Comparison of the syndesmotic staple to the transsyndesmotic screw: a biomechanical study

BACKGROUND: Controversy still exists about treatment of syndesmotic injuries. This study compared the fixation strengths and biomechanical characteristics of two types of ankle fracture syndesmotic fixation devices: the barbed, round staple and the 4.5-mm cortical screw. METHODS: Cadaveric testing was done on 21 fresh-frozen knee disarticulation specimens in biaxial servohydraulic Instron testing equipment. Submaximal torsional loads were applied to specimens in intact and Weber C bimalleolar fracture states. The specimens were then fixed with one of two techniques and again subjected to submaximal torsion and torsion to failure. Biomechanical parameters measured included tibiofibular translation and rotation, maximal torque to failure, and degrees of rotation at failure. RESULTS: Compared to the intact state before testing, the staple held the fibula in a more anatomic position than the screw for mediolateral and anterior displacements (p < 0.01). With submaximal torsional testing, the staple restored 85% of the tibiofibular external rotation and all of the posterior translation values as compared to the intact state. The screw resulted in 203% more tibiofibular medial translation and 115% more external rotation than the intact state. The degree of tibial rotation during submaximal torsional loading was restored to within 15% of intact values but was 21% less with the screw. There was no statistical difference between the screw and staple when tested in load to failure. Tibiotalar rotation at failure was statistically different with the staple construct, allowing more rotation as compared to the screw. CONCLUSION: The staple restored a more physiologic position of the fibula compared to the syndesmotic screw. Both provided similar performance for the load to failure testing, while the screw reduced tibial rotation more after cyclic loading. There was more tibial rotation before failure for the staple, suggesting a more elastic construct. This study provides biomechanical data to support the clinical use of the syndesmotic staple.     

Verletzungen der unteren tibiofibularen Syndesmose

The incidence of isolated distal tibiofibular syndesmotic ruptures in acute ankle sprains lies between 1% and 11%. These injuries are frequently overseen or misdiagnosed as anterolateral rotational instability of the ankle and often become apparent through protracted courses. Although the pathomechanics and extent of syndesmotic injuries have been systematically described by Lauge-Hansen and Weber, no generally accepted guidelines exist as to when these complex injuries are to be treated surgically to ensure sufficient and stable healing of the syndesmosis besides correct alignment of the distal fibula. So far, systematic follow-up regarding syndesmotic injuries in ankle fractures is missing, although it has long been recognized that tibiofibular diastasis secondary to chronic syndesmotic instability leads to external rotation of the talus. In combination with a valgus position of the talus, this instability leads to a decrease in the contact area which results in posttraumatic arthritic changes. This paper reviews the standard diagnostic and therapeutic procedures for acute syndesmotic ruptures in fracture dislocations of the ankle. Among the few corrective procedures advocated for chronic syndesmotic insufficiency are tibiofibular arthrodesis, synthetic ligament substitutes, and tenodesis with the peroneus brevis tendon. A sufficient reconstruction must restore the stability of the ankle mortise and alignment of the fibula in the tibiofibular incisura to ensure limitation of talar rotation. Therefore, a tenodesis was developed which substitutes the three important ligaments of the syndesmotic complex. The Casting procedure for chronic syndesmotic insufficiency was modified with reconstruction of the interosseous tibiofibular ligament in addition to the anterior and posterior tibiofibular ligaments. The resulting three-point fixation of the distal fibula appears more anatomically, physiologically, and biomechanically advantageous. The operative procedure is given in detail. Distal tibiofibular syndesmosis. Persistent instability of the distal syndesmosis. Ankle fractures. Syndesmotic screw.     

Therapie der Sprunggelenksluxationsfrakturen vom Pronationstyp

Objective

Early reduction of the dislocation and anatomic reconstruction of axial alignment, ankle mortise and articular congruity with special focus on syndesmotic stability.

Indications

Fracture–dislocations resulting from pronation injuries to the ankle with a highly incongruent and unstable mortise and either considerable internal pressure on the soft tissues by the displaced fragments or open soft tissue damage.

Contraindications

General contraindications to surgery: closed reduction and cast immobilization or external fixation.

Surgical technique

Early preoperative closed reduction of complete dislocations is achieved through longitudinal traction and movements contrary to the original fracture mechanism. A cast or joint-spanning external fixator is applied temporarily. Ideally, definite anatomic reduction of the posterior tibial fragment, the distal fibula and medial malleolus and stable internal fixation is achieved within the first hours after the injury. Congruity of the ankle mortise and syndesmotic stability is controlled intraoperatively and a syndesmotic screw is inserted if necessary. In these cases, the correct positioning of the distal fibula within the tibial incisura is verified with three-dimensional fluoroscopy or postoperative computed tomography scanning.

Postoperative management

Early range of motion exercises of the ankle and subtalar joints are initiated the second postoperative day or after soft tissue consolidation and removal of the external fixation. Patients are mobilized with partial weight bearing (20 kg) in a cast or special boot for 6 weeks postoperatively. The syndesmotic screw is then removed in most cases and weight-bearing is rapidly increased.

Results

The presence of a dislocation at the time of injury represents a negative prognostic factor in malleolar fractures. Higher rates of posttraumatic arthritis are also observed with trimalleolar fracures, especially fractures of the posterior tibial rim, cartilage damage, and syndesmotic disruption. Irrespective of the fracture classsification, good to excellent results can be obtained in 75–89?% of cases with anatomic reconstruction of the ankle mortise and the articular surfaces. Proper reduction of the distal fibula into the tibial incisura is of utmost importance in cases of frank syndesmotic diastasis.     

Which Ankle Fractures Require Syndesmotic Stabilization?

Syndesmotic ruptures associated with ankle fractures are most commonly caused by external rotation of the foot, eversion of the talus within the ankle mortise, and excessive dorsiflexion. The distal tibiofibular syndesmosis consists of the anterior inferior tibiofibular ligament, posterior inferior tibiofibular ligament, and interosseous ligament, and it is essential for stability of the ankle mortise. Despite the numerous biomechanical and clinical studies pertaining to ankle fractures, there are no uniform recommendations regarding the use of the syndesmotic screw for specific injury patterns and fracture types. The objective of this review was to formulate recommendations for clinical practice related to the use of syndesmotic screw placement.     

Mid-diaphyseal fibular fractures with syndesmotic disruption: should we plate the fibula?

BACKGROUND: The treatment of mid-diaphyseal fibula fractures with syndesmotic disruption is controversial. The purpose of this study was to compare the biomechanical properties of 2 fixation constructs. MATERIALS AND METHODS: Eight pairs of human cadaveric legs were divided into two groups, both of which had midshaft fibular osteotomies and disruption of all ligamentous support up to the osteotomy level. In Group I, the left legs were fixed with only a 3.5-mm tricortical syndesmotic screw. In Group II, the right legs received this syndesmotic fixation in addition to plating of the fibula. Rotational stability was tested on each ankle in the intact, repaired, and post-cyclical load conditions. Each specimen was ultimately tested to failure in external rotation. RESULTS: The rotational stability, load to failure, and stiffness were all found to be significantly higher with the plate and syndesmotic fixation repair technique (Group II) than with the syndesmotic fixation only technique (Group I). Furthermore, fixation in Group II improved rotational stability both before and after cyclic loading. CONCLUSION: Improved biomechanical properties were found with fibular plating in addition to a syndesmotic screw in a midshaft fibular fracture model with syndesmotic and deltoid injury. CLINICAL RELEVANCE: This information may be helpful in the decision-making process to optimally treat patients with this fracture pattern.     

Evaluation of the syndesmotic-only fixation for Weber-C ankle fractures with syndesmotic injury

Background:

With the length of the fibula restored and the syndesmosis reduced anatomically, internal fixation using a plating device may not be necessary for supra-syndesmotic fibular fractures combined with diastasis of inferior tibio-fibular joint. A retrospective observational study was performed in patients who had this injury pattern treated with syndesmosis-only fixation.

Materials and Methods:

12 patients who had Weber type-C injury pattern were treated with syndesmosis only fixation. The treatment plan was followed only if the fibular length could be restored and if the syndesmosis could be anatomically reduced. Through a percutaneous or mini-open reduction and clamp stabilization of the syndesmosis, all but one patient had a single tricortical screw fixation across the syndesmosis. Patients were kept non-weight-bearing for 6 weeks, followed by screw removal at an average of 8 weeks. Outcomes were assessed using an objective ankle scoring system (Olerud and Molander scale) and by radiographic assessment of the ankle mortise.

Results:

At a mean follow-up of 13 months, the functional outcome score was 75. Excellent to good outcomes were noted in 83% of the patients. Ankle mortise was reduced in all cases, and all but one fibular fracture united without loss of fixation. Six patients had more than one malleolar injury, needing either screw or anchor fixations. One patient had late diastasis after removal of the syndesmotic screw and underwent revision surgery with bone grafting of the fibula. This was probably due to early screw removal, before union of the fibular fracture had occurred.

Conclusion:

We recommend syndesmosis-only fixation as an effective treatment option for a combination of syndesmosis disruption and Weber type-C lateral malleolar fractures.     

踝关节骨折伴下胫腓联合分离的手术治疗及临床意义

目的探讨治疗踝关节骨折伴下胫腓联合分离的手术方法及临床意义。方法自2002年1月～2005年12月对112例伴踝关节骨折下胫腓联合分离行腓骨内固定或不固定,内踝内固定,三角韧带探查修复术。未固定下胫腓联合。术后随访6～36个月,平均20.8个月。结果用Mazur评分系统评估手术疗效:优98例,良14例。未见骨折不愈合、关节不稳及创伤性关节炎等并发症。结论对伴下胫腓联合分离的踝关节骨折行手术治疗时,除了固定内、外踝,还要修复三角韧带损伤。恢复了内、外侧所有结构的完整性后才能真正恢复下胫腓联合及踝关节的正常生物力学环境和稳定性,这时即使不固定下胫腓联合,也可以获得下胫腓联合的稳定。固定内、外踝和下胫腓联合,而三角韧带的损伤不修复,虽然下胫腓韧带可以获得愈合,但三角韧带会愈合不佳、韧带松弛及功能不良,最终仍会导致创伤性关节炎。     

Predictors of functional outcome following transsyndesmotic screw fixation of ankle fractures

OBJECTIVE: Given the continued debate regarding syndesmotic screw fixation, we reviewed our institution's series of ankle syndesmotic screw insertions: 1) to examine technical aspects of syndesmotic screw fixation; and 2) to identify predictors of function and quality of life utilizing validated instruments. DESIGN: Retrospective observational study (level IV). SETTING: Three university hospitals. PATIENTS AND METHODS: All patients with ankle injuries who received syndesmotic screw fixation at 3 university-affiliated hospitals from 1998 to 2001. A combined hospital database for all 3 university affiliated hospitals was searched to identify all ankle fractures. Potentially eligible patients' charts were hand searched to determine the use of syndesmotic screw fixation. Radiographs from each patient were assessed for final eligibility for study inclusion. Baseline demographic information, fracture type (Lauge-Hansen, AO Weber), radiographic measurements of syndesmotic reduction, type of implants (number of screws, number of cortices, screw size), and screw removal at follow-up were determined. All radiographs were standardized for magnification. Patients also reported return to work, a visual analogue ankle pain score, and completed 2 functional outcomes instruments (Short Musculoskeletal Functional Assessment Index, Olerud and Molander Scale). MAIN OUTCOMES: Return to work, a visual analogue ankle pain score, and 3 functional outcomes instruments (Short Musculoskeletal Functional Assessment Index, Olerud and Molander Scale). RESULTS: Of 425 ankle fractures treated, 51 fractures had syndesmotic screw fixation. Patients were often males (67%), mean age 40.0 +/- 18.0 years, with sedentary occupations (88%), and twisting injuries (80%). Seventy percent of injuries were pronation external rotation injuries, and 30% were supination external rotation injuries. The ankle was dislocated in 45% of cases. The most common constructs for fixation included lateral plates with syndesmotic screws (45%). The majority of constructs included a single 3.5-mm cortical screw through 3 cortices of bone. Based upon postoperative x-rays, 16% of syndesmoses were not reduced. Additionally, 8 patients were deemed have inappropriate/lack of indications for syndesmotic screw insertion. At final follow-up (N = 39 patients, mean 18.1 months), patients achieved good function and quality of life (mean scores: Short Musculoskeletal Functional Assessment functional index = 11.4 +/- 10.6, Short Musculoskeletal Functional Assessment bother index = 13.5 +/- 13.1, Olerud and Molander = 74.1 +/- 23.4, visual analogue pain scale = 1.7 +/- 1.9). The only significant predictor of functional outcome was reduction of the syndesmosis (P = 0.04). This variable alone accounted for 18% of the variation in Short Musculoskeletal Functional Assessment Index physical function scores and 15% of the variance in the Olerud and Molander (running subscale) outcome measure. CONCLUSIONS/SIGNIFICANCE: Our findings suggest: 1) technical aspects of syndesmotic screw fixation vary between surgeons; 2) 16% of syndesmotic screws may have been unnecessary; and 3) despite variability in technique and indications, anatomic reduction of syndesmosis was significantly associated with improved Short Musculoskeletal Functional Assessment Index functional outcome. Larger, prospective studies are needed to further explore our findings.     

Comparing Different Surgical Techniques for Addressing the Posterior Malleolus in Supination External Rotation Ankle Fractures and the Need for Syndesmotic Screw Fixation

Trimalleolar ankle fractures are unstable injuries with possible syndesmotic disruption. Recent data have described inherent morbidity associated with screw fixation of the syndesmosis, including the potential for malreduction, hardware irritation, and post-traumatic arthritis. The posterior malleolus is an important soft tissue attachment for the posterior inferior syndesmosis ligament. We hypothesized that fixation of a sizable posterior malleolar (PM) fracture in supination external rotation type IV (SER IV) ankle fractures would act to stabilize the syndesmosis and minimize or eliminate the need for trans-syndesmotic fixation. A retrospective review of trimalleolar ankle fractures surgically treated from October 2006 to April of 2011 was performed. A total of 143 trimalleolar ankle fractures were identified, and 97 were classified as SER IV. Of the 97 patients, 74 (76.3%) had a sizable PM fragment. Syndesmotic fixation was required in 7 of 34 (20%) and 27 of 40 (68%), respectively, when the PM was fixed versus not fixed (p = .0002). When the PM was indirectly reduced using an anterior to posterior screw, 7 of 15 patients (46.7%) required syndesmotic fixation compared with none of 19 patients when the PM fragment was fixated with direct posterior lateral plate fixation (p = .0012). Fixation of the PM fracture in SER IV ankle fractures can restore syndesmotic stability and, thus, lower the rate of syndesmotic fixation. We found that fixation of a sizable PM fragment in SER IV or equivalent injuries through posterolateral plating can eliminate the need for syndesmotic screw fixation.     

Does medial tenderness predict deep deltoid ligament incompetence in supination-external rotation type ankle fractures?

OBJECTIVE: To identify whether medial tenderness is a predictor of deep deltoid ligament incompetence in supination-external rotation ankle fractures. DESIGN: All Weber B lateral malleolar fractures with normal medial clear space over a 9 month period were prospectively included in the study. Fracture patterns not consistent with a supination-external rotation mechanism were excluded. SETTING: High-volume tertiary care referral center and Level I trauma center. PATIENTS/PARTICIPANTS: Fifty-five skeletally mature patients with a Weber B lateral malleolar fracture and normal medial clear space presenting to our institution were included. INTERVENTION: All study patients had ankle anteroposterior, lateral, and mortise radiographs. Each patient was seen and evaluated by an orthopedic specialist and the mechanism of injury was recorded. Each patient was assessed for tenderness to palpation in the region of the deltoid ligament and then had an external rotation stress mortise radiograph. MAIN OUTCOME MEASURE: Correlating medial tenderness with deep deltoid competence as measured by stress radiographs. RESULTS: Thirteen patients (23.6%) were tender medially and had a positive external rotation stress radiograph. Thirteen patients (23.6%) were tender medially and had a negative external rotation stress radiograph. Nineteen patients (34.5%) were nontender medially and had a negative external rotation stress radiograph. Ten patients (18.2%) were nontender medially and had a positive external rotation stress radiograph. We calculated a chi statistic of 2.37 as well as the associated P value of 0.12. Medial tenderness as a measure of deep deltoid ligament incompetence had a sensitivity of 57%, a specificity of 59%, a positive predictive value of 50%, a negative predictive value of 66%, and an accuracy of 42%. CONCLUSION: There was no statistical significance between the presence of medial tenderness and deep deltoid ligament incompetence. There is a 25% chance of the fracture in question with medial tenderness having a positive external rotation stress and a 25% chance the fracture with no medial tenderness having a positive stress test. Medial tenderness in a Weber B lateral ankle fracture with a normal clear space on standard plain radiographs does not ensure the presence of a positive external rotation stress test.     

False negative rate of syndesmotic injury in pronation-external rotation stage IV ankle fractures

Background:

To investigate false negative rate in the diagnosis of diastasis on initial static anteroposterior radiograph and reliability of intraoperative external rotational stress test for detection of concealed disruption of syndesmosis in pronation external rotation (PER) stage IV (Lauge-Hansen) ankle fractures.

Materials and Methods:

We prospectively studied 34 PER stage IV ankle fractures between September 2001 and September 2008. Twenty (59%) patients show syndesmotic injury on initial anteroposterior radiographs. We performed an intraoperative external rotation stress test in other 14 patients with suspicious PER stage IV ankle fractures, which showed no defined syndesmotic injury on anteroposterior radiographs inspite of a medial malleolar fracture, an oblique fibular fracture above the syndesmosis and fracture of the posterior tubercle of the tibia.

Results:

All 14 fractures showed different degrees of tibiofibular clear space (TFCS) and tibiofibular overlapping (TFO) on the external rotation stress test radiograph compared to the initial plain anteroposterior radiograph. It is important to understand the fracture pattern characterstic of PER stage IV ankle fractures even though it appears normal on anteroposterior radiographs, it is to be confirmed for the concealed syndesmotic injury through a routine intraoperative external rotational stress radiograph.     

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.     

Tightrope fixation of syndesmotic injuries in Weber C ankle fractures: a multicentre case series

Background

No general consensus has yet been established for the gold standard treatment of ankle syndesmotic complex injuries. Recent literature has documented the success of ankle tightrope fixation for heterogeneous ankle fracture patterns, resulting in syndesmotic complex injuries. We present a multicentre case series assessing the clinical, radiological and functional outcomes of patients with Weber C ankle fractures treated with the Arthrex TightRope^® fixation system.

Method

We performed a retrospective analysis of all adult patients with Weber C ankle fractures who were treated with the Arthrex TightRope^® fixation system at four centres over a 3-year period. All patients were followed up for a mean of 14 months (range 12–26). Outcomes measures were assessed subjectively using functional scores (AOFAS and Olerud and Molander) and objectively using radiological measurements, complication rates and revision surgery rates.

Results

Thirty-six patients met our eligibility criteria. The mean age at operation was 31 years (range 18–65). There were 20 males and 16 females. No patients were lost to follow-up. The ankle tightrope maintained satisfactory reduction in the ankle mortise in 97% of cases. Of these 35 successfully treated cases, no evidence of re-displacement on follow-up radiographs of the syndesmotic complex was observed at an average of 10.8 months (range 6–12). Post-operative mean medial clear space was 3.1 mm, and mean tibio-fibular overlap was 10.1 mm. The mean American Orthopaedic Foot and Ankle Society (AOFAS) score was 88.8 (range 67–98) at a mean follow-up of 14 months (range 12–26). The overall complication rate was 6% (one failure requiring revision surgery and one medial sided skin irritation requiring removal of suture button). No infections or wound complications occurred.

Conclusion

Tightrope fixation is a safe alternative to screw fixation for syndesmotic complex injuries in Weber C ankle fractures. We have shown that it has low complication rates and a high patient satisfaction.

     

Syndesmotic screw fixation in Weber C ankle injuries--should the screw be removed before weight bearing?

OBJECTIVE: To compare the outcomes of Weber C ankle fractures treated with syndesmotic screw fixation where the screw was removed prior to weight bearing against those where the screw was left in situ indefinitely. DESIGN: Retrospective observational analysis of a consecutive series. SETTING: Acute tertiary hospital. PATIENTS: Thirty-three patients with ankle fractures and syndesmotic disruption were treated with open reduction, internal fixation, and syndesmotic stabilisation with a syndesmotic screw. Three patients defaulted follow-up after 1-3 months. In the remaining 30, the syndesmotic screw was removed prior to weight bearing in 23 patients and was left in situ in 7 patients. Mean follow-up was 15 months. METHODS: Assessment with subjective, objective, and radiographic criteria was used. Statistical analysis was performed with independent groups t-test and chi-square test. RESULTS: There was no statistically significant difference between ankle scores, functional outcome or range of motion between the two groups. However, there was a significantly higher incidence of syndesmotic screw breakage and osteolysis in the group where screws were retained. CONCLUSIONS: Judicious fixation of Weber C type injuries with syndesmotic screw fixation allows for good functional outcome. Retaining of the syndesmotic screw on commencement of weight bearing seems to increase the risk of subsequent screw breakage. Removal of the screw prior to weight bearing should be performed to avoid such an eventuality.     

Intraoperative diagnosis of syndesmosis injuries in external rotation ankle fractures

OBJECTIVE: This study was designed to compare intraoperative fluoroscopic stress testing, static radiographs, and biomechanical criteria for the diagnosis of distal tibiofibular syndesmotic instability associated with external rotation type ankle fractures. DESIGN: Prospective, consecutive series. SETTING: Academic level 1 trauma center. PATIENTS/PARTICIPANTS: Thirty-eight skeletally mature patients with unstable unilateral external rotation ankle fractures were prospectively recruited. INTERVENTION: Before surgery, the treating surgeon detailed the operative treatment plan, including need for syndesmotic fixation. In pronation-external rotation injuries, biomechanical criteria were applied to predict syndesmotic instability. Ankles were examined using intraoperative fluoroscopic external rotation stress tests. The contralateral uninjured limb was used as a control. A 7.2-Nm force was applied for the external rotation stress examination. Stress testing was performed after lateral malleolar fixation and repeated after medial and syndesmotic fixation. MAIN OUTCOME MEASURES: The incidence of syndesmotic instability was determined based on radiographic clear space measurements and compared with previously published criteria. RESULTS: Intraoperative fluoroscopy detected unpredicted syndesmotic instability in 37% of ankles. In supination-external rotation (OTA 44B) injuries, unpredicted syndesmosis instability was found in 10 of 30 patients (33%). In pronation-external rotation injuries (OTA 44C), 4 of 7 patients (57%) were associated with syndesmosis disruption not predicted by biomechanical criteria. In bimalleolar fractures, syndesmosis fixation improved stability compared with rigid bimalleolar fixation alone (P < 0.01). CONCLUSIONS: Preoperative radiographs and biomechanical criteria are unable to routinely predict the presence or absence of syndesmosis instability. Rigid bimalleolar fixation was frequently not sufficient to stabilize syndesmotic disruption. Intraoperative stress fluoroscopy is a valuable tool for detection of unstable syndesmotic injuries.     

Stable ankle joint fractures. Indications for operative or conservative treatment?

In German literature, ankle joint fractures are mostly classified in three groups according to Weber. In cases of the type A, the fracture line runs below, in cases of type B at height of the syndesmotic ligaments. C-type fractures are typically seen above this region. However, this practical and simple classification allows no inferences at accompanying injuries which in turn influence the functional outcome. We observed isolated fractures of the lateral malleolus in more than 60% of all type B-fractures, as soon as in the majority the type A-fractures. Since isolated medial ankle fractures occur very rarely, careful exclusion of further injuries is advisable here. In order to differentiate stable ones from unstable type B ankle injuries, we carry out a manual stress test, if there is less than 2 mm fracture dislocation and a congruent ankle mortise. In this manner we could find that stable lateral ankle fractures are characterized with a combination of an intact dorsal syndesmotic and medial ligament. Stable type B and undisplaced type A fractures were treated conservatively with an ankle brace (Aircast?). Unstable ankle injuries were treated by ORIF. Conservative treatment for undisplaced medial malleolar fractures is recommended, if x-rays showed less than 2 mm dislocation which allows a tibio-talare impingement. Biomechanical investigations could prove a significant increase in ankle joint stability, when an axial load of 300 N was applied to various horizontal loads. The talus does not follow automatically a displaced fibular fracture. The dorsal syndesmotic and the medial deltoid ligaments control ankle joint stability.     

Comparison of Open Anterior Syndesmotic Repair Augmented With Suture-Tape and Trans-syndesmotic Screw Fixation: A Biomechanical Study

The treatment of syndesmotic injuries with ankle fractures is controversial. The purpose of this study was to compare the biomechanical properties of open anterior syndesmotic repair with those of screw fixation. Ten matched pairs of human cadaver specimens were subjected to open syndesmotic repair or screw fixation. Each specimen underwent initial intact physiologic loading, consisting of 10 cycles of external torsional loading with a peak torque of 7.5 Nm at 0.05 Hz. Injuries of the anterior inferior tibiofibular ligament, tibiofibular interosseous membrane, and deltoid ligament were applied to each specimen. Postfixation cyclic loading consisted of 50 cycles of combined axial and external rotation loading with peak torques of 750 N and 7.5 Nm at a rate of 0.05 Hz. After postfixation loading, each specimen underwent failure loading by external rotation at 0.25 degrees/second. Failure torque and failure angle were measured. The paired t test and Wilcoxon signed-rank test were used to analyze the data. Mean failure torques were 95.63 Nm in the open anterior syndesmotic repair augmented with suture-tape group and 108.61 Nm in the screw group. Mean failure angles were 34.93 degrees in the open anterior syndesmotic repair augmented with suture-tape group and 43.55 degrees in the screw group. These data were not statistically significantly different between the groups (p= .7682 and .4133, respectively). Open anterior syndesmotic repair augmented with suture tape for ankle syndesmotic injury provides similar torsional strength to that of screw fixation. Therefore, this technique can be considered as an alternative treatment option for syndesmosis injury.     

Weber B型和C型踝关节骨折术中下胫腓联合稳定性的评价

目的 探讨Weber B型和C型踝关节骨折术中下胫腓联合稳定性的评价方法及效果. 方法 2007年3月至2009年3月,收治231例Weber B型和C型踝关节骨折患者,术中踝关节骨折的骨性结构恢复后,在C型臂X线透视下通过腓骨外拉应力试验来检查下胫腓联合的稳定性. 结果 Weber B型踝关节骨折145例,42例(28.9%)出现下胫腓联合不稳定;C型踝关节骨折86例,62例(72.1%)出现下胫腓联合不稳定.下胫腓联合不稳定的踝关节骨折均进行了下胫腓联合固定. 结论 Weber B型和C型踝关节骨折在骨性结构被恢复后,下胫腓联合不稳定仍然有较高的发生率.术中通过C型臂X线透视下腓骨外拉应力试验能简单有效地对下胫腓联合的稳定性进行评价,可根据其稳定性来确定是否行下胫腓联合固定.     

Complications of Distal Tibiofibular Syndesmotic Screw Stabilization: Analysis of 236 Patients

The objective of the present study was to evaluate our complications of screw stabilization and to formulate recommendations for clinical practice. Using a prospectively collected fracture database, the data from 236 consecutive adult patients were analyzed who had undergone syndesmotic screw stabilization from January 1979 to December 2000 at our level I academic trauma center. We observed 16 complications in 15 patients. The average patient age was 37.5 years. Of the 15 patients, 1 had a Weber B fracture and 14 had a Weber C ankle fracture. These complications included tibiofibular synostosis in 11 patients, screw breakage in 4 patients, and late diastasis in 1 patient. All breakages occurred in Weber C fractures. In particular, the 3.5-mm screws, penetrating both tibial cortices, tended to break. Synostosis was observed in 3% of the Weber B fractures and 5% of the Weber C fractures. Weightbearing in a plaster cast during syndesmotic screw stabilization is a safe postoperative treatment. We suggest that the use of 3.5-mm screws and screws penetrating 2 tibial cortices have a greater risk of breakage. Because of the low complication rate and more difficult treatment of late syndesmotic diastasis, a syndesmotic screw should be placed when in doubt of the indication.     

Weber B型和C型踝关节骨折术中下胫腓联合稳定性的评价

目的 探讨Weber B型和C型踝关节骨折术中下胫腓联合稳定性的评价方法及效果. 方法 2007年3月至2009年3月,收治231例Weber B型和C型踝关节骨折患者,术中踝关节骨折的骨性结构恢复后,在C型臂X线透视下通过腓骨外拉应力试验来检查下胫腓联合的稳定性. 结果 Weber B型踝关节骨折145例,42例(28.9%)出现下胫腓联合不稳定;C型踝关节骨折86例,62例(72.1%)出现下胫腓联合不稳定.下胫腓联合不稳定的踝关节骨折均进行了下胫腓联合固定. 结论 Weber B型和C型踝关节骨折在骨性结构被恢复后,下胫腓联合不稳定仍然有较高的发生率.术中通过C型臂X线透视下腓骨外拉应力试验能简单有效地对下胫腓联合的稳定性进行评价,可根据其稳定性来确定是否行下胫腓联合固定.