Identification of risk factors affecting bone formation in gradual ulnar lengthening in children with hereditary multiple exostoses: A retrospective study

Ulnar lengthening for children with forearm deformity from hereditary multiple exostoses: a retrospective study from a tertiary medical center

BACKGROUND

Patients with hereditary multiple exostosis (HME) usually present with forearm deformity with or without radial head dislocation. Ulna lengthening has been proposed to address this condition. Exostosis resection plus ulna lengthening has been adopted in our hospital since 2008, and patients with this condition were retrospectively reviewed. Herein, we aimed to investigate the optimal timing and clinical outcomes of this surgical approach.

METHODS

In all, thirty-five patients (40 forearms), including 22 boys and 13 girls, were enrolled in our study from July 2014 to September 2020. We divided the patients into 4 groups based on the age when they received surgery and the status of the radial head. Pronation and supination of the forearm, flexion and extension of the elbow, wrist ulnar deviation and wrist radial deviation, and radiological parameters including ulnar length (UL), ulnar variance (UV), the percentage of radial bowing (RB/RL), radio articular angle (RAA) and carpal slip (CS), were assessed and recorded.

RESULTS

The mean UL was significantly improved after surgery in four Groups (P<0.05). In patients with radial head dislocation, we found significant improvement in forearm, wrist function and elbow flexion (p < 0.05). For the patients with radial head dislocation, the juniors demonstrated better improvement in % RB and RAA (p<0.05, p = 0.003 and 0.031).

CONCLUSION

Exostosis resection and ulna lengthening with unilateral external fixation can effectively improve the function and radiological parameters of forearm deformity in HME children. For patients with radial head dislocation, early surgery can achieve better results. For patients not associated with radial head dislocation, we recommend regular follow-up and surgical treatment after 10 years of age.

A comparative study of bone union and nonunion during distraction osteogenesis

BACKGROUND

The clinical characteristics of bone nonunion during distraction osteogenesis (DO) were rarely discussed. This study was employed to specify the difference between bone union and nonunion during DO.

METHODS

The patients with bone lengthening were recruited in our study. The bone union cases indicated the ones that remove the external fixator successfully, whereas the bone nonunion represented the bridging callus did not appear even after 9 months (an absence of bridging callus for at least three out of four cortices on plain radiographs) that needs autogenous bone transplantation. The differences in the pixel value ratio (PVR) growth of regenerated callus, lengthening index (LI), healing index (HI), external fixation index (EFI) and blood biochemical indexes between bone union and nonunion were analyzed.

RESULTS

A total of 8 bone nonunion and 27 bone union subjects were included in this study. The PVR growth in bone nonunion was significantly lower than that in bone union (0.19 ± 0.06 vs. 0.32 ± 0.16, P = 0.048). Interestingly, the HI and EFI in bone nonunion was significantly higher than that in bone union (62.0 ± 31.4 vs. 37.0 ± 27.4, P = 0.036; 75.0 ± 30.9 vs. 49.9 ± 16.1, P = 0.006). However, no significant difference with regard to LI was identified (0.76 ± 0.52 vs. 0.77 ± 0.32, P = 0.976). Moreover, the circulating level of urea and lymphocyte count in bone union was significantly lower than that in bone nonunion (4.31 ± 1.05 vs. 5.17 ± 1.06, P = 0.049; 2.08 ± 0.67 vs. 2.73 ± 0.54, P = 0.018). On the contrary, the circulating level of magnesium in bone union was significantly higher than that in bone nonunion (0.87 ± 0.07 vs. 0.80 ± 0.07, P = 0.014).

CONCLUSION

Compared to the bone union, the PVR growth was significantly lower, whereas the HI and EFI was significantly higher in the bone nonunion. Moreover, the circulating level of urea, magnesium and lymphocyte count was also different between these two. Therefore, the PVR, HI and EFI seems to be reliable and sensitive indicators to reflect the bone nonunion during DO, which might be considered in bone lengthening. Further prospective studies are still needed to elaborate the concerned issues.

Lengthening of the ulna by callotasis in children with multiple hereditary exostoses: comparison of methods with and without internal fixation

PURPOSE

The goal of this retrospective study was to compare the gradual lengthening of the ulna in children with multiple hereditary exostoses with and without an elastic intramedullary nail.

METHODS

Between 1998 to 2018, the ulna was lengthened in 28 forearms in 21 patients (aged 7.1 to 16.6 years) using a monolateral external fixator when relative ulnar shortening exceeded 15 mm. In total, 16 forearms were lengthened with the external fixator (group I) and 12 forearms with the addition of an intramedullary elastic nail (group II). Subjective assessment of function, range of movement (ROM) of the wrist and elbow and complications were compared. Ulnar shortening, radial head dislocation, radial articular angle (RAA) and percentage of carpal slip and radial bowing were followed radiographically. The difference between the groups has been evaluated statistically.

RESULTS

The function of the extremity improved partially in 81% of patients in group I and in 83% of patients in group II. ROM was not improved except for radial deviation. Radial head position did not change. The values in group II in comparison with group I are higher for gain of length and lower for bone lengthening index and for bone healing index. Carpal slip decreased insignificantly. The RAA and radial bowing decreased, the comparison of values between groups and age under and over ten years were not statistically significant. Complications were more common in group I. No permanent complications were noted.

CONCLUSION

The addition of an intramedullary nail during the gradual ulnar lengthening improves the gain, bone healing index and rate of complications.

LEVEL OF EVIDENCE

III.

International recognition of the Ilizarov bone reconstruction techniques: Current practice and research (dedicated to 100th birthday of G. A. Ilizarov)

The Ilizarov method is one of the current methods used in bone reconstruction. It originated in the middle of the past century and comprises a number of bone reconstruction techniques executed with a ring external fixator developed by Ilizarov GA. Its main merits are viable new bone formation through distraction osteogenesis, high union rates and functional use of the limb throughout the course of treatment. The study of the phenomenon of distraction osteogenesis induced by tension stress with the Ilizarov apparatus was the impetus for advancement in bone reconstruction surgery. Since then, the original method has been used along with a number of its modifications developed due to emergence of new fixation devices and techniques of their application such as hexapod external fixators and motorized intramedullary lengthening nails. They gave rise to a relatively new orthopedic subspecialty termed “limb lengthening and reconstruction surgery”. Based on a comprehensive literature search, we summarized the recent clinical practice and research in bone reconstruction by the Ilizarov method with a special focus on its modification and recognition by the world orthopedic community. The international influence of the Ilizarov method was reviewed in regard to the origin country of the authors and journal’s rating. The Ilizarov method and other techniques based on distraction osteogenesis have been used in many countries and on all populated continents. It proves its international significance and confirms the greatest contribution of Ilizarov GA to bone reconstruction surgery.

Older age and multi-joint external fixator are two risk factors of complications in ulnar lengthening in children with hereditary multiple exostosis

Objectives

Hereditary multiple exostosis (HME) often involves forearm deformities. The aim of this study was to present the clinical results of 37 children who underwent ulnar lengthening with two different types of unilateral external fixators and to investigate the risk factors of complications.

Methods

We evaluated 37 children with forearm deformities caused by HME treated in our hospital from January 2008 to July 2019. The surgical procedures included resection of exostosis, osteotomy of the ulna, and gradual lengthening of the ulna with a unilateral external fixator. According to the type of fixator they received, the children were divided into two groups: group A received monorail fixators and group B received multi-joint fixators. Radiographic and functional parameters were assessed. Complications were recorded.

Results

All patients were followed-up for an average of 4.6 years (3.0 to 6.5). In both group A and group B, the ulna shortening (US), radial articular angle (RAA), carpal slip (CS), elbow flexion, forearm pronation, supination, and Mayo Elbow Performance Score (MEPS) values improved significantly from preoperatively to postoperatively (p < 0.05). However, the ulnar deviation was observed in 4 cases in group B and no cases in group A. According to logistic regression, the difference was only related to age (p < 0.05) and the type of external fixator (p < 0.05).

Conclusions

Ulnar lengthening with unilateral external fixation is a safe and effective procedure for the treatment of HME. Regarding complications, deviation of the ulna axis was more likely to occur in older children with multi-joint external fixators.

Forearm Deformity and Radial Head Dislocation in Pediatric Patients with Hereditary Multiple Exostoses: A Prospective Study Using Proportional Ulnar Length as a Scale to Lengthen the Shortened Ulna

BACKGROUND

Ulnar lengthening is a consensus treatment for hereditary multiple exostoses with radial head dislocation in pediatric patients; however, the optimal amount of ulnar lengthening remains unclear. It is necessary to look for a parameter to decide the amount of ulnar lengthening that will avoid recurrence and complications. The purpose of the present study was to confirm that proportional ulnar length (ulnar length/radial length) can be used as a scale for ulnar lengthening in pediatric patients.

METHODS

The normal lengths of the ulna and radius in the pediatric population were measured in different age groups. The proportional ulnar length was calculated as ulnar length/radial length in each group. Thirty forearms in 26 patients with radial head dislocation were treated with ulnar lengthening and deformity correction. The goal of ulnar lengthening was to recover the normal proportional ulnar length. The function of the forearm was evaluated at the time of the latest follow-up. The preoperative and postoperative values for radial bowing, radioarticular angle, ulnar variance, and carpal slip were also compared.

RESULTS

The value of proportional ulnar length in the normal population consistently averaged approximately 1.1. In all cases, proportional ulnar length recovered to the normal value of 1.1. Reduction of the dislocated radial head was achieved in 28 forearms (93%); in 16 of these forearms, good-quality reduction was achieved and no recurrence of radial head dislocation was observed during follow-up. The function of the forearm improved markedly (p < 0.001). Ulnar variance improved from 2.51 to -0.79 cm (p < 0.001). Radial deformities improved according to measurements of radial bowing and the radioarticular angle (p < 0.001). All parents were satisfied with the postoperative appearance and function of the forearm.

CONCLUSIONS

Proportional ulnar length could be used as a scale to decide the amount of ulnar lengthening for radial head dislocation in pediatric patients with hereditary multiple exostoses. Ulnar lengthening according to proportional ulnar length and deformity correction can prevent recurrence of ulnar variance and avoid impingement of the wrist.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.