A BIOMECHANICAL COMPARISON OF GARDNER-WELLS TONGS AND HALO DEVICE USED FOR CERVICAL-SPINE TRACTION

Summary of Background Data. Unstable cervical spine fractures and dislocations are often reduced by the application of axial traction using a halo or Gardner-Wells tongs. Failure of tong or halo attachment can cause substantial morbidity and usually occurs at the pin-bone interface. Institutions commonly clean and reuse tongs. The effect of tong wear on pullout strength and the strength of the halo used as a traction device have not been documented. Methods. A skull model biomechanically similar to human calvarium was used to compare the axial pullout strengths of four sets of new tongs, three sets of rarely used tongs, and one set of heavily used tongs, as well as a standard four-pin halo. Results. The pullout strength of tongs tightened to the manufacturer's recommended level appeared to decrease with increased use. Measurement of the pin force generated by each set of tongs and of the spring constant of each spring, as well as inspection of the tongs after testing, suggested that the decrease in pullout strength may be partly attributable to spring and/or pin wear. The pullout strength of the halo or of the new or slightly used tongs but not the heavily used tongs exceeded the maximum weight used clinically in cervical spine traction. Conclusion. The data suggest that consideration be given to replacement or recalibration of heavily used tongs.