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How Joints Work


When you stand, sit, walk, or extend any limb, you are using your joints—those connecting points that hold your skeleton together while allowing the bones to rotate or swivel.

Besides bones, joints consist of:

  • Ligaments… dense, slightly elastic fibers that form a tough sleeve around the joint, preventing it from separating
  • Cartilage… a smooth plastic-like tissue that lines the ends of bones and, along with the meniscus in the knee and the labrum in the hip and shoulder, acts as a shock absorber and cushion to prevent the bones from rubbing against each other
  • Synovium… a delicate membrane that produces a lubricant to reduce friction and wear in the joint

The knee joint

Common Causes of Joint Pain

Age, stress, injury and disease can make joints stiffen in much the same way as wear and a lack of lubrication can cause stiffness and squeaking in mechanical hinges. The most common joint problem is arthritis, which affects millions of Americans.

In patients with arthritis, the joint’s cartilage lining wears away, allowing the bones to rub against each other, resulting in friction, swelling, stiffness, pain, instability, and sometimes deformity. Severe arthritis can cause constant pain and loss of mobility that can dramatically affect the individual’s quality of life.

Joint pain can also be caused by overload or direct injury to the joint. In some cases, joint pain is made worse because a person will avoid using it, thereby weakening the muscles and making the joint even more difficult to move.

The hip joint

Joint Pain Relief

While joint pain is common, the expertise and experience offered by Dr. Harwin is not. That is why he was named Chief of Adult Reconstructive Surgery and Total Joint Replacement in the Department of Orthopaedic Surgery at Mount Sinai Beth Israel in New York.

His active involvement in clinical research ensures advanced treatment. Dr. Harwin has designed, invented, and patented several orthopaedic products and assisted in the development and improvement of devices and joint replacement implants,including the Kinemax® and Triathlon® Total Knee Prostheses and the Restoration PS®, Restoration Modular Revision®, Sentry®, Talon®, Trident® and Accolade® Total Hip Prostheses, and the Mainstay® Bone Anchor. These prostheses have been implanted in more than one million patients worldwide.

Total Hip Replacement
Total Hip Replacement

Total Knee Replacement
Total Knee Replacement

By Dr. Steven Harwin