Perioperative nutrition and amino-acid augmentation — reading our cost-of-illness paper into a clinic protocol.

Why this matters — the economic case our paper makes.

Earlier this year our group at the University of the Sunshine Coast published a cost-of-illness analysis in the ANZ Journal of Surgery quantifying the economic burden of metabolic syndrome in elective surgery in Australia.¹ The headline finding is uncomfortable but useful: the surgical economy quietly pays a large bill for the metabolic state of the patients it operates on — longer length of stay, higher readmission rates, higher complication rates, higher revision rates, and downstream years-of-life-with-disability adjustments. The numbers move from the editorial-page kind of argument into the operational kind.

The paper does not argue for a particular nutritional intervention. It argues for a particular posture: that the surgeon's job is not only to operate well but to make sure the host biology arriving in theatre is the best version of itself that the timeline allows. Operating on a patient whose metabolic and nutritional state is below the line, when those things were modifiable, is a missed step in the modern operative pathway.

This essay walks the next step. How, exactly, do you optimise the host biology in the four-to-six-week pre-operative window? Which amino acids? At which doses? With which evidence? And what does that look like translated into a clinic-level protocol?

Why the conversation has spread beyond rotator cuff repair.

For most of the last two decades, the perioperative-nutrition conversation in orthopaedics has been confined to rotator cuff repair. The biology of tendon healing depends on protein substrate; smokers and vitamin D-deficient patients heal worse; the surgeon optimises what is optimisable. That was the conversation. At the May 2026 Stryker Shoulder Masters Meeting it was the first time I had heard a serious nutrition conversation extended to shoulder arthroplasty. Different speakers, on different sessions, kept returning to the same point: the bone-implant interface in a reverse, the soft-tissue envelope in a primary, the periprosthetic-fracture risk in the older patient — all of it sits on a metabolic substrate that the surgeon usually ignores until something goes wrong.

Rotator cuff repair is the operation in our field where the nutrition argument is best worked out, so the science walks more cleanly from there. The tendon-to-bone interface heals by extracellular-matrix synthesis — mostly collagen — and collagen is built from amino acids. The host that cannot supply the substrate cannot build the matrix. The published unhealed-cuff-repair rate is roughly 11% for small isolated tears and climbs to 40–90% in massive multi-tendon tears with significant retraction.² Smoking, hypovitaminosis D, and metabolic syndrome consistently appear in the multivariable models for non-healing. The biology around the operation drives the outcome at least as much as the construct does. The Rotator Cuff Healing Index essay structures this into a score; the biology of cuff repair essay walks through the underlying mechanisms in narrative form.

Specific amino acids — what to actually do.

The pragmatic question is: what do you change in clinic on Monday morning? Five threads are worth pulling on.

1. Total protein intake — the foundation.

ESPEN clinical-nutrition guidelines for the surgical patient recommend approximately 1.2–1.5 g of protein per kilogram of body weight per day in the perioperative window — well above the 0.8 g/kg/day baseline that most Australian adults consume.³ For older patients with sarcopenia the target moves higher again, toward 1.5–2.0 g/kg/day. The clinical implication for a typical rotator-cuff-repair patient is straightforward: one to two additional high-protein meals or supplements per day in the four weeks before surgery and the six weeks after. A dietary recall in clinic almost always finds them well short.

This is the foundation. None of the more sophisticated amino-acid interventions below rescue the patient who is missing the basics.

2. Leucine — the metabolic switch.

Leucine is one of three branched-chain amino acids and is the metabolic trigger for muscle protein synthesis — it activates the mTOR pathway, the cellular switch that tells muscle (and, to a lesser extent, tendon) to build new protein. The dose-response is not linear. A leucine bolus of approximately 2.5–3 g per meal appears to be the threshold dose for stimulating protein synthesis in older adults — below that threshold, the synthesis response is muted; above it, the additional response plateaus.⁴

The practical implication is to concentrate protein at meals rather than spread it thinly across the day. A meal containing 25–30 g of high-quality protein (whey, lean beef, fish, eggs, or a leucine-enriched supplement) crosses the leucine threshold and triggers the anabolic response. Three such meals across the day will move the needle. Six small snacks of 10 g of protein each, despite adding to the same total daily intake, often will not.

Whey protein has the highest leucine content per gram of any commonly available protein source. For patients who struggle to eat solid food in the early post-operative period, a whey protein shake post-meal is the most efficient way to hit the threshold.

3. HMB — the catabolism brake.

HMB (β-hydroxy-β-methylbutyrate) is a metabolite of leucine. While leucine drives protein synthesis, HMB reduces protein breakdown — complementing the synthesis effect from the other direction. The published evidence base sits mostly in cancer cachexia and post-operative sarcopenia, where HMB demonstrably preserves muscle mass and physical function during periods of catabolic stress.⁵ The mechanism is biologically plausible in the cuff-repair sarcopenic-shoulder context, where post-operative disuse atrophy is the rule rather than the exception. Typical dose is 3 g per day, divided across two or three doses with meals. It is well-tolerated, inexpensive, and available over the counter in Australia.

4. Vitamin D — the cheapest single win.

Hypovitaminosis D is over-represented in cuff-repair failure series and is the easiest single thing to fix — serum 25-OH vitamin D, replacement if low, cheap, safe, well-tolerated.⁶ Every rotator-cuff-repair patient and every shoulder-arthroplasty patient should have a 25-OH vitamin D measured at booking. The threshold for replacement is debated but operating from a position of "let's get them above 75 nmol/L before theatre" is reasonable. The cost of a 1000-IU/day or 2000-IU/day supplement for six weeks is trivial; the upside on tendon-bone integration and on the broader bone-health story is real.

5. Immunonutrition — the higher-risk patient.

Pre-operative supplementation with a formula combination of arginine, omega-3 fatty acids, nucleotides and antioxidants has the strongest evidence in upper-GI cancer surgery, where a 5–7-day pre-operative course of an "immunonutrition" formula such as Impact Oral reduces infectious complications.⁷ In shoulder arthroplasty the evidence is extrapolated rather than direct — we do not have a large RCT in shoulder replacement to point to. The mechanism is reasonable, though: supporting wound healing and the immune response to the implant-host interface in the higher-risk patient. I do not prescribe this routinely; I do consider it in the patient with diabetes, the patient with a previous infection, the patient on chronic steroids, and the revision patient.

What this looks like as a single sentence.

For most rotator-cuff-repair and shoulder-arthroplasty patients: 1.2–1.5 g/kg/day total protein, concentrated at meals to clear the leucine threshold, vitamin D measured and replaced if low, the four-to-six weeks before surgery treated as the most important window in the entire pathway. Selective HMB and immunonutrition in the higher-risk patient.

None of this is a magic bullet.

The point underneath the list is that the perioperative nutritional intervention is dose-dependent, time-dependent, and largely free of meaningful harm. A four-to-six-week pre-operative window of optimisation moves the host biology in a direction that the surgical construct cannot. Nothing here replaces the operation. Everything here helps the operation do what it is supposed to do.

What I am doing differently in clinic.

Three concrete changes after the Stryker Masters Meeting and our paper:

1. A dietary recall at the first consultation for every cuff repair and arthroplasty patient — not a moral conversation, a metabolic one. The recall takes three minutes and the result is almost always a protein-intake number well under the surgical-window target. Most patients want to know — nobody is offended by the conversation when it is framed as "let's get the biology ready for the operation."
2. A serum 25-OH vitamin D on every booking, treated if low. The cost is trivial and the upside is real. The local Birtinya GPs and our care coordinator have built this into the pre-operative bloods order so it does not require a separate visit.
3. A standardised handout covering the four-week pre-operative nutrition window — the protein target, leucine-rich meals, vitamin D, smoking cessation, alcohol — built into the clinical-experience pre-operative pack rather than left to the patient to assemble. The handout includes example day-by-day meal plans for two body weights (70 kg and 90 kg) so the abstract gram-per-kilogram targets become specific meals.

Watch this space. There will be a follow-up post once the protocol has run for six months and the early data are worth sharing — particularly on the protein-intake recall numbers, the vitamin D replacement rates, and any signal in the cuff-repair healing rates at six-month MRI.

The deeper point.

Our cost-of-illness paper is the closest thing in the recent Australian orthopaedic literature to a numerical argument that perioperative metabolic optimisation pays for itself many times over — in shorter stays, fewer complications, fewer revisions. It is, in that sense, an argument the system can hear. But the more important argument lives one level beneath the numbers: that the surgical decision should not stop at the operation. The four-to-six weeks before theatre are the most leveraged window in the entire pathway. Spending a fraction of the surgical effort on the host biology in that window is the kind of detail that, over a career, separates the careful practice from the busy one.

The amino acids above are not exotic. The science is mature. The doses are well-defined. The cost is trivial. The patient gets the operation they came for — performed on a body that has been deliberately prepared to heal it. That is the model. The Sydney meeting was where I saw it land in real time across an arthroplasty audience for the first time.

---

Related reading on this site

• Three takeaways from the Stryker Shoulder Masters Meeting, Sydney 2026 — the parent essay that surfaces this deep-dive as takeaway #2
• Rotator Cuff Healing Index — predicting failure, augmenting biology (the score that structures host-biology risk)
• The biology of rotator cuff repair: why technique has hit a ceiling
• Research & Affiliations — the Coory et al 2026 cost-of-illness paper

References

1. Norris P, Gow J, Arthur T, Rodda D, Coory J, Oprescu F, Neville S, Ralph N. The Economic Burden of Metabolic Syndrome in Elective Surgery: An Australian Cost-of-Illness Study. ANZ J Surg. 2026. doi:10.1111/ans.70588. PMID 41859958.
2. Galatz LM, Ball CM, Teefey SA, Middleton WD, Yamaguchi K. The outcome and repair integrity of completely arthroscopically repaired large and massive rotator cuff tears. J Bone Joint Surg Am. 2004;86(2):219–224.
3. Weimann A, Braga M, Carli F, et al. ESPEN guideline: Clinical nutrition in surgery. Clin Nutr. 2017;36(3):623–650. (Updated 2021.)
4. Devries MC, Phillips SM. Supplemental protein in support of muscle mass and health: Advantage whey. J Food Sci. 2015;80(S1):A8–A15. (See also: Phillips SM, Chevalier S, Leidy HJ. Protein "requirements" beyond the RDA: implications for optimizing health. Appl Physiol Nutr Metab. 2016;41(5):565–572.)
5. Bear DE, Langan A, Dimidi E, et al. β-Hydroxy-β-methylbutyrate and its impact on skeletal muscle mass and physical function in clinical practice: a systematic review and meta-analysis. Am J Clin Nutr. 2019;109(4):1119–1132.
6. Cancienne JM, Brockmeier SF, Rodeo SA, Werner BC. Hypovitaminosis D as a risk factor for rotator cuff repair failure. Am J Sports Med. 2020;48(13):3325–3331.
7. Marimuthu K, Varadhan KK, Ljungqvist O, Lobo DN. A meta-analysis of the effect of combinations of immune modulating nutrients on outcome in patients undergoing major open gastrointestinal surgery. Ann Surg. 2012;255(6):1060–1068.