Fixator-assisted Technique Enables Less Invasive Plate Osteosynthesis in Medial Opening-wedge High Tibial Osteotomy: A Novel Technique

Abstract

Background: Opening-wedge high tibial osteotomy is a well-established procedure in the management of medial osteoarthritis of the knee and correction of proximal tibia vara. Recently, surgical approaches using less invasive plate osteosynthesis have been used with the goal of minimizing complications from more extensive soft tissue exposures. However, to our knowledge, less invasive fixator-assisted plate osteosynthesis has not been tested in the setting of opening-wedge high tibial osteotomy.

Questions/purposes: The purposes of this study were (1) to assess the complications associated with use of a fixator-assisted less invasive plate osteosynthesis technique to stabilize an opening-wedge high tibial osteotomy in the treatment of proximal tibial vara; and (2) to evaluate the ability of this technique to achieve correction of the proximal tibial deformity and achieve osseous union.

Methods: From June 2011 to June 2013, a total of 157 limbs in 83 patients who underwent fixator-assisted high tibial osteotomy for (1) idiopathic genu vara; or (2) osteoarthritis of the knee with proximal tibia vara were initially enrolled. Of these, eight limbs (5%) were excluded on the way; thus, 149 limbs in 77 patients were evaluated. During the period in question, no other techniques were used for proximal tibial osteotomy. The surgical procedures included less preparation of soft tissue, proximal tibial osteotomy, application of a temporary external fixator, correction of alignment, and final fixation with the help of an external fixator. Complications were assessed by chart review and the alignment in both coronal and sagittal planes was compared pre- and postoperatively. Radiographic review to confirm osseous union and alignment was performed by two of the authors not involved in clinical care of the patient. Delayed union was described as union occurring later than 4 months.

Results: Thirty limbs out of 149 tibiae (20%) showed complications, all of which were resolved without leaving any sequela. Twenty-seven limbs out of 149 limbs (18%) showed lateral cortical hinge fracture and three limbs out of 149 limbs (2%) showed soft tissue complications (two superficial infections, one wound hematoma). The overall completeness of reaching the target correction was excellent. In the coronal plane, the difference between the amount of real correction and the amount of target correction was 0.3° ± 0.7° (p < 0.001). In the sagittal plane, the difference between pre- and postoperative posterior proximal tibial angle was -0.1° ± 0.2° (p < 0.001). All osteotomies healed before 4 months.

Conclusions: Fixator-assisted high tibial osteotomy is a valid option for medial opening-wedge high tibial osteotomy, which enables less invasive surgery with excellent coronal/sagittal/rotational alignment control. However, future studies should compare this approach with other approaches for proximal tibial osteotomy to ascertain whether indeed this procedure is less invasive or more reliable.

Level of evidence: Level IV, therapeutic study.

Fig. 1A–C

(A) This intraoperative clinical image shows the patient’s operated leg at the early stage of fixator-assisted high tibial osteotomy. A 2.5-cm oblique incision is made midway between the center of the tibial tuberosity and the posteromedial border of the proximal tibia. p = 2.5-cm oblique incision; q = center of the tibial tuberosity; r = posteromedial border of the proximal tibia. (B) The oblique skin incision starts from 1 cm below the upper margin of the pes anserinus tendon and extending proximally in parallel with the posteromedial border of the tibia. p = 2.5-cm oblique incision; q = center of the tibial tuberosity. (C) Multiple drill holes are made along the superior margin of the two guidewires before osteotomy.

Fig. 2

A schematic illustration shows soft tissue dissection after incision of the skin. A sharp L-shaped incision is made along the anterior border of superficial medial collateral ligament and upper margin of the semitendinosus tendon. These are released subperiosteally.

Fig. 3A–B

(A) Proximal tibial osteotomy is performed. When performing osteotomy for the posterior cortex, the knee is flexed to 70° to 90° to release posterior neurovascular structures from the posterior cortex and the osteotomy is performed from the posteromedial to posterolateral border. (B) When proximal tibial osteotomy is performed, the osteotomy for the anterior cortex can be either proximal or distal to the tibial tuberosity. This C-arm image shows anterior cortical osteotomy distal to the tibial tuberosity.

Fig. 4A–B

(A) Location of two half pins is shown. Posteriorly located half pins are important, because they enable plating providing space at the medial surface of the tibia and help maintain posterior tibial slope. (B) The two half pins for application of external fixation can also be used to check the changes in rotational alignment.

Fig. 5A–D

(A) Correction of alignment is performed. Precise correction with fine tuning to accomplish preoperatively planned alignment is possible using the external fixator and bone-holding forceps. (B) During the alignment correction, the grid method can be useful. A predetermined line on the grid should be at the center of the femoral head of the affected leg. (C) During alignment correction, the grid method can be useful. Once the predetermined line on the grid was set to be at the femoral head center proximally and at the ankle center distally, the surgeon can determine where the same line on the grid should pass through the knee, which can be determined intraoperatively by fine tuning using the external fixator and the bone-holding forceps. (D) During alignment correction, the grid method can be useful. The same line that passed the femoral head center should also pass through the ankle center in the AP view.

Fig. 6A–B

(A) Fixation with a plate (TomoFix^®, TomoFix Medial High Tibial Plate; DePuy, Synthes) is performed. A plate is inserted into the anteromedial surface of the tibia and fixed with 5.0-mm locking screws. (B) The skin incision for the distal half pin can also be used for distal locking screws.

Fig. 7A–C

(A) Preoperative standing long bone radiograph shows proximal tibia vara. The medial proximal tibial angle (MPTA) was 82° and the mFTA was varus 5° for both legs. (B) Postoperative standing long bone radiograph shows correction of the proximal tibia vara. The MPTA was 88° and the mFTA was neutral for both legs. (C) This technique leaves less scar and enables less invasive surgery in medial opening wedge high tibial osteotomy.