Nutrition for amputations

In the United States, an estimated 2.3 million people are living with limb loss, and approximately 465,000 amputations take place annually. Amputations are often linked to health conditions such as diabetes (57% of cases), infections (43%), and vascular disease (40%). Considering the vital role nutrition plays in healing and overall quality of life for amputations, it is essential for dietitians to be well-informed of the unique assessment considerations for this population.   

Adjusting body weight 

In recent years, the Academy of Nutrition and Dietetics has discouraged the use of adjusted body weight (ABW) in the general population due to insufficient evidence of its accuracy and relevance. However, careful consideration is needed when determining whether to utilize actual body weight versus adjusted body weight for various assessments in those with limb loss.

A formula, commonly referred to as the “Osterkamp method,” was published in the Journal of the American Dietetic Association in 1995 and remains widely used by many practitioners today. The formula is as follows, utilized in combination with a body segment chart like the one shown here:   

  Wto / (1-P) = WtE 

• Wto is the current body weight, or the “observed” body weight 
• P represents the fraction of total body weight accounted for by the missing body segment (see chart pictured) 
• WtE or “estimated weight” can then be used to calculate BMI, or in other formulas 

*Please note there is no consensus on how much each limb contributes to total body weight, so values may vary slightly across different sources.  This chart is an adaptation of the chart provided by the AND.  

For example, you have a patient who has a history of bilateral below-knee amputations (BKA) with a current weight of 145 lbs (65.9kg). Per the chart provided, a BKA would be estimated at 5.9% (1.5% + 4.4%), and this patient has experienced bilateral BKA (5.9% x 2 = 11.8%).  So for this case, “P” = 11.8% or 0.118. Our calculation would proceed as follows:  

65.9kg / (1 – 0.118) = 74.7kg WtE 

It is important to note that inaccurately calculating the missing segment proportion can lead to errors in the calculation for ABW. This will, in turn, affect the results of any other calculation requiring the use of the ABW. As you are likely aware, not all amputations occur right at the hip, knee, or ankle; some individuals are left with residual limbs (for example, a long residual limb may be ⅔ of the original thigh). 

Due to this, a more recent method has been developed by Arupendra Mozumdar that can be applied to limb loss occurring between the joints rather than just at the hip, knee, or ankle per the Osterkamp method. 

This is likely a more accurate estimate of ABW, however it is much more involved. For the Mozumdar method, depending on the level of limb loss, physical measurements are needed such as residual limb length, knee height, and buttock-knee length. When actual measurements are not available, the Osterkamp method can be used by estimating the proportion of the missing segment, rather than just rounding to the nearest joint.

The example below depicts a patient with an above-knee amputation (AKA) with a long residual limb (approximately ⅔ of the original thigh). You can see how there would be quite a difference in calculations using 16% for AKA versus 9.27% accounting for the residual limb.

Body Mass Index (BMI) interpretation 

The standard BMI calculation is not applicable to individuals with limb loss, as it does not consider the absence of a limb. Unfortunately, there are currently no validated tools for assessing BMI in this population. The proposed method for more accurately interpreting BMI in this population is to first calculate adjusted body weight using the previously discussed approach and then use that value along with the individual’s pre-amputation height (or arm span measurement) to determine BMI.

Other methods for BMI assessment in this population have been suggested (such as upper arm anthropometry, corrected arm muscle area, and mid-upper arm circumference), however, the studies are small and primarily focused on individuals with lower limb loss. It is also important to note that BMI is a tool to be utilized in conjunction with other valid measures of risk (such as waist circumference, genetic or metabolic factors, measurements of body fat percentage, etc.) rather than a sole clinical measure.

Estimating nutrition needs 

Not all calculations will require the use of adjusted body weight. According to the Academy’s Evidence Analysis Library, in non-critically ill individuals, the Mifflin-St. Jeor equation using actual body weight is regarded as the most reliable method for estimating resting energy expenditure when indirect calorimetry is unavailable.

However, in certain situations, such as critical illness, edema, or elevated BMI, other values may be more appropriate. Adjusted body weight (ABW) or ideal body weight (IBW) have been used when assessing energy and protein needs historically by clinicians, although limited research exists to validate this. Clinical judgment is recommended when determining whether to use ABW, IBW, or actual weight in this population. 

Energy, protein, and fluid needs are highly individualized based on a full clinical picture. In the immediate post-operative state, nutrition therapy for comorbid conditions (such as diabetes, renal disease, heart disease, etc.) should serve as the foundation for baseline nutrition prescriptions, with adjustments made as needed to support optimal wound healing. 

During this period, higher protein intake is recommended (1.25 – 2.0 g/kg per day), typically encouraged through easily digested whole foods, though oral nutrition supplements can also be used if necessary. In the long-term phase, protein requirements return to normal.

Other considerations 

• Weight gain. Factors contributing to weight gain include decreased physical activity, mood changes, medication side effects, and lifestyle adjustments—such as challenges with food shopping and meal preparation. Excess weight will further stress the joints which may already be affected by prosthetics. It also increases the risk of complications, including infections, pressure ulcers, osteoarthritis, and cardiovascular disease. Counseling approaches for weight management, if the individual is open to this, are an important consideration.   
• Constipation. Patients may experience constipation as a result of reduced mobility and pain medications. In these cases, a high-fiber diet, along with sufficient fluid intake, may be beneficial. 
• Bone health. Low bone mineral density can occur in the residual limb, so it’s important to ensure adequate intake of calcium and vitamin D to maintain bone density and strength. In some cases, micronutrient supplementation may be necessary. 
• Pressure ulcers. While this needs to be individualized, it’s estimated that a protein intake of 1.25-2.0g/kg is required to facilitate pressure injury healing. Wound-specific oral nutrition supplements can be helpful such as those with arginine-enriched formulas, with antioxidants and zinc which are associated with increased healing rates and are a cost-effective way to optimize healing. Vitamin C supplementation (at least 500 mg/day) can support healing, while zinc should only be supplemented if a deficiency is present as excessive zinc can deplete copper stores which harms skin strength and tissue integrity. Evidence for specific wound-healing supplements is limited, and a varied diet from all food groups is the best way to ensure adequate micronutrient intake, though a multivitamin may be considered if nutrition is lacking.
• Meal preparation. Before discharge, the dietitian should review meal preparation with the patient and, as needed, collaborate with occupational therapy staff to recommend suitable assistive devices for use at home. 
• Managing comorbidities. Often, individuals will have comorbid conditions such as diabetes, cardiovascular disease, or renal disease. Careful dietary management of these comorbid conditions is necessary for overall health and prevention of complications. 

Nutrition is a key factor in the recovery and long-term well-being of individuals with limb loss.  By implementing personalized nutrition strategies that promote healing and manage comorbidities, dietitians can help to improve outcomes and enhance overall quality of life. 

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References

Limb loss statistics. Amputee Coalition. (2024, October 18). https://www.amputee-coalition.org/resources/limb-loss-statistics. Accessed November 8, 2024. 

OSTERKAMP, L. K. (1995). Current perspective on assessment of human body proportions of relevance to amputees. Journal of the American Dietetic Association, 95(2), 215–218. https://doi.org/10.1016/s0002-8223(95)00050-x  

Andrews, A. M., & Pruziner, A. L. (2017). Guidelines for using adjusted versus unadjusted body weights when conducting clinical evaluations and making clinical recommendations. Journal of the Academy of Nutrition and Dietetics, 117(7), 1011–1015. https://doi.org/10.1016/j.jand.2016.07.003  

Estimating BMI for Patients with Amputations. Eatrightpro.org. https://www.eatrightpro.org/news-center/practice-trends/estimating-bmi-for-patients-with-amputations. Accessed November 8, 2024. 

Academy of Nutrition and Dietetics Evidence Analysis Library. “Adult weight management”. Accessed November 8, 2024. https://www.andeal.org/topic.cfm?menu=5276  

Academy of Nutrition and Dietetics. Nutrition Care Manual. Musculoskeletal, Amputations. Accessed November 8, 2024. 

Flint JH, Wade AM, Stocker DJ, Pasquina PF, Howard RS, Potter BK. Bone mineral density loss after combat-related lower extremity amputation. J Orthop Trauma. 2014 Apr;28(4):238-44. doi: 10.1097/BOT.0b013e3182a66a8a. PMID: 23912861. 

Shields BE. Diet in Wound Care: Can Nutrition Impact Healing? Cutis. 2021 Dec;108(6):325-328. doi: 10.12788/cutis.0407. PMID: 35167786