Osteoclast-mediated bioresorption can be an efficient means of incorporating the dissolution of biomaterials in the bone remodeling process. Because of the compositionally and structurally close resemblance of biomaterials with the natural mineral phases of the bone matrix, synthetic carbonate-substituted apatite (CA) is considered as an ideal biomaterial for clinical use. The present study therefore investigated the effects of electrical polarization on the surface characteristics and interactions with human osteoclasts of hydroxyapatite (HA) and CA. Electrical polarization was found to improve the surface wettability of these materials by increasing the surface free energy, and this effect was maintained for 1 month. Analyses of human osteoclast cultures established that CA subjected to a polarization treatment enhanced osteoclast resorption but did not affect the early differentiation phase or the adherent morphology of the osteoclasts as evaluated by staining. These data suggest that the surface characteristics of the CA promoted osteoclast resorption. The results of this work are expected to contribute to the future design of cell-mediated bioresorbable biomaterials capable of resorption by osteoclasts and of serving as a scaffold for bone regeneration.

Surgical correction of spinal deformities is major surgery with extensive manipulation of the spine and neural elements. Persistent postsurgical pain affects the patients` quality of life and can also cause financial burden for families and community. We aimed to investigate the effects of perioperative pregabalin on the incidence of persistent pain after instrumented spinal fusion. Methods:The study design was a randomized, double-blind and placebo-controlled single center clinical trial. Adolescents and children aged 10 -21 years, with a spinal deformity scheduled for pedicle screw instrumentation and fusion were randomized in pregabalin or placebo group. The study subjects received preoperatively and five days after surgery pregabalin 2 mg/kg or placebo twice daily. Duration of follow-up was 2 years. The primary outcomes were cumulative oxycodone consumption during the first 48 postoperative hours and the incidence of persistent postsurgical pain during 2-year follow-up. Results:Out of 77 eligible patients 64 were enrolled in the study with all patients completing 2-year follow-up. Thirty-three patients were randomized into pregabalin group and 31 patients into placebo group. There was no statistically significant difference in the cumulative 48-hour oxycodone consumption between the study groups. The SRS-24 pain domain score showed a significant improvement from a mean value of 3.8 in both groups to 4.3 in the pregabalin and 4.0 in the placebo group during the 2-year FU with no differences between the study groups at any time point (p=0.317). The SRS-24 total scores were similar in the study groups (p=0.678). Back pain on a visual analogue scale improved significantly from preoperative 3 value during the two-year follow-up (p=0.0011) with no significant differences at any time point (preoperative, 6-month, 1 year and 2 year). Conclusions:Perioperative pregabalin does not reduce the postoperative opioid consumption nor the incidence of persistent postsurgical pain among adolescents after instrumented posterior spinal fusion for spinal deformities.

Purpose To determine predictors for postoperative urinary retention in adolescents undergoing posterior spinal fusion for idiopathic scoliosis. Postoperative urinary retention affects almost every third adolescent after spinal fusion for idiopathic scoliosis. There are limited data regarding the risk factors of postoperative urinary retention in this patient group. Methods A retrospective study with prospectively collected urinary retention data from paediatric spine register with 159 consecutive patients (114 females, mean age 15.6 years, range 10–21 years) undergoing pedicle screw instrumentation for adolescent idiopathic scoliosis at a university hospital between May 2010 and April 2020. Postoperative urinary retention was defined as an inability to void after catheter removal and documented residual over 300 mL as confirmed using an ultrasound or by catheterization. Results Postoperative urinary retention was diagnosed in 33% (53 of 159) of the patients during hospital stay. Opioid amount on the day of catheter removal (OR 6.74 [95% CI: 2.47, 18.36], p < 0.001), male gender (OR 2.26 [95% CI: 1.01, 5.05], p = 0.048), and increasing weight (OR 1.04 [95% CI: 1.01, 1.07], p = 0.014) were associated with postoperative urinary retention. Mean opioid consumption on the day of catheter removal was 0.81 mg/kg (95% CI: 0.66, 0.96) in the retention group vs 0.57 mg/kg (95% CI: 0.51, 0.64) in the non-retention group, p < 0.001. Conclusions Higher total opioid consumption, opioid amount on the day of catheter removal, higher weight, and male gender increases the risk of postoperative urinary retention in adolescents with idiopathic scoliosis undergoing posterior spinal fusion.