KOBEUNIVERSITY

Concomitant Lateral Meniscus Injury Aggravates Rotational Laxity

of the Anterior Cruciate Ligament Injured Knees.Yuichi Hoshino1,2, Nobuaki Miyaji2, Toshikazu Tanaka2, Kazuyuki Ibaragi2, Kyohei Nishida2,

Yuichiro Nishizawa2,3, Daisuke Araki2, Noriyuki Kanzaki2, Takehiko Matsushita2, Ryosuke Kuroda2

There are still some cases which have residual rotational laxity after the anterior cruciate

ligament (ACL) reconstruction. Not only the ACL but also the secondary restraint against the

rotational laxity is suggested to cause this problem, but detection and treatment of the

secondary restraint are difficult due to lack of meticulous evaluation systems.

Recently several measurement systems for the rotational laxity have been developed to be

available for clinical use, such as an electromagnetic system [1], an accelerometer [2], and an

iPad app[3].

Several anatomic structures are suggested to be the secondary restraint for the rotational

laxity of the knee. Although anterolateral ligamentous structure of the knee has increasingly

been focused on, meniscus injury is frequently accompanied with the ACL injury and assumed

to have significant impact on the rotational laxity based on previous studies. [4,5]

However, it is still unknown how much the concomitant meniscus injury affects the

rotational laxity of the ACL-deficient knees in-vivo. As reported by Musahl et al [6] using the

iPad system, our electromagnetic measurement of the pivot-shift test might be used to

quantify the effect of the meniscus injury in clinical cases. The purpose of this study was to

determine the effect of the meniscus tear on the rotational laxity in the ACL-deficient using

the electromagnetic measurement system.

OBJECTIVES

Fifty-seven unilateral ACL-injured patients (26 males and 31 females, 24±10 y.o.) were

tested. The protocol of this study was approved by the Institutional Review Board in Kobe

University, and the informed consent was obtained from all the patients.

The pivot-shift test was performed under general anesthesia during their ACL

reconstruction. (Figure.1)

METHODS

1. Hoshino Y, et al. Am J Sports Med. 2007 Jul;35(7):1098-104

2. Lopomo N, et al. Knee Surg Sports Traumatol Arthrosc. 2012 Apr;20(4):713-7.

3. Hoshino Y, et al. Knee Surg Sports Traumatol Arthrosc. 2013 Apr;21(4):975-80.

4. Musahl V, et al. Am J Sports Med. 2010 Aug;38(8):1591-7

5. Shybut TB, et al. Am J Sports Med. 2015 Apr;43(4):905-11

6. Musahl V, et al. Am J Sports Med. 2016 Dec;44(12):3126-3131

REFERENCES

Although the meniscus injury is the most common in addition to the ACL injury, the impact of

the meniscus injury on the knee rotational laxity has not been fully examined. Similar to the

report by Musahl et al [6], this study demonstrated the significant impact of the meniscus

injury, especially lateral meniscus injury, on the rotational laxity in the ACL-deficient knees,

which was successfully detected in clinical cases by using the quantitative measurement device.

A careful inspection of the lateral meniscus tear should be required in the ACL-deficient

knees with a substantial pivot-shift and, if there is any, it should be repaired as much as

possible to avoid additional rotational laxity

RESULTS

Concomitant meniscus tear was observed in 32 knees.

ACKNOWLEDGEMENTS

CONCLUSIONS

This work was supported by JSPS KAKENHI (No. JP16K10902)

1. Department of Orthopaedic Surgery, Kobe Kaisei Hospital, Kobe, Japan.

2. Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.

3. Department of Orthopaedic Surgery, Shinsuma Hospital, Kobe, Japan.

Clinical grading according to the IKDC (none, glide, clunk, and gross) was determined,

whereas the quantitative assessment of the pivot-shift was conducted using electromagnetic

measurement system to provide the tibial acceleration (m/sec2). [1]

Meniscus injuries were finally confirmed under arthroscopy during the ACL reconstruction.

The difference of clinical grading and tibial acceleration between the ACL-injured knees with

and without additional meniscus tear was assessed by chi-square test and independent t-test

respectively.

Subgroup analysis was then performed in the same manner for each medial and lateral

meniscus tear separately. Statistical significance was set at p-value of 0.05.

Figure.1

In-vivo quantitative evaluation of the

pivot-shift test using an electromagnetic

measurement system.

EM receivers

EM Transmitter

The tibial acceleration (m/sec2) was calculated based on

the 6 degree-of-freedom of knee kinematics which was

reflected by the relative motion between the sensors.

Meniscus

intact

(n=25)

Meniscus

tear

(n=32)

Medial

meniscus

tear (n=20)

Lateral

meniscus

tear (n=19)

Pivot-

shift

clinical

grading

Glide (+) 15cases 12cases 7cases 6cases

Clunk (++) 10cases 18cases 11cases 13cases

Gross (++) 0cases 2cases 1cases 1cases

P-value vs meniscus

intact knees0.04 0.02 0.03

Tendency of increased

pivot-shift measurements in

the meniscus torn knees was

demonstrated by the

quantitative evaluation, but

statistical significance was

not achieved (p=0.09).

Subgroup analysis showed

that the ACL-deficient knees

with lateral meniscus tear

had larger tibial acceleration

than the meniscus-intact

knees (p<0.05), whereas the

medial meniscus torn knees

did not show aggravated

rotational laxity (p=0.33)

There was a significant difference

of clinical grading between the ACL-

injured knees with and without

meniscus tear (p<0.05).

Also, significant difference was

observed for each medial and lateral

meniscus torn knee, separately. (p=

0.02 and 0.03, medial and lateral,

respectively )

DISCLOSURE

All authors has no conflicts of interest for this study.

AOSSM annual meeting July.20-23. 2017 in Toronto, CanadaPoster 220