Øhrn Frank-David, Lian Øystein Bjerkestrand, Tsukanaka Masako, Röhrl Stephan Maximillian
Kristiansund Hospital, Møre and Romsdal Health Trust, Kristiansund, Norway.
Department of Neuromedicine and Movement Science, NTNU Norwegian University of Science and Technology, Trondheim, Norway.
Bone Jt Open. 2021 Sep;2(9):737-744. doi: 10.1302/2633-1462.29.BJO-2021-0115.R1.
Medial pivot (MP) total knee arthroplasties (TKAs) were designed to mimic native knee kinematics with their deep medial congruent fitting of the tibia to the femur almost like a ball-on-socket, and a flat lateral part. GMK Sphere is a novel MP implant. Our primary aim was to study the migration pattern of the tibial tray of this TKA.
A total of 31 patients were recruited to this single-group radiostereometric analysis (RSA) study and received a medial pivot GMK Sphere TKA. The distributions of male patients versus female patients and right versus left knees were 21:10 and 17:14, respectively. Mean BMI was 29 kg/m (95% confidence interval (CI) 27 to 30) and mean age at surgery was 63 years (95% CI 61 to 66). Maximum total point motions (MTPMs), medial, proximal, and anterior translations and transversal, internal, and varus rotations were calculated at three, 12, and 24 months. Patient-reported outcome measure data were also retrieved.
MTPMs at three, 12, and 24 months were 1.0 mm (95% CI 0.8 to 1.2), 1.3 mm (95% CI 0.9 to 1.7), and 1.4 mm (0.8 to 2.0), respectively. The Forgotten Joint Score was 79 (95% CI 39 to 95) and Knee Injury and Osteoarthritis Outcome Score obtained at two years was 94 (95% CI 81 to 100), 86 (95% CI 75 to 93), 94 (95% CI 88 to 100), 69 (95% CI 48 to 88), and 81 (95% CI59 to 100) for Pain, Symptoms, Activities of Daily Living, Sport & Recreation, and Quality of Life, respectively.
In conclusion, we found that the mean increase in MTPM was lower than 0.2 mm between 12 and 24 months and thus apparently stable. Yet the GMK Sphere had higher migration at one and two years than anticipated. Based on current RSA data, we therefore cannot conclude on the long-term performance of the implant, pending further assessment. Cite this article: 2021;2(9):737-744.
内侧旋转（MP）全膝关节置换术（TKA）旨在模拟天然膝关节的运动学，其胫骨与股骨的内侧紧密贴合，几乎类似于球窝关节，外侧部分则较为平坦。GMK Sphere是一种新型的MP植入物。我们的主要目的是研究这种TKA胫骨托的移位模式。
本单组放射立体测量分析（RSA）研究共招募了31例患者，他们接受了内侧旋转GMK Sphere TKA。男性患者与女性患者以及右膝与左膝的分布分别为21:10和17:14。平均体重指数为29kg/m（95%置信区间（CI）27至30），手术时的平均年龄为63岁（95%CI 61至66）。在3个月、12个月和24个月时计算最大总点运动（MTPM）、内侧、近端和前方平移以及横向、内旋和内翻旋转。还检索了患者报告的结局测量数据。
3个月、12个月和24个月时的MTPM分别为1.0mm（95%CI 从0.8至1.2）、1.3mm（95%CI 从0.9至1.7）和1.4mm（0.8至2.0）。遗忘关节评分是79（95%CI 39至95），两年时获得的膝关节损伤和骨关节炎结局评分中，疼痛、症状、日常生活活动、运动与娱乐以及生活质量方面分别为94（95%CI 81至100）、86（95%CI 75至93）、94（95%CI 88至100）、69（95%CI 48至88）和81（95%CI 59至100）。
总之，我们发现12个月至24个月之间MTPM的平均增加低于0.2mm，因此显然是稳定的。然而，GMK Sphere在1年和2年时的移位高于预期。基于目前的RSA数据，因此在进一步评估之前，我们无法得出该植入物长期性能的结论。引用本文：2021；2（9）：737 - 744。
