Radiological classification of congenital pseudarthrosis of the tibia

Free Fibula Flap for Congenital Pseudarthrosis of the Tibia: Indications and Challenges

Background

Congenital pseudoarthrosis of the tibia (CPT) is a rare pathological disease associated with neurofibromatosis type 1 (NF1). It presents with tibial bowing and can progress into a nonhealing fracture. Treatment options include conservative approaches such as serial bracing or various surgical options.Surgically, the aims are to achieve long-term bone union, prevent limb length discrepancies (LLDs), and avoid mechanical axis deviation, soft tissue lesions, nearby joint stiffness, and pathological fracture.The purpose of our study is to highlight our experience with both the conservative approach and the use of vascularized free fibula reconstruction of these deformities, including the challenges encountered with a long-term follow-up until skeletal maturity.

Methods

We present a retrospective analysis of a total of nine (9) patients consisting of three (3) girls and six (6) boys. Six (6) children were treated with a vascularized fibula flap, and the other three (3) were treated conservatively. Outcomes measured included fractures, LLD, ankle valgus deformity, donor site morbidity, and number of surgical corrections.

Results

All patients had flap survival. Three (3) of six children had a previous failed surgery with intramedullary nail and bone graft prior to performing a vascularized free fibula reconstruction. The follow-up period ranged from 8 months to 200 months. The complications included stress fractures (50%), LLD (66.6%), and ankle valgus (33.3%). During growth phases, these children required multiple corrective surgeries.

Conclusions

Fibula free flap is a good treatment option for CPT even in patients with prior surgical failures with variable results.Level of Evidence - Level 4 - Case series Therapeutic Studies-Investigating the Results of Treatment.

Congenital Pseudoarthrosis of Tibia With Anterolateral Bowing Treated With Ilizarov Ring Fixator: A Case Report

Congenital pseudarthrosis of the tibia (CPT) is a rare, dysplastic condition that is characterized by a "false joint" in the tibia, leading to potential disability. We present a rare case report of a 12-year-old male from India with a history of neurofibromatosis type 1 (NF1) and anterolateral bowing of the tibia since birth. He sustained a tibial fracture during play. X-ray evaluation confirmed the fracture, and a clinical diagnosis of CPT was established. The treatment involved corticotomy for deformity correction and stabilization using Ilizarov's ring fixation. The procedure was successful, with post-operative radiological evaluations showing significant improvement in the center of rotation of angulation (CORA) from 60° pre-operatively to 25° post-operatively. The patient was discharged with an external fixator and after seven months, transitioned to full weight-bearing ambulation with a specialized brace. The Ilizarov procedure proved to be a safe and effective treatment for CPT, offering benefits such as limb lengthening and ankle stabilization.

Combination of the Ilizarov Method and Intramedullary Fixation for the Treatment of Congenital Pseudarthrosis of the Tibia in Children: A Retrospective Observational Study

Purpose

Congenital pseudoarthrosis of the tibia (CPT) is a rare disease in children, and its treatment remains a challenge for orthopedic surgeons. The purpose of this study was to evaluate treatment outcomes of patients with CPT treated by using the Ilizarov method combined with intramedullary fixation.

Method

Eighteen patients evaluated retrospectively from January 2009 to January 2020 were treated using the Ilizarov method combined with intramedullary fixation. Demographic data, clinical characteristics, and complications were all recorded and investigated during the period of follow-up. Ankle function was evaluated by the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scores at the last follow-up.

Result

The average follow-up was 39.2 months (25–85 months) for all 18 patients. The mean age was 6.2 years (3.5–11.2 years). Fourteen (77.8%) patients had a primary bone union at the site of pseudarthrosis, while four obtained union after secondary surgical intervention. The mean duration of the Ilizarov method was 8.1 months (4.2–13.5 months). Eight (44.4%) patients had a pin-tract infection during treatment. Four (22.2%) patients had proximal tibial valgus with a mean angle of 12.1° (5–25°), while seven (38.9%) patients had ankle valgus deformities with a mean of 10.3° (5–20°). Eleven (61.1%) patients had an average 1.4 cm of limb length discrepancy (LLD) (0.6–3.1 cm) postoperatively. Five (27.8%) patients had refracture and recovered after a secondary surgery. At the last follow-up, the average postoperative AOFAS score was 72 (55–84).

Conclusion

The Ilizarov method combined with intramedullary fixation is an effective method for the treatment of CPT, which can facilitate bony union and help to prevent refracture. Management of fibular pseudarthrosis is associated with functional outcomes. It is necessary to follow up until skeletal maturity and evaluate long-term clinical outcomes.

Reconstructive Approaches in Surgical Management of Congenital Pseudarthrosis of the Tibia

Treatment of congenital pseudarthrosis of the tibia remains a major challenge in pediatric orthopedics. Ideal timing and preference of surgical procedures are discussed controversially. A variety of reconstructive treatment strategies have been described in literature, but so far none has proven its superiority. The aim of treatment is to obtain long-term bone union, to prevent refracture, and to correct angular deformities and leg length discrepancies. This study retrospectively evaluates the outcome of different reconstructive strategies. Sixty-nine patients were identified who presented to our outpatient department between 1997 and 2019. Twenty-six of these patients underwent reconstructive surgical treatment and were included in this study. The study cohort was divided into three groups. Excision of the pseudarthrosis was performed in all patients in Group A and B, and in two patients of Group C. Group A (six/26 patients) received subsequent bone transport through external fixation maintaining original length. In Group B (15/26 patients), patients underwent either previous, simultaneous, or subsequent extrafocal lengthening through external fixation to reconstitute length. In Group C (five/26 patients), internal fixation with intramedullary nails was applied. Radiological and clinical evaluation was performed to assess bone union and complication rates. Results varied considerably between the study groups. Overall, the primary bone fusion rate was 69.2%. There were four refractures, all occurring in Group B. The long-term bone union rate without refracture was 53.8%. The overall complication rate was 53.8% and 23.1% showed persistent pseudarthrosis. Two secondary amputations were performed due to failed bone fusion. In conclusion, excision of the pseudarthrosis and extrafocal lengthening achieves a satisfying bone union rate and limb reconstruction, while bone transport does not offer significant advantages but shows higher complication rates. Intramedullary stabilization should be applied to maintain bone union, but shows lower bone union rates when used as a stand-alone treatment regimen. Regardless of the primary bone fusion rates, the probability of long-term bone union remains unpredictable.

Diagnostic and treatment challenge in adult presentation of congenital pseudoarthrosis of the tibia: A case report

Introduction

Congenital pseudoarthrosis of the tibia is a rare congenital disease. Late presentation in adult, makes the diagnostic far more challenging and often misdiagnosed as a common non-union fracture with high re-operation rate. In long courses of repeated surgery, non-union persisted along with severe leg length discrepancy.

Case presentation

A 19-year-old male presented with history of left tibia fracture with repeated surgery. Current problems were progressed bowing of the left lower leg and length discrepancy without recent injury. There was a sign of neurofibroma and pseudoarthrosis at distal third of the tibia shaft with fibula involvement. A radical resection was performed followed by staged deformity correction with Ilizarov's method which was consisted of bone transport procedure in 4 months and lengthening procedure in another 4 months, without grafts.

Discussion

After one-year, patient achieved union at docking site, equal lower limb length, good alignment and consolidation in bone transport and lengthening site. Three months after frame removal patient has achieved functional bipedal gait with no sign of recurrence.

Conclusion

Diagnostic and therapeutic challenge in the late onset of congenital pseudoarthrosis of tibia is in differentiating it with another cause of non-union and in dealing with deformities. Although none of surgical methods have proven their superiority, reconstruction using Ilizarov method is proved to be safe, practical, and effective to solve both problems. However, the patient still needs to be closely observed and protected weight bearing due to the refractory nature of the disease.

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No gold standard of treatment in congenital pseudoarthrosis.

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Late presentation of CPT makes the diagnostic far more challenging and it often misdiagnosed as a common non-union fracture with high re-operation rate.

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Ilizarov method is not a modern technique but it is proved to be safe, simple, practical, and effective to solve both deformity and pseudoarthrosis problems in CPT.

Congenital pseudarthrosis of the tibia: biological and biomechanical considerations to achieve union and prevent refracture

Congenital pseudarthrosis of the tibia (CPT) is likely to be a primary periosteal disease and secondary bone disease. The primary goal of treatment is to obtain union, correct the diaphyseal deformity, correct any proximal fibular migration and prevent refracture. The pathobiology demonstrates increased osteoclasis by the surrounding fibrous hamartoma and reduced osteogenesis and bone morphogenic protein production by the bone. This leads to a loss of remodelling potential and gradual bowing and atrophy of the bone with eventual fracture of the tibia and or fibula. This recommends the synergistic use of bisphosphonates and bone morphogenic protein. The pathomechanics of CPT implicate the anterolateral bowing, narrow diameter of the atrophic bone ends and proximal fibular migration. These biomechanical factors can be addressed by means of straightening of the deformity, intramedullary support of both bones, stable fixation and reduction of proximal migration of the fibula. A summary of the literature on CPT shows that the mean probability of achieving primary union without refracture, by most treatments is 50% (12% to 80%). Two recent studies have shown a much higher success rate approaching 100%, by creating a cross-union between the tibia and fibula. The cross-union with intramedullary reinforcement of the bone makes refracture unlikely due to the cross-sectional area of union with its two-bar linkage. A new classification to guide such treatment is also proposed.

LEVEL OF EVIDENCE

V - expert opinion.

Evaluation of bone marrow-derived mesenchymal stem cell quality from patients with congenital pseudoarthrosis of the tibia

Background

The treatment of congenital pseudoarthrosis of the tibia (CPT) remains challenging in pediatric orthopedics due to the difficulties in bone union, continuous angulation, joint stiffness, and severe limb length discrepancy. Mesenchymal stem cells (MSCs) therapy offers a complementary approach to improve the conventional surgical treatments. Although the autologous MSC treatment shows a promising strategy to promote bone healing in CPT patients, the quality of MSCs from CPT patients has not been well studied. The purpose of this study is to investigate the quality of MSCs isolated from patients with CPT.

Methods

The bone marrow-derived MSCs from the fracture site and iliac crest of six CPT patients were isolated and compared. The cumulative population doubling level (cPDL), phenotype characteristics, and trilineage differentiation potency were observed to assess the quality of both MSCs.

Results

There were no significant differences of the MSCs derived from the fracture site and the MSCs from the iliac crest of the subjects, in terms of cPDL, phenotype characteristics, and trilineage differentiation potency (all p > 0.05). However, MSCs from the fracture site had a higher senescence tendency than those from the iliac crest.

Conclusion

MSC quality is not the main reason for delayed bone regeneration in those with CPT. Thus, autologous MSC is a promising source for treating CPT patients

Does pamidronate enhance the osteogenesis in mesenchymal stem cells derived from fibrous hamartoma in congenital pseudarthrosis of the tibia?

Neurofibromatosis type 1 (NF1) is a commonly occurring genetic disorder in children. Mutation in the NF1 gene has its implication in poor osteoblastic capabilities. We hypothesised that pamidronate will enhance the osteoblastic potential of the mesenchymal stem cells (MSCs) derived from lipofibromatosis tissue of children with congenital pseudarthrosis tibia (CPT) associated with NF1. In this study, bone marrow MSCs (BM MSCs) and CPT MSCs were obtained from three patients undergoing salvage surgeries/bone grafting (healthy controls) and those undergoing excision of the hamartoma and corrective surgeries respectively. The effects of pamidronate (0, 10 nM, 100 nM and 1 μM) on cell proliferation, toxicity and differentiation potential were assessed and the outcome was measured by staining and gene expression. Our outcome showed that CPT MSCs had more proliferation rate as compared to BM MSCs. All 3 doses of pamidronate did not cause any toxicity to the cells in both the groups. The CPT MSCs showed less differentiation with pamidronate compared to the healthy control MSCs. This was quantitated by staining and gene expression analysis. Therefore, supplementation with pamidronate alone will not aid in bone formation in patients diagnosed with CPT. An additional stimulus is required to enhance bone formation.

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First study demonstrating the differentiation potential of MSCs derived from the hamartoma using pamidronate

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The CPT MSCs have lower osteogenic potential as compared to BM MSCs.

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The osteoblastic response does not improve with the addition of pamidronate (1 μM) in CPT MSCs.

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Pamidronate enhances osteogenic differentiation in normal BM MSCs.

Isolation and Characterization of Multipotential Mesenchymal Stromal Cells from Congenital Pseudoarthrosis of the Tibia: Case Report

Congenital pseudoarthrosis of the tibia (CPT) is an uncommon disease whose etiology and pathogenesis is unknown. Several evidences suggest that decreased osteogenic capacities, impaired local vascularization, and microenvironment alterations may play a role in the pathogenesis of CPT. Additionally, it is not clear if the pathogenesis of this disease is related to the absence of cells with osteogenic capacity of differentiation. In this work, a two-year-old patient diagnosed with CPT underwent an orthopedic surgery to promote bone union in a pseudoarthrosis lesion. Tissue from CPT lesion was excised, and histological evaluation and tissue culture were performed. Histologic analysis of the soft CPT lesion showed the presence of highly cellular fibrous tissue, vascularization, and abundant extracellular matrix. Fusiform cells of mesenchymal appearance were observed but osteoblasts, osteoclasts, chondrocytes, and adipose cells were not found. There was no evidence of osteogenesis. CPT tissue cultured as explants showed, after one month of culture, evidence of osteogenesis, chondrogenesis, and adipogenesis. Cells isolated from explants of CPT tissue showed a fibroblast-like morphology and expressed the mesenchymal stromal cell (MSC) markers: CD105, CD73, and CD90 (CPT-MSC). Functional analysis showed that CPT-MSC differentiate, in vitro, into osteogenic, chondrogenic, and adipocytic cells. CPT-MSC expressed osteocalcin and agrecan. CPT-MSC produced collagen in the presence of ascorbic acid. MSC from BM of normal individuals were used as control. In summary, our results indicate that CPT tissue contains MSC with osteogenic capacity of differentiation. It is possible that CPT microenvironment may contribute to impair the osteogenic capacity of differentiation of CPT-MSC.

Epidemiology and treatment outcome of congenital pseudarthrosis of the tibia

PURPOSE

Congenital pseudarthrosis of the tibia (CPT) is a rare disease. Epidemiological data are limited, and treatment of the condition is challenging. The purpose of our study was to gain epidemiological data on the incidence of CPT in Norway and to evaluate the treatment outcome of the disease.

METHODS

During the period 1987-2006 22 patients with CPT were born in Norway (11 boys, 11 girls; mean age 15 years, age range 8-24 years) and are included in this study. During the same time period 1,183,380 live-births were registered by the Norwegian Birth Register. Primary surgical treatment was the Ilizarov method in 15 patients, intramedullary nailing in three patients, and plate osteosynthesis in two patients; two patients never developed a fracture and were treated with an orthosis.

RESULTS

The incidence of CPT based on this period was 1:53,000. The rate of primary healing was 66 % for the Ilizarov group. Primary healing occurred in three patients treated with intramedullary nailing and in none of the patients treated with plate osteosynthesis. However, almost all patients required additional surgery due to refracture or deformity correction. Currently, all 12 skeletally mature patients are considered to be healed, whereas two of the skeletally immature patients are still under treatment.

CONCLUSION

The incidence of CPT in Norway seems to be notably higher than that based on epidemiological data from other studies. Primary healing rates are satisfactory when treated either with an Ilizarov device or intramedullary nailing. Refractures must be avoided, and alignment of the leg must be maintained. Healing is usually achieved before skeletal maturity. However, residual deformities are common.

Successful treatment of congenital pseudarthrosis of the tibia: still a challenge

The congenital pseudarthrosis of the tibia (CPT) is one of the most challenging problems in pediatric orthopedics. The primary treatment goals are outlined as osteosynthesis, stabilization of the ankle mortise by fibular stabilization and lower-limb-length equalization. Despite the fact that each of the aforementioned goals is difficult to be achieved regardless the surgical option, the main biological consideration is the same: pseudarthrosis resection, biological bone bridging of the defect by stable fixation and the correction of any angular deformity. The external fixation method is suggested as valuable treatment of CPT because it can address not only pseudarthrosis but also all complex deformities associated with this condition. However, treatment of CPT is impaired with complications due to the complex nature of the disease thus failure is common. The most common of these are refracture, growth disturbance, poor foot and ankle function with stiffness. Of these, refracture is the most common and serious complication after primary healing and might result in the reestablishment of pseudarthrosis. Therefore, an effective, safe and practical treatment method that minimizes the residual challenges after healing and accomplishes the multiple goals of treatment is needed. In this article, we report a patient with CPT treated successfully with external fixation. Level of evidence IV retrospective.

Limb Lengthening and Reconstruction Society AIM index reliably assesses lower limb deformity

BACKGROUND

Although several systems exist for classifying specific limb deformities, there currently are no validated rating scales for evaluating the complexity of general lower limb deformities. Accurate assessment of the complexity of a limb deformity is essential for successful treatment. A committee of the Limb Lengthening and Reconstruction Society (LLRS) therefore developed the LLRS AIM Index to quantify the severity of a broad range of lower extremity deformities in seven domains.

QUESTIONS/PURPOSES

We addressed two questions: (1) Does the LLRS AIM Index show construct validity by correlating with rankings of case complexity? (2) Does the LLRS AIM Index show sufficient interrater and intrarater reliabilities?

METHODS

We had eight surgeons evaluate 10 fictionalized patients with various lower limb deformities. First, they ranked the cases from simplest to most complex, and then they rated the cases using the LLRS AIM Index. Two or more weeks later, they rated the cases again. We assessed reliability using the Kendall's W test.

RESULTS

Raters were consistent in their rankings of case complexity (W = 0.33). Patient rankings also correlated with both sets of LLRS AIM ratings (r(2) = 0.25; r(2) = 0.23). The LLRS AIM Index showed interrater reliability with an intraclass correlation (ICC) of 0.97 for Trial 1 and 0.98 for Trial 2 and intrarater reliability with an ICC of 0.94. The LLRS AIM Index ratings also were highly consistent between the attending surgeons and surgeons-in-training (ICC = 0.91).

CONCLUSIONS

Our preliminarily observations suggest that the LLRS AIM Index reliably classifies the complexity of lower limb deformities in and between observers.

Congenital pseudarthrosis of the tibia: Management and complications

Congenital pseudarthrosis of the tibia (CPT) is a rare pathology, which is usually associated with neurofibromatosis type I. The natural history of the disease is extremely unfavorable and once a fracture occurs, there is a little or no tendency for the lesion to heal spontaneously. It is challenging to treat effectively this difficult condition and its possible complications. Treatment is mainly surgical and it aims to obtain a long term bone union, to prevent limb length discrepancies, to avoid mechanical axis deviation, soft tissue lesions, nearby joint stiffness, and pathological fracture. The key to get primary union is to excise hamartomatous tissue and pathological periosteum. Age at surgery, status of fibula, associated shortening, and deformities of leg and ankle play significant role in primary union and residual challenges after primary healing. Unfortunately, none of invasive and noninvasive methods have proven their superiority. Surgical options such as intramedullary nailing, vascularized fibula graft, and external fixator, have shown equivocal success rate in achieving primary union although they are often associated with acceptable results. Amputation must be reserved for failed reconstruction, severe limb length discrepancy and gross deformities of leg and ankle. Distinct advantages, complications, and limitation of each primary treatment as well as strategies to deal with potential complications have been described. Each child with CPT must be followed up till skeletal maturity to identify and rectify residual problems after primary healing.

Skeletal abnormalities in neurofibromatosis type 1: approaches to therapeutic options

The skeleton is frequently affected in individuals with neurofibromatosis type 1, and some of these bone manifestations can result in significant morbidity. The natural history and pathogenesis of the skeletal abnormalities of this disorder are poorly understood and consequently therapeutic options for these manifestations are currently limited. The Children's Tumor Foundation convened an International Neurofibromatosis Type 1 Bone Abnormalities Consortium to address future directions for clinical trials in skeletal abnormalities associated with this disorder. This report reviews the clinical skeletal manifestations and available preclinical mouse models and summarizes key issues that present barriers to optimal clinical management of skeletal abnormalities in neurofibromatosis type 1. These concepts should help advance optimal clinical management of the skeletal abnormalities in this disease and address major difficulties encountered for the design of clinical trials.

Analysis of radiographic characteristics of anterolateral bowing of the leg before fracture in neurofibromatosis type 1

BACKGROUND

Anterolateral leg bowing is associated with neurofibromatosis type 1 (NF1) frequently leading to fracture and nonunion of the tibia. The objective of the study was to characterize the radiographic findings of tibial dysplasia in NF1.

METHODS

This study is a retrospective review of radiographs of tibial dysplasia obtained within 52 years, between 1950 and 2002, from the Shriners Hospitals for Children, Salt Lake City, and of peripheral quantitative computed tomographic images of 3 individuals with anterolateral bowing of the leg without fracture compared with age- and sex-matched controls.

RESULTS

Individuals with NF1 with bowing of the leg have the appearance of thicker cortices with medullary narrowing on plain film radiographs. The peripheral quantitative computed tomographic images of individuals with NF1 with anterolateral bowing show an unusual configuration of the tibia.

CONCLUSIONS

Anterolateral bowing of the leg in NF1 is associated with the appearance of thicker cortices with medullary narrowing rather than thinning of the long bone cortex on plain film radiographs as currently used as a qualifier in the sixth diagnostic criterion for the clinical diagnosis of NF1. Individuals with NF1 who have anterolateral bowing of the leg have differences in tibial geometry compared with age- and sex-matched controls.

CLINICAL RELEVANCE

The characterization of the radiographic findings of long bone bowing in NF1 helps clarify the NF1 clinical diagnostic criteria.

Congenital pseudarthrosis of neurofibromatosis type 1: impaired osteoblast differentiation and function and altered NF1 gene expression

Three patients with neurofibromatosis 1 (NF1) were operated for congenital pseudarthrosis (PA) of the tibia. Three non-NF1 patients served as reference. Both NF1 mRNA and protein were detected in the PAs and in rows of osteoblasts and numerous osteoclasts next to the NF1-related PA arguing against inactivation of both NF1 alleles in the resident cells. Analyses on mesenchymal stem cells (MSCs) cultured from the red bone marrow of 1) next to PA of the affected NF1 tibiae, 2) the non-affected NF1 iliac crest of the same patients, and from 3) non-NF1 bone marrow demonstrated that the potential to form bone in vitro was the lowest in cells from the affected NF1-tibiae. The latter cells also displayed reduced levels of NF1 mRNA and protein, and upregulated phosphorylated p44/42 MAPK levels, consistent with an upregulated Ras-pathway. An exhaustive NF1 gene analysis detected constitutional mutation in each case, but no second hits or loss of heterozygosity were found. However, one patient displayed a mutation resulting in two potential active splice sites ultimately affecting exon 6. Interestingly, only one of the respective transcripts was detected in cells from the iliac crest, but two novel transcripts were detected in MSCs cultured from site next to PA. This finding may identify a novel mechanism how a single NF1 gene mutation may exert distinct effects on separate anatomical locations. The molecular pathogenesis of NF1-related PA apparently may not be entirely explained by second mutations or loss of heterozygosity of the NF1 gene.

Association of Ilizarov's technique and intramedullary rodding in the treatment of congenital pseudarthrosis of the tibia

PURPOSE

Many surgical techniques have been published on how to treat congenital pseudoarthrosis of the tibia (CPT). We combined Ilizarov's fixator with intramedullary nailing of the tibia and developed a procedure which combines the advantages of both methods: Ilizarov's high fusion rate with alignment control and the protection against refracture provided by the intramedullary nail. The results of this approach are presented and discussed.

MATERIAL AND METHODS

Seven boys and three girls aged 3-14 years (mean age 8 years 2 months) were treated using our combined technique. In six cases, the CPT was associated with neurofibromatosis. Two strategies were adopted: in six cases, a compression was applied on the bone defect, and in four cases, segmental bone transportation was performed before the compression procedure. The final follow-up (1.2-6.6 years) included a clinical and radiological examination.

RESULTS

Tibial union was achieved in nine cases without bone grafting. In one case, tibial union still remains uncertain, despite intertibiofibular bone grafting and additional compression procedures. Thirteen overall complications were noted, including three valgus deformity of the ankle. Bone transportation failed to achieve complete limb lengthening in three cases. One deep infection occurred 4 years after removal of the external fixator. The treatment for this included nail removal and antibiotic therapy for 3 months. Despite a permanent protection of orthosis, a refracture occurred 2 years after nail removal, reverting to the initial level of pseudarthrosis. Another surgical attempt using the same method was then performed with a satisfactory result.

CONCLUSIONS

The association of Ilizarov's technique and intramedullary nailing achieved and maintained tibial union in nine of ten patients at final follow-up. It also allowed correction of axial deformities and prevented refracture. Despite the short duration of the follow-up and a high rate of complications in our series, this method can be useful in many cases of CPT in which healing has failed to occur despite many previous surgeries.

The use of anterolateral bowing of the lower leg in the diagnostic criteria for neurofibromatosis type 1

Neurofibromatosis type 1 is diagnosed clinically based on the presence of two of seven criteria developed by a panel of experts in 1987. The sixth criterion focuses on skeletal findings and is as follows: "A distinctive osseous lesion such as sphenoid dysplasia or thinning of long bone cortex, with or without pseudarthrosis." The wording for this criterion is misleading. In particular, "thinning of long bone cortex" is not the characteristic radiographic presentation, and no mention of long bone bowing is included. The distinctive clinical feature of long bone dysplasia in neurofibromatosis type 1 is anterolateral bowing of the lower leg (portion of the body delimited by the knee and ankle). The usual radiographic findings of long bone dysplasia in neurofibromatosis type 1 at first presentation, prior to fracture, are anterolateral bowing with medullary canal narrowing and cortical thickening at the apex of the bowing. We suggest that anterolateral bowing of the lower leg, with or without fracture or pseudarthrosis, is a more appropriate description of the primary finding that a clinician will use to fulfill the sixth diagnostic criterion for neurofibromatosis type 1. Clarification of this diagnostic criterion is important for the clinician and for research protocols. Appropriate interpretation will improve understanding of the natural history and pathophysiology of neurofibromatosis type 1.

Treatment of congenital pseudarthrosis of the tibia: a multicenter study in Japan

Treatment of congenital pseudarthrosis of the tibia (CPT) remains a challenge. To clarify the current situation in treatment, a multicenter study was carried out to obtain information on the results of CPT treatment. The objective of this study was to propose appropriate treatment guidelines for CPT. Records of 73 patients with CPT who underwent surgical treatment were collected from 32 hospitals. The modality of the treatment was 26 with Ilizarov technique, 25 with free vascularized fibular graft, 7 with a combination of the two techniques, 6 with intramedullary nailing with free bone grafting, 5 plating with free bone grafting, and 4 with other treatments. Fifty-four procedures resulted in union, 7 resulted in delayed union, 7 were left un-united, 1 underwent amputation, and the results were unknown in 4. According to the results of this study, the most acceptable methods of treatment of CPT are the Ilizarov method and the vascularized fibular graft.

Use of an intramedullary rod for treatment of congenital pseudarthrosis of the tibia. A long-term follow-up study

BACKGROUND

The treatment of congenital pseudarthrosis of the tibia remains difficult and controversial. The purpose of this study was to evaluate the long-term results of a technique consisting of excision of the pseudarthrosis, autologous bone-grafting, and insertion of a Williams intramedullary rod into the tibia.

METHODS

Twenty-one consecutive patients with congenital pseudarthrosis of the tibia were managed with this technique between 1978 and 1999, and the results were retrospectively reviewed. The mean age of the patients at the time of the latest follow-up was 17.2 years (range, seven to twenty-five years), and the mean duration of postoperative follow-up was 14.2 years (range, three to twenty years).

RESULTS

Initial consolidation occurred in eighteen of the twenty-one patients. Refracture occurred in twelve patients; five fractures healed with closed treatment, five healed after an additional surgical procedure, and two ultimately required amputation. Ten patients had an ankle valgus deformity after tibial union. Eleven patients had a residual limb-length discrepancy of >2 cm; six required a contralateral distal femoral and/or proximal tibial epiphyseodesis, two had a tibial lengthening, and one used a shoe-lift. Five patients had an amputation: two, because of a recalcitrant fracture; two, because of a limb-length discrepancy (6 and 9 cm); and one, because of a chronic lower-extremity deformity.

CONCLUSIONS

This technique produced a satisfactory long-term functional outcome in sixteen of twenty-one patients and should be considered for the management of congenital pseudarthrosis of the tibia.

Residual challenges after healing of congenital pseudarthrosis in the tibia

The purpose of the current study was to evaluate the clinical results of the Ilizarov bone transport method in the treatment of congenital pseudarthrosis in the tibia. In seven patients operated on between 2.6 and 7.8 years of age, primary healing of the pseudarthrosis was achieved in all patients (after additional bone grafting in two patients). Within a followup of 6 to 8 years, major complications occurred in all patients. Five refractures occurred, and in one patient the refracture did not heal. At the last followup, axial deformities and an abnormal malalignment test with lateral mechanical axis deviation of 10 mm or greater was found in all patients. Three patients had leg length inequality of 20 mm or more. The Ilizarov bone transport method is useful in achieving primary healing in congenital pseudarthrosis of the tibia, but residual challenges with secondary reconstructive surgery caused by refracture and postoperative deformities must be expected.

Congenital pseudarthrosis of the tibia in pediatric patients: MR imaging

OBJECTIVE

The purpose of this study was to describe the characteristics of congenital pseudarthrosis of the tibia on MR images of infants and children and to assess the value of MR imaging in evaluating this disease.

CONCLUSION

MR imaging of congenital pseudarthrosis allows assessment of the type and extension of the disease. It is especially recommended for the evaluation of periosteal and soft-tissue changes near the pseudarthrosis.

Descriptive analysis of tibial pseudarthrosis in patients with neurofibromatosis 1

Five percent of individuals with neurofibromatosis type 1 (NF1) present with congenital long bone pseudarthrosis (PA). In large series, 50-80% of patients with congenital long bone PA also have NF1. Very little information exists on the natural history and pathogenesis of PA in NF1. This report is a descriptive analysis of a large series of patients with NF1 and tibial bowing or PA. Study A is a case-control study using the National Neurofibromatosis Foundation International Database (NNFFID). Eighty-five patients with PA were compared to a control group from the same database. There was a statistically significant male predominance of NF1 cases with PA (54 males to 31 females), compared to controls (85 males to 87 females) (chi2 = 4.0, P = 0.046, using a two-tailed test with Yates' correction). There was no significant difference in the clinical presentation of NF1 manifestations in NF1 patients with PA than in NF1 patients without PA. Of the affected individuals with PA, there were 24 de novo cases and 21 familial cases (9 through maternal and 12 through paternal inheritance). Questions that could not be answered by Study A were addressed by a partially overlapping case-series report, Study B, in which data on 75 cases ascertained through questionnaires completed by NF center directors were collected. From Study B we determined that half of the patients who had a fracture sustained it before age 2, and approximately 16% of the pseudarthrosis patients had an amputation. Our data indicate a male predominance and no parent-of-origin effect. Male gender may be a susceptibility factor for pseudarthrosis in NF1.

Congenital pseudarthrosis of the tibia. Treatment and outcome at skeletal maturity in 10 children

We present the clinical characteristics of 14 children with congenital pseudarthrosis of the tibia (CPT) treated in northern Finland at Oulu University Hospital during the years 1968-1996. The incidence of CPT in northern Finland was 3.5/10(5) during years 1962-1996, which is higher than in previous reports. The estimated prevalence of pseudarthrosis was 1.8/10(5). The first 10 children with a mean follow-up time of 19 years from the first grafting procedure and 14 years from the last grafts, all had a solid bony union and could walk without external support at the last follow-up. The best treatment, especially in unfavorable types, seems to be a radical resection of the pseudarthrosis and reconstruction with a free vascularized fibular graft.

The differential diagnosis of congenital pseudarthrosis of the tibia

The key to the solution of this problem lies in the differential diagnosis. There are at least four dysplastic lesions of the congentially bowed tibia (with or without cysts) which have quite different behaviour patterns. There are also six different types of true congenital pseudarthrosis which exhibit similar differences in behaviour and response to treatment.

Congenital pseudarthrosis of the tibia and neurofibromatosis

On the basis of 21 cases of congenital pseudarthrosis of the tibia, which were radiologically typed and later personally examined, it was found that all cases of the dysplastic type also showed evidence of neurofibromatosis. No evidence of neurofibromatosis was found among the cystic and the clubfoot type of pseudarthroses.