Sagittal plane positioning of the femoral component in total knee arthroplasty

Abstract Purpose To determine the preferred knee in patients with both one total and one unicompartmental knee arthroplasty. Method Patients simply with a unicompartmental (UKA) and total knee arthroplasty (TKA) on contralateral sides were retrospectively screened from three senior knee surgeon’s logs over a 15 year period. Patients safe and free from other diseases to affect gait were approached. A total of 16 patients (mean age 70 ± 8) agreed to ground reaction force testing on an instrumented treadmill at a fair pace and incline. A gender-ratio identical group of 16 healthy control subjects (mean age 67 ± 10) and 16 patients with ipsilateral medial knee OA (mean age 66 ± 7) were analysed to compare. Results Radiographically the mode preoperative Kellgren–Lawrence knee grade for each side was 3. Postoperatively, the TKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 89° with a mean posterior slope of 5° in the sagittal plane. The UKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 86° with a mean posterior slope of 4° in the sagittal plane. In 7 patients, the TKA was the first procedure, while 6 for the UKA and 3 done simultaneously. Gait analysis demonstrated in both walking conditions the UKA limb was the preferred side through all phases of loading (p < 0.05) and nearer to normal than the TKA limb when compared to healthy controls and patients with knee OA. The greatest difference was observed between the transition of weight acceptance and midstance (p = 0.008), when 22% more load was taken by the UKA side. Conclusion By using a dynamic metric of an everyday activity, a distinct gait difference between differing arthroplasty types were established. A more natural loading pattern can be achieved with unicompartmentals as compared to total knees. Level of evidence Retrospective comparative study, Level III.

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Sagittal flexion arc evaluation for a modern generation single-radius femoral component design

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411918759136 ◽

2018 ◽

Vol 232 (4) ◽

pp. 412-417 ◽

Cited By ~ 1

Author(s):

David John Deehan ◽

K Milton Ghosh ◽

Alasdair Blain ◽

Lee Longstaff ◽

Steven Rushton

Keyword(s):

Total Knee Arthroplasty ◽

Femoral Component ◽

Knee Arthroplasty ◽

Sagittal Plane ◽

Transepicondylar Axis ◽

Component Design ◽

Cast Doubt ◽

Kinematic Behaviour ◽

Total Knee ◽

Single Radius

Single-radius femoral total knee design aims to deliver improved kinematic behaviour when compared to the standard two-radii geometry. This study has evaluated the behaviour, through a functional range of motion in the sagittal plane, of a single-radius femoral component compared to a dual-radius standard knee construct. Particular focus was placed on how the flexion axes of the native and replaced knee approximated to the transepicondylar axis through a loaded navigated knee design. Significant differences in flexion arcs were noted between the native and total knee arthroplasty state. These arcs were not uniform in all knees and did not display single-radius behaviour. There were no significant differences in the location of flexion axes in the native and total knee arthroplasty knee. Both exhibited similar posterior and inferior transverse axes of motion with respect to the anatomical epicondylar axis. This work has cast doubt on the reliability under loaded conditions of the single-radius concept, but the close proximity of the flexion axes of each replaced knee in relation to the functional flexion axis of the native knee may be the true basis of this purported improved kinematic performance.

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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.

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