| BackgroundFeet are weight-bearing parts of body, it play an important rore in standing, walking and jumping, if mishandled, will give the injured serious impact on their learning, life and work. Tarsometatarsal joints assume an important rore in foot biomechanics. It is a bridge to contact the forefoot and midfoot, and also an importmant of transverse arch of foot. Stable tarsometatarsal joint charged with the responsibility of load stress from the hind foot forward forefoot, which is of great significance. Usually tarsometatarsal joint injury, also known as Lisfranc injury, was named after the French surgeon Jacques Lisfranc and described for the first time is from the plane of tarsometatarsal joint amputation for gangrene on the battlefield. Along with society’s unceasing progress, traffic accident, falling injury, sports injury is increasing, Lisfranc injury has been paid more and more attention, its containing more widespread, as purely ligamentous injuries, ligament injury with fracture or intra-articular fractures, the in a broad sense refers to a or a plurality of tarsometatarsal joint removal or damage, but far more used to describe the midfoot second tarsometatarsal joint injury. Because of the Lisfranc injury is uncommon, 0.2% of all fractures, often associated with metatarsal or tarsal bone fracture. Study reported the incidence rate is about 1/55000 person years, but apparently this figure is significantly undervalued. And due to the presence of pure Lisfranc ligament injury, X-ray is difficult to diagnosis and initial misdiagnosis and missed diagnosis rate is higher, according to statistics have more than 20% were misdiagnosed or missed diagnosis. And at present for the treatment of Lisfranc injury diversity, there is no uniform therapeutic methods, the method best there has been controversy and inappropriate treatment often leads to severe complications. Therefore, it is necessary to Lisfranc ligament anatomic and biomechanical study in detail, provide the basis for its diagnosis and treatment. First, tarsometatarsal joints were detailed anatomical study and measurement of the Lisfranc ligament complex (including the tarsometatarsal ligaments, dorsal and plantar intertarsal ligaments, plantar tarsometatarsal side ligament) long, wide, cross-sectional area, the starting and ending points, and ligament walking angle. According to the results of measurement data, select the best sites and angle of ligament reconstruction, and plantar tendon which is concomitant with Achilles tendon was selected to simulate ligament reconstruction surgery. Secondly, the ligament reconstruction model fixed on the biomechanical testing machine, the neutral position and plantar flexion weight-bearing loading, contrast ligament intact model and ligament injury model, understand the tarsometatarsal joint transverse and longitudinal stability Of ligament reconstruction model.The first part Anatomic study on the reconstruction of ligaments between the first cuneiform and second metatarsal baseObjective Morphological measurements of Lisfranc ligament complex provided anatomical basis for ligament reconstruction.Methods 8 adult cadaveric foot specimens, including 5 left foot, right foot 3. All excluded foot deformity, trauma and other diseases by visual and X-ray examination. Selected specimens were immediately with the package of the double-layer plastic cloth, placed 20 degrees of deep hypothermic freezer preservation, at this temperature, the biological characteristics of bone and ligament did not change significantly,6 hours before the experiment out at room temperature for thawing. Excluding the dorsal and plantar skin, muscle and tendon. Anatomical observation dorsal ligament, plantar ligament and the Lisfranc ligament (intertarsal ligaments). Cut the ligament connecting, medial cuneiform bone and the second metatarsal bone articular surfaces were exposed. Length is From both ends of the attachment point of the midpoint of ligament, width is measured according to the widest point. Distance from the medial cuneiform of lisfranc ligamengt attachment center to dorsal medial cuneiform and Navicular-Medial cuneiform articular surface were measured by electronic vernier caliper. Using the protractor to measure the angle of Lisfranc ligament:from the second metatarsal to the medial cuneiform bone, a 1.25mm Kirschner across the ligament attachment points to the center position in the bone, measuring the angle of Kirschner with the second metatarsal bone and distance from needle pitch of the second metatarsal to articular surface of second metatarsal-Intermediate cuneiform. According to the Lisfranc ligament angle, with 2.5mm drill from the second metatarsal to the medial cuneiform bone, and then from the dorsal medial cuneiform to meidal. Autogeous plantar tendon through the medial cuneiform bone to the second metatarsal (Lisfranc bone tunnel), by passing the dorsal surface of the bone, piercing the medial cuneiform bone, tendon suture to be fixed.Results The lengths,widths and area of dorsal ligament, Lisfranc ligament and plantar ligament were (6.74～7.46)mm. (3.02～3.83)mm and (15.48～ 27.12)mm2;(9.11～12.03)mm,(7.36～10.16)mm and(92.01～120.01)mm2;(9.88～ 12.54)mm, (5.18～6.22)mmand(36.94～64.31)mm2.The Lisfranc ligament is attached near the center of Cl (8.72～10.59)mm from C1-M1 joint,distance from dorsal surface is (13.17～15.42)mm.The Lisfanc direction of (39.22～47.06) degrees to the sagittal plane and (12.25～19.58) degrees horizontal plane. Lisfranc bone tunnel:The entry point is (0.80～1.22) mm from C2-M2 joint,out point is Lisfranc ligament origin of he first cuneiform.Conclusion ①Acording to morphological measurement, Lisfranc is the most robust among the three ligaments. The bone tunnel of reconstruction is established for the formation of Lisfranc ligament and dorsal ligament in accordance with Lisfranc ligament angle and attachment; ②It is a possible treatment method to reconstruct lisfranc ligament and dorsal ligament through lisfranc bone tunnel with autogeous plantar tendon; ③Since the position of plantar ligament is deep, the reconstruction is kind of approximate anatomical reconstruction subject to the technical limitations.The second part Biochanical study of lisfranc ligament reconstruction with autogenous tendonObjective ①Under mechanical loading, comparison of Lisfranc ligament intact model and damage model, displacement shift is more obvious in what position, to provide the basis for early diagnosis of occult Lisfranc injury; ②By means of mechanical loading, evaluate tarsometatarsal joint stability after Lisfranc ligament reconstruction with autologous plantar tendon and explore the feasibility of this reconstruction method.Method 12 adult cadaveric foot specimens, including 7 left foot, right foot 5. All excluded foot deformity, trauma and other diseases by visual and X-ray examination. Selected specimens were immediately with the package of the double-layer plastic cloth, placed 20 degrees of deep hypothermic freezer preservation, at this temperature, the biological characteristics of bone and ligament did not change significantly,6 hours before the experiment out at room temperature for thawing. Disecting the tibia and fibula 5centimeters from the tibial tubercle, and to reject the skin, muscle and other soft tissue around the broken segment. Talocalcaneal joint, calcaneocuboidal joint and articulation talonavicularis joint were fixed with 2.0mm kirschner wire. Retaining the Z-line between the tibia and the fibula, the dissected proximal aspect of the tibia and fibula were then potted in the custom jig while the foot was maintained in a neutral stance position. The specimens are labeled for later experiments and statistical analysis. All were prepared testing conditions, intact ligament model:Excluding dorsal skin, does not any process ligament and joint capsule. Disrupted ligament model:Cut ligament connection between the medial cuneiform and the second metatarsal. Simultaneously cut the second tarsometatarsal joint capsual retain the first tarsometatarsal joint capsule and the 1,2 intercuneiform ligament integrity. Hemostatic forceps is inserted into the medial cuneiform bone and the second metatarsal and bracing to ensure the lisfranc ligament is cut completely. Ligament reconstruction model:On the basis of disrupted model, harvesting autogeous plantar tendon, reducting displacement of the medial cuneiform and the second metatarsal. 1cm far from the second metatarsal and intermediate cuneiform joint surface as starting point,2.5mm drill bit from the second metatarsal direction into the medial cuneiform bone, the angle is 16°horizontal and 42°sagittal palane to the second metatarsal consistent with Lisfranc ligament walking angle, also drill from dorsal medial cuneiform to medial cuneiform. Autogeous plantar tendon through the medial cuneiform bone to the second metatarsal (Lisfranc bone tunnel), by passing the dorsal surface of the bone, piercing the medial cuneiform bone, tendon suture to be fixed with ETHIBOND. During the testing procedure, the specinmens were kept moist with saline solution. The specimens were attached to the vitodynamics macine, underneath the specimen through the skid resistant contact surface which can adjust angle, place above connected the charger. Two markers place in the medial cuneiform and the second metatarsal bottom parallel position, distance of 12mm. Under fixing on the BOSE mechanical test machine, three models were given 0-600N axial loading in the neutral position and the the plantar flexion of 30 degrees according to the speed of ION per second, every 100N load stop 1 min. Recording the medial cuneiform(Cl) and the second metatarsal(M2) base displacement and the foot transverse arch height variation. Calculating displacement change of C1-M2 and transverse arch height by converted coordinates in terms of Adobe Photoshop CS6. All results are change value which take the non loaded state marker displacement as reference date.Result ①Mean C1-M2 displacement in neutral position for each models were as follows:intac(0.81±0.11)mm, cut ligament(1.66±0.19)mm, autograft fixation(0.95±0.17)mm; the changes of height of the second metatarsal base were (3.27±0.31)mm, (5.51±0.40)mm, (5.27±0.49)mm. The changes of C1-M2 displacement in the damage model were greater than that of the intact model and the ligament reconstruction model(p<0.05), the difference was statistically significant,and the model of ligament reconstruction was slightly larger than that of normal group(p<0.05), there was statistically significant difference.About the transverse arch of foot height variation, both damage group and the reconstructed group were larger than the normal group(p<0.05), the difference was statistically significant,and the level of the reconstruction group was slightly less than that of the damage group(p>0.05), there was no statistically significant difference; ②Mean C1-M2 displacement in plantar flexion position for each models were (1.37±0.27)mm, (2.70±0.39)mm, (1.69±0.23)mm. The changes of C1-M2 displacement in the damage model were greater than that of the intact model and the ligament reconstruction model(p<0.05), the difference was statistically significant,and the model of ligament reconstruction was slightly larger than that of normal group(p<0.05), there was statistically significant difference;③In the damage group, C1-M2 displacement were (1.37±0.27)mm in the plantar flexion position larger than (1.66±0.19)mm in the neutral position(t=3.932,p=0.000), the difference was statistically significant.Conclusion ①Reconstruction of the Lisfranc ligament model with autogenous tendon can reduce the displacement of C1-M2 and stabilize Lisfranc joint to a certain extent, whicn can be considered as a method to repair this injury; ②After the rupture of Lisfranc ligament, the longitudinal displacement of C1-M2 increasd and the buffering capacity of the foot decreased. Reconstruction model (both dorsal ligament and lisfranc ligament were reconstructen) has failed to improve the buffering capacity, plantar ligament considered stable transverse arch of the foot; ③The change of the displacement of the C1-M2 under the 30 degree of the plantar flexion was more obvious than that of neutral weight bearing.lt was helpful to improve clinical diagnosis of occult lisfranc damage. |
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