Radiologic simulation of leg length change after double level osteotomy in preoperative surgical planning.

BACKGROUND: To evaluate the expected postoperative total leg length change using preoperative radiographs during surgical planning of four different methods of double level osteotomy (DLO). METHODS: This study included 34 patients (44 knees) who underwent DLO for varus knee osteoarthritis. Surgical planning was performed so that the postoperative weight bearing line ratio was 62.5%. In DLO, lateral closed or medial open wedge distal femoral osteotomy (LCWDFO, MOWDFO) was performed so that the postoperative mechanical lateral distal femoral angle was 85°, and residual deformity was corrected with medial open or lateral closed wedge high tibial osteotomy (MOWHTO, LCWHTO). Pre- and surgical planning X-rays in the one-leg standing position were compared to assess the change in leg length, and the factors affecting it, in the various surgical groups. The proportion of cases in which Δ total leg length was greater than 6 mm (symptomatic change) was investigated. RESULTS: The mean postoperative total leg length increased significantly with LCWDFO + MOWHTO, MOWDFO + MOWHTO, and MOWDFO + LCWHTO, while it decreased with LCWDFO + LCWHTO. The proportion of cases with a postoperative total leg length change > 6 mm was 72.7%, 2.3%, 100%, and 6.8% in LCWDFO + MOWHTO, LCWDFO + LCWHTO, MOWDFO + MOWHTO, and MOWDFO + LCWHTO, respectively. In addition, the preoperative hip-knee-ankle angle correlated negatively with the postoperative total leg length change in LCWDFO + MOWHTO, MOWDFO + MOWHTO, and MOWDFO + LCWHTO, but not in LCWDFO + LCWHTO. CONCLUSIONS: MOWDFO + MOWHTO had the largest postoperative leg length change and MOWDFO + LCWHTO had the smallest. Symptomatic leg length change (> 6 mm) should be considered in MOWDFO + MOWHTO and LCWDFO + MOWHTO.

Cartilage Degeneration of the Lateral Compartment of the Knee at Second-Look Arthroscopy Is Associated With Deterioration of 10-Year Clinical Outcomes After Opening-Wedge High Tibial Osteotomy.

PURPOSE: To identify the arthroscopic findings associated with deterioration of 10-year clinical outcomes after opening-wedge high tibial osteotomy (OWHTO) in patients with knee osteoarthritis. METHODS: A total of 114 consecutive knees of 91 patients with knee osteoarthritis who underwent OWHTO between 2007 and 2011 were retrospectively reviewed. Of these patients, those who underwent second-look arthroscopy and were followed up for a minimum of 10 years were enrolled. The Knee Society Score (KSS) and hip-knee-ankle angle were assessed. Cartilage status was graded at the time of osteotomy (first look) and plate removal (second look) according to the International Cartilage Repair Society (ICRS) grading system. The KSS knee subscale score and function subscale score were assessed separately, and on the basis of the changes in each of these scores from 1 to 10 years postoperatively and the minimal clinically important difference (MCID), the patients were divided into 2 groups: deteriorated (deterioration of score ≥ MCID) and non-deteriorated (deterioration of score < MCID). RESULTS: Sixty-nine knees were included in this study. The mean knee score improved continuously from 48.7 ± 11.3 preoperatively to 86.8 ± 10.3 at 1 year (P < .001), 87.5 ± 9.9 at 5 years (P < .001), and 86.5 ± 10.5 at 10 years (P < .001) postoperatively. The mean function score also improved continuously from 62.5 ± 12.1 preoperatively to 90.7 ± 12.9 at 1 year (P < .001), 91.6 ± 12.1 at 5 years (P < .001), and 88.5 ± 13.1 at 10 years (P < .001) postoperatively. Three knees underwent conversion to total knee arthroplasty within 10 years postoperatively. The deteriorated KSS group showed significantly progressed ICRS grades in the lateral compartment compared with the non-deteriorated KSS group. The ICRS grade in the lateral compartment at second-look arthroscopy was identified as the only significant factor associated with both knee score deterioration (odds ratio, 4.89; P = .03) and function score deterioration (odds ratio, 3.91; P = .03) on multivariable logistic regression analysis. CONCLUSIONS: The presence of cartilage degeneration of the lateral compartment of the knee at second-look arthroscopy is associated with deterioration of long-term clinical outcomes after OWHTO. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Bevacizumab suppressed degenerative changes in articular cartilage explants from patients with osteoarthritis of the knee.

BACKGROUND: This study was designed to test the hypothesis that blockade of vascular endothelial growth factor (VEGF) suppresses degenerative changes in articular cartilage from patients with osteoarthritis (OA). METHODS: Articular cartilage from eight OA patients was subjected to explant culture for 2 days in the presence or absence of 10 ng/ml recombinant interleukin (IL)-1ß. The blocking effect of VEGF was examined by the addition of 10 or 100 ng/ml of bevacizumab. The culture media were harvested, and markers for cartilage degradation were measured by sandwich enzyme-linked immunoassay. Total RNA was isolated from cartilage tissues, and gene expressions associated with the anabolic response were examined by the quantitative real-time polymerase chain reaction. RESULTS: Bevacizumab significantly reduced concentrations of matrix metalloproteinase (MMP)-2, MMP-3, and cartilage oligomeric matrix protein in the culture media with and without IL-1ß. Significant suppressive effects of bevacizumab on MMP-9 and MMP-13 were shown only in the presence of IL-1ß. Gene expression of Col2a1 was significantly increased by the addition of bevacizumab in the absence of IL-1ß. CONCLUSION: Bevacizumab inhibits catabolic reactions and stimulates anabolic function in articular cartilage derived from OA patients directly, suggesting a protective effect on articular cartilage from OA progression.

Potential anatomic risk factors resulting oversized postoperative medial proximal tibial angle after double level osteotomy.

BACKGROUND: Double level osteotomy (DLO) has been introduced to prevent increased postoperative joint line obliquity. However, although DLO is planned, knees with postoperative medial proximal tibial angle (MPTA) > 95° in preoperative surgical planning are present. This retrospective study aimed to evaluate risk factors for an MPTA > 95° in preoperative surgical planning for DLO in patients with varus knee osteoarthritis (OA). METHODS: A total of 168 knees that underwent osteotomies around the knee for varus knee OA were enrolled. The hip-knee-ankle angle (HKA), weight-bearing line (WBL) ratio, mechanical lateral distal femoral angle (mLDFA), joint line convergence angle (JLCA) and mechanical medial proximal tibial angle (mMPTA) were measured on preoperative radiographs. The postoperative WBL ratio was planned to be 62.5%. When the postoperative mMPTA was more than 95° in isolated high tibial osteotomy (HTO), (DLO) was planned so that the postoperative mLDFA was 85°, and residual deformity was corrected by HTO. Knees with postoperative mMPTA ≤ 95° and > 95° were classified into the correctable group and uncorrectable group, respectively. RESULTS: DLO was required in 101 knees (60.1%). Among them, 41 knees (40.6%) were classified into the uncorrectable group. Binomial logistic regression analysis showed that preoperative JLCA and mMPTA were independent predictors in the uncorrectable group. CONCLUSIONS: Even with DLO, postoperative mMPTA was more than 95° in approximately 40% of cases. Preoperative increased JLCA and decreased mMPTA were risk factors for a postoperative mMPTA of > 95° after DLO.

Patient-specific instrumentation for total knee arthroplasty improves reproducibility in the planned rotational positioning of the tibial component.

BACKGROUND: The purpose of this study was to evaluate the reproducibility of planned component positioning including tibial rotational alignment in patient-specific instrumentation (PSI) for total knee arthroplasty (TKA). METHODS: A total of 100 knees of 100 patients underwent TKA using PSI (n = 50) or the conventional method (n = 50). Full-length anteroposterior radiographs of the lower limb were taken in the standing position, and the coronal alignments of the femoral and tibial components were measured. Computed tomography (CT) images of the lower limb were obtained preoperatively and postoperatively, and the rotational alignments of the femoral and tibial components were measured. The difference from the preoperative planning in tibial rotational alignment was measured using three-dimensionally merged pre- and postoperative images. The mean values and rates of outliers in each measurement were compared between the PSI group and the conventional group. RESULTS: There were no significant differences in coronal alignment of the femoral and tibial components and rotational alignment of the femoral component between the two groups. With respect to rotational alignment of the tibial component from the preoperatively planned reference axis, the PSI group showed a lower rate of outliers (internal rotation > 10°) than the conventional group (p < 0.05). CONCLUSIONS: This study demonstrated that the difference from the preoperative planning in tibial rotational positioning was accurately evaluated using novel three-dimensional measurement method, and PSI could reduce outliers in rotational alignment of the tibial component (internal rotation > 10°). PSI is a useful technique for improving the reproducibility of the planned tibial rotational positioning in TKA.

Minimum 5-Year Outcomes of Osteochondral Autograft Transplantation with a Concomitant High Tibial Osteotomy for Spontaneous Osteonecrosis of the Knee with a Large Lesion.

OBJECTIVE: The purpose of this study was to evaluate the mid-term clinical outcomes of osteochondral autograft transplantation (OAT) with concomitant high tibial osteotomy (HTO) in spontaneous osteonecrosis of the knee (SONK) with a large lesion. DESIGN: A total of 48 knees of 48 consecutive patients with SONK (lesion size ≥4 cm2, no age criteria) who underwent opening wedge HTO and concomitant OAT were retrospectively investigated, and those who were followed up postoperatively for at least 5 years were included in this case series study. Clinical outcomes were evaluated using knee and function scores of Knee Society Score, radiographic outcomes were evaluated using the anatomical femorotibial angle (FTA), and these outcomes were compared between patients aged ≥70 years and <70 years. RESULTS: Of the 48 cases, a total of 43 cases were available for review at a minimum of 5 years, and 5 cases were excluded from the analysis. Overall, the mean knee score improved from preoperative 48.8 ± 13.3 to postoperative 87.9 ± 8.6 at 1 year (P < 0.05) and 85.0 ± 10.4 at final follow-up (P < 0.05 vs. preop., N.S. vs. 1 year). The mean function score also improved from preoperative 60.1 ± 10.9 to postoperative 87.3 ± 12.2 at 1 year (P < 0.05) and 84.2 ± 12.4 at final follow-up (P < 0.05 vs. preop., N.S. vs. 1 year). The mean standing FTA was corrected significantly from 181.1° ± 2.7° preoperatively to 169.7° ± 2.4° at 1 year (P < 0.05) and 169.4° ± 3.1° at final follow-up (P < 0.05 vs. preop., N.S. vs. 1 year). There were no significant differences in clinical and radiographic outcomes between patients aged ≥70 years and <70 years. There were 4 cases of lateral hinge fracture around the osteotomy site and 1 case of delayed union. None of the patients underwent revision surgery during the follow-up period (survival rate of 100%). CONCLUSIONS: Mid-term clinical outcomes of patients with SONK who underwent HTO and OAT with a relatively large lesion were good.

Biological Effects of High Tibial Osteotomy on Spontaneous Osteonecrosis of the Knee.

OBJECTIVE: The purpose of this study was to evaluate the postoperative status of spontaneous osteonecrosis of the knee (SONK) after high tibial osteotomy (HTO) with concomitant bone marrow stimulation (BMS) using synovial fluid (SF) biomarkers. DESIGN: Twenty patients with SONK who underwent opening wedge HTO were enrolled. Paired SF samples from the affected knee were collected at the time of HTO surgery and at the time of plate removal. SF concentrations of interleukin (IL)-6, IL-8, and matrix metalloproteinase (MMP)-13 were measured by enzyme-linked immunosorbent assays. The Knee Society Score (KSS) and hip-knee-ankle (HKA) angle were assessed before and 2 years after HTO. RESULTS: The KSS knee and function scores were significantly improved after HTO (mean changes of 33.8 and 29.4, respectively). The mean HKA angle was changed from mechanical varus (-8.6°) to valgus (5.2°). Concentrations of IL-6, IL-8, and MMP-13 were significantly decreased after HTO (mean changes of -73.7%, -32.4%, and -47.9% from preoperative baseline, respectively). Significant correlations were found between lesion size and concentrations of biomarkers, except for preoperative MMP-13. CONCLUSIONS: SF levels of biomarkers of inflammation and cartilage degradation were reduced after HTO with a concomitant BMS procedure, suggesting a biological improvement in SONK.

Surgical planning of osteotomies around the knee differs between preoperative standing and supine radiographs in nearly half of cases.

BACKGROUND: To evaluate the difference in surgical planning of osteotomies around the knee between preoperative standing and supine radiographs and to identify risk factors for discrepancies in surgical planning. METHODS: This study included 117 knees of 100 patients who underwent osteotomies around the knee for knee osteoarthritis with genu varum. Surgical planning was performed so that the target point of the postoperative weight-bearing line (WBL) ratio was 62.5% in preoperative standing and supine radiographs. If the opening gap would be > 13 mm in open-wedge high tibial osteotomy (OWHTO), closed-wedge HTO (CWHTO) was planned. If the postoperative mMPTA would be > 95° in isolated HTO, double-level osteotomy (DLO) was planned. In DLO, lateral closed-wedge distal femoral osteotomy was performed so that the postoperative mechanical lateral distal femoral angle (mLDFA) was 85°, and any residual varus deformity was corrected with HTO. RESULTS: Surgical planning differed between standing and supine radiographs in 43.6% of cases. In all knees for which surgical planning differed between standing and supine radiographs, a more invasive type of osteotomy was suggested by standing radiographs than by supine radiographs. The risk factors for discrepancies in surgical planning were a lower WBL ratio in standing radiographs and a lower joint line convergence angle in supine radiographs. CONCLUSIONS: Surgical planning of DLO, CWHTO and OWHTO, in standing radiographs differed from that in supine radiographs in nearly half of the cases. Surgical planning based on standing radiographs leads to more invasive surgical procedures compared to supine radiographs.

The range of the required anterolateral cortex osteotomy distance varied widely in biplanar open wedge high tibial osteotomy.

BACKGROUND: To evaluate the anterolateral cortex distance between the lateral edge of the flange and hinge point in surgical simulations of biplanar open wedge high tibial osteotomy (OWHTO) using computed tomography (CT) images. METHODS: A total of 110 knees treated with OWHTO for medial knee osteoarthritis with varus malalignment were enrolled. Surgical simulations of biplanar OWHTO, including the transverse and ascending cuts, were performed in the standard manner using preoperative CT images. The distance between the lateral edge of the flange and the hinge point was measured. In addition, another plane of the ascending cut was defined through the hinge point. The angle between these two planes of the ascending cut was measured in the axial plane. RESULTS: The mean anterolateral cortex distance was 9.4 ± 4.6 mm (range, - 1.5 mm - 20.3 mm). In 3 knees, osteotomy of the anterolateral cortex was not needed. The mean value of the angle between the two ascending cut planes was 8.4 ± 3.6° (range, - 2.1° - 14.8°), which meant that osteotomy of anterolateral cortex was not needed when the ascending cut was performed at this angle. Moreover, these two values increased when the flange thickness was changed from one-third to one-fourth of the anteroposterior tibial diameter or the angle between the transverse and ascending cuts was changed from 110° to 120°. CONCLUSIONS: In biplanar OWHTO, anterolateral cortex osteotomy would be required. However, the range of the required anterolateral cortex osteotomy distance varied widely and the required anterolateral cortex osteotomy distance depended on the flange thickness and the angle between the transverse and ascending cuts. In addition, change of the ascending cut plane can change the necessity of anterolateral cortex osteotomy.

Risk of interference between the tibial tunnel and locking screws in medial meniscus posterior root repair and open wedge high tibial osteotomy.

PURPOSE: To evaluate whether the frequency of interference between locking screws for the plate fixation and tibial tunnels differs depending on the tibial tunnel positions in a surgical simulation of the transtibial pull-out repair of medial meniscus posterior root tears (MMPRTs) in patients undergoing biplanar open wedge high tibial osteotomy (OWHTO). METHODS: Sixty-five patients (75 knees) who underwent OWHTO with TomoFix small plate (Depuy Synthes, PA, USA) for medial knee osteoarthritis with varus malalignment were enrolled in this study. Surgical simulation of transtibial pull-out repair of MMPRTs was performed using postoperative computed tomography images. The tibial tunnel was created in the anatomical attachment area of the medial meniscus posterior root. Another aperture of the tibial tunnel was created on the anteromedial (AM) tibial cortex, the posteromedial (PM) tibial cortex, and the anterolateral (AL) tibial cortex in the proximal tibial fragment. The frequency of interference between the tibial tunnel and A-D locking screws was compared in the 3 tibial tunnel positions. In each tibial tunnel position, the locking plate position with and without interference between the tibial tunnel and at least one locking screw was compared. RESULTS: For screw A, the frequency of interference with the tibial tunnel in the AL position was higher than that in the AM (P = 0.048) and PM positions (P <  0.001). For screws B and C, the frequency of interference with the tibial tunnel in the AM position was higher than that in the PM (P <  0.001, P = 0.007) and AL positions (P <  0.001, P = 0.001), respectively. For screw D, there was no difference in the frequency of interference with the tibial tunnel among the three positions. The frequency of interference between the tibial tunnel and at least one screw in the AM position was 100%, which was higher than that in the PM (P <  0.001) and AL positions (P <  0.001). In the PM position, the locking plate was placed more posteriorly in the group where the locking screw interfered with the tibial tunnel. In the AL position, the locking plate was placed more parallel to the medial/lateral axis of the tibial plateau in the interference group. CONCLUSION: Making the tibial tunnel in the AM position should be avoided because interference with locking screws was inevitable. When the tibial tunnel is created in the PM position, interference between the tibial tunnel and screw C should be paid attention. Anterior placement of the locking plate could be useful to prevent interference between locking screws and the tibial tunnel in the PM position. In addition, when the tibial tunnel is created in the AL position, interference between the tibial tunnel and especially screw A among screws A-C should be paid attention. Placing the locking plate in an anteromedial direction could be useful to prevent interference between locking screws and the tibial tunnel in the AL position. LEVEL OF EVIDENCE: IV.

No differences in clinical outcomes and cartilage repair between opening wedge and closed wedge high tibial osteotomies at short-term follow-up: A retrospective case series analysis.

PURPOSE: The aim of this study was to assess differences in clinical outcomes and postoperative cartilage repair between opening wedge high tibial osteotomy (OWHTO) and closed wedge HTO (CWHTO) for medial osteoarthritis (OA) of the knee. METHODS: A total of 90 knees of 76 patients who underwent OWHTO (45 knees of 40 patients) and CWHTO (45 knees of 36 patients) was followed-up for 2 years. Cartilage repair at the medial compartment was arthroscopically classified into the following stages: Stage 1 (no reparative change); Stage 2 (partial coverage with white cartilaginous tissue); and Stage 3 (full coverage with white cartilaginous tissue). Clinical outcomes were assessed using Knee Society scores, and radiographic assessment was carried out by anatomical femorotibial angle (aFTA). RESULTS: Regarding preoperative OA grade, varus alignment, and function score, CWHTO patients showed more advanced OA status than OWHTO patients. Knee scores and function scores were significantly improved after surgery with both HTO procedures (P < 0.05), with no significant difference between the two procedures. Cartilage repair of stage 2 or 3 was found in more than 80% of the subjects in the medial femoral condyle and more than 60% in the medial tibial condyle. However, there were no significant differences between the two HTO procedures. Multivariate logistic regression analysis showed that preoperative International Cartilage Repair Society (ICRS) grade was the only factor affecting cartilage repair. CONCLUSIONS: CWHTO improved clinical outcomes and cartilage status as much as OWHTO. Although the effects of cartilage repair on clinical outcomes are unknown, HTO is an effective treatment option even for severe medial OA of the knee.

Medialization of the mechanical axis of the tibia is related to lateralization of the tibial tuberosity in knee osteoarthritis.

PURPOSE: To determine whether medialization of the proximal tibia due to a varus deformity is related to lateralization of the tibial tuberosity in varus knee osteoarthritis (OA). METHODS: A total of 120 knees that underwent osteotomies around the knee for varus knee OA were enrolled. Mechanical medial proximal tibial angle (mMPTA) was measured on radiographs. The angle between the mechanical and anatomical axes of the tibia (angle MA) and the distance between the centre of the tibial plateau and the anatomical axis (distance MA) were measured in the coronal plane on computed tomography images. The tibial tuberosity-posterior cruciate ligament (TT-PCL) distance, the distance between the midpoint of the tibial tuberosity and the centre of the tibial plateau (TT-centre distance), and the angle between the line through the midpoint of the tibial tuberosity and the centre of the tibial plateau and the anteroposterior axis (TT-centre angle) were measured in the axial plane. The correlations of these parameters were evaluated. RESULTS: mMPTA correlated negatively with angle MA (r = -0.37, P < 0.01) and distance MA (r = -0.55, P < 0.01). Angle MA and distance MA correlated with TT-PCL distance (r = 0.39, P < 0.01, r = 0.42, P < 0.01), TT-centre distance (r = 0.35, P < 0.01, r = 0.38, P < 0.01) and TT-centre angle (r = 0.36, P < 0.01, r = 0.36, P < 0.01). CONCLUSIONS: Medialization of the proximal tibia due to a varus deformity may induce lateralization of the tibial tuberosity.

Increased contact area of flange and decreased wedge volume of osteotomy site by open wedge distal tibial tuberosity arc osteotomy compared to the conventional technique.

PURPOSE: The purpose of this study was to evaluate the area of the osteotomy surface, including the flange and wedge volume, in open wedge high tibial osteotomy (OWHTO), distal tibial tuberosity osteotomy (DTO), and distal tibial tuberosity arc osteotomy (DTAO) using tibial sawbones. It was hypothesized that the area of the osteotomy surface, including the flange, in DTAO was larger than that in OWHTO and DTO and that the wedge volume in DTAO was smaller than that in OWHTO and DTO. METHODS: Fifteen tibial sawbones were divided equally into three groups: OWHTO, DTO, and DTAO. The total area of the osteotomy surface in OWHTO, DTO, and DTAO was compared using image analysis software. The contact area of the flange and the wedge volume at wedge heights of 5, 10, and 15 mm were compared among osteotomy types. One-way repeated-measures analysis of variance was used to compare the total area of the osteotomy surface, the contact area of the flange, and the wedge volume at 5, 10, and 15 mm in OWHTO, DTO, and DTAO. RESULTS: The total area of the osteotomy surface in DTO and DTAO was significantly larger than that in OWHTO (P < 0.05). The contact area of the flange in DTAO was significantly larger than that in OWHTO at each wedge height (P < 0.05). In addition, the contact area of the flange in DTAO was significantly larger than that in DTO at wedge heights of 5 and 15 mm (P < 0.05). The wedge volume in DTAO was significantly smaller than that in DTO at each wedge height (P < 0.05). CONCLUSIONS: This study demonstrated that an increase in the flange contact area and a decrease in the wedge volume in the opening gap were found in DTAO compared to DTO. This would be an advantage for anteroposterior screw insertion from the flange to the distal tibial fragment and bone union at the osteotomy site.

Varus inclination of the tibia is related to patellofemoral osteoarthritis in Japanese female patients with moderate knee osteoarthritis.

PURPOSE: The aim of this study was to investigate whether the tibial tuberosity-trochlear groove (TT-TG) distance and lateral patellar tilt, which induce patellofemoral osteoarthritis (OA), are related to the coronal deformity of the lower limb in varus knee OA. It was hypothesized that varus inclination of the tibia was negatively correlated with the TT-TG distance and lateral patellar tilt in Japanese female patients with moderate knee OA. METHODS: A total of 104 female patients (139 knees) scheduled to undergo knee osteotomy for varus knee OA were enrolled. The coronal lower limb alignment was measured on anteroposterior whole-leg radiographs. The TT-TG distance, patellar tilt angle, and the patellofemoral joint space were measured both medially and laterally on computed tomography images. The correlations between coronal lower limb alignment and the TT-TG distance or patellar tilt angle, and the correlations between the TT-TG distance or patellar tilt angle and patellofemoral joint space were evaluated. RESULTS: The medial proximal tibial angle was negatively correlated with the TT-TG distance (r = - 0.383, P < 0.01) and patellar tilt angle (r = - 0.34, P < 0.01). Lateral patellofemoral joint space was negatively correlated with the TT-TG distance (r = - 0.256, P = 0.002) and patellar tilt angle (r = - 0.205, P = 0.016). CONCLUSIONS: Varus inclination of the proximal tibia may induce lateralization of the tibial tuberosity and lateral patellar tilt. The tibial tuberosity lateralization and lateral patellar tilt may induce lateral patellofemoral OA in patients with varus knee OA. LEVEL OF EVIDENCE: III.

Coronal shaft bowing of the femur affects varus inclination of the surgical transepicondylar axis in varus knee osteoarthritis.

PURPOSE: This study investigated the relationship between femoral shaft bowing and the orientation of the surgical transepicondylar axis (TEA) in the coronal plane in varus knee osteoarthritis (OA). METHODS: A total of 82 knees scheduled to undergo total knee arthroplasty (TKA) for the treatment of varus knee OA were enrolled. The hip-knee-ankle angle (HKA) was measured preoperatively on anteroposterior whole-leg standing radiographs. The lateral angle between the TEA and the mechanical axis of the femur (MA-TEA) was measured in the coronal plane from preoperative computed tomography (CT) images. Femoral shaft bowing was measured on CT images. Pearson's correlation coefficient was used to examine the correlation of the MA-TEA with the HKA and femoral shaft bowing. RESULTS: The MA-TEA correlated negatively with the HKA (r = - 0.321, P < 0.01) and positively with femoral shaft bowing (r = 0.415, P < 0.01). CONCLUSIONS: The TEA changed to varus as femoral shaft bowing increased in patients with varus knee OA. This suggests that the TEA is not always the centre of the rotational axis of the femur after TKA. In addition, the TEA may not be useful as a consistent parameter in the coronal plane in patients with increasing femoral shaft bowing. LEVEL OF EVIDENCE: III.

Intraoperatively accurate limb alignment after opening wedge high tibial osteotomy can be lost by large knee joint line convergence angle during surgery.

INTRODUCTION: The purpose of this study was to assess early postoperative loss of achieved correction and associated factors after opening wedge high tibial osteotomy (OWHTO). MATERIALS AND METHODS: OWHTO was performed in 121 patients with osteoarthritis of the knee (mean age 66 years, 154 knees). Anteroposterior radiographs of the knee and full-length leg, and varus and valgus stress radiographs of the knee were taken, and the femorotibial angle (FTA), joint line convergence angle (JLCA), and medial proximal tibial angle (MPTA) were measured. The changes in the FTA, JLCA, and MPTA were defined as ΔFTA, ΔJLCA, and ΔMPTA. RESULTS: The ΔFTA and ΔJLCA at postoperative 0-2 days were - 1.8 ± 1.2° and - 1.9 ± 1.4°, respectively. The ΔFTA, ΔJLCA and ΔMPTA at postoperative 1-12 months were 0.9 ± 1.3°, 0.2 ± 1.2° and - 0.8 ± 0.8°, respectively. A positive correlation was found between ΔFTA and ΔJLCA at postoperative 0-2 days (ρ = 0.642, P < 0.001) and at postoperative 1-12 months (ρ = 0.402, P < 0.001). A negative correlation was found between ΔFTA and ΔMPTA at postoperative 1-12 months (ρ = - 0.534, P < 0.001). A discrepancy in alignment represented by the FTA occurred in the supine radiographs between the day of surgery and postoperative 2 days. Multiple regression analysis suggested that postoperative JLCA on the day of surgery was the factor related to early postoperative change of the FTA. CONCLUSIONS: This study demonstrated the early loss of achieved correction after OWHTO due to change of the JLCA, even if the accurate alignment is obtained intraoperatively.

Relationship between the bony correction angle and mechanical axis change and their differences between closed and open wedge high tibial osteotomy.

BACKGROUND: The purpose of this study was to investigate the relationship between the bony correction angle and mechanical axis change and their differences between closed wedge high tibial osteotomy (CWHTO) and open wedge high tibial osteotomy (OWHTO). METHODS: A total of 100 knees of 89 patients who underwent OWHTO (50 knees) or CWHTO (50 knees) between 2011 and 2015 with a clinical follow-up for 1 year and a radiological follow-up for 1 month were investigated in a case control study. Anteroposterior radiographs of the knee and full-length leg were taken in the standing position using digital acquisition. The femorotibial angle (FTA), % mechanical axis deviation (MAD), % anatomical tibial axis deviation (ATAD), % mechanical tibial axis deviation (MTAD), mechanical medial proximal tibial angle (mMPTA), and joint line convergence angle (JLCA) were measured on preoperative and postoperative radiographs using a dedicated software. RESULTS: CWHTO resulted in a greater variation between the tibial anatomical and mechanical axes than OWHTO (P <  0.05), and a greater soft tissue correction than OWHTO (P <  0.05). However, no significant difference was found between CWHTO and OWHTO in the ratio of MAD change to the correction angle. When the osteotomy was planned with the same bony correction angle, %MAD passed more laterally in OWHTO than in CWHTO (P <  0.05). These results suggested a lesser valgus bony correction ratio due to greater medial shift of the tibial axis and greater valgus compensation of the soft tissue in CWHTO compared to OWHTO. CONCLUSIONS: The ratio of mechanical axis shift to the correction angle differed in preoperative planning, but postoperative alignment was comparable between opening wedge and closed wedge high tibial osteotomy.