Effects Of Different Degrees Of Syndesmosis Ligament Injury On Ankle Stability

The anterior inferior tibiofibular ligament, posterior ligament, transverse ligament, interosseous ligaments syndesmosis ligament, and the ankle joint, lateral structure common in maintaining the stability of the ankle mortise. In recent years, with the popularity of the sport, the ankle joint injury is increasing, while the distal tibiofibular syndesmosis injury patients accounted for a considerable proportion. Distal tibiofibular syndesmosis injury if not timely diagnosis and treatment effective, will lead to the occurrence of post traumatic arthritis.The ankle joint injury, the maintenance and restoration of distal tibiofibular joint stability is very important. But for which patients, what degree of ligament injury required syndesmotic fixation operation is the focus of debate at present. Ankle syndesmosis is a micro connecting joints, can appear before and after rotation, and the up and down movement. The three point fixation of anterior inferior tibiofibular ligament, interosseous ligaments after and three correct position on the fibula in the fibular notch in the crucial.Foreign scholars:as long as the tibia and fibula interosseous membrane remained intact syndesmosis cannot completely fracture, distal tibiofibular syndesmosis separation will not occur; fibular fracture, can achieve anatomical reduction and rigid fixation under, can not be syndesmosis fixation; even tibiofibular combined with the separation, but if in the triangular ligament intact circumstances, the stability of ankle joint does not change obviously. And that is in the range of ankle joint above the level of 3～4.5 cm 1 transition region, if the deltoid ligament intact, fracture fixation of the medial malleolus, also not be fixed the anterior inferior tibiofibular ligament, this is the "Boden theory". Domestic scholars have put forward the "three column" theory of ankle joint, external, respectively, in the medial column structure, the lateral malleolus, medial malleolus syndesmosis structure,2 column stability can not syndesmosis fixation. Only when the three are in two or more of irreversible injury, ankle joint stability will change.Under what circumstances fixed injury of anterior inferior tibiofibular ligament, how do you fix these problems of the controversial, most domestic hospitals also follow previous Boden theory, but at present from clinically diagnosed, treatment and follow-up results, this theory is flawed. Some researchers pointed out:stop the fibula moves outside 90% resistance from syndesmotic ligaments under article three, so any one or both damage will affect the syndesmosis normal joint fretting and stability of. The anterior inferior tibiofibular ligament with tibia, fibula in the syndesmosis cross section consists of a concentric circle structure and keep a certain tension, arbitrary partial damage can lead to damage of annular chains, and affects stability syndesmosis.Without ligament injury repair operation, the spontaneous healing of the ligament relaxation, lead to growth, and finally cause ankle pain, instability, arthritis. If the stability of distal tibiofibular syndesmosis has not been effectively restored, even if the inner and outer ankle fractures have been properly fixed, still can cause ankle pain, instability, traumatic arthritis and other severe adverse consequences, therefore, the syndesmosis stability judgment is very important. Most scholars believe that as long as the existence of the syndesmosis separation should be through surgical intervention, good accurate reduction of can be achieved better clinical effect. Stark found that fixed ankle supination external rotation type IV degree after ankle fracture, there are still 39% of the patients with inferior tibiofibular joint instability. Teramoto A through the analysis of the ankle for three-dimensional mechanics, proposed cutting tibiofibular ligament can result in more than one direction of ankle joint instability, which the ankle external rotation and varus instability when the most obvious. There is still controversy on the diagnostic criteria of the anterior inferior tibiofibular ligament injury instability.Such as:the present syndesmosis widened more than 1.5mm should be the syndesmosis fixation; distal tibiofibular syndesmosis separation> 2mm activity is not stable; ankle fracture fixation, external rotation should be measured by X ray contrast force health, suffering from the same difference gap side of ankle joint the level of tibia and fibula, greater than 1 mm for the diagnosis of distal tibiofibular syndesmosis unstable.Effect of Luo Biao such that the patient’s age, gender, height, body mass of the syndesmosis various evaluation parameter is very small, almost can not consider. The general population can meet the daily motion of the ankle joint direction include: neutral, dorsiflexion (15 degrees), plantar flexion (20 degrees) bit. But also often appear:special groups such as the athlete (15 degrees), varus valgus (10 degrees), internal rotation (10 degrees), external rotation (5 degrees).The purpose of this study: plans from the experimental point of biomechanics, in different positions, cadaveric specimens (neutral, dorsiflexion, plantar flexion, varus, valgus position, internal rotating, extorsion) simulation of the anterior inferior tibiofibular ligament injury of different degree, on the anterior inferior tibiofibular ligament separation distance, contact area (especially the tibiotalar joint), biomechanical measurement of change in average contact pressure and peak pressure. Meaning:the influence on the stability of the ankle of the tibiofibular ligament is inferred under the injury, to provide the experimental basis for the treatment of anterior inferior tibiofibular ligament injury in different population. The accuracy of the detection of ankle joint "three column" theory, according to the severity of tibiofibular syndesmosis injury separation distance deduce that.Materials and methods:select no injury and deformity of Chinese adults, the embalming formalin soaked within 1 months of the lower limbs 10 (male 7, female 3; 6 left,4 right out by Department of anatomy; Southern Medical University).10 specimens from 30 cm from the broken ankle, leg and ankle and foot retention. Remove the skin, muscle and soft tissue, retention of tibia and fibula interosseous membrane, deltoid ligament of ankle joint, lateral collateral ligament and the inferior tibiofibular ligament and joint capsule. With polymethyl methacrylate resin embedding specimens of tibial tubercle end. The digital electronic pressure sensor (K-Scan5033, Tekscan, Inc., USA) implantation in ankle joint. Stop point positioning needle is sheathed on displacement sensor in the anterior inferior tibiofibular ligament, connected to the static resistance strain demonstration instrument to record the tibiofibular joint separation shift.The specimen is placed in the BOSE Eletroc Force from 3510 material testing machine (high precision biological material experiment system; Chinese Shanghai, force value:+/-7.5KN;+/-25mm; dynamic strain: frequency:100HZ). The horizontal plate specimen placed in foot, plantar contact surface simulation adults daily life or movement of the. Specific steps:1, the inferior tibiofibular ligament intact (group A) state, loading 500N, respectively in different postures:neutral, dorsiflexion (15 degrees), plantar flexion (20 degrees), varus (15 degrees), valgus (20 degrees), internal rotation (10 degrees), external rotation (5 degrees) position, measuring changes in all the samples from the distal tibiofibular syndesmosis separation distance, tibiotalar joint contact area, mean contact pressure and peak pressure. Step 2:all were cut off before the syndesmosis ligament (group B), 7 positions measurement of pressure. Step 3:in step 2 basis,5 randomly selected specimens and ligament transection (group C1), another 5 specimens were cut off the interosseous ligament (group C2),500N pressure were measured, position under the data. Step 4:all specimens were cut off the anterior inferior tibiofibular ligament+ interosseous ligament+ligament (group D), and cut off the interosseous membrane (more than 5cm),500N pressure were measured, position under the data.Before the experiment were first given to pre load, as far as possible to eliminate material error caused by ligament creep. With the speed of 50N/S samples on the additional axial load to 500N, for 30 seconds, in order to fully recorded in the loading process of tibiotalar joint contact area, mean contact pressure and peak pressure experimental data. Samples in each experiment state record loading measurement 3 times, with average values of 3 experimental data as the final results of different position, different patterns of each ligament injury of the. Through the pressure data of I a ScanSoftware record dynamic or static measurement, comparative analysis. Previous studies showed that normal adult, ankle joint activities,5-7 times the ankle by pressure can reach the highest weight, this experiment we used the 500N loading capacity, in order to avoid excessive pressure loading repeated causing irreversible damage to the specimen, and the pressure range according to the adult normal stand lower extremity feet bear and set. The use of SPSS13.0 statistical data, by using analysis of variance for repeated measurement design analysis, multiple comparison using the method of SNK, P<0.05 are considered to have significant difference.Results:the experiment with 10 specimens of normal, intact condition, group A data in the syndesmosis separation distance, no statistical significance from the tibial articular contact area, mean contact pressure and peak pressure difference (P> 0.05). The only injury of anterior inferior tibiofibular ligament (group B), ankle joint stability is good, the various anthropometric data had no obvious change, no statistical significance (P> 0.05). With the injury, the separation distance tibiofibular ligament increases, the contact area gradually narrow, average pressure increases, the peak pressure increases. Each group of data between the same change trend. The anterior inferior tibiofibular ligament 2 ligaments and more than 2 damage (group C1, group C2, group D), in a neutral position, dorsiflexion, plantar flexion, varus position, internal rotation, can still maintain the stability of the ankle joint, no statistically significant difference between each data (P> 0.05). But in external rotation and varus stress, ankle instability, separation distance, the distance of tibial inferior tibiofibular joint contact area, contact pressure and peak pressure average of statistically significant differences (P<0.05). In external rotation and varus stress, the syndesmosis separation distance widened substantially larger than 2mm, were significantly better than the other 5 position.External rotation position (group C1, C2, D) tibiotalar area of contact data are as follows:405+44.73 mm2,370.95+29.10 mm2,365.37+39.11 mm2; varus position was 408.50+38.87 mm2 and 376.01+30.93 mm2, and 372.95+38.44 mm2; contact area gradually reduced, the more obvious extorsion. But there was no statistically significant difference between the two groups (P> 0.05). In external rotation and varus stress, the mean contact pressure and peak pressure increased significantly, and external rotation group C1:21573.35+1477.86 Kpa,36004.57+3597.73 Kpa; group C2:20716.48+1728.83 Kpa,35323.15+5173.21 Kpa; group D:22488.19+ 1624.46 Kpa,37393.82+4236.32 Kpa. Varus position under C1 group:21338.91+ 1535.81 Kpa,36317.08+3369.92 Kpa; C2 group of 20589.06+1781.90 Kpa, 35144.59+5280.99 Kpa; group D,22316.67+1964.47 Kpa,37361.07+4405.73 Kpa. No statistically significant difference between the two groups (P> 0.05). But compared with the other five position significantly reduced the contact area, pressure increased significantly, to infer multiple ligament injury, external rotation and varus stress position, the ankle is more likely to cause injury and complications. Next tibiofibular separation distance, average contact pressure, peak pressure, the former ligament injury group after++ interosseous ligament ligament injury group was significantly more than the previous ligament, the impact of the former on the ankle injury is more significant than the latter.Conclusion:Simple syndesmosis ligament damage in varying degrees, in the majority position, the ankle remains stable, can meet the daily needs of the general population weight. But turn the position of the outer or inner spin, even if between the tibia and fibula bones film no or mild injury, is still inferior tibiofibular joint separation occurs, syndesmosis ligament injury can significantly affect the stability of the ankle joint. Proposal for moderate and severe ligament injury while inline ankle, repair, outside a fixed structure, emphasis on restoration of the inferior tibiofibular ligament fixation, especially in demanding ankle populations, such as athletes.