Locomotion is the ability to move from one place to another. In humans, walking upright, or bipedally, is the most common form of locomotion. This form of movement involves all of the joints in the lower limb, and is characterized by an ‘inverted pendulum’ motion, which is where the body vaults over the non-moving limb.
In this article, we will explore the various stages of walking and the muscle involvement during each stage. This will include the stance phase and the swing phase, both of which are essential elements of the gait cycle.
The stance phase accounts for 60% of the gait cycle and can be divided into the heel strike, support, and toe-off phases. The heel strike phase is where the foot hits the ground heel-first. Three muscles or muscle sets are involved in this phase, each acting at a different joint and performing their own unique functions.
The support phase is where the rest of the leading foot hits the ground and the muscles work to cope with the force passing through the leg. This process is stabilized by a few key muscles:
The toe-off phase is when the foot prepares to leave the ground, heel-first and toes-last. This requires a few muscles:
Once the foot has left the ground, the lower limb is raised in preparation for the swing phase. This requires:
In the swing phase, the raised leg is propelled forward, providing the forward momentum of the walk. This is made possible by the:
Following the swing phase, the heel hits the ground and the whole cycle is repeated.
One such example of a characteristic gait is known as a Trendelenburg gait. In the leg lift and swing phases of walking, the body’s weight is placed on one limb, whilst the key abductor muscles (the gluteus medius and gluteus minimus) contract to stop the pelvis dropping towards the raised leg, as gravity would otherwise cause it to do.
A patient with a malfunctioning hip abductor will present with a positive Trendelenburg sign - their pelvis drops towards the side of the raised limb. This positive sign signifies that the abductor muscles on the standing limb are weakened or paralysed. For example, if the left leg is raised and a pelvic drop is observed on that side, then the abductor muscles on the right leg are likely to be the cause.
Humans walk by following a five-stage process, which is divided into the leg lift and swing phases. During the heel-strike phase, the foot hits the ground with the heel first. Three muscles/muscle sets are involved in this process, acting at a different joint. The gluteus maximus acts on the hip to decelerate the forward motion of the lower limb, while the quadriceps femoris keeps the leg extended at the knee and the thigh flexed at the hip. The anterior compartment of the leg helps to maintain the ankle dorsiflexion, positioning the heel for the strike.
The next stage is known as the support stage. After the heel strikes the ground, the rest of the leading foot follows and the muscles work together to cope with the incoming force. The quadriceps femoris stabilises the knee in extension, supporting the weight of the body. Other muscles such as the foot inverters and evertors, gluteus minimus, gluteus medius and tensor fascia lata contract in a balanced manner to stabilise the foot and work to abduct the lower limb, keeping the pelvis level by counteracting the imbalance caused from having most of the body weight on one leg.
Following the support stage is the toe-off phase. Here, the foot prepares to leave the ground, with the heel first and toes last. During this process, the hamstring muscles extend the thigh at the hip, while the quadriceps femoris maintains the extended position of the knee. Additionally, the posterior compartment of the leg plantarflexes the ankle, with the prime movers being gastrocnemius, soleus and tibialis posterior.
The fourth phase is the leg lift, where the lower limb is raised in preparation for the swing stage. During this process, the iliopsoas and rectus femoris flex the thigh at the hip, driving the knee forwards, whilst the hamstring muscles flex the leg at the knee joint. Simultaneously, the anterior compartment of the leg dorsiflexes the ankle.
The final phase, the swing phase, propels the raised leg forward and allows for the forward motion of the walk. The iliopsoas and rectus femoris keep the thigh flexed at the hip, resisting gravity, whilst the quadriceps femoris extends the leg at the knee, positioning the foot for landing. The role of the anterior compartment of the leg is to maintain ankle dorsiflexion to keep the heel in place for landing. Finally, the heel hits the ground and the cycle repeats.
One of the key disorders that can be observed during walking is the Trendelenburg Gait. During the leg lift and swing phases, the body weight is placed on one limb and the gluteus medius and gluteus minimus contract to stop the pelvis dropping under the influence of gravity. However, a person with malfunctioning hip abductors will present with a positive Trendelenburg sign, where the pelvis drops towards the side of the raised limb, signifying that the abductor muscles on the standing limb are weakened or paralysed.
In order to compensate for this weakness, the trunk lurches to the opposite side and, eventually, the patient has a highly recognisable lurching gait. The cause of this disorder can either be neurogenic, where the superior gluteal nerve is damaged, or myogenic, where the muscle fibres are stretched or weakened but the nerve remains functional. The myogenic cause can be treated with muscle strengthening exercises and physical therapy, while a neurogenic cause is more difficult and sometimes impossible to treat.
Another characteristic gait is Footdrop, which is caused by damage to the common or deep fibular nerve. Blunt trauma or fracture to the head of fibula can damage the common fibular nerve, while damage to the deep fibular nerve can occur when it is stretched or weakened. This nerve innervates the muscles in the anterior compartment of the leg, which are important for dorsiflexing the foot during the swing phase of walking, and for clearing the toes away from the ground.
Walking is a complex process that requires the coordination of multiple muscles. The five stages of walking - heel-strike, support, toe-off, leg lift and swing - help to create the motion we know as walking. Deficiencies in certain muscles or nerves can lead to characteristic gaits such as the Trendelenburg gait or Footdrop. In the case of the Trendelenburg gait, a patient with malfunctioning hip abductors will present with a positive Trendelenburg sign, which signifies that the abductor muscles on the standing limb are weakened or paralysed. On the other hand, Footdrop is caused by damage to the common or deep fibular nerve, which can be caused by blunt trauma or fracture.
When the deep fibular nerve is damaged, the foot cannot be dorsiflexed, and it drags along the ground during the swing phase. To compensate, the patient might use an ‘eversion flick’—a sudden eversion motion. Another common compensatory movement is hyperflexion of the thigh at the hip to help the dropped foot clear the floor, which is called “high steppage gait.”[caption id="attachment_25733" align="aligncenter" width="312"] Fig 3 - Left footdrop. This can occur following common fibular or deep fibular nerve palsy.[/caption][end-clinical]
Walking is a complex process that involves the heel strike, support, toe-off, leg lift, and swing stages. It’s important to be able to recognize most characteristic gaits in order to determine possible underlying pathology. For instance, the Trendelenburg Gait is identified through the lopsided pelvic tilt that can indicate hip pathology. The lifted foot off the ground while clearing obstacles is an indicator of Footdrop. Lastly, an Antalgic Gait is often seen with lower back conditions where the affected side has a shortened stance time and quickened swing time.
The deep fibular nerve and its resulting footdrop can not only be caused by physical trauma but also by advanced diabetes and neurological disorders. To compensate, an ‘eversion flick’ can help the patient in their gait as well as the common compensatory movement of hyperflexion of the thigh at the hip, the ‘High Steppage Gait’. However, these can be difficult to master, requiring a period of practice and an intensive regimen to help build strength as well as promote muscle and nerve recovery.
While these compensatory movements are used to help with the debilitating pain caused by Footdrop, they also can lead to increased fatigue and an increase in knee joint stress due to the uneven gait caused by the feet movement. This, in turn, could lead to more long-term complications such as arthritis and joint degeneration. Therefore, a complete evaluation by a physician is recommended, and proper management of the condition is necessary to minimize further injury and pain.
Patients with Footdrop may also experience an Antalgic Gait. This gait is characterized by a shortened stance phase, commonly seen in patients with chronic musculoskeletal pain. It’s important for the patient to be aware that this may be caused by the underlying condition, so they can work to seek proper treatment.
Since Footdrop and its associated compensatory gaits can have such a detrimental impact on a patient’s mobility and quality of life, it is absolutely essential that a full evaluation and personalized treatment plan is prescribed by a physician. While physical therapy and rehabilitation can be an effective treatment, it is important to remember that every patient’s condition is different and requires a tailored approach.
The key to successful treatment of Footdrop is a combination of physical therapy, rehabilitative exercises, and, in some cases, surgery. Physical therapy is essential for strengthening the muscles affected by the condition, as well as aiding in the recovery of any affected nerves. With physical therapy, the patient will be given a personalized treatment plan that they must adhere to regularly. Additionally, rehabilitative exercises in the form of stretching and strengthening exercises can help build strength in the affected areas.
In more severe cases, however, surgery may be necessary to correct any physical abnormalities or injuries causing the Footdrop. Surgery is necessary to replace, repair, or remove the damaged nerves, as well as repair any muscle or tendon damage that may have occurred. Surgery involves a recovery period, and the patient must be careful to adhere to their physical therapy regimen following the procedure.
In conclusion, Footdrop is a debilitating condition that can have a major impact on a person’s mobility and quality of life. It is important to recognize the symptoms of this condition so that an accurate diagnosis can be made and a personalized treatment plan can be formulated and implemented. Physical therapy, rehabilitative exercises, and in severe cases, surgery are all viable options for treating Footdrop, and should be considered in consultation with a physician.
