Ankle Joint Pressure in Supination–External Rotation Injuries: A Biomechanical Study in an Unrestrained Cadaver Model

Background Previous biomechanical studies simulating supination–external rotation (SER) IV injuries revealed different alterations in contact area and peak pressure. We investigated joint reaction forces and radiographic parameters in an unrestrained, more physiological setup. Methods Twelve lower leg specimens were destabilized stepwise by osteotomy of the fibula (SER II) and transection of the superficial (SER IVa) and the deep deltoid ligament (SER IVb) according to the Lauge-Hansen classification. Sensors in the ankle joint recorded tibio-talar pressure changes with axial loading at 700 N in neutral position, 10° of dorsiflexion, and 20° of plantarflexion. Radiographs were taken for each step. Results Three of 12 specimen collapsed during SER IVb. In the neutral position, the peak pressure and contact area changed insignificantly from 2.6 ± 0.5 mPa (baseline) to 3.0 ± 1.4 mPa (SER IVb) ( P = .35) and from 810 ± 42 mm2 to 735 ± 27 mm2 ( P = .08), respectively. The corresponding medial clear space (MCS) increased significantly from 2.5 ± 0.4 mm (baseline) to 3.9 ± 1.1 mm (SER IVb) ( P = .028). The position of the ankle joint had a decisive effect on contact area ( P = .00), center of force ( P = .00) and MCS ( P = .01). Conclusion Simulated SER IVb injuries demonstrated radiological, but no biomechanical changes. This should be considered for surgical decision making based on MCS width on weightbearing radiographs. Levels of Evidence: Not applicable. Biomechanical study

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Ankle Joint Pressure in Supination-External Rotation Injuries: A Dynamic Biomechanic Cadaveric Study

Foot & Ankle Orthopaedics ◽

10.1177/2473011420s00306 ◽

2020 ◽

Vol 5 (4) ◽

pp. 2473011420S0030

Author(s):

Fabian Krause ◽

Ivan Zderic ◽

Angela Seidel ◽

Boyko Gueorguiev ◽

Marc C. Attinger ◽

...

Keyword(s):

Operative Treatment ◽

Contact Area ◽

Peak Pressure ◽

External Rotation ◽

Clinical Results ◽

Deltoid Ligament ◽

Type Ii ◽

Type Iv ◽

Joint Contact ◽

Supination External Rotation

Category: Ankle; Basic Sciences/Biologics; Trauma Introduction/Purpose: In isolated lateral malleolar fractures of the supination-external rotation (SER) type and competent medial stabilizers (type II and III), non-operative treatment has yielded excellent outcome. With complete rupture of the deltoid ligament (SER type IV) fracture instability increases substantially. The rationale for operative treatment of SER type IV fractures is based upon good clinical results and previous biomechanical studies. A significant reduction of the ankle contact area that however is caused by an artificially forced lateralization of the talus in the ankle mortise has been demonstrated. Presumed resultant elevated joint contact stresses are thought to lead to ankle arthritis in the longterm. Methods: In 12 lower leg specimen SER type injuries were simulated by gradual bony and ligamentous destabilization of the ankle from lateral to medial according to the mechanism of injury as described by Lauge and Hansen. High-resolution pressure sensors placed in the ankle joint recorded tibio-talar pressure changes at physiologic weightbearing (700N) in three positions (plantigrade, 10° dorsiflexion and 20° plantarflexion). Results: With increasing instability changes of the ankle kinematics were seen in SER II and III fractures with the same trend also in SER IV lesions. In the plantigrade position, the medial clear space (MCS) increased significantly from an average of 2.5+-0.4mm (no fracture) to 3.9+-1.1mm (SER type IV fracture). However, the corresponding peak pressure increased only slightly from 2.6+- 0.5 mPa to 3.0+-1.4 mPa on average, and the contact area decreased slightly from 810+-42 mm2 to 735+-27mm2 on average representing a non-significant reduction of only 9% of the contact area (p=0.08) after the deep deltoid ligament was completely dissected.The comparison of the results in plantigrade and plantarflexed position revealed substantial differences for MCS, contact area and center of force. Conclusion: Under physiologic load SER type IV isolated lateral malleolar fracture with completely disrupted deep deltoid ligament led to a significant increase of the MCS, but neither to a significant decrease of the of the joint contact area nor significant increase of peak pressure. Clinical Relevance: The findings of this biomechanical study support the recently reported good clinical results of non-operative treatment of SER type II to IV fractures.

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Invisible Injuries in Ankle Fractures

Foot & Ankle Orthopaedics ◽

10.1177/2473011417s000121 ◽

2017 ◽

Vol 2 (3) ◽

pp. 2473011417S0001

Author(s):

Robin Blom ◽

Markus Knupp ◽

Beat Hintermann ◽

Sjoerd Stufkens

Keyword(s):

Ankle Instability ◽

External Rotation ◽

Plantar Flexion ◽

Axial Loading ◽

Ankle Fractures ◽

Deltoid Ligament ◽

Neutral Position ◽

Need For Treatment ◽

Ligament Rupture ◽

Fresh Frozen

Category: Ankle, Trauma, Biomechanical Introduction/Purpose: Ankle fractures are often associated with ligamentous injuries of the distal tibiofibular syndesmosis, the deltoid ligament and are predictive of ankle instability, early joint degeneration and long-term ankle dysfunction. Detection of ligamentous injuries and the need for treatment remain subject of ongoing debate. In the classic article of Boden it was made clear that injuries of the syndesmotic ligaments were of no importance in the absence of a deltoid ligament rupture. Even in the presence of a deltoid ligament rupture, the interosseous membrane withstood lateralization of the fibula in fractures up to 4.5 mm above the ankle joint. Generally, syndesmotic ligamentous injuries are treated operatively by temporary fixation performed with positioning screws. But do syndesmotic injuries need to be treated operatively at all? Methods: The purpose of this biomechanical cadaveric study was to investigate the relative movements of the tibia and fibula, under normal physiological conditions and after sequential sectioning of the syndesmotic ligaments. Ten fresh-frozen below-knee human cadaveric specimens were tested under normal physiological loading conditions. Axial loads of 50 Newton (N) and 700 N were provided in an intact state and after sequential sectioning of the following ligaments: anterior-inferior tibiofibular (AITFL), posterior-inferior tibiofibular (PITFL), interosseous (IOL), and whole deltoid (DL). In each condition the specimens were tested in neutral position, 10 degrees of dorsiflexion, 30 degrees of plantar flexion, 10 degrees of inversion, 5 degrees of eversion, and externally rotated up to 10 Nm torque. Finally, after sectioning of the deltoid ligament, we triangulated Boden’s classic findings with modern instruments. We hypothesized that only after sectioning of the deltoid ligament; the lateralization of the talus will push the fibula away from the tibia. Results: During dorsiflexion and external rotation the ankle syndesmosis widened, and the fibula externally rotated after sequential sectioning of the syndesmotic ligaments. After the AITFL was sectioned the fibula starts rotating externally. However, the external rotation of the fibula significantly reduced when the external rotation torque was combined with axial loading up to 700 N as compared to the external rotation torque alone. The most relative moments between the tibia and fibula were observed after the deltoid ligament was sectioned. Conclusion: Significant increases in movements of the fibula relative to the tibia occur when an external rotation torque is provided. However, axial pressure seemed to limit external rotation because of the bony congruence of the tibiotalar surface. The AITFL is necessary to prevent the fibula to rotate externally when the foot is rotating externally. The deltoid ligament is the main stabilizer of the ankle mortise.

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

Foot & Ankle Orthopaedics ◽

10.1177/2473011418s00303 ◽

2018 ◽

Vol 3 (3) ◽

pp. 2473011418S0030

Author(s):

L. Daniel Latt ◽

Alfonso Ayala ◽

Samuel Kim ◽

Jesus Lopez

Keyword(s):

Achilles Tendon ◽

Ankle Joint ◽

Contact Area ◽

Axial Load ◽

Peak Pressure ◽

The Body ◽

Neutral Position ◽

Joint Contact ◽

Axially Loaded ◽

The Impact

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 < 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 < 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 < 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.

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Systematic Review of Stress Radiographic Modalities Stability Assessment in Supination External Rotation Ankle Fractures

Foot & Ankle Orthopaedics ◽

10.1177/2473011419890861 ◽

2019 ◽

Vol 4 (4) ◽

pp. 247301141989086

Author(s):

Sohail Yousaf ◽

Alan Saleh ◽

Aashish Ahluwalia ◽

Shahnawaz Haleem ◽

Zara Hayat ◽

...

Keyword(s):

Systematic Review ◽

Ankle Joint ◽

External Rotation ◽

Imaging Modality ◽

Ankle Fractures ◽

Deltoid Ligament ◽

Stress Radiographs ◽

Clear Space ◽

Standard Radiographs ◽

Supination External Rotation

Background: Isolated distal fibular fractures resulting from supination external rotation (SER) injuries without evidence of obvious talar shift on standard radiographs present a diagnostic dilemma for clinicians. The status of the deep deltoid ligament, the main stabilizer of the ankle joint, is assessed by an increase in medial clear space (MCS) on radiographs. Therefore, these injuries can be either stable or unstable. In recent years, considerable clinical and research efforts have been made to determine ankle stability following SER fracture. The purpose of this systematic review was to evaluate and compare the role of different stress radiograph modalities in assessing stability of the ankle with SER fractures with no obvious talar subluxation on standard radiographs. Methods: The electronic databases MEDLINE, EMBASE, Ovid, Cochrane Central, CINAHL, and Google Scholar were searched from January 2000 to January 2018 to identify literature relating to radiologic assessment of stability of SER ankle fractures. Results: Our literature search revealed 10 peer-reviewed articles that fulfilled inclusion criteria. This yielded a total of 698 patients. The systematic review found 3 broad categories of radiographic investigations in the assessment of ankle joint stability: external rotation (ER) stress radiographs, gravity stress views (GSV), and weightbearing (WB) radiographs. Proponents of WB radiographs have demonstrated how axial load can normalize ankle joint alignment in cases of proven instability. There was a consistently high grade of evidence for using a medial clear space (MCS) value of more than 4 to 5 mm to indicate an unstable ankle following SER fracture. Conclusion: In conclusion, the results of this systematic review support an MCS value of less than 4 to 5 mm as a good indicator of stability, regardless of choice of stress imaging modality. These patients can be allowed early weightbearing with expected good functional outcomes. Recent published literature favors WB stress radiographs as a reliable and safe technique for assessing stability in SER ankle fractures. However, it should be kept in mind that this is based on studies with relatively low grades of evidence. Level of Evidence: Level II, systematic review of variable quality studies.

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Tibiotalar Joint Dynamics: Indications for the Syndesmotic Screw—A Cadaver Study

Foot & Ankle ◽

10.1177/107110079301400308 ◽

1993 ◽

Vol 14 (3) ◽

pp. 153-158 ◽

Cited By ~ 101

Author(s):

William C. Burns ◽

Karanvir Prakash ◽

Robert Adelaar ◽

Armaria Beaudoin ◽

William Krause

Keyword(s):

Contact Area ◽

Peak Pressure ◽

External Rotation ◽

Ankle Injuries ◽

Deltoid Ligament ◽

Tibiotalar Joint ◽

Syndesmotic Screw ◽

Joint Dynamics ◽

Complete Disruption ◽

Pronation External Rotation

Pronation-external rotation ankle injuries involve varying degrees of disruption of the syndesmotic ligaments. The loss of ligament support and alteration in the stability of the mortise have been postulated to lead to an increase in joint reactive forces and traumatic arthritis. The purpose of this study was to determine the changes in tibiotalar joint dynamics associated with syndesmotic diastasis as a result of the sequential sectioning of the syndesmotic ligaments to simulate a pronation-external rotation injury. Dissections were conducted on 10 fresh-frozen, knee-disarticulated cadaveric specimens which were then axi-ally loaded in an unconstrained manner. Tibiotalar joint forces were measured at each level of sequential sectioning of the syndesmotic ligaments, the interosseous membrane, and finally the deltoid ligament. Complete disruption of the syndesmosis with the medial structures of the ankle intact resulted in an average syndesmotic widening of 0.24 mm and no significant change in the tibiotalar contact area or the peak pressure. However, deltoid ligament strain increases with sectioning of the syndesmosis. With the addition of deltoid ligament sectioning, there was an average syndesmotic diastasis of 0.73 mm, a 39% reduction in the tibiotalar contact area, and a 42% increase in the peak pressure. In a simulated unconstrained cadaveric model of a pronation-external rotation ankle injury that results in complete disruption of the syndesmosis, if rigid anatomic medial and lateral joint fixation is obtained and the deltoid ligament complex is intact, syndesmotic screw fixation is not required to maintain the integrity of the tibiotalar joint.

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Effect of Distal Tibial Varus and Valgus Deformity on Tibiotalar Joint Contact

Foot & Ankle Orthopaedics ◽

10.1177/2473011420s00253 ◽

2020 ◽

Vol 5 (4) ◽

pp. 2473011420S0025

Author(s):

Zhao Hong-Mou

Keyword(s):

Contact Pressure ◽

Ankle Joint ◽

Contact Area ◽

Peak Pressure ◽

Tibiotalar Joint ◽

Force Center ◽

Fibular Osteotomy ◽

Group I ◽

Joint Contact ◽

Group A

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: To study the effect of different degrees of distal tibial varus and valgus deformities on the tibiotalar joint contact, and to understand the role of fibular osteotomy. Methods: Eight cadaveric lower legs were used for biomechanical study. Nine conditions were included: normal ankle joint (group A), 10° varus (group B), 5° varus (group C), 5° valgus (group D), 10° valgus (group E) with fibular preserved, and 10° varus (group F), 5° varus (group G), 5° valgus (group H), and 10° valgus (group I) after fibular osteotomy. The joint contact area, contact pressure, and peak pressure were tested; and the translation of contact force center was observed. Results: The joint contact area, contact pressure, and peak pressure had no significant difference between group A and groups B to E (P>0.05). After fibular osteotomy, the contact area decreased significantly in groups F and I when compared with group A (P<0.05); the contact pressure increased significantly in groups F, H, and I when compared with group A (P<0.05); the peak pressure increased significantly in groups F and I when compared with group A (P<0.05). There were two main anterior-lateral and anterior-medial contact centers in normal tibiotalar joint, respectively; and the force center was in anterior-lateral part, just near the center of tibiotalar joint. While the fibula was preserved, the force center transferred laterally with increased varus angles; and the force center transferred medially with increased valgus angles. However, the force center transferred oppositely to the medial part with increased varus angles, and laterally with increased valgus angles after fibular osteotomy. Conclusion: Fibular osteotomy facilitates the tibiotalar contact pressure translation, and is helpful for ankle joint realignment in suitable cases.

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