Outcomes of Simultaneous Lengthening and ACL Reconstruction in Fibular Hemimelia: A Retrospective Case Series.

Background: Fibular hemimelia is the most common congenital long bone deficiency. It is often associated with femoral and tibial deficiencies which result in a clinically evident leg length discrepancy. The primary soft tissue concern is ACL/PCL deficiency. If treatment includes bony lengthening, joint stability is imperative to avoid complications. In this study, we detail a novel technique for long bone lengthening and ACL reconstruction in a single, cohesive surgery. This consolidates the need for multiple procedures and offers improved limb length symmetry and knee stability for this patient population. Clinical outcomes of pediatric patients with hemimelia who underwent either femoral or tibial lengthening with PRECICE® nail and concomitant ACL reconstruction are presented. Methods: After IRB approval, we identified five patients with complex fibular hemimelia who underwent ACL reconstruction and concomitant lengthening with at least two years of follow-up. Two patients (40%) presented with congenital short femur, and three (60%) with congenital short tibia. In each case, ACL reconstruction and either femoral or tibial guided growth via PRECICE® nail were performed. Operative techniques involving both soft tissue and bony methodology are described in detail. Results: All patients had objective improvement in knee stability as assessed both intra and post operatively, as well as successful intermedullary lengthening without complications related to joint stability. Three patients had minor complications unrelated to joint stability that did not interfere with overall result. Conclusion: Fibular hemimelia associated with hypoplasia of bony and soft tissue structures can be successfully addressed with concomitant ligamentous reconstruction at the time of implantation of lengthening devices. This addresses knee instability and reduces both number of operative procedures and potential complications related to joint instability while pursuing bony lengthening. Level of Evidence: V.

Treatment of Recalcitrant Isolated Congenital Fibular Pseudarthrosis: Fibular Segment Transfer and Tibiofibular Synostosis with Unilateral External Fixator.

Isolated congenital pseudarthrosis of the fibula is a rare entity with a limited number of cases reported in the literature. Treatment is challenging because of recalcitrant nonunion and because no consensus about the best treatment plan exists. We report a case of isolated congenital fibular pseudarthrosis with valgus deformity of the ankle. The patient had a history of two failed operations. We used a novel surgical plan that combined tibiofibular synostosis with fibular segment transfer through a unilateral external fixator. The patient showed good early results with fibular union. We advocate the combination of tibiofibular synostosis and fibular segment transfer to restore the integrity and stability of the ankle in recalcitrant isolated congenital fibular pseudarthrosis cases with a history of failed surgery.

Fibular hemimelia.

Fibular hemimelia is defined as a partial or complete absence of the fibula. Alongside fibular deformities, there is a wide spectrum of anomalies, foot deformities, and absent rays. A literature review showed only a handful of cases of prenatal diagnosis of fibular hemimelia. It is a rare disorder that might be isolated or associated with visceral anomalies.

A case report on fibular aplasia, tibial campomelia, oligosyndactyly syndrome variant in a male infant.

Fibular aplasia, tibial campomelia, and oligosyndactyly (FATCO syndrome) is a rare, genetic, congenital limb malformation characterised by unilateral or bilateral fibular aplasia, tibial campomelia, and lower limb oligosyndactyly involving the lateral rays. A newborn male born at term via a Caesarean Section presented with malformations consisting of tibial campomelia, unilateral fibular hypoplasia, and oligosyndactyly, a "FATCO variant" case. On radiographic examination, an anterolateral shortened and bowed right lower limb at the distal third of the tibia, a rudimentary right fibula and absence of three rays on right foot were revealed. "FATCO syndrome" although rare may be linked to involvement of different body systems with morbidity and mortality. Proper parent counseling is a key aspect of this syndrome. Timely diagnosis and management with a multidisciplinary approach is essential to avoid lifelong disability, which can be a hurdle in a developing country.

Physical performance of children with longitudinal fibular deficiency (fibular hemimelia).

PURPOSE: Longitudinal fibular deficiency (LFD) is the most common congenital long bone deficiency. This study aimed to objectively assess the physical performance of children and adolescents with LFD compared with unaffected peers, and to examine trends over age for subgroups of the LFD population. METHODS: Differences between children with LFD and unaffected peers were examined with hand-held dynamometry for lower-limb muscle strength, Six-Minute Walk Test, Timed up and down stairs test, Star Excursion Balance Test, and Standing long jump. RESULTS: Thirty-nine children with LFD and 284 unaffected peers participated. Children with LFD performed at a lower level than their unaffected peers, on all measures of physical performance (mean 2.1 z-scores lower, all p < 0.01), except in long jump (p = 0.27). When comparing the performance of children with LFD to their unaffected peers across four age groups, there was a significant between-groups difference on all strength measures, and on the Six-Minute Walk distance, between children with and without LFD. These differences were smallest in young children (3-6 years) and largest in the older children (15-18 years) (all p < 0.01). Children with no lengthening surgery performed better on the Six-Minute Walk Test, covering a greater distance during the test, than those who had surgery (mean difference 83 metres, p < 0.01). There were no significant differences between children who had or had not undergone an amputation. CONCLUSIONS: Children with LFD performed at a significantly lower level than unaffected peers on all measures of physical performance other than jumping. The largest differences were in older children. This paper provides baseline functional data for future interventions in LFD. LEVEL OF EVIDENCE: Cross-sectional study.Implications for RehabilitationThis paper provides the first baseline functional data using validated objective measures on a consecutive cohort of children and adolescents with longitudinal fibular deficiency.Children with LFD performed significantly worse than their unaffected peers on all measures of physical performance other than jumping, with children falling further behind their peers as they age.Children who undergo an amputation typically have the most severe anatomical presentation and yet perform at an equivalent functional level.This paper identifies multiple modifiable impairments that represent potential opportunities for rehabilitation professionals to target with conservative treatment options to improve functional performance.

Bilateral Calcaneus Transfers for the Treatment of Congenital Tibial Deficiencies: A Novel Surgical Technique and Case Report.

Tibial deficiency (also known as tibial hemimelia) is a rare condition with variable presentation. A 2-month-old patient presented with absent bilateral tibias. When the patient was 1 year, a novel reconstructive surgery was done. A bilateral fibular resection with pedicled calcaneus transfer was done, allowing for transfer of the calcaneus along with the overlying glabrous skin and soft tissues to the end of the femur. The patient was permitted to weight-bear after the 4-week postoperative follow-up. At the six-month follow-up, the patient was able to pull to stand and walk with assistance without any reports of pain.

Prenatal diagnosis of fibular aplasia-tibial campomelia-oligosyndactyly syndrome: Two case reports and review of the literature.

Fibular aplasia-tibial campomelia-oligosyndactyly also known as FATCO syndrome is a rare condition characterized by fibular aplasia, shortening and anterior bowing of the lower limb at the tibia with overlying soft tissue dimpling and oligosyndactyly. Its etiology is currently unknown, but there is a male predominance. There are less than 30 cases reported in the literature but only three with prenatal diagnosis. We report two cases of FATCO syndrome with prenatal lower limb malformation diagnosis. Identification of the ultrasound findings of this condition in the prenatal stages allows an adequate parental counselling regarding the clinical features, prognosis, and potential treatments.

[Identification of a novel c.1A>G variant of GDAP1 gene in a pedigree affected with autosomal recessive fibula atrophy].

OBJECTIVE: To explore the genetic basis for a pedigree affected with Charcot-Marie-Tooth (CMT) disease through high-throughput sequencing. METHODS: Potential variants of the genes associated with CMT were screened by next-generation sequencing (NGS) of the members of the pedigree. RESULTS: NGS has revealed that the two affected sisters both harbored homozygous c.1A>G variant of the GDAP1 gene, which caused replacement of the first amino acid Methionine by Valine (p.Met1Val). Their parents were both carriers of the heterozygous c.1A>G variant. The variant was unreported previously and has an extremely low frequency in the population. Meanwhile, one of the sisters and the mother also carried heterozygous c.710A>T variant of the BAG3 gene. CONCLUSION: The homozygous c.1A>G variant of the GDAP1 gene probably underlay the CMT in both children. Above result has enabled clinical diagnosis and genetic counseling for this pedigree.

Deformity progression in congenital posteromedial bowing of the tibia: a report of 44 cases.

BACKGROUND: congenital posteromedial bowing of tibia (CPMBT) is a very rare birth defect, characterized by shortened bowed leg and ankle deformity. We described a single institution experience in the management of CPMBT. METHODS: we identified 44 CPMBT in 44 children. The age at presentation was 5.5 ± 5.6 years and the mean age at the final review was 10.1 ± 4.8 years. Radiographic evaluation included the antero-posterior and lateral inter-physeal angle (AP-IPA and L-IPA), the limb length discrepancy (LLD), the morphology of the distal tibia and the lateral distal tibial angle (LDTA). During the study period, 26 children underwent surgical treatment. RESULTS: the estimated curves showed a progressive spontaneous correction of both AP-IPA and L-IPA during growth, but a progressive increase of the LLD. The L-IPA showed a more predictable behaviour while the AP-IPA showed a scattered correction, with a wider variation of the estimated final angle. The final LDTA was 85.3° ± 4.2° and was correlated with the L-IPA (r = 0.5; p = 0.02). Among the 26 children who underwent surgical treatment, 23 cases had limb lengthening, 1 case had contralateral epiphysiodesis, 1 child underwent tibial osteotomy, 1 patient was treated by hemiepiphysiodesis of the distal tibia to correct ankle valgus deformity. CONCLUSIONS: our study described the largest case series of CPMBT. A combination of surgical treatments, in a staged surgical process, should be tailored to the developmental characteristics of this abnormality. An experience-based algorithm of treatment is also proposed. Further studies are needed to understand which is the best strategy to correct this deformity during childhood. LEVEL OF EVIDENCE: level IV prognostic study.

Management of Tibial Bow in Fibular Deficiency.

BACKGROUND: Deformity of the tibia, including shortening and angulation, may accompany severe forms of postaxial hypoplasia (fibular deficiency). The current literature reflects varying opinions on the appropriate management for tibial deformity in the setting of fibular deficiency. METHODS: We performed a retrospective review to determine outcomes of tibial deformity correction in patients with a primary diagnosis of fibular deficiency. Clinical and radiographic outcomes of patients treated with foot ablation were reviewed to establish indications for tibial deformity correction, identify occurrence of additional surgical procedures related to limb alignment or deformity, and characterize difficulties with prosthetic wear potentially related to residual or recurrent tibial deformity. RESULTS: From 1989 to 2016, 51 patients (57 extremities) with fibular deficiency were managed with a foot ablation procedure. Twenty-five (44%) had simultaneous correction of the tibial deformity. The initial tibial deformity measured 42.5 degrees, was corrected to 5.6 degrees intraoperatively, and measured 18.6 degrees at follow-up, suggesting recurrent deformity. In follow-up, approximately half of the patients complained of redness and one third complained of a continued prominence along the anterior tibia. Thirty-two extremities had an isolated foot ablation procedure without tibial osteotomy. Radiographic review demonstrated mild tibial bowing at the time of amputation with a mean angular deformity of 15.4 degrees and remained unchanged during the follow-up period (mean, 12.7 degrees). Similar to the osteotomy group, approximately half of the patients complained of redness and erythema over the anterior bow, with one fourth noting prominence, and only 2 reporting significant pain. CONCLUSIONS: Tibial osteotomies in patients with more significant degrees of angular deformity can be safely performed at the same setting as foot ablative procedures for fibular deficiency. Recurrent deformity with growth may occur. Patients and their caregivers should be aware that rebound deformity may occur, but typically can be managed with prosthetic adjustment and without significant disruption to the child's daily activities. LEVEL OF EVIDENCE: Level IV (case series).

Correction of Genu Valgum in Patients With Congenital Fibular Deficiency.

BACKGROUND: Patients with congenital fibular deficiency often develop genu valgum secondary to lateral femoral condylar hypoplasia. Guided growth strategies are often performed to correct limb alignment when adequate skeletal growth remains. METHODS: A retrospective review of patients with postaxial hypoplasia of the lower extremity managed with an amputation strategy and who had a guided growth procedure for coronal plane limb malalignment during their course of treatment was performed. Clinical and radiographic data, including measures of coronal plane deformity and alignment, type of amputation, subsequent operative procedures, and complications were recorded. RESULTS: Seventeen patients (20 extremities) met study inclusion criteria (mean follow-up 8.8 y). Foot ablation and hemiepiphysiodesis for valgus deformity of the knee was performed in all extremities. The average age at the time of initial hemiepiphysiodesis was 11.2 years at an average of 8.8 years from the initial amputation procedure. The mean preoperative mechanical axis deviation was 26.5 mm, which was corrected to a mean mechanical axis deviation of 7.0 mm. Fifteen (75%) of the extremities had correction of the deformity to neutral alignment after the initial procedure. Lack of correction occurred in 3 extremities, and overcorrection occurred in 2 extremities. Additional procedures were required in 5 extremities for rebound valgus deformity after hardware removal. CONCLUSIONS: In patients with postaxial hypoplasia, regular monitoring of the residual limb for growth-related changes must occur to ensure optimal function and prosthetic fit. Timing of the guided growth procedure is critical, as younger patients may be more likely to experience rebound deformity. Families and patients should be made aware that growth might be unpredictable in this population with risks of both overcorrection and undercorrection. LEVEL OF EVIDENCE: Level IV-case series.

Congenital Pseudarthrosis of the Fibula: Controlling Ankle Valgus in a Heterogenous Condition.

BACKGROUND: Congenital pseudarthrosis of the fibula (CPF) is a rare disorder characterized by a deficiency in the continuity of the fibula and can lead to progressive ankle valgus malalignment. An existing classification system for CPF is imperfect and may contribute to heterogeneity in reporting and discrepancy of outcomes in the literature. METHODS: Fifteen patients with CPF treated at our institution between 1995 and 2017 were retrospectively identified. Only patients with dysplasia leading to spontaneous fracture or pseudarthrosis were included in this series. The median age at presentation was 2.5 years (range: 3 mo to 13.4 y). The median duration of follow-up from the initial presentation was 11.8 years (range: 2.0 to 24 y). Chart review and serial radiographs were analyzed to assess natural history and outcomes following surgery. RESULTS: The coexistence of tibial dysplasia in CPF is very common. Patients were classified into 3 groups based on the degree of tibial involvement-group 1: no evidence of tibial dysplasia, group 2: mild tibial dysplasia, and group 3: significant tibial dysplasia. Age at presentation and age at which fibular fracture occurred were progressively younger with a greater degree of tibial involvement (P<0.05). In the absence of surgical intervention, group 1 patients did not undergo progressive ankle valgus (defined as the valgus change in tibiotalar angle by ≥4 degrees), whereas all patients in groups 2 and 3 did (P<0.001). Fibular osteosynthesis was performed in 6 patients, with union seen only in group 1 patients. Ten patients underwent distal tibiofibular fusion, with no cases of nonunion seen. Distal tibiofibular fusion with or without medial distal tibial hemiepiphysiodesis halted the progression of ankle valgus in 8 of the 10 patients. Further progression of ankle valgus occurred only in patients who did not undergo concurrent medial distal tibial hemiepiphysiodesis and with considerable wedging of the distal tibial epiphysis at the time of fusion. CONCLUSIONS: Tibial dysplasia and CPF are intimately related. Grouping patients on this basis may help guide natural history and treatment and may explain discrepancies in findings in the literature. Fibular osteosynthesis, distal tibiofibular fusion, and medial distal tibial hemiepiphysiodesis may all have an important role in the treatment of CPF. LEVEL OF EVIDENCE: Level IV-case series.

Amputation Versus Limb Reconstruction for Fibula Hemimelia: A Meta-analysis.

PURPOSE: Fibula hemimelia is the most common congenital deficiency of long bones. Primary treatment options include amputation with prosthetic fitting or limb reconstruction. The aim of our study was to conduct a systematic review comparing amputation with limb reconstruction for fibula hemimelia. METHODS: MEDLINE, EMBASE, Web of Science, Elsevier Scopus, and the Cochrane Registry of Clinical Trials were searched from 1951 to 2019 for studies that evaluated amputation versus limb reconstruction for fibula hemimelia. Random effect models were utilized for the meta-analytic comparisons of amputation versus limb reconstruction for patient satisfaction and surgical complications. Descriptive, quantitative, and qualitative data were extracted. RESULTS: Seven retrospective cohort studies were eligible for the meta-analysis, with a total of 169 fibula hemimelia cases. Amputation resulted in an odds ratio of 6.8 (95% confidence interval: 2.4, 19.2) when compared with limb reconstruction in terms of patient satisfaction. Furthermore, limb reconstruction was found to have an odds ratio of 28 (95% confidence interval: 7.8, 100.3) for complications. The total surgical complication rates in the amputation and limb reconstruction groups were 0.2 and 1.2 complications per limb. The rate of surgical procedures per patient was 1.5 and 4.2 for amputation and limb reconstruction, respectively. CONCLUSIONS: The cumulative evidence at present indicates better patient satisfaction with less surgical complications and less number of procedures with amputation for fibula hemimelia when compared with limb reconstruction. Absence of uniform protocols make it difficult to compare results accurately. LEVEL OF EVIDENCE: Level III-therapeutic.

Upper extremity anomalies in children with femoral and fibular deficiency.

Defects occurring in the femoral-fibular-ulnar developmental field are believed to cause the cluster of anomalies seen with femoral, fibular and ulnar limb deficiencies. Upper limb function must be considered in the management of lower limb deficiencies. The purpose of this study is to determine the frequency and type of upper extremity anomalies found in children with femoral and/or fibular deficiency. A retrospective review of 327 consecutive patients with the diagnosis of femoral and/or fibular deficiency was performed using existing records and radiographs. Characteristics of those with and without upper extremity anomalies were compared. Upper extremity anomalies were identified in 56 patients. They were more common among those with bilateral, compared with unilateral, lower extremity deficiencies (P < 0.0001). Seventy-five upper limbs were involved with 50 ulnar deficiencies, nine congenital transhumeral deficiencies, four congenital shoulder disarticulations, seven cleft hands, two radial head dislocations and one each - radial deficiency, syndactyly and capitate-lunate coalition. Two patients with bilateral upper extremity anomalies had ulnar deficiency on one side and a transverse deficiency on the other. Upper extremity anomalies are found in 17% of children with femoral and/or fibular deficiency, especially with bilateral lower extremity involvement. Ulnar deficiency is the most common type but one-third had other anomalies. The frequent finding of congenital transverse upper extremity deficiencies suggests there may be common embryology.

Congenital fibular dystrophisms conform to embryonic arterial dysgenesis.

The congenital short limb (CSL) with fibular deficiency has traditionally been graded by plain radiography. The most popular orthopedic classification sorts the fibular dysmorphologies into three radiographic groupings: IA (thinned), IB (proximally truncated), or II (absent). In contrast, the soft tissues have been relatively neglected. Since bone formation of the fibula progresses from the anlage, a scaffolding cartilage mold intermediate, cartilage transformation to bone is dependent upon timely embryonic arterial invasion. Absences of the requisite arteries predicate specific skeletal dysmorphologies. The usual arterial supply of the fibula is comprised primarily of the anterior tibialis artery (ATA), which uniquely supplies the proximal portion of the fibula, and also joins the peroneal artery (PA) in supplying the mid to distal fibular shaft. Combinations of the two nutrient arteries allow four potential variations of fibular vascular supply, among which the ATA and PA conjoin to supply the normal fibula and variably supply the three dysmorphic fibular models. The IA and IB deformities conform, respectively, to the absences of the PA and the ATA. Combined ATA and PA absences present in the radiographically "absent" fibula. Thus, each of the four fibular (dys)morphologies conforms to a specific embryonic pattern of arterial development. The term "dystrophism" most accurately characterizes such malformed long bones.

Morphological Characteristics of Os Subfibulare Related to Failure of Conservative Treatment of Chronic Lateral Ankle Instability.

BACKGROUND: The os subfibulare is usually asymptomatic and found incidentally on radiographs. However, sometimes it may cause subfibular pain and may be associated with chronic lateral ankle instability (CLAI). We hypothesized that os subfibulare could interrupt the talofibular space causing impingement, resulting in chronic pain and functional instability around the lateral malleolus. The purposes of this study were to analyze morphologic characteristics of os subfibulare, and to evaluate the clinical significance of the os subfibulare in patients with CLAI. METHODS: Between November 2011 and April 2015, 70 patients who had both computed tomography (CT) and magnetic resonance imaging (MRI) among 252 patients who visited our hospital with the symptom of lateral ankle instability were included in this study. The location of the ossicle was classified into 3 zones in reference to the attachment site of the lateral ankle ligaments. The impingement was classified into 2 groups according to the presence of talofibular encroachment. Digital radiographs were used to measure the ossicle width and shape determined by the length and width on an magnetic resonance (MR) image. RESULTS: The most common shape of ossicles was oval, and the most common location of ossicles was at the anterior talofibular ligament (ATFL) attachment site. Sixty-one percent of patients showed talofibular impingement on coronal MR images. In 48 cases, the dimension of fibula plus os subfibulare was larger than that of the contralateral normal fibula. The larger size and talofibular impingement of the ossicle were associated with greater need for operative treatment in patients with ankle instability. CONCLUSION: The morphologic analysis of the os subfibulare revealed that there might be impingement of the talofibular space by the ossicle in some patients. We suggest that morphologic characteristics of the os subfibulare should be considered when selecting treatment options in patients with CLAI and os subfibulare. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Identification of a novel c.1A>G variant of GDAP1 gene in a pedigree affected with autosomal recessive fibula atrophy / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a pedigree affected with Charcot-Marie-Tooth (CMT) disease through high-throughput sequencing.@*METHODS@#Potential variants of the genes associated with CMT were screened by next-generation sequencing (NGS) of the members of the pedigree.@*RESULTS@#NGS has revealed that the two affected sisters both harbored homozygous c.1A>G variant of the GDAP1 gene, which caused replacement of the first amino acid Methionine by Valine (p.Met1Val). Their parents were both carriers of the heterozygous c.1A>G variant. The variant was unreported previously and has an extremely low frequency in the population. Meanwhile, one of the sisters and the mother also carried heterozygous c.710A>T variant of the BAG3 gene.@*CONCLUSION@#The homozygous c.1A>G variant of the GDAP1 gene probably underlay the CMT in both children. Above result has enabled clinical diagnosis and genetic counseling for this pedigree.

Widely Divergent Congenital Inferior Tibiofibular Diastasis with Separate Soft-Tissue Cover and Persistent Sciatic Artery: A Previously Unreported Combination: A Case Report.

CASE: We report a case of a child with widely divergent congenital inferior tibiofibular diastasis with persistent sciatic artery (PSA). The dysplastic tibia and fibula were widely divergent, and the fibula was displaced proximally and medially with the foot alongside the thigh between the 2 legs, with PSA diagnosed on computed tomography angiogram. The child was treated with fibula-foot complex excision and below-knee prosthesis and was ambulating independently at 1-year follow-up. CONCLUSIONS: The combination of a major structural anomaly (tibiofibular diastasis with a separate soft-tissue cover) and an unusual vascular malformation (PSA) has not been reported previously and made surgical reconstruction challenging.

Lengthening With Monolateral External Fixation Versus Magnetically Motorized Intramedullary Nail in Congenital Femoral Deficiency.

BACKGROUND: Limb lengthening for congenital femoral deficiency (CFD) with or without fibular hemimelia can be performed with both external and internal devices. The purpose of this study is to compare clinical outcomes of femoral lengthening utilizing monolateral external fixation versus a magnetically motorized intramedullary nail in patients with CFD with or without fibular hemimelia. METHODS: This retrospective review included 62 patients with femoral lengthening, 32 patients had monolateral external fixation (group A), 30 patients had internal lengthening nail (group B). Mean age in years was 9.4±3.8 and 15.4±4.9 for groups A and B, respectively. Mean follow-up in years was 4.47±2.7 and 1.86±0.7 years for groups A and B, respectively. RESULTS: Mean lengthening achieved was 5.6±1.7 and 4.8±1.4 cm for group A and group B, respectively (P=0.052). Mean distraction index was 0.7±0.2 mm/d for group A and 0.7±0.2 mm/d for the group B (P=0.99). Mean consolidation index for group A was 29.3±12.7 and 34.8±11.2 d/cm for group B (P=0.08). Mean arc of motion before surgery and at final follow-up were similar between groups (P=0.35). Group A had significantly less range of motion at the end of distraction (P=0.0007) and at consolidation (P<0.0001). Both groups had similar rates of obstacles and complications. A significant difference between groups was found in the total problems (P<0.001) specifically with pin site/superficial infection (P<0.0001). CONCLUSIONS: The intramedullary nail had superior range of motion during the lengthening phase and at consolidation and an overall lower problem complication rate, while maintaining similar distraction and healing indices to monolateral external fixation. Internal lengthening nails represent a significant advance in technology for CFD lengthening. LEVEL OF EVIDENCE: Level IV-therapeutic.