Distal Ulna
The distal ulnar secondary center of ossification (SCO) is an epiphysis (rather than an apophysis) by virtue of its physis being transverse to the longitudi- nal axis of the ulna, and because it contributes 80%
growth of the ulna (Fig. 16.1). These features preempt the apophyseal features: lack of articulation with the carpus and being the site of strong ligamentous attachments (triangular fibrocartilage, dorsal and palmar radioulnar ligaments, and ulnocarpal liga- ments), all of which attach to the ulnar styloid.
Anatomy and Growth
The distal ulnar physis is initially transverse and flat.
It gradually develops a mild convex contour with mild undulations. The roentgenographic appearance of the SCO is extremely variable, beginning between ages 4.5 and 7.5 years in girls and between 5.5 and 9.5 years in boys [8,14]. In a study of 1,762 children [25] it was present in 100% of subjects only by age 9 years. Ossi-
Contents
Anatomy and Growth... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...525 Classification ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...527 Epidemiology .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..527 Literature.Review.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .527 Olmsted.County.Study. . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .527 Evaluation . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .527 Management ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...531 Complications.. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..534 Irreducible.Fracture. ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...534 Premature.Closure. . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .534 Bifid.Epiphysis... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..536 Malunion. ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...536 Author’s Perspective. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .542 References. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .546
fication of the styloid process of the epiphysis occurs by extension from the primary SCO and occurs later.
It appears radiographically at age 7 in 7%, at age 11 in 75%, and at age 13 years in 94% [25]. A separate ossi- fication center for the styloid process could be found in only 4 out of 2,684 cases between ages 14 and 16, and there was a history of trauma in each of these four [25]. This refutes the theory that the styloid process of the ulna may have an independent ossification center.
Fig. 16.1
Contribution.of.growth.from.the.distal.and.proximal.
physis.of.the.ulna.at.birth,.mid-childhood,.and.at.com- pletion. of. growth .. (Adapted. from. Pritchett. [19,. 22],.
with.permission)
Fig. 16.2
The.contribution.of.growth.of.
the.distal.ulnar.physis.is.shown.
on.the.solid line ..Line B.indicates.
birth ..The.solid.line.is.extrapo- lated.back.to.the.beginning.of.
growth ..(Adapted.from.Pritch- ett.[21,.22],.with.permission)
Fig. 16.3
Annual. increment. of. growth.
for. the. distal. ulna. from. age.
7.years. to. skeletal. maturity ..
(Adapted. from. Pritchett. [22],.
with.permission)
Fig. 16.4
Amount. of. growth. remaining.
from. the. distal. ulna. from. age.
7.years. to. maturity .. (Adapted.
from. Pritchett. [20,. 22],. with.
permission)
Thus, when a separate ulnar styloid ossific structure is present, the implication is that it is a result of previ- ous trauma.
The distal ulnar epiphysis articulates with the dis- tal radius and functions as a post around which the radius rotates. It is separated from the carpus by the triangular cartilage and is therefore extra-articular to the wrist joint. It does, however, support the wrist.
Absence of a normal distal ulnar epiphysis, or a short ulna, results in radial bowing, ulnar angulation of the distal radial articular surface, and ultimately ulnar- ward slip of the carpus on the distal radius.
Longitudinal growth of the distal ulnar physis gradually assumes a greater proportion of total ulnar growth (Fig. 16.2). From age 7 to near skeletal matu- rity the distal ulna grows approximately 1.0 cm a year in boys and 0.9 cm in girls (Fig. 16.3). From age 7 the amount of growth remaining gradually diminishes until maturity (Fig. 16.4). These graphs can be helpful when evaluating growth or lack of growth in individ- ual patients.
There is also disproportionate growth between the distal ulnar and radial physes. The distal ulna mi- grates distally, relative to the distal radius, during growth. In early life the distal ulnar physis is proxi- mal to the distal radial physis, and at the end of growth is equal to it [19]. Assessing this aspect of wrist growth in any given case could be done by compari- son views with the normal wrist.
Classification
The 6 type anatomic classification is used here (Fig. 3.6).
Epidemiology Literature Review
The percentage of physeal fractures occurring in the distal ulna has gradually decreased in the past centu- ry. From 1900 to 1970, the frequency was 6% of all physeal fractures (Table 4.5), and from 1970 to 1990, 3% (Table 4.6) [10, 12, 17]. The low risk of distal ulnar physeal fracture may be explained, in part, by the cushioning effect imparted by the interposition of the meniscus between the ulna and the proximal carpal row, as well as the propagation of deforming forces through the triangular cartilage directly to the styloid process which frequently fractures (Fig. 10.8) [5]. In addition, when a distal ulnar physeal fracture occurs with a fracture of the distal radius, it may not be re-
corded statistically, particularly if it is undisplaced or otherwise requires no individual treatment. Of all ul- nar physeal fractures, 91% are distal and 9% are prox- imal (Table 4.7).
The largest series in the literature is 18 cases [5].
All had an associated fracture of the radius. The youngest patient was 5 years and the oldest 15 years of age. There were 10 girls and 8 boys. Salter-Harris type 1 fractures were the most common, followed by type 3 fractures. The most common mechanism of injury is a fall on the outstretched arm.
Olmsted County Study
In the Olmsted County study [18] population-based study of 951 physeal fractures, there were 27 (2.8%) in the distal ulna (Table 4.12). The 27 distal ulnar frac- tures represented 87% of all ulnar physeal fractures (Table 4.13). There were 17 males, ages 5–16 years (maximal incidence at 14 years) and 10 females, ages 5–14 years (maximal incidence at 10 years). There were 6 type 1, 7 type 2, 5 type 3, 9 type 4, and no types 5 or 6 (Table 4.12). This is a more even distribu- tion of types than at other sites. The high frequency of type 4 fractures (Fig. 16.5) in this study has not been noted in previous literature. No patient had initial surgery on the distal ulna. Two of the 27 patients (7%, Table 8.6) had four complications (Table 8.1). Both patients were treated with late surgery.
Evaluation
Isolated fracture of the distal ulnar physis is uncom- mon (Fig. 16.5). When the distal ulnar physis is frac- tured, there is almost invariably an associated distal radial fracture [1, 2, 5, 11, 23]. Conversely, fractures of the distal radius are frequently accompanied by ulnar styloid fracture (Fig. 10.8), and less commonly by ul- nar physis fracture. If a distal radial fracture has no accompanying fracture of the ulnar styloid or ulnar metaphysis, then ulnar physeal fracture should be suspected. This may all be explained by propagation of forces through the palmar and dorsal radioulnar ligaments and the triangular fibrocartilage directly to the styloid process, and by the cushioning effect of the triangular fibrocartilage “meniscus” between the dis- tal ulna and proximal carpal row [5].
The mechanism of injury is invariably wrist dorsi-
flexion associated with hyperpronation [2]. Clinical
findings of tenderness, swelling, and deformity are
invariably more marked over the radius, drawing the
examiner’s attention away from the ulna.
Evaluation of wrist AP roentgenographs is highly dependent on roentgenographic technique [26]. Views taken in pronation and supination differ in ulnar variance and position of the styloid. In pronation, the ulna moves distally relative to the radius, decreasing the negative ulnar variance. In addition, since the ulna lies slightly more dorsally relative to the radius, the length of each is dependent on any distal or prox- imal angulation of the x-ray beam. To avoid these va- garies a standardized technique protocol is mandato- ry. Wrist views taken with the forearm supinated
correlates better with AP views of the forearm. The alternative is to take comparison views of the opposite wrist each time [26]. The lateral view also needs close scrutiny. Because the ulnar fragment is often hidden by the superimposed radius additional surveillance is necessary in young children prior to the relatively late ossification of the epiphysis.
Interestingly, in the Olmsted County study, type 4 fracture (Fig. 16.5) was most common, followed close- ly by type 2 (Fig. 16.6). A fracture of the distal radial metaphysis associated with separation of the distal
Fig. 16.5
Distal.ulna.type.4.fracture ..This.14.year.5.month.old.boy.injured.his.left.wrist.in.a.sledding.accident ..There.was.swelling.
of.the.wrist.and.tenderness.over.the.distal.ulna ..a.A.type.4.fracture.of.the.distal.ulna.is.visualized.on.the.AP.(left).and.
oblique.(right).views ..A.type.3.fracture.of.the.distal.radius.cannot.be.ruled.out ..A.short.arm.cast.was.worn.3.weeks ...
b.Seven.months.later,.age.15.years.0.months,.the.distal.radial.and.ulnar.physes.and.epiphyses.are.normal
ulnar physis and displacement of the ulnar metaphy- sis, has been described as a “Galeazzi-equivalent in- jury” in children [8, 9]. The adult Galeazzi injury is a fracture of the distal radius associated with disloca- tion of the distal radioulnar joint [8, 9]. In adults the radioulnar ligaments rupture, in children the ulnar physis fractures.
Stress injury of the distal ulnar physis (widening and metaphyseal irregularity of the physis) is identi- cal to stress injury of the distal radius (Chapter 10A).
This phenomenon is found primarily in gymnasts.
The stress injury is often isolated to the radius. When the ulna is involved the radius is typically also in- volved. Stress injury isolated to the ulna [27] is rare, but has been found in the ulna with break dancing [4].
This activity entails repetitive wrist rotation support- ing full body weight with the wrist in maximal dorsi- flexion. Symptoms abate and roentgenographs return to normal upon discontinuing the activity.
Fig. 16.6
Distal.ulna.type.2.fracture ..This.5.year.10.month.old.girl.
fell. landing. on. her. right. hand ..a. The. AP. view. (left).
shows.a.torus.fracture.of.the.distal.radius ..The.distal.
ulna. is. abnormal,. but. fracture. type. is. indeterminate ..
The. lateral. view. (right). shows. dorsal. displacement. of.
the.distal.ulnar.epiphysis.(arrow) ..b.The.oblique.view.
shows.a.completely.displaced.type.2.fracture ..(Contin- uation see next page)
Fig. 16.6 (continued)
c.Reduction.was.accomplished.by.manipulation.using.
Demerol.and.Phenergan.IV.sedation ..A.long.arm.cast..
was.worn.3.weeks ..d.Comparison.view.AP.left ..e.Four.
months. later,. age. 6.years. 2.months,. the. fractures. are.
healed.and.the.physes.growing
Management
Many distal ulnar physeal fractures occur in conjunc- tion with distal radial fractures, and since they are perceived as being less important, their presence and their treatment may go unrecorded. All 27 distal ul- nar physeal fractures in the Olmsted County study [18] were treated nonoperatively.
An isolated nondisplaced fracture of the distal ul- nar physis is uncommon and may be treated by im- mobilization. A displaced distal ulnar type 2 physeal fracture, even when associated with distal radial frac- ture, can “almost always” be reduced by closed reduc- tion even when the displacement is significant (Fig. 16.7) [3, 7]. When manipulation fails to reduce the fracture, there may be soft tissue interposition [2,
3, 7, 24] requiring open reduction (Fig. 16.8) [1]. After reduction, the fingers should move passively through their full range of motion. If there is a block or limita- tion of motion remanipulation reproducing the de- formity may disengage the tendons [1], but multiple remanipulations are usually unsuccessful, cause more tissue damage, and should be avoided.
Although open reduction of a distal ulnar physeal fracture is infrequently reported, some fractures treated nonoperatively have turned out poorly, sug- gesting that perhaps they might have turned out bet- ter with anatomic surgical reduction and internal fixation. Even though a single smooth pin is used lon- gitudinally to transfix the ulnar epiphysis, growth ar- rest may occur [1]. Open reduction without internal fixation has also been satisfactory in isolated cases [7].
Fig. 16.7
Distal. ulna. type.2. fracture .. This. 14.year. 3.month. old.
boy.was.hanging.from.his.knees.on.a.high.bar.during.
gymnastics.practice.when.he.fell,.landing.on.the.palms.
of.both.hands ..a.A.type.2.fracture.of.the.left.distal.ulna.
is.displaced.dorsally ..The.arrow.points.to.the.metaphy- seal.fragment.(Holland.sign) ..b.The.fractures.were.re- duced. under. general. anesthesia. by. manual. traction.
and. manipulation .. The.arrow. is. on. the. metaphyseal.
fragment .. A. long. arm. cast. for. 4.weeks. was. followed. . by.a.short.arm.cast.for.3.weeks ..(Continuation see next page)
Fig. 16.7 (continued)
c.Eight.months.later,.age.14.years.11.months,.the.patient.was.normally.active.and.asymptomatic ..The.ulnar.physis.was.
normal.(arrow)
Fig. 16.8
Distal.ulna.irreducible.type.3.fracture ..This.16.year.3.month.old.boy.injured.his.right.wrist.as.an.unrestrained.passenger.
in.a.motor.vehicle.rollover.accident ..a.Marked.displacement.of.the.radial.and.ulnar.epiphyses.make.fracture.type.dis- cernment.difficult ..(Continuation see next page)
Fig. 16.8 (continued)
b.Under.general.anesthesia.manual.traction.reveals.a.type.3.fracture.of.distal.ulna.(solid arrow).and.a.type.2.fracture..
of.the.distal.radius.(open arrow.points.to.the.metaphyseal.fragment) ..The.fractures.could.not.be.fully.reduced.closed ..
A.volar.incision.was.used.to.reduce.the.radius.fracture,.but.it.was.unstable.and.ulnar.fracture.remained.unreduced ...
c.A.Hoffman.external.fixator.was.applied.and.the.radius.fracture.secured.with.two. .062.and.two. .045.K-wires ..The.ulnar.
epiphysis. remained. displaced .. Upon. making. an. ulnar. incision. an. entrapped. extensor. carpi. ulnaris. was. found. and.
.extricated ..This.allowed.reduction.of.the.ulnar.epiphysis.which.was.stabilized.with.a.single. .045.K-wire ..AP.view.(left).
made.with.forearm.pronated ..Following.hospital.dismissal.the.patient.resided.in.a.correctional.facility.and.was.lost.to.
follow-up ..Anticipated.imminent.physeal.closure.would.not.present.growth.problems.at.this.age
Residual deformities are uncommon because re- modeling at the site of fracture is usually satisfactory [7]. Even with residual deformities, most patients are asymptomatic [5]. The Darrach (excision of the distal ulna) or Suave-Kapandji (distal radioulnar arthrode- sis with segmental ulnar resection) procedures are rarely needed in children following distal ulnar phy- seal fractures.
Complications Irreducible Fracture
Occasionally, closed reduction of a displaced distal ulna epiphysis cannot be accomplished. The fracture is usually type 2 [2, 3]. The cause of irreducibility is varied: interposed extensor carpiulnaris tendon (Fig. 16.8) [3, 8, 9], interposed periosteum [8, 9], inter- posed extensor carpiulnaris tendon and periosteum [8], interposed extensor digitorum communis, exten- sor indicis proprius, and extensor digiti minimi [7], interposed median nerve and flexor pollicis longus [24], and the epiphysis button-holed through the joint capsule [2]. Intact nerve function does not exclude nerve entrapment [24].
Premature Closure
The difference between premature partial and com- plete closure has not been well defined in the distal ulna, probably because the total area of the physis is small. Ogden [13] published a study on transphyseal linear ossific striations of the distal ulna, and con- cluded that these tiny physeal bridges represented a microscopic response to antecedent ischemic trauma that was insufficient to cause macrofailure (fracture) of the physis. One conclusion from this study was
that the Salter-Harris type 5 injury could be some- thing other than compression of cartilage cells in the physis.
Premature closure of the growth plate occurs com- monly in the distal ulna [2, 5, 6, 11, 15, 23]; 55% in one series [5]. This results in relative shortening of the ulna, which in turn causes progressive bowing of the radius, ulnarward tilt of the radial physis, epiphysis, and articular surface (Fig. 16.9) [16], and ultimately ulnarward slip of the carpus. These are all related to tethering of the triangular fibrocartilage, pull of the tight dorsal and palmar radioulnar ligaments, and possibly to altered forearm muscle force vectors [6].
Although the cosmetic appearance is the most com- mon complaint [5, 11], this complication may be in- sidious and may go unnoticed by the patient. As the radial bowing increases there is loss of radial devia- tion of the wrist, loss of forearm rotation, and eventu- ally dislocation of the proximal radius from the capi- tellum. If relative ulnar shortening is severe it may be associated with weakness of grip and limitation of wrist motion [23]. Regular post fracture follow-up is the only way to prevent these deformities.
In assessing ulnar variances of small amounts it is necessary to obtain roentgenographs of both wrists for comparison. Since the ulna lies dorsal to the radi- us the x-ray projection must be perpendicular to the wrist joint to avoid parallax discrepancies. In addi- tion, in supination the distal radius moves distally relative to the distal ulna and the contour of the ulnar styloid changes [26]. Wrist roentgenographs should be institutionally standardized in pronation or supi- nation, and always be taken at a right angle to the wrist.
The treatment approach should be individualized.
If the deformity is mild and the child older, surgical arrest of the distal radial physis may be sufficient.
Fig. 16.9 Ñ
Distal.ulna.type.2.fracture,.with.premature.closure ..This.10.year.11.month.old.girl.fell.through.a.monkey.bar.apparatus.
striking.the.left.wrist.against.a.bar.on.the.way.down ..a.The.distal.ulnar.epiphysis.is.displaced.dorsally.and.ulnarward.
(horizontal arrows) ..The.vertical arrows.point.to.the.metaphyseal.fragment.(Holland.sign) ..Manual.traction.and.reduc- tion.was.accomplished.under.general.anesthesia ..A.long.arm.cast.was.worn.30.days.followed.by.a.cock-up.splint.for.
2.weeks ..b.Two.years.post.fracture,.age.12.years.10.months,.there.is.premature.partial.ulnar.physeal.closure.and.a.few.
millimeters.of.ulnar.minus.deformity.on.the.left.(left) ..c.A.tomogram.confirms.a.physeal.bar.laterally,.but.the.portion.of.
the.physis.associated.with.the.metaphyseal.fragment.remains.open ..Surgical.arrest.of.the.distal.radius.was.performed.
at.age.13.years.7.months ..d.Four.years.1.month.post.fracture,.age.15.years.1.month,.all.physes.are.closed ..There.is.ulnar.
minus.deformity.with.ulnar.tilt.of.the.distal.radial.articular.surface ..The.patient.was.normally.active.and.asymptomatic.
with.full.range.of.motion.and.normal.grip.and.pinch.strength ..Note:.The.question.is.when.and.how.this.mild.ulnar.mi- nus.deformity.and.increased.radial.articular.angle.will.predispose.to.later.degenerative.changes ..Earlier.radial.arrest.
would.not.have.caused.significant.arm.length.discrepancy
Fig. 16.9
Prompt excision of a small physeal bar in a young child and insertion of an interposition material may reestablish growth. Results have been disappointing compared with other sites (Fig. 16.10).
More significant deformity requires combinations of distal radial physeal closure, distal radius closing wedge osteotomy and ulnar lengthening [6, 11, 23].
Ulnar lengthening by either a one-stage step cut advancement (for lengthenings of 1.5 cm or less), or gradual distraction by monolateral devices (for lengthenings of greater than 1.5 cm) work well (Fig.
16.10h–k). This may be combined with inserting staples on the radial side of the distal radial physis to correct the distal radial ulnar angulation if there is enough growth remaining. Corrective osteotomy of the distal radius may be performed if growth is complete [6]. Since the ulna is relatively easy to length- en, surgical shortening of the radius is rarely neces- sary.
Bifid Epiphysis
Occasionally, a bifid distal ulna is found following fracture [5, 11, 23]. This has some similarity to the fishtail deformity of the distal humerus (Chapter 15E).
It seems likely this would be the result of a previous type 5 fracture. Documentation of fracture type may be lacking (Fig. 16.11). A bifid epiphysis implies a malunion of at least one of the fragments. Excision of the most angulated or poorly growing portion is the best way to maintain and encourage growth of the more normal limb. Even then length discrepancy usu- ally means additional treatment, as mentioned in the section on premature closure.
Malunion
Most malunions are associated with inability to ob- tain or maintain satisfactory reduction (Fig. 16.12).
This reinforces the dictum to strive for anatomic reduction.
Fig. 16.10
Distal.ulna.type.5.fracture ..This.7.year.11.month.old.girl.
fell. on. her. outstretched. left. hand ..a. AP. (left),. lateral.
(middle),.and.oblique.views.(right).show.a.buckle.frac- ture.of.the.radial.metaphysis ..The.lateral.and.oblique.
views.show.a.peripheral.vertical.fracture.of.the.ulnar.
metaphysis.(arrow).and.an.unusual.contour.of.the.ul- nar.styloid.strongly.suggestive.of.a.type.5.fracture ..A.
short.arm.cast.was.worn.for. 6.weeks ..b.Three. weeks.
post.injury.the.radial.metaphyseal.fracture.is.healing ..
The.ulnar.physis.is.irregular.and.widened,.suggesting.
the.original.fracture.was.possibly.type.2 ..The.patient.
returned. to. normal. activities. and. had. no. difficulty .. . (Continuation see next page)
Fig. 16.10 (continued)
c.One.year.post.injury.she.sustained.a.direct.blow.to.the.left.wrist ..Roentgenographs.revealed.relative.shortening.of.
the.ulna.and.a.tilted.distal.ulnar.epiphysis,.but.no.physeal.bar ..d.Twenty-three.months.post.injury,.age.9.years.10.months ..
Scanograms.show.the.left.ulna.6.mm.shorter.than.the.right,.and.left.increased.radial.articular.angle ..The.radii.are.equal.
in.length ..e.Tomogram.shows.distal.ulna.peripheral.bar.(arrow) ..(Continuation see next page)
Fig. 16.10 (continued)
f. Three. months. following. bar.
excision.the.metal.markers.are.
6.mm. apart;. 5.mm. apart. at. . surgery ..g. Seventeen. months.
post.bar.excision,.age.11.years.
7.months,. scanograms. show.
increased. relative. shortening.
of. the. left. ulna,. recurrent. bar.
formation,. and. mild. distal. left.
radial.bowing ..h.Step-cut.ulnar.
lengthening.was.begun.at.age.
11.years. 9.months ..i. Twenty- eight.millimeters.of.length.was.
achieved.in.28.days ..(Continua- tion see next page)
Fig. 16.10 (continued)
j.The.length.was.secured.with..
2. screws. and. the. fixator. re- moved .. k. At. age. 17.years.
8.months. the. patient. is. nor- mally.active.and.asymptomatic.
and. has. full. range. of. motion ..
There. is. 1.mm. negative. ulnar.
variance .. The. ulnar. lengthen- ing.was.successful,.but.did.not.
improve. the. radial. bowing. or.
the. increased. distal. radial. ar- ticular. angle .. Hemiepiphysio- desis. on. the. radial. side. of. the.
distal. radial. physis. may. have.
improved. this .. Note:. The. fact.
that. the. physeal. bar. was. pe- ripheral.supports.the.diagnosis.
of. type.5. fracture. (compare.
with. the. physeal. bar. in. the.
type.2.fracture,.Fig ..16 .9c)
Fig. 16.11
Distal.ulna.type.4.fracture.(suspected) ..This.10.year.11.month.old.boy.injured.his.right.wrist.from.a.fall.while.rollerblad- ing ..a.Initial.roentgenographs.(forearm.pronated).show.a.torus.fracture.of.the.distal.radius.(arrow) ..The.plane.of.the..
x-ray.is.oblique.to.the.ulnar.physis.and.no.specific.fracture.is.seen ..(Continuation see next page)
Fig. 16.11 (continued)
b.Comparison.views.of.the.normal.right.wrist.show.similar.distal.ulna.physeal.features ..c.Two.years.2.months.later.
(forearms.supinated),.age.13.years.1.month,.the.right.distal.ulna.(right).has.an.obvious.central.bar.(arrow).creating.a.
bifid.epiphysis.similar.to.the.fishtail.deformity.of.the.distal.humerus ..Left.wrist.on.left ..(Continuation see next page)
Fig. 16.11 (continued)
d.MRI.confirms.the.bar.and.shows.two.healthy.physes ..e.Bar.excision.at.age.13.years.9.months.was.filled.with.fat ...
f.Within.a.month.the.bar.had.recurred.(arrow) ..g.At.age.14.years.11.months.the.recurrent.bar.was.well.established ..
(Continuation see next page)
Fig. 16.11 (continued)
h.The.more.proximal.of.the.two.physes.and.epiphyses.was.excised.and.a.step-cut.lengthening.was.fixed.with.2.screws ..
i.At.age.15.years.1.month.the.lengthening.was.healing.well ..Note:.Although.no.specific.fracture.can.be.seen.on.the.
original.films,.the.best.explanation.for.this.unusual.complication.is.the.presence.of.an.undisplaced.type.4.fracture ..A.
type.2.or.5.fracture.could.have.shown.new.subperiosteal.bone.formation.had.roentgenographs.been.taken.shortly.
after.the.fracture ..Although.a.type.4.fracture.may.have.been.found.on.roentgenographic.views.with.the.x-ray.parallel.
with.the.physis.or.on.supplemental.imaging.such.as.oblique.views,.CT.scans,.or.MRI,.these.images.were.not.warranted.
in.view.of.the.negative.initial.routine.and.comparison.views.associated.with.a.minor.radius.fracture ..This.case.was..
referred.by.Dr ..William.Garvin,.Lincoln,.Nebraska
Author’s Perspective
The distal ulna deserves the respect offered to other epiphyses. A more aggressive approach is needed to prevent distal ulnar premature arrest or malunion.
This may mean more ORIF of distal ulnar fractures,
even when the distal radius fracture can be managed
nonoperatively. The poor results of bar excision of the
distal ulna may be associated with the small total area
of the physis. Ulnar lengthening is easily accom-
plished and has fewer complications than surgical
lengthening of other bones.
Fig. 16.12
Distal.ulna.type.4.or.5.fracture,.with.malunited.bifid.epiphysis ..This.10.year.1.month.old.girl.fell.on.the.outstretched.
right.hand.while.rollerskating ..a.The.AP.view.shows.a.compression.torus.fracture.of.the.radial.metaphysis.and.abnor- mality.of.the.radial.side.of.the.distal.ulnar.epiphysis,.suggestive.of.a.type.4.or.5.fracture ..The.lateral.view.(right).shows.
a.comminuted.fracture.of.the.distal.ulna.with.epiphyseal.fragments.both.volarly.and.dorsally ..This.then.would.be.a.
double.type.4.fracture.(Poland.type.4,.Fig ..1 .3) ..b.A.short.arm.cast.was.worn.6.weeks ..History.of.attempted.reduction.
not.available ..A.large.portion.of.distal.ulnar.epiphysis.is.displaced.and.rotated.nearly.90° ..(Continuation see next page)
Fig. 16.12 (continued)
c.Four.months.post.fracture.there.is.a.bifid.epiphysis.secondary.to.malunion ..On.the.AP.view.(left).the.new.subperi- osteal.bone.on.the.ulnar.side.of.the.distal.ulnar.metaphysis.suggests.that.the.associated.epiphysis.was.displaced.sup- porting.the.diagnosis.of.an.initial.double.type.4.fracture ..The.displaced.epiphysis.seen.on.b.is.growing.70°.from.its.
normal.longitudinal.trajectory.in.a.volar.and.radial.direction ..d.CT.scan.of.both.distal.forearms.confirms.an.open.physis.
on.the.more.horizontal.of.the.bifid.projections.of.the.distal.left.ulna.(right) ..(Continuation see next page)
Fig. 16.12 (continued)
e.Nine.months.post.injury,.age.10.years.10.months,.
there.is.ulnar.minus.deformity.(right) ..The.normal.left.
is. on. the.left . f. Tomograms. confirm. open. physis. . (arrow).in.only.a.portion.of.the.more.normally.aligned.
epiphyseal.fragment ..(Continuation see next page)
Fig. 16.12 (continued)
g.Multiplane.osteotomies.were.performed ..The.more.normal.latitudinally.growing.volar.fragment.was.rotated.to.align.
longitudinally.with.the.metaphysis.and.fixed.with.one. .062.K-wire ..Portions.of.the.distally.projecting.bifid.projection.
were. excised ..h. Sixteen. months. later,. age. 12.years. 2.months,. ulnar. growth. has. occurred. and. is. keeping. pace. with.
growth.of.the.radius ..There.may.be.a.physeal.bar.on.the.radial.side.(not.at.the.site.of.the.K-wire) ..Additional.follow-up.
is.necessary ..Surgical.arrest.of.the.distal.radius.would.be.the.easiest.way.to.prevent.any.increasing.radioulnar.length.
discrepancy,.if.it.occurs
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