Joint Mobility Background Without freely moveable joints, Man cannot move. If joints stiffen, as in injury or disease, disability may be the result. The mobility of a joint may be affected by intra-articular factors, e.g. the state of articular cartilage, or its lubrication by extra-articular structures, e.g. tight capsules or limited musculo-tendinous ties; by functional capacity, e.g. uncoordinated reciprocal activity of agonist and antagonist muscle groups; or by pathological condition, e.g. osteophytes or articular pain. If one is to understand the degree to which function in a joint is lacking, an accurate measure of the normal functional state of the joint is necessary. This state may be measured in at least three ways: by measuring statically the maximum limits to which the joint can be moved passively; by measuring the mid-range stiffness of the joint when moved by some external force; c) by measuring the dynamic movement range of the joint, i.e. the limits within which movement is confined during habitual activities. In this sessions attention is directed to the first of these, viz, to determining the static limits of joint movement. Clinically, it is customary to adopt the anatomical position of a joint as neutral zero, and to measure angular deviation from this position either positively or negatively. Full details of this recommended clinical method of measuring joint motion can be found in the British Orthopaedic Association’s Handbook "Joint Motion". Alternative methods, slightly more convenient for numeral handling use the normal 360° scale, with an absolute zero. Method It is important to keep a record of all measurements made on yourself and the others in your group. All measurements should be made twice and entered on the chart provided. Various methods may be used such as radiographs, photographs, flexmeter and goniometer. The methods chosen depends on resources and the need for accuracy. The universal goniometer is the most common device for measuring joint angles. Basically it is either a 3600 or 1800 protractor with one axis which joins two arms. One arm is stationary and the other movable around the axis. In general this is a reliable instrument when used correctly. Ensure that the joint to be measured is not impeded in any way and in the anatomical position. The anatomical position is defined as the zero position. Ensure that the patient knows what to do if the measurement is active or what to expect if it is passive. Ensure that proximal joints are stabilized and prevent any substitute movements. A. Hip movements Working in groups of four, the following measurements will be made: i Rotation of the hip ii Extension of the hip i Rotation of the hip. (Fig. 1) Sit on the edge of the bench with the hip and knee flexed at 90°. Make a note of the position of the leg when it hangs vertically down. Move the leg so that the foot moves towards the midline (medial rotation), and make a note of the angular change. Repeat in the opposite direction (lateral rotation). Extension of the hip (Fig. 2) With the subject in the prone position align the goniometer along the lateral midline with the fulcrum over the greater trochanter. The lateral epicondyle of the femur is a useful landmark. All measurements must be taken passively. Ankle movements. Flexion and extension of the ankle. The position of reference is achieved when the sole of the foot is perpendicular to the axis of the leg. a) Extension (Diagram 5 and 6) Ask the subject to stand on tip toe and measure the distance from ground to heel. Flexion (Diagram 5 and 6) The vertebral column Sit and reach box Grip strength Ensure that the meter is held comfortably in the right hand. The meter can be adjusted. With the arm at the side squeeze the grip as hard as possible. Repeat using left hand. Measure the circumference of the forearm just below the elbow skin crease. Questionnaire Using your own results and those from other groups discuss the following: Describe instruments used for each measurement and comment on the methods used to determine the joint mobility measures. How reproducible were the measurements? (See reliability coefficients.) 2. Display results. Discuss the range of movements between subjects. Are there any sex differences in the range of joint movement? Hip movements. Rotation. Do any of your group habitually sit on the floor with legs crossed? If so, compare his/her rotational movements with the others. Are they greater? Extension. What is affecting the range of movement? Ankle. Ankle. At the extremes of the movement the ankle joint may not be the only active joint. Which other joints may contribute to the range of movement? 7. Vertebral Column. Discuss the variations in the flexibility of the subjects. Do leisure/sporting activities affect the extent of movement? Is flexibility of the vertebral column important to the ‘quality of your life’? 8. Draw a graph of grip strength against forearm circumference separating the males form the females. What conclusions can be drawn? General Conclusions Using the data collected from the volunteers and the questionnaire draw conclusions concerning the variability of the joint mobility of the class and the reasons behind them. Consider any anatomical considerations as to why there is variability between individuals.