Ligamentous restraints of the second tarsometatarsal joint: a biomechanical evaluation

Influence of the transverse tarsal arch on radiological components of progressive collapsing foot deformity

The importance of the transverse tarsal arch (TTA) has recently been extensively reevaluated and has even been considered to play a greater role in foot stability than the medial longitudinal arch (MLA). However, the relevance of this observation in the context of common clinical foot disorders, such as progressive collapsing foot deformity (PCFD), has not yet been fully clarified. In this biomechanical study, we examined ten pairs of human cadaveric feet by serial weight-bearing cone-beam computed tomography under controlled loading using a custom-designed testing machine. The MLA and TTA were transected separately, alternating the order in two study groups. A semiautomated three-dimensional evaluation of their influence on three components of PCFD, namely collapse of the longitudinal arch (sagittal Meary's angle), hindfoot alignment (sagittal talocalcaneal angle), and forefoot abduction (axial Meary's angle), was performed. Both arches had a relevant effect on collapse of the longitudinal arch, however the effect of transecting the MLA was stronger compared to the TTA (sagittal Meary's angle, 7.4° (95%CI 3.8° to 11.0°) vs. 3.2° (95%CI 0.5° to 5.9°); p = 0.021). Both arches had an equally pronounced effect on forefoot abduction (axial Meary's angle, 4.6° (95%CI 2.0° to 7.1°) vs. 3.0° (95%CI 0.6° to 5.3°); p = 0.239). Neither arch showed a consistent effect on hindfoot alignment. In conclusion, weakness of the TTA has a decisive influence on radiological components of PCFD, but not greater than that of the MLA. Our findings contribute to a deeper understanding and further development of treatment concepts for flatfoot disorders.

Nonoperative management of lisfranc injuries - A systematic review of outcomes

BACKGROUND

Historically, most Lisfranc injuries have been considered to be unstable and treated with surgical intervention. However, with better access to cross-sectional imaging, stable injury patterns are starting to be recognised. The aims of the current study were to perform a systematic review of outcomes of Lisfranc injuries treated non-operatively.

METHODS

A literature review was performed of studies reporting nonoperative management of Lisfranc injuries (PROSPERO registered and following PRISMA guidelines). Following exclusions, 8 papers were identified: 1 prospective and 7 retrospective studies. A total of 220 patients were studied with a mean age of 39.8 years and a mean follow-up of 4.3 years. Outcomes included function, displacement, and rates of surgery.

RESULTS

High heterogeneity was observed with variable outcomes. Four papers reported good outcomes, with adjusted functional scores ranging from 82.6 to 100 (out of 100). However, one study reported late displacement in 54 % of patients. Rates of secondary osteoarthritis ranged from 5 % to 38 %. Rates of surgical intervention were as high as 56 %. Several studies compared operative to non-operative treatment, reporting superior outcomes with surgery. Those injuries with no displacement on CT, measured at the medial cuneiform-second metatarsal had the best outcomes.

CONCLUSION

Reported outcomes following nonoperative treatment of Lisfranc injuries vary widely, including high rates of conversion to surgery. In contrast, some studies have reported excellent functional outcomes. CT seems to be an important diagnostic tool in defining a stable injury. Due to limited data and lack of a clear definition of a stable injury or treatment protocol, prospective research is needed to determine which Lisfranc injuries can be safely treated nonoperatively.

A computational model of force within the ligaments and tendons in progressive collapsing foot deformity

Progressive collapsing foot deformity results from degeneration of the ligaments and posterior tibial tendon (PTT). Our understanding of the relationship between their failures remains incomplete. We sought to improve this understanding through computational modeling of the forces in these soft tissues. The impact of PTT and ligament failures on force changes in the remaining ligaments was investigated by quantifying ligament force changes during simulated ligament and tendon cutting in a validated finite element model of the foot. The ability of the PTT to restore foot alignment was also evaluated by increasing the PTT force in a foot with attenuated ligaments and comparing the alignment angles to the intact foot. We found that failure of any one of the ligaments led to overloading the remaining ligaments, except for the plantar naviculocuneiform, first plantar tarsometatarsal, and spring ligaments, where removing one led to unloading the other two. The combined attenuation of the plantar fascia, long plantar, short plantar, and spring ligaments significantly overloaded the deltoid and talocalcaneal ligaments. Isolated PTT rupture had no effect on foot alignment but did increase the force in the deltoid and spring ligaments. Moreover, increasing the force within the PTT to 30% of body weight was effective at restoring foot alignment during quiet stance, primarily through reducing hindfoot valgus and forefoot abduction as opposed to improving arch collapse. Our findings suggest that early intervention might be used to prevent the progression of deformity. Moreover, strengthening the PTT through therapeutic exercise might improve its ability to restore foot alignment.

A Rare Case of a Lisfranc Ligament Transection

Ligamentous Lisfranc injuries, which mimic a surgical transection are rare. Left untreated or missed, these injuries may result in severe complications including long-term disability. The present case describes a unique mechanism of injury via a sharp object puncture through the plantar surface of the midfoot. It highlights the utility of planning staged procedures to remove a large foreign body object, reports notable intraoperative techniques, and provides a decision management guide for treating this type of injury. Extensive surgical planning may be required when encountering similar cases and knowledge of this may be useful to providers.

Surgical controversies and current concepts in Lisfranc injuries

INTRODUCTION

Lisfranc injuries, not as rare as previously reported, range from ligamentous to complex fracture-dislocations. Anatomical studies have identified a complex of discrete structures, and defined the anatomical characteristics of the Lisfranc joint.

SOURCES OF DATA

A narrative evidence-based review encompassed and analyzed published systematic reviews. Outcomes included clinical and surgical decision-making, including clinical-presentation, diagnosis, pathological-assessment, surgical-management techniques and indications, post-surgical care and comparative outcomes.

AREAS OF AGREEMENT

Better understanding of the Lisfranc complex anatomy aids surgical treatment and tactics. Prognosis is related to injury severity, estimated by the number of foot columns affected. Surgical outcome is determined by anatomical reduction for most fixation and fusion techniques. Appropriate treatment allows return to sport, improving outcome scores.

AREAS OF CONTROVERSY

Identification of Lisfranc injuries may be improved by imaging modalities such as weight-bearing computer tomography. Recent evidence supports dorsal plate fixation as a result of better quality of reduction. In complex injuries, the use of combined techniques such as trans-articular screw and plate fixation has been associated with poorer outcomes, and fusion may instead offer greater benefits.

GROWING POINTS

Open reduction is mandatory if closed reduction fails, highlighting the importance of understanding surgical anatomy. If anatomical reduction is achieved, acute arthrodesis is a safe alternative to open reduction internal fixation in selected patients, as demonstrated by comparable outcomes in subgroup analysis.

AREAS FOR DEVELOPING RESEARCH

The current controversies in surgical treatment remain around techniques and outcomes, as randomized controlled trials are infrequent.

Lisfranc Arthrodesis in Posttraumatic Chronic Injuries

Chronic injuries at the tarsometatarsal joint represent a wide array of painful malunions ranging from isolated instability to complex three-dimensional deformities with rapid development of posttraumatic arthritis. Deformity correction and arthrodesis of the symptomatic joints leads to significant pain reduction and functional improvement provided that realignment of the anatomic axes is achieved. Arthrodesis should be limited to the first to third tarsometatarsal joints, whereas interposition arthroplasty is preferred for symptomatic arthritis of the fourth to fifth tarsometatarsal joints. For complex deformities and instability, the intercuneiform and naviculocuneiform joints may need to be included into corrective fusion.

Comparing bilateral feet computed tomography scans can improve surgical decision making for subtle Lisfranc injury

INTRODUCTION

Subtle Lisfranc injuries (SLIs) are challenging to diagnose. Although weightbearing (WB) radiographs have been suggested to identify SLIs, approximately 20% are missed on initial radiographic assessment. Computed tomography (CT) has been suggested as an alternative, but has not provided any diagnostic guideline. Therefore we compared measurement techniques on radiographs and bilateral foot CT scans for the efficiency of diagnosis and making surgical decisions for SLI.

METHODS

We retrospectively investigated patients diagnosed with SLIs between January 2014 and January 2020. Distances between both medial cuneiform and second metatarsal base (C1M2), and the first and second metatarsal bases (M1M2), were measured on bilateral WB radiographs. Bilateral foot CT scans were taken, and the distances between C1M2 were checked on the axial and three points of the coronal plane (top, middle, and base). The surgical indication was > 1 mm of diastasis on CT scan. Clinical outcomes were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) score at final follow-up. Intraobserver and interobserver agreements were assessed.

RESULTS

Thirty patients with SLIs were reviewed. Twenty-four patients underwent surgical fixation (Group A) and six patients were treated conservatively (Group B). The side-to-side difference (STSD) of C1M2 and M1M2 distances greater than 1 mm showed 91.7% and 54.2% sensitivity, and 66.7% and 16.7% specificity, respectively. Investigating STSDs of all points on CT scans were informative to discriminate both groups (P ≤ 0.038). Clinical outcomes showed no significant difference between the groups (P = 0.631). Intraclass and interclass correlation coefficient values showed good to very good reliability, except for STSD of WB M1M2 distance and the coronal top plane.

CONCLUSION

Investigating bilateral foot CT scans was significantly efficient and reliable for the diagnosis and treatment plan for SLI. On radiographs, STSD of WB C1M2 distance was more sensitive than STSD of WB M1M2 distance.

LEVEL OF EVIDENCE

Case control study; III.

Support system of Lisfranc joint complex: An anatomical investigation with an evolutionary perspective

BACKGROUND

The anatomical arrangement of the Lisfranc joint between the midfoot and forefoot is complex and not just critical for bipedal gait but also for prevention, management, and rehabilitation of injuries in this region.

MATERIAL AND METHODS

In forty adult cadaveric lower limbs, the Lisfranc mortise, the ligaments and supports were observed and noted.

RESULTS

The structural arrangement that accords stability to the joint has osseous, ligamentous, and tendinous components. A bony mortise, which is deep medially, disrupts the linearity of the joint line. An extensive Lisfranc ligament with confluent interosseous and plantar parts was observed. Tibialis posterior, peroneus Longus and Lisfranc ligament exhibit a unique anatomical arrangement that supports the joint inferiorly.

CONCLUSION

The study documents a unique lattice of tendons and ligament offering dynamic support to the joint. Demands of assumption of erect posture and bipedal walking in humans like adduction of the first ray of the foot, maintenance of longitudinal and transverse arches of the foot and ability stiffen midfoot for efficient forefoot take-off are well reflected in the joint structure and supports.

Biomechanical Comparison of Fiber Tape Device Versus Transarticular Screws for Ligamentous Lisfranc Injury in a Cadaveric Model

BACKGROUND

The preferred method of fixation and surgical treatment for ligamentous Lisfranc injuries is controversial. Transarticular screws, bridge plating, fusion, and flexible fixation have been described, yet none have demonstrated superiority. Furthermore, screw fixation and plating often require secondary surgery to remove implants, leading surgeons to seek alternative fixation methods.

PURPOSE

To compare transarticular screws and a fiber tape construct under a spectrum of biomechanical loads by evaluating the diastasis at 3 joints in the Lisfranc complex.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight matched pairs of fresh, previously frozen lower extremity cadaveric specimens were fixed with either 2 cannulated transarticular crossed screws or a fiber tape construct with a supplemental intercuneiform limb. The diastasis between bones was measured at 3 midfoot joints in the Lisfranc complex: the Lisfranc articulation, the second tarsometatarsal joint, and the intercuneiform joint. Measurements were obtained for the preinjured, injured, and fixation conditions under static loading at 50% donor body weight. Specimens then underwent cyclic loading performed at 1 Hz and 100 cycles, based on 100-N stepwise increases in ground-reaction force from 100 to 2000 N, to simulate postoperative loading from the partial weightbearing stage to high-energy activities. Failure of fixation was defined as diastasis ≥2 mm at the Lisfranc articulation (second metatarsal-medial cuneiform joint).

RESULTS

There were no significant differences in diastasis detected at the Lisfranc articulation or the intercuneiform joint throughout all loading cycles between groups. All specimens endured loading up to 50% body weight + 1400 N. Up to and including this stage, there were 2 failures in the cannulated transarticular crossed-screw group and none in the fiber tape group.

CONCLUSION

The fiber tape construct with a supplemental intercuneiform limb, which does not require later removal, may provide comparable biomechanical stability to cannulated transarticular crossed screws, even at higher loads.

CLINICAL RELEVANCE

Ligamentous Lisfranc injuries are common among athletes. Therefore, biomechanical evaluations are necessary to determine stable constructs that can limit the time to return to play. This study compares the biomechanical stability of 2 methods of fixation for ligamentous injury through a wide spectrum of loading, including those experienced by athletes.

The contribution of the ligaments in progressive collapsing foot deformity: A comprehensive computational study

The contribution of each of the ligaments in preventing the arch loss, hindfoot valgus, and forefoot abduction seen in progressive collapsing foot deformity (PCFD) has not been well characterized. An improved understanding of the individual ligament contributions to the deformity would aid in selecting among available treatments, optimizing current surgical techniques, and developing new ones. In this study, we evaluated the contribution of each ligament to the maintenance of foot alignment using a finite element model of the foot reconstructed from computed tomography scan images. The collapsed foot was modeled by simulating the failure of all the ligaments involved in PCFD. The ligaments were removed one at a time to determine the impact of each ligament on foot alignment, and then restored one at a time to simulate isolated reconstruction. Our findings show that the failure of any one ligament did not immediately lead to deformity, but that combined failure of only a few (the plantar fascia, long plantar, short plantar, deltoid, and spring ligaments) could lead to significant deformity. The plantar fascia, deltoid, and spring ligaments were primarily responsible for the prevention of arch collapse, hindfoot valgus, and forefoot abduction, respectively. Moreover, to produce deformity, a considerable amount of attenuation in the spring, tibiocalcaneal, interosseous talocalcaneal, plantar naviculocuneiform, and first plantar tarsometatarsal ligaments, but only a small amount in the plantar fascia, long plantar, and short plantar ligaments was needed. The results of this study suggest that the ability of a ligament to prevent deformity may not correlate with its attenuation in a collapsed foot.

Effects of badminton insole design on stress distribution, displacement and bone rotation of ankle joint during single-leg landing: a finite element analysis

Previous research has reported that up to 92% of injuries amongst badminton players consist of lower limb, whereby 35% of foot fractures occurred at the metatarsal bone. In sports, insoles are widely used to increase athletes' performance and prevent many injuries. However, there is still a lack of badminton insole analysis and improvements. Therefore, this study aimed to biomechanically analyse three different insole designs. A validated and converged three-dimensional (3D) finite element model of ankle-foot complex was developed, which consisted of the skin, talus, calcaneus, navicular, three cuneiform, cuboid, five metatarsals and five phalanges. Three existing insoles from the market, (1) Yonex Active Pro Truactive, (2) Victor VT-XD 8 and (3) Li-Ning L6200LA, were scanned using a 3D scanner. For the analysis, single-leg landing was simulated. On the superior surface of the skin, 2.57 times of the bodyweight was axially applied, and the inferior surface of the outsole was fixed. The results showed that Insole 3 was the most optimum design to reduce peak stress on the metatarsals (3.807 MPa). In conclusion, the optimum design of Insole 3, based on the finite element analysis, could be a justification of athletes' choices to prevent injury and other complications.

Micro-CT analysis of the Lisfranc complex reveals higher bone mineral density in dorsal compared to plantar regions

Injuries to the Lisfranc complex may require surgical fixation, the stability of which may be correlated with bone mineral density (BMD). However, there is limited research on regional BMD variations in the Lisfranc complex. This study used quantitative micro-CT to characterize regional BMD in the four bones (medial cuneiform, intermediate cuneiform, first metatarsal, and second metatarsal) of this complex. Twenty-four cadaveric specimens were imaged with a calibration phantom using micro-CT. Each bone was segmented and divided into eight regions based on an anatomical coordinate system. BMD for each octant was calculated using scan-specific calibration equations and average image intensity. Differences between regions were analyzed using ANOVA with post hoc analysis and differences between groups of four octants in each plane were analyzed with t-tests with significance level α = 0.05. The highest density region in the medial cuneiform was the distal-dorsal-lateral and dorsal regions showed significantly higher BMD than plantar regions. The intermediate cuneiform had the highest density in the distal-dorsal-medial region and the dorsal and medial regions had higher BMD than the plantar and lateral regions, respectively. The densest region of the first metatarsal was the distal-dorsal-lateral and distal regions had significantly higher BMD than proximal regions. In the second metatarsal, the distal-dorsal-medial region had the highest density, and the distal, dorsal, and medial regions had significantly higher BMD than the proximal, plantar, and lateral regions, respectively. The predominant finding was a pattern of increased density in the dorsal bone regions, which may be relevant in the surgical management of Lisfranc injuries.

Analysis of Intramedullary Beam Designs Using Customized Finite Element Models for Medial Column Arthrodesis of the Foot

Intramedullary beaming is a surgical option for medial column arthrodesis; however, disagreement exists about which beam design should be used. This computational study aimed to analyze the effects that common beam parameters have on medial column arthrodesis using a set of 5 subject-specific finite element models. A full-factorial design of experiments was conducted with 3 factors: implant stiffness (114 GPa Titanium vs 193 GPa Stainless Steel), threaded portion (25 mm Partially Threaded vs 130 mm Fully Threaded) and cannulation (Cannulated vs Solid). Increasing implant stiffness, threaded portion and using a solid beam all significantly increased medial column stiffness from 13.9 to 20.0 N/mm (p < .001), 15.2 to 18.8 N/mm (p = .001) and 13.6 to 20.4 N/mm (p < .001), respectively. Moreover, simultaneously increasing all 3 factors resulted in a 172% increase in medial column stiffness, as well as a 33% decrease in maximum von-Mises stress, 70% decrease in strain energy and 44% decrease in the average normal force in the implant during bending; all of which were significant. There was no significant increase in contact area in any of the joints, but there was a significant decrease in micromotion in each joint, ranging from 63% to 66%. Based on the parameters tested, a stainless steel, fully threaded (design that can apply compression), solid intramedullary device would produce the most stable construct for medial column arthrodesis under ideal conditions. Future studies simulating neuropathic conditions are needed before clinical use; however, this study shows the potential benefits of altering the implant design.

The impact of ligament tears on joint contact mechanics in progressive collapsing foot deformity: A finite element study

BACKGROUND

Patients with longstanding progressive collapsing foot deformity often develop osteoarthritis of the ankle, midfoot, or hindfoot joints, which can be symptomatic or lead to fixed deformities that complicate treatment. The development of deformity is likely caused by ligament degeneration and tears. However, the effect of individual ligament tears on changes in joint contact mechanics has not been investigated.

METHODS

A validated finite element model of the foot was used to compare joint contact areas, forces, and pressures between the intact and collapsed foot, and to evaluate the effect of individual ligament tears on joint contact mechanics.

FINDINGS

Collapsing the foot resulted in an increase in contact pressure in the subtalar, calcaneocuboid, tibiotalar, medial naviculocuneiform, and first tarsometatarsal joints but a decrease in contact pressure in the talonavicular joint. Rupture of the spring ligament was the main contributor to increased calcaneocuboid and subtalar joint contact pressures and decreased medial naviculocuneiform and first tarsometatarsal joint contact pressures, as well as talonavicular subluxation. Deltoid ligament rupture was the primary source of increased contact pressure in the medial naviculocuneiform, first tarsometatarsal, and tibiotalar joints.

INTERPRETATION

Degenerative tearing of the ligaments in flatfoot deformity leads to increased joint contact pressures, primarily in the calcaneocuboid, subtalar, and tibiotalar joints, which has been implicated in the development of osteoarthritis in these joints. An improved understanding of the relationship between ligament tears and joint contact pressures could provide support for the use of ligament reconstructions to prevent the development of arthrosis.

A new finite element model of intra-articular impacted fragment in posterior malleolar fractures: A technical note

Intra-articular impacted fragment (IAIF) was considered as the articular surface fragment resulting from impact and compressive forces. Malreduction of IAIF in posterior malleolar fractures was associated with the cause of talus subluxation and long-term arthritis. The effect of IAIF on ankle pressure and stress has not been studied, and it's difficult to do this in cadaver bone. So we established IAIF defect finite element model in posterior malleolar fractures and explored the effect of IAIF defect in ankle joint. We also discussed the relation between IAIF defect and post-traumatic arthritis.

A Review of Finite Element Models of Ligaments in the Foot and Considerations for Practical Application

PURPOSE

Finite element (FE) modeling has been used as a research tool for investigating underlying ligaments biomechanics and orthopedic applications. However, FE models of the ligament in the foot have been developed with various configurations, mainly due to their complex 3D geometry, material properties, and boundary conditions. Therefore, the purpose of this review was to summarize the current state of finite element modeling approaches that have been used in the ?eld of ligament biomechanics, to discuss their applicability to foot ligament modeling in a practical setting, and also to acknowledge current limitations and challenges.

METHODS

A comprehensive literature search was performed. Each article was analyzed in terms of the methods used for: (a) ligament geometry, (b) material property, (c) boundary and loading condition related to its application, and (d) model verification and validation.

RESULTS

Of the reviewed studies, 80% of the studies used simplified representations of ligament geometry, the non-linear mechanical behavior of ligaments was taken into account in only 19.2% of the studies, 33% of included studies did not include any kind of validation of the FE model.

CONCLUSION

Further refinement in the functional modeling of ligaments, the micro-structure level characteristics, nonlinearity, and time-dependent response, may be warranted to ensure the predictive ability of the models.

The Diagnostic Accuracy of MRI to Evaluate Acute Lisfranc Joint Injuries: Comparison With Direct Operative Observations

Background:

Early diagnosis is important in patients with Lisfranc joint injury to avoid subsequent complications. As the ligaments in the Lisfranc joint are relatively small and course obliquely, isotropic 3-dimensional (3D) magnetic resonance imaging (MRI) can be beneficial to evaluate ligament injury. The purpose of this study was to investigate the diagnostic accuracy of MRI, including isotropic 3D MRI for acute injury of the Lisfranc joint, especially of the interosseous C1-M2 ligament (Lisfranc ligament), the dorsal C1-M2 ligament (dorsal ligament), and the interosseous C1-C2 ligament, compared with direct operative observations.

Methods:

This retrospective review identified 27 patients who had undergone MR examination for acute Lisfranc joint injury followed by surgery. We reviewed the operative reports that described the Lisfranc, dorsal, and interosseous C1-C2 ligaments. All patients underwent an MRI, including a 2D oblique plane image parallel to the Lisfranc ligament and an isotropic 3D MRI. An image analysis of the integrity of the 3 ligaments and other associated injuries was performed. The diagnostic accuracy of MRI was analyzed using operative findings as a reference standard.

Results:

Lisfranc and dorsal ligament injuries were identified on MRI in all patients. MRI depicted disruption of the interosseous C1-C2 ligament in 12 patients. MRI diagnostic accuracy for detection of Lisfranc, dorsal, and interosseous C1-C2 ligaments was 100% (95% CI 0.82-1.0), 74% (95% CI 0.54-0.89), and 70% (95% CI 0.50-0.86), respectively.

Conclusion:

MRI with oblique planes parallel to the Lisfranc ligament and isotropic 3D MRI was reliable for detecting Lisfranc ligament injury, whereas MRI findings of the dorsal and interosseous C1-C2 ligaments were less consistent with operative observations.

Level of Evidence:

Level IV, case series.

The Lisfranc Injury: A Literature Review of Anatomy, Etiology, Evaluation, and Management

Despite being first described in the 1800s, the Lisfranc injury remains one of the most controversial topics in foot and ankle surgery. From the basic anatomy of the ligament complex to the optimal diagnostic and management methods, new research both sharpens and yet confounds our understanding of this unique injury. This article reviews the literature from established and classic papers to recent studies evaluating newer techniques. We discuss the unique bony and ligamentous anatomy, which confer strength to the Lisfranc complex, the typical mechanisms of injury, the most common classification systems, the clinical presentation, current imaging modalities, and conservative and surgical treatment options. We review studies comparing open reduction and internal fixation with primary arthrodesis of acute injuries, in addition to studies evaluating the various methods for obtaining fixation, including intra-articular screws, dorsal plates, and flexible fixation. It is clear from this review that despite the vast number of studies in the literature, much is still to be learned about the diagnosis and management of this challenging injury.Levels of Evidence: Level V: Expert opinion.

Reliability of measurements assessing the Lisfranc joint using weightbearing computed tomography imaging

INTRODUCTION

Subtle Lisfranc joint injuries remain challenging to diagnose in clinical practice. Although of questionable accuracy, bilateral weightbearing radiographs are considered the current gold standard to assess these injuries. However, weightbearing computed tomography (WBCT), which provides clearer visualization of bony landmarks, can also be used for evaluation. This study aims to design a protocol that reliably measures the distance between the medial cuneiform (C1) and second metatarsal (M2) to assess the Lisfranc joint using WBCT imaging.

METHODS

Two unique methods of measuring the C1-M2 distance were designed that localize the center of the interosseous Lisfranc ligament (ILL, reference point). This reference point was located by (I) measuring a specific distance at the M2 base, or (II) approximating from nearby bony landmarks, on both axial (Ax) and coronal (Cor) WBCT images. Four parameters (I-Ax, I-Cor, II-Ax, and II-Cor) were evaluated for each of 96 specimens. Measurements were recorded by three independent observers and repeated for inter- and intra-observer agreement.

RESULTS

In total, 96 patient image series were included and assessed in our study with an average age of 46 (19-66, SD 16.1) and average BMI of 25.8 (17.8-30.5, SD 4.3). I-Ax showed excellent agreement for intra-observer evaluation (R = 0.802) and good agreement for inter-observer evaluation (R = 0.727). I-Cor demonstrated excellent inter- (R = 0.814) and intra-observer (R = 0.840) agreement. Good agreement was found for both II-Ax and II-Cor for both intra- (R = 0.730, R = 0.708) and inter-observer (R = 0.705, R = 0.645) evaluation.

CONCLUSION

Measuring the C1-M2 joint space with coronal WBCT imaging through a protocol that localizes the ILL is reproducible, simple, and can potentially be utilized clinically to evaluate the Lisfranc joint.

Anatomy and biomechanics of the Lisfranc ligamentous complex: A systematic literature review

Lisfranc injuries are challenging to treat and can have a detrimental effect on active individuals. Over the past decade researchers have investigated methods for the reconstruction of the Lisfranc ligamentous complex (LLC) to preserve its functional stability and mobility. To aid in this innovation, this study presents the current understanding of the anatomical and biomechanical characteristics of the LLC through a systematic review. Three medical databases (PubMed, Scopus, and Embase) were searched from inception through July 2019. Original studies investigating the anatomy and/or biomechanical properties of the LLC were considered for inclusion. Data recorded from each study included: number of cadavers, number of feet, gender, laterality, age, type of specimen, measurement methods, reported ligamentous bundles, ligament origins and insertions, geometric characteristics, and biomechanical properties of the LLC. The Quality Appraisal for Cadaveric Studies (QUACS) scale was used to assess the methodologic quality of included articles. Eight cadaveric studies investigating the LLC were included out of 1204 screened articles. Most articles described the LLC as three distinct structures: the dorsal- (DLL), interosseous- (ILL), and plantar- (PLL) Lisfranc Ligaments. The ILL had the largest thickness and insertional area of osseous attachment. Biomechanically, the ILL also had the highest stiffness and resistance to load prior to failure when loaded parallel to its fiber orientation. Current knowledge of the anatomical and biomechanical properties of the LLC are presented and highlight its significant role of stabilizing the tarsometatarsal articulation. Appreciating the biomechanical characteristics of the ILL may improve clinical insight in managing LLC injuries.

Development of customized finite element models of medial column fixation using an intramedullary beam: A computational sensitivity analysis

Intramedullary beaming is commonly used for medial column arthrodesis to prevent or correct rocker-bottom deformities; however, the biomechanics of these reconstructions have not been rigorously studied. Customized FE models of intramedullary beaming of the medial column were developed and compared to a previous cadaveric study, which resulted in a strong correlation in medial column stiffness (ρ = 0.83, p = .079) and implant failure locations. A design of experiments was performed to quantify the models' sensitivities to varying cortical shell and cartilage thicknesses, cancellous bone and cartilage elastic moduli, and surgical medial column compression distance. Cartilage thickness and cartilage elastic modulus had the largest impact on medial column stiffness and compression distance had the greatest effect on cartilage contact area. Cortical shell thickness and cancellous bone properties did not have a significant effect on the measured parameters for the values tested. Overall, the FE models exhibited behavior that is consistent with known mechanical principles related to bending and composite structures as well as the experimental results. This study elucidates the effects of varying commonly assumed model parameters that can aid future studies aimed at screening implant designs.

Updates on Lisfranc Complex Injuries

Lisfranc injuries are a disruption of one or more of the tarsometatarsal joints and have an estimated incidence of 1/55 000 people. However, the total number of Lisfranc injuries could be underreported, because almost 20% of these injuries are initially missed. Because of the relative infrequency of these injuries, the current literature is inconsistent in regard to proper treatment. This article provides a review of Lisfranc complex injuries including relevant anatomy, diagnosis, treatment, classifications, operative approaches, and outcomes and complications. Based on existing evidence, it also proposes an algorithm the authors prefer for the evaluation and treatment of Lisfranc complex injuries.

Asymmetric lambda sign of the second tarsometatarsal joint on axial weight-bearing cone-beam CT scans of the foot: preliminary investigation for diagnosis of subtle ligamentous Lisfranc injuries in a cadaveric model

BACKGROUND

Subtle Lisfranc joint injuries remain challenging to diagnose. Although of questionable accuracy, the current gold standard to assess these injuries is through bilateral weight-bearing radiography. However, weight-bearing cone beam-computed tomography (CBCT), providing clearer visualization of bony landmarks, can also be utilized for evaluation. This study aims to establish the hypothesis that a specific weight-bearing CBCT finding (asymmetric lambda sign) can serve as an independent indicator of a subtle Lisfranc injury.

METHODS

Weight-bearing CBCT images of 24 match-paired cadaveric legs were acquired, initially intact, and then following sequential dissection of each aspect (dorsal, interosseous, and plantar ligaments, respectively) of the Lisfranc ligamentous complex (LLC). All scans were taken in non- (NWB, 0 kg), partial- (PWB, 40 kg), and full-weight-bearing (FWB, 80 kg) manners. The lambda sign was then inspected axially for asymmetry (positive sign) by identifying three symmetrical joint spaces created between the medial cuneiform and the second metatarsal base (C1-M2), the medial and middle cuneiform (C1-C2), and the second metatarsal base and middle cuneiform (M2-C2).

RESULTS

A positive sign was observed in 25.6% (221/864) of all studies. Most notably, the fully dissected specimens demonstrated an asymmetric lambda sign in 33.3%, 72.2%, and 83.3% in NWB, PWB, and FWB conditions, respectively. The inter- and intra-observer reliability kappa value was calculated to be 0.843 and 0.912.

CONCLUSION

An asymmetric lambda sign is a simple and useful indicator for a complete LLC injury in PWB and FWB conditions using a cadaver model.

Dynamic MR imaging analysis of instability in the injured Lisfranc joint with an MRI-compatible foot stressor device

PURPOSE

To evaluate the applicability of an MRI-compatible foot stressor device in patients with image-proven or clinically suspected Lisfranc joint injuries.

METHOD

This prospective study evaluated Lisfranc joint injury by utilizing a joint-specific, stress device that was engineered to replicate weightbearing and physical examination maneuvers. Sixteen patients with either clinically suspected or image-proven Lisfranc joint injuries were recruited from September 2018 to November 2019 (9 men, 7 women; mean age, 39.3 years; age range, 14-68 years). Resting and stressed MR sequences of the injured and non-injured feet were obtained. Measured values for Lisfranc interval widths, dorsal tarsometatarsal subluxations, and lambda-angles were subtracted between the stressed and resting images to calculate net stress-induced changes. A graded injury schema was used to measure significance.

RESULTS

The foot stressor device reliably generated stress-induced changes in the Lisfranc joint during dynamic MRI examination. All morphologically abnormal ligaments on resting images demonstrated stress-induced changes, whereas all morphologically normal ligaments lacked evidence of instability. More severely injured Lisfranc ligaments allowed greater Lisfranc joint widening (IOL, p < 0.001; PCL, p < 0.001; DCL, p < 0.001). More highly graded DCL injuries allowed greater dorsal TMT subluxation when present (p < 0.001). Angular gain in the midfoot (lambda-angle) correlated with the graded IOL score (p < 0.001). Acute-to-subacute injuries demonstrated greater inducible changes than chronic injuries (p = 0.047). Seven patients underwent surgery and nine patients received physical therapy.

CONCLUSIONS

Stress-induced changes in the midfoot provided information on the degree of ligament pathology and associated joint instability in Lisfranc joint injuries.

Limited internal fixation combined with a joint-spanning external fixator in the treatment of Midfoot injuries in children

The aim of this study was to explore the clinical features and surgical treatment methods of unstable midfoot injuries in children. Eleven children with severe unstable midfoot injuries admitted to Jishuitan Hospital, Beijing, from June 2009 to October 2016 were enrolled, including seven patients with Lisfranc injuries and four patients with Chopart injuries. All Lisfranc injuries had radiographic data from the healthy sides, and radiographs of the affected sides showed that all injured Lisfranc joints separated more than 3 mm compared with the healthy sides. The treatment methods employed a joint-spanning external fixator to distract and maintain the length of the medial and lateral columns, combined with joint-preserving trans-joint locking plate fixation or trans-articular cannulated screw and Kirschner wire fixation that passed through the joint. The patients were followed up for 53.7 months (17-110 months). The average operation time was 95.1 minutes, and the average intraoperative blood loss was 83.3 ml. Nine of the 11 patients were treated with an external fixator to distract and fix the medial or lateral column. Bone healing was achieved in all patients, and none of the patients complained of chronic pain in the midfoot. Flatfoot and valgus deformity were corrected after the surgery in the child with old fracture, and the pain in the calcaneocuboid joint disappeared. The average American Orthopedic Foot and Ankle Society mid-foot score at the last follow-up was 93.4, of which nine cases were greater than 90 and two cases were between 75 and 89. Children's midfoot injury is characterized by fracture-dislocation. Simple joint capsule tear or ligament rupture is rare and often accompanied by severe cuboid compression fracture. The treatment should be focused on restoring the stability of the bony structure and the length of the medial and lateral columns. The use of a joint-spanning external fixator helps maintain reduction and restore the length of the medial and lateral columns.

Low-Energy Lisfranc Injuries: When to Fix and When to Fuse

Lisfranc injuries can be devastating to the athlete and nonathlete. In the athletic population, minor loss of midfoot stability compromises the high level of function demanded of the lower extremity. The most critical aspect of treatment is identifying the injury and severity of the ligamentous/articular damage. Not all athletes are able to return to their previous level of function. With appropriate treatment, a Lisfranc injury does not mandate the cessation of an athletic career. We focus on the diagnosis and an algorithmic approach to treatment in the athlete discussion the controversy of open reduction and internal fixation versus arthrodesis.

Lisfranc injuries: Incidence, mechanisms of injury and predictors of instability

BACKGROUND

In Lisfranc injuries the stability of the tarsometatarsal joints guides the treatment of the injury. Determining the stability, especially in the subtle Lisfranc injuries, can be challenging. The purpose of this study was to identify incidence, mechanisms of injury and predictors for instability in Lisfranc injuries.

METHODS

Eighty-four Lisfranc injuries presenting at Oslo University Hospital between September 2014 and August 2015 were included. The diagnosis was based on radiologically verified injuries to the tarsometatarsal joints. Associations between radiographic findings and stability were examined.

RESULTS

The incidence of Lisfranc injuries was 14/100,000 person-years, and only 31% were high-energy injuries. The incidence of unstable injuries was 6/100,000 person-years, and these were more common in women than men (P = 0.016). Intraarticular fractures in the two lateral tarsometatarsal joints increased the risk of instability (P = 0.007). The height of the second tarsometatarsal joint was less in the unstable injuries than in the stable injuries (P = 0.036).

CONCLUSION

The incidence of Lisfranc injuries in the present study is higher than previously published. The most common mechanism of injury is low-energy trauma. Intraarticular fractures in the two lateral tarsometatarsal joints, female gender and shorter second tarsometatarsal joint height increase the risk of an unstable injury.

LEVEL OF EVIDENCE

Level III, cross-sectional study.

Imaging in Lisfranc injury: a systematic literature review

OBJECTIVES

To systematically review current diagnostic imaging options for assessment of the Lisfranc joint.

MATERIALS AND METHODS

PubMed and ScienceDirect were systematically searched. Thirty articles were subdivided by imaging modality: conventional radiography (17 articles), ultrasonography (six articles), computed tomography (CT) (four articles), and magnetic resonance imaging (MRI) (11 articles). Some articles discussed multiple modalities. The following data were extracted: imaging modality, measurement methods, participant number, sensitivity, specificity, and measurement technique accuracy. Methodological quality was assessed by the QUADAS-2 tool.

RESULTS

Conventional radiography commonly assesses Lisfranc injuries by evaluating the distance between either the first and second metatarsal base (M1-M2) or the medial cuneiform and second metatarsal base (C1-M2) and the congruence between each metatarsal base and its connecting tarsal bone. For ultrasonography, C1-M2 distance and dorsal Lisfranc ligament (DLL) length and thickness are evaluated. CT clarifies tarsometatarsal (TMT) joint alignment and occult fractures obscured on radiographs. Most MRI studies assessed Lisfranc ligament integrity. Overall, included studies show low bias for all domains except patient selection and are applicable to daily practice.

CONCLUSIONS

While conventional radiography can demonstrate frank diastasis at the TMT joints; applying weightbearing can improve the viewer's capacity to detect subtle Lisfranc injury by radiography. Although ultrasonography can evaluate the DLL, its accuracy for diagnosing Lisfranc instability remains unproven. CT is more beneficial than radiography for detecting non-displaced fractures and minimal osseous subluxation. MRI is clearly the best for detecting ligament abnormalities; however, its utility for detecting subtle Lisfranc instability needs further investigation. Overall, the available studies' methodological quality was satisfactory.

Anatomy of the Lateral Plantar Ligaments of the Transverse Metatarsal Arch

BACKGROUND

While the anatomy of the Lisfranc complex is well understood, the lateral tarsometatarsal ligamentous structures, in contrast, are less well studied. Our aim in this study was to identify an anatomical explanation as to why the second to fifth metatarsals function as a unit in homolateral and divergent midfoot injuries.

METHODS

Eleven cadaveric lower limbs, preserved in formaldehyde, were examined at the University of Liverpool Human Anatomy and Resource Centre. Each of the lower limbs was dissected to identify the plantar aspect of the transverse metatarsal arch.

RESULTS

On removal of the long plantar ligament, the peroneal longus tendon was visible, as was its insertion onto the first metatarsal base. A lateral Lisfranc ligament (which was a transverse suspensory metatarsal ligament) spanned between the bases of the second and fifth metatarsals in all specimens with an average length of 33.7 mm and width of 4.6 mm. This ligament has not previously been described. It was noted that in all specimens, the long plantar ligament blended with the lateral Lisfranc ligament. In addition to the lateral Lisfranc ligament, separate intermetatarsal ligaments were identifiable connecting each metatarsal. The long plantar ligament provided a connection through the lateral Lisfranc ligament connecting the transverse and longitudinal arches of the foot.

CONCLUSION

We found a plantar ligament that provided connection through the long plantar ligament of both the transverse and the longitudinal arches. It spanned from the second to the fifth metatarsal, which we believe may explain that in some cases, lateral instability can be overcome when the middle column is stabilized.

CLINICAL RELEVANCE

We suspect that in the majority of homolateral and divergent types of tarsometatarsal injuries that the lateral Lisfranc ligament remains intact and thus it has significant clinical ramifications.

Flexible Fixation Technique for Lisfranc Injuries

Injuries to the Lisfranc complex range from purely ligamentous disruptions to fracture-dislocations of the tarsometatarsal joint. Treatment options include closed/open reduction with percutaneous pinning, open reduction and internal fixation (ORIF), and primary arthrodesis. We present a ligament reinforcement technique utilizing a flexible fixation device for the treatment of ligamentous Lisfranc injuries. Level of Evidence: Level V, expert opinion.

Anatomical Pathology of Subtle Lisfranc Injury

The extent and patterns of Lisfranc joint complex disruption in subtle Lisfranc injuries have not been well clarified. We reviewed the direct intraoperative findings for 87 patients, examined computed tomography images that had been obtained preoperatively for 73 of the patients, and classified the injuries according to the Kaar  et al. criteria as the transverse type (instability between the first cuneiform [C1] and the second metatarsal [M2] and between the second cuneiform [C2] and M2) or longitudinal type (instability between C1 and M2 and between C1 and C2). Our patients’ injuries were classified as follows: longitudinal type (38%), transverse type (30%), transverse type and first tarsometatarsal (TMT) joint injury (20%), longitudinal type plus transverse type (7%), longitudinal type and first TMT joint injury (3%), and longitudinal type, transverse type, and first TMT joint injury (2%). In 11 patients, the longitudinal injury extended into the naviculo-first cuneiform joint. In 41 (56%) of the 73 patients for whom CT images were obtained, 1 or more fractures (not counting small avulsion fragments between C1 and M2) were found. Orthopedic surgeons should be aware of the various injury patterns possible in cases of subtle Lisfranc injury.

Dynamic Stress MRI of Midfoot Injuries: Measurable Morphology and Laxity of the Sprained Lisfranc Ligament During Mechanical Loading: A Case Report

CASE

Our 26-year-old patient is a professional ballet dancer who suffered a classic Lisfranc joint injury while performing a dancing maneuver with his foot in full plantar flexion. Initial workup with radiographs revealed borderline Lisfranc interval widening without definitive joint instability. Further evaluation with an innovative dynamic stress magnetic resonance imaging (MRI) revealed mild interosseous Lisfranc ligament laxity and sprain, which allowed the orthopaedic surgeon to pursue conservative management, rather than surgery. After physical therapy, our patient reports a successful return to dancing.

CONCLUSIONS

Dynamic stress MRI may become a useful technique in evaluating equivocal cases of midfoot injury through the use of new imaging-based criteria.

InternalBrace has biomechanical properties comparable to suture button but less rigid than screw in ligamentous lisfranc model

Purpose

The aim of this study was to investigate the biomechanical properties of the InternalBrace for lisfranc injuries.

Methods

A Sawbone model was developed comparing screw, suture button and InternalBrace.

Results

When loaded in axial tension at 0.5 mm/s, the screw was stiffest (2,240 N/mm), while the InternalBrace (200 N/mm) was stiffer than the suture button (133 N/mm). Cyclic loading with 10,000 cycles of 69 N, 138 N, and 207 N showed the InternalBrace maintained stiffness, but fatigued earlier than the suture button.

Conclusion

The mechanical properties of the InternalBrace support clinical use, but further studies are needed regarding early weight bearing.

The computed tomographybased anatomy of the ossa cuneiformia

There is a lack of basic anatomic information regarding the ossa cuneiformia. The aim of the present descriptive study was the detailed evaluation of the anatomy of the ossa cuneiformia. We analyzed 100 computer tomography scans of feet without deformities or previous trauma. The length, height and width of each cuneiforme and their articular surfaces were assessed. We itemized the data to gender differences and to foot length. The medial cuneiforme os had a length of 24.0 mm ± 2.4 (mean ± standard deviation), a width of 17.3 mm ± 2.8 and a height of 28.0 mm ± 3.4. The respective values for the intermediate cuneiforme were 18.2 mm ± 2.1, 15.8 mm ± 2.1 and 22.5 ± 2.2 and for the lateral cuneiforme 26.4 mm ± 2.7, 17.2 mm ± 2.9 and 22.8 mm ± 2.9. We found statistical relevant differences regarding gender and foot length subgroups whereas not for all parameters. The present study illustrates basic anatomic data regarding the ossa cuneiformia. This information might be helpful for implant design and placement during midfoot surgery.

Evaluation of the Area of the Lisfranc Ligament Damaged by Screw Fixation

BACKGROUND

A cannulated screw is currently the standard fixation method to reduce and stabilize diastasis at the lisfranc joint following injury. Currently, there is no literature examining the area of the lisfranc ligament damaged by screw placement. The objective of this investigation is to define the area of the ligament damaged by fixation with a 3.5-mm cannulated screw.

MATERIALS AND METHODS

Twelve cadaveric feet were dissected to identify the Lisfranc ligament metatarsal insertion site and origin on the medial cuneiform. A 3.5-mm cannulated screw was then passed over the course of the ligament and removed. The Lisfranc joint was then dissected to measure the dimensions of the ligament and damage from screw passage at the origin and insertion using imaging software.

RESULTS

Mean injury area on the metatarsal was 3.49 mm² and the area of injury for the cuneiform was 3.33 mm². The mean percent of the area damaged was calculated to be 1.75% and 2.43% at the cuneiform and metatarsal, respectively.

CONCLUSION

A proportionally small area of the Lisfranc ligament is disrupted following screw fixation, but the implications of this on ligament healing and outcomes remain to be elucidated.

LEVELS OF EVIDENCE

Level V: Cadaveric study.

Reliability, Surgeon Preferences, and Eye-Tracking Assessment of the Stress Examination of the Tarsometatarsal (Lisfranc) Joint Complex

The primary objective of this investigation was to determine the level of agreement and reliability of the stress examination of the Lisfranc tarsometatarsal joint complex. Secondary objectives were to determine surgeon preferences with respect to this testing and to use gaze recognition software to perform an eye-tracking assessment during the performance of the test. Twelve foot and ankle surgeons, 12 residents, and 12 students were shown 2 intraoperative fluoroscopic still images and 1 video of the stress examination of the tarsometatarsal joint complex using stress abduction of the forefoot on the rearfoot. Participants were asked to evaluate the result as being "positive" or "negative" for tarsometatarsal joint stability. The overall reliability of the interpretation of the stress examination was a kappa of 0.281 (surgeons 0.182; residents 0.423; students 0.256) indicating "fair" agreement. Survey results indicated wide variability in the perioperative preferences and protocols of surgeons dealing with the evaluation and treatment of the tarsometatarsal joint. Eye-tracking results also demonstrated variability in the anatomic structures of interest focused on during performance of this testing. The results of this investigation provide evidence of reliability well below what would be expected of a gold standard test during stress examination of the Lisfranc tarsometatarsal joint complex. These results indicate that future scientific endeavors are required to standardize the performance and interpretation of this testing.

Lisfranc Joint Ligament Complex Reconstruction: A Promising Solution for Missed, Delayed, or Chronic Lisfranc Injury Without Arthritis

The current classifications of "Lisfranc injury" can be purely ligamentous (low-grade midfoot sprains) or involve the osseous and articular structures (high-grade Lisfranc fracture displacements). The first type is often difficult to detect. If these patients are not properly treated, long-term disability can result. The rate of missed or delayed diagnoses has ranged from 13% to 24%, primarily owing to the subtlety of the radiographic findings. This is relatively more common in cases of subtle ligamentous injury (19%). The aim of the present report was to provide a new technique for missed or delayed Lisfranc injury without degenerative local signs. The Lisfranc ligament complex reconstruction is performed with a gracilis tendon graft and is protected by temporary screw fixation. We performed this technique in 3 patients. All 3 patients obtained good results, have been able to resume their previous activities, and have stated they would undergo this type of procedure again. The minimum follow-up length was 2 years.

Subtle Lisfranc Injuries: A Topical Review and Modification of the Classification System

Lisfranc injuries are relatively uncommon. No specific incidence of subtle injuries has been reported; however, almost one-third are missed on initial review. These missed injuries are a common cause of litigation. Although seen in high-energy injuries with direct application of forces, they are also associated with lower-energy indirect mechanisms, often on the athletic field. This article provides a topical review of subtle Lisfranc disruptions, focusing on contemporary perspectives, and describes a modification to the most prevalent classification system. [Orthopedics. 2018; 41(2):e168-e175.].

Stability of Lisfranc injury fixation in Thiel Cadavers: Is routine fixation of the 1st and 3rd tarsometatarsal joint necessary?

BACKGROUND

There is debate as to whether a home run screw (medial cuneiform to 2nd metatarsal base) combined with k-wire fixation of the 4th & 5th tarsometatarsal joints is sufficient to stabilise Lisfranc injuries or if fixation of the 1st and 3rd tarsometatarsal joints is also required. Unlike the 2nd, 4th and 5th tarsometatarsal joints, stabilisation of the 1st and 3rd requires either intra-articular screw or an extra-articular plate which risk causing chondrolysis and/or osteoarthritis. The aims of this cadaveric study were to determine if routine fixation of the 1st and 3rd tarsometatarsal joints is necessary and to determine if a distal to proximal home run screw is adequate.

METHODS

Using 8 Theil-embalmed specimens, measurements of tarsometatarsal joint dorsal displacement at each ray (1st-5th) and 1st-2nd metatarsal gaping were made during simulated weight bearing with sequential ligamentous injury and stabilisation to determine the contribution of anatomical structures and fixation to stability.

RESULTS

At baseline, mean dorsal tarsometatarsal joint displacement of the intact specimens during simulated weight bearing (mm) was: 1st: 0.14, 2nd: 0.1, 3rd:0, 4th: 0, 5th: 0.14. The 1st-2nd intermetatarsal gap was 0mm. After transection of the Lisfranc ligament only, there was 1st-2nd intermetatarsal gaping (mean 4.5mm), but no increased dorsal displacement. After additional transection of all the tarsometatarsal joint ligaments, dorsal displacement increased at all joints (1st: 4.5, 2nd: 5.1, 3rd: 3.6, 4th: 2, 5th: 1.3). Stabilisation with the home run screw and 4th and 5th ray k-wires virtually eliminated all displacement. Further transection of the inter-metatarsal ligaments increased mean dorsal displacement of the 3rd ray to 2.5mm. K-wire fixation of the 3rd ray completely eliminated dorsal displacement.

CONCLUSIONS

The results of this cadaveric study suggest that stabilising the medial cuneiform to the 2nd metatarsal base combined with stabilisation of the 4th and 5th tarsometatarsal joints with K-wires will stabilise the 1st and 3rd tarsometatarsal joints if the inter-metatarsal ligaments are intact. Thus 3rd TMTJ stability should be checked after stabilising the 2nd and 4/5th. Provided the intermetatarsal ligaments (3rd-4th) are intact, the 3rd ray does not need to be routinely stabilised.

Management of Tarsometatarsal Joint Injuries

Joint disruptions to the tarsometatarsal (TMT) joint complex, also known as the Lisfranc joint, represent a broad spectrum of pathology from subtle athletic sprains to severe crush injuries. Although injuries to the TMT joint complex are uncommon, when missed, they may lead to pain and dysfunction secondary to posttraumatic arthritis and arch collapse. An understanding of the appropriate anatomy, mechanism, physical examination, and imaging techniques is necessary to diagnose and treat injuries of the TMT joints. Nonsurgical management is indicated in select patients who maintain reduction of the TMT joints under physiologic stress. Successful surgical management of these injuries is predicated on anatomic reduction and stable fixation. Open reduction and internal fixation remains the standard treatment, although primary arthrodesis has emerged as a viable option for certain types of TMT joint injuries.

A Finite Element Model of the Foot/Ankle to Evaluate Injury Risk in Various Postures

The foot/ankle complex is frequently injured in many types of debilitating events, such as car crashes. Numerical models used to assess injury risk are typically minimally validated and do not account for ankle posture variations that frequently occur during these events. The purpose of this study was to evaluate a finite element model of the foot and ankle accounting for these positional changes. A model was constructed from computed tomography scans of a male cadaveric lower leg and was evaluated by comparing simulated bone positions and strain responses to experimental results at five postures in which fractures are commonly reported. The bone positions showed agreement typically within 6° or less in all anatomical directions, and strain matching was consistent with the range of errors observed in similar studies (typically within 50% of the average strains). Fracture thresholds and locations in each posture were also estimated to be similar to those reported in the literature (ranging from 6.3 kN in the neutral posture to 3.9 kN in combined eversion and external rotation). The least vulnerable posture was neutral, and all other postures had lower fracture thresholds, indicating that examination of the fracture threshold of the lower limb in the neutral posture alone may be an underestimation. This work presents an important step forward in the modeling of lower limb injury risk in altered ankle postures. Potential clinical applications of the model include the development of postural guidelines to minimize injury, as well as the evaluation of new protective systems.

3-D computer modelling of malunited posterior malleolar fractures: effect of fragment size and offset on ankle stability, contact pressure and pattern

BACKGROUND

The positioning of the fracture fragment of a posterior malleolus fracture is critical to healing and a successful outcome as malunion of a posterior malleolar fracture, a condition seen in clinical practice, can affect the dynamics of the ankle joint, cause posterolateral rotational subluxation of the talus and ultimately lead to destruction of the joint. Current consensus is to employ anatomic reduction with internal fixation when the fragment size is larger than 25 to 33% of the tibial plafond.

METHODS

A 3-dimensional finite element (FE) model of ankle was developed in order to investigate the effect of fragment size (6-15 mm) and offset (1-4 mm) of a malunited posterior malleolus on tibiotalar joint contact area, pressure, motion of joint and ligament forces. Three positions of the joint were simulated; neutral position, 20° dorsiflexion and 30° plantarflexion.

RESULTS

Compared to the intact joint our model predicted that contact area was greater in all malunion scenarios considered. In general, the joint contact area was affected more by section length than section offset. In addition fibula contact area played a role in all the malunion cases.

CONCLUSIONS

We found no evidence to support the current consensus of fixing posterior malleolus fractures of greater than 25% of the tibial plafond. Our model predicted joint instability only with the highest level of fracture in a loaded limb at an extreme position of dorsiflexion. No increase of peak contact pressure as a result of malunion was predicted but contact pattern was modified. The results of our study support the view that in cases of posterior malleolar fracture, posttraumatic osteoarthritis occurs as a result of load on areas of cartilage not used to loading rather than an increase in contact pressure. Ankle repositioning resulted in increased force in two ankle ligaments. Our finding could explain commonly reported clinical observations.

The Role of Percutaneous Reduction and Fixation of Lisfranc Injuries

To be able to perform percutaneous fixation of Lisfranc injuries, this article emphasizes that an anatomic reduction must be mandatory. When uncertainty remains as to whether closed reduction is anatomic, formal open reduction is recommended because accuracy of reduction is correlated with long-term outcome. Closed injuries with minimal displacement, bony avulsions, and skeletally immature individuals seem the most appropriate indications for percutaneous fixation. Not all injuries are ideal for this method of treatment, and this is an area that needs to be more clearly defined in the future.

Open Reduction and Internal Fixation Versus Primary Arthrodesis for Lisfranc Injuries

Management of injuries to the tarsometatarsal (Lisfranc) joint complex continues to generate heated debate. Arthrodesis of the Lisfranc joint complex has historically been reserved as a salvage procedure for failed treatment. Recently, primary arthrodesis has emerged as a viable treatment alternative to open reduction and internal fixation for these injuries. The objective of this article was to examine the current literature regarding open reduction and internal fixation versus primary arthrodesis of Lisfranc injuries.

Management of sports injuries of the foot and ankle: An update

Injuries to the foot in athletes are often subtle and can lead to a substantial loss of function if not diagnosed and treated appropriately. For these injuries in general, even after a diagnosis is made, treatment options are controversial and become even more so in high level athletes where limiting the time away from training and competition is a significant consideration. In this review, we cover some of the common and important sporting injuries affecting the foot including updates on their management and outcomes. Cite this article: Bone Joint J 2016;98-B:1299-1311.