What’s New in Limb Lengthening and Deformity Correction

This article represents a review of selected literature published from April 2024 through March 2025 with a focus on limb lengthening and/or deformity correction. Congenital Limb Differences Simultaneous hemiepiphysiodesis with antegrade femoral lengthening was recently reported to correct valgus at the time of lengthening in patients with congenital femoral deficiency1. Tschurl et al. reported on hip instability in patients with Paley type-1A congenital femoral deficiency2. They reported that 6 of their 33 patients had episodes of late hip instability at a mean of 637 days after external fixator removal, despite a mean lateral center-edge angle of 23°. Ankle instability in the setting of fibular hemimelia can be challenging to correct. Shadi et al.3 reported on their experience with ankle reconstruction of Paley type-3C fibular hemimelia. They reported that, in 58% of the limbs, correction was maintained over time, with good clinical and radiographic results, whereas 40% of patients had additional reconstructive procedures that ultimately led to a plantigrade foot suitable for ambulation as well as lengthening. Exner et al.4 described a bending osteotomy through the distal tibial physis, inspired by the Pemberton osteotomy. They followed 4 of their patients to skeletal maturity and determined that the bending osteotomy was successful at realigning the distal tibia to the hindfoot, with no cases of physeal arrest. Yadav5 reported on tibial deformity correction, lengthening, and then a later ankle arthrodesis to achieve a plantigrade foot. Physeal Bars Hooper et al.6 studied risk factors for the development of posttraumatic physeal bars. Of the 330 patients prospectively enrolled in their study, 100 developed physeal arrest within 6 months of the injury. In general, patients who had higher magnitudes of initial displacement and patients who had a distal femoral fracture were most likely to develop growth arrest. With regard to bar resection for treatment, Alhassan et al.7 reported that combining bar resection with hemiepiphysiodesis of the side opposite the arrest was associated with a higher likelihood of angular deformity correction than bar resection alone. Furthermore, they noted that the group who underwent hemiepiphysiodesis with bar resection had no cases of worsening angular deformity postoperatively. Guided Growth Shim et al. studied the results of hemipercutaneous epiphysiodesis using a transphyseal screw (hemi-PETS) after screw removal. They concluded that about one-quarter of the patients with involved femoral segments continued to have growth inhibition after removal and cautioned against placing the screws too close to the periphery8. This contrasts with the study of the epiphyseal-entry percutaneous epiphysiodesis using transphyseal screws (PETS), in which Neal and Kiebzak documented no iatrogenic physeal arrests in 89 patients who underwent 146 procedures9. Lastly, Abdelaziz et al.10 evaluated the reversibility of PETS by performing computed tomographic (CT) scans at 6 months after screw removal. Of the 36 limb segments evaluated, 24 had both CT scans and lower-limb radiographs after removal. There were no visible osseous bars on the CT scans. Twelve patients resumed growth, 4 limbs were stationary (did not grow), and 8 limbs were excluded because of a lack of calibration. Hösl et al.11 evaluated guided growth via tension band plating in the setting of achondroplasia. They calculated that the femoral growth rate was 43.3% lower and the tibial growth rate was 48.5% lower compared with the general population. In concordance with slower growth, the mean duration (and standard deviation) that the implant lasted for the achondroplasia group was significantly longer: 36.9 ± 8.9 months in valgus knees and 23.0 ± 14.3 months in varus knees. When normalizing for growth, correction rates for femora were no longer significant, and there was a trend toward slower correction for tibiae. The authors concluded that guided growth could be successful in achondroplasia, but should be done when the patient is at a younger age, with treatment more prolonged. Bram et al.12 studied tension band plating for genu valgum in patients with multiple hereditary exostosis compared with patients with idiopathic genu valgum. Compared with the idiopathic group, there was no difference in the correction rate. However, the authors noted that 11 extremities in the multiple hereditary exostosis group that had open physes at implant removal had a mean recurrence of 4° hip-knee-ankle angle at the 19-month follow-up. Liang et al.13 evaluated a robot-assisted screw insertion technique for tension band plating. Although there was no difference in the screw position in the coronal plane, the robot-assisted group demonstrated a more accurate screw position compared with freehand in the sagittal plane and a more accurate screw-plate angle. However, the authors noted no difference in either deformity correction or limb-length difference at the final follow-up. Kutschke and Kim14 evaluated the 3-dimensional effects of growth modulation of the proximal femoral physis in a pig model. They noted that screw position can strongly affect both the correction of varus and the femoral version over time. Basic Science Extensive research has been dedicated to characterizing and improving regenerate quality during distraction osteogenesis. In a pilot study, Bafor et al.15 described a new “inner zone” that was seen on histological sections of regenerate formed via internal limb lengthening of goat tibiae. Pu et al.16 were able to develop a time-lapse “4-dimensional” study to better characterize regenerate formation. They reported rapid bone formation for the first 10 days of the consolidation period, followed by a more characteristic callus reshaping. Using rabbits, Shchepkina et al.17 evaluated regenerate formation in distraction osteogenesis by comparing 3 models: use of an external fixator (control group), lengthening with an external fixator and then nailing, and lengthening over a nail. The authors discovered more profound periosteal bone formation and bone structure in both experimental groups, with the most robust regenerate in the cohort that had lengthening with an external fixator and then nailing. Critical-sized bone defects treated via the Masquelet technique continue to receive scientific attention. Ziroglu et al.18 utilized different types of bone cement models to determine if they could improve the healing characteristics of the induced membrane. They determined that polymethylmethacrylate (PMMA) cement impregnated with estrogen or bone chips, as well as a calcium phosphate cement spacer, had better inflammatory characteristics in their rat model. Kaneko et al.19 investigated the effect of different bone-defect fixation methods on macrophage expression. They concluded that induced membranes are formed differently in various models and that they form on the basis of the foreign body reaction to the PMMA. They noted that this inflammatory reaction is different from granulation tissue that can infiltrate bone defects or even from the capsules that occur because of other types of foreign body reactions. Lastly, Noonan et al.20 published a proof-of-concept study utilizing microwave antennas to ablate the physis, first in cadaveric models and then in live pig models. They demonstrated ablation of the physis in all models, no obvious evidence of articular cartilage damage, and no apparent pain from the procedure. Further studies are ongoing to better understand and refine the process. Medical Diseases Limb lengthening in the setting of Ollier disease was evaluated21. All 21 limb lengthenings, whether the osteotomy was performed intralesionally or extralesionally, were successful at achieving both length and consolidation. There were no differences in lengthening rate or healing index if the osteotomy was intralesional instead of extralesional. Vosoritide is a disease-specific medication indicated for children and adolescents with achondroplasia. In an international expert panel determining the role for limb surgery in patients taking vosoritide22, consensus with regard to the timing of surgery for patients taking the medication could not be reached because of insufficient data. The panel members all agreed that it is important to consider short-term and long-term patient-specific goals. Lastly, Dong et al. published intermediate-term results on a modified McFarland allograft bypass procedure for patients with congenital pseudarthrosis of the tibia23. At the last follow-up (median, 7 years), all 7 patients had allografts that completely consolidated in the tibiae at both ends. Patients used long-term bracing. No amputations were performed. Limb Lengthening Several large meta-analysis studies were conducted this year. Bulut et al.24 reviewed complications associated with cosmetic lengthening using either magnetic internal lengthening nails or external fixators. Although both cohorts had excellent patient satisfaction results, there were fewer problems (37%), obstacles (42%), and complications (0%) in the magnetic internal lengthening nail group compared with the external fixator group, in which the rates were 56% for problems, 48% for obstacles, and 10% for complications. Gigi et al.25 evaluated the consolidation of 61 antegrade femoral lengthenings according to whether the femoral canal was vented prior to reaming. In the venting group, there were significant improvements in both healing and consolidation indices compared with the nonventing group. In the venting group, the mean healing index (and the standard deviation) was 21 ± 6 days/cm and the mean consolidation index was 10 ± 6 days/cm. In contrast, the nonventing group had a mean healing index of 31 ± 22 days/cm and a mean consolidation index of 20 ± 22 days/cm. There were no instances of embolic events in either group. There were 2 instances of delayed regenerate healing, both in the nonventing group. Al Ramlawi et al. performed 2 separate studies reviewing their femoral antegrade lengthening cohort: one examined iatrogenic proximal femoral varus26 and the other examined nail bending following lengthening27. The authors found that iatrogenic proximal femoral varus was more related to the osteotomy site than to the use of a piriformis nail compared with a trochanteric nail26. Nail bending27 was highly associated with a higher coefficient of weight in kilograms per nail diameter in millimeters. The authors also determined that there was a higher rate of nail bending when bilateral antegrade femoral lengthenings were performed. Bains et al.28 evaluated the risk of surgical site infection in the setting of internal limb lengthening. The risk of developing a deep infection was nearly 3%. All of the deep infections were osteomyelitis, and 8 of 14 limbs that had a deep infection had a history of limb lengthening via an external fixator. Arthroplasty The arthroplasty literature has advanced the application of limb deformity principles, as noted in several recent publications. Polascik et al. reported on the impact of coronal deformity on the operative course and early outcomes after total knee arthroplasty (TKA). They found that patients with a coronal deformity of >10° had longer operations and were more likely to be discharged to a skilled nursing facility29. Xing et al. studied the impact of robot-assisted TKA in mildly and severely deformed arthritic knees. When compared with patients treated with conventional TKA, the authors noted significantly enhanced accuracy with respect to deformity correction as measured with the hip-knee-ankle angle and the posterior tibial slope, despite the robot-assisted TKA group having a greater proportion of patients with severe deformities30. Total hip arthroplasty (THA) for advanced hip dysplasia using a staged approach was recently reported, with generally positive results. In this osteotomy-sparing method, hips were first distracted by 6 to 12 cm using either external fixation or an internal lengthening device, and a THA was then performed. In their series of 14 patients, 1 sustained temporary peroneal nerve palsy, 2 required revision of the internal lengthening device, and 1 required acetabular revision at 7 years postoperatively31. Trauma Ring fixators for the treatment of traumatic injuries have proven to be a valuable strategy. Investigators at the Sheffield Teaching Hospitals reported on long-term outcomes in treating 225 patients with Gustilo-Anderson type III-B open tibial fractures using Ilizarov methods coupled with an orthoplastics approach. Patients spent a mean of 6.4 months in circular frames. Only 3.5% of patients developed a deep infection, and 98.2% of patients went on to union32. Hui et al. found that ring fixators also had advantages in the treatment of pediatric tibial shaft fractures, with both faster mean fracture union (7.8 weeks) compared with pin-to-bar external fixation (9.3 weeks) and earlier mean time to weight-bearing (2.6 compared with 9.9 weeks). However, they did note the increased cost of treatment for patients who received the Ilizarov devices33. A team of researchers in Poland analyzed gait patterns after using the Ilizarov method for intra-articular calcaneal fractures and found no significant differences with respect to cadence, gait velocity, or stride length when compared with volunteer controls. There were shortened stance and single support phases in the treated limb compared with the intact limb. There were no significant differences between treated limbs and nondominant control limbs in any gait parameters, suggesting that the Ilizarov method not only has evidence supporting normalization of radiographic parameters, but also has good biomechanical outcomes34. Circular fixation constructs were also studied. Historically, ring blocks have been utilized, coupling several rings together to enhance stability. The reverse dynamization concept challenges this approach. Hodkinson et al. studied different constructs in 302 consecutive patients with a complex tibial fracture and found that 2 ring constructs required less time in the frame, with no significant difference in the rate of malunion or need for a secondary surgery35. Foot and Ankle Disorders The role of ankle alignment in limb deformity is being better elucidated. Yang et al. studied the impact of high tibial osteotomy on hindfoot alignment. They utilized standing full-length radiographs preoperatively and 2 years postoperatively and noted that the hindfoot alignment angle improved significantly from 5.1° of valgus preoperatively to 1.9° of valgus postoperatively for patients with preoperative hindfoot valgus. However, for patients with preoperative hindfoot varus, no meaningful improvement in coronal hindfoot alignment was noted. Patients with preoperative hindfoot varus were noted to have increased pain and worse functional scores36. Larios et al. reported on using hexapod external fixation in complex foot and ankle reconstruction, with consistent improvement in alignment and functional scores37. Siddiqui et al. compared outcomes of gradual and acute lengthening in the treatment of brachymetatarsia and found comparable outcomes, but increased time of treatment and need for revision surgery using a gradual technique38. Brinkemper et al. found that nonunions in the ankle following hindfoot nailing were only able to be successfully fused using salvage Illizarov fixators 37% of the time. The authors believed that this is a last resort before amputation39. Bone Defects Management of bone defects remains a substantial orthopaedic challenge. Langlais et al. reported on long-term results using the induced membrane technique in 8 children treated with wide resection for malignant bone tumors. The mean defect measured 17.4 cm, and the mean delay between stages was 9.4 months. They followed patients for 6.6 years and found that the mean Musculoskeletal Tumor Society (MSTS) score was 77.4%. There was 1 local recurrence, 1 aseptic nonunion, and 1 fracture40. Astudillo Potes et al. evaluated the use of biodegradable polycaprolactone fumarate spacers as a 1-stage intervention for bone defects using rat femoral models. They noted that biomechanical properties and the development of collagen-rich membranes were similar to those of PMMA spacers. Using histomorphometric evaluation, they found the porous scaffolds to have high bone morphogenic protein-2 (BMP-2) expression and woven bone formation. The authors concluded that this biomaterial could obviate the need for a second surgery for bone grafting41. Researchers at the Shock Trauma Center compared bone transport using ringed fixators with Masquelet-induced membrane bone grafting for tibial segmental bone defects. They reported that bone transport was associated with an 85% reduction in major unplanned reoperations42. A recent innovation is the use of balanced cable bone segment transport with a fulcrum and pulleys, reducing the need for pins in the transport segment. Richmond et al. found that fulcrums without threads and with a larger diameter reduced stiffness in a custom testing rig43. Haruno et al. reported on a case report of using automated struts for balanced cable trifocal bone transport in a 14-year-old boy with a 10.4-cm bone defect, reducing the need to rely on the patient for strut management44. The use of internal lengthening nails has allowed for bone transport without external fixation via plate-assisted bone segment transport (PABST). Freischmidt et al. reported their results using this technique in 15 patients with large femoral and tibial bone defects. All patients achieved full weight-bearing, by a median of 8.7 months; of patients consolidation of the formed by a mean of months; and of patients were noted to have and by a mean of The technique has and can of the internal lengthening nail. 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