Infection after knee replacement surgery is rare. This statement means little however if you end up dealing with a periprosthetic joint infection (PJI), one of the most serious and dreaded complications of knee replacement surgery.
The overall early deep infection rate for patients undergoing a primary knee replacement is 0.39%, while revision knee replacement infection rates are 0.97%.
In the first 2 years after surgery, the chance of developing an infection is estimated at 1.5%. After 2 years, the chance of infection goes down to about 0.5%.
While these numbers are exceedingly small, they are not zero, and they are only generalized statistics. YOUR individual infection risk may be much higher so read on to find out how to lower your personal risk for one of the worst possible outcomes of knee replacement surgery.
Factors That Influence YOUR Personal Risk of Infection
Hospitals with high volumes of knee replacement surgeries have lower infection rates than small community hospitals, so pick your hospital accordingly.
Each surgeon will have his own rates of infection as well as overall complication rates which he’ll, no doubt, be happy to share with you if they are lower than national averages.
Hanging out in healthcare facilities after your surgery can negatively affect your chance of infection, so go home as soon as possible to your own germs.
Diabetes, obesity (those with BMI> 40), smoking, alcoholism, steroid use, and rheumatoid arthritis, are all well-known factors that predispose someone toward a higher risk of infection. Correcting these factors aren’t quick or easy.
However, I would like to address a different factor that is more amenable to change prior to surgical intervention IF you are aware of it and that is impaired nutritional status. There is a growing body of evidence that implicates malnutrition as a risk factor for infection. 
Malnutrition is defined by some researchers as a serum albumin level <3.5 g/dL, serum transferrin levels <200 mg/dL, and/or total lymphocyte count (TLC) <1,500 cells/mm3.
Malnutrition has been shown to interfere with optimal synthesis of collagen and proteoglycan, resulting in disruptions in the wound healing process that can lead to persistent wound drainage and increased risk of infection.
A recent meta-analysis indicated that an albumin level < 3.5 g/dL had an almost 2.5 fold increased risk of infection in generalized orthopedic surgeries. Researchers of the study recommended a “thorough nutritional consultation for each hospitalized patient in orthopedics.”
In another study patients with hypoalbuminemia (albumin level < 3.5 g/dL) had a higher risk for surgical site infection, pneumonia, extended length of stay, and readmission. 
Researchers recommended that “future efforts should investigate methods of correcting nutritional deficiencies prior to total joint arthroplasty. If successful, such efforts could lead to improvements in short-term outcomes for patients.” 
The Connection Between Vitamin D and Protein Status
Let’s also look at a closely related finding. Patients with post surgical infection in the hip and knee joints show significantly lower calcium and vitamin D3 levels as well as reduced protein levels (albumin and total protein) compared with primary arthroplasty and aseptic revisions.
The vitamin D status was defined as follows:
- deficiency <20 ng/mL,
- insufficiency 20–29 ng/mL
- normal: 30–100 ng/mL
It has long been established that vitamin D deficiency has been associated with joint infections.  It is also known that 99% of the body’s vitamin D exists in the protein-bound form. The vitamin D-binding protein (VDBP), which serves as the most important carrier protein for vitamin D3 and its intermediates, binds about 85%–90%, while 10%–15% are bound to albumin and other lipoproteins. Less than 1% is present as unbound components of the blood. (See Chart Above). [8-9]
So we can easily conclude that reduced protein levels impact Vitamin D delivery to the cells and that all of these markers are early warning signs that you have a higher risk of infection should you choose to move forward with knee replacement surgery.
Of course this scenario assumes that your surgeon provided you with this information and that he did a routine screen of your nutritional status pre-surgically to check for any problems so that you can make an informed decision.
Unfortunately, I’m not sure how prevalent pre-surgical nutritional screening is, but you have been forewarned and are now prepared.
It is something that you can ask your surgeon about and request. It is even possible to get your own testing done if none are being provided for you.
Common Causes of Low Serum Albumin
- Liver Congestion: The liver manufactures albumin. So albumin tests are often a part of liver-functioning checks. Many diseases can cause liver failure, including cirrhosis, liver cancer, hepatitis, alcohol-related liver disease, and fatty liver disease. Many livers are congested but don’t yet fall into a “disease” category.
- Kidney damage: Problems with the kidneys may cause them to release large amounts of protein into the urine. This can take albumin from the blood, leading to hypoalbuminemia.
- Protein losing enteropathy: Some stomach and gastrointestinal conditions, including celiac disease and inflammatory bowel disease, can cause the digestive system to lose a lot of protein. This causes a syndrome called protein losing enteropathy that can lead to low albumin levels.
- Low stomach acid: Hypochlorydria is another root cause of faulty protein mal-digestion because the enzymes that breakdown protein need an acid environment to start working in the stomach. Without that head start, protein may end up undigested in the intestines and unavailable for use by the cells.
- Malnutrition: People may develop hypoalbuminemia when they do not eat enough key nutrients, or medical conditions make it hard for their bodies to absorb nutrients. Some people who have recently undergone chemotherapy may be malnourished.
Albumin is present in many animal products. Changing your diet to include the following; beef, milk, cottage cheese, eggs, and greek yogurt, may improve albumin status.
If your diet already includes protein rich foods then the root problem could be in your ability to absorb, make or process the proteins.
Absorption: If you have a known GI condition or you suspect you have one, you may have trouble breaking down protein and absorbing it in the small intestine. It is best to work with a functional medicine practitioner before surgery to reduce your risk.
Processing: A congested liver may be causing the deficiency in albumin. A liver and gall bladder flush as described here could go a long way to improving your nutritional status.
Addressing vitamin D deficiency prior to surgery is essential as well. It is not possible for me to go into all the details but check here for an excellent article on symptoms and ways to reverse vitamin D deficiency.
Factors That Lower Infection Risk Following Knee Replacement Surgery
- Overall knee replacement infection rates are not high but YOUR risk can be higher or lower depending on many different factors.
- Hospital and MD selection are important
- Going Home as soon as possible will lower risk
- Losing weight and quitting smoking will lower risk
- Addressing your nutritional status prior to surgery and correcting for low albumin and total protein as well as addressing vitamin D deficiency specifically 25-hydroxyvitamin D or 25(OH) D (calcidiol) will also help lower your infection risk
 Yuwen, Peizhi et al. “Albumin and surgical site infection risk in orthopaedics: a meta-analysis” BMC surgery vol. 17,1 7. 16 Jan. 2017, doi:10.1186/s12893-016-0186-6.
 Bohl, Daniel et al. “ Hypoalbuminemia Independently Predicts Surgical Site Infection, Pneumonia, Length of Stay, and Readmission After Total Joint Arthroplasty” J Arthroplasty. 31(1):15-21. Jan. 2016, doi: 10.1016/j.arth.2015.08.028.
 Greene, K et al. “ Preoperative Nutritional status of total joint patients. Relationship to postoperative wound complications” Journal of Arthroplasty, 6 (4); 321-5 6 Dec. 1991.
 Kamath AF et al. “Low Albumin Is a Risk Factor for Complications after Revision Total Knee Arthroplasty” Journal of Knee Surgery 30(3):269-275. Mar. 2017, doi: 10.1055/s-0036-1584575.
 Bohl, Daniel et al. “Is Hypoalbuminemia Associated With Septic Failure and Acute Infection After Revision Total Joint Arthroplasty? A Study of 4517 Patients From the National Surgical Quality Improvement Program” The Journal of Arthroplasty, 31(5): 963 – 967.
 Ihle C, Weiß C, Blumenstock G, et al. Interview based malnutrition assessment can predict adverse events within 6 months after primary and revision arthroplasty – a prospective observational study of 351 patients. BMC Musculoskelet Disord. 19(1):83. Mar 15 2018, doi:10.1186/s12891-018-2004-z.
 Gu, Alex et al. “Preoperative Malnutrition Negatively Correlates With Postoperative Wound Complications and Infection After Total Joint Arthroplasty: A Systematic Review and Meta-Analysis” The Journal of Arthroplasty, 0 (0) Jan 9, 2019, doi.org/10.1016/j.arth.2019.01.005.
 Zajonz, Dirk et al. “The significance of the vitamin D metabolism in the development of periprosthetic infections after THA and TKA: a prospective matched-pair analysis of 240 patients” Clinical interventions in aging vol. 13 1429-1435. 17 Aug. 2018, doi:10.2147/CIA.S171307.
 Zajonz D, Prager F, Edel M, et al. The significance of the vitamin D metabolism in the development of periprosthetic infections after THA and TKA: a prospective matched-pair analysis of 240 patients. Clin Interv Aging. 2018;13:1429-1435. Published 2018 Aug 17. doi:10.2147/CIA.S171307.