Femoral notching in total knee arthroplasty
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Transcript of Femoral notching in total knee arthroplasty
FEMORAL NOTCHING in TOTAL KNEE ARTHROPLASTY
By
Ihab El-Desouky (M.D.)
Kasr Alainy School of MedicinePelvis and joint Reconstruction Unit
July 2016
Femoral Notching in Total Knee Arthroplasty• Definition: Violation of the anterior cortex (+/-
medulla)of the distal femur during preparation in TKR.
• Hirsh et al (1981) by
FOUR CASES.
was 1st to associate
notching with
supracondylar
fracture in TKR.
Then ;
Femoral Notching in Total Knee Arthroplasty
Early reports: • Culp et al. (1987): 61 fractures
with 27 cases showed notching.
• Aaron et al.,(1987) five cases 42% of deep resection of trochlea.
• Ritter et al., (1988) one case (of 180 notched femur)
• Madsen et al., (1989) two cases.
• Figgie et al., (1990) eight (of 20 notched femur) • Healy et al,. (1993) two cases ( of 7 factured femora)
Femoral Notching in Total Knee ArthroplastyNon-stop:deep resection of the anterior femoral cortex causes stress-riser and fracture.
1-Clinical hypothesis : Culp et al., (1987): 3mm notching---29.2 reduction of the torsional strength.
2-Biomechanical studies: Lesh et al,. (2000) paired human cadaver femora (Rt and Lt of same specimen) -----TKR one with notching and one without: ----bending and torsion-----fracture.
---------- ----------Results.
Femoral Notching in Total Knee Arthroplasty
Non-stop: deep resection of the anterior femoral cortex causes stress-riser and fracture.
Lesh et al,. (2000) Results: Notching decreases bending strength to fracture by
18 % and torsion by 40%
Fracture configuration of fracture: notched; cortical defect and non-notched: mid-shaft
Shawen et al (2003) cadaveric femora---- 3-mm anterior cortical notch
reduced torsional load to failure by 31%. BUT added other variables ( bone mass by DEXA + distal femur cortical geometry by polar moment of inertia by CT)
3- Finite element analysis : Zalzal et al., (2006) 3-D computer aided
design: computer software –femoral model during gait ---model for TKR --
notches (shallow or deep, with sharp or smooth corners, proximity of the notch)
Femoral Notching in Total Knee ArthroplastyNon-stop: deep resection of the anterior femoral cortex causes stress-riser and fracture.
Zalzal et al (2006) : Finite Element Analysis: High stresses at
1- Deep notch (h) (more than 3mm)2-Sharp corners of the notch (r )3-Close proximity of the notch to implant(L)
Colour differentiation for more stresses with close implant
Femoral Notching in Total Knee Arthroplasty
Stop sign: before final move.
1-Epidemiology:
-Supra-condylar femoral # after TKR= 0.3- 2.5 % of all cases(400.000/year in USA, 2/3 are females, National Center for Health Statistics).
-Anterior femoral notching incidence in some recent studies:
• Ritter et al., (2005-USA) 325/ 1089 TKR= 30%
• Gujarathi et al., (2009- UK) 72/200 TKR= 41%
Femoral Notching in Total Knee Arthroplasty
Incidence of #
Notched #Incidence of #
Non-Notched #
No. of # / total
Study
0.48%250.13%732/5233Merkel and Johnson 1986
1.4%80.8%514/567Figge, 1990
%0.091%0.0912/1089Ritter, 2005
0.5%11%23/200Gujarathi, 2009
Stop sign: before final move.1-Epidemiology:
-Supra-condylar femoral # following ant. notching:
Femoral Notching in Total Knee Arthroplasty
Stop sign2-Classification system: Tayside classification 2009(Scotland );
I: violation of the outer table
II: violation of the outer and the inner tables
III: violation up to 25% of the medullary canal
(from the inner table to the center of the medullary canal);
IV: violation up to 50% of the medullary canal
-Grade II = 3 mm violation
of the cortex in other studies.
-Grades III and IV are the risky groups.
Femoral Notching in Total Knee ArthroplastyStop sign
3-Risk factors for supracondylar femoral fractures, in decreasing order (Multi-factorial)OsteopeniaRheumatoid arthritisSteroid useNeurologic disordersRevision TKRFemale genderSeventh decade of lifeDistal femoral osteolysisAnterior femoral notching +/- AND
Mismatch of the elastic modulus Rotationally constrained componentsDelayed bone remodeling due to vascular compromise at the surgical site.Hole in navigation systems
So still notching is a controversial issue for supra-condylar fracture.
Femoral Notching in Total Knee Arthroplasty
Run again:-A clear conflict between the clinical ,biomechanical and finite element analysis.
-Hoffmann et al, (2012) series of 36 # , 9 (25%) with notching:
• Length of time from initial TKA to fracture was shorter
• distance from the anterior flange ofthe femoral component to the fracture (smaller short segmentfixation) was significantly reduced. more challenging to treat.
• An avoidable factor, other factors can’t be avoided( age , gender, oseoporosis---)
-Minoda et al., (2013): Computer Assisted Study--- more notching with navigation system.
-Lee et al., (2015): a retrospective study of 148 TKA ( 70 conventional and 78 navigated) ---- notching in 4 conventional (5.7%) and 13 navigated (16.7)
Anterior femoral bowing of the distal femur observed in 61.5%
Femoral Notching in Total Knee Arthroplasty
Factors affecting the anterior femoral cut and notching:
1-Patient-related :
1- Anterior femoral bowing:
Femoral Notching in Total Knee Arthroplasty
Stop sign
Femoral Notching in Total Knee Arthroplasty
Stop sign
Femoral Notching in Total Knee Arthroplasty
• Take Home Massage:• Notching should be avoided.
• patients who sustain inadvertentnotching that they should have additional protection inthe early postoperative period, and to consider the use afemoral component with stem as a means to bypass thestress riser of the anterior cortical notch. Mostimportant, authors believe that an anterior cortical notchshould be considered as a contraindication for manipulation of the knee prosthesis in the earlypostoperative period