| Summary: | 碩士 === 國立成功大學 === 工程科學系 === 103 === Biomechanical Analysis of Patients After Posterior Cruciate Ligament Reconstruction
Author: Chang, Kai-Hao
Advisor: Wang, Rong-Tyai
Department of Engineering Science, National Cheng Kung University
SUMMARY
Twenty-two isolated PCL injured patients and ten normal subjects were recruited in this study. Post-op group are ten patients who underwent single-bundle PCL reconstructive surgery by hamstring graft. Non-copers are twelve patients who complain about knee pain and knee instability after non-operative treatment. The extensor strength of post-op group was similar to control group, and even bigger than control group. But the flexor strength at 60∘/s of non-copers and post-op group is significant smaller than control group. Based on the result, found that the average extensor strength of post-op group recovery to a good level, but the average flexor strength is relatively weak. The reason is that the patients of post-op group underwent the PCL reconstruction by hamstrings autograft. From the comparison of the relative contributions of each joint to the support moment at loading response, it is obviously that the non-copers transferred the load from knee to ankle. In the analysis of descending stairs, due to the knee instability in non-coper group, they have to reduce the knee flexion angle by concentric contraction of quadriceps in order to make a more stable landing. From the result of jump and landing, the patients in non-coper group with deficient PCL knee had to avoid excessive ground reaction force when touching the ground.Consequently, a rehabilitation program can be designed to strengthen the Quadriceps, flexors of ankle and hip in order to help patients with PCL deficiency.
Key words: PCL, PCL reconstruction by hamstrings, kinematics, kinetics, muscle strength.
INTRODUCTION
The posterior cruciate ligament (PCL) is the strongest ligament in the knee and is approximately twice as strong as the anterior cruciate ligament. The PCL plays an integral role in knee joint stability. It is the primary restraint to posterior translocation of the proximal tibia and is a secondary restraint to varus, valgus, and external rotation forces. Current clinical treatment strategies must take into account the degree of laxity, which can be divided into three grades based on the results of a posterior drawer test. Grade I and II injuries represent partial tears of the PCL, whereas grade III tears represent complete tears and suspicion of associated injuries should be increased. Grade I and II PCL injuries with conservative treatment has been shown to have consistently good functional results, but a large percentage progress to have instability and arthritis. Surgical reconstruction is suggested for use in grade III and combined PCL injuries. The treatment of PCL injury remains controversial. It is necessary to conduct an analysis of the kinematics and kinetics of the lower limbs of these patients to gain a better understanding of the clinical performance of patients with isolated PCL injuries, to serve as reference for evaluating the clinical prognosis and establishing treatment strategies. The purpose of this study is to investigate the difference of kinematics parameters, kinetics parameters and muscle strength among three groups. And the difference of kinematics parameters, kinetics parameters and muscle strength between non-involved side and involved side were also be investigated.
METHOD
Twenty-two isolated PCL injured patients and ten normal subjects were recruited in this study. Post-op group are ten patients who underwent single-bundle PCL reconstructive surgery by hamstring graft more than a year ago. Non-copers are twelve patients who complain about knee pain and knee instability after non-operative treatment. The experiment is divided into six parts, respectively laxity examination, range of motion test, thigh circumference, strength test, proprioception test, functional motion analysis. The biodex Biodex System3 Pro (Biodex Medical System, New York,USA) was used to measure the isokinetic muscle strength and proprioception test. The Qualysis motion capture system (Qualisys, Swenden) was used to collect the biomechanical data during functional tasks. There are 6 infrared cameras with 200 Hz of capture freduency. Two force plates (Type 9286 and 9286AA, Kistler Instrument Corp., Winterthur,Switzerland) recorded the GRFs of the two feet with 1000 Hz of capture frequency.
RESULTS ＆ DISCUSSION
In comparison of average Lysholm score, non-copers were 63.75 belong to scale of poor and post-op group were 89.63 belong to scale of good. In the comparison of muscle strength, it can be seen that the extensor strength of post-op group was similar to control group, and even bigger than control group. But the flexor strength at 60∘/s of non-copers and post-op group is significant smaller than control group. Based on the result, found that the average extensor strength of post-op group recovery to a good level, but the average flexor strength is relatively weak. The reason is that the patients of post-op group underwent the PCL reconstruction by hamstrings autograft, caused flexor strength weak.
In the analysis of gait, the knee flexion angle of post-op group is significant smaller than rest of two group at initial contact, loading response and mid-stance. We inferred that the patients in post-op group had better extensor strength, and they used the concentric contraction of quadriceps to keep the knee stable. From the comparison of the relative contributions of each joint to the support moment at loading response, the knee contribution of involved side (45.9%) is smaller than non-involved side (49.37%), but the ankle contributions of involved side (24.6%) is greater than non-involved (19%). It is obviously that the non-copers transferred the load from knee to ankle at loading response.
In the analysis of descending stairs, the knee flexion angle of non-copers was significant smaller than control group at instant of toe contact. And the same situation also can be seen between non-involved and involved side, the knee flexion angle of non-involved side was significant smaller than involved side at instant of toe contact. It is because the knee instability in non-coper group, they have to reduce the knee flexion angle by concentric contraction of quadriceps in order to make a more stable landing.
In this study, the maximum knee flexion angle of non-copers is significant smaller than post-op and control group in squatting. We concluded that the lower the squatting, the moment of body weight acted on knee higher. Subjects in post-op and control group had good extensor strength so that they could be lower in squatting, but not collapsed because they could not support the body weight. From the result of jump and landing, it can be seen that the maximum ground reaction force of non-copers is significant smaller than post-op and control group. The same situation occurred between non-involved and involved side in non-copers, the maximum ground reaction force of involved side is significant smaller than non-involved side. Obviously, the patients in non-coper group with deficient PCL knee had to avoid excessive ground reaction force when touching the ground.
CONCLUSION
It can be seen that the patients after posterior cruciate ligament reconstruction could recovery to the good level. In this study, the patients after PCL reconstruction would have better extensor strength but relatively poor flexor strength, due to the patients underwent the single-bundle PCL reconstruction by hamstrings autograft. From the comparison of the relative contributions of each joint to the support moment of non-copers can be seen that the non-copers transferred the loading from knee to hip and ankle. Consequently, a rehabilitation program can be designed to strengthen the Quadriceps, flexors of ankle and hip in order to help patients with PCL deficiency.
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