Skip to main content

Validity of GNRB® arthrometer compared to Telos™ in the assessment of partial anterior cruciate ligament tears



The main goal of this study was to compare the results of the GNRB® arthrometer to those of Telos™ in the diagnosis of partial thickness tears of the anterior cruciate ligament (ACL).


A prospective study performed January–December 2011 included all patients presenting with a partial or full-thickness ACL tears without ACL reconstruction and with a healthy contralateral knee. Anterior laxity was measured in all patients by the Telos™ and GNRB® devices. This series included 139 patients, mean age 30.7 ± 9.3 years. Arthroscopic reconstruction was performed in 109 patients, 97 for complete tears and 12 single bundle reconstructions for partial thickness tears. Conservative treatment was proposed in 30 patients with a partial thickness tear. The correlation between the two devices was evaluated by the Spearman coefficient. The optimal laxity thresholds were determined with ROC curves, and the diagnostic value of the tests was assessed by the area under the curve (AUC).


The differential laxities of full and partial thickness tears were significantly different with the two tests. The correlation between the results of laxity measurement with the two devices was fair, with the strongest correlation between Telos™ 250 N and GNRB® 250 N (r = 0.46, p = 0.00001). Evaluation of the AUC showed that the informative value of all tests was fair with the best results with the GNRB® 250 N: AUC = 0.89 [95 % CI 0.83–0.94]. The optimal differential laxity threshold with the GNRB® 250 N was 2.5 mm (Se = 84 %, Sp = 81 %).


The diagnostic value of GNRB® was better than Telos™ for ACL partial thickness tears.

Level of evidence

Diagnostic study, Level II.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2


  1. Ahldén M, Hoshino Y, Samuelsson K et al (2012) Dynamic knee laxity measurement devices. Knee Surg Sports Traumatol Arthrosc 20:621–632

    PubMed  Article  Google Scholar 

  2. Bach BR, Warren RF, Flynn WM et al (1990) Arthrometric evaluation of knees that have a torn anterior cruciate ligament. J Bone Joint Surg Am 72:1299–1306

    PubMed  Google Scholar 

  3. Bak K, Scavenius M, Hansen S et al (1997) Isolated partial rupture of the anterior cruciate ligament. Long-term follow-up of 56 cases. Knee Surg Sports Traumatol Arthrosc 5:66–71

    CAS  PubMed  Article  Google Scholar 

  4. Barrack RL, Buckley SL, Bruckner JD et al (1990) Partial versus complete acute anterior cruciate ligament tears. The results of nonoperative treatment. J Bone Joint Surg Br 72:622–624

    CAS  PubMed  Google Scholar 

  5. Beldame J, Mouchel S, Bertiaux S et al (2012) Anterior knee laxity measurement: comparison of passive stress radiographs Telos® and “Lerat”, and GNRB® arthrometer. Orthop Traumatol Surg Res 98:744–750

    CAS  PubMed  Article  Google Scholar 

  6. Berry J, Kramer K, Binkley J et al (1999) Error estimates in novice and expert raters for the KT-1000 arthrometer. J Orthop Sports Phys Ther 29:49–55

    CAS  PubMed  Article  Google Scholar 

  7. Branch TP, Mayr HO, Browne JE et al (2010) Instrumented examination of anterior cruciate ligament injuries: minimizing flaws of the manual clinical examination. Arthroscopy 26:997–1004

    PubMed  Article  Google Scholar 

  8. Buckley SL, Barrack RL, Alexander AH (1989) The natural history of conservatively treated partial anterior cruciate ligament tears. Am J Sports Med 17:221–225

    CAS  PubMed  Article  Google Scholar 

  9. Collette M, Courville J, Forton M, Gagnière B (2012) Objective evaluation of anterior knee laxity; comparison of the KT-1000 and GNRB® arthrometers. Knee Surg Sports Traumatol Arthrosc. doi:10.1007/s00167-011-1869-2

    Google Scholar 

  10. Colombet P, Dejour D, Panisset JC et al (2010) Current concept of partial anterior cruciate ligament ruptures. Orthop Traumatol Surg Res 96:S109–S118

    CAS  PubMed  Article  Google Scholar 

  11. Daniel DM, Stone ML, Sachs R, Malcom L (1985) Instrumented measurements of anterior knee laxity in patients with acute anterior cruciate ligament disruption. Am J Sports Med 13:401–407

    CAS  PubMed  Article  Google Scholar 

  12. DeFranco MJ, Bach BR (2009) A comprehensive review of partial anterior cruciate ligament tears. J Bone Joint Surg Am 91:198–208

    PubMed  Article  Google Scholar 

  13. Ganko A, Engebretsen L, Ozer H (2000) The rolimeter: a new arthrometer compared with the KT-1000. Knee Surg Sports Traumatol Arthrosc 8:36–39

    CAS  PubMed  Article  Google Scholar 

  14. Huber FE, Irrgang JJ, Harner C, Lephart S (1997) Intratester and intertester reliability of the KT-1000 arthrometer in the assessment of posterior laxity of the knee. Am J Sports Med 25:479–485

    CAS  PubMed  Article  Google Scholar 

  15. Jardin C, Chantelot C, Migaud H et al (1999) Low accuracy of KT-1000 versus Telos radiographic measurements to assess anterior knee laxity after ACL graft. Intra and interobserver reproducibility of KT-1000. Rev Chir Orthop Reparatrice Appar Mot 85:698–707

    CAS  PubMed  Google Scholar 

  16. Lee YS, Han SH, Jo J et al (2011) Comparison of 5 different methods for measuring stress radiographs to improve reproducibility during the evaluation of knee instability. Am J Sports Med 39:1275–1281

    PubMed  Article  Google Scholar 

  17. Margheritini F, Mancini L, Mauro CS, Mariani PP (2003) Stress radiography for quantifying posterior cruciate ligament deficiency. Arthroscopy 19:706–711

    PubMed  Article  Google Scholar 

  18. Muellner T, Bugge W, Johansen S et al (2001) Inter- and intra-tester comparison of the Rolimeter knee tester: effect of tester’s experience and the examination technique. Knee Surg Sports Traumatol Arthrosc 9:302–306

    CAS  PubMed  Article  Google Scholar 

  19. Ohsawa T, Kimura M, Kobayashi Y et al (2012) Arthroscopic evaluation of preserved ligament remnant after selective anteromedial or posterolateral bundle anterior cruciate ligament reconstruction. Arthroscopy 28:807–817

    PubMed  Article  Google Scholar 

  20. Papandreou MG, Antonogiannakis E, Karabalis C, Karliaftis K (2005) Inter-rater reliability of Rolimeter measurements between anterior cruciate ligament injured and normal contra lateral knees. Knee Surg Sports Traumatol Arthrosc 13:592–597

    PubMed  Article  Google Scholar 

  21. Pugh L, Mascarenhas R, Arneja S et al (2009) Current concepts in instrumented knee-laxity testing. Am J Sports Med 37(1):199–210

    PubMed  Article  Google Scholar 

  22. Robert H, Nouveau S, Gageot S, Gagnière B (2009) A new knee arthrometer, the GNRB: experience in ACL complete and partial tears. Orthop Traumatol Surg Res 95:171–176

    CAS  PubMed  Article  Google Scholar 

  23. Schuster AJ, McNicholas MJ, Wachtl SW et al (2004) A new mechanical testing device for measuring anteroposterior knee laxity. Am J Sports Med 32:1731–1735

    PubMed  Article  Google Scholar 

  24. Solomon DH, Simel DL, Bates DW et al (2001) The rational clinical examination. Does this patient have a torn meniscus or ligament of the knee? Value of the physical examination. JAMA 286:1610–1620

    CAS  Google Scholar 

  25. Stäubli HU, Jakob RP (1991) Anterior knee motion analysis. Measurement simultaneous radiography. Am J Sports Med 19:172–177

    PubMed  Article  Google Scholar 

  26. Swets JA (1988) Measuring the accuracy of diagnosis system. Science 240:1285–1293

    CAS  PubMed  Article  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to N. Lefevre.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Lefevre, N., Bohu, Y., Naouri, J.F. et al. Validity of GNRB® arthrometer compared to Telos™ in the assessment of partial anterior cruciate ligament tears. Knee Surg Sports Traumatol Arthrosc 22, 285–290 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • GNRB®
  • Anterior cruciate ligament
  • Knee laxity