Proximal Fibula

Proximal Fibula

Isolated fractures of the proximal fibular physis are rare [1, 3]. Most fractures of the proximal fibular phy- sis occur in conjunction with tibial shaft fractures.

Since the tibial fracture is of greater concern, the fibu- lar fracture often is unnoticed or untreated and may not be documented statistically. It is rarely reported [1, 3].

Anatomy and Growth

The contour of the proximal fibular physis is initially transverse, but changes to one with peripheral lappet formation and multiple undulations. It is located 5–

10 mm distal to the proximal tibial physis [5]. Ossifi- cation of the epiphysis begins just proximal to the physis at mean age 33 months in girls and 47 months of age in boys [2, 8]. Ossification gradually extends proximally into the rest of the epiphysis with the fibu- lar styloid ossifying late in skeletal maturation [5].

Contents

Anatomy and Growth .. . . ..791 Classification ... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ...792 Epidemiology .. . . ..793 Literature.Review.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .793 Olmsted.County.Study. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .793 Evaluation . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .793 Management ... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ...793 Complications . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .793 Growth.Arrest. .. . . ..793 Neuropathy.... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ...793 References . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .795

The proportion of growth occurring at the proxi- mal and distal ends of the fibula gradually changes so that more growth occurs at the proximal physis than at the distal physis (Fig. 27.1). The proportion of

Fig. 27.1

The.percentage.of.growth.of.each.end.of.the.fibula.at.

birth,. midway. through. growth,. and. at. maturity .

(Adapted.from.Pritchett.[7],.with.permission)

growth occurring at the proximal fibular physis varies from 50% at age 7 to 85% at age 13 in girls and in boys from 50% at age 7 to 85% at age 15 (Fig. 27.2) [7]. The overall growth contribution of the proximal fibular physis is 61% compared with 57% for the prox- imal tibia [7]. Knowledge of the amount of growth remaining (Fig. 27.3) is helpful in treating cases of premature closure of any physis of the fibula or tibia.

An intact fibula and weightbearing are important for normal growth of the proximal physis. Deformity of both the knee and the ankle is possible when fibu- lar growth is not in normal proportion to tibial growth [7]. The mean age of closure of the physis is 17 years for boys and 15 years for girls (Fig. 27.3); two years later

than the distal fibular physis (Fig. 12.3). There is little growth during the last 2 years of the open physis.

The lateral collateral ligament and biceps tendon attachments to the proximal fibular styloid may play a role in producing avulsion type 3 and 4 fractures, and in maintaining displacement with any type of fracture.

Classification

The anatomic classification is appropriate here (Fig. 3.6). It is expected that the majority of proximal fibular physes fractures would be types 2 (Fig. 27.4) and 3 (Fig. 27.5).

Fig. 27.2

The percentage of growth of the fibula occurring at the proximal physis from age 7 years to maturity. (Adapted from Pritchett [7], with permis- sion)

Fig. 27.3

The amount of growth remain-

ing in the proximal fibula from

7 years to maturity. The central

line is the average, the broken

lines are one standard devia-

tion to each side from the aver-

age. (Adapted from Pritchett

[7], with permission)

Epidemiology Literature Review

The proximal fibular physis is the least injured long bone physis (Tables 4.5, 4.6, 4.11). Only seven cases are recorded in the literature as case studies [1, 3].

Other cases are present in articles and book chapters as fractures associated with tibial fractures. Havránek [3] reported that, of 292 fibular fractures, 6 (2.1%) were proximal fibular physeal fractures. All six in- curred their fracture as pedestrians in traffic acci- dents by vehicles striking the knee, and all but one had multiple concomitant injuries. There were two boys and four girls with a mean age of 11.9 years. Of 175 physeal fibular fractures reported from 1970- 1990, 9 (5%) were proximal and 166 (95%) were distal (Table 4.7). In Mann and Rajmaira’s report [4], 7 of 97 fibular physeal fractures (7%) were at the proximal end. There were 4 males and 3 females. Information regarding fracture type is very limited (Table 27.1).

Olmsted County Study

Only 1 case (0.1% of all 954 physeal fractures) was recorded in the Olmsted County population-based study [6]. It was a type 5 fracture (Peterson classifica- tion) in a 14-year-old boy (Table 4.12). This represent- ed 1.4% of all fibular physeal fractures (Table 4.13).

There were no complications (Table 8.1).

Evaluation

Pain, tenderness, and swelling over the head of the fibula are usual. AP and lateral roentgenograms frequently do not display the fracture well (Figs. 27.4a, 27.5a). Oblique views are suggested. Concomitant tibial fracture is the rule.

Management

Severe displacement is uncommon and most fractures can be treated by cast immobilization for 3–6 weeks [3]. The longer time in cast may be a result of con- comitant injuries. Significant displacement, possibly caused by the powerful biceps muscle-tendon attach- ment, warrants open reduction. Most children have uneventful recoveries [3].

Complications Growth Arrest

Premature physeal arrest has not yet been shown to produce a clinical problem with either the knee or the ankle. Both partial (Fig. 27.4d) and complete (Fig. 27.5c) arrests are possible. There is suspicion that shortening of the proximal fibula relative to the tibia in a young child may lead to progressive genu valgum (Fig. 27.4c, d). No bar excisions have been recorded at this site (Table 33.4).

Neuropathy

The peroneal nerve lies close to the proximal tibial epiphysis. In most cases, an accompanying neuropa- thy would be expected to resolve spontaneously.

Table 27.1. Proximal.fibula.physeal.fractures.by.type.(Salter-Harris.classification)

Year Author   1   2   3   4 5 Total

1990 Mann.and.Rajmaira 2 2 2 1 0 7

1996 Havránek 0 3 1 2 0 6

T

2 5 3 3 0 13

Percent 15 4 38 5 23 1 23 1 0 100 1

Fig. 27.4

Proximal.fibula.type.2.fracture.in.a.6.year.5.month.old.girl.with.an.associated.fracture.of.the.proximal.tibia .a.There.is.

lateral.displacement.of.the.proximal.fibular.epiphysis.along.with.a.portion.of.the.metaphysis.(Holland.sign),.partially.

obscured.by.an.external.immobilizing.device .Treatment.was.closed.reduction.of.the.tibia.fracture.and.cast.immobili- zation .b.Fifteen.months.later,.age.7.years.8.months,.there.is.relative.shortening.of.the.proximal.fibula,.an.indistinct.

proximal.fibular.physis,.and.possible.genu.valgum .c.Tomogram.confirms.premature.partial.physeal.closure.medially . The.normal.proximal.fibula.has.6–7.cm.of.growth.remaining.(Fig .27 3) .d.Photograph.at.age.7.years.9.months .There.is.

mild.left.genu.valgum .The.treating.physician.chose.to.continue.observation

References

1. Brenkel IJ, Prosser AJ, Pearse M: Salter type 2 fracture separation of the proximal epiphysis of the fibula. Injury 18:421-422, 1987

2. Flecker H: Time of appearance and fusion of ossification centers as observed by roentgenographic methods. Am J Roentgenol 47:97-159, 1942

3. Havránek P: Proximal fibular physeal injury. J Pediatr Or- thop 5:115-118, 1996

4. Mann DC, Rajmaira S: Distribution of physeal and non- physeal fractures in 2650 long-bone fractures in children ages 0 to 16 years. J Pediatr Orthop 10:713-716, 1990

5. Ogden JA: Radiology of postnatal skeletal development.

IX. Proximal tibia and fibula. Skel Radiol 11:169-177, 1984 6. Peterson HA, Madhok R, Benson JT, Ilstrup DM, Melton

III LJ: Physeal fractures: Part 1. Epidemiology in Olmsted County, Minnesota, 1979-1988. J Pediatr Orthop 14:423- 430, 1994

7. Pritchett JW: Growth and growth prediction of the fibula.

Clin Orthop 334:251-256, 1997

8. Pyle I, Sontag LW: Variability in onset of ossification in epiphyses and short bones of the extremities. Am J Roent- genol 49:795-798, 1943

Fig. 27.5

Proximal.fibula.type.3.fracture .This.14.year.6.month.old.boy.injured.his.right.knee.in.a.motorcycle.accident .a.AP.view.

shows.fracture.of.the.proximal.tibia.and.suggestion.of.fracture.of.the.distal.femur .The.proximal.tibia.and.fibular.physes.

appear.normal .b.Lateral.view.shows.mildly.displaced.and.angulated.type.3.fracture.of.the.proximal.fibula .The.tibial.

fracture.was.reduced.closed.and.a.long.leg.cast.was.worn.for.several.weeks .c.Scanogram.at.age.16.years.11.months,.

2.years.4.months.post.injury .All.physes.are.closed .The.proximal.right.tibial.and.fibular.physes.ceased.growing.earlier.

than.the.left.resulting.in.a.3.cm.length.discrepancy