Abstract
Introduction
Humeral radiolucent lines after anatomic TSA (aTSA) have been well described; however, little clinical consequences have been attributed to them. The recent emergence of shorter humeral stems has demonstrated higher incidences of humeral radiolucencies than has been reported historically with standard length components. This large scale database analysis quantifies and compares the clinical outcomes of aTSAs with and without radiolucent humeral lines using one specific prosthesis to determine their impact on clinical outcomes.
Methodology
This is a multicenter, retrospective, case controlled radiographic and clinical review. Preoperative and postoperative data was analyzed from 671 aTSA patients with a minimum of 2 years followup. 538 of these 671 aTSA patients had full radiographic followup (80.2%) and were included in this study; these patients had an average followup of 45.3 months). 459 patients had noncemented humeral stems; whereas, 79 patients had cemented humeral stems. Radiographs were reviewed at latest follow up for humeral radiolucent lines based on the technique described by Gruen et al. Patients were evaluated and scored pre-operatively and at latest follow-up using the SST, UCLA, ASES, Constant, and SPADI scoring metrics; ROM was also recorded. A Student's two-tailed, unpaired t-test was used to identify differences in pre-operative, post-operative, and improvement in results, where p<0.05 denoted a significant difference.
Results
All patients demonstrated significant improvements in pain and function following treatment with the primary shoulder arthroplasty. 14 patients (8 female, avg: 65.6 yrs; 6 male, avg: 61.7 yrs) were observed to have radiolucent lines around the humeral component (2.6%). The rate of humeral radiolucent lines was observed to be significantly higher in patients with cemented (7.6%) vs. noncemented (1.7%) humeral stems (p = 0.0025). Pre-operatively, no difference was noted in any clinical metric score between patients with or without radiolucent humeral lines. (Figure 1) However post-operatively, patients with radiolucent humeral lines had significantly worse ASES (p=0.0087), UCLA (p=0.0371), SST (p=0.0341), and SPADI (p=0.0051) scores (Figure 2) and significantly lower improvements in outcomes according to ASES (p=0.0120) and SPADI (p=0.0247) scores (Figure 3), relative to patients without radiolucent humeral lines. Additionally, radiolucent lines had a more profound effect on cemented stems (as compared to noncemented stems), where cemented stems with radiolucent humeral liners were associated with significantly lower post-operative outcomes and significantly lower improvements in outcomes. Finally, patients with humeral radiolucent lines had a significantly higher complication rate (21.4% vs 4.6%, p = 0.004) as compared to the complication rate of patients without radiolucent humeral lines.
Conclusions
The study demonstrated a relatively low incidence of humeral radiolucent lines with anatomic TSA. Cemented stems were associated with a significantly higher rate of humeral radiolucent lines as compared to noncemented stems. Patients whose shoulders had radiolucent humeral lines were associated with significantly lower clinical outcomes and significantly less active ROM as compared to those without radiolucent lines. This diminished outcome was more pronounced with cemented humeral stems. Additional and longer term clinical followup is necessary to confirm the results of this study.
