Primary or secondary wound healing of the pin sites after removal of the external fixator: study protocol for a prospective, randomized controlled, monocenter trial

BACKGROUND: Temporary fixation with an external fixator is used for numerous indications in orthopedic trauma surgery. It is unclear whether primary wound healing or secondary open-wound healing after removal of the external fixator should be advocated for the pin site. This study compares primary wound closure with secondary wound healing for the pin site. The primary aim is to compare pin-site infection rates. The secondary aim is to compare time to wound healing and esthetic outcome. The hypothesis was that primary wound closure does not lead to more infections than secondary wound healing. METHODS AND DESIGN: This is a prospective, randomized controlled, blinded, monocenter study based on a non-inferiority design. To obtain an equal patient population and groups, all pin-entry sites of the patients are treated alternately at the time of removal of the external fixator with primary wound closure and secondary wound healing. Patients are randomized according to whether the proximal pin-entry site is treated with wound closure or by secondary open-wound healing, from which the further sequence develops. The pre- and postoperative protocol is standardized for all pin-entry sites. A photo documentation of the pin-entry sites takes place 2 and 52 weeks postoperatively during the routine clinical follow-up visits. Further controls take place at 6, 12 and 26 weeks after pin removal. The primary outcome was to demonstrate the non-inferiority of primary wound closure compared to secondary wound healing in terms of postoperative wound infections according to the Center of Disease Control and Prevention (CDC) definitions. The secondary outcomes are time to complete wound healing (days) and esthetical outcome (subjective preference of patients and Vancouver Scar Scale score). DISCUSSION: This study aims to answer how to deal with the pin site after removal of the external fixator. To date, no routine and generally accepted protocol exists for the management of pin sites after removal of the external fixator. This prospective, randomized controlled, blinded monocenter trial should determine whether primary wound closure or secondary wound healing should be advocated after removal of the external fixator. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT03842956. Registered retrospectively on 13 February 2019.