2015 ISAKOS Biennial Congress ePoster #1102

Generalized Ligamentous Laxity as a Predictor of High-Grade Rotatory Knee Laxity

Kristian Samuelsson, MD, PhD, MSc, Prof., Mölndal SWEDEN
Volker Musahl, MD, Pittsburgh, PA UNITED STATES
James J. Irrgang, PT, PhD, FAPTA, Pittsburgh, PA UNITED STATES
Freddie H. Fu, MD, Pittsburgh, PA UNITED STATES
Yuichi Hoshino, MD, PhD, Kobe, Hyogo JAPAN
Ryosuke Kuroda, MD, PhD, Kobe, Hyogo JAPAN
Nicola Francesco Lopomo, PhD, MSc Eng, Bologna ITALY
Stefano Zaffagnini, MD, Prof., Bologna ITALY
Jon Karlsson, Prof., Mölndal SWEDEN

Department of Orthopaedic Surgery, Gothenburg, SWEDEN

FDA Status Not Applicable

Summary: Results suggests that there is a correlation between the Beighton Hypermobility Score and objective quantification of the Pivot shift test in an international multicenter study.

ePoster Not Provided
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Abstract:

Introduction

Patients with benign joint hypermobility syndrome (BJHS) are in general considered difficult in terms of evaluating kinematics before and after Anterior Cruciate Ligament (ACL) reconstruction. The main difficulty is to determine native knee laxity in the injured knee and any relationship to laxity of the healthy contralateral knee. Two different objective measurement devices for assessment of the pivot shift test are currently being evaluated in an international multicenter study. These devices have been utilized to assess rotational knee laxity in patients with BJHS.

Purpose

The purpose of this study was to evaluate the relationship between the Beighton Hypermobility Score (BHS) with objective quantification of the pivot shift test.

Level of Evidence
Prospective cohort study, Level 2

Methods

Thirty-four patients with unilateral ACL deficient knees at three different research sites were included. Two different methods to assess the rotational laxity were utilized and the involved and non-involved knees were compared. The accelerometer system (KiRA, Orthokey, Italy) and the image analysis system using an iPad (PIVOT Technicology, Pittsburgh, USA) were utilized. The measurements were performed by a senior orthopaedic surgeon before ACL reconstruction, both when the patients were awake and when the patients were under anesthesia. Spearman correlation coefficients were calculated between the BHS and the acceleration and image analysis values for the involved knee, non-involved knee and side to side difference. Furthermore, correlations coefficients were also calculated for the means for acceleration and image analysis values and a dichotomized BHS as 0 to 3 (low) versus 4 to 9 (high). Alpha was set at 0.05.

Results

When the patients were awake there were no significant correlations between the BHS and the accelerometer and image analysis values for the involved knee, non-involved knee and side to side difference. When the BHS was dichotomized, there was a significant side to side difference in mean acceleration values between awake patients with low BHS (-0.05 + 0.80) and high BHS (1.29 + 1.62), p=0.023. When the patients were under anesthesia, several significant findings were found in the image analysis system values but not in the acceleration system values. There was a significant correlation in the image analysis between the BHS and the involved knee (correlation 0.430, p=0.016) and the non-involved knee (correlation 0.493, p=0.004). Also, patients with low BHS had significantly lower mean translation values (2.51 ± 1.71) compared with patients with high BHS (3.99 ± 2.00), p=0.037.

Discussion

These results suggest there is a relationship between the BHS and the values from the image analysis system when the patients were under anesthesia. There was also a significant difference between the patients with low and high BHS in the involved knee. Why the acceleration measurement system did not detect these differences is yet to be discovered. The results also put light on the importance of measuring the pivot shift test when the patients are under anesthesia, especially in patients with BJHS. The reason for this is that these patients are known to use muscle defense to cope with a native hypermobile joint. Finally, it is of great importance to be able to analyze and quantify the important prognostic pivot shift test in these patients as they are not only known to have worse outcome than the general patient, but there is also evidence that the higher the BHS the higher risk that the patient will develop joint osteoarthritis.