Evaluating the results of long tubular bone distraction with an advanced rod monolateral external fixator for achondroplasia

Limb lengthening in individuals with achondroplasia: Analysis of an international survey

BACKGROUND

Limb lengthening surgery is a contentious option for individuals with achondroplasia. This study aimed to assess real-world experiences, outcomes, and perspectives on limb lengthening in a multinational cohort of individuals with achondroplasia.

METHODS

A cross-sectional, international online survey on limb lengthening experiences and perspectives was conducted in 11 languages across 16 countries from May until July 2024.

RESULTS

Out of 467 responders (229 self-responders, 238 parents/caregivers), 90 (19.3 %) reported undergoing limb lengthening (LL) surgery. The mean age at first surgery was 10.5 years (SD 4.5). On average, respondents underwent 3.7 (SD 2.9) procedures, resulting in 14.5 cm (SD10.4) added and final adult height of 137.1 cm in females and 142.1 cm in males. Significant improvements were described in activities such as car driving, bathing, brushing hair, and wiping after toileting for those who underwent both arm and leg lengthening (p ≤ 0.001). Among respondents, 23 % would recommend the procedure to others and 28 % would not recommend LL. Nearly half of respondents (49 %) was uncertain about recommending LL.

CONCLUSIONS

This is the largest international survey on LL in achondroplasia with results highlighting some of the differences in perspectives and choices of the individual with achondroplasia and their families, providing real-world evidence of the outcomes of this intervention. While significant functional improvements were reported, a reduced percentage of respondents recommended LL intervention. The findings underscore the existence of a triad when considering limb lengthening in achondroplasia as individual choices and life experiences, socio-cultural environment and access to clinical options.

International expert opinion on the considerations for combining vosoritide and limb surgery: a modified delphi study

BACKGROUND

Achondroplasia is the most common form of skeletal disorder with disproportionate short stature. Vosoritide is the first disease-specific, precision pharmacotherapy to increase growth velocity in children with achondroplasia. Limb surgery is a standard approach to increase height and arm span, improve proportionality and functionality, as well as correcting deformities. The aim of this study was to gain expert opinion on the combined use of vosoritide and limb surgery in children and adolescents with achondroplasia.

METHODS

An international expert panel of 17 clinicians and orthopaedic surgeons was convened, and a modified Delphi process undertaken. The panel reviewed 120 statements for wording, removed any unnecessary statements, and added any that they felt were missing. There were 26 statements identified as facts that were not included in subsequent rounds of voting. A total of 97 statements were rated on a ten-point scale where 1 was 'Completely disagree' and 10 'Completely agree'. A score of ≥ 7 was identified as agreement, and ≤ 4 as disagreement. All experts who scored a statement ≤ 4 were invited to provide comments.

RESULTS

There was 100% agreement with several statements including, "Achieve a target height, arm span or upper limb length to improve daily activities" (mean level of agreement [LoA] 9.47, range 8-10), the "Involvement of a multidisciplinary team in a specialist centre to follow up the patient" (mean LoA 9.67, range 7-10), "Planning a treatment strategy based on age and pubertal stage" (mean LoA 9.60, range 8-10), and "Identification of short- and long-term goals, based on individualised treatment planning" (mean LoA 9.27, range 7-10), among others. The sequence of a combined approach and potential impact on the physes caused disagreement, largely due to a lack of available data.

CONCLUSIONS

It is clear from the range of responses that this modified Delphi process is only the beginning of new considerations, now that a medical therapy for achondroplasia is available. Until data on a combined treatment approach are available, sharing expert opinion is a vital way of providing support and guidance to the clinical community.

Periosteal expansion osteogenesis using a tubular dynamic frame device: An experimental study in rats

Periosteal expansion osteogenesis (PEO) is a technique for augmenting bone by creating a gradual separation between the bone and periosteum. This study assessed PEO-induced bone formation around the femurs of rats using a dynamic frame device (DFD), consisting of a shape memory membrane made of polyethylene terephthalate (PET) formed into a tubular shape. The DFDs, consisting of a PET membrane coated with hydroxyapatite (HA)/gelatin on the bone-contact surface, were inserted between the periosteum and bone of the femurs of rats. In the experimental group, DFDs were suture-fixed to the femur with 4-0 Vicryl Rapid; in the control group, 4-0 silk thread was used for fixation. Five rats per group were euthanized at intervals of 3, 5, and 8 weeks postoperatively. Bone formation was evaluated via micro-CT imaging, histomorphometry, and histological analysis. Morphological analysis revealed new bone between the femur and the periosteum, expanded by the DFD, in all groups. The mean values of new bone were 0.30 mm2 proximally, 0.18 mm2 centrally, and 0.82 mm2 distally in the control group, compared to 1.05 mm2 proximally, 0.27 mm2 centrally, and 0.84 mm2 distally in the experimental group. A significant difference in new bone was observed in the proximal region of the experimental group. Histological examination showed that a single layer of newly formed neoplastic bone was noted on the cortical bone surface across all sites. The proximal portion displayed a bone marrow cavity at the center, encircled by a thick bone cortex with a layered structure. New bone formation was notable between existing cortical bone and the periosteum, particularly at both ends of the DFD. The use of PET in PEO was a viable option for achieving ideal bone morphology.

Quality of Life in Children With Achondroplasia Undergoing Paired Limb Lengthening With an External Fixator and Modified Distraction Control: Observational Nonrandomized Study

BACKGROUND

Transosseous distraction osteosynthesis is prioritized in orthopedic care for children with achondroplasia. However, difficulties encountered during treatment and rehabilitation directly impact patients' quality of life. Using rod external fixators within a semicircular frame for osteosynthesis is less traumatic compared to spoke circular devices. Their straightforward assembly and mounting on the limb segment can help significantly reduce treatment duration, thereby improving children's quality of life during treatment and rehabilitation.

OBJECTIVE

This study aimed to conduct a comparative analysis of the quality of life (measured by postoperative pain syndrome, physical activity, and emotional state) among children with achondroplasia undergoing paired limb lengthening using either an external fixator with modified distraction control or a circular multiaxial system developed by the authors.

METHODS

This was an observational, prospective, nonrandomized, and longitudinal study with historical control. The study group consisted of 14 patients ranging from 5 to 15 (mean 7.6, SD 2.3) years old with a genetically confirmed diagnosis of achondroplasia. All patients underwent paired limb lengthening with a rod external fixator and a modified distraction control developed by the authors. A total of 28 limb segments, among them 4 (14%) humeri, 8 (29%) femurs, and 16 (57%) tibias, were lengthened in 1 round. Unpublished data from the previous study served as the control group, comprising 9 patients (18 limb segments) of the same age group (mean age at surgery 8.6, SD 2.3 years), who underwent limb lengthening surgery using a circular multiaxial system-2 (11%) humeri, 6 (33%) femurs, and 10 (56%) tibias. The Wong-Baker Faces Rating Scale was used to measure pain symptoms, while the Russified Pediatric Quality of Life (PedsQL) v4.0 questionnaire assessed quality of life.

RESULTS

During the latent phase (7 to 10 days after surgery), a more pronounced decrease in the indicators of physical activity and emotional state on the PedsQL v4.0 questionnaire was noted in the control group (mean 52.4, SD 4.8 versus mean 52.8, SD 5.5 points according to children's responses and their parents' responses, respectively) compared to the experimental group (mean 59.5, SD 6.8 points and mean 61.33, SD 6.5 points according to the children's responses and their parents' responses, respectively). The differences between the groups were statistically significant (P<.05 for children's responses and P<.01 for parents' responses). Importantly, 6 months after surgery, these quality-of-life indicators, as reported by children in the experimental group, averaged 70.25 (SS 4.8) points. Similarly, their parents reported a mean of 70.54 (SD 4.2) points. In the control group, the corresponding values were 69.64 (SD 5.6) and 69.35 (SD 6.2), respectively. There was no statistically significant difference between the groups.

CONCLUSIONS

The external fixator with modified distraction control developed by the authors provides a higher standard of living compared with the circular multiaxial system during the latency phase.

Results and complications of bilateral limb lengthening in achondroplasia: a retrospective analysis

Background

Achondroplasia is one of the main causes of disharmonic dwarfism. Patients with achondroplasia might have physical and psychological limitations due to their disproportionate stature. Surgical limb lengthening is the only practical option available to achieve a stature comparable to normal population range. The purpose of this study is to analyze results and complications of our lengthening protocol.

Methods

A retrospective analysis was performed on 33 patients with achondroplasia (21 females and 12 males) undergoing simultaneous bilateral tibia or femur lengthening in four surgical stages from 2017 to 2021 (46 lengthening procedures, with a total of 56 tibias and 36 femurs). For each patient, patients' characteristics and antero-posterior and lateral radiographs were obtained. The following parameters were analyzed: duration of lengthening with external fixator, amount of lengthening, complications or events that influenced outcomes and the healing index (HI).

Results

The average tibial and femoral gain was 7.9 cm and 6.9 cm, respectively. The tibiae achieved better results than the femurs (p = 0.005). Nineteen complications were reported for 92 segments (20.7%), and the variables influencing complications were: step (p = 0.002) and fixation duration (p = 0.061).

Conclusions

Bilateral parallel lower limb lengthening in four surgical steps may be a viable technique in patients with achondroplasia.

Prevalence of Thalassemia in the Vietnamese Population and Building a Clinical Decision Support System for Prenatal Screening for Thalassemia

Introduction

The prevalence of thalassemia among the Vietnamese population was studied, and clinical decision support systems for prenatal screening of thalassemia were created. The aim of this report was to investigate the prevalence of thalassemia in the Vietnamese population, building a clinical decision support system for prenatal screening for thalassemia.

Methods

A cross-sectional study was conducted on pregnant women and their husbands visiting the Vietnam National Hospital of Obstetrics and Gynecology from October 2020 to December 2021. A total of 10112 medical records of first-time pregnant women and their husbands were collected.

Results

A clinical decision support system was built, including 2 different types of systems for prenatal screening for thalassemia (an expert system and 4 AI-based CDSS). One thousand nine hundred ninety-two cases were used to train and test machine learning models, while 1555 cases were used for specialized expert system evaluation. There were ten key variables for AI-based CDSS for machine learning. The four most important features in thalassemia screening were identified. The accuracy of the expert system and AI-based CDSS was compared. The rate of patients with Alpha thalassemia is 10.73% (1085 patients), the rate of patients with beta-thalassemia is 2.24% (227 patients), and 0.29% (29 patients) of patients carry both alpha-thalassemia and beta-thalassemia gene mutations. The expert system showed an accuracy of 98.45%. Among the AI-based CDSS developed, the multilayer perceptron (MLP) model was the most stable regardless of the training database (accuracy of 98,5% using all features and 97% using only the four most important features).

Conclusions

When comparing the expert system with the AI-based CDSS, the accuracy of the expert system and AI-based models was comparable. The developed expert system for prenatal thalassemia screening showed high accuracy. AI-based CDSS showed satisfactory results. Further development of such systems is promising with a view to their introduction into clinical practice.