Abstract
Introduction: Deterioration of bone-pin interface, causing pin loosening and infection, is a major cause of postoperative complications following external fixation. This paper presents the results obtained using hydroxyapatite (HA)-coated pins in various bone types, such as osteoporotic bone.
Materials And Methods; In an animal study comparing HA-coated and standard pins, pin insertion and extraction torque were measured. Subsequently, a clinical study compared insertion, extraction torque and pin-tract infection rate of standard and HA-coated pins implanted in healthy and osteoporotic bone.
Results: hi the animal study, mean final insertion torque was 4360±1050Nmm in the standard group and 3420 ± 676 Nmm in the HA-coated group. Mean extraction torque was 253 ± 175 Nmm in the standard group and 3360 ± 1260 Nmm in the HA-coated group (p = 0.002). In the clinical study on healthy bone, the mean insertion torque was 4130 ± 2160 Nmm in the standard group and 3440 ± 1930 Nmm in the HA-coated group (p = 0.03). The mean extraction torque was 1470 ± 1700 Nmm in the standard group and 5130 ± 2300 Nmm in the HA-coated group (p < 0.001). There were 33 pin-tract infections in the standard group and 20 pin-tract infections in the HA-coated group (p < 0.05, power 0.9). The standard pin group had a mean extraction torque of 730 (0–5500) Nmm in the infected pin-tracks and 2110 (0–7000) Nmm in the uninfected pin-tracts (p < 0.0001). The HA-coated group had a mean extraction torque of 5310 (1000–8000) Nmm in the infected pin-tracts and 5080 (0–8000) Nmm in the uninfected pin tracts (NS). In the clinical study on osteoporotic bone, mean final insertion torque was 461 ± 254 Nmm in the standard group and 331 ± 175Nmm in the HA-coated group (p = 0.01). Mean extraction torque was 191 ± 154 Nmm in the standard group and 600 ± 214 Nmm in the HA-coated group (p < 0.0005). Pin infection rate was greater in the standard group (p < 0.05).
Conclusion: There was no deterioration of the bone-pin interface strength (measured by torque resistance at the time of pin extraction) with HA-coated pins. The improved strength of fixation of the HA-coated pins was associated with a lower incidence of pin-tract infection.
The abstracts were prepared by editorial secretary, Mrs K. Papastefanou. Correspondence should be addressed to Professor K.N. Malizos, Department of Orthopaedic Surgery, School of Medicine, University of Thessalia, Larissa, 41222 GREECE
