Multivariate Logistic Regression Analysis of the Outcomes After Humeral Head Replacement: A Case Series

Background: The aim of our study was to explore the risk factors affecting the treatment of humeral head replacement. Methods: 52 patients with humeral head replacement surgery were enrolled in the study. The information of patients were recorded. The treatment outcomes of humeral head replacement were evaluated by ASES scores. The indicators that may affect humeral head arthroplasty surgery effect were analyzed by univariate analysis and multivariate logistic regression analysis. Results: Univariate analysis showed: the differences of age, time from injury to surgery, time to start exercising after surgery, whether the patient regular follow-up, visual Analogue Scale(VSA), whether with shoulder dislocation, and whether with osteoporosis, were statistically significant (P <0.05). Multivariate Logistic regression analysis showed that age, time from injury to surgery, whether with shoulder dislocation, time to start exercising after surgery, and whether the patient regular follow-up were the influencing factors, but whether with osteoporosis and VSA were not illustrated as a risk factor. Conclusion: Age, time from injury to surgery, time to start exercising after surgery, whether with shoulder dislocation, and whether the patient regular follow-up may be the chief factors affecting humeral head replacement surgery. Trial Registration: This trial was registered at the Research Registry on June 22, 2018(researchregistry3243, https://www.researchregistry.com/browse-the-registry).

Elastomeric pump malfunction resulting in over-infusion of local anesthetic

A 70 year-old female patient presented for a right humeral head replacement. Preoperatively an interscalene catheter was placed and postoperatively connected to an elastomeric pump for continuous infusion at 8 mL/h of Ropivacaine 0.2% with an additional 5 mL patient activated bolus available every 30 min. About 17 h after the elastomeric pump was connected to the catheter, the 550 mL reservoir was found to be empty, indicating the pump’s infusion rate was more than 32 mL/h despite the pump still being set at an infusion rate of 8 mL/h with a possible 5 mL bolus every 30 min. There was no visible damage or leak in the pump system, and the insertion site was dry. The patient denied any changes to the pump settings. She was alert and oriented and denied any signs of local anesthetic toxicity. The catheter was immediately pulled and the manufacturer notified. The manufacturer found a red tab broken inside the patient-controlled bolus remote resulting in the over-infusion. Despite the dependability of elastomeric pumps, healthcare providers must be aware of their possible complications and malfunctions.