Deng Lei, Ma Zhanzhong, Sun Jianfeng, Li Zhibin, Chen Jingfeng, Zhang Yandong, Department of Orthopedics, Xiyuan Hospital, Chinese Academy of Traditional Chinese Medicine, China
[Abstract] Objective To investigate the clinical efficacy of using absorbable nail internal fixation in the treatment of unstable ankle fractures of the inferior tibiofibular joint Methods A total of 108 ankle fractures were treated with absorbable screws from 2001 to 2007, including 36 ankle fractures with different degrees of inferior tibiofibular joint ligament injury and internal fixation with absorbable screws (TAKIRON PLLA), including inferior tibiofibular joint fixation. The results showed good fracture healing and stability of the ankle cavity with an excellent rate of 89% according to the JOA criteria (swelling, joint mobility and joint space changes). Conclusion Internal fixation with absorbable nails has the advantages of easy operation, stable fixation of the lower tibiofibular joint, good fracture repositioning and healing, and elimination of secondary surgery, and is a better method for treating partially unstable ankle fractures of the lower tibiofibular joint. Deng Lei, Department of Traumatology, Xiyuan Hospital, Chinese Academy of Traditional Chinese Medicine
Keywords: Ankle fracture, lower tibiofibular joint injury, internal fixation, absorbable screw
PLLA screws fixated in an ankle fracture with syndesmosis ruptures
Deng Lei Ma zhan zhong Sun jianfeng Li zhibin Chen jingfeng Zhang yandong
Orthopedic Department of Beijing XiYuan Hospital,China Academy of Chinese Medical Science
[Abstract
Objective To explore the clinical curative effect of using biodegradable screw(PLLA) in the treatment of the fractures of ankle joint with tibia-fibula syndesmotic ruptures .
Methods From 2001to 2007 ,108 patients with ankle joint fractures were treated by bioabsorbable screws Of 36 cases were sustained not only malleolar fractures but also tibia-fibula syndesmotic ruptures ,all these fractures and ruptures were treated with a bioabsorbable polylevolactic acid ( TAKIRON PLLA) screw.
Result All of 36 patients had a mean follow-up of 12 (range 6-32) months ,and had good rate 89% according to JOA evaluation icluding swelling ,joint motion and medial joint spaces in the ankles of these patients.
Conclusions PLLA screws worked well in syndesmosis fixation in patients with an ankle fracture the advantage of PLLA screws was easy to use ,fixating It is better choice in an ankle fracture with syndesmosis ruptures .
Key Words ankle fracture syndesmosis ruptures internal fixation PLLA
The stability of the lower tibiofibular joint is of great concern in ankle fractures, both in the AO and the Lauge-Hensen staging. Once the joint is destabilized, it is prone to the development of traumatic arthritis, which can result in ankle dysfunction. Therefore, it is important to restore the anatomical alignment of the joint, especially the stability of the lower tibiofibular joint. Surgery is mostly performed to achieve strong internal fixation by implantation of metal internal fixation, which is the current conventional means. However, the disadvantage is that it causes stress masking or osteoporosis, and the metal nail fixing the inferior tibiofibular joint is also easy to bend and break, and the metal objects need to be removed again. The use of absorbable screws as internal fixation can eliminate the above-mentioned shortcomings, while ensuring good fixation and healing of the fracture. However, absorbable nails are not suitable for fractures with high stress because of their lower strength than metal nails. The 36 cases of ankle fractures in this group belonged to partial injury ankle fractures of the lower tibiofibula, which were partially stable and less stressful, and were suitable for fixation with absorbable screws.
1. Clinical data
1.1 There were 36 cases in this group, 28 males and 8 females. The age ranged from 18 to 68 years old, with an average of 42 years old. All were fresh closed fractures, including 20 cases of fall injury and 16 cases of traffic injury. According to the Lauge-Hensen typing, there were 15 cases of posterior external rotation, 10 cases of anterior external rotation, and 11 cases of anterior external rotation, while 13 cases were A, 21 cases were B, and 2 cases were C. According to the number of fractures and the degree of joint ligament injury, there were 26 fractures of the outer ankle at the level of the inferior tibiofibular union, 8 fractures below and 2 fractures above the level of the inferior tibiofibular union, and 26 fractures of the inferior tibiofibular anterior ligament injury. There were 26 anterior tibiofibular ligament injuries, 7 posterior ligament injuries, and 3 complete injuries; 3 cases of combined internal ankle fractures, 26 cases of posterior ankle fractures, and 6 cases of internal ankle deltoid ligament injuries. The average operating days after the injury were 3 days (3 hours to 7 days).
1.2 The internal fixation material was TAKIRON Bioabsorbable PLLA, with diameters of 3.5 mm and 4.5 mm, divided into 2 types of cortical and cancellous screws.
1.3 Surgical method Combined lumbar and rigid anesthesia. Firstly, the external ankle is repositioned, the fracture line is mostly short oblique or spiral, the embedded periosteum or ligament in the fracture line is removed, and the lower tibiofibular union is pried out in order to understand whether it is anterior or posteriorly unstable, but the ligament part of the lower tibiofibular union is not sutured for repair. The hole is drilled perpendicular to the fracture line and screw fixation is selected according to the anatomic diameter of the fracture site, with 3.5 mm screws above the inferior tibiofibular joint and 4.5 mm screws below the inferior tibiofibular joint. A cortical resorbable screw was then drilled into the tibia at or 2 cm above the level of the inferior tibiofibular joint and fixed to stabilize the inferior tibiofibular joint with a tightness of 90° flexion of the talus within the ankle cavity. One or two absorbable screws are fixed in the medial and posterior ankle depending on the size of the fracture, and no fixation is done in the posterior ankle if the fracture mass involves less than 1/4 of the articular surface. For tears of the deltoid ligament of the medial ankle, the repair is done by suturing through the internal thread of the medial ankle fracture. The tail of the nail protruding into the skin was bitten off. After surgery, external fixation with the aid of a cast was performed for 4 weeks.
2 . Results All cases were followed up with a mean follow-up of 12 months (6 to 32 months). According to the JOA foot joint function assessment standard, 32 cases in this group were excellent, with normal joint activity, no pain, no deformation and stable joint; 3 cases were acceptable, with occasional pain, slight joint deformation and slight instability when running, and the range of joint activity was more than 1/2 of normal; 1 case was poor, with the range of joint activity was less than 1/2 of normal, and the joint was obviously deformed, painful when walking and needed brace protection. The surgical wounds all healed in one stage without foreign body reaction, with an excellent rate of 89%.
3. Discussion
3.1 Resorbable screws (PLLA) are increasingly used in periarticular cancellous bone or fractures at its junction because of their biomechanical strength and the advantages of good biocompatibility, non-toxic side effects, non-corrosion, no stress masking, and no need for reoperation to remove them. The authors’ department has successfully treated 189 cases of humeral greater tuberosity fractures and intercondylar fractures, radial tuberosity fractures, carpal navicular fractures, metacarpal base fractures, patella fractures, ankle fractures, talus and navicular fractures, including 108 cases of ankle fractures, using resorbable screws. After retrospective analysis, 36 cases of ankle fractures with partial instability of the lower tibiofibular were treated with absorbable screws and achieved 89% excellent function rate. In recent years, the use of absorbable screws for periarticular fractures has been reported in the domestic literature [1, 2, 3], but the use of absorbable screws for ankle fractures, especially the type of inferior tibiofibular joint instability, has been reported less frequently. A search of several retrospective analyses reported good results using lower tibiofibular union with absorbable nail fixation [4, 5]. And a new randomized comparative study by Joha-Pekka and Thordarson et al [6, 7] further showed that the use of absorbable nail fixation for post-injury instability of the lower tibiofibular is better than metal nails. It was found that due to the lower mechanical strength of the inferior tibiofibular union, good stability could be achieved with absorbable nail fixation. The authors’ experience is that after fixation of the inferior tibiofibular joint with absorbable nails, it can be checked for firmness by clamping or prying and rotation tests, and plaster fixation is applied for 4 weeks after surgery.
3.2 Selection of surgical indications. The types of unstable ankle fractures of the lower tibiofibular union included in this group are mainly post-rotation external rotation, pre-rotation adduction type and pre-rotation external rotation type, which are equivalent to A, B and some C fractures in AO staging. These fractures are characterized by varying degrees of injury to the anterior or posterior inferior tibiofibular ligaments, leading to instability and outward displacement of the talus. These types of injuries can be surgically fixed with absorbable screws and achieve biomechanical stability. The authors found during surgery that strong fixation could be achieved with the selection of compatible absorbable screws for all ankle fractures except comminuted fractures. The present group of cases demonstrates that stabilization of the external ankle and inferior tibiofibular union can be achieved with absorbable screws. The initial bending strength, shear strength, and modulus of elasticity of the resorbable screw (PLLA) exceed those of cortical bone, so the fixation strength is reliable, and after 6 to 12 weeks the mechanical strength gradually decreases as the fracture begins to heal and begins to resorb, a process consistent with bone biology. However, Bostman [8], after analyzing a large number of cases, found that the resorbable nail fixation material showed adverse reactions after application, mainly including local foreign body reactions, synovitis and articular cartilage degeneration. David [9] also reported on osteolysis around implants after fixation with absorbable nails and considered it important to reduce thermal injury and prevent nailing into the joint. The authors of this paper noted that drilling should be flushed to cool down and tapping taps should be matched and not over tightened.
Juha-Pekka also found a foreign body reaction and suggested that this reaction process is slow and incomplete and may be related to the excessive length of the resorbable nail, suggesting the selection of a moderately long resorbable nail while avoiding exposure of the nail into the joint or under the skin.
3.3 Fixation of external ankle fractures and inferior tibiofibular instability The most convincing study by Ramsey showed that a 1 mm outward displacement of the talus would result in a 42% reduction in tibiofibular joint surface contact, ultimately leading to traumatic arthritis. Therefore, stabilization of the lower tibiofibular and lateral ankle has been recognized as a critical area. Stabilization of the lower tibiofibular joint is the key to treatment and requires simultaneous fixation of the external ankle fracture and the lower tibiofibular joint. The application of absorbable screws (PLLA) for the treatment of ankle fractures, including those of the internal, external and posterior ankle, has been recognized, but for those with unstable lower tibiofibular union, metal screws used to be used for fixation, while the possibility of fixation with absorbable screws has been less reported. The main reason is that the screws are point-to-point fixation and it is difficult to maintain the stability of fixation especially at the outer ankle without plate protection. Therefore, plate and screw fixation is mostly used to fix the inferior tibiofibular joint at the same time. The authors analyzed the injury characteristics of the lower tibiofibular joint and found that the type of injury correlated with the degree of injury. By observation during surgery, partial ligament injuries can be repaired without repair sutures if only the lower tibiofibular rotation is unstable and laterally stable, that is, if there is a single injury to the anterior or posterior lateral ligament of the lower tibiofibular, and fixed and repaired if there is a stenosis fracture. At the same time, one absorbable screw is used to fix the lower tibiofibular joint at the level of the fibula to the tibia. The advantage is that it can stabilize the inferior tibiofibular joint, reposition the torn ligament, avoid stress masking and local osteoporosis caused by the plate, and eliminate the need for secondary surgery. In the case of instability caused by complete rupture of the inferior tibiofibular joint ligament and large interosseous membrane damage, the authors fixed two cases with absorbable screws and later developed instability of the ankle cavity, which was considered to be caused by high stress and decay of screw strength, so this method of fixation is not recommended for this type of injury. At the same time, the alignment of the external ankle fracture line is mostly oblique, so one or two absorbable screws can be fixed to achieve anatomical repositioning. If the cap of the external ankle screw is protruding under the skin, it is recommended that the cap be partially removed to avoid local foreign body reaction and pain in the future.
3.4 In double or triple ankle fractures, in addition to the lower tibiofibular union and the external ankle, which are the key to fixation, the internal ankle fracture also requires anatomical repositioning to achieve stability of the entire ankle point. This is because the forces of posterior and external rotation can easily cause damage to the deltoid ligament, which in turn can displace the talus outward. If an external ankle injury is accompanied by significant swelling and pressure in the medial ankle, a stress radiograph should be taken to determine if there is damage to the deltoid ligament. The deltoid ligament should be repaired at the same time as the external ankle fracture is fixed. If it is a combined medial ankle fracture, it can be fixed with one or two absorbable cancellous bone screws. Whether a posterior ankle fracture is fixed or not depends on how much of the articular surface is involved in the fracture and whether there is a significant step. Some studies have shown that even a step as small as 2 mm within the tibial talar joint significantly increases stress and increases the incidence of ankle arthritis. We have increased the stability of the ankle cavity by fixing one to two resorbable cancellous bone screws in all posterior ankle fractures involving greater than 1/4 of the articular surface. Care should be taken to protect the saphenous vein during surgery, and all incisions should be adequately flushed before closing the wound to avoid debris residue.
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