Establishment of a Finite Element Model of Supination-external Rotation Ankle Joint Injury and Analysis of Mechanical Changes in the Posterior Malleolar Surface

BackgroundBy establishing a three-dimensional finite element model of supination and external rotation ankle injury, the stress characteristics of the posterior ankle joint surface can be obtained, and complete analysis of the corresponding stress on the lateral ankle can be examined. MethodsThin-layer computed tomography (CT) images of normal ankle joints in the supination and external rotation non-weight-bearing states were selected, a three-dimensional data model of each ankle joint, including the ligament, was established, and whether different degrees of injury were coexistent with lateral ankle fracture was analysed by the finite element method. A load was applied to examine different ankle joint stress values and pressure distributions on the surface of the posterior ankle joint. ResultsWhen a load was applied, the maximum stress was located at the point of attachment of the anterior tibiofibular ligament to the tibia. When the anterior tibiofibular ligament was removed and the lateral malleolus was intact, the maximum stress (271.2 MPa) was located at the attachment point of the posterior tibiofibular ligament to the tibia, and the maximum pressure of the posterior ankle joint surface was 2.626 MPa. When a lateral malleolus fracture was present and the same load was applied, the maximum stress (82 MPa) was located on the fibular fracture surface, and the maximum pressure of the posterior ankle joint surface was 7.787 MPa. The posterior tibiofibular ligament was then removed completely from the lateral malleolus, and the maximum stress (132.7 MPa) was located at the point of attachment of the posterior tibiofibular ligament to the fibula, and the maximum pressure of the posterior ankle joint surface was 4.505 MPa. When a lateral malleolar fracture was present, the maximum stress (82.72 MPa) was located on the fibular fracture surface, and the maximum pressure of the posterior ankle joint surface was 8.022 MPa. ConclusionThis study shows that reconstruction of the lateral malleolus in supination-external rotation ankle injury significantly affects the stress distribution at the posterior malleolar joint surface. When reconstruction of the lateral malleolus is complete, the pressure distribution of the posterior malleolar joint surface can be significantly reduced. The results highlight the significance of reconstruction of posterior malleolar fractures and posterior tibiofibular ligament stability.

Lateral Trans-Malleolar Approach for Posterior Malleolar Fractures of the Ankle for Articular and Syndesmosis Reduction : A Retrospective Study

Background The lateral transmalleolar approach (LTA) is a surgical approach for posterior malleolar fractures (PMFs), providing direct visualization of the articular surface of the posterior malleolus, though temporarily disrupting the syndesmosis. However, it is still unclear whether this fibrous joint can be effectively reconstructed afterward to prevent complications. We report the clinical results and computed tomography (CT) findings for articular and syndesmosis reduction status after surgery with LTA for PMF. Methods Sixteen patients who underwent PMF reduction with LTA and were followed up for at least 1 year were evaluated retrospectively. According to the AO/OTA classification, the fracture type was type 44B in 13 patients and 44C in three patients. The Haraguchi classifications of PMF were type 1 in six cases and type 2 in 10 cases. The American Orthopedic Foot and Ankle Society Ankle-Hindfoot Scale (AOFAS) score, post-surgical complications, and reduction status of PMF and syndesmosis on CT were investigated. Results The mean AOFAS score was 93.0 ± 5.2 points. Post-operative complications were observed in one case of superficial infection and one case of delayed fibular union. The articular step-off seen on CT improved significantly after surgery (5.9 ± 2.9 mm preoperatively vs. 0.6 ± 0.8 mm post-operatively). Syndesmosis malreduction was seen in three cases, including two high fibular fractures and one comminuted fibular fracture with osteoporosis. Conclusions The LTA provided favourable clinical results and effective reduction of intra-articular PMFs. However, surgeons should be aware of the possibility of syndesmosis malreduction in cases of high fibular fractures or comminuted fibular fractures.

Characteristics of supination-external rotation Salter-Harris II ankle fractures in computed tomography

Background: Recent literature has shown that Salter-Harris (S-H)Ⅱfractures are the most common ankle fractures and carry a higher rate of growth disturbance. Recent literature has shown that Salter-Harris (S-H) Ⅱ fractures are the most common ankle fractures. CT characteristics of S-H Ⅱ ankle fractures are not well depicted. The purpose of this study was to evaluate supination-external rotation (SER) S-HⅡankle fractures by CT and to analyze the features of the associated fibular fracture to further determine the injury mechanism.Methods: The radiographs and CT with S-H Ⅱankle fractures were reviewed. Patients suffered from SER injury were included. The medial tibial cortex (MTC) of the distal tibia broken or intact, the metaphyseal fracture angle (MFA) 5-10mm proximal to the physis was documented in axial CT. The length of the metaphyseal fragment was measured in saggital CT. The correlation of the upper limits between fibular fracture and metaphyseal fragment was analyzed. In presence of the fibular fracture, the fracture pattern was classified based on the location and morphology of the fracture line.Results: Seventy-nine SER S-HⅡankle fractures were identified. Stage 1 was present in 35 and stage 2 in 44. In axial CT, the mean MFA was 11.2 degrees. MTC was fully broken in one case and 20, in stage 1 and stage 2, respectively (P=0.001). In saggital CT, the mean length of metaphyseal fragment was 35.3mm. The length of this fragment was 35.0mm, 35.5mm, in stage 1 and stage 2, respectively (P=0.868). The upper part of the fibular fracture line was located at the same level or higher than that of metaphyseal fragment. In 44 cases with associated fibular fracture, forty were in distal metaphysis with oblique fracture line for which 4 types were demonstrated with plantar flexion. Other 4 were in distal diaphysis with spiral fracture line.Conclusions: For SER S-H Ⅱ ankle fractures, MTC and orientation of the fracture plane can be shown in CT to help to make an appropriate preoperative plan. In addition to SER, majority of the concurrent fibular fracture was in the distal metaphysis with oblique fracture line and plantar flexion.

Effects of Ketamine Analgesia on Cardiorespiratory Responses and Survival to Trauma and Hemorrhage in Rats

Ketamine is the recommended analgesic on the battlefield for Soldiers with hemorrhage, despite a lack of supportive evidence from laboratory or clinical studies. Hence, this study determined the effects of ketamine analgesia on cardiorespiratory responses and survival to moderate (37% blood volume; n=8/group) or severe hemorrhage (50% blood volume; n=10/group) after trauma in rats. We used a conscious hemorrhage model with extremity trauma (fibular fracture + soft tissue injury) while measuring mean arterial pressure (MAP), heart rate (HR), and body temperature (Tb) by telemetry, and respiration rate (RR), minute volume (MV), and tidal volume (TV) via whole body plethysmography . Male rats received saline (S) or 5.0 mg/kg ketamine (K) (100 µl/100 gram body weight) intra-arterially after trauma and hemorrhage. All rats survived 37% hemorrhage. For 50% hemorrhage, neither survival times (180 min (SD 78) vs 209 min (SD 66) nor percent survival (60% vs 80%) differed between S and K-treated rats. After 37% hemorrhage, K (compared with S) increased MAP, and decreased Tb and MV. After 50% hemorrhage, K (compared with S) increased MAP but decreased HR and MV. K effects on cardiorespiratory function were time-dependent, significant but modest, and transient at the analgesic dose given. K effects on Tb were also significant but modest, and more prolonged. Using this rat model, our data support the use of K as an analgesic in injured, hypovolemic patients.

P109 Sherlock Holmes in Clinical Practice: The Deduction of the Pattern and Mechanism of Injury in Ankle Fractures Using Lauge-Hansen System

Introduction Ankle fractures are among the commonest fractures in adults and as population ages, the incidence is also increasing. It is crucial to ascertain the mechanism of injury of an ankle fracture as it determines the management plan. The diagnosis and management of ankle fractures are usually relatively straightforward but they are not always the case. Most patients are unable to recall the exact mechanism of injury due to the instantaneous nature of incident. We herein describe a case report of a patient who sustained an ankle fracture following a fall but was unable to recall the exact mechanisms of injury. This case report addresses the importance of recognising Maisonneuve fractures and how Lauge-Hansen Classification system might be useful in diagnosing and making management plans for ankle fractures. Case Report A 30-year-old male self-presented to the Emergency Department in a wheelchair following a fall. He tripped down the last four steps of stairs the night before, sustaining a right ankle injury as a result. He has been unable to weight-bear since. Elevation and application of ice packs have showed limited effect. Patient was unable to recall the exact mechanism of injury. On examination, the right ankle was swollen and there were bruises around the medial malleolus. Upon palpation, he complained of bony tenderness around lateral and medial malleoli. No other injury was found and patient was neurovascularly intact. A referral was made to the Orthopaedics team and further orthopaedic examinations revealed tenderness and crepitus upon palpation over the proximal fibula. Full lower leg X-rays was ordered to look for possible proximal fibula fracture. A diagnosis of closed, Maisonneuve (Weber C)/trimalleolar fracture of the right ankle was made. A CT-scan of the right ankle was requested to determine the involvement of joint surface to aid surgical planning. Both CT-scan and ankle X-rays showed disrupted syndesmosis. Disrupted syndesmosis is most commonly associated with Weber C fractures as shown in this case. Since the fibular fracture is greater than 4.5cm away from the tibial plafond, syndesmosis fixation is required. In Maisonneuve fractures, syndesmotic screws can be used to achieve anatomical reduction and ankle stability. This patient was scheduled for an ORIF surgery. Discussions Based on the findings of medial and posterior malleoli fractures from the ankle X-rays, we can deduce that the patient has most likely sustained a complete Pronation-External Rotation (PER) injury. A Maisonneuve fracture was almost missed initially due to distracting injuries and not obtaining full lower leg X-rays. However, based on Lauge-Hansen Classification, we know that it is highly unlikely to have a posterior malleolus fracture (Stage 4) without any fibular fracture (Stage 3). Hence, a full-fibula X-ray was ordered to look for proximal fibula fracture and the X-rays revealed a spiral fracture at the proximal fibula (Maisonneuve fracture). The injury force was transmitted along the interosseous membrane and exited at the shaft of proximal fibula, causing a proximal fibular fracture. PER or injury sustained from an internally rotated leg on a planted foot may cause external rotation injury, resulting in a disruption of the ligaments. The syndesmosis, which provides primary support to the ankle, if disrupted, will disrupt the ankle mortise, displacing the fibula laterally, as demonstrated in this case. Conclusion As demonstrated in this case, some fractures, like the Maisonneuve fracture, can easily be missed. Due to distracting injuries, the chief complain in most cases of Maisonneuve fracture is severe ankle pain instead of the fracture site at proximal fibula. These fractures, if not identified early, can lead to poor prognosis. It is important to consider Maisonneuve fracture in all ankle injuries. A delayed diagnosis can lead to post-traumatic arthritis and pain, leading to loss of function. This case report addresses the importance of recognising easily missed fractures and how Lauge- Hansen Classification system is useful in aiding the diagnosis and management of ankle fracture

Acute presentation of a proximal fibular stress fracture after a total knee arthroplasty

A 67-year-old woman underwent a routine and uneventful elective total knee arthroplasty for osteoarthritis at our centre. No intraoperative nor immediate postoperative complications were noted clinically nor radiologically. At 5 weeks postoperative, she began to notice some new discomfort in her upper calf area, with no preceding history of trauma. A Doppler ultrasound scan ruled out a deep vein thrombus. Only on further re-imaging of her knee with X-rays and CT was there shown to be a fibular fracture of the proximal third with evidence of callus formation. The pain arising from her stress fracture delayed her rehabilitation slightly, going on to require a successful manipulation under anaesthetic (0°–95°). She went on to have excellent function in her knee and the pain from the stress fracture had settled by 5 months.