What is the optimal alignment of the tibial and femoral components in knee arthroplasty?

Gromov, Kirill; Korchi, Mounim; Thomsen, M; Husted, Henrik; Troelsen, Anders

doi:10.3109/17453674.2014.940573

Cited by 204 publications

(187 citation statements)

References 73 publications

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“…The radiological definition of “normally” aligned TKA knees is debated (Abdel et al 2014, Gromov et al 2014), but most papers on implant survival and radiological alignment have used some deviation from the mechanical or anatomical coronal axis for definement of malalignment. Several studies have used a deviation of 3° from a neutral alignment as a threshold for what is acceptable for good long-term results (Jeffery et al 1991, Ritter et al 1994 and 2011, Berend et al 2004).…”

Section: Discussionmentioning

confidence: 99%

Moderate varus/valgus malalignment after total knee arthroplasty has little effect on knee function or muscle strength

Stučinskas¹,

Robertsson²,

Širka³

et al. 2015

Acta Orthopaedica

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Background and purpose — Postoperative muscle strength and component alignment are important factors affecting functional results after total knee arthroplasty (TKA). We are not aware of any studies that have investigated the relationship between them. We therefore investigated whether coronal malalignment of the mechanical axis and/or of individual implant components would affect knee muscle strength and function 1 year after TKA surgery.Patients and methods — We included 120 consecutive osteoarthritis (OA) patients admitted for TKA. Preoperative active range of motion (ROM) of the knee, patient age, sex, and BMI were recorded and the Knee Society score (KSS) and knee joint extensor/flexor muscle strength were assessed. At 1-year follow-up, the mechanical and coronal component alignment was measured from a postoperative long standing radiograph, and ROM, KSS, and muscle strength measurements were taken in 91 patients. Functional outcome and muscle strength measurements were compared between normally aligned and malaligned TKA groups.Results — 29 of 91 TKAs were malaligned, i.e. they deviated more than 3° from the neutral mechanical axis. 18 femoral components and 15 tibial components were malaligned. Before surgery, the malaligned and normally aligned groups were similar regarding sex distribution, BMI, ROM, KSS, and muscle strength. At the 1-year follow-up, the differences between the groups regarding knee joint function and muscle strength were small, not statistically significant, and barely clinically relevant.Interpretation — Moderate varus/valgus malalignment of the mechanical axis or of individual components has no relevant clinical effect on function or muscle strength 1 year after TKA surgery.

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Section: Discussionmentioning

confidence: 99%

Moderate varus/valgus malalignment after total knee arthroplasty has little effect on knee function or muscle strength

Stučinskas¹,

Robertsson²,

Širka³

et al. 2015

Acta Orthopaedica

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“…Geometric differences between these axes have been compared in various studies (Berger et al, 1993; Eckhoff et al, 2001; Most et al, 2004; Victor et al, 2009). However, the differences of femoral condylar motion measured using these axes are still not well defined during dynamic motions of the knee (Gromov et al, 2014; Victor, 2009). …”

Section: Introductionmentioning

confidence: 99%

In-vivo analysis of flexion axes of the knee: Femoral condylar motion during dynamic knee flexion

Tsai

Rubash

et al. 2016

Clinical Biomechanics

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Background Transepicondylar axis and geometrical center axis are widely used for investigation of the knee kinematics and component alignment in total knee arthroplasty. However, the kinematic characteristics of these knee axes are not well defined in literature. This study investigated the femoral condylar motion during a dynamic flexion of the knee using different flexion axes. Methods Twenty healthy knees (10 males and 10 females) were CT scanned to create 3D anatomic models. The subjects performed a single leg flexion from full extension to maximal flexion while the knees were imaged using fluoroscopes. The femoral condyle translations in anterior-posterior and proximal-distal directions were described using clinical transepicondylar axis, surgical transepicondylar axis and geometrical center axis. Findings The subjects achieved −9.4° (SD 3.0°) hyperextension at full extension and 116.4° (SD 9.0°) at maximal flexion of the knee. The anterior-posterior translations of the three flexion axes were different for the medial condyle, but similar for the lateral condyle. Substantial variations of the condylar motion in proximal-distal direction were measured along the flexion path using these axes. While the surgical transepicondylar axis maintained condyle heights from full extension to 60° of flexion, geometrical center axis showed little changes in condyle heights from 30° to maximal knee flexion. The condyles moved distally beyond 90° flexion using both transepicondylar axes. Interpretation The femoral condylar motion measurement is sensitive to the selection of flexion axis. The different kinematic features of these axes provide an insightful reference when selecting a flexion axis in total knee arthroplasty component alignment.

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“…An optimal sagittal alignment of the posterior tibial slope is between 0°and 7°, while optimal placement of the femoral component in the sagittal plane should be within 0°-3°of flexion [9]. In this regard, the current study resulted in one outlier for the tibia component on the sagittal plane.…”

Section: Discussionmentioning

confidence: 79%

Accuracy of CT-based patient-specific guides for total knee arthroplasty in patients with post-traumatic osteoarthritis

Schotanus

Haaren

Hendrickx

et al. 2015

Eur J Orthop Surg Traumatol

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Published clinical trials who studied the accuracy of patient-specific guides (PSG) for total knee arthroplasty exclude patients with articular deformity of the knee joint. We prospectively analysed a series of 30 patients with post-traumatic osteoarthritis of the knee joint with use of PSG. At 1 year post-operative, the achieved biomechanical (HKA) axis and varus/valgus of the femur and tibia components were measured on anterior-posterior (AP) long-standing weight-bearing radiographs. Flexion/extension of the femoral and AP slope of the tibia component was measured on standard lateral radiographs. Percentages >3° deviation of the pre-operative planned HKA axis and individual implant components were considered as outliers. Approved and used implant size, median blood loss (ml) and operation time (min) were obtained from the operation records. Pre- and 1-year post-operative patient-reported outcome measures (PROMs) were performed. Eighty-three per cent of the patients had a HKA axis restored <3° of the pre-operative planned alignment. Varus/valgus outliers were 0.0 and 6.7 % for the femoral and tibial components, respectively. Percentages of outliers of flexion/extension were 36.7 % for the femoral component and 10.0 % for the AP slope of the tibial component. Median blood loss was 300 ml (50-700), while operation time was 67 min (44-144). In 20 % of all cases, the approved implant size was changed into one size smaller. One-year post-operative PROMs improved significantly. We conclude that the accuracy of CT-based PSG is not impaired in patients with post-traumatic osteoarthritis and this modality can restore biomechanical limb alignment.

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What is the optimal alignment of the tibial and femoral components in knee arthroplasty?

Cited by 204 publications

References 73 publications

Moderate varus/valgus malalignment after total knee arthroplasty has little effect on knee function or muscle strength

Moderate varus/valgus malalignment after total knee arthroplasty has little effect on knee function or muscle strength

In-vivo analysis of flexion axes of the knee: Femoral condylar motion during dynamic knee flexion

Accuracy of CT-based patient-specific guides for total knee arthroplasty in patients with post-traumatic osteoarthritis

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