Bilateral double level tibial lengthening in dwarfism

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.

Two-stage Bone Lengthening With Reuse of a Single Intramedullary Telescopic Nail in Patients With Achondroplasia

BACKGROUND

Patients with achondroplasia may benefit from limb-lengthening surgery with telescopic intramedullary nails (TIMNs). However, the 5-cm maximum length of the nails used in these patients in their original design may be insufficient. The aim of this research is to analyze the outcomes and complications after reusing the same TIMN for a second consecutive 5-cm lengthening in patients with achondroplasia.

METHODS

Retrospective study of 26 bones (16 femurs and 10 tibias) in 9 patients with achondroplasia treated for bilateral 2-stage sequential lengthening reusing the same TIMN. On completion of a first stage of 5 cm of elongation, the nail was unlocked, retracted, and re-locked; a second stage of 5 cm of distraction followed. Radiologic and clinical parameters were measured preoperatively and postoperatively, and complications were recorded.

RESULTS

The median age of patients at first surgery was 13.54 (12.9 to 16.3) years; 55% were males. The median preoperative height was 121 (117.5 to 127) cm, and the median healing index was 18.12 (14.5 to 32.8) and 26.96 (23.3 to 31.6) d/cm, while time to weight bearing was 185.5 (144.8 to 308.5) and 242.5 (208.5 to 293.8) days for femurs and tibias, respectively. Major complications included 3 cases of moderate ankle equinus, 2 cases of hardware failure (failure to relengthen), 2 premature consolidations, 1 common peroneal neurapraxia, and 2 valgus deformities. Femoral procedures had significantly fewer complications than tibial interventions (7 vs. 15, P=0.03), whereas patients who underwent lengthening of both the femur and tibia did not have significantly higher complication rates (14 vs. 8, P=0.6).

CONCLUSIONS

This study analyzes lower-limb lengthening in a series of achondroplastic patients using TIMN with the novelty of nail reuse to relengthen the bone. The complication rate found is acceptable, among which, potential damage to the internal lengthening mechanism must be considered, though this complication can usually be easily resolved. Overall, nail reuse seems advisable in cases where bone elongation is indicated, and the size and design of the nail limits the extent of lengthening.

LEVEL OF EVIDENCE

Level III, retrospective comparative study, before and after intervention.

Simultaneous Bilateral Femoral and Tibial Lengthening in Achondroplasia

Previous studies on lengthening for achondroplasia have reported bilateral extensive femoral lengthening followed by bilateral extensive tibial lengthening. To decrease trauma on soft tissues and joints, we propose bilateral simultaneous moderate femoral lengthening and moderate tibial lengthening followed by a similar repeat lengthening a few years later. Fifty patients with achondroplasia underwent 65 simultaneous bilateral femoral and tibial lengthening procedures. Segment lengthening amount and adverse events were obtained from medical records. Mean follow-up after bone healing was 35.6 months. Mean tibial lengthening was 52 mm; mean femoral lengthening was 72 mm. Average healing index was 1.4 months/cm for the tibia and 1 month/cm for the femur. Mean duration of treatment with external fixation was 6.7 months (range, 4.4-10.5 months). Thirty-eight (76%) of 50 patients experienced one or more adverse events during lengthening. We observed 78 adverse events, 35 (45%) of which required additional surgical procedures. All resolved by the end of treatment. Mechanical axis deviation improved from a mean of 15 mm medially to 8 mm medially. Simultaneous lengthening of four segments in patients with achondroplasia is a feasible strategy. Compared with isolated femoral or tibial lengthening, distributing the lengthening between the femur and tibia decreases total external fixator time.

Extensive Limb Lengthening for Achondroplasia and Hypochondroplasia

Extensive limb lengthening (ELL) was completed in 75 patients: 66 achondroplasia and 9 hypochondroplasia. The average lengthening was 27 cm for achondroplasia (12–40 cm) and 17 cm for hypochondroplasia (range 10–25 cm). There were 48 females and 27 males. Lengthening was done either by 2-segment (14 patients; both tibias and/or both femurs) or by 4-segment lengthenings (64 patients; both femurs and tibias at the same time). Most patients also had bilateral humeral lengthening. Patients had 2 or 3 lower limb lengthenings and one humeral lengthening. Lengthenings were either juvenile-onset (31), adolescent-onset (38) or adult-onset (6). The average age at final follow-up was 26 years old (range 17–43 years). There were few permanent sequelae of complications. The most serious was one paraparesis. All patients returned to activities of normal living and only one was made worse by the surgery (paraparesis). This is the first study to show that ELL can lead to an increase of height into the normal height range. Previous studies showed mean increases of height of up to 20 cm, while this study consistently showed an average increase of 30 cm (range 15–40 cm) for juvenile-onset and mean increase of 26 cm (range 15–30 cm) for adolescent-onset. This results in low normal height at skeletal maturity for males and females. The adult-onset had a mean increase of 16.8 (range 12–22 cm). This long-term follow-up study shows that ELL can be done safely even with large lengthenings and that 4-segment lengthening may offer advantages over 2-segment lengthening. While all but the more recent cases were performed using external fixation, implantable limb lengthening promises to be an excellent alternative and perhaps an improvement.

Staged upper and lower limb lengthening performing bilateral simultaneous surgery of the femur and tibia in achondroplastic patients

INTRODUCTION

Surgical lengthening and angular correction of the limbs are an option for treating the orthopedic clinical manifestations in patients with achondroplasia. This study assesses a staged limb lengthening protocol, performing simultaneous bilateral lengthening of the femur and tibia (stage I [S1]), and humeral lengthening (stage II [S2]).

MATERIALS AND METHODS

Twenty-one achondroplastic patients were included in this study, and 106 segments (34 femurs, 34 tibias and 38 humeri) were lengthened. Achondroplasia patients with a growth curve below the mean of the standard growth curves for achondroplasia were included in S1. The remaining patients were included directly in S2. Variables analyzed included anthropometric measurements, lengthening outcomes, difficulties, and functionality.

RESULTS

Of the all patients included in the protocol, 15 patients completed S1 and S2, 4 only completed S2, and 2 only completed S1. Height and limb-trunk ratio before S1 were 107.65 ± 7.14 cm and 1.89 ± 0.10 and after S1 were 126.50 ± 9.19 cm and 1.64 ± 0.09, respectively. Limbs were lengthened 14.43 ± 1.41 cm (femurs and tibias) for S1 and 9.95 ± 0.60 cm for S2 (humeri), with a stage healing index of 18.23 ± 3.54 in S1 and 28.92 ± 4.42 in S2. Correction of lower angular deviations, functional improvement, and a controlled complications rate were achieved in all patients.

CONCLUSIONS

The limb lengthening protocol proposed in this study is a suitable treatment for achondroplasia patients to achieve the agreed-upon objectives (limb-trunk ratio, improved functionality, and lower limb alignment). The reproducibility of the procedure and patient safety were upheld.

Limb lengthening history, evolution, complications and current concepts

Limb lengthening continues to be a real challenge to both the patient and the orthopaedic surgeon. Although it is not a difficult operative problem, there is a long and exhausting postoperative commitment which can jeopardize early good results. I aim to review the history, evolution, biology, complications and current concepts of limb lengthening. Ilizarov's innovative procedure using distraction histeogenesis is the mainstay of all newly developing methods of treatment. The method of fixation is evolving rapidly from unilateral external fixator to ring fixator, computer assisted and finally lengthening intramedullary nails. The newly manufactured nails avoid many of the drawbacks of external fixation but they have their own complications. In general, the indications for limb lengthening are controversial. The indications have been extended from lower limb length inequality to upper extremity lengthening, including humeral, forearm and phalangeal lengthening. A wide range in frequency of complications is recorded in the English literature, which may reach up to 100% of cases treated. With developing experience, cosmetic lengthening has become possible using external or internal lengthening devices with an acceptable rate of problems.Level of evidence: V.

Achondroplasia: Development, pathogenesis, and therapy

Autosomal dominant mutations in fibroblast growth factor receptor 3 (FGFR3) cause achondroplasia (Ach), the most common form of dwarfism in humans, and related chondrodysplasia syndromes that include hypochondroplasia (Hch), severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN), and thanatophoric dysplasia (TD). FGFR3 is expressed in chondrocytes and mature osteoblasts where it functions to regulate bone growth. Analysis of the mutations in FGFR3 revealed increased signaling through a combination of mechanisms that include stabilization of the receptor, enhanced dimerization, and enhanced tyrosine kinase activity. Paradoxically, increased FGFR3 signaling profoundly suppresses proliferation and maturation of growth plate chondrocytes resulting in decreased growth plate size, reduced trabecular bone volume, and resulting decreased bone elongation. In this review, we discuss the molecular mechanisms that regulate growth plate chondrocytes, the pathogenesis of Ach, and therapeutic approaches that are being evaluated to improve endochondral bone growth in people with Ach and related conditions. Developmental Dynamics 246:291-309, 2017. © 2016 Wiley Periodicals, Inc.

Lower extremity growth and deformity

The pediatric lower extremity has well known growth patterns. When deformities or growth disturbances occur, there are several methods to measure and predict the resulting discrepancy, including the Green-Anderson, Moseley, and Multiplier methods. Many techniques exist to correct leg length discrepancy and deformity such and temporary epiphysiodesis, permanent epiphysiodesis, external fixators, and internal lengthening devices. All of these methods have numerous complications and limitations; however, with careful planning and patient selection, length and alignment can be improved with high patient satisfaction.