Department of Orthopaedic Surgery, Kobe Kaisei Hospital, Nada, Kobe, Japan.
Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Chuo, Kobe, Japan.
J Arthroplasty. 2020 Feb;35(2):388-393. doi: 10.1016/j.arth.2019.08.055. Epub 2019 Sep 5.
Narrow femoral implants were developed to improve fit and prevent overhang in primary total knee arthroplasty (TKA). We compared intraoperative soft tissue balance between standard and narrow implants in posterior-stabilized (PS) TKA.
We enrolled 30 consecutive patients with varus osteoarthritis undergoing PS TKA using an image-free navigation system. Standard and narrow femoral trial implants were inserted, and their soft tissue balance was measured. Subgroup analysis, based on the actual implanted femoral implant, was performed to assess the influence of narrow implants on soft tissue balance.
Narrow trial group had significantly larger joint component gaps than standard trial group at all measured flexion angles, except at 60° (P < .05). For the standard implant cohort, narrow trial group had significantly larger joint component gaps than standard trial group at 30°, 120°, and 135° flexion (P < .05). For the narrow implant cohort, narrow trial group had significantly larger joint component gaps than standard trial group at all measured flexion angles, except at 0° and 60° (P < .05). Narrow trial group had significantly larger varus ligament balance than standard trial group at 45° and 60° flexion (P < .05). The varus angles for standard implants were comparable between groups; however, narrow trial group had significantly larger varus angles for narrow implants than standard trial group at 45°, 60°, and 120° flexion (P < .05).
The medial-lateral dimension and volume of the femoral component may influence intraoperative soft tissue balance in PS TKA. The effects may be greater when narrow implants are selected to avoid component overhang.
为了改善初次全膝关节置换术（TKA）中的假体匹配度并防止假体突出，开发了窄型股骨假体。我们比较了后稳定型（PS）TKA 中标准型和窄型假体的术中软组织平衡。
我们纳入了 30 例采用无图像导航系统的内侧骨关节炎行 PS TKA 的连续患者。插入标准和窄型股骨试模，并测量其软组织平衡。基于实际植入的股骨假体进行亚组分析，评估窄型假体对软组织平衡的影响。
除 60°时外（P＜.05），在所有测量的屈曲角度中，窄型试模组的关节组件间隙均明显大于标准试模组。对于标准假体组，在 30°、120°和 135°屈曲时，窄型试模组的关节组件间隙均明显大于标准试模组（P＜.05）。对于窄型假体组，在所有测量的屈曲角度中，除 0°和 60°外，窄型试模组的关节组件间隙均明显大于标准试模组（P＜.05）。在 45°和 60°屈曲时，窄型试模组的内侧副韧带平衡明显大于标准试模组（P＜.05）。标准假体组的内翻角度在组间具有可比性；然而，在 45°、60°和 120°屈曲时，窄型试模组的窄型假体的内翻角度明显大于标准试模组（P＜.05）。
股骨假体的内外径和体积可能会影响 PS TKA 中的术中软组织平衡。选择避免假体突出的窄型假体时，影响可能更大。
