Interface-Mediated Neurogenic Signaling: The Impact of Surface Geometry and Chemistry on Neural Cell Behavior for Regenerative and Brain-Machine Interfacing Applications.

Nanomaterial advancements have driven progress in central and peripheral nervous system applications such as tissue regeneration and brain-machine interfacing. Ideally, neural interfaces with native tissue shall seamlessly integrate, a process that is often mediated by the interfacial material properties. Surface topography and material chemistry are significant extracellular stimuli that can influence neural cell behavior to facilitate tissue integration and augment therapeutic outcomes. This review characterizes topographical modifications, including micropillars, microchannels, surface roughness, and porosity, implemented on regenerative scaffolding and brain-machine interfaces. Their impact on neural cell response is summarized through neurogenic outcome and mechanistic analysis. The effects of surface chemistry on neural cell signaling with common interfacing compounds like carbon-based nanomaterials, conductive polymers, and biologically inspired matrices are also reviewed. Finally, the impact of these extracellular mediated neural cues on intracellular signaling cascades is discussed to provide perspective on the manipulation of neuron and neuroglia cell microenvironments to drive therapeutic outcomes.

Antibiotics Versus Surgery in Treatment of Early Flexor Tenosynovitis.

BACKGROUND: Treatment of pyogenic flexor tenosynovitis (FTS) historically involved surgical debridement supplemented with antibiotic therapy. No consensus exists on either: (1) the treatment algorithm for this infection; or (2) the clinical definition of "early" FTS. We performed a retrospective study to clarify indications for nonoperative management. METHODS: We identified 40 patients with a diagnosis of FTS using Current Procedural Terminology and International Classification of Diseases, Tenth Revision, codes and a keyword search from an electronic medical record between 2011 and 2019. Patients underwent either surgical management (SG) (n = 20) or early antibiotics only (EAG) (n = 20). The surgical group was divided into patients with intraoperative purulence within the tendon sheath (PU) and those without purulence (NP). RESULTS: The number of Kanavel signs and duration of days of symptoms were significantly greater in SG compared with EAG. Subgroup analysis of SG showed a greater number of days of symptoms in the NP group when compared with the PU group. No statistical significance was found with respect to age, smoking, or specific individual Kanavel signs between SG and EAG. CONCLUSIONS: Both duration of symptoms and number of Kanavel signs should be considered in suspected early FTS. Patients with shorter duration of symptoms and fewer Kanavel signs were treated successfully with antibiotics alone. Operatively confirmed FTS presented more acutely with fewer days of symptoms and a higher number of Kanavel signs. Patients with subacute presentations may represent inflammatory conditions and hand infections other than FTS.

Arthroscopic Capsulolabral Reconstruction for Posterior Shoulder Instability Is Successful in Adolescent Athletes.

BACKGROUND: Posterior shoulder instability is an increasingly common pathology recognized in athletes. Adolescent athletes are especially at risk for this condition due to the widespread participation in numerous sports, including both overhead throwing and collision activities. Little data are available regarding surgical outcomes in these athletes with only a single small case series (N=25) currently published. METHODS: In total, 68 athletes (82 shoulders) with unidirectional posterior shoulder instability were treated with arthroscopic posterior capsulolabral reconstruction and underwent an evaluation at a mean of 36 months postoperatively. The average age for our cohort was 17.2 years (range, 14 to 19 y), with 66 males (80%) and 16 females (20%). A total of 55 athletes (67%) participated in contact sports and 32 athletes (39%) participated in overhead throwing. Thirty athletes (37%) participated in multiple sports. Preoperative and postoperative outcomes data were retrospectively reviewed, and included the American Shoulder and Elbow Surgeons (ASES) shoulder score, subjective stability score, strength, range of motion, and return-to-play status. Intraoperative findings and methods of fixation were also recorded. RESULTS: Mean ASES score improved from 48.6 to 85.7 (P<0.001) after surgery. There were also significant improvements in stability, pain, and functional scores after surgery. Contact, throwing, and multisport athletes all showed similar scores at preoperative and follow-up timepoints, and no differences were noted between these athlete groups for any patient-reported outcome measure. Female athletes tended to have significantly lower preoperative and postoperative ASES scores, specifically within the pain domain when compared with males. With regard to the method of internal fixation, patients who underwent capsulolabral plications with suture anchors showed a trend toward greater improvement in ASES scores which did not reach statistical significance. Overall, 89% of athletes were able to return to competition, with 71% returning to their preinjury level of play. In total, 8.5% of athletes failed their initial surgical procedure with continued pain or instability that required revision surgery. CONCLUSIONS: Arthroscopic capsulolabral reconstruction is a reliable treatment for unidirectional posterior shoulder instability in an adolescent population, and does well for athletes involved in a variety of sporting activities. LEVEL OF EVIDENCE: Level IV-case series.

Changes in Cross-sectional Area and Signal Intensity of Healing Anterior Cruciate Ligaments and Grafts in the First 2 Years After Surgery.

BACKGROUND: The quality of a repaired anterior cruciate ligament (ACL) or reconstructed graft is typically quantified in clinical studies by evaluating knee, lower extremity, or patient performance. However, magnetic resonance imaging of the healing ACL or graft may provide a more direct measure of tissue quality (ie, signal intensity) and quantity (ie, cross-sectional area). HYPOTHESES: (1) Average cross-sectional area or signal intensity of a healing ACL after bridge-enhanced ACL repair (BEAR) or a hamstring autograft (ACL reconstruction) will change postoperatively from 3 to 24 months. (2) The average cross-sectional area and signal intensity of the healing ligament or graft will correlate with anatomic features of the knee associated with ACL injury. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Patients with a complete midsubstance ACL tear who were treated with either BEAR (n = 10) or ACL reconstruction (n = 10) underwent magnetic resonance imaging at 3, 6, 12, and 24 months after surgery. Images were analyzed to determine the average cross-sectional area and signal intensity of the ACL or graft at each time point. ACL orientation, stump length, and bony anatomy were also assessed. RESULTS: Mean cross-sectional area of the grafts was 48% to 98% larger than the contralateral intact ACLs at all time points (P < .01). The BEAR ACLs were 23% to 28% greater in cross-sectional area than the contralateral intact ACLs at 3 and 6 months (P < .02) but similar at 12 and 24 months. The BEAR ACLs were similar in sagittal orientation to the contralateral ACLs, while the grafts were 6.5° more vertical (P = .005). For the BEAR ACLs, a bigger notch correlated with a bigger cross-sectional area, while a shorter ACL femoral stump, steeper lateral tibial slope, and shallower medial tibial depth were associated with higher signal intensity (R2 > .40, P < .05). Performance of notchplasty resulted in an increased ACL cross-sectional area after the BEAR procedure (P = .007). No anatomic features were correlated with ACL graft size or signal intensity. CONCLUSION: Hamstring autografts were larger in cross-sectional area and more vertically oriented than the native ACLs at 24 months after surgery. BEAR ACLs had a cross-sectional area, signal intensity, and sagittal orientation similar to the contralateral ACLs at 24 months. The early signal intensity and cross-sectional area of the repaired ACL may be affected by specific anatomic features, including lateral tibial slope and notch width-observations that deserve further study in a larger cohort of patients. REGISTRATION: NCT02292004 (ClinicalTrials.gov identifier).

Bridge-Enhanced Anterior Cruciate Ligament Repair: Two-Year Results of a First-in-Human Study.

BACKGROUND: Bridge-enhanced anterior cruciate ligament repair (BEAR) combines suture repair of the anterior cruciate ligament (ACL) with a specific extracellular matrix scaffold (the BEAR scaffold) that is placed in the gap between the torn ends of the ACL to facilitate ligament healing. PURPOSE/HYPOTHESIS: The purpose of this study was to report the 12- and 24-month outcomes of patients who underwent the BEAR procedure compared with a nonrandomized concurrent control group who underwent ACL reconstruction (ACLR) with an autograft. We hypothesized that the BEAR group would have physical examination findings, patient-reported outcomes, and adverse events that were similar to those of the ACLR group. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Ten patients underwent BEAR, and 10 underwent ACLR with a 4-stranded hamstring autograft. At 24 months, 9 of the 10 BEAR patients and 7 of the 10 ACLR patients completed a study visit. Outcomes reported included International Knee Documentation Committee (IKDC) subjective and objective results, knee anteroposterior (AP) laxity findings via an arthrometer, and functional outcomes. RESULTS: There were no graft or repair failures in the first 24 months after surgery. The IKDC subjective scores in both groups improved significantly from baseline (P < .0001) at 12 and 24 months, to 84.6 ± 17.2 in the ACLR group and to 91.7 ± 11.7 in the BEAR group. An IKDC objective grade of A (normal) was found in 44% of patients in the BEAR group and in 29% of patients in the ACLR group at 24 months; no patients in either group had C (abnormal) or D (severely abnormal) grades. Arthrometer testing demonstrated mean side-to-side differences in AP laxity that were similar in the 2 groups at 24 months (BEAR, 1.94 ± 2.08 mm; ACLR, 3.14 ± 2.66 mm). Functional hop testing results were similar in the 2 groups at 12 and 24 months after surgery. Hamstring strength indices were significantly higher in the BEAR group compared with the ACLR group (P = .0001). CONCLUSION: In this small, first-in-human study, BEAR produced similar outcomes to ACLR with a hamstring autograft. BEAR may result in knee stability and patient-reported outcomes at 2 years sufficient to warrant longer term studies of efficacy in larger groups of patients.