An Achilles tendon rupture is a devastating injury that prevents RTP for 30.6% of professional players. Athletes who do return play in fewer games, have less play time, and perform at a lower level than their preinjury status. However, these functional deficits are seen only at 1 year after surgery compared with matched controls, such that players who return to play can expect to perform at a level commensurate with uninjured controls 2 years postoperatively.

The purpose of staging in orthopaedic oncology is to provide a framework for classifying tumors based on their risk of local recurrence and distant metastasis to guide treatment decisions. Two separate systems are commonly used to categorize bone and soft-tissue sarcomas. The Musculoskeletal Tumor Society system for bone sarcomas and the Enneking system for soft-tissue sarcomas are the original staging systems developed by orthopaedic surgeons. The American Joint Committee on Cancer staging systems for bone and soft-tissue sarcomas are periodically updated based on new data, and they are currently on their eighth edition.

Ischemia of the myocardium and lower limbs is a common consequence of arterial disease and a major source of morbidity and mortality in modernized countries. Inducing neovascularization for the treatment of ischemia is an appealing therapeutic strategy for patients for whom traditional treatment modalities cannot be performed or are ineffective. In the past, the stimulation of blood vessel growth was pursued using direct delivery of growth factors, angiogenic gene therapy, or cellular therapy. Although therapeutic angiogenesis holds great promise for treating patients with ischemia, current methods have not found success in clinical trials. Fibroblast growth factor-2 (FGF-2) was one of the first growth factors to be tested for use in therapeutic angiogenesis. Here, we present a method for improving the biological activity of FGF-2 by codelivering the growth factor with a liposomally embedded coreceptor, syndecan-4. This technique was shown to increase FGF-2 cellular signaling, uptake, and nuclear localization in comparison with FGF-2 alone. Delivery of syndecan-4 proteoliposomes also increased endothelial proliferation, migration, and angiogenic tube formation in response to FGF-2. Using an animal model of limb ischemia, syndecan-4 proteoliposomes markedly improved the neovascularization following femoral artery ligation and recovery of perfusion of the ischemic limb. Taken together, these results support liposomal delivery of syndecan-4 as an effective means to improving the potential of using growth factors to achieve therapeutic neovascularization of ischemic tissue.

Introduction: Surgical site infections (SSIs) are common complications after surgeries involving musculoskeletal tumors, but we know little about SSI risk factors unique to orthopaedic oncology. A greater understanding of these factors will help risk-stratify patients and guide surgical decision-making. Methods: A retrospective review at a single-institution identified 757 procedures done on 624 over 6 years. The patients had a preoperative diagnosis of a malignant or potentially malignant neoplasm of the bone or soft tissues. Patient-specific and procedure-specific variables and diagnosis of SSI were recorded for each case. Data were analyzed through univariate analysis and multiple logistic regression. Results: On univariate analysis, significant patient-specific risk factors for SSI included malignancy (P < 0.001), smoking history (P = 0.041), and American Society of Anesthesiologists Score (P = 0.002). Significant procedure-specific risk factors for SSI on univariate analysis included surgery time (P < 0.001), estimated blood loss (P < 0.001), blood transfusion volume (P < 0.001), neoadjuvant chemotherapy (P < 0.001), neoadjuvant radiation therapy (P < 0.001), inpatient surgery (P < 0.001), and number of previous surgeries within the study period (P < 0.001). The two factors that independently predicted risk of SSI when controlling for all other variables in a multiple logistic regression were whether the surgery was done on an inpatient basis (P = 0.005) and the number of previous surgeries done on the same site (P = 0.001). Conclusions: We found a number of risk factors that correlate markedly with SSI after orthopaedic oncology surgery. The surgeon can use these risk factors to aid in surgical decision-making.

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A healthy skeleton relies on bone's ability to respond to external mechanical forces. The molecular mechanisms by which bone cells sense and convert mechanical stimuli into biochemical signals, a process known as mechanotransduction, are unclear. Focal adhesions play a critical role in cell survival, migration and sensing physical force. Focal adhesion kinase (FAK) is a non-receptor protein tyrosine kinase that controls focal adhesion dynamics and can mediate reparative bone formation in vivo and osteoblast mechanotransduction in vitro. Based on these data, we hypothesized that FAK plays a role in load-induced bone formation. To test this hypothesis, we performed in vitro fluid flow experiments and in vivo bone loading studies in FAK−/− clonal lines and conditional FAK knockout mice, respectively. FAK−/− osteoblasts showed an ablated prostaglandin E2 (PGE2) response to fluid flow shear. This effect was reversed with the re-expression of wild-type FAK. Re-expression of FAK containing site-specific mutations at Tyr-397 and Tyr-925 phosphorylation sites did not rescue the phenotype, suggesting that these sites are important in osteoblast mechanotransduction. Interestingly, mice in which FAK was conditionally deleted in osteoblasts and osteocytes did not exhibit altered load-induced periosteal bone formation. Together these data suggest that although FAK is important in mechanically-induced signaling in osteoblasts in vitro, it is not required for an adaptive response in vivo, possibly due to a compensatory mechanism that does not exist in the cell culture system.

Background: Many reference axes are used to evaluate rotation of the femoral component during total knee arthroplasty, including the Whiteside line, surgical transepicondylar axis (sTEA), anatomical transepicondylar axis (aTEA), posterior condylar axis externally rotated 3° (PCA+3°ER), sulcus line, and femoral transverse axis (FTA). There is no consensus about which of these axes is most accurate. Methods: The Stryker Orthopaedic Modeling and Analytics (SOMA) database was used to identify 2,128 entire-femur computed tomography (CT) scans. The Whiteside line, aTEA, PCA+3°ER, sulcus line, and FTA were constructed according to published guidelines. Every axis was compared with the sTEA, which is widely regarded as the gold standard reference axis for rotation of the distal part of the femur but has low intraobserver and interobserver reliability intraoperatively. Results: The PCA+3°ER differed from the sTEA by a mean (and standard deviation) of 0.60° ± 1.64°; it was the most accurate but also had the highest degree of intersubject variability. The mean PCA-sTEA angle was 2.40°, close to the accepted “rule of thumb” of 3°. This value was significantly higher in women (2.64° ± 1.74°) than in men (2.18° ± 1.52°; p < 0.001). The Whiteside line differed from the sTEA by a mean of 1.90° ± 1.38°, and the sulcus line differed from the sTEA by a mean of 1.94° ± 1.49°; neither of these values varied significantly with sex or ethnicity. The FTA differed from the sTEA by a mean of 2.04° ± 1.50°. Least accurate was the aTEA, which differed from the sTEA by a mean of 2.05° ± 1.33°. The combination of 3 axes that are readily available intraoperatively (the Whiteside line, aTEA, and PCA+3°ER) differed from the sTEA by a mean of 1.80° ± 0.70°. Conclusions: In the largest study of its kind, analysis of CT scans of 2,128 femora revealed that no 1 axis could serve as a marker of femoral component rotation with both high accuracy and low variability. Utilizing a combination of 3 methods (PCA+3°ER, the Whiteside or sulcus line, and aTEA) to maximize accuracy and sex and ethnic generalizability when positioning the femoral component is recommended. Clinical Relevance: A large-scale study using a CT-based biomorphometric database demonstrated that use of a combination of 3 axes (PCA+3°ER, the Whiteside or sulcus line, and aTEA) was the optimal strategy for judging femoral component rotation.

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