. Continued evaluation will determine prosthetic longevity and maintained clinical improvement.

Total shoulder replacement using a bone ingrowth central peg polyethylene glenoid component: a prospective clinical and computed tomography study with short- to mid-term follow-up

AIM OF THE STUDY

To assess the clinical and computed tomography (CT) outcomes of shoulder replacement with a novel bone ingrowth all-polyethylene glenoid component (APGC).

METHODS

Twenty-eight patients (30 shoulders) with osteoarthritis, mean age 62.3 years (range, 45-75), were implanted with the novel component between 2011 and 2013. Patients were evaluated by active range of motion (ROM), Constant-Murley score (CMS), simple shoulder test (SST), X-rays, and multidetector CT at two months and at a mean follow-up of 31 months (range, 24-39). Early and late follow-up CT scans were available for 21/30 shoulders.

RESULTS

Median ROM increased from 105 to 160° for anterior elevation, from 100 to 160° for lateral elevation, from 20 to 40° for external rotation, and from 2 to 10 points for internal rotation (all p < 0.001). CMS rose from 30 to 80.5 points and SST from 2.5 to 11 (both p < 0.0001). None of the glenoid components migrated. Progressive radiolucency was seen in 28/30 shoulders. There was a strong correlation between greater bone ingrowth (median Arnold score: 7) and lower radiolucency score (median Yian score: 2) at the last follow-up (p < 0.001). Osteolysis around the central peg was seen in two shoulders. There was no correlation between clinical scores and CT findings (p >0.05).

DISCUSSION

The partially cemented glenoid component for TSR assessed in this study resulted in satisfactory shoulder function at an early follow-up. The glenoid prosthesis was stable, with few radiolucent lines and good central peg bone ingrowth.

CONCLUSIONS

The satisfactory bone ingrowth documented on CT is encouraging and supports the use of the new prosthesis. Long-term follow-up studies can confirm if this device represents a rational alternative to fully cemented polyethylene glenoids.

Clinical and Radiographic Results of an All-Polyethylene Pegged Bone-Ingrowth Glenoid Component

BACKGROUND

Loosening of the glenoid component continues to be the main cause of medium and long-term failure of shoulder replacements. The purpose of this study was to evaluate the early clinical and radiographic results following use of an all-polyethylene pegged glenoid component designed for hybrid (biological and cement) fixation.

METHODS

Eighty-three shoulders in 77 patients (mean age, 68.6 years) underwent total shoulder arthroplasty with a pegged hybrid-fixation component (bone-ingrowth glenoid and cemented peg). Outcomes were determined with the American Shoulder and Elbow Surgeons (ASES) score and the Oxford shoulder score. A detailed analysis of radiographs and fine-slice computed tomography (CT) images was performed to determine the extent of bone ingrowth between the flanges and the extent of radiolucent lines at the prosthesis-bone interface.

RESULTS

The mean duration of follow-up was 46.7 months (range, 24 to 99 months). At the time of final follow-up, the median ASES score was 97 points (range, 43 to 100 points) and the median Oxford score was 48 points (range, 24 to 48 points). The median active forward elevation was 130° (range, 65° to 170°), median external rotation was 45° (range, 5° to 80°), and median internal rotation was to T11 (range, buttock to T4). Seventy-eight shoulders demonstrated a perfect Lazarus score for radiolucency (0, indicating no radiolucency). Sixty-eight shoulders demonstrated complete osseointegration, with bone ingrowth between all of the flanges seen on coronal CT; 5 demonstrated partial osseointegration; and 10 demonstrated osteolysis around the central peg. Most radiolucent lines were in the inferior Yian zones. There were no correlations between the Yian CT scores and either the ASES or Oxford score (rho = 0.13 and 0.07, respectively).

CONCLUSIONS

Total shoulder arthroplasty with an all-polyethylene pegged glenoid component, utilizing hybrid fixation, demonstrated excellent clinical and radiographic results at the time of early follow-up. Radiolucent lines were seen most commonly around the inferior pegs of the prosthesis, and this may represent an incipient mode of failure.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Total shoulder arthroplasty with a second-generation tantalum trabecular metal-backed glenoid component: Clinical and radiographic outcomes at a mean follow-up of 38 months

AIMS

We evaluated clinical and radiographic outcomes of total shoulder arthroplasty (TSA) using the second-generation Trabecular Metal (TM) Glenoid component. The first generation component was withdrawn in 2005 after a series of failures were reported. Between 2009 and 2012, 40 consecutive patients with unilateral TSA using the second-generation component were enrolled in this clinical study. The mean age of the patients was 63.8 years (40 to 75) and the mean follow-up was 38 months (24 to 42).

METHODS

Patients were evaluated using the Constant score (CS), the American Shoulder and Elbow Surgeons (ASES) score and routine radiographs.

RESULTS

Significant differences were found between the pre- and post-operative CS (p = 0.003), ASES (p = 0.009) scores and CS subscores of pain (p < 0.001), strength (p < 0.001) and mobility items (p < 0.05). No glenoid or humeral components migrated. Posterior thinning of the keel and slight wear at the polyethylene-TM interface was observed in one patient but was asymptomatic. Radiolucent lines were found around three humeral (< 1.5 mm) and two glenoid components (< 1 mm) and all were asymptomatic.

DISCUSSION

TSA with the second-generation TM Glenoid component results in satisfactory to excellent clinical performance, function, and subjective satisfaction at a mean follow-up of about three years. Radiographic changes were few and did not affect the outcome.

TAKE HOME MESSAGE

This paper highlights that the second generation Trabecular Metal Glenoid has better outcomes than those reported with the first-generation component.

Total shoulder arthroplasty with an augmented component for anterior glenoid bone deficiency

BACKGROUND

Glenoid bone loss is a challenging problem when performing total shoulder arthroplasty (TSA). Posterior glenoid bone deficiency is more common than anterior deficiency, and so the literature on methods to treat anterior glenoid deficiency in the setting of TSA is not common. The purpose of this case series was to describe preoperative factors, surgical technique, and clinical outcomes in select patients who underwent placement of an anteriorly augmented glenoid component during TSA.

METHODS

This was a retrospective case series of 5 patients who underwent TSA with an anteriorly augmented component. The medical records were reviewed, including preoperative demographics, clinical examination, radiographs, Penn Shoulder Score and American Shoulder and Elbow Surgeons score.

RESULTS

Preoperative diagnoses were anterior glenoid erosion in 2 patients, and 1 patient each with malunited glenoid fracture, nonunited glenoid fracture, and post-traumatic arthritis. The mean age at the time of surgery was 67.4 years (range, 53-75 years). No patient demonstrated radiographic or clinical signs of glenoid component loosening at final follow-up. Postoperative Penn Shoulder Scores averaged 84.4 points (range, 58-100 points), and postoperative American Shoulder and Elbow Surgeons scores averaged 88.0 points (range, 68-100 points). Average postoperative active forward elevation was 140° (range, 80°-170°), and active external rotation was 29° (range 10°-45°). There were no dislocations or revision surgeries at an average of 33.2 months (range, 21.9-43.2 months) after surgery.

CONCLUSION

In the short term, glenohumeral arthrosis in the setting of anterior glenoid deficiency can be treated with an anteriorly augmented glenoid component. Further follow-up and a larger series of patients are necessary to determine the long-term outcomes and complications associated with this technique.

The association of incomplete glenoid component seating and periprosthetic glenoid radiolucencies after total shoulder arthroplasty

BACKGROUND

Radiolucent lines surrounding prosthetic glenoid components are commonly seen after unconstrained total shoulder arthroplasty and can be a harbinger of subsequent glenoid component failure. Whether less than 100% glenoid seating is associated with the development of radiolucent lines around glenoid prostheses is unknown. This study investigated the association between incomplete glenoid component seating and periprosthetic glenoid radiolucencies.

METHODS

Thirty-six unconstrained total shoulder arthroplasties were performed in 29 patients for primary glenohumeral osteoarthritis with a minimum 2-year follow-up. All were implanted with a partially cemented all-polyethylene glenoid prosthesis. Patients were evaluated with standardized plain films preoperatively and postoperatively and with thin-cut computed tomography (CT) scans at the latest follow-up. The Lazarus and Yian classifications were used to assess radiolucency and seating on radiographs and CT scans. Ratings were calculated for intraobserver and interobserver reliability and given κ, the Kendall coefficient, and interclass correlation coefficient values.

RESULTS

At a mean of 43 months (range 24-26 months) after surgery, neither Lazarus plain film radiolucency scores (P = .78) nor Yian CT radiolucency scores (P = .68) were associated with Lazarus plain film seating scores. Neither Lazarus plain film radiolucency scores (P = .25) nor Yian CT radiolucency scores (P = .91) were associated with modified Lazarus CT scan seating scores. CT allowed for better intraobserver and interobserver reliability in all categories.

CONCLUSION

Radiolucencies around a partially cemented glenoid component were not associated with the degree of component seating. Complete seating of the glenoid component is not necessary to achieve radiographic implant stability at a mean follow-up of 43 months.

Radiographic and clinical outcomes of total shoulder arthroplasty with an all-polyethylene pegged bone ingrowth glenoid component: prospective short- to medium-term follow-up

BACKGROUND

Glenoid components often cause total shoulder arthroplasty failure. This study examines short-term to midterm radiographic and clinical results of a hybrid glenoid component with 3 cemented peripheral pegs and a central peg, which allows biologic fixation with use of native humeral head autograft.

METHODS

In 4 years, 80 glenoid components were implanted during primary total shoulder arthroplasty with at least 2-year follow-up data. Within 12 months, 4 shoulders were revised and excluded from final analyses. Seven patients did not complete their questionnaires. Outcomes data included the American Shoulder and Elbow Surgeons (ASES) questionnaire, Constant score, and satisfaction score. A shoulder and elbow fellowship-trained surgeon, not involved in the care of these patients, analyzed radiographs for radiolucent lines, glenoid seating, and radiodensity in between the flanges of the central peg.

RESULTS

Only 1 of 80 shoulders was revised for aseptic glenoid loosening. At final follow-up, 81.6% had a radiolucency grade of 0 or 1. Nearly 90% had a glenoid seating grade of A or B. Grade 2 or 3 bone around the central peg was seen in 88.2%. No statistical association existed between Walch glenoid types and radiolucency grades, bone grades around the central peg, perfect radiolucency grade, seating grade, and grade 3 bone around the central peg. There was significant improvement in mean ASES score, adjusted ASES pain score, Constant score, and satisfaction score as well as in forward flexion, abduction, and external rotation.

CONCLUSIONS

The hybrid glenoid can produce stable radiographic and clinical outcomes at short- to medium-term follow-up.

Outcomes of anatomic shoulder arthroplasty in primary osteoarthritis in type B glenoids

BACKGROUND

Primary glenohumeral osteoarthritis with posterior wear of the glenoid and posterior subluxation of the humerus (Walch type B) presents a challenge to the treating surgeon. Our hypothesis was that glenoids with biconcavity (B2) would be associated with worse outcomes (functional scores and complications) than B1 glenoids.

MATERIALS AND METHODS

We retrospectively analyzed prospectively collected data on 112 anatomic total shoulder arthroplasties (104 patients) with B glenoids. Preoperative computed tomography identified 64 B1 glenoids and 48 B2 glenoids (50 and 37 available for follow-up).

RESULTS

A significant difference between B1 and B2 glenoids was noted in average retroversion (11° vs. 16°; P < .001) and average posterior humeral subluxation (65% vs. 75%; P < .001). No significant difference was seen in mean age (69.5 vs. 69.2 years) or body mass index (28.5 vs. 27.4) at time of surgery. At average follow-up of 60 months (range, 23-120 months), glenoid component radiolucencies (51.6%, B1; 47.9%, B2), range of motion, preoperative and postoperative scores of the shortened Disabilities of the Arm, Shoulder, and Hand questionnaire, and patient satisfaction were not significantly different between the 2 groups. Four revisions (4.6%) were documented for acute postoperative infection (2.3%), subscapularis failure (1.1%), and glenoid loosening (1.1%).

CONCLUSIONS

Although biconcave glenoids commonly have more severe retroversion and posterior subluxation of the humerus, we were unable to find a clinical or radiographic difference in outcome of patients with B1 or B2 glenoids treated with anatomic total shoulder arthroplasty at intermediate-term follow-up. Continued clinical and radiographic follow-up of these cohorts will be necessary to assess any future divergence in outcome.

Catastrophic failure of a low profile metal-backed glenoid component after total shoulder arthroplasty

Context:

The longevity of the glenoid component in total shoulder arthroplasty (TSA) continues to be problematic. All polyethylene glenoid components have been most widely used, but loosening rates with time and the need for revision has resulted in high-profile metal-backed components with the potential for a more stable prosthesis bone interface and liner exchange. High revision rates in the high profile metal backed designs led us to evaluate a low profile metal backed component.

Aims:

To examine the rate and mode of failure of a TSA in a single surgeon consecutive series that has been identified by the Australian National Joint Replacement Registry to have a higher than anticipated rate of revision.

Materials and Methods:

This is a single surgeon retrospective consecutive series of 51 arthroplasties undertaken in 50 patients (18 males and 32 females) with an average age of 70.4 ears (range 51-90) and mean follow-up of 5.5 years (range 3.7-8.1).

Results:

We observed a very high (29%) rate of revision of the metal-backed glenoid components in this series. The primary mode of failure was glenoid baseplate nonintegration which with a well-fixed central cage screw led to bone resorption and implant breakage or disassembly.

Conclusion:

Analysis of the mode of failure of implants identified by robust registries is essential for the development of new prostheses and the pursuit of prosthesis longevity. This low profile metal backed prosthesis has been withdrawn, but without a published mechanism of failure. We feel that any prosthesis withdrawal should be accompanied by appropriate published mechanisms to prevent future component design errors based on similar design problems.

No differences in early results of a hybrid glenoid compared with a pegged implant

BACKGROUND

Glenoid component loosening after total shoulder arthroplasty is one of the most common causes of failure. A hybrid glenoid that uses peripherally cemented pegs and a central press-fit post may improve implant longevity.

QUESTIONS/PURPOSES

We asked, compared with polyethylene pegged glenoid implants, do hybrid glenoid implants with a titanium post provide (1) better ingrowth with fewer radiolucencies, (2) better outcome and pain scores, and (3) lower risk of complications and revisions?

METHODS

Between 2009 and 2010, 126 patients underwent primary total shoulder arthroplasty for osteoarthritis. Patients were included in this retrospective study if they consented for inclusion in a shoulder arthroplasty registry, had complete baseline and 2-year data, and had complete radiographs. Eighty-three (67%) were available at an average followup of 3.2 years (range, 24-45 months). Forty received a conventional all-polyethylene pegged glenoid and 43 received a hybrid component. During the period in question, four of the participating surgeons used only one implant, and four used only the other; there was one high-volume surgeon in each of the study groups. Radiographs were taken at the 2-year followup and analyzed for radiolucent lines. CT scans were obtained randomly for 10 patients with hybrid glenoid implants to assess bone ongrowth. American Shoulder and Elbow Surgeons score, VAS score, complications and revisions were recorded.

RESULTS

At final followup, radiolucent lines between the two study groups were not different (hybrid, 1.0 ± 0.4; pegged, 1.6 ± 0.3; mean difference, 0.6; 95% CI, 0.85-1.72; p = 0.323). Final VAS pain scores were not different (hybrid, 1.2 ± 0.2; pegged, 1.5 ± 0.3; p = 0.056). Change in American Shoulder and Elbow Surgeons scores were not different (hybrid, 33.7 ± 7.3; pegged, 35.5 ± 8.2; p = 0.283). There were no differences in complication risk (hybrid, one of 43 [2.3%]; pegged, three of 40 [7.5%]; relative risk, 2.3; 95% CI, 0.82-3.12; p = 0.061).

CONCLUSIONS

With the numbers available and at early followup, there were no differences between the hybrid and pegged glenoids in terms of fixation, functional outcome, pain scores, and complications. CT scans confirmed bone ongrowth on the porous titanium post in a small subcohort of patients. Further studies are needed to determine how this new implant will perform with time. Until then, its use should be initiated with caution.

LEVEL OF EVIDENCE

Level III, therapeutic study.

An in vitro study comparing limited to full cementation of polyethylene glenoid components

Background

Glenoid component survival is critical to good long-term outcomes in total shoulder arthroplasty. Optimizing the fixation environment is paramount. The purpose of this study was to compare two glenoid cementing techniques for fixation in total shoulder arthroplasty.

Methods

Sixteen cadaveric specimens were randomized to receive peg-only cementation (CPEG) or full back-side cementation (CBACK). Physiological cyclic loading was performed and implant displacement was recorded using an optical tracking system. The cement mantle was examined with micro-computed tomography before and after cyclic loading.

Results

Significantly greater implant displacement away from the inferior portion of the glenoid was observed in the peg cementation group when compared to the fully cemented group during the physiological loading. The displacement was greatest at the beginning of the loading protocol and persisted at a diminished rate during the remainder of the loading protocol. Micro-CT scanning demonstrated that the cement mantle remained intact in both groups and that three specimens in the CBACK group demonstrated microfracturing in one area only.

Discussion

Displacement of the CPEG implants away from the inferior subchondral bone may represent a suboptimal condition for long-term implant survival. Cement around the back of the implant is suggested to improve initial stability of all polyethylene glenoid implants.

Clinical relevance

Full cementation provides greater implant stability when compared to limited cementation techniques for insertion of glenoid implants. Loading characteristics are more favorable when cement is placed along the entire back of the implant contacting the subchondral bone.

Five- to ten-year follow-up with a partially cemented all-polyethylene bone-ingrowth glenoid component

BACKGROUND

Although total shoulder arthroplasty has demonstrated better clinical outcomes than hemiarthroplasty, glenoid component loosening is a common complication. Recently, a novel partially cemented all-polyethylene fluted central peg bone-ingrowth component was introduced.

METHODS

Forty-two consecutive total shoulder arthroplasties from 2003 to 2007 performed by a single surgeon were evaluated radiographically and clinically with American Shoulder and Elbow Surgeons (ASES) scores and range of motion.

RESULTS

The average follow-up was 80 months (63-114); the average forward elevation improved from 107° to 137°, and external rotation improved from 30° to 37° at the latest follow-up. The average ASES score improved from 50 to 84. There was a strong correlation with the mean peripheral peg lucent line score (Lazarus score), which was 0.81, with the mean anchor peg lucent line score, which was 0.50 (P < .001). An analysis of polyethylene before and after cross-linking revealed a strong correlation between components with cross-linking and the Lazarus scores and the central fluted peg scores. Overall, there was 97% survivorship at 80 months. On radiographs, 81% of the central fluted pegs had complete incorporation with no lucent lines. These lucent lines correlated with lower ASES scores, suggesting that loosening of the glenoid decreases functional outcome.

CONCLUSION

Care should be taken in preparing the central fluted peg as perforation of the vault can lead to central flute peg lucent line formation, whereas perforation of the peripheral pegs does not seem to negatively affect the outcome.

The glenoid component in anatomic shoulder arthroplasty

Ideal management of the glenoid in anatomic shoulder arthroplasty remains controversial. Glenoid component loosening remains a common source of clinical concern and, in young, active patients, implantation of a glenoid prosthesis is often avoided. Efforts to decrease glenoid loosening have resulted in changes to prosthetic design and implantation techniques. Currently, a wide variety of glenoid component options are available, including metal-backed or all-polyethylene, bone ingrowth or ongrowth, inset, and augmented designs. Additionally, several alternatives are available for the young, active patient, including hemiarthroplasty, nonprosthetic resurfacing, and tissue interposition. Many recent clinical and biomechanical studies have examined these implant options. A thorough knowledge of glenoid anatomy, pathology, implant options, indications, and principles of implantation is necessary to optimize the outcome following anatomic shoulder arthroplasty.

Long-term survival of the glenoid components in total shoulder replacement for arthritis

PURPOSE

Aseptic glenoid component loosening remains a common problem in total shoulder arthroplasty (TSA). This study presents long-term prospective follow-up after implantation of a glenoid component using the "cancellous compaction technique" and its effect on clinical outcome and presence and progression of radiolucent lines (RLLs).

METHOD

Thirty-nine TSAs were performed for primary osteoarthritis by one surgeon using the same technique. For the glenoid side, a keeled, polyethylene, convex-backed component was implanted using the "cancellous compaction technique" consisting of minimal reaming, compaction bone grafting of the glenoid and minimal addition of cement. Postoperative clinical outcome was analysed using Constant scores and patient's subjective evaluation. Independent observers evaluated postoperative X-rays for radiolucent lines (RLL) around the base plate and keel.

RESULTS

At an average follow-up of 8.5 years (range 4.7-12.5), the Constant score improved from 33.5 to 73.0 points (P < 0.0001). Active anterior elevation improved from an average 95 ° to 140° (P < 0.0001), and active external rotation improved from 20° to 45° (P < 0.0001). Pain score improved from 3.1 to 13.6 (P < 0.0001). Radiologically, the RLL score increased from 1.09 (range, 0-3) postoperative to 5.7 (range, 0-18) (P < 0.0001) at final follow-up. The occurrence of definite radiological glenoid loosening was 15.5 %. Constant scores deteriorated with the progression of RLLs (P = 0.006). The rate of revision surgery for glenoid loosening was 2.5 %.

CONCLUSIONS

This study showed highly satisfactory clinical outcomes and low rates of revision for glenoid loosening using a bone-saving compaction technique for implantation of an all-polyethylene glenoid component.

Accuracy and reliability testing of two methods to measure internal rotation of the glenohumeral joint

BACKGROUND

We compared accuracy and reliability of a traditional method of measurement (most cephalad vertebral spinous process that can be reached by a patient with the extended thumb) to estimates made with the shoulder in abduction to determine if there were differences between the two methods.

METHODS

Six physicians with fellowship training in sports medicine or shoulder surgery estimated measurements in 48 healthy volunteers. Three were randomly chosen to make estimates of both internal rotation measurements for each volunteer. An independent observer made objective measurements on lateral scoliosis films (spinous process method) or with a goniometer (abduction method). Examiners were blinded to objective measurements as well as to previous estimates.

RESULTS

Intraclass coefficients for interobserver reliability for the traditional method averaged 0.75, indicating good agreement among observers. The difference in vertebral level estimated by the examiner and the actual radiographic level averaged 1.8 levels. The intraclass coefficient for interobserver reliability for the abduction method averaged 0.81 for all examiners, indicating near-perfect agreement. Confidence intervals indicated that estimates were an average of 8° different from the objective goniometer measurements. Pearson correlation coefficients of intraobserver reliability for the abduction method averaged 0.94, indicating near-perfect agreement within observers. Confidence intervals demonstrated repeated estimates between 5° and 10° of the original.

CONCLUSIONS

Internal rotation estimates made with the shoulder abducted demonstrated interobserver reliability superior to that of spinous process estimates, and reproducibility was high. On the basis of this finding, we now take glenohumeral internal rotation measurements with the shoulder in abduction and use a goniometer to maximize accuracy and objectivity.

Correction of acquired glenoid bone loss in osteoarthritis with a standard versus an augmented glenoid component

BACKGROUND

The magnitude and anatomic consequences of pathologic acquired glenoid retroversion and posterior bone loss that can be surgically corrected with a standard versus an augmented glenoid component have not been studied extensively in a surgical patient population.

MATERIALS AND METHODS

Twenty-nine patients with glenohumeral osteoarthritis, acquired posterior bone loss, and increased retroversion were studied by use of a three-dimensional computer surgical simulation. For each case, amount of medialization was measured as the linear distance from the lateral aspect of the glenoid vault model to the center of the articular implant surface. Simulation of implant placement at 0° or 6° was performed with use of a standard glenoid having a uniform thickness and an asymmetric thickness augmented component.

RESULTS

An increased amount of medialization was seen with the standard glenoid, 8.3 ± 4.1 mm, compared with 3.8 ± 3.3 mm with use of the augmented glenoid implant (P < .001). When glenoid retroversion was corrected to 0°, pathologic version was shown to have strong and significant relationship to the amount of medialization for both the standard (R(2) = 0.825) and augmented (R(2) = -0.68) glenoid implant. There was an increased ability to correct greater amounts of pathologic version with less medialization by use of an augmented step glenoid compared with a standard anchor peg glenoid.

DISCUSSION

Correction of moderate to severe glenoid retroversion by asymmetric reaming cannot always be done with use of a standard component, and if it is done, it will result in greater medialization of the joint line. Use of an augmented component can allow complete correction of retroversion and minimize the effect of medialization.

Metal-Backed Glenoid Components Have a Higher Rate of Failure and Fail by Different Modes in Comparison with All-Polyethylene Components: A Systematic Review

BACKGROUND

Glenoid component failure is a common and serious complication of total shoulder arthroplasty. The purpose of this study was to evaluate published evidence on whether metal backing lessens the rate of glenoid component failure.

METHODS

A comprehensive systematic review yielded twenty-one studies on radiolucency, radiographic failure, and revision after arthroplasty with metal-backed glenoid components and twenty-three studies with all-polyethylene components. Our analysis included data on 1571 metal-backed and 3035 all-polyethylene components. The mean duration of follow-up was 5.8 years in the studies with metal-backed components and 7.3 years with all-polyethylene components.

RESULTS

All-polyethylene components had a 42.5% rate of radiolucency compared with 34.9% for metal-backed components (p = 0.0026) and a 21.1% rate of radiographic loosening or failure compared with 16.8% for metal-backed components (p = 0.0005). However, the rate of revision was more than three times higher with metal-backed components (14.0%) than with all-polyethylene components (3.8%, p < 0.0001). Although 77% of the revisions of all-polyethylene components were for loosening, 62% of the revisions of metal-backed components were for other reasons, such as component fracture, screw breakage, component dissociation, polyethylene wear, metal wear, and rotator cuff tear (p < 0.0001).

CONCLUSIONS

The published evidence indicates that metal-backed glenoid components require revision at a significantly higher rate and for different reasons in comparison with all-polyethylene components.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Glenoid perforation with pegged components during total shoulder arthroplasty

A subset of patients undergoing primary total shoulder arthroplasty (TSA) have a medialized joint line secondary to glenoid wear. In some cases, the central pegs or peripheral pegs of a peg design glenoid component may violate the medial cortex of the glenoid vault. It is unknown whether this leads to early failure. The objectives of this study were to determine (1) whether glenoid components with uncontained pegs would be associated with a high rate of failure and (2) whether peg perforation would be associated with inferior clinical outcomes. The authors performed a case-control retrospective review comparing 25 TSAs in which one or multiple pegs perforated the medial glenoid vault (uncontained group) with 25 TSAs without peg perforation (contained group). Implant survival was calculated with revision for glenoid component loosening as the primary outcome variable. Clinical outcomes were determined using American Shoulder and Elbow Surgeons (ASES) and Penn Shoulder Scores. Average follow-up was more than 5 years. No patient in either group had symptomatic glenoid loosening. Two (8%) patients in the uncontained group required revision for rotator cuff tears. Penn and ASES scores were significantly lower in the uncontained group (Penn, P=.002; ASES, P=.004). Pain and satisfaction subscores were similar between the groups, but function subscores were significantly lower in the uncontained group (Penn, P=.002; ASES, P=.005). Uncontained pegs of an anchor peg glenoid component are not associated with early glenoid loosening. Similar pain relief is obtained when compared with contained glenoid components, but shoulder function is significantly lower in patients with uncontained pegs.

Axillary view: arthritic glenohumeral anatomy and changes after ream and run

BACKGROUND

The technique and results of shoulder arthroplasty are influenced by glenohumeral pathoanatomy. Although some authors advocate a routine preoperative CT scan to define this anatomy, ordering a CT scan substantially increases the cost and the radiation exposure for the patient.

QUESTIONS/PURPOSES

We asked whether measurements of arthritic shoulders on a standardized axillary view are reliable; if postoperative radiographs can reliably show the changes in glenoid anatomy and glenohumeral relationships after shoulder arthroplasty, and if the axillary view can show differences in glenohumeral pathoanatomy in the different sexes and disease types.

METHODS

These questions were addressed using cross-sectional studies of 344 shoulders with different types of arthritis and of 128 osteoarthritic shoulders having a ream and run arthroplasty (a glenohumeral arthroplasty that combines a noncemented humeral hemiarthroplasty with concentric reaming of the glenoid bone without implantation of a prosthetic glenoid component). Measurements of glenoid type, glenoid version, and glenohumeral contact were made on standardized axillary radiographs. Interobserver reliability was calculated, preoperative and postoperative measurements were compared, and morphologic differences were compared as stratified by sex and disease type.

RESULTS

The measurements on axillary views showed a high degree of interobserver reliability and sensitivity to the changes effected by arthroplasty. The ream and run substantially corrected the glenoid type and point of glenohumeral contact. Male shoulders and shoulders with osteoarthritis had more type B glenoids (ie, those with posterior erosion and biconcavity of the glenoid), more retroversion, and a greater degree of posterior displacement of the point of glenohumeral contact.

CONCLUSIONS

The axillary view provides a practical method of characterizing glenohumeral anatomy before and after surgery that is less costly and exposes the patient to less radiation than a CT scan.

LEVEL OF EVIDENCE

Level IV, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.

Longitudinal observational study of total shoulder replacements with cement: fifteen to twenty-year follow-up

BACKGROUND

There is little information about the long-term longitudinal outcomes of total shoulder arthroplasty. Moreover, long-term data on a single shoulder replacement system are lacking. The aim of this study was to analyze, at different time points during a follow-up period of fifteen to twenty years, the clinical and radiographic outcomes of patients treated with a third-generation total shoulder arthroplasty.

METHODS

Sixty-three total shoulder arthroplasties were performed in fifty-eight patients. Two patients were lost to follow-up, and sixteen patients died during the follow-up period, leaving a cohort of forty-five total shoulder arthroplasties in forty patients with a mean age of sixty-four years. Follow-up examinations were carried out at six months, one year, two years, three to four years, five to eight years, nine to fourteen years, and fifteen years or more. Preoperatively and at each follow-up visit, the Constant score as well as shoulder flexion and external rotation were assessed. Radiographs were analyzed for loosening and migration of the components at all time points.

RESULTS

There was a substantial improvement of all clinical parameters from baseline to the latest follow-up evaluation. Clinical results reached a plateau at one year, remained stable without substantial worsening for eight years, and then remained as good as the six-month results until fifteen years postoperatively. Compared with the outcomes at the six-month follow-up examination, the results were worse beyond fifteen years. The clinical outcome was not influenced by sex, age, hand dominance, glenoid morphology, glenoid loosening, or upward migration of the humeral head. Thirty-three (73%) of the forty-five shoulders had radiographic evidence of glenoid loosening at the time of final follow-up. Fourteen shoulders (31%) were revised: a soft-tissue revision was performed in one of them, and implant revision was necessary in thirteen.

CONCLUSIONS

Although there is a significant and longitudinal improvement in shoulder function and pain relief after total shoulder replacement, long-term follow-up of fifteen to twenty years demonstrated a high revision rate in this cohort.

Computed tomography quantification of bone density adjacent to cemented pegged polyethylene glenoid components in shoulder arthroplasty

BACKGROUND

Cemented polyethylene devices are the prostheses implanted more frequently, but there is no agreement on the optimal glenoid component design. In this study, bone mineral density (BMD) adjacent to cemented all-polyethylene glenoid components was assessed to gain insights into the characteristics of glenoid bone as a potential risk factor implicated in the failure of shoulder arthroplasty.

PATIENTS AND METHODS

Twenty-two subjects were examined at an average follow-up of 31 months using the Constant-Murley score (CS) and multi-detector computed tomography. BMD was measured in 5 regions of interest (ROIs) at the sites where radiolucent lines are usually detected. BMD differences among the ROIs were tested. The relationship between BMD and a number of variables (CS subscores, age, gender, follow-up duration) was explored.

RESULTS

There was a significant increase in CS scores (p<0.05). Significantly different BMD (p=0.0039) was found in the 5 ROIs, especially between ROIs 2 and 5 (p=0.016, Bonferroni's test) and between ROIs 3 and 5 (p=0.005, Bonferroni's test). BMD was lower in ROI 1 than ROI 3 and in ROI 2 than ROI 4, but the difference was not significant.

DISCUSSION

The heterogeneous BMD distribution may be related to: (1) an interindividual variability in glenoid BMD; (2) the fixation technique; or (3) the different bone response to eccentric loading of the prosthetic head on the glenoid component.

CONCLUSIONS

BMD analysis may contribute to extent our knowledge on glenoid component loosening and encourage further techniques of glenoid fixation.

Liftoff resistance of augmented glenoid components during cyclic fatigue loading in the posterior-superior direction

BACKGROUND AND HYPOTHESIS

Posterior glenoid bone loss is found in a majority of patients with advanced osteoarthritis of the shoulder. In total shoulder arthroplasty, several methods currently exist for management of this bone loss, including the use of an augmented glenoid component. Different augmented glenoid designs would be expected to vary in their resistance to loosening during mechanical bench-top testing. Our hypothesis is that a stepped augmented glenoid component will have less mechanical liftoff than augmented components of varying designs without a step.

MATERIALS AND METHODS

Four glenoid prototypes articulated with a humeral head were loaded with a 170-lb compressive load and with 4 mm of posterior-superior translation of the humeral head to 100,000 cycles. Anterior glenoid liftoff was measured.

RESULTS

The stepped glenoid component had significantly lower liftoff values (P < .05) compared with several other designs at many of the test intervals.

DISCUSSION

A stepped design for an augmented glenoid component has superior fixation and less anterior glenoid liftoff in the presence of eccentric loading and may have better long-term clinical results.

Fully uncemented glenoid component in total shoulder arthroplasty

BACKGROUND

Loosening of the glenoid component remains the most common problem in total shoulder arthroplasty. It has been described that the round-backed, all-polyethylene components with cemented peg fixation perform better biomechanically and clinically than flat-backed, metal-backed, or keeled components. However, side effects of cementing have been described. We hypothesized that cementing of a specific type of all-polyethylene glenoid component with 3 peripheral pegs and 1 central anchor peg is not necessary to obtain good clinical and radiologic results.

MATERIALS AND METHODS

Thirty-four shoulders (34 patients), with a mean follow-up of 28.3 months, were evaluated clinically with the Constant-Murley score and the SF-12 Health Survey score. The fixation of the glenoid component was evaluated with computed tomography scan.

RESULTS

The Constant-Murley score increased from 40.2 points (range, 13-73 points) preoperatively to 72 points (range, 54-93 points) postoperatively. The SF-12 Physical Component Summary score was 45, and the SF-12 Mental Component Summary score was 50. No signs of loosening were seen around the pegs or glenoid in 30 shoulders. Signs of loosening were seen around the central anchor peg and the peripheral pegs in 4 shoulders. There was no statistical difference between the clinical outcome of patients with and without signs of loosening.

CONCLUSION

The clinical and radiologic evaluation of an uncemented all-polyethylene glenoid is promising, with good clinical results and with no signs of loosening in 88% of the patients on computed tomography scans.

Glenoid morphology affects the incidence of radiolucent lines around cemented pegged polyethylene glenoid components

PURPOSE

Radiolucent lines (RLL) are frequent findings around cemented all-polyethylene glenoid implants. The present study evaluates the frequency, extend and the clinical impact of RLL around a cemented two-pegged glenoid implant with special focus on the influence of preoperative glenoid morphology. Our hypothesis was that glenoid morphology does not affect clinical outcome and RLL in the investigated setting.

METHODS

Between 2003 and 2008, a total of 113 cases of total shoulder arthroplasties (Affinis, Mathys Ltd Bettlach, Switzerland) were performed in three surgical centres using a pegged cemented polyethylene glenoid component. A total of 90 cases could be evaluated clinically and radiographically. Clinical outcome was analysed using the constant score (CS) and range of motion assessment. Radiographic evaluation was performed in true anterior-posterior and axial views with special focus on loosening and RLL. Further, preoperative glenoid morphology was documented and its correlation to radiolucent lines and clinical outcomes was evaluated.

RESULTS

At a mean of 58.8 (range 31.2-92.5)-month follow-up the CS improved from 21.5 points preoperatively to 62.3 points postoperatively. Radiolucent lines were found in 76.6 % of cases. If present, RLL were located at the backside of the implant (74.4 %) in the majority of the cases not around the pegs (10 %). There was no significant correlation between RLL and clinical outcome or follow-up time. The amount and extend of RLL were correlated to glenoid morphology with significantly higher values for glenoid types B2 and C according to Walch in comparison to glenoid types A1, A2 and B1.

CONCLUSIONS

RLL did not affect clinical outcome and did not correlate with the follow-up time. Patients with glenoid morphology types B2 and C showed significantly worse radiographic results.

LEVEL OF EVIDENCE

Level IV case series study.

Addressing glenoid bone deficiency and asymmetric posterior erosion in shoulder arthroplasty

Glenoid bone deficiency and eccentric posterior wear are difficult problems faced by shoulder arthroplasty surgeons. Numerous options and techniques exist for addressing these issues. Hemiarthroplasty with concentric glenoid reaming may be a viable alternative in motivated patients in whom glenoid component failure is a concern. Total shoulder arthroplasty has been shown to provide durable pain relief and excellent function in patients, and numerous methods and techniques can assist in addressing bone loss and eccentric wear. However, the ideal amount of version correction in cases of severe retroversion has not yet been established. Asymmetric reaming is a commonly used technique to address glenoid version, but correction of severe retroversion may compromise bone stock and component fixation. Bone grafting is a technically demanding alternative for uncontained defects and has mixed clinical results. Specialized glenoid implants with posterior augmentation have been created to assist the surgeon in correcting glenoid version without compromising bone stock, but clinical data on these implants are still pending. Custom implants or instruments based on each patient's unique glenoid anatomy may hold promise. In elderly, sedentary patients in whom bone stock and soft-tissue balance are concerns, reverse total shoulder arthroplasty may be less technically demanding while still providing satisfactory pain relief and functional improvements.

Magnetic resonance scanning vs axillary radiography in the assessment of glenoid version for osteoarthritis

BACKGROUND

Osteoarthritic shoulders are mainly associated with glenoid retroversion. Total shoulder arthroplasty with the glenoid component implanted in retroversion predisposes to loosening of the glenoid prosthesis. Correction of glenoid retroversion through anterior eccentric reaming, before glenoid component implantation, is performed to restore normal joint biomechanics. Accurate preoperative assessment is required to ascertain the degree of retroversion and calculate the degree of reaming.

MATERIALS AND METHODS

We assessed the utility of magnetic resonance imaging (MRI) for the assessment of glenoid version in glenohumeral osteoarthritis compared with standard plain axillary radiography (AXR). Two independent observers reviewed both types of imaging in 48 primary osteoarthritic shoulders on 2 separate occasions.

RESULTS

The mean glenoid version measured was -14.3° on MRI and -21.6° on AXR (mean difference, -7.36°; P < .001). Intraobserver and interobserver reliability coefficients were 0.96 and 0.9, respectively, for MRI and 0.8 and 0.71, respectively, for AXR. Glenoid retroversion was greater in 73% of AXR.

CONCLUSION

We demonstrated that MRI is more reproducible in the assessment of glenoid version in osteoarthritis and provides excellent intraobserver and interobserver reliability. MRI is useful for preoperative osseous imaging for total shoulder arthroplasty because it offers a more precise method of determining glenoid version compared with x-ray imaging in addition to the standard assessment of rotator cuff integrity.

Glenoid component retroversion is associated with osteolysis

BACKGROUND

It has been suggested that glenoid component retroversion and eccentric loading are an important mechanism leading to glenoid component loosening, but little clinical data have been published to support this concept.

METHODS

Sixty-six shoulders underwent total shoulder replacement with an all-polyethylene press-fit pegged glenoid component designed for osseous ingrowth for treatment of osteoarthritis. These shoulders were followed clinically and with radiographs for an average (and standard deviation) of 3.8 ± 1.8 years (range, two to seven years). Preclinical radiographic loosening was defined as osteolysis around the central peg of the glenoid component.

RESULTS

Of the sixty-six shoulders, twenty (30%) had osteolysis around the center peg. The length of time after replacement (p = 0.0006), preoperative glenoid retroversion (p = 0.036), and postoperative glenoid component retroversion (p = 0.041) were correlated with osteolysis around the glenoid center peg and an increase in the Lazarus component loosening grade. Postoperative retroversion correlated with preoperative retroversion (Pearson correlation coefficient = 0.44, 95% confidence interval [CI] = 0.19 to 0.64, p = 0.0011). The presence of osteolysis around the center peg was not correlated with a worse clinical outcome defined by shoulder scores or a reoperation due to glenoid loosening. After adjustment for follow-up time, excessive postoperative glenoid retroversion (≥15°) was associated with an increased odds of osteolysis (odds ratio = 5.23, 95% CI = 1.31 to 20.9]), whereas preoperative glenoid retroversion was associated with no change in the odds of osteolysis.

CONCLUSIONS

Osteolysis around the center peg of a glenoid component is correlated with component retroversion of ≥15°. This finding suggests that there should be additional investigation into the effects of correcting preoperative glenoid retroversion to prevent osteolysis around the center peg.

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.

Bone grafting in shoulder arthroplasty

Shoulder arthroplasty is one of the fastest-growing fields in orthopedic surgery. Deficiency of the glenoid or humeral bone stock is a major challenge that can result from degenerative arthritis, component loosening or extraction, fracture, or malignancy. Approximately 15% of primary reconstructions will require bone grafting, and the rate is higher for revisions. The authors present a systematic review of the current literature focused on the indications for and results of bone grafting techniques. This provides the practicing surgeon with a set of strategies to address bone loss in the primary and revision settings, whether using an anatomic or reverse design.