Similar short-term KOOS between open-wedge high tibial osteotomy and total knee arthroplasty in patients over age 60: A propensity score-matched cohort study.

OBJECTIVES: The purpose of the present study was to evaluate improvement in the Knee Injury and Osteoarthritis Outcome Score (KOOS) after open-wedge high tibial osteotomy (HTO) in comparison with total knee arthroplasty (TKA) in cohorts over age 60 matched by pre-operative age, gender, body mass index (BMI), hip-knee-ankle angle (HKAA), KOOS sub-scores, and osteoarthritis (OA) grade. METHODS: Propensity score matching was performed between 162 HTO patients and 134 TKA patients. When calculating the propensity score by multivariate logistic regression analysis, the following pre-operative confounders were included: age, gender, BMI, HKAA, KOOS sub-scores, and OA grade. Consequently, a total of 55 patients were included in each group. The Student's t-test was used to analyse differences in the post-operative KOOS sub-scores between groups. RESULTS: After propensity score matching, all matched pre-operative valuables were identical, with no significant differences between the HTO and TKA groups. None of the post-operative KOOS sub-scores at 1 year after surgery showed a significant difference between the HTO and TKA groups. Both groups demonstrated significant and comparable post-operative improvement in every KOOS sub-score. CONCLUSIONS: In patients over age 60, there was no significant difference in short-term pain relief and improvements in activity and quality of life between HTO and TKA after propensity score matching including pre-operative age, KOOS sub-scores, and OA grade. HTO is a joint preservation procedure that is valid for knee OA even in individuals over age 60.

Feasibility and applicability of locomotive syndrome risk test in elderly patients who underwent total knee arthroplasty.

OBJECTIVES: The concept of locomotive syndrome (LS) and its evaluation method, the LS risk test, have been applied in an integrated manner to capture the decline in mobility resulting from musculoskeletal disorders. The purpose of this study was to evaluate the impact of total knee arthroplasty (TKA) in the elderly with knee osteoarthritis, a common disorder found in LS. METHODS: A total of 111 patients were registered prior to TKA and postoperatively followed up for 1 year. Three components of the LS risk test (the two-step test, stand-up test, and Geriatric Locomotive Function Scale-25) were assessed pre- and postoperatively. RESULTS: After surgery, all three components of the test showed significant improvements from the baseline. The ratio of Stage 3 LS patients (progressed stage of decrease in mobility) reduced from 82.3% to 33.9% postoperatively. There was no significant difference in the degree of change in the scores between the younger (60-74 years) and older (≥75 years) age groups. CONCLUSIONS: We found that TKA has a major impact in preventing the progression of LS in patients with knee osteoarthritis. The LS risk test is a feasible tool for the longitudinal evaluation of patients with musculoskeletal diseases of varying severity and with multiple symptoms.

Postoperative Valgus Laxity and Medial Pivot Kinematics Are Significantly Associated With Better Clinical Outcomes.

BACKGROUND: The relative impact of soft tissue balance and knee laxity on clinical outcomes after total knee arthroplasty (TKA) is not fully understood. We analyzed associations among knee laxity, kinematics, and patient-reported outcomes. METHODS: Knee Society Scores were recorded in 67 patients before and after primary TKA for osteoarthritis with varus deformity (N = 78). Varus and valgus laxity was measured in 78 knees using stress radiographs. Knee kinematics were measured fluoroscopically during stair ascent in 16 knees. RESULTS: On average, varus laxity decreased significantly, and valgus laxity increased significantly after TKA, although the net combined varus-valgus laxity did not change significantly. Postoperatively, the magnitude of valgus laxity correlated significantly with greater patient symptoms and satisfaction scores. Patients with medial pivot kinematics scored higher on patient satisfaction and standard activities. CONCLUSION: We found that postoperative valgus laxity and medial pivot kinematics were significantly associated with better clinical outcomes. These results emphasize the importance of careful preoperative planning and attention to intraoperative alignment and ligament balancing.

Evaluation of the balance function before and after total knee arthroplasty using Berg balance scale.

INTRODUCTION: The purpose of this study was to evaluate balance function before and after total knee arthroplasty (TKA) using Berg balance scale (BBS). The study also aimed to identify factors associated with balance impairment. MATERIALS AND METHODS: Ninety-three knees in 90 patients were prospectively evaluated using their BBS scores, passive knee extension/flexion angles, Visual analogue scale for pain scores, hip-knee-ankle angles, and knee extensor/flexor muscle strengths before and after TKA. A total BBS score of less than 45 indicates an enhanced risk of multiple falls. Multivariate logistic regression models were performed to elucidate factors associated with post-operative BBS score. RESULTS: A significant difference in mean pre- and post-operative BBS scores were noted (49.3 ± 6.4 vs. 52.2 ± 4.7) (p < 0.05). The percentage of pre- and post-operative BBS scores less than 45 were 20% and 10% (p < 0.05). Rheumatoid Arthritis (RA), lower pre-operative BBS score, and larger post-operative knee flexion contracture were significantly associated with lower post-operative BBS score (p < 0.01). The post-operative knee flexion contracture greater than 10° was significantly associated with substantially high odds of post-operative BBS scores less than 45 (Odds ratio 7.6; 95% confidential interval 1.69-34.17). CONCLUSIONS: While TKA significantly improved BBS scores, 10% of the patients remained at a risk for multiple falls. RA, lower pre-operative BBS score, and post-operative knee flexion contracture greater than 10° retained balance impairment even after TKA.

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 (ß coefficient = 0.78, P < .001), followed by opening wedge angle (ß coefficient = 0.36, P < .001) and gap ratio (ß 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.

Patient-specific prediction of joint line convergence angle after high tibial osteotomy using a whole-leg radiograph standing on lateral-wedge insole.

PURPOSE: To assess the usefulness of a whole-leg radiograph standing on lateral-wedge insole (LWI) for predicting the change in joint line convergence angle (JLCA) before vs. after high tibial osteotomy (HTO). METHODS: Forty knees with medial osteoarthritis underwent open-wedge HTO. Pre-operatively, all patients had whole-leg radiographs taken in three different conditions: supine, standing, and standing on LWI inclined at 20°. A standing whole-leg radiograph was also obtained post-operatively. Radiological measurements including JLCA and percentage of mechanical axis (%MA) were compared. Using pre-operative radiographs, correction angles were calculated with the target %MA at 62.5%. Correlations between the difference in calculated correction angle among the three pre-operative conditions and the change in JLCA before vs. after HTO were assessed. RESULTS: In the pre-operative standing conditions, the mean JLCA of 3.8° was significantly decreased to 3.2° using LWI, which did not differ from post-operative JLCA of 3.1°. Mean %MA significantly shifted laterally from 20.6 to 24.8% using LWI, and was strongly correlated with the change in JLCA (coefficient, 0.83). Calculated correction angles differed significantly among the three pre-operative conditions. The difference in calculated correction angle between standing with and without LWI was strongly correlated to the change in standing JLCA before vs. after HTO (coefficient, 0.73). CONCLUSION: Larger differences in calculated correction angles between pre-operative radiographs standing with and without LWI predicted larger changes in JLCA after HTO. Whole-leg radiograph standing on LWI is a promising modality for correct pre-operative planning considering patient-specific changes in JLCA before vs. after HTO. LEVEL OF EVIDENCE: IV.

Does Preparation of the Subtalar Joint for Primary Union Affect Clinical Outcome in Patients Undergoing Intramedullary Nail for Rheumatoid Arthritis of the Hindfoot and Ankle?

This study aimed to evaluate whether preparation of the subtalar joint affects the clinical outcomes after tibiotalocalcaneal arthrodesis using an intramedullary nail with fins for rheumatoid ankle/hindfoot deformity. Fifty-three joints in 51 patients who underwent tibiotalocalcaneal arthrodesis using an intramedullary nail with fins for rheumatoid arthritis at 2 institutions were included. Ten patients were male and 41 were female, with a mean age at surgery and follow-up period of 61.3 years and 71.6 months, respectively. Radiographic bone union was evaluated at the most recent visit. Univariate and multivariable analyses were performed to determine the risk factors associated with nonunion. The mean postoperative Japanese Society for Surgery of the Foot ankle/hindfoot scale was 65.3 (range, 5-84). The tibiotalar nonunion rate was 0%, whereas the subtalar nonunion rate was 43.3% (23 joints). Revision surgery was performed in 5, all of which were due to painful subtalar nonunion. Absence of subtalar curettage and earlier postoperative weightbearing were significantly associated with subtalar nonunion (p = .0451 and p = .0438, respectively). Subtalar nonunion after tibiotalocalcaneal arthrodesis for rheumatoid hindfoot is associated with higher revision rate. To decrease the risk of subtalar nonunion after tibiotalocalcaneal arthrodesis with an intramedullary nail in rheumatoid patients, curettage for the subtalar joint should be performed, and full weightbearing should be delayed until at least 26 days postoperatively.

Bony landmarks with tibial cutting surface are useful to avoid rotational mismatch in total knee arthroplasty.

PURPOSE: The purpose of this study was to define various anteroposterior axes of the tibial component as references and to evaluate their accuracy and variability using virtual surgery. It was hypothesized that (1) Akagi's Line could result in high accuracy and low variability in varus osteoarthritic knees; (2) anteroposterior axes defined by using the tibial bony cutting surface as a landmark might be good substitutes for Akagi's Line; and (3) extra-articular bony landmarks might influence the variability of the anteroposterior axis. METHODS: Three-dimensional bone models were reconstructed from the preoperative computed tomography data of 111 osteoarthritic knees with varus deformities. Seven different anteroposterior axes of the tibial component were defined: Akagi's Line, Axis MED, Axis 1/6MED, Axis 1/3MED, Axis of Oval Shape, Axis of Anterior Crest, and Axis Second Metatarsus. The rotational mismatch angle was measured between the tibial anteroposterior axis and the line perpendicular to the transepicondylar axis projected on the cutting surface (positive value: external rotation of the tibial anteroposterior axis). RESULTS: The average rotational mismatch angles (referring to the projected anatomical/surgical epicondylar axes) were - 2.7° ± 5.8°/1.0° ± 6.0° (Akagi's Line), - 4.2° ± 7.7°/- 0.5° ± 7.8°, 2.9° ± 7.2°/6.6° ± 7.2°, 9.8° ± 7.0°/13.5° ± 6.8° (Axis MED, Axis 1/6MED, Axis 1/3MED), - 5.1° ± 7.9°/- 1.4° ± 7.8° (Axis of Oval Shape), and 19.3 ± 9.5°/23.0° ± 9.6°, - 2.0° ± 11.3°/1.7° ± 11.4° (Axis Anterior Crest, Axis Second Metatarsus), respectively. CONCLUSIONS: Akagi's Line provided the best accuracy and least variability in varus osteoarthritic knees. Axis 1/6MED and Axis MED are good substitutes for Akagi's Line due to the difficulty of identifying the attachment site of the posterior cruciate ligament after the proximal tibia has been cut. Extra-articular bony landmarks should not be used for alignment due to their high variability. This study will aid surgeons in choosing the proper anteroposterior axis of the tibial component to reduce rotational mismatch and thus achieve good clinical knee outcomes. LEVELS OF EVIDENCE: III.

Medial soft tissue contracture does not always exist in varus osteoarthritis knees in total knee arthroplasty.

PURPOSE: To evaluate preoperative soft tissue balance for total knee arthroplasty (TKA), varus/valgus stress radiographs has been used in previous studies. While the joint line of femur and tibia is almost parallel in healthy and postoperative knees, osteoarthritis (OA) knees exhibit articular cartilage wear that causes the joint line tilting even in a non-stress condition. Therefore, the exact angle of the joint line might mislead to understand the joint laxity in OA knees. The purpose of this study was to evaluate soft tissue balance in varus OA knees using preoperative stress radiographs under three different constant loads, taking the articular cartilage wear into consideration. METHODS: One hundred and eighteen varus-deformed OA knees in 102 patients were investigated before primary TKA. Preoperative knee radiographs were obtained in the anteroposterior view with no stress (defined as the neutral condition) and with varus and valgus stresses (5, 10, and 15 kg) in extension. Two different types of joint line angle (JLA), the absolute JLA (an exact angle of joint line) and the relative JLA (the absolute JLA minus the JLA in the neutral condition), were compared for the same load with the paired t test. RESULTS: The absolute JLA was 7.9 ± 1.2°/- 1.5 ± 2.2° under varus/valgus 15 kg stress, 6.7 ± 2.4°/- 0.3 ± 2.1° under varus/valgus 10 kg stress, and 4.7 ± 2.4°/1.1 ± 2.2° under varus/valgus 5 kg stress. Significant differences in the numerical values of the absolute JLA were observed between varus and valgus stresses for each load. The neutral JLA was 3.2 ± 2.0°. The relative JLA was 4.8 ± 2.1°/- 4.7 ± 1.8° under varus/valgus 15 kg stress, 3.5 ± 2.0°/- 3.5 ± 1.8° under varus/valgus 10 kg stress, and 1.5 ± 1.9°/- 2.1 ± 1.8° under varus/valgus 5 kg stress. No significant differences in the numerical values of the relative JLA were observed between varus and valgus stresses for each load. CONCLUSIONS: Consideration of cartilage wear allowed knee laxity to be evaluated more precisely in this study than in previous reports. It was shown that medial soft tissue contracture did not always exist, even in varus OA knees. Regarding clinical relevance, surgeons should be aware that underestimating medial soft tissue laxity due to reliance on the absolute JLA might lead to excessive medial tissue release and result in postoperative instability and lower patient satisfaction. LEVEL OF EVIDENCE: IV.

Degenerative changes in cartilage likely occur in the medial compartment after anterior cruciate ligament reconstruction.

PURPOSE: Magnetic resonance imaging with T1ρ mapping is used to quantify the amount of glycosaminoglycan in articular cartilage, which reflects early degenerative changes. The purposes of this study were to evaluate early degenerative changes in knees after anterior cruciate ligament (ACL) reconstruction by comparing T1ρ values before and 2 years after surgery and investigate whether surgical factors and clinical outcomes are related to differences in T1ρ values. METHODS: Fifty patients who underwent unilateral primary ACL reconstruction were evaluated using T1ρ mapping before and 2 years after surgery. Three regions of interest (ROIs) were defined in the cartilage associated with the medial (M) and lateral (L) weight-bearing areas of the femoral condyle (FC) (anterior: MFC1 and LFC1, middle: MFC2 and LFC2, and posterior: MFC3 and LFC3). Two ROIs associated with the tibial plateau (T) were defined (anterior: MT1 and LT1, and posterior: MT2 and LT2). T1ρ values within the ROIs were measured before and 2 years after surgery and compared using the paired t test. Correlations between the difference in T1ρ values at these two time points and patient characteristics, presence of a cartilaginous lesion, graft type, and postoperative anteroposterior laxity were also evaluated using Pearson's and Spearman's correlation coefficients. RESULTS: There was a significant increase in T1ρ before versus 2 years after surgery in the MT1, MT2, LFC1, and LT1 areas, and a significant decrease in the LFC3 and LT2 areas. There was a significant correlation between postoperative anterior-posterior laxity and a postoperative increase in T1ρ values in the MFC3 (r = 0.37, P = 0.013) and MT2 (r = 0.35, P = 0.021) areas. Increases in T1ρ values in the MFC2 area were negatively correlated with KOOS symptoms (ρ = - 0.349, P = 0.027) and quality of life (ρ = - 0.374, P = 0.017) subscale scores. CONCLUSION: Early degenerative changes in medial articular cartilage were observed with T1ρ mapping at 2 years after ACL reconstruction. Postoperative anterior-posterior laxity is correlated with an increase in T1ρ values in the posteromedial femur and tibia. An increase in T1ρ values in the central medial femoral condyle was associated with knee symptoms. LEVEL OF EVIDENCE: III.

Alignment factors affecting the medial meniscus extrusion increases the risk of osteoarthritis development.

PURPOSE: Varus alignment is known as one of the major causes of medial compartment osteoarthritis (OA). Medial meniscus extrusion also plays a critical role in the in the development of OA. However, studies on the exact relationship between alignment parameters and medial meniscus extrusion are limited. Therefore, this study aimed to investigate this relationship in patients with knee OA. METHODS: Based on a retrospective analysis of the outpatient magnetic resonance imaging (MRI) database, 190 knees were identified to be examined using weight-bearing, whole-leg radiographs and MRIs within 3 months from the first consultation. Subsequently, various parameters of lower leg alignment were measured, which affected the knee varus in radiographs. Finally, a statistical analysis was performed to assess the relationships between the OA grade, distance of medial meniscus extrusion (MME), and alignment parameters; hip-knee-ankle angle (HKAA), percentage of mechanical axis (% MA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). The subjects were divided according to the presence or absence of MME (Group A: MME distance below 3 mm, Group B: MME distance 3 mm and above) to assess the differences in each alignment parameter correlated with MME distance between the groups. RESULTS: MME distance significantly increased with OA grade progression. HKAA, % MA, MPTA, and JLCA significantly correlated with medial meniscus extrusion distance (r = - 0.21, - 0.23, - 0.16, 0.3, respectively). Multiple regression analysis of each significant alignment combined with age, sex, and body mass index revealed that HKAA, % MA, MPTA, and JLCA were significant independent factors of MME distance (P = 0.008, 0.0026, 0.011, 0.0001, respectively). These significant findings were reinforced in group B. In contrast, the correlation between alignment parameters and medial meniscus extrusion distance was not significant in group A. CONCLUSION: Varus alignment factors are related to MME distance especially in extruded meniscus knees, as the OA grade progressed. Therefore, the coexistence of varus alignment and MME can be the risk factors for OA progression. As the low MPTA was an independent alignment factor for generating varus alignment, patients with osteoarthritis of the knee with both, low MPTA and MME could be the appropriate candidates for early intervention by high tibial osteotomy. LEVEL OF EVIDENCE: III.

Patient reported outcomes after high tibial osteotomy show comparable results at different ages in the mid-term to long-term follow-up.

BACKGROUND: Few studies have evaluated the impact of age on patient-reported outcomes in the long-term follow-up after high tibial valgus osteotomy (HTO). The purpose of this study is to assess the association between age at surgery and patient-reported clinical outcomes in the mid-term to long-term follow-up of HTO. MATERIALS AND METHODS: We mailed the 2011 Knee Society score (KSS) questionnaires to 234 consecutive patients (295 knees) who had undergone closing-wedge HTO, and 158 patients (202 knees, 68.5%) returned a completed questionnaire. The cohort was divided into two groups depending on the age at the time of surgery, and pairs matched the follow-up period and sex was created. The mean follow-up period was approximately 12 years. KSS scores at the final follow-up were compared between two groups using the Student t test and chi-square test, and the survival rates were calculated using Kaplan-Meier survival curves. RESULTS: The symptom, satisfaction, and expectation scores were not significantly different between the ≤64-year-old patients and ≥65-year-old patients. The functional activities score was significantly lower in older patients than in younger patients. The overall survival rates of HTO were 99.1 ± 0.4% at 5 years, 94.4 ± 1.2% at 10 years, and 84.6 ± 2.7% at 15 years. There was no significant difference in the survival rate after HTO between the two groups divided by the age (p = 0.602). CONCLUSIONS: Pain relief and satisfaction after HTO in older patients were comparable to those in younger patients in the mid-term to long-term follow-up, although the functional activity was affected by age.

Bi-cruciate stabilized total knee arthroplasty can reduce the risk of knee instability associated with posterior tibial slope.

PURPOSE: The purpose of this study was to evaluate the relationship between posterior tibial slope and knee kinematics in bi-cruciate stabilized (BCS) total knee arthroplasty (TKA), which has not been previously reported. METHODS: This computer simulation study evaluated Journey 2 BCS components (Smith & Nephew, Inc., Memphis, TN, USA) implanted in a female patient to simulate weight-bearing stair climbing. Knee kinematics, patellofemoral contact forces, and quadriceps forces during stair climbing (from 86° to 6° of flexion) were computed in the simulation. Six different posterior tibial slope angles (0°-10°) were simulated to evaluate the effect of posterior tibial slope on knee kinematics and forces. RESULTS: At 65° of knee flexion, no anterior sliding of the tibial component occurred if the posterior tibial slope was less than 10°. Anterior contact between the anterior aspect of the tibial post- and the femoral component was observed if the posterior tibial slope was 6° or more. An increase of 10° in posterior tibial slope (relative to 0°) led to a 4.8% decrease in maximum patellofemoral contact force and a 1.2% decrease in maximum quadriceps force. CONCLUSION: BCS TKA has a wide acceptable range of posterior tibial slope for avoiding knee instability if the posterior tibial slope is less than 10°. Surgeons should prioritize avoiding adverse effects over trying to achieve positive effects such as decreasing patellofemoral contact force and quadriceps force by increasing posterior tibial slope. Our study helps surgeons determine the optimal posterior tibial slope during surgery with BCS TKA; posterior tibial slope should not exceed 10° in routine clinical practice.

In vivo kinematics of gait in posterior-stabilized and bicruciate-stabilized total knee arthroplasties using image-matching techniques.

PURPOSE: This study aimed to evaluate the effects of two types of total knee arthroplasty (TKA) designs: posterior-stabilized (PS) and bicruciate-stabilized (BCS) on in vivo kinematics during gait. METHODS: Continuous X-ray images of the gait were taken using a flat panel detector for 23 PS and BCS TKAs. We analyzed the tibiofemoral implant flexion angle, anteroposterior (AP) translation, axial rotation, and anterior/posterior cam-post contact using image-matching techniques. RESULTS: Double knee actions were demonstrated for the PS and BCS design (35 and 61%, respectively, p = 0.08). The tibiofemoral AP positions were significantly more posterior at peak extension (- 1.7 ± 2.2 and 1.0 ± 2.5 mm, respectively, p < 0.01) and anterior at peak flexion (1.3 ± 2.3 and - 0.8 ± 2.8 mm, respectively, p = 0.01) for the PS design than for the BCS design, with a significant difference in AP translation (3.0 ± 3.9 mm anterior and 1.7 ± 2.8 mm posterior, respectively, p < 0.01). Anterior/posterior tibial post contacts were found in 83/4% and 74/30% for the PS and BCS designs, respectively, with a significant difference in posterior contact (p = 0.72/0.04, respectively). CONCLUSION: The knee flexion pattern, tibiofemoral AP translation, axial rotation, and cam-post contact during gait varied, depending on the type of implant, the PS and BCS designs.

Effects of tibial baseplate shape on rotational alignment in total knee arthroplasty: three-dimensional surgical simulation using osteoarthritis knees.

INTRODUCTION: Placement of tibial component is expected to fulfill both maximum surface coverage and recommended anterior-posterior (AP) alignment in total knee arthroplasty (TKA). The purpose of this study is to evaluate the effect of the tibial baseplate shape on AP axis. MATERIALS AND METHODS: Virtual surgery of TKA was performed with three-dimensional bone models reconstructed from 77 osteoarthritis varus knees. Two differently designed tibial baseplates, symmetrically and anatomically, were set to the cut surface under posterior slopes of 0°, 3°, and 7°. The AP axes were defined by connecting the geometrical center of the cut surface with the medial edge (axis MED) and medial 1/3 (axis 1/3MED) of patella tendon attachment. We evaluated the overhang rates as well as the most fitting AP axis which passes through the geometric center. RESULTS: Overhang rates when aligned to axis MED were 12-25% for the symmetrical-type group and 13-22% for the anatomical-type group. Overhang rates when aligned to axis 1/3MED were 42-48% for the symmetrical-type group and 3-7% for the anatomical-type group. The most fitting AP axis of tibial baseplate was located 2.5° external to axis MED for the symmetrical-type group and around 3.3° internal to axis 1/3MED for the anatomical-type group. CONCLUSIONS: Symmetrically or anatomically designed tibial baseplates have their own favored AP axis and specific performance on coverage. When aligned to axis 1/3MED, anatomically designed tibial baseplates will effectively lower the mismatch rates compared to a symmetrically designed tibial baseplate. Orthopaedic surgeons are expected to place the tibial components to the cut surface during TKA with full understanding of the features between different baseplate designs, AP axes, and posterior slopes for an ideal tibial rotational position.

Comparison of the impact of closing wedge versus opening wedge high tibial osteotomy on proximal tibial deformity and subsequent revision to total knee arthroplasty.

PURPOSE: The purpose of this study was to assess the differences in proximal tibial deformity between closing wedge (CW) and opening wedge (OW) high tibial osteotomy (HTO) and their effects on the difficulty of total knee arthroplasty (TKA) conversion. METHODS: Surgical simulations of CW-HTO and OW-HTO were performed on the same 3D computer-aided design knee models reconstructed from computed tomographic datasets of patients (median age 77 years; range 55-87 years; 40 knees) with medial osteoarthritis or osteonecrosis, and proximal tibial deformities were analysed. Subsequent TKA conversion was simulated in both CW and OW models, and the interference between the tibial implant and endosteal cortex was assessed. RESULTS: The difference in the metaphyseal-diaphyseal angle in the CW-HTO and OW-HTO groups was 0.3° ± 0.2° (p < 0.001). The mechanical axis in the CW-HTO group was shifted laterally by 1.8 ± 1.1 mm relative to that in the OW-HTO group (p < 0.001) on the resection surface in TKA. Finally, the TKA tibial implant was substantially closer to the endosteal cortex in the CW-HTO group (mean 5.6 ± 1.6 mm) than to that in the OW-HTO group (mean 7.3 ± 1.6 mm) (p < 0.001). CONCLUSION: The difference in the post-operative angular deformities of the proximal tibia between CW-HTO and OW-HTO was considered to be clinically irrelevant. The risk of interference between TKA tibial implant and endosteal bone was greater after CW-HTO than after OW-HTO. For clinical relevance, the difference between the two techniques has little influence on subsequent TKA difficulty regarding the proximal tibial deformity, although preoperative planning is obligatory, particularly after CW-HTO, to prevent interference with the tibial implant. LEVEL OF EVIDENCE: II.

The Anteroposterior Axis of the Proximal Tibia Can Change After Tibial Resection in Total Knee Arthroplasty: Computer Simulation Using Asian Osteoarthritis Knees.

BACKGROUND: We evaluated the effect of cutting surface on the anteroposterior (AP) axis of the proximal tibia using a 3-dimensional (3D) bone model to ensure proper tibial rotational alignment in total knee arthroplasty. METHODS: 3D bone models were reconstructed from the preoperative computed tomography data of 93 Japanese osteoarthritis knees with varus deformity. The AP axis was defined as the perpendicular bisector of the medial and lateral condylar centers in a 3D coordinate system. Bone cutting of the proximal tibia was performed with various tibial posterior slopes (0°, 3°, 7°) to the mechanical axis, and we compared the AP axes before and after bone cutting. RESULTS: The AP axis before bone cutting crossed a point at about 16% (one-sixth) of the distance from the medial edge of the patellar tendon at its tibial attachment. The AP axis after bone cutting was significantly internally rotated at all posterior slopes: 4.1° at slope 0°, 3.0° at slope 3°, and 2.1° at slope 7°. The percentages of cases with differences of more than 3° or 5° were 66.7% and 34.4% at slope 0°, 53.8% and 24.7% at slope 3°, and 38.3% and 11.8% at slope 7°, respectively. CONCLUSION: The AP axis of the proximal tibia may be rotated internally after resection of the proximal tibia in total knee arthroplasty. Hence, surgeons should recognize the effect of changes in the cutting surface on rotational alignment of the proximal tibia.

Three-dimensional analysis of accuracy of patient-matched instrumentation in total knee arthroplasty: Evaluation of intraoperative techniques and postoperative alignment.

BACKGROUND: It is questionable that the accuracies of patient-matched instrumentation (PMI) have been controversial, even though many surgeons follow manufacturers' recommendations. The purpose of this study was to evaluate the accuracy of intraoperative procedures and the postoperative alignment of the femoral side using PMI with 3-dimensional (3D) analysis. METHODS: Eighteen knees that underwent total knee arthroplasty using MRI-based PMI were assessed. Intraoperative alignment and bone resection errors of the femoral side were evaluated with a CT-based navigation system. A conventional adjustable guide was used to compare cartilage data with that derived by PMI intraoperatively. Postoperative alignment was assessed using a 3D coordinate system with a computer-assisted design software. We also measured the postoperative alignments using conventional alignment guides with the 3D evaluation. RESULTS: Intraoperative coronal alignment with PMI was 90.9° ± 1.6°. Seventeen knees (94.4%) were within 3° of the optimal alignment. Intraoperative rotational alignment of the femoral guide position of PMI was 0.2° ± 1.6°compared with the adjustable guide, with 17 knees (94.4%) differing by 3° or less between the two methods. Maximum differences in coronal and rotation alignment before and after bone cutting were 2.0° and 2.8°, respectively. Postoperative coronal and rotational alignments were 89.4° ± 1.8° and -1.1° ± 1.3°, respectively. In both alignments, 94.4% of cases were within 3° of the optimal value. The PMI group had less outliers than conventional group in rotational alignment (p = 0.018). CONCLUSIONS: Our 3D analysis provided evidence that PMI system resulted in reasonably satisfactory alignments both intraoperatively and postoperatively. Surgeons should be aware that certain surgical techniques including bone cutting, and the associated errors may affect postoperative alignment despite accurate PMI positioning.

Kinematic analysis of stair climbing in rotating platform cruciate-retaining and posterior-stabilized mobile-bearing total knee arthroplasties.

INTRODUCTION: The aim of our study was to compare and contrast the effects of two types of mobile-bearing total knee arthroplasties (TKA), namely, the cruciate-retaining (CR) and posterior-stabilized (PS) TKAs, on clinical outcomes and in vivo kinematics during stair climbing. MATERIALS AND METHODS: The Press-Fit Condylar Sigma rotating platform was used for both CR and PS TKAs. Patient-reported outcomes were assessed using the 2011 Knee Society Score. Quadriceps muscle strength was evaluated by isokinetic dynamometry. In vivo kinematics were evaluated using periodic sagittal plane radiographic images obtained during stair climbing to quantify anteroposterior (AP) tibiofemoral translation, implant flexion and axial rotation angles using image-matching techniques. Outcomes were evaluated in 20 TKAs, which had been undergone with clinical success, including ten knees with CR types and ten knees with PS types. RESULTS: There were no significant differences between the CR and PS TKA groups (p > 0.05) in isometric extensor torque (1.0 ± 0.2 and 1.1 ± 0.6 N m/kg, respectively) or patient-reported score for stair climbing function (4.0 ± 0.5 and 3.8 ± 0.9, respectively). Both types of TKAs showed stable AP translation in the mid range of knee flexion and paradoxical translation in the low range of flexion, with limited rotation, during stair climbing. There were no significant differences between the CR and PS TKA groups (P > 0.05) in anterior translation from 80° to 40° of knee flexion (4.2 ± 1.2 and 3.5 ± 1.6 mm, respectively), posterior translation from 40° to 10° of knee flexion (2.3 ± 1.9 and 2.0 ± 1.5 mm, respectively), and total external rotation (2.8° ± 4.9° and 0.5° ± 5.0°, respectively). CONCLUSIONS: Both CR and PS types of rotating platform mobile-bearing TKAs provided reproducible knee joint kinematics during stair climbing and equivalent clinical outcomes. LEVEL OF EVIDENCE: IV.

Management of Intra-Articular Calcaneal Fractures: Clinical Results of Reduction Technique Using a Bone Spreader.

The purpose of the present study was to examine the clinical results of surgery for intra-articular calcaneal fractures using a calcaneal locking plate and a bone spreader as a reduction tool. Ten patients with intra-articular calcaneal fractures were treated. An extended lateral approach was used. The reduction of the intra-articular fragments of the posterior facet was temporarily held using a bone spreader and Kirschner wires. Internal fixation was achieved with a locking calcaneal plate. Böhler's angle and Preiss' angle were assessed on the day of injury and the day of the final follow-up examination. The step off and gap of the posterior facet were assessed on the day of injury and the first week after surgery. The functional outcome was evaluated using the American Orthopaedic Foot and Ankle Society ankle hindfoot scale score. The mean Böhler's angle ranged from 2.1° ± 11.0° to 30.4° ± 5.0° (p < .0001), the mean Preiss' angle ranged from 23.5° ± 4.5° to 15.5° ± 2.9° (p < .0001), the mean step off ranged from 4.0 ± 1.9 mm to 0.1 ± 0.2 mm (p = .0002), and the mean gap ranged from 2.6 ± 1.0 mm to 1.2 ± 0.6 mm (p = .0035). The mean American Orthopaedic Foot and Ankle Society Ankle-Hindfoot scale score was 89.2 (range 85 to 100) at a mean of 14.3 months after surgery. Our results suggest that a locking calcaneal plate can be used to restore and reduce an intra-articular calcaneal fracture and achieve good clinical results.