Hop and Step tests: new functional tests for THA evaluation PA Vendittoli, MD, V Godbout , MD *, M Lavigne , MD, N Duval , MD

Introduction Assessment of clinical outcome post THA *questionnaires SF-36, WOMAC, Harris Hip Score *external observer tests step up and go, gait analysis

Introduction Time consuming Validity, Reliability Md and Patient Validity, Reliability Not well established for majority Lack of Precision between patients with excellent results Maybe not suitable to evaluate the young and more demanding patients with THA Not all specific to Hip Voir résultats de l’étude randomisée PTH vs resurfacing: Tous les tests idem pour les deux groupes sauf hop et step

Goals 1) Describe 2 new functional tests for post-op evaluation of patient with THA 2) Correlate results with other outcome measures 3) Determine results of “step” and “hop” tests in different group of pts 4) Validate a subjective scale (with a motion lab) for in office use

Material and Methods 1- Describe the hop and step tests performances of a group of patient with well functioning THA N 91 Avg age 54,2 y Sex 47 M (51,6 %) 44 W (48,4 %) Avg f/up 5,6 y Approach 82 antero-lateral 9 posterior Component 49 M-P 28 mm 42 alumina 32 mm Hybrid Yes

Hop Test Modified single-leg vertical hop test (Gobbi A, 2003) Pre-Op Hop Test Modified single-leg vertical hop test (Gobbi A, 2003) Hop on one foot with no assistance Requirements : dynamic balance, hip flexors and abductors strength, confidence External observer and patient rates using subjective scale : Very easy Easy Difficult Impossible Post-Op Original test description: Dr David Young, Australia

Pre-Op Step Test Climb and get down a two step height using one leg with no assistance Requirements : dynamic balance, hip flexors and abductors strength, hip range of motion, confidence External observer and patient rates : Very easy Easy Difficult Impossible Post-Op Original test description: Dr David Young, Australia

Material and Methods Hybrid THA N = 91 2- Correlate the hop and step tests performances with other outcome measures SF-36 WOMAC MAP Bearing surfaces Hip reconstruction Other patients data Hybrid THA N = 91

Results : Hop Test in Hybride THA Significant correlation with : SF-36 P < 0,0001 WOMAC P < 0,0003 MAP P < 0,0008 % 56,2 % 43,8 %

Results : Step Test in Hybride THA Significant correlation with : SF-36 P < 0,0001 WOMAC P < 0,02 MAP P < 0,0008 % 49,4 % 50,6 %

Results Graph Hop Test vs Womac P = 0,008 P = 0,004

Results Graph Step Test vs Womac P = 0,012 P = 0,043

Results Correlation Hop vs Step = 0,804 (0,01 **) SF-36, WOMAC, MAP No Correlation Offset MA bearing type age sex

Material and Methods 3- Compare hop and step tests performances between different groups of patients MoM Resurfacing N = 36 Post Hybrid THA N = 91 Ant-lat MoM Uncemented THA N = 38 Post Control group Randomized study

Material and Methods 54,2 yo 51,3 yo 48,9 yo 47 M (51,6%) 44 W (48,4%) MoM Uncemented THA N = 38 Post MoM Resurfacing N = 36 Post Hybrid THA N = 91 Ant-lat 54,2 yo 51,3 yo 48,9 yo 47 M (51,6%) 44 W (48,4%) 22 M (57,4%) 16 W (42,6%) 24 M (68,5) 12 W (29,6) 66 6 87,3 89,7 93,2 17,3 16,2 11,8 16,0 16,9 17,4 Age Sex Fu in Mo SF-36 WOMAC MAP Hop and Step

Results hop test Mann-whitney P < 0,023 MoM vs R P < 0,001 H vs Mom +R Resurf + MoM = 6 mois results at 1 yr even better

Results step test

How explain these differences …

Discussion Type of reconstruction has an effect on functional tests performance

Discussion: Bias Factors hybrid MoM THA RSA Offset (mm) difference operated vs non-operated + 3,2 + 6 - 4,9 Resurfacing are less anatomic Comparison of offset in Birmingham hip resurfacing and hybrid total hip arthroplasty J. M. Loughead, D. Chesney, J. P. Holland, A. W. McCaskie Journal of Bone and Joint Surgery - British Volume,2005 Vol 87-B, Issue 2, 163-166 Better offset reconstruction gives better abductor strength Total hip arthroplasty: the relationship between posterolateral reconstruction, abductor muscle strength, and femoral offset. Yamaguchi T, Naito M, Asayama I, Ishiko T. J Orthop Surg (Hong Kong). 2004 Dec;12(2):164-7

Discussion: Bias Factors Head Size Discussion: Bias Factors Negative pressure Bearing type Komistek RD , JBJS am 2002 , Hip separation MM vs MP With fluoro MP 2 mm (avg) en swing phase vs MM = no Hybrid MoM SRA But no difference between MP and Alumina in hop and step test Alumina negative pressure as MoM

Discussion: Bias Factors hybrid MoM THA RSA Surgical approach Antero-lateral Posterior Femoral stem cemented Non-cemented No stem Weight transfer more physiologic in RSA

Discussion: Bias Factors Is the femoral stem the problem ? New study in fall : same bearing surface and head size with different stem In gait lab

Discussion The Hop and Step tests are simple Correlate well with other established function scores WOMAC, SF-35, MAP More specific, differences not explain, gives more information on patients function

Conclusion Hop and step tests might be useful and sensitive clinical tests to quickly and easily determine the functional status of the patient in clinical setting Further evaluation in motion laboratory will be done to determine validity, reliability and precision of these tests and better understand variables explaining the differences found

4) Validate a subjective scale (with a motion lab) Resurf vs MoM in gait lab Objective and Validation of questionnaire Correlations with other factors

Acknowledgments Daniel Lusignan, research nurse Lucie Grondin, physiotherapist David Young MD