Variation in Optimal Sagittal Alignment of the Femoral Component in Total Knee Arthroplasty

AbstractTraditionally, a rigid intramedullary rod has been used as the reference guide for femoral cutting in total knee arthroplasty (TKA). However, correct positioning of this rigid rod is difficult, especially in the knees with severe distal femoral sagittal bowing. A flexible intramedullary rod has been developed to address this problem. This study was performed to compare the sagittal alignment and clinical outcomes of TKAs performed with flexible and rigid femoral intramedullary guides. Thirty-eight knees that underwent primary TKAs with flexible intramedullary rods as femoral cutting guides were matched according to patient height and sex with 38 knees that underwent TKAs using conventional rigid rods. Clinical outcomes, including the range of motion and functional scores, and radiological variables, including the distal femoral bowing angle (DFBA), femoral component flexion angle (FFA), and mediolateral overhang and anteroposterior (AP) oversizing of femoral components, were evaluated. Clinical and radiological outcomes did not differ significantly between the flexible rod and conventional rigid rod groups. A subgroup analysis of knees with severe distal femoral sagittal bowing (DFBA >4 degrees) showed that the FFA was significantly larger in the flexible rod group than in the rigid rod group, with an average difference of 3 degrees (5.2 ± 2.4 vs. 2.2 ± 1.6 degrees, respectively, p = 0.022). In addition, the incidence of AP oversizing of femoral components was lower in the flexible rod group than in the rigid rod group (11.1 vs. 60.0%, respectively, p = 0.027). Relative to TKA with a rigid rod, TKA performed with a flexible femoral intramedullary guide resulted in more flexed sagittal alignment of femoral components in patients with severe distal femoral sagittal bowing. This greater flexion of the femoral component resulted in less AP oversizing. However, the use of a flexible rod had no impact on short-term clinical outcomes.

Download Full-text

Excessive flexed position of the femoral component was associated with poor new Knee Society Score after total knee arthroplasty with the Bi-Surface knee prosthesis

The Bone & Joint Journal ◽

10.1302/0301-620x.102b6.bjj-2019-1531.r1 ◽

2020 ◽

Vol 102-B (6_Supple_A) ◽

pp. 36-42

Author(s):

Kohei Nishitani ◽

Shinichi Kuriyama ◽

Shinichiro Nakamura ◽

Naoki Umatani ◽

Hiromu Ito ◽

...

Keyword(s):

Total Knee Arthroplasty ◽

Clinical Outcomes ◽

Femoral Component ◽

Knee Arthroplasty ◽

Knee Society Score ◽

Sagittal Alignment ◽

Knee Prosthesis ◽

Rear Surface ◽

Functional Activities ◽

Total Knee

Aims This study aimed to evaluate the association between the sagittal alignment of the femoral component in total knee arthroplasty (TKA) and new Knee Society Score (2011KSS), under the hypothesis that outliers such as the excessive extended or flexed femoral component were related to worse clinical outcomes. Methods A group of 156 knees (134 F:22 M) in 133 patients with a mean age 75.8 years (SD 6.4) who underwent TKA with the cruciate-substituting Bi-Surface Knee prosthesis were retrospectively enrolled. On lateral radiographs, γ angle (the angle between the distal femoral axis and the line perpendicular to the distal rear surface of the femoral component) was measured, and the patients were divided into four groups according to the γ angle. The 2011KSSs among groups were compared using the Kruskal-Wallis test. A secondary regression analysis was used to investigate the association between the 2011KSS and γ angle. Results According to the mean and SD of γ angle (γ, 4.0 SD 3.0°), four groups (Extended or minor flexed group, −0.5° ≤ γ < 2.5° (n = 54)), Mild flexed group (2.5° ≤ γ < 5.5° (n = 63)), Moderate flexed group (5.5° ≤ γ < 8.5° (n = 26)), and Excessive flexed group (8.5° ≤ γ (n = 13)) were defined. The Excessive flexed group showed worse 2011KSSs in all subdomains (Symptoms, Satisfaction, Expectations, and Functional activities) than the Mild flexed group. Secondary regression showed a convex upward function, and the scores were highest at γ = 3.0°, 4.0°, and 3.0° in Satisfaction, Expectations, and Functional activities, respectively. Conclusion The groups with a sagittal alignment of the femoral component > 8.5° showed inferior clinical outcomes in 2011KSSs. Secondary regression analyses showed that mild flexion of the femoral component was associated with the highest score. When implanting the Bi-Surface Knee prosthesis surgeons should pay careful attention to avoiding flexing the femoral component extensively during TKA. Our findings may be applicable to other implant designs. Cite this article: Bone Joint J 2020;102-B(6 Supple A):36–42.

Download Full-text

Sagittal Alignment of the Femoral Component and Patient Height Are Associated With Persisting Flexion Contracture After Primary Total Knee Arthroplasty

The Journal of Arthroplasty ◽

10.1016/j.arth.2019.02.051 ◽

2019 ◽

Vol 34 (7) ◽

pp. 1476-1482 ◽

Cited By ~ 3

Author(s):

Yoshinori Okamoto ◽

Shuhei Otsuki ◽

Mikio Nakajima ◽

Tsuyoshi Jotoku ◽

Hitoshi Wakama ◽

...

Keyword(s):

Total Knee Arthroplasty ◽

Femoral Component ◽

Knee Arthroplasty ◽

Sagittal Alignment ◽

Primary Total Knee Arthroplasty ◽

Flexion Contracture ◽

Total Knee ◽

Primary Total Knee

Download Full-text

Sagittal alignment of the cemented femoral component in revision total knee arthroplasty influences the anterior and posterior condylar offset: Stem length does not affect these variables

The Knee ◽

10.1016/j.knee.2019.10.025 ◽

2020 ◽

Vol 27 (2) ◽

pp. 477-484

Author(s):

N. Ng ◽

J.T. Patton ◽

R. Burnett ◽

N.D. Clement

Keyword(s):

Total Knee Arthroplasty ◽

Femoral Component ◽

Knee Arthroplasty ◽

Sagittal Alignment ◽

Revision Total Knee Arthroplasty ◽

Stem Length ◽

Posterior Condylar Offset ◽

Posterior Condylar ◽

Total Knee

Download Full-text

Isolated Liner Revision for Total Knee Arthroplasty Instability: A Road That Should Remain Less Taken

The Journal of Knee Surgery ◽

10.1055/s-0040-1721091 ◽

2020 ◽

Author(s):

Jason D. Tegethoff ◽

Rafael Walker-Santiago ◽

William M. Ralston ◽

James A. Keeney

Keyword(s):

Total Knee Arthroplasty ◽

Femoral Component ◽

Knee Arthroplasty ◽

Primary Total Knee Arthroplasty ◽

P Value ◽

Surgical Morbidity ◽

Exact Test ◽

Total Knee ◽

Component Revision

AbstractIsolated polyethylene liner exchange (IPLE) is infrequently selected as a treatment approach for patients with primary total knee arthroplasty (TKA) prosthetic joint instability. Potential advantages of less immediate surgical morbidity, faster recovery, and lower procedural cost need to be measured against reoperation and re-revision risk. Few published studies have directly compared IPLE with combined tibial and femoral component revision to treat patients with primary TKA instability. After obtaining institutional review board (IRB) approval, we performed a retrospective comparison of 20 patients treated with IPLE and 126 patients treated with tibial and femoral component revisions at a single institution between 2011 and 2018. Patient demographic characteristics, medical comorbidities, time to initial revision TKA, and reoperation (90 days, <2 years, and >2 years) were assessed using paired Student's t-test or Fisher's exact test with a p-value <0.01 used to determine significance. Patients undergoing IPLE were more likely to undergo reoperation (60.0 vs. 17.5%, p = 0.001), component revision surgery (45.0 vs. 8.7%, p = 0.002), and component revision within 2 years (30.0 vs. 1.6%, p < 0.0001). Differences in 90-day reoperation (p = 0.14) and revision >2 years (p = 0.19) were not significant. Reoperation for instability (30.0 vs. 4.0%, p < 0.001) and infection (20.0 vs. 1.6%, p < 0.01) were both higher in the IPLE group. IPLE does not provide consistent benefits for patients undergoing TKA revision for instability. Considerations for lower immediate postoperative morbidity and cost need to be carefully measured against long-term consequences of reoperation, delayed component revision, and increased long-term costs of multiple surgical procedures. This is a level III, case–control study.

Download Full-text