Calcium, Vitamin D, & Your New Knee

Published: 15:34 pm, Mon March 22, 2021

Q&A with Dr. Gary Zartman

Dr. Zartman,

 I am considering a total knee replacement and have osteoporosis (low calcium in my bones). Can Calcium and Vitamin D help my new knee last longer?


Yes. That is a very good question! First, a little biology and background info:

Osteoporosis is a condition in which our bones lack calcium. Calcium makes up the hard and rigid parts of the bone that give them strength. Without enough calcium our bones become weak and break more easily. In addition, weak bones cannot support the metal components of a total knee replacement and can lead to collapse of the bone, leading to pain and swelling.

Osteoporosis affects not only many women over the age of menopause, but also younger women whose ovaries were removed during a hysterectomy or due to ovarian cancer. It also affects both men and women taking certain drugs that can cause poor calcium stores in the bones – such as corticosteroids, certain chemotherapy drugs, and Dilantin for seizure prevention

Calcium is necessary to allow our cells to function properly. The body normally obtains calcium from the foods we eat and uses Vitamin D to absorb that calcium from the small intestine. A lack of Vitamin D (Vitamin D deficiency) prevents our bodies from absorbing enough calcium for everyday use and the body then has to rob the bones of their calcium to supply the rest of the body’s needs. Over time, this leads to Osteoporosis.

A recent study published in The Journal of Arthroplasty looked at the risk of failure of total knee replacements requiring surgery and Calcium and Vitamin D use. The authors studied the medical records of 142,127 patients who had received a total knee replacement between 2009 and 2018. Those patients were then followed to determine if their knee replacement failed and required knee revision surgery. The results showed that the patients who took both calcium and Vitamin D for greater than a year had a 56% lower risk of revision knee surgery. The average age of the patients was 68.8 years – quite typical for patients needing hip or knee replacement.

When we perform hip or knee replacement surgery both the surgeon and the patient hope that no further surgery will be needed and the new joint will last the remainder of the patient’s lifetime. In most cases that is true. Joint replacements fail at a rate of approximately 1% per year, so in 20 years about 80% are still working. Unfortunately, this also means that 20% have failed. Knee replacements primarily fail due to either infection or what we call “loosening”. Loosening means the cement bond between the metal components of the knee replacement and the underlying bone breaks up and the pieces can shift and move. This causes pain, swelling, and a feeling of instability. Some patients notice a “giving way” feeling or a change in the alignment of their leg.

Calcium plays a role in maintaining bone strength and a lack of calcium can cause the bone to fail. In addition, Vitamin D not only helps our bodies absorb calcium, but plays many roles in maintaining our body’s immune function. Vitamin D deficiency is associated with a number of acute and chronic illnesses and is a risk factor for total joint replacement infections.

So, to answer your question – yes!

This study does show that calcium and Vitamin D supplements are associated with a greater than 50% chance of your knee replacement lasting longer and giving you more years of enjoyment. It is especially important for you to take calcium and Vitamin D supplements if you have been diagnosed with Osteoporosis or Vitamin D deficiency.

It is important to take the correct amount of calcium and Vitamin D. Doses of calcium less than 100 mg. (milligrams) daily and Vitamin D of less than 400IU daily are not recommended for the prevention of fractures due to osteoporosis, as these low doses do not seem to have an effect of fracture occurrence. The current recommendations are to take 1200 mg. of calcium and 800IU of Vit. D. It is important to take the calcium as 600mg twice daily, as the body has a hard time absorbing 1200mg all in one dose. Both calcium and Vitamin D are available without a prescription and are fairly safe at these doses. Always check with your primary care doctor before starting a new medication.

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