ANALYSIS OF THE RESULTS OF SURGICAL TREATMENT OF RIGID PLANO-VALGUS FEET IN CHILDREN WITH METHOD OF SUBTALAR ARTHROEREISIS Shabaldin N.A., Titov F.V.,Gibadullin D.G., Malikova L.G.

Kemerovo State Medical University,

Regional Pediatric Clinical Hospital, Kemerovo, Russia

Embryonal development of the human foot begins after three months of antenatal life. However this organ of the locomotor system is characterized by physiological immaturity after birth and during the first years of life [1].

The term flatfoot in children means the applanation of longitudinal arch of the foot as the most frequent pathology. This term includes the group of conditions of different origin. In most cases, especially in children of early age group, this condition is physiological, with a trend to self-correction along with growing [1, 2]. The mobile flatfoot does not cause development of degenerative changes in foot joints, does not lead to pain syndrome and does not require for active treatment. Most authors estimate this condition as a natural stage of physiological evolution of the foot. It is confirmed by the fact of decreasing amount of the mobile flatfoot in the population of children with ageing [3].

Certainly, the longitudinal arch flattening shows rigid characteristics in some children. Several diagnostic tests are used for mobility estimation. The most common ones are position on tiptoe and Jack test [4]. Rigid plano-valgus deformation is characterized by absent modeling of the foot arch, and correction of valgus position of the posterior part.

Significant rigid flattening of the longitudinal arch decreases the damper function of the foot, resulting in formation of persistent pain syndrome and decreasing resistance to physical loads [5]. According to some authors, a disorder of arch structure of the foot changes the rigidity as the locomotor characteristics. Therefore, flatfoot is the risk factor of degenerative and destructive changes in the foot joints, mainly in Chopard’s joint.

Conservative management of patients with non-physiological forms of flatfoot is mainly used for young children with absent pain, and non-evident anatomical and functional disorders in the foot joints. However this technique does not give a significant correction of longitudinal arch flattening [5, 6]. If conservative therapy is inefficient, a surgical correction is recommended for intense pain. One of the most modern techniques is subtalar arthroereisis with the metal implant. A surgical intervention is a low-invasive, promoting the modeling of longitudinal arch and restoration of dampfer function of the foot [6, 7, 8].

Objective – to analyze the early and long-term clinical and radiological results of treatment of children with rigid forms of plano-valgus deformity of the foot treated with subtalar arthroereisis with a metal implant.

MATERIALS AND METHODS

The study was approved by the local ethical committee of Kemerovo State Medical University (the protocol No.14, 18 October 2018). All parents gave their written consent for use of clinical data of their children in the scientific research.

For achievement of the objective, 74 cases of children with severe forms of plano-valgus feet were analyzed. The treatment was realized with subtalar arthroereisis with the metal implant in Kemerovo Regional Pediatric Clinical Hospital in 2016-2018. A surgical intervention was conducted from the age of 9. The oldest age was 17 years, the mean one – 11. 124 foot surgeries were conducted totally.

The parents participated in the survey. The main sections of the questionnaire included the social aspect of their social life (education, bad habits, professional harm, address of residence at the moment of pregnancy and others), their health (chronic diseases of organs and systems of the body), familial history of chronic diseases (including diseases of the locomotor system), features of pregnancy course, perinatal and postnatal periods. The systemic analysis of case histories (F No.003/4) and the medical records (F No.112) was performed for included patients.

We used AOSAF for estimation of efficiency of the presented technique. All patients received the clinical examination: before surgery, 1 month, 3 months and one year after it. The clinical examination considered a degree of correction in all morphofunctional parts of the foot: flattened longitudinal arch, the talar head with medial bulging, valgus declination of the calcaneal bone during load, and supination contracture of the anterior foot.

The X-ray examination was conducted before surgery, one month and one year after it. It included frontal and lateral views under load. We used the following radiologic values for estimation of the foot deformation: foot arch angle, talocalcaneal angle, astragalotibial angle, calcaneoplantar angle. Before surgery, 33 cases (26.6 %) corresponded to the second degree of longitudinal flatfoot, 91 cases (73.4 %) – to the third degree. Moreover, we estimated the indirect signs of tarsal coalition in the case of specific clinical picture including S-symptom, anteater nose sign, beak symptom, S-shaped articular cavity of talo-navicular joint. If one or several signs of coalitions were found, additional examination with multi-spiral computer tomography was conducted.

Considering the absence of the uniform opinion on treatment of patients with rigid forms of plano-valgus foot, we selected the surgical techniques on the basis of the main clinical criteria: age > 9, persistent pain syndrome during physical load, significant feet deformation, which is persistent to conservative therapy. Tip toe test and Jack test were used for confirmation of rigid pattern of longitudinal arch flattening. At the moment of admission to the unit, all patients received the standard X-ray examination, with additional use of multi-spiral computer tomography if required. Considering the anatomic and functional features of the patient’s foot, the presurgical planning was realized, which included selection of the implant size, and solution of the question about additional correcting manipulations.

The results of the study were estimated with the standard statistical methods with MS Excel 2007 and Statistica for Windows 7.0. The characteristics of distribution were estimated. Kolmogorov-Smirnov's test and Shapiro-Wilk’s tests were used. The descriptive statistical methods were used. Descriptive statistics was used in normal distribution of values. It was presented as the mean arithmetic (M) and standard error of the mean (m). If normal distribution was absent, the descriptive statistic was presented as the median (Me) and 25th and 75th quartiles (Q25 – UQ and Q75 – LQ). Non-parametric Kruskel-Wallis’s test was used for testing the statistical hypotheses of absent intergroup differences in quantitative signs. Paired comparison of the groups was conducted for rejection of the null hypothesis during the analysis. The results were considered as statistically significant in error < 5 %. It corresponds to medicobiological studies.

RESULTS AND DISCUSSION

All children demonstrated the flatfoot of rigid pattern at the background of structural features of the locomotor system. The pathology was severe in two cases – rocker bottom foot.

The collection of the anamnesis data showed the complicated heredity of foot abnormality in most cases (72/97.2 %).

Moreover, 18 children (36 feet, 29 %) showed the inborn plano-valgus deformation due to vertical position of the talus. One patient showed the tarsal coalition: cartilaginous tarsocalcaneal fusion of the middle facet joint.

22 children (44 feet, 35.5 %) showed the initial signs of degenerative and dystrophic changes in the foot joints.

112 cases included the standard technique of subtalar arthroereisis with introduction of the metal implant into the subtalar sinus. However the surgical intervention was supplemented with subcutaneous Z-shaped extending achillotomy for ankle joint contracture. Two cases required for surgical correction of the medial column of the foot, and transposition of the anterior tibial muscle onto the third alar bone.

The presented surgical technique is primarily oriented to correction of position of the posterior foot, calcaneal bone and the talus. Therefore, introduction of the metal correcting implant into the subtalar sinus promotes the persistent correction of excessive valgus of the calcaneal bone, and corrects the talar equines, with achievement of modeling of the longitudinal arch and increasing the region under the arch. In most cases, (112/90.3 %), this single manipulation resulted in persistent correction of the posterior foot, and increasing the medial column of the foot.

A surgical intervention corresponded to the principles of low traumatic potential. A surgical approach was realized along the external surface of the foot, in the plane of subtalar sinus (the length of 1.5 cm). The surgical correction did not disorder the physiological ratios in the foot joints and did not damage the articular surfaces, resulting in decreasing risks of formation of degenerative and dystrophic arthrosis after surgery.

In case of rigidity of the posterior foot with retraction of the triceps muscle of calf, the surgical intervention was supplemented with subcutaneous Z-shaped extending achillotomy, which mobilized the calcaneal bone and allowed achieving the appropriate spatial position. In one case with foot hypermobility, the technique of subtalar arthroereisis was supplemented with transposition of the anterior tibial muscle onto the third sphenoid bone for increasing the space under the arch.

The postsurgical analysis of the radiologic criteria showed the normalization of the ratios in the foot joint. The highest correction was made for talocalcaneal angle, with the average decrease by 18.7˚. The normalization of the position of the talar bone promoted the decrease in the angle of the foot arch within 8.7˚, with increasing the height of the arch by 7.7 mm. The angle of inclination of the calcaneal bone decreased by 3˚ on the average (Fig. 1).

Figure 1

X-ray examination of the foot: a) X-ray image of the foot with load before surgery; b) X-ray image with load after surgery.

Figure 1 X-ray examination of the foot: X-ray image of the foot with load before surgery	Figure 1 X-ray examination of the foot: X-ray image with load after surgery.

Correction of degree 2 longitudinal flatfoot was conducted in 33 cases (26.6 %), degree 3 – in 91 (73.4 %). In most cases, the surgery resulted in achievement of the radiological values of degree 1 (44 cases, 35.5 %) and degree 2 (52 cases, 41.9 %) of longitudinal flatfoot. The radiological criteria corresponded to degree 3 in some patients (28 cases, 22.6 %). However the comparison with the initial findings showed the modeling of the foot arch. In the early and remote postsurgical periods, the correction was persistent.

One month after surgery, a clinical examination showed the moderate pain in subtalar sinus and lateral column of the foot in all patients. Some disorders of locomotion included the increasing pressure to lateral column in the supporting phase, limited equinus and elevated supination while pushing off. The static examination showed the stable uprightness of the calcaneal bone, elevated underarch space, increasing supination in the anterior foot (Fig. 2). These features can be related to change in architectonics, more correct distribution of load to anterior, middle and posterior parts in persons who accustomed to anatomic and functional features of the foot with plano-valgus deformation. Pain syndrome during resting was absent in all cases.

Figure 2 Clinical examination of the foot: appearance of the postsurgical wound	Figure 2 Clinical examination of the foot: appearance of the foot under load before surgery

Figure 2 Clinical examination of the foot: appearance of the foot after surgery.

Three months after it, the values of locomotion corresponded to the average physiological parameters. The decrease in intensity of pain syndrome with full recovery in some cases was observed in 68 children. In cases of primarily identified signs of foot arthrosis, pain syndrome delivered troubles in high physical load.

In the remote postsurgical period, a clinical examination showed a positive trend to decreasing intensity of pain syndrome, increasing resistance to load, with persistent achieved position of correction. Three months after surgery, the mean AOFAS was 88.5 (UQ – 76.1; LQ – 97.8), after one year – 98.5 (UQ – 81.4; LQ – 99.7).

We estimated 91 cases (73.4 %, 53 children) as excellent results. Pain syndrome disappeared in this group of children, even in physical load to feet. The radiologic values corresponded to the first and second degrees of longitudinal flatfoot.

The satisfactory results were received in 30 (24.2 %, 18 children) cases. Pain syndrome did not disturb, however some patients complained of inconvenience during load to the foot. The postsurgical X-ray examination showed the achievement of more advantageous relations in the foot joints, i.e. degrees 2-3 of flatfoot, as compared to presurgical values. A surgical intervention resulted in refusal from expensive orthopedic footwear for all patients who could already wear comfortable footwear. The table shows the X-ray values after surgery.

Table

X-ray values before and after correction with use of subtalar arthroereisis

Talocalcaneal angle
Satisfactory						P
Before surgery			After surgery
Me	UQ	LQ	Me	UQ	LQ
50.800	48.575	53.025	44.800	41.219	48.381	0.063
Good						P
Before surgery			After surgery
Me	UQ	LQ	Me	UQ	LQ
49.182	44.353	54.011	38.727	32.799	44.655	0.032*
Satisfactory delta			Good delta			P
Me	UQ	LQ	Me	UQ	LQ	P
6.000	4.500	7.500	10.455	4.990	15.919	0.078
Calcaneal bone inclination
Satisfactory						P
Before surgery			After surgery
Me	UQ	LQ	Me	UQ	LQ
5.400	3.690	7.110	13.600	11.890	15.310	0.002*
Good						P
Before surgery			After surgery
Me	UQ	LQ	Me	UQ	LQ
6.545	4.284	8.807	17.273	13.133	21.413	0.001*
Satisfactory delta			Good delta			P
Me	UQ	LQ	Me	UQ	LQ	P
8.200	5.735	10.665	10.727	6.642	14.813	0.071
Foot arch angle
Satisfactory						P
Before surgery			After surgery
Me	UQ	LQ	Me	UQ	LQ
164.400	159.950	168.850	156.600	150.928	162.272	0.054
Good						P
Before surgery			After surgery
Me	UQ	LQ	Me	UQ	LQ
154.455	148.748	160.161	142.182	136.264	148.099	0.023*
Satisfactory delta			Good delta			P
Me	UQ	LQ	Me	UQ	LQ	P
7.800	6.157	9.443	12.273	5.396	19.150	0.069
Arch height
Satisfactory						P
Before surgery			After surgery
Me	UQ	LQ	Me	UQ	LQ
11.000	9.163	12.837	16.800	14.575	19.025	0.031*
Good						P
Before surgery			After surgery
Me	UQ	LQ	Me	UQ	LQ
18.091	13.051	23.131	31.273	26.232	36.313	0.002*
Satisfactory delta			Good delta			P
Me	UQ	LQ	Me	UQ	LQ	P
5.800	5.129	6.471	13.182	4.944	21.420	0.037*

Note: * – statistically significant difference, p < 0.05. Comparison was made according to corresponding figures.

As the table shows, the X-ray examination identified a significant decrease in the tarsocalcaneal angle in good results of surgical treatment. A reliable increase in the calcaneal bone inclination was observed in satisfactory and good results of surgical treatment. The foot arch angle decreased in good results of treatment. The increase in foot arch height was important for all treatment results. The good result of treatment was reliably different from satisfactory ones according to the delta of increasing arch height. This radiological sign can be main one in determination of efficiency of surgical treatment.

Poor outcomes of surgical treatment were noted in 3 cases (2.4 %, 3 kids). After two surgeries, a migration of the implant due to excessive axial load to the feet was observed, as well as due to incorrect size of the implant, resulting in recurrent implantation. After recurrent surgical intervention, migration was not found, and the radiological and clinical values corresponded to satisfactory result. One patient with plano-valgus feet and cerebral palsy showed more appropriate position of the foot during load and rest after placement of the implant. However the patient with evident paralytic gait showed further disorders of locomotion with full refusal from independent walking. The implants were removed. Later, this technique was not used for patients with cerebral palsy.

CONCLUSION

The analysis of treatment outcomes for patients with rigid plano-valgus feet with use of subtalar arthroereisis allowed concluding that the surgical technique was low invasive and corrected the spatial ratios in the middle and posterior parts of the feet in most cases, and corrected the pain syndrome, and allowed refusal from expensive orthopedic footwear in daily life.

Information on financing and conflict of interests

The study was conducted without sponsorship.

The authors declare the absence of any clear or potential conflicts of interests relating to publication of this article.