Why does arthritis wear out only one side of the knee?

The inner side carries more load

Even in a straight leg, more of the body weight passes through the inner (medial) compartment than the outer one during walking. In someone who is even slightly bow-legged, this imbalance increases. Over years, the cartilage on the inner side thins first, which makes the leg more bowed, which loads the inner side even more. This cycle explains why inner-side arthritis is the most common pattern.

Other common causes

• Loss of the meniscus, either from a tear or from surgery that removed part of it
• A meniscus root tear, which stops the meniscus spreading load and can lead to rapid wear
• A previous fracture into the joint surface
• Knock knees, which load the outer compartment instead
• Spontaneous bone stress injuries under the cartilage, more common in older women
• Previous surgery or injury that changed the knee's alignment

Why the cause matters

Understanding the cause guides treatment. When arthritis is truly confined to one compartment and the ligaments are intact, the knee may suit a partial replacement, which resurfaces only the worn side. In younger, active patients with a bowed leg and preserved cartilage elsewhere, a high tibial osteotomy can shift the load to the healthier side instead. A recent root tear caught early may be repairable.

Slowing one-sided wear

Weight management reduces the load on the overloaded side, and strong thigh and hip muscles improve control. An unloader brace helps some patients. Cushioned footwear can make walking more comfortable. These measures do not reverse the wear but can reduce pain and may slow the process.

Assessment in Doha

At Aman Hospital, Dr. Gelber looks at your alignment standing and walking, checks the ligaments and reviews standing and, when needed, long-leg X-rays. This shows which compartment is affected, why, and which treatment options are realistic.