Clinical Benefit of Hydroxyapatite-Coated Versus Uncoated External Fixation: A Systematic Review

Abstract

Aim : Common complications of external fixators include pin-loosening, infection and loss of reduction/malunion. These are increased with prolonged fixation. The main aim of this systematic review was to investigate HA-coated versus uncoated external fixator and determine benefits in terms of pin loosening, infection and loss of reduction/malunion. Material and Methods : A systematic literature search using PubMed, EMBASE, OVID SP, Cochrane database, ClinicalTrials.gov website and the references of the studies identified was undertaken on 26th August 2014. Comparative trials investigating HA-coated versus uncoated external fixation pins were identified. These were limited using strict eligibility criteria and critically appraised as per the CASP and CONSORT guidelines. Primary outcome measures included pin loosening and infection. Secondary outcome measures included loss of reduction/malunion. Results : Seven studies were identified of which five studies demonstrated a statistically significant reduction in loosening with HA-coated pins. There was insufficient evidence to demonstrate any clinical benefits, such as numbers needed to treat to avoid early removal of pins. Review of the studies included also demonstrated insufficient evidence to determine any significant clinical benefit with regards to infection and malunion. Critical appraisal demonstrated average methodological quality of the studies. Conclusion : HA-coating of external fixator pins improves bone fixation and reduces loosening in patients undergoing prolonged fixation procedures, such as leg-lengthening, but the influence on infection and malunion is not clear. Further large, well-designed randomised controlled trials with observer blinding, standardized pin insertion and pin care investigating clinically relevant pin loosening, infection and malunion are recommended. Patient reported, functional outcome measures should also be considered.