You are in: eMedicine Specialties > Orthopedic Surgery > KNEE Fibular HemimeliaArticle Last Updated: Aug 14, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Michael C Holmstrom, MD, Consulting Surgeon, Department of Orthopedics, The Orthopedic Specialty Hospital (TOSH) Michael C Holmstrom is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Medical Association, Arthroscopy Association of North America, Pediatric Orthopaedic Society of North America, and Utah Medical Association Coauthor(s): Peter M Stevens, MD, Professor, Director of Pediatric Orthopedic Fellowship Program, Department of Orthopedics, University of Utah School of Medicine Editors: Dennis P Grogan, MD, Clinical Professor, Department of Orthopedic Surgery, University of South Florida College of Medicine; Chief of Staff, Department of Orthopedic Surgery, Shriners Hospital for Children of Tampa; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Thomas M DeBerardino, MD, Director, John A Feagin, Jr, Sports Medicine Fellowship at West Point, Associate Professor of Orthopedic Surgery, Uniformed Services University of the Health Sciences and Keller Army Community Hospital; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Carlos J Lavernia, MD, FAAOS, Adjunct Clinical Professor, Department of Orthopedic Surgery, University of Miami School of Medicine; Medical Director, Orthopedic Institute at Mercy Hospital Author and Editor Disclosure Synonyms and related keywords: fibular hemimelia, fibular hypoplasia, fibula hypoplasia, fibula aplasia, fibular aplasia, fibular abnormality, postaxial hypoplasia of the lower extremity, limb-length discrepancy, postaxial hypoplasia of the lower extremity, amelia, phocomelia, ectromelia, sirenomelia INTRODUCTIONSection 2 of 12
  Fibular hemimelia was described initially as a condition that is related to aplasia or hypoplasia of the fibula.1 Coventry and Johnson, and later Achterman and Kalamchi, provided early classification systems.2, 3 These are primarily based on and concerned with treatment of the accompanying limb-length discrepancy. A constellation of lower-extremity features accompanies fibular hemimelia. These should be evaluated and treated when appropriate. The association of these features has led to a recent recommendation that the name postaxial hypoplasia of the lower extremity may be more appropriate and a better description of the entire pattern of abnormalities seen with this syndrome.4 History of the ProcedureHistorically, the recommended treatment for postaxial hypoplasia of the lower extremity (fibular hemimelia) was amputation, but only as a last resort. However, Herring et al showed that patients who undergo amputation after several failed attempts at salvage are at high risk for emotional problems.5, 6 Therefore, determining which patients fare better with immediate amputation is important. Generally, these are patients with a nonfunctional foot or a limb-length discrepancy of more than 20-30%.7 Then, the need arose to establish criteria for the indications for amputation. The first recommendations used a projected limb-length discrepancy of 3 inches at maturity as an appropriate cutoff. However, as limb-lengthening techniques have improved, this length criterion has increased, and limb salvage is regarded more often as a feasible option. Other features of postaxial hypoplasia have also been investigated, and treatments have been defined. ProblemAs is evidenced by its historic name, a primary feature of fibular hemimelia is the fibular abnormality. This may range from a minimal shortening of the fibula to its complete absence. See Clinical for other related features. FrequencyPostaxial hypoplasia of the lower extremity (fibular hemimelia) is rare and has variable expression, ranging from mild deformity (which the patient may never notice) to severe deformity. EtiologyAlthough a number of causes have been suggested for postaxial hypoplasia of the lower extremity (fibular hemimelia), recent theory postulates that interference with limb-bud development plays an important role. Widespread pathology throughout the limb has been noted, even in mild cases of fibular deficiency.8 During the fetal period, the fibular field of the limb bud controls development of the proximal femur, explaining the frequent association of femoral abnormalities. Other associated abnormalities of the knee, leg, ankle, and foot also are related to the fibular field of the lower limb bud.9, 10, 11 Therefore, postaxial hypoplasia of the lower extremity is a descriptive term that encompasses this constellation of abnormalities. PathophysiologySee Etiology. ClinicalPresentations of postaxial hypoplasia of the lower extremity (fibular hemimelia) vary widely, ranging from what appears to be merely an absent fifth toe in a newborn or a minimal difference in limb lengths, to severe fibular deformities that are immediately apparent. The clinician must also look for associated abnormalities, including problems with alignment and stability, and must realize that the clinical picture may evolve with growth and development. Clinical findings may include the following:
Related eMedicine topics: INDICATIONSSection 3 of 12
Evaluate the entire limb in patients presenting with postaxial hypoplasia of the lower extremity (fibular hemimelia), specifically examining for all of the previously mentioned clinical features. This is important and helpful for developing a treatment plan, both to guide the physician's treatment decisions and to inform the family of what they might expect. The ultimate goal is to enable the child to gain maximal function by achieving adequate lower-extremity alignment, length, and stability. If this is not possible, the goal is an appropriately timed amputation to allow the child's development with the use of a functional prosthesis. Goals and expectations must be realistic. When treatment alternatives are discussed, the social and psychological state of the child and the child's family must be considered, especially if multiple surgeries are anticipated. RELEVANT ANATOMYSection 4 of 12
Fibular hemimelia cannot be characterized fully by any single anatomic feature. The condition encompasses a constellation of features that are best addressed individually to obtain optimal limb length, alignment, and function. CONTRAINDICATIONSSection 5 of 12
As with any surgical procedure, the potential benefits must outweigh the risks. Although a number of abnormalities are related to postaxial hypoplasia of the lower extremity (fibular hemimelia), limb-length discrepancy is one of the more difficult to address. If the difference is minimal or if it is large and accompanied by a nonfunctional foot, the decision is relatively straightforward. However, in many situations, several relative contraindications to limb-lengthening salvage operations may be present. The recommended maximum to be corrected is 7.5-15 cm. Other relative contraindications include a nonfunctional foot, a limb that may have severe cosmetic problems, or a patient who may not tolerate multiple surgeries over an extended period. Each patient's situation is unique, however. Most patients and parents want the limb to be as normal as possible, and they may wish to undergo the long-term treatment necessary to achieve this goal despite relative contraindications. WORKUPSection 6 of 12
Imaging StudiesJudicious use of appropriate imaging studies is necessary to fully evaluate and treat postaxial hypoplasia of the lower extremity (fibular hemimelia). Some of the more pertinent radiographic studies are listed below.
Related eMedicine topic: TREATMENTSection 7 of 12
Medical therapyNo specific medical therapies can correct the underlying abnormalities for fibular hemimelia. However, for mild deformities, observation and/or nonoperative management may be useful. As with limb-length discrepancies resulting from other causes, no treatment may be necessary or the use of heel lifts may be adequate, particularly in discrepancies less than 2 cm. However, although the percentage of shortening generally remains constant at 10-20% relative to the contralateral side, the absolute discrepancy may progress with growth and must be followed until skeletal maturity.15 Similarly, observation may be adequate for hip varus, genu valgum, tibial kyphosis, and patellar instability. Although an absent anterior cruciate ligament (ACL) with a positive Lachman test result is observed frequently, clinical signs of instability are rare, and nonoperative management is appropriate.16 In mild cases, ankle valgus may be managed with a University of California-Berkeley (UCB) orthosis, but as with limb-length discrepancy, the patient must be monitored throughout his or her growth because the fibular portion of the mortise may be progressively compromised. Surgical therapySeveral issues must be addressed before any procedure is performed for postaxial hypoplasia of the lower extremity (fibular hemimelia). The ultimate goal is to achieve symmetrical, stable, and well-aligned joints with the minimal number of surgical procedures. No single set of operations should always be performed; instead, individual procedures should be planned that address the specific abnormalities in each patient. Finally, realistic expectations of the timing, the duration of recovery, and the ultimate outcome must be communicated to the patient and to his or her family. In patients with a nonfunctional foot, Birch et al recommend amputation, regardless of limb-length discrepancy, unless the upper extremities also are nonfunctional.17 In patients with a functional foot, the surgical recommendations generally fall into 1 of 3 groups:
If amputation is determined to be the most appropriate procedure for an individual, the Syme amputation is generally used. In the past, transtibial amputation was performed more commonly because of cosmetic concerns for a bulky ankle. However, subsequent observations showed that the ankle does not enlarge with growth after the Syme amputation, and that the procedure allows weight bearing on the residual limb. Boyd described a modification to the Syme amputation in which the talus is removed, but the retained calcaneus is fused to the tibia to help prevent posterior migration of the heel pad.18, 19 In this modification, the heel pad grows with the patient. However, the procedure is associated with more wound problems, nonunion, and malpositioning of the calcaneus. Thus, the unmodified Syme amputation is generally recommended.20 When a Syme amputation is performed in children, trimming the condyles is not necessary. As opposed to adults, children have small condyles that do not grow to a normal size. For patients with hip dysplasia, PFFD, and/or coxa vara, please refer to Developmental Dysplasia of the Hip, Proximal Femoral Focal Deficiency, and Congenital Coxa Vara for further details on the various treatment procedures. Several issues should be noted, however. Any necessary operations for acetabular redirection are generally performed before femoral lengthening. Also, in the setting of combined coxa vara and limb-length discrepancy, lengthening via callotasis at the subtrochanteric level is not recommended because of the bending moment and the small cross-sectional area in that portion of the femur. Instead, a more standard valgus intertrochanteric osteotomy should be performed with any necessary lengthening performed separately at the distal femur. Genu valgum associated with postaxial hypoplasia of the lower extremity is progressive, and it can adversely affect alignment of the lower limb. This can be treated in several ways. Acute correction can be obtained by means of a distal femur corticotomy during a femoral lengthening procedure or by means of an osteotomy during correction of anteromedial tibial bowing. In patients with a hypoplastic lateral femoral condyle, temporary medial epiphyseal stapling has been recommended because osteotomy has a high recurrence rate unless it is performed near maturity. Ankle abnormalities can range from complete absence of the fibula to ankle valgus and/or a ball-and-socket ankle.21 For the more severe deformities, a Gruca reconstruction has been described.22 This procedure creates a lateral malleolus by using an oblique sliding osteotomy of the distal tibia. In milder cases of fibular hypoplasia and possible valgus, a supramalleolar osteotomy is traditionally used. As a less-invasive alternative, a medial malleolar screw epiphysiodesis may provide good results, as Stevens described.23 Procedures in the foot include resection of talar coalitions or fusions and addressing any problems with shoe fit that might arise for any deformity. Specific details of these procedures are discussed in other articles. Preoperative detailsAs mentioned above, the most important part of preoperative planning is thorough evaluation of the entire limb to identify all of the associated abnormalities that may be present as a part of fibular hemimelia. The mechanical and anatomic axes should be determined and corrected when possible. An overall plan is important, and should be discussed in detail with the patient and his or her family. Postoperative detailsPostoperative care for postaxial hypoplasia of the lower extremity (fibular hemimelia) depends on the specific procedures performed. Follow-upBecause the abnormalities associated with postaxial hypoplasia of the lower extremity (fibular hemimelia) tend to be relative as opposed to absolute, the patient should continue to be monitored through maturity to ensure that no additional interventions are necessary. COMPLICATIONSSection 8 of 12
Postaxial hypoplasia of the lower extremity (fibular hemimelia) is a syndrome that involves structures throughout a large anatomic area, and complications of treatment are not infrequent. In addition to the standard surgical complications (eg, infection, bleeding), several complications specific to this disorder have been described. In the hip, the Hilgenreiner epiphyseal angle must be corrected to less than 38° from the horizontal; repeat valgus intertrochanteric osteotomies may be needed.24 Limb lengthening has a range of complications, from the frequent superficial infections along the pin tract to more significant problems related to fracture, tightening of soft tissues, stiffness, and recurrent deformity. Stapling is an effective method for correcting angular deformities, but staple displacement and/or rebound growth may occur. However, in some situations, stapling may be preferable to an osteotomy because of the increased morbidity rate and because of the possibility of nonunion and recurrence after an osteotomy procedure. Finally, amputation may ultimately be necessary despite limb-sparing treatment, a possibility that must be discussed with the parents from the beginning. OUTCOME AND PROGNOSISSection 9 of 12
Because postaxial hypoplasia of the lower extremity (fibular hemimelia) represents such a wide range of abnormalities with varying degrees of involvement, no simple statement can be made regarding the patient's prognosis. Judiciously chosen, well-timed procedures specifically tailored to the individual patient provide the best prospects for a well-aligned, functional limb of adequate length. FUTURE AND CONTROVERSIESSection 10 of 12
One controversy regarding postaxial hypoplasia of the lower extremity (fibular hemimelia) is its name. Historically, it has been called fibular aplasia or hypoplasia. This name has been defended largely because of historical precedent. However, as more insights have been gained into the constellation of related abnormalities stemming from the embryological limb bud, postaxial hypoplasia of the lower extremity may describe the syndrome more accurately. It also helps remind the clinician to look for other subtle abnormalities and not focus on only the obvious fibular deficiency. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
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