Current Concepts in Ankle Fracture Management.

Ankle fractures are one of the more common musculoskeletal injuries that are treated by foot and ankle specialists. A thorough understanding of managing these injuries requires the ability to differentiate between stable and unstable fractures. The current literature supports the nonoperative management of stable Weber B ankle fractures, whereas unstable fractures have much better outcomes with surgical intervention. Specifically, we review the fixation strategies for the lateral, medial, and posterior malleolar fractures respectively. Finally, we discuss the current trends in postoperative management of some of the more common fracture patterns, and the safety in early weight-bearing protocols.

A novel classification of lateral malleolus morphological characteristics based on three-dimensional computed tomography reconstruction.

BACKGROUND: The study was to establish a novel classification of the morphological characteristics of fibula anterior-inferior margin (FAIM), which was reported in few studies. METHODS: The 501 images with three-dimensional computed tomography (3D CT) reconstruction were reviewed retrospectively. The width, height, thickness, long axis, short axis, and lateral malleolus angle were measured. RESULTS: The FAIM was divided into Angular, Flat, and Arc. The Flat has no distinct fibular obscure tubercles (FOT). The short axis of Angular and Arc were more significant than the Flat (P < 0. 05). The height of left was larger than the right, but short axis was less than it (P < 0.05). The height and short axis of males were larger than the females (P < 0.05). CONCLUSIONS: A novel classification (the Angular, Flat and Arc) of FAIM was identified based on lateral malleolus morphology, and it suggested that not all have obvious FOT. LEVEL OF EVIDENCE: Level Ⅲ, retrospective study.

Displaced Distal Fibular Epiphysis in a Child: A Clinical and Radiological Evaluation of a Rare Injury Hidden From the Initial Radiological Examination.

Fractures of the lateral malleolus are common in children. Isolated lesions of the distal fibula physis commonly comprise nondisplaced or minimally displaced fractures. An isolated, completely displaced epiphysiolisthesis of the distal fibula is an extremely rare lesion. This study introduces the case of an 11-year-old boy presenting an extremely rare lesion of an isolated, completely displaced distal fibular epiphysis that was difficult to diagnose on X-ray. Initial radiographic examination of the injured ankle showed normal configuration of the tibia and fibula on AP projection, with soft tissue swelling of the lateral malleolus. On the lateral projection, the talus completely covered the distal fibular epiphysis, and particular attention was required to reveal the complete displacement of the distal fibular epiphysis. A CT scan confirmed the diagnosis of an isolated, completely displaced distal fibular epiphysiolisthesis. The patient was treated with a closed reduction and made an uneventful recovery. This report highlights the importance of accurate clinical and radiological assessment of an isolated, completely displaced, distal fibular epiphysiolisthesis.

[Effectiveness comparison of a new hook-shaped anatomical locking plate and conventional anatomical locking plate in treatment of Danis-Weber type A lateral malleolus fractures].

Objective: To investigate the effectiveness of a new hook-shaped anatomical locking plate in the treatment of Danis-Weber type A lateral malleolus fractures. Methods: A retrospective analysis was performed on the clinical data of 45 patients with Danis-Weber type A lateral malleolus fractures who met the selection criteria between November 2020 and November 2022. According to the surgical methods, they were divided into the observation group (treated with the new hook-shaped anatomical locking plate, 23 cases) and the control group (treated with the conventional lateral malleolus anatomical locking plate, 22 cases). There was no significant difference in baseline data such as gender, age, cause of injury, Danis-Weber type of fracture, time from injury to operation, and combined ligament injury between the two groups ( P>0.05). The operation time, partial weight-bearing time, return to work time, and postoperative complications were recorded and compared between the two groups. The function and pain of ankle joint were evaluated by the range of motion of ankle dorsiflexion, plantarflexion, varus, valgus, and visual analogue scale (VAS) score at 1 and 3 months after operation, and at last follow-up, and the American Orthopaedic Foot and Ankle Society (AOFAS) score at 3 months after operation and at last follow-up. Results: All patients were followed up 10-18 months (mean, 15.1 months). There was no significant difference in operation time between the two groups ( P>0.05); the postoperative partial weight-bearing time and return to work time of the observation group were significantly earlier than those of the control group ( P<0.05). During the follow-up, there was 1 case of joint stiffness in the observation group, and 1 case of joint surface displacement, 1 case of joint stiffness, and 1 case of traumatic arthritis in the control group. There was no significant difference in the incidences of complications between the two groups ( P>0.05). With the extension of time after operation, the range of motion of ankle dorsiflexion, plantarflexion, varus, valgus, and VAS score of the two groups gradually improved, and there were significant differences between different time points ( P<0.05); At 1 and 3 months after operation, the above indexes in the observation group were significantly better than those in the control group ( P<0.05), and there was no significant difference between the two groups at last follow-up ( P>0.05). The difference of AOFAS score between the last follow-up and 3 months after operation in the observation group was significantly better than that in the control group ( P<0.05). Conclusion: Compared with the conventional lateral malleolus anatomical locking plate, the new hook-shaped anatomical locking plate has a more reliable fixation effect in the treatment of Danis-Weber type A lateral malleolus fracture, which is conducive to early functional exercise of the ankle joint, so that patients can bear weight earlier and return to work earlier, and the operation time is not significantly prolonged, and the effectiveness is satisfactory.

Anatomical considerations of the sural nerve in the distal leg: Side branch patterns and significance in nerve harvesting procedures.

BACKGROUND: The sural nerve is a somatosensory nerve that provides sensation to the posterolateral aspect of the lower leg and the lateral part of the ankle and foot. Due to its location and anatomical properties, it is often used as an autologous nerve graft. However, the nerve harvest can be complicated by the presence of side branches. The objective of this study was to investigate the anatomy of the sural nerve and to map its side branches. This information can be used to predict the localization of separate incisions during the stair-step incisions technique for nerve harvest, thereby reducing the risk of complications. METHODS: The study involved the dissection of 50 adult cadaveric legs (25 left and 25 right) obtained from 27 Central European cadavers. The focus of the dissection was to identify the sural nerve, small saphenous vein, and surrounding anatomical structures. Detailed measurements were taken on the side branches of the sural nerve, tributaries of the small saphenous vein, and their interrelationship. RESULTS: The average number of sural nerve side branches in a single leg was 4.2±1.9. These side branches were categorized into six groups based on their location and course: mediodistal, medioproximal, lateroproximal, laterodistal, medial perpendicular, and lateral perpendicular. Specific patterns of combination of these side branches were also identified and described. The branching point of the sural nerve was found to be 5.8±2.7 cm proximal to the lateral malleolus, whereas the small saphenous vein branching point was located more distally, 4.5 ± 2.8 cm proximal to the lateral malleolus. The highest density of sural nerve side branches was found 2.1-6.0 cm above the lateral malleolus. CONCLUSION: This study presents valuable data about the relationship between the sural nerve and the surrounding anatomical structures in the distal part of the leg, including the identification of its side branches and their relevance during nerve harvest procedures. On the basis of the most frequent locations of side branches, a three-incision-technique for nerve harvest is proposed.

Residual Medial Ankle Pain After the Delayed Union of a Lateral Malleolus Fracture: A Case Report.

A 17-year-old girl sprained her left ankle and was diagnosed with a lateral malleolar fracture. She was treated conservatively for six months but had medial ankle pain with activity. Imaging revealed an oblique lateral malleolar fracture, with posterolateral displacement and partial fusion of the bone fragments, and bone marrow edema on the medial articular surface of the talus and medial malleolus. We diagnosed ankle instability due to delayed union with a displacement of the lateral malleolus, which caused an osteochondral lesion. We performed arthroscopic and open surgery eight months after the injury, reducted the lateral malleolus anatomically, and fixed it with a plate. Postoperatively, the pain improved rapidly, and the bone marrow edema had almost disappeared on an MRI. In this case, we think rotational instability of the ankle mortise caused abnormal pressure and continuous stress on the medial malleolus after injury, which may have contributed to persistent medial ankle pain.

Use of Fibula Nails With Proximal and Distal Fixation.

Background: Ankle fractures are a frequent injury in the adult population and a quarter of all ankle fractures are classified as unstable, requiring surgical intervention. Plate-and-screw construct is the traditionally used fixation method for fibula fractures. The use of an intramedullary nail is an alternative fixation method, with current literature supporting very low complication rates and hardware removal surgeries. The purpose of this study was to evaluate the outcomes, including complication rates and implant removal rates, using a fibula nail with both proximal and distal fixation capabilities by an experienced surgeon. Methods: We retrospectively reviewed 203 consecutive fibula nail cases from a single surgeon using a mini-open technique for anatomic reduction. Demographic, operative, clinical, and radiographic outcome data were analyzed, specifically examining complication rates and need for implant removal. Results: The average follow-up was 18.8 months (6-54 months). All fractures healed. We identified 2 cases of superficial wound infection, 1 superficial peroneal nerve irritation, and 1 case of implant removal. In the first 110 cases, 2 fractures were converted to a plate intraoperatively prior to a technique modification which has prevented this occurrence. No deep infection, delayed union, or nonunion occurred. Conclusion: Our data support that fibula nails with proximal and distal locking capabilities offer an alternative to plating with the potential for lower complication rates and lower need for implant removal. Level of evidence: Level IV, case series.

A comparison of outcomes of locking versus non-locking plate fixation for the distal fibula fractures: a systematic review and meta-analysis.

PURPOSE: A locking plate (LP) or non-locking plate (NLP) can be used for distal fibula fracture fixation. However, the advantages of LP over NLP in patients with distal fibula fractures are not clear. In terms of indications, the role of the two plates probably differs; however, to draw comparative conclusions, we conceptualized this systematic review and meta-analysis of studies that directly compared the two plates, wherein both groups' indications and baseline parameters were similar. METHODS: An electronic literature search was performed using PubMed/Medline, Embase, Scopus, and Cochrane Library databases for studies comparing the LP versus NLP fixation for the lateral malleolus fracture. A total of 18 studies were included in qualitative and quantitative analysis. A subgroup analysis was performed for patients aged < 55 years and patients aged > 55 years. The statistical analysis was performed by Review Manager Software version 5.4.1. RESULTS: A meta-analysis of 4243 fractures was performed across 18 studies. The rate of fracture union and overall complication rates did not differ between the two fixation groups with an OR of 0.71 (95% CI 0.26, 1.96, p = 0.51 and 1.11 (95% CI 0.84, 1.47, p = 0.47, respectively. There is no difference in the reoperation rate due to minor or major complications between the two groups. There was no difference in functional outcome (MD -0.85, with 95% CI -5.63, 3.93, p = 0.73), but NLP has a shorter surgical duration (MD 3.0, with 95% CI 0.26, 5.75, p = 0.03). A leave-one-out sensitivity analysis performed for overall complications affected the final outcome of the meta-analysis. CONCLUSION: This meta-analysis demonstrates no clear benefit in selecting LP over NLP for the fixation of lateral malleolus fractures.

Factors and Radiographic Findings Influencing Patient-Reported Outcomes Following Maisonneuve Fractures.

BACKGROUND: This research adds to the literature by providing prognostic information for physicians and patients regarding the outcomes of operative management of Maisonneuve fractures (MFs). To date, this is the only cohort study of patient-reported outcomes measurement information systems (PROMIS) scores following surgical fixation of MF. Patient outcomes were compared focusing on the mean population with an inter-analysis using basic demographic information, radiographic findings, and patient comorbidities and their respective impact on PROMIS scores. METHODS: A total of 24 patients between 2012 and 2020 met the inclusion criteria and completed PROMIS surveys at a minimum of 18 months postoperatively. Patient charts were reviewed through the electronic medical record (EMR) for demographic information and comorbidities as well as operative variables. PROMIS scores for physical function (PF), pain interference (PI), and depression were obtained via follow-up visits and phone calls. The impact of categorical variables on complications was compared using Chi-Squared tests. Variables were analyzed with a type 3 SS test to stratify independent risk factors' effect on PROMIS scores and to account for confounding variables. RESULTS: PROMIS PF averaged 44.84 and was significantly affected by BMI>30 (p=.033), hypertension (HTN) (p=.026), patients with clinical anxiety or depression (p=.047), and subsequent screw removal (p=.041). PROMIS PI averaged a score of 54.57 and was significantly affected by BMI>30 (p=.0046), coronary artery disease (CAD) (p=.0123), patients with clinical anxiety or depression (p=.0206), and subsequent screw removal (p=.0039). PROMIS depression scores averaged 46.03 and were significantly affected by the presence of CAD (p=.049) and subsequent screw removal (p=.023). CONCLUSION: Patient-reported outcomes following MF surgery demonstrated PROMIS scores within +/- 1 standard deviation of the population-based control, and thus many patients can reasonably expect to return to a level of function comparable to the general population. Nonetheless, the significant effects of patient comorbidities and surgical variables ought to be evaluated and utilized as prognostic indicators when managing patient expectations prior to operative treatment of an MF injury.

Does Screw Order Matter? A Technique Tip to Prevent Loss of Fracture Reduction during Surgical Fixation of Lateral Malleolus Fractures.

When obtaining surgical fixation of lateral malleolus fractures, a cortical lag screw is commonly used to obtain anatomic reduction. Subsequently, a neutralization plate is applied. Slight loss of fracture reduction after plate placement occasionally occurs. Although this is frequently attributed to poor bone quality or suboptimal initial lag screw fixation, a frequently overlooked factor is screw order when applying the neutralization plate. The purpose of this technique tip is to highlight the biomechanical rationale behind this loss of reduction and advocate a specific screw order for lateral malleolus fixation.

The distal fibular perforating axial flap for lateral malleolus coverage: an anatomical description and surgical technique.

PURPOSE: Skin closure disorders in ankle surgery are a recurrent problem not only in traumatology but also in elective surgery. The aim of the study was to describe the anatomical basis of the fasciocutaneous vascularization of the lateral malleolus region to develop a posterior cover flap for the region. METHODS: We dissected ten fresh frozen specimens after arterial injection of an Indian ink preparation and individualized the perforating arteries. Their positions and diameters were collated. Then, the surgical technique was clinically applied for two different cases by transferring the fasciocutaneous flap posterior to the lateral malleolus to cover a loss of skin substance. RESULTS: There were in average 5 fibular perforators over the last 100 mm of the fibula. The average diameter of the first two perforating arteries was 0.6 ± 0.12 mm and 0.9 ± 0.25 mm, respectively, and the consistency of the latter makes it possible to produce a skin flap with anterior translation. This is an axial flap. Two patients were operated on using this technique. There was no necrosis of the posterior fibular flap and healing was achieved by the third post-operative week. CONCLUSION: This study showed the presence of fibular perforating arteries with a high reproducibility of their dissection. This anatomical description served as the basis for the description of a new distal fibular perforating flap.

Indications and Interpretation of Stress Radiographs in Supination External Rotation Ankle Fractures.

Introduction In supination external rotation (SER) ankle fractures with an intact medial malleolus, stability hinges upon the competence of the deltoid ligament. The purpose of this study is to define the indications and establish criteria for a positive stress radiograph. Methods This is a prospective study of 27 isolated SER lateral malleolar fractures with a reduced ankle mortise. Pain and swelling were noted about the medial ankle, followed by an ultrasound to evaluate the integrity of the deltoid ligament. Static and stress radiographs were performed on both the fractured and contralateral ankles. Results Fourteen patients were normal on ultrasound examination, eight had partial tears, and five had full-thickness tears. The difference in the level of pain to palpation postero-medially between the complete tear (7 +/- 1) and the partial tear (1.3 +/- 2.4) group was significant (p < .001). The negative predictive values for medial swelling and tenderness were 93% and 100%, respectively. Sensitivity and specificity for medial clear space on stress radiograph (fracture (fx)) > 5.0 mm were both 100% while a 2.5 mm or greater change to the contralateral side yielded a sensitivity of 100% and specificity of 95%. Conclusion The lack of significant medial pain, as well as swelling, implies the absence of a complete ligament tear and eliminates the need for stress examination. Conversely, the presence of medial signs of injury is suggestive, but not pathognomonic for a complete deltoid tear. Medial clear space (MCS) variability prompts to recommend a minimum of 2.5 mm on stress radiographs compared to the contralateral side as indirect evidence for a complete tear of the deltoid ligament.

Allogeneic tendons in the treatment of malunited lateral malleolar avulsion fractures with chronic lateral ankle instability.

BACKGROUND: The aim of this study is to report our institution's experience regarding the application of allogeneic tendons for the reconstruction of malunited lateral malleolar avulsion fractures with chronic lateral ankle instability. METHODS: This retrospective study included 34 (34 ankles) patients surgically treated for malunited lateral malleolar avulsion fractures with chronic lateral ankle instability from January 2016 to December 2019. All patients underwent allogeneic tendon reconstruction. The pre- and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) scores、Karlsson Ankle Functional Scores (KAFS) and visual analogue scale (VAS) scores were used to evaluate the functional recovery of the ankle joint. The final follow-up, based on radiographic assessment, including talar tilt and anterior talar translation, was performed to evaluate the stability of the postoperative ankle joints. RESULTS: Thirty-two patients (32 ankles) returned for final clinical and radiologic follow-up at an average of 29 (range 24-35) months and 2 patients (2 ankles) were lost to follow-up. The preoperative talus inclination angle (13.6 ± 1.9°) and anterior displacement (9.6 ± 2.8 mm) were re-examined under X-ray and found to be reduced to 3.4 ± 1.2° and 3.8 ± 1.1 mm, respectively (p＜0.01). The AOFAS scores increased from 58.5 ± 4.0 to 90.9 ± 3.8 and the Karlsson scores improved from 52.2 ± 3.6 to 89.8 ± 4.5, which was obviously better and the difference was statistically significant (P < 0.01). The VAS scores were significantly reduced from a preoperative mean of 6.8 ± 1.0 to 2.8 ± 0.9 postoperatively (p＜0.01). CONCLUSION: In this population and with this follow-up, the application of allogeneic tendons to treat malunited lateral malleolar avulsion fractures combined with chronic lateral ankle instability appeared safe and effective.

[Translated article] Relationship between low lying peroneus brevis muscle belly and peroneal tendons dislocation.

INTRODUCTION: Peroneal tendon pathologies are an important cause of pain in the lateral aspect of the ankle. It has been proposed in the literature that low lying peroneus brevis muscle belly occupies more space in the retromalleolar groove and could cause laxity of the superior retinaculum which would promote tendon dislocation, tenosynovitis or ruptures. The objective of the study is to characterise the population with low lying peroneus brevis muscle belly and determine the association between the low lying peroneus brevis muscle belly found on magnetic resonance imaging and clinical peroneal tendon dislocation. METHODS: A case-control study was developed with a sample of 103 patients. The cases were patients with low lying peroneus brevis muscle belly and peroneal dislocation and the controls were patients with normal implantation of the peroneus brevis muscle and peroneal tendon dislocation. RESULTS: The prevalence of clinical peroneal dislocation in patients with low implantation of the peroneal brevis muscle belly was 7.64%, and the prevalence of clinical peroneal dislocation in patients with normal implantation of the peroneus brevis muscle belly was 8.88%. The OR was 0.85 (CI 0.09-7.44, p=0.88). DISCUSSION: Our findings indicate that there is no statistically significant relationship between low lying peroneus brevis muscle belly and clinical dislocation of the peroneal tendons.

Lateral malleolar crest and its clinical importance.

PURPOSE: During study of anatomy of a fractured posterior malleolus of the ankle on CT scans, the authors noticed a prominent crest on the lateral malleolus, which they termed the lateral malleolar crest (LMC). As, in their view, LMC is a clinically important structure which was only briefly mentioned by a few authors without an official term, they focused on the anatomy of this structure. MATERIALS AND METHODS: A total of 352 dry fibulae were analyzed and the following parameters recorded: (F) length of the fibula, (LMC) total length of LMC, (A) length of the part of the examined crest from the superior border of the articular facet of the lateral malleolus (AFLM) to its most proximal intersection with the midline of the fibula, (B) height of the medial triangular rough surface, and (A/F) A/F ratio. RESULTS: The crest was observed in all specimens. (F) was 346.5 ± 26 mm (95% confidence interval [CI] 344-349), (LMC) was 85.4 ± 11.6 mm (95% CI 84.2-86.6), (A/F) was 25% ± 3% (95% CI 24.7-25.3) in the whole group. (A) was 25.9 ± 6.5 mm (95% CI 24.8-26.8) in the whole group, (B) was 34.9 ± 4.7 mm (95% CI 34.3-35.5) in the whole group, 36 ± 6.1 mm (95% CI 35.1-36.9). CONCLUSION: LMC is an important structure on the lateral malleolus. The knowledge of its anatomy is essential for placement of syndesmotic screws or/and the fibular plate.

Clinical Application of the Peroneal Artery Perforator Flap for Reconstruction of Lateral Malleolus Defects.

The reconstruction of defects of the lateral malleolus involving the exposed fibular bone or tendon is challenging. This study aimed to evaluate the clinical application of the peroneal artery perforator flap with or without split-thickness skin grafting for soft tissue reconstruction of the bony defect of the lateral malleolus of the ankle joints. Reconstruction using a peroneal artery perforator flap with or without split-thickness skin grafting was performed for 15 patients (10 men, 5 women) between January 2007 and December 2018. The mean age was 53.7 years, and the mean size of the flaps was 40 cm2. The flaps were elevated in the form of a perforator flap, and split-thickness skin grafting was performed over the flaps and adjoining raw areas. The flaps survived in all cases; however, partial necrosis was observed in 3 cases. In cases of small-sized defects of the lateral malleolus of the ankle joints where a flap is required for the exposed bone or tendon, reconstruction using the peroneal artery perforator flap is advantageous, since the morbidity rate of the donor site is low and soft tissue is reconstructed.

Relationship between low lying peroneus brevis muscle belly and peroneal tendons dislocation. / Relación entre implantación baja del vientre muscular del peroneo corto y luxación de los tendones peroneos.

INTRODUCTION: Peroneal tendon pathologies are an important cause of pain in the lateral aspect of the ankle. It has been proposed in the literature that low lying peroneus brevis muscle belly occupies more space in the retromalleolar groove and could cause laxity of the superior retinaculum which would promote tendon dislocation, tenosynovitis or ruptures. The objective of the study is to characterize the population with low lying peroneus brevis muscle belly and determine the association between the low lying peroneus brevis muscle belly found on magnetic resonance imaging and clinical peroneal tendon dislocation. METHODS: A case-control study was developed with a sample of 103 patients. The cases were patients with low lying peroneus brevis muscle belly and peroneal dislocation and the controls were patients with normal implantation of the peroneus brevis muscle and peroneal tendon dislocation. RESULTS: The prevalence of clinical peroneal dislocation in patients with low implantation of the peroneal brevis muscle belly was 7.64%, and the prevalence of clinical peroneal dislocation in patients with normal implantation of the peroneus brevis muscle belly was 8.88%. The OR was 0.85 (CI 0.09-7.44, P=0.88). DISCUSSION: Our findings indicate that there is no statistically significant relationship between low lying peroneus brevis muscle belly and clinical dislocation of the peroneal tendons.

Can CT-based assessment of lateral malleolus anatomy indicate when and how to perform an intramedullary fixation in distal fibula fractures? An analysis of 150 ankles.

PURPOSE: The primary aim was to analyse the lateral malleolus morphology with a focus on the shape of the distal fibula for IM fixation of the fibula in infra- and transsyndesmotic fracture patterns. The secondary aim was to propose a treatment algorithm according to the lateral malleolar anatomy. METHODS: 77 healthy, skeletally mature volunteers underwent CT scanning of the ankle. The fibula medullary canal and its cortical thickness were quantitatively analysed at 4 different levels measured from the fibular tip (1.5 cm, 3.0 cm, 4.5 cm, and 6.0 cm). A geometric classification was proposed, and a decision algorithm was developed. Statistical significance was set at a p-value < 0.05. RESULTS: The smallest diameter of the medullary canal of the fibula was at 6.0 cm from the tip of the fibula, in 98.2% of the ankles. The distal fibula can be classified into triangular and rectangular type, according to the cortical thickness index (p < 0.0001). In 16.7% ankles, the internal diameter of the fibula at 6.0 cm was equal or narrower than 3.5 mm (p < 0.05). CONCLUSION: The shape of the distal fibula as evaluated by CT-guided analysis allows for IM osteosynthesis of the lateral malleolus in 83% of individuals. In our study, the smallest diameter of the medullary canal of the fibula was located 6.0 cm from the tip of the lateral malleolus. Coronal CT evaluation is advantageous in indicating which type of IM implant should be used safely for infra- and transsyndesmotic fracture patterns, potentially reducing intraoperative risks.

Development and external validation of automated detection, classification, and localization of ankle fractures: inside the black box of a convolutional neural network (CNN).

PURPOSE: Convolutional neural networks (CNNs) are increasingly being developed for automated fracture detection in orthopaedic trauma surgery. Studies to date, however, are limited to providing classification based on the entire image-and only produce heatmaps for approximate fracture localization instead of delineating exact fracture morphology. Therefore, we aimed to answer (1) what is the performance of a CNN that detects, classifies, localizes, and segments an ankle fracture, and (2) would this be externally valid? METHODS: The training set included 326 isolated fibula fractures and 423 non-fracture radiographs. The Detectron2 implementation of the Mask R-CNN was trained with labelled and annotated radiographs. The internal validation (or 'test set') and external validation sets consisted of 300 and 334 radiographs, respectively. Consensus agreement between three experienced fellowship-trained trauma surgeons was defined as the ground truth label. Diagnostic accuracy and area under the receiver operator characteristic curve (AUC) were used to assess classification performance. The Intersection over Union (IoU) was used to quantify accuracy of the segmentation predictions by the CNN, where a value of 0.5 is generally considered an adequate segmentation. RESULTS: The final CNN was able to classify fibula fractures according to four classes (Danis-Weber A, B, C and No Fracture) with AUC values ranging from 0.93 to 0.99. Diagnostic accuracy was 89% on the test set with average sensitivity of 89% and specificity of 96%. External validity was 89-90% accurate on a set of radiographs from a different hospital. Accuracies/AUCs observed were 100/0.99 for the 'No Fracture' class, 92/0.99 for 'Weber B', 88/0.93 for 'Weber C', and 76/0.97 for 'Weber A'. For the fracture bounding box prediction by the CNN, a mean IoU of 0.65 (SD ± 0.16) was observed. The fracture segmentation predictions by the CNN resulted in a mean IoU of 0.47 (SD ± 0.17). CONCLUSIONS: This study presents a look into the 'black box' of CNNs and represents the first automated delineation (segmentation) of fracture lines on (ankle) radiographs. The AUC values presented in this paper indicate good discriminatory capability of the CNN and substantiate further study of CNNs in detecting and classifying ankle fractures. LEVEL OF EVIDENCE: II, Diagnostic imaging study.

Screw-only fibular construct for Weber B ankle fractures: A retrospective clinical and cost comparison to assess feasibility for resource-limited settings.

INTRODUCTION: Ankle fractures are one of the most common injuries sustained worldwide, with the majority being isolated lateral malleolus fractures. The majority of the world's population live in Low and Middle Income Countries (LMIC), where implant cost may limit surgical treatment of ankle fractures. We investigate if Weber B ankle fractures could be effectively treated with a lower-cost technique using two screws between the fibula and the tibia to neutralize an interfragmentary lag screw. METHODS: After IRB approval, consecutive patients from January 1, 2020 to December 31, 2020 with Weber-B ankle fractures were treated using AO technique (AOT) with plate osteosynthesis neutralizing an interfragmentary screw. Syndesmotic injuries, as well as injuries to the medial malleolus or foot were treated according to the surgeon's preferences. From January 1, 2021 to December 31, 2021 these injuries were treated with a screw-only technique (SOT) with two fibula pro tibia screws to neutralize an interfragmentary screw. Patient demographics including age, sex, BMI, smoking status, associated rheumatoid arthritis, and associated diabetes mellitus were recorded. The primary outcome variable was a stable radiographic mortise at six weeks post-surgery, secondary outcome variables included clinical union, infection, hardware removal, and implant cost for lateral malleolar fixation charged to the hospital. RESULTS: Seventeen AOT and 10 SOT constructs were included. Demographic characteristics were similar between groups. All fractures maintained a stable mortise with clinical union at 6 weeks without infection. There was a statistically significant difference in hardware removal (17.6% AOT, 50% SOT, p = 0.012). The average implant cost to the hospital of the lateral malleolar fixation was significantly less in the SOT group ($592 (SD $229)), compared to the AOT group ($1,949.97 (SD $562)), (p < 0.0001). CONCLUSION: We introduce proof of concept of a novel lower-cost fixation strategy for Weber B ankle fractures that maintained a stable mortise with clinical union at six weeks post-surgery. However, there was a significantly higher rate of hardware removal following fixation with a screw-only construct.