Factors Affecting Range of Motion

Range of Motion (ROM)

Measures the distance and direction a joint can move in degrees of a circle

Factors Affecting Range of Motion

Structure of bones, ligament strength, muscle tension, soft tissue contact, hormones, and disuse.

Structure of Articulating Bones

The shape of bones determines how closely they fit together and how much movement is possible.

Hip Joint Example

The head of the femur fits into the acetabulum, allowing rotational movement.

Strength and Tension of Ligaments

Joint ligaments passively stabilize and guide the bones articulating in synovial joints by tightening or loosening in specific positions to protect joints from excessive motion

Anterior Cruciate Ligament (ACL)

Taut when the knee is straightened and helps stabilize the knee.

Posterior Cruciate Ligament (PCL)

Loose when the knee is straightened and taut when the knee is bent.

Arrangement and Tension of Muscles

Muscle tension helps stabilize joints and can restrict movement.

Hamstring Muscles

Limit hip flexion when the knee is extended.

Contact of Soft Parts

Movement may be limited when soft tissues press against one another as natural physical barriers

Soft Parts: Example

Elbow flexion stops when the forearm contacts the biceps brachii.

Hormones

A factor that can affect joint flexibility.

Relaxin

A hormone produced by the placenta and ovaries that increases joint flexibility during pregnancy to aid childbirth by expanding the pelvic outlet

Relaxin: Pubic Symphysis

Increases flexibility of the fibrocartilage.

Relaxin: Pelvic Ligaments

Loosens ligaments between the sacrum, hip bones, and coccyx.

Disuse

Lack of joint movement for an extended period that would decreases joint flexibility and range of motion.

Disuse: Synovial Fluid

Decreases synovial fluid production that can result in stiffness, pain, and restricted movement

Disuse: Ligaments and Tendons

Reduces flexibility to rapidly lose their structural integrity and strength

Muscular Atrophy

A decrease in muscle size due to lack of use.