Hierarchically Porous Implants Orchestrating a Physiological Viscoelastic and Piezoelectric Microenvironment for Bone Regeneration.

The extracellular matrix microenvironment of bone tissue comprises several physiological cues. Thus, artificial bone substitute materials with a single cue are insufficient to meet the demands for bone defect repair. Regeneration of critical-size bone defects remains challenging in orthopedic surgery. Intrinsic viscoelastic and piezoelectric cues from collagen fibers play crucial roles in accelerating bone regeneration, but scaffolds or implants providing integrated cues have seldom been reported. In this study, it is aimed to design and prepare hierarchically porous poly(methylmethacrylate)/polyethyleneimine/poly(vinylidenefluoride) composite implants presenting a similar viscoelastic and piezoelectric microenvironment to bone tissue via anti-solvent vapor-induced phase separation. The viscoelastic and piezoelectric cues of the composite implants for human bone marrow mesenchymal stem cell line stimulate and activate Piezo1 proteins associated with mechanotransduction signaling pathways. Cortical and spongy bone exhibit excellent regeneration and integration in models of critical-size bone defects on the knee joint and femur in vivo. This study demonstrates that implants with integrated physiological cues are promising artificial bone substitute materials for regenerating critical-size bone defects.

[Comparison between laparoscopic pyloromyotomy and open pyloromyotomy for infants with congenital hypertrophic pyloric stenosis]

OBJECTIVE: To compare the efficacy of laparoscopic pyloromyotomy with open pyloromyotomy in treatment of congenital hypertrophic pyloric stenosis(CHPS). METHODS: Fifteen patients (age 20%ape;90 days, body weight 2.5 approximate, equals 5.0 kg) with CHPS underwent laparoscopic pyloromyotomy (Group I) and 10 patients (age 26 approximate, equals 90 days, body weight 2.8 approximate, equals 4.5 kg) with CHPS underwent open pyloromyotomy (Group II). Ambulatory 24 hr esophageal pH metry and gastroesophageal mamometry were studied in two groups before and after surgery. RESULTS: All patients presented gastroesophageal reflux (GER) before operation and all reflux parameters were significantly decreased after operation (P<0.01). There was no significant difference between two groups in reflux parameters after surgery. Intragastric pressure (GP) significantly reduced in two groups after operation(3.83+/-1.45)mmHg compared with (2.38+/-0.54)mmHg P<0.01 in Group I,(4.52+/-1.96)mmHg compared with (2.38+/-0.72)mmHg P<0.05 in Guoup II). There was no significant difference in lower esophageal sphincter pressure (LESP), lower esophageal sphincter length (LESL) before and after operation in two groups. The mean operative time for Group I was (32+/-19) mins, which was close to that of Group II after an initial trail. Oral feeding was started 6 h postoperatively in Group I, which was earlier than that in Group II. No technical failures and complications in Group I were encountered. One wound infection and dehiscense was seen in Group II. CLUSION: Laparoscopic pyloromyotomy for infantile hypertrophic pyloric stenosis is safe and feasible, which has lesser complication and similar effect of antireflux as open pyloromyotomy.