Pin-tract infections are a common problem in orthopaedic surgery, which limits the time an external fixator or Taylor spatial frame can be applied to a patient. The purpose of our study is to evaluate the ability of a novel implant surface coating — cationic steroid antibiotic (CSA)-44 — to delay or prevent the onset of these infections. This coating mimics endogenous antimicrobial peptides of the innate immune system and has been shown to effectively eradicate biofilms as well as prevent infection and stimulate healing of open, contaminated fractures. Surgeries were performed on 20 animals (outbred; Sprague-Dawley strain rats). Each animal received both CSA-coated and standard-of-care titanium pins, with pins randomized to the fifth or sixth vertebrae prior to surgeries. Animals were also randomized to either “Imaging” (imaging analysis) or “Infection” (microbiological analysis) cohorts. Surgeons were blinded to pin types and analyses cohorts. Digital images of pin sites were collected weekly over 12 weeks, and then graded by two orthopaedic surgery residents according to an established Likert scale. Graders were blinded to animal numbers, pin types, and timepoints (Figure 1). For the infection analysis cohort, four specimens per site were subjected to microbiological analysis from each site (i.e. pin, superficial skin swab, deep skin swab, sonicated bone). Each specimen was processed on three different microbiological plates (i.e. BAP, CAN, MAC) using standardized techniques. Imaging analysis was performed by dissecting vertebrae Introduction
Methods
Optimal surgical management of proximal humeral fractures remains controversial. We report our experience and the study on our surgical technique for proximal humeral fractures and fracture-dislocations using locking plates in conjunction with calcium sulphate augmentation and tuberosity repair using high strength sutures. We used the extended deltoid-splitting approach for fracture patterns involving displacement of both lesser and greater tuberosities and for fracture-dislocations. We retrospectively analysed 22 proximal humeral fractures in 21 patients. 10 were male and 11 female with an average age of 64.6 years (Range 37 to 77). Average follow-up was 24 months. Fractures were classified according to Neer and Hertel systems. Pre-operative radiographs and CT scans in three and four-part fractures were done to assess the displacement and medial calcar length for predicting the humeral head vascularity. According to the Neer classification, there were 5 two-part, 6 three-part, 5 four-part fractures and 6 fracture-dislocations (2 anterior and 4 posterior). Results were assessed clinically with DASH scores, modified Constant & Murley scores and serial post-operative radiographs. The mean DASH score was 16.18 and modified Constant & Murley score was 64.04 at the last follow-up. 18 out of 22 cases achieved good clinical outcome. All the fractures united with no evidence of infection, failure of fixation, malunion, tuberosity failure, avascular necrosis or adverse reaction to calcium sulphate bone substitute. There was no evidence of axillary nerve injury. The CaSO4 bone substitute was replaced by normal appearing trabecular bone texture at an average of 6 months in all patients.
