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.
This experimental study presents baseline data on the differences in the primary stability of bone-implant constructs used in SCO. The data in this study can be used as reference for future testing of SCO techniques. Furthermore, it is recommended that based on the differences found, the early postoperative rehabilitation protocol is tailored to the stability and stiffness of the fixation method used.
Between January 2005 and October 2008, 60 patients were treated with medial closed-wedge osteotomy of the distal femur (since 11/2006 only with biplanar osteotomy technique) at the Department of Trauma and Reconstructive Surgery, Diakoniekrankenhaus Henriettenstiftung Hannover, Germany. The average wedge size was 7.6 mm (4-13 mm). The mean age was 39.7 years (17-79 years). The patients had had 2.3 previous surgeries. The mean follow- up was 21 months (3-45 months). Freiling D, et al. Biplanare Osteotomie bei unikompartimentaler lateraler Kniegelenkarthrose Flexion was 126 degrees (95-140 degrees) preoperatively, and 128 degrees (105-140 degrees) postoperatively. 25 patients had at least 5 degrees extension deficit (5-15 degrees) before surgery, whereas ten patient did not reach the full extension at follow-up examination. The Tegner Activity Score increased from 2.8 (1-4) preoperatively to 5.6 (2-9) postoperatively, in IKDC (International Knee Documentation Committee) Score, 18 patients reached grade A, 27 grade B, nine grade C, and six grade D. The visual analog scale (VAS) score decreased from 6.8 (8-2) preoperatively to 3.1 (0-7) postoperatively. Seven patients had revision surgery (three times delayed union/nonunion of the osteotomy, one superficial and one deep infection, one hematoma, one fracture [proximal of the internal plate fixator] after a fall).
In this article, patient selection, planning, surgical techniques, stability of fixation, and bone healing are discussed. Varus supracondylar osteotomy is a viable treatment option for a well-defined patient group suffering from valgus malalignment and lateral compartment osteoarthritis, and in addition may be considered in ligamentous imbalance and lateral patellofemoral maltracking.
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