Range of Motion Study
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The document presents a hypothesis that the range of motion (ROM) of synovial joints can be predicted by subtracting the concave arc from the convex arc of the articular surfaces. The authors tested this hypothesis on 21 joints from cadavers by measuring the actual ROM and comparing it to the predicted ROM calculated from the articular surface dimensions. They found a moderate correlation of r=0.77 between the measured and predicted ROM, supporting the hypothesis with some limitations.
Range of Motion Study
- 1. STRUCTURE-BASED PREDICTION OF JOINT MOTION P.V. Loubert 1 , T.J. Masterson 2 , A. Saltarelli 2 1 School of Rehabilitation and Medical Sciences 2 School of Health Sciences Central Michigan University, Mt. Pleasant, MI 48859
- 2. INTRODUCTION
- 3. INTRODUCTION Our hypothesis states that for any given synovial joint, the range of motion (ROM) can be predicted by subtracting the concave arc from the convex arc of the respective articular surfaces in a joint (see Figure 1) . Convex Arc Concave Arc Convex Arc â Concave Arc = ROM
- 4. Figure 1. ROM - Arc Relationship. Convex Arc - Concave Arc = Predicted ROM 180 deg. - 60 deg. = 120 deg.
- 5. INTRODUCTION Cont. This hypothesis is based on two assumptions: (1) The entire dimension of an articular surface is utilized in some part of the ROM, and (2) There is no part of the ROM where there would not be contact between articular surfaces. Violations of these assumptions will require consideration of additional variables in the application of our hypothesis.
- 6. METHODS We used the procedure developed by Lee et. al. (1998) to test our hypothesis. 1. Restraining soft tissues were removed or released for the cadaver specimens. 2. Passive ROM was measured using a standard clinical gonimeter on each specimen and recorded. 3. Twenty-one joints were transected in the same plane as the measured ROM using a band saw. Joints studied include: - 5 glenohumoral joints - 5 ulnohumoral joints - 3 radiohumoral joints - 4 knee joints - 2 radioulnar joints - 1 ankle joint - 1 proximal interphalangeal joint.
- 7. Figure 2. Determining center of curvature.
- 8. Figure 3. Measuring predicted ROM.
- 9. CALCULATIONS Rom was predicted by subtracting the concave arc from the convex arc. Correlations were calculated between the: a. Predicted ROM and measured ROM b. Predicted ROM and published ROM (Rothstein et. al., 1998)
- 10. RESULTS 5.70 80.30 157.40 86.00 110.00 3 rd PIP Sagittal 6.00 Difference 52 Predicted ROM 77.40 Convex ARC 46.00 Measured ROM 50.00 Published ROM Talocural Sagittal Joint Section
- 11. RESULTS
- 12. DISCUSSION WHAT DOES IT ALL MEAN? Our results indicate that there is a moderate correlation, r = 0.77, between the measured and predicted ROM, as well as between the published and predicted ROM, r = 0.77. Several kinematic relationships were observed between articular surfaces during movement that suggest additional considerations that must be taken into account in order to achieve a higher correlation between joint structure and function. These included: 1) Violations of the assumption that the articular surfaces would be in contact during the entire movement, and 2) The transection of the joint must be in the true plane of movement.
- 13. CHANGES IN GEOMETRIC AXES OF ROTATION A B A + B = ROM
- 14. CONCLUSION WHY STUDY ARTHROKINEMATICS? The relationship tested in this study may be used by: 1)Paleontologists to refine predictions of functional motion in fossil primates as well as other organisms, and 2) Practicing medical clinicians who treat joint dysfunction and help in the design and fabrication of prosthetic devices for humans
- 15. REFERENCES Lee KJ, RJ Kranich, PV Loubert: Qualitative Analysis of the Convex-Concave Rule as it Applies to the Glenohumeral Joint. Phys Ther 78:S65 1998. Loubert PV: The Theoretical Foundations for Joint Mobilization. Physical Therapy â98 Course Materials: A Compendium of Conference Handouts , American Physical Therapy Association, pp354-359 1998. Rothstein JM, SH ROY, SL Wolf: The Rehabilitation Specialistâs Handbook, Second Edition . F.A. Davis, Philadelphia, 1998. Paint Shop Pro 7.0, JASC Software ( www.jasc.com ). Scion Image (beta 4.02), Scion Corporation ( www.scioncorp.com ).
- 16. THANKS Dr. Loubert, Dr. Masterson
Editor's Notes
- #4: Explain concave/ convex
- #5: Rolling and translational gliding in opposite directions combine to a result of no net linear displacement. However the angular component of the rolling remains to produce some net angular displacement. The end result (but not the process) are equivalent to tangential glide as a component of true angular motion.