Spontaneous Resolution
Introduction
The possibility of spontaneous disappearance of an established bone bar is very small [5, 11]. However, on rare occasions, a small physeal bar, which has caused relative shortening, angular deformity, and has asym- metric growth arrest lines, may resolve spontaneously
Contents
Introduction . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .902 Forme Fruste Bar ... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .902 Author’s Perspective ... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .904 References . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .906
(Fig. 36.1). This phenomenon is conceptualized by continued longitudinal growth of the noninjured physis adjacent to the bar, overcoming the bar (break- ing it loose) [13]. The process has also been likened to “a small bridge letting go, like a piece of taffy” [4].
With resumption of growth the osseous bar is left be- hind in the metaphysis [3, 14]. Presumably, normal physis grows latitudinally, occupying the site of the previous bar.
It would be logical to study this phenomenon by expressing the bar as a percentage of the total physis.
In 1969, Nordentoft [13] conducted a series of experi- ments on dogs and rabbits, one of which was piercing the physis with 3- to 5-mm drills. He concluded that destruction of up to 10% of the physis “did not ever result in permanent arrest of growth.” Both Bollini et al. [1] and Kershaw and Kenwright [9] misinterpreted
Fig. 36.1
Distal.tibia.medial.malleolus.type.5.fracture,.with.premature.partial.arrest.and.spontaneous.resolution .This.8.year.
10.month.old.boy.fell.out.of.a.tree.injuring.his.left.ankle .a.There.is.a.mildly.displaced.type.5.fracture.through.the..
medial.portion.of.Poland’s.hump.and.a.type.3.fracture.of.the.distal.fibular.physis .b.An.“excellent.anatomical.reduc- tion”.was.achieved.and.maintained.by.a.“leg.cast”.for.7.weeks .(Continuation see next page)
Fig. 36.1 (continued)
c.One.year.later,.age.9.years.10.months,.there.was.occasional.mild.limp,.mild.ankle.varus.clinically,.and.bar.formation.
medially.at.Poland’s.hump.with.asymmetric.Harris.growth.arrest.lines.on.the.left,.due.to.more.growth.laterally.than.
medially .The.bone.age.was.9.years.0.months .d.At.age.10.years.1.month.the.bar.had.broken.and.the.Harris.growth..
arrest.lines.were.more.symmetric .The.patient’s.total.body.height.had.increased.5/8.inch.during.this.3.month.interval . (Continuation see next page)
Nordentoft by stating that a bone bridge of less than 10% of the overall surface of the growth plate may spontaneously break, with no adverse effect on length.
Bowen [3] estimated that bone bridges of “less than approximately 7% of the growth plate” may break loose. Jaramillo and Shapiro [7] state that physeal growth can overcome “very small” bridges and allow
normal growth to occur, but only in the first 6 months
following physeal fracture. None of these statements
(other than by Nordentoft) were supported with sci-
entific evidence. Also note that the bar illustrated in
Fig. 36.1b broke loose sometime between 12 and
15 months after fracture (Fig. 36.1c). Conversely, the
size of the smallest bar that has progressed to com-
Fig. 36.1 (continued)
e.Tomograms.confirmed.physeal.deformity.but.an.absence.of.a.complete.bar.on.all.cuts.available.for.review .f.At.age.
10.years. 6.months. the. patient. had. grown. 1-3/8.inch. in. the. previous. 8.months. and. the. left. leg. clinically. measured.
1/4.inch.shorter.than.the.right .Note.an.os.subtibiale.on.left,.not.on.right .(Continuation see next page)
plete closure has also not been determined. In a per- sonal case, a 4.5% bar of the distal tibial physis (Fig. 11.6f) did not break loose, and progressed to complete premature closure (Fig. 11.6g). Information presented on biodegradeable implants across the physis (Chapter 6), has some relevance to this discus- sion.
Case reports of spontaneous resolution include
three from the distal tibia [2, 5, 6], one from the distal
femur [10, 11], and one from the proximal femoral
capital physis [8]. The ages of these patients at time
of fracture were 4 years 11 months [5], 5 years [2],
5 years 4 months [8], 8 years [6], and 10 years 3 months
[10, 11].
Forme Fruste Bar
A post physeal fracture cartilage disturbance which masquerades as an incomplete bar, may cause relative shortening (Fig. 36.2). This could be called an atypi- cal or forme fruste bar. This phenomenon is uncom- mon, may cause angular deformity, and may resolve spontaneously (Fig. 36.3). The longitudinal length of the cartilage in the metaphysis is related to the dura-
tion of time between the insult and imaging and is similar, if not identical, to a vascular insult of the me- taphysis as depicted on Fig. 2.8. Histologic analysis confirms the presence of hypertrophic physeal chon- drocytes in the metaphysis, which represent an inter- ruption or delay of enchondral ossification [12]. The type of insult (single event or repetitive) along with the morphology and location of the cartilage abnor- mality, may be predictors of subsequent true growth disturbance [12].
Fig. 36.1 (continued)
g.Internal.rotation.views.age.12.years.4.months .The.Harris.growth.arrest.lines.show.symmetric.growth .The.left.tibia.
was.4.mm.shorter.than.the.right,.and.the.left.femur.3.mm.longer.than.the.right .h.At.age.14.years.8.months.the.patient.
was.normally.active.and.asymptomatic .The.left.tibia.is.3.mm.shorter.than.the.right .The.Harris.lines.have.nearly.disap- peared .(Case.contributed.by.Dr .Lee.Skimming,.St .Louis,.MO)
Fig. 36.2
Forme.fruste.bar .This.8.year.7.month.old.boy.sustained.
a.left.wrist.injury .a.There.is.a.dorsally.displaced.type.3.
fracture.of.the.distal.radius .The.point.of.contact.of.the.
dorsal.metaphysis.to.the.epiphysis.could.predispose.to.
a.central.physeal.bar .b.The.fracture.was.reduced.and.a.
long.arm.cast.applied .c.Twenty-two.months.later,.age.
10.years.5.months,.the.patient.sustained.a.finger.frac- ture . The. roentgenograph. included. the. wrist,. which.
showed. relative. shortening. of. the. radius. compared. . to.the.ulna,.and.an.essentially.normal.radial.physis .The.
prominent. distal. ulna. had. not. been. noted. by. the. . patient.or.the.physician.father .Note.nonunion.of.the.
ulnar.styloid .(Continuation see next page)
Internal fixation pins temporarily placed across a physis may result in abnormalities resembling tiny bars (Fig. 3B.5e) or established bars (Fig. 30.9d, e, f, g). They may subsequently show relatively normal growth, yet with residual minor relative shortening and angular deformity (Fig. 3B.5f). One explanation would be that the bar that formed following pin re- moval temporarily inhibited growth, but broke loose to allow normal subsequent growth.
Author’s Perspective
Physeal bar spontaneous resolution is poorly defined, little researched, infrequently described, and may be underreported. After personal involvement in cases described in Figs. 3B.5 and 36.1, considerable experi- ence with bar excision, and review of the literature, I conclude that a bar of greater than 5% of the total physis will not spontaneously resolve and I would proceed with alternative treatment. A bar 5% or less could be observed a short while, but not long enough to allow deformity sufficient to require osteotomy.
In making this decision, the age of the patient, the amount of growth remaining, and the site are obvi- ously important. A young patient with actively grow- ing physes might have the best chance for spontane- ous resolution (note the ages of the patients illustrated here and in the literature are all ten years or less).
Fig. 36.2 (continued)
d.An.MRI.showed.an.irregular.distal.radial.physis.with.a.nonosseous.longitudinal.defect.originating.in.the.metaphysis.
extending.distally.to.the.epiphysis .There.was.no.specific.physeal.bar .Growth.of.the.radius.was.less.than.that.of.the.
normal.ulna .The.patient.was.lost.to.follow-up .(Case.contributed.by.Dr .MI.Busch,.Atlanta,.GA,.with.permission)
Fig. 36.3
Displaced.distal.femur.type.2.fracture,.with.forme.fruste.bar .This.7.year.0.month.old.female.was.struck.by.an.automo- bile.injuring.the.left.knee .a.There.is.anterior.and.medial.displacement.of.the.epiphysis .Closed.reduction.was.followed.
by.application.of.a.single.spice.cast .b.One.year.post.fracture.(age.8.years.0.months).the.distal.femoral.physis.and.its.
accompanying.growth.arrest.lines.were.indistinct .There.was.mild.genu.valgum .c.Eighteen.months.post.fracture.(age.
8.years.6.months).the.genu.valgum.had.increased.and.the.left.femur.was.3.mm.shorter.than.the.right .Premature.par- tial.arrest.was.suspected .The.left.tibia.was.2.mm.shorter.than.the.right .d.MR.imaging.revealed.a.cartilage.irregularity.
on.the.lateral.side,.but.no.true.bone.bridge .Observation.was.continued .(Continuation see next page)
References
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duced in the cartilaginous epiphyseal plate of immature dogs by experimental surgical traumata. J Bone Joint Surg 41A:1221-1242, 1959
5. Chadwick CJ: Spontaneous resolution of varus deformity at the ankle following adduction injury of the distal tibial epiphysis: a case report. J Bone Joint Surg 64A:774-776, 6. Herring JA: Instructional Case: Whither the bar. Guest 1982 Discussant: John Birch MD. J Pediatr Orthop 7:722-725, 1987
7. Jaramillo D, Shapiro F: Musculoskeletal trauma in chil- dren. Magn. Reson. Imaging Clin. N. Am. 6:521-536, 8. Katz JF: Spontaneous correction of angulational deformity 1998 of the proximal femoral epiphysis after cervical and tro- chanteric fracture. J Pediatr Orthop 3:231-234, 1983 9. Kershaw CJ, Kenwright J: Epiphyseal distraction for bony
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Raven Press, New York, 1988, pp 259-261
11. Langenskiöld A: The possibilities of eliminating premature partial closure of an epiphyseal plate caused by trauma or disease. Acta Orthop Scand 38:267-279, 1967
12. Laor T, Hartman AL, Jaramillo D: Local physeal widen- ing on MR imaging: an incidental finding suggesting prior metaphyseal insult. Pediatr Radiol 27:654-662, 1997 13. Nordentoft EL: Experimental epiphyseal injuries: Grading
of traumas and attempts at treating traumatic epiphyseal arrest in animals. Acta Orthop Scand 40:126-192, 1969 14. Österman K: Regeneration of the growth plate. Mapfre
Med 4 (suppl III):85-86, 1993 Fig. 36.3 (continued)
e.Scanogram.2.years.4.months.post.fracture.(age.9.years.4.months).shows.genu.valgum.and.length.discrepancy.un- changed .Continued.observation.was.advised .The.genu.valgum.gradually.decreased .f.Scanogram.3.years.4.months.
post.fracture.(age.10.years.4.months).shows.the.genu.valgum.has.decreased.to.near.normal.and.the.left.femur.remains.
only.2.mm.shorter.than.the.right .g.A.close-up.of.the.distal.femur.show.the.epiphysis.has.grown.away.from.the.carti- lage.abnormality.and.the.physis.appears.normal
