Flatfoot is the collapse of the medial longitudinal arch of the foot with or without weight bearing, either acquired or progressive, due to the collapse of the medial longitudinal arch and dorsolateral hallux valgus of the forefoot accompanied by heel valgus, talar pronation and plantar flexion. There is a natural progression of this deformity, which manifests as congenital or juvenile flexible flatfoot, and if left untreated, the deformity can worsen over time and progress to pain in adults. In adults, meaning patients older than 18 years of age, acquired flexible flatfoot deformity is associated with posterior tibial tendon insufficiency. The etiology of posterior tibial tendon insufficiency may be related to abnormal mechanics and patients with previous hypertension, diabetes mellitus, steroid use, peripheral vascular disease, obesity, and renal heart disease. Most often, the disease develops in women between 43 and 60 years of age. The Kidner-Cobb procedure, as well as various modifications of the procedure, is used to treat patients with stage 2 posterior tibial tendon insufficiency, which has been reported in the literature.Patients with stage 2 present with tendons that are edematous, stretched, and nonfunctional. The foot has adapted to this flattened valgus deformity and has become flaccid with concomitant tension in the posterior tibial tendon. It is this flexibility that distinguishes them from patients with stage 3 posterior tibial tendon insufficiency. The original Kidner procedure was reported in 1929, where the paratibial navicular led to an abnormal biomechanical mechanism causing a diminished ability to pronate the foot. This procedure was used primarily in patients with symptomatic paravalvular bone and was not required in patients with posterior tibial tendon insufficiency only.Kidner’s discussion of the relationship between symptomatic paravalvular bone and flat feet suggests that the presence of the paravalvular bone can alter the direction of pull of the posterior tibial tendon. This imbalance can lead to excessive pronation of the foot and impingement of the paravalvular bone against the medial malleolus. This produces a painful bursa and posterior tibial tendonitis with dysfunction. Kidner therefore recommended not only resection of the paravalvular bone, but also reconstruction of the posterior tibial tendon on the metatarsal surface of the navicular bone. Other studies have refuted this theory, suggesting that the paravalvular bone is only an irritant.Prichasuk and Sinphurmsukskul used the Kidner procedure in 28 patients and found an excellent rate of 96%.The modified Kidner procedure consisted of either excision of the paravalvular bone or excision of the medial navicular protuberance and anterior displacement of the posterior tibial tendon stop. The Cobb procedure was performed next, and Lowman, reported using the tibialis anterior tendon as a suspensory band under the navicular bone to repair symptomatic flat feet. 1979 Cobb used part of the tibialis anterior tendon to strengthen the tibialis posterior tendon at stage 2, and three retrospective analyses of patients who used the Cobb procedure showed that nearly 80-85% of the patients had some improvement from the preoperative period. 2007 Knupp and Hintermann conducted a study of 22 consecutive patients who underwent the Cobb procedure. In 2007, Knupp and Hintermann performed the Cobb procedure on 22 consecutive patients with stage 2 posterior tibial tendon insufficiency with a 96% success rate. This study focuses on the functional and patient satisfaction assessment of stage 2 patients using the modified Kidner-Cobb procedure. PATIENTS AND METHODS: Three surgeons from three independent clinical institutions performed the modified Kidner-Cobb procedure on 39 symptomatic patients with flexible flat feet. Evaluation metrics included recovery time-postoperative to fully pain-free daily activities and use of everyday shoes. Postoperative functional assessment criteria were based on earlier studies by Prichasuk and Sinphurmsuksukul – comparing postoperative pain levels, mobility, and comfort in wearing shoes. Patient inclusion criteria: patients with reduced ability to walk greater than 100 feet without pain and definite foot discomfort. Patients with persistent progression of flatfoot appearance deformity with the use of foot supports and support pads, clinical examination confirming that the patient has stage 2 posterior tibial tendon insufficiency: passive correction of forefoot abduction and rearfoot valgus deformity, protruding head of the talus head, subsidence of the medial arch, tenderness at the posterior tibial tendon alignment, resistance inversion pain, positive single-leg heel-lift test, and radiographic evidence of: mild subluxation of the talonavicular joint, increased adduction of the dice bone, and no significant MRI showed a long internal tendon tear consistent with a stage 2 lesion with degeneration of the inner wall. Exclusion criteria: rigid deformity, arthropathy, neuromuscular lesion continuity soft tissue malformation, patient has undergone previous surgical intervention, almost all patients initially present with aching, stabbing pain, colic in the medial longitudinal arch, lateral tarsal sinus region, heel and posterior calf. These conditions can lead to decreased walking, running and jumping activities. Conservative treatment is given for 6 months to 1 year through the use of anti-inflammatory medications, injection therapy, physical therapy and customized braces. Surgical intervention was performed only in patients with persistent symptoms. For this study, a body mass index >30 locating obesity was included in the study index. Additional surgical operations included heel dice joint fusion, heel osteotomy, subtalar joint fusion, and percutaneous Achilles tendon lengthening. Patients were followed up, clinically examined and x-rayed for bone healing before and after surgery. Pain, medial longitudinal arch height and muscle strength were also considered. Surgical approach: Modified Kidner-Cobb procedure: A 10-15 cm curved incision was made on the medial edge of the dorsum of the foot to expose the anterior tibial tendon and posterior tibial tendon, and the joint capsule was incised longitudinally above the stopping point of the posterior tibial muscle up to the level of the head of the talus and the neck of the talus. The joint capsule, periosteum, and posterior tibial tendon stop were peeled away from the navicular tuberosity, allowing direct visualization of the tendon’s properties and determining the extent of tissue removal based on the degree of calcification. The medial tuberosity of the navicular bone, and the paravalvular bone are resected using osteotomies. The joint capsule, periosteum, and posterior tibial tendon stop are moved forward in foot rotation and sutured to the exposed cancellous bone of the navicular bone and adjacent soft combinations, where the posterior tibial tendon is mildly strained. The anterior tibial tendon was split centrally from the point of termination, encircled with an umbilical band of saline, pushed as proximally as possible, freed the medial half, and transferred deeper to the posterior tibial tendon and sutured in the rotated posterior position of the foot. The remaining transected anterior tibial tendon was prepared and sutured to the posterior tibial tendon. And then the wound was closed layer by layer. A weightless cast was used for 6 weeks postoperatively. Afterwards, a compression stocking is worn and the ankle brace is used for partial weight-bearing for 2 to 4 weeks. Physical therapy, including muscle training, joint mobility training, low-voltage electrical stimulation, and whirlpool baths can be performed during this period, and additional procedures, such as percutaneous Achilles tendon lengthening, and talar fusion, can be performed if surgical necessity requires it. Achilles tendon lengthening is indicated for patients with clubfoot deformity. Subtalar joint fusion is mainly used in patients with flexible flat feet with hyperrotation of the subtalar joint. Results: The statistical description of this study is shown in Table 6. 39 patients with a mean age of 32.3 years (5-70 years) were treated surgically with 28 right feet, 22 left feet, 11 patients underwent bipedal treatment, 18 pediatric patients and 21 adults. The average follow-up time after surgery was 4.6 years (2-8 years). Using manual muscle strength testing, patients did not perceive a decrease in tibialis anterior muscle strength compared to the contralateral side, and patients reported a reduction in preoperative symptoms of calf or foot pain, weakness, and fatigue. Our criteria for evaluating postoperative function were based on earlier studies by Prichasuk and Sinphurmsuksukul – comparing postoperative pain levels, mobility, and comfort in wearing shoes. Clinical outcomes were rated for each foot that underwent surgery: 48 feet were excellent, 2 were satisfactory, and there were no adverse outcomes. The excellent patients showed no significant pain by visual pain scores, did not use customized shoes, did not require support or use crutches, and were able to participate in daily activities without restriction. The medial longitudinal arch of the foot was increased on the affected side compared to the contralateral side.Complications occurred in 3 cases, wound dehiscence in 2 cases, and internal fixation breakage in 1 case.As mentioned earlier, the tibialis anterior muscle did not show any significant regression after tendon transfer. Children younger than 18 years of age recovered more quickly than adults, with an average of 3.7 months of unrestricted daily activity using shelf shoes. In contrast, adults took an average of 5.7 months to reach the same level. In addition, patients who received postoperative physical therapy had a significantly longer recovery period. Obesity had no significant effect on the course of postoperative bone healing (P=0.5). Multiple regression analysis showed no statistically significant effect of additional surgery on the outcome. DISCUSSION: From an anatomical point of view, the position of the symptomatic flat exostosis foot resides lateral to the line of force of the lower limb, which is mainly due to intrinsic bony structural abnormalities and muscular imbalance. The intrinsic osteoarticular structural abnormality (as described in our paper) stems from posterior tibial tendon insufficiency and is progressively aggravated by gastrocnemius or flounder-gastrocnemius pathology. Restoring this strength, which enhances the medial longitudinal arch, can therefore help to improve foot function and slow the progression of flatfoot deformity. In adults or children with greater mobility of the subtalar joint, an additional subtalar fusion can be performed, which will help to reduce the strength of the medial column anterior to rotation. Restore the relative sequence of the talus to the heel. In children, the tibial-heel relationship takes into account the corrected position of the bone as well as the adaptability of the involved articular surfaces. Early literature was enthusiastic about tendon fixation or tendon transfer procedures using the flexor digitorum longus tendon, with the goal of the procedure being to aid in the restoration of posterior tibial tendon function. This is because they belong to the same group of muscles that are innervated by the cervical nerve. In young patients with flexible flat feet who have not lost function, a separate tendon transfer such as the anterior tibialis tendon is used as a component of reconstructive surgery. Additional clinical reviews have shown that tendon transfers combined with bony surgery have improved clinical improvement significantly. This study shows that the modified Kidner-Cobb procedure is a good option for patients with symptomatic flat feet secondary to paravalvular and navicular hypertrophy and Mueller stage 2 posterior tibial tendon dysfunction (ignoring age, gender, medical history, and weight). At each postoperative follow-up visit, there was no recurrence of painful flatfoot deformity, and despite a slight, nonmeasurable, visual longitudinal arch decline over the years, patients reported pain relief and improved function during exercise, thus improving daily activities. The lack of measurement of longitudinal arch height and the absence of weight-bearing position x-ray measurements make this study of diminished quality. Other similar shortcomings were the lack of skin sensitivity analysis. In conclusion, the modified Kidner-Cobb procedure is a good option for patients with flexible flatfoot stage 2 going for correction of forefoot pronation. Other additional procedures may be utilized on a patient-by-patient basis. Mueller’s classification of posterior tibial tendon insufficiency Stage 1: asymptomatic: presents with underlying biomechanical abnormalities Stage 2: symptomatic: tendinitis and progressive flatfoot manifestations Stage 3: rupture (functional rupture): worsening of symptoms, with the possibility of recovery with reconstruction Stage 4: terminal: rapid worsening of the above symptoms, with severe mobility limitations.