Boorman R S, Shrive N G, Frank C B
McCaig Centre for Joint Injury and Arthritis Research, Department of Surgery, University of Calgary, Alberta, Canada.
J Orthop Res. 1998 Nov;16(6):682-9. doi: 10.1002/jor.1100160609.
Rehabilitation after soft-tissue autograft reconstructions is controversial because there is indirect evidence that some grafts fail by creeping over time. The vulnerability of soft-tissue grafts to creep over healing time and the effects of the load environment during healing on this vulnerability have never been studied specifically. We hypothesized that immobilization would decrease the magnitude of the vulnerability of ligament grafts to creep. Thirty-nine skeletally mature New Zealand White rabbits underwent a standardized medial collateral ligament autograft procedure to the right hindlimb, and 19 of the rabbits also had the limb rigidly pinned into flexion. Subgroups were killed at 3 or 8 weeks, and all isolated tibia/medial collateral ligament/femur complexes were tested for creep at 4.1 MPa under a standardized protocol. Eight normal medial collateral ligament controls were tested similarly. Results showed that all grafts were quantitatively more susceptible to cyclic and static creep than were normal medial collateral ligament controls (p < 0.05). By 3 weeks of healing, immobilization significantly increased the magnitude of the vulnerability of the grafts to cyclic, static, and total creep (all: p < 0.05). Furthermore, the grafts had more unrecovered creep strain than did the controls following a 20-minute recovery period. Contrary to our hypothesis, immobilization resulted in increased vulnerability of these ligament autografts to creep even with this relatively nonprovocative test of short duration and low stress. We postulate that following immobilization, this increase in the magnitude of susceptibility of the grafts to creep will result in functionally significant elongation of the graft if it is exposed to higher loads and over longer periods of time in vivo.
软组织自体移植重建后的康复存在争议，因为有间接证据表明一些移植物会随着时间推移逐渐失效。软组织移植物在愈合过程中对逐渐伸展的易损性，以及愈合过程中负荷环境对这种易损性的影响从未得到专门研究。我们假设固定会降低韧带移植物对逐渐伸展的易损程度。39只骨骼成熟的新西兰白兔接受了标准化的右后肢内侧副韧带自体移植手术，其中19只兔子的后肢还被刚性固定在屈曲位。在3周或8周时处死亚组动物，所有分离出的胫骨/内侧副韧带/股骨复合体按照标准化方案在4.1兆帕压力下进行逐渐伸展测试。对8个正常内侧副韧带对照组进行类似测试。结果显示，与正常内侧副韧带对照组相比，所有移植物在定量上对周期性和静态逐渐伸展更敏感（p < 0.05）。到愈合3周时，固定显著增加了移植物对周期性、静态和总逐渐伸展的易损程度（所有情况：p < 0.05）。此外，在20分钟恢复期后，移植物的未恢复逐渐伸展应变比对照组更多。与我们的假设相反，即使在这种持续时间短且应力低的相对温和测试中，固定也导致这些韧带自体移植物对逐渐伸展的易损性增加。我们推测，固定后，如果移植物在体内暴露于更高负荷和更长时间，其对逐渐伸展的易损程度增加将导致移植物在功能上显著伸长。
