Evaluation Of Balance, Plantar Pressure Distribution and Gait in Adults With Pes Planus

Introduction The lower extremity kinematic chain includes foot, ankle, knee, and hip joints. The foot is a complex structure and provides the body's contact with the ground. The foot is one of the most important sources of somatosensory information required for balance and walking. The proprioceptive information from the joints, muscles, and ligaments of the foot maintains the upright posture. Also, it helps to absorb ground reaction forces during walking and provides balance by adapting to different grounds.

The arches of the foot have a critical role in stability and flexibility. These arches have functions such as carrying body weight, contributing to the gait cycle, and generating energy. The foot has two longitudinal arches in the transverse plane: the medial longitudinal arch and the lateral longitudinal arch. The calcaneus, talus, navicular, cuneiform I, II, III, and the first three metatarsal bones form the medial longitudinal arch. The arch is the primary weight-bearing and shock-absorbing structure of the foot. The talonavicular joint, the subtalar joint, and the tibialis posterior muscle protect the structure of this arch.

Pes planus is defined as the decrease or complete disappearance of the medial longitudinal arch of the foot. It is the most common deformity among foot deformities. All babies have pes planus on their feet from birth. The medial longitudinal arch may not form in the feet of healthy infants until the age of 3 years. In advancing age, the development of the midtarsal joints and bones is supported by the strengthening of the ligaments, and the medial arch develops. However, with the weakness of the plantar fascia and muscle groups that support the medial longitudinal arch, arch support may decrease, and pes planus may be seen. In addition, it can be seen as a result of excessive load on the plantar fascia in adults who stand on hard floors for a long time due to their profession, in obese individuals, in cases with muscle imbalance, or as a result of the progression of pes planus in childhood. In a study on pes planus and pes cavus; 60% of the population had a normal foot structure, while 20% had a pes planus foot structure, and 20% had a pes cavus foot structure.

Pes planus causes a change in the load distribution in the medial side of the foot. The number of loads on the lower extremity joints and lumbar vertebrae vary. Various symptoms are seen after this biomechanical change. The symptoms are pain, loss of strength, fatigue, instability, and functional limitations, especially with walking and standing. As a result of the energy expenditure of the individuals during gait also increases. The increased energy expenditure negatively affects lower extremity performance .

Balance is the ability to keep the body's center of gravity within the acceptable limits of the support surface during activities such as sitting, standing, or gait. Balance is a complex process involving multifaceted sensory, motor, and biomechanical components. It is divided into two as static and dynamic balance. Changes in the normal alignment of the foot in pes planus cause abnormal sensory input from the foot, which prevents proper muscle activity required for posture and postural swings. This condition may cause balance problems. While some studies in the literature have shown that static postural stability, which is evaluated by force plate or balance systems, decreases in individuals with pes planus, others reported no difference compared to the neutral foot. Kim et al. stated that static stability is better in individuals with pes planus than in individuals without pes planus. The authors also found that there was no difference in dynamic stability. Plantar pressure distribution is a factor that affects both balance and gait. It has been observed that individuals with pes planus give more weight to the big toe, middle of the forefoot, and medial foot compared to the neutral foot. However, in another study, the same researchers compared pes planus, pes cavus, and foot pressure center in normal feet and found that only the terminal phase of the stance and the pre-swing phase differed. Although some evidence of characteristic plantar pressure patterns has been identified, differences in gait analysis protocols and plantar pressure analysis techniques make it difficult to obtain a clear result.