Increased Posterior Tibial Slope After Medial Open-Wedge High Tibial Osteotomy May Result in Degenerative Changes in Anterior Cruciate Ligament

Effect of plate design on maintenance of anterior and posterior gaps and posterior tibial slope after cyclic loading in medial open-wedge high tibial osteotomy: A biomechanical study using porcine's tibia

Purpose

We aimed to investigate whether a plate adapted to the anatomy of the proximal medial porcine's tibia would provide maintenance of the anterior gap (AG), posterior gap (PG) and posterior tibial slope (PTS).

Methods

Twenty-seven porcine tibias were biomechanically evaluated by performing MOWHTO and placing TOMOFIX (n = 9), AC plate (n = 9) and TriS (n = 9) anteromedially. Cyclic testing (800 N, 2000 cycles, 0.5 Hz) was performed to investigate the PTS over time for MOWHTO. The particular displacement calculated from the maximum to the minimum point with the load-displacement curve along the mechanical axis during cyclic testing, the final AG and PG changes at the osteotomy site, the increased PTS calculated by subtracting AG from PG after 2000 cycles were compared among the three groups. The displacement was evaluated by repeated-measures analysis of variance (ANOVA), and changes in AG and PG and increased PTS were evaluated by one-way ANOVA. The sample size for α and β errors were <0.05 and <0.20, and the effect size was 0.64 for one-way ANOVA and 0.49 for repeated-measures ANOVA.

Results

There were no significant differences in displacement among the groups. A significant difference was observed in the AG (p = 0.044) and PG (p = 0.0085) changes. There were no significant differences in increased PTS among the groups.

Conclusion

When anteromedially placed, the AC plate and TriS resulted in significant maintenance of AG and PG compared with that of TOMOFIX in MOWHTO after cyclic loading.

Level of Evidence

Level Ⅳ.

Biomechanical comparisons of plate placement for medial tibial plateau fractures (Schatzker type IV): A biomechanical study using porcine tibias

INTRODUCTION

Biomechanical studies on medial tibial plateau fractures (MTPFs) (Schatzker classification type IV) are currently few, while studies using locking plates (LPs) placed on medial proximal tibias are unavailable. Hence, we compared the biomechanical properties of plate osteosynthesis at the medial and anteromedial placements using large- and small-fragment LPs in porcine bones.

MATERIALS AND METHODS

MTPFs were internally fixed using LPs on 40 porcine tibias. Specimens were equally divided into four groups: medial placement using a large-fragment LP (LPs for the medial (LM) group), anteromedial placement using a large-fragment LP (LAM group), medial placement using a small-fragment LP (SM group), and anteromedial placement using a small-fragment LP (SAM group). The translation patterns of the constructs in each group were examined by cycling loading test (displacement and translation along the mechanical axis at 10-100, 100-500, 500-1000, 1000-1500, and 1500-2000 cycles). Then, articular gaps and step-off changes after 2000 cycles were compared among the four groups.

RESULTS

One-way analysis of variance (ANOVA) revealed no significant differences in displacement and translation during cyclic loading. One-way ANOVA followed by post hoc analysis revealed that the anterior gap was lower in LPs for the medial (LM) than in SM (P = 0.029) and SAM (P = 0.0026). The central gap was also lower in LM than in SM (P = 0.042) and SAM (P < 0.001), and it was lower in LAM than in SAM (P = 0.047). Likewise, the posterior gap was lower in LM than in LAM (P = 0.025) and SAM (P < 0.001). Furthermore, the central step-off of SAM was higher than that of LM, LAM, and SM (P < 0.001, P = 0.0014, and P = 0.0077, respectively). The posterior step-off was lower in LM than in SAM and LAM (P = 0.037 and P < 0.001), and it was also lower in SM than in SAM (P = 0.0082).

CONCLUSION

Medial LP placement for MTPFs in porcine bones resulted in significantly lower posterior step-offs after cyclic loading than anteromedial placement, and large-fragment LPs for MTPFs caused significantly lower fracture gaps in the central articular after cyclic loading than small-fragment LPs.

Factors Causing Unintended Sagittal and Axial Alignment Changes in High Tibial Osteotomy: Comparative 3-Dimensional Analysis of Simulation and Actual Surgery

BACKGROUND

Unintended secondary changes in the posterior tibial slope (PTS) and tibial torsion angle (TTA) may occur after medial open-wedge high tibial osteotomy (MOWHTO). In surgical procedures using patient-specific instruments (PSIs), it is essential to reproduce the PTS and TTA that were planned in simulations.

PURPOSE

To analyze the factors causing unintended sagittal and axial alignment changes after MOWHTO.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Overall, 63 patients (70 knees) who underwent MOWHTO using a PSI between June 2020 and June 2023 were retrospectively reviewed. Preoperative and postoperative computed tomography scans were 3-dimensionally reconstructed. Simulated osteotomy was performed so that the weightbearing line could pass through the target point. A PSI gapper was 3-dimensionally printed to fit the posteromedial corner of the osteotomy gap in the simulated HTO model. After MOWHTO using the PSI gapper, the actual postoperative model was compared with the preoperative or simulation model. This assessment included PTS, TTA, hinge axis, and osteotomy-related parameters. Cortical breakage around the lateral hinge was evaluated to assess stability.

RESULTS

The mean PTS and TTA did not change in the simulation. However, significant changes were observed in the actual postoperative PTS and TTA (change, -2.4°± 2.2° and -3.9°± 4.7°, respectively). The PTS was reduced, while the TTA decreased with internal rotation of the distal fragment. The difference in the axial hinge axis angle (AHA) between the simulation and actual surgery was the factor most correlated with the difference in the PTS (r = 0.625; P < .001). In regression analysis, the difference in the AHA was the only factor associated with the difference in the PTS (β = 0.558; P = .001), and there were no factors that showed any significant associations with the difference in the TTA. In subgroup analyses for the change in the TTA, the correction angle and anterior osteotomy angle were significantly higher in the more internal rotation group (P = .023 and P = .010, respectively). The TTA change was significantly higher in the unstable group with lateral cortical breakage (P = .018). The unstable group was more likely to show an internal rotation of ≥5° (odds ratio, 5.0; P = .007).

CONCLUSION

The AHA was associated with a difference in the PTS between the simulation and actual surgery. The change in the TTA was caused by a combination of multiple factors, such as a large correction angle and anterior osteotomy angle, but mainly by instability of the lateral cortical hinge.

Retro-tubercular Biplanar Medial Opening-Wedge High Tibial Osteotomy Results in Superior Patellofemoral Alignment Versus Supra-tubercular Osteotomy

PURPOSE

To compare the changes in patellofemoral (PF) joint alignment, focusing on multiple planes, between two different types of biplanar medial opening-wedge high tibial osteotomy (OWHTO).

METHODS

Patients who underwent biplanar OWHTO between July 2017 and May 2021 were retrospectively evaluated. They were allocated to either the supra-tubercular (ST)- or retro-tubercular (RT)-OWHTO group. The following radiologic parameters were compared between the two groups: 1) weight-bearing line ratio (WBLR), 2) patellar height, 3) posterior tibial slope (PTS), 4) tibial tubercle-trochlear groove (TT-TG) distance, 5) TT-TG angle, and 6) femoral shaft-patellar tendon (FS-PT) angle. Clinical outcomes and the minimal clinically important difference (MCID) were also evaluated.

RESULTS

In total, 104 knees that underwent ST-OWHTO and 105 knees that underwent RT-OWHTO were evaluated. The patellar height significantly decreased only after ST-OWHTO (P < .001). The TT-TG distance and FS-PT angle significantly increased, more after ST-OWHTO than RT-OWHTO (mean change value: 5.72 mm vs 1.91 mm; P < .001 for TT-TG distance; and 4.72° vs 1.80°; P < .001 for FS-PT angle). The TT-TG angle increased significantly after ST-OWHTO (mean change value: 7.62°; P < .001) but decreased after RT-OWHTO mean change value: -4.30°; P < .001). The PTS more increased after RT-OWHTO than after ST-OWHTO (mean change value: 0.91° vs 1.69°; P = .003). Clinical outcomes in both groups improved postoperatively, and no significant differences were observed between the groups.

CONCLUSIONS

RT-OWHTO resulted in lesser changes in multiplane PF joint alignment than ST-OWHTO. However, no difference was observed in clinical outcomes between both groups, and PTS increased after RT-OWHTO. Therefore, these aspects of RT-OWHTO should also be considered.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

3D osteotomies-improved accuracy with patient-specific instruments (PSI)

PURPOSE

Three-dimensional (3D) printed patient-specific instruments (PSI) have been introduced to increase precision and simplify surgical procedures. Initial results in femoral and tibial osteotomies are promising, but validation studies on 3D planning, manufacturing of patient-specific cutting blocks and 3D evaluation of the attained results are lacking.

METHODS

In this study, patient-specific cutting blocks and spacers were designed, fabricated, and used to perform a high tibial osteotomy (HTO). After segmentation of CT data sets from 13 human tibiae, 3D digital planning of the HTO was performed with a medial opening of 8 mm. These 3D models were used to fabricate patient-specific cutting blocks and spacers. After the surgical procedure, accuracy was evaluated measuring 3D joint angles and surface deviations.

RESULTS

The lowest mean deviation was found to be 0.57° (SD ± 0.27) for the MPTA. Medial and lateral tibial slope deviated from the 3D planning by an average of 0.98° (SD ± 0.53) and 1.26° (SD ± 0.79), respectively, while tibial torsion deviated by an average of 5.74° (SD ± 3.24). Color analysis of surface deviations showed excellent and good agreement in 7 tibiae.

CONCLUSION

With 3D cutting blocks and spacers, the 3D planning of the HTO can be translated into reality with small deviations of the resulting joint angles. Within this study, the results of the individual steps are examined for errors and thus a critical evaluation of this new and promising method for performing patient-specific HTOs is presented.

Effect of plate position on tibial displacement and posterior tibial slope after cyclic loading in medial open wedge high tibial osteotomy: A biomechanical study using porcine tibia

BACKGROUND

Medial open wedge high tibial osteotomy is currently the most common osteotomy, but its complication is an increased posterior tibial slope over time. However, no study has clarified whether the plate position of medial open wedge high tibial osteotomy could reduce the increase in posterior tibial slope after cyclic loading.

METHODS

Fourteen porcine bones were biomechanically evaluated by performing medial open wedge high tibial osteotomy and placing TOMOFIX medially and anteromedially. Cyclic testing was performed to investigate the posterior tibial slope over time for medial open wedge high tibial osteotomy with medial or anteromedial plate. The displacement along the mechanical axis during cyclic testing from 10 to 100th, 100-500th, 500-1000th, 1000-1500th, and 1500-2000th cycles, and changes in anterior and posterior gaps after 2000 cycles were compared between plate position.

FINDINGS

There were no significant differences in displacement. A significant difference was found in posterior gap changes (-0.20 ± 0.84 mm in group of using medial plate, 1.07 ± 0.82 mm in group of using anteromedial plate) (P = 0.014), but none was found in anterior gap changes.

INTERPRETATION

Medial plate placement in medial open wedge high tibial osteotomy resulted in significantly less increased posterior tibial slope than anteromedial plate placement after cyclic loading.

Particulated Costal Hyaline Cartilage Allograft With Subchondral Drilling Improves Joint Space Width and Second-Look Macroscopic Articular Cartilage Scores Compared With Subchondral Drilling Alone in Medial Open-Wedge High Tibial Osteotomy

PURPOSE

To compare the articular cartilage regeneration based on second-look arthroscopy in patients who underwent medial open-wedge high tibial osteotomy (MOWHTO) combined with particulated costal hyaline cartilage allograft (PCHCA) implantation with those who underwent MOWHTO and subchondral drilling (SD). Moreover, we compared the clinical and radiographic outcomes between the groups.

METHODS

From January 2014 to November 2020, patients with full-thickness cartilage defect on the medial femoral condyle who underwent MOWHTO combined with PCHCA (group A) or SD (group B) were reviewed. Fifty-one knees were matched after propensity score matching. The status of regenerated cartilage was classified according to the International Cartilage Repair Society-Cartilage Repair Assessment (ICRS-CRA) grading system and Koshino staging system, based on second-look arthroscopic findings. Clinically, the Knee Injury and Osteoarthritis Outcome Score, the Western Ontario and McMaster Universities Osteoarthritis Index, and range of motion were compared. Radiographically, we compared the differences in the minimum joint space width (JSW) and change in JSW.

RESULTS

The average age was 55.5 years (range, 42-64 years), and the average follow-up period was 27.1 months (range, 24-48 months). Group A showed a significantly better cartilage status than group B based on the ICRS-CRA grading system and Koshino staging system (P < .001 and <.001, respectively). There were no significant differences in clinical and radiographic outcomes between groups. In group A, the minimum JSW at the last follow-up was significantly increased than that before surgery (P = .013), and a significantly greater increase in JSW was observed in group A (P = .025).

CONCLUSIONS

When performed with MOWHTO, the combination of SD and PCHCA was associated with superior articular cartilage regeneration on the ICRS-CRA grading and Koshino staging on second-look arthroscopy performed at a minimum of 2 years follow-up than SD alone. However, there was no difference in clinical outcomes.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Additional anteromedial staple fixation prevents changes in the posterior tibial slope in retrotuberosity bi-planar open-wedge high tibial osteotomy

PURPOSE

To compare the changes in posterior tibial slope (PTS) between retrotuberosity biplane open-wedge high tibial osteotomies (RT-OWHTOs) with and without additional anteromedial staple fixation.

METHODS

Seventy-nine and 77 cases of RT-OWHTOs without (Group N) and with (Group S) additional staple fixation, respectively, were retrospectively reviewed. All procedures were performed using a locking spacer plate. Demographics and preoperative knee condition were similar between the groups. Clinically, the Western Ontario and McMaster Universities Arthritis Index and range of motion were evaluated preoperatively and 2 years postoperatively. Radiographically, the mechanical axis (MA), medial proximal tibial angle (MPTA), and PTS were evaluated preoperatively and within 2 years postoperatively. Hinge fractures were investigated using computed tomography at 2 weeks postoperatively. PTS loss was defined as the difference between the corresponding values at 2 weeks and 2 years postoperatively. The incidence of PTS failure (PTS loss ≥  ± 3°) was also investigated.

RESULTS

The clinical results were not significantly different between groups N and S preoperatively and 2 years postoperatively. There were no significant differences in the MA, MPTA, and PTS between the groups preoperatively and 2 weeks postoperatively; changes in these variables did not differ significantly between the groups. The incidence of hinge fractures, all of which were categorized as Takeuchi type 1, did not differ significantly. PTS loss within 2 years postoperatively was significantly greater in group N than in group S (1.0° vs. 0.1°; p < 0.01). The incidence of the PTS failure was 16.5% (13/79) and 2.6% (2/77) in groups N and S, respectively (p < 0.01).

CONCLUSION

Additional anteromedial staple fixation could prevent changes in the PTS in RT-OWHTO. It is a simple method for preventing an increase in the PTS after RT-OWHTO.

LEVEL OF EVIDENCE

III.

Impacted bone allograft personalised by a novel 3D printed customization kit produces high surgical accuracy in medial opening wedge high tibial osteotomy: a pilot study

PURPOSE

Contemporary medial opening wedge high tibial osteotomy (MOWHTO) still seems to struggle with inconsistent accuracy outcomes. Our objective was to assess surgical accuracy and short-term clinical outcomes when using 3D planning and a patient-specific instrumentation (PSI) kit to prepare customized bone allografts.

METHODS

Thirty subjects (age 48y ± 13) were included in a double-center prospective case series. A low-dose CT-scan was performed to generate 3D bone models, a MOWHTO was simulated, and PSI was designed and 3D printed based on the complementary negative of the planned osteotomy gap. Clinical outcome was assessed at two, four, 12 weeks and one year using NRS, KOOS, UCLA activity score, EQ-5D and anchor questions. A linear-mixed model approach was implemented for data analysis.

RESULTS

Preoperative 3D values were 175.0° ± 2.2 mechanical tibiofemoral angle (mTFA), 85.0° ± 3.0 medial proximal tibial angle (MPTA), and 94.1° ± 3.4 medial posterior tibial slope (MPTS). Target planning ranged from slight varus to the lateral tibial spine (slight valgus). Postoperative 3D analysis showed an accuracy of 1.1° ± 0.7 ΔMPTA (p = 0.04) and 1.2° ± 1.2 ΔMPTS (p = 0.11). NRS decreased from baseline 6.1 ± 1.9 to 2.7 ± 1.9 at four weeks (p < 0.001) and 1.7 ± 1.9 at one year (p < 0.001). KOOS increased from 31.4 ± 17.6 to 50.6 ± 20.6 at 12 weeks (p < 0.001) and to 71.8 ± 15.6 at one year (p < 0.001).

CONCLUSION

The study suggests that 3D printed instrumentation to personalize structural bone allograft is a viable alternative method in MOWHTO that has the benefit of optimizing surgical accuracy while providing early and consistent pain relief after surgery.

Wear patterns in knee OA correlate with native limb geometry

Background: To date, the amount of cartilage loss is graded by means of discrete scoring systems on artificially divided regions of interest (ROI). However, optimal statistical comparison between and within populations requires anatomically standardized cartilage thickness assessment. Providing anatomical standardization relying on non-rigid registration, we aim to compare morphotypes of a healthy control cohort and virtual reconstructed twins of end-stage knee OA subjects to assess the shape-related knee OA risk and to evaluate possible correlations between phenotype and location of cartilage loss.

Methods: Out of an anonymized dataset provided by the Medacta company (Medacta International SA, Castel S. Pietro, CH), 798 end-stage knee OA cases were extracted. Cartilage wear patterns were observed by computing joint space width. The three-dimensional joint space width data was translated into a two-dimensional pixel image, which served as the input for a principal polynomial autoencoder developed for non-linear encoding of wear patterns. Virtual healthy twin reconstruction enabled the investigation of the morphology-related risk for OA requiring joint arthroplasty.

Results: The polynomial autoencoder revealed 4 dominant, orthogonal components, accounting for 94% of variance in the latent feature space. This could be interpreted as medial (54.8%), bicompartmental (25.2%) and lateral (9.1%) wear. Medial wear was subdivided into anteromedial (11.3%) and posteromedial (10.4%) wear. Pre-diseased limb geometry had a positive predictive value of 0.80 in the prediction of OA incidence (r 0.58, p &lt; 0.001).

Conclusion: An innovative methodological workflow is presented to correlate cartilage wear patterns with knee joint phenotype and to assess the distinct knee OA risk based on pre-diseased lower limb morphology. Confirming previous research, both alignment and joint geometry are of importance in knee OA disease onset and progression.

Increasing the posterior tibial slope lowers in situ forces in the native ACL primarily at deep flexion angles

High tibial osteotomy is becoming increasingly popular but can be associated with unintentional posterior tibial slope (PTS) increase and subsequent anterior cruciate ligament (ACL) degeneration. This study quantified the effect of increasing PTS on knee kinematics and in situ forces in the native ACL. A robotic testing system was used to apply external loads from full extension to 90° flexion to seven human cadaveric knees: (1) 200 N axial compressive load, (2) 5 Nm internal tibial + 10 Nm valgus torque, and (3) 5 Nm external tibial + 10 Nm varus torque. Kinematics and in situ forces in the ACL were acquired for the native and increased PTS state. Increasing PTS resulted in increased anterior tibial translation at 30° (1.8 mm), 60° (1.7 mm), and 90° (0.9 mm) flexion and reduced in situ force in the ACL at 30° (57.6%), 60° (69.8%), and 90° (75.0%) flexion in response to 200 N axial compressive load. In response to 5 Nm internal tibial + 10 Nm valgus torque, there was significantly less (39.0%) in situ force in the ACL at 90° flexion in the increased compared with the native PTS state. Significantly less in situ force in the ACL at 60° (62.8%) and 90° (67.0%) flexion was observed in the increased compared with the native PTS state in response to 5 Nm external tibial + 10 Nm varus torque. Increasing PTS affects knee kinematics and results in a reduction of in situ forces in the native ACL during compressive and rotatory loads at flexion angles exceeding 30°. In a controlled laboratory setting PTS increase unloads the ACL, affecting its natural function.

Effect of the sagittal osteotomy inclination angle on the posterior tibial slope change in high tibial osteotomy: three-dimensional simulation study

In performing medial open-wedge high tibial osteotomy, it is recommended not to alter the posterior tibial slope. However, it remains unclear whether the osteotomy inclination angle affects the posterior tibial slope in the sagittal plane. This study aimed to verify how anterior or posterior osteotomy inclination angle affects the tendency of change in the posterior tibial slope and to conduct quantitative analysis of the extent to which the posterior tibial slope changes according to the degree of the osteotomy inclination angle change in MOWHTO. Computed tomography images of 30 patients who underwent MOWHTO were collected. Three-dimensional models of preoperative original tibia were reconstructed, and virtual osteotomies were performed. The sagittal osteotomy inclination angles formed by the osteotomy line and the medial tibial plateau line were classified as positive in case of anteriorly inclined osteotomy and negative in case of posteriorly inclined osteotomy. Thirteen osteotomies were performed for each tibial model at intervals of 5° from - 30° to 30°. The posterior tibial slope was assessed, and the proportional relationship between the sagittal osteotomy inclination angle and the posterior tibial slope change was analyzed. The posterior tibial slope changed significantly after osteotomy (p < 0.001), except for the cases where the sagittal osteotomy inclination angles were 5°, 0°, and - 5°. Anteriorly and posteriorly inclined osteotomy caused increase and decrease in the posterior tibial slope, respectively. As the inclination angle increased by 1°, the posterior tibial slope increased by 0.079° in anterior inclination osteotomy, while in posterior inclination osteotomy, as the inclination angle decreased by 1°, the posterior tibial slope decreased by 0.067°. The osteotomy inclination angle in the sagittal plane significantly affected the posterior tibial slope. When there was an inclination angle occurred between the osteotomy line and the medial tibial plateau line in the sagittal plane, the posterior tibial slope changed after MOWHTO. The posterior tibial slope tended to increase in anteriorly inclined osteotomy and decrease in posteriorly inclined osteotomy. The change in the posterior tibial slope was proportionally related to the absolute value of the osteotomy inclination angle.

Patellofemoral Joint after Opening Wedge High Tibial Osteotomy: A Comparative Study of Uniplane versus Biplane Osteotomies

OBJECTIVE

To the best of our knowledge, there has been no comparative study of changes in radiographic parameters in the sagittal plane between biplane opening wedge high tibial osteotomy (OWHTO) with plate fixation and uniplane OWHTO with spacer implantation. The aim of the study was to compare sagittal radiographs between the procedures of biplane and uniplane OWHTOs in patients with genu varum and to investigate the impact on the patellofemoral joint.

METHODS

A retrospective study of 71 patients (58.0 ± 5.0 years of age, 58 females and 13 males) with varus-aligned medial compartment knee osteoarthritis treated with OWHTO was performed during the period from January 2016 to February 2019. Thirty-three patients underwent biplane osteotomy with plate fixation (biplane group), and 38 patients underwent uniplane osteotomy with absorbable wedged spacer fixation (uniplane group). Independent t tests were used to compare the two groups according to the preoperative and postoperative radiographic parameters of hip-knee-ankle (HKA) angle, posterior tibial slope (PTS), tibial tubercle prominence (TTP), Caton-Deschamps (CD) index, and Blackburne-Peel (BP) index. During the last follow-up assessment, patients were asked to rate their patellofemoral joint status using the Samsung Medical Center (SMC) patellofemoral (PF) scoring system. The visual analog scale (VAS) was also used to rate knee joint pain when walking.

RESULTS

There was no significant difference between the two groups in any of the demographic, clinical, or radiological characteristics at baseline (p > 0.05). Comparisons of postoperative sagittal radiographic parameters between patients in the uniplane group and patients in the biplane group showed significant differences in the PTS (13.4° vs 16.6°, t = 4.465, p < 0.001), TTP (9.0 mm vs 4.2 mm, t = 7.950, p < 0.001), and CD index (0.81 vs 0.70, t = 4.035, p < 0.001). At the final follow-up assessment (minimum, 2 years), the SMC PF function score was significantly lower in patients in the uniplane group than in patients in the biplane group (27.8 vs. 32.1, t = 2.458, p = 0.016), but there were no significant differences in the SMC PF pain score or VAS score (p > 0.05).

CONCLUSION

The essential difference in the postoperative sagittal radiographic changes between biplane and uniplane OWHTO was the tibial tubercle prominence, indicating the posterior displacement of the tibial tubercle. Uniplane OWHTO may yield better function of the patellofemoral joint compared to biplane OWHTO.

[Short-term effectiveness of high tibial osteotomy combined with arthroscopic surgery for knee varus arthritis and the results of secondary arthroscopic exploration]

OBJECTIVE

To investigate the effectiveness of high tibial osteotomy (HTO) combined with arthroscopic surgery to treat medial compartment knee osteoarthritis (KOA) and secondary arthroscopic exploration to evaluate the outcome of cartilage and meniscus.

METHODS

A clinical data of 57 patients with medial compartment KOA with varus deformity of lower extremities admitted between August 2014 and October 2018 were retrospectively analyzed. There were 23 males and 34 females with an average age of 51.2 years (range, 41-63 years). The disease duration ranged from 2 to 8 years, with an average of 4.7 years. The preoperative femorotibial angle was (179.86±4.69)°, the relative position of the lower limb mechanical axis passing through the tibial plateau was 24.21%±6.98%, and the posterior slope of the tibial plateau was (5.23±1.45)°. The Kellgren-Lawrence grade of knee joint was grade Ⅱ in 22 cases and grade Ⅲ in 35 cases. The preoperative Hospital for Special Surgery (HSS) score, Lysholm score, and visual analogue scale (VAS) score were 59.1±7.3, 48.8±7.6, and 6.2±1.1, respectively. Arthroscopic exploration was performed during the operation to record the articular cartilage degeneration in the weight-bearing area of the medial compartment (Outerbridge grade Ⅰ in 18 cases, grade Ⅱ in 30 cases, and grade Ⅲ in 9 cases) and the condition of the medial meniscus injury, and the corresponding treatment was performed. The coronal force line was adjusted according to the preoperative Kellgren-Lawrence grade of the knee joint during the operation. After operation, the relative position of the lower limb mechanical axis passing through the tibial plateau, the femorotibial angle, and the posterior slope of the tibial plateau were measured; the Kellgren-Lawrence grade of the knee joint was recorded; the Outerbridge grade of articular cartilage degeneration and the meniscus outcome were evaluated by combining with the MRI of the knee joint at 1 year after operation and the second arthroscopic exploration when the internal fixator was removed. The function and pain of the knee were evaluated by Lysholm score, HSS score, and VAS score.

RESULTS

All the 57 patients were followed up 36-58 months with an average of 42.1 months. Incisions healed by first intention, and no neurovascular injury, intraarticular or hinge fractures occurred during operation, and no postoperative complications such as deep vein thrombosis of lower limbs and internal fixation failure occurred. All the osteotomy sites healed at 3 months after operation. At 1 year after operation, the internal fixator was removed, and the second arthroscopic exploration showed that there were 15 cases of Outerbridge grade Ⅰ, 31 cases of grade Ⅱ, and 11 cases of grade Ⅲ in the weight-bearing area of the medial compartment, and there was no significant difference when compared with preoperative grade ( Z=31.992, P=0.997); there was no cartilage degeneration in other compartments. Meniscus healing was seen in the injured meniscus, and no injury was seen in the normal meniscus. At last follow-up, there were 19 cases of Kellgren-Lawrence grade Ⅱ and 38 cases of grade Ⅲ, and there was no significant difference when compared with preoperative grade ( Z=49.049, P=0.764). The relative position of the lower limb mechanical axis passing through the tibial plateau was 59.16%±2.87%, and the femorotibial angle was (171.54±3.39)°, which significantly improved when compared with those before operation ( P<0.001). The posterior slope of the tibial plateau was (5.65±1.22)°, which was not significantly different from that before operation ( t=-1.673, P=0.096). The HSS score, Lysholm score, and VAS score were 82.3±7.7, 83.4±6.4, and 1.6±1.1 respectively, which were significantly different from those before operation ( P<0.001).

CONCLUSION

HTO combined with arthroscopic surgery for medial compartment KOA with varus deformity of lower extremities can effectively improve the force line of lower extremities, relieve pain symptoms, and improve joint function, with satisfactory short-term effectiveness, and without significant progress in articular cartilage or meniscus injury after operation.

Distal tibial tubercle osteotomy can lessen change in patellar height post medial opening wedge high tibial osteotomy? A systematic review and meta-analysis

Objective

Medial opening wedge high tibial osteotomy (MOWHTO) is a mainstream surgical method for treating early medial compartment knee osteoarthritis. Undesirable sequelae such as patella infera may happen following tuberosity osteotomy. We conducted this systematic review and meta-analysis to compare the change in patellar position after proximal tibial tubercle osteotomy (PTO) versus distal tibial tubercle osteotomy (DTO) intervention.

Methods

The 11 studies were acquired from PubMed, Medline, Embase and Cochrane Library. The data were extracted by two of the coauthors independently and were analyzed by RevMan5.3. Mean differences, odds ratios and 95% confidence intervals were calculated. Cochrane Collaboration’s Risk of Bias Tool and Newcastle–Ottawa Scale were used to assess risk of bias.

Results

Eleven observational studies were assessed. The methodological quality of the trials ranged from moderate to high. The pooled results of postoperative patellar height (Caton-Deschamps index and Blackburne-Peel index) and postoperative complications showed that the differences were statistically significant between PTO and DTO interventions. Patellar index ratios decreased significantly in the PTO groups, and 12 (9.2%) complications under DTO surgery and 2 (1.6%) complications under PTO surgery were reported. The differences of postoperative posterior tibial slope (angle) was not statistically significant, but postoperative posterior tibial slope of both groups increased. Sensitivity analysis proved the stability of the pooled results and the publication bias was not apparent.

Conclusions

DTO in MOWHTO maintained the postoperative patellar height, and clinically, for patients with serious patellofemoral osteoarthritis, DTO can be preferred. Postoperative complications are easily preventable with caution. In view of the heterogeneity and small sample size, whether these conclusions are applicable should be further determined in future studies.

Considerations of the Posterior Tibial Slope in Anterior Cruciate Ligament Reconstruction: a Scoping Review

PURPOSE OF REVIEW

The significance of posterior tibial slope (PTS) in the setting of anterior cruciate ligament (ACL) injury and reconstruction has been increasingly recognized in recent years. The purpose of this article is to review the biomechanical and clinical studies of PTS in conjunction with ACL injuries, providing an evidence-based approach for the evaluation and management of this patient population.

RECENT FINDINGS

Several biomechanical and clinical studies suggest that PTS > 12° may be considered with increased strain on the native ACL fibers (or reconstructed graft) and greater anterior tibial translation, predisposing patients to a recurrent ACL injury. The increased rates of ACL injury and graft failure seen in those with increased PTS have garnered attention to diagnose and surgically address increased PTS in the revision ACL setting; however, the role of a slope-reducing high tibial osteotomy (HTO) in primary ACL reconstruction (ACL-R) has yet to be defined. Various HTO techniques to decrease PTS during revision ACL-R have demonstrated promising outcomes, though conclusions are limited by the multifactorial nature of revision surgery and concomitant procedures performed. Recent evidence suggests that increased PTS is a risk factor for failure following ACL-R, which may be mitigated by a slope-reducing HTO. Further investigation is needed to elucidate abnormal PTS values and to determine appropriate indications for a slope-reducing HTO in primary ACL-R.

[Effect of knee suspension on posterior tibial slope after medial opening-wedge high tibial osteotomy]

OBJECTIVE

To investigate the effect of knee suspension during titanium plate fixation on postoperative posterior tibial slope (PTS) in knee osteoarthritis (KOA) with medial opening-wedge high tibial osteotomy (OWHTO).

METHODS

The clinical data of 47 patients with KOA treated by OWHTO between January 2019 and December 2020 was retrospectively analyzed. In 24 cases, the knee joint was suspended when titanium plate was fixed (research group), and in 23 cases, the knee joint was naturally straightened when titanium plate was fixed (control group). There was no significant difference in gender, age, side, body mass index, disease duration, preoperative visual analogue scale (VAS) score, American Hospital for Special Surgery (HSS) score, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score, Lysholm score, and preoperative PTS between the two groups ( P>0.05). PTS were measured at 1 day after operation and last follow-up, and were compared with that before operation. Before operation and at last follow-up, VAS score was used to evaluate the knee pain, HSS score, WOMAC score, and Lysholm score were used to evaluate the knee function.

RESULTS

The patients in both groups were followed up 13-24 months, with an average of 19.9 months. There was no complication such as incision infection, screw fracture, and deep venous thrombosis of lower limbs in two groups. At last follow-up, the VAS score, HSS score, WOMAC score, and Lysholm score in two groups were significantly improved when compared with those before operation ( P<0.05), but there was no significant difference between the two groups in the each score difference of before and after operation ( P>0.05). There was no significant difference in PTS at each time point before and after operation in the research group ( P>0.05), but PTS in the control group significantly increased at 1 day after operation and last follow-up ( P<0.05). PTS of the research group at 1 day after operation and last follow-up were significantly lower than those of the control group ( P<0.05).

CONCLUSION

OWHTO can effectively relieve knee pain and improve knee function in KOA, and the increase of postoperative PTS can be effectively avoided by suspending knee joint.

Extreme Hinge Axis Positions Are Necessary to Achieve Posterior Tibial Slope Reduction With Small Coronal-Plane Corrections in Medial Opening Wedge High Tibial Osteotomy

Background:

Both coronal- and sagittal-plane knee malalignment can increase the risk of ligamentous injuries and the progression of degenerative joint disease. High tibial osteotomy can achieve multiplanar correction, but determining the precise hinge axis position for osteotomy is technically challenging.

Purpose:

To create computed tomography (CT)–based patient-specific models to identify the ideal hinge axis position angle and the amount of maximum opening in medial opening wedge high tibial osteotomy (MOWHTO) required to achieve the desired multiplanar correction.

Study Design:

Descriptive laboratory study.

Methods:

A total of 10 patients with lower extremity CT scans were included. Baseline measurements including the mechanical tibiofemoral angle (mTFA) and the posterior tibial slope (PTS) were calculated. Virtual osteotomy was performed to achieve (1) a specified degree of PTS correction and (2) a planned degree of mTFA correction. The mean hinge axis position angle for MOWHTO to maintain an anatomic PTS (no slope correction) was 102.6° ± 8.3° relative to the posterior condylar axis (PCA). Using this as the baseline correction, the resultant hinge axis position and maximum opening were then calculated for each subsequent osteotomy procedure.

Results:

For 5.0° of mTFA correction, the hinge axis position was decreased by 6.8°, and the maximum opening was increased by 0.49 mm for every 1° of PTS correction. For 10.0° of mTFA correction, the hinge axis position was decreased by 5.2°, and the maximum opening was increased by 0.37 mm for every 1° of PTS correction. There was a significant difference in the trend-line slopes for hinge axis position versus PTS correction (P = .013) and a significant difference in the trend-line intercepts for maximum opening versus PTS correction (P < .0001).

Conclusion:

The mean hinge axis position for slope-neutral osteotomy was 102.6° ± 8.3° relative to the PCA. For smaller corrections in the coronal plane, more extreme hinge axis positions were necessary to achieve higher magnitudes of PTS reduction.

Clinical Relevance:

Extreme hinge axis positions are technically challenging and can lead to unstable osteotomy. Patient-specific instrumentation may allow for precise correction to be more readily achieved.

The validity and accuracy of 3D-printed patient-specific instruments for high tibial osteotomy: a cadaveric study

Objective

High tibial osteotomy (HTO) has been used for the treatment of patients with knee osteoarthritis. However, the successful implementation of HTO requires precise intraoperative positioning, which places greater requirements on the surgeon. In this study, we aimed to design a new kind of 3D-printed patient-specific instrument (PSI) for HTO, including a positioning device and an angle bracing spacer, and verify its effectiveness using cadaveric specimens.

Methods

This study included ten fresh human lower-limb cadaveric specimens. Computed tomography (CT) and X-ray examinations were performed to make preoperative plans. PSI was designed and 3D-printed according to the preoperative plan. Then, the PSI was used to guide HTO. Finally, we performed X-ray and CT after the operation to verify its validity and accuracy.

Results

The PSI using process was adjusted according to the pre-experimental procedure in 1 case. Hinge fracture occurred in 1 case. According to X-rays of the remaining eight cadaveric specimens, no statistically significant difference was noted between the preoperative planning medial proximal tibial angle (MPTA) and postoperative MPTA (P > 0.05) or the preoperative and postoperative posterior slope angle (PSA) (P > 0.05). According to the CT of 10 cadaveric specimens, no statistically significant difference was noted between the design angle and actual angle, which was measured according to the angle between the osteotomized line and the cross section (P > 0.05). The gap between the designed osteotomy line and the actual osteotomy line was 2.09 (0.8 ~ 3.44) mm in the coronal plane and 1.58 (0.7 ~ 2.85) mm in the sagittal plane.

Conclusion

This 3D-printed PSI of HTO accurately achieves the angle and position of the preoperative plan without increasing the stripping area. However, its use still requires a certain degree of proficiency to avoid complications, such as hinge fracture.

Use of a suspended and straightened knee joint position when fixing steel plates can prevent the increase in postoperative posterior tibial slope after open‑wedge high tibial osteotomy

BACKGROUND

Posterior tibial slope (PTS) increases after medial open-wedge high tibial osteotomy (OWHTO) is challenging for patients. This study aims to determine whether use of a suspended and straightened knee joint position during the fixing of steel plates can prevent an increase in the PTS after OWHTO.

METHODS

This study retrospectively analyzed 112 subjects (122 knees) [34 males, 78 females; mean age 59.1 ± 6.6 (range 48-76) years; mean body mass index 28.06 ± 3.61 kg/m²] who underwent OWHTO. A total of 78 knees that were suspended and extended by placing a sterile cloth ball under the ipsilateral ankle during the fixing of steel plates comprised the suspended and straightened knee joint position (SSP) group, and 44 knees that were kept naturally straightened without placing a sterile cloth ball under the ipsilateral ankle during the fixing of steel plates comprised the naturally straightened knee joint position (NSP) group. Patients were clinically assessed according to the visual analog pain scale (VAS), the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index, the Knee Society Scores (KSS) knee and function scores, the Hospital for Special Surgery (HSS) knee scores and the Lysholm knee scores. Radiological assessment was performed according to the changes in the PTS between preoperation, 1-day postoperation, and the final follow-up periods. Ultimately, the difference in postoperative PTS changes between the two groups was statistically analyzed. The median follow-up period was 2.2 years (range 1.6-3.7 years).

RESULTS

In the final follow-up period, significant improvements were observed in the clinical VAS scores, WOMAC scores, KSS knee and function scores, HSS scores and the Lysholm knee scores in both groups (P < 0.001), and no difference was found between the two groups. Radiological assessment showed that there was no statistical difference in the preoperative PTS between the two groups. The 1-day postoperative PTS and the most recent follow-up PTS were significantly greater than the preoperative PTS in the NSP group (t = - 3.213, - 6.406, all P < 0.001), but no significant increase was seen in the SSP group (P > 0.05). The increase in PTS in the NSP group was significantly greater than that in the SSP group at the 1-day postoperative (t = 2.243, P = 0.030) and final follow-up periods (t = 6.501, P < 0.001).

CONCLUSIONS

For OWHTO, the use of a suspended and straightened knee joint position rather than a naturally straightened knee joint position during the fixing of steel plates could effectively prevent the increase in postoperative PTS.

LEVEL OF EVIDENCE

Retrospective Study Level III.

[Comparison of two osteotomies in the treatment of medial compartment osteoarthritis]

Objective

To compare the effectiveness of modified distal tibial tubercle-high tibial osteotomy (DTT-HTO) and open-wedge HTO (OWHTO) in the treatment of medial compartment osteoarthritis.

Methods

A clinical data of 80 patients with medial compartment osteoarthritis treated with HTO between January 2016 and January 2019 was retrospectively analyzed, including 40 patients treated with DTT-HTO (DTT-HTO group) and 40 patients treated with OWHTO (OWHTO group). There was no significant difference in gender, age, body mass index, affected side, disease duration, Kellgren-Lawrence grading of osteoarthritis, and preoperative knee society score (KSS), Hospital for Special Surgery (HSS) score, knee joint visual analogue scale (VAS) score, hip-knee-ankle angle (HKA), posterior tibial slope (PTS), weight-bearing line ratio (WBL), Blackburne-Peel index (BPI), Caton-Deschamps index (CDI), and Insall-Salvati index (ISI) between the two groups ( P>0.05). The operation time, incision length, bleeding volume, hospital stay, and complications in both groups were recorded. The KSS, HSS, and VAS scores were used to evaluated the effectiveness. A self-made questionnaire was used to evaluate the recovery of low-impact sports ability of the knee. X-ray films were used to observe the osteotomy healing and measure the HKA, PTS, WBL, and the patellar height indexes (BPI, CDI, ISI).

Results

All operations successfully completed in both groups. The OWHTO group operated longer than the DTT-HTO group ( P<0.05). There was no significant difference in the incision length, bleeding volume, and hospital stay between the two groups ( P>0.05). All incisions healed by first intention in both groups. There were 2 cases of lateral hinge fractures in the OWHTO group, and 1 case of lateral hinge fracture and 2 cases of tibial plateau fractures in the DTT-HTO group. No other complications occurred. The patients in both groups were followed up 2-4 years with an average of 2.8 years. The HSS, KSS, and VAS scores in both groups significantly improved after operation when compared with preoperative scores ( P<0.05). All scores gradually improved with the time and there were significant differences between different time points ( P<0.05). The HSS, KSS, and VAS scores were significantly better in the DTT-HTO group than in the OWHTO group at 3 months after operation ( P<0.05). There was no significant difference between the two groups at 6 months, 1 year, and 2 years ( P>0.05). At 1 year, the low-impact sports ability of the OWHTO group was rated as excellent in 8 cases, general in 25 cases, and poor in 7 cases, and as excellent in 7 cases, general in 26 cases, and poor in 7 cases of the DTT-HTO group. There was no significant difference between the two groups ( Z=-0.715, P=0.475). X-ray film reexamination showed that the osteotomies healed in both groups. The healing time was (4.52±1.23) months in the OWHTO group, and (4.23±1.56) months in the DTT-HTO group, showing no significant difference ( t=0.923, P=0.359). At immediate after operation, the HKA and WBL of the two groups significantly improved when compared with the preoperative values ( P<0.05). However, the pre- and post-operational difference was not significant between the two groups ( P>0.05). The PTS of the OWHTO group was significantly higher than preoperative value ( P<0.05), while the PTS of the DTT-HTO group was lower than preoperative value ( P>0.05). The pre- and post-operational difference between the two groups was significant ( P<0.05). BPI and CDI in the OWHTO group were significantly lower than preoperative values ( P<0.05), but there was no significant difference in ISI when compared with preoperative value ( P>0.05). There was no significant difference in the BPI, CDI, and ISI of the DTT-HTO group between pre- and post-operation ( P>0.05). The pre- and post-operational differences of BPI and CDI between the two groups were significant ( P<0.05), and there was no significant difference in the pre- and post-operational difference of ISI ( P>0.05).

Conclusion

The two osteotomies in the treatment of medial compartment osteoarthritis can significantly change the varus deformity and achieve satisfactory effectiveness. The early functional recovery of DTT-HTO is faster, which can avoid the increased PTS and patellar baja of traditional OWHTO. However, neither of the two surgical procedures can restore the patient's ideal low-impact sports ability of the knee.

Effect of the Osteotomy Inclination Angle in the Sagittal Plane on the Posterior Tibial Slope of the Tibiofemoral Joint in Medial Open-Wedge High Tibial Osteotomy: Three-Dimensional Computed Tomography Analysis

The posterior tibial slope of the tibiofemoral joint changes after medial open wedge high tibial osteotomy (MOWHTO), but little is known about the effect of the sagittal osteotomy inclination angle on the change in the posterior tibial slope of the tibiofemoral joint. The purpose of this study was to investigate the effect of the osteotomy inclination angle in the sagittal plane on changes in the posterior tibial slope after MOWHTO by comparing how anterior and posterior inclination affect the posterior tibial slope of the tibiofemoral joint. The correlation between the osteotomy inclination angle and the postoperative posterior tibial slope angle was also assessed. Between May 2011 and November 2017, 80 patients with medial compartment osteoarthritis who underwent MOWHTO were included. The patients were divided into two groups according to the sagittal osteotomy inclination angle on the 3D reconstructed model. Patients with an osteotomy line inclined anteriorly to the medial tibial plateau line were classified into group A (58 patients). Patients with posteriorly inclined osteotomy line were classified as group P (22 patients). In the 3D reconstructed model, the preoperative and postoperative posterior tibial slope, osteotomy inclination angle relative to medial tibial plateau line in sagittal plane, and gap distance and ratio of the anterior and posterior osteotomy openings were measured. The preoperative and postoperative hip-knee-ankle angle, weight-bearing line ratio, and posterior tibial slope were also measured using plain radiographs. In the 3D reconstructed model, the postoperative posterior tibial slope significantly increased in group A (preoperative value = 9.7 ± 2.9°, postoperative value = 10.7 ± 3.0°, p < 0.001) and decreased in group P (preoperative value = 8.7 ± 2.7°, postoperative value = 7.7 ± 2.7°, p < 0.001). The postoperative posterior tibial slope (group A = 10.7 ± 3.0°, group P = 7.7 ± 2.7°, p < 0.001) and posterior tibial slope change before and after surgery (group A = 1.0 ± 0.8°, group P = −0.9 ± 0.8°, p < 0.001) also differed significantly between the groups. The Pearson correlation coefficient was 0.875 (p < 0.001) for the osteotomy inclination angle, and multivariate regression analysis showed that the only significant factor among the variables was the sagittal osteotomy inclination angle (β coefficient = 0.216, p < 0.001). The posterior tibial slope changed according to the osteotomy inclination angle in the sagittal plane after MOWHTO. The postoperative posterior tibial slope tended to increase when the osteotomy line was inclined anteriorly with respect to the medial tibial plateau line but decreased when the osteotomy line was inclined posteriorly. To avoid inadvertent change of posterior tibial slope, close attention needs to be paid to maintaining the sagittal osteotomy line parallel to the medial joint line during MOWHTO.

Retro-Tubercle Biplanar Opening Wedge High Tibial Osteotomy Is Favorable for the Patellofemoral Joint But Not for the Osteotomized Tubercle Itself Compared With Supra-Tubercle Osteotomy

PURPOSE

To identify whether retro-tubercle opening-wedge high tibial osteotomy (RT-OWHTO) produces more favorable radiographic outcomes on patellofemoral joint alignment and clinical outcomes than supra-tubercle opening-wedge high tibial osteotomy (ST-OWHTO).

METHODS

From January 2017 to July 2018, patients who underwent biplanar OWHTO were allocated to 1 of 2 groups (ST-OWHTO and RT-OWHTO). Plain radiographs and computed tomography were used to analyze patellofemoral alignment and other radiologic parameters representing osteotomy configurations. Clinical outcomes were assessed using American Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index.

RESULTS

In total, 50 knees that underwent ST-OWHTO and 44 knees that underwent RT-OWHTO were enrolled. Patellar height was significantly decreased only after ST-OWHTO (Caton-Deschamps ratio: P = .007; Blackburne-Peel ratio: P = .012). Patellar tilt angle was decreased in both groups (P = .009 and .004, respectively). Postoperative posterior tibial slope (PTS) (P = .013), PTS (Δ) (P < .001), retro-tuberosity gap distance (P = .001), and retro-tuberosity tip distance (P = .001) were significantly larger in RT-OWHTO. Retro-tuberosity tip distance was significantly correlated with retro-tuberosity gap distance (P = .002), thickness of second plane osteotomy fragment (P = .027), and anterior osteotomy ratio (P = .031) in ST-OWHTO. In RT-OWHTO, it was significantly correlated with PTS (△) (P < .001), retro-tuberosity gap distance (P < .001), and sagittal angle of bi-planar osteotomy (P = .005). There were 2 cases of tibial tuberosity fracture, 9 cases of delayed union on second plane osteotomy and 5 cases of tuberosity protrusion in RT-OWHTO.

CONCLUSIONS

Although the RT-OWHTO technique maintains patellofemoral joint alignment, no difference in clinical outcome was detected. The RT-OWHTO has increased risk of tuberosity fracture, delayed union, and prominent tibial tuberosity. The surgeon should consider these negative aspects of the technique and consider adjusting additional stabilization.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Axial But Not Sagittal Hinge Axis Affects Posterior Tibial Slope in Medial Open-Wedge High Tibial Osteotomy: A 3-Dimensional Surgical Simulation Study

PURPOSE

The purpose of this 3-dimensional (3D) surgical simulation study was to investigate the effects of axial and sagittal hinge axes (hinge axes in the axial and sagittal planes) on medial and lateral posterior tibial slope (PTS) in medial open-wedge high tibial osteotomy (OWHTO), and evaluate the quantitative relationship between hinge axis and PTS change.

METHODS

Preoperative computed tomography data from patients with varus knee deformity were collected. A standard hinge axis (0°) and 12 different hinge axes (6 axial hinge axes and 6 sagittal hinge axes: ±10°, ±20°, and ±30°) were defined in a 3D surgical simulation of OWHTO using a bone model. The differences between before and after simulation surgery in medial and lateral PTS, medial proximal tibial angle, opening gap, and opening wedge angle were measured.

RESULTS

In total, 93 varus knees in 93 patients were included for study. Compared with the standard hinge axis, axial hinge axis significantly affected medial and lateral PTS (P < .001). In contrast, sagittal hinge axis had no significant effect on medial and lateral PTS (P > .05). Every 10° change in axial hinge axis with a mean coronal valgus correction of 10° might result in approximately 1.6° of alteration in PTS. Stepwise regression analysis showed that axial hinge axis is the most significant factors affecting PTS (β coefficient = 0.78, P < .001), followed by opening wedge angle (β coefficient = 0.36, P < .001) and gap ratio (β coefficient = 0.12, P < 0.001).

CONCLUSION

Based on our findings of 3D OWHTO simulation, axial hinge axis significantly influences medial and lateral PTS in OWHTO, but sagittal hinge axis has no effect on change in PTS. Every 10° change of axial hinge axis with a 10° coronal valgus correction caused approximately 1.6° change of PTS.

CLINICAL RELEVANCE

Hinge axis in the axial plane significantly affects PTS, but hinge axis in the sagittal plane has no effect on PTS. To maintain PTS, surgeons should make hinge axis at the true lateral position of the tibia in the axial plane. To intentionally alter PTS, an anterolateral axial hinge axis could be used to decrease PTS or a posterolateral axial hinge axis could be used to increase PTS. Opening wedge angle or gap ratio is also useful for intentional modification of PTS.

Editorial Commentary: Posterolateral Malposition of the Cortical Hinge During Medial Open-Wedge High Tibial Osteotomy Increases Posterior Tibial Slope: Incomplete Posterior Osteotomy May Shift the Hinge From Lateral to Posterolateral

Medial open-wedge high tibial osteotomy is an established treatment option for relatively young patients with medial-compartment osteoarthritis and varus deformity. This procedure is mainly focused on correcting coronal malalignment; however, it inevitably affects the posterior tibial slope (PTS) in the sagittal plane. The alteration of the PTS significantly affects knee stability and kinematics. When medial open-wedge high tibial osteotomy is performed, incomplete osteotomy of the posterior cortex could lead to a cortical hinge shift from the lateral side to the posterolateral side, which indicates the alteration of the axial hinge axis. In this case, there is a risk of an increasing PTS. In addition, incomplete posterior cortex osteotomy can lead to a lateral hinge fracture.

The Ideal Hinge Axis Position to Reduce Tibial Slope in Opening-Wedge High Tibial Osteotomy Includes Proximalization-Extension and Internal Rotation

PURPOSE

To evaluate the effect of the hinge axis position on the posterior tibial slope (PTS) in medial opening-wedge high tibial osteotomy.

METHODS

This study included adults with medial-compartment osteoarthritis who had computed tomography (CT) scans available that were amenable to Bodycad Osteotomy software analysis. Virtual osteotomies modeling a 10-mm medial opening-wedge gap were performed. The hinge axis was rotated internally and externally and was proximalized-extended and distalized-flexed with respect to the anterior tibial cortex for 5°, 10°, 15°, and 20°. Each resultant PTS was recorded and compared with the results obtained from the true lateral hinge position and with the preoperative PTS.

RESULTS

Computed tomography scans from 10 patients were used. Strong linear correlations were found with each hinge axis position change and the resultant PTS. The trend-line differences were statistically significant by single-factor analysis of variance (P < .001). The PTS decreased for an anterolateral hinge, whereas it increased for a posterolateral hinge. Linear regression analysis showed that rotating the hinge axis by 9.0° externally or angulating the hinge axis by 21.8° of distalization-flexion would result in increasing the tibial slope by 1° whereas rotating the hinge axis by 8.7° internally or angulating the hinge axis by 21.6° of proximalization-extension would decrease the tibial slope by 1°.

CONCLUSIONS

Distalization-flexion and external rotation of the hinge axis position led to stepwise increases in the PTS, whereas proximalization-extension and internal rotation led to decreases in the PTS.

CLINICAL RELEVANCE

Our findings suggest that when performing medial opening-wedge high tibial osteotomy and aiming to decrease the PTS, the surgeon should aim to achieve maximal internal rotation (producing an anterolateral hinge), as well as proximalization-extension, of the hinge axis. This study quantifies and provides a model for the effect of the hinge axis position for a predetermined angular correction on the PTS.

The effect of the sagittal plane osteotomy inclination on the posterior tibial slope in medial open wedge HTO: experimental study with a square column model

Background

Medial open-wedge high tibial osteotomy (HTO) is an effective and safe treatment method for medial osteoarthritis of the knee. However, unintended changes in the posterior tibial slope (PTS) may occur. Several factors cause PTS alterations after medial open-wedge HTO; however, research on sagittal-plane osteotomy inclination (SPOI) in relation to the PTS is sparse. The purpose of this study was to evaluate whether the SPOI affects changes in the PTS after medial open-wedge HTO. The hypothesis was that an SPOI parallel to the PTS causes no change in the PTS after medial open-wedge HTO.

Methods

A square column model with a 10° posterior slope was produced using two three-dimensional (3D) programs and a 3D printer. Then, a series of medial open-wedge HTO procedures was performed on the square column model through virtual simulation using the two 3D programs, and an actual simulation was conducted using a 3D printer, a testing machine and a measurement system. The SPOI was divided into four types: ① SPOI 20° (posterior-inclined 10° osteotomy), ② SPOI 10° (osteotomy parallel to posterior slope), ③ SPOI 0° (anterior-inclined 10° osteotomy), and ④ SPOI − 10° (anterior-inclined 20° osteotomy). The correction angle was increased at intervals of 5° from 0° to 30°. The change in posterior slope was measured in the sagittal plane.

Results

The posterior slope was increased in SPOI 20° (posterior-inclined 10° osteotomy), maintained in SPOI 10° (osteotomy parallel to posterior slope), and decreased in SPOI 0° (anterior-inclined 10° osteotomy) and SPOI − 10° (anterior-inclined 20° osteotomy) based on the correction angle.

Conclusions

In this study using a square column model, the SPOI affected the change in the PTS, and an SPOI parallel to the PTS caused no change in the PTS after medial open-wedge HTO.

Clinical Outcomes and Complications During and After Medial Open-Wedge High Tibial Osteotomy Using a Locking Plate: A 3- to 7-Year Follow-up Study

Background:

Outcomes and complications at mid- or long-term follow-up after medial open-wedge high tibial osteotomy (MOWHTO) with the TomoFix locking plate have not been fully evaluated.

Purpose:

To evaluate the complications and midterm clinical outcomes after MOWHTO using a TomoFix.

Study Design:

Case series; Level of evidence, 4.

Methods:

Enrolled in this study were 80 patients (85 knees) who underwent MOWHTO with the TomoFix locking plate between 2009 and 2013. There were 66 women and 14 men, with a mean age of 61.5 years at the time of surgery. The diagnosis was medial osteoarthritis in 76 knees and spontaneous osteonecrosis of the knee in 9 knees. Metal removal and second-look arthroscopy were performed in all cases. Clinical and radiological examinations were performed at final follow-up after surgery (mean, 4.5 years).

Results:

The mean Japanese Orthopaedic Association score and Knee injury and Osteoarthritis Outcome Score improved significantly from pre- to postoperatively (P < .0001). The weightbearing line percentage shifted to pass through a point 67.7% lateral from the medial edge of the tibial plateau. The Caton-Deschamps index changed significantly from 0.88 to 0.66 at final follow-up (P < .0001). The mean posterior tibial slope changed significantly from 8.9° to 11.9° at final follow-up (P < .0001). Limb length was significantly increased after MOWHTO (10.3 mm; P < .0001). During plate removal, 14 locking screws were found to be broken in 9 knees (10.6%). The articular cartilage grade of the patellofemoral joint was significantly higher in the second arthroscopy than in the first arthroscopy (P < .0001). The cumulative rate of all complications was 41.2%, with major complications (ie, those requiring additional or extended treatment) in 24.7%.

Conclusion:

Postoperative outcome scores indicated significant improvement after MOWHTO, although the cumulative rate of all complications was 41.2% and the rate of major complications was 24.7%. These results indicate that MOWHTO with the TomoFix is a technically demanding procedure. Careful preoperative planning and meticulous surgical technique are needed to decrease the incidence of complications associated with MOWHTO.

Intraarticular Ligament Degeneration Is Interrelated with Cartilage and Bone Destruction in Osteoarthritis

Osteoarthritis (OA) induces inflammation and degeneration of all joint components including cartilage, joint capsule, bone and bone marrow, and ligaments. Particularly intraarticular ligaments, which connect the articulating bones such as the anterior cruciate ligament (ACL) and meniscotibial ligaments, fixing the fibrocartilaginous menisci to the tibial bone, are prone to the inflamed joint milieu in OA. However, the pathogenesis of ligament degeneration on the cellular level, most likely triggered by OA associated inflammation, remains poorly understood. Hence, this review sheds light into the intimate interrelation between ligament degeneration, synovitis, joint cartilage degradation, and dysbalanced subchondral bone remodeling. Various features of ligament degeneration accompanying joint cartilage degradation have been reported including chondroid metaplasia, cyst formation, heterotopic ossification, and mucoid and fatty degenerations. The entheses of ligaments, fixing ligaments to the subchondral bone, possibly influence the localization of subchondral bone lesions. The transforming growth factor (TGF)β/bone morphogenetic (BMP) pathway could present a link between degeneration of the osteochondral unit and ligaments with misrouted stem cell differentiation as one likely reason for ligament degeneration, but less studied pathways such as complement activation could also contribute to inflammation. Facilitation of OA progression by changed biomechanics of degenerated ligaments should be addressed in more detail in the future.