Ma Yuan, Chen Wei-Jia, Nagamine Ryuji
1 Department of Orthopaedic Surgery, Kyushu University Hospital, Higashi Ku, Fukuoka City, Japan.
2 Centre of Artificial Joint and Rheumatism, Fukuoka Tokushukai Medical Centre, Kasuga, Japan.
J Orthop Surg (Hong Kong). 2017 Jan;25(1):2309499017690976. doi: 10.1177/2309499017690976.
It has been realized that for osteoarthritis (OA) knee with varus deformity, posterior cruciate ligament (PCL) release resulted in the increase of the flexion gap without significant effect on the extension gap. While the effect of release on gap angle is still obscure. On the other hand, gap distance and varus angle measured under different distraction forces suggest different patterns.
In the current study, mechanical gap balance in displacement and angular alternation of extension and flexion gaps will be evaluated, with PCL fully retained or resected under different distracting forces in varus knees.
Fifty cases with medial OA undergoing posterior-stabilized (PS) total knee arthroplasty (TKA) were included in the study. PCL of all the cases were identified intact before resection. After distal femoral and proximal tibial cuts were initially performed and anterior cruciate ligament was excised, joint gap angle and distance in full extension and at 90° flexion were obtained by means of a tensioning device with 10, 20 and 30 inch-pounds (in-lbf) of distraction force. The gap angle and distance were measured three times at each step. After the excision of PCL, the same measurement was performed.
Both the distance and the varus angles of the knee gap enlarged accordingly with the augment of distraction forces at both extension and flexion with or without PCL resection. As to the gap distance, it remained the same after PCL resection at extension; while at flexion, the gap distance significantly ( p < 0.001) enlarged - 1.2, 1.6 and 1.9 mm - under 10, 20 and 30 in-lbf, respectively, after PCL resection. As to the varus angles, it significantly ( p < .050) decreased 0.6°, 0.3° and 0.4° at extension; while at flexion, the varus angles decreased 0° (not significant), 0.6° ( p < 0.050) and 1.1° ( p < 0.001) with 10, 20 and 30 in-lbf, respectively, after PCL resection.
Our study indicated that the sacrifice of PCL will decrease the varus deformity at both extension and flexion, but with the exception under low distraction force at flexion. A proper distraction tension is of great importance in gap balancing during TKA. Sufficient attention of varus differences should be paid to the gap balance technique when choosing from different techniques, PCL-retained TKA or PCL-sacrificed TKA, as well as and an appropriate distract tension during measurement.
人们已经认识到，对于存在内翻畸形的骨关节炎（OA）膝关节，后交叉韧带（PCL）松解会导致屈膝间隙增大，而对伸膝间隙无显著影响。然而，韧带松解对间隙角度的影响仍不明确。另一方面，在不同牵张力下测量的间隙距离和内翻角度呈现出不同模式。
在本研究中，将评估在不同牵张力下，内翻膝关节中PCL完全保留或切除时，屈伸间隙在位移和角度变化方面的力学间隙平衡情况。
本研究纳入了50例行后稳定型（PS）全膝关节置换术（TKA）的内侧OA患者。所有病例在韧带切除前均确认PCL完整。在初步完成股骨远端和胫骨近端截骨并切除前交叉韧带后，通过使用具有10、20和30英寸磅（in-lbf）牵张力的张紧装置，获取膝关节在完全伸直和屈膝90°时的间隙角度和距离。每个步骤的间隙角度和距离均测量3次。在切除PCL后，进行相同的测量。
无论是否切除PCL，随着牵张力的增加，膝关节间隙的距离和内翻角度在伸直和屈膝时均相应增大。就间隙距离而言，伸直位PCL切除后保持不变；而在屈膝位，PCL切除后，在10、20和30 in-lbf牵张力下，间隙距离分别显著增大（p < 0.001）——1.2、1.6和l.9 mm。就内翻角度而言，伸直位时显著减小（p < 0.050）——0.6°、0.3°和0.4°；而在屈膝位，PCL切除后，在10、20和30 in-lbf牵张力下，内翻角度分别减小0°（无显著差异）、0.6°（p < 0.050）和1.1°（p < 0.001）。
我们的研究表明，PCL的牺牲会在伸直和屈膝时均减小内翻畸形，但屈膝时低牵张力情况除外。适当的牵张力在TKA的间隙平衡中至关重要。在从不同技术（保留PCL的TKA或牺牲PCL的TKA）中选择时，以及在测量过程中选择合适的牵张力时，应充分关注间隙平衡技术中的内翻差异。
