Ali A M, Newman S D S, Hooper P A, Davies C M, Cobb J P
Imperial College London, Charing Cross Campus, London, W6 8RP, UK
Imperial College London, Charing Cross Campus, London, W6 8RP, UK.
Bone Joint Res. 2017 Aug;6(8):522-529. doi: 10.1302/2046-3758.68.BJR-2017-0067.R1.
Unicompartmental knee arthroplasty (UKA) is a demanding procedure, with tibial component subsidence or pain from high tibial strain being potential causes of revision. The optimal position in terms of load transfer has not been documented for lateral UKA. Our aim was to determine the effect of tibial component position on proximal tibial strain.
A total of 16 composite tibias were implanted with an Oxford Domed Lateral Partial Knee implant using cutting guides to define tibial slope and resection depth. Four implant positions were assessed: standard (5° posterior slope); 10° posterior slope; 5° reverse tibial slope; and 4 mm increased tibial resection. Using an electrodynamic axial-torsional materials testing machine (Instron 5565), a compressive load of 1.5 kN was applied at 60 N/s on a meniscal bearing via a matching femoral component. Tibial strain beneath the implant was measured using a calibrated Digital Image Correlation system.
A 5° increase in tibial component posterior slope resulted in a 53% increase in mean major principal strain in the posterior tibial zone adjacent to the implant (p = 0.003). The highest strains for all implant positions were recorded in the anterior cortex 2 cm to 3 cm distal to the implant. Posteriorly, strain tended to decrease with increasing distance from the implant. Lateral cortical strain showed no significant relationship with implant position.
Relatively small changes in implant position and orientation may significantly affect tibial cortical strain. Avoidance of excessive posterior tibial slope may be advisable during lateral UKA.: A. M. Ali, S. D. S. Newman, P. A. Hooper, C. M. Davies, J. P. Cobb. The effect of implant position on bone strain following lateral unicompartmental knee arthroplasty: A Biomechanical Model Using Digital Image Correlation. 2017;6:522-529. DOI: 10.1302/2046-3758.68.BJR-2017-0067.R1.
单髁膝关节置换术（UKA）是一项要求较高的手术，胫骨部件下沉或胫骨高应力引起的疼痛是翻修的潜在原因。外侧UKA在负荷转移方面的最佳位置尚无文献记载。我们的目的是确定胫骨部件位置对胫骨近端应变的影响。
使用截骨导向器确定胫骨坡度和截骨深度，将16个复合胫骨植入牛津圆顶外侧单髁膝关节假体。评估了四种假体位置：标准（5°后倾坡度）；10°后倾坡度；5°反向胫骨坡度；以及增加4mm胫骨截骨。使用电动轴向扭转材料试验机（Instron 5565），通过匹配的股骨部件以60N/s的速度在半月板承重面上施加1.5kN的压缩载荷。使用校准的数字图像相关系统测量假体下方的胫骨应变。
胫骨部件后倾坡度增加5°，导致假体相邻胫骨后侧区域的平均最大主应变增加53%（p = 0.003）。所有假体位置的最高应变记录在假体远端2cm至3cm处的前皮质。在后方，应变倾向于随着与假体距离的增加而降低。外侧皮质应变与假体位置无显著关系。
假体位置和方向的相对小变化可能会显著影响胫骨皮质应变。在外侧UKA手术中，避免胫骨后倾坡度过大可能是明智的。：A.M.阿里、S.D.S.纽曼P.A.胡珀、C.M.戴维斯、J.P.科布。外侧单髁膝关节置换术后假体位置对骨应变的影响：使用数字图像相关的生物力学模型。2017；6：522 - 529。DOI：10.1302/2046 - 3758.68.BJR - 2017 - 0067.R1。
