Limb lengthening for limb length discrepancy: Overview, complications, and new treatment algorithm

Abstract

Limb lengthening stands as a transformative surgical procedure, offering newfound hope for individuals suffering from limb deformities or discrepancies. Several studies underscore the efficacy of both external and internal fixators in correcting limb length discrepancy (LLD). The choice between these modalities depends on multiple patient-specific factors, with each method presenting distinct advantages and limitations. While the success of limb lengthening in managing LLD is well established, both short-term and long-term physical as well as psychological implications necessitate a critical evaluation of indications. The appropriateness of pursuing limb lengthening should be guided by meticulously considering the prospective physical benefits and psychological ramifications. To address this need, we present a novel treatment algorithm designed to guide clinical decision-making in the management of LLD. This algorithm integrates current evidence, complication patterns, and patient-centered considerations to provide a structured approach to selecting appropriate interventions. A multidisciplinary, patient-focused strategy remains essential for optimizing outcomes and improving the overall quality of life for individuals undergoing limb lengthening.

Key Words: Limb lengthening; Limb length discrepancy; Osteogenesis; External fixators; Complications; Ilizarov

Core Tip: Limb lengthening has become an essential surgical option for patients with limb length discrepancy, yet its complexity and associated complications demand structured guidance. This mini-review synthesizes current evidence on external and internal fixation methods and highlights both physical and psychological outcomes. Importantly, we introduce a new treatment algorithm for limb length discrepancy that integrates patient-specific factors, complication profiles, and multidisciplinary perspectives. By providing a practical framework, this algorithm aims to support surgeons in optimizing decision-making and improving both functional outcomes and quality of life in patients undergoing limb lengthening.

INTRODUCTION

Limb lengthening is a transformative procedure that holds immense potential for enhancing mobility and self-esteem while enabling individuals to achieve a more harmonious and balanced limb structure[1-3]. It has been employed to address a wide range of conditions, including congenital anomalies, growth plate injuries, and trauma-related discrepancies, which are categorized under the term “limb length discrepancy” (LLD)[1-3]. While dwarfism and achondroplasia involve overall short stature rather than isolated limb length differences, limb lengthening may also be used as a treatment option for these conditions to improve functional outcomes or achieve proportional body alignment. LLD refers to a condition where one limb is shorter than the other, and in the case of a leg length discrepancy, it may lead to an imbalance in gait and posture[1-3]. Leg length discrepancies are frequent: About one-third of the population shows 0.5-1.5 cm disparities, 5% more than 1.5 cm, and about 1/1000 have been prescribed a shoe lift[1-3]. There are two types of LLD: (1) Structural, and (2) Functional. Structural discrepancies involve actual bone length differences, while in functional discrepancies, the bones maintain exactly equal length, but it’s rather a condition of joint or muscle contracture that gives rise to a syndrome resembling LLD[4]. The former can occur due to various reasons, such as congenital anomalies causing some limbs to grow more than others, developmental issues, serious fractures or ones that don’t heal properly, and medical conditions such as bone tumors or cysts[4].

Dating back to ancient civilizations, early attempts at limb lengthening have paved the way for the modern techniques we employ today[5]. The history of surgical bone lengthening comprises 100 years of struggling, development, and ongoing learning. The initial strategy of acute or rapid incremental distraction lasted almost half a century[5]. However, it was in the 20^th century that significant breakthroughs occurred, notably with the pioneering work of Dr. Gavril Ilizarov[5,6]. His revolutionary Ilizarov apparatus, an external fixation device, allowed controlled bone distraction and compression, leading to successful limb-lengthening outcomes[5,6]. Contemporary limb lengthening techniques encompass both external and internal approaches. External fixation involves the use of external fixators, such as the Ilizarov apparatus for controlled adjustments, usually done by the patient himself, his caretaker, or his medical team[6]. Alternately, internal methods utilize implants, such as telescopic rods and intramedullary nails, that are placed within the bone and allow for controlled lengthening[6].

Even though limb lengthening surgeries are incomparably successful at treating length discrepancies, it is still questionable if the indications should be followed accurately knowing the various physical and psychological complications of this procedure.

The aim of this article is to provide a comprehensive overview of LLD, the evolution of lengthening techniques, current indications, and the clinical considerations necessary for optimal patient selection and management. In addition, this review highlights emerging priorities for future research, including reducing complication rates, refining patient-centered decision frameworks, and advancing technologies that improve precision, comfort, and long-term outcomes in limb lengthening.

METHODOLOGY

In this narrative review, we aimed to synthesize current evidence on limb lengthening techniques and associated complications. A total of 2583 records were screened. A structured literature search was conducted in PubMed, EMBASE, Scopus, and Google Scholar on May, 2025. The following search queries were used: (1) PubMed, EMBASE: “limb lengthening” OR “leg length discrepancy” OR “limb length discrepancy” AND (“external fixator” OR “internal lengthening nail” OR “Ilizarov”) AND (“complications” OR “outcomes” OR “osteogenesis”); (2) Scopus: TITLE-ABS-KEY (“limb lengthening” OR “limb length discrepancy”) AND TITLE-ABS-KEY (“external fixator” OR “intramedullary nail”) AND (“complications” OR “outcomes”); and (3) Google Scholar: “limb lengthening techniques” + “Ilizarov” + “limb length discrepancy complications”.

We included studies published in English, with no restriction on publication year, that addressed limb lengthening procedures, LLD, or surgical techniques using external or internal devices. Eligible study types included randomized controlled trials, cohort studies, case-control studies, cross-sectional studies, case series, technical notes, and authoritative expert reviews. We excluded isolated case reports, conference abstracts without full text, studies not focused on limb lengthening, and papers unrelated to surgical technique, outcomes, or complications.

LLD

LLD can arise from a diverse range of structural and functional etiologies including congenital anomalies, acquired conditions such as a bone fracture, or damage to the growth plate by infections, tumors, cysts, chemotherapy, or radiation therapy[7]. Moreover, functional discrepancies consist of neuromuscular disorders such as cerebral palsy that can disrupt a child’s general alignment and posture[7]. A thorough understanding of these causative agents is crucial for accurate diagnosis and effective treatment planning. Accurate diagnosis is essential in the course of LLD assessment. Clinical examination, radiographic imaging, and advanced imaging techniques are commonly employed diagnostic approaches[7].

A meticulous physical examination, including assessment of limb lengths and joint range of motion, is very important to detect subtle LLD[7]. Radiographic imaging, such as plain X-rays and computed tomography scans, provides valuable information on bone length and alignment. Magnetic resonance imaging has also been utilized to evaluate soft tissue structures and identify specific causes of LLD[8]. In addition, it has been proposed to use computerized gait analysis and three-dimensional motion capture systems to evaluate limb alignment and functional limitations associated with LLD, to assess the patient’s eligibility for limb lengthening surgery[9,10]. These advanced technologies provide quantitative data on parameters such as step length, stride symmetry, joint angles, and force distribution during walking[9,10]. This information is essential for identifying functional impairments and compensatory mechanisms, such as altered gait patterns, that may not be apparent during a standard clinical evaluation[9,10]. Additionally, gait analysis helps in determining the patient’s eligibility for limb lengthening surgery by assessing the degree of functional impairment and predicting the potential benefits of the intervention. By offering precise, objective measurements, these systems aid in preoperative planning, surgical decision-making, and monitoring postoperative outcomes, ensuring a tailored and patient-specific approach to treatment.

SURGICAL TREATMENT FOR LLD

Lengthening by osteotomy: External fixation

Overview of external fixation: The method of continuous bone elongation was introduced during the 1980s through the utilization of external fixation devices[11]. Following the osteotomy procedure, the process of distraction osteogenesis was employed to stimulate the generation of new bone tissue (Figure 1)[11]. The external device is typically retained for a duration of approximately one to two months for every centimeter of elongation required[11,12].

Figure 1 Illustration demonstrating the steps of osteotomy in limb lengthening. It outlines the sequential stages of limb lengthening using a monolateral external fixator, beginning with osteotomy, followed by the gradual distraction phase (1 mm/day), and concluding with the consolidation phase as new bone forms and strengthens.

Types and techniques of external fixators: Various types of external fixators are employed in orthopedic procedures to correct LLD. These include: (1) One particular circular fixator is the Ilizarov apparatus. It was developed by the Russian orthopedic surgeon Dr. Gavriil Ilizarov in the 1950s and has since become a widely recognized and effective approach[13-15]. It’s known for its circular frame design and versatility in treating various orthopedic conditions, including limb lengthening and deformity correction (Figure 2)[13,16,17]; (2) Despite these challenges, hexapodal fixators have demonstrated excellent outcomes in patients with complex orthopedic conditions; and (3) Other types of external fixators include the hybrid external fixator, which combines elements from various fixator types for specific surgical needs[12,18].

Figure 2 Illustration demonstrating the different types of external fixators. It depicts three commonly used external fixation systems for limb reconstruction and lengthening: (1) A monolateral external fixator; (2) The Taylor Spatial Frame; and (3) The circular Ilizarov external fixator.

Lengthening by osteotomy: Internal fixation

Overview of internal fixation: Internal fixators can be employed in the treatment of LLD when the condition is associated with certain types of fractures or deformities[11]. These fixators are inserted inside the bone's medullary canal or affixed to the bone segments to provide stabilization, promote bone healing, and ultimately correct the LLD[11,19,20].

Types and techniques of internal fixators: Different types of internal fixators, such as intramedullary nails, locking compression plates, and intramedullary rods, offer orthopedic surgeon versatile options for addressing LLD, depending on the patient’s specific condition and requirements[20].

Extramedullary implantable limb lengthening (EMILL) and extramedullary internal limb lengthening are surgical techniques employed to correct LLD or short stature[21]. EMILL involves the implantation of an external remote control magnetic device called PRECICE, which contains an adjustable telescopic rod surgically inserted near the lengthening site[21]. The patient or their physician can use an external remote control to gradually lengthen the rod, resulting in limb lengthening[21]. This method is less invasive and more comfortable than traditional external fixators[21]. Conversely, extramedullary internal limb lengthening relies on internal implants rather than external fixators to achieve the desired bone lengthening[21].

Lengthening by targeting the growth plate

Lengthening procedures that target the growth plate, also known as epiphyseal or physical lengthening, are surgical techniques employed to correct LLD in growing children and adolescents[22]. These procedures capitalize on the growth potential of the epiphyseal plate, a specialized region at the end of long bones where longitudinal growth occurs[22]. The growth plate consists of cartilage cells that eventually ossify into bone, allowing the bone to lengthen until the individual reaches skeletal maturity[22].

EFFICACY OF THESE TECHNIQUES FOR LLD PATIENTS

When addressing LLD, the choice between internal and external fixators hinges on various factors. Numerous studies have demonstrated the effectiveness of both external and internal fixators for LLD correction[23,24]. Furthermore, comprehensive insights into various limb lengthening and deformity correction techniques emphasize the versatility and reliability of both external and internal fixators[23,25,26]. Internal fixators, such as intramedullary nails, have also proven their worth, with effective outcomes reported for intramedullary nailing[27,28]. Emerging techniques like the minimally invasive PRECICE intramedullary nail showcase ongoing innovation and effectiveness in addressing LLD, particularly for non-growing LLD patients[21,27-29]. A particular retrospective study including the cases of 12 children with severe LLD showed that using the Ilizarov fixator for simultaneous femoral and tibial lengthening is a relatively safe procedure with the result of correction of total LLD in one session in a shorter time and less morbidity[25].

In summary, these studies underscore the effectiveness of both internal and external fixators for LLD correction. The choice should hinge on individual patient factors, such as age, growth potential, and the underlying cause of the LLD. External fixators, exemplified by the Ilizarov method, offer precise control and suit growing children. In contrast, internal fixators like intramedullary nailing and plates provide stability for non-growing patients. Emerging techniques such as EMILL with devices like PRECICE offer a less invasive option for non-growing LLD correction, especially when there is an already retained implant, or the medullary canal is too narrow[21,30]. The selection of the most suitable approach should be made in consultation with an orthopedic specialist, accounting for each patient’s unique needs[30].

FACTORS AFFECTING LIMB LENGTHENING OUTCOMES

Despite the innovative techniques in limb lengthening, the post-operative outcomes are affected by various factors that could influence the recovery of the patient. For instance, successful limb lengthening depends on patient-related factors, surgical technique, distraction protocol, and patient compliance with rehabilitation protocols.

Patient-related factors

Younger patients show a better profile of bone regeneration post-surgery than adults due to their increased regeneration capacity[31]. Moreover, the presence of underlying comorbidities such as diabetes, postmenopausal osteoporosis, and chronic stress plays a pivotal role in the retardation of bone growth and regeneration[32].

Surgical technique

Appropriate and precise preoperative planning (radiographic, segment elongation) is extremely important to ensure a smooth and successful surgery for both the patient and the surgeon[33]. The selection of external fixation devices, such as Ilizarov or Taylor Spatial Frame, and the use of intramedullary nails or internal fixation, are key determinants of mechanical stability during the lengthening process.

Rate and distraction protocol

The rate and distraction protocol are 2 very important criteria for a successful and better outcome of the surgery. First, the distraction of the bone should be 1 mm/day; an overly aggressive distraction rate could lead to serious complications such as nerve injury and nonunion of the bone[33]. The distraction process should be slow and gradual to ensure appropriate osteogenesis and the absence of complications[34].

Compliance with rehabilitation

The commitment and adherence to rehabilitation after a limb lengthening surgery is extremely important and can greatly affect the success of the surgery. In fact, the post-surgical initiation of physical therapy showed better outcomes since it reduced the complications of immobility, reduced the risk of mortality, and resulted in a fast recovery[35]. Moreover, adherence to antibiotics (for prophylactic purposes to prevent infections, as cited below in the complications) and analgesics is also pivotal for reducing complications[36].

COMPLICATIONS

Limb lengthening procedures can be accompanied by various complications, ranging from mild discomfort to complete loss of function of the limb and even limb amputation. These complications encompass a wide range of issues, including neurological, infectious, orthopedic, and psychological sequelae (Figure 3).

Figure 3 Summary of the complications in limb lengthening procedures. It summarizes key complications of limb lengthening, including neurological, infectious, joint-related, bone-related (across different techniques), and psychological effects associated with prolonged treatment.

Pain and neurological complications

Pain is a common complication, with internal lengthening rods generally associated with less pain than external fixators[37,38]. In case of pain, one can slow down the distraction for a few days until pain resolution. Patients may also experience electrophysiological changes like compound muscle action potential latency, because of altered expression of sodium channels in the nodes of Ranvier following elongation, resulting in motor and sensory loss[37,38].

Another potential complication is nerve compression, with peroneal nerve compression against the fibula being the most encountered[37]. In such cases, surgical decompression is recommended if there is a deterioration in function. Patients with a congenital etiology tend to show a greater reduction in nerve function compared to those with a growth disturbance[37]. The extent of nerve damage and electrophysiological deterioration increases with the increased amount and rate of lengthening[37]. Effective management of complications is pivotal to ensuring positive outcomes in limb lengthening procedures. Initial strategies involve modifying the distraction rate to alleviate pressure on the affected nerve. If symptoms persist or progress, surgical decompression, such as fasciotomy or neurolysis, may be necessary to restore nerve function[37,38].

Infection

Infections delay wound healing and may cause deformities if left untreated. When an external fixator is used, especially for a prolonged time, there is an increased risk of pin tract infection, which can necessitate the removal of the device[39-41]. Superficial infections can often be treated with irrigation and antibiotics. Deeper infections like osteomyelitis are classified as acute or chronic. Acute ones are treated with antibiotics and debridement. However, in case of chronicity, amputation may be necessary[41,42]. Infections, particularly pin tract infections associated with external fixators, are managed based on the severity of the infection. For superficial infections, meticulous pin care, along with the use of topical or systemic antibiotics, is effective. In cases of deeper infections, such as osteomyelitis, surgical debridement may be required to remove infected tissue, and prolonged courses of intravenous antibiotics are recommended[39-41]. Preventative measures, including rigorous adherence to pin care protocols and patient education, significantly reduce the risk of infections.

Joint-related complications

A prolonged restricted range of motion leads to joint stiffness and contracture[39,42]. This can be best managed through early and aggressive physical therapy aimed at maintaining joint mobility and preventing adhesions. Muscle plasty, physiotherapy, and rehabilitation also address these issues in both children and adults with external or internal fixators[42]. Furthermore, joint subluxation, acetabular dislocation, and avascular necrosis can arise, often necessitating surgery or correction by Illizarov[43,44].

Bone-related complications

Fractures are mostly seen with the Ilizarov fixator after frame removal[38]. Hybrid fixation techniques, combining external fixators with intramedullary nails, can improve bone stability and reduce fracture risk[40]. Other complications include premature consolidation, electrical wire fractures, nail breakage, nail backwinding, and united[45]. Unintentional shortening[40,43], delayed bone healing[46], pseudoarthrosis, osteonecrosis, physeal injuries, screw migration, risk of the nail becoming unreachable inside the canal, nail tilting leading to varus and valgus deformities are mainly related to intramedullary nail use[47-51]. The use of newer nail generations, solid nails, blocking screws, and surgical correction can mitigate these problems[49]. For nonunion or delayed healing, interventions such as bone grafting, platelet-rich plasma injections, or dynamization of internal nails are employed to stimulate osteogenesis[49]. External fixation systems can also lead to varus and valgus deformities, heterotopic ossification, delayed healing, reduced joint motion, equinus deformities, premature consolidation, prolonged fixation time, and nonunion, where the patient might necessitate surgical correction[51-53].

Psychological complications

According to a study by Depaoli et al[54], patients who undergo limb-lengthening surgery may experience depression, anxiety, and social isolation. Additionally, the leg-lengthening procedure itself can be psychologically stressful due to its long duration and numerous complications[55]. As a result, patients and their families can experience serious emotional problems during hospitalization[56]. However, it is important to note that some studies have found that self-esteem and perceived competence can improve after the procedure, and positive appraisal of physical appearance may also increase[55]. It is crucial to carefully consider the potential psychological impacts of the leg-lengthening procedure when deciding to undergo the surgery. While there may be short-term improvements in self-esteem, long-term psychosocial evaluations have shown a return to near preoperative levels of self-esteem[57].

RECENT GUIDELINES AND RECOMMENDATIONS

The choice of limb lengthening procedure should be primarily based on the orthopedic surgeon’s experience and the patient’s objective condition[39]. In children, external fixators remain the treatment of choice because the damage to open growth plates is more serious with internal fixation[49]. For Achilles tendon lengthening, a physiotherapy-focused approach to address stiffness is considered more appropriate than surgery, as surgery can further weaken the tendon[58]. When it comes to placing a nail within a curved femur, it is not recommended to use a straight nail as it can lead to failure to achieve the desired length, especially when there is a longer bone segment in contact with the thick segment of the nail[47]. Concerning bone cancer patients, limb lengthening after surgical treatment of malignancy is appropriate only when the risk of recurrence is less than 10% and preferably in patients not undergoing radiotherapy and chemotherapy[59,60].

Hybrid techniques are preferred over the use of internal or external fixators alone. These techniques have better functional outcomes and decreased complications resulting from either technique alone[37,40,52,61].

Patient training and regular follow-ups during the lengthening phase are crucial for the procedure’s success[46]. Adherence to the protocol increases the likelihood of positive functional outcomes and minimizes complications. Delays in the lengthening schedule, caused by early bone consolidation, unauthorized weight bearing, or non-compliance with the lengthening protocol, may require an increase in daily distraction sessions[42]. In cases of long-term nonunion, bone grafting, platelet-rich plasma injections, nail dynamization, or nail exchange are recommended[42,48,49,62]. In situations of slow bone healing, early revision surgery with an exchange for a solid trauma nail should be considered to prevent nail breakage[6]. Finally, the involvement of a multidisciplinary team is particularly important in cases where the risk of complications is high[42]. By considering these various factors and implementing these strategies, orthopedic surgeons can optimize limb-lengthening procedures and improve patient outcomes.

The extent of the LLD usually guides the treatment choice (Figure 4)[11,63-68]. For a difference in length not exceeding 1 cm, observation is typically sufficient. When the discrepancy is between 1-2 cm, we reduce it to 1 cm using conservative measures like shoe lifts and insoles[11,64].

Figure 4 Leg length discrepancy treatment algorithm. This algorithm outlines recommended management of leg length discrepancy according to discrepancy size and skeletal maturity, highlighting when observation, conservative therapy, epiphysiodesis, shortening, or lengthening procedures are indicated.

For a discrepancy of 2-5 cm, we either adopt a conservative or surgical approach[66-68]. Surgery remains the only solution if conservative treatment fails to relieve pain. In this case, surgery becomes necessary[11,67]. Regarding the surgical repair, we can either lengthen the shorter limb using intramedullary nails or external fixators (osteotomy and distraction osteogenesis) or shorten the longer limb by epiphysiodesis for skeletally immature patients[65,67], or an acute shortening osteotomy for skeletally mature patients[11]. Multiple long-term studies have demonstrated that temporary and permanent epiphysiodesis are effective options for correcting limb-length discrepancies of 2-5 cm in skeletally immature patients, with significant reduction in final LLD at skeletal maturity[67,69]. Evidence also shows that permanent epiphysiodesis relies heavily on accurate timing and prediction of remaining growth, whereas temporary methods may reduce the risk of over-correction or under-correction[67,69]. However, growth-modulation techniques may be less reliable in patients with pathological physis or dysplastic bone disorders, highlighting the need for individualized surgical planning[67,69].

For discrepancies greater than 5 cm, potential treatments include shoe lifts, physical therapy, or multi-step lengthening that combines intramedullary nails with external fixators (Figure 4)[11,63].

It is worth noting that the proposed treatment algorithm is specifically optimized for LLD, where gait mechanics, pelvic alignment, and weight-bearing forces inform clinical decision-making. In contrast, upper-LLD follow different functional priorities and therefore require separate, tailored criteria rather than direct application of this lower-limb-focused framework.

CONCLUSION

Limb lengthening procedures represent a remarkable advancement in orthopedic surgery, offering renewed hope and improved mobility to individuals facing LLD. The choice between internal and external fixation methods hinges on various patient-specific factors, with each approach demonstrating its own set of advantages and considerations. Research supports the efficacy of both techniques, highlighting the precision of external fixators like the Ilizarov method for growing children and the stability provided by internal fixators for non-growing patients. Nonetheless, it is essential to acknowledge the potential complications associated with these procedures, encompassing neurological issues, infections, and psychosocial challenges. Psychological well-being can fluctuate during the arduous lengthening process, emphasizing the need for comprehensive patient support. To ensure the best possible outcomes, meticulous preoperative planning, vigilant postoperative care, and the consideration of hybrid techniques are pivotal. Ultimately, the decision to undergo limb lengthening must be a carefully considered one, balancing the physical benefits with the potential psychological impact. A collaborative, patient-centered approach, involving a multidisciplinary team of medical professionals, is paramount in optimizing the results of limb-lengthening procedures, thereby enhancing the overall quality of life for individuals with LLD. Future research in limb lengthening should prioritize improving osteogenesis biology, developing predictive models to guide individualized treatment choices, and refining patient-centered criteria for selecting lengthening techniques. Additional priorities include reducing complication rates, improving psychological support frameworks, and advancing internal and hybrid lengthening technologies that enhance accuracy, reduce treatment burden, and optimize long-term functional outcomes.