The effect of the syndesmotic screw on the extension capacity of the ankle joint

Summary To investigate whether, when inserting a syndesmotic screw, the foot position effects the range of motion in dorsal extension, 16 osteoligamentous lower-leg preparations were studied. The specimens were placed in a test frame where a constant dorsal extension force could be applied to the foot. The dorsal extension capacity was recorded with a syndesmotic screw inserted by a standardized technique in various plantar flexion positions. The dorsal extension capacity decreased by an average of 0.1° for every degree of increase in plantar flexion when the screw was being inserted. There was a correlation between a large decrease in range of motion and a limited dorsal extension capacity to start with. No correlation could be found between a large decrease in range of motion and a large difference in width between the anterior and posterior edges of the talar trochlea. The results suggest that the foot should be in maximal dorsal extension when a syndesmotic screw is inserted in order to decrease the risk of stiffness.     

Surgical treatment of syndesmotic diastasis: emphasis on effect of syndesmotic screw on ankle function

Fifty-two consecutive adult patients with syndesmotic diastasis (SD) were treated with closed anatomical reduction and stable fixation by a trans-syndesmotic cancellous screw. A short leg splint was prescribed for a six week postoperative period. Treatment outcomes of syndesmotic screw removal at various time points were studied and compared (group 1 at six weeks, group 2 at three months and group 3 at an average of nine months). Recurrence of SD, incidence of syndesmotic screw breakage and ankle function were compared among the three groups. Recurrence of SD occurred in 15.8% (3/19) of patients in group 1, 15.0% (3/20) in group 2 and 0% (0/13) in group 3 (p = 0.054). Breakage of the syndesmotic screw occurred in three patients within three months (group 2, 15.0%) and in two patients beyond three months (group 3, each at six and 12 months, 15.4%). None of the group 1 patients experienced screw breakage (p = 0.034). Forty-three patients (82.7%) were classified as having satisfactory outcomes. Ankle function did not significantly differ among the three groups (p = 0.191), with or without syndesmotic screw breakage (p = 0.343) and with or without SD recurrence (p = 0.218). In conclusion, restriction of daily activity for at least three months is required to prevent recurrence. Removal of the syndesmotic screw at six weeks may prevent its breakage but increases the risk of recurrence. Over an average follow-up of 19 months, SD recurrence does not lead to deterioration in ankle function.     

Evaluation of the syndesmotic screw in low Weber C ankle fractures

OBJECTIVE: To determine the functional and radiographic outcome of low Weber C ankle fractures and to evaluate the contribution of the syndesmotic screw in their outcome. DESIGN: Prospective evaluation of a consecutive series. SETTING: Level I trauma center. PATIENTS: Forty-five patients divided into two groups matched for age, sex, and severity of injury. Twenty-six patients were treated with open reduction, internal fixation, and a supplemental syndesmotic screw, and nineteen patients were treated without a syndesmotic screw. Minimum time to follow-up was three years. METHODS: A subjective, objective, and radiographic ankle scoring system was used. Logistical regression analysis was performed to determine whether the presence or absence of a syndesmotic screw was a predictor of a poor outcome. The likelihood ratio test was used to evaluate the significance of each variable in both univariate and multivariate analyses. RESULTS: There was no statistically significant difference between either group, either using subjective outcome criteria (p = 0.86) or in ankle range of motion (p = 0.94). Logistical regression analysis indicated that fracture dislocation could be used as a predictor of a poor outcome for either group. Inadequate reduction and advancing age were also found to be significant predictors of a poorer outcome regardless of the use of a syndesmotic screw (p = 0.003, p = 0.004). CONCLUSIONS: Judicious fixation of Weber C type injuries within five centimeters of the ankle joint, with or without a syndesmotic screw, gives similar results. Obligatory fixation of these fractures with syndesmotic screws appears to have no benefit and creates the need for an additional procedure.     

下胫腓联合损伤对踝关节稳定性影响的生物力学研究

[目的]探讨下胫腓联合损伤对踝关节稳定性的生物力学影响。[方法]采用6例新鲜尸体标本,制作踝关节旋前外旋损伤模型,逐步离断下胫腓联合各韧带、骨间膜和三角韧带。对标本进行600 N轴向加载,同时对踝关节施加扭矩为5 Nm的外旋力。测量下胫腓联合不同程度损伤情况下,下胫腓联合的相对位移和踝关节外旋扭转角度。[结果]随着下胫腓联合韧带和三角韧带的序贯性离断,下胫腓联合的远端腓骨相对内外位移、前后位移、腓骨转角以及踝关节扭转角度呈逐渐增加趋势。[结论]下胫腓联合韧带维持踝关节稳定。在旋转稳定性方面,下胫腓后韧带的作用最为突出。下胫腓联合韧带离断后,再离断三角韧带,踝关节的稳定性进一步丢失。     

Treatment of syndesmotic disruptions of the ankle with bioabsorbable screw fixation.

BACKGROUND: Bioabsorbable implants have restricted indications because of their unique biochemical properties and their inferior biomechanical properties compared with those of conventional metallic implants. The purpose of this prospective study was to assess the efficacy of screws made of polylevolactic acid (PLLA) in the treatment of syndesmotic disruptions associated with ankle fractures and fracture-dislocations. METHODS: Thirty-three consecutive patients with a syndesmotic disruption were managed with standard metallic plate-and-screw fixation of the malleolar fracture and with 4.5-mm polylevolactic acid screws, with purchase in four cortices, for fixation of the syndesmosis. Intraoperative radiographs confirmed reduction of the syndesmosis, and all of the patients were managed with a non-weight-bearing plaster splint or brace for six weeks. Clinical and radiographic assessment and functional evaluation with use of the Olerud-Molander scoring system were performed at the time of follow-up. RESULTS: Ten patients were lost to follow-up prior to the twenty-four-month evaluation, leaving twenty-three patients with an average duration of follow-up of thirty-four months (range, twenty-four to forty-three months). All of the malleolar fractures healed in an anatomical position at an average of three months, and no postoperative displacement of the syndesmosis or widening of the medial clear space was detectable on radiographs. No episodes of osteolysis or late inflammation secondary to the hydrolyzed polylactide occurred. Nineteen patients (83%) had an excellent result, and four patients (17%) had a good result. All twenty-three patients returned to their preinjury level of work and activities of daily living. No patient had malunion, nonunion, loss of reduction, or complications attributable to the biomechanical or biochemical properties of the implants. CONCLUSIONS: Polylevolactic acid screws are effective in stabilizing disruption of the syndesmosis during healing of unstable ankle fractures. In this small series, the bioabsorbable screw was well tolerated, and there was no need for a second operation to remove it.     

Untreated small posterior fragment of ankle fracture with early removal of syndesmotic screw is associated with recurrent syndesmotic instability

IntroductionThis retrospective study aimed to report outcomes of fixation of bi-malleolar or tri-malleolar fractures combined with syndesmotic injury with or without posterior malleolar fracture (PMF), and to ascertain whether syndesmotic screw removal at 6 to 8 weeks or 3 months postoperatively is more beneficial.MethodsWe retrospectively reviewed patients who received open reduction and internal fixation for bi-malleolar (without PMF) or tri-malleolar ankle fracture (with PMF) with syndesmotic injury between January 2013 and December 2017 with at least 24 months of postoperative follow-up. All patients suffered syndesmotic instabilities and were treated using a syndesmotic screw without PMF fixation. Patients with bi-malleolar fracture with syndesmotic screw removal at 6 to 8 weeks postoperatively were included in Group I, tri-malleolar fracture with syndesmotic screw removal at 6 to 8 weeks in Group II, and tri-malleolar fracture with syndesmotic screw removal at 3 months in Group III. Demographic data, clinical and radiographic outcomes were analyzed.ResultsA total of 113 patients were included (Group I, n=47; Group II, n=43; Group III, n=23). Average size of PMF was 14% in patients with tri-malleolar fractures (Groups II and III). No significant difference in ankle functional outcome among groups was observed. The recurrence rate of syndesmotic instability was 10.6% in Group I, 20.9% in Group II, and 8.7% in Group III. Although the difference in recurrence rates of syndesmotic instability among three groups was not statistically significant (P=0.264), Group II showed more interval change in tibiofibular clear space between initial postoperative radiographs and last follow-up radiographs (P=0.028) compared to the other two groups. Fracture union was achieved in all patients without screw breakage.ConclusionWe suggest that the better timing for syndesmotic screw removal is 3 months, instead of 6 to 8 weeks postoperatively, to reduce the risk of recurrence of syndesmotic instability for tri-malleolar fracture without posterior fragment fixation.Level of EvidenceLevel III- Case-control study.     

Changes in the syndesmotic reduction after syndesmotic screw fixation for ankle malleolar fractures: One-year longitudinal evaluations using computer tomography

IntroductionTo evaluate time-dependent changes in the syndesmotic reduction after syndesmotic screw fixation and one year after screw removal for ankle malleolar fractures, and to assess whether the incidence of syndesmotic malreduction changes depending on the measurement method.MethodsWe assessed twenty patients who underwent syndesmotic screw fixation for ankle fractures. The syndesmotic screws were removed after six weeks of the fracture surgery. Syndesmotic reduction was assessed within two weeks of the fracture surgery and one year after the screw removal using the axial computer tomographic images. Side-to-side differences in the anterior and posterior tibiofibular distances, anteroposterior fibular translation, and fibular rotation were measured.ResultsThe mean anterior tibiofibular distance was 0.7 mm after syndesmotic fixation. It increased to 1.9 mm at one year after screw removal (p = 0.002). After syndesmotic fixation, four ankles had malreduction of the anterior tibiofibular distance, including three ankles with widening and one with overtightening. At one year, eight ankles had malreduction, all of whom had widening. The other measurement values did not change over time (0.1 mm vs. 0.6 mm for the posterior tibiofibular distance, 0.2 mm vs. 0.3 mm for the anteroposterior fibular translation, and 0.7 ° vs. 0 ° for the fibular rotation). The incidences of malreduction were significantly different depending on the definition of malreduction, ranging from 10% to 50% after syndesmotic fixation (p = 0.01) and from 20% to 60% at one year after screw removal (p = 0.02).ConclusionsThe anterior tibiofibular distance widened after one year of syndesmotic screw removal. The incidence of malreduction varied depending on the measurement method.     

Biomechanical comparison of suture-button,bioabsorbable screw,and metal screw for ankle syndesmotic repair: A meta-analysis

BackgroundTo compare biomechanically metal screw fixation to suture-button or bioabsorbable screw fixation for ankle syndesmotic injuries.MethodsA literature search of the comparison studies in Pubmed and Google Scholar was conducted. The biomechanical outcomes of interest were syndesmotic stability in the coronal, sagittal, and axial planes as well as torque and rotation at failure.ResultsA total of 11 cadaveric studies were included. In the suture-button group, coronal displacement (MD 1.72 mm, p = 0.02) and sagittal displacement (MD 2.65 mm, p = 0.0003) were increased relative to the metal screw group. In contrast, no difference was found with axial rotation (MD 0.35 degrees, p = 0.57). Bioabsorbable screws exhibited equivalent failure torque (MD ?3.04 Nm, p = 0.53) and rotation at failure (MD 3.77 degrees, p = 0.48) in comparison to metal screws.ConclusionsSuture-button provide less rigidity when compared to metal screw fixation. They afford flexible syndesmotic micromotion which may more closely resemble a physiological state and be helpful for ligament healing. Bioabsorbable screws demonstrate similar mechanical strength properties to metal screws.     

Overtightening of the syndesmosis revisited and the effect of syndesmotic malreduction on ankle dorsiflexion

BackgroundAnkle syndesmotic injuries are a significant source of morbidity and require anatomic reduction to optimize outcomes. Although a previous study concluded that maximal dorsiflexion during syndesmotic fixation was not required, methodologic weaknesses existed and several studies have demonstrated improved ankle dorsiflexion after removal of syndesmotic screws.The purposes of the current investigation are: (1) To assess the effect of compressive syndesmotic screw fixation on ankle dorsiflexion utilizing a controlled load and instrumentation allowing for precise measurement of motion. (2) To assess the effect of anterior & posterior syndesmotic malreduction after compressive syndesmotic screw fixation on ankle dorsiflexion.Material and methodsFifteen lower limb cadaveric leg specimens were utilized for the study. Ankle dorsiflexion was measured utilizing a precise micro-sensor system after application of a consistent load in the (1) intact state, (2) after compression fixation with a syndesmotic screw and (3) after anterior & (4) posterior malreduction of the syndesmosis.ResultsFollowing screw compression of the nondisplaced syndesmosis, dorsiflexion ROM was 99.7 ± 0.87% (mean ± standard error) of baseline ankle ROM. Anterior and posterior malreduction of the syndesmosis resulted in dorsiflexion ROM that was 99.1 ± 1.75% and 98.6 ± 1.56% of baseline ankle ROM, respectively. One-way ANOVA was performed showing no statistical significance between groups (p-value = 0.88).Two-way ANOVA comparing the groups with respect to both the reduction condition (intact, anatomic reduction, anterior displacement, posterior displacement) and the displacement order (anterior first, posterior first) did not demonstrate a statistically significant effect (p-value = 0.99).ConclusionMaximal dorsiflexion of the ankle is not required prior to syndesmotic fixation as no loss of motion was seen with compressive fixation in our cadaver model. Anterior or posterior syndesmotic malreduction following syndesmotic screw fixation had no effect on ankle dorsiflexion. Poor patient outcomes after syndesmotic malreduction may be due to other factors and not loss of dorsiflexion motion.Level of Evidence: IV     

Radiological assessment of ankle syndesmotic reduction

IntroductionThe intraoperative assessment of adequacy of syndesmotic reduction is challenging. The aim of this study was to develop a radiographic measure based on the lateral ankle view to assess both the normal and abnormal relationship between the tibia and fibula after simulated syndesmotic malreduction and to evaluate the effect on commonly used mortise measurements.MethodsMortise and talar dome lateral radiographs were obtained in eight fresh-frozen cadaveric specimens before and following syndesmosis division and posterior fibular displacement of 2 mm increments. Using the technique described, on the lateral radiograph the anterior fibular line ratio (AFL ratio) and posterior fibular line distance (PFL distance) were measured. Both measures were based on the anterior and posterior distal tibia articular margins and flat borders of the fibula.ResultsInter- and intraobserver reliability of the AFL ratio and PFL distance measured almost perfect agreement. In all uninjured specimens the AFL lay just anterior to the midpoint of the tibia and the PFL intersected the posterior tibia articular margin or lay just anterior to it, not posterior. At 2, 4 and 6 mm of posterior fibular displacement the decrease in AFL ratio and PFL distance showed significant differences between all pairwise comparisons.ConclusionThe proposed new measures of syndesmotic reduction are reproducible and capable of detecting from 2 mm of sagittal fibula displacement and can be useful adjuncts in the assessment of syndesmotic reduction.     

Clinical diagnosis of syndesmotic ankle instability

We studied the feasibility of clinical tests in the diagnosis of syndesmotic injury of the ankle. 9 investigators examined 12 persons twice, including 2 patients with an arthroscopically-confirmed syndesmotic injury. They sat behind a curtain that exposed only the lower legs. We found a statistically significant relation between the final arthroscopic diagnosis and the squeeze, fibula translation, Cotton, and external rotation tests as well as for limited dorsal flexion. None of the syndesmotic tests was uniformly positive in chronic syndesmotic injury. The external rotation test had the fewest false-positive results, the fibula translation test the most. The external rotation test had the smallest inter-observer variance. The physical diagnosis was missed in one fifth of all examinations. When in accordance with medical history and physical examination, positive stress tests should raise a high index of suspicion of syndesmotic instability. The final diagnosis of such instability, however, should be made by additional diagnostic imaging and/or arthroscopy.     

The effect of rotationplasty on the ankle joint: long-term results

In patients with rotationplasty the biomechanical conditions in the ankle joint are altered dramatically. By displacement and reduction of the weight-bearing area of the joint, the stress affecting its cartilage is increased. The use of an exoprothesis results in skin and soft tissue irritation. Due to these biomechanical changes, a prearthrotic deformity or skin problems could be expected. The current study examines changes in 21 patients treated with rotationplasty (mean follow-up 13.5 years) because of a malignant bone tumour or a femoral segmental defect. Local tenderness, skin and soft tissue changes, problems with exoprostheses, and pain was assessed by clinical examination and documented. Osseous changes were evaluated by plain X-ray. A MRI-scan was also obtained in five patients. Hardened skin and blisters were located at the main loading areas of the rotated foot. These changes could be reduced by optimizing the exoprosthetic fit. Radiographically, a slight asymptomatic attenuation of the articular space was observed in four patients and a slight coexistent subchondral sclerosis with small osteophytes in one patient. No degenerative changes were observed on X-ray and no cartilaginous changes were observed on MRI. The results suggest that the foot is able to adapt to the load changes after this procedure and that rotationplasty does not cause an inevitable arthrosis in the ankle joint.     

Movement at the ankle joint after driving a screw across the inferior tibiofibular joint

Twenty-eight patients with fracture-subluxation of the ankle were studied for at least 1 year after fixation with an oblique fibulotibial screw, supplemented when necessary by a screw in the medial malleolus and loops of wire around the fibula. The range of movement at each ankle was measured at 6 weeks and 1 year after operation. The patient's comments on mobility and symptoms were also noted.

Irrespective of the radiological severity of the injury, 6 of the 28 had full movement at 6 weeks, and 13 at 1 year, and a further 9 had movement reduced by less than 5 mm, at 1 year, at which time 22 were free from symptoms.     

Diagnostics in suspicion of ankle syndesmotic injury

Ankle sprains are among of the most common injuries seen in daily orthopaedic practice. Beside injuries of the lateral ligament, which is the most frequently injured single structure in the body of athletes, sprains can also affect the tibiofibular syndesmosis. These injuries are known as high ankle sprains. They can occur with or without a bony injury. In this report, we will discuss the high ankle sprain without any bony injury. These kinds of injuries are rare, but often associated with complications and are frequently misdiagnosed or undiagnosed. The purpose of this article is to provide a clear understanding of clinical tests described in the literature for testing of syndesmotic integrity.     

The role of the tibiofibular syndesmotic and the deltoid ligaments in stabilizing Weber B type ankle joint fractures--an experimental investigation

The purpose of the present biomechanical investigation was to check the functional importance of the syndesmosis ligaments and of the deltoid ligament for ankle fracture type B according to the AO-Weber classification. We constructed a special fixation clamp, with 12 fresh and unembalmed lower legs being tested for lateral shift (mm) and ten for tibiotalar rotation. All specimens were exposed in the same neutral position.Transverse loads (F(y)) varied between 0 and 150 N, axial loads (F(z)) between 0, 300, 600 and 1,000 N and rotational loads (F(r)) between 2.4 and 4.9 Nm. All series were repeated according to supination-eversion (SE) injury patterns of the Lauge-Hansen classification. Syndesmotic ligaments and the fibula were incrementally sectioned from anterior to posterior. Type SE I consisted of an isolated incision of the anterior syndesmosis ligament. Type SE II had an additional oblique fracture of the fibula at the height of the tibiofibular syndesmosis. In type SE III injuries, in addition to the fibular fracture, a complete rupture of the syndesmosis ligaments was present, and for type SE IV lesions the deltoid ligaments were incised.The transverse load-displacement curve was s-shaped in all uninjured joints,with the highest gradient between 10 and 20 N with no axial compression. Without axial compression in cases of F(y)=25 N transverse loads, the mean talus translation was 0.51 mm. Following type II injuries, the average talus translation was 0.68 mm (not significant) and rose to an average of 0.95 mm ( P <0.01) in type III injuries. After additional incision of the deltoid ligaments, the ankle joint subluxed permanently when more than 5-10 N transverse loads were applied. Axial loads of 300 N or more resulted in a considerable reduction in talus translations, indicating increased stability and congruency within the joint complex. In this way, the vertical loading of the ankle joints always contributed to joint stability. The average internal tibiotalar rotation reached with a torque of 2.4 Nm was 3.52 degrees and with 4.9 Nm 5.15 degrees when no axial compression was applied.External rotation measured -6.36 degrees and -8.62 degrees, respectively. Following the experimental protocol, significant increases were noted for external rotation at SE II degrees injuries ( P =0.003) and for internal rotation at SE III degrees ( P =0.03) injuries. Our data support the proposition that the deltoid ligaments and the posterior syndesmosis play a key role in the stability of ankle fractures for supination-eversion injuries. If these structures remain intact, conservative and early functional treatment are recommended in patients with minimal (<2 mm) or no fracture displacement. This concept is confirmed by the literature dealing with clinical mid- and long-term follow-up studies.     

Use of tightrope fixation in ankle syndesmotic injuries

Objective： Conventional fixation of syndesmotic injuries with screws remains problematic. A novel fibrewire device （Tightrope） has suggested advantages. However, small case series have reported high soft tissue complication rates. The purpose of our study was to quantify complication rates and further procedures in patients treated with Tightropes. A secondary objective was to determine incidence of complications and further procedures in those treated with syndesmotic screws over the same period. Methods： All patients undergoing syndesmotic fixa- tion for ankle fracture between May 2008 and October 2009 were retrospectively reviewed. Incidence of complications, secondary procedures, maintenance of syndesmotic reduc- tion and time spent on non-weight bearing were recorded. Family doctors were contacted for those treated with Tight- ropes to check for any complications managed elsewhere. Results： Thirty-five patients required syndesmoticfixation, in which 12 were treated with Tightropes. They were followed up in clinic for a mean of 12.4 weeks. Family doctors were contacted at mean 14.6 months after treatment to determine any complications suffered. There were no complications attributable to method of fixation. In this series, 12 patients underwent 13 procedures and no patient had recurrent diastasis at discharge; 23 patients treated with screw fixation underwent 45 procedures （19 were screw removals）. There was 1 case ofsyndesmotic diastasis. Screw removal resulted in 2 minor complications. Conclusion： Tightrope fixation provideds effective syndesmotic fixation that is maintained at discharge. We do not experience soft tissue complications reported elsewhere.