Upload
malcolm-carpenter
View
217
Download
0
Tags:
Embed Size (px)
Citation preview
IntroductionPatient specific positioning guides (PSPGs) in TKA are based on MRI or CT data. Preoperatively, knee component positions can be visualized in 3-dimensional reconstructed images. Software allows anticipation of component position. From software planning PSPGs are manufactured and those PSPGs represent intra-operative component alignment
AimTo investigate the correlation between pre-operative planning of component positioning and the post-operative achieved alignment with PSPG technique.
PatientsFirst 42 TKA (Vanguard® Complete Knee System, Biomet) withPSPG technique (Signature™, Materialise)
Methods- CT measurement of component position according Perth protocol- Compared CT measurements with softwareplan obtained from MRI- 2 independent observers
Femoral component angle: 3 planes
Tibial component angle: 2 planesMeasurements in the axial plane were not performed: intraoperative
tibial rotation was in most cases obtained by extra-medullary guide.
Results
Intra-class correlation (ICC) between observer 1 and observer 2
Target angle: pre-operative planned alignment from Signature software.Mean, SD and Range of post-operative CT measurements
ConclusionIn our study postoperative knee component positioning is not consistent with preoperative software planning.
Correlation between pre-operative planning and post-operative position of components in TKA with PSPG
Justin AMJ van leeuwen¹, Stephan M Röhrl², Bjarne Grøgaard², Finnur Snorrason³
¹Dep. of Orthopaedic Surgery, Betanien Hospital Skien, Norway ²Dep. of Orthopaedic Surgery, Oslo University Hospital, Norway ³Dep. of Orthopaedic Surgery, Vestre Viken Drammen, Norway
25 TKAs at Telemark Hospital, Skien Period: 2009-2010
17 TKAs at Oslo University Hospital Period: 2010-2011
CT Measurements: Component Angles
ICC
Femur Coronal 0.75
Femur Sagittal 0.93
Femur Axial 0.46
Tibia Coronal 0.89
Tibia Sagittal 0.91
Component Angle Target Mean SD Range
Femur
Coronal (valgus- / varus +) 0.0 1.2 1.6 -1.7 – 4.5
Sagittal (flexion- / extension+) -2.8 -4.4 3.9 -17.3 – 2.5
Axial (Internal rot- / external rot+) 0.0 0.5 0.1 -2.9 – 4.3
Tibia
Coronal (valgus- / varus +) 0.0 0.5 2.4 -3.6 – 7.3
Sagittal (flexion- / extension+) -3.0 -3.7 2.3 -8.8 – 2.4
DiscussionMean values of post-operative measurements are close to pre-operative software planning, but we found a considerable spread. Possible explanations might be error levels in pre-operative wrong identification of landmarks from MRI and/or different identification of bony landmarks on CT and intra-operative errors. There might be a learning curve in using PSPGs. Time gap between PSPG manufacturing and intra-operative use can theoretically provide a less proper fit due to slight change of anatomy in a progressive osteoarthritis. It is uncertain whether this inconsistency is of clinical relevance. More data is necessary to prove any benefit of PSPG compared to existing procedures for TKA.
- Victor J, Van Doninck D, Labey L, Innocenti B, Parizel PM, Bellemans J: How precise can bony landmarks be determined on a CT scan of the knee? The Knee 2009, 16(5):358-365.- Chareancholvanich K, Narkbunnam R, Pornrattanamaneewong C: A prospective randomised controlled study of patient-specific cutting guides compared with conventional instrumentation in total knee replacement. The
bone & joint journal 2013, 95-B(3):354-359.- Boonen B, Schotanus MG, Kort NP: Preliminary experience with the patient-specific templating total knee arthroplasty. Acta orthopaedica 2012, 83(4):387-393.
Justin van Leeuwen E-mail: [email protected]