This update summarizes select research highlights pertaining to limb lengthening and deformity correction that were either published in a peer-reviewed journal between January 2009 and June 2010 or presented at the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS), the Limb Lengthening and Reconstruction Society (LLRS), the Pediatric Orthopaedic Society of North America (POSNA), the Orthopaedic Trauma Association (OTA), or the American Orthopaedic Foot & Ankle Society (AOFAS).
Assessment of Lower Limb Alignment in Children
The assessment of standard radiographic measurements such as the mechanical axis deviation with use of full-length standing radiographs has been found to be reliable in children1. However, the hip-knee-ankle angle does not reach the adult reference values until the age of seven years2.
Guided Growth
Guided growth techniques continue to evolve. One study compared traditional physeal stapling with the more recently introduced non-locking plate hemiepiphysiodesis and demonstrated minimal difference between the two types of implants3. The rate of angular correction was approximately 10° per year in both groups, with comparable complication rates. In another study, anterior distal femoral hemiepiphysiodesis was evaluated for the management of children who had arthrogryposis and flexion contracture of the knee4. A mean improvement of 18° was noted in this challenging group of patients, with better results in those with flexion deformities of <45°. The use of guided growth techniques to alter growth around the hip was demonstrated in an animal study5 and was the focus of a symposium at the recent POSNA meeting5. Although guided growth techniques with plate fixation are effective and are used for a variety of disorders, a higher rate of mechanical failure was reported for children with Blount disease6. New design modifications in these implants may decrease the prevalence of mechanical failure in such patients7.
The results of hemiepiphysiodesis in patients with physeal abnormalities and multiplanar deformities have been unpredictable. Cho et al.8 reviewed nine patients who were managed with hemiepiphyseal stapling for the treatment of angular deformity at the knee due to multiple epiphyseal dysplasia and reported a satisfactory outcome in two-thirds of the patients. Physeal behavior following staple removal may be unpredictable in patients with abnormal growth plates.
Blount Disease
In the study by Aird et al., computed tomography (CT) scan measurements demonstrated that children with Blount disease had increased femoral anteversion in addition to internal tibial torsion9. Using mathematical calculations to study the effect of varus or valgus osteotomies on femoral version, Liu et al. noted that proximal femoral varus osteotomies tended to decrease anteversion whereas valgus osteotomies tended to increase anteversion10. A number of authors have evaluated the results of surgery for the treatment of Blount disease. Multivariate analysis demonstrated that lateral hemiepiphyseodesis around the knee for the treatment of adolescent Blount disease was less effective for patients with an age of more than fourteen years, a body mass index (BMI) of =45 kg/m2, or a severe proximal tibial deformity11. Rab revisited the use of oblique osteotomy for the treatment of Blount disease and found this technique to be safe and accurate12. He described several refinements to the original technique, such as performing a prophylactic partial fasciotomy; orienting the starting plane of the oblique osteotomy to correspond with the distal, internally rotated tibial surface; and using two screws perpendicular to the long axis of the tibia. The use of a monolateral fixator that allows for multiplanar adjustment for the treatment of Blount disease was associated with satisfactory correction, with a complication rate that was comparable with that associated with traditional ring fixators13,14. Functional outcomes after the treatment of Blount disease are affected by the accuracy of correction15 and BMI15,16 and appear to worsen with time16.
Congenital Extremity Deficiencies
Congenital deficiencies are often difficult to treat, and even the most experienced surgeons have reported complications, especially when lengthening a congenitally short femur. One single-surgeon case series demonstrated regenerate deformation or fracture after lengthening in >50% of cases, regardless of the location of the corticotomy17. The risk of this complication can be substantially decreased with the use of intramedullary fixation during the lengthening procedure18. Hazra et al. reported hip and knee dislocation in association with a lengthening procedure in a patient with a congenitally short femur19, emphasizing one of the worst hazards of treating this condition. The authors recommended avoiding lengthening of >6 cm or >20% of the original length of the femur and recommended using staged lengthenings for larger discrepancies. Besides protecting an unstable knee joint from dislocating during lengthening, using the external fixator to span the knee may also stimulate growth of the lengthened extremity20. In another study, CT angiography was used to delineate the abnormal vascular pattern associated with proximal femoral focal deficiency21.
The debate regarding the treatment of fibular deficiency has been rekindled, with confirmation that surgical treatment can be highly successful22. The clinical results of limb lengthening have been reported to be similar to those of reconstructive amputation23. Lengthening for tibial deficiencies has not been as successful. Following tibial lengthening in nine patients with congenital tibial deficiencies, knee flexion was substantially limited in those with Jones type-I deficiencies24.
Two studies evaluated the quality-of-life scores following limb lengthening in children25,26. Moraal et al. reported that, while there may be a small decrease in quality-of-life scores shortly after surgery, the long-term quality-of-life scores were similar to those for controls, especially when the remaining limb-length discrepancy was <2 cm26.
Joint Distraction
Gradual correction with use of external fixation for the treatment of popliteal pterygium was recently revisited27. Although satisfactory correction could be attained, recurrent flexion deformities and tibial subluxation were commonly noted; these findings were similar to those of previous reports. Another study investigated the use of hip joint distraction (arthrodiatasis) for the treatment of Legg-Calvé-Perthes disease and demonstrated that >90% of the subjects had a satisfactory clinical and radiographic outcome28. However, the patients in that study were young at the time of the procedure (mean age, 6.8 years; range, five to eight years) and had a favorable natural history even without surgery.
Fibrous Dysplasia and Ollier Disease
Numerous surgical techniques have been described for the treatment of proximal femoral deformities in patients with fibrous dysplasia. Yang et al.29 described a four-step surgical procedure for the correction of proximal femoral varus deformity in a study of thirteen children (fourteen femora) with fibrous dysplasia. The steps included (1) valgus osteotomy, (2) curettage of the lesion, (3) massive impaction allografting, and (4) the insertion of an intramedullary nail with fixation across the femoral neck. After an average duration of follow-up of seventy-five months, there were no cases of infection, recurrent fracture, or progression of the deformity.
Several authors have reported on the beneficial effects of lengthening over elastic intramedullary nails. In a large case series of patients with Ollier disease, Popkov et al.30 assessed the effect of adding elastic stable intramedullary nailing to a circular fixator in the cases of forty-four patients who underwent limb lengthening. A substantially reduced duration of external fixation, limited postoperative complications, and prevention of fractures following fixator removal was noted with use of elastic stable intramedullary nailing.
Charcot Arthropathy
Charcot arthropathy of the foot and ankle, a frequent consequence of diabetic peripheral neuropathy, usually results in midfoot collapse, plantar flexion of the talus, and ulceration of the skin in association with osteomyelitis of the exposed bones. Small-wire external fixation has become valuable for the treatment of such limb-threatening problems71,72. Although patient tolerance of the bulky fixator is always a consideration, a sufficient number of patients benefit from limb salvage with use of external skeletal fixation, resection of infected bone, and midfoot osteotomy. Such treatment may become the first line of treatment for midfoot Charcot arthropathy, with amputation being reserved as the secondary approach in many cases.
Arthrodiatasis
Concern about the long-term effects of ankle arthrodesis, combined with issues related to the longevity of total ankle replacement, has led clinicians to consider controlled joint distraction (arthrodiatasis) for ankle osteoarthritis. The concept is simple: permitting continuous joint motion without compressing the articular surfaces as a result of weight-bearing forces. To accomplish this, one needs an adaptable external fixator with hinges collinear with the rotation axis of the ankle joint. Tellisi et al.73 reported on twenty-five patients with ankle osteoarthritis who were managed with a protocol that included joint distraction and mobilization while in an external fixator. The results were generally favorable, with 91% of the patients reporting improvement. How much of this improvement may be due to the placebo effect of a surgical procedure in a patient wanting to avoid an ankle arthrodesis remains unresolved.
Lengthening for Brachymetatarsia
A congenitally short metatarsal, usually the first or fourth, can be corrected by lengthening the bone with use of one of several strategies. W.C. Lee et al.74 reported the results of a retrospective study of patients who were managed with fourth metatarsal lengthening with use of one of three different techniques: (1) intercalary graft, (2) distraction osteogenesis after osteotomy with an electric saw, or (3) distraction osteogenesis after percutaneous osteotomy with an osteotome. The highest rate of patient satisfaction was noted in the last group in association with the use of the percutaneous approach. In another series, K.B. Lee et al.75 reported on sixteen patients (twenty-seven feet) who underwent first metatarsal lengthening with use of a unilateral external fixator. The most commonly reported problem was stiffness of the first metatarsophalangeal joint. Despite other complications such as cavus deformities, hallux valgus, and fracture of the regenerate, a satisfactory clinical outcome was achieved in the majority of patients.
Skeletal Dysplasias
Individuals with skeletal dysplasia, including those with achondroplasia and hypochondroplasia, are typically short in stature and also may have angular deformities of the lower limb. Deformity correction with and without limb lengthening is practiced at some centers but has not been universally accepted. The few clinical series on lengthening for body height increase often have combined patients with skeletal dysplasias and constitutional short stature. Lie and Chow83 reported on eight patients with short stature (five of whom had skeletal dysplasia and three of whom had constitutional short stature) who underwent lengthening with use of external fixation. The average time in the fixator was eight months, with a mean gain of 5.2 cm (21%) per lengthened segment. Besides pin-track infections and transient joint stiffness, the authors reported 0.6 complication per segment. In another report on twenty patients with achondroplasia, femoral lengthening of >50% of the initial femoral length was associated with poor bone formation and stiffness in adjacent joints84.
Cosmetic Lengthening
Judging from the list of practitioners offering surgery to increase height on the Internet, the introduction of self-lengthening intramedullary nails appears to have overcome surgeon and patient-related apprehension regarding pin-site-related complications associated with lengthening with use of external fixation. However, the literature on the subject is scarce and can be misleading because clinicians typically incorporate limb-lengthening procedures that are performed to increase height with those that are performed for other reasons in a single publication. Thus, readers need to tease out bilateral cases from the data and assume that at least some of the reported procedures were performed for stature indications alone. There are several potential complications associated with internal lengthening devices, including temporary or permanent joint contractures, joint instability, weakness, numbness or dysesthesias, and mechanical problems with the device itself, such as breakage, the inability to lengthen, and "run-away" (too rapid) lengthening failures. Besides the typical early complications that may be associated with limb lengthening, the long-term effects on articular cartilage in the joints of the lengthened limb remain largely unknown. With femoral lengthening with use of an intramedullary device, the bone is lengthened along its anatomic axis, rather than along the biomechanical axis, which is perpendicular to the floor. The knee is pushed toward the midline, increasing valgus stresses during weight-bearing. Concern about lateral compartment osteoarthritis developing in patients undergoing intramedullary cosmetic femoral lengthening has become a contentious issue at meetings at which the subject of stature surgery is discussed.
Lengthening with Use of Intramedullary Nails and Plates
The availability of computer software has allowed surgeons to perform six-axis deformity correction with precison94. One of the challenges associated with standard lengthening with use of external fixators is the prolonged external fixation time until the newly formed bone consolidates enough to allow for fixator removal without the risk of refracture of the regenerated bone. In response to this problem, the techniques of lengthening with use of intramedullary nails and plates are emerging. However, the potential for deep infection as well as additional cost are concerns with such methods. H. Kim et al.95, in a retrospective review of eighteen tibiae (thirteen patients), investigated the results of lengthening with use of a reamed intramedullary nail (minimum diameter, 10 mm) and a circular external fixator. No cases of infection, poor bone formation, or breakage of nails or screws were noted. Li et al.96 used an intramedullary nail and a monolateral external fixator for bone transport for the reconstruction of massive post-osteomyelitis skeletal defects of the femur in seventeen patients. Bone union at the docking site was achieved without bone graft, and one patient experienced recurrence of deep infection. Bilen et al.97, in a study of thirteen tibiae in nine patients, reviewed the results of acute fixator-assisted correction of deformity and subsequent lengthening over an intramedullary nail with use of a circular fixator. The mean external fixation index was 16 days/cm. Complications included two cases of poor bone formation that required bone-grafting and one case of compartment syndrome.
Oh et al.98 reviewed the records of ten patients who underwent lower limb lengthening with use of an external fixator with a submuscular locking plate. The external fixation index was 15 days/cm, and no major complications were reported. The authors described advantages of this technique compared with lengthening over nails.
Despite the attractive option of internal lengthening devices with avoidance of overlying external fixation, numerous complications continue to be reported. Simpson et al.99, in a review of thirty-three femora that were lengthened with use of the intramedullary skeletal kinetic distractor, reported difficulty in achieving length in eight cases and uncontrolled lengthening in seven cases. Kenawey et al.100 reported their experience with thirty-seven consecutive femoral lengthening procedures that were performed with use of intramedullary lengthening nails. The device-related complications included failure of distraction (one case), uncontrolled lengthening (seven cases), and poor new-bone formation (eight cases). The authors concluded that problems related to that particular intramedullary device were largely due to internal malfunction of the lengthening mechanism and recommended careful patient selection and the avoidance of a distraction rate of >1.5 mm/day.
Digital Imaging and Intraoperative Navigation Tools
Despite the recent popularity of digital imaging and navigation systems for the preoperative and intraoperative assessment of lower limb alignment, their advantages over conventional imaging systems remain unresolved. Jamali101 reported on the use of a universally available digital imaging software package for deformity analysis and surgical planning. Bae et al.64 and S.J. Kim et al.102 compared navigation systems with conventional radiography for preoperative planning and the intraoperative assessment of limb alignment in patients undergoing proximal tibial osteotomies and concluded that a navigation-guided procedure was associated with better clinical and radiographic outcomes. On the other hand, on the basis of a review of the current literature, Pearle et al.103 concluded that while image-free navigation systems may be clinically useful for intraoperative monitoring of the coronal plane alignment, currently available devices were of limited value for accurately assessing axial and sagittal plane alignment of the lower extremity.