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Comparative outcomes of patient-specific instrumentation, the conventional method and navigation assistance in open-wedge high tibial osteotomy: A prospective comparative study with a two-year follow up

  • Author Footnotes
    1 These authors contributed equally to this work.
    Xiaohang Zhu
    Footnotes
    1 These authors contributed equally to this work.
    Affiliations
    Department of Orthopedics and Sports Medicine, The First Affiliated Hospital of Soochow University, Suzhou, PR China
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  • Author Footnotes
    1 These authors contributed equally to this work.
    Yufan Qian
    Footnotes
    1 These authors contributed equally to this work.
    Affiliations
    Department of Orthopedics and Sports Medicine, The First Affiliated Hospital of Soochow University, Suzhou, PR China
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  • An Liu
    Affiliations
    Department of Orthopedics and Sports Medicine, The First Affiliated Hospital of Soochow University, Suzhou, PR China

    Suzhou Medical College of Soochow University, Suzhou, PR China
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  • Pingcheng Xu
    Affiliations
    Department of Orthopedics, Wujiang Fourth People’s Hospital, Wujiang, Suzhou, PR China
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  • Jiong Jiong Guo
    Correspondence
    Corresponding author at: 188 Shizi Street, Suzhou 215006, PR China.
    Affiliations
    Department of Orthopedics and Sports Medicine, The First Affiliated Hospital of Soochow University, Suzhou, PR China
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  • Author Footnotes
    1 These authors contributed equally to this work.
Published:September 14, 2022DOI:https://doi.org/10.1016/j.knee.2022.08.013

      Abstract

      Background

      To compare and analyze the correction precision, clinical outcomes and complications among the three methods of performing open-wedge high tibial osteotomy (HTO), including patient-specific instrumentation (PSI), conventional method and navigation assistance.

      Methods

      In this prospective, single-center study, we randomly assigned patients with knee osteoarthritis in a 1:1:1 ratio to undergo Open-wedge high tibial osteotomy (OWHTO) with conventional method, navigation assistance or PSI. The primary outcome was the target/observed hip–knee–ankle (HKA) angle difference at 1 month postoperatively. Secondary outcomes were changes in the postoperative posterior tibial slope (PTS) at 1 month and clinical outcomes including knee pain on a visual analogue scale (ranging from 0 to 100, with higher scores indicating more severe pain), Lysholm and Western Ontario and McMaster Universities Osteoarthritis Index (ranging from 0 to 240) scores at 1 month, 6 months, 12 months, and 24 months.

      Results

      From 2017 through 2019, a total of 608 patients were screened; of those patients, 144 were enrolled, with 48 in each group. The primary outcome of the HKA difference was 2.6 ± 2.0° in the conventional group, 2.3 ± 1.5° in the navigation group and 0.6 ± 1.0° in the PSI group (P < 0.001). Secondary outcomes including changes in the postoperative PTS and clinical outcomes at 1 month, 6 months, and 12 months were in the same direction as the primary outcome. There were no significant differences in the complications among the three groups.

      Conclusions

      In the present study, none of the three methods showed superiority in objective correction precision and clinical outcomes at 2 years.

      Keywords

      1. Introduction

      Generally, knee osteoarthritis (KOA) is the most common cause of knee pain and dysfunction in the elderly. Osteoarthritis usually affects the medial compartment of the knee joint, which is related to misalignment [
      • Koh Y.G.
      • Kwon O.R.
      • Kim Y.S.
      • Choi Y.J.
      Comparative outcomes of open-wedge high tibial osteotomy with platelet-rich plasma alone or in combination with mesenchymal stem cell treatment: A prospective study.
      ]. High tibial osteotomy (HTO) is a treatment option for younger and/or physically active patients who have osteoarthritis (OA) of the medial compartment of the knee [
      • Sterett W.I.
      • Steadman J.R.
      • Huang M.J.
      • Matheny L.M.
      • Briggs K.K.
      Chondral resurfacing and high tibial osteotomy in the varus knee: survivorship analysis.
      ]. Favorable clinical outcomes of HTO can be expected when the accurate correction of the lower limb alignment is achieved. Compared with closed-wedge high tibial osteotomy, open-wedge high tibial osteotomy (OWHTO) showed better delicate correction. However, some discouraging results have been reported for correction accuracy in OWHTO [
      • Song J.H.
      • Bin S.I.
      • Kim J.M.
      • Lee B.S.
      Unstable lateral hinge fracture or occult complete osteotomy adversely affects correction accuracy in open-wedge high tibial osteotomy.
      ,
      • Nha K.W.
      • Kim H.J.
      • Ahn H.S.
      • Lee D.H.
      Change in posterior tibial slope after open-wedge and closed-wedge high tibial osteotomy: A meta-analysis.
      ].
      Preoperative planning in HTO is a critical step for achieving the desired correction and satisfactory outcome. One of the leading challenges in HTO is to perform axis correction as precisely as possible [
      • Brinkman J.M.
      • Lobenhoffer P.
      • Agneskirchner J.D.
      • Staubli A.E.
      • Wymenga A.B.
      • van Heerwaarden R.J.
      Osteotomies around the knee: Patient selection, stability of fixation and bone healing in high tibial osteotomies.
      ]. Another challenge in HTO is the maintenance of the posterior tibial slope (PTS). A meta-analysis by Nha et al. [
      • Nha K.W.
      • Kim H.J.
      • Ahn H.S.
      • Lee D.H.
      Change in posterior tibial slope after open-wedge and closed-wedge high tibial osteotomy: A meta-analysis.
      ] indicated that medial open-wedge HTO could lead to a 2.0° increase in PTS. Unintended slope changes could result in anteroposterior knee instability and increase stress on the cruciate ligaments [
      • Giffin J.R.
      • Vogrin T.M.
      • Zantop T.
      • Woo S.L.
      • Harner C.D.
      Effects of increasing tibial slope on the biomechanics of the knee.
      ,
      • Voos J.E.
      • Suero E.M.
      • Citak M.
      • Petrigliano F.P.
      • Bosscher M.R.F.
      • Citak M.
      • et al.
      Effect of tibial slope on the stability of the anterior cruciate ligament-deficient knee.
      ,
      • Yamaguchi K.T.
      • Cheung E.C.
      • Markolf K.L.
      • Boguszewski D.V.
      • Mathew J.
      • Lama C.J.
      • et al.
      Effects of anterior closing wedge tibial osteotomy on anterior cruciate ligament force and knee kinematics [published correction appears in Am J Sports Med. 2018 Feb;46(2):NP2].
      ]. Conventional radiography, navigation assistance and patient-specific instrumentation (PSI) are the three methods of planning [
      • Bae D.K.
      • Song S.J.
      • Yoon K.H.
      Closed-wedge high tibial osteotomy using computer-assisted surgery compared to the conventional technique.
      ]. The conventional planning technique uses standard X-ray and intraoperative fluoroscopy. However, the conventional method combined with imprecise preoperative planning can result in inaccurate wedge opening, often with the lateral hinge fracture and latent medial laxity [
      • Song S.J.
      • Bae D.K.
      Computer-assisted navigation in high tibial osteotomy.
      ,
      • Noyes F.R.
      • Goebel S.X.
      • West J.
      Opening wedge tibial osteotomy: The 3-triangle method to correct axial alignment and tibial slope [published correction appears in Am J Sports Med. 2006 Sep;34(9):1537].
      ]. Computer-navigated techniques and novel instrumentation have been introduced recently to improve HTO accuracy.
      PSI is an innovative surgical procedure that uses three-dimensional (3D) virtual surgical planning and custom-made PSI guides. The PSI rationale is to create a guiding instrument for the surfaces that fits well with the targeting region of the patient’s bone. The benefits include increased accuracy, decreased surgery time, and elimination of the need for extra devices or reference markers [
      • Clark A.N.
      • Hounat A.
      • O’Donnell S.
      • May P.
      • Doonan J.
      • Rowe P.
      • et al.
      Electromagnetic navigated versus conventional total knee arthroplasty—A five-year follow-up of a single-blind randomized control trial.
      ,
      • IJpma F.F.A.
      • Meesters A.M.L.
      • Merema B.B.J.
      • ten Duis K.
      • de Vries J.-P.
      • Banierink H.
      • et al.
      Feasibility of imaging-based 3-dimensional models to design patient-specific osteosynthesis plates and drilling guides.
      ]. However, to date there is a lack of studies that compare the precision and clinical outcomes among the three methods.
      The purpose of this study was to compare and analyze the correction precision and clinical outcomes among the three methods to perform open-wedge HTO, including PSI, the conventional method and navigation assistance. PSI, in open-wedge HTO, was hypothesized to improve correction precision and show better clinical outcomes than the conventional method or navigation assistance.

      2. Methods

      This prospective comparative study was designed to evaluate the superiority of PSI. The study was conducted in the First Affiliated Hospital of Soochow University over 24 months. Study protocols were approved by the local ethics committee, and all patients provided written informed consent (2017-152). From 1 June 2017 to 31 December 2019, 144 patients who met the following inclusion and exclusion criteria were enrolled in this study. The patient screening was performed in the outpatient department, where two experienced physicians evaluated patient eligibility for enrollment in this study. The inclusion criteria for surgical treatment reflected those outlined in the literature for this procedure: (1) age younger than 60 years; (2) radiographs showing grade I, II or III Kellgren–Lawrence symptomatic isolated medial knee compartment OA with stable knee; (3) failure of 3 months’ conservative treatment. The exclusion criteria were as follows: (1) history of fracture or periarticular osteotomy of the knee; (2) stiff knee (flexion contracture > 5° and/or flexion < 120°); (3) operated or non-operated ligament injury; (4) severe cardiocerebrovascular disease, liver or kidney disease, or endocrine disease; (5) chondromalacia of the lateral compartment or patellofemoral joint.
      Patients were randomly assigned in a 1:1:1 ratio to three groups according to surgical techniques: conventional method (Group 1), navigation assistant (Group 2) and PSI (Group 3) with the use of computer-generated permuted blocks. The randomization process was conducted by a research assistant who was blinded to the patients’ data. A total of 144 patients were enrolled, with each group comprising 48 knees.
      In the preoperative planning stage, the planned correction was first calculated by the surgeon using conventional radiographs (EOS weight-bearing long-leg, anterior–posterior (A/P) and lateral views). The target hip–knee–ankle (HKA) was based on disease severity. The mechanical HKA axis, PTS and osteoarthritis grade were assessed by Kellgren–Lawrence classification [
      • Ogata K.
      • Yoshii I.
      • Kawamura H.
      • Miura H.
      • Arizono T.
      • Sugioka Y.
      Standing radiographs cannot determine the correction in high tibial osteotomy.
      ]. Group 3 patients also underwent computed tomography (CT) (GE Light Speed VCT64) to plan the osteotomy and produce custom-made PSI guides. The CT scan protocol consisted of acquiring images centered on the femoral head, the knee (allowing the distal femur and 15 cm of the proximal tibia to be captured), and one centered over the ankle. The slice thickness was 0.625 mm for the knee and 2 mm for the hip and ankle. Afterwards the models were imported into the preoperative planning software Creo-CAD® (Johnson & Johnson, New Brunswick, NJ, USA). PSI and 3D print-outs of the native preoperative and simulative postoperative bones were manufactured (Figure 1). The virtual 3D position of the osteotomy line and plate (Tomofix) was confirmed by the surgeon ahead of production.
      Figure thumbnail gr1
      Figure 1(a) Transverse osteotomy; (b) ascending osteotomy; (c) patient-specific osteotomy guide; (d) patient-specific space block; (e) K-wire check; (f) plate placement.

      2.1 Surgical technique and postoperative rehabilitation

      Preoperative planning determined the target angular correction and HKA value. Surgery was performed with patients under general anesthesia and with tourniquet control. All patients were operated by a single senior surgeon who has extensive experience in OWHTO. Group 1 used the conventional techniques described by Miniaci [
      • Miniaci A.
      • Ballmer F.T.
      • Ballmer P.M.
      • Jakob R.P.
      Proximal tibial osteotomy. A new fixation device.
      ] or Hernigou [
      • Hernigou P.
      • Ovadia H.
      • Goutallier D.
      Modélisation mathématique de l'ostéotomie tibiale d'ouverture et tables de correction [Mathematical modelling of open-wedge tibial osteotomy and correction tables].
      ]. Group 2 used a standardized navigation protocol (Orthopilot® Navigation System, B-Braun-Aesculap®, Tuttlingen, Germany).
      Group 3 used PSI (Creo-CAD®, Johnson & Johnson, New Brunswick, NJ, USA). Patients were placed in a supine position by general methods. Application of a tourniquet and an anteromedial approach to the proximal tibia were performed. Bone detachment from the soft tissue was performed to identify prominent bony landmarks, which were integrated into the undersurface of the PSI for proper positioning. Next, the basic guide, serving as a registration tool between the preoperative planning and the intraoperative situation, was positioned and reference pins for the orientation of the following guides were inserted. Screw positions of the Tomofix Medial High Tibial Plate (Johnson & Johnson, New Brunswick, NJ, USA) were pre-drilled using integrated drill sleeves. Afterwards, the osteotomy guide was placed, and the osteotomy was performed in a PSI-navigated fashion by predefined osteotomy-plane position and orientation, as well as cutting depth. Using the reduction guide, predefined reduction was performed, and the Tomofix Medial High Tibial Plate could be placed over the pre-drilled screw holes; subsequently, the screws could be successively inserted. Fluoroscopy was used to confirm osteotomy and positioning of the implants. Skin was closed over a drain.[
      • Fucentese S.F.
      • Meier P.
      • Jud L.
      • Köchli G.-L.
      • Aichmair A.
      • Vlachopoulos L.
      • et al.
      Accuracy of 3D-planned patient specific instrumentation in high tibial open wedge valgisation osteotomy.
      ].
      Postoperative rehabilitation was the same for all the groups. The first day after surgery, isometric quadriceps, active ankle, and straight leg raising exercises began. The patients could move their knee from 0° to 90° after 2 weeks. Toe-touch weight bearing was allowed for 2 weeks after surgery, followed by partial weight bearing for the next 2 weeks. After radiographic evaluation of bone consolidation at the osteotomy site, full weight bearing was allowed at 4 weeks after surgery.

      2.2 Outcome measures

      All clinical and radiologic assessments were conducted by assessors blinded to treatment allocation. Full radiologic assessment was performed at 1-month follow up, with an EOS weight-bearing long-leg view to determine the HKA axis and PTS. To ensure the accuracy of the radiological outcomes, the analysis was performed independently by one radiologist and one orthopaedic surgeon, and both had over 10 years of experience in musculoskeletal imaging. All clinical outcomes were assessed at baseline, 1, 6, 12, and 24 months after surgery. The primary outcome was the target/observed HKA difference at 1 month after surgery. Secondary outcomes, which were analyzed at 1, 6, 12 and 24 months, were changes in the postoperative PTS and clinical outcomes including knee pain on a visual analogue scale (VAS) (ranging from 0 to 100, with higher scores indicating more severe pain), Lysholm and Western Ontario and McMaster Universities Osteoarthritis Index (ranging from 0 to 240, with higher scores indicating more severe symptoms of KOA) scores. Surgery-related adverse events were documented.

      2.3 Power calculation and statistical analysis

      Primary outcome was the difference in target/observed HKA. The sample size estimation was calculated using software (PASS 15.0). According to previous studies, the means of target/observed HKA in each group was expected to be 3, 2.5, 1 and the standard deviation was expected to be 2.5, 2.5, 1.5 [
      • Fucentese S.F.
      • Meier P.
      • Jud L.
      • Köchli G.-L.
      • Aichmair A.
      • Vlachopoulos L.
      • et al.
      Accuracy of 3D-planned patient specific instrumentation in high tibial open wedge valgisation osteotomy.
      ,
      • Saragaglia D.
      • Chedal-Bornu B.
      • Rouchy R.C.
      • Rubens-Duval B.
      • Mader R.
      • Pailhé R.
      Role of computer-assisted surgery in osteotomies around the knee.
      ,
      • Tardy N.
      • Steltzlen C.
      • Bouguennec N.
      • Cartier J.-L.
      • Mertl P.
      • Batailler C.
      • et al.
      Is patient-specific instrumentation more precise than conventional techniques and navigation in achieving planned correction in high tibial osteotomy?.
      ]. Thus, accepting a false-positive rate of 5% (α = 0.05) and a power of at least 90% (β = 0.10), we determined a theoretical minimum sample size of 114 patients. Considering the estimated 20% dropout rate, a total of 48 patients per group were required. Patient recruitment terminated in all groups when the required minimum number of patients was attained.
      Statistical analyses were performed using SPSS software, version 17.0 (SPSS, Chicago, IL, USA), with significance defined as P < 0.05. All data were tested for normality using the Kolmogorov–Smirnov test. The Chi-squared or Fisher’s exact tests were used for the categorical variables. The association of various categorical/classified data, including complications, within the three groups was analyzed using the χ2-test. Analysis of variance (ANOVA) was performed for the normally distributed parameters to compare their means, with analysis of variance for repeated measure used to compare the primary and secondary outcomes at different follow up periods. The least significant difference (LSD) test for post-hoc analysis was used to compare three independent groups over the same follow up period.

      3. Results

      3.1 Patients

      A total of 608 patients were screened, 464 patients were determined to be ineligible at the screening visit (Figure 2). The majority of patients who were excluded did not meet the radiological standards or combined with chondromalacia of the lateral compartment or patellofemoral joint. Fifty-eight eligible patients declined to participate in the trial at the screening visit. Thus, 144 patients were recruited into the study, 48 patients in each group. Twenty-eight patients (eight in the conventional group, 10 in the navigation group and 10 in the PSI group) could not be evaluated at the 2-year postoperative visit.
      Figure thumbnail gr2
      Figure 2Trial profile of patients randomized in study. The patients were randomized into three groups; 28 patients were lost to follow up during the 2-year follow up.
      The patient demographic data and characteristics are shown in Table 1. There were no significant differences in patient demographic data among the three groups. Likewise, no significant difference was detected in the Kellgren–Lawrence grade (P = 0.611) among the three groups.
      Table 1Demographic data.
      Group 1 (conventional)

      n = 40
      Group 2 (navigation)

      n = 38
      Group 3 (PSI)

      n = 38
      P
      Gender26F/14M28F/10M13F/25M0.765
      Mean age (years)51.252.451.80.563
      Mean BMI (kg/m2)27.127.528.20.492
      Side24L/16R19L/19R18L/20R0.758
      Kellgren–Lawrence grade0.611
       15 (12.5%)6 (15.8%)3 (7.8%)
       217 (42.5%)15 (39.4%)19 (50.0%)
       318 (45.0%)17 (44.7%)16 (42.1%)
      BMI, body mass index; F, female; L, left; M, male; R, right.

      3.2 Outcomes

      Regarding the primary outcome, the full radiologic assessment (weight-bearing long-leg, A/P and lateral views) taken at the 1-month follow up showed improved knee joint mechanics in all groups relative to their preoperative conditions (Table 2). The mean target/observed HKA difference was 2.6 ± 2.0° in the conventional group (Group 1), 2.3 ± 1.5° in the navigation group (Group 2) and 0.6 ± 1.0° in the PSI group (Group 3, P < 0.001). The target/observed HKA difference in the PSI group was significantly lower than in either the conventional group or the navigation group (P < 0.001) (Table 3).
      Table 2Clinical and radiologic data.
      Group 1

      n = 40
      Group 2

      n = 38
      Group 3

      n = 38
      P
      Lysholm score
       Preoperative56.4 ± 11.354.1 ± 14.556.3 ± 14.10.725
       1 month64.4 ± 10.864.1 ± 12.173.7 ± 10.00.018
       6 months76.2 ± 11.576.5 ± 11.785.9 ± 9.90.009
       12 month69.6 ± 10.570.4 ± 11.182.2 ± 9.1<0.001
       Last follow-up66.7 ± 10.968.1 ± 11.574.8 ± 9.10.039
      VAS
       Preoperative45.4 ± 6.944.5 ± 6.046.0 ± 5.70.576
       1 month35.8 ± 6.234.1 ± 7.230.8 ± 6.20.028
       6 months22.4 ± 6.521.8 ± 5.619.9 ± 5.50.013
       12 months19.1 ± 4.418.2 ± 5.515.1 ± 4.3<0.001
       Last follow-up20.5 ± 4.820.7 ± 6.218.2 ± 4.40.028
      WOMAC score
       Preoperative105.5 ± 15.8106.1 ± 17.4105.7 ± 17.10.659
       1 month94.8 ± 12.492.7 ± 13.681.1 ± 11.00.016
       6 months82.7 ± 11.982.5 ± 12.170.9 ± 11.10.012
       12 months87.1 ± 12.388.8 ± 12.174.6 ± 10.6<0.001
       Last follow-up89.2 ± 11.588.9 ± 11.789.1 ± 10.80.034
      HKA
       Preoperative175.6 ± 2.7173.7 ± 2.8175.9 ± 2.90.004
       Target182.3 ± 1.1182.8 ± 0.9183.4 ± 1.6<0.001
       1 month184.6 ± 2.0180.4 ± 1.6182.8 ± 1.9<0.001
       HKA difference2.6 ± 2.02.3 ± 1.50.6 ± 1.0<0.001
      PTS
       Preoperative8.2 ± 2.47.9 ± 2.28.3 ± 2.00.738
       1 month11.1 ± 2.910.4 ± 2.59.9 ± 2.70.171
       PTS difference2.9 ± 2.02.5 ± 2.11.6 ± 1.60.018
      Values are expressed as mean ± standard deviation unless otherwise indicated. Group 1, conventional high tibial osteotomy (HTO); Group 2, navigation; Group 3, patient-specific instrumentation (PSI). HKA, hip–knee–ankle angle; PTS, posterior tibial slope; VAS, visual analog scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.
      Table 3Post hoc tests (least significant difference).
      GroupGroupP95% CI
      HKA difference120.439−0.45 to 1.03
       1 month13<0.0011.28 to 2.76
      23<0.001−0.96 to 2.49
      PTS difference120.426−0.53 to 1.24
       1 month130.0060.38 to 2.16
      230.048−0.01 to 1.83
      Lysholm score
       1 month120.511−1.21 to 5.27
      130.027−10.51 to −6.23
      230.011−11.70 to −7.71
       6 months120.782−2.43 to 5.59
      130.007−12.74 to −7.52
      230.013−12.63 to −6.01
       12 months120.090−0.65 to 8.95
      130.002−15.41 to −9.80
      23<0.001−16.71to −10.79
       Last follow-up120.921−2.19 to 4.89
      130.045−9.57 to −6.17
      230.031−9.83 to −7.15
      VAS
       1 month120.257−2.01 to 2.99
      130.0162.64 to 6.69
      230.0282.17 to 6.04
       6 months120.475−1.31 to 2.18
      130.0063.05 to 6.87
      230.0122.93 to 6.74
       12 months120.754−1.87 to 2.58
      13<0.0013.82 to 8.27
      23<0.0013.39 to 7.99
       Last follow-up120.776−0.89 to 2.22
      130.0311.28 to 5.41
      230.0291.76 to 5.87
      WOMAC score
       1 month120.625−6.77 to 4.21
      130.0204.78 to 11.27
      230.0155.34 to 12.01
       6 months120.692−6.21 to 4.36
      130.0088.73 to 15.61
      230.0147.57 to 14.24
       12 months120.563−7.43 to 5.59
      130.00412.41 to 20.04
      23<0.00113.59 to 21.27
       Last follow-up120.787−4.87 to 4.82
      130.0374.01 to 10.85
      230.0314.29 to 11.19
      Group 1, conventional high tibial osteotomy (HTO); Group 2, navigation; Group 3, patient-specific instrumentation (PSI). CI, confidence interval; HKA, hip–knee–ankle angle; PTS, posterior tibial slope; VAS, visual analog scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.
      Secondary outcomes were generally in the same direction as the primary outcome (Figure 3, Figure 4). In Group 3, the mean clinical scores including VAS, Lysholm and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score improved from baseline at 1, 6, and 12 months of follow up, followed by a slight decline in clinical scores at the 24-month follow up, which was significant. However, the mean scores at 24 months were still better than that at baseline. At the 12-month follow up, the gap in clinical scores between the PSI group and the conventional group or the navigation group was at its highest (Figure 5, Figure 6, Figure 7).
      Figure thumbnail gr3
      Figure 3Comparison of hip–knee–ankle (HKA) angle difference. Conv, conventional technique; Nav, navigation; PSI, patient-specific instrumentation. Values represent the mean ± standard deviation.
      Figure thumbnail gr4
      Figure 4Comparison of posterior tibial slope (PTS) difference. Conv, conventional technique; Nav, navigation; PSI, patient-specific instrumentation. Values represent the mean ± standard deviation.
      Figure thumbnail gr5
      Figure 5The visual analog scale (VAS) score at each follow up time point. Conv, conventional technique; Nav, navigation; PSI, patient-specific instrumentation. Values represent the mean ± standard deviation.
      Figure thumbnail gr6
      Figure 6The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at each follow up time point. Conv, conventional technique; Nav, navigation; PSI, patient-specific instrumentation. Values represent the mean ± standard deviation.
      Figure thumbnail gr7
      Figure 7The Lysholm score at each follow up time point. Conv, conventional technique; Nav, navigation; PSI, patient-specific instrumentation. Values represent the mean ± standard deviation.
      The intraclass correlation coefficient (ICC) between two observers regarding the preoperative HKA axis and PTS were 0.97 (95% confidence interval (CI): 0.91–0.99) and 0.93 (95% CI: 0.84–0.97), respectively. The ICC regarding the postoperative HKA axis and PTS were 0.98 (95% CI: 0.97–1) and 0.89 (95% CI: 0.81–0.95), respectively. The inter-rater reliability was high.

      3.3 Complications

      The percentage of patients who reported one or more complications related to surgery was similar in the three groups: 10.0% in the conventional group, 10.5% in the navigation group and 7.9% in the PSI group (Table 4). There was no statistically significant difference among all the groups (P = 0.594). Superficial wound infection and concomitant cartilage lesion were the most common complications.
      Table 4Surgery-related complications.
      ComplicationsGroup 1Group 2Group 3P
      No. of patients403838
      No. of patients with at least 1 event (%)4 (10)4 (10.5)3 (7.9)0.594
      No. of complications (event rate)5 (0.13)6 (0.16)4 (0.11)0.416
      Early superficial surgical wound infection201
      Deep infection040
      Lateral hinge fracture after surgery111
      Concomitant cartilage lesion212
      Group 1, conventional high tibial osteotomy (HTO); Group 2, navigation; Group 3, patient-specific instrumentation (PSI).

      4. Discussion

      The principal findings of this study were that no single planning method showed superiority in correction precision and clinical outcomes at 2 years postoperatively. There was no correlation of primary and secondary outcomes with respect to Kellgren–Lawrence grades or other patient demographic factors (age, sex, and body mass index) in our study. The study hypothesis was not confirmed.
      In this study, we utilized HKA difference and PTS change as objective postoperative precision evaluation methods. HKA difference and PTS change seemed to be the most reliable criteria for assessing planning methods’ achievement of targets [
      • Han S.B.
      • Kim H.J.
      • Lee D.H.
      Effect of computer navigation on accuracy and reliability of limb alignment correction following open-wedge high tibial osteotomy: A meta-analysis.
      ,
      • Reising K.
      • Strohm P.C.
      • Hauschild O.
      • Schmal H.
      • Khattab M.
      • Südkamp N.P.
      • et al.
      Computer-assisted navigation for the intraoperative assessment of lower limb alignment in high tibial osteotomy can avoid outliers compared with the conventional technique.
      ]. Tardy et al. [
      • Tardy N.
      • Steltzlen C.
      • Bouguennec N.
      • Cartier J.-L.
      • Mertl P.
      • Batailler C.
      • et al.
      Is patient-specific instrumentation more precise than conventional techniques and navigation in achieving planned correction in high tibial osteotomy?.
      ] compared the precision of conventional techniques, navigation, and PSI. They found that none of the three methods showed superiority. This may be because all their procedures were performed by experienced surgeons with full mastery of their techniques and the multicenter design entailed variable management. In the present study, we found that HKA difference and PTS change of the PSI group was smaller than the conventional group or the navigation group. The finding was consistent with previous reports noting that PSI technology used for OW-HTO allows accurate achievement of the desired correction [
      • Fucentese S.F.
      • Meier P.
      • Jud L.
      • Köchli G.-L.
      • Aichmair A.
      • Vlachopoulos L.
      • et al.
      Accuracy of 3D-planned patient specific instrumentation in high tibial open wedge valgisation osteotomy.
      ,
      • Schenk P.
      • Vlachopoulos L.
      • Hingsammer A.
      • Fucentese S.F.
      • Fürnstahl P.
      Is the contralateral tibia a reliable template for reconstruction: A three-dimensional anatomy cadaveric study.
      ,
      • Victor J.
      • Premanathan A.
      Virtual 3D planning and patient specific surgical guides for osteotomies around the knee: A feasibility and proof-of-concept study.
      ,
      • Chaouche S.
      • Jacquet C.
      • Fabre-Aubrespy M.
      • Sharma A.
      • Argenson J.-N.
      • Parratte S.
      • et al.
      Patient-specific cutting guides for open-wedge high tibial osteotomy: safety and accuracy analysis of a hundred patients continuous cohort.
      ].
      The differences were within 1° or 2° only. They were imperceptible or unimportant to these patients. Therefore, the differences might only be statistically but not clinically significant.
      Looking at clinical outcomes as the secondary outcomes measure, we noted that mean scores improved initially in the three groups. This result was consistent and parallel with other published studies demonstrating that functional scores improved after HTO [
      • Saragaglia D.
      • Blaysat M.
      • Inman D.
      • Mercier N.
      Outcome of opening wedge high tibial osteotomy augmented with a Biosorb® wedge and fixed with a plate and screws in 124 patients with a mean of ten years follow-up.
      ,
      • Schröter S.
      • Ihle C.
      • Elson D.W.
      • Döbele S.
      • Stöckle U.
      • Ateschrang A.
      Surgical accuracy in high tibial osteotomy: coronal equivalence of computer navigation and gap measurement [published correction appears in Knee Surg Sports Traumatol Arthrosc. 2016 Nov;24(11):3418].
      ,
      • Han S.-B.
      • Lee J.-H.
      • Kim S.-G.
      • Cui C.-G.
      • Suh D.-W.
      • Lee S.-Y.
      • et al.
      Patient-reported outcomes correlate with functional scores after opening-wedge high tibial osteotomy: A clinical study.
      ]. However, all groups showed a small decline in mean clinical scores at the final 24-month follow up. The final score was still far better than the baseline clinical scores. This result could partly be due to the limitations of HTO in maintaining precision, which could result in a decrease in correction accuracy and clinical outcomes at 24 months [
      • Yang J.-S.
      • Chen C.-F.
      • Luo C.-A.
      • Chang M.-C.
      • Lee O.K.
      • Huang Y.e.
      • et al.
      Clinical experience using a 3D-printed patient-specific instrument for medial opening wedge high tibial osteotomy.
      ]. We also noted PSI achieved better clinical outcomes than other groups. And the mean difference of Lysholm and WOMAC scores were higher than minimal clinically important difference (the minimal clinically important difference of Lysholm and WOMAC scores were 8.9 and 11.5 points [
      • Harris J.D.
      • Brand J.C.
      • Cote M.P.
      • Faucett S.C.
      • Dhawan A.
      Research pearls: The significance of statistics and perils of pooling. Part 1: Clinical versus statistical significance.
      ]) of each score in the first postoperative year. In fact, a recent study examining the clinical outcomes of PSI by the the Knee Injury and Osteoarthritis Outcome Score (KOOS) and UCLA activity scale also found that PSI allows better clinical outcomes with early return to work and sport. Additionally, the mean gap was at its highest at 12 months but narrowed at 24 months in the present study. These results showed that the PSI group had better clinical outcomes than the other two groups in the first postoperative year. However, it failed to achieve minimal clinically important difference and significant clinical benefit after 24 months.
      Several studies reported that the rate of surgery-related complication following OW-HTO ranged from 1.9% to 55% [
      • Seo S.S.
      • Kim O.G.
      • Seo J.H.
      • Kim D.H.
      • Kim Y.G.
      • Lee I.S.
      Complications and short-term outcomes of medial opening wedge high tibial osteotomy using a locking plate for medial osteoarthritis of the knee.
      ]. In the present study, the incidence of complications in the navigation group (16%) was higher than the PSI group (11%) or conventional group (13%), but there were no statistically significant differences among them. Han et al. [
      • Han S.B.
      • In Y.
      • Oh K.J.
      • Song K.Y.
      • Yun S.T.
      • Jang K.M.
      Complications associated with medial opening-wedge high tibial osteotomy using a locking plate: A multicenter study.
      ] reported a 29.7% complication rate after OW-HTO using locking plates. The most reported surgery-related complication was stable lateral hinge fracture. The incidence of lateral hinge fractures in our study was lower and there were no specific complications occurring in each group.
      This study has several limitations. First, the follow up period was medium. To our knowledge, this is the first prospective, randomized study comparing clinical and radiologic outcomes among conventional technique, navigation and PSI. Second, the numbers per group were small, however, they were larger than in most other studies of HTO. Third, the correction precision evaluation in the present study was based on 2D analysis, not 3D analysis. Finally, there are several other factors affecting accuracy of correction in HTO, such as lateral hinge fracture, varus laxity and tibiofemoral subluxation, which should be further analyzed in the future.

      5. Conclusion

      In the present study, none of the three methods showed superiority in objective correction precision and clinical outcomes at 2 years.

      Funding

      This work was supported by Clinical Application-oriented Medical Innovation Foundation (Grant No 2021-NCRC-CXJJ-PY-09) from National Clinical Research Center for Orthopedics, Sports Medicine & Rehabilitation and Jiangsu China-Israel Industrial Technical Research Institute Foundation, and Jiangsu Province Science and Technology Innovation Support Plan Project (grant number 320000220950183112124).

      Author contributions

      J.J.G.: conception and design, data acquisition, interpretation of data, manuscript draft. X.Z. and Y.Q.: conception and design. X.Z.: ethical approval. A.L.: idea, conception and design, assisting in surgery, statistics, interpretation of data, help in drafting the manuscript. P.X.: intellectual input for surgery, interpretation of data. All authors: revision of the manuscript, final approval of the version to be published.

      Declaration of Competing Interest

      The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

      Appendix A. Supplementary material

      The following are the Supplementary material to this article:

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