The most characteristic features of the Lyme disease pathogens, the Borrelia burgdorferi sensu lato (s.l.) group, are their ability to invade tissues and to circumvent the immune defenses of the host for extended periods of time, despite elevated levels of borrelia-specific antibodies in serum and other body fluids. Our aim in the present study was to determine whether B. burgdorferi is able to interfere with complement (C) at the level of C3 by accelerating C3b inactivation and thus to inhibit the amplification of the C cascade. Strains belonging to different genospecies (Borrelia garinii, B. burgdorferi sensu stricto, and Borrelia afzelii) were compared for their sensitivities to normal human serum and abilities to promote factor I-mediated C3b degradation. B. burgdorferi sensu stricto and B. afzelii strains were found to be serum resistant. When the spirochetes were incubated with radiolabeled C3b, factor I-mediated degradation of C3b was observed in the presence of C-resistant B. afzelii (n ‫؍‬ 3) and B. burgdorferi sensu stricto (n ‫؍‬ 1) strains but not in the presence of C-sensitive B. garinii (n ‫؍‬ 7) strains or control bacteria (Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis). Immunoblotting and radioligand binding analyses showed that the C-resistant strains had the capacity to acquire the C inhibitors factor H and factor H-like protein 1 (FHL-1) from growth medium and human serum. A novel surface protein with an apparent molecular mass of 35 kDa was found to preferentially bind to the N terminus region of factor H. Thus, the serum-resistant B. burgdorferi s.l. strains can circumvent C attack by binding the C inhibitors factor H and FHL-1 to their surfaces and promoting factor I-mediated C3b degradation.

IMPORTANCE Humeral shaft fractures traditionally have been treated nonsurgically, but there has been a steady increase in the rate of surgery over the past 2 decades without high-quality evidence to justify the trend.OBJECTIVE To compare the effectiveness of surgical treatment with open reduction and internal plate fixation to nonsurgical treatment with functional bracing in the treatment of closed humeral shaft fractures. DESIGN, SETTING, AND PARTICIPANTS Randomized clinical trial conducted at 2 university hospital trauma centers in Finland, enrollment between November 2012 and January 2018 with a final follow-up of January 2019. A total of 82 adult patients with closed, unilateral, displaced humeral shaft fracture met criteria for inclusion. Patients were excluded if they had cognitive disabilities preventing them from following the protocol or had multimorbidity or multiple trauma. INTERVENTIONS Patients were randomly assigned to surgical treatment with open reduction and internal plate fixation (n = 38) or to nonsurgical treatment with functional bracing (n = 44). MAIN OUTCOME AND MEASUREThe primary outcome was Disabilities of Arm, Shoulder and Hand (DASH) score at 12 months (range, 0 to 100 points, 0 denotes no disability and 100 extreme disability; minimal clinically important difference, 10 points). RESULTS Among 82 patients who were randomized (mean age, 48.9 years; 38 women [46%]; 44 men [54%]), 78 (95%) completed the trial. Thirteen (30%) of the patients assigned to functional bracing underwent surgery during the 12-month follow-up period to promote healing of the fracture. At 12 months, the mean DASH score was 8.9 (95% CI, 4.2 to 13.6) in the surgery group and 12.0 (95% CI, 7.7 to 16.4) in the bracing group (between-group difference, −3.1 points; 95% CI, −9.6 to 3.3; P = .34). Eleven patients (25%) allocated to functional bracing developed fracture nonunion. Three patients (8%) allocated to surgery developed a temporary radial nerve palsy.CONCLUSIONS AND RELEVANCE Among patients with closed humeral shaft fracture, internal fixation surgery, compared with nonoperative functional bracing, did not significantly improve functional outcomes at 12 months. However, the substantial amount of treatment crossover from nonoperative to surgical treatment should be considered when interpreting the trial results.

IMPORTANCEExisting evidence indicates that surgery fails to provide superior functional outcome over nonoperative care in patients with a closed humeral shaft fracture. However, up to one-third of patients treated nonoperatively may require secondary surgery.OBJECTIVE To compare the 2-year outcomes of patients who required secondary surgery with the outcomes of patients with successful initial treatment. DESIGN, SETTING, AND PARTICIPANTSThis 2-year follow-up of the Finnish Shaft of the Humerus (FISH) randomized clinical trial comparing surgery with nonoperative treatment (functional brace) was completed in January 2020. Enrollment in the original trial was between November 2012 and January 2018 at 2 university hospital trauma centers in Finland. A total of 321 adult patients with closed, displaced humeral shaft fracture were assessed for eligibility. After excluding patients with cognitive disabilities, multimorbidity, or multiple trauma and those refusing randomization, 82 patients were randomized.INTERVENTIONS Interventions were surgery with plate fixation (n = 38; initial surgery group) or functional bracing (n = 44); the latter group was divided into the successful fracture healing group (n = 30; bracing group) and the secondary surgery group (n = 14) with fracture healing problems. MAIN OUTCOMES AND MEASURESThe primary outcome was Disabilities of Arm, Shoulder and Hand (DASH) score at 2 years (range, 0 to 100 points; 0 denotes no disability, 100 extreme disability; minimal clinically important difference, 10 points). RESULTSOf 82 randomized patients, 38 (46%) were female. The mean (SD) age was 48.9 (17.1) years. A total of 74 patients (90%) completed the 2-year follow-up. At 2 years, the mean DASH score was 6.8 (95% CI, 2.3 to 11.4) in the initial surgery group, 6.0 (95% CI, 1.0 to 11.0) in the bracing group, and 17.5 (95% CI, 10.5 to 24.5) in the secondary surgery group. The between-group difference was −10.7 points (95% CI, −19.1 to −2.3; P = .01) between the initial and secondary surgery groups and −11.5 points (95% CI, −20.1 to −2.9; P = .009) between the bracing group and secondary surgery group.CONCLUSIONS AND RELEVANCE Patients contemplating treatment for closed humeral shaft fracture should be informed that two-thirds of patients treated with functional bracing may heal successfully while one-third may experience fracture healing problems that require secondary surgery and lead to inferior functional outcomes 2 years after the injury.