The pathology most frequently identified in the study was a meniscal tear. The mi-eye+TM was more sensitive than MRI in identifying meniscal tears (92.6% vs 77.8%; P = .0035) and more specific in diagnosing these tears (100% vs 87.5%; P < .0002). The difference in specificity resulted from the false MRI diagnosis of a meniscal tear among 24 patients, who were found to have no tear by both mi-eye+TM and surgical arthroscopy.
Table 1. Raw Data of mi-eye+TM and Magnetic Resonance Imaging Findings
| Data | True-Positive | False-Negative | False-Negative | True-Negative |
| mi-eye+TM | ||||
| Medial meniscal tear | 68 | 3 | 0 | 35 |
| Lateral meniscal tear | 32 | 5 | 0 | 69 |
| Any meniscal tear | 100 | 8 | 0 | 104 |
| Intra-articular loose body | 13 | 2 | 0 | 87 |
| Osteoarthritis | 31 | 2 | 00 | 73 |
| Osteochondritis dissecans | 8 | 2 | 0 | 97 |
| Anterior cruciate ligament tear | 16 | 0 | 0 | 90 |
| Posterior cruciate ligament tear | 0 | 0 | 0 | 106 |
| All pathologies | 168 | 14 | 0 | 557 |
| Magnetic resonance imaging | ||||
| Medial meniscal tear | 62 | 9 | 6 | 29 |
| Lateral meniscal tear | 22 | 15 | 7 | 62 |
| Any meniscal tear | 84 | 24 | 13 | 91 |
| Intra-articular loose body | 3 | 12 | 0 | 87 |
| Osteoarthritis | 26 | 7 | 8 | 65 |
| Osteochondritis dissecans | 5 | 5 | 4 | 93 |
| Anterior cruciate ligament tear | 14 | 2 | 3 | 87 |
| Posterior cruciate ligament tear | 0 | 0 | 2 | 104 |
| All pathologies | 132 | 500 | 30 | 527 |
The second most frequent pathology was an intra-articular loose body. The mi-eye+TM was more sensitive than MRI in identifying loose bodies (86.7% vs 20%; P = .0007). The specificity of the mi-eye+TM and the specificity of MRI were equivalent in diagnosing loose bodies (100%). Table 1 and Table 2 show the complete set of diagnoses and associated diagnostic profiles.
Table 2. Diagnostic Profiles: Sensitivity and Specificity of mi-eye+TM and Magnetic Resonance Imaging
| Patient Group | mi-eye+TM | MRI | |||
| Estimate, % | CI, % | Estimate, % | CI, % | Pa | |
| Sensitivity | |||||
| Medial meniscal tear | 95.77 | 88.1-99.1 | 87.32 | 77.3-94.0 | .0129 |
| Lateral meniscal tear | 86.49 | 71.2-95.5 | 59.46 | 42.1-75.3 | .0172 |
| Any meniscal tear | 92.59 | 85.9-96.8 | 77.78 | 68.8-85.2 | .0035 |
| Intra-articular loose body | 86.70 | 59.5-98.3 | 20 | 4.3-48.1 | .0006789 |
| Osteoarthritis | 93.90 | 79.8-99.3 | 78.80 | 61.1-91.0 | .1487 |
| Osteochondritis dissecans | 80.00 | 44.4-97.5 | 50 | 18.7-81.3 | .3498 |
| Anterior crucitate ligament tear | 100.00 | 79.4-100.0 | 87.50 | 61.7-98.4 | .4839 |
| Posterior cruciate ligament tear | N/A | N/A | N/A | N/A | N/A |
| Specificity | |||||
| Medial meniscal tear | 100.00 | 90.0-100.0 | 82.86 | 66.4-93.4 | .0246 |
| Lateral meniscal tear | 100.00 | 94.8-100.0 | 89.86 | 80.2-95.8 | .0133 |
| Any meniscal tear | 100.00 | 96.5-100.0 | 87.50 | 79.6-93.2 | .0002 |
| Intra-articular loose body | 100.00 | 95.9-100.0 | 100.00 | 95.9-100.0 | 1 |
| Osteoarthritis | 100.00 | 95.1-100.0 | 89.00 | 79.5-95.1 | .006382 |
| Osteochondritis dissecans | 100.00 | 96.3-100.0 | 95.90 | 89.8-98.9 | .1211 |
| Anterior cruciate ligament tear | 100.00 | 96.0-100.0 | 96.70 | 90.6-99.3 | .2458 |
| Posterior crttuciate ligament tear | 100.00 | 96.6-100.0 | 98.10 | 93.4-99.8 | .4976 |
aBold P values are significant. Abbreviations: CI, confidence interval; MRI, magnetic resonance imaging; N/A, not applicable.
DISCUSSION
The overall accuracy of the mi-eye+TM was superior to that of MRI relative to the arthroscopic gold standard in this pilot study. Other studies have demonstrated the accuracy, feasibility, and cost-efficacy of in-office arthroscopy. However, likely because of the cumbersomeness of in-office arthroscopy equipment and the potential for patient discomfort, the technique is not yet standard in the field. Recent advances in small-bore technology, digital optics, and ergonomics have addressed the difficulties associated with in-office arthroscopy, facilitating a faster and more efficient procedure. Our goal in this study was to evaluate the diagnostic capability of the mi-eye+TM in-office arthroscopy unit, which features a small bore, digital optics, and functionality without an irrigation tower.
This study of 106 patients demonstrated equivalent or better accuracy of the mi-eye+TM relative to MRI when compared with the gold standard of surgical arthroscopy. This was not surprising given that both the mi-eye+TM and surgical arthroscopy are based on direct visualization of intra-articular pathology. The mi-eye+TM unit identified more meniscal tears, intra-articular loose bodies, ACL tears, and OCD lesions than MRI did, and with enough power to demonstrate statistically significant improved sensitivity for meniscal tears and loose bodies. Furthermore, MRI demonstrated false-positive meniscal tears, ACL tears, OCD lesions, and OA, whereas the mi-eye+TM did not demonstrate any false-positive results in comparison with surgical arthroscopy. This study demonstrated statistically significant improved specificity of the mi-eye+ compared with MRI in the diagnosis of meniscal tears and OA.
There are several limitations to our study. We refer to it as a pilot study because it was performed in a standard operating room. Before taking the technology to an outpatient setting, we wanted to confirm efficacy and safety in an operating room. However, the techniques used in this study are readily transferable to the outpatient clinic setting and to date have been used in more than 2000 cases.
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