The Presence of Calcaneal FibularRemodeling Associated With Middle FacetTalocalcaneal Coalition: A RetrospectiveCT Review of 35 Feet. InvestigationsInvolving Middle Facet Coalitions—Part II

Klaus J. Kernbach, DPM,1 and Neal M. Blitz, DPM, FACFAS2

Middle facet talocalcaneal coalition is often associated with a rigid pes planovalgus. In the presence ofcalcaneal valgus, the fibula may come into contact with the lateral calcaneal wall during weight bearing,and develop a pseudoarticulation. Spurring, bone cysts, and other morphologic changes may concom-itantly occur at the calcaneus and fibula, suggesting a pathological degenerative process. This associ-ation has not been previously studied in middle facet tarsal coalition and we term the condition calcanealfibular remodeling, the focus of this investigation. To our knowledge, no study has specifically looked atthe abutment of the calcaneus and fibula as an additional area of pathology in patients treated operativelyfor tarsal coalition.Computerized axial tomography was retrospectively reviewed in 21 patients (35 feet) with symptomaticmiddle facet talocalcaneal coalition who were surgically treated for the coalition on at least 1 foot overa 12-year period. In 19 (54%) of the 35 feet, calcaneal fibular remodeling was identified and associatedwith concomitant coalition and pes planovalgus deformity. Fifteen (79%) of the 19 feet with calcanealfibular remodeling were managed surgically at the time of manuscript submission for middle facettalocalcaneal coalition. This new finding suggests that simple resection of the coalition may not fullyaddress the entire deformity and other combined surgical approaches may be more appropriate in theface of middle facet talocalcaneal coalition with heel valgus and calcaneal fibular remodeling. Level ofClinical Evidence: 4 (The Journal of Foot & Ankle Surgery 47(4):288–294, 2008)

Key Words: tarsal coalition, calcaneal fibular remodeling, pes planus, middle facet talocalcaneal coalition

Painful middle facet talocalcaneal coalition (TCC) is of-ten associated with a rigid pes planovalgus. Recent literaturehas questioned the source of the associated symptoms,which may be related to the coalition itself, or instead, to thepes planovalgus (1–4). Three separate investigators demon-strated that simple resection alone in the presence of heelvalgus resulted in poorer outcomes, suggesting that the

Address correspondence to Neal M. Blitz, DPM, FACFAS, ResearchDirector, Kaiser North Bay Consortium Residency Program, Departmentof Orthopedics and Foot & Ankle Surgery, Kaiser Permanente MedicalCenter, 401 Bicentennial Way, Santa Rosa, CA 95403. E-mail: nealblitz@yahoo.com.

1Resident Podiatric Surgeon, PGY-2, Department of Podiatry, KaiserFoundation Hospital, Vallejo, CA.

2Attending Podiatric Surgeon, Research Director Kaiser North BayConsortium Residency Program, Department of Orthopedics and Foot &Ankle Surgery, Kaiser Permanente Medical Center, Santa Rosa, CA.

Financial Disclosure: None reported.Conflict of Interest: None reported.Copyright © 2008 by the American College of Foot and Ankle Surgeons

1067-2516/08/4704-0006$34.00/0doi:10.1053/j.jfas.2008.04.004

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calcaneal valgus contributes to the painful condition (1, 2, 5).Moreover, single-stage middle facet coalition resectionscombined with flatfoot reconstruction demonstrated suc-cessful outcomes in a small series, further implicating thepes planovalgus as part of the pathological process (4, 6).

It is not entirely clear what aspects of the calcaneal valgusresult in pain when associated with middle facet coalition.Some investigators implicated an associated peroneal spasm(2, 7–10). Others have also advocated advanced imaging inan attempt to identify arthrosis in the rearfoot complex thatmay exist concurrently with the coalition (2, 4, 10–12). Toour knowledge, no study has specifically looked at theabutment of the calcaneus and fibula as an additional area ofpathology in coalition associated with flatfoot.

Depending on the severity of hindfoot valgus, the fibulaabuts against the fixed calcaneus and a pseudoarticulationmay develop (12). Spurring, cysts, and other morphologicchanges may concomitantly occur at the calcaneus andfibula, suggesting a pathological degenerative process (seeFigures 1–6). This association has not previously been

studied in tarsal coalition. We term the condition calcaneal

fibular remodeling (CFR), the focus of this investigation.The presence of CFR may contribute to the symptomsassociated with painful TCC, which may provide a clearerindication that simple resection of the coalition may notfully address the entire deformity and other combined sur-gical approaches may be more appropriate in the face ofTCC with heel valgus and CFR.

Materials and Methods

A retrospective review of 12 surgeons’ logs for patientswho had middle facet TCC identified on preoperative com-puterized axial tomography (CT), and treated by surgicalmanagement over a 12-year period was performed. Surgicalmanagement of the TCC was defined as operative interven-tion that may have included one of the following proce-

FIGURE 1 Bilateral severe CFR ina 51-year-old female with middlefacet TCC. Note severe calcanealvalgus, fibular and calcaneal cysts(black arrows), and morphologic“cup-like” changes representing apseudoarticulation between thecalcaneus and fibula (white arrow).

dures: simple resection of the coalition, rearfoot arthrodesis,

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or combined single-stage flatfoot reconstruction with mid-dle facet coalition resection. We identified 21 patients withpreoperative CT scans of middle facet TCC who had at leastone foot surgery for coalition management. If a patient wasfound to have bilateral middle facet TCC on CT, and only1 foot was operated on, then the contralateral nonsurgicallytreated foot was also included in this review. Thirty-five feetin 21 patients fulfilled these inclusion criteria.

In each patient, CT scans were obtained at the surgeon’sinstitution and reviewed by both authors electronically. AllCT scans used slice width between 1 and 4.5 mm with amean of 2.4 mm. The CT scans were evaluated for thepresence of middle facet TCC, as well as the presence ofmiddle facet TCC on the contralateral foot. Coalitions weredefined by significant joint irregularity (consistent with afibrous coalition) or trabecular bridging at the middle facet

(consistent with an osseous coalition) from the talus to the

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calcaneus. The presence of CFR was confirmed by using thesame CT scans used for coalition evaluation. In all in-stances, the identification of CFR was most easily identifiedon the coronal CT slices at or about the level of the middleand posterior facets of the subtalar joint. CFR was definedby the presence of a valgus heel coupled with at least 2 ofthe following 3 criteria: eburnation, subchondral cysts, ormorphologic changes in the calcaneus, fibula, or both. Thepresence of heel valgus was determined by evaluating tibialcalcaneal bisections on coronal CT scans. In all cases, CFRwas present only if there was concomitant heel valgus.

Results

The patient demographics, site clarification, CT data, andsurgical confirmations are reviewed in Table 1. Coronal CTscans depicting CFR are displayed in Figures 1 to 6. Twenty-one patients with 35 feet met the inclusion criteria. Elevenpatients (52.4%) were male and 10 (47.6%) were femalewith an average age of 20.2 years. There were 21 (60%) leftfeet and 14 (40%) right feet. Two thirds of the sample (14patients) had bilateral coalition identified. Seven patientshad unilateral coalition.

FIGURE 2 CFR with a fibrous middle facet TCC in a skeletallymature 14-year-old girl. Note the calcaneal cysts intimately associ-ated with eburnation and deformation in the calcaneus (whitearrow). Also, note that the middle facet orientation is roughly per-pendicular to the bisection of the heel, which is grossly in valgusrelative to the tibial bisection.

CFR was identified in 11 (52%) of the 21 patients, or 19

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(54%) of 35 feet, and in all cases the CFR was presentconcomitantly with middle facet TCC and a valgus heelbisection. Eight of these patients (73%) with CFR had thecondition bilaterally. Of the remaining 3 patients with CFR,2 had unilateral TCC and 1 had bilateral TCC. Of the 2patients with unilateral TCC and CFR the contralateralextremity had not been evaluated by CT scan so a diagnosisof CFR could not be confirmed or denied. Fifteen (79%) ofthe 19 feet with CFR were treated surgically for theirconcomitant middle facet TCC.

Discussion

Middle facet tarsal coalitions are common causes of rigidflatfeet in children and adolescents (7, 13–15). In a literaturereview spanning 50 years, Stormont and Peterson (15)found that 314 tarsal coalitions had been reported and 48%involved the talocalcaneal complex, with the majority ofthose involving the middle facet. They may occur unilater-ally or bilaterally in as many as 50% of cases (9, 15–17),although in our series the incidence of symptomatic bilateralcoalition with at least 1 foot treated surgically was 67%, andthe incidence of bilateral coalition when CFR was presentwas even greater. Tarsal coalitions frequently go unrecog-nized because the symptoms tend not to appear until mid tolate adolescence (14, 18). As a result, patients may developperoneal spastic flatfoot and secondary degenerative arthri-tis of the rearfoot complex (8, 9), but no article has studiedthe pseudoarticulation between the fibula and calcaneus inthis patient subset that we are aware of. Furthermore, untilnow no author has identified CFR as a potential part of thepathological process associated with TCC and pes plano-valgus deformity in such a large cohort of surgically man-aged patients analyzed through CT scans.

Recent literature has questioned the source of the associatedsymptoms, which may be related to the coalition itself, orinstead, to the pes planovalgus (1, 3, 5, 6). Part I of this seriesemphasized the concomitant single-stage correction of pesplanus associated with middle facet TCC. It has been previ-ously illustrated by at least 3 separate investigators that in thepresence of heel valgus, simple resection of the TCC mayresult in poorer outcomes if the flatfoot is not addressed (1, 5, 6).Mosca (3) identified separately in his article on calcaneallengthening for symptomatic flatfoot and skewfoot deformity,that 1 patient required a staged correction of flatfoot for per-sistent pain after an isolated TCC resection.

This part of our series (Part II) identifies a component oftarsal coalition and pes planus that, to the best of ourknowledge, has never before been correlated on CT: calca-neal fibular remodeling. Diagnosed best on coronal CTslices, CFR refers to remodeling present at the lateral cal-caneus and distal fibula that is likely secondary to a fixed

heel valgus leading to consistent pathological contact be-

tween the 2 bones. In a pediatric patient with a congenitalfixed coalition and calcaneal valgus, the axial loads may betransferred laterally into the fibula and onto the calcaneus,resulting in CFR.

It appears that less severe CFR takes the form of ebur-

FIGURE 4 Bilateral CFR and heelvalgus associated with bilateralmiddle facet TCC in a skeletally im-mature 12-year-old male. Note thecystic areas within the bilateralplantar lateral calcaneus (asterisks),eburnation at the superolateral cal-caneal wall (inferior to arrows) andslight peri-articular lipping (arrows)at the most superior portion of thelateral calcaneus.

nation and sclerosis at the superolateral wall of the calca-

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neus as it is forced to articulate with the distal lateralmalleolus. In later stages of CFR, or more advanced CFR,cysts may be found in the calcaneus and fibula that maycommunicate with the developing false articulation betweenthe 2 bones, as Landells (19) describes in his treatise on

FIGURE 3 CFR associated withTCC in a skeletally immature 11-year-old girl (TCC is not visualizedon these sections). Heel valgus ispresent along with eburnation atthe superolateral wall of the calca-neus where the fibula abuts the cal-caneus. A large plantar calcanealcyst is intimately associated withthe eburnation (asterisks). A fibularcyst is present as well, unilaterally(white arrow).

bone cysts in osteoarthritis. However, Landells was discuss-

LUME 47, NUMBER 4, JULY/AUGUST 2008 291

ing periarticular cysts and we identify cysts associated witha pseudoarticulation. In end-stage remodeling, or severeCFR, there are significant morphologic changes in the cal-caneus and distal fibula that fully resemble the assembly ofan errant articulation between these two bones. Similar to afalse ball and socket joint, the calcaneus may develop an

FIGURE 5 A 56-year-old femalewith bilateral TCC and bilateral CFR.Note the presence of “cup-shaped”morphologic changes at the lateralcalcaneal wall bilaterally. There is aphyseal remnant present.

acetabulum at its superolateral wall (Figure 1) to accommo-

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date for the lateral malleolus being driven inferiorly withweight-bearing axial loads.

The etiology of CFR appears to be the rigid pes plano-valgus, which is frequently secondary to the tarsal coalition.In other words, the etiology of CFR is a reflection of thecalcaneal valgus and ground reactive forces that are lateral

FIGURE 6 A 13-year-old femalewith bilateral middle facet TCC,heel valgus, and CFR. Note thepresence of extensive calcanealcysts (asterisks) intimately associ-ated with the eburnation at the su-perolateral calcaneal wall. Alsonote the subtle fibular cysts and thesignificant lateral talar spur that ap-pears to be “caught” between thepseudoarticulation (black arrow).

to the sagittal bisection of the ankle. Hansen (12) identified

that “The difference between ‘good’ and ‘bad’ flatfoot liesin the alignment of the foot in relation to the weight-bearingline of the leg. In general, a symptomatic foot lies lateral tothe weight-bearing line of the leg and demonstrates bothintrinsic bony malalignment (due to damage or stretching ofthe ligament) and muscle imbalance (usually gastrocnemiusor gastrocsoleus equinus).”

Many authors have identified peroneal spasm as a sourceof pain and disability that has been associated with tarsalcoalition (7, 8). We suspect that, in some cases, the lateralrearfoot pain associated with peroneal spasm may instead bepart of the sequela of the peroneal tendon entrapment at thepseudoarticulation between the calcaneus and fibula withaxial weight-bearing loads. Furthermore, in the setting ofsymptomatic TCC, some surgeons have associated the dif-fuse rearfoot pain with calcaneocuboid, talonavicular, or

TABLE 1 Patient data

Patient Age* andSex

Side CT Width,mm

CFR TCC SurgeryPerformed

1 10F R 3 y yL y y

2 9M L 3 n y3 17M L 4.5 n y4 51F R 3.75 y y

L y n5 18F R 1 y n

L y y6 13M L 2.5 n y7 10M R 3 n y

L n y8 16M L 1.3 n y9 48M R 1.25 n y

L n n10 12M R 3 y y

L y y11 18M R 2.5 n n

L n y12 56F R 3 y y

L 3 y n13 8F R 2.5 y y

L y y14 19M R 2.5 n y

L n n15 14F L 2.5 y y16 11M R 1.25 y n

L y y17 10M L 1.2 y y18 15F L 2.5 n y19 16F R 2.5 y y

L n y20 16F R 3 n y

L n y21 13F R 1.2 y y

L y y

Abbreviations: CFR, calcaneal fibular remodeling; F, female; L, left;M, male; n, no; R, right; TCC, talocalcaneal coalition; y, yes.*Age at time of computed tomography (CT).

talocalcaneal arthrosis, when in fact it may be the pain

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associated with CFR. In some cases involving the subtalarjoint, double or triple arthrodesis has been recommended forthe management of peroneal spasm and/or talocalcanealcoalition that may have been associated with CFR. Unfor-tunately, long-term studies on the fusion of essential jointshave demonstrated significant devolution of arthrosis in theremaining joints of the foot (20, 21). Is it possible that insome instances the hindfoot joints may be spared (ratherthan fused) for the management of TCC? In the absence ofsignificant subtalar joint arthrosis, perhaps an alternativeoption for the management of TCC with concomitant CFRis to restore the weightbearing axis of the leg and the foot bya single-stage flatfoot reconstruction coupled with middlefacet coalition resection (4). The goals of this combinedreconstructive procedure would include alleviation of thepotential peroneal tendon impingement, restoration of nor-mal hindfoot architecture by bringing the calcaneus underthe tibia, and perhaps prevention of CFR exacerbation.

With CFR it is unclear if there is a progressive remodel-ing with weight-bearing loads where the spurs and cystslead to collapse into the lateral calcaneal wall. It is unclearif the eburnation begins first followed by the spurs and cystsor vice versa. It is also unclear if the degree of calcanealvalgus plays the most important role in determining theseverity of CFR, although these authors believe this may bethe case. In any event, we identified CFR in about halfthe patients (52%) who were treated operatively for middlefacet coalition, and CFR consistently presented in a triadwith TCC and heel valgus. Furthermore, 15 (79%) of the 19feet with CFR were managed surgically at the time ofmanuscript submission for middle facet TCC.

Varner and Michelson (22) retrospectively reviewed 32feet in 27 adults with the diagnosis of tarsal coalition seenat The Johns Hopkins Hospital Foot and Ankle Clinic overa 5-year period. Although they used CT scans for analysis ofthe deformity, they did not seem to identify the CFR, whichwe describe in this article. Taniguchi et al (23) retrospec-tively reviewed 19 CT scans in 55 feet with coalition.Nowhere in their study did they identify CFR either. Giventhe paucity of evidence-based medicine on this topic, futurestudies specifically looking at CFR would be beneficial.

There were limitations to this study. For one, there werevariations in slice width between some of the CT scans, al-though the average slice width across all examinations wasonly 2.4 mm. Also, because some of the CT scans werecompleted at different institutions there may be subtle differ-ences between the scans. In evaluation of CFR there may havebeen observer bias and/or error. In all cases, the presence ofCFR was evaluated by both authors. We attempted to useobjective criteria in evaluating for the presence or absence ofCFR. The presence of eburnation, in particular, was moredifficult to assess and this did pose a challenge for our objec-tive criteria. Furthermore, because this was a retrospective

study evaluating CT scans over a 12-year period at numerous

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locations, the quality and techniques of scans varied and clin-ical charts were not always available. This precluded a consis-tent method for evaluating the exact degree of heel valgus. Inthis study, the inference was made that all feet were symptom-atic because all feet in this retrospective review were evaluatedby CT and 28 of the 35 feet had surgery. It is possible,however, that the 7 feet that were not treated surgically forTCC were not symptomatic, although they were scanned byCT, which suggests otherwise. Furthermore, it is possible,although unlikely, that there were feet in this study that werenot symptomatic despite the fact that they were treated oper-atively. Because this was a retrospective study and CFR wasidentified secondarily, there is no way to clearly know if theCFR was a direct source of symptoms. Only a prospectivestudy targeting CFR would better correlate its clinical signifi-cance. While the morphologic changes are somewhat obviouson the CT images, it is possible that CFR may not be directlyassociated with the patients’ “symptoms” at all. However,these morphologic changes associated with heel valgus surelysuggest a pathologic process, especially in the context of TCCwith concomitant flatfoot. This is particularly poignant whenconsidering that a large majority (79%) of those feet with CFRhad surgery to treat their concomitant symptomatic middlefacet TCC. This does not necessarily suggest that CFR was thecause or need for surgery, but rather that it may play a role inthe symptoms associated with the condition.

Conclusion

Talocalcaneal middle facet coalitions are known to producea rigid pes planovalgus that often requires surgical interven-tion. Unfortunately, there is a lack of evidence-based medicinedefining the pathophysiology behind the symptomatic middlefacet TCC altogether. This retrospective CT review presentsthe largest cohort of patients treated surgically for symptomatictalocalcaneal coalition that the authors are aware of to date. Inthis review, we identify a pathological component of middlefacet TCC associated with calcaneal valgus; titled calcanealfibular remodeling. In this cohort of 35 feet, CFR was presentin about half (52%) of the patients treated surgically for middlefacet TCC. The presence of CFR may contribute to the symp-toms associated with painful middle facet TCC. The morpho-logic changes associated with CFR provide a clearer indicationthat simple resection of the coalition may not fully address theentire deformity and other combined surgical approaches maybe more appropriate in the face of middle facet TCC with heelvalgus and CFR.

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