Inter-rater Reliability of the GNRB Arthrometer

Assessing Knee Laxity and Inter-rater Reliability of the GNRB Arthrometer a Clinical Study of Patients With Anterior Cruciate Ligament Injuries Before and After Reconstruction

Although clinical examination is commonly used to diagnose an anterior cruciate ligament (ACL) injury, the method is subjective. For many years, the arthrometer KT1000 has been used to verify clinical results, mostly due to its simplicity. While the KT1000 is no longer available for purchase, other arthrometers have been introduced, one being the Genoroub (GNRB). The latter has several automatic steps, has been marketed to have a higher reproducibility, and able to detect partial tears.

While the KT1000 and GNRB have previously been compared in several studies, it's mostly been compared in healthy subjects. The current study aim to analyse the results in a clinical environment on injured objects and compare the results both before and after ACL reconstruction. The main hypothesis was that the GNRB offers high inter-rater reliability between two examinors and can replace the KT1000 in the everyday clinical setting.

Methods Consecutively, 20 patients > 18 years of age, 12 men and 8 women, with an ACL injury scheduled for surgical reconstruction, were included. All patients were screened between August 2020-2021 at the NU Hospital Group in Trollhattan, Sweden. To be eligible, the patients had to present with a first time ACL injury verified by clinical examination with or without an magnetic resonance imaging, a healthy contralateral knee and to not have sustained multi-ligament injuries to the knee. Minor collateral ligament injuries and meniscal and cartilage injuries were included.

All patients received both spoken and written information before signing an informed consent. The study was approved by the Swedish ethical committee.

All patients were examined both pre- and postoperatively, in accordance with local standard protocol, including range of motion, knee laxity measurements (manual Lachman test, pivot shift test) The participants were examined starting with the healthy/uninjured knee. Who of the two examinors started the testing was randomly decided, however alternated at the follow-up. Clinical examination and KT1000 testing were only performed by examiner 2, given the need for experience with the KT1000 for accurate results.

Statistically, a side-to-side difference (SSD) of 3 mm was set to indicate ACL injury according to general concensus. For the dichotomous values, an SSD of ≥3 mm was considered a yes to ACL injury and <3mm a no, respectively, for both the GNRB and the KT1000.

A power analysis was performed estimating a difference of 1 mm between examiners with an SD of 1 mm, resulting in 17 patients needed to reach a power of 80% with a significance level of 0.05.

As for the inter-rater reliability, the intra-correlation coefficient (ICC) was calculated and considered poor (<0.5), moderate (0.5-0.75), good (0.75-0.9) or excellent (>0.9).

Study Overview

• Status: Completed
• Conditions: Anterior Cruciate Ligament Reconstruction
• Intervention / Treatment: Diagnostic test: Knee laxity arthrometer

• Study Type: Interventional
• Enrollment (Actual): 17
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Sweden
  • Europe
    • Trollhättan, Europe, Sweden, 46185
      • NU Hospital Group

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

-

Exclusion Criteria:

Patients under 18 years of age, and those having had previous surgery to any knee, posterior cruciate ligament (PCL) injury or more severe concomitant injuries to the meniscus and collateral ligaments

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: GNRB arthrometer; Reliability testing GNRB arthrometer between two examinors	Diagnostic test: Knee laxity arthrometer; Inter-reliability analysis of the GNRB arthrometer between two examinors compared to standard KT 1000 arthrometer

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Identifying anterior knee translation in patients with anterior cruciate ligament injury before and after reconstruction compared to the contralateral non-injured knee	Measuring anterior knee translation in both injured and non injured knee before and after reconstruction using two different devices; GNRB and KT 1000 arthrometer	Primary measurement pre operative, secondary measurement 6-12 months after reconstruction

Collaborators and Investigators

• Sponsor: Vastra Gotaland Region

Study record dates

Study Major Dates

• Study Start (Actual): August 24, 2020
• Primary Completion (Actual): December 20, 2022
• Study Completion (Actual): December 20, 2022

Study Registration Dates

• First Submitted: September 15, 2025
• First Submitted That Met QC Criteria: September 22, 2025
• First Posted (Estimated): October 1, 2025

Study Record Updates

• Last Update Posted (Estimated): October 1, 2025
• Last Update Submitted That Met QC Criteria: September 22, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Keywords: Anterior cruciate ligament reconstruction, arthrometers, GNRB, KT1000, knee laxity
• Other Study ID Numbers: Dnr 2020-02062

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: As the study is a part of future thesis data will be available in this publication
• IPD Sharing Time Frame: At earliest 2027
• IPD Sharing Access Criteria: The future thesis will be available both as a printed book and in digital form
• IPD Sharing Supporting Information Type: ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No