Open wedge tibial osteotomies influence on axial rotation and tibial slope

Osseous factors influencing distal tibial rotation in biplane medial opening wedge high tibial osteotomy

PURPOSE

There is a lack of studies investigating the distal tibial rotation (DTR) during medial opening wedge high tibial osteotomy (MOWHTO). This study was designed to evaluate osseous factors influencing DTR in patients who underwent biplane MOWHTO.

METHODS

A total of 106 knee joints in 69 patients who underwent surgery for varus malalignment of knee were reviewed. Based on several software, standard and actual hinge positions were defined in pre-operative and post-operative CT data. Pearson's correlation and Spearman's correlation analysis were performed with DTR change as the dependent variable. Independent variables included angles between standard and actual hinge in the sagittal (ASAHS) and axial (ASAHA) planes, pre-operative and post-operative medial proximal tibial angle, opening width (OW), tuberosity osteotomy angle, flange angle (FA), gap ratio, and hinge fracture.

RESULTS

The distal tibia rotated approximately 0.35° internally. Pearson's and Spearman's correlation analysis showed that DTR change was associated with ASAHS, OW, and FA. Larger OW and FA resulted in higher external rotation angles.

CONCLUSIONS

DTR change was significantly associated with ASAHS, followed by OW and FA rather than ASAHA if only considering osseous factors in biplane MOWHTO. The distal tibia tended to rotate externally when the actual hinge was inclined posteriorly to the standard hinge in the sagittal planes, but rotate externally or internally when the actual hinge was inclined anteriorly.

Changes in Parameters after High Tibial Osteotomy: Comparison of EOS System and Computed Tomographic Analysis

Unintended rotation of the distal tibia occurs during medial open-wedge high tibial osteotomy (MOWHTO). Computed tomography (CT) is the standard method of measuring lower limb alignment; however, the new low-dose EOS system allows three-dimensional limb modeling with automated measurements of lower limb alignment. This study investigated the differences between the changes in lower limb alignment profiles obtained using the EOS system and CT in patients who underwent MOWHTO. We investigated whether any factors contributed to the degree of deformation. Thirty patients were prospectively enrolled between October 2019 and February 2023. Changes in femoral and tibial torsion, femorotibial rotation, and posterior tibial slope were measured using pre- and post-MOWHTO CT and EOS images. We found no significant difference in pre- and postoperative tibial torsion or posterior tibial slope between CT and EOS. No variables showed a significant correlation with changes in the tibial torsion or posterior tibial slope. This study confirmed the possibility that the EOS system could replace CT in measuring changes in several parameters pre- and postoperatively. Furthermore, we confirmed that the distal tibia tended to be internally rotated after MOWHTO; however, we found no significantly related parameters related to deformation caused by MOWHTO.

Changes in sagittal and axial plane alignment in medial opening wedge high tibial osteotomy: a prospective observational study

PURPOSE

Deformity correction during high tibial osteotomy is generally based on coronal plane alignment. The aim of this study was to measure changes in sagittal and axial plane alignment following medial opening wedge high tibial osteotomy [mHTO], using pre- and postoperative computed tomography [CT] scans, and correlate them with changes in coronal plane. The secondary objective was to correlate changes in functional outcomes with changes in alignment in each plane. The null hypothesis was that sagittal and axial plane alignment does not change significantly following mHTO.

METHODS

This was a prospective, observational study including 30 patients of isolated medial compartment osteoarthritis of the knee joint, between 30 and 60 years of age. Preoperative and postoperative computed tomography scan of bilateral lower limbs from hip to ankle was performed. Varus angle, mechanical axis deviation [MAD] of the lower limb, medial proximal tibial angle [MPTA], tibial torsion and posterior proximal tibial angle [PPTA] were measured. Visual Analogue Scale [VAS 0-10 cm scale] was used for assessment of pain. Functional outcomes were evaluated using Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], 12 Item Short Form Survey [SF 12] and Tegner Lysholm knee scoring scale.

RESULTS

Mean age of patients was 44.59 ± 8.157 years. Mean preoperative varus deformity was 11.13 ± 1.5 degrees, which got corrected to a mean valgus alignment of 3.8 ± 0.93 degrees postoperatively. The mechanical axis deviation was 4.32 ± 1.76 mm lateral to the knee joint center postoperatively. Preoperatively, all knees had external tibial torsion [27.08 ± 2.18 degrees] which was corrected to a mean external tibial torsion of 19.80 ± 3.72 degree after the surgery [P < 0.001]. The overall decrease in sagittal alignment in the present study was 3.70 ± 3.14 degree, 3.97 ± 3.06 degree, 3.92 ± 2.33 degree, for medial, middle and lateral cuts, respectively. There was a significant correlation between change in varus/valgus angle and change in TT and PPTA. Significant positive correlation was seen between change in coronal alignment and functional outcome scores.

CONCLUSION

This study has shown that mHTO significantly changes torsional and sagittal alignment. This is the first study to establish relation between correction in coronal plane and associated changes in sagittal and torsional alignments.

Discharging the medial knee compartment: comparison of pressure distribution and kinematic shifting after implantation of an extra-capsular absorber system (ATLAS) and open-wedge high tibial osteotomy-a biomechanical in vitro analysis

PURPOSE

Young and active patients suffering early degenerative changes of the medial compartment with an underlying straight-leg axis do face a therapeutical gap as unloading of the medial compartment cannot be achieved by high tibial osteotomy. Extracapsular absorbing implants were developed to close this existing therapeutical gap. Purpose of the present cadaveric biomechanical study was to compare the unloading effect of the knee joint after implantation of an extra-articular absorber system (ATLAS) in comparison to open-wedge high tibial osteotomy (OW-HTO) under physiological conditions. The hypothesis of the study was that implantation of an extra-capsular absorber results in an unloading effect comparable to the one achievable with OW-HTO.

METHODS

Eight fresh-frozen cadaveric knees were tested under isokinetic flexion-extension motions and physiological loading using a biomechanical knee simulator. Tibiofemoral area contact and peak contact pressures were measured using pressure-sensitive film in the untreated medial compartment. The tibiofemoral superior-inferior, latero-medial translation and varus/valgus rotation were measured with a 3D tracking system Polaris. Pressures and kinematics changes were measured after native testing, ATLAS System implantation and OW-HTO (5° and 10° correction angles) performed with an angular stable internal fixator (TomoFix).

RESULTS

The absorber device decreased the pressure in the medial compartment near full extension moments. Implantation of the ATLAS absorbing system according to the manufacturers' instruction did not result in a significant unloading effect. Deviating from the surgery manual provided by the manufacturer the implantation of a larger spring size while applying varus stress before releasing the absorber resulted in a significant pressure diminution. Contact pressure decreased significantly Δ0.20 ± 0.04 MPa p = 0.044. Performing the OW-HTO in 5° correction angle resulted in significant decreased contact pressure (Δ0.25 ± 0.10 MPa, p = 0.0036) and peak contact pressure (Δ0.39 ± 0.38 MPa, p = 0.029) compared with the native test cycle. With a 10° correction angle, OW-HTO significantly decreased area contact pressure by Δ0.32 ± 0.09 MPa, p = 0.006 and peak contact pressure by Δ0.48 ± 0.12 MPa, p = 0.0654 compared to OW-HTO 5°. Surgical treatment did not result in kinematic changes regarding the superior-inferior translation of the medial joint section. A significant difference was observed for the translation towards the lateral compartment for the ATLAS system Δ1.31 ± 0.54 MPa p = 0.022 and the osteotomy Δ3.51 ± 0.92 MPa p = 0.001. Furthermore, significant shifting varus to valgus rotation of the treated knee joint was verified for HTO 5° about Δ2.97-3.69° and for HTO 10° Δ4.11-5.23° (pHTO 5 = 0.0012; pHTO 10 = 0.0007) over the entire extension cycle.

CONCLUSION

OW-HTO results in a significant unloading of the medial compartment. Implantation of an extra-capsular absorbing device did not result in a significant unloading until the implantation technique was applied against the manufacturer's recommendation. While the clinical difficulty for young and active patients with straight-leg axis and early degenerative changes of the medial compartment persists further biomechanical research to develop sufficient unloading devices is required.

Analysis of changes in tibial torsion angle on open-wedge high tibial osteotomy depending on the osteotomy level

PURPOSE

This study evaluated the tibial torsional angle changes of 72 knees before and after open-wedge high tibial osteotomy (OWHTO) and compared the results according to the osteotomy level.

MATERIALS AND METHODS

Seventy patients (72 knees) with Kellgren-Lawrence grade 3 underwent OWHTO. Demographic data, operation procedures, and measurement of mechanical tibiofemoral angle (mTFA), anatomical tibiofemoral angle (aTFA), tibial torsional angle (TTA), and pre- and postoperative Lysholm and International Knee Documentation Committee (IKDC) scores were obtained. The authors analyzed TTA changes between 30 knees with high-level osteotomy (group A) and 42 knees with low-level osteotomy (group B).

RESULTS

The changes of TTAs in the subjects of 72 knees went from 29.26 ± 5.6° preoperative mean to 25.36 ± 6.4° postoperative mean (p = 0.032). The postoperative TTAs of group A (mean 27.4 ± 4.8°) and B (mean 25.7 ± 4.9°) were statistically significant (p < 0.01). Preoperative Lysholm and IKDC scores of 72 knees had means of 49.1 ± 3.5 and 49.0 ± 15.2, respectively, and postoperative means of 85.7 ± 8.56 and 78.0 ± 17.6, respectively, which were statistically significant (p < 0.01).

CONCLUSIONS

Changes of TTA with internal rotation of distal tibia were observed following OWHTO. High-level osteotomy on the proximal tibia's lateral cortex had less internal rotation of the distal tibia than low-level osteotomy.

Three dimensional CT analysis of the change in rotational alignment in double level osteotomy after double level osteotomy performed for varus osteoarthritic knees

Purpose

To analyze the change in rotational alignment caused by double level osteotomy (DLO) based on comparative three-dimensional image analysis of pre- and postoperative CT images.

Methods

Pre- and postoperative CT examination of the lower extremities were performed with informed consent for 39 consecutive knees undergoing DLO for varus knee deformity. The DLO procedure consisted of closed wedge distal femoral osteotomy (CWDFO) and open wedge high tibial osteotomy (OWHTO). Among those cases, 20 knees complicated with hinge fracture at the osteotomy site were excluded from the analysis to eliminate a confounding factor affecting the results. Consequently, data obtained from 19 knees were subjected to the study analysis while osteotomies with hinge fractures complications were excluded from the study. In the three-dimensional CT image analysis of axial plane images, femoral torsion (the angle between midline along the femoral neck axis and the tangent of the posterior edges of the medial/lateral femoral condyles) and tibial torsion (the angle between the tangent of the posterior edges of the medial/lateral tibial condyles and the transmalleolar axis) were measured. The torsion angle was measured in each of the femurs and the tibias on both pre- and postoperative CT axial images, and the change induced by the osteotomy was calculated and statistically(using Wilcoxon signed-rank test) compared.

Results

The mean pre- and postoperative femoral torsion (anteversion) angles were 29.3° and 31.4° with a significant postoperative increase in internal rotation of the bony segment distal to the osteotomy(P = 0.002). On the tibial side, the mean pre- and postoperative torsion angles were 26.5° and 25.7°, indicating no significant postoperative change(P = 0.199)（NS）.

Conclusions

This study showed that the DLO procedure (combining CWDFO and OWHTO) increased torsion (anteversion) of the femur by 2.1° on average while inducing no significant rotational change on the tibial side.

Rotational Changes in the Distal Tibial Fragment Relative to the Proximal Tibial Fragment at the Osteotomy Site after Open-Wedge High-Tibial Osteotomy

The present study is aimed at assessing the changes in tibial rotation at the osteotomy site after an open-wedge, high-tibial osteotomy (OWHTO) and analysing the factors that affect rotational changes in the distal tibial fragment relative to the proximal tibial fragment at the same site. This study involved 53 patients (60 knees; 16 males and 37 females) with medial osteoarthritis (OA) who underwent OWHTO and preoperative and 3-month postoperative computed tomography (CT) scans. Rotational angles of the distal tibia were measured using Stryker OrthoMap 3D by comparing preoperative and postoperative CTs. The mean rotational angle yielded an external rotation of 2.9° ± 4.8°. There were 17 knees with internal rotations, 37 knees with external rotations, and one knee with no rotation. The rotational angle significantly correlated with the resultant change in the femorotibial angle (correction angle) and the angle between the ascending and transverse osteotomy lines on the anterior osteotomised surface on which a flange was formed with the distal tibial osteotomised surface (flange angle). The flange angle affected the rotation, but it may have been affected by our surgical technique. The rotational angle did not significantly correlate with the change in the angle of the posterior tibial slope or body mass index. There were significant correlations between the rotational angle and correction angle (r = 0.42, p < 0.05). Additionally, the rotational angle correlated with the flange angle (r = -0.41, p < 0.05).

Opening gap width influences distal tibial rotation below the osteotomy site following open wedge high tibial osteotomy

Purpose

Although rotation of the distal portion of the tibia below the osteotomy site is considered an inevitable change in the axial plane in open wedge high tibial osteotomy (HTO), several studies on this issue have shown contradictory results. The purpose of this study was, therefore, to determine the direction and amount of distal tibial rotation following open wedge HTO using a three-dimensional reconstructed model.

Methods

This study involved 41 patients (42 knees) undergoing open wedge HTO for primary medial osteoarthritis. Distal tibial rotation was measured on the overlaid tibial plateau of a preoperative and postoperative 3-dimensional reconstructed model based on computed tomography.

Results

The mean distal tibial external rotation was 2.7° ± 2.3° (range, -0.9° to 9.9°), and the opening gap was larger in the group with > 3° distal tibial rotation than in the group with ≤ 3° distal tibial rotation (11.4 mm vs. 9.6 mm, P = 0.027). Multiple regression analysis showed that the opening gap was the only predictor of distal tibial rotation. On receiver operating characteristics analysis, an opening gap of 10 mm was found to be the optimal cutoff value for achieving greater than 3° of distal tibial rotation.

Conclusions

Following medial opening wedge HTO, the distal tibial portion below the osteotomy site rotated approximately 3° externally. The magnitude of the external rotation of the distal tibia was affected by the opening gap width.

Tibial rotational alignment after opening-wedge and closing-wedge high tibial osteotomy

A lot of good outcomes have been reported after opening-wedge high tibial osteotomy (OWHTO) and closing-wedge high tibial osteotomy (CWHTO).The purpose of this study was to examine the rotational alignment after OWHTO and CWHTO performed by the same surgeon in one hospital.

The sample included 30 knees from 24 patients. In all cases, the same orthopaedic surgeon performed the osteotomy surgeries using the same method. The tibial external rotation angle (TERA) was measured using the CT images of proximal tibial plateau and distal tibial malleolus from the consecutive axial CT slices of tibia. In this study, two considerations were examined. The first was the change in rotation angle, which was defined by TERA noted before and after the operation. The second was the relationship between the correction angle of the osteotomy and the rotation angle change of the distal tibia. The first was evaluated using the paired-Student’s t-test, while the second was analyzed with Pearson’s correlation coefficient. In the OWHTO group, the mean TERA was 21.4± 7.0° preoperatively and 20.2 ± 8.0° postoperatively, but no significant difference was seen between pre- and post-operation measurements (p = 0.21). Significant TERA increasing (that is, external rotation of the distal tibia) was seen postoperatively in only three knees. In the CWHTO group, the mean TERA was 19.9 ± 10.5° preoperatively and 16.5 ± 9.5° postoperatively, and significant difference was seen between pre- and post-operative TERA (p < 0.05). No significant correlation was seen between the correction angle and the change of the rotation angle in either group (r = 0.40, r = 0.12) .

In the OWHTO group, both internal and external rotation of the distal tibia can occur after surgery. In the CWHTO group, the distal tibia rotated internally postoperatively. No significant correlation was seen between the correction angle and the change in the rotation angle in either group

Role of constraining staple on tibial slope in open wedge osteotomy: A comparative study

BACKGROUND

Medial opening-wedge high tibial osteotomy (HTO) corrects varum deformities in osteoarthritic knees. This procedure has been shown to increase tibial slope, which may limit knee extension and provoke an anterior tibial translation. The purpose of this research was to study the impact of a constraining staple on the variation of the tibial slope in medial opening-wedge HTO.

HYPOTHESIS

Insertion of a bone staple on the anterior aspect of the tibia during medial opening-wedge HTO minimizes risks of tibial slope increase.

MATERIALS AND METHODS

This retrospective study was conducted on 91 cases of HTO performed by a single surgeon between 2008 and 2013. Tibial slope was measured pre-operatively and postoperatively according to Brazier's method. We analyzed tibial slope variation in a group that did not receive bone staple insertion during their HTO and compared to the group that did.

RESULTS

A total of 91 patients met the inclusion criteria, 61 males (67.0%) and 30 females (33.0%). The median age was 51 years old. In the staple group, a 0.1° mean increase in tibial slope was found (p<0.001), whereas in the non-staple-inserted group, a 2.4° mean increase in tibial slope was observed (p<0.001).

DISCUSSION AND CONCLUSION

The use of a temporary anterior staple during medial-opening HTO appears to be effective in minimizing tibial slope increase.

LEVEL OF EVIDENCE

III, Retrospective comparative study.

Retro-tubercular gap widening can be caused by inappropriate anterior osteotomy and large opening gap in the medial biplanar open-wedge HTO

PURPOSE

The purpose of this study was to investigate the causes of retro-tubercular gap widening and to confirm whether this widened gap causes instability of the osteotomy configuration during open-wedge high tibial osteotomy (OWHTO).

METHODS

Operative records and radiologic findings of patients who underwent biplanar medial OWHTO between 2014 and 2016 were retrospectively evaluated. To identify the osteotomy configuration including lateral hinge fracture, postoperative simple radiographs and CT images were analyzed. Postoperative CT scan was used to evaluate the widening of the retro-tubercular gap, thickness, and axial angle of retro-tubercular osteotomy, as well as the ratios of anterior and posterior osteotomy, and hinge length. The correlation of each factor was evaluated and analyzed in accordance with the lateral hinge fracture (LHF).

RESULTS

Widening of the retro-tubercular gap showed a significant correlation with the axial angle of retro-tubercular osteotomy, anterior osteotomy ratio, and opening gap distance, but not with the thickness of retro-tubercular osteotomy, posterior osteotomy ratio, and hinge length ratio. The LHF group showed significantly larger value than the non-LHF group with respect to the thickness of retro-tubercular osteotomy (P = 0.003), axial angle of retro-tubercular osteotomy (P = 0.033), retro-planar gap distance (P = 0.001), anterior osteotomy ratio (P = 0.000), and opening gap distance (P = 0.003). The hinge length ratio was smaller in the LHF group than in the non-LHF group (P = 0.001). However, the posterior osteotomy ratio was not different between the two groups (n.s.).

CONCLUSION

Retro-tubercular gap widening can be caused by inappropriate anterior osteotomy and large opening gap distance, which can be related to LHF. Therefore, anterior cortical osteotomy may also be an important factor for preventing instability of the proximal fragment in biplanar OWHTO.

LEVEL OF EVIDENCE

Case-control study, Level III.

Comparison of torsional changes in the tibia following a lateral closed or medial open wedge high tibial osteotomy

OBJECTIVE

The aim of this study is to evaluate, by computed tomography (CT), whether different torsional changes occur in the tibia following a lateral closed wedge high tibial osteotomy (CWHTO) versus a medial open wedge high tibial osteotomy (OWHTO) procedure. It was hypothesized that the distal fragment of the tibia would show greater internal rotation after CWHTO.

METHODS

Thirty knees from 25 patients who underwent HTO were enrolled. Fifteen knees of 14 patients who underwent CWHTO and 15 knees of 11 patients who received OWHTO were match-paired. CT scans were taken before and three weeks after surgery. Rotational changes in the distal fragment of the tibia were assessed by measuring the tibial torsion angle (TTA).

RESULTS

The mean TTA in the CWHTO group pre-operatively and postoperatively was +23.9° ± 7.8° and + 18.2° ± 7.0°, respectively. Internal rotation of the distal fragment of the tibia after CWHTO was -5.7 ± 3.3° (P < 0.001). In the OWHTO group, the mean TTA pre-operatively and postoperatively was +27.9° ± 6.9° and + 26.8 ± 7.7°, respectively, with no significant change in torsion observed (P > 0.05).

CONCLUSIONS

The distal fragment of the tibia rotated internally after CWHTO but not after OWHTO.

LEVEL OF EVIDENCE

Level III: case-control study.

Short-term functional outcomes of computer assisted navigated high tibial osteotomy

Purpose

High tibial osteotomy (HTO) is a surgical procedure performed on patients with knee osteoarthritis (OA). Computer assisted navigated high tibial osteotomy (CAN-HTO) may result in improved outcomes for patients undergoing this procedure.

Methods

Retrospective study involving patients undergoing CAN-HTO.

Results

Surveyed thirty-three patients. Average follow-up: 2.3 years. 97% patients reported they would have this procedure performed again, if indicated. Re-operation rate: 6.1% and complication rate: 12.1%. Patients had decreased KOOS for symptoms when compared to non-navigation based HTO (p = 0.000).

Conclusion

There may be merit with the use of CAN-HTO, with demonstrated patient-reported benefits at 2-year follow-up.

Leg length change after opening wedge and closing wedge high tibial osteotomy: A meta-analysis

Background

Theoretical considerations suggest that leg length increases after opening wedge high tibial osteotomy (HTO) and decreases after closing wedge HTO; however, in vivo studies have yielded conflicting results. This meta-analysis therefore assessed changes in leg length after opening wedge and closing wedge HTO.

Methods

All studies comparing pre- and postoperative leg length in patients who underwent opening and/or closing wedge HTO were included. Two reviewers independently recorded data from each study in terms of sample size as well as preoperative and postoperative leg length of open wedge and/or closed wedge HTO groups.

Results

Four studies were included in the meta-analysis. Although pooled results showed leg length changes from before to after surgery were –6.93 mm (95% confidence interval [CI]: –17.53 to 3.67 mm; P = 0.20) in opening wedge HTO and 1.97 mm (95% CI: –7.13 to 11.07 mm; P = 0.67) in closing wedge HTO, respectively, these values were statistically not significant. However, the difference in the pooled mean leg length change from before to after surgery between opening wedge and closing wedge HTO was 8 mm, a difference that was significant (95% CI: 6.53 to 9.46 mm; P<0.001).

Conclusion

The change in leg length was not statistically significant for either opening or closing wedge HTO. However, leg length change from before to after surgery was 8 mm greater for opening wedge HTO than for closing wedge HTO.

Three-dimensional relationships between secondary changes and selective osteotomy parameters for biplane medial open-wedge high tibial osteotomy

BACKGROUND

To assess the axial rotational change of distal tibia and posterior tibial slope (PTS) change after OWHTO in 3-D planes and to identify the causal relationship on the effect of variation in the posterior slope angle and rotational errors.

METHODS

A total of 21 patients (23 knees) underwent OWHTO and were evaluated with 3D-CT before and after surgery. Medial proximal tibial angle in the coronal plane, PTS in the sagittal plane, and rotational axis in axial plane were evaluated and compared between pre- and post-operative 3D models constructed by applying reverse-engineering software. As a selective osteotomy parameter, hinge axis and gap ratio were measured in the postoperative 3D models RESULTS: The increasing tendency of internal rotation of the distal tibia after OWHTO was positively related to hinge axis (β=0.730, p=0.001, R²=0.546) and gap ratio (β=-0.283, p=0.001, R²=0.520), which also showed statistically significant linear correlations to PTS changes after multivariate regression analysis that controlled for the rotational change of the distal tibia (hinge axis: β=0.443, p=0.006; gap ratio: β=0.144, p=0.017).

CONCLUSION

Hinge axis more posterolaterally was related to a greater increase in internal rotation after biplane medial open-wedge HTO, and hinge axis and gap ratio were significant predictors of PTS change after rotational change was controlled for. Hinge axis has to be considered an important independent variable for limiting unintended axial rotation change as well as PTS change as secondary.

CLINICAL RELEVANCE

The relationship of the hinge axis with the rotational change and its influence to PTS change, acknowledged from by-product of the statistical analysis, might provide a deeper understanding of HTO, and should have constitutional effects on the development of HTO procedures and implants.

Effect of soft tissue laxity of the knee joint on limb alignment correction in open-wedge high tibial osteotomy

PURPOSE

Open-wedge high tibial osteotomy (HTO) cannot always accurately correct limb alignment, resulting in under- or over-correction. This study assessed the relationship between soft tissue laxity of the knee joint and alignment correction in open-wedge HTO.

METHODS

This prospective study involved 85 patients (86 knees) undergoing open-wedge HTO for primary medial osteoarthritis. The mechanical axis (MA), weight-bearing line (WBL) ratio, and joint line convergence angle (JLCA) were measured on radiographs preoperatively and after 6 months, and the differences between the pre- and post-surgery values were calculated. Post-operative WBL ratios of 57-67 % were classified as acceptable correction. WBL ratios <57 and >67 % were classified as under- and over-corrections, respectively.

RESULTS

Preoperative JLCA correlated positively with differences in MA (r = 0.358, P = 0.001) and WBL ratio (P = 0.003). Difference in JLCA showed a stronger correlation than preoperative JLCA with differences in MA (P < 0.001) and WBL ratio (P < 0.001). Difference in JLCA was the only predictor of both difference in MA (P < 0.001) and difference in WBL ratio (P < 0.001). The difference between pre- and post-operative JLCA differed significantly between the under-correction, acceptable-correction, and over-correction groups (P = 0.033). Preoperative JLCA, however, did not differ significantly between the three groups. Neither preoperative JLCA nor difference in JLCA correlated with change in posterior slope.

CONCLUSIONS

Preoperative degree of soft tissue laxity in the knee joint was related to the degree of alignment correction, but not to alignment correction error, in open-wedge HTO. Change in soft tissue laxity around the knee from before to after open-wedge HTO correlated with both correction amount and correction error. Therefore, a too large change in JLCA from before to after open-wedge osteotomy may be due to an overly large reduction in JLCA following osteotomy, suggesting alignment over-correction during surgery.

LEVEL OF EVIDENCE

II.

Computer-assisted navigation decreases the change in the tibial posterior slope angle after closed-wedge high tibial osteotomy

PURPOSE

The purpose of the present study was to compare the change in tibial posterior slope angle (PSA) between patients treated via computer-assisted and conventional closed-wedge high tibial osteotomy (CWHTO). It was hypothesized that a decrease in the PSA would be less in the computer-assisted group than in the conventional group.

METHODS

Data on a total of 75 computer-assisted CWHTOs (60 patients) and 75 conventional CWHTOs (49 patients) were retrospectively compared using matched pair analysis. The pre- and postoperative mechanical axis (MA) and the PSA were radiographically evaluated. The parallel angle was defined as the angle between the joint line and the osteotomy surface. The data were compared between the two groups.

RESULTS

The postoperative radiographic MA averaged 1.3° ± 2.6° valgus in the computer-assisted group and 0.3° ± 3.1° varus in the conventional group. The change in PSA averaged -0.8° ± 0.9° in the computer-assisted group and -4.0° ± 2.2° in the conventional group. The parallel angle averaged 0.2° ± 3.0° in the computer-assisted group and 6.2° ± 5.3° in the conventional group.

CONCLUSION

Computer-assisted CWHTO using four guide pins could avoid inadvertent change in the PSA. The navigation can be used in anticipation of decreasing the risk of change in the PSA in CWHTO, especially in patients whose preoperative PSA is small. The special attention should be paid to locate the hinge axis acutely and to make the parallel proximal and distal osteotomy surfaces during CWHTO.

LEVEL OF EVIDENCE

III.

Unintended Rotational Changes of the Distal Tibia After Biplane Medial Open-Wedge High Tibial Osteotomy

This study involved 35 knees undergoing biplane medial open-wedge high tibial osteotomy (OWHTO) to assess the axial rotation of the distal tibia. The distal tibiae were internally rotated by 3.0° ± 7.1° after OWHTO. The opening width showed a Pearson correlation coefficient of -0.743 (P < .001), and the tuberosity osteotomy angle showed that of -0.678 (P < .001) with distal tibial rotation. However, changes in hip-knee-ankle angle, medial proximal tibial angle, and posterior tibial slope were not significantly correlated with the change in distal tibial rotation. In conclusion, there was an unintended tendency of increasing internal rotation of the distal tibia after biplane medial OWHTO, and this tendency was positively related to the opening width and tuberosity osteotomy angle.

Factors influencing posterior tibial slope and tibial rotation in opening wedge high tibial osteotomy

PURPOSE

Opening wedge high tibial osteotomy (HTO) is an accepted treatment option for medial compartment knee osteoarthritis with associated varus lower limb axis in younger, more active patients. A concern with the use of this technique is that posterior tibial slope (PTS) and tibial rotation can be altered. We hypothesized that there is a tendency to increase the PTS and internal rotation of the distal tibia during the procedure and that certain intra-operative parameters may influence the amount of change that can be expected.

METHODS

A cadaveric model and surgical navigation system were used to evaluate the influence of certain intra-operative factors of the degree of PTS and tibial rotation change observed during medial opening HTO. Parameters evaluated included: degree of osteotomy opening, knee flexion angle, location of limb support (thigh versus foot), performance of a posteromedial release, the status of the lateral cortical hinge, and the degree of osteoarthritis present in the knee.

RESULTS

Combining measurements of all specimens and parameters, a mean PTS increase of 2.7° ± 3.9° and a mean tibial internal rotation of 1.5° ± 2.9° were observed. Clinically, significant changes in tibial slope (>2°) occurred in 50.4 % of corrections, while significant changes in tibial rotation (>5°) occurred in only 11.9 % of corrections. Patients with significant osteoarthritis and concomitant flexion contracture, cases where large corrections were required, and procedures in which the lateral cortical hinge was disrupted were associated with increased PTS change. The other factors evaluated did not exert a significant influence of the degree of PTS change observed.

CONCLUSIONS

Surgeons should be vigilant for possible PTS change, particularly in high-risk situations as outlined above. Routine use of an intra-operative measure of PTS is recommended to avoid inadvertent slope change.

No correction angle loss with stable plates in open-wedge high tibial osteotomy

PURPOSE

The aim of this study was to compare the clinical and radiological results of the wedge plate and locking plate systems in open-wedge high tibial osteotomy.

METHODS

Between 2007 and 2010, the wedge plate was used as the fixation device for osteotomy to treat a total of 67 patients; from 2009 to 2010, the locking plate was used in 19 patients. Matching for gender, age, body mass index (BMI), and articular cartilage status, 19 pairs of wedge plate and locking plate cases were enrolled in a 1:1 retrospective matched-pair analysis. Clinical data were collected and scored using the visual analogue scale and the International Knee Documentation subjective score. Additionally, pre-operative, immediate post-operative, and last follow-up radiographs were obtained to assess changes in the hip-knee-ankle (H-K-A) angle and posterior tibial slope.

RESULTS

No significant differences in gender, age, BMI, follow-up period, and articular cartilage status were found between the groups. Although the initial correction of the H-K-A angles, 8.9° ± 1.9° and 9.4° ± 4.2° for the wedge plate and locking plate groups, respectively, was not significantly different, a significant difference (P = 0.046) in the final correction angles, 7.2° ± 2.1° and 9.4° ± 4.4°, respectively, was found. The increase in the posterior tibial slope, 0.5° ± 2.0° and 3.2° ± 2.6°, for the wedge plate and locking plate groups, respectively, was significantly different (P = 0.010). When classified according to the correction angle, we found that when the initial correction angle exceeded 10.0°, an average correction loss of 2.9° ± 0.5° was observed in the wedge plate group, whereas an average increase in the posterior tibial slope of 5.8° ± 1.6° was evident for the locking plate group.

CONCLUSIONS

At 2 years post-operatively, the final correction angles of the wedge and the locking plate groups differed significantly, and the wedge plate group had a smaller increase in the posterior tibial slope than the locking plate group.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Total knee arthroplasty after high tibial osteotomy

High tibial osteotomy may be indicated in the treatment of varus knee in young, active patients. The preservation of proprioception and native joint and biomechanics is crucial for functional recovery in these patients. However, deterioration of initial good results can occur with time. In such cases, revision with total knee arthroplasty is indicated. However, this is a more surgically demanding option compared with a primary prosthesis. Accurate preoperative planning is mandatory to decrease the risk of intraoperative complications. A precise surgical technique, which is crucial to improving functional outcomes, includes hardware removal, joint exposition, tibial deformities due to previous osteotomy, and managing soft tissue mismatches. Possible technical challenges and surgical solutions exist for each of these aspects. However, several studies report lower functional results compared with primary implants. Thus, patients should be informed before high tibial osteotomy about its failure rate, the difficult surgical aspects of an additional prosthesis, and less satisfactory clinical results.

Open-wedge high tibial osteotomy: comparison between manual and computer-assisted techniques

PURPOSE

The purpose of our study was to compare clinical and radiological results of two groups of patients treated for medial compartment osteoarthritis of the knee with either conventional or computer-assisted open-wedge high tibial osteotomy (HTO). Goals of surgical treatment were a correction of the mechanical axis between 2° and 6° of valgus and a modification of posterior tibial slope between -2° and +2°.

METHODS

Twenty-four patients (27 knees) affected by varus knee deformity and operated with HTO were prospectively followed-up. They were randomly divided in two groups, A (11 patients, conventional treatment) and B (13 patients, navigated treatment). The American Knee Society Score and the Modified Cincinnati Rating System Questionnaire were used for clinical assessment. All patients were radiologically evaluated with a comparative lower limb weight-bearing digital radiograph, a standard digital anteroposterior, a latero-lateral radiograph of the knee, and a Rosenberg view.

RESULTS

Patients were followed-up at a mean of 39 months. Clinical evaluation showed no statistical difference (n.s.) between the two groups. Radiological results showed an 86% reproducibility in achieving a mechanical axis of 182°-186° in group B compared to a 23% in group A (p = 0.0392); furthermore, in group B, we achieved a modification of posterior tibial slope between -2° and +2° in 100% of patients, while in group A, this goal was achieved only in 24% of cases (p = 0.0021).

CONCLUSION

High tibial osteotomy with navigator is more accurate and reproducible in the correction of the deformity compared to standard technique.

LEVEL OF EVIDENCE

Therapeutic study, Level II.

Computer-assisted navigation for the intraoperative assessment of lower limb alignment in high tibial osteotomy can avoid outliers compared with the conventional technique

PURPOSE

Longterm outcomes after valgization high tibial osteotomy (HTO) to treat varus osteoarthritis seem to depend mainly on correction precision. Intraoperative assessment of leg alignment based on radiological visualization of the mechanical axis is difficult and its precision is limited. A promising approach to improving precision is to make use of navigation systems. The case-control study reported here involved the evaluation of patients whose varus osteoarthritis had been treated by open-wedge high tibial ostoetomy, and an analysis of the effect of computer-guided navigation on postoperative leg alignment.

METHODS

Forty patients with medial varus osteoarthritis managed by open-wedge high tibial osteotomy using a surgical navigation system were included in the present study (Group 1). They were compared with a retrospective control group (Group 2) of 40 patients with respect to postoperative leg alignment, correlation of planned and definitive correction, and postoperative deviation from the Fujisawa point.

RESULTS

The mean values for planned and definitive correction showed no significant differences for identical demographic data. As a percentage of the width of the tibial plateau the postoperative weight-bearing radiographs showed a mechanical line that intersected with the knee base line at the desired value of 62% (Fujisawa point) in 58.8% (SD ± 6.1) in Group 1 and in 58.6% (SD ± 8.1) in Group 2. Despite similar mean values a significantly higher number of corrections were outside the reference area (n = 7) in the non-navigated group, whereby all corrections were within the desired range in the navigated group. There were no significant differences in operation time.

CONCLUSIONS

This study showed that the use of a navigation system can not increase the precision of the open-wedge HTO procedure in patients with varus osteoarthritis but it can eliminate the outliers of a well defined range.

LEVEL OF EVIDENCE

Case-control study, Retrospective comparative study, Level III.

Gait analysis of walking before and after medial opening wedge high tibial osteotomy

INTRODUCTION

Medial opening wedge high tibial osteotomy (HTO) is used to treat medial compartment osteoarthritis (OA) of the knee. HTO shifts the weight-bearing line from the medial compartment into the lateral compartment. The aim of this study was to investigate the functional biomechanical consequences of this alteration in alignment.

METHODS

Eleven male patients with medial compartment osteoarthritis underwent three-dimensional gait analysis during level walking before 12 months and after medial opening wedge HTO. Nine male control subjects of a similar age were also tested using the same protocol. Sagittal and coronal angles and moments in both operated and non-operated knees were compared. Pre and postoperative radiographic coronal plane alignment was also measured.

RESULTS

Walking speed increased significantly postoperatively (P = 0.0001) and was not different from controls. Preoperatively, maximum knee flexion in stance was reduced compared to control (P = 0.02). Postoperatively, maximum knee flexion increased significantly (P = 0.005) and was the same as the controls. Similar changes were observed for the maximum knee flexion moment. The mean maximum varus angle during stance was reduced from 13.5° preoperatively to 5.4° postoperatively (P = 0.0001) compared to (6.8°) in controls. The mean maximum adduction moment also reduced from 3.9 to 2.7 (% Bw/ht, P = 0.02), compared to 3.6 in control subjects. Interestingly, the adduction moments in the non-operated knee increased postoperatively from 3.3 to 4.1 (% Bw/ht, P = 0.02). The mean radiological mechanical alignment was changed from 172 degrees preoperatively to 180 degrees postoperatively (P < 0.001).

CONCLUSION

HTO resulted in normalisation of several dynamic knee function parameters such as walking speed, knee flexion and external knee flexion moment. As anticipated, HTO reduced the varus angle and adduction moments of the operated knee. An increased adduction moment in the non-operated knee over the first postoperative year was found.

LEVEL OF EVIDENCE

Prospective case-control clinical laboratory study, Level III.

The role of the tibial slope in sustaining and treating anterior cruciate ligament injuries

PURPOSE

A steep tibial slope may contribute to anterior cruciate ligament (ACL)-injuries, a higher degree of instability in the case of ACL insufficiency, and recurrent instability after ACL reconstruction. A better understanding of the significance of the tibial slope could improve the development of ACL injury screening and prevention programmes, might serve as a basis for individually adapted rehabilitation programmes after ACL reconstruction and could clarify the role of slope-decreasing osteotomies in the treatment of ACL insufficiency. This article summarizes and discusses the current published literature on these topics.

METHODS

A comprehensive review of the MEDLINE database was carried out to identify relevant articles using multiple different keywords (e.g. 'tibial slope', 'anterior cruciate ligament', 'osteotomy', and 'knee instability'). The reference lists of the reviewed articles were searched for additional relevant articles.

RESULTS

In cadaveric studies, an artificially increased tibial slope produced an anterior shift of the tibia relative to the femur. While mathematical models additionally demonstrated increased strain in the ACL, cadaveric studies have not confirmed these findings. There is some evidence that a steep tibial slope represents a risk factor for non-contact ACL injuries. MRI-based studies indicate that a steep slope of the lateral tibial plateau might specifically be responsible for this injury mechanism. The influence of the tibial slope on outcomes after ACL reconstruction and the role of slope-decreasing osteotomies in the treatment of ACL insufficiency remain unclear.

CONCLUSION

The role of the tibial slope in sustaining and treating ACL injuries is not well understood. Characterizing the tibial plateau surface with a single slope measurement represents an insufficient approximation of its three-dimensionality, and the biomechanical impact of the tibial slope likely is more complex than previously appreciated.

LEVEL OF EVIDENCE

IV.

Computer-assisted navigation in high tibial osteotomy: a systematic review of the literature

High tibial osteotomy (HTO) is a procedure which aims to change the mechanical axis of the lower limb, transferring the body weight across healthy articular cartilage. Several studies have shown that accurate correction is the leading predictor for success.

In this article, we systematically review the computer-assisted techniques that have been used in attempts to increase the accuracy of the surgery and improve postoperative outcomes. The results of the cadaveric and clinical studies to date are presented and the benefits and pitfalls of navigation are discussed.

High complication rate after biplanar open wedge high tibial osteotomy stabilized with a new spacer plate (Position HTO plate) without bone substitute

PURPOSE

We performed a prospective clinical and radiographic evaluation after open wedge high tibial osteotomy (HTO) using the new Position HTO plate (Aesculap, Tuttlingen, Germany) without bone transplantation.

METHODS

Thirty-five open wedge HTOs with the Position HTO plate were performed without bone wedges. The mean patient age was 44.6 ± 9.2 years at the time of osteotomy, which was planned with mediCAD II software (Hectec, Niederviehbach, Germany). The Hospital for Special Surgery score, Lysholm-Gillquist score, Tegner activity level, and International Knee Documentation Committee subjective score were used for clinical assessment. We evaluated radiographs obtained preoperatively and at 2, 6, and 12 months postoperatively using full-weight-bearing anteroposterior whole-leg views and anteroposterior and lateral views of the knee. For statistical analyses, JMP 8.0.1 (SAS, Cary, NC) was used.

RESULTS

We observed an overall complication rate of 34% and a plate-related complication rate of 23%. Plate-related complications included loss of correction, fracture of the tibial plateau, screw failure, malunion, and fracture of the lateral cortical bone. A significant difference in the mechanical tibiofemoral angle of -1.3° ± 1.4° (P < .001) was found between the follow-up at 2 and 6 months. The mean Hospital for Special Surgery score was 74.8 ± 11.7 preoperatively, and it increased to 87.8 ± 11.0 (P < .001). The mean score on the Lysholm-Gillquist knee functional scoring scale was 55.5 ± 21.7 preoperatively, and it improved to 73.0 ± 23.9 (P < .001). The Tegner activity level was 2.6 ± 0.9 preoperatively, and it improved significantly at final follow-up to 3.7 ± 1.8 (P < .02). The International Knee Documentation Committee subjective score was 43.0 ± 14.9 preoperatively, and it increased to 66.1 ± 21 (P < .001).

CONCLUSIONS

We have shown a high plate-related complication rate and a significant loss of correction between 2 and 6 months of follow-up after open wedge HTO using the new Position HTO plate without bone wedges. The preoperatively planned mechanical tibiofemoral angle was not achieved. Despite these complications, the clinical outcome improved significantly. The Position HTO plate cannot be recommended with the presented technique.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Computer-assisted high tibial osteotomy: preliminary results

Open-wedge high tibial osteotomy (HTO) is an established technique for the treatment of symptomatic varus malaligned knees. In this study, we prospectively followed up 13 patients (14 knees) who underwent navigation system-supported HTO for varus knee deformity. Preoperatively all patients underwent a physical examination, and anteroposterior and laterolateral lower limb weight-bearing digital radiographs were obtained. The following parameters were examined: (1) Insall-Salvati index; (2) posterior tibial slope angle; (3) mechanical femorotibial angle; (4) inferior limb length. At a mean follow-up of 12.6 months, clinical examination showed satisfactory results in all patients. The mean Modified Cincinnati Rating System Questionnaire rating increased significantly from 46.5 ± 7.2 to 84.6 ± 8, while the mean Knee Society Score increased significantly from 51.4 ± 9.9 to 85.1 ± 7.3. The mean Insall-Salvati index changed from 1.11 preoperatively to 1.10 postoperatively (P=.742). According to the navigation system data, the femorotibial mechanical axis was corrected from a varus of 6.3° ± 1.9° to a valgus of 2.1° ± 1.6°. These data matched postoperative radiographic lower limb weight-bearing data. In the group of patients in whom we evaluated the posterior tibial slope with the navigation system, we detected an increase of 0.3° ± 0.4° compared with the preoperative radiographic examination evaluations; the comparison between the postoperative and the preoperative radiograhic examination results showed an increase of 0.5° ± 0.7° (P=.87). The results of our study seem to show greater accuracy of mechanical axis correction and smaller increase in tibial slope when a navigation system is used in open-wedge HTO.

Avoiding intraoperative complications in open-wedge high tibial valgus osteotomy: technical advancement

Open-wedge high tibial osteotomy for varus osteoarthritis of the knee is a successful treatment option, but is associated with potential intraoperative complications, jeopardizing outcome. We describe four technical hints avoiding complications as tibia plateau fracture, lateral hinge dislocation, over- and undercorrection, and unwanted increase of the posterior tibial slope and axial malrotation. The technique, which is primarily based on placing five Kirschner-wires (one for the osteotomy direction, two for the external fixator, and two for rotational and slope control) is simple, reproducible, inexpensive, and readily available.

Patellar height and posterior tibial slope after open- and closed-wedge high tibial osteotomy: a radiological study on 100 patients

BACKGROUND

Valgus high tibial osteotomy (HTO) may be associated with changes in the patellar height and posterior tibial slope.

HYPOTHESIS

Patellar height increases and posterior tibial slope decreases after closed-wedge HTO, whereas patellar height decreases and tibial slope increases after open-wedge osteotomy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Lateral radiographs of 100 knees were assessed for patellar height (PH) (Insall-Salvati index [ISI], Caton-De Champ index [CDI], and Blackburne-Peel index [BPI]) as well as posterior tibial slope. Measurements were done before HTO (50 closed wedge [CW], 50 open wedge [OW]), direct postoperatively, and before removal of the hardware.

RESULTS

In the CW group, all 3 PH indices were increased direct postoperatively and at removal of the hardware, with changes in CDI and BPI being significant (P<.05). The effect size (ES) for the direct postoperative PH increase was medium (ES = 0.48) according to CDI. In the OW group, all 3 indices showed a significant (P <.05) PH decrease direct postoperatively and at hardware removal. The ES for the direct postoperative PH decrease was large according to CDI (ES = 0.92) and BPI (ES = 0.80). There were no significant changes between the 2 follow-up measurements (P > .05) with a small ES each. Posterior tibial slope showed a significant (P <.05) decrease of 3.1 degrees +/- 3.4 degrees after CW HTO and a significant (P <.05) increase of 2.1 degrees +/- 3.6 degrees after OW HTO direct postoperatively. These changes did not change at the second follow-up. In CW HTO, the correlations between frontal plane correction and PH changes were moderate (CDI: r = .57; BPI: r = .64). In OW HTO, these correlations were weak (CDI: r = .44; BPI: r = .46). According to ISI, there was no correlation (CW: r = .11; OW: r = .16). There was no correlation between PH changes and slope changes (CDI) and no correlation between frontal plane HTO correction and slope changes in both CW and OW HTO.

CONCLUSION

The results confirm our hypothesis for PH and posterior tibial slope changes after valgus HTO. However, there is no strong correlation between PH changes and the degree of frontal plane HTO correction. The incidence of patella infera increases after OW HTO, whereas the incidence of patella alta increases after CW HTO. Therefore, we recommend performing CW HTO or OW HTO with the tuberosity left at the proximal tibia in cases of patellofemoral complaints or patella infera. Neither technique leads to patellar lowering. It should be borne in mind that PH and posterior tibial slope may have been altered before planning total knee replacement after HTO.

Reliability of image-free navigation to monitor lower-limb alignment

Proper alignment of the mechanical axis of the lower limb is the principal goal of a high tibial osteotomy. A well-accepted and relevant technical specification is the coronal plane lower-limb alignment. Target values for coronal plane alignment after high tibial osteotomy include 2 degrees of overcorrection, while tolerances for this specification have been established as 2 degrees to 4 degrees. However, the role of axial plane and sagittal plane realignment after high tibial osteotomy is poorly understood; consequently, targets and tolerance for this technical specification remain undefined. This article reviews the literature concerning the reliability and precision of navigation in monitoring the clinically relevant specification of lower-limb alignment in high tibial osteotomy. We conclude that image-free navigation registration may be clinically useful for intraoperative monitoring of the coronal plane only. Only fair and poor results for the axial and sagittal planes can be obtained by image-free navigation systems. In the future, combined image-based data, such as those from radiographs, magnetic resonance imaging, and gait analysis, may be used to help to improve the accuracy and reproducibility of quantitative intraoperative monitoring of lower-limb alignment.