The field of pediatric limb deformity correction and limb lengthening has experienced a paradigm shift in recent years. Although external fixation devices still play a critical role in complex deformity correction as well as bone lengthening in young children, bone lengthening in older children and simultaneous deformity correction, and lengthening are now reliably performed with motorized intramedullary lengthening devices. Guided growth and growth modulation techniques are increasingly being studied and indications are being refined. Congenital pediatric bone deficiencies are rare and therefore exceedingly difficult to study in a randomized or even controlled fashion. Therefore, we continue to rely almost exclusively on small series reporting on 1 particular treatment, often by a single group or surgeon, to slowly move our understanding of the management of these conditions forward.
The “What’s New in …” series of articles in the Journal of Pediatric Orthopaedics has been endorsed by the POSNA Presidential Line. Authors have been vetted by the POSNA Publications Committee to provide experts in each subspecialty area and to minimize any potential personal conflicts of interest. All review articles of this type undergo the full JPO review process to ensure the highest quality information.
The PubMed database was used to search for all papers published over the past 5 years (2013-2018) related to the treatment of pediatric bone deformity and limb length discrepancy (LLD) including underlying pathologies that were developmental, congenital, and bone disease-related. We selected the most relevant and higher-level evidence articles to review on each topic when available.
Treatment of LLD by Growth Modulation
Growing children with expected LLDs of between 2 and 5 cm may be good candidates for epiphysiodesis of the longer leg. Challenges exist with regard to timing, use of permanent versus temporary epiphysiodesis, implant choice, and both frequency and duration of follow-up. In 2013, Lykissas et al1 compared 3 commonly used techniques for epiphysiodesis and found no difference between tension band plating (TBP), stapling, and percutaneous transphyseal screws (PETS). In 2016, Gaumetou et al2 followed 32 patients treated with TBP for LLD and found that only 68% of femurs and 42% of tibias achieved expected growth retardation at final follow-up, whereas Sinha et al3 showed that TBP, especially for LLD, caused morphologic changes in tibial plateau slope and roof angle. Bayhan et al4 demonstrated that percutaneous permanent epiphysiodesis had better correction and fewer complications than TBP. Lee et al,5 in a smaller study of 19 patients, reported more favorable outcomes with staples compared with TBP, including faster growth arrest and more effective correction of LLD. In short, most of these studies call into question the effectiveness of utilizing TBP as an alternative to other methods of epiphysiodesis.
Treatment of LLD by Limb Lengthening With and Without Deformity Correction
Horn et al6 reviewed the results of 50 consecutive limb lengthenings with deformity correction in 47 patients using motorized intramedullary nails. The underlying diagnoses included congenital limb deficiencies, posttraumatic and idiopathic discrepancies, and associated limb deformities varied and included deformity in coronal, sagittal, and axial planes. The authors found that the planned amount of lengthening was achieved in all but 2 patients. The authors also noted successful deformity correction with this technique although minor residual axial, sagittal, and/or coronal plane deformity was often seen at final follow-up but it was not thought to be clinically significant.
Iobst et al7 detailed their results and surgical technique of simultaneous acute femoral deformity correction and lengthening using the PRECICE nail (Nuvasive, San Diego, CA). They performed the procedure in 27 patients: 93% achieved their lengthening goals (within 3 mm) and 81% achieved satisfactory coronal plane correction. The authors noted that the patients undergoing this procedure maintained knee motion and had excellent healing of their regenerate bone. The authors concluded the PRECICE nail provides excellent results with simultaneous deformity correction and lengthening, although they did emphasize several technical factors (such as the use of 6 mm temporary external fixation pins and the use of multiple blocking screws) to increase success.
Steiger et al8 described their technique and outcomes in 5 patients in whom they corrected bone deformity acutely with a locking plate and simultaneously implanted a motorized lengthening nail to gradually correct leg length difference. This may provide an alternative for the treatment of severe or complex deformity where a nail alone may not be appropriate.
Panagiotopoulou et al9 performed a retrieval analysis on 15 PRECICE nails removed from 13 patients. Visual, radiographic, and microscopic analysis revealed internal corrosive debris and actuator pin failure in first generation designs but none in subsequent designs. The newer designs, however, did show evidence of biological deposits and titanium wear particles on the internal stainless-steel bearings. These findings support current recommendations that reusing nails for repeat lengthening may increase the risk of internal corrosion and possible implant failure.
Looking at results of external fixator lengthenings, Xu10 performed a systematic review of studies comparing traditional Ilizarov lengthening with lengthening with an external fixator over an intramedullary nail. They found that patients lengthened over a nail had improved consolidation indices and decreased time in the external fixator comparedwith patients with traditional lengthening without a nail, although the study was limited by the paucity and heterogeneity of studies included in the systematic review.
Two studies examined medical comorbidities in children with Blount disease. Taussig et al11 reported that children with infantile and adolescent Blount disease as well as slipped capital femoral epiphysis had higher levels of hypertension than controls matched for age, sex, height, and obesity. The authors theorized that hypertension contributes to pathologic changes at the physis in these conditions. Almost none of the study patients had been previously diagnosed as hypertensive, creating an opportunity to identify, and treat this condition in this population. In another study, Lisenda et al12 assessed vitamin D status in patients with Blount disease in South Africa and found no association between vitamin D deficiency and infantile or adolescent Blount disease.
Complications and failures of guided growth in Blount disease is a topic of increasing interest. Burghardt et al13 performed a systematic review that included 12 studies and found increased risk of failure in patients with higher body mass index and greater severity of deformity. Unpredictable results with this technique in Blount disease were also identified as a risk, noting that osteotomy is the salvage procedure of choice. Implant failure, most commonly screw breakage, has led some to suggest that solid screws are preferable to cannulated screws.14 Another study of surgical failure focused on an instance of TBP fracture in guided growth for Blount disease, with finding of mechanical failure from cyclic stress rather than tension from growth, leading the authors to recommend consideration of stronger or multiple implants in obese patients.15
Outcomes of tibial osteotomy with and without fibular osteotomy in Blount disease were compared using a circular fixator.16 The authors found that in the setting of tibia vara, with minimal lengthening required, fibular osteotomy and fixation to the tibia is not necessary. Fibular osteotomy is considered if there is severe varus and excessive rotational deformity.
Congenital Limb Deficiencies
Two studies evaluated limb lengthening techniques for children and adolescents with congenital femoral deficiency comparing external fixation to internal motorized nails. Szymczuk et al17 found use of an external fixator resulted in decreased knee range of motion during distraction and after consolidation as well as increased total problems due to pin site infection compared with the motorized nail group. Likewise, Black et al18 found an overall decreased number of complications in their motorized nail group compared with their circular external fixator group.
Shabtai and colleagues published their early experience with internal lengthening nails for femur and tibial deficiency in 18 adults and children as young as 9 years old. They found the amount of lengthening to be accurate and that all patients achieved their lengthening goal despite 7 complications requiring return to the operating room.19
A number of authors recently published their congenital femoral deficiency lengthening results using external devices. These were retrospective series with all surgeries performed in the years before the availability of internal lengthening nails. Prince et al20 found lengthening with a monolateral fixator was effective in 30 patients with 2 year follow-up in terms of length achieved and maintenance of functional knee and hip flexion and extension. Some patient-report score domains were noted to be lower in the patients with lengthenings over 6 cm or >25% of initial femoral length. Abdelgawad et al21 found prophylactic intramedullary rodding with a rush rod after removal of external device for femoral lengthening significantly decreased the rate of fracture after lengthening compared with historical controls, whereas Georgiadis et al22 found percutaneous plate fixation can decrease the time spent in an external fixator.
A randomized, double-blind, multicenter controlled trial found that children undergoing limb lengthening with external fixators for both congenital and acquired limb deformities and deficiencies benefited from botulinum toxin A injection at the time of surgery.23 The injections were administered into the quadriceps and hamstrings for the femoral lengthening group and into the gastrocsoleus muscle group for the tibial lengthening patients. Pain was significantly decreased in the botulinum group as were pin tract infections in the tibial lengthening group. Three quality of life domains were also superior in the botulinum group.
Calder et al24 reported on functional outcomes in fibular deficiency patients with severe limb deformity treated with either an amputation or extension prosthesis. Patients who had undergone amputation had significantly greater activity scores and decreased pain compared with the extension prosthesis group but the authors concluded that extension prostheses offer reasonable, although inferior, long-term function.
For patients with Achterman type II fibular hemimelia, Popkov et al25 reported that recurrence of tibia and ankle deformities after bone lengthening could be prevented by resection of the fibular anlage.
In 2016, Paley26 published a new classification system for tibial hemimelia that is designed to guide treatment and prognosis, whereas Clinton and Birch27 reported his 37 year experience treating 125 extremities with congenital tibial deficiency.
Deformities Associated With Metabolic Bone Diseases and Skeletal Disorders
Three groups reported on surgical outcomes for pediatric patients with X-linked hypophosphatemic rickets (XLH). Horn et al28 shared the results of 23 limbs in XLH patients treated with guided growth at a mean age of 10.3 years old. Indications for surgery were mechanical axis deviation through zones II or III despite proper medical management. The majority (70%) of limbs were restored to neutral mechanical axis and only 1 limb has required osteotomy. Those with ≥3 years of growth remaining and those with valgus deformity rather than varus deformity achieved significantly better correction. Gizard and colleagues and Popkov and colleagues reported on 49 and 47 patients with XLH, respectively. Gizard et al29 found that need for repeat operation was decreased in those treated with surgery when older and those with good metabolic control. Popkov et al30 reported that a historical group treated with Ilizarov frames spent significantly more time (124.7 d) in fixators compared with those treated with Ilizarov frames combined with flexible intramedullary nails (87.4 d).
In patients with osteogenesis imperfecta treated by osteotomies and intramedullary rod placement, osteotomy healing rates for 2 different groups were reported by Anam et al.31 Healing rates were significantly better (72% vs. 42%) in the more recent cohort when bisphosphonate infusions were delayed for 4 months after surgery, osteotomes instead of power saws were utilized and zolendronic acid infusions were used instead of the traditional pamidronate infusions. Another study32 reported on the longevity of 179 Fassier-Duval rods (Pega Medical, Laval, QC, Canada) in 58 children. There was a 53% revision rate at a mean of 4 years 4 months, generally due to growth and subsequent fracture.
Treatment of Angular Deformities Via Growth Modulation Versus Osteotomy
Shin et al33 reported that there is no difference in the rate of deformity correction when comparing 3 different guided growth implants (peanut plate, eight-plate, and hinge plate) and implant-related complications were significantly associated with increased body weight and use of cannulated screws. Park et al34 compared 90 limbs with valgus deformity treated with PETS to 60 limbs treated with TBP and concluded that the mean rate of correction was more rapid with PETS and recommended PETS in those patients closer to skeletal maturity. In a prospective randomized study, Masquijo et al35 compared 2 techniques of TBP insertion and reported significantly less operative time, radiation exposure and incision size with a modified technique that involves placing guide wires before making an incision.
In an effort to reduce radiation exposure from repeat full-length limb radiographs, Sweeney et al36 derived 2 equations based on the change in screw divergence measured on knee radiographs to calculate the change in the tibial-femoral angle and anatomic lateral distal femoral angle in patients being treated with guided growth plates. Farr et al37 noted rebound phenomenon in 47 of 64 extremities that underwent growth modulation with TBP: children above 1 year from skeletal maturity at plate removal and children with increased body mass index were at increased risk. Leveille et al38 reported that growth modulation at a younger age and that those with large initial deformity had increased risk of rebound deformity.
Guided growth continues to be utilized for coronal plane deformities about the ankle, as well. In a retrospective study of 60 limbs with ankles valgus deformity, Driscoll et al39 reported that although rate of correction was faster with medial malleolar screw than with TPB, TPB had fewer hardware-related complications.
Finally, 2 studies highlighted the importance of close follow-up when using guided growth techniques.40,41 The authors reported that 12% to 39% of patients either had limited follow-up or were lost completely. Non-English speaking families were at increased risk of lack of follow-up. Given the high need for secondary surgery for overcorrection in patients without regular follow-up, increased effort, and attention to ensuring guided growth patients attend appointments is critical.
In patients with severe and/or multiplanar lower extremity deformity, osteotomy with gradual correction may be more reliable than guided growth. In a retrospective comparative study, Mayer et al42 reported that both Iliazarov and TSF were viable options for infantile and adolescent Blount disease with no clear advantage of 1 device with regard to deformity correction. Hughes et al43 reported good results via intraoperative use of TSF to correct complex tibial multiplanar deformities before definitive internal stabilization in 12 patients.
Congenital Pseudarthrosis of the Tibia (CPT)
CPT remains one of the most challenging pathologies managed by the pediatric orthopedic surgeon. In a 2013 Norwegian epidemiological study, the incidence of CPT was found to be 1:53,000 between 1987 and 2006, a rate 3 times higher than previously reported.44 Another study reported that 63% of these patients had definitive signs of neurofibromatosis.45
Vanderstappen et al46 reported on 12 CPT patients with an average follow-up of 24 years (range: 6 to 39 y). The majority (10/12) healed initially with Ilizarov bone transport but half refractured and at final follow-up 4 of 12 were nonunited with 1 undergoing amputation.
Questioning whether to delay surgery until a specific age, Liu and colleagues reported on 29 children under 3 years of age and 13 older than 3 at the time of index surgery. They found a >90% primary union rate in both groups and similarly high complications including refracture, malalignment and leg length discrepancy, and concluded that there is no indication to delay surgery in these patients.47 Using the induced membrane technique, Pannier et al reported good outcomes on 5 children with CPT aged 10 to 30 months with all patients achieving bone union.48
In 2018, Richards and Anderson49 found that the addition of bone morphogenetic protein to intramedullary fixation accelerated but did not guarantee primary union in CPT cases. Shah and colleagues, in a multicenter study, followed 119 patients with CPT to skeletal maturity and found that only 69% were united. The use of bone morphogenetic protein and combining intramedullary nailing with Ilizarov were risk factors for treatment failure while use of cortical graft and not osteotomizing the fibula was associated with union.50 The authors acknowledge that selection bias may have influenced these results.
Seo et al51 found satisfactory foot and ankle function after successful Ilizarov treatment. Westberry and colleagues reported a 90% tibial union rate after Boyd amputation with CPT stabilization and good functional outcomes with that or below knee amputation. They cautioned that secondary surgeries are still common and emphasized that patient-oriented outcome scores need to be studied.52
There is significant interest in studying and writing about pediatric limb deformity and LLD in recent years. Because many of these conditions, particularly congenital conditions, are quite rare, large treatment series do not exist for many of these diseases, emphasizing the need for multicenter collaboration. The advent of mechanized internal lengthening nails is revolutionizing the treatment of deformity and leg length discrepancy in older children and adolescents while the indications for use of guided growth for angular deformities are becoming better studied and more tailored.
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3. Sinha R, Weigl D, Mercado E, et al. Eight-plate epiphysiodesis: are we creating an intra-articular deformity? Bone Joint J. 2018;100-B:1112–1116.
4. Bayhan IA, Karatas AF, Rogers KJ, et al. Comparing percutaneous physeal epiphysiodesis and eight-plate epiphysiodesis for the treatment of limb length discrepancy
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5. Lee WC, Kao HK, Yang WE, et al. Tension band plating is less effective in achieving equalization of leg length. J Child Orthop. 2018;12:629–634.
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7. Iobst CA, Rozbruch SR, Nelson S, et al. Simultaneous acute femoral deformity correction and gradual limb lengthening using a retrograde femoral nail: technique and clinical results. J Am Acad Orthop Surg. 2018;26:241–250.
8. Steiger CN, Lenze U, Krieg AH. A new technique for correction of leg length discrepancies in combination with complex axis deformities of the lower limb using a lengthening nail and a locking plate. J Child Orthop. 2018;12:515–525.
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21. Abdelgawad AA, Jauregui JJ, Standard SC, et al. Prophylactic intramedullary rodding following femoral lengthening in congenital deficiency of the femur. J Pediatr Orthop. 2017;37:416–423.
22. Georgiadis AG, Rossow JK, Laine JC, et al. Plate-assisted lengthening of the femur and tibia in pediatric patients. J Pediatr Orthop. 2017;37:473–478.
23. Hamdy RC, Montpetit K, Aiona MD, et al. Safety and efficacy of botulinum toxin A in children undergoing lower limb lengthening and deformity correction: results of a double-blind, multicenter, randomized controlled trial. J Pediatr Orthop. 2016;36:48–55.
24. Calder P, Shaw S, Roberts A, et al. A comparison of functional outcome between amputation and extension prosthesis in the treatment of congenital absence of the fibula with severe limb deformity. J Child Orthop. 2017;11:318–325.
25. Popkov A, Aranovich A, Popkov D. Prevention of recurrence of tibia and ankle deformities after bone lengthening in children with type II fibular hemimelia. Int Orthop. 2015;39:1365–1370.
26. Paley D. Tibial hemimelia: new classification and reconstructive options. J Child Orthop. 2016;10:529–555.
27. Clinton R, Birch JG. Congenital tibial deficiency: a 37-year experience at 1 institution. J Pediatr Orthop. 2015;35:385–390.
28. Horn A, Wright J, Bockenhauer D, et al. The orthopaedic management of lower limb deformity in hypophosphataemic rickets. J Child Orthop. 2017;11:298–305.
29. Gizard A, Rothenbuhler A, Pejin Z, et al. Outcomes of orthopedic surgery in a cohort of 49 patients with X-linked hypophosphatemic rickets (XLHR). Endocr Connect. 2017;6:566–573.
30. Popkov A, Aranovich A, Popkov D. Results of deformity correction in children with X-linked hereditary hypophosphatemic rickets by external fixation or combined technique. Int Orthop. 2015;39:2423–2431.
31. Anam EA, Rauch F, Glorieux FH, et al. Osteotomy healing in children with osteogenesis imperfecta receiving bisphosphonate treatment. J Bone Miner Res. 2015;30:1362–1368.
32. Azzam KA, Rush ET, Burke BR, et al. Mid-term results of femoral and tibial osteotomies and fassier-duval nailing in children with osteogenesis imperfecta. J Pediatr Orthop. 2018;38:331–336.
33. Shin YW, Trehan SK, Uppstrom TJ, et al. Radiographic results and complications of 3 guided growth implants. J Pediatr Orthop. 2018;38:360–364.
34. Park H, Park M, Kim SM, et al. Hemiepiphysiodesis for idiopathic genu valgum: percutaneous transphyseal screw versus tension-band plate. J Pediatr Orthop. 2018;38:325–330.
35. Masquijo JJ, Lanfranchi L, Torres-Gomez A, et al. Guided growth with the tension band plate construct: a prospective comparison of 2 methods of implant placement. J Pediatr Orthop. 2015;35:e20–e25.
36. Sweeney KR, Shi WJ, Gottschalk MB, et al. Radiographic assessment of guided growth: the correlation between screw divergence and change in anatomic alignment. J Pediatr Orthop. 2017;37:e261–e264.
37. Farr S, Alrabai HM, Meizer E, et al. Rebound of frontal plane malalignment after tension band plating. J Pediatr Orthop. 2018;38:365–369.
38. Leveille LA, Razi O, Johnston CE. Rebound deformity after growth modulation in patients with coronal plane angular deformities about the knee: who gets it and how much? J Pediatr Orthop. 2019;39:353–358.
39. Driscoll MD, Linton J, Sullivan E, et al. Medial malleolar screw versus tension-band plate hemiepiphysiodesis for ankle valgus in the skeletally immature. J Pediatr Orthop. 2014;34:441–446.
40. Kemppainen JW, Hood KA, Roocroft JH, et al. Incomplete follow-up after growth modulation surgery: incidence and associated complications. J Pediatr Orthop. 2016;36:516–520.
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45. Van Royen K, Brems H, Legius E, et al. Prevalence of neurofibromatosis type 1 in congenital pseudarthrosis of the tibia
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46. Vanderstappen J, Lammens J, Berger P, et al. Ilizarov bone transport as a treatment of congenital pseudarthrosis of the tibia
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47. Liu Y, Mei H, Zhu G, et al. Congenital pseudarthrosis of the tibia
in children: should we defer surgery until 3 years old? J Pediatr Orthop B. 2018;27:17–25.
48. Pannier S, Pejin Z, Dana C, et al. Induced membrane technique for the treatment of congenital pseudarthrosis of the tibia
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49. Richards BS, Anderson TD. rhBMP-2 and intramedullary fixation in congenital pseudarthrosis of the tibia
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50. Shah H, Joseph B, Nair BVS, et al. What factors influence union and refracture of congenital pseudarthrosis of the tibia
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51. Seo SG, Lee DY, Kim YS, et al. Foot and ankle function at maturity after Ilizarov treatment for atrophic-type congenital pseudarthrosis of the tibia
: a comprehensive outcome comparison with normal controls. J Bone Joint Surg Am. 2016;98:490–498.
52. Westberry DE, Carpenter AM, Tisch J, et al. Amputation outcomes in congenital pseudarthrosis of the tibia
. J Pediatr Orthop. 2018;38:e475–e481.