CCL19 and CCL21 are chemokines involved in the trafficking of immune cells, particularly within the lymphatic system, through activation of CCR7. Concurrent expression of PSGL-1 and CCR7 in naive T-cells enhances recruitment of these cells to secondary lymphoid organs by CCL19 and CCL21. Here the solution structure of CCL19 is reported. It contains a canonical chemokine domain. Chemical shift mapping shows the N-termini of PSGL-1 and CCR7 have overlapping binding sites for CCL19 and binding is competitive. Implications for the mechanism of PSGL-1’s enhancement of resting T-cell recruitment are discussed.
Background: Previous retrospective research found that the presence or absence of bridging callus within 4 months postoperatively discriminated accurately between eventual union and nonunion of fractures of the tibial shaft. However, there remains no consensus regarding early prognostication of long bone nonunion. We prospectively assessed the accuracy and reliability of the presence of any bridging callus within 4 months in a cohort that was expanded to include both tibial and femoral shaft fractures. Methods: We identified 194 consecutive fractures of the shaft of the tibia (OTA/AO type 42-A, B, or C) and femur (OTA/AO type 32-A, B, or C) that were treated with intramedullary nailing. Exclusions for inadequate follow-up (55), extended delay prior to nailing (10), and skeletal immaturity (3) resulted in a study population of 126 fractures (56 tibiae and 70 femora) in 115 patients. Digital radiographs made between 3 and 4 months postoperatively were independently assessed by 3 orthopaedic traumatologists. The accuracy of assessment of the presence of any bridging callus, bicortical bridging, and tricortical bridging to predict union or nonunion was assessed with chi-square analysis and by interobserver reliability (kappa statistic). Results: The nonunion rate was 4% (5 of 126 fractures). The presence of any bridging callus by 4 months accurately predicted union (121 of 122 fractures) and its absence predicted nonunion (4 of 4 fractures). There was 1 incorrect prediction of union for a fracture that failed to unite (p < 0.001). Bicortical or greater bridging predicted union when present (116 of 116 fractures) and nonunion when absent (5 of 10 fractures), incorrectly predicting that 5 healing fractures would go on to nonunion (p < 0.001). Tricortical or greater bridging predicted union when present (103 of 103 fractures) and nonunion when absent (5 of 23 fractures), incorrectly predicting that 18 healing fractures would go on to nonunion (p < 0.001). Interobserver reliability was calculated for any bridging (kappa value, 0.91), bicortical bridging (kappa value, 0.79), tricortical bridging (kappa value, 0.71), and the exact number of cortices bridged (kappa value, 0.67). Conclusions: The presence of any bridging callus within 4 months accurately predicts the final healing outcome for tibial and femoral shaft fractures treated with intramedullary nailing. This criterion is simple and reliable, and only standard radiographs are needed to make the determination. Basing the prognosis on the bridging of additional cortices risks overestimation of the nonunion rate and is associated with relatively poor reliability.
Objectives: To assess the relationship between the distal nail target and postoperative alignment for distal tibia fractures treated with intramedullary nailing. Design: Retrospective cohort study. Setting: A single level 1 trauma center. Patients/Participants: One hundred thirty distal tibia fractures treated with intramedullary nailing over a 10-year period. Main Outcome Measurements: Malalignment >5 degrees. Results: Thirty-eight cases (29.2%) of malalignment >5 degrees included valgus (19 cases, 14.6%), procurvatum (13 cases, 10.0%), recurvatum (1 case, 0.8%), and combined valgus with procurvatum (5 cases, 3.8%). Medially directed nails demonstrated relative valgus (mean lateral distal tibia angle 86.4 vs. 89.4 degrees, P < 0.01) and more frequent coronal malalignment (24 of 78, 30.8% vs. 0 of 52, 0%, P < 0.01). Anteriorly directed nails demonstrated relative procurvatum (mean anterior distal tibia angle 82.8 vs. 80.9 degrees, P < 0.01) and more frequent sagittal malalignment (15 of 78, 19.2% vs. 3 of 52, 5.8%, P = 0.03). Malalignment was less common for nails targeting the central or slightly posterolateral plafond (0 of 30, 0% vs. 38 of 100, 38%), P < 0.01. Multivariate analysis demonstrated the distal nail target (P = 0.03), fracture within 5 cm of the plafond (P = 0.01), as well as night and weekend surgery (P = 0.03) were all independently associated with malalignment. Conclusions: Alignment of distal tibia fractures is sensitive to both injury and treatment factors. Nails should be targeted centrally or slightly posterolaterally to minimize malalignment. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Level II, prospective comparative investigation.
Background: There is a problem with opioid use in the United States. The aim of this research was to identify techniques to decrease opioid use in a specific patient population. Is perioperative peripheral nerve block (PNB) for tibial plateau fractures associated with postoperative opioid prescription, inpatient length of stay, and readmission? Methods: This was a retrospective secondary data analysis of patients between the ages of 18 and 65 years with operative tibial plateau fractures from 2006 to 2015 at a level-I trauma center. Exclusion criteria included preinjury opioid use or history of opioid dependence, an American Society of Anesthesiologists (ASA) class of ≥3, renal or lower-extremity neurological impairment, and/or rheumatoid arthritis. Three hundred and fifteen operative tibial plateau fractures were identified and, following application of our exclusion criteria, the final sample size was 216. The patients were classified as receiving a single-shot PNB versus no PNB. The main outcome measurements included total inpatient and long-term opioid use, hospital length of stay, and early follow-up, which were compared in both groups. Results: There was less total opioid use on the day of surgery (p = 0.044, t = 2.028, mean difference = 27.109 mg, 95% confidence interval [CI] [0.766 to 53.452], degrees of freedom [df] = 1) and a decrease in hospital length of stay by 2.8 days in the single-shot PNB group (p = 0.003, t = 2.990, mean difference = 2.812 days, 95% CI [0.952 to 4.672]) compared with the no-PNB group. Conclusions: Single-shot PNB may be an effective method for decreasing day-of-surgery opioid use and hospital length of stay for patients undergoing tibial plateau fracture repair compared with no PNB. Single-shot PNB did not impact readmission or long-term opioid usage compared with no PNB for tibial plateau fracture repair. Rebound pain needs to be controlled for on postoperative day 1.
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