Functional state of blood circulation and neuromuscular system of the lower limb of patients with congenital pseudarthrosis of the tibia after consolidation of the nonunion

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Introduction:

The issue of the possibility of deformities correction in patients with congenital false joint of lower-leg bones (CFJLL) after consolidation of the pseudarthrosis is still open [1, 2, 3, 4]. Multi-level and multi-component deformities of the lower extremity require complex corrections as well as the use of modern bone-holding devices. However, these surgical interventions are accompanied by the risk of pseudarthrosis re-formation and loss of weight bearing for the affected lower extremity [1].

Study objective:

This study was designed to evaluate the clinical findings and functional status of affected lower extremities in children with CFJLL of different origins after successful surgical treatment of false joint before and after deformities correction.

Study materials and methods:

The study included 100 children and adolescents (50 males and 50 females) aged 3–18 years with CFJLL of different origins. They had previously been followed up and were successfully treated for lower-leg false joint consolidation at the Turner Institute for Children. Patients were admitted for deformities correction.

All patients underwent an orthopedic examination to determine the range of motion in the joints of lower extremities. Panoramic radiography, electroneuromyography (ENMG), and rheovasography (RVG) of the lower extremities were also performed.

All patients had a combination of lower-leg shaft deformation and shortening. According to the classification of A.P. Pozdeev (1984), based on etiological factors of CFJLL, the majority of patients had neurofibromatosis (62 patients, 62%), 26% (26 patients) had myelodysplasia and incontinence, and 12% (12 patients) had CFJLL secondary to fibrous dysplasia. The distribution of patients by sex and age is presented in Table 1.

The age group 9–14 years had the most number of patients (46%), whereas the group 15–18 years had the least (17%). The 3–8 years group accounted for 37% of patients. The number of boys and girls in each age group was approximately equal.

The functional status of the neuromuscular system for lower extremities was studied using ENMG. We conducted an electromyography (EMG) of lower leg muscles (anterior tibial, gastrocnemius, and peroneal muscles) for shortened and contralateral extremities. Electroneurography (ENG) (peroneal and tibial nerves) allowed us to evaluate the neurological deficit and the level of peripheral nerve damage in the lower extremity.

To study the blood supply in the affected lower extremity after surgical (often multiple) treatment and restoration of continuity in lower leg bones, we performed RVG of the lower extremities. This method was developed to estimate the perfusion of the extremity, flexible and elastic properties of blood vessels, and conditions of capillary blood flow and venous outflow. We analyzed the following parameters: rheovasographic, bisferious, and diastolic indices and assessed the tone of the main vessels.

Results

From the analyses of subjective data, including complaints and medical history, we could determine the frequency of the most typical complaints for this group of patients. They were, in descending order as follows: the presence of deformities in the lower extremity (100%), lameness and gait disorders (98%), and pain in adjacent joints (10%). There were no complaints in 6% of the children.

Detailed orthopedic examination allowed us to evaluate the degree of severity of abnormalities in the affected lower extremities and disorders of the contralateral extremities and other body segments. Data on the nature of orthopedic pathology in patients with CFJLL before deformity correction are presented in Table 2.

Table 2

Orthopedic conditions in patients with CFJLL
before epithesis

Other musculoskeletal disorders was observed in all patients with shortened extremities, but this was not a primary complaint in most cases. Postural disorders and deformations of segments of affected lower extremities were observed in allpatients. A combination of deformities with shortened lower extremities was diagnosed in 92 patients (92%) with CFJLL of different origins.

The disorders of adjacent joints were as follows: knee joint (10%), ankle joint on the affected side (50%), valgus at the level of talar and subtalar joints (66%), and foot shortening (95%). These were the most prevalent but were probably not primary disorders because of the lack of adequate weight bearing on the affected extremity and multiple surgical treatments. The average length of foot shortening was 2 ± 1 cm.

We also analyzed the magnitude of lower extremity shortening in children with CFJLL before epithesis.

Patients with shortenings of < 4.5 cm were the most prevalent in this study. This group accounted for 40% of the children who were admitted to the hospital before epithesis. Patients with shortenings of > 9.5 cm accounted for 17% of all patients, those with shortenings of 8.6–9.5 cm accounted for 7%, and those with shortenings of 5.6–6.5 cm and 7.6–8.5 cm accounted for 8% each. Shortening of the affected lower extremity was associated with the following: bone tissue resection during multiple surgical interventions, injury to the distal growth zone of the tibia, and the lack of continuity and support ability of the tibia.

Surface ENG of the lower extremity in patients with CFJLL before epithesis revealed the presence of fibular neuropathy in most cases. There were changes both in the affected lower extremity and on the contralateral side. In most cases, neuropathy was manifested as an axonopathy.

Depending on the CFJLL origin, the highest incidence of fibular neuropathy on the affected side was present in patients with myelodysplasia (75%). Contralateral nerve injury in this group of patients occurred in 25% of patients. Fibular nerve injury on the affected side in patients with neurofibromatosis was observed in 52% of the patients and in 24% of patients on the contralateral side. In patients with fibrous dysplasia, fibular neuropathy was seen in 43% of the patients and only on the affected side. ENG data are shown in Table 4.

Tibial neuropathy was seen only in patients with CFJLL secondary to neurofibromatosis and myelodysplasia and only on the affected side. Neuropathy was not a primary condition; it was the result of multiple surgical interventions. Incidence in both groups was 4% and 9%, respectively.

Contractility studies for the lower leg muscles during EMG showed a decrease in contractility both on the affected and contralateral sides in patients with CFJLL. A decrease of muscle contractility on the affected side was observed in patients with CFJLL secondary to neurofibromatosis (76%) and fibrous dysplasia (64%).

In all patients with CFJLL secondary to myelodysplasia, we noted a decrease of muscle contractility on both lower extremities. The assessment of motoneuron activation in the lumbar and sacral spinal segments showed an injury in an average of 50% of children with CFJLL of different origins both on the affected side and on contralateral lower extremity.

The analysis of blood supply in the lower extremity did not reveal significant abnormalities in RVG parameters relative to normal standards and appropriate parameters of the contralateral lower extremity segments in patients with CFJLL secondary to neurofibromatosis and myelodysplasia. RVG data for these studies are shown in Tables 5–7. Peripheral hemodynamics was quite stable, capillary blood flow was not impeded, and venous outflow was not delayed.

Thus, RVG data showed the absence of marked abnormalities in the circulation of affected lower extremity segments in patients with CFJLL secondary to neurofibromatosis and myelodysplasia. This indicates an adequate body response to the restoration of the continuity of affected extremity bones and the ability of the musculoskeletal and central nervous systems of patients to support rehabilitation of the extremity after surgical treatment.

Table 4

Results of surface EMG of the lower extremities in patients with CFJLL before epithesis

Table 5

Rheovasographic data in patients with CFJLL secondary to neurofibromatosis

Table 6 

Rheovasographic data in patients with CFJLL secondary to myelodysplasia

Table 7 

Data on longitudinal RVG of the lower extremities in patients with CFJLL secondary to fibrous dysplasia

The symbol * indicates significantly varying parameters with confidence levels of p < 0.05 in comparison with similar parameters of the contralateral segment.

Despite preserved blood flow in patients with CFJLL secondary to fibrous dysplasia, abnormalities in the peripheral hemodynamics both at the level of the hip and the lower leg of the affected extremity in this group of patients were identified. At the hip level this condition was manifested by impeded capillary blood flow, as evidenced by a significant increase in the bisferious index to 57.0% ± 2.5% compared with the unaffected segment (48.8% ± 2.3%), (p < 0.05).

In addition, there was delayed venous outflow in the hip of the affected side where the average diastolic index increased significantly to 48.3% ± 3.5% compared with that of the contralateral segment (38.6% ± 1.4%), (p < 0.05). Conversely, at the level of the lower leg on the affected side, parameters of capillary blood flow and venous outflow indicated the tendency for the shunting of blood flow to the area of interest (partial discharge of blood from arterial to venous bed, bypassing the capillary network). This is evidenced by the reduction of bisferious and diastolic indices. Moreover, a median resistance of the capillary network was reduced insignificantly up to 23.7% ± 5.3% compared with the value of the contralateral side, which was 26.7% ± 3.6%, (p > 0.05). However, in general, the venous outflow was reduced significantly to 24.4% ± 2.0% as against 33.5% ± 1.6%, (p < 0.05).

These changes indicate that in patients with CFJLL secondary to fibrous dysplasia, moderate circulatory disorders of the entire affected lower extremity persisted after surgical repair. These disorders were characterized by abnormalities in peripheral blood circulation that ultimately manifested with reduced microcirculation mainly in the area of interest.

In general, the circulation of the affected lower extremities in children with CFJLL of different origin was satisfactorily compensated, which suggests the long term benefits of surgical interventions.

Discussion

The data obtained during a comprehensive study of the lower extremities in children with CFJLL after consolidation of the lower leg bones indicate the involvement of the entire lower extremity in the pathological process, either as a result of disease or as a result of multiple surgical interventions. These results should be considered at the stage of elongation and epithesis of the lower extremities to avoid the development of circulatory disorders of the lower extremity or neuropathies.

Conclusions

On the basis of this study we may conclude the following:

1. Common complaints of patients with CFJLL of different origin after lower leg bone continuity were lameness (in 98% of patients), affected lower extremity deformities (in 80% of patients), and pain in adjacent joints (in 10% of patients).
2. For all patients with CFJLL, the presence of concomitant orthopedic conditions was typical with postural disorders, stiffness of the ankle joint of the affected lower extremity in 50% of patients, and foot shortening in 65% of patients.
3. Surface ENMG revealed a decrease in the contractility of lower leg muscles and fibular neuropathy of axonal origin in both lower extremities. Thus at each stage of treatment, the magnitude of elongation and the speed at which epithesis is performed must be considered.
4. Data obtained from RVG analysis indicated improved circulation in the lower extremities after the restoration of the continuity of the lower leg bones, and the possibility of further surgical treatment aimed at epithesis of the affected lower extremity.

About the authors

Aleksander Pavlovich Pozdeev

Author for correspondence.
Email: professorpozdeev@mail.ru
MD, PhD, professor, chief research associate of the department of bone pathology. The Turner Scientific and Research Institute for Children’s Orthopedics Russian Federation

Ekaterina Anatolievna Zakharyan

Email: zax-2008@mail.ru
MD, PhD student of the chair of pediatric traumatology and orthopedics. North-Western State Medical University n. a. I.I. Mechnikov Russian Federation

Timur Faizovich Zubairov

Email: professorpozdeev@mail.ru
MD, PhD, research associate of the department of bone pathology. The Turner Scientific and Research Institute for Children’s Orthopedics Russian Federation

Igor Evgenievich Nikityuk

Email: femtotech@mail.ru
MD, PhD, leading research associate of the laboratory of physiological and biomechanical research. The Turner Scientific and Research Institute for Children’s Orthopedics Russian Federation

References

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