Author(s): David Guerrero Ramos, Cristina Herrera Ligero, Paqui Peydro de Moya, María José Vivas Broseta, Marina Vidal Pedros, Ignacio Bermejo Bosch

Instituto de Biomecánica de Valencia
Universitat Politècnica de València
Edificio 9C. Camino de Vera s/n
(46022) Valencia. Spain

Ankle fractures are the most common bone fracture in the body, subsequently leading to biomechanical alterations. In this context, it is important to carry out an assessment of the functional capacity with parameters that can be determining factors for recovery. We present a clinical case in which the functional capacity of gait has been assessed using the NedAMHPlus/IBV application in a patient with an ankle fracture, the purpose being to demonstrate the clinical usefulness of this application and to understand how fatigue affects gait in patients of this type.

 

INTRODUCTION

Ankle fractures are the most common bone fracture in the body, accounting for 10% of the total. These injuries affect the patient's day-to-day activities such as walking, running and balance, and involve pain, weakness and swelling in the joint. When the joint cannot be restored by conservative treatment, a surgical intervention is carried out, which leads to subsequent immobilization which in turn gives rise to biomechanical alterations.

When faced with an injury of this nature, it is important to carry out an assessment of the functional capacity using parameters that may be determining factors for recovery and the fine-tuning of the rehabilitation treatment. By way of example, it is important to ascertain the biomechanical variables in what is one of the most studied human activities to date, human gait. In this way, we can gain knowledge of any possible deficits in the phases that constitute gait as well as any deficiencies in the articular range of the joints involved, in the forces used, or in the activation of the key muscle groups implicated in the movement.                                             

The different studies that have focused on the analysis of human gait after an ankle fracture conclude that 6 months after surgical treatment, the gait speed is lower, there is a reduced range of mobility in the dorsiflexion of the affected ankle, and stance asymmetries in the lower limbs.

Although it is one of the most studied activities, its study sometimes requires complex assessment protocols and instrumentation that need to be carried out by expert personnel. Today, we have applications at our disposal that facilitate this process and perform a gait analysis in a simple, quick and agile way. This is the case of the NedAMHPlus/IBV software, an application developed exclusively for quantitative gait analysis, and which provides easily interpretable data.

The following is a clinical case in which the functional capacity of gait has been assessed with NedAMHPlus/IBV in a patient with an ankle fracture, the purpose being to learn about the biomechanical deficits in gait, how fatigue affects the patient during gait, and to demonstrate the usefulness of gait assessment in the clinical setting.

CASE REPORT                                            

A 48-year-old man with a history of a crushed right ankle and foot resulting in a bimalleolar ankle fracture with intra-articular extension, a displaced fibula diaphysis fracture and a medial/proximal scaphoid fracture with extension to the astragalo-scaphoid joint. He underwent an osteosynthesis procedure involving a fibula plate attached by screws and two screws in the tibial malleolus. He then had another operation to remove the osteosynthesis material 10 months after the surgery.

As the patient continued to suffer pain despite the surgery and rehabilitation that had been carried out, his doctor referred him to the Institute of Biomechanics (IBV) for biomechanical assessment. His pain becomes more severe during the course of his working day. A functional gait assessment is requested to find out in which phases the patient's gait is impaired, so that a decision can be made in relation to his pain and rehabilitation programme.

Just before the assessment begins, the patient manifested generalized pain in the right ankle and foot, located mainly in the heel support area and the Achilles region, as well as in both malleoli of the ankle, and at the level of the tibiotalar and astragalo-scaphoid joints. His pain has a mechanical profile, insofar as it disappears when he is at rest and increases with prolonged standing and ambulation.

The NedAMHPlus/IBV application is used to analyse and assess the dynamic and kinematic parameters of the patient's gait through a dynamometric platform, together with two photocell barriers to record speed and a 3D photogrammetry system. The patient's data are compared with a normality database developed by the IBV, which is segmented by age, sex, speed and the presence or absence of footwear. Only 10 markers, attached at key and easily accessible anatomical points, are required to instrument the patient (Figure 1). The measurement protocol consists of walking along a corridor at a speed that the patient finds comfortable, taking only 3 steps with each foot. A baseline and post-fatigue assessment is carried out with footwear to analyse how fatigue may affect the patient. The fatigue protocol involved the patient walking on a treadmill at a slow speed, without a slope, until the pain increased considerably and the patient could not  walk any longer.

The application automatically provides a report with the results. The results are divided into three key points: an overall dynamic assessment (resulting from the analysis of the speed, stance time difference and reaction forces in the stance phase), an overall kinematic assessment (resulting from the analysis of the sagittal plane mobility of the joints of both lower limbs) and repeatability (an analysis of the regularity of the dynamic parameters).

Figure 1: Placement of surface markers on key anatomical regions while a subject performs a NedAMHPlus/IBV gait test.

RESULTS AND DISCUSSION

The final result of the gait analysis translates into an impaired gait ability (Table 1), with an overall dynamic rating of 67% for the baseline condition and 65% for the post-fatigue condition, and a mostly preserved but slightly off-normal pattern of 89% and 84% (normal is when both are equal to or greater than 90%) in the kinematic rating.

Table 1: Final result of gait functionality through dynamic and kinematic biomechanical assessment. Upper: Baseline condition wearing shoes. Lower: Post-fatigue condition wearing shoes.

This limitation occurs due to alterations in the stance pattern on the right side (Figure 2), highlighting the generation of insufficient forces both in the braking phase and in the push-off and propulsion phase. In addition, there is an overall asymmetry of all forces, being greater on the unaffected side (Table 2). This is due to a tendency to overload the healthy side, not exerting enough force with the triceps surae and a limited plantar flexion range, in accordance with the characteristics of the patient's pain. This asymmetry of forces worsens with the post-fatigue condition, as his pain increases with prolonged gait or standing.

Figure 2: Graphical representation of the reaction force in the stride. Superimposition of footprint recordings. Left: Baseline condition wearing shoes. Right: Post-fatigue condition wearing shoes (Right forces: orange lines. Left forces: purple lines).

There is also a claudication of the gait with a decrease in right foot stance time, which worsens slightly after the fatigue protocol, thereby increasing the asymmetry between the two feet (Figure 2). In a person with a functional gait, there should be no difference in stance time between the two limbs, as can be seen in Figure 3.

Figure 3: Graphical representation of the reaction forces in a normal gait during walking.

It should be noted that the patient’s walking speed was adequate in both situations (Table 2), which means that, despite the biomechanical alterations, he makes compensations in order to move forward efficiently.

Table 2: Result in percentage of normality of the average gait parameters. Values equal to or greater than 90% are considered functionally normal. Upper: Baseline condition wearing shoes. Lower: Post-fatigue condition wearing shoes.

In relation to his kinematic pattern (Figure 4), we observed a locking of the right knee during mid-stance on this side (coinciding with the swing of the contralateral side) and reduced plantar flexion at the end of the stance. On the other hand, after the post-fatigue assessment, the patient avoids heel strike and performs excessive plantar flexion in the first part of his gait with greater knee flexion. This suggests that he performs midfoot strike in order to avoid contact with the heel due to the increased pain he is suffering after the fatigue protocol.

Figure 4: Sagittal plane mobility averages for each of the lower limb joints and in foot progression during the gait cycle. Normality band (green) and reference pattern (white line). Right lower limb: lighter or orange line. Left lower limb: darker or purple line. Upper: Baseline condition wearing shoes. Lower: Post-fatigue condition wearing shoes. 

In summary, the patient has a highly altered gait in terms of his dynamic and kinematic pattern, due to his limitation when performing plantar flexion with his right foot and the pain he has in the Achilles region and in the calcaneus. In addition, given the high repeatability of the patient when performing this movement, it can be concluded that he has made an effort that is compatible with his possibilities.

Given these biomechanical results, it was decided to institute a treatment to recover the plantar flexion range of motion and to strengthen the triceps surae, which would reduce the deficits in the braking, push-off and propulsion forces. This will avoid overloading the healthy side of the body, preventing future pathologies due to overuse, and will create optimal conditions to generate strength on the affected side, where there is currently a deficit. It was also decided to create a programme to tolerate the load on the affected calcaneus, working to that end on a perceptual-sensory-motor re-education program.

In addition, this objective information reinforces the subjective sensations described by the patient in the clinic. A coherence is observed between what is described and the variables obtained when performing a test in a fatigued state.

CONCLUSIONS

After visualizing the clinical case and the results obtained using the NedAMHPlus/IBV application for the analysis of gait functionality, we reach the following conclusions:

- In the patient we have studied, evident biomechanical alterations in his gait pattern have been observed, being even more altered when he is in a state of fatigue, reinforcing the subjective sensations that he presented in the clinic.

- NedAMHPlus/IBV is a highly useful clinical tool due to the large number of variables it provides in an agile and simple way. In addition to providing the healthcare professional with objective information, it can be used in situations of occupational contingencies, as support for prescribing rehabilitation, or as justification for surgery.