Fink B, Stefanou D
Department of Joint Replacement, General and Rheumatic Orthopaedics, Orthopaedic Clinic Markgröningen gGmbH, Kurt-Lindemann-Weg 10, 71706, Markgröningen, Germany.
Orthopaedic Department, University Hospital Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
Oper Orthop Traumatol. 2020 Aug;32(4):329-339. doi: 10.1007/s00064-020-00672-w. Epub 2020 Jul 10.
Implantation of an axis-guided knee prosthesis with consideration of the joint line and balanced flexion and extension gap to reduce the mechanical load on the prosthesis axis and to improve the movement of the prosthesis.
Distinct unilateral instability due to ligament insufficiency in association with knee prostheses. Primary implantation of axis-guided knee prostheses with pronounced axial malalignment (>20-25° valgus or varus malalignment) or/and severe flexion contracture > 40°. Replacement of prosthesis with nonsignificant imbalance between flexion and extension gap.
Clearly unstable flexion gap such that the extension gap cannot be adjusted appropriately. Significant femoral bone defects requiring distal femoral replacement prostheses.
Reconstruction of the tibial platform with the trial prosthesis with regard to height in relation to the tip of the fibula. Determination of the femoral prosthesis size. Adjustment of the anteroposterior (AP) cutting block of the selected size, referenced anteriorly and in correct rotation. Determination of the flexion gap with spacers using the stable side of the collateral ligaments. Positioning the distal cutting block and determination of the height of the extension gap. Moving the distal cutting block until the same height of spacer as used in the flexion gap fits into the extension gap, taking into account the stable side of the collateral ligaments. The extent of the displacement D1 is noted. Reverse displacement of the distal cutting block by the distance D2 until a satisfactory bony contact surface for the femoral component in the distal femur can be created. The thickness of the required distal augments on the following chamfer-cutting guide (4-in‑1 cutting block) and thus on the femoral prosthetic component is the sum of D1 + D2. The chamfer-cutting guide (4-in‑1 block) with distal augments of the calculated height (D = D1 + D2) is placed in position. Definition and preparation of the posterior contact surface with positioning of any necessary posterior augments. Completion of the femoral preparation taking into account the distal and posterior augments. Assembly of the trial prostheses with a trial inlay having the height of the spacers used. Implantation of the selected prosthesis components.
Thrombosis prophylaxis, physiotherapy under full weight-bearing and mobility exercises.
After implantation of 104 axis-guided Enduro™ knee prostheses (Aesculap AG, Tuttlingen, Germany) (73 knee prosthesis revisions and 31 primary implantations), the Knee Society Score increased from 42.8 ± 18.8 preoperatively to 84.8 ± 13.9 after 24 months. Complications comprised one deep vein thrombosis and one periprosthetic infection.
植入轴引导式膝关节假体时考虑关节线以及屈伸间隙平衡，以减轻假体轴上的机械负荷并改善假体运动。
因韧带不足导致明显单侧不稳定并伴有膝关节假体。初次植入轴引导式膝关节假体，伴有明显的轴向排列不齐（外翻或内翻排列不齐>20 - 25°）或/和严重屈曲挛缩>40°。更换屈伸间隙无明显不平衡的假体。
屈曲间隙明显不稳定，以至于无法适当调整伸直间隙。需要进行股骨远端置换假体的明显股骨骨缺损。
使用试验假体重建胫骨平台，使其相对于腓骨尖端具有合适高度。确定股骨假体尺寸。调整所选尺寸的前后（AP）切割块，向前参考并正确旋转。使用侧副韧带稳定侧的垫片确定屈曲间隙。放置远端切割块并确定伸直间隙高度。移动远端切割块，直到与屈曲间隙中使用的垫片高度相同的垫片能放入伸直间隙，同时考虑侧副韧带稳定侧。记录位移D1的大小。将远端切割块反向移动距离D2，直到能在股骨远端为股骨部件创建满意的骨接触面。后续倒角切割导向器（四合一切割块）以及股骨假体部件所需远端增强块的厚度为D1 + D2之和。放置带有计算高度（D = D1 + D2）远端增强块的倒角切割导向器（四合一切割块）。确定并准备后接触面，放置任何必要的后增强块。考虑远端和后增强块完成股骨准备。组装试验假体，使用与所使用垫片高度相同的试验嵌体。植入所选假体部件。
预防血栓形成，全负重下进行物理治疗和活动锻炼。
植入104个轴引导式Enduro™膝关节假体（德国图特林根的蛇牌股份公司）（73例膝关节假体翻修和31例初次植入）后，膝关节协会评分从术前的42.8±18.8提高到24个月后的84.8±13.9。并发症包括1例深静脉血栓形成和1例假体周围感染。
