Robert N Green1, Oliver W Donaldson2, Meilyr Dafydd3, Sam L Evans4, Rohit Kulkarni5. 1. Department of Orthopaedics, Northern Deanery, Newcastle-upon-Tyne, England. Electronic address: nicholasgreen@doctors.org.uk. 2. Yeovil District Hospital, Yeovil, England. 3. Department of Radiology, Welsh Deanery, Cardiff, Wales. 4. School of Engineering, Cardiff University, Cardiff, Wales. 5. Royal Gwent Hospital, Newport, Wales.
Abstract
PURPOSE: To assess the effect of the insertion angle and the angle of applied load on the pullout strength of screw-in suture anchors. METHODS: Screw-in metallic suture anchors were inserted into a 10-lb/cu ft synthetic cancellous bone block at 30°, 45°, 60°, and 90° to the surface. The suture pull angle was then varied in 30° increments between 0° and 180°. Five constructs were tested to failure (anchor pullout) for each combination of angles using a Zwick tensile testing machine (Zwick Roell, Ulm, Germany). RESULTS: There were a total of 25 combinations. The greatest pullout strength was seen with a suture anchor inserted at 90° to the bone block with a pull angle of 90° to the bone (mean, 306 N; standard deviation [SD], 9 N). The weakest pullout strength was seen with a suture anchor inserted at 30° with the angle of pull at 120° (i.e., opposite to the direction of insertion of the anchor) (mean, 97 N; SD, 11 N). A simulated deadman's angle of 45° with an angle of pull of 150° produced a pullout strength of 127 N (SD, 4 N). The pullout strengths for each insertion angle were greatest when the angle of pull was similar to the angle of insertion (P < .0001, repeated-measures analysis of variance). CONCLUSIONS: The angle of applied load to a suture anchor and the insertion angle significantly influence the biomechanical pullout strength of screw-in suture anchors. The insertion angle of the suture anchor should replicate the angle of applied load to ensure the optimum pullout strength. CLINICAL RELEVANCE: The screw-in anchor insertion angle and angle of applied load may have an influence on pullout strength.
PURPOSE: To assess the effect of the insertion angle and the angle of applied load on the pullout strength of screw-in suture anchors. METHODS: Screw-in metallic suture anchors were inserted into a 10-lb/cu ft synthetic cancellous bone block at 30°, 45°, 60°, and 90° to the surface. The suture pull angle was then varied in 30° increments between 0° and 180°. Five constructs were tested to failure (anchor pullout) for each combination of angles using a Zwick tensile testing machine (Zwick Roell, Ulm, Germany). RESULTS: There were a total of 25 combinations. The greatest pullout strength was seen with a suture anchor inserted at 90° to the bone block with a pull angle of 90° to the bone (mean, 306 N; standard deviation [SD], 9 N). The weakest pullout strength was seen with a suture anchor inserted at 30° with the angle of pull at 120° (i.e., opposite to the direction of insertion of the anchor) (mean, 97 N; SD, 11 N). A simulated deadman's angle of 45° with an angle of pull of 150° produced a pullout strength of 127 N (SD, 4 N). The pullout strengths for each insertion angle were greatest when the angle of pull was similar to the angle of insertion (P < .0001, repeated-measures analysis of variance). CONCLUSIONS: The angle of applied load to a suture anchor and the insertion angle significantly influence the biomechanical pullout strength of screw-in suture anchors. The insertion angle of the suture anchor should replicate the angle of applied load to ensure the optimum pullout strength. CLINICAL RELEVANCE: The screw-in anchor insertion angle and angle of applied load may have an influence on pullout strength.
Authors: Dimitris Ntalos; Kay Sellenschloh; Gerd Huber; Daniel Briem; Klaus Püschel; Michael M Morlock; Karl-Heinz Frosch; Florian Fensky; Till Orla Klatte Journal: PLoS One Date: 2019-11-27 Impact factor: 3.240