Moreno CR, Santschi EM, Janes J, Liu J, Kim DG, Litsky AS. Compression generated by cortical screws in an artificial bone model of an equine medial femoral condylar cyst.
Vet Surg 2022;
51:833-842. [PMID:
35394080 PMCID:
PMC9321887 DOI:
10.1111/vsu.13814]
[Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/11/2022] [Accepted: 03/19/2022] [Indexed: 11/29/2022]
Abstract
Objective
Determine compression generated by lag and neutral screws over 12 h using two bone analogs.
Study design
Experimental study.
Sample population
Bone analogs were made of composite synthetic bone (CSB) or three‐dimensional printed polylactic acid (PLA). Analogs had a 2 mm exterior shell with a 10 mm thick internal layer of open‐cell material.
Methods
Bone analogs were opposed, making a 4‐sided box with open ends. A central channel contained the sensor and the screws passed through it to engage both paired analogs. Four screw/analog conditions were tested: neutral and lag screw with bicortical engagement, neutral and lag screw with unicortical engagement. All screws were tightened to 2 Nm torque and compression values recorded at 0, 0.5, 1, 2, 6, and 12 h (six trials per condition). Medians were compared across groups for statistical significance.
Results
There was no difference in median compression between lag and neutral bicortical screws. For PLA, greater median compression was generated by neutral (median 437 N) and lag (median 379 N) bicortical screws compared to neutral unicortical screws (median 208 N, p < .001); lag bicortical screws generated greater median compression than lag unicortical screws (median 265 N, p = .012). For CSB, lag bicortical screws (median 293 N) generated greater median compression than neutral unicortical screws (median 228 N, p = .008).
Conclusion
Lag and neutral screws generated similar compression. Bicortical screws had higher median compression than unicortical screws in bone analogs.
Clinical significance
Neutral screws generate compression in cancellous bone analogs that can be increased with bicortical bone engagement.
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