Investigation of the kinematics of walking in children with rigid flat feet

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**Rigid flatfoot is the most common type of foot dysfunction [1].** It is characterized by a lowering of the longitudinal arch of the foot but is actually a three-dimensional deformity, including valgus deformity of the hindfoot, forefoot abduction, and pronation, which is associated with the severity of the foot pathology itself [2, 3].  

In rigid flatfoot, the normal gait pattern is disrupted, and a new type of pathological gait emerges. Studying pathological movement patterns allows for diagnosing the causes and pathogenesis of the disease, as well as identifying individual and clinical variations in different clinical situations [4, 5].  

The treatment of the rigid form of flatfoot has its own characteristics, differing from the mobile form of this pathology, often requiring invasive surgical interventions [6]. Existing surgical correction methods for rigid flatfoot differ in technique and scope, ranging from methods applied to soft tissues by modifying the configuration of the talus with tendon and muscle transposition to methods used in bone tissue with various metal fixators [7]. However, long-term postoperative results remain unexpected and sometimes unsatisfactory for patients, their parents, and even orthopedic surgeons, leading to the necessity of constantly wearing orthopedic devices to eliminate clinical symptoms [8].  

The presented data indicate the lack of characterization of the pathogenetic elements of rigid flatfoot, biomechanical disorders of the neuromuscular structure of the lower leg and foot depending on the severity and stages of the disease, as well as the lack of their consideration in the development of indications and selection of correction methods for patients with rigid flatfoot [9].  

At the present stage, this pathology remains relevant, as it is necessary to study gait kinematics disorders in rigid flatfoot using the most modern research methods, such as video recording of gait and three-dimensional motion capture in a gait laboratory.  

### **OBJECTIVE**  
To determine the role of gait kinematics diagnostics in patients with rigid flatfoot by comparing pre- and postoperative data in a gait laboratory.  

### **MATERIALS AND METHODS**  
The study group included 51 patients (42 boys and 9 girls) with rigid flatfoot who were observed and treated at the Andijan Children's Multidisciplinary Clinic from 2019 to 2024. The average age of the patients was 10.5 years (ranging from 7 to 16 years). Referring to the classification by Myerson M.S. (1997), we developed a new algorithm, “№ DGU 42326 – Algorithm for Classifying Children with Rigid Flatfoot” (2024), at the Intellectual Property Agency of the Republic of Uzbekistan.  

Unlike Myerson’s classification, we included spastic contracture of the **m. peroneus longus** tendon in stages III and IV, which plays a significant role in the complexity of the pathological changes in the foot and ankle joint in rigid flatfoot (Table 1).  

#### **Table 1**  
**Distribution of patients by clinical form and stage of rigid flatfoot according to our developed classification**  

| Stage of Disease | Clinical Forms | I st. | II st. (n=13) | III st. (n=22) | IV st. (n=16) |
|------------------|---------------|-------|--------------|---------------|--------------|
| | | | III A (n=9) | III B (n=13) | IV A (n=8) | IV B (n=8) |
| **Congenital form (n=10, 19.5%)** | 0 | 2 (3.9%) | 2 (3.9%) | 2 (3.9%) | 3 (5.9%) | 1 (1.9%) |
| **Acquired form (n=41, 80.5%)** | 0 | 11 (21.6%) | 7 (13.7%) | 11 (21.6%) | 5 (9.9%) | 7 (13.7%) |

From the data in Table 1, it can be seen that the acquired form was more common, occurring in 41 (80.5%) cases, compared to 10 (19.5%) cases of congenital etiology. By disease stage, patients with stage III were most frequently registered (22 cases, 43.1%). Additionally, spastic contracture of the **m. peroneus longus** tendon was noted in 13 cases (25.5%) in subgroup III B and in 8 cases (15.7%) in subgroup IV B.  

The functional state of **m. peroneus longus** plays a key role in the transformation of mobile flatfoot into the rigid form, as well as in the importance of its tendon transposition towards the supinator side during surgical correction. Based on this, we developed a method for correcting rigid flatfoot:  

**"Transposition of the m. peroneus longus tendon to the medial side of the foot, shortening of the m. tibialis posterior tendon, and arthrodesis of the cuneonavicular joint."**  

The developed method differs by:  
- Wedge-shaped resection of the articular surfaces of the navicular and cuneiform bones (the wedge angle opens toward the plantar surface),  
- Formation of a tunnel in the cuneiform bone,  
- Re-insertion of the attachment site of the **m. tibialis posterior** tendon,  
- Shortening its tendon by tensioning and embedding it into the tunnel of the cuneiform bone,  
- Transposition of the **m. peroneus longus** tendon to the medial side and attachment to the **m. tibialis posterior** tendon,  
- Fixation of the cuneonavicular joint with pins in the form of a triangle to form the arch of the foot.  

**(Patent for invention № FAP 2416 (2024) at the Intellectual Property Agency of the Republic of Uzbekistan.)**  

This method was applied to all 51 patients.  

### **RESULTS AND DISCUSSION**  

Gait analysis was performed on all 51 patients using a 3D motion capture system in a gait laboratory before and after surgical correction. The following parameters were evaluated:  

- Step length  
- Stride width  
- Walking speed  
- Foot progression angle  
- Ankle dorsiflexion and plantarflexion angles  
- Knee joint flexion-extension angles  

Preoperative analysis showed significant deviations from normal gait patterns in all patients, including excessive pronation, valgus deviation of the hindfoot, and external rotation of the forefoot. The average foot progression angle was **+18.5°**, which is significantly higher than normal values.  

After surgery, gait kinematics improved in all patients. The foot progression angle decreased to an average of **+8.2°**, indicating better foot alignment. Walking speed increased by **21%**, and step length improved by **17%**, suggesting enhanced mobility and function.  

A statistical analysis of pre- and postoperative parameters confirmed significant improvements in gait biomechanics (**p < 0.05**). This confirms the effectiveness of the developed surgical method in restoring foot function.  

### **CONCLUSION**  

The study demonstrated that patients with rigid flatfoot experience significant gait disturbances, which can be objectively assessed using a 3D motion capture system. The newly developed surgical technique effectively corrects foot deformities, improves gait kinematics, and enhances overall mobility. The use of gait laboratory diagnostics allows for precise assessment of treatment outcomes and can be recommended for clinical practice in pediatric orthopedic surgery.  

 

About the authors

Khasanali Umarov

Andijan State Medical Institute

Author for correspondence.
Email: umarovhasanboj47@gmail.com
ORCID iD: 0009-0008-5466-1687
https://t.me/Doctor_Umarov_02

Травматолог, Ортопед

Uzbekistan, Republic of Uzbekistan, Andijan region, Andijan city, Y. Otabekov street, house 1.

References

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