Pagani Nicholas, Mazzocco John, Thienpont Emmanuel, Smith Eric
New England Baptist Hospital, Boston, USA.
Tufts Medical Center, Boston, USA.
Arch Orthop Trauma Surg. 2025 Apr 24;145(1):263. doi: 10.1007/s00402-025-05873-1.
Correction of valgus knee deformity during total knee arthroplasty (TKA) can present numerous challenges. This study assessed the ability of a patient-specific knee design to allow easier intraoperative balancing of valgus knees in primary TKA.
This study utilized a database consisting of de-identified computed tomography (CT) scans, low constraint knee designs (CR or PS), tibial and femoral implant dimensions, and implanted polyethylene (PE) thickness for all patients who underwent primary TKA with a patient-specific knee design provided by Conformis Inc. (Boston, MA, US). Data were analyzed for knee design, coronal deformity, native posterior and distal femoral offset, and PE thickness.
A total of 26,227 cases were included, of which 25% had valgus deformity. In the PS group, the thinnest available PE (6 mm) was used for 64% of varus cases and 68% of valgus cases (P = 0.004). There was no difference in the distribution of thin (≤ 8 mm) and thick (> 8 mm) PE between varus or valgus knees with 0-5 degrees or > 10 degrees of deformity. Knees with varus deformity of 5-10 degrees were more likely to receive a thick PE than knees with valgus deformity of 5-10 degrees. For the CR group, the thinnest available PE (6 mm) was used in 77% of varus cases and 76% of valgus cases (P = 0.12). There was no difference in the distribution of thin and thick PE between varus or valgus knees regardless of deformity. Over 99% of CR knees received PE with thicknesses 8 mm or less, regardless of degree of preoperative varus or valgus deformity.
These results indicate that patient-specific instrumentation in TKA can facilitate valgus deformity correction without requiring increased PE thickness to achieve balancing. Patient-specific knee designs may reduce the difficulty of valgus knee correction while allowing the use of minimal thickness PEs in low constraint TKA implants.
全膝关节置换术（TKA）中纠正膝外翻畸形可能会带来诸多挑战。本研究评估了一种定制膝关节设计在初次TKA中使膝外翻更容易实现术中平衡的能力。
本研究利用了一个数据库，该数据库包含所有接受由Conformis公司（美国马萨诸塞州波士顿）提供的定制膝关节设计的初次TKA患者的去识别化计算机断层扫描（CT）图像、低约束膝关节设计（CR或PS）、胫骨和股骨植入物尺寸以及植入的聚乙烯（PE）厚度。对膝关节设计、冠状面畸形、股骨近端和远端的自然偏移以及PE厚度进行了数据分析。
共纳入26227例病例，其中25%存在外翻畸形。在PS组中，最薄的可用PE（6mm）用于64%的内翻病例和68%的外翻病例（P = 0.004）。畸形0 - 5度或>10度的内翻或外翻膝关节之间，薄（≤8mm）和厚（>8mm）PE的分布没有差异。5 - 10度内翻畸形的膝关节比5 - 10度外翻畸形的膝关节更有可能接受厚PE。对于CR组，最薄的可用PE（6mm）用于77%的内翻病例和76%的外翻病例（P = 0.12）。无论畸形程度如何，内翻或外翻膝关节之间薄PE和厚PE的分布没有差异。超过99%的CR膝关节接受的PE厚度为8mm或更小，无论术前内翻或外翻畸形程度如何。
这些结果表明，TKA中的定制器械可以促进膝外翻畸形的纠正，而无需增加PE厚度来实现平衡。定制膝关节设计可能会降低膝外翻矫正的难度，同时允许在低约束TKA植入物中使用最小厚度的PE。
