BACKGROUND
High tibial osteotomy (HTO) is a well-known procedure for the correction of knee varus. The purpose of this study was to compare the radiological results and accuracy of deformity correction performed using two different techniques: acute opening wedge correction using a plate and gradual correction with a monolateral external fixator.
AIM
To compare of the radiological results of two different techniques: acute opening wedge correction (a plate and screw) and gradual correction (external fixator).
METHODS
A total of 43 patients with plates and 36 patients with external fixators were included. All patients had moderate uniplanar varus deformities. We measured radiographic parameters, including the mechanical axis deviation (MAD), medial proximal tibial angle (MPTA), Caton-Deschamps Index (CDI), posterior proximal tibial angle, and joint line obliquity angle (JLOA). The accuracy of MAD correction was calculated based on a correction goal of neutral or overcorrection for medial compartment arthritis.
RESULTS
Demographics including age, body mass index, sex, and preoperative deformities were similar between the groups. The MAD significantly improved from 23.6 mm medial to the midline (SD = 8.2 mm) to 6.9 mm lateral to the midline (SD = 5.4 mm) (
P
< 0.001). The accuracy of MAD correction did not differ between the groups and was 96.1% (SD = 8.1%) in the plate group and 98.2% (SD = 5.2%) in the external fixator group (
P
= 0.18). The MPTA significantly improved from 83.9° (SD = 2.9°) to 90.9° (SD = 3.3°) (
P
< 0.001), and the change was similar between the groups. Differences were noted in patella height, with a CDI change of -19.2% (SD = 13.7%) and 3.1% (SD = 8.0%) for the plate and external fixator groups, respectively (
P
< 0.001). The change in JLOA was 1.6 degrees (SD = 1.1 degrees) and 0.9 degrees (SD = 0.9 degrees) for the plate and external fixator groups, respectively (
P
= 0.04).
CONCLUSION
Reliable correction of moderate varus alignment was achieved with both the acute opening wedge technique with a plate and the gradual monolateral external fixator technique. The patellar height decreased with the open wedge plate technique. Joint line obliquity decreased to a greater degree with the open wedge plate technique, perhaps as a result of medial collateral ligament release. The appropriate technique should be selected based on surgeon and patient preferences; however, external fixation may be a better choice when the preservation of patellar height is deemed important.
Preoperative planning is important for accurate intraoperative execution in many surgical fields. Planning for distal femoral osteotomies (DFOs) and proximal tibial osteotomies (PTOs) consists of choosing the level of the osteotomy, measuring the angle of the osteotomy based on hip-knee-ankle alignment, and choosing a proper osteotomy wedge size. Medical imaging IT solutions company Sectra has implemented a new osteotomy tool in their radiographic system that is simpler than the accepted standard of modified center of rotation of angulation (mCORA) technique, yet unvalidated. In this study, we aim to compare the Sectra osteotomy tool versus the mCORA technique to measure the osteotomy angles as well as wedge sizes in both DFOs and PTOs to validate this new tool.We enrolled n = 30 consecutive patients with DFOs and n = 30 PTOs from the last year. The Pearson correlation coefficient (PCC) along with descriptive statistics was used to evaluate for similarity between the two techniques. We also compared interobserver and intraobserver reliability using intraclass correlation coefficients (ICC).The PCC for osteotomy angles in DFOs and PTOs were both 0.998 (p < 0.001 for both). For wedge sizes, the PCC in DFOs was 0.993 and 0.980 in PTOs (p < 0.001 for both). ICCs were high for both interobserver measurements in osteotomy angles and wedge sizes (range: 0.989–0.999) as well as intraobserver measurements (0.994–0.999).The Sectra osteotomy tool is a validated tool for preoperative measurements of DFOs and PTOs. It is reliable and simpler than the current practice of the mCORA technique. We suggest future studies to analyze this Sectra osteotomy tool in other settings as to incorporate it into widespread clinical use.
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