1. Presented by Dymond Unutoa
Altered Movement Patterns During a Sit-to-Stand Task Following Total Knee Arthroplasty
Presented by Dymond Unutoa

2. OBJECTIVES Understand Background of Study Understand Purpose of Study
Know 2 Hypotheses established for Study
Know qualifications of Subjects in Study
Understand various Methods of Study
Understand Study Results and their Discussion
Understand Conclusion of Study

3. Background of STS Study
The joint most commonly affected by osteoarthritis (OA) is the knee1
TKA is often performed to relieve pain of end-stage knee OA following a failure in non-surgical management1
Functional tests to analyze TKA are often Timed “Up & Go” (TUG) test, the Stair- Climbing Test (SCT), and the 6-Minute Walk Test (6MWT)1

4. STS Study Background cont.
Quadriceps femoris muscleweakness, post TKA, reported to persist for 1 year and up to 3 years1
At 3 months following TKA, quadriceps femoris muscle correlated with functional performance and walking symmetry and STS movement1,2

5. Purpose of Study
Analysis of the Sit-to-Stand (STS) task showed side to side differences in subjects with TKA vs control subjects
Investigate changes in STS task performance at 3 months and 1 year following TKA in comparison to control subjects who were healthy

6. Hypotheses (2)
1) If subjects 3 months post TKA self- selected their starting position for STS task, there would be asymmetries in the motions and moments of the hips and knees relative to healthy control subjects
2) Quadriceps femoris muscle strength and function would show improvements 1 year after TKA and that strength, function, and movement patterns would be more similar to control group

7. Subject Criteria and Information
14 subjects with unilateral TKA (6 women/8 men) chosen for study
Subjects chosen from selected group of orthopedic surgeons
All surgeons performed tricompartmental, cemented TKA w/ a medial parapatellar surgical approach, with proximal incision extending into quadriceps tendon

8. Control group
12 subjects without injury (5 women and 7 men) were matched by age (±5years), height (±5%), and BMI (±5%) matched to TKA subjects
Control group designated specific side of leg, for comparison, to match TKA subject’s involved limb
No MS impairments that limit function to low back, knee or ankle
No pain (verbal scale) greater than 4/10 in low back, knee or ankle

9. Methods of Study Motion Analysis1,2 EMG
Quadriceps Muscle Strength Measurement
Functional Testing
Data Analysis

10. Methods-Motion Analysis
Subjects sat on armless, backless chair, with chair height set to knee joint line1,2,4,5
Analysis by 3-dimensional, 6 camera motion analysis system (Vicon Peak)1,2,3
2 forceplates positioned in floor to capture ground reaction forces of each leg during STS task1,4
Retroreflective markers placed bilaterally on LEs and 1 on sacrum to track movement1,2,3

11. Ground Reaction Force Plates and Retroreflective Markers

12. Methods-EMG (Electromyographic) Activity1
Electrodes placed over vastus lateralis and biceps femoris muscle bellies
Subjects recorded resting and max (MVIC- max volitional isometric contraction) signal recordings for baseline values
Data collected during STS task analyzed for peak level of muscle activation2,

13. Method-Quadricep Muscle Strength Measurement1
MVIC assessed isometrically
Subjects tested while seated in electromechanical dynamometer with knee flexed to 75° degrees
Max of 3 MVIC trials performed on each leg with highest score/force used for analysis
Uninvolved limb tested before involved

14. Electromechanical Dynamometer used to assess Quadricep MVIC

15. Methods-Functional Testing1
TUG Test: Subject measured in time to rise from 46cm chair, walk 3 meters, turn around, and return to sitting in same chair
SCT: Subject measured in time to ascend and descent a flight of twelve 7” high steps (use of one handrail permitted)
6MWT: Subject measured in distance walked in 6 minutes (self-paced)

16. Functional Tests

17. Methods - Data Analysis
Joint angles, joint moments, vertical ground reaction forces, and peak magnitudes of muscle activity analyzed – ANOVA (Analysis of Variance) used1,2
2 repeated measures comparing TKA subjects at 3 months and 1 year post surgery and involved vs uninvolved limbs1

18. Results
No differences in hip flexion angle for subjects 3 months and 1 year following TKA, but numbers (hip flexion angle) were significantly higher than control group at 3 months and 1 year.1
Extensor moment values correlated with STS movement time. An increase in speed equaled an increase in action moment1,5
Peak knee flexion angle did not change over time for both TKA and control group1,2
At 1 year, velocity of knee extension in STS still remained slower in subjects with peak magnitude lower than control group1,2

19. Results cont’d
Ground reaction forces did show a difference in side to side comparison with subjects at 3 months but increased to no differences by 1 year1,3
SCT had the only significant difference in results from 3 months to 1 year as 6MWT and TUG showed no differences – At 1 year, however, SCT showed no significant difference with control group1

20. Results cont’d
Peak Vastus Lateralis EMG activity: Involved limb values were lower than uninvolved at 3 months and showed no difference at 1 year.
Peak Biceps Femoris EMG activity: Involved limb values were lower than uninvolved at months and showed no difference at 1 year, However, values showed a decrease in the uninvolved side at 1 year vs. only gain from involved limb

21. Discussion
Hypothesis 1 concerning asymmetries in motion and moments of hips and knees partially supported by results (3 months vs. 1 year)
TKA subjects showed improvement in quadriceps femoris strength, movement patterns, and performance on functional tests from 3 months to 1 year
However, TKA subjects did NOT demonstrate a similar STS movement pattern similar to control group.1,2,5

22. Discussion cont’d
TKA subjects showed a reliance on hip extensor muscles at 3 months and became more pronounced over time1,5
At 1 year after TKA, quad strength, vertical ground forces, knee moments and EMG data normalized but HIP moments increased further (which continued reduced demand on knee extensors although weight bearing and strength were normalized)1

23. Discussion cont’d
Limitations: Subjects were allowed to choose their own starting position which, with only 14 subjects, may highly correlate with varied results in joint angles, asymmetries and motion moments1
Limitations: Subjects weren’t perfectly matched to control group2
An efficient STS Task generally can be generated in 2 to 3 seconds – not too fast for fatigue and slow enough to reduce peak joint moments1,5

24. Conclusion
At 3 months post TKA, subjects had quadriceps femoris muscle weakness likely contributing to STS task compensatory movements1,2
At 1 year, subjects’ impairments resolved but abnormal movement strategies still present with increased hip flexion and larger hip extensor moments1,2
Therefore, resolution of impairments does NOT correlate with resolution of compensatory patterns – Retraining will likely be a necessity to correct compensation1,4

25. Conclusion Cont’d Limitation: Activity level of subjects4
Abnormal movement patterns established from TKA may NOT resolve without retraining1,2,4,5
These abnormal movement patterns may be a potential contributor to OA development in surrounding joints1
Subjects may need proper rehabilitation to ensure correct force production is initiated for STS task1,2,3,5

26. References
1 Farquhar S, Reisman D, Snyder-Mackler L. Persistence of altered movement patterns during a sit-to-stand task 1 year following unilateral total knee arthroplasty. Physical Therapy [ISSN ]. May 2008;88(5):
2 Boonstra M, Schwering P, Malefijt M, Verdonschot N. Sit- to-stand movement as a performance-based measure for patients with total knee arthroplasty. Physical Therapy [ISSN ]. February 2010;90(2):
3 Fotoohabadi M, Tully E, Galea M. Kinematics of rising from a chair: image-based analysis of the sagittal hip- spine movement pattern in elderly people who are healthy. Physical Therapy [ISSN ]. April 2010;90(4):

27. References cont’d
4 Piva S, Gil A, Almeida G, DiGioia A, Levison T, Fitzgerald G. A balance exercise program appears to improve function for patients with total knee arthroplasty: a randomized clinical trial. Physical Therapy [ISSN ]. June 2010;90(6):
5 Yoshioka S, Nagano A, Hay D, Fukashiro S. Biomechanical analysis of the relation between movement time and joint moment development during a sit-to-stand task. Biomedical Engineering Online [serial online]. October 22, 2009;8:27.