The Anterior Cruciate Ligament Can Become Hypertrophied in Response to Mechanical Loading: A Magnetic Resonance Imaging Study in Elite Athletes.

BACKGROUND: Evidence, mainly from animal models, suggests that exercise during periods of pubertal growth can produce a hypertrophied anterior cruciate ligament (ACL) and improve its mechanical properties. In humans, the only evidence of ACL hypertrophy comes from a small cross-sectional study of elite weight lifters and control participants; that study had methodological weaknesses and, thus, more evidence is needed. PURPOSE: To investigate bilateral differences in the ACL cross-sectional area (CSA) for evidence of unilateral hypertrophy in athletes who have habitually loaded 1 leg more than the other. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: We recruited 52 figure skaters and springboard divers (46 female and 6 male; mean age, 20.2 ± 2.7 years) because the former always land/jump on the same leg while the latter always drive the same leg into the board during their hurdle approach. Sport training for all participants began before puberty and continued throughout as well as after. Using oblique axial- and oblique sagittal-plane magnetic resonance imaging, we measured the ACL CSA and the anteroposterior diameter of the patellar tendon, respectively. In addition, isometric and isokinetic knee extensor and flexor peak torques were acquired using a dynamometer. Bilateral differences in the ACL CSA, patellar tendon diameter, and knee muscle strength were evaluated via 2-sided paired-samples t tests. Correlations between the bilateral difference in the ACL CSA and age of training onset as well as between the bilateral difference in the ACL CSA and years of training were also examined. RESULTS: A significantly larger ACL CSA (mean difference, 4.9% ± 14.0%; P = .041), as well as patellar tendon diameter (mean difference, 4.7% ± 9.4%; P = .002), was found in the landing/drive leg than in the contralateral leg. The bilateral difference in the ACL CSA, however, was not associated with the age of training onset or years of training. Last, the isometric knee flexor peak torque was significantly greater in the landing/drive leg than the contralateral leg (mean difference, 14.5% ± 33.8%; P = .019). CONCLUSION: Athletes who habitually loaded 1 leg more than the other before, during, and after puberty exhibited significant unilateral ACL hypertrophy. This study suggests that the ACL may be able to be "trained" in athletes. If done correctly, it could help lower the risk for ACL injuries.

The Association Between Preoperative Opioid Exposure and Prolonged Postoperative Use.

OBJECTIVE: To determine the effect of nonchronic, periodic preoperative opioid use on prolonged opioid fills after surgery. BACKGROUND: Nonchronic, periodic opioid use is common, but its effect on prolonged postoperative opioid fills is not well understood. We hypothesize greater periodic opioid use before surgery is correlated with persistent postoperative use. METHODS: We used a national private insurance claims database, Optum's de-identifed Clinformatics Data Mart Database, to identify adults undergoing general, gynecologic, and urologic surgical procedures between 2008 and 2015 (N = 191,043). We described patterns of opioid fills based on dose, recency, duration, and continuity to categorize preoperative opioid exposure. Patients with chronic use were excluded. Our primary outcome was persistent postoperative use, defined as filling an opioid prescription between 91- and 180-days post-discharge. The association between preoperative opioid use and persistent use was determined using multivariable logistic regression, controlling for clinical covariates. RESULTS: In the year before surgery, 41% of patients had nonchronic, periodic opioid fills. Compared with other risk factors, patterns of preoperative fills were most strongly correlated with persistent postoperative opioid use. Patients with recent intermittent use were significantly more likely to have prolonged fills after surgery compared with opioid-naïve patients [minimal use: odds ratio (OR): 2.0, 95% confidence interval (CI) 1.89-2.03; remote intermittent: OR 4.7, 95% CI 4.46-4.93; recent intermittent: OR 12.2, 95% CI 11.49-12.90]. CONCLUSIONS: Patients with nonchronic, periodic opioid use before surgery are vulnerable to persistent postoperative opioid use. Identifying opioid use before surgery is a critical opportunity to optimize care after surgery.

Multifunctional and Spatially Controlled Bioconjugation to Melt Coextruded Nanofibers.

Polymeric fibers have drawn recent interest for uses in biomedical technologies that span drug delivery, regenerative medicine, and wound-healing patches, amongst others. We have recently reported a new class of fibrous biomaterials fabricated using coextrusion and a photochemical modification procedure to introduce functional groups onto the fibers. In this report, we extend our methodology to control surface modification density, describe methods to synthesize multifunctional fibers, and provide methods to spatially control functional group modification. Several different functional fibers are reported for bioconjugation, including propargyl, alkene, alkoxyamine, and ketone modified fibers. The modification scheme allows for control over surface density and provides a handle for downstream functionalization with appropriate bioconjugation chemistries. Through the use of multiple orthogonal chemistries, fiber chemistry could be differentially controlled to append multiple modifications. Spatial control on the fiber surface was also realized, leading to reverse gradients of small molecule dyes. One application is demonstrated for pH-responsive drug delivery of an anti-cancer therapeutics. Finally, the introduction of orthogonal chemical modifications onto these fibers allowed for modification with multiple cell-responsive peptides providing a substrate for osteoblast differentiation.

Coextruded, aligned, and gradient-modified poly(ε-caprolactone) fibers as platforms for neural growth.

Polymeric fibers are of increasing interest to regenerative medicine, as materials made from these fibers are porous, allowing for cell infiltration, influx of nutrients, and efflux of waste products. Recently, multilayered coextrusion has emerged as a scalable and rapid fabrication method to yield microscale to submicron fibers. In this report, we describe the multilayered coextrusion of aligned poly(ε-caprolactone) (PCL) fibers, followed by a simple photochemical patterning to create surface-immobilized gradients onto the polymer fibers. PCL fibers were photochemically decorated with a linear gradient of propargyl benzophenone using a gradient photomask to control light source intensity. The pendant alkynes were then able to undergo the copper-catalyzed azide-alkyne cycloaddition reaction with an azide-modified IKVAV peptide to further functionalize the surface. Gradient-modified IKVAV fibers were evaluated for neural cell adhesion and neural differentiation, using PC-12 cells cultured onto the fibers. The aligned gradient fibers provided directional cues for neurite outgrowth and alignment of neural cells, as observed by cellular elongation, neurite differentiation, and orientation. The work presented herein describes a scalable fiber system combined with simple chemical patterning to generate aligned fibers with controlled surface gradients as cell-seeding scaffolds.