Effect of Osteotomy Position and Tibial Plateau Rotation on the Tensile Force Required for Failure of the Canine Quadriceps Mechanism

Abstract

The overwhelming mode of failure of the quadriceps mechanism was by tibial tuberosity fracture, thus this was the weakest part of the construct. Reducing the tibial tuberosity width and rotation of the tibial plateau segment below the patella tendon insertion decreased the force required for tibial tuberosity fracture. These results support the idea of a safe point with the tibial plateau segment providing buttress to the tibial tuberosity.

Modified cranial closing wedge ostectomy in 25 dogs

“…In these cases, the surgeon strove for higher TPA target to mitigate the CWL because of concern about the consequent change in stifle joint dynamics. In previous studies, owners of dogs with post‐TPLO TPA < 14 ° perceived positive return to function, and ground reaction forces did not differ among dogs with postoperative TPA between 0 ° and 14 ° . We attribute the largest discrepancy between TPA target (12 °) and TPA postop (20 °; Figure ) in the current study to an intraoperative error rather than to a planning error or a TLA shift (7 °).…”

“…Rotation of the tibial plateau via TPLO beyond the insertion of the patellar tendon increases the risk of tibial tuberosity fracture by diminishing its caudal buttress. 19 Under rotation of the tibial plateau or combined TPLO/CCWO has been proposed to palliate this limitation but results in variable clinical outcomes and high complication rates. 6,20 No implant failure or fractures were observed on follow-up radiographs 8 weeks after the mCCWO plan, prompting our consideration of this procedure as a low-risk option for correction of eTPA.…”

Factors associated with early tibial tuberosity fracture after tibial plateau leveling osteotomy

“…The results of our study support the hypothesis that narrower tibial tuberosities post‐TPLO surgery are more likely to fracture. The finding that tibial tuberosities that are narrower in the sagittal plane are more likely to fracture supports findings from previous studies . In our study we found a significant difference in the calculated ratios of length and width between our fracture and nonfracture groups, meaning that tibial tuberosities that fractured had a taller and thinner shape than those that did not fracture.…”

“…We theorize that the maximum tension from the quadriceps mechanism is experienced by the bone at or immediately distal to the insertion of the PL. As demonstrated by Hamilton et al, the tibial tuberosity is the weakest point of the quadriceps mechanism construct and thus most likely to fail. We recommend planning an osteotomy such that the tuberosity is broadest at the base of the osteotomy and tapers to a narrowest point proximal to the insertion of the PL to help prevent postoperative tuberosity fracture.…”

“…An observation from one study suggested that a tuberosity with a 10‐mm craniocaudal width is less likely to fracture compared with those that are more narrow but did not make recommendations that were applicable for a variety of patient sizes and body weights . One ex vivo mechanical modeling study provided evidence that the tensile forces required for failure of the quadriceps mechanism as evidenced by TTF decreased with decreasing tibial tuberosity width, further highlighting the requirement for guidelines defining optimal tibial tuberosity width …”