Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

No abstract

Background. By the year 2030, 3.48 million older U.S. adults are projected to undergo total knee arthroplasty (TKA). Following this surgery, considerable muscle atrophy occurs, resulting in decreased strength and impaired functional mobility. Essential amino acids (EAAs) have been shown to attenuate muscle loss during periods of reduced activity and may be beneficial for TKA patients.Methods. We used a double-blind, placebo-controlled, randomized clinical trial with 28 older adults undergoing TKA. Patients were randomized to ingest either 20 g of EAAs (n = 16) or placebo (n = 12) twice daily between meals for 1 week before and 2 weeks after TKA. At baseline, 2 weeks, and 6 weeks after TKA, an MRI was performed to determine mid-thigh muscle and adipose tissue volume. Muscle strength and functional mobility were also measured at these times.Results. TKA patients receiving placebo exhibited greater quadriceps muscle atrophy, with a -14.3 ± 3.6% change from baseline to 2 weeks after surgery compared with -3.4 ± 3.1% for the EAA group (F = 5.16, P = 0.036) and a -18.4 ± 2.3% change from baseline to 6 weeks after surgery for placebo versus -6.2 ± 2.2% for the EAA group (F = 14.14, P = 0.001). EAAs also attenuated atrophy in the nonoperated quadriceps and in the hamstring and adductor muscles of both extremities. The EAA group performed better at 2 and 6 weeks after surgery on functional mobility tests (all P < 0.05). Change in quadriceps muscle atrophy was significantly associated with change in functional mobility (F = 5.78, P = 0.021).Conclusion. EAA treatment attenuated muscle atrophy and accelerated the return of functional mobility in older adults following TKA.Trial registration. Clinicaltrials.gov NCT00760383.

Background:Substantial muscle atrophy occurs after total knee arthroplasty (TKA), resulting in decreased strength and impaired mobility. We sought to determine whether perioperative supplementation with essential amino acids (EAA) would attenuate muscle atrophy following TKA and whether the supplements were safe for ingestion in an older surgical population.Methods:We performed a double-blind, placebo-controlled, randomized trial of 39 adults (age range, 53 to 76 years) undergoing primary unilateral TKA who ingested 20 g of EAA (n = 19) or placebo (n = 20) twice daily for 7 days preoperatively and for 6 weeks postoperatively. At baseline and 6 weeks postoperatively, magnetic resonance imaging (MRI) scans were obtained to measure quadriceps and hamstrings muscle volume. Secondary outcomes included functional mobility and strength. Data on physical activity, diet, and patient-reported outcomes (Veterans RAND 12-Item Health Survey and Knee injury and Osteoarthritis Outcome Score) were collected. Safety was determined through blood tests evaluating blood urea nitrogen, creatinine, creatinine clearance, homocysteine, and renal and liver function. Laboratory values at baseline, on the day of surgery, and at 2 days, 2 weeks, and 6 weeks postoperatively were compared between treatment groups. Analysis of covariance models, with baseline values as covariates, were used to evaluate outcomes between treatment groups. P values were adjusted for multiple tests.Results:Compared with baseline, the EAA group had significantly less decrease in mean quadriceps muscle volume compared with the placebo group in the involved leg (−8.5% ± 2.5% compared with −13.4% ± 1.9%; p = 0.033) and the contralateral leg (−1.5% ± 1.6% compared with −7.2% ± 1.4%; p = 0.014). The hamstrings also demonstrated a greater muscle-volume-sparing effect for the EAA group than for the placebo group in the involved leg (−7.4% ± 2.0% compared with −12.2% ± 1.4%; p = 0.036) and contralateral leg (−2.1% ± 1.3% compared with −7.5% ± 1.5%; p = 0.005). There were no differences between the groups in terms of functional measures or strength. Blood chemistry values varied significantly between assessments periods but did not statistically differ between groups.Conclusions:The results of the present study suggest that EAA supplementation is safe and reduces the loss of muscle volume in older adults recovering from TKA.Level of Evidence:Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Surgical technique is an important factor affecting recovery of hip function after total hip arthroplasty (THA). We therefore asked whether short-term recovery of hip strength and motion would differ between the anterior and anterolateral THA approaches. We presumed that although both approaches would improve hip function by 16 weeks postsurgery when compared with presurgery, a slower recovery would be demonstrated by the anterolateral group at 6 weeks when compared with the anterior group as a result of division and reattachment of the abductor muscles. We observed hip kinematics and kinetics during walking and isometric hip abductor strength for the involved limb. Hip abductor strength of all patients was lower than controls at all three testing times. Compared with presurgery, all patients demonstrated improved abductor strength at 16 weeks postsurgery. At 6 weeks, the patients with an anterior approach had improved late stance peak abductor moment postsurgery and reached the level of controls, but those with an anterolateral approach did not. Although the anterior approach was associated with improved gait velocity and peak flexor moments at 6 weeks compared to before surgery, we observed no differences between the two approaches for most of the isometric strength and dynamic gait measures at 6 or 16 weeks. Neither approach provided faster recovery.