Obliquity of tibial component after unicompartmental knee arthroplasty

Asada, Shigeki; Inoue, Shunsuke; Tsukamoto, Ichiro; Mori, Satoshi; Akagi, Masao

doi:10.1016/j.knee.2018.12.013

Cited by 26 publications

(33 citation statements)

References 30 publications

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“…They also recommended the 3° varus cut, however, because in some reports, an excessive varus cut was shown to decrease the implant survival in UKA. 4) Another computer simulation study recommended a slight varus implantation to reduce the peak stress on the medial cortex in the mobile-bearing OUKA. 7) Sekiguchi et al 8) reported a computer simulation study where a 2° varus cut showed the best kinematics and ligament tension.…”

Section: Discussionmentioning

confidence: 99%

“…3) A slight varus cut has been recommended to prevent fractures because it can distance the keel from the cortex. Regarding fixed-bearing UKA, a slight varus implantation has been a popular technique to reduce mechanical stress 4) and cutting instru-ments, and computer navigation and robotic surgery can be used to adjust the varus cut angle. In OUKA, however, only orthogonal cuts against the tibial axis are available.…”

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confidence: 99%

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A Novel Technique for Varus Tibial Cutting for Oxford Unicompartmental Knee Arthroplasty

et al. 2020

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To reduce the stress on the medial tibial cortex and to decrease the risk of fracture, a varus cut of the tibia appears to be a reasonable alternative to the orthogonal cut by conventional methods. We present a new instrument and procedure, which enables a varus tibial cut for Oxford unicompartmental knee arthroplasty. We used a custom-made, slidable fixator instead of the standard fixator to set the extramedullary rod on the leg. We also made a numeric formula and a chart to arrange the varus cutting angle using the length of the mediolateral shift of the distal end and the longitudinal extension length of the extramedullary tibial rod. A varus cut up to 4.5° can be controlled. This technique is a simple and useful means of obtaining a varus tibial cut for Oxford unicompartmental knee arthroplasty.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

A Novel Technique for Varus Tibial Cutting for Oxford Unicompartmental Knee Arthroplasty

et al. 2020

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“…For example, other authors from Japan suggested the need for a tibial component with 4 or 5 degrees varus instead of our recommendation of 2 or 3 degrees varus to maintain the joint line parallelism. 34 Further prospective studies are needed to elucidate the tibial component's more precise optimal range. Regarding KOOS subscale of symptom, the present study suggested that postoperative knee flexion angles affected the clinical scores after Oxford UKA at both postoperative years 1 and 2.…”

Section: Discussionmentioning

confidence: 99%

Implant Alignment and Patient Factors Affecting the Short-Term Patient-Reported Clinical Outcomes after Oxford Unicompartmental Knee Arthroplasty

et al. 2020

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This study aims at clarifying implant alignment and other patient factors' influence on clinical outcomes, particularly on patient-reported outcomes (PRO), following Oxford unicompartmental knee arthroplasty (OUKA). A total of 142 patients after OUKA were divided into two groups according to the validated Japanese version of the knee injury and osteoarthritis outcome score (KOOS) for each subscale of pain, symptoms, and activities of daily living (ADL) at postoperative year 1 and 2: group 1 had ≥80 scores and group 2 had <80 scores. Postoperative clinical and radiographical findings were then compared among groups in each subscale. Using postoperative year 1 and 2 data, a multivariable logistic regression analysis was conducted to clarify factors for clinical outcomes' improvement. In the analysis of KOOS subscale of symptoms at postoperative year 1, gender distribution, preoperative body mass index, and postoperative maximum knee flexion angles differed significantly among groups. In the analysis for KOOS subscale of ADL, significant differences were observed in postoperative tibial component varus angles. Multivariable logistic regression analysis revealed that all of these parameters significantly related to ≥80 KOOS scores of each subscale at postoperative year 1. Additionally, at postoperative year 2, larger postoperative knee flexion angles and tibial component varus angles related to ≥80 KOOS subscale of symptoms and ADL were observed. In conclusion, tibial component's larger varus alignment was associated with the better PRO at both 1 and 2 years after OUKA. Importantly, larger postoperative knee flexion angle helped achieve good short-term PRO after OUKA.

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“…Varus >4 or valgus alignment caused excessive Medial/lateral (ML) translation, which could be related to feelings of instability and could potentially have negative effects on clinical outcomes and implant durability 6 . Recently, Asada et al 5 indicated that the tibial component should be installed 4 to 2 varus to the tibial mechanical axis to maintain joint-line parallelism for UKA in medial osteoarthritis patients. Barbadoro et al used the maximal total point motion (MTPM) as a predictor for implant loosening, and reported that there is correlation between varus orientation of the tibial component and MTPM from radiostereometry in UKA.…”

Section: Introductionmentioning

confidence: 99%

Impact of Tibial Component Coronal Alignment on Knee Joint Biomechanics Following Fixed‐bearing Unicompartmental Knee Arthroplasty: A Finite Element Analysis

Nie

Shen

2021

Orthopaedic Surgery

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Objective: Unicompartmental knee arthroplasty (UKA) has indicated a higher rate of revision than total knee arthroplasty (TKA). The success of UKA depends on UKA component alignment, fixation, and soft tissue integrity. The purpose of this study was to investigate the effects of different tibial component alignments in the coronal plane on the stress distribution in UKA. It was hypothesized that the stress distribution would approach native knee when the tibial component was neutrally positioned. Methods:The left legs from two healthy volunteers were considered to represent the geometric native knee models.All bones within the knee joint were extracted from the three-dimensional (3D) computed tomography (CT). MRI was used to generate cartilage, menisci, and four major ligaments. The UKA components were virtually implanted in the medial compartment of the knee model using MIMICS. A total of five different configurations of UKA tibial obliquity in the coronal plane (neutral, 3 varus, 6 varus, 3 valgus, and 6 valgus) were adopted and investigated. Subjectspecific inhomogeneous material properties of bones were used in the finite element analysis (FEA) model. The von Mises stress in the tibia platform and proximal tibia, and the load distribution between the medial and lateral compartments were extracted and compared among the five different configurations. Results:The inhomogeneous material properties of the trabecular bone were closer to real physics than traditional homogeneous methods. Neutral and 3 varus alignments of the tibial component in the coronal plane have better stress distribution between medial and lateral compartment as healthy knee models, and less stress-shielding effects than other UKA configurations. The stress pathway under the medial tibia platform in neutral and 3 varus UKA configurations was similar and more obvious than the other three UKA configurations. Notably, the stress of the medial tibia platform in the 3 varus UKA models was more homogenous than the neutral UKA configuration. The 6 varus, 3 valgus, and 6 valgus UKA models had higher stress at the location of anterolateral and posterolateral tibia platform than other UKA configurations. Conclusion:Neutral or 3 varus positioned in the coronal plane for the tibial component could be the optimal alignment for UKA. Excessive varus or valgus obliquity in the coronal plane lead to significant differences in bone stress transfer and load distribution in the knee, and increase the risk of UKA failure.

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Obliquity of tibial component after unicompartmental knee arthroplasty

Cited by 26 publications

References 30 publications

A Novel Technique for Varus Tibial Cutting for Oxford Unicompartmental Knee Arthroplasty

A Novel Technique for Varus Tibial Cutting for Oxford Unicompartmental Knee Arthroplasty

Implant Alignment and Patient Factors Affecting the Short-Term Patient-Reported Clinical Outcomes after Oxford Unicompartmental Knee Arthroplasty

Impact of Tibial Component Coronal Alignment on Knee Joint Biomechanics Following Fixed‐bearing Unicompartmental Knee Arthroplasty: A Finite Element Analysis

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