Unicompartmental knee resurfacing: enlarged tibio-femoral contact area and reduced contact stress using novel patient-derived geometries.
Advances in imaging technology and computer-assisted design (CAD) have recently enabled the introduction of patient-specific knee implant designs that hold the potential to improve functional performance on the basis of patient-specific geometries, namely a patient-specific sagittal and coronal curvature, as well as enhanced bone preservation. The objective of this study was to investigate the use of a novel implant design utilizing a patient specific sagittal J-curve on the femoral component combined with a novel constant, patient-derived femoral coronal curvature and to assess tibio-femoral contact area and contact stress on a femur matched curved tibial polyethylene insert. Mean contact area and standard deviations were 81+/-5, 96+/-5 and 74+/-4 mm(2) for the heel strike, toe off and mid-stance positions, respectively. Mean contact stress and standard deviations were 23.83+/-1.39, 23.27+/-1.14 and 20.78+/-0.54 MPa for the heel strike, toe off and mid-stance positions, respectively. Standard deviations of the measurements were small, not exceeding 6-7% confirming the consistency of loading conditions across different flexion angles. The results were comparable to those reported for standard, off-the-shelf fixed-bearing implants with paired femoral and tibial geometries. These data show that a constant coronal curvature can be applied to a patient-specific implant by measuring coronal curvatures across the femoral condyle in each patient and by deriving an average curvature. This novel approach combines unique benefits of patient-specific geometry with proven design concepts for minimizing polyethylene wear.
Steklov
Nick
N
Shiley Center for Orthopedic Research and Education Center (SCORE), 11025 N. Torrey Pines Road, Suite 140, LaJolla, CA, 92037, USA.
Slamin
John
J
Srivastav
Sudesh
S
D'Lima
Darryl
D
J Arthroplasty. 2008 Apr;23(3):408-12
18358380
Orthopedics. 2007 May;30(5 Suppl):19-23
17549861
J Bone Joint Surg Am. 2005;87 Suppl 2:120-4
16326731
Clin Orthop Relat Res. 2002 Nov;(404):62-70
12439239
J Arthroplasty. 1997 Sep;12(6):599-602
9306209
Clin Orthop Relat Res. 2005 Nov;440:60-6
16239785
J Bone Joint Surg Am. 1986 Sep;68(7):1041-51
3745241
J Bone Joint Surg Am. 2003;85-A Suppl 4:111-4
14652401
Knee Surg Sports Traumatol Arthrosc. 2007 Sep;15(9):1107-11
17551711
Orthop Rev. 1988 Oct;17(10):983-8
3186287
J Bone Joint Surg Br. 1998 Sep;80(5):862-5
9768899
Knee. 2004 Oct;11(5):357-62
15351409
J Am Acad Orthop Surg. 2008 Jan;16(1):9-18
18180388
J Bone Joint Surg Br. 2003 Sep;85(7):937-42
14516022
Clin Orthop Relat Res. 1993 Jan;(286):143-8
8425335
J Arthroplasty. 2004 Jun;19(4 Suppl 1):9-16
15190542
J Bone Joint Surg Am. 1989 Jan;71(1):145-50
2643607
Knee. 2006 Oct;13(5):365-70
16797994
Knee. 2007 Mar;14(2):138-44
17188876
Acta Orthop Scand. 1996 Apr;67(2):115-21
8623562
Knee. 2004 Oct;11(5):379-84
15351413