Cellular and morphological changes with EAA supplementation before and after total knee arthroplasty.

Investigate the underlying cellular basis of muscle atrophy (Placebo) and atrophy reduction (essential amino acid supplementation, EAAs) in total knee arthroplasty (TKA) patients by examining satellite cells and other key histological markers of inflammation, recovery, and fibrosis. Forty-one subjects (53-76 yr) scheduled for TKA were randomized into two groups, ingesting 20 g of EAAs or placebo, twice-daily, for 7 days before TKA and for 6 wk after surgery. A first set of muscle biopsies was obtained from both legs before surgery in the operating room, and patients were randomly assigned and equally allocated to have two additional biopsies at either 1 or 2 wk after surgery. Biopsies were processed for gene expression and immunohistochemistry. Satellite cells were significantly higher in patients ingesting 20 g of essential amino acids twice daily for the 7 days leading up to surgery compared with Placebo (operative leg P = 0.03 for satellite cells/fiber and P = 0.05 for satellite cell proportions for Type I-associated cells and P = 0.05 for satellite cells/fiber for Type II-associated cells.) Myogenic regulatory factor gene expression was different between groups, with the Placebo Group having elevated MyoD expression at 1 wk and EAAs having elevated myogenin expression at 1 wk. M1 macrophages were more prevalent in Placebo than the EAAs Group. IL-6 and TNF-α transcripts were elevated postsurgery in both groups; however, TNF-α declined by 2 wk in the EAAs Group. EAAs starting 7 days before surgery increased satellite cells on the day of surgery and promoted a more favorable inflammatory environment postsurgery.NEW & NOTEWORTHY Clinical studies by our group indicate that the majority of muscle atrophy after total knee arthroplasty (TKA) in older adults occurs rapidly, within the first 2 wks. We have also shown that essential amino acid supplementation (EAAs) before and after TKA mitigates muscle atrophy; however, the mechanisms are unknown. These results suggest that satellite cell numbers are elevated with EAA ingestion before surgery, and after surgery, EAA ingestion positively influences markers of inflammation. Combined, these data may help inform further studies designed to address the accelerated sarcopenia that occurs in older adults after major surgery.

Essential Amino Acid Supplementation Mitigates Muscle Atrophy After Total Knee Arthroplasty: A Randomized, Double-Blind, Placebo-Controlled Trial.

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.

Transcriptional profiling and muscle cross-section analysis reveal signs of ischemia reperfusion injury following total knee arthroplasty with tourniquet.

Total knee arthroplasty (TKA) is the most common and cost-effective treatment for older adults with long-standing osteoarthritis. Projections indicate that nearly 3.5 million older adults will undergo this procedure annually by the year 2030. Thus, understanding the factors that lead to optimal outcomes is of great clinical interest. In the majority of cases, tourniquet is applied during surgery to maintain a clear surgical field, however, there is debate as to whether this intervention is completely benign. In particular, muscle atrophy is a significant factor in preventing full functional recovery following surgery, and some evidence suggests that tourniquet application and the associated ischemia-reperfusion injury that results contributes to muscle atrophy. For this reason, we examined tissue level changes in muscle in TKA patients following surgery and found that there was a significant increase in cross-sectional area of muscle fibers of all types. Furthermore, to detect changes not evident at the tissue level, we performed NextSeq analysis to assess the transcriptional landscape of quadriceps muscle cells following TKA with tourniquet and found 72 genes that were significantly upregulated. A large proportion of those genes regulate cell stress pathways, suggesting that muscle cells in our cohort of older adults were capable of mounting a significant response to cell stress. Furthermore, factors related to complement were upregulated, suggesting tourniquet may play a role in priming cells to ischemia reperfusion injury. Therefore, our analysis reveals potential harms of tourniquet during TKA, thus suggesting that surgeons should consider limiting its use.

Essential amino acid supplementation in patients following total knee arthroplasty.

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.

MAFbx, MuRF1, and the stress-activated protein kinases are upregulated in muscle cells during total knee arthroplasty.

Total knee arthroplasty (TKA) is the most common and a cost-effective surgical remediation for older adults with long-standing osteoarthritis. In parallel with the expanding population of older adults, the number of TKAs performed annually is projected to be 3.48 million by 2030. During this surgery, a tourniquet is used to stop blood flow to the operative leg. However, the molecular pathways that are affected by tourniquet use during TKA continue to be elucidated. We hypothesized that components of the catabolic FoxO3a (i.e., MuRF1, MAFbx, and Bnip3) pathway, as well as the cellular stress pathways [i.e., stress-activated protein kinase (SAPK)/JNK and MAPKs], are upregulated during TKA. The purpose of this study was to measure changes in transcripts and proteins involved in muscle cell catabolic and stress-activated pathways. We obtained muscle biopsies from subjects, 70 ± 1.3 yr, during TKA, from the vastus lateralis at baseline (before tourniquet inflation), during maximal ischemia (just before tourniquet release), and during reperfusion. Total tourniquet time was 43 ± 2 min and reperfusion time was 16 ± 1. Significant increases in FoxO3a downstream targets, MAFbx and MuRF1, were present for mRNA levels during ischemia (MAFbx, P = 0.04; MuRF1, P = 0.04), and protein expression during ischemia (MAFbx, P = 0.002; MuRF1, P = 0.001) and reperfusion (MuRF1, P = 0.002). Additionally, stress-activated JNK gene expression (P = 0.01) and protein were elevated during ischemia (P = 0.001). The results of this study support our hypothesis that protein degradation pathways are stimulated during TKA. Muscle protein catabolism is likely to play a role in the rapid loss of muscle volume measured within 2 wk of this surgery.

Retrieval analysis of failed constrained acetabular liners.

Despite the large loads placed upon constrained acetabular liners, little is known of their mechanical performance. We analyzed retrieved liners to determine wear and other damage modes and assess associations between types and severity of damage and clinical, radiographic, and implant variables. Outer rim impingement frequency and severity were higher than that for the inner rim. The 20 degrees elevation was most frequently affected by impingement. Inner rim impingement was more frequent with small heads. Outer bearing surface wear scores were higher than inner bearing scores. Liners removed for infection or stem failure had similar damage compared with other groups, demonstrating the complex relationship of impingement and wear with clinical performance. No association was found between liner damage and clinical and radiographic variables.

Early wound complications after operative treatment of high energy tibial plateau fractures through two incisions.

Dual plating of complex, bicondylar tibial plateau fractures through an anterolateral and posteromedial approach is often performed to treat fractures complicated by a significantly displaced posteromedial fragment or a depression of the medial articular surface. The purpose of the present study was to (1) determine the deep infection rate of such fractures that are operatively fixed after allowing for soft tissue recovery and (2) compare this rate to other series in the literature. The study group was comprised of 29 patients with 29 AO/OTA 41-C bicondylar tibial plateau fractures. The average length of follow-up was 16.4 months. The deep infection rate was 13.8% (4/29). A lower rate of deep infection was observed compared to historical reports. This is likely a result of a treatment algorithm that requires recovery of the soft tissue envelope prior to definitive fixation.

Complete traumatic extrusion of the distal ulna through the hypothenar eminence: a case report.

We present a case of complete traumatic extrusion of the distal 40% of the ulna through the hypothenar eminence in the context of an open, both-bone forearm fracture and spinal cord transection. To the best of our knowledge, this specific trauma is unique to the literature, and, therefore, there is no standard treatment approach. Our patient was managed with irrigation and débridement along with open reduction and internal fixation of the radius fracture. No reconstruction of the ulna was performed. The patient reported excellent functional results at 13-month follow-up.

Flexion contracture after total knee arthroplasty in a patient with Parkinson's disease: successful treatment with botulinum toxin type A.

The few reports in the orthopedic literature that discuss outcomes after total knee arthroplasty in patients with Parkinson's disease cite mixed results. These patients are at increased risk for the development of flexion contracture, which has been shown to significantly worsen functional scores. The present report describes the development of a flexion contracture in a patient with Parkinson's disease after total knee arthroplasty. This contracture was successfully treated with manipulation under anesthesia and injections of botulinum toxin type A into the hamstring and gastrocnemius muscles, in conjunction with a static progressive extension orthosis and rigorous physical therapy.

Hemiarthroplasty for femoral neck fracture in the elderly surgeon and hospital volume-related outcomes.

The elderly patient with a displaced femoral neck fracture is commonly treated via hemiarthroplasty. The objectives of this study were to: 1) determine the rates of in-hospital mortality, complications, and prolonged length of stay (LOS) in such patients; 2) elucidate the patient characteristics that predict these occurrences; and 3) investigate the influence of surgeon and hospital volumes on these outcomes. Using the Nationwide Inpatient Sample (NIS), 173,508 cases of hemiarthroplasty for femoral neck fracture were identified in patients > or =65 years of age. Univariate and multivariate analysis demonstrated that hospitals with low caseload volumes were associated with increased patient risk for prolonged LOS, pulmonary embolism, urinary tract infection, and pneumonia. Surgeons with low caseload volumes were associated with increased risk for mortality and prolonged LOS. Quality-improvement initiatives would benefit from consideration of these factors.

Body mass index as a predictor of complications after operative treatment of acetabular fractures.

BACKGROUND: Obesity, a growing public health concern, is often thought to be an important risk factor for postoperative complications. We hypothesized that body mass index is predictive of complications after operative treatment of acetabular fractures. METHODS: A retrospective chart review identified 169 consecutive patients in whom an acetabular fracture had been treated with open reduction and internal fixation at a level-1 trauma center. The patients were stratified into four classes according to their body mass index: normal (<25), overweight (> or =25 but <30), obese (> or =30 but <40), and morbidly > or =40). The perioperative outcomes that were evaluated included estimated blood loss, wound infection, nerve palsy, deep venous thrombosis, pulmonary embolism, and heterotopic ossification. Multivariate general linear models were used to test for the relationship between body mass index and perioperative outcomes while controlling for potential intervening variables (including surgical approach, fracture type, and surgeon experience). Odds ratios were calculated as well. RESULTS: When body mass index was measured as a continuous variable, it was found to have a significant relationship with estimated blood loss (p = 0.003), prevalence of wound infection (p = 0.002), and prevalence of deep venous thrombosis (p = 0.03). Odds ratio analysis revealed that obese subjects (body mass index of > or =30) were 2.1 times more likely than patients of normal weight (body mass index of <25) to have an estimated blood loss of >750 mL and 2.6 times more likely to have a deep venous thrombosis. Morbidly obese patients (body mass index of > or =40) were five times more likely to have a wound infection. CONCLUSIONS: Body mass index is predictive of complications after operative treatment of acetabular fractures.

Chronic exertional compartment syndrome.

Chronic exertional compartment syndrome is an overuse condition affecting primarily active, athletic people. Its etiology is unclear, but several theories have been proposed. The syndrome is characterized by recurrent, often severe muscle compartment pain that occurs with vigorous exercise and subsides with rest. Physical examination usually provides little helpful information. Compartment pressure measurement before and after exercise is the mainstay of objective diagnosis. Conservative management has been highly unsuccessful. Overall, considerable success can be expected from fasciotomy of the involved compartments followed by a rigorous rehabilitation program, though recurrence of symptoms is a reported complication. Recent research efforts have focused on the development of less invasive and more accurate diagnostic modalities and safer and more effective surgical procedures.

Screw migration from total knee prostheses requiring subsequent surgery.

Complications in total knee arthroplasty directly related to hardware failure other than polyethylene wear are rare. We report 2 cases of symptomatic screw migration into the joint space from total knee prostheses. In the first case, a screw disengaged from a constrained condylar knee prosthesis. Arthroscopy using standard arthroscopy portals and a small arthrotomy were performed to remove the screw. In the second case, symptomatic screw disengagement and posterior migration from the tibial component of a posterior-stabilized prosthesis occurred. Revision with replacement of the polyethylene insert and locking screw was required.