As a result of supplementation, patients had improved function and quicker achievement of rehabilitation benchmarks.
“Decreased mechanical loading after orthopedic surgery predisposes patients to develop muscle atrophy,” the researchers wrote. “This disuse atrophy is a result of a multitude of factors, including the postoperative catabolic state and loss of neuromuscular activation.”
Muscle atrophy in the postoperative period can be a challenge to overcome and can lead to pain, weakness, decreased range of motion (ROM), increased risk of injury and diminished quality of life.
“While physical therapy can help combat postoperative muscle atrophy and its negative consequences, muscle atrophy often persists despite progressive rehabilitation,” the researchers added. “Understanding the biochemical mechanisms of disuse musculoskeletal atrophy, as well as formulating strategies to counteract it, is therefore a high priority for improving clinical outcomes after orthopedic surgery.”
The researchers examined fourteen studies which included 611 patients (224 male, 387 female). The goal was to identify high quality studies that evaluated the use of proteins, amino acids or peptides to prevent or treat muscle atrophy in the postoperative period following any orthopedic procedure.
The researchers cataloged the functional or measures of muscle atrophy or strength. They also explored patient satisfaction and time to return to sport or work.
Next, they gathered demographic data, protein supplement regimen used, outcomes, complications and length of follow up. Four surgical groups were identified: anterior cruciate ligament reconstruction (ACLR), total hip arthroplasty (THA), hip fractures (THA, revision THA, hip resurfacing) and total knee arthroplasty (TKA). The average length of follow-up was nine weeks for ACLR, seven weeks for THA, 10 weeks for hip fracture, and seven weeks for TKA. Study participants received various combinations of essential amino acids in tablet form or protein powder. Two studies utilized milk protein supplementation.
“Protein supplementation was reported to have beneficial effects across all types of identified surgeries. The primary benefit was decreased muscle atrophy measured by muscle cross sectional area,” the researchers wrote. “The most significant difference in muscle atrophy was observed in the final week of follow-up for 11/14 studies.”
Eight of the fourteen studies also demonstrated improved functional measures, including increased muscle function measured by isokinetic muscle strength. Specifically, protein supplementation was found to have a significant effect on muscle cross-sectional area and isokinetic muscle strength, which was most notable in the final follow-up week for 11/14 studies. Several of the studies examined here also reported improved functional measures and quicker achievement of rehabilitation benchmarks.
The researchers noted that the review may be the first of its kind to evaluate protein and amino acid supplementation following orthopedic injuries.
“This information could help providers recommend appropriate nutritional supplementation after specific orthopedic procedures, and it could identify areas where further research is needed,” they wrote.
There were some caveats.
“It is difficult to recommend a specific, maximally effective regimen based on this review,” the researchers wrote. “Therefore, further RCTs with greater methods of standardization will be required to improve targeting and to further develop guidelines for populations who may stand to benefit from nutritional intervention.”
Also, there was wide variation in the types of protein supplements used, most evident in the ACLR cohort. One study evaluated protein in the form of skim milk and soybean product, while another chose whey protein for supplementation.
“These factors are important as protein source affects absorption rate and amino acid flux, which may acutely contribute to differences in nutrient sensing and signaling,” the researchers concluded.
Additionally, other factors play a role in recovery after various orthopedic procedures. Varying demographics, medical comorbidities and baseline functional status of the patient may play a unique role in overall recovery and return to function. Moreover, the rehabilitation procedures are very different among each surgery, the researchers explained. As rehabilitation strategies may improve functional recovery after each orthopedic protocol, further research is needed to determine the role protein supplementation may play in the context of these rehabilitation approaches.
Source: Sports Medicine and Health Science
“Post-operative protein supplementation following orthopaedic surgery: A systematic review”
Authors: Andrew George et al.