Demographic, Disease, and Imaging Model Parameters
| Parameter | Base case | Range | Reference |
| Demographics | |||
| Age < 65 y | 40.4% | 0%–100% | |
| Medicare-to-commercial reimbursement conversion factor | 1.5 | 1.17–1.95 | American Hospital Association’s aggregate hospital payment-to-cost ratio (66) |
| Disease-related | |||
| Prevalence of loosening/wear | 70.38% | 10%–94.95% | (14,16,20–26,28,30–32,34–41) |
| Prevalence of low-grade infection | 16.68% | 14.81%–80.52% | (14,16,20–25,28,30,31,34–41,51,63) |
| Prevalence of patellofemoral problems | 12.94% | 0%–68.75% | |
| Imaging-scan-related | |||
| SPECT/CT | |||
| Scan cost | $239.38 | — | Medicare national payment amount for CPT code 78320 (49) |
| Sensitivity | 98.42% | 97%–100% | (14,16,17) |
| Specificity | 91.34% | 68.5%–100% | (17) |
| Nondiagnostic rate | 3.17% | 0%–8.83% | (14,16,17) |
| CT | |||
| Scan cost | $115.20 | — | Medicare national payment amount for CPT code 73700/73701/73702 (49) |
| Sensitivity | 80.60% | 80%–81% | (67,68) |
| Specificity | 74% | 50%–98% | (69,70) |
| Nondiagnostic rate | 16.13% | 12.1%–20.2% | (63) |
| MARS-MRI | |||
| Scan cost | $646.72 | — | Medicare national payment amount for CPT code 73721/73722/73723 (49) |
| Sensitivity | 82.87% | 67%–100% | (24,67,69,71,72) |
| Specificity | 84.52% | 83%–88% | (71,72) |
| Nondiagnostic rate | 8.47% | 0%–16.1% | (63,71) |