Biomechanical Analysis of a Novel Syndesmotic Plate Compared With Traditional Screw and Suture Button Fixation.

Many lateral malleolus fractures have been found to have syndesmosis injuries after anatomic reduction. The main methods for the treatment of syndesmosis injuries are screw fixation and suture-button flexible fixations. In pursuit of innovation, we have designed a novel syndesmotic plate (NSP) for simultaneous fixation of lateral malleolus fractures and distal tibiofibular syndesmosis injuries. The purpose of this study is to compare the biomechanical characteristics of the NSP to syndesmotic screw and suture-button fixations. Twelve adult cadaveric specimens were used in this experiment. Axial loading as well as rotation torque were applied in 3 different ankle positions: neutral, dorsiflexion, and plantarflexion. After the initial specimens were tested, they were made into a pronation-abduction III fracture model as described by Lauge-Hansen. Subsequently, the specimens were fixed sequentially using a distal fibular anatomic locking plate (DFALP) combined with syndesmotic screws, DFALP combined with suture button, and NSP. Then the above tests were repeated. The syndesmotic displacement and the strain of the tibia and fibula were recorded during the experiment. In most cases, the displacements and strains of the NSP group and the screw group were smaller than the suture button groups and the native (SBGAN) (p < .05), and the displacements and strains of the NSP group were also slightly smaller than the screw group in most cases, and there was no significant difference between the 2 groups. The NSP we developed has a fixed strength no less than the traditional syndesmotic screw fixation. This provides us a new idea for the treatment of distal tibiofibular syndesmosis injuries.

Relationship between fracture morphology of lateral malleolus and syndesmotic stability after supination-external rotation type ankle fractures.

BACKGROUND: Syndesmotic injury with supination-external rotation (SER)-type ankle fractures are well known for the serious damages to the osseous and soft tissue envelope. However, the Lauge-Hansen classification system does not provide sufficient information related to syndesmotic injury. In this study, we aimed to investigate factors for preoperative detection of syndesmotic injury according to fracture patterns in SER III and IV ankle fractures by using radiography and computed tomography (CT). METHODS: All operative SER III and IV ankle fractures treated by a single surgeon from 2009 to 2015 were enrolled in a retrospective database. Based on computed tomographic evidence and intra-operative Cotton test, stable and unstable groups of the ankle factures were divided. RESULTS: A total of 52 patients with SER III, 75 patients with SER IV, and 27 patients with SER IV equivalent ankle fractures were identified, with 106 in the unstable syndesmosis group (68.8%) and 48 patients in the stable syndesmosis group (31.2%). Medial space widening and fragment angle of the fibular posterior cortex were significant predictors. The cutoff values of these factors were 4.4 mm and 32.8 degrees, respectively. CONCLUSIONS: CT was superior to simple radiography in predicting syndesmotic injury at the preoperative period in SER-type III and IV. Medial space widening and fragment angle of the fibular posterior cortex, as predictive factors, showed significant correlations. In particular, sharper fragment angle of the posterior cortex indicated higher probability of instability that remained after fracture fixation.

A rare type of ankle fracture: Syndesmotic rupture combined with a high fibular fracture without medial injury.

High fibular spiral fractures are usually caused by pronation-external rotation mechanism. The foot is in pronation and the talus externally rotates, causing a rupture of the medial ligaments or a fracture of the medial malleolus. With continued rotation the anterior and posterior tibiofibular ligament will rupture, and finally, the energy leaves the fibula by creating a spiral fracture from anterior superior to posterior inferior. In this article we demonstrate a type of ankle fracture with syndesmotic injury and high fibular spiral fractures without a medial component. This type of ankle fractures cannot be explained by the Lauge-Hansen classification, since it lacks injury on the medial side of the ankle, but it does have the fibular fracture pattern matching the pronation external rotation injury (anterior superior to posterior inferior fracture). We investigated the mechanism of this injury illustrated by 3 cases and postulate a theory explaining the biomechanics behind this type of injury.

Effect of syndesmosis injury in SER IV (Weber B)-type ankle fractures on function and incidence of osteoarthritis.

BACKGROUND: Syndesmosis fixation of Lauge-Hansen SER IV, Weber B ankle fractures is controversial. This study compared a matched pair of SER IV patients with stress proven syndesmotic injuries with the same number without stress proven syndesmotic injury in terms of functional, pain, and radiologic result. METHODS: The study was based on a RCT-study comparing syndesmotic transfixation to no fixation in SER IV (Weber B)-type ankle fractures. Twenty-four patients with a syndesmosis injury found on the intraoperative 7.5 Nm standardized external rotation test were compared to 24 patients with a stable syndesmosis. The pairs were matched by fracture morphology, sex, and age. The primary outcome measure was ankle function as assessed by the Olerud-Molander score. Weight-bearing plain radiographs and 3T MRI of the injured ankle were used to assess ankle joint congruity and osteoarthritis, according to Kellgren-Lawrence classification and cartilage defects. RESULTS: The Olerud-Molander score was 86 in syndesmosis injury patients and 90 in patients with normal syndesmosis (P = .28). The incidence of ankle joint osteoarthritis on plain radiographs was not significantly different between the groups (Grade I 5% vs 21%; Grade II 86% vs 75%; Grade III 9% vs 4%; P = .34). MRI scans showed TC joint cartilage defects in 54% of the patients: 12 (56%) in the syndesmosis injury group vs 13 (54%) in the group without syndesmosis injury (P > .9). CONCLUSION: After 4 to 6 years of follow-up, clinical and radiologic outcome were not different in patients with syndesmosis injury compared to patients with stable syndesmosis in SER IV (Weber B)-type ankle fractures. LEVEL OF EVIDENCE: Prognostic Level II, comparative study.

Comparison of radiographic stress tests for syndesmotic instability of supination-external rotation ankle fractures: a cadaveric study.

OBJECTIVE: According to the classification of Lauge-Hansen, supination-external rotation IV (OTA 44-B) injuries should not have syndesmotic instability; yet, several studies have suggested disruption is present in up to 40% of these injuries based on stress tests. In this study, we examine various stress radiographic parameters in a cadaver model of supination-external rotation IV equivalent injury. We hypothesize that external rotation stress testing and widening of the medial clear space do not always represent syndesmotic instability. Rather, the better predictor of syndesmotic instability will be an increased tibia-fibula clear space with the lateral stress test. METHODS: Eleven fresh frozen human lower limbs were each secured into a custom frame. External rotation stress test was performed by applying an external moment of 7.5 Nm, and lateral stress test was performed by applying 100 N lateral pull at the distal fibula. True mortise radiographs were taken of intact ankles and while performing external rotation and lateral stress tests at each stage of sequentially sectioning the ankle ligaments. The deltoid ligament was sectioned first, then anterior-inferior tibiofibular ligament, posterior-inferior tibiofibular ligament, and interosseous membrane. Tibiofibular clear space and medial clear space were measured on each radiograph. RESULTS: External rotation stress test produced significant medial clear space widening when the deltoid ligaments were sectioned (P < 0.05). Lateral stress test produced no significant widening of the tibiofibular clear space until interosseous membranes were sectioned (P < 0.05). CONCLUSIONS: Lateral stress test with widening of the tibiofibular clear space is the preferred indicator of syndesmotic instability. The external rotation stress is a poor indicator of syndesmotic injury in the setting of deltoid ligament injury.

Correlation of weightbearing radiographs and stability of stress positive ankle fractures.

BACKGROUND: A positive external rotation stress test has been used as an indication for operative treatment of fractures of the lateral malleolus. The objective of the current study was to ascertain the results of a protocol initially treating stress positive ankle fractures nonoperatively and utilizing weightbearing radiographs in surgical decision making. METHODS: We performed a prospective study of lateral malleolar fractures with an associated medial ligamentous injury. All patients with fractures of the lateral malleolus with medial sided symptoms and/or signs, and an intact ankle mortise underwent an external rotation stress test to confirm injury to the deltoid ligament (stress positive). Patients with a positive stress test were placed in a short-leg walking cast and seen in 7 days where weightbearing radiographs of the ankle were obtained. If the radiographs demonstrated an intact mortise, then nonoperative treatment was continued. If the weightbearing radiographs demonstrated medial clear space widening, then the patient was offered operative treatment to restore the congruency of the ankle mortise. Patients were assessed for conversion to operative treatment, complications, and functional outcome. Thirty-eight patients were enrolled in the study. Using Lauge-Hansen classification 36 (95%) were stress positive supination-external rotation fractures and 2 (5%) were stress positive pronation-external rotation fractures. Followup assessment was performed at a minimum of 6 months and averaged 12 months. RESULTS: Weightbearing radiographs at the first post-injury clinic visit had an average medial clear space of 2.9 ±0.9 mm. Three (8%) patients met our criteria for medial clear space widening and underwent operative treatment. Of these three patients, two were pronation-external rotation fracture patterns. Therefore, 3% of the supination-external rotation IV fractures, and all of the pronation-external III/IV rotation fractures ultimately required operative treatment. At final followup, the average AOFAS hindfoot score was 92 ±8.1. CONCLUSION: Ligamentous supination-external rotation Stage IV fractures with an intact mortise on static radiographs can be initially treated nonoperatively. Weightbearing radiographs should be utilized to assess congruency of the ankle mortise during an early post-injury visit. Utilizing this approach, a significant number of surgeries were avoided, and good to excellent results were obtained. From our early experience, nonoperative treatment of pronation-external rotation III/IV injuries using this protocol is not recommended.

[Supination external rotation lesions of the ankle joint in osteoporotic lower leg specimens. Experimental induction and review of the literature]. / Die Supinations-Eversions-Verletzung des OSG in osteoporotischen Unterschenkelpräparaten. Experimentelle Induktion und Literaturübersicht.

BACKGROUND: Knowledge of the pathomechanism and the detailed extent of ankle joint lesions determines adequate therapy and success of treatment. MATERIAL AND METHODS: Supination external rotation lesions were induced in 29 human cadavera with a testing apparatus; 27 of these specimens were from elderly women. Bone mineral density was measured. The literature review includes experimental studies of this fracture entity. RESULTS: We induced stage II in 42%; applying an additional lateral force on the fibula raised the incidence. The syndesmosis stayed intact in 50% although the fibula fractured at the level of the tibial plafond. Stage IV lesions were registered in 25%. The overall low bone mineral density showed a positive correlation to the angle at which the fibula fracture occurred. CONCLUSIONS: We reproduced supination external rotation lesions according to Lauge-Hansen in osteoporotic ankles. There is a certain discrepancy between the obligatory lesion of the inferior anterior tibiofibular syndesmosis at stage II according to Lauge-Hansen, as we observed an intact syndesmosis in 50% at stage II. Stage IV defining medial malleolar fractures were reproduced after Lauge-Hansen and Michelson et al.

Surgical versus nonsurgical treatment of the SE4-equivalent ankle fracture: a retrospective functional outcome study.

Treatment of Lauge-Hansen supination-eversion (SE)4-equivalent ankle fractures is controversial. This retrospective study conducted at a level-I trauma center compared the clinical outcome of nonsurgical vs open management of these fractures. One thousand eight ankle fractures treated between 1998 and 2003 were reviewed. Forty-three patients who met the criteria for a SE4-equivalent ankle fracture were identified. Average patient age of 23 men and 20 women was 42 years (range, 18-84 years). Olerud Molander ankle scores were recorded. Medical records and radiographs of all patients were reviewed. Average follow-up was 20 months.Twenty-six patients were treated nonsurgically, with an average ankle score of 84 ± 4. Seventeen patients treated surgically had an average ankle score of 63 ± 5. The difference is statistically significant (unpaired t test, P=.0035). There was no difference between open vs closed treatment in maintaining a reduction. To investigate the reason for poor results in the surgical group, we sought an association between functional ankle score and common covariables and found that age and preoperative radiographic grading were important variables for ankle score. Patients younger than 30 years had an average ankle score of 85, whereas those older than 50 years had an average score of 61 (P<.001). Type 1 fractures (medial clear space >5 mm in stress view only) had an average ankle score of 89, type 2 (medial clear space >5 mm but <10 mm) an average score of 76, and type 3 (medial clear space >10 mm or presented with fracture dislocation and/or syndesmosis injury) an average score of 61. Our data support that type 1 and 2 fractures can effectively be treated nonsurgically.

Ankle fracture syndesmosis fixation and management: the current practice of orthopedic surgeons.

There is a wide variety of treatments for disruption of the syndesmosis. There is also controversy as to which device should be used for fixation of the syndesmosis, how many devices should be used, how many cortices the screws should engage, and whether, when, and where the screws should be removed. We conducted a study to determine how orthopedic surgeons manage these injuries. In a survey, we asked orthopedic trauma and foot and ankle fellowship directors and members of the Orthopaedic Trauma Association and the American Orthopaedic Foot and Ankle Society how they routinely treated the syndesmotic injury component of Danis-Weber type C or Lauge-Hansen pronation-external rotation type IV ankle fractures. The overall response rate was 50% (77/153). Fifty-one percent of respondents routinely used 3.5-mm cortical screws, 24% routinely used 4.5-mm cortical screws, and 14% routinely used a suture fixation device. Forty-four percent of respondents routinely used 1 screw, 44% routinely used 2 screws, and the rest were undecided between 1 and 2 screws. Twenty-nine percent of respondents engaged 3 cortices with syndesmotic screws, and 67% engaged 4 cortices. Syndesmotic screws were routinely removed 65% of the time and left in place 35% of the time. Routine removal of syndesmotic screws was done in the operating room in 95% of cases; it was done at 3 months in 49% of cases, at 4 months in 37%, and at 6 months in 12%. The most common method for treating syndesmotic injuries was through use of 3.5-mm screws engaging 4 cortices routinely removed in the operating room at 3 months. Number of screws used to fix the syndesmosis, either 1 or 2, was evenly split.

The use of weightbearing radiographs to assess the stability of supination-external rotation fractures of the ankle.

BACKGROUND: Isolated lateral malleolar fractures usually result from a supination-external rotation (SER) injury and may include a deltoid ligament rupture. The necessity of operative treatment is based on the recognition of a relevant medial soft-tissue disruption. Currently used tests to assess ankle stability include manual stress radiographs and gravity stress radiographs, but seem to overestimate the need for fracture fixation. METHODS: We investigated the use of weightbearing radiographs to distinguish stable and unstable isolated lateral malleolar fractures induced by the SER mechanism in 57 patients. Patients with stable fractures (SER type II according to the Lauge-Hansen classification) were treated non-operatively with varying external support. Forty-seven patients were evaluated by questionnaire and AOFAS ankle-hindfoot score. Follow-up was 18-120 months (mean 62). RESULTS: Fifty-one of fifty-seven (90%) patients were found to have stable fractures (SER type II) and were treated nonoperatively. The AOFAS score was 96.1 points on average (range 85-100) at latest follow-up. Four patients reported minor complaints. A "moderate" correlation of risk factors (i.e. smoking) to delayed bone healing was found while the correlation of varying external support (i.e. bandage, cast) to the AOFAS score and delayed bone healing was "poor". CONCLUSION: The use of weightbearing radiographs is an easy, pain-free, safe and reliable method to exclude the need for operative treatment, with excellent clinical outcome in the majority of the patients seen at latest follow-up. The delay of 3-10 days until the decision about surgical treatment is well accepted by the patients.

A new interpretation of the mechanism of ankle fracture.

BACKGROUND: Researchers have found it difficult to recreate a Lauge-Hansen supination-external rotation-type ankle fracture in experimental settings. We hypothesized that a pronation-external rotation mechanism could cause both distal, short oblique and high fibular fractures and that the fracture type would be affected by associated, laterally directed forces applied to the foot. Methlods: Twenty-three cadaver ankles were subjected to fracture loading that replicated the Lauge-Hansen pronation-external rotation mechanism with or without applying an external lateral force. In Phase I, an axial load was applied to fifteen specimens mounted on a materials testing machine. Each foot was rotated externally to failure. In Phase II, eight specimens were tested according to the Phase-I protocol, but external forces were applied laterally at the foot to increase the abduction moment at the ankle. Load and position versus time curves were recorded and were correlated with video image data to establish the sequence of failure of specific anatomic structures. RESULTS: Eight specimens tested in Phase I sustained an oblique fracture of the distal end of the fibula with both medial and posterior injuries that occurred after the fibular fracture. Increasing the external lateral force and hence the abduction moment within the ankle (Phase II) resulted in three of eight specimens sustaining a high fibular fracture with a reversed fracture line (anterosuperior to posteroinferior) and/or a comminuted high fibular fracture. The distribution of traditional pronation-external rotation-type fractures differed significantly between Phase I and Phase II (p=0.032). CONCLUSIONS: This study generated counterexamples to the Lauge-Hansen classification system by showing that a short oblique fracture of the distal end of the fibula can occur with the foot in the pronated position. Furthermore, a high fibular fracture was recreated by increasing the abduction moment at the ankle.

Arthroscopically detected intra-articular lesions associated with acute ankle fractures.

BACKGROUND: Anatomic surgical realignment of ankle fractures may still be associated with poor clinical outcomes, possibly as a result of occult intra-articular injury. The aim of this study was to determine if the severity of an acute ankle fracture is correlated with an increased number of arthroscopically detected intra-articular chondral lesions. METHODS: We conducted a retrospective review of the medical charts on 283 ankle fractures that had been treated with open reduction and internal fixation and for which ankle arthroscopy had been routinely performed. The severity of the ankle fractures was categorized, with use of the arthroscopic findings derived from the operative reports as well as the findings on preoperative radiographs, according to the Lauge-Hansen criteria. RESULTS: Of the 283 patients, eighty-four (forty-four female and forty male) met our inclusion criteria. Chondral lesions were found in sixty-one patients (73%). Of seventeen fractures graded as pronation-external rotation or supination-external rotation type I according to the Lauge-Hansen classification, fifteen were associated with one or no chondral lesion and two, with two or more chondral lesions. Of ten fractures graded as pronation-external rotation or supination-external rotation type II, nine were associated with one or no chondral lesion and one, with two or more chondral lesions. Of fifty-six fractures graded as pronation-external rotation or supination-external rotation type IV, twenty-seven were associated with one or no chondral lesion and twenty-nine, with two or more chondral lesions. Type-IV pronation-external rotation and supination-external rotation ankle fractures were more likely to be associated with two or more chondral lesions than type-I fractures (odds ratio = 8.1, 95% confidence interval = 1.7 to 38.6; p = 0.0044) or type-II fractures (odds ratio = 9.7, 95% confidence interval = 1.1 to 81.5; p = 0.0172). CONCLUSIONS: Chondral lesions are commonly found after an acute ankle fracture. This retrospective study demonstrated that the number of intra-articular chondral lesions associated with the more severe ankle fracture patterns (pronation-external rotation and supination-external rotation type-IV fractures) was greater than the number associated with the less severe ankle fracture patterns.

Clinical utility of a stability-based ankle fracture classification system.

OBJECTIVE: Neither of the ankle fracture classification systems (Lauge-Hansen or Weber) in widespread use today is prognostic. To test the hypothesis that ankle fracture prognosis is dependent on initial biomechanical stability, an alternative classification system created using stability-based treatment criteria was developed on the basis of a structured analysis of the ankle fracture literature. DATA SOURCES: All English-language papers reporting on ankle fractures (searched using the terms "ankle + fracture") published between 1966 and 2005 with available online abstracts via PubMed were screened. STUDY SELECTION: Abstracts were manually screened for inclusion using the following criteria: (1) there were at least 2 groups of patients categorized on the basis of either fracture configuration or treatment and (2) data was reported in sufficient detail to permit interstudy comparisons. DATA EXTRACTION: Each included paper was abstracted into a computerized database for consistent data capture. Data elements included the following: fracture classification, stability definitions, surgical indications, patient follow-up parameters, and outcome measures. Ankle fractures were also stratified into stable and unstable groups using predefined stability criteria, and the outcome measures were re-analyzed. DATA SYNTHESIS: Wilcoxon matched-pairs signed-rank test was used for statistical comparisons, assigning statistical significance to 2-tailed tests with P < 0.05. CONCLUSIONS: The results support the hypothesis that a stability-based ankle fracture classification system can be prognostic. For unstable ankle fractures, the radiographic outcomes were better after surgery, when the decision for surgery was made on the basis of stability (P = 0.0173). Overall, non-operative treatment results were also better with stability-based treatment (P = 0.0299).

Retrospective analysis of malleolar fractures in an impact environment.

To protect against malleolar fractures in frontal crashes it is important to understand the mechanisms of injury. We have investigated the accuracy of Orthopaedic Specialists in deducing the injury mechanisms of experimentally generated malleolar fractures from radiographs; and the applicability of classic descriptors of injury mechanisms, such as the Lauge-Hansen classification system, in analysing impact induced trauma. Orthopaedic Specialists did not consistently deduce the mechanism of ankle injuries suggesting there may not be a unique fracture pattern for every injury mechanism and that the Lauge-Hansen classification system does not reliably describe ankle fractures created in the impact environment.

[The role of the tibiofibular syndesmotic and the deltoid ligaments in stabilizing Weber B type ankle joint fractures--an experimental investigation]. / Beitrag der Syndesmosen und des Deltabandes zur Stabilität der Aussenknöchelfraktur Typ Weber B. Eine experimentelle Untersuchung.

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.

The ANK device: a new approach in the treatment of the fractures of the lateral malleolus associated with the rupture of the syndesmosis.

The ANK device was developed for the treatment of fractures of the lateral malleolus occurring with rupture of the syndesmosis. While it provides the anatomic reduction of the fracture and the syndesmosis, it allows the physiologic movements of the fibula. It is not used for comminuted fractures of the lateral malleolus and in cases where fibular medullary canal is narrow. We included forty-nine patients who had the ANK device applied and at least 2 years follow-up. The mean follow-up was 41 months (range 24-124). The fractures were evaluated according to the Lauge-Hansen classification; 25 cases were evaluated as supination-external rotation, 11 cases were pronation-abduction, and 13 cases were pronation-external rotation type fractures. There were also 46 fractures of the medial malleolus and three ruptures of the deltoid ligament. Twenty-nine (59,2%) patients were evaluated as excellent, 12 (24,5%) as good, 5 (10.2%) as fair and 3 (6.1%) as poor. Arthrosis was observed in 3 (6.1%) of the patients.

Ankle fractures involving the fibula proximal to the distal tibiofibular syndesmosis.

Thirty-two cases of ankle fractures associated with fibular fractures above the distal tibiofibular syndesmosis were studied. All were treated with open reduction and internal fixation. The average follow-up was 25 months. The results of the postoperative evaluation were rated, based on subjective clinical criteria, as good, fair, and poor. According to the Lauge-Hansen classification, there were 17 (53%) cases of supination-external rotation injury (2 stage 2 and 15 stage 4), 9 (28%) cases of stage 3 pronation-abduction injury, and 6 (19%) cases of pronation-external rotation injury (3 stage 3 and 3 stage 4). All cases could be classified as Weber type C or as suprasyndesmotic, fibular diaphyseal fracture (44-C) according to the Orthopaedic Trauma Association classification. In 18 (56%) cases, the fracture was associated with ankle dislocation. There were seven (22%) open fractures, (two grade I, four grade II, and one grade IIIA). Syndesmotic screws were used in 23 (72%) cases (12 supination-external rotation injury, 6 pronation-external rotation injury, and 5 pronation-abduction injury). The syndesmotic screw was removed after an average of 9 weeks. Four (13%) nonunions and two (6%) delayed unions of the fibula were treated with bone grafting and/or hardware revision and eventually healed. Three of the nonunions had poor clinical results because of degenerative ankle joint arthritis in two (one of them ended in arthrodesis) and deep infection, which was eventually cured, in the third. The fourth nonunion had a fair result. One of the delayed unions had a fair result (an obese patient) and the other had a good result. Two patients developed deep infections; one ended in gangrene and amputation in a diabetic patient, and the other was a patient with fibular nonunion that eventually healed. Three patients had superficial infections that were treated successfully. Of the 32 cases, 23 (72%) showed good results, 4 (13%) showed fair results, and 5 (16%) showed poor results. The cases with poor results included three fibular nonunions, one deep infection, and one recurrent superficial infection and wound dehiscence after hardware removal. A syndesmotic screw is usually needed in cases of fracture-dislocations. Two patients with occult fibular nonunions developed diastasis of the syndesmosis after removal of the syndesmotic screw. It was found that reduction and temporary pinning of the distal tibiofibular joint helps achieve fibular length, which is crucial to restoring the biomechanics of the ankle joint. It seems advisable not to remove the syndesmotic screw until there are signs of healing of fibular fracture to avoid diastasis of the distal tibiofibular joint. Bone grafting should be considered in high energy fractures with comminution. These complex injuries are associated with higher rates of complications. Poor results can be attributed to fracture factors, e.g., open fractures, infections; patient factors, e.g., obesity, lowered immunity as in diabetes, and noncompliance; and iatrogenic factors, e.g., early removal of syndesmotic screws.

Motion of the ankle in a simulated supination-external rotation fracture model.

UNLABELLED: An experimental study was undertaken with use of axially loaded, unconstrained cadaver ankles to determine the motion patterns seen with progressive stages of the supination-external rotation type of fracture. As described by Lauge-Hansen, these fractures were modeled by transection of the anterior aspect of the capsule and the anterior tibiofibular ligament (stage I), followed by oblique fibular osteotomy ending at the level of the ankle joint (stage II), transection of the posterior aspect of the capsule (stage III), and sequential sectioning of the superficial and deep fibers of the deltoid ligament (stage IV). Thirteen specimens were tested on an apparatus that allowed for controlled loading while the ankle was passed through a physiological range of dorsiflexion and plantar flexion. The ankles were unconstrained about the axial (internal and external rotation) and coronal (varus and valgus angulation) axes. Measurements were made throughout the range of motion in these axes in order to define the kinematic behavior. In the intact specimens, maximum plantar flexion was associated with a mean (and standard deviation) of 1.9 +/- 4.12 degrees of internal rotation of the talus and maximum dorsiflexion, with a mean of 7.2 +/- 3.88 degrees of external rotation. Varus angulation increased slightly with plantar flexion compared with the value in dorsiflexion (2.4 +/- 2.40 compared with 0.3 +/- 1.96 degrees). Internal and external rotation was not affected by fibular osteotomy or by transection of the superficial fibers of the deltoid ligament. Transection of the deep fibers of the deltoid ligament caused a significant (p < 0.02) increase in external rotation of the talus at maximum plantar flexion; this was corrected incompletely by insertion of an anatomical fibular plate. With the numbers available for study, we could not show that varus or valgus angulation was significantly affected by any combination of sectioning of the deltoid ligament and fibular osteotomy. These experiments were repeated with the addition of fixation of the subtalar joint with a talocalcaneal screw. With the number of specimens available, we could detect no significant difference, with respect to axial rotation, due to fixation of the subtalar joint. However, along the coronal axis, increased valgus angulation (p < 0.02) was seen during plantar flexion when either the deep or the superficial fibers of the deltoid ligament had been cut. CLINICAL SIGNIFICANCE: These results indicate that stability of the loaded ankle is primarily due to the deltoid ligament, which exerts a restraining influence on external rotation of the talus. Complete fibular osteotomy did not cause abnormal motion of the ankle in the absence of a medial injury. In the presence of a complete injury, lateral reconstruction only partially restored the mechanical integrity of the ankle. The results provide justification for the non-operative treatment of isolated fractures of the lateral malleolus. The data also suggest that a lateral fracture associated with a major injury of the deltoid ligament should be treated with anatomical lateral fixation followed by immobilization without early motion, to allow adequate healing of the deltoid ligament at its resting length.

An axially loaded model of the ankle after pronation external rotation injury.

Using a testing apparatus that allows axial loading and displacement in the sagittal, axial, and coronal planes, 6 ankles were tested under experimental conditions intended to model the Lauge-Hansen pronation external rotation injury. All specimens were rotated through a continuous range of sagittal motion with the ankle under 300 N of axial load as the coupled motion of the ankle in the coronal and axial axes was recorded. Combinations of fibular osteotomy, disruption of the syndesmosis up to 6 cm above the plafond, and deltoid transection were tested to mimic Stages I to III of the pronation external rotation ankle fracture. The effects of stabilization of the fibula and syndesmosis also were examined. Neither fracture of the fibula 4 cm above the plafond nor disruption of the syndesmosis to 6.0 cm resulted in a significant change in coupled motion of the talus. When the superficial deltoid was sectioned, the ankle had increased external rotation in plantar flexion. When the deep deltoid was sectioned, the ankle dislocated in plantar flexion unless the fibula was stabilized. This prevented dislocation but failed to restore normal talar kinematics. This study found no biomechanical support for placement of a syndesmotic screw unless the medial side cannot be stabilized anatomically.

Ankle fracture classification systems: a case for integration of the Lauge-Hansen and AO-Danis-Weber schemes.

The two dominant classification systems for ankle fractures in use are the Lauge-Hansen and AO-Danis-Weber schemes. Each has certain advantages and disadvantages. Because of basic similarities, integration of these systems into one scheme involving three basic patterns with appropriate staging appears to be reasonable. This integration is based upon combining the pronation-abduction and pronation-external rotation injuries in Lauge-Hansen's scheme into one pronation-abduction-external rotation pattern. The resultant system would appear attractive in terms of combining relative simplicity with completeness.