Experimental Comparsion Between Semi-tendon Semi-muscle Graft And Total Tendon Graft For Renconstruction Of Anterior Cruciate Ligament

BackgroundInjury to anterior cruciate ligament (ACL), one of the important stablizing ligaments within the knee joint, is hard to cure. The ACL injury may lead to severe knee joint instability, secondary cartilage and meniscus injury, and osteoarthritis. And it will severely decrease the patient's work and life quality. So, more and more patients require reconstruction of anterior cruciate ligament.Nowadays, the frequently-used ligament replacements are biological materials (bone-patellar tendon-bone graft, semitendinosus and gracilis muscle, etc.) and synthetic materials (artificial ligament). According to the clinical experience and short-term follow-up, the artificial ligament has good outcome. But it needs large-number case study and long-term follow-up. Futhermore, the artificial ligament is quite expensive, which limits the clinical application to some extent.Semitendinosus and gracilis muscle is the commonly-used biological reconstruction material. But the havest of semitendinosus and gracilis muscle may cause injury to saphenous nerve and decrease in the hamstring muscle strength. So, reducing the amount of tendon harvested can reduce the damage to the host tendon area. And when the tendon is harvested, there will be partial muscle left the junction of tendon. It remains unobserved as to the muscle pertaining to the creeping substitution and intensity of the ligament.ObjectiveTo provide the fundamental study for the creeping substitution of the muscle remnant and for the harvest of the ligament graft.Methods 1. The New Zealand White rabbits were adopted in the experiment. For each rabbit, after the cut off of anterior cruciate ligaments of bilateral hind legs, the ligament was reconstructed with semitendon-semimuscle Achille's tendon (with one half of tendon and one half of muscle) for one side and with Achille's tendon for the contralateral side.2.GroupIn the experiment, there were 40 New Zealand White rabbits, who were randomized into 4 groups with 10 rabbits for each.The histological experiment:In group 1 the animals were kept untill 8 weeks after the operation.In group 2 the animals were kept untill 4 weeks after the operation.In group 3the animals were kept untill 2 weeks after the operation.The biomachanics experiment:In group 4 the animals were kept untill 8 weeks after the operation.3.After the ligament reconstruction, the animals were observed about the knee joint movement both active and passive.4.For the histological experiment,the ligament specimens were harvested at the time points. The diamters were measured at the femur junction, at the middle,and at the tibia junction. Then the ligaments were 10% EDTA decalcified, embedded, sliced, HE stained and Masson stained.5.For the biomachanics experiment, the animals were killed at 8 weeks after operation and the ligaments were harvested to carry out to get bioma-chanical measurements.6.Then the data was collected to make the statistical analysis with SPSS 12.0 and P<0.05 defined as statistical significance.Results1. Morphological observation of the graft:At 2 weeks post-operation, it can be observed of the decrease in the amount of the muscle. In the semitendon-semimuscle group, the diamter of the graft is smaller and there is more exudate and the exudate is more turbid. In the whole tendon group, there is not obvious change in the graft diameter and there is less exudate and the exudate is clearer than that of the semitendon-semimuscle group.At 4 weeks post-operation, in the semitendon-semimuscle group, the diamter of the graft is much smaller and there is less exudate and the exudate is turbid. In the whole tendon group, there is not obvious change in the graft diameter and exduate is the same as that of the semitendon-semimuscle group.At 8 weeks post-operation, the ligament of the semitendon-semimuscle group is obviously thinner and there is no muscle tissue and the exduate is quite clear and little. In the whole tendon group, there is not obvious change in the graft diameter and exduate is the same as that of the semitendon-semimuscle group.2. The diameter of the ligament post-operation:At all the time point, there is statistically significant difference in the diameter of the ligament between the semitendon-semimuscle group and the whole tendon group (P<0.05).3. The biomechanical comparision:At 8 weeks after operation, there is statistically significant difference in the biomechanical features of the ligament between the semitendon-semimuscle group and the whole tendon group(P<0.05).4. HE stain and Masson stainAt all the time points, there is difference in the histological feature between the semitendon-semimuscle group and the whole tendon group. In the semitendon-semimuscle group, the muscle gradually denatured, is obsorbed and patially transformed to dense connective tissue.Conclusion1. There is no difference in knee joint function score between SSG and TTG for reconstruction of ACL2.Inflammatory reaction in SSG group is more serious than TTG group in the ACL reconstruction3. Graft diameter of the SSG group was reduced nearly half of TTG group in ACL reconstruction.4. Maximal tensile strength of SSG was reduced nearly half of TTG group5. Improved ingrowth of new cells and tissues is found in SSG Group compared with TTG Group.6. In clinical reconstruction of ACL with tendon graft,if much more skeletal is preserved in the graft,the strongth of the graft will be decreased,however,it is benefit to creeping substitation of the graft with preservation of a little of skeletal in the graft.