Tibiotalar Contact Area Research Articles

Management of Neglected and Malunited Ankle Fractures

Abstract Background Ankle fractures are very frequent and they can present a variety of clinical features. Dislocated or unstable ankle fractures are generally treated with surgical anatomical reduction and internal fixation. Most of these fractures heal very well. However, some of these fractures fail to reduce and become malunited. Early biomechanical studies have demonstrated that lateral talar shift greater than 1mm may cause a loss of over 40% of the tibiotalar contact area. Aim of the Work The aim of the treatment is to obtain an ankle with normal alignment and function which exhibits no pain with preventing any degenerative changes that may take place in the future. Surgical options include refixation of non-united medial or lateral malleolus, lengthening of fibula, repair of neglected syndesmotic injury, and repair of other ligamentous injury. Patients and Methods Our study included 30 patients with malunited ankle fractures. The outcomes were compared pre and post operatively. The Inclusion criteria were patients with malunited or neglected ankle fractures, both sexes and Age between 20 – 60 years old. While, Exclusion criteria were patients suffering from peripheral vascular insufficiency, advanced ischemia, peripheral neuropathy, advanced tibiotalar osteoarthritis, soft tissue compromise, stiff ankle, infected non-union and skeletally immature patients. Results The AOFAS in patient with syndesmotic affection showed improvement from mean±SD 48.35±12.99 preoperatively to 82.71±10.32 postoperatively, while in patients with non syndesmotic affection showed improvement from 60.46±18.91 preoperatively to 86.77±20.79 post operatively. This means that this is significant increase in AOFAS score in both groups but its more obvious among patients with syndesmotic affection. The FAAM score in patient with syndesmotic affection showed improvement from mean±SD 46.47±15.96 preoperatively to 82.41±8.05 postoperatively, while in patients with non syndesmotic affection showed improvement from 54±18.96 preoperatively to 79.77±16.45 post operatively. It means that there is increase in FAAM score in both groups but its more significant among patients with syndesmotic affection. The FADI score among patients was mean±SD 49.87±11.39 preoperatively and 77.07±11.89 two years postoperative, there was statistically significant higher mean value of FADI in follow up compared to pre-operative. Conclusion There is statistically significant improvement in functional and radiological outcomes in patients with syndesmotic affections more than patients with non syndesmotic affection.

The Influence of Talar Displacement on Articular Contact Mechanics: A 3D Finite Element Analysis Study Using Weightbearing Computed Tomography.

Talar displacement is considered the main predictive factor for poor outcomes and the development of post-traumatic osteoarthritis after ankle fractures. Isolated lateral talar translation, as previously studied by Ramsey and Hamilton using carbon powder imprinting, does not fully replicate the multidirectional joint subluxations seen in ankle fractures. The purpose of this study was to analyze the influence of multiple uniplanar talar displacements on tibiotalar contact mechanics utilizing weightbearing computed tomography (WBCT) and finite element analysis (FEA). Nineteen subjects (mean age = 37.6 years) with no history of ankle surgery or injury having undergone WBCT arthrogram (n = 1) and WBCT without arthrogram (n = 18) were included. Segmentation of the WBCT images into 3D simulated models of bone and cartilage was performed. Three-dimensional (3D) multiple uniplanar talar displacements were simulated to investigate the respective influence of various uniaxial displacements (including lateral translation, anteroposterior translation, varus-valgus angulation, and external rotation) on the tibiotalar contact mechanics using FEA. Tibiotalar peak contact stress and contact area were modeled for each displacement and its gradations. Our modeling demonstrated that peak contact stress of the talus and tibia increased, whereas contact area decreased, with incremental displacement in all tested directions. Contact stress maps of the talus and tibia were computed for each displacement demonstrating unique patterns of pressure derangement. One millimeter of lateral translation resulted in 14% increase of peak talar contact pressure and a 3% decrease in contact area. Our model predicted that with lateral talar translation, there is less noticeable change in tibiotalar contact area compared with prior studies whereas external rotation greater than 12 degrees had the largest effect on peak contact stress predictions. Level V, computational simulation study.

Injury to the posterior malleolus in Maisonneuve fractures

PurposeThe aim of this study was to describe the incidence and a complex pathoanatomy of posterior malleolus fractures in a Maisonneuve fracture.MethodsThe study included 100 prospectively collected patients with a complete clinical and radiological documentation of an ankle fracture or fracture-dislocation including a fracture of the proximal quarter of the fibula.ResultsA posterior malleolus fracture was identified in 74 patients, and in 27% of these cases it carried more than one quarter of the fibular notch. Displacement of the posterior fragment by more than 2 mm was shown by scans in 72% of cases. Small intercalary fragments were identified in 43% of cases. Fractures of the Tillaux–Chaput tubercle were identified in 20 patients.ConclusionOur study has proved a high rate of posterior malleolus fractures associated with a Maisonneuve fracture, and documented their considerable variability in terms of involvement of the fibular notch, tibiotalar contact area, direction of displacement and frequency of intercalary fragments. Of no less importance is a combination of Tillaux–Chaput fractures with a Maisonneuve fracture.

The Influence of Multiplanar Talar Displacement on Articular Ankle Loading: A 3D Finite Element Study

Category: Trauma; Ankle Introduction/Purpose: Ankle fractures represent an increasingly common injury world-wide and the decision for operative fixation often hinges on the definition of acceptable stability. Mortise malalignment has generally been considered as the main predictive factor leading to poorer outcomes and the development of post-traumatic osteoarthritis. Following pioneering work by Ramsey & Hamilton, 1-2 mm of lateral talar displacement has commonly been regarded as a cutoff value for surgical decision making. However, isolated lateral talar translation (as studied in previous works) does not fully replicate the multidirectional joint subluxation seen in ankle fractures. Furthermore, previous studies have been limited by low fidelity methodologic techniques. Therefore, the aim of this study was to analyze the influence of multiplanar talar displacement on tibiotalar contact mechanics utilizing finite element analysis (FEA). Methods: 19 patients having undergone advanced computed tomography (CT) scanning of the ankle were included. A female patient (age 18 years, weight 60 kg) without preexisting articular ankle pathology underwent a weightbearing CT-arthrogram of the left ankle. Additionally, 18 ankles derived from the contralateral healthy side in patients who underwent bilateral weightbearing CT scans (WBCT ) for evaluation of a contralateral ankle fracture were included (mean age = 38.70 years, mean weight = 80.00 kg, left/right: 9/9). Segmentation of the WBCT images into 3D models of bone and cartilage was performed semi-automatically, while on the non-arthrography WBCT images, personalized cartilage layers were modeled based on a previously validated methodology. 3D multiplanar talar displacement was simulated to investigate their respective influence on the tibiotalar contact mechanics. Tibial peak contact stress, talar peak contact stress and contact area were extracted from the FEA models for each condition. Results: The talar peak contact stress (in MPa), tibial peak contact stress (in MPa) and contact area (in mm²) for each condition are presented in Table 1. Overall, both the mean and peak contact stress for the talus and tibia incrementally increased when the talus was displaced, for all directions. Correspondingly, the contact area incrementally decreased. Contact stress maps of the talus and tibia were computed for each of the conditions, demonstrating unique patterns of pressure derangement. 1 mm of lateral translation resulted in 11% increase in peak contact pressure and a 12% decrease in contact area. External rotation exhibited the greatest influence on contact stress, reaching a peak talar stress of 510% above baseline after 20 degrees of external talar rotation. Conclusion: In this study, we were able to build on the paradigm of prior uniplanar cadaveric studies and provide a multiplanar mortise malalignment model. The use of advanced computational technologies allowed for more precise quantitative evaluation of articular contact mechanics. With lateral talar translation, our model demonstrated less dramatic increases in tibiotalar contact area compared to previous studies, whereas external rotation had the largest effect regarding pathologic joint loading. Clinically, this study provides a novel understanding of the mechanical sequelae of 3D talar displacement and the importance for adequate mortise alignment.

Biomechanical Changes in the Ankle Joint after Syndesmosis and Deltoid Injury and Subsequent Repair in a Cadaveric Model

Category: Ankle; Trauma Introduction/Purpose: Recent studies have stressed the important role of the deltoid ligament in maintaining global ankle stability. However, controversy remains around whether deltoid ligament repair is necessary in addition to syndesmotic repair when addressing injuries to both. The purpose of this study was to measure differences in tibiotalar joint contact pressures and tibiotalar contact area in the presence of deltoid ligament injury, syndesmotic injury, and after their respective repairs using a cadaveric model. Our hypotheses were 1) injury to the syndesmosis and deltoid would increase contact pressures and decrease contact area, 2) repaired injuries would restore biomechanics to near native state, and 3) that there would be similar tibiotalar contact pressures and contact area with syndesmosis repair alone compared to syndesmosis and deltoid ligament repair. Methods: Twelve human cadaveric lower extremities were randomized and tested under a series of conditions: 1) native, 2) sectioning of syndesmosis or deltoid, 3) sectioning of both the syndesmosis and deltoid, 4) repair of syndesmosis or deltoid, 5) repair of both. In one group, the syndesmosis was sectioned and repaired first and in the other the deltoid was sectioned and repaired first. The syndesmosis was repaired with a single high-tensile strength suture mechanism and deltoid ligament repairs were performed with a single suture anchor. Specimens were tested under each condition with an axial compressive and torsional load. Contact pressures and area within the ankle were measured with a digitized pressure sensor (Tekscan, Boston MA). Changes in contact pressure and area were compared with two-way repeated measure analysis of variance and significant findings were tested with post-hoc pairwise comparisons of estimated marginal means with Bonferroni-adjusted p-values for multiple comparisons (α = 0.05). Results: The highest mean contact pressure was seen when the deltoid was injured, but the syndesmosis was still intact (4.43 +/- 1.328 mPa) compared to mean contact pressure of 3.142 +/-0.511 mPa in the native condition. The lowest mean contact pressure was seen when the deltoid was repaired, but the syndesmosis was still disrupted (3.068 +/- 0.477). However, these differences in mean contact pressures did not differ significantly with pairwise comparison. Total contact area was significantly less following syndesmosis repair in isolation when compared to the native condition (609.55+-312.37mm2 vs 903.854mm2 p=0.0183). When the syndesmosis was repaired, irrespective of the state of the deltoid, the distribution of contact pressures shifted from the medial half of the joint to the lateral half of the joint in all but one specimen. Conversely, after deltoid ligament repair the distribution of pressure remain concentrated in the medial half of the joint, like the native state. Conclusion: We did not find a significant difference in overall mean ankle contact pressures between the various tested conditions. However, there can be a significant decrease in the joint contact area and a shift in the distribution of contact pressures within the joint after syndesmosis repair that was not seen after deltoid repair. In fact, with a deltoid repair alone, the distribution of contact pressures and the joint contact area did not differ significantly from the native state. These changes in contact area and distribution of pressures may affect long-term clinical and radiographic outcomes.

Impact of Weber B Fracture Displacement on Medial Clear Space Volume: How Much Displacement Matters?

Category:Ankle; Sports; TraumaIntroduction/Purpose:Numerous radiographic studies examining Weber B fibular fractures demonstrate no change in tibiotalar contact area until the deltoid ligament is disrupted. In contrast, more recent studies using weight-bearing CT scan (WBCT) and 3D volume analysis suggest that medial clear space (MCS) volume can in fact increase in the setting of a Weber B fibular fracture even if initial radiographs are reassuring, possibly due to a loss of fibular buttress. This study aims to evaluate the ability of WBCT to quantify the impact of isolated Weber B fractures on MCS volume (3D), as well as understand the implication of increasing fibular displacement among patients with symmetric MCS distance (1D) on initial radiographs.Methods:The study group included 18 patients with unilateral Weber B ankle fractures who underwent preoperative bilateral foot and ankle WBCT. The control group consisted of 60 patients without ankle injury who underwent similar imaging.Measurements on WBCT images included: 1) MCS distance, 2) syndesmotic area, 3) anterior, middle, and posterior distal tibiofibular distance, 4) fibular rotation, 5) distance from fibular tip to plafond, and 6) fibular fracture displacement. Additionally, volumetric measurements included: 1) MCS volume 2) syndesmotic joint volume from the tibial plafond extending to 3cm and 5 cm proximally, and 3) lateral clear space volume were calculated. Area under the receiver operating characteristic (ROC) curve analysis and Delong test were used, and optimal cutoff values to distinguish between stable and unstable Weber B fractures without syndesmotic instability and MCS widening were determined using Youden's J statistic.Results:Among patients with unilateral Weber B ankle fractures, all WBCT measurements showed no side-to-side difference in any parameter, except MCS volume (p-values <0.001). When compared to the uninjured side, fibular displacement up to 2cm and up to 4cm increased lateral MCS volume by 37.1% (0.23cm3) and 51.8% (0.3cm3), respectively. Based on ROC analysis and Youden's J statistic, the optimal threshold for differentiating stable from an unstable Weber B fracture was 2.3 mm of displacement (AUC 0.81; sensitivity 77.8%; specificity 80%). The control group showed no difference in any of the measurements between the two sides.Conclusion:When using WBCT, 3D MCS volume increases significantly with Weber B fibular fractures, even if 1D distance measurements at the medial clear space are reassuring. This is especially true with fibular displacement greater than 2.3mm and may have an important role in the management of SER II ankle fractures.

The Effects of Fibular Malrotation on Tibiotalar Contact Area and Peak Pressure Distributions in Weber B Ankle Fractures

Category:Basic Sciences/Biologics; Ankle; Hindfoot; TraumaIntroduction/Purpose:Decreased tibiotalar joint contact area (CA) and increased peak pressure (PP) following rotational ankle fractures may predispose the development of post-traumatic osteoarthritis. Previous studies have highlighted the effects of lateral talar translation on tibiotalar joint congruity. However, debate remains regarding surgical indications in minimally displaced (< 2mm of clear space widening), but potentially malrotated ankle fractures. Malrotation of the talus and fibula are poorly visualized on plain radiographs, thus their impact on ankle joint contact mechanics has not been determined. The aim of this project is to understand the effects of fibular malrotation on tibiotalar joint CA and PP distributions using an axially loaded cadaveric model.We hypothesized that fibular malrotation would result in decreased contact area and increased peak pressures within the tibiotalar joint.Methods:Ten fresh frozen cadaveric lower extremity specimens transected mid-tibia were dissected free of soft tissues surrounding the ankle, sparing the ligaments. The proximal tibia and fibula were potted in quick drying cement for rigid mounting on a MTS machine. A pressure sensing element (TekScan model 5033) was inserted into the tibiotalar joint and used to measure CA (cm2) and PP (MPa). An axial load of 686 N was applied through the tibia and fibula, followed by a 147 N load via the Achillies tendon at mid-stance position, 15o dorsiflexion and 15o plantarflexion. The samples were first tested in the native condition, a Weber B ankle fracture was simulated and then re-tested in an anatomically fixed state, and a malrotated state. Malrotation was achieved by externally rotating the talus and shortening the fibula along the fracture by the maximal amount that would allow bony apposition along the fracture line (usually 5-10mm).Results:In the six ankles tested thus far (Figure 1), we have observed small but statistically insignificant (P>0.05) increases in tibiotalar CA at all stance phases following malreduction. Significant (p>0.05) increases in tibiotalar PP were seen mid-stance following a simulated Weber B fracture, and these changes were shown to be greatest in the malreduced state versus the anatomically fixed state (7.21 MPa vs. 6.35 MPa respectively, p = 0.004). Interestingly, similar (p=0.84) decreases tibiotalar PP were shown during plantarflexion following a simulated Weber B fracture fixed in both the anatomically fixed and malreduced state.Conclusion:Our preliminary data supports the notion that significant changes in tibiotalar PP occur following ankle fractures even in an anatomically fixed state. Increases in tibiotalar PP seem to be further amplified following malreduction at specific stance phases. Further data collection is needed to validate these findings, and to determine the role of malrotation as a potential surgical indication for minimally laterally displaced ankle fractures.

A prospective observational study of surgical management of bimalleolar fractures around ankle

Ankle fractures are one of the commonest fracture of lower limb encountered by orthopaedic surgeon. Incidence of ankle fracture has increased in both young and elderly age group; which accounts for 9% of all fractures. The incidence of ankle fractures is approximately 187 per 1 lakh person each year. Sir Robert Jones said “The least well treated and most prone joint to get injured is the ankle joint. Ankle fractures most commonly caused by fall, twisting and sport injuries. Middle and older aged patients presenting with ankle fractures have co-morbidities like diabetes mellitus and obesity. Ankle joint is most commonly injured because of its weight bearing function and role in locomotion. Ankle fracture are likely to cause lifelong complication like early degenerative arthritis, instability and pain; therefore understanding of biomechanics of ankle joint, proper fixation technique and findings of outcome studies is utmost important. Experimentally shown by Paul L. Ramsay, about 1mm lateral shift in talus, produces about 42% of decrease in tibio-talar contact area. Therefore the reduction should be ideal anatomically, which can be attained by open reduction and internal fixation. The operative procedure preserve the anatomy and weight bearing function of ankle joint and also helps in easier rehabilitation without a cast, early mobilization and weight bearing.

Delayed surgical reconstruction of adult ankle malunion by supramalleolar osteotomy

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Malunion of the ankle fractures is a frequent cause of morbidity. The normal ankle is essential for normal mobility. Ankle malunion is a common cause of chronic pain, posttraumatic arthritis and work related disability. The importance of proper treatment of these injuries cannot be over emphasised. Lateral talar shift of only 1 mm decreases the tibio-talar contact area by 42%. This increases contact pressure stress by 36%. Together with instability this results in chronic pain and arthrosis.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; A retrospective study was designed to review 21 cases reconstructed after several months to many years of neglect prior to this review. The case reports, operative records, X-rays and CT scans of the patients in addition to physical examination findings were analysed. &lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Good to excellent results were achieved using basic orthopaedic instrument and implants. This technique is an important armamentarium to orthopaedic surgeons in the third world where late presentation of ankle fractures is common and ideal implants are scanty.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; Good to excellent radiological and functional outcomes are achievable with proper preoperative planning and corrective supramalleolar osteotomies.&lt;/p&gt;

Screw distraction technique for gaining fibular length

Shortening of fibular length is most commonly secondary to fracture, especially in cases of malreduction, malunion or nonunion. In the presence of deltoid ligament incompetence, a shortened fibula causes lateral talar shift, widening of the mortise, decreased tibiotalar contact area and increased incidence of post-traumatic arthrosis. Restoring fibular length is important for normal anatomic relationships and kinematics of the ankle joint. While several techniques have been described for restoring length, some limitations exist.We describe an alternative surgical technique that is straightforward and reproducible that allows for restoration of fibular length and rotation.

The Effect of Achilles Tendon Loading on Ankle Joint Contact Area and Peak Pressure

Category: Ankle Introduction/Purpose: Increased tibiotalar peak pressure (PP) and decreased contact area (CA) following ankle fracture are associated with the development of post-traumatic osteoarthtritis. Lateral talar translation of just 1 mm has been shown to decrease CA by 42%. The impact of talar malalignment in other directions on ankle joint contact pressures (AJCP) are not well understood. The majority of research on AJCP has utilized cadaveric models in which body weight is simulated with an axial load applied through the tibia. This model does not account for Achilles tendon - which transmits the largest tendon force in the body during weight bearing. This study aimed to determine the effects of Achilles tendon loading on tibiotalar CA and PP in an axially loaded cadaver model at different ankle flexion angles. Methods: Ten fresh frozen cadaveric lower extremity specimens transected mid-tibia were dissected free of soft tissues surrounding the ankle, sparing the ligaments. The proximal tibia and fibula were potted in quick drying cement for rigid mounting on a MTS machine. A pressure sensing element (TekScan KScan model 5033) was inserted into the tibiotalar joint and used to measure CA (cm2) and PP (MPa). An axial load of 686 N was applied through the tibia and fibula, followed by a 350 N load via the Achilles tendon to simulate mid-stance conditions. Measurements were taken at neutral position, 15 degrees of dorsiflexion and 15 degrees of plantarflexion, with and without Achilles load. The effects of Achilles load and ankle flexion angle on CA and PP were analyzed using a 2x3 ANOVA. Bonferroni post-hoc adjustments were used for multiple comparisons. Level of statistical significance was set at p &lt; 0.05. Results: ANOVA revealed significant main effects of ankle flexion on contact area and peak pressures (Table 1). Contact area was significantly lower for 15 degrees of plantarflexion than neutral and 15 degrees of dorsiflexion (p &lt; 0.001). In addition, peak pressure was significantly higher for 15 degrees of plantarflexion than neutral and 15 degrees of dorsiflexion. ANOVA also indicated that contact area and peak pressure were significantly higher with Achilles load than without (p &lt; 0.001). No interaction effects were found. Conclusion: The applied Achilles tendon load significantly altered tibiotalar PP in an axially loaded cadaver model. On the other hand, changes in CA with Achilles load were found to be minimal (~1.8%). We also found that the greatest PP and smallest CA occured during plantar flexion. This observation can be explained by a difference in width between the anterior and posterior talus. While the results of this study demonstrate the importance of Achilles tendon load on tibiotalar measurements, further studies investigating the effects of additional factors such as loading techniques are warranted to improve the physiological accuracy of cadaver models.

Talar Motion is Constrained by Tricortical Screw Fixation of the Syndesmosis: A Cadaveric Robotic Study

Objectives:High ankle sprains are a common injury that occur in up to 11% of ankle sprains. Injury to the structures of the syndesmosis, the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), and interosseous membrane (IOM), has been shown to be predictive of residual symptoms after ankle injury. When the syndesmosis is unstable, it is typically treated surgically with cortical screw fixation or suture button fixation. Studies have shown that a 1 mm lateral shift of the talus relative to the tibia significantly decreases the tibiotalar contact area by 42%. Thus, restoring the tibiotalar kinematics to those of the intact ankle with appropriate fixation is important to avoid accelerated tibiotalar arthritis. The objective of this study was to quantify tibiotalar joint motion after syndesmotic screw and suture button fixation compared to the intact ankle.Methods:Nine fresh-frozen human cadaveric specimens (mean age 60 yrs.; range 38-73 yrs.) were tested using a six degree-of-freedom robotic testing system. The subtalar joint was fused and the tibia and calcaneus were rigidly fixed to a robotic manipulator, while fibular length was maintained and fibular motion was unconstrained. Talar motion with respect to the tibia was measured using the robotic testing system. A 5 Nm external rotation moment and 5 Nm inversion moment were applied independently to the ankle at 0°, 15°, and 30° plantarflexion and 10° dorsiflexion. Outcome variables included talar medial-lateral (ML) translation, anterior-posterior (AP) translation, and internal/external rotation relative to the tibia in the following syndesmosis states: 1) intact, 2) AITFL transected, 3) AITFL, PITFL, and IOM transected, 4) 3.5 mm cannulated tricortical screw fixation, and 5) suture button fixation. An ANOVA with a post-hoc Tukey analysis was performed for statistical analysis. Statistical significance was set at p < 0.05.Results:There were significant differences in ML translation of the talus relative to the tibia between the tricortical screw fixation and the intact ankle. These significant changes were only present during states with no loads applied. Tricotical screw fixation resulted in a significant decrease in medial translation of the talus compared to the intact ankle at 30° plantarflexion and increased lateral translation at 0° flexion (p < 0.05) (Figure 1). The talus moved 1.1 mm less medially at 30° plantarflexion and 0.4 mm more laterally at 0° flexion in the tricortical screw fixation state compared to the intact ankle. The total medial translation of the talus relative to the tibia during plantarflexion decreased from 1.1 mm to only 0.4 mm. No significant difference in AP translation or external rotation of the talus existed between the tricortical screw fixation and the intact ankle. No significant differences existed in translation or rotation of the talus between the suture button fixation and intact ankle at any ankle positions.Conclusion:Suture button fixation restored tibiotalar motion in all planes, with no significant differences compared to the intact ankle. Tricortical screw fixation significantly increased lateral shift of the talus in a neutral ankle position and constrained motion during plantarflexion compared to the intact ankle, which can lead to accelerated tibiotalar arthritis. Thus, physicians should consider hardware removal after tricortical screw fixation for syndesmotic repair to avoid post-traumatic arthritis.Figure 1.Medial-lateral translation of the talus relative to the tibia with no loads applied. (Mean ± Standard Deviation), *p < 0.05

Screw Distraction Technique For Gaining Fibular Length

Category: Trauma Introduction/Purpose: A shortened fibula may be caused by several conditions like tumors, premature closure of the growth plate and most frequently, malunion. Biomechanically a shortened fibula causes a lateral shift of the talus, widening of the ankle mortise, decreased tibiotalar contact area and eventually could lead to osteoarthritis. Even in a posttraumatic scenario, with moderate or severe osteoarthritis, fibular lengthening has shown to be beneficial in terms of pain reduction and improved function.Several osteotomies have been described with their advantages and disadvantages in terms of technical difficulty, need for bone graft and the ability to correct length and rotation.We present an easy and reproducible surgical technique on a case, that allow restoring length and rotation independently and it does not require complex distractor devices. Methods: Case report: A 34 year old female patient who presented 8 months status post initial open reduction internal fixation (ORIF). She developed a fibular nonunion, broken distal fixation with a shortened fibula and non-anatomic mortise and presented for revision surgery.Surgical technique: The fibula is exposed in standard fashion. A fully-threaded cortical screw is placed across the tibia, distal to the fibula fracture and parallel to the plafond. Next, a second screw is placed into the fibula bicortically from anterior to posterior and approximately 12 mm distal to the tibial screw. A toothed laminar spreader is then placed in-between the screws and distracted resulting in a lengthening of the fibula. A 2 mm Kirschner wire is placed to hold reduction once fibular length is restored and ORIF continues in standard fashion. Results: The technique we present has several advantages. The technique is straightforward, easy to reproduce, and cost effective. Since the anchoring points used for distraction are not both in the fibula, rotation is not implicitly locked in as in the case when both anchoring points are in the fibula, allowing for independent and progressive adjustment of both length and rotation. There is also less risk of proximal migration of the fibular head as no force is applied directly to the proximal fibula. There is also less risk of proximal migration of the fibular head as no force is applied directly to the proximal fibula. Conclusion: Fibular lengthening can achieve improved function, pain relief and decrease the risk of osteoarthritis in selected patients. Several techniques with different degrees of difficulty have been described to treat this condition, but most are not versatile enough in correcting the length and rotation independently. The technique that we present has the advantage of correcting the length and rotation as needed, without requiring complex devices.

Deltoid Ligament Reconstruction

Category: Ankle, Sports Introduction/Purpose: Deltoid Ligament Reconstruction: Clinical Outcomes. The Deltoid ligament is a primary ligamentous stabilizer of the ankle joint. Deltoid ligament insufficiency has been demonstrated to decrease tibiotalar contact area by around 43%. The authors report on their clinical outcomes of repairing deltoid ligament in the acute and chronic settings. Methods: 61 Deltoid ligament reconstructions in the acute setting and 24 in the chronic setting (of which 7 had an additional medial displacing calcaneal osteotomy) were followed up over a period of 1 year. This study was performed in St. Vincent’s University Hospital - Dublin, Republic of Ireland (Teaching hospital for University College Dublin). Results: 100% of patients receiving deltoid ligament reconstruction in the acute setting returned to sports within 3.5 months. 1.8% had excessive scaring requiring arthroscopic debridement. In the chronic setting, 95.8% of patients returned to sports at 6 months. Conclusion: Deltoid ligament reconstruction is associated with favorable outcomes and return to sports.

Weightbearing Radiographs and stability in SER II - IV Ankle Fractures

Category: Ankle, Sports, Trauma, Radiography, Weber B Fracture Introduction/Purpose: SER lateral malleolar fractures are common. The assessment of the stability of the ankle fracture is crucial for decision making of treatment which is associated with the integrity of the deltoid ligament (SERII-III). Slight talar shift can lead to extensive decrease of tibio-talar contact area (Ramsey 1999). Several clinical tests have been proposed of which static weightbearing radiography is used to measure the lateral talar shift with the medial clear space to detect medial instability (SERIV). However, the correlation of a stable ankle joint under weightbearing load with the structural integrity of the deltoid ligament has not been shown yet which we want to investigate. Methods: 17 patients with lateral malleolar fractures were investigated who underwent an MRI and weightbearing radiography examination. In the MRI, the deep deltoid ligament was assessed as intact, partial und complete rupture. The medial clear space was measured - distance between the lateral border of the medial malleolus and the medial border of the talus at the level of the talar dome (millimeter). Results: 7 patients suffered from deep deltoid ligament rupture (4 partial; 3 complete).The medial clear space in patients with intact deep deltoid ligament was 2.96+0.41 mm in mean, in partial rupture 2.8+0.38 mm, in complete rupture 3.43+0.23 mm. When counting the complete and partial ruptures together the mean was 3.07+0.45 mm and in partial ruptures plus the intact ones 2.91+0.40 mm. Conclusion: Our results show no significant correlation between the medial clear space and the integrity of the deep deltoid ligament (figure1). A negative weightbearing radiograph does not exclude deep deltoid ligament rupture. This fact might indicate the importance of the intrinsic stability provided by the osseous contour of the highly congruent ankle joint. In our opinion, malleolar fracture with deep deltoid ligament rupture (SERIV) can therefore be treated conservatively as long as ankle stability is provided under physiological load.

Radiography in in SER II - IV Ankle Fractures

Category: Ankle, Sports, Trauma Introduction/Purpose: SER lateral malleolar fractures are common. The assessment of the stability of the ankle fracture is crucial for decision making of treatment which is associated with the integrity of the deltoid ligament (SERII-III). Slight talar shift can lead to extensive decrease of tibio-talar contact area (Ramsey 1999). Several clinical tests have been proposed of which static weightbearing radiography is used to measure the lateral talar shift with the medial clear space to detect medial instability (SERIV). However, the correlation of a stable ankle joint under weightbearing load with the structural integrity of the deltoid ligament has not been shown yet which we want to investigate. Methods: 17 patients with lateral malleolar fractures were investigated who underwent an MRI and weightbearing radiography examination. In the MRI, the deep deltoid ligament was assessed as intact, partial und complete rupture. The medial clear space was measured - distance between the lateral border of the medial malleolus and the medial border of the talus at the level of the talar dome (millimeter). Results: 7 patients suffered from deep deltoid ligament rupture (4 partial; 3 complete).The medial clear space in patients with intact deep deltoid ligament was 2.96+0.41 mm in mean, in partial rupture 2.8+0.38 mm, in complete rupture 3.43+0.23 mm. When counting the complete and partial ruptures together the mean was 3.07+0.45 mm and in partial ruptures plus the intact ones 2.91+0.40 mm. Conclusion: Our results show no significant correlation between the medial clear space and the integrity of the deep deltoid ligament (figure1). A negative weightbearing radiograph does not exclude deep deltoid ligament rupture. This fact might indicate the importance of the intrinsic stability provided by the osseous contour of the highly congruent ankle joint. In our opinion, malleolar fracture with deep deltoid ligament rupture (SERIV) can therefore be treated conservatively as long as ankle stability is provided under physiological load.

The Role of Fluid Dynamics in Distributing Ankle Stresses in Anatomic and Injured States.

In 1976, Ramsey and Hamilton published a landmark cadaveric study demonstrating a dramatic 42% decrease in tibiotalar contact area with only 1 mm of lateral talar shift. An increase in maximum principal stress of at least 72% is predicted based on these findings though the delayed development of arthritis in minimally misaligned ankles does not appear to be commensurate with the results found in dry cadaveric models. We hypothesized that synovial fluid could be a previously unrecognized factor that contributes significantly to stress distribution in the tibiotalar joint in anatomic and injured states. As it is not possible to directly measure contact stresses with and without fluid in a cadaveric model, finite element analysis (FEA) was employed for this study. FEA is a modeling technique used to calculate stresses in complex geometric structures by dividing them into small, simple components called elements. Four test configurations were investigated using a finite element model (FEM): baseline ankle alignment, 1 mm laterally translated talus and fibula, and the previous 2 bone orientations with fluid added. The FEM selected for this study was the Global Human Body Models Consortium-owned GHBMC model, M50 version 4.2, a model of an average-sized male (distributed by Elemance, LLC, Winston-Salem, NC). The ankle was loaded at the proximal tibia with a distributed load equal to the GHBMC body weight, and the maximum principal stress was computed. All numerical simulations were stable and completed with no errors. In the baseline anatomic configuration, the addition of fluid between the tibia, fibula, and talus reduced the maximum principal stress computed in the distal tibia at maximum load from 31.3 N/mm2 to 11.5 N/mm2. Following 1 mm lateral translation of the talus and fibula, there was a modest 30% increase in the maximum stress in fluid cases. Qualitatively, translation created less high stress locations on the tibial plafond when fluid was incorporated into the model. The findings in this study demonstrate a meaningful role for synovial fluid in distributing stresses within the ankle that has not been considered in historical dry cadaveric studies. The increase in maximum stress predicted by simulation of an ankle with fluid was less than half that projected by cadaveric data, indicating a protective effect of fluid in the injured state. The trends demonstrated by these simulations suggest that bony alignment and fluid in the ankle joint change loading patterns on the tibia and should be accounted for in future experiments. Synovial fluid may play a protective role in ankle injuries, thus delaying the onset of arthritis. Reactive joint effusions may also function to additionally redistribute stresses with higher volumes of viscous fluid.

Fluid Dynamics Play a Role In Distributing Ankle Stresses in Anatomic and Injured States

Category: Basic Sciences/Biologics Introduction/Purpose: In 1976, Ramsey and Hamilton published a landmark cadaveric study demonstrating a dramatic 42% decrease in tibiotalar contact area with only 1 mm of lateral talar shift. An increase in principal stress of at least 72% is predicted based on these findings though the delayed development of arthritis in minimally misaligned ankles does not appear to be commensurate with the results found in dry cadaveric models. We hypothesize that synovial fluid is a previously unrecognized factor that contributes significantly to stress distribution in the tibiotalar joint in anatomic and injured states. Methods: As it is not possible to directly measure contact stresses with and without fluid in a cadaveric model, finite element analysis (FEA) was employed for this study. FEA is a modeling technique used to calculate stresses in complex geometric structures by dividing them into small, simple components called elements. Four test groups were investigated utilizing a finite element model (FEM): baseline ankle alignment, 1 mm laterally translated talus and fibula, and the previous two bone orientations with fluid added. The FEM selected for this study was the Global Human Body Models Consortium (GHBMC) M50 version 4.2, a validated model of an average sized male. The ankle was loaded at the proximal tibia with a distributed load equal to the GHBMC body weight and first principal stress (which is also the maximum principal stress) was computed. Results: All simulations were stable and completed with no errors. In the baseline anatomic configuration, the addition of fluid between the tibia, fibula and talus reduced the maximum principal stress measured in the distal tibia at maximum load from 31.3 N/mm2 to 11.5 N/mm2. Following 1 mm lateral translation of the talus and fibula there was a modest 30% increase in the maximum stress in fluid cases. Qualitatively, translation created less high stress locations on the tibial plafond when fluid was incorporated in the model (Figure 1). Conclusion: The findings in this study demonstrate a potential role for synovial fluid in distributing stresses within the ankle that has not been considered in historical dry cadaveric studies. The increase in maximum stress predicted by simulation of an ankle with fluid is less than half that projected by cadaveric data, indicating a protective effect of fluid in the injured state. The trends demonstrated by these simulations suggest that bony alignment and fluid in the ankle joint change loading patterns on the distal tibia and should be accounted for in future experiments.

The effect of distal tibial rotation during high tibial osteotomy on the contact pressures in the knee and ankle joints.

Intraoperative fracture of the lateral cortex fractures of the tibia is a potential complication of high tibial osteotomy (HTO), which may result in inadequate rotational alignment of the distal tibia. Our aim was to determine how rotational malalignment of the distal tibial segment distal would affect intraarticular contact pressure distribution in the knee and ankle joints. A medial, L-shaped opening-wedge HTO was performed on seven human lower body specimens. A stainless steel device with integrated load cell was used to axially load the leg. Pressure-sensitive sensors were used to measure intraarticular contact pressures. Intraoperative changes in alignment were monitored in real time using computer navigation. Measurements were performed in the native knee alignment, after 10° and 15° of alignment correction and with the distal tibia fixed at 15° of external rotation. Moderate-to-large alignment changes after medial opening-wedge HTO resulted in a shift in intraarticular contact pressures from the medial compartment of the knee towards the lateral compartment. However, fixation of the distal tibial segment at 15° of external rotation neutralized this intended beneficial effect. In the ankle, external rotation of the distal tibia also caused a reduction in contact pressures and tibiotalar contact area. Malrotation of the distal tibial fragment negates the intended effect of offloading the diseased compartment of the knee, with the contact pressures remaining similar to those of the native knee. Furthermore, malrotation leads to abnormal ankle contact pressures. Care should be taken to ensure appropriate rotational alignment of the distal tibial segment during intraoperative fixation of HTO procedures.

Contribution of the medial malleolus to tibiotalar joint contact characteristics.

Isolated medial malleolus fractures are typically treated operatively to minimize the potential for articular incongruity, instability, nonunion, and posttraumatic arthritis. The literature, however, has not clearly demonstrated inferior outcomes with conservative treatment of these injuries. This study measured the effects of medial malleolus fracture and its resultant instability on tibiotalar joint contact characteristics. We hypothesized that restoration of anatomical alignment and stability through fixation would significantly improve contact characteristics. A Tekscan pressure sensor was inserted and centered over the talar dome in 8 cadaveric foot and ankle specimens. Each specimen was loaded at 700 N in multiple coronal and sagittal plane orientations. After testing fractured samples, the medial malleolus was anatomically fixed before repeat testing. Contact area and pressure were analyzed using a 2-way repeated-measure ANOVA. In treated fractures, contact areas were higher, and mean contact pressures were lower for all positions. These differences were statistically significant in the majority of orientations and approached statistical significance in pure plantarflexion and pure inversion. Decreases in contact area varied from 15.1% to 42.1%, with the most dramatic reductions in positions of hindfoot eversion. These data emphasize the importance of the medial malleolus in maintaining normal tibiotalar contact area and pressure. The average decrease in contact area after simulated medial malleolar fractures was 27.8% (>40% in positions of hindfoot eversion). Such differences become clinically relevant in cases of medial malleolar nonunion or malunion. Therefore, we recommend anatomical reduction and fixation of medial malleolus fractures with any displacement. Therapeutic Level V-Cadaveric Study.