The role of the posterior malleolus in the treatment of unstable upper ankle joint injuries - A biomechanical study

BACKGROUND

This biomechanical study aimed to test if the fixation of the posterior malleolus (PM) only with screws inserted from posterior to anterior (PA) restores stability comparable with the natural condition. The extent of stability was also compared with that of anterior to posterior (AP) screw osteosynthesis (OS) with an additional syndesmotic screw (SS).

METHODS

First, the stability of the upper ankle joint in seven pairs of intact lower legs were examined. Subsequently, half of the lower legs were treated with PA screw fixation of a PM fracture without SS and the other half with AP screw fixation with additional tricortical SS.

RESULTS

PA OS without SS showed significantly more diastasis (p = 0.027). The AP OS with an SS revealed a diastasis that was comparable with the intact condition (p = 0.797). The use of SS led to significantly higher stability compared to OS without SS (p = 0.019).

CONCLUSIONS

The Fixation of the PM alone without an additional syndesmotic screw cannot achieve intact upper ankle stability. Fixation of a PM fracture with an SS helps in nearly achieving the natural condition.

Frontal plane ankle stiffness increases with axial load independent of muscle activity

Ankle sprains are the most common musculoskeletal injury, typically resulting from excessive inversion of the ankle. One way to prevent excessive inversion and maintain ankle stability is to generate a stiffness that is sufficient to resist externally imposed rotations. Frontal-plane ankle stiffness increases as participants place more weight on their ankle, but whether this effect is due to muscle activation or axial loading of the ankle is unknown. Identifying whether and to what extent axial loading affects ankle stiffness is important in understanding what role the passive mechanics of the ankle joint play in maintaining its stability. The objective of this study was to determine the effect of passive axial load on frontal-plane ankle stiffness. We had subjects seated in a chair as an axial load was applied to the ankle ranging from 10% to 50% body weight. Small rotational perturbations were applied to the ankle in the frontal plane to estimate stiffness. We found a significant, linear, 3-fold increase in ankle stiffness with axial load from the range of 0% body weight to 50% body weight. This increase could not be due to muscle activity as we observed no significant axial-load-dependent change in any of the recorded muscle activations. These results demonstrate that axial loading is a significant contributor to maintaining frontal-plane ankle stability, and that disruptions to the mechanism mediating this sensitivity of stiffness to axial loading may result in pathological cases of ankle instability.

Increasing grades of frontal deformities in knee osteoarthritis are not associated with ligamentous ankle instabilities

PURPOSE

Varus or valgus deformities in knee osteoarthritis may have a crucial impact on ankle subtalar range of motion (ROM) and ligamentous stability. The purpose of this study was to assess whether the grade of ankle eversion and inversion rotation stability was influenced by frontal deformities of the knee joint.

METHODS

Patients who were planned to undergo total knee arthroplasty (TKA) were prospectively included in this study. Patients were examined radiologically (mechanical tibiofemoral angle (mTFA), hindfoot alignment view angle (HAVA), anterior distal tibia angle (ADTA)) and clinically (ROM of the knee and ankle joint, foot function index, knee osteoarthritis outcome score). Ankle stability was assessed using an ankle arthrometer (AA) to test inversion/eversion (ie) rotation and anterior/posterior (ap) displacement stability of the ankle joint. Correlations were calculated using Pearson's coefficient, and differences between two independent groups of nonparametric data were calculated using a two-sided Wilcoxon signed rank test.

RESULTS

Eighty-two (varus n = 52, valgus n = 30) patients were included. The preoperative mTFA significantly correlated with the HAVA (Pearson's correlation = - 0.72, p < 0.001). Laxity testing of the ankle demonstrated that in both varus and valgus knee osteoarthritis, higher grades of mTFA did not correlate with the inversion or eversion capacity of the ankle joint. The ADTA significantly correlated with the posterior displacement of the ankle joint (cor = 0.24, p = 0.049).

CONCLUSIONS

This study could not confirm that higher degrees of frontal knee deformities in osteoarthritis were associated with increasing grades of ligamentous ankle instabilities or a reduced ROM of the subtalar joint.

LEVEL OF EVIDENCE

II.

There is a difference in functional ankle stability between different types of footwear in male athletes: A cross-sectional study

CONTEXT

Lateral ankle sprains (LAS) are among the most common injuries in sports, with a poor long - term prognosis due to high chronicity and recurrence rates. Chronic ankle instability (CAI) results up to 40% of people that endured a first - time LAS.

OBJECTIVE

The aim of this study was to compare ankle stability between groups characterised by the use of different types of footwear during their sport activities.

DESIGN

Cross-sectional study.

SETTING

Firm training surface, local sport clubs.

PARTICIPANTS

Fifty - one male subjects were recruited, distributed in four groups based on the type of footwear they use during their sport activities.

MAIN OUTCOME MEASURES

All subjects performed four clinical ankle stability tests, and completed the Dutch version of the Cumberland Ankle Instability Tool (CAIT) and Profile of Mood States (POMS). All clinical ankle stability tests were performed barefoot.

RESULTS

Subjects performing their sport activities barefoot scored better than subjects performing their sport with shoes at the multiple hop test (p=.002 to .047) and executed the figure-of-8 hop test significantly faster than subjects with submalleolar ankle support (AS) (p=.019). Subjects with submalleolar AS and studs showed significantly better results than subjects with supramalleolar AS on the CAIT- score (p=.024, p=.030) and the side- hop test (p=.050, p=.045). They also scored significantly better than subjects with submalleolar AS for the side - hop test (p=.032), foot - lift test (p=.019) and figure-of 8 hop test (p=.011).

CONCLUSION

Barefoot sports performing subjects appear to have better ankle stability compared to subjects performing their sports with shoe support. Subjects performing sports with high AS appear to have worst ankle stability.

LEVEL OF EVIDENCE

Level III, Cross-sectional study.

Individuals with chronic ankle instability exhibit altered ankle kinematics and neuromuscular control compared to copers during inversion single-leg landing

OBJECTIVES

This study compares the ankle kinematics and muscle activities of the individuals with chronic ankle instability (CAI), coper, and control groups in normal and inversion single-leg landings.

DESIGN

cross-sectional study; SETTING: Biomechanics laboratory.

PARTICIPANTS

Physically active adults with CAI (N = 12); and coper (N = 12) and control (N = 12) groups.

MAIN OUTCOME MEASURES

The participants performed normal and inversion single-leg landing. The muscle activity 200 ms before and after landing of the tibialis anterior, the medial gastrocnemius, and the fibularis longus (FL) were recorded. The FL latency, sagittal and frontal co-contraction indexes (CCI), ankle inversion angle at the initial contact, and the maximum inversion angle were recorded.

RESULTS

Significantly longer FL latency, decreased FL muscle activity, frontal CCI, and an increased maximum inversion angle at post-landing were discovered during inversion single-leg landing in the CAI group compared to the coper and control groups. However, no significant difference was observed among the CAI and coper groups during normal single-leg landing.

CONCLUSION

These results suggest prolonged FL latency and altered ankle kinematics suggest an increased risk of recurrent lateral ankle sprains in CAI with inversion single-leg landing.

Finite element analysis of the effect of sagittal angle on ankle joint stability in posterior malleolus fracture: A cohort study

OBJECTIVE

Aim of this study was to establish three-dimensional finite element model of the posterolateral-oblique type of posterior malleolus fracture with different sagittal angle and to explore the effect of sagittal angle on ankle joint stability.

METHODS

CT data of ankle were collected from a normal male volunteer.Established finite element model of the normal ankle and verified its reliability. Five posterior malleolus fracture models with different sagittal angles were established. Finite element analysis(FEA)was carried out to simulate the conditions of vertical loading in neutral position with a total weight of 600 N.Recorded the data and did statistical analyses.

RESULTS

(1) The contact area was 483.55 mm2 and the maximum contact stress was 3.793 MPa in the model of the normal ankle joint. (2) There was a positive correlation between the sagittal angle(SA)and the contact area(CA)(r = 0.925,P < 0.05). Regression equation was CA = 316.755 + 1.749* SA. The correlation between the sagittal angle and the maximum contact stress(MCS)was negative (r = -0.988,P < 0.01). Regression equation was MCS = 5.214-0.018*SA. There was a negative correlation between the sagittal angle of fracture and relative displacement(RD)(r = -0.950,P < 0.05). Regression equation was RD = 1.388-0.009*SA.

CONCLUSION

The greater the sagittal angle of fracture was, The more stable the ankle joint was. The sagittal angle of fracture could be used as a relative index to reflect ankle stability for posterior malleolus fracture.

Function of ankle ligaments for subtalar and talocrural joint stability during an inversion movement - an in vitro study

Background

The lateral ankle ligament complex consisting of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL) and the posterior talofibular ligament (PTFL) is known to provide stability against ankle joint inversion. As injuries of the ankle joint have been reported at a wide range of plantarflexion/dorsiflexion angles, the aim of the present study was to evaluate the stabilizing function of these ligaments depending on the sagittal plane positioning of the ankle joint.

Methods

Eight fresh-frozen specimens were tested on a custom-built ankle deflection tester allowing the application of inversion torques in various plantarflexion/dorsiflexion positions. A motion capture system recorded kinematic data from the talus, calcaneus and fibula with bone-pin markers during inversion movements at 10° of dorsiflexion, at neutral position and at plantarflexion 10°. ATFL, CFL and PTFL were separately but sequentially sectioned in order to assess the contribution of the individual ligament with regard to ankle joint stability.

Results

Joint- and position-specific modulations could be observed when the ligaments were cut. Cutting the ATFL did not lead to any observable alterations in ankle inversion angle at a given torque. But subsequently cutting the CFL increased the inversion angle of the talocrural joint in the 10° plantarflexed position, and significantly increased the inversion angle of the subtalar joint in the 10° dorsiflexed position. Sectioning of the PTFL led to minor increases of inversion angles in both joints.

Conclusions

The CFL is the primary ligamentous stabilizer of the ankle joint against a forced inversion. Its functioning depends greatly on the plantar−/dorsiflexion position of the ankle joint complex, as it provides the stability of the talocrural joint primarily during plantarflexion and the stability of the subtalar joint primarily during dorsiflexion.

Electronic supplementary material

The online version of this article (10.1186/s13047-019-0330-5) contains supplementary material, which is available to authorized users.

[Ankle dislocation without osseous lesions]

Approximately 7-10% of all emergency department patients are diagnosed with distortion of the upper ankle joint. A dislocation of the upper ankle joint without fracture is described in the literature as being very rare. In 33-50% the ankle dislocations are at least first-degree open and associated with a fracture of the tibia, the fibula or the talus. We report the course, treatment and results 12 months after trauma of a posteromedial first-degree open dislocation of the upper ankle joint without fracture. To our knowledge, there is no record of this pathology mentioned in the German language literature.

The role of military footwear and workload on ground reaction forces during a simulated lateral ankle sprain mechanism

BACKGROUND

Ankle sprains are a common orthopedic injury in military populations, which may be attributed to occupational demands and footwear. Minimalist military boots have become popular, but their influence on ground reaction force (GRF) attenuation capabilities during an ankle inversion perturbation are unknown. Therefore, the purpose of this study was to examine potential differences in GRFs during an ankle inversion perturbation in a standard issue (STN) and minimalist military boot (MIN) before and after a simulated military workload.

METHODS

Twenty-one healthy adult males completed an ankle inversion perturbation protocol in each footwear condition before and after an incremental treadmill exercise protocol to volitional exhaustion while wearing a 16kg rucksack. The ankle inversion perturbation protocol consisted of stepping down from a 27cm box onto a force platform with a fulcrum (FUL), which created 25° of inversion upon landing, or flat (FLT) outer sole attached to the plantar aspect of the participants' footwear in random order. Peak vertical, anterior/posterior, and medial/lateral components of the GRF during FUL and FLT conditions were assessed, normalized to multiples of body weight in each footwear. Dependent variables were then analyzed using separate 2 (footwear)×2 (time) repeated measures ANOVA (p<0.05).

RESULTS

The MIN footwear demonstrated significantly greater vertical GRF and significantly less medial GRF during the FUL condition.

CONCLUSIONS

These results indicate that various mechanical and design characteristics of military footwear may influence GRF attenuation capabilities and ankle joint loading when the foot/ankle complex is forced into inversion.

Deficits in subtalar pronation and supination proprioception in subjects with chronic ankle instability

Deficits in joint position sense (JPS) and force sense (FS) are two functional insufficiencies contributing to chronic ankle instability (CAI). To date, JPS and FS have been only investigated in the sagittal and transverse movement planes but not in the functional movement plane of the pronators and supinators defined by the axis of the subtalar joint (STJ). The purpose of this study was to investigate subtalar JPS as well as pronator and supinator FS in supinated and pronated joint angle in subjects with CAI. Using a force transducer and a goniometer integrated in an apparatus with a movement axis corresponding to Inman's STJ axis, JPS and FS were examined in 20 sport students with CAI and 20 age- and sex-matched controls. Compared to uninjured subjects, CAI leads to reduced pronator (p<0.01) and supinator FS (p<0.01) as well as JPS (p<0.05). A significant main effect for 'angle' was found for JPS (P<0.0001). JPS is affected by a significant 'group'×'angle' interaction (p<0.05) indicating reduced JPS in the 24° supinated angle however not in the 8° pronated angle. The angle-specific JPS deficits indicate that the anatomical STJ axis has to be considered when assessing pronation and supination proprioception in subjects with CAI.