Which joints are intended to produce movement primarily in one plane and are prone to stability limitations?

• A. Ball-And-Socket Joints
• B. Synarthrotic Joints
• C. Stable Joints
• D. Hinge Joints

Answer: (C)

Joints that move mainly in one plane are uniaxial, meaning their motion is restricted to a single axis. The hinge joint is the classic example, allowing mainly flexion and extension as you see in the elbow or knee. Because the movement is confined to that one plane, stability depends a lot on how well the bones align and on the surrounding ligaments; if those supporting structures are lax or damaged, the joint is more prone to instability in that plane. Ball-and-socket joints, by contrast, move in multiple planes and axes, so they aren’t described as uniaxial. Synarthrotic joints don’t produce movement at all, so they don’t fit the idea of a joint designed for movement. The term “stable joints” isn’t a standard joint category and doesn’t capture the uniaxial movement pattern. So the joints described by this pattern are hinge-type joints.