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Abstract

Introduction: This study evaluated the survivorship of pegged versus keeled cemented, all-polyethylene glenoid components using modern cementing and glenoid preparation techniques. Survival of glenoid design was determined according to severity of radiolucencies on follow-up radiographs.

Methods: Between April 22, 1999, and February 17, 2009, retrospective chart review was performed on 194 total shoulder arthroplasties performed by a single fellowship-trained shoulder surgeon. A minimum of 3 year follow-up was established. Scapular plane anteroposterior radiographs (Grashey view) were analyzed and graded for the degree of radiolucency surrounding the glenoid anchor using Franklin’s method for keeled components and a modification of that method for pegged components. Radiographs were evaluated by 3 raters who independently graded radiographs for each patient in this study. Unpaired 2-tailed t-test was used to calculate significance, p < 0.05. Interobserver correlation was computed using the intraclass correlation coefficient (ICC) 2-way mixed model with measures of absolute agreement to analyze the measurement reliability. Values of ICC range from 0 to 1, with a higher value indicating better reliability. ICC less than 0.40 is considered poor; 0.40 to 0.59 as fair; 0.60 to 0.74 as good; and 0.75 to 1.00 as excellent. Active forward elevation (AFE) and active external rotation (AER) were recorded before and after surgery. The range of motion scores for pegged glenoids was compared to keeled glenoids, as well as grading lucency from 0-1 to >1 lucency.

Results: Fifty-two total shoulders in 45 patients met the inclusion criteria, with 36 pegged glenoid components and 16 keeled components. Average length of follow up was 67 months (range 36 to 128 months). Average radiolucency was 1.01 on a modified Franklin scale of 0 to 5 in the pegged glenoid component group, compared to 1.90 in the keeled group, (p<0.01). Interobserver correlation coefficient was 0.31. For the pegged group, AFE increased from 123° to 150°, and AER increased from 24° to 59°. For the keeled group, AFE increased from 105° to 148°, and AER increased from 14° to 59°. For grade 0-1 lucency, AFE increased from 120° to 151°, and AER increased from 20° to 56°. For grade >1 lucency, AFE increased from 114° to 148°, and AER increased from 21° to 61°.

Conclusions: Significantly greater component survival was found with pegged as opposed to keeled anchoring design. Poor interobserver reliability was noted with the Franklin grading system among othropaedic physicians at various levels of training. There did not appear to be a difference in range of motion between pegged and keeled glenoids or with respect to degree of radiolucency.

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