Hydroxyapatite-coated pins versus titanium alloy pins in external fixation at the wrist: a controlled cohort study.

BACKGROUND: The purpose of this study was to analyze whether the prevalence of pin-related complications can be reduced by the use of hydroxyapatite (HA)-coated pins in external fixators applied for unstable wrist fractures. METHODS: Forty patients (160 pins) were randomized for standard uniplanar fixator treatment with the use of identically designed pins either composed of titanium-alloy (Ti6Al4V) (n = 20) or coated by HA (n = 20). Each pin site was clinically evaluated with regard to erythema, drainage, pain value, and radiologically assessed concerning loosening at T1 (mean, 9 days), T2 (mean, 43 days), and T3 (mean, 56 days). In case of pin-track complication, the patient was followed continuously. The need for antibiotics or additional surgery was documented. Bone mineral density was analyzed by Dual Energy X-ray Absorptiometry. At fixator removal (T2), the pin-extraction strength was measured by the use of a digital-torque-wrench. RESULTS: Two minor pin-track infections requiring oral antibiotics occurred in the HA-pin group (2.7%) (p > 0.05). The vast majority of clinical pin-site parameters were comparable in both groups. At the end of the fixator therapy, there were 16 loose pins (n(Ti6AL4V-group) = 10; n(HA-group) = 6). The rate of loose pins was correlated to patient's age (p < 0.05) but not to bone mineral density values or the occurrence of pin-site infection. Finally, no significant difference between the two groups was detected with regard to the prevalence of clinical relevant pin-site complications (p = 0.80). CONCLUSIONS: In external fixation of the wrist, the use of HA-coated pins yields no clinical advantages: there is a trend toward a superior pin-bone anchorage, but a tendency of increased susceptibility for minor pin-track infections.

Clinical benefit of hydroxyapatite-coated pins compared with stainless steel pins in external fixation at the wrist: a randomised prospective study.

BACKGROUND: The purpose of this study was to determine the clinical benefit of hydroxyapatite (HA)-coated pins compared with standard stainless steel pins in external fixators applied for unstable fractures of the distal radius. METHODS: A total of 40 patients (160 pins) with unstable wrist fractures were randomised for uniplanar fixator treatment with the use of identically designed, commercially available pins either composed of stainless steel (steel group) (n = 20) or coated by hydroxyapatite (HA group) (n = 20). Each pin site was clinically evaluated concerning erythema and grade of drainage as well as pain intensity (numeric rating scale (NRS) 0­10) and, additionally, radiological assessment was performed concerning pin-loosening/infection as well as fracture healing at T1 (Ø18 days), T2 (Ø44 days) and T3 (Ø65 days). In case of pintrack complication, the patient was followed continuously. The need for intensified pin-site care, oral or intravenous antibiotic medication, re-admission for additional surgery and premature fixator removal was documented. Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry. At fixator removal (T2), the pin-extraction strength was measured by the use of an electronic torque wrench. RESULTS: Two pin-track infections requiring daily pin-site care and oral antibiotics occurred in the HA group (2.6%) compared with four in the steel group (5.3%) (p = 0.601) and although a trend towards a superior performance of HA pins was detectable, the majority of clinical pin-site-parameters were comparable in both groups. At the end of the fixator therapy, the HA group showed a non-significant lower rate of loose pins (n(steel group) = 9; n(HA group) = 6; p = 0.864) and both hydroxyapatite-coated pins showed at the radius a significantly stronger pin-bone bonding measured by the torque wrench (p(proximal radius pin) = 0.007; p(distal radius pin) = 0.031). Except for elderly patients of the steel group (p = 0.018), all demographic-, health- and injury-related data including BMD were not correlated to any type of pin-site complication in both groups (p > 0.05). Since all fracture healed uneventfully without any type of additional surgery, the number of patients suffering clinically relevant pin-related complications showed no significant difference between both groups (p = 0.707). CONCLUSIONS: The use of HA-coated pins compared with standard stainless-steel pins in external fixation for unstable wrist fractures yields only a trend towards a superior clinical outcome.