使用三維運動學分析犬膝關節囊外等距點之研究

Abstract

前十字韌帶疾病是造成犬後肢跛行最常見的疾病之一，目前雖發展出許多治療方式，然而目前在臨床上對於何種治療方式較佳尚無定論。囊外固定術因為其術式簡單、成本便宜、侵入性低，且手術預後良好，目前仍是獸醫領域中最為廣泛選擇的手術治療方式。囊外固定提供支撐的線材必須在關節受力時保持一定張力，當線材張力過小將無法提供穩定膝關節的功能；相反地，當線材承受過大張力則會導致提早斷裂，並且限制關節運動範圍。因此，需要在股骨與脛骨上找到在膝關節活動範圍中相對距離不會改變的兩點，稱之為等距點(Isometric point)。過去十年間也有不少相關研究，但礙於研究方法差異，受限於二維研究、體外試驗，在這幾篇研究中對於等距點之選擇都各自推翻或歸納出不同的結論。基於過去研究的限制性，本研究旨在整合透視攝影和以電腦斷層骨模型為基礎的影像追蹤與定位技術，重建犬後肢在三維空間之膝關節運動學，並計算出骨模型上兩點之最短距離。研究最終共納入十隻健康台灣犬，結果顯示FD1-TA3, FD1-TA4, FD1-TA5, FD1-TA7, FE1-TA5, FE1-TA6, FE1-TA7, 與FE1-TB6於犬隻行走期間在三維空間中測量之最大距離長度百分比變化量小於6%。不論是以FD1或FE1為股骨固定位置，其越往前側接近脛骨脊近端等距性越佳，若以TA7為脛骨固定位置，其股骨固定位置以種子骨正下方之等距性最佳，越遠離種子骨其等距性越差。除此之外，本研究亦提供了在步態週期間兩點距離之波形變化，在FD1之所有分析組合中，在步態週期之擺盪期(Swing phase)，其兩點距離會最大，此時膝關節角度最小，約為100至110°；然而，在FE1之所有分析組合中，在此階段兩點距離則會最小，可能會因為線材張力下降，導致患犬出現膝關節的不穩定。 本研究亦分析比較了過去文獻的潛在等距組合，其中，腸趾伸肌溝前後皆非適合之等距點，而脛骨粗隆近端則可以作為近端脛骨脊之外的第二替代等距點。臨床上仍須考量到囊外固定其預防脛骨前移與內轉之功能性。若將兩點連線之張力分成垂直分量和水平分量來看，FD1-TA3, FD1-TA4, 與TA5因為其兩點連線過於平行脛骨長軸，預期此組合預防脛骨前移或內轉之能力亦可能較差，可能不是臨床上較佳之囊外固定位置。 總結來說， FD1-TA7, FE1-TA6, FE1-TA7, 與FE1-TB6皆為較佳之潛在囊外等距組合。從解剖位置來看，以種子骨正下方與後側之外側髁作為股骨等距點，近端脛骨脊為較佳之脛骨等距點；但當選擇較後側的股骨等距點，會使擺盪期時兩點距離縮短，線材張力下降，可能導致患犬出現膝關節的不穩定。本研究之結論可在臨床上提供囊外固定較佳之等距組合，以維持患犬膝關節纖維化穩定前之線材張力，在不限制關節活動的前提下，穩定膝關節，並減少術後發生線材提早延長、斷裂的併發症。

Cranial cruciate ligament deficiency (CCLD) was one of the most common causes of hind limb lameness in canine. Many treatments have been developed, but the most recommended treatment still remained controversial. Extracapsular stabilization was a widely used treatment for CCLD in canine because of its advantages including simple procedure, low cost, low invasiveness, and good prognosis. Appropriate suture points on the femur and tibia that can keep the suture under stable tension were crucial to optimize the post-operative performance of the stifle joint. Quasi-isometric suture sites on the stifle joint have been investigated with 2-D measurements or cadaveric studies, but the optimal suture point locations still remain controversial. Therefore, the study aimed to assess the isometric points of extracapsular stabilization in canine stifle joint based on the reconstructed 3-D stifle kinematics. Therefore, the purpose of the study was to assess the isometric points of extracapsular stabilization in canine stifle joint based on the reconstructed 3-D kinematics of the stifle joint. The stifle kinematics during the treadmill gait was determined using a real-time fluoroscopy analysis method. Wrapping distance variations of the candidate suture sites on the bone models were calculated. Ten healthy dogs were enrolled in the study. The results showed the suture pairs FD1-TA3, FD1-TA4, FD1-TA5, FD1-TA7, FE1-TA5, FE1-TA6, FE1-TA7, and FE1-TB6 presented the max length percentage changes less than 6% over entire gait cycle. However, the connection pairs of FD1-TA3, FD1-TA4 and FD1-TA5 are considered too vertical to provide sufficient parallel tension force to resist cranial tibial thrust and tibial internal rotation. For the femoral attachments on the FD1 and FE1, the connection sites on those points more cranial to proximal tibial crest, the better the isometry. On the other hand, with the TA7 as tibial attachment, the best isometric femoral attachment was just caudal and below the fabella. The farther away from the fabella, the worse the isometry. Waveforms of the two-points distance during the gait cycle were also presented in this study. Among all the suture combinations of FD1, the distances of pairs would be largest in the swing phase of the gait cycle with stifle angle within 100 to 110°; however, among all the suture combination of FE1, the distances of pairs would be smallest during the same motion period, which may cause stifle instability. Potential quasi-isometric points determined in the literature were also analyzed in our study, in which the long digital extensor groove was shown to be not isometric, while the tibial tuberosity could be the second alternative to the proximal tibial crest. In summary, suture pairs FD1-TA7, FE1-TA6, FE1-TA7, and FE1-TB6 could yield the most isometric outcome comparing to other combinations, which may be suggested as an appropriate suture points in clinical practice. The femoral attachment of FD1 or FE1 is a location just distal or caudodistal to the fabella, while the tibial attachment of TA6, TA7, or TB6 is near the proximal tibial crest.