The aspiration test: an arthroscopic sign of lateral meniscus posterior horn instability

Christophe Jacquet,Romain Seil,Amanda Magosch,Caroline Mouton

doi:10.1186/s40634-021-00327-0

Abstract

The suspensory mechanism of the posterior horn of the lateral meniscus (PHLM) is an anatomically complex structure including the popliteomeniscal fascicles, the meniscotibial posterior root attachment and the meniscofemoral ligaments. Damage to one or several of these structures – either through knee trauma or congenital abnormalities—can result in an instability of the PHLM that may lead to lateral knee pain, locking sensations or lack of rotational control of the knee (e.g. after anterior cruciate ligament injuries). The diagnosis of PHLM instability is complex due to the lack of reliable clinical tests and imaging signs. Direct visual dynamic inspection via arthroscopy thus remains the gold standard. However, arthroscopic probing of the PHLM is not always reliable and the precise quantification of the amount of subluxation of the PHLM can be difficult. Therefore, the main objective of this report was to describe a quick and easy arthroscopic screening test called “the aspiration test” in order to help surgeons to detect PHLM instability. During the exploration of the lateral tibiofemoral compartment with the knee kept in the figure of 4 position, the arthroscope is placed in the antero-lateral portal and directed towards the lateral tibiofemoral compartment. The aspiration test is then performed by activating the aspiration of the 4-mm shaver when located in the intercondylar notch. In case of a PHLM instability, an excessive displacement of the PHLM is observed. After repair, a second aspiration test allows to verify that the PHLM has been stabilized.

Highlights

Identifying an instability of the posterior horn of the lateral meniscus (PHLM) can be challenging due to the lack of an appropriate, dynamic method to confirm the diagnosis
As magnetic resonance imaging (MRI) assesses the knee in Jacquet et al J EXP ORTOP (2021) 8:17 static conditions, it may not allow diagnosing the instability of the PHLM that occurs during knee motion
Knee flexion is increased to 90° to ‘plunge’ the arthroscope in the popliteal space. This technique allows the visualization of the posterior tibia, the menisco-tibial capsular attachments, the popliteo-fibular ligament, the posterosuperior popliteo-meniscal fascicles (PMF) (PS-PMF) (Fig. 1b), the posterior lateral femoral condyle and the posterior aspect of the lateral meniscus

Summary

Introduction

Identifying an instability of the posterior horn of the lateral meniscus (PHLM) can be challenging due to the lack of an appropriate, dynamic method to confirm the diagnosis. Knee flexion is increased to 90° to ‘plunge’ the arthroscope in the popliteal space This technique allows the visualization of the posterior tibia, the menisco-tibial capsular attachments, the popliteo-fibular ligament, the posterosuperior PMF (PS-PMF) (Fig. 1b), the posterior lateral femoral condyle and the posterior aspect of the lateral meniscus. Anterior arthroscopic inspection of the PHLM The second arthroscopic method to evaluate the stability of the PHLM is the classic anterior view with the knee held in a figure-of-4 position [16] This method has several disadvantages like the impossibility or difficulty to directly assess the PMF’s and the limited joint line opening of the lateral tiobiofemoral compartment in narrow knees It does allow for a direct visualization of the posterior root of the lateral meniscus (PRLM) and of the meniscofemoral ligaments. After repair of the PHLM and its suspensory mechanism, a second aspiration test allows to verify that the PHLM has been stabilized. (Video 1 and Video 4)

Discussion

Findings

Compliance with ethical standards