Congenital lower limb differences are present at birth due to aplasia or hypoplasia of bone during fetal development,1 occurring in either a longitudinal or transverse manner and can be complete or incomplete. They can involve one or more bones, occur unilaterally or bilaterally, and are seldom associated with organ system defects, and association with other major congenital anomalies is more common in upper limb deficiencies than lower limb deficiencies.2
Naming is restricted to skeletal deficiencies and are described on an anatomical and radiological basis. Naming does not classify the etiology of the deficiency. They are divided into transverse and longitudinal. Transverse deficiencies are when a limb develops normally to a particular level, beyond which there are no skeletal elements present. There may be digital buds, however. Transverse deficiencies can be described as total, partial, or upper, middle or lower third depending on the affected bones. Longitudinal deficiencies are a reduction or absence of skeletal elements within the long axis of the limb, and there may or may not be normal skeletal elements distal to the affected bone or bones. For longitudinal deficiencies, bones are named in a proximo-distal sequence, and noted to be totally or partially absent (often involving a percentage if partially absent). If metacarpals or metatarsals are involved, they should be numbered starting medially moving laterally. The term “ray” refers to a deficient metacarpal or metatarsal and its corresponding phalanges. Terms such as hemimelia (meaning absence of all or part of the distal half of a limb), amelia (congenital absence of one or more limbs) and phocomelia (where hands or feet are attached close to the trunk and limbs are underdeveloped or absent) are older terms that are often still used in literature and in billing codes, however their use should be avoided due to lack of accuracy in describing the deficiency, and due to the difficulty in translating these terms into other languages that are not related to Greek.3
Etiology and Risk Factors
The etiology of congenital limb deficiency in most cases is unknown.4 Some medications known to affect limb development include thalidomide, retinoic acid, and misoprostol. Teratogenic causes are often difficult to study because prenatal history may be complicated by maternal recall bias.5 Limb development occurs between the fourth and eighth week of gestation, so many expectant mothers may not have been aware of their pregnancy at that time, further increasing maternal recall bias. In addition to teratogenic medications, limb deficiencies can also be caused by vascular disruption (e.g., amniotic band syndrome), vascular malformations (e.g., Poland syndrome), or genetic factors (spontaneous point mutation). Of the more than 120 clinical congenital limb deficiencies described in the Online Mendelian Inheritance in Man (OMIM; www.ncbi.nlm.nih.gov/omim), less than 40% have a known molecular basis.4 Maternal cigarette smoking increases the risk for longitudinal deficiencies, such as preaxial deficiencies of the lower extremity.6 Poorly controlled maternal diabetes during the first trimester can cause longitudinal deficiencies as well as sacral agenesis with lower extremity hypoplasia.7 In addition, an association between maternal thrombophilia and congenital limb deficiencies has been described.8 Additional risk factors may include maternal age >35, maternal smoking or alcohol use, and chorionic villus sampling.2
Epidemiology and primary prevention
Overall, congenital limb deficiencies occur at a rate of 0.26 to 1 per 1000 live births.4 The Center for Disease Control and Prevention estimates that each year 750 infants are born in the United States with lower limb deficiencies.9 No racial predilection has been noted.10 Congenital longitudinal fibular deficiency is the most common, occurring in 1-2 per 100,000 live births.11 Primary prevention includes a prenatal daily multivitamin with folic acid (400 µg), screening for smoking, diabetes, and thrombophilia, as well as stopping teratogenic medications prior to pregnancy.
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
Lower limb congenital malformations may worsen with bone growth, depending on the number of bones and growth plates involved. For example, in children with longitudinal fibular deficiency, progressive genu valgum results secondary to lateral femoral condyle hypoplasia.
Specific secondary or associated conditions and complications
Most lower limb deficiencies are not associated with other organ system defects. Some exceptions include the following:
- Tibial deficiency has been reported with deafness, ectrodactyly or polydactyly of the hands, and cleft palate.12
- Femoral hypoplasia-unusual facies syndrome (femoral facial syndrome) involves bilateral femurs, facial abnormalities including micrognathia and cleft palate, and may include hypoplasia or synostosis of the upper extremity, vertebral abnormalities, congenital heart disease, or polydactyly.13
- Roberts-SC phocomelia syndrome results in bilateral symmetric tetraphocomelia and may include thumb aplasia, syndactyly, elbow and knee flexion contractures, intellectual disability, cleft lip/palate, micrognathia, hypotelorism, cryptorchidism, and cardiac defects.14
- Sacral agenesis (caudal regression syndrome) is associated with abnormalities in all 4 limbs including congenital hemipelvis or complete femoral deficiency, as well as spinal dysraphisms, renal anomalies, and is often associated with neurogenic bowel and bladder.4, 15, 16, 17
Essentials of Assessment
- A careful maternal and birth history, including prenatal exposures.
- Family history, although familial associations are rare.
- Developmental history, including gross and fine motor milestones.
- A full Review of Systems to rule out congenital syndromes, particularly cardiac, musculoskeletal, eyes/ears/nose/throat, neurologic, gastrointestinal, and genitourinary symptoms.
- Assessment of family understanding of the condition, expectations, and goals.
- Psychosocial factors
- Examine the affected/residual limb by first inspecting the skin for dimples, puckering/tethering, verrucous hyperplasia, breakdown, or other abnormalities. Check for lymphedema in the extremities.
- A thorough joint assessment to determine stability and weight-bearing potential is imperative as well as active and passive range of motion and strength testing to decipher the child’s ability to use the affected limb with a prosthesis or orthosis in the future. Evaluation of the hip, knee and ankle for range of motion, strength, stability and whether or not there is dislocation, as these are important factors in surgical planning. Assess the size, shape, and location of the bony defect. Determine if distal joints are present, and if they involve missing or intact bones.
- Examine the spine for scoliosis or overlying skin abnormalities.
- Observe postural balance while seated and standing as well as ambulation, if present.
- Observe how mobility is achieved, such as crawling types (commando, bear, or reciprocal), or if the child attempts to pull to stand on objects in the room.
- If able, perform sensory testing
- Complete a full physical exam to rule out major organ abnormalities (e.g., cardiac defects).
Dynamic standing balance, gait and mobility assessment is important for prosthetic planning. Observe how the child interacts with others to determine cognitive status, speech, and development. Also observe gross motor skills and ADLs. Obtain information from the child’s teacher about how they are doing in school and in extracurricular activities including sports.
If syndromic findings are present on exam, consider appropriate genetic testing and if indicated, genetic consultation.
Radiographs of the involved limb with opposite side comparison can be helpful in determining outcomes and possible surgical planning. Consider spine films if spinal abnormalities are suspected or observed on physical exam. In newborns, radiographs are often inconclusive due to the lack of bony ossification and thus may require repeat radiographs in the future. If there is concern for a congenital syndrome, consider additional imaging such as an echocardiogram or renal ultrasound, or referral to a medical geneticist. An in-depth history including feeding/swallowing, respiratory function, cardiac and hematologic history should be obtained.
Supplemental assessment tools
Consider a formal gait analysis if abnormal gait patterns are observed, or if there is difficulty with functional prosthetic fitting or surgical planning.
Early predictions of outcomes
Presence of knee or ankle function increases options for surgical conversion and prosthetic fitting. For example, in the case of proximal focal femoral dysplasia, the presence of ankle range of motion and stability with lack of knee function may be corrected with rotationplasty surgery, which offers superior control and function over an above-the-knee amputation with mechanical prosthetic knee.18 The presence or absence of active knee extension in a child with tibial longitudinal deficiency can determine if knee disarticulation is a more appropriate surgical plan versus foot ablation.16 Assessing stability of the knee is important if guided growth or lengthening is being considered.19 It is important to project limb length discrepancies when developing a treatment plan.
Perform an assessment of the home and school environment and accessibility. Home climate (e.g., hot and humid) may also impact decisions regarding the type of prosthesis prescribed.
Social role and social support system
Screening for psychosocial issues, such as self-image/self-esteem problems or teasing/bullying in school is recommended. Assess parental cultural and personal beliefs, as this impacts the child’s support system. Assess access to resources, such as physical therapy for gait training and funding for prostheses.
The child’s access to proper prosthetic follow-up should be carefully assessed prior to surgical intervention, especially in the case of patients who live in very rural areas or less developed parts of the world.
Rehabilitation Management and Treatments
Coordination of care
A multidisciplinary approach is recommended when available.
Biannual, coordinated assessments by a physician, physical therapist, occupational therapist (when needed if ADLs are impacted or multilimb involvement), prosthetist, social worker, and psychologist.
- Physical therapist: evaluates function, strength, and range of motion, and assists with activities such as ambulation and mobility, with or without assistive devices like walkers or wheelchairs.
- Occupational therapist: evaluates activities of daily living and assists with adaptive fitting (e.g., in the case of upper limb involvement) if the patient uses their feet for activities and needs to be able to remove the prosthesis for foot use.
- Prosthetist: inspects function of the prosthetic components and makes adjustments as necessary to ensure adequate fit in collaboration with the physician.
- Social worker and/or psychologist: often needed to assess the patient and family for psychosocial risk factors, depression, problems with self-image/self-esteem, acceptance of disability, bullying, or other school issues.
Multidisciplinary management ensures holistic care of a developing, growing child with a limb difference.
In community-based practice, physician follow-up should be coordinated with the prosthetist whenever possible.
Patient & family education
Education on proper care of the prosthesis and residual limb is important to avoid injury or morbidity. Children should be encouraged to be active and involved in sports or extracurricular activities and encouraged to prepare a personal script to discuss their limb differences with their classmates, teachers, and friends. Refer to support groups, medical camps, online communities, and facilitate meeting other families, if indicated.
Useful resources include the following:
- Amputee Coalition of America (www.amputee-coalition.org)
- Amputee-Online.com (www.amputee-online.com)
- Challenged Athletes Foundation (www.challengedathletes.org)
- Disabled Sports USA (www.dsusa.org)
- Limbless Association (www.limbless-association.org)
- Limbs for Life Foundation (www.limbsforlife.org)
- U.S. Paralympics (www.usparalympics.org)
Amputee activity levels have historically been classified by the Medicare Functional Classification Level, or K level. The K level is a subjective assessment of current activity level of the amputee based on self-report and clinical observation. Children are often automatically put in the K4 level (potential for ambulation that exceeds basic ambulation skills, i.e., high impact/energy); however, it is not a useful qualitative measure of treatment outcome.
Another measurement of community-based gait performance in children is the data collected by an ankle-worn accelerometer, worn over a specific time period.20 However, this has not been applied in pediatric amputees. Subjective measures of prosthetic use/fit can include extracurricular activity, pain assessments, and skin evaluation. Questionnaires, such as the Child Amputee Prosthetics Project-Functional Status Inventory for Preschool Children (CAPP-FSIP) can be used to evaluate the functional status of preschool-aged children with limb deficiency.21
3-D printing is an emerging field that is beginning to show some utility in fitting patients with upper limb deficiency.22 It has not yet been widely applied to lower limb prostheses, however. Osseointegration, or replacing a prosthetic socket with prosthetic implant into the residual bone, eliminates the need for a traditional socket-mounted prosthesis and can eliminate associated problems such as sweating, pinching, and skin irritation with a traditional socket. However, there have been high rates of postoperative complications.23, 24
Targeted muscle reinnervation enables more intuitive control of upper extremity myeloelectric prostheses by attaching residual nerves to muscles that have lost function. This improves upper extremity function compared to preoperative function, and many patients had resolution of pain from neuromas.25
Mind-controlled prostheses, or self-contained neuromusculoskeletal limbs, have recently been used for patients with upper extremity amputations. Electrodes detect signals from voluntary contraction in remaining muscles to create motion in the prosthetic hand. This innovative technology additionally provides intuitive, real-time somatosensory feedback from the prosthetic hand.26
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
The treatment of a child with a congenital limb difference is maximized when the family and child are involved in the decision-making process.
The surgical and prosthetic options are often complex and must be suited to the individual’s needs.
A multidisciplinary team based approach is recommended.
Cutting Edge/ Emerging and Unique Concepts and Practice
Continued improvements in pediatric-sized components offer technological advances in comfort, stability, cosmesis, and mobility. These include myoelectric or power-assist (motor-driven) knee and ankle units and elastomeric prosthetic coverings. Limitations in the use of these exist due to lack of payer funding and applicability of the components to a growing, active, and developing child.27
Gaps in the Evidence- Based Knowledge
The use of myoelectric prostheses in congenital upper limb deformities is commonplace; however, myoelectric lower limb prostheses have not been tested nor widely applied to children. Additionally, there are a limited number of studies on the long-term implantation of electrodes that provide somatosensory feedback.26 The utilization of osseointegration of prosthetics for children is still unclear, as children continue to grow, necessitating longer term follow up on existing studies.28 Major procedures like rotationplasty are effective, but the effect on psychological health is unclear.18 Ongoing research in novel designs and methods to fit prostheses with continued input from the patients is essential for further advancements in pediatric prosthetic limbs.24
- Wilcox WR, Coulter CP, Schmitz ML. Congenital limb deficiency disorders. Clin Perinatol.2015 Jun;42(2):281-300.
- Syvänen J, Nietosvaara Y, Hurme S, et al. Maternal risk factors for congenital limb deficiencies: A population-based case-control study. Paediatr Perinat Epidemiol. Published online January 13, 2021. doi:10.1111/ppe.12740
- Day HJB. The ISO/ISPO classification of congenital limb deficiency. The Journal of the International Society for Prosthetics and Orthotics. 1991;15(2):67-69.
- Yoon PW, Rasmussen SA, Lynberg MC, et al. The National Birth Defects Prevention Study. Public Health Rep. 2001;116 Suppl 1:32-40.
- Werler MM, Pober BR, Nelson K, Holmes LB. Reporting accuracy among mothers of malformed and nonmalformed infants. Am J Epidemiol. 1989;129:415-421.
- Caspers KM, Romitti PA, Lin S, et al. Maternal periconceptional exposure to cigarette smoking and congenital limb deficiencies. Paediatr Perinat Epidemiol. 2013:27(6),509-520.
- Garne E, Loane M, Dolk H, et al. Spectrum of congenital anomalies in pregnancies with pregestational diabetes. Birth Defect Res A Clin Mol Teratol. 2013:94 (3):134-140.
- Ordal L, et al. Congenital limb deficiencies with vascular etiology: Possible association with maternal thrombophilia. Am J Med Genet A. 2016 Dec;170(12):3083-3089.
- Dillingham TR, Pezzin LE, MacKensie EJ. Limb amputation and limb deficiency: epidemiology and recent trends in the US. South Med J. 2002;95:875-883.
- Canfield MA, Honein MA, Yuskiv N, et al. National estimates and race/ethnic-specific variation of selected birth defects in the United States, 1999-2001. Birth Defects Res A. 2006;76:747-756.
- Ghanem I. Epidemiology, etiology, and genetic aspects of reduction deficiencies of the lower limb. Journal of Children’s Orthopaedics. 2008;2(5):329-332. doi:10.1007/s11832-008-0098-9
- Cooper A, Fernandes JA. Lower limb deficiency syndromes. Orthopaedics and Trauma. 2016;30(6):547-552. doi:10.1016/j.mporth.2016.09.007
- Lacarrubba-Flores MDJ, Carvalho DR, Ribeiro EM, et al. Femoral-facial syndrome: A review of the literature and 14 additional patients including a monozygotic discordant twin pair. Am J Med Genet A. 2018;176(9):1917-1928. doi:10.1002/ajmg.a.40425
- Máximo G, Raposo-Amaral CA, Paez ABA, Raposo-Amaral CE. Roberts Syndrome With a Bilateral Cleft Lip and Palate. J Craniofac Surg. 2021;32(1):e23-e25. doi:10.1097/SCS.0000000000006851
- Lee JY, Shim Y, Wang K-C. Caudal Agenesis : Understanding the Base of the Wide Clinical Spectrum. J Korean Neurosurg Soc. 2021;64(3):380-385. doi:10.3340/jkns.2021.0025
- Krajbich JI,Pinzur MS, Potter LTC BK, Stevens PM, eds. Atlas of Amputations and Limb Deficiencies: Surgical Prosthetic, and Rehabilitation Principles. 4th ed. Rosemont, IL: American Academy of Orthopedic Surgeons; 2016.Vol.3.
- Alexander MA, Matthews DJ, eds. Pediatric Rehabilitation: Principles and Practice. 4th ed. New York, NY: Demos Medical; 2010.
- Deloge C, Allington N, Rondia J. Rotationplasty as an alternative to amputation. Rev Med Liege. 2021;76(4):262-267.
- Mindler GT, Radler C, Ganger R. The unstable knee in congenital limb deficiency. J Child Orthop.2016 Dec;10(6):521-528.
- Bjornson KF, Yung D, Jacques K, Burr RL, Christakis D. StepWatch stride counting: accuracy, precision, and prediction of energy expenditure in children. J Pediatr Rehabil Med. 2012;5:7-14.
- Griffet J. Amputation and prosthesis fitting in paediatric patients. Orthop Traumatol Surg Res. 2016;102(1 Suppl):S161-175. doi:10.1016/j.otsr.2015.03.020
- Abdul Wahit MA, Ahmad SA, Marhaban MH, Wada C, Izhar LI. 3D Printed Robot Hand Structure Using Four-Bar Linkage Mechanism for Prosthetic Application. Sensors (Basel). 2020;20(15). doi:10.3390/s20154174
- Diaz Balzani L, Ciuffreda M, Vadalà G, Di Pino G, Papalia R, Denaro V. Osseointegration for lower and upper-limb amputation a systematic review of clinical outcomes and complications. J Biol Regul Homeost Agents. 2020;34(4 Suppl. 3):315-326. Congress of the Italian Orthopaedic Research Society.
- Mitchell F. Prosthetic limbs for children. The Lancet Child & Adolescent Health. 2020;4(12):862-863. doi:10.1016/S2352-4642(20)30347-3
- Keszler MS, Heckman JT, Kaufman GE, Morgenroth DC. Advances in Prosthetics and Rehabilitation of Individuals with Limb Loss. Phys Med Rehabil Clin N Am. 2019;30(2):423-437. doi:10.1016/j.pmr.2018.12.013
- Ortiz-Catalan M, Mastinu E, Sassu P, Aszmann O, Brånemark R. Self-Contained Neuromusculoskeletal Arm Prostheses. N Engl J Med. 2020;382(18):1732-1738. doi:10.1056/NEJMoa1917537
- Talwalkar VR. Pediatric prosthetics. Current Opinion in Orthopaedics. 2006;17(6):517-520. doi:10.1097/01.bco.0000247362.74750.32
- Beltrami G, Ristori G, Nucci AM, et al. Custom-Made 3D-Printed Implants as Novel Approach to Reconstructive Surgery after Oncologic Resection in Pediatric Patients. J Clin Med. 2021;10(5). doi:10.3390/jcm10051056
Original Version of the Topic
Phoebe R. Scott-Wyard, DO. Congenital Lower Limb Deficiency. 12/2/2013.
Previous Revision(s) of the Topic
Phoebe R. Scott-Wyard, DO. Congenital Lower Limb Deficiency. 8/1/2017.
Justin Weppner, DO
Nothing to Disclose
Emily Hillaker, DO
Nothing to Disclose
William Ide, MD
Nothing to Disclose