Keeled Glenoid Components Research Articles

Risk factors for loosening of cemented glenoid components in anatomical shoulder arthroplasty

Several risk factors leading to loosening of the glenoid have been described; however, there is no detailed information available on the exact numbers or percentages for each patient-related risk factor, implant-related risk factor, or risk factors related to surgical technique. Therefore, the aim of this multicenter study was to analyze these risk factors in a large cohort of patients treated with a 3rd-generation cemented total shoulder arthroplasty. Four-hundred seventy-one shoulder arthroplasties with a mean follow-up of 8.1 years were included. There were 318 women and 153 men. The mean age at the time of arthroplasty was 68 (range 35–90) years. The dominant shoulder was treated in 294 cases and the nondominant in 177. The following risk factors for loosening of the cemented keeled glenoid component were examined: gender, age, hand dominance, glenoid morphology, reaming on the glenoid side (reaming down the complete subchondral bone layer), glenohumeral mismatch, glenoid component design, and fatty degeneration of the rotator cuff. No influence on radiographic glenoid loosening was found for patient age at surgery, gender, hand dominance, preparation technique on the glenoid side, or fatty degeneration of the rotator cuff (p > 0.067). Excessive reaming on the native glenoid led to a 3.7-fold higher risk for glenoid component loosening (p < 0.001). A glenohumeral mismatch <6 mm was associated with higher radiographic loosening rates (p < 0.03). The use of a flat-back glenoid component led to a 3.1-fold higher risk for radiographic loosening compared to convex-back glenoids (p < 0.001). B2 glenoids had a higher risk for radiographic loosening compared to A1 (2.3-fold), A2 (3.6-fold), and B1 (2.7-fold) glenoids (p < 0.001). Based on a large and homogenous cohort of patients, this study has shown several risk factors for loosening of a cemented glenoid component in the midterm and long term. The loosening rates of cemented keeled glenoid components in primary osteoarthritis could possibly be reduced by optimizing surgical technique, implant configuration, and patient selection. Further long-term studies are necessary to confirm these findings.

Paper #2 - Radiographic and Clinical Comparison of Pegged and Keeled Glenoid Components Using Modern Cementing Techniques: Midterm Results of a Prospective Randomized Study

Background: Glenoid component loosening remains a significant issue after anatomic shoulder arthroplasty. Pegged glenoid components have shown better lucency rates than keeled components in the short term, however, mid to long-term results have not fully been determined. We previously reported early outcomes of this randomized, controlled group of patients, with higher glenoid lucency rates in patients with a keeled glenoid. The purpose of this study was to evaluate the radiographic and clinical outcomes of pegged and keeled glenoid components at midterm follow-up.

Short-term radiographic results of a cemented polyethylene keeled glenoid component with varying backside radiuses of curvature

This study analyzed the radiographic results of a cemented all-polyethylene keeled glenoid component available in different sizes and multiple backside radiuses of curvature. The study group consisted of 118 cases (114 patients). There were 63 women and 51 men. Mean age at the time of arthroplasty was 68 years (range, 51-85 years). True anterior-posterior radiographs obtained postoperatively and at the final follow-up were analyzed for implant seating and the occurrence of radiolucent lines. Glenoid morphology and fatty infiltration of the rotator cuff muscles were examined using computed tomography scans. Mean follow-up was 38 months (range, 24-70 months). The mean radiolucent line score after surgery was 0.54 points (range, 0-3 points), and 90% had no or only 1 radiolucent line. At the final follow-up, the mean score was 1.06 points (range, 0-3 points), and 74% had no or only 1 radiolucent line. The score increased significantly over time (P < .001). No component was at risk for loosening. No correlation was found between patient age, sex, hand dominance, glenoid morphology, or fatty infiltration of the rotator cuff muscles and the occurrence of radiolucent lines. In the short-term, the glenoid component analyzed in this study showed promising radiographic results, with a low number of radiolucent lines without failure. However, the mean radiolucent line score increased significantly over time, and long-term observations are necessary to confirm a possible advantage compared with older component designs.

Radiographic and clinical comparison of pegged and keeled glenoid components using modern cementing techniques: midterm results of a prospective randomized study

Glenoid component loosening remains a significant issue after anatomic shoulder arthroplasty. Pegged glenoid components have shown better lucency rates than keeled components in the short term; however, midterm to long-term results have not fully been determined. We previously reported early outcomes of the current randomized controlled group of patients, with higher glenoid lucency rates in those with a keeled glenoid. The purpose of this study was to evaluate the radiographic and clinical outcomes of these components at minimum 5-year follow-up. Fifty-nine total shoulder arthroplasties were performed in patients with primary glenohumeral osteoarthritis. Patients were randomized to receive either a pegged or keeled glenoid component. Three raters graded radiographic glenoid lucencies. Clinical outcome scores and active mobility outcomes were collected preoperatively and at yearly postoperative appointments. Of the 46 shoulders meeting the inclusion criteria, 38 (82.6%) were available for minimum 5-year radiographic follow-up. After an average of 7.9 years, radiographic lucency was present in 100% of pegged and 91% of keeled components (P = .617). Grade 4 or 5 lucency was present in 44% of pegged and 36% of keeled components (P = .743). There were no differences in clinical outcome scores or active mobility outcomes between shoulders with pegged and keeled components at last follow-up. Within the initial cohort, 20% of the keeled shoulders (6 of 30) and 7% of the pegged shoulders (2 of 29) underwent revision surgery (P = .263). Kaplan-Meier analysis showed no significant difference in survival rates between groups (P = .560). At an average 7.9-year follow-up, non-ingrowth, all-polyethylene pegged glenoid implants are equivalent to keeled implants with respect to radiolucency, clinical outcomes, and need for revision surgery.

No correlation between radiolucency and biomechanical stability of keeled and pegged glenoid components

BackgroundThe purpose of this study was to examine biomechanical properties and the degree of radiolucency of two cemented basic glenoid designs for total shoulder arthroplasty. Our hypothesis was that a component with increased micro-motion in the laboratory at time zero would also exhibit a greater amount of radiolucency in patients at a minimum of 2 years post total shoulder arthroplasty.MethodsThirty cadaveric shoulders were divided into 2 groups (keel vs. peg). The glenoid components were first loaded with a single axial eccentric force of 196 N in all orientations and then with a transversal load of 49 N to simulate in vivo loads with abduction. Displacement of the glenoid component was determined with four different linear variable-differential transducers. In the second phase, 56 antero-posterior x-rays of 52 patients with either the same keeled (n = 24) or pegged (n = 32) glenoid component with a minimum of 24 months follow-up were evaluated for radiolucency.ResultsBiomechanically the pegged glenoid showed a significant increase in micro-motion during eccentric axial loading as well as during combined loading in the anterior, posterior, and inferior position as compared to the keeled glenoid (p < 0.05). In contrast all results were significant with greater radiolucency for the keeled glenoid component (p = 0.001).ConclusionWhile the pegged component exhibited a greater amount of micro-motion during biomechanical testing, radiolucency was greater in patients with a keeled component. These findings provide support for both components from different perspectives and highlight the need for well-constructed studies to determine whether glenoid design has an effect on clinical outcome, because influences are multifactorial and biomechanical forces may not recreate forces seen in vivo.

Comparison of Pegged and Keeled Glenoid Components for Total Shoulder Arthroplasty

Background Limited evidence exists regarding the relative rates of glenoid loosening after total shoulder arthroplasty utilizing pegged or keeled cemented all-polyethylene glenoid components. Methods A systematic review of level I, II, and III studies comparing the development of radiolucent lines and glenoid failure after total shoulder arthroplasty with pegged or keeled glenoid components was conducted. Four articles were included in the final analysis with a total of 203 total shoulder arthroplasties comprising 107 pegged and 96 keeled glenoid components. Results Development of radiolucent lines was less likely with pegged glenoid components with a risk difference of −0.32 (95% CI −0.62, −0.03) favoring the pegged design. There was no statistically significant difference in the rate of radiographically at-risk glenoids, clinical glenoid failure, or the composite endpoint. Conclusions Although the development of radiolucent lines was less likely around pegged glenoid components, there was no significant difference in the rate of radiographic or clinical glenoid failure between pegged and keeled components. More high-quality studies are needed to determine the relative rates of glenoid loosening with pegged and keeled glenoid components.

Radiographic survival in total shoulder arthroplasty

Glenoid component loosening is thought to be a major cause of failure. This study assesses radiographic and clinical failure in shoulder arthroplasty, identifying factors predictive of loosening. Three-hundred two shoulder arthroplasties were implanted utilizing a cemented, keeled glenoid component, mean clinical follow-up 8.6 years. One-hundred fifty one shoulders had preoperative, early postoperative, and most recent radiographs, mean radiographic follow-up 8.0 years, minimum 4 years or less if revision was performed (2 cases). Fifty-two of 151 glenoid components (34%) showed a shift in position or a complete lucent line ≥1.5 mm. Four humeral components (3%) shifted or showed a 2-mm lucency in 3 zones. Component survival (Kaplan-Meier) free from radiographic failure at 5 and 10 years were 99% (95% CI) (98-100%) and 67% (95% CI) (58-78%). Glenoid components with lines at the keel on initial radiographs were at risk for radiographic failure, hazard ratio 4.6 95% CI 1.2-17.2, P=.02. No associations were found between radiographic survival and age, gender, diagnosis, glenoid erosion, and preoperative or early subluxation. Late subluxation superiorly was associated with the glenoid at risk for radiographic failure (P=.006). Glenoid component survivals free from revision at 5 and 10 years for the 302 shoulders were 99% (95% CI) (97-100%) and 93% (95% CI) (90-97%). Glenoid radiolucencies are seldom seen early, except beneath the faceplate. Glenoid radiolucencies develop, with notable changes 5 or more years following surgery. Humeral components seldom loosen. Revision rates remain low. The high frequency of late radiographic changes dictates the need for innovation.

Rates of Radiolucency and Loosening After Total Shoulder Arthroplasty with Pegged or Keeled Glenoid Components

The objective of this study was to conduct a meta-analysis and cost-effectiveness analysis of the effect of glenoid design on radiolucency, loosening, and revision after total shoulder arthroplasty. We conducted a systematic review of PubMed, MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and CINAHL with use of a search for the terms arthroplasty AND shoulder AND (peg OR keel). Data on study design and on the end points of radiolucency, loosening, and revision were extracted independently and in duplicate. Random-effect models were used to calculate the pooled risk ratio and risk difference. The risk difference was used to estimate the number needed to treat (the number of individuals who would have to receive a pegged component to avoid one loosening or revision). Eight studies with a total of 1460 patients (mean age, sixty-seven years) were included. The mean study quality was 1.75 points (95% confidence interval [CI], 1.26 to 2.24) on the 3-point modified Jadad scale. There was no significant difference in the risk of any radiolucency (risk ratio, 0.42; 95% CI, 0.12 to 1.42) or in the risk of severe radiolucency (risk ratio, 0.65; 95% CI, 0.23 to 1.82) between pegged and keeled components. The pooled risk ratio for revision was 0.27 (95% CI, 0.08 to 0.88) in favor of pegged components (p = 0.028). At a cost-effectiveness threshold of $50,000 per quality-adjusted life year, pegged components can be between $2325 and $40,920 more expensive than keeled components and still be cost-effective. Our study produced evidence that pegged glenoid components were associated with a lower revision risk compared with keeled components. However, the difference was rather small and will therefore be most meaningful to high-volume shoulder arthroplasty centers. Because of the similarity between primary and secondary costs, pegged glenoid designs were more cost-effective than keeled glenoid designs.

Glenoid Component Design and Fixation in Total Shoulder Arthroplasty

Glenoid component loosening is one of the most common complications of total shoulder arthroplasty. It accounts for poor functional outcome, persistent pain, and increased chance of reoperation. Many factors contribute to this phenomenon, including limited glenoid bone, especially in the setting of erosion characteristic of osteoarthritis and inflammatory arthropathies, and joint-reactive forces inherent to the shoulder joint. A great deal of research has been done in the areas of component design and implantation technique. We advocate careful glenoid preparation and pressurized cementing technique of all-polyethylene pegged or keeled glenoid components with specialized instrumentation in the majority of cases. We have narrower indications for newer, ingrowth tantalum components.

Important Factors in the Development of Loosening of Polyethylene Keeled Glenoid Components in Shoulder Arthroplasty for Primary Osteoarthritis: The European Experience

Important Factors in the Development of Loosening of Polyethylene Keeled Glenoid Components in Shoulder Arthroplasty for Primary Osteoarthritis: The European Experience

Heat Generated With Pegged or Keeled Glenoid Components Fixed With Defined Amounts of Cement

Glenoid component loosening is a common complication of total shoulder arthroplasty and has been associated with the progression of radiolucent lines at the glenoid bone-cement interface. Generation of heat during the exothermic reaction of cement curing may cause osteonecrosis of bone, potentially leading to the development of radiolucent lines. The purpose of this study was to measure the heat generated with various defined amounts of cement used for glenoid component fixation.Ten fresh-frozen cadaver scapulas were randomized to receive a keeled or pegged component with 1, 2, 3, 5, or 7 g of cement for fixation. An infrared camera was used to record the surface temperature generated during the cement curing process to an accuracy of ±2.0°C. Computed tomography was used to evaluate the cement mantle. The maximum temperatures generated did not exceed the critical value for osteonecrosis (56°C) in any of the specimens. The 4 specimens without a complete mantle were those fixed with a smaller quantity of cement (1, 2, or 3 g), and the largest cement mantle thicknesses were observed with the use of 7 g of cement.Up to 7 g of cement can be used without significant concern for thermal necrosis. Incomplete cement mantles were observed when ≤3 g of cement was used for fixation. Our results suggest that surgeons should use >3 g of cement to avoid incomplete cement mantles and that up to 7 g of cement can safely be used for glenoid fixation.

Patterns of Loosening of Polyethylene Keeled Glenoid Components After Shoulder Arthroplasty for Primary Osteoarthritis

The aim of this study was to radiographically analyze the long-term glenoid migration patterns following total shoulder arthroplasty to better understand the factors responsible for loosening. Complete radiographic follow-up of more than five years was available for 518 total shoulder arthroplasties performed for primary glenohumeral osteoarthritis with use of an anatomically designed prosthesis with a cemented, all-polyethylene, keeled glenoid component. Radiographs were assessed for humeral head subluxation, periprosthetic radiolucent lines, and shifting of the position of the glenoid component. The type of migration of the glenoid was defined according to the direction of tilt, or as subsidence in the case of medial migration. Definite radiographic evidence of glenoid loosening was observed in 166 shoulders (32%) and was characterized by radiolucency of ≥2 mm over the entire bone-cement interface in thirty shoulders and by a migration of the glenoid component (shift or subsidence) in 136 shoulders. Three predominant patterns of migration of the glenoid component were observed: superior tilting in fifty-two shoulders (10%), subsidence in forty-one shoulders (7.9%), and posterior tilting in thirty-three shoulders (6.4%). Superior tilting of the glenoid was associated with three risk factors: low positioning of the glenoid component, superior tilt of the glenoid component on the immediate postoperative coronal plane radiographs, and superior subluxation of the humeral head (p < 0.05 for all). Subsidence of the glenoid component was associated with the use of reaming to optimize the seating and positioning of the glenoid component (p < 0.001). Posterior tilting of the glenoid component was associated with preoperative posterior subluxation (i.e., a Walch type-B glenoid) and with excessive reaming (p < 0.01 for both). The three patterns of migration observed in this study underscore the potential importance of the supporting bone beneath the glenoid component. In some shoulders, use of a keel or pegs to provide fixation of a polyethylene component in the absence of good support from subchondral bone may not be sufficient to resist compressive and eccentric forces, resulting in loosening. Preserving subchondral bone may be important for long-term longevity of the glenoid component.

A multicentre study of the long-term results of using a flat-back polyethylene glenoid component in shoulder replacement for primary osteoarthritis

We report the long-term clinical and radiological outcomes of the Aequalis total shoulder replacement with a cemented all-polyethylene flat-back keeled glenoid component implanted for primary osteoarthritis between 1991 and 2003 in nine European centres. A total of 226 shoulders in 210 patients were retrospectively reviewed at a mean of 122.7 months (61 to 219) or at revision. Clinical outcome was assessed using the Constant score, patient satisfaction score and range of movement. Kaplan-Meier survivorship analysis was performed with glenoid revision for loosening and radiological glenoid loosening (SD) as endpoints. The Constant score was found to improve from a mean of 26.8 (SD 10.3) pre-operatively to 57.6 (SD 20.0) post-operatively (p < 0.001). Active forward flexion improved from a mean of 85.3° (SD 27.4) pre-operatively to 125° (SD 37.3) postoperatively (p < 0.001). External rotation improved from a mean of 7° (SD 6.5) pre-operatively to 30.3° (SD 21.8°) post-operatively (p < 0.001). Survivorship with revision of the glenoid component as the endpoint was 99.1% at five years, 94.5% at ten years and 79.4% at 15 years. Survivorship with radiological loosening as the endpoint was 99.1% at five years, 80.3% at ten years and 33.6% at 15 years. Younger patient age and the curettage technique for glenoid preparation correlated with loosening. The rate of glenoid revision and radiological loosening increased with duration of follow-up, but not until a follow-up of five years. Therefore, we recommend that future studies reporting radiological outcomes of new glenoid designs should report follow-up of at least five to ten years.

Results of a convex-back cemented keeled glenoid component in primary osteoarthritis: multicenter study with a follow-up greater than 5 years

We assessed the clinical and radiologic results of a cemented all-polyethylene convex-back keeled glenoid component used with a third-generation prosthesis. Between 1996 and 2003, in 4 European centers, 333 shoulder arthroplasties were performed for primary osteoarthritis by use of a cemented all-polyethylene convex-back keeled glenoid component. Kaplan-Meier survivorship analysis was performed, and clinical outcome was assessed with the Constant score, range of motion, and subjective evaluation. At a mean of 89.5 months' follow-up, the Constant score improved from 31.4 to 67.6 points (P < .0001). Active forward elevation improved from 94.9° to 146.6° (P < .0001) and external rotation from 9.0° to 35.3° (P < .0001). Of the patients, 93.5% were either satisfied or very satisfied. The rate of revision for glenoid loosening was 0.6%; however, the rate of radiologic glenoid loosening was 18.9%. Glenoid survival was 99.7% at 5 years and 98.3% at 10 years with endpoint defined as revision surgery for glenoid loosening and 99.7% at 5 years and 51.5% at 10 years with endpoint defined as radiologic loosening. We showed highly satisfactory clinical outcomes and extremely low rates of revision for glenoid loosening using a cemented convex-back keeled glenoid. There was a concerning rate of radiologic loosening, which only became apparent after 5 years, and this was associated with excessive glenoid reaming. Because radiologic changes are progressive and precede the need for revision, innovations in this field need to report radiologic and clinical results with follow-up of at least 5 to 10 years to prove any superiority.

Radiographic comparison of pegged and keeled glenoid components using modern cementing techniques: A prospective randomized study

Modern cementing techniques have improved glenoid fixation, reduced glenoid lucency seen with keeled components, and may eliminate differences attributable to glenoid design. The purpose of this study was to determine the effect of glenoid design on immediate and follow-up radiographic lucency of pegged and keeled glenoid components, using modern cementing techniques. Fifty-three total shoulder arthroplasties were performed in patients with primary glenohumeral osteoarthritis. Patients were randomized prospectively to receive either a pegged or keeled glenoid component. Three raters graded radiographic glenoid lucencies. On immediate radiographs, there was no significant difference in the rate of glenoid lucency between pegged (0%) and keeled (15%) glenoid components (P = .128). However, after an average of 26 months, the rate of glenoid lucency was significantly higher in patients with keeled components (46%) compared to patients with pegged components (15%) (P = .003). Even with modern cementing techniques, pegged glenoid components remain radiographically superior to keeled glenoid components.

Pegged versus keeled glenoid components in total shoulder arthroplasty

Loosening of the glenoid component is a common complication in shoulder arthroplasty. We proposed to radiographically and clinically investigate the outcomes of keeled and pegged glenoid components to test the hypothesis that these implants would have equivalent performance. One hundred patients undergoing primary shoulder arthroplasty for osteoarthritis were reviewed. Fifty patients had pegged glenoid components, and fifty had keeled components. Standardized radiographs were taken. Preoperative films classified the severity of degenerative change. The postoperative films were analyzed for radiolucent lines and shift in component position-at-risk signs for loosening. Mean radiographic follow-up was 51.3 months (range, 24-90 months) for the keeled group and 45.7 months (range, 27-98 months) for the pegged group. There were no differences in the degree of preoperative arthritic change between groups. Both groups had significant improvement in motion and pain (P < .001) postoperatively, with no differences in clinical outcome between cohorts (P > or = .20). Initial radiographs showed no radiolucencies around the pegs in 46 implants or around the keel in 49 components. At final follow-up, 10 glenoid implants were found to be at risk for loosening, 6 (12%) in the pegged group and 4 (8%) in the keeled group (P = .74). Initial postoperative radiographs with pegged and keeled components show a low rate of radiolucent lines. These radiolucencies develop over time. However, there is no difference in clinical or radiographic outcomes between pegged and keeled components at intermediate-term follow-up.

Stability of Cemented in-Line Pegged Glenoid Compared with Keeled Glenoid Components in Total Shoulder Arthroplasty

Stability of Cemented in-Line Pegged Glenoid Compared with Keeled Glenoid Components in Total Shoulder Arthroplasty

Stability of Cemented in-Line Pegged Glenoid Compared with Keeled Glenoid Components in Total Shoulder Arthroplasty

Considerable interest has been focused on the design of the glenoid component used in total shoulder arthroplasty in order to reduce the risk of loosening. One design-related feature that has attracted attention is whether to use pegged or keeled cemented glenoid components. The main purpose of this study was to compare the fixation of cemented keeled glenoid components with that of cemented in-line pegged glenoid components. In a prospective randomized study, we compared the stability of cemented, all-polyethylene, keeled glenoid components and cemented, all-polyethylene, in-line three-pegged glenoid components by radiostereometric analysis. Twenty-seven shoulders in twenty-five patients with osteoarthritis (twenty-two shoulders had primary and five shoulders had secondary osteoarthritis) were included. There were sixteen women and nine men, and the mean age was sixty-four years. Radiostereometric analysis and conventional radiographs were carried out at five days, at four months, and at one and two years postoperatively. The mean Constant and Murley score preoperatively and two years postoperatively was 25 and 70, respectively, for shoulders with the keeled glenoid component and 22 and 70 for the shoulders with a pegged component. No significant difference was detected between groups with regard to the average micromigration of the glenoid components at any of the time points. The average translation was <1 mm, while the median value was <0.3 mm at two years, with no significant difference between the different axes. In five shoulders (three with the keeled component and two with the pegged component), translation at two years was >1 mm. In fourteen shoulders (eight with the keeled and six with the pegged component), the rotation around one or several axes was >2 degrees . We were not able to detect any specific pattern with regard to movement for either type of component nor were we able to detect any difference between the two types of components in the way they migrated, if migration occurred. Cemented all-polyethylene keeled or in-line three-pegged glenoid components appear to have similar stability during the first two years after surgery. Studies with a longer follow-up period are needed to relate these findings to long-term clinical and radiographic outcomes.

A study of the micromovement of pegged and keeled glenoid components compared using radiostereometric analysis

In a prospective, randomized study between 2000 and 2004, 20 patients with primary osteoarthritis of the shoulder had a total shoulder arthroplasty with radiostereometric analysis, 10 with keeled and 10 with pegged glenoid components. The relative movement of the glenoid component with respect to the scapula was measured over a 24-month period. Three keeled and five pegged glenoids needed reaming for erosion. The largest translations occurred along the longitudinal axis (mean of 1.35 mm for keeled eroded components) (P = .017 for keeled vs pegged components and P = .013 for eroded vs non-eroded components). Both of the other translation axes showed no significant differences. The highest maximum total point movement at 24 months was 2.57 mm for keeled eroded components and 1.64 mm for pegged eroded components (P = .029 for keeled vs pegged components and P = .023 for eroded vs non-eroded components). The largest rotation was anteversion, with mean values of 5.5 degrees for keeled eroded components and 4.8 degrees for pegged eroded components (P = .658 for keeled vs pegged components and P = .90 for eroded vs non-eroded components). The mean varus tilt was 4.5 degrees for keeled eroded components compared with 2.3 degrees for pegged eroded components (P = .004 for keeled vs pegged components and P = .016 for eroded vs non-eroded components), and finally, anterior-posterior rotation mean values were 3.5 degrees for keeled eroded components and 1.1 degrees for pegged eroded components (P = .022 for keeled vs pegged components and P = .04 for eroded vs non-eroded components). In conclusion, whereas all components moved, radiostereometric analysis revealed increased migration with keeled components, exacerbated by glenoid erosion. Furthermore, a distinctive pattern of migration was identified over the 2-year period.

Stability of Cemented All-Polyethylene Keeled Glenoid Components: A Radiostereometric Study With a Two-Year Follow-up

Stability of Cemented All-Polyethylene Keeled Glenoid Components: A Radiostereometric Study With a Two-Year Follow-up