Page 33 - ISAKOS 2018 Winter Newsletter

CURRENT CONCEPTS
We concluded that the EMS method has an advantage over the KiRA and iPad methods because it provides a more comprehensive and accurate evaluation both tibial acceleration and translation.
Investigating the Effect of the Concomitant Meniscal Tear on the Pivot-Shift
Although meniscal injury commonly occurs in association with ACL injury, the impact of meniscal injury on knee rotational laxity has not been fully examined, especially in vivo, mainly because of the lack of instrumented measurement systems. Musahl et al., in an in vivo study involving the iPad measurement system, demonstrated increased lateral translation during the pivot-shift test when knees that had ACL injury combined with meniscal and anterolateral capsule injuries were compared with knees that had an isolated ACL injury. We also tested the effect of the concomitant meniscal tear on the pivot-shift test in a clinical study of 57 knees with an ACL injury. A concomitant meniscal tear was confirmed in 32 knees. Clinical grading was different between the knees with and without a meniscal tear (p < 0.05), whereas tibial acceleration was not significantly different between these groups (1.6 ± 1.1 m/sec for knees with a meniscal tear, compared with 1.3 ± 0.8 m/sec for knees without a meniscal tear; p = 0.09). Subgroup analysis showed that the ACL-deficient knees with lateral meniscus tear had larger tibial acceleration (1.8 ± 1.1 m/sec, n = 19) than those without a meniscal tear (p < 0.05), whereas the knees with a medial meniscus tear (1.4 ± 1.0 m/sec, n = 20) did not show aggravated rotational laxity (p = 0.33) (Fig. 5). This investigation was reported in 2017 at the 11TH ISAKOS Congress in Shanghai and received the Jan I. Gillquist Scientific Research Award.
Both the iPad and electromagnetic measurement systems could detect the effect of a concomitant meniscus tear on the pivot shift in ACL-injured knees. It is difficult to achieve similar results with use of manual examination during the pivot-shift test. Significant but subtle influences of such secondary restraint injuries should be further tested with use of instrumented measurements.
Conclusion
Several non-invasive instrument systems are currently available for use in clinical practice, although their accessibilities are geographically different to some extent. The electromagnetic system might provide higher diagnostic accuracy and comprehensive evaluation of the pivot shift than the other instruments, whereas the iPad or accelerometer system might be more user-friendly tools with acceptable diagnostic accuracy.
The use of instrumented measurement systems during the pivot-shift test is required in order to detect subtle but significant differences between various injury patterns and treatments of the ACL-injured knees. As a result, further advancements in ACL treatment will likely depend on the use of such systems when performing the pivot-shift test.
05
03 The commercially available electromagnetic knee kinematics measurement instrument (Joint Instability Measurement Interface JIMI Kobe; Arthrex Japan, Tokyo, JAPAN). This device is an all-in-one unit that contains an electromagnetic tracking system and a processing computer.
04 iPad image analysis. The markers on the lateral side of the knee joint are captured by the iPad during the pivot-shift test.
05 The tibial acceleration during the pivot-shift test in the ACL-deficient knees with and without concomitant meniscus tear. There was a significant difference between the ACL-injured knees with an intact meniscus and those with torn lateral meniscus.
ISAKOS NEWSLETTER 2018: VOLUME I 31