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03/23/2018

Research Article

Simultaneous Acute FemoralDeformity Correction and GradualLimb Lengthening Using aRetrograde Femoral Nail:Technique and Clinical Results

Abstract

Introduction: Patients with limb-length discrepancies often haveconcomitant deformity. We describe the outcomes of acute, fixator-assisted deformity correction with gradual lengthening using theretrograde femoral Precice nail (NuVasive).Methods: We analyzed a retrospective series of 27 patients in whoman external fixator was combinedwith a Precice nail to correct angularor rotational deformity and limb-length discrepancy. The fixator wasapplied temporarily to restore normal alignment. The Precice nail wasinserted and locked in place to hold the correction, with gradualrestoration of limb length.Results: The27patients (meanage,28years) hadamean follow-upof13 months. Secondary deformities were mainly valgus (15 patients)andvarus (10patients).Postoperatively, 93%ofpatientshadcorrectionof limb length to within 3 mm of the discrepancy (mean lengthening, 30mm).Mechanical axis deviationwas corrected towithin 8mmof neutral(ie, zero) in 81%of patients. Themechanical lateral distal femoral anglewas corrected to a mean of 88! postoperatively. Final Association forthe Study and Application of Methods of Ilizarov (ASAMI)–Paleyscores were excellent for 96% of patients.Discussion: The use of intramedullary lengthening nails hasrevolutionized the field of limb lengthening. The results of our study showthat a retrograde femoral Precice nail can be used safely and accuratelyto correct both limb-length discrepancy and deformity with minimalcomplications. The benefits of using this implant include the ability tomaintain knee range of motion during the lengthening process. Rapidbone healing allows a relatively fast return toweight-bearing ambulation.Conclusions: The Precice nail was effectively used to correct bothlimb-length discrepancy and deformity, with excellent overalloutcomes. This surgical technique may help avoid the complicationsthat can occur with prolonged postoperative use of an external fixator.Level of Evidence: Level IV retrospective study

Patients with unequal femorallengths often have concomitant

deformity in the coronal, sagittal, or

axial plane. External fixation haslong been the standard for simulta-neous surgical correction of leg

Christopher A. Iobst, MD

S. Robert Rozbruch, MD

Scott Nelson, MD

Austin Fragomen, MD

From the Department of OrthopedicSurgery, Nationwide Children’sHospital, Columbus, OH (Dr. Iobst),the Hospital for Special Surgery, WeillCornell Medical College of CornellUniversity, New York, NY(Dr. Rozbruch and Dr. Fragomen),and the Department of OrthopaedicSurgery, Loma Linda University,Loma Linda, CA (Dr. Nelson).

Correspondence to Dr. Iobst:[email protected]

J Am Acad Orthop Surg 2018;26:241-250

DOI: 10.5435/JAAOS-D-16-00573

Copyright 2018 by the AmericanAcademy of Orthopaedic Surgeons.

April 1, 2018, Vol 26, No 7 241

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited.

length discrepancy and deformity.1-4

Despite the success and versatility ofthis method, it has drawbacks.External fixation is cumbersome andcan be uncomfortable for patients.The experience may be psychologi-cally difficult for the patient andfamily. Pin-track infections canoccur.5 To manage these infections,many patients require oral antibi-otics, which increase the possibilityof antimicrobial resistance andexpose patients to adverse effects,such as gastrointestinal dysfunctionand allergic reactions. Because of thepain associated with external fixa-tion, prolonged courses of narcoticsmay be required, leading to associ-ated problems. Transfixion of thesoft-tissue envelope by half pins andwires makes it more difficult for thepatient to maintain range of motion(ROM) during treatment.6

Intramedullary (IM) lengtheningnails can be used as an alternative toexternal fixation in patients with limb-lengthdiscrepancies.7-9 However, thesedevices do not have the capacity toperform additional deformity correc-tion. Fixator-assisted nailing and plat-ing techniques have been developed tohelp make acute osteotomy correctionsmore accurate.10-13 A temporaryexternal fixator is used intraoperativelyto adjust the alignment until the desiredcorrection is obtained. A plate or rod isthen inserted to maintain the correc-tion, and the external fixator isremoved. Previous studies have dem-onstrated that this method can suc-cessfully correct deformities and restorelimb alignment without the need forpostoperative external fixation.10-13

Alternatively, the surgeon can use theIM lengthening nail to maintain in-

traoperative, fixator-assisted, acutecorrection of the limb alignment andthen gradually correct the limb-lengthdiscrepancy postoperatively. One con-cern, however, is that the gapping andloss of bone contact that occurs at theacute osteotomy site has a detrimentaleffect on the subsequent formation ofregenerate bone.This study presents the results of

simultaneous deformity correctionand lengthening using a retrogradefemoral Precice nail (NuVasive). Theaim of the study was to demonstratethe efficacy of the Precice nail in limblengthening and deformity correc-tion. Outcome measures includedfinal alignment, limb length, consol-idation index, and knee motion.

Methods

Design and CohortThis study was a multicenter retro-spective case series. InstitutionalReview Board approval was obtainedat each institution (ie, NemoursChildren’s Hospital, Hospital forSpecial Surgery, and Loma LindaUniversity). All 27 patients underwentsimultaneous fixator-assisted acutedeformity correction and insertion of aretrograde femoral Precice nail.At the time of surgery, the patients

had a mean age of 28 6 13.9 years(range, 13 to 57 years) and a meanbody mass index (BMI) of 27.36 6.9(range, 16.6 to 43.0). The mean LimbLengthening and ReconstructionSociety (LLRS) AIM score was 4.6 62.3 (range, 1 to 11). (The LLRS AIMscore is a classification system used tostandardize the complexity of theprocedures.) All patients had a limb-

length discrepancy and secondarydeformities, specifically valgus (15patients), varus (10 patients), externalrotation (1 patient), and apex anterior(1 patient) deformities.

IndicationsTreatment with an IM lengtheningnail can be considered for any patientwith a limb-length deficiency thatcan be managed with long bone dis-traction osteogenesis. Juxta-articulardeformity requires substantial trans-lation at a metaphyseal osteotomysite and is difficult to control with anIM nail. Therefore, this technique isbest suited for deformity in thediaphyseal or metadiaphyseal area.

ContraindicationsAnarrowdiaphyseal canal diameter isa relative contraindication to defor-mity correction and limb lengtheningusing a retrograde femoral nail. Thecanal must be able to accommodate a10.5-mm reamer for an 8.5-mm nail.Ideally, a larger nail can be used. A5-mmthickness of cortexmust remaincircumferentially after reaming toreduce the risk of fracture.A high body mass index is a relative

contraindication to simultaneousdeformity correction and lengtheningusing a retrograde femoral Precice nailbecause the thickness of the patient’sthigh will affect the external magneticsignal. For an 8.5-mm nail, a distanceof .38 mm between the IM length-ening nail and the skin surface willpreclude the use of the nail. For a 10.7-mm diameter nail, the requisite dis-tance is ,51 mm. Because post-operative weight-bearing restrictionsare necessary, the inability to comply

Dr. Iobst or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of Smith & Nephewand serves as a paid consultant to NuVasive and Orthofix. Dr. Rozbruch or an immediate family member has received royalties from Stryker;is a member of a speakers’ bureau or has made paid presentations on behalf of and serves as a paid consultant to NuVasive, Smith &Nephew, and Stryker; and serves as a board member, owner, officer, or committee member of the Limb Lengthening and ReconstructionSociety. Dr. Nelson or an immediate family member serves as a paid consultant to NuVasive and Orthofix. Dr. Fragomen or an immediatefamily member has received royalties from Stryker; is a member of a speakers’ bureau or has made paid presentations on behalf ofNuVasive and Smith & Nephew; serves as a paid consultant to DePuy Synthes, NuVasive, and Smith & Nephew; and serves as a boardmember, owner, officer, or committee member of the Limb Lengthening and Reconstruction Society.

Simultaneous Acute Femoral Deformity Correction and Gradual Limb Lengthening

242 Journal of the American Academy of Orthopaedic Surgeons


with partial weight bearing is a con-traindication. Osteopenia is anothercontraindication; in patients with poorbone quality, the locking screws mayloosen and back out of the nail.Alternatively, the bone may deformaround the loose screws duringlengthening.Any active infection in the bone to

be lengthened is a contraindication tothe procedure. Patients who haveundergone successful treatment forprior infections should be considered

high risk, although the procedure isnot contraindicated in these patients.Patients who have had previousexternal fixation with possible historyof pin-track infections are consideredto be at moderate risk for deep infec-tion of the IM lengthening nail.Finally, an open physis is a concern.Placing an IM lengthening nail acrossan open physis is a high-risk endeavorthat should be approached with cau-tion and requires substantial expertiseto avoid physeal closure.

Preoperative Planning andSurgical TechniqueFour surgeons (C.A.I., S.R.R., S.N.,A.F.) performed the procedure usinga similar method for preoperativeplanning and the surgical technique.Preoperatively, an AP standingradiograph of the lower extremitieswas obtained (Figure 1, A). Themechanical axes of the proximal anddistal femur were measured (Figure1, B). The surgeons selected an os-teotomy site that would not be too

Figure 1

AP standing radiographs of the lower extremities demonstrating deformity correction in a 14-year-old girl with 14! of distalfemoral varus and a 24-mm limb-length discrepancy after a traumatic, partial distal femoral physeal arrest. A, AP standingradiograph of the lower extremities prior to measurement of the mechanical axes. B, The mechanical axes are measured toassess the amount and location of the deformity. The long, black lines represent the mechanical axes of the proximal and distalfemur. The intersection of these lines is near the knee joint and represents the apex of the deformity. The short line representsthe anatomic axis of the proximal femoral segment.C, The proposed osteotomy site (transverse black line) must be far enoughaway from the joint that the intramedullary nail will be able to control the distal fragment. This osteotomy site will requiretranslation because it will be distal to the apex of the deformity.D, Themagnitude of the deformity and the necessary translationwere transferred into an anatomic axis planning model. Because the intramedullary nail needs to occupy the canal proximally,all of the varus must be corrected in the distal fragment. The black lines represent the path of the intramedullary nail that will berequired to fully correct the deformity. They must be collinear after the nail insertion, which will require substantial translation.

Christopher A. Iobst, MD, et al

April 1, 2018, Vol 26, No 7 243


distal to allow the IM lengtheningnail to control the distal fragment(Figure 1, C). The magnitude of de-formity and the necessary translationwere transferred into an anatomicaxis planning model (Figure 1, D).The planned lengthening was anaverage of 3 cm, which would havea minimal effect on the mechanicalaxis. Thus, special consideration wasnot given to correcting this expectedmild valgus deformity. For patientswho require a lengthening .3 cm,the surgeon must consider the effectthat lengthening along the anatomicaxis can have on the mechanical axis.Intraoperatively, thekneewaskept in

approximately40! of flexion. Througha percutaneous incision, multiple drillholes were made at the distal femoralosteotomy site. The osteotomy wasmade $5 cm proximal to the distalend of the nail because of the patternof the locking screw used with thePrecice nail. The osteotomy site shouldbe as close to the apex of the deformityas possible. The anatomy and thequality of the soft tissue and bone mayinfluence the location of the osteot-omy. When the osteotomy level didnot match the apex of the deformity,translation of the distal femoral frag-ment was performed to maintain themechanical axis of the limb.

A half pin was placed perpendicu-lar to the distal femoral mechanicalaxis and either anterior or posteriorto the planned path of the nail. Forextra precision, a guidewire may beinserted initially anterior or posteriorto the proposed path of the nail. Oncethe guidewire position is found to besatisfactory, a cannulated drill maybe used to prepare a path to ensureexact placement of the half pin and toavoid the IM canal. If necessary, asecond half pin can be added in thedistal segment. A single half pin wasplaced perpendicular to the mechan-ical axis of the femur proximal to theplanned ending point of the nail(Figure 2). Placement of the pinperpendicular to the mechanical axisrather than to the anatomic axis ofthe femur allowed the lengthening tooccur along the mechanical axis ofthe femur. This method helped toprevent inadvertent valgus defor-mity, which can result when length-ening occurs along the anatomicaxis.14 The percutaneous osteotomywas completed with the use of a thin,sharp osteotome. To avoid thermalnecrosis of the bone, a sagittal sawwas not used. Acute correction of thedeformity was performed. Theamount of correction was adjustedwith the fixator half pins until the

mechanical axis was adequatelycorrected. The correction was con-firmed with the use of either theelectrocautery cord technique (place-ment of a tightly stretched cord overthe center of the hip and the ankle) ora radiopaque straight-line grid placedunder the patient on the operatingtable. After the desired alignment wasachieved, the fixator pins were con-nected with a bar and locked in place(Figure 3).If control of the flexion/extension

of the segment was a concern, or if asagittal plane correction was neces-sary, a second fixator was mountedanteriorly (Figure 4). These half pinswere placed perpendicular to thefemur at their respective levels in ananterior-to-posterior direction. Thedistal half pin was placed medial orlateral to the path of the nail, and theproximal half pin was placed prox-imal to the planned nail endingpoint. Alternatively, a single distalhalf pin was inserted and incorpo-rated into the external fixator (Fig-ure 5). A guidewire was inserted intothe distal femur such that theguidewire was visible in the center ofthe femur on the sagittal fluoro-scopic view and aiming toward thecenter of the proximal femoral canalon the AP fluoroscopic view. In

Figure 2

Intraoperative photograph of a thighdemonstrating the placement of halfpins distal and proximal to theproposed osteotomy site. Theincision for the percutaneousosteotomy is visible on the distalanterolateral thigh.

Figure 3

Intraoperative photograph of a thighdemonstrating maintenance of theacute correction with the use of afixator mounted posterior to theplanned path of the nail. A ball-tippedguidewire is visible entering the distalfemur.

Figure 4

Intraoperative photograph of a thighdemonstrating anterior mounting of asecond external fixator. The secondfixator controls the flexion/extensionof the segment and can be used if asagittal plane correction is necessary.




patients with a varus deformity, aslightly medial entry point in thetrochlear notch was used to allowmore angulation of the distal frag-ment. In patients with a valgusdeformity, a slightly lateral entrypoint was used.An entry reamerwas placed over the

guidewire and advanced into the distalfemoral canal to the appropriatedepth. With the entry reamer in place,blocking screws were placed to guidethe path of the subsequent flexiblereamers. The anterior-to-posteriorblocking screws were placed on theconcave side of the deformity as closeto the entry reamer as possible. Thelateral-to-medial blocking screw wasplacedposterior to thenail and close tothe entry reamer. A cannulated drillover a guidewire was used to place thescrew in an exact location. The drill bitwas left in place during the reaming ofthe femur, and the screw was insertedat the end of the procedure. Alterna-tively, a 5-mm half pin was insertedand left in place during the reaming. A5.5-mm screw could then be placed inthe half pin hole at the end of theprocedure. The entry reamer wasremoved, and a ball-tipped guidewirewas inserted into the femoral canaland passed across the osteotomy siteinto the proximal femur. Sequentialreaming of the femur was performedwith flexible or rigid reamers over theball-tipped guidewire. The canal wasreamed to approximately 2 mm largerthan the size of the Precice nail to beinserted.The Precice nail was inserted care-

fully without force. Additional ream-ing was performed when necessary.The Precice nail comes in two types: astraight nail and anailwith a10! distalbend. In patients with sagittal planedeformity, the nail with the 10! bendcan be used to help obtain correction.The distal and proximal interlockingpegs were inserted into the nail. Thedrill bit or half pins used for blockingduring the reaming were replaced witha 5.0- or 5.5-mm screw (Figure 6). The

temporary external fixator wasremoved.Postoperatively, patients were al-

lowed 50- or 70-lb weight bearingdepending on their nail diameter (10.7or 12.5 mm, respectively). Venousthromboembolic prophylaxis was ini-tiated on postoperative day 2 in adultpatients. Patients’ medications varieddepending on the postoperative pro-tocol at each medical center. Medi-cations included aspirin, rivaroxaban,and enoxaparin. Because this studywas retrospective, we did not controlfor the choice of venous thrombo-embolic prophylaxis. Lengtheningadjustments began after 4 to 7 days ata rate of 0.99 to 1.0 mm per day.Adjustments were performed fourtimes daily in 0.25-mm increments orthree times daily in 0.33-mm incre-ments. Patients were seen for follow-up every 1 to 2 weeks, at which timeradiographs were obtained and rateadjustments were initiated.

Data CollectionStudy data were recorded usingREDCap (Research Electronic DataCapture),15 which is a secure, web-based application that is designed tosupport data capture for researchstudies, providing an intuitive inter-face for validated data entry, audittrails for tracking data manipulationand export procedures, automated

export procedures for seamless datadownloads to common statisticalpackages, and procedures for im-porting data from external sources.Preoperative demographic data,LLRS AIM scores, and relevant ana-tomic angles of the lower extremitywere recorded.16 Pertinent surgicaldata that were recorded included thePrecice nail diameter and length,the length of surgery, and surgicalblood loss. Postoperative outcomesincluded final corrected anatomicangles, including the mechanical axisdeviation (MAD), mechanical lateraldistal femoral angle (LDFA), poste-rior distal femoral angle (PDFA), andlimb-length discrepancy; knee ROM;the amount of lengthening obtained;

Figure 5

Intraoperative photograph of the legdemonstrating an alternative methodto control the sagittal plane of thedistal segment using one anterior-to-posterior half pin incorporated intothe fixator.

Figure 6

Intraoperative lateral fluoroscopicimage of the distal femurdemonstrating the open physis andtypical placement of blocking screws inthe coronal and sagittal planes tomaintain the correction during thelengthening process in an adolescentpatient. The authors have observedthat physeal closure will not occur if thenail remains across the physis. If thenail is removed, a physeal bar willform. An end cap can be added later toprevent excessive involution of the nail(with growth) past the physis in ayounger child.


April 1, 2018, Vol 26, No 7 245


the percentage of desired lengtheningachieved; the percentage of pre-operative bone length gained; thenumber of lengthening days; therate of lengthening; the rhythm oflengthening; the time to full weightbearing; the time to full consolida-tion; a bone-healing index; and theAssociation for the Study andApplication of Methods of Ilizarov(ASAMI)–Paley score,17 whichassesses return to function after sur-gery. Although it has not been vali-dated, the ASAMI–Paley score hasbeen used as an outcome measure formany years in the field of limbdeformity correction. It was used inthis study as a postoperative measureof success or failure. This score con-sists of a subjective pain/functionoutcome score and an objective bonescore. An excellent score is achievedwith full healing at the osteotomy siteand a minimal residual limb-lengthdiscrepancy. A good score denotespersistent angular deformity or limbshortening despite surgical correc-tion. In addition to postoperativeassessment, patients were observedfor postoperative complications.

Statistical AnalysesDescriptive statistics were calculatedasmean6 SD. The preoperative andpostoperative measurements werecompared with standard values fornormal limb alignment: LDFA, 88!;PDFA, 83!; and MAD, ,10 mmmedial to the center of the kneejoint.18 Comparisons were madeusing pairwise two-tailed unpairedStudent t-tests or one-sample Studentt-tests, with P , 0.05 definingstatistical significance. Statisticalanalyses were performed using In-stat (GraphPad Software).

Results

Preoperatively, the mean LLRS AIMscore was 4.66 2.3 (range, 1 to 11).All patients had a limb-length dis-

crepancy and secondary deformities,including valgus deformity (15 pa-tients), varus deformity (10 patients),and external rotation (1 patient) andapex anterior (1 patient) deformities.The mean preoperative MAD was22.1 6 12.6 mm. The mean limb-length discrepancy was 30.9 612.9 mm. With 88! considered as thenormal LDFA, the patients had anaverage 7.6! of deformity pre-operatively (maximum, 15!). Themean deviation from 88! was sta-tistically significant for patients withvarus or valgus deformity (P =0.0004 and P , 0.0001, respec-tively; one-sample Student t-tests).The PDFA was an average of82.1! 6 7.2! preoperatively. Pre-operatively, the average knee exten-sion was 2! short of full extension(two patients had 10! less than fullextension, and two patients had 20!less than full extension). Knee flex-ion was an average of 127! 6 23.1!preoperatively (four patients had,130! of knee flexion). The averagepreoperative knee arc of motion was125! 6 22.5!.The external fixator construct

consisted of one half pin in each seg-ment for 22 patients (81%) and twodistal half pins with one proximalhalf pin in 5 patients (19%). Twelvepatients had 5-mm half pins placed,and 15 patients had 6-mm half pins.The average number of blockingscrews (5.0 or 5.5 mm) placed perpatient was 1.3 screws (range, 0 to 3screws).The latency period to limb length-

ening averaged 5 days (range, 4 to 10days). The mean postoperative limb-length discrepancy was 0.8 mm, with25 of 27 patients (93%) corrected towithin3mm.Twopatients had6-mmresidual limb-length discrepancies.The average lengthening was 30 mm.The mean postoperative MAD was6.16 4.4 mm, with 22 of 27 patients(81%) corrected to within 8 mm ofneutral (ie, zero). The LDFA wascorrected to a mean of 88! post-

operatively. The mean postoperativeLDFA values for the varus and val-gus groups were not substantiallydifferent from 88! using one-sampleStudent t-tests. The mean post-operative PDFA was 88.4! 6 3.0!.The mean acute angular correctionperformed was 7!, with a maximumof 15!. Mean follow-up was 12.9 65.2 months (range, 7 to 29 months).The mean consolidation index was42 days/cm.Postoperatively, knee extension

was 0.6! 6 1.6!, with all patientswithin 5! of full extension. The meanknee flexion was 124! 6 21.7!.Flexion measured ,130! in 10patients (37%). The mean post-operative knee arc of motion was123! 6 21.5!. The mean time to fullweight bearing was 89 6 33.7 days(range, 48 to 184 days). ASAMI–Paley scores were excellent for 26patients (96%) and good for onepatient. No patients had any infec-tions, fractures, implant mechanicalfailures, or implant breakage. Nopatients had insufficient regeneratebone formation.Complications developed in four

patients (15%). One patient, who hadchronic pain, required a slow length-ening rate that led to premature con-solidation. Posterior tibial subluxationdeveloped in one patient, requiringrevision surgery. This patient had fib-ular hemimelia with a preoperativevalgus deformity and an anterior cru-ciate ligament–deficient knee. Thepatient was undergoing simultaneousfemoral and tibial lengthening. Thesubluxation resolved after excision ofthe fascia lata combined with ham-string and gastrocnemius-soleus com-plex lengthening. One patient requiredarthroscopic lysis of adhesions toimprove knee flexion. In the otherpatient, a flexion deformity (malunion)developed during lengthening. Thispatient required an extension osteot-omy of the distal femur with plating tocorrect this residual sagittal planedeformity. This patient’s index surgery




was the first retrograde procedureperformed, and the correct use ofblocking screws was not implemented.The preoperative characteristics of

patients with valgus and varusdeformitywere similar (Table 1). Thepatients with valgus deformity hadslightly better angular correctionpostoperatively, although all patientswith varus deformity achieved thedesired lengthening and had excellentASAMI–Paley scores (Table 2). Threeof 15 patients in the valgus grouprequired secondary surgery; however,the proportion of patients in thisgroup who required secondary sur-gery was not statistically significantlydifferent from that of the varus group(0 of 10 patients; P = 0.25) (Fisherexact test).Because the goal was correction of

the MAD to ,10 mm medially, aseparate analysis of the five patientswho had a final MAD of $10 mmwas performed. Compared with the22 patients with MAD of ,10 mm,patients with a final MAD of$10 mm had no substantial differ-ences in outcomes. Of the 12 patientswhose deformity was corrected in-traoperatively with 5-mm half pins,4 patients had final correction with aMAD$10 mm, compared with only1 of 15 patients in whom 6-mm halfpins were used. Of the 17 patients inwhom no blocking screws were usedor one blocking screw was used, 4patients (24%) had a final MAD of$10 mm. Only 1 of the 10 patientsin whom two or more blockingscrews were used had a final MAD$10 mm. One of the two patientswith an 8.5-mm nail and 3 of the 15patients with a 10.7-mm nail had afinal MAD of $10 mm. Only 1 ofthe 10 patients with a 12.5-mm nailhad a final MAD of $10 mm.Among the five patients with MADof $10 mm, three short-length nails(215 mm, 230 mm, and 230 mm)and two long-length nails (330 mmand 355 mm) were used. Thus, thenail length did not seem to affect the

outcome. The average time to fullweight bearing in the five patientswith MAD of $10 mm was 79 days,compared with 92 days for the other22 patients.

Discussion

The use of IM lengthening nails,such as the Precice nail, has revolu-tionized the field of limb lengthen-ing.7-9,19-21 Instead of requiringmonths of postoperative externalfixation, patients can now undergolimb lengthening with a completelyinternal device. Patients who

undergo IM limb lengthening haveless pain, maintain better ROM,and experience fewer infectionscompared with patients whoundergo lengthening with externalfixation.22 Fixator-assisted nailingand plating techniques have beendeveloped to allow surgeons tocorrect deformity with the use ofinternal implants only.10-13 Inthese techniques, the external fix-ator is applied temporarily in theoperating room to obtain thedesired limb deformity correction,and then the internal hardware(nail or plate) is inserted to main-tain the correction.

Table 1

Preoperative Characteristics of Patients With Valgus or Varus Deformitya

PreoperativeCharacteristics

Patients With ValgusDeformity (n = 15)

Patients With VarusDeformity (n = 10)

Mechanical lateral distalfemoral angle (degrees)

81.56 3.4 96.76 5.0

Limb-length discrepancy(mm)

31.36 10.4 30.36 17.0

Mechanical axis deviation(mm)

23.76 11.0 24.16 12.5

Limb Lengthening andReconstruction SocietyAIM index

4.066 1.8 4.7 6 2.3

a Values are mean 6 SD.

Table 2

Postoperative Characteristics of Patients With Valgus or Varus Deformitya

Postoperative Characteristics

Patients WithValgus Deformity

(n = 15)

Patients WithVarus Deformity

(n = 10)

Mechanical axis deviation (mm) 5.4 6 4.4 6.9 6 4.8Mechanical lateral distal femoralangle (degrees)

87.36 2.0 90.1 6 3.7

Mean percentage of desiredlength attained

99.1 100

Percentage of patients achievingexcellent ASAMI–Paley scores

93 100

No. of blocking screws used 1.3 6 0.8 1.4 6 1.3No. of patients requiring secondarysurgery

3 (20%) None

ASAMI = Association for the Study and Application of Methods of Ilizarova Values are mean 6 SD except as noted.


April 1, 2018, Vol 26, No 7 247


Baumgart23 previously describedfemoral deformity correction withthe use of the “reverse planning”method. In this technique, a series ofpreoperative templates is drawn toplan the surgery. As an alternativemethod, the fixator-assisted nailingtechnique can be used. The results ofour study show that the retrogradefemoral Precice nail can be usedsafely and accurately to correct bothlimb-length discrepancy and defor-mity with minimal risk of compli-cations (Figures 6 to 8). On the basisof the final ASAMI–Paley scores,96% of the patients had an excellentoutcome. To our knowledge, thisseries represents the largest reportednumber of procedures performedusing this technique. In our study,the average preoperative limb-length

discrepancy was 31 mm. All patientshad successful correction to leglengths within normal limits(,10 mm final discrepancy). Thefinal average limb-length discrep-ancy was 0.8 mm. Lengthening was

achieved in every patient to within6 mm of residual discrepancy, and93% of the patients achieved cor-rection to within 3 mm. This result issimilar to the findings in a previousstudy, in which the lengtheningachieved with the Precice nail wasfound to be 96% accurate.20 Nodevice failure or breakage occurredduring the lengthening process.The ability to maintain knee ROM

during the lengthening process is oneof the major advantages of IM limblengthening.21 Our series reinforcesthis concept. After an average of30 mm of lengthening, the averagefunctional knee arc of motion was123!, which is not markedly differ-ent from the preoperative arc ofmotion (125!). This outcome mayhave been influenced by the empha-sis on daily ROM exercises duringthe postoperative rehabilitation. Theexcellent results demonstrate theadvantage of postoperative physicaltherapy that is not hindered by thepresence of an external fixator. Incontrast, external fixation is associatedwith a reduction in final knee flexionand a need for quadricepsplasty.24

In addition, bone healing after IMlimb lengthening progressed rapidly,allowing patients to return to fullweight bearing without assistivedevices at an average of 89 days afterundergoing 3 cm of lengthening. Thisrelatively fast return to ambulation isprobably related to two factors. First,because the nail is an IM device, itprotects the regenerate bone fromdeformation during the healing pro-cess. Second, the smooth axial dis-traction produced by the Precice nailcreates excellent regenerate bonedespite a loss of bone contact at theinitiation of distraction. Unlikemechanically actuated IM naildesigns,25,26 the Precice nail doesnot require twisting of the regen-erate bone as it distracts. Becauseof its design, the Precice naillengthens along the axial planewith pure distraction. No patient

Figure 7

Intraoperative AP fluoroscopic imageof the distal femur demonstratingappropriate translation andangulation after acute correction ofthe patient’s deformity. Note theplacement of a blocking screw on theconcave side of the deformity(medial to the nail).

Figure 8

Postoperative AP standingradiograph of the lower extremitiesdemonstrating restoration of themechanical axis and leg lengths afterfixator-assisted femoral nailing with aretrograde Precice nail (NuVasive).The mechanical axis (white line) isslightly medial and well within normalparameters.




required bone grafting, bone mar-row aspirate injection, bone stim-ulators, or any other type ofaugmentation to achieve full heal-ing of the regenerate bone. Healingprogressed so well that one adultpatient had premature consolida-tion. The low incidence of delayedunion (none of 27 patients) is lessthan that observed during a studyof lengthening over a nail withoutdeformity correction (the standardfor lengthening before the adventof the Precice nail), which was 1 of22 patients (5%).24 Higher rates ofdelayed union with the Precice nailhave been reported in patientsrequiring tibial lengthening20 andin patients with congenital femoraldeficiency,27 neither of which wereincluded in this study. Otherstudies of the use of retrogradefemoral IM lengthening nails withacute deformity correction havereported rapid healing with lowconsolidation indices.28,29

These prior studies all involved theuse of a percutaneous osteotomywith minimal periosteal stripping.The osteotomy is predrilled, and thenreaming is performed. This techniqueensures deposition of the reamings atthe lengthening site, which may con-tribute to healing. However, the riskof unwanted consolidation is higher.In our experience, an initial acceler-ated rate of distraction (4-day latencyand 1.32 mm/d for 4 days) is recom-mended to avoid this complication.The acute deformity correction didnot affect the ability to form robustregenerate bone. Although the maxi-mum deformity corrected in thisseries was 15!, other series haveshown that up to 20! of deformitycan be corrected with this tech-nique.8,27-32

The fixator-assisted technique usedin our study allowed a correction ofthemeanMAD from24mm to6mm,with 81% of patients having finalalignment restored to normal (MAD,10mm). This result is similar to the

accuracy of external fixation–mediated correction of femoralvarus and valgus deformity, whichhas been reported to yield correctionof theMAD to within 10 mm in 85%of patients.13 This finding includesprocedures in which a postoperativeadjustment of the external fixatorwas used to fine-tune the correction.The subgroup of five patientswith a

final MAD of.10 mm did not haveworse preoperative deformity, worseLLRS AIM scores, or longer surgicaltimes than did other patients. Thesize of the half pins used in thetemporary external fixator constructand the number of blocking screwsused may have influenced the out-come. Four of these patients had5-mm half pins. These smaller-diameter pins may not have beenable to control the femoral segmentsas well as the stiffer 6-mm–diameterhalf pins could have. One blockingscrew or no blocking screws wereused in four patients in this sub-group, which highlights the impor-tance of the blocking screws andsuggests that at least two screws beinserted to obtain optimal alignment.The blocking screws serve a dualpurpose: They help to guide thereaming to create the ideal path forthe nail, and they help to maintainthe alignment in the femoral me-taphysis during the lengthening andconsolidation phases. Inserting a nailwith a larger diameter seemed toimprove the MAD outcome. Theaverage time to full weight bearingwas just 79 days, compared with 92days for the other 22 patients. Plac-ing full weight-bearing stress on theconstruct too early may cause a lossof alignment.This studyhas several limitations. It

is a retrospective, level IV study withthe inherent shortcomings of this typeof research. The series of patients isrelatively small, and larger studiesmust be performed to confirm ourfindings. This series represents theresults of procedures performed by

four different surgeons from threedifferent medical centers, and biasmay have occurred. Finally, the studydoes not include data regarding out-comes after nail removal. Becausethis nail contains a strongmagnet andhas internal machinery, removal ofthe nail after completion of thetreatment, typically 6 to 12 monthsafter insertion, is recommended. Theneed for this additional proceduremay cause increased morbidity thatwas not considered in this review.

Conclusion

This study confirms that deformitycorrection combined with graduallengthening using a retrograde fem-oral Precice nail can be performedsuccessfully. Acute correction of $15!is possible. Appropriately placedblocking screws are important toensure maintenance of the acute cor-rection. Close monitoring of the softtissues during the lengthening processis mandatory to prevent joint con-tracture or subluxation.

References

Evidence-based Medicine: Levels ofevidence are described in the table ofcontents. In this article, reference 5 isa level I study. References 6, 10, 22,26, 28, and 29 are level II studies.References 1-4, 8, 13, 16, 19, 24,and 30 are level III studies. Refer-ences 12, 17, 20, 23, 25, and 27 arelevel IV studies. References 7, 9, 11,and 14 are level V expert opinion.

References printed in bold type arethose published within the past 5years.

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