Mechanical alignment for primary TKA may change both knee phenotype and joint line obliquity without influencing clinical outcomes: a study comparing restored and unrestored joint line obliquity

Objectives:The purpose of this study was to compare the intra-operative benefits and the clinical outcomes from kinematic or mechanical alignment for total knee arthroplasty (TKA) in patients undergoing revision of failed unicompartmental kneel arthroplasty (UKA) to TKA.Methods:Ten revisions were performed with a kinematic alignment technique and 11 with a mechanical alignment. Measurements of the hip-knee-ankle angle (HKA), the lateral distal femoral angle (LDFA), and the medial proximal tibial angle (MPTA) were performed using long-leg radiographs. The need for augments, stems, and constrained inserts was compared between groups. Clinical outcomes were compared using the WOMAC score along with maximum distance walked as well as knee range of motion obtained prior to discharge. All data was obtained by a retrospective review of patient files.Results:The kinematic group required less augments, stems, and constrained inserts than the mechanical group and thinner polyethylene bearings. There were significant differences in the lateral distal femoral angle (LDFA) and the medial proximal tibial angle (MPTA) between the two groups (p<0.05). The mean WOMAC score obtained at discharge was better in the kinematic group as was mean knee flexion. At last follow up of 34 months for the kinematic group and 58 months for the mechanical group, no orthopedic complications or reoperations were recorded.Conclusion:Although this study has a small patient cohort, our results suggest that kinematic alignment for TKA after UKA revision is an attractive method. Further studies are warranted.

Download Full-text

The iAssist Navigation System Demonstrated Superior Radiological Outcomes in Restoring Mechanical Alignment and Component Sagittal Positioning in Total Knee Arthroplasty

10.21203/rs.3.rs-117247/v1 ◽

2020 ◽

Author(s):

Jiaxiang Gao ◽

Yunfei Hou ◽

Zhichang Li ◽

Runjun Li ◽

Yan Ke ◽

...

Keyword(s):

Total Knee Arthroplasty ◽

Clinical Outcomes ◽

Knee Arthroplasty ◽

Navigation System ◽

Clinical Parameters ◽

Mechanical Alignment ◽

Absolute Deviation ◽

Total Knee ◽

The Absolute

Abstract Background: This study aimed to determine whether the iAssist navigation system (NAV) could improve the accuracy of restoring mechanical axis (MA), component positioning, and clinical outcomes compared to conventional (CON) total knee arthroplasty (TKA). Methods: A total of 301 consecutive patients (NAV: 27, CON: 274) were included. A 1:4 propensity score matching (PSM) was performed between the two groups according to preoperative demographic and clinical parameters. The postoperative MA, femoral coronal angle (FCA), femoral sagittal angle (FSA), tibial coronal angle (TCA) and tibial sagittal angle (TSA) were compared. Absolute deviations of aforementioned angles were calculated as the absolute value of difference between the exact and ideal value and defined as appropriate if within 3°, otherwise regarded as outliers. Additional clinical parameters, including the Knee Society knee and function scores (KSKS and KSFS) and range of motion (ROM), were assessed at the final follow-up (mean follow-up time was 21.88 and 21.56 months respectively for NAV and CON group). Results: A total of 98 patients/102 knees were analyzed after the PSM (NAV: 21 patients/24 knees, CON: 77 patients/78 knees). In the NAV group, the mean MA, FCA and TSA were significantly improved (p = 0.019, 0.006, <0.001, respectively). Proportions of TKAs within a ±3°deviation were significantly improved in all the postoperative radiological variables except for TCA (p = 0.003, 0.021, 0,017, 0.013, respectively for MA, FCA, FSA, and TSA). The absolute deviations of FSA and TSA were also significantly lower in the NAV group (p = 0.016, 0.048, respectively). In particular, no significant differences were found in either mean value, absolute deviation or outlier ratio of TCA between two groups. For the clinical outcomes, there were no significant differences between two groups, although KSKS, KSFS and ROM (p<0.01, respectively) dramatically improved compared to baseline. Conclusions: We suggested that the iAssist system could improve the accuracy and precision of mechanical alignment and component positioning without significant improvement of clinical outcomes. Further long-term high-quality studies are necessary to validate the results.

Download Full-text

How joint line orientation affects the amount of bone resected in mechanically aligned TKA: a retrospective clinical-radiographic correlational study

10.21203/rs.3.rs-38300/v2 ◽

2021 ◽

Author(s):

Zhiwei Wang ◽

Yang Yu ◽

Liang Wen ◽

Desi Ma ◽

Tiebing Qu

Keyword(s):

Weight Bearing ◽

Case Series ◽

Joint Line ◽

Line Orientation ◽

Mechanical Alignment ◽

Bone Resection ◽

Current Case ◽

Technical Parameters ◽

Knee Oa ◽

Total Knee

Abstract Background: Discrepancies in bone resection between the medial and lateral compartments is very common in total knee replacement (TKA) when mechanical alignment (MA) is used. The purpose of this study was to explore whether and how joint line orientation affects the gross amount of bone resected in mechanically aligned TKA.Methods: A total of 112 patients (137 knees) diagnosed with osteoarthritis (OA) were included. Bone resection simulations were conducted in the coronal view using full-length weight-bearing radiographs per the technical parameters of MA, and the feasibility of simulated osteotomy was verified via intraoperative caliper measurement. Correlation and regression analyses were conducted comparing the amount of bone resected and various parameters, including hip-knee-ankle (HKA) angle, mechanical lateral distal femoral angle (mLDFA), joint line congruency angle (JLCA), and medial proximal tibial angle (MPTA). Moreover, any intraoperative bone resection adjustments that were made were retrospectively collected using a medical record query system.Results: All knees in the current case series could be artificially divided into 4 subgroups: 84 varus knees (61.3%) with valgus femurs in subgroup 1, 32 varus knees (23.4%) with varus femurs in subgroup 2, 14 valgus knees (10.2%) with varus tibias in subgroup 3, and 7 valgus knees (5.1%) with valgus tibias in subgroup 4. Simulated bone resection thickness was highly consistent with intraoperative measurements. MPTA and mLDFA were positively correlated with the amount of bone resected in subgroup 1. The regression equation was: Maximum resection thickness (mm) = 0.556*mLDFA (deg.) + 0.098*MPTA (deg.) -39.74; R2=0.808. Similarly, intraoperative bone resection adjustments also showed a correlation with mLDFA in subgroup 1.Conclusions: Deformities in knee OA can be divided into 4 subgroups based on the alignment of extremities and the joint line orientation. When TKA is performed in varus knees with valgus femurs using conventional instruments and mechanical alignment techniques, the amount of bone resected in the coronal plane demonstrates a linear relationship with the patient’s mLDFA.

Download Full-text

Is there difference and correlation between medial and lateral tibial plateau coronal obliquity in native knee? A radiographic study

Journal of Orthopaedics Trauma and Rehabilitation ◽

10.1177/22104917211056940 ◽

2021 ◽

Vol 28 ◽

pp. 221049172110569

Author(s):

Thomas Ka Chun Leung ◽

Will Wai Hong Lau ◽

Wing Chiu Fung ◽

Vincent Wai Kwan Chan ◽

Amy Cheung ◽

...

Keyword(s):

Knee Joint ◽

Tibial Plateau ◽

Articular Surface ◽

Young Patients ◽

Joint Line ◽

Significant Implication ◽

Lateral Tibial Plateau ◽

Radiographic Measurements ◽

Significant Difference ◽

Joint Line Obliquity

Background/Purpose Knee joint line is commonly defined as a tangent to medial and lateral tibial plateaus in various radiographic measurements. We aim to investigate radiographic differences between medial and lateral knee joint line coronal obliquity. It has significant implication on radiographic analysis following unicompartmental knee arthroplasty. Methods We analysed the knee radiographs of 48 young patients (mean age 25.1 + /-5.6 years) with 50 anterior cruciate ligament-deficient knees. Medial and lateral tibial plateau coronal obliquity were defined as angles between femoral knee joint line and the tangent to articular surface of each tibial plateau. Mediolateral differences and linear correlation were analysed. Results Significant difference was found between medial (mean = -1.5, SD = 2.4 degrees) and lateral obliquity (mean = + 0.6, SD = 3.0 degrees) ( p < 0.001). The mean mediolateral difference was 3.1 degrees (SD = 2.8, range 0–11.8 degrees), without significant correlation (r = 0.085, p = 0.56). Conclusion Mediolateral differences exist in knee joint line obliquity. Each compartment should be considered separately when measuring knee joint line obliquity.

Download Full-text

Association of Preoperative Tibial Varus Deformity With Joint Line Orientation and Clinical Outcome After Open-Wedge High Tibial Osteotomy for Medial Compartment Osteoarthritis: A Propensity Score–Matched Analysis

The American Journal of Sports Medicine ◽

10.1177/03635465211044146 ◽

2021 ◽

pp. 036354652110441

Author(s):

Jun-Gu Park ◽

Seung-Beom Han ◽

Ki-Mo Jang

Keyword(s):

Varus Deformity ◽

Important Change ◽

Joint Line ◽

Ankle Angle ◽

Joint Line Obliquity ◽

Group 2 ◽

Hip Knee Ankle Angle ◽

Minimally Important Change ◽

Group 1

Background: The correction of lower limb deformity should be performed at the site of deformity to maintain knee joint orientation. However, the effectiveness of open-wedge high tibial osteotomy (OWHTO) for treatment of medial osteoarthritis in varus malalignment without definite tibial varus deformity has not been confirmed. Purpose/Hypothesis: This study aimed to compare the clinical and radiologic outcomes after OWHTO in patients without tibial varus deformity versus patients with tibial varus deformity after matching for confounding factors. We hypothesized that these outcomes would be inferior in patients without tibial varus deformity. Study Design: Cohort study; Level of evidence, 3. Methods: The outcomes of 133 OWHTO operations for medial osteoarthritis in 107 patients were retrospectively reviewed after follow-up for >2 years. The patients were divided into group 1 (tibia with varus deformity, preoperative medial proximal tibial angle [MPTA] <85°) and group 2 (tibia without varus deformity, preoperative MPTA ≥85°). The confounding factors, including patient characteristics, preoperative limb alignment, degree of osteoarthritis, and correction angle, were matched using propensity score matching. The radiologic parameters, including MPTA and joint line obliquity, were evaluated preoperatively, between 6 and 12 months postoperatively, and at the last follow-up. The radiologic outcomes were assessed using the medial joint space width and mechanical hip-knee-ankle angle. The clinical outcomes were evaluated by the Hospital for Special Surgery knee score, Knee Society Score (KSS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. The clinical and radiologic outcomes were compared between the groups. The proportions of patients achieving improvement in the clinical outcome beyond the minimal clinically important difference (MCID) or minimally important change were compared between the groups. Results: After propensity score matching, 32 patients were selected for each group. The mechanical hip-knee-ankle angle was corrected without significant difference from a mean ± SD varus angle of 8.0°± 3.3° to valgus angle of −3.2°± 2.5° in group 1 and from varus 8.0°± 3.6° to valgus −3.9°± 1.7° in group 2. The preoperative joint line obliquity was greater in group 2 as compared with group 1 (2.2°± 2.2° vs −0.4°± 1.8°, P < .001). With a similar 10° correction angle, the postoperative MPTA and joint line obliquity were 96.6°± 2.5° and 5.3°± 2.3°, respectively, in group 2, which were greater than 94.0°± 2.6° and 3.5°± 1.8°, respectively, in group 1 (both P < .001). The changes in joint space width and mechanical hip-knee-ankle angle were not significantly different between the groups over the follow-up period. At the last follow-up, the postoperative KSS objective score and WOMAC pain score in terms of symptom improvement were not significantly different between groups ( P = .092 and .068). However, the postoperative KSS and WOMAC functional scores were significantly worse in group 2 than in group 1 (77.3 ± 14.1 vs 84.4 ± 11.6, P = .044; 10.3 ± 9.2 vs 5.6 ± 7.2, P = .001). In group 1, 96.9% and 100% of patients showed improvements of >10 points in the KSS functional score and 15 points in the WOMAC functional score based on MCID or minimally important change. Meanwhile, 65.6% and 81.3% of patients in group 2, which were significantly lower than those of group 1, were improved beyond the MCID or minimally important change ( P = .001 and .024, respectively). Conclusion: In varus malalignment, the knee joint line was more oblique in patients without tibial varus deformity after OWHTO pre- and postoperatively. The clinical outcomes in terms of functional scores were inferior in patients without tibial varus deformity. However, the radiologic outcomes and symptomatic improvement after OWHTO were comparable regardless of the preoperative tibial varus deformity on midterm follow-up.

Download Full-text