Severe injury-induced osteoporosis and skeletal muscle mineralization: Are these related complications?

Severely injured patients are beleaguered by complications during convalescence, such as dysregulated biomineralization. Paradoxically, severely injured patients experience the loss of bone (osteoporosis), resulting in diminished skeletal integrity and increased risk of fragility fractures; yet they also accrue mineralization in soft tissues, resulting in complications such as heterotopic ossification (HO). The pathophysiology leading to dysregulated biomineralization in severely injured patients is not well defined. It has been postulated that these pathologies are linked, such that mineralization is "transferred" from the bone to soft tissue compartments. The goal of this study was to determine if severe injury-induced osteoporosis and soft tissue calcification are temporally coincident following injury. Using a murine model of combined burn and skeletal muscle injury to model severe injury, it was determined that mice developed significant progressive bone loss, detectable as early as 3 days post injury, and marked soft tissue mineralization by 7 days after injury. The observed temporal concordance between the development of severe injury-induced osteoporosis and soft tissue mineralization indicates the plausibility that these complications share a common pathophysiology, though further experiments are required.

Propranolol Reverses Impaired Fracture Healing Response Observed With Selective Serotonin Reuptake Inhibitor Treatment

Selective serotonin reuptake inhibitors (SSRIs) are one of the most commonly prescribed antidepressants worldwide and recent data show significant impairment of fracture healing after treatment with the SSRI fluoxetine in mice. Here, we provide evidence that the negative effects of SSRIs can be overcome by administration of the beta-blocker propranolol at the time of fracture. First, in vitro experiments established that propranolol does not affect osteogenic differentiation. We then used a murine model of intramembranous ossification to study the potential rescue effect of propranolol on SSRI-induced impaired fracture healing. Micro-CT analysis revealed that fluoxetine treatment resulted in a smaller bony regenerate and that this decrease in bone formation can be overcome by co-treatment with propranolol. We then tested this in a clinically relevant model of endochondral ossification. Fluoxetine-treated mice with a femur fracture were treated with propranolol initiated at the time of fracture, and a battery of analyses demonstrated a reversal of the detrimental effect of fluoxetine on fracture healing in response to propranolol treatment. These experiments show for the first time to our knowledge that the negative effects of SSRIs on fracture healing can be overcome by co-treatment with a beta-blocker. © 2019 American Society for Bone and Mineral Research.

Efficacy of liposomal bupivacaine in shoulder surgery: a systematic review and meta-analysis

HYPOTHESIS

The aim of this meta-analysis was to compare the safety, efficacy, and opioid-sparing effect of liposomal bupivacaine (LB) vs. nonliposomal local anesthetic agents (NLAs) for postoperative analgesia after shoulder surgery.

METHODS

A systematic literature review of randomized controlled clinical studies comparing the efficacy of LB with NLAs in shoulder surgery was conducted. Seven level I and II studies were included in the meta-analysis, and shoulder surgical procedures included arthroscopic rotator cuff repair and shoulder arthroplasty. Bias was assessed using The Cochrane Collaboration's tool. The primary outcome measures were visual analog scale pain scores and opioid consumption 24 and 48 hours after shoulder surgery. Subgroup analysis was performed for the method of LB administration (interscalene nerve block vs. local infiltration).

RESULTS

A total of 7 studies (535 patients) were included in the final meta-analysis comparing LB (n = 260) with NLAs (n = 275). No significant difference was found between the LB and NLA groups in terms of visual analog scale pain scores at 24 hours (95% confidence interval, -1.02 to 0.84; P = .86) and 48 hours (95% confidence interval, -0.53 to 0.71; P = .78). Both groups had comparable opioid consumption at both 24 hours (P = .43) and 48 hours (P = .78) postoperatively and with respect to length of stay (P = .87) and adverse events (P = .97). Subgroup analysis demonstrated comparable efficacy irrespective of the method of administration of LB.

CONCLUSION

LB is comparable to NLAs with respect to pain relief, the opioid-sparing effect, and adverse effects in the first 48 hours after arthroscopic rotator cuff repair and total shoulder arthroplasty.