Primary stability of four different implants for opening wedge high tibial osteotomy

Abstract

Since a significant number of implant failures have been reported in association with the procedure of open wedge valgus high tibial osteotomy, the initial biomechanical stability of different fixation devices was investigated in this study. Fifteen third generation Sawbones composite tibiae were used as a model. Four different plates were tested: a short spacer plate (OWO) (n = 4), a short spacer plate with multi-directional locking bolts (MSO) (n = 5), a prototype version of a long spacer plate with multi-directional locking bolts (MSOnew) (n = 2), and a long medial tibia plate fixator with locking bolts (MPF) (n = 4). All opening wedge osteotomies were performed by the same surgeon (PL) in a standardized fashion. Axial compression of the tibiae was performed using a materials testing machine under standardized alignment of the loading axis. Single load to failure tests as well as load-controlled cyclical failure tests were performed. The required force and cycles to failure were recorded. Osteotomy gap motion was measured using linear displacement transducers. Residual stability after failure of the opposite lateral cortex was analysed. Failure occurred at the lateral cortex bone-bride in all tested implants. The rigid long plate fixator (MPF) resisted the greatest amount of force (2,881 N) in the single load to failure tests. In the cyclical load-to-failure tests, the constructs with MPF resisted more than twice the amount of loading cycles when compared to the short spacer plates. The osteotomy gap motion was smallest in the MPF, with a reduction of the displacements of up to 65, 66 and 88%, when compared to OWO, MSO and MSOnew, respectively. The highest residual stability after failure of the lateral cortex was observed in MPF as well. The results suggest that the implant design strongly influences the primary stability of medial opening wedge tibial osteotomy. A rigid long plate fixator with angle-stable locking bolts yields the best results.

Medial Open Wedge High Tibial Osteotomy: Can Delayed or Nonunion Be Predicted?

“…Furthermore, it has been suggested that instability resulting from a fracture of the lateral cortical hinge could lead to nonunion. Mechanical studies have shown that when the lateral tibial cortex is fractured, angle-stable implants provide superior stability compared with nonangle-stable implants, eg, the Puddu plate [1,14,19]. The present study shows that for open wedge HTO fixed using an angle-stable implant, fracture of the lateral cortical hinge is not a risk factor for developing nonunion.…”

“…Factors that can lead to problems in bone healing are loss of correction resulting from hardware failure [4,16,20] and lateral cortical hinge fracture [1,19,22]. In the past decade, new angle-stable fixation implants have made the medial open wedge HTO technique more popular as a result of the higher loading capacity and the high residual stability after failure of the lateral cortex [1].…”

“…In the past decade, new angle-stable fixation implants have made the medial open wedge HTO technique more popular as a result of the higher loading capacity and the high residual stability after failure of the lateral cortex [1]. Clinical results for the angle-stable implants have shown lower rates for loss of correction [8,16,17].…”

Results of high tibial osteotomy: review of the literature

“…Agneskirchner et al [2] compared four different plates: (1) short spacer plate, (2) short spacer plate with multi-directional locking screws, (3) long spacer plate with multi-directional locking screws and (4) long medial tibia plate fixator with locking screws. They stated that a rigid long plate fixator with angle stable locking screws yields the best results.…”

Open wedge re-correction high tibial osteotomy in an elderly patient with a varus angulated non-united dome-shaped high tibial osteotomy

“…By using the TomoFix™ plate, a fixation without cancellous bone transplantation has become possible (Lobenhoffer and Agneskirchner, 2003;Staubli et al, 2003). Biomechanical investigations in sawbone models showed a high primary stability with a limit of 1 606 N in axial load (Agneskirchner et al, 2006). In our case, a biplanar osteotomy after the failed dome-shaped HTO was not possible due to the non-union in the dome-shaped osteotomy.…”