022: What Are Mobilisations?

manual therapy mobilisation mobility Aug 30, 2021

'Mobilisation' refers to the application of force to move the articular surfaces inside a joint. Therapists perform this technique to improve the joint's mobility, flexibility, or reduce pain associated with joint structures by passively or manually influencing the accessory motions of the joint (Manske, 2016).

Understand that the terms 'joint mobility and 'joint flexibility' are used here according to how they are most often used in the scientific literature. 'Joint mobility' refers to the internal motion of one articular surface relative to the other inside the joint capsule; hence, methods designed to improve the joint surface relationship are called 'mobilisations.' Other names for these motions include 'arthrokinematics' and 'accessory motions.'

'Joint flexibility' refers to the range of motion available at a joint or series of joints. That includes all types of range of motion: static and dynamic, active and passive. Contrary to recent popular opinion within the health and fitness industry, flexibility is not limited to only passive range of motion - this was a myth perpetuated by certain training providers for unknown reasons (perhaps because of a lack of understanding of the literature, or to create a sense of superiority around their methods).

Successful application of mobilisations requires awareness of four important concepts:

1) How accessory motions work to form the mobilisation exercise (Riddle, 1992).

2) Convex-concave rule (Neumann, 2012).

3) Close- and loose-packed joint positions (Singh, 2014).

4) Grades for performing the mobilisation exercise (Kisner & Colby, 2012).

Types of Joint Play Movements

'Joint play' is another term that refers to the internal, accessory motions within the joint. Depending upon the source, there can be up to five types of joint play motions during mobilisations. The first type is the 'roll .' A new point on one of the two joint bone surfaces contacts new points on the other bone surface. The second type is the 'glide,' whereby the same point on one of the two joint bone surfaces contacts new points on the other bone surface. The third type is traction. There is a vertical linear separation of the joint surfaces away from the treatment plane; this occurs during mobilisation but not regular movements. The fourth type is compression, which is the opposite of traction: a vertical linear approximation of the joint surface toward the treatment plane. While compression occurs during regular movements, in the context of this blog post, 'compression' will refer to the manual therapy technique described here. Finally, the fifth type is the 'glide,' in which one joint surface rotates around a stationary axis in either a clockwise or counterclockwise direction.

Convex-Concave Rule

The convex-concave rule was first described by the Irish anatomist Michael A. MacConaill (1902-1987), a pioneer in the fields of biomechanics and kinesiology (Prendergast & Lee, 2006). A simplified explanation of the rule is as follows:

If a convex joint surface moves on a stationary concave surface, the convex joint will slide in the direction opposite to that of the angular motion of the bone; if a concave joint surface moves on a stationary convex surface, the articular surface will slide in the same direction as the angular motion of the bone.

For example, when the distal radioulnar (wrist) joint supinates, the radius (concave surface) moves on the ulna (convex surface). To do a successful mobilisation of the joint to increase supination range of motion, the mobilising force applied by the therapist should be in a posterior direction (the same direction).

Close- and Loose-Packed Positions

Every joint has two common positions: 1) the close-packed position, in which the capsular ligaments are taught and there is maximum surface contact between the articulating surfaces of the two bones that make up the joint; and 2) the loose-packed position, in which the capsular ligaments are loose and there is minimal contact between the articulating surfaces. The close-packed position offers maximum stability and the loose-packed position provides maximum mobility within the joint. Therapists should perform mobilisations in the loose-packed position, given that greater motion can be achieved compared to the close-packed position.

Grades of Mobilisation Exercises

Different schools of training have their own rules for grading mobilisations. However, all grades depend on several biomechanical factors, including the velocity of movement, amount of motion, and the number of oscillations per minute. Mobilisations generally have five grades:

I: Low-speed, low oscillations, small amount of motion.

II: Low-speed, low oscillations, large amount of motion.

III: Low-speed, low oscillations, large amount of motion.

IV: Low-speed, low oscillations, small amount of motion.

V: High-speed, high oscillations, small amount of motion.

Grade I is performed only at the beginning of the available range of motion to decrease pain. Grade II is performed near the middle of the available range of motion; again, it is mainly used to reduce pain levels. Grade III is performed near the end of the available ROM to increase flexibility. Grade IV is performed at the end of the available ROM, again to increase flexibility. Finally, grade V is a specialised category of mobilisation exercises called 'manipulations,' which are performed beyond the end of the available range of motion; think of grade V as ballistic stretching for the joint surfaces.

Limitations

It is essential to keep in mind that while mobilisations can be considered a flexibility training technique, in most territories, they can only be performed by fully qualified and licensed healthcare professionals (physiotherapists, osteopaths, chiropractors, sports therapists, etc.). Furthermore, due to the required positions and leverage, it is generally impossible to perform hands-on mobilisations to one's own oints. However, it is possible can apply some techniques with certain pieces of equipment, such as using a therapy band wrapped around the foot and ankle to apply traction to the hip joint.

References

Manske, R. C. (2016) Fundamental Orthopaedic Management for the Physical Therapist Assistant (4th ed.). St. Louis, MI: Mosby/Elsevier.

Riddle, D. L. (1992) Measurement of Accessory Motion: Critical Issues and Related Concepts. Physical Therapy vol. 72, no. 12, pp. 865-874.

Neumann, D. A. (2012) The Convex-Concave Rule of Arthrokinematics: Flawed or Perhaps Just Misinterpreted? Journal of Orthopaedic and Sports Physical Therapy vol. 42, no. 2, pp. 53-55.

Singh, V. (2014) General Anatomy. Cambridge, MA: Elsevier Health Sciences.

Kisner, C. & Colby, L. (2012) Peripheral Joint Mobilisation/Manipulation. In: Therapeutic Exercise Foundations and Techniques (6th ed.). Philadelphia, PA: F. A. Davis Company.

Prendergast, P. J. & Lee, T. C. (2006) Walking on Water. Irish Journal of Medical Science vol. 175, no. 3, pp. 69-75.