Tibial Tuberosity Transposition Fixation with a Locking Plate during Medial Patellar Luxation Surgery: An Ex Vivo Mechanical Study

Abstract

Objectives The purpose of this study was to compare the load at failure, stiffness and mode of failure between three types of tibial tuberosity transposition fixation techniques: (a) pin and figure-8 tension band wire (Pin-TBW), (b) locking plate with pin and a tension band wire (Plate-Pin-TBW) and (c) locking plate with a pin (Plate-Pin). Methods Six pairs of raccoon dog cadaveric tibiae were tested in Phase I Pin-TBW versus Plate-Pin-TBW and seven pairs in Phase II Plate-Pin-TBW versus Plate-Pin. One limb of each pair was randomly assigned to one of two groups for each phase. A tensile force was applied to the patellar ligament until construct failure. Results Pin-TBW (342N ± 54.7N) failed at a lower load than Plate-Pin-TBW (469N ± 77.3N), p = 0.00748, with all Pin-TBW failing by fracture and the majority of Plate-Pin-TBW failing by rupture of patellar ligament. Pin-TBW group Phase I, normalized with Plate-Pin-TBW Phase I, failed at a lower load than Plate-Pin group Phase II, normalized with Plate-Pin-TBW Phase II, p = 0.00467. There was no significant difference in mean load at failure, stiffness or mode at failure between the groups in the Phase II study. Clinical Significance Although ex vivo mechanical testing does not replicate the postoperative live dog or cat, these results demonstrate lower construct strength of the Pin-TBW construct compared with the Plate-Pin construct in the raccoon dog cadaver model.

Biomechanical evaluation of a fixation technique with a modified hemicerclage for tibial tuberosity transposition: an ex vivo cadaveric study

“…The load to failure reported in our study was approximately two times higher than that reported in a similar study performed with tibiae from raccoon dogs, which have similar mean body weights to the specimens used in the present study ( 12 ). The raccoon dog study reported mean weights of 7.1 kg and 6.2 kg.…”

“…Another limitation is the broad range of body weight of the dogs used for the study. We selected small breed dogs because of the clinical significance, which may be considered more relevant in comparison to other similar studies that utilized larger cadavers ( 12 , 18 , 28–30 ). The wide range of tibia size would likely have caused variability in mean stiffness and maximum load at failure, as well as failure modes.…”

“…The proposed technique utilizes a single-length orthopedic wire placed as a modified hemicerclage (MH) in a tension band fashion, without the use of pins through the tuberosity. Similar studies employing quasi-static load-to-failure tests have been conducted, focusing on different fixation methods, however predominantly involving larger breed subjects ( 12 , 18 , 28–30 ). This biomechanical study explicitly focuses on the initial validation of the novel technique’s biomechanical properties compared to well-established techniques and aims to primarily assess the mechanical strength of the fixation method.…”

Evaluation of Surgical Technique and Clinical Results of a Procedure-Specific Fixation Method for Tibial Tuberosity Transposition in Dogs: 37 Cases

“…25,26 A biomechanical study has shown a higher load to tibial tuberosity avulsion or fracture with a Kirschner wire plus locking plate compared to Kirschner wire plus tension band wire. 27 Clinical results of TTA plates or locking plates for TTT have not been published.…”

Influence of Kirschner-Wire Insertion Angle on Construct Biomechanics following Tibial Tuberosity Osteotomy Fixation in Dogs

“…1 3 Multiple methods for fixation of the tibial tuberosity osteotomy have been described in the veterinary literature including lag screw fixation, 4 use of a single Kirschner wire, 5 6 7 double Kirschner wires, 1 2 3 8 9 or locking plate fixation. 10 Prior investigators have proposed that Kirschner wires should be oriented caudoproximally as this has been associated with increased tensile strength, 3 6 9 however, caudodistal angulation is described and routinely performed clinically. 11 One study by Cashmore and colleagues found that the more caudodistally the Kirschner wires were directed, the greater the risk for tibial tuberosity avulsion.…”