Assessment of Lower Limb Load Distribution in Patients Treated with the Ilizarov Method for Tibial Nonunion

Background

Problems with bone union or lack of union are common complications following fractures of the tibia [1–7]. One of these complications is tibial nonunion, for which the Ilizarov fixator is a widely accepted treatment method [2–28]. Surgical techniques and clinical and radiological results of this treatment have been described in numerous publications [2–28].

Delayed union or nonunion after a fracture manifests in many adverse symptoms, including pain. Such complications can lead to pathological mobility of the affected limb, limited joint movement, weakness and edema of the muscles, and in turn, worsen its functioning [2–33]. These symptoms impair the biomechanics of the limb in the case of nonunion. A good treatment outcome is characterized by the achievement of the bone union, elimination of pain and pathological limb mobility, improvement in joint mobility, and restoration of muscle strength, which in turn improve the biomechanics of the limbs [33–45].

To our knowledge, no evidence has been published regarding lower limb statics following tibial nonunion treatment using nails, plates or external fixators. Earlier work analyzed pedobarographic foot loading distribution in patients with unilateral ankylosis of the talonavicular joint, after osteotomy and after ankle arthrodesis [33–36,38].

Examinations with a pedobarographic platform deliver reproducible and objective information on the biomechanics of the lower limbs [33–38,45].

We propose 2 hypotheses: (1) patients treated with the Ilizarov method for aseptic tibial nonunion would place equal and symmetric load on both lower limbs, and (2) patients subjected to treatment with the Ilizarov external fixator due to aseptic tibial nonunion would display similar lower limb loading to healthy people.

The aim of this study was to assess the load placed on the lower limbs by patients treated with the Ilizarov method for aseptic tibial nonunion.

Material and Methods

STATISTICAL ANALYSIS:

Data were statistically analyzed using the SigmaPlot v13 (Systat Software Inc., San Jose, CA, USA) statistics package. The Kolmogorov-Smirnov test was used to check for normality of distribution. For comparisons of variables, the unpaired t test or the Mann-Whitney U test were used, depending on the type of distribution. All values were expressed as the median and the 5^th and 95^th percentiles. The level of statistical significance was set at P<0.05.

Results

We did not observe significant differences between the treated group and control group in terms of age, body weight, height, or BMI (Table 1). None of the patients during the follow-up reported knee or ankle stiffness. Five patients developed pin track infection, which resolved after administration of oral antibiotics. In 4 patients, during treatment, limitation of the ankle joint movement appeared, which disappeared after rehabilitation.

Table 2 depicts the measurements of load distribution over the entire foot and of the forefoot and hindfoot of participants from both groups. The load distribution was not significantly different over the entire foot or of the forefoot and hindfoot of the operated limb of the treated group compared to the non-dominant limb of the control group, or in the healthy, not operated, limb of the patient group compared to the dominant limb of the control group (Table 2).

Measurements comparing the load distribution in the operated and healthy limbs of the patients and the load distribution in the non-dominant and dominant limbs of the control group are shown in Table 3 and Figure 5. Results obtained with eyes closed and open for the load distribution over the entire foot and of the forefoot and hindfoot were assessed. There were no significant differences in load distribution between the operated and healthy (not operated) limbs of participants in the treated group (Table 3, Figure 5). In the control group, a significantly different load distribution of the entire foot between the non-dominant and dominant limbs was observed for open and closed eyes (Table 3, Figure 5).

Discussion

Fractures of the tibia often result in complications in the form of bone union disorders and nonunions [1–7]. The Ilizarov method is recognized as one of the best methods for treating joint nonunion [2–28], but it does not guarantee a complete recovery [12,13,16,20,21,24].

Studies from the literature reported various aspects of tibial nonunion treatment using the Ilizarov external fixator, including the surgical techniques, complications, clinical outcomes, and radiological results [2–28]. However, these studies did not focus on a very important outcome of treatment; namely, the biomechanics of the lower limbs. McHale and colleagues evaluated complicated cases, including 10 patients with tibial nonunions with debridement, antibiotic beads, and the Ilizarov method with a circular external fixator used for infected nonunions [43]. The authors tested dynamic parameters and observed impaired lower limb function due to limitations in ankle and knee joint movement and associated reductions in muscular strength in 6 persons. In the present study, we described the static parameters of the lower limb but not the dynamic ones. Our work is a part of the entire cycle of assessing the effectiveness of the Ilizarov method for biomechanics as well as statics and dynamics of patients’ gait. In another paper submitted for review, we evaluated dynamic tests depicting ground reaction forces and gait parameters.

Restoration of correct biomechanical parameters is an important element in the treatment of various limb diseases [33–42,45]. Improvements in muscle strength, proprioception, joint mobility, pain, and swelling translated into an improvement in the limb functioning, enhancing the biomechanics of limbs, and, at the same time, quality of life of individuals subjected to complicated therapy. The effectiveness of the Ilizarov external fixator in treating tibial nonunion has been explored by many authors [33–42,45].

The pedobarographic platform used in our study allows for reproducible, objective evaluation of the dynamics and statics of the musculoskeletal system [33–38,45], enabling a comparison of previously published results with the outcomes of the present study.

Lorkowski and colleagues analyzed pedobarographic foot loading distribution in patients with unilateral ankylosis of the talonavicular joint. An improvement in load distribution was observed following orthopedic treatment, along with a reduction in pain [38].

A previous study by Morasiewicz and colleagues assessed the load distribution on the lower extremities in individuals after osteotomy [35,36] and ankle arthrodesis [33,34] using the Ilizarov fixators. In all cases, symmetrical loading of both lower limbs distribution was found following treatment [33–36]. After lower limb osteotomy using the Ilizarov external fixators, patients were found to place a similar load on their lower extremities to healthy people [36].

To date, no studies have assessed the load distribution on the lower limbs following the treatment of aseptic tibial nonunion. Ling and colleagues performed a systematic literature review on the results of ankle arthrodesis treatment [44]. Based on information from 24 manuscripts (18 clinical studies, 5 biomechanical studies, and 1 gait analysis study), the majority of biomechanical studies showed altered biomechanics in the fused ankle. Several studies that assessed biomechanics following ankle arthrodesis found a load distribution disorder, but there is no real consensus in the literature regarding the effect of ankle arthrodesis on biomechanics [44]. For this reason, a symmetric load distribution between the dominant and non-dominant limb can be assumed.

In our study, we performed trials with eyes open and eyes closed. Restricting the use of vision was intended to force patients to additionally activate receptors located in joints and muscles, thus using somatosensory and vestibular senses to balance. When testing with eyes closed, in many cases, we can see significantly better results of loading symmetry due to improvement of postural control elicited by enhancing proprioceptive and vestibular sensations. This is especially observable in people recovering from strokes or returning after prolonged immobilization [46,47]. In the present study, differences between the sample with eyes open and closed were not observed.

In this study, patients showed symmetrical lower limb load distribution on the non-operated and operated limbs following the Ilizarov treatment of aseptic tibial nonunion. These results were better than those observed in the control group, in which we found significant differences in load distribution between the dominant and non-dominant limbs. Moreover, in the treated group, we recorded a symmetrical load distribution of the forefoot and hindfoot in both the healthy and operated limbs.

Comparing the lower limbs load distribution posed on the operated limb in the patient group to the non-dominant limb in the healthy (control) group, no significant differences were observed. Also, the load on the healthy limb in the patients subjected to the surgery and the load on the dominant limb in the healthy controls did not show a significant difference. When the load distributions of the forefoot and hindfoot were assessed, no significant differences were found between the operated limb and the non-dominant limb of the control group. In addition, the load distribution of the forefoot and hindfoot did not differ between the healthy (non-operated) limb of the treated group and the dominant limb of the controls.

This study has some limitations. First, lower limb load was not assessed before surgery due to the small size of the study groups that could be examined before and after the treatment. Second, patients with nonunion had difficulties with the movement of the limb before treatment, which prevented pedobarographic examination. Finally, in this study, only static parameters were assessed, but the inclusion of the dynamic data is essential for evaluating the effectiveness of the applied therapeutic method and would have made the conclusions stronger and more clinically relevant. A strength of our work was the comparative assessment with a healthy group of volunteers matched for sex and age.

Conclusions

In summary, patients treated with the Ilizarov fixators for tibial aseptic nonunion show symmetrical load distribution on both lower limbs following treatment, which does not differentiate them in this respect from healthy individuals. In the patient group, we observed a symmetrical distribution of lower limb load over the entire foot surface, as well as for the forefoot and hindfoot. Finally, in the treatment of tibial nonunion, the Ilizarov method enables the restoration of correct static biomechanics of the lower limbs.