A synthetic bone insert may protect the lateral cortex and fixation plate following a high tibial osteotomy by reducing the tensile strains

• Published in: Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA Vol. 28; no. 6; pp. 1814 - 1820
• Main Authors: MacDonald, Rachel, Huebner, Kyla, Farr, Jack, Dunning, Cynthia E., Getgood, Alan, Burkhart, Timothy A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2020; Springer Nature B.V
• Subjects: Absorbable Implants; Aged; Aged, 80 and over; Biocompatibility; Bone Plates; Cadaver; Cadavers; Compression; Compressive properties; Compressive Strength; Cortical Bone - physiology; Fixation; Gauges; Humans; Knee; Knee Joint - surgery; Mechanical loading; Medicine; Medicine & Public Health; Middle Aged; Orthopedics; Osteotomy; Osteotomy - instrumentation; Osteotomy - methods; Strain gauges; Surgical equipment; Tensile strain; Tensile Strength; Tibia - surgery; Wedges; Fracture; Stability; Fixation; Osteotomy; Wedge; Strain
• ISSN: 0942-2056; 1433-7347
• DOI: 10.1007/s00167-019-05606-z

Purpose To determine the effectiveness of a synthetic bone insert on improving medial opening wedge high tibial osteotomy integrity in response to post-surgical cyclical loading. Materials and methods A medial opening wedge high tibial osteotomy, secured with a compression fixation plate, was performed on 12 cadaveric knee specimens that were randomised to either: (1) a synthetic insert condition ( n  = 6), in which a 9 mm bio-absorbable wedge was inserted into the gap space; or (2) a plate-only condition ( n  = 6). Uniaxial strain gauges, placed on the lateral cortex and fixation plate, measured the strain response as the specimens were subjected to a staircase cyclical loading protocol; a sinusoidal waveform between 100 and 800 N was applied and increased by increments of 200 N every 5000 cycles until failure. Peak strains at failure were compared between conditions using a one-tailed independent samples t test. Results The strains from the fixation plate were significantly different between the insert and plate only conditions ( p  = 0.02), transitioning from a compressive strain with the wedge (mean [SD] = − 8.6 [− 3.6] µε) to a tensile strain without the wedge (mean [SD] = 12.9 [23] µε). The strains measured at the lateral cortex were also significantly affected by the inclusion of a synthetic bone insert ( p  = 0.016), increasing from − 55.6 (− 54.3) µε when the insert was utilised to 23.7 (55.7) µε when only the plate was used. Conclusions The addition of a synthetic insert limited the tensile strains at the plate and lateral cortex, suggesting that this may protect these regions from fracture during prolonged loading.