Physeal Bar Excision
Contents
History ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...853 Experimental Studies in Animals ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .854 Indications in Humans . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .855 Surgical Technique ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...855 Surgical.Approach... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..855 The.Final.Cavity.... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...857 The.Hematoma.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .858 Metal.Markers. .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..858 Osteotomy.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .860 Interposition Materials ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .860 Fat.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .861 Cranioplast.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .861 Cranioplast.Removal. . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .862 Silastic.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .863 Cartilage.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .863 Postoperative Care ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .863 Results: The Literature . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .863 Gender.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .864 Age.... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .864 Extremity.... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .864 Side... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .864 Site.... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .864 Location.of.the.Bar.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .871 Angulation.Correction... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..871 Size.of.Bar... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..871 Duration.of.the.Bar.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .871 Interposition.Material. ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...872 Season.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .872 Follow-up .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..872 Regeneration.of.the.Physis. . ... ... ... ... ... ... ... ... ... ... ... ... ... ... .873 Clinical.Series. ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...875 Complications . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .876 Bar.Reformation... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..876 Technical.Errors.... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...876 Postoperative.Infection.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .877 Results: The Mayo Clinic Experience.. .. . .. . .. . .. . .. . .. . .. . .. . .. ..877 The.Distal.Femur.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .880 The.Proximal.Tibia... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..881 The.Distal.Tibia.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .881 Summary. ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...881 Author’s Perspective ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .882 References . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .882
Excision (or resection) of premature partial physeal closure (a physeal bridge or bar) has also been called physolysis [15, 79], epiphyseolysis [8], epiphysiolysis [78], epiphyseodesiolysis [1, 17], and desphyseodesis [28]. The objective of bar excision is to allow the re- maining physis to resume normal growth. Several comprehensive reviews are available [43, 55, 60, 62, 64–66, 68–70, 78].
History
Before the mid 1960s, it was generally believed that growth could not be reestablished in a physis with premature partial arrest [40, 41, 52, 73]. In 1963, Salter and Harris (S-H) [73] wrote (concerning premature partial physeal closure), that “the resulting deformity is progressive until the end of the child’s growing period.”
The first record of a physeal bar excision in a hu-
man may have been by Crenshaw [16], who in 1959
excised a post fracture bar from the distal tibia of an
11-year-old girl. The case was followed 3.5 years until
maturity, and reported in 1965. The result was rea-
sonably good; angular deformity did not change, the
amount of growth was not documented. In 1967, Lan-
genskiöld [41] reported a 15-year-old boy with genu
recurvatum secondary to a bone bar in the anterior
proximal tibia; the etiology and duration of the bar
were unknown. The space of the excised bar was filled
with autogenous fat. During the 1.5-year follow-up,
the angle of genu recurvatum improved 10°, but there
was no documentation of longitudinal growth. The
first case documenting longitudinal growth was per-
formed in 1968, in the distal tibia of a 5 year 4 month
old boy [63]. Gelfoam inserted as a spacer to hold
sheet Silastic against the bone surfaces were used as
interposition materials. During a 10-year follow-up,
the involved tibia increased in length 16.7 cm, the
normal uninvolved tibia increased 18.2 cm.
Experimental Studies in Animals
Numerous animal experiments have been performed in which a physeal bar is created at a first operation, the bar is excised and an interposition material in- serted at a second operation, and the animal sacri- ficed later to observe the result. The first such experi- ment was recorded in 1957 by Friedenberg [21]. More investigations followed (Table 33.1). When no inter- position material or bone wax is inserted, a bone bar promptly reforms [1, 21, 47, 54, 56, 75]. Other interpo- sition materials used include fat [13–15, 17, 19, 42, 46, 47, 56], cartilage [1, 30, 47, 56], and various types of silicone (also known as Silastic) [5, 6, 47].
Although the results have varied, there has been enough success to confirm that a bar can be success- fully excised and growth re-established. Because of variables in the experiments, it is difficult to deter- mine superiority of one interposition material over another. Lee et al. [47] noted that in rabbits, iliac
apophysis cartilage was superior to silastic, and that fat yielded the poorest results. Large interosseous cysts that sometimes occur following fat interposi- tion, are prone to fracture [17]. A load-sharing inter- position material, such as polymethylmethacrylate, may be superior in resection of large bars in weight- bearing areas [9].
Ultraviolet visualization of tetracycline-labeled bone in rabbits has been reported to allow complete excision of experimentally created physeal arrests while minimizing excision of normal physis [71].
A study in rabbits [75] suggested that re-forma- tion of a bar after excision can be inhibited by the use of oral indomethacin without the use of an inter- position material. Indomethacin produces a nonspe- cific inhibition of osteoblastic activity that is triggered by fracture or postoperative inflammation. No clini- cal trial using oral indomethacin in conjunction with bar excision in humans has been reported. Whether indomethacin can be given in humans in sufficient doses to prevent the bone bar from re-forming, with-
Table 33.1. Excision of a physeal bar: animal experimentation
Year Authora Interposition material Animal Site
1957 Friedenberg [21] Bone wax Rabbit Distal femur
1969 Nordentoft [54] None Rabbit Proximal tibia
1972 Österman [56] None Rabbit Distal femur
Fat Cartilage Bone wax
1974 Bright [6] Silicone-rubber Dog Distal femur
Silicone adhesive Isobutyl cyanoacrylate
1982 Sudmann [75] None Rabbit Distal femur
1986 Alford [1] None Rabbit Distal femur
Fat Cartilage
1986 Langenskiöld [46] Fat Pig Proximal tibia
1987 Kawabe [30] Cartilage Rabbit Proximal tibia
1991 Foster [20] Fat Sheep Proximal tibia
1992 Cady [12] None Rabbit Distal femur
Fat
1993 Delgado Baeza [17] Fat Rat Proximal tibia
1993 Lee [47] None Rabbit Proximal tibia
Fat Cartilage Silastic
a Some articles have more than one author; see References
out inhibiting normal bone growth, remains to be seen.
Indications in Humans
There must be growth potential in the remaining physis. Without it, there is no point in excising the bar. Most authors suggest that there be two years of growth remaining. Langenskiöld [39] recommended only 1 year need remain. Other authors specify the amount of growth remaining should be a linear mea- surement, for example 2.5 cm [29]. This, of course, would depend on the physis involved, since a 1 cm gain in a bone such as the distal radius or ulna could have a very desirable effect. Determination of growth remaining, even using bone age films and charts, is subject to varying maturation patterns among chil- dren.
In general, excision of bone bars of greater than 50% of the area of the physis are unsuccessful in rees- tablishing meaningful growth. However, if a young child has a central bar in a physis destined to have significant growth, such as the distal femur or proxi- mal tibia, a bar excision could be offered [43]. Some have been successful. If unsuccessful, all other meth- ods of management would be available.
Angulatory deformity correction following bar ex- cision is usually nil to modest, though up to 20° im- provement have been noted in some cases [32, 36, 46].
However, any improvement in angular deformity may make the magnitude of corrective osteotomy less. The presence or absence of angulatory deformity associ- ated with a bar is not an indication for or against bar excision.
Even if the bone with the bar is significantly short- er than its normal counterpart, reestablishing growth by bar excision can have a positive effect and lessen the magnitude of other procedures.
Surgical Technique
The objectives of surgical excision of a bone bar are to remove the bar completely and to preserve as much of the remaining normal physis as possible. This re- quires careful preoperative evaluation and planning, and knowledge of surgical anatomy [2, 3]. The surgi- cal excision may be challenging if the bar is irregular or the epiphyseal/metaphyseal complex is deformed (Fig. 31.14). A tourniquet is used whenever possible.
Surgical Approach
Peripherally located bars (Fig. 31.19) are approached directly from the periphery (Fig. 33.1). Any perioste- um overlying the bar is excised in an effort to prevent subsequent bar re-formation [43]. The bar can then be removed under direct vision, until normal physis is visible on all sides of the cavity. Optical loupes are helpful [43] and ordinary surgical light is satisfactory.
The bone bar is removed initially using an osteotome, curet, and rongeur. The final exposure of the normal physis is done more precisely with a motorized burr [43]. This allows excellent visualization of the physis, removal of as little metaphyseal bone as necessary, and facilitates contouring of the cavity in the epiphy- sis. The heat generated by the burr has no apparent deleterious effect on the viability of the remaining physis.
Centrally located bars have normal physis periph- erally and an intact perichondrial ring of Ranvier (Fig. 31.20). These must be preserved. This requires approaching the bar through the metaphysis by re- moving a window of cortical bone and cancellous me- taphyseal bone to expose the bar from inside out (Fig. 33.2). The cortical window is outlined by multi- ple drill holes and completed with a narrow osteo-
Fig. 33.1
Peripheral. bar. excision ..a. Peripheral. bar. in. AP. view .. . b.Bar.removed.directly.to.normal.physis.with.a.motor- ized.burr ..c.Cavity.filled.with.fat ..(Redrawn.from.Peter- son.HA.[65],.with.permission)
tome (Fig. 33.3). Accessory drill holes are made in both the window and adjacent cortex for suture place- ment to secure the window during closure. The me- taphyseal cancellous bone is removed with a rongeur or curet and saved for use during closure. The bar is removed with a motorized burr. Headlamp light to illuminate the depth of the excision is beneficial. A roentgenograph is taken to ensure the entire bar has been removed and that the burr is not too deep within the epiphysis (Fig. 33.4).
Combined peripheral and central bars (Fig. 31.21) must be carefully evaluated with maps to determine the surgical approach, either from the periphery or through a metaphyseal window, depending on the lo- cation, position, and the extent of the bar.
Modifications of and supplemental procedures to these basic techniques have been reported. Osteotomy of the metaphysis adjacent to the physis allows a di- rect access to the bar [27]. However, this adds another component to the operation which affects the opera- tion and the postoperative care, and may directly or indirectly negatively affect the outcome. The use of an arthroscope in the resection cavity of a central bar may allow a reduction in the size of the metaphyseal window and aid in visualizing the normal remaining physis [36, 39, 44, 57, 74, 78, 79]. An operating micro- scope has been used by some surgeons [36, 37, 39, 43, 44, 78]. Inserting a guide wire through the metaphysis into the center of the bar under x-ray control, has been followed by removing the bridge with a cannulated
Fig. 33.2
Central. bar. excision ..a. Bar. in.
center.with.growth.peripheral- ly.results.in.cupping.or.tenting.
of.the.physis ..b.A.circular.win- dow.of.cortex.is.removed.from.
the. metaphysis. using. a. drill.
and. multiple. drill. holes .. Extra.
holes.are.for.suturing.cortex.in.
place.during.closure ..c.Cancel- lous.bone.from.the.metaphysis.
is.removed.with.rongeurs.and.
curettes. and. saved .. The. bar. is.
removed.with.a.motorized.bar ..
Normal. physis. is. visualized.
with.a.dental.mirror ..d.The.in- terposition. material. (here. cra- nioplast). is. inserted,. followed.
by.the.cancellous.metaphyseal.
bone.and.cortical.window ..(Re- drawn. from. Peterson. HA. [65],.
with.permission)
reamer [80]. Bar excision combined with physeal dis- traction is discussed in Chapter 34. I have not found these modifications necessary and have no personal experience with them.
The Final Cavity
The final cavity is carefully inspected to ensure that the entire bar has been removed. Normal physis must be visualized circumferentially within the cavity. A fine surgical light is helpful. A small (5 mm diameter) dental mirror is an excellent adjunct (Fig. 33.5).
Roentgenographs are taken to confirm that the entire bar has been removed and that epiphyseal bone has not been excessively removed. The exposed normal
physis should be flat and smooth (Fig. 33.1b). Enlarg- ing the cavity in the epiphysis into the shape of a col- lar button may retain the interposition material with- in the epiphysis (Fig. 33.2c) [62], but this has not proven to enhance results. Care must be taken not to weaken the epiphysis, predisposing it to fracture [39].
Removing metaphyseal and epiphyseal bone to leave the physis protruding in the cavity, is an effort to en- sure contact of the physis to the interposition material and reduce the likelihood of bar reformation [7, 55].
However, the protruding physis is thereby deprived of its blood supply. Heikel [25] has shown in rabbits that dead physeal cartilage may be replaced by regenera- tion from surviving adjacent physeal cartilage.
Fig. 33.3
Intraoperative. photograph. showing. an. osteotome.
connecting. drill. holes. in. preparation. for. window. re- moval ..Extra.drill.holes.within.and.outside.the.center.
circle.are.for.suturing.the.window.in.place.during.clo- sure
Fig. 33.4
Anteroposterior.roentgenograph.of.distal.femur.of.an.
11.year.0.month.old.boy.taken.at.time.of.bar.excision.
to.document.the.depth.of.the.burr.within.the.epiphy- sis,.removal.of.the.bar,.and.presence.of.remaining.nor- mal.physis ..The.fracture.and.evaluation.of.this.patient.
is.shown.in.Fig ..31 .18 ..Follow-up.is.shown.in.Fig ..33 .17 ..
(From.Peterson.[61],.with.permission)
The Hematoma
Even under tourniquet control the exposed bone sur- faces will ooze blood. The blood can push soft tissues, such as fat, aside, and produce a hematoma which or- ganizes and forms a recurrent bar. Prevention of bar reformation requires preventing a hematoma in the
cavity [10]. Langenskiöld recommended deflating the tourniquet and waiting for the bone bleeding to stop before inserting the fat [43]. A liquid thrombin so- lution (Fig. 33.6) may be inserted into the cavity (Fig. 33.7), or applied topically to the bone surface [37]. Bone wax pressed against the bone surface is also commonly used to reduce bleeding [12, 78, 79]. Silas- tic and cranioplast provide hemostasis by completely occupying the cavity, filling the cancellous interstic- es, thereby preventing a hematoma from forming.
Metal Markers
Metal markers are placed in the metaphysis and the epiphysis to allow accurate radiographic measure- ment of subsequent growth (Fig. 33.8) [65]. Growth of the physis at the other end of the bone can also be measured. These markers are placed in cancellous bone, not in contact with the cavity to avoid attach- ment to the interposition material, or if fat is used to prevent the marker from becoming loose in the cavity.
Marker position at the center of the bone is preferable because eccentric markers may become extraosseous due to growth and metaphyseal remodeling. Any metal marker will do; half of a vascular clip (stainless steel or silver), was commonly used in early cases.
Transversely oriented longitudinal markers (pins, wires, etc.) parallel with each other and with the phy- sis, one in the metaphysis and one in the epiphysis, also allow accurate assessment of angular change [62].
Titanium markers avoid artifact on subsequent MRI evaluation. After trying many metal markers our preference was a titanium 0.062 Kirschner-wire, notched 10 mm from one end (Fig. 33.9) so that after it was placed in the desired position, the embedded end could be broken off by wiggling the longer pro- truding end (Fig. 33.10) [34].
Fig. 33.5
A. 5-mm-diameter. dental. mirror. is. used. to. visualize.
normal.physis.circumferentially.in.the.cavity ..(Redrawn.
from.Peterson.[65],.with.permission)
Fig. 33.6
Liquid.thrombin.and.diluent
Fig. 33.7
Insertion. of. liquid. thrombin.
into.the.cavity
Fig. 33.8
Metal.markers ..a.Coronal.tomogram.of.the.distal.femur.
of.a.4.year.11.month.girl.with.a.central.bar.of.the.distal.
femur .. The. bar. was. excised. and. K-wires. inserted. as.
markers ..b. Six. months. post. bar. excision,. age. 5.years.
5.months,.the.metal.markers.are.28.mm.apart.and.the.
physis.is.open ..c.Four.years.post.bar.excision.the.mark- ers.are.83.mm.apart ..This.represents.a.gain.in.excess.of.
55.mm,.since.the.growth.in.the.first.six.months.follow- ing.surgery.was.not.documented ..A.scanogram.should.
be.taken.immediately.after.surgery.for.accurate.docu- mentation.of.growth ..The.physis.has.grown.away.from.
the.cranioplast,.leaving.it.in.the.junction.of.the.diaphy- sis.with.the.metaphysis ..The.angle.relationship.of.the.
markers.to.each.other.has.not.changed ..The.physis.is.
normal ..(Further.details.of.this.case.are.documented.in.
Peterson.HA.[65],.with.permission)
Metal markers placed in both the operated bone and the normal contralateral bone [28], allows more accurate assessment of growth. Failure of the markers to become farther apart is confirmation of recurrent bar formation.
Osteotomy
The need for osteotomy to correct accompanying an- gular deformity will depend on the degree of angula- tion, the age of the patient, and the site. Mild angular deformity, particularly those secondary to peripheral bars, may correct spontaneously with growth after excision of the bar [36]. Angular deformities of more than 20 degrees will probably not correct spontane- ously and usually require osteotomy [79]. This can be done at the same time as bar excision, or later. Fifty- three of Bright’s [7] 100 bar excisions had concurrent corrective osteotomy. Concurrent osteotomy adds an- other component to the operation which affects the operative treatment, the postoperative management, and the assessment of bar reformation, if it occurs.
The best chance of success is bar excision without os- teotomy. In some cases, the deformity corrects com- pletely negating the need for osteotomy, or corrects partially making the final osteotomy less difficult. In addition, in cases in which the bar and the deformity recur, a second osteotomy might then become neces- sary. In general, osteotomy is best performed at the conclusion of growth, combined with bone lengthen- ing or shortening, as needed.
Interposition Materials
The object of inserting an interposition material into the resected cavity is to fill the cavity to prevent blood from occupying the cavity, organizing, and re-form- ing a bone bar. Autogenous fat [1, 8, 15, 29, 35–41, 43–48, 53, 55, 57–59, 77, 80, 81], Silastic [4, 7, 26, 76, 77], cranioplast [31, 32, 60, 62, 64–66, 68–70], poly- methylmethacrylate [49, 50], and various types of cartilage [1, 30, 47, 56] have been the most popular interposition materials. Combinations of materials have also been used: bone wax and fat [12, 78, 79], and sheet Silastic held against the cavity wall by Gelfoam [63] or methylmethacrylate [33].
Fig. 33.9
This.is.a.0 .062.titanium.Kirsch- ner. wire. notched. 10.mm. from.
one.end
Fig. 33.10
The.proximal.wire.was.properly.placed.and.the.pro- truding.portion.broken.and.removed ..The.distal.wire,.
intended.for.placement.in.the.epiphysis.is.too.distal ..It.
was.removed.and.replaced.in.the.epiphysis ..The.distal.
tibial.bar.and.the.deformity.of.the.os.calcis.are.due.to.
the.underlying.diagnosis.of.congenital.insensitivity.to.
pain
Fat
Fat has the distinct advantage of being autogenous.
The fat is often harvested from the area of the existing incision. Langenskiöld [36] preferred buttock fat be- cause of its more firm and globular consistency. This requires appropriate draping to expose the buttock, and in some instances an intraoperative change of pa- tient position. It also adds 15–20 minutes to the pro- cedure; a financial consideration if anesthesia charges are by time increments. Fat has the disadvantage of a lack of hemostasis in the resected cavity. When the tourniquet is released, fat tends to float out of the cav- ity. Applying a thrombin solution or a thin layer of bone wax to the sides of the exposed cavity prior to tourniquet release, reduces blood flow into the cavity [37]. Langenskiold [36, 46] recommended suturing ligament, muscle, or subcutaneous tissue over the transplanted fat to keep it in place. Closing perioste- um over the cavity to contain the fat predisposes to new bone formation peripherally. The fat-filled oper- ative defect weakens the structure of the bone, and a cast is recommended to protect a weightbearing bone from fracture [80]. Weightbearing is deferred 8–12 weeks, depending on the site and size of the de- fect and the age of the patient [55].
The fate of the fat is not known in detail [43, 59].
Shortly after surgery it has been noted to be necrotic [59]. Later on, its histology becomes more normal, but with some fibrotic tissue [59]. Usually it persists as a living tissue [37]. When fat grafts work well, the intra- operative cavity enlarges, in particular elongating as the bone grows in length [1, 28, 40, 44–46]. Langen- skiöld [38, 46] found in pigs that cavities implanted with fat “enlarged 2 to 4 times their original size,” and were completely filled with living adipose tissue. As this lucent defect increases in size, the margins be- come more evenly and smoothly sclerotic [1]. Dense bone surrounds the radiolucent defect [45]. This com- pensates for the weakness of the cavity. This fat-filled interosseous cyst may predispose to pathologic frac- ture [17, 39, 43, 45]. Following closure of the physis at the end of growth, the lucent defect no longer increas- es in size [1] and gradual ossification of the cavities seems to occur [9, 39, 43]. However, Langenskiöld re- corded “two adult patients in which the fat grafts en- larged during the growth periods, and remained as adipose tissue for years” [9, 37], possibly for more than a decade [45]. The final fate of large cavities left be- hind in the metaphysis is not yet clear [44]. There are no reports of bone grafting surgery of these fat filled cysts.
Recurrent bone bridges are common [17]. Failure of the fat to maintain its position, hemorrhage at the bone/fat interval, and failure of the fat to survive, are the leading causes of recurrent bridges [13, 14, 20].
Cranioplast
Polymethylmethacrylate (PMMA), an autopolymer- izing acrylic resin, was produced in 1927 [72] and first used to repair crania in humans by Zander in 1940 [11]. Its thermogenic properties are minor, as evidence by the neurosurgical practice of placing it directly on the dura prior to polymerization. It has been used for over 6 decades by neurosurgeons to repair skull de- fects and has been found to be an inert and safe mate- rial. When used as an isolated substance, it has caused no rejection, infection, or neoplastic change [11]. Pure methylmethacrylate is trademarked as Cranioplastic®, manufactured by LD Caulk Co, Milford, DE, USA, distributed by Codman and Shurtleff, Randolph, MA, USA (Fig. 33.11), and remains in common neurosur- gical use.
As an interposition material cranioplast has sev- eral desirable qualities. It is easily available, inexpen- sive, and there is no Food and Drug Administration (FDA) control (as for Silastic). Both the liquid (mono- mer) and the powder (polymer) are sterile as packaged and can be mixed in the operating room. It is unnec- essary to take cultures (as for Silastic). It is light, easy to handle and mold. In a cavity that is gravity de-
Fig. 33.11
Cranioplast,.polymer.(left).and.monomer.(right)
pendent, cranioplast may be poured in a liquid state (Fig.33.12). If the cavity is not in a dependent position, cranioplast is placed in a syringe and pushed into the defect through a short polyethylene tube (Fig. 33.13).
Alternatively, cranioplast may be allowed to partially set and then pushed into the defect like putty. It pro-
vides hemostasis by virtue of occupying the entire desired position of the cavity. It cures quickly with minimal heat into a solid mass with a porous matrix [72]. After the cranioplast has set, the rest of the me- taphyseal cavity is filled with previously removed cancellous bone followed by the cortical window (Fig. 33.2d). No second incision is needed (as for fat).
Cranioplast is strong, so that no postoperative immo- bilization is necessary. Weightbearing is allowed on the day of surgery. It is especially useful as a load- sharing interposition material following excision of large bars in weightbearing sites [9, 22, 80]. It is radio- lucent and thereby does not obstruct visualization of a developing recurrent bar. There are no apparent side effects [11].
Misunderstandings concerning the term “methyl- methracrylate” are related to terminology and to mul- tiple substances added to the PMMA by different companies [51, 60]. In the 1970s when initial results from total hip arthroplasty revealed prosthesis loos- ening, a search for a bone cement was undertaken.
Cranioplast was found to work well, but the radiolu- cent property made subsequent prosthesis loosening difficult to assess. A radiopacifier, such as barium sulfate or zirconium oxide, was added to the methyl- methacrylate. This achieved radiopacity, but it in- creased the exothermic property and decreased the setting time. Thus, the material that is now generally referred to as methylmethacrylate or PMMA, has ad- ditives, which cranioplast does not have. PMMA with these additives is undesirable as an interposition ma- terial for bar excisions because the radiopacity obvi- ates detection of recurrent bar formation, and possi- bly because of its exothermic property.
Cranioplast Removal
Cranioplast plugs become embedded firmly in the bone. There has been no loosening, such as occurs when methylmethacrylate is used with a joint replace- ment. They do not “shell” or “toggle out.” The few that were removed required cutting around them with an osteotome. Histologic evaluation revealed a thin surrounding layer of fibrous tissue and no untoward reaction. Burring the cranioplast from its center to its periphery was found to be the least intrusive method of removal.
When the physis grows away from the cranioplast, the bone remodeling causes cranioplast to be located in the metaphysis or diaphysis. The cranioplast, al- though remaining the same size, occupies a greater proportion of the transverse plane of the shaft of the bone (compare Fig. 33.8b and c). With marked re-
Fig. 33.12
Liquid.cranioplast.gravity.dependent.insertion.into.a.
bar.excision.cavity
Fig. 33.13
Insertion.of.cranioplast.by.use.of.a.syringe.and.cathe- ter
modeling or with a peripheral bar, the cranioplast may extrude and become extraosseous.
After initially removing a few cranioplast plugs it was elected to leave them in situ. The only complica- tion encountered was a fracture following removal of cranioplast from its diaphyseal location in a femur (Fig. 33.18k). The author’s practice is to not remove the cranioplast, although patients should be advised that it might have to be removed at a later date. No complications have occurred from leaving the cranio- plast in situ.
Silastic
Silastic has many properties similar to cranioplast, and was used frequently [4, 7, 26, 48, 76] prior to its withdrawal from commercial markets by Dow Corn- ing in 1987. The ability to mold and anchor the Silastic over a K-wire in the epiphysis, maintaining its posi- tion in the epiphysis, is an advantage over fat [48, 76].
Silastic was FDA controlled and its use required an in- vestigation number [81]. Intraoperative cultures of the Silastic were recommended [81]. It did not harden like cranioplast and remained soft, allowing a potential source of fracture. Removal of the Silastic after growth was complete was recommended [7]. Several Silastic products were used. Results were superior with sili- cone rubber (Silastic No. 382), compared with silicone adhesive, or isobutyl cyanoacrylate [7].
Cartilage
Since the tissue to be replaced during bone bar exci- sion was originally cartilage, it is reasonable to as- sume that cartilage, preferably physeal cartilage, would be the ideal interposition material. Possible sources of cartilage are another physis, an apophysis such as the iliac crest, and laboratory-procured chon- drocyte allograft transplants. There are technical dif- ficulties procuring and inserting another physis. In addition, taking normal healthy physis from another part of a human body to replace a damaged physis has severe limitations. Apophyseal cartilage, for example from the iliac crest or scapular edge, may not have the same growth potential as epiphyseal cartilage. Chon- drocyte allograft transplants require initial cartilage procurement, followed by laboratory time for the car- tilage matrix to develop. There are immune response problems if the transfer is from one human to anoth- er. It is hoped that more investigations will solve these problems in the near future. Multiple possibilities for the use of cartilage as an interposition material are discussed in Chapter 35.
Postoperative Care
Postoperatively, if cranioplast is inserted and no oste- otomy is performed, no cast or other immobilization is necessary [62]. Joint motion and weightbearing are encouraged on the day of operation, or as soon as op- erative discomfort subsides. Regardless of the inter- position material used, follow-up up until maturity is essential. Reestablished physeal growth may cease at any time [55] (see Complications: Bar Reformation).
Results: The Literature
Analyzing results of individual cases is difficult be- cause so many factors are involved [60, 62]. The site, size and duration of the bar, the age of the patient, the interposition material used, and length of follow-up, are paramount factors, and make comparison of case series even more difficult. Criteria for expressing re- sults vary widely, and have included descriptive ana- tomic changes as well as designations such as: 1) suc- cess or failure [4, 8, 40, 48, 53], 2) definite benefit or questionable [39, 43, 44], 3) lasting improvement or complete correction avoiding further surgery [15], 4) resumption or no resumption of growth [12, 78], 5) no, partial, full and over-correction [35], 6) excellent, good, fair, and poor [26, 76, 81], and 7) as a percentage of growth of the contralateral normal bone [48, 60, 62, 64–66, 68–70].
This renewed growth may diminish or stop the rate of progression of limb-length inequality and the angular deformity [36, 43]. Occasionally, the length inequality even gets less, signifying that the treated limb is growing faster than the normal limb [35].
When the procedure works well, it is most gratifying and may be the only procedure needed.
Only patients followed to maturity should be in- cluded in any reported series [44]. Maturity of all pa- tients is not present in most reported series. Some physes, although growing well after the procedure, close earlier than their contralateral physes [32]. Thus, in some patients, surgical arrest of the contralateral physis is performed toward the end of growth to ne- gate additional length discrepancy. Failure to account for secondary procedures, such as contralateral phy- seal arrest, in the final assessment favorably influ- ences the result expressed as a percentage.
The question of growth at the end of the bone op- posite the bar excision is relevant to the final result.
There is a concept that when a physis is prematurely
closed (traumatically or surgically) the physis at the
opposite end of the bone is stimulated and exhibits compensatory overgrowth. Experimenting with rab- bits, Hall-Craggs [24] confirmed this concept, Heikel [25] rejected it. Conversely, when a bar is excised there frequently is increased growth of that bone in the first few months [28], like a dam bursting, followed by a return to normal growth (Fig. 33.16e), or less than normal growth. It is difficult to determine if this ac- celerated growth is all from the site of bar excision, or whether some of the increase in bone length is due to compensatory overgrowth at the opposite physis. The only way to determine this would be to place metal markers in both the ipsilateral and contralateral bones at the time of bar excision. My personal feeling is that any overgrowth at the physis opposite a bar excision is a minor phenomenon at best.
Gender
The gender in patient series of bar excisions is not al- ways reported. In those series in which it is reported, the ratio of boys to girls is approximately 2:1 (Ta- ble 33.2), similar to the 2:1 ratio of all physeal frac- tures (Table 4.10). This suggests there is no gender preference for bar formation following physeal frac- ture.
Age
The mean age at time of bar excision varied from 9.4 years [4, 26] to 12 years 7 months [81]. The young- est patient reported was 11 months old [7]; the oldest 16 years [7, 44, 57, 81]. Bar excisions are performed
mostly in mid-age children because: 1) the fracture rate responsible for the bar begins to rise (Fig. 4.2), 2) the bar takes time to develop after the fracture, and 3) a patient undergoing bar excision should have at least 2 years or 2 cm of growth to make the procedure worth while. Therefore older teenagers are not good candidates. Results were superior in younger children in one study [76].
Extremity
Although 70% of physeal fractures occur in the upper extremity (Table 4.3), only 13% of bar excisions occur in the upper extremity (Table 33.3). It is not known if premature physeal arrest occurs less frequently in the upper extremity, but it is safe to say that fewer bar ex- cisions are performed in the upper extremity than in the lower extremity (87%, Table 33.4). The reason for this is undocumented, although the desire and need for equal bone length and proper joint angle is less in the upper extremity than in the lower extremity.
Side
Of 100 consecutive bar excisions (not all due to frac- ture) by Bright and 19 associated surgeons [7], 54 were on the right side and 46 were on the left.
Site
In the upper extremity, the distal radius is the site of 62% of upper extremity bar excisions (Table 33.3).
Successful (Fig. 33.14), partially successful (Fig. 10.14), and unsuccessful (Figs. 10.11, 10.12, 10.15, 10.16), re- sults have been obtained. Macksoud and Bright [48]
reported 21 distal radial bar excisions. Bar excisions of the smaller physes, such as the distal ulna, proxi- mal radius, metacarpals, and hand phalanges are technically more difficult and results are not well re- corded.
In the lower extremity, the distal femur accounts for 43% of bar excisions (Table 33.4). Considering both the upper and lower extremities, it accounts for 37% of all bar excisions. Although physeal factures of the knee (distal femur and proximal tibia) account for only 2–6% of all physeal fractures (Tables 4.5, 4.6), the knee accounts for 63% of all bar excisions (Ta- ble 33.4). These are the largest physes in the body, making bars in these locations more easy to assess and surgically remove. They provide the greatest amount of growth, making bar removal more benefi- cial to the patient.
Table 33.2. Physeal. bar. excisions. in. humans. by. gender:.
.literature.reviewa
Year Authorb Boys Girls Total
1979 Langenskiöld.[44] 17 8 25
1980 Vickers.[79] 6 4 10
1981 Kvidera.[35] 7 4 11
1982 Bright.[7] 60 38 98
1989 Broughton.[8] 7 6 13
1990 Williamson.[81] 13 9 22
1992 Cady.[12] 7 1 8
2000 Klassen.[31] 65 33 98c
ToTal 182 103 285
Percent . 63 .9 . 36 .1 100 .0
a.Most,.but.not.all,.bars.resulted.from.fracture
b.Most.articles.have.more.than.one.author;.see.References
c. .These. 98. cases. include. cases. reported. by. Klassen. and.
.Peterson.in.1976.(6.cases).[33].and.1982.(37.cases).[32]
Table 33.3. Physeal.bar.excision.in.humans.by.site:.literature.review.of.upper.extremitya YearAuthorbInterposition materialDistal radiusDistal ulnaHandProximal humerusProximal radiusDistal humerusTotal upper extremityTotal upper and lower extremities 1980Vickers.[79]Bone.wax.and.fat1110 1982Bright.[7]Silicone.rubber6129100 1983Langenskiöld.[43]Fat32529c 1988Hume.[26]Silastic2229 1989Broughton.[8]Fat1113 1990Williamson.[81]Fat.or.Silastic311522d 1992Cady.[12]Bone.wax.and.fat339 1998Peterson.[70]Cranioplast1553326178e 1999Dunn.[18]Fat.or.cranioplast09 ToTal336652153408 Percent.in.the.upper.extremities62 .311 .311 .39 .43 .81 .9100 Percent.in.the.upper.and.lower.extremities.8 .1.1 .5.1 .51 .20 .50 .2.13 .1 a.Series.of.5.cases.or.less,.and.of.only.one.site.are.not.included ..Most,.but.not.all,.bars.resulted.from.fracture b.Most.articles.have.more.than.one.author;.see.References c..These.29.cases.are.due.only.to.fracture.and.probably.include.the.same.cases.reported.by.Langenskiöld.in.1975.(11.cases).[36],.in.1981.(28.cases).[39],.and.by.Langenskiöld.and. Osterman.in.1979.(25.cases).[44] d.These.22.cases.probably.include.the.same.11.cases.reported.by.Kvidera.and.Staheli.in.1981.[35] e..These.178.cases.include.the.same.cases.reported.by.Klassen.and.Peterson.in.1976.(6.cases).[33],.1982.(37.cases).[32],.1987.(97.cases).[67],.1990.(114.cases).[64],.1993.(130.cases).[62],. and.2000.(98.cases).[31]
Table 33.4. Physeal.bar.excision.in.humans.by.site:.literature.review.of.lower.extremitya YearAuthorbInterposition materialDistal femurDistal tibiaProximal tibiaFootDistal fibulaProximal femur Pelvis trir
adiateTotal lower extremityTotal upper and lower extremities 1980Vickers.[79]Bone.wax.and.fat351910 1982Bright.[7]Silicone.rubber362722691100 1983Langenskiöld.[43]Fat155312429c 1988Hume.[26]Silastic741512729 1989Broughton.[8]Fat6331213 1990Williamson.[81]Fat9621722d 1992Cady.[12]Bone.wax.and.fat5169 1998Peterson.[70]Cranioplast6152295221152178e 1999Dunn.[18]Fat.or.cranioplast62190 ToTal1511058012331355408 Percent.in.the.lower.extremities.42 .7.29 .7.22 .6.3 .10 .80 .80 .2100 .0 Percent.in.the.upper.and.lower.extremities.37 .0.25 .7.19 .6.2 .90 .70 .70 .2.86 .8 a.Series.of.5.cases.or.less,.and.of.only.one.site.are.not.included ..Most,.but.not.all,.bars.resulted.from.fracture b.Most.articles.have.more.than.one.author:.see.References c..These.29.cases.are.due.only.to.fracture.and.probably.include.the.same.cases.reported.by.Langenskiöld.in.1975.(11.cases).[36],.1981.(28.cases).[39],.and.by.Langenskiöld.and.Oster- man.in.1979.(25.cases).[44] d.These.22.cases.probably.include.the.same.11.cases.reported.by.Kvidera.and.Staheli.in.1981.[35] e..These.178.cases.include.the.same.cases.reported.by.Klassen.and.Peterson.in.1976.(6.cases).[33],.1982.(37.cases).[32],.1987.(97.cases).[67],.1990.(114.cases).[64],.1993.(130.cases).[62],. and.2000.(98.cases).[31]
Fig. 33.14
Distal.radius.bar.excision.and.reexcision ..a.Displaced.type.3.fracture,.distal.right.radius.(forearm.pronated),.in.a.9.year.
6.month.old.girl.who.fell.from.a.swing ..b.Closed.reduction.under.general.anesthesia.and.application.of.a.long.arm.cast ..
c.One.week.post.fracture.mild.dorsal.redisplacement.was.remanipulated.and.recasted ..Seven.weeks.post.fracture.
physical.therapy.was.begun ..(Continuation see next page)
Fig. 33.14 (continued)
d.One.year.post.fracture,.age.10.years.6.months,.a.prominence.of.the.distal.ulna.was.noted.clinically,.and.relative.short- ening.of.the.radius.noted.roentgenographically ..e.Tomograms.revealed.a.mature.central.bar ..Scanograms.showed.the.
right.radius.5.mm.shorter.than.the.left ..f.At.age.10.years.8.months.the.bar.was.excised.through.a.dorsal.approach ..The.
distal.metal.marker.(half.of.a.silver.vascular.clip).was.in.the.dorsal.rim.of.the.epiphysis.(right),.and.was.replaced.more.
proximally.to.avoid.doubt.of.its.epiphyseal.position.on.the.AP.view.(left) ..Estimated.physis.remaining.at.conclusion.of.
excision.was.50% ..(Continuation see next page)
Fig. 33.14 (continued)
g.After.inserting.cranioplast.and.replacing.the.cortical.
window,.the.metal.markers.were.25.mm.apart ..h.One.
year.postoperative,.age.11.years.8.months,.the.physis.
is.open.and.has.grown.away.from.the.proximal.marker ..
The.markers.are.now.33.mm.apart ..The.positive.ulna.
variance. is. less .. Scanograms. show. the. right. radius. is.
4.mm.shorter.than.the.left ..The.right.radius.is.growing.
faster.than.the.ulna.and.the.left.radius ..i.At.age.12.years.
a.recurrent.physeal.bar.was.present.(left),.confirmed.by.
tomogram.(right) ..(Continuation see next page)
Fig. 33.14 (continued)
Location of the Bar
Physeal bars can be located in any area of the physis, expressed as central or peripheral, or as a quadrant (for example posterior-medial), or any combination thereof. Although good, and not so good, results have been attained from bar excision in any location, there is a general feeling that the procedure is most effective for bars affecting only the central area of the plate [8, 76]. This may be associated with less good regenera- tive powers of the ring of Ranvier, which is involved in peripheral bars.
Angulation Correction
Langenskiöld has shown angular deformities of 20°
correcting to normal following bar excisions in the finger middle phalanx [36] and in the distal femur [36, 46]. Of 37 cases reported by Klassen and Peterson [32], the extremity angulation remained unchanged in 25 cases (some had no deformity at time of bar ex- cision), decreased 5–22° in 9 cases, and increased 2–
10° in 2 cases. Vickers [79] has provided schematic drawings showing progressive angular correction fol- lowing bar excision. Williamson and Staheli [81] rec- ommended concurrent osteotomy with deformities greater than 10°, particularly with bars >25% in area.
Size of Bar
Bridge size correlates inversely with results. Bar exci- sions of bars of <25% of the total area of the physis were uniformly (100%) excellent, and generally poor (no growth) in bridges >50% in one series [81].
It is generally accepted that excision of bars 50% or more of an entire physis usually fail to restore satis- factory longitudinal growth [10, 32, 81]. Bars more than 50% of the physis may be excised in very young children because the alternatives are undesirable, the
procedure occasionally provides some meaningful growth making subsequent procedures less difficult, and if it is unsuccessful, all other methods of manage- ment can still be used [70]. Langenskiöld and Öster- man [43] noted “good results” from excision of bars greater than 50% in the distal femur and proximal tibia when the bars are central rather than peripheral.
In Bright’s series [7] of 98 patients, the smallest bar excision was 5%, the largest 70%, and the mean 29%.
In Klassen and Peterson’s series [32] of 37 patients, the bars ranged from 5% to 50%. There is a correlation between the size of the bar removed and the eventual amount of longitudinal growth. The smaller the bar the better chance of success [8]. Excision of peripheral bars of <17% of the physis are likely to be successful [19].
Duration of the Bar
The interval between the date of fracture and date of bar excision is not necessarily synonymous with the duration of the bar. The developing bridge in the growth plate initially consists of fibrous tissue, per- mitting longitudinal growth for a variable time. Dur- ing the following calcification of the fibrous scar, growth continues (decreasingly) until solid bone de- velops between the epiphysis and metaphysis, result- ing in complete growth arrest [28]. When the interval between fracture and bar excision is long, e.g., years, the duration of the bar is often unknown, because the bar could have occurred at any time during the inter- val. This information is not commonly documented in the literature, and may correlate with the result (see summary of the Mayo Clinic experience at the end of this chapter). Assumably, the shorter the duration of the bar, the better the result [76]. However, Langen- skiöld and Österman [43] noted “some success” from a distal femoral bar excision undertaken 7 years after the fracture.
É Fig. 33.14 (continued)
j.The.recurrent.bar.was.reexcised.through.a.volar.approach ..The.original.cranioplast.was.removed.and.new.cranioplast.
inserted ..The.estimated.physis.remaining.was.60%.(the.recurrent.bar.was.smaller.than.the.original.bar) ..The.metal.
markers.were.not.disturbed ..k.Twenty-three.months.after.the.second.bar.excision,.age.14.years.4.months,.the.markers.
are.48.mm.apart,.a.gain.of.an.additional.15.mm.from.the.second.excision.and.23.mm.from.the.first.excision ..The.ulnar.
variance.has.not.changed.appreciably ..Scanograms.show.the.right.radius.is.11.mm.shorter.than.the.left ..The.patient.is.
normally.active,.plays.competitive.volley.ball,.and.is.asymptomatic ..The.parents.declined.consideration.for.distal.ulnar.
physeal.arrest ..She.was.left.with.a.3.mm.ulnar.plus.deformity ..Note:.It.is.difficult.to.assess.the.need.for,.and.the.timing.
of,.physeal.arrest.of.the.ulna.because.the.rate.of.distal.radial.growth.gradually.diminishes,.perhaps.at.a.greater.rate.
after.bar.excision ..The.two.bar.excisions.in.this.case.are.less.involved.procedures,.less.traumatic.to.the.patient,.and.less.
expensive.than.surgical.radial.lengthening
Interposition Material
Comparison of interposition materials has been, for the most part, theoretical and cognitive [10, 81]. Sta- tistical analysis for comparison would require a large number of cases of similar age, gender, sites, bar sizes, etc., in which different interposition materials were used and followed to maturity. Too few patients have been followed to maturity and critically analyzed to determine superiority of one interposition material over the others [8, 29]. “The question as to the best interposition material needs further investigation”
[43]. Guille et al. [23] stated that “the type of interpo- sition material probably does not affect the overall result.” Burke [10] summarized it well by stating “fat is readily available, but is perhaps slightly less effec- tive than cranioplast or silastic.” Langenskiöld and Österman [43] speculated that “it seems possible that autologous or heterogenous cartilage, either dead or alive, may be the most effective material for prevent- ing reformation of bone bridges.”
Season
One patient with a distal tibial physeal fracture who was followed closely was found to have greater growth in both the injured and uninjured tibia in the spring and summer months, both before and after bar exci- sion [28].
Follow-up
Follow-up of patients with bar excision should be at regular intervals, preferably every 6 months and is fa- cilitated by sequential scanograms available for dis- play and comparison (Fig. 33.15). Charting the results (Fig. 33.16) to create a graph containing appropriate data is essential in detecting a recurrence early. The Green and Anderson charts (discussed in Chapter 31) work well (Fig. 33.16h). Follow-up must continue un- til the patient reaches skeletal maturity. Many cases develop recurrent bars, sometimes years after the ex- cision. This is the only way to collect meaningful data concerning results.
Fig. 33.15
Serial.scanograms.of.a.patient.with.leg.length.discrepancy.displayed.in.the.examining.room.for.the.physician,.parents,.
and.patient.to.review.together
Regeneration of the Physis
Growth resumption following bar excision, is due to the remaining physis. What actually happens in the area of the bar excision is not well documented. When fat is the interposition material, the fat is pushed aside by the ingrowth of physis from the remaining normal physis [36, 38, 40, 43–46, 65]. Partial regeneration of the physis is the usual result [45]. There are no con-
vincing examples of complete regeneration of the physis throughout the entire area of the excised bar.
When a solid interposition material is used, the physis also appears to grow into the defect as the physis grows away from the interposition material (Fig. 33.17). This has been less well studied. Attempts to keep the interposition material in the epiphysis, ei- ther by contouring the cavity or by internal fixation, have not enhanced the overall result.
Fig. 33.16
Result.of.a.bar.excision.secondary.to.a.distal.tibial.type.1.fracture,.sustained.
at.age.3.years.7.months ..The.fracture.and.bar.assessment.are.recorded.in.
Fig ..31 .15 ..a. Scanogram. at. age. 6.years. 10.months .. The. left. tibia. is. 1 .8.cm.
shorter.than.the.right ..The.left.femur.is.1.cm.shorter.than.the.right ..b.Bar.
excision.of.left.distal.tibia.at.age.6.years.10.months ..c.At.the.conclusion.of.
the.bar.excision,.the.metal.markers.(1/2.silver.clip.distally,.titanium.break- off.wire.proximally).are.32.mm.apart ..Subsequent.scanograms.were.taken.
every.6.months ..(Continuation see next page)
Fig. 33.16 (continued)
d.One.year.later,.age.7.years.9.months,.the.normal.right.tibia.had.grown.1 .7.cm,.the.left.2 .1.cm,.and.the.metal.markers.
were.4 .0.cm.apart ..e.Data.from.yearly.(approximately).scanograms ..At.the.time.of.bar.excision.(age.6.years.10.months).
the.tibial.length.difference.was.1 .8.cm.and.the.metal.markers.were.3 .2.cm.apart ..At.age.7.years.9.months.the.tibial.
length.difference.was.reduced.to.1 .4.cm.and.the.left.tibia.had.growth.124%.compared.with.the.right ..Two.years.post.
operatively,.age.8.years.10.months,.the.right.tibia.had.grown.3 .6.cm,.the.left.3 .9.cm,.the.tibial.length.difference.was.
1 .5.cm,.and.the.metal.markers.were.4 .8.cm.apart ..The.left.tibia.had.now.grown.108%.compared.with.the.right.since.
surgery ..By.age.13.years.1.month,.6.years.3months.post.operative,.the.right.tibia.had.grown.11 .1.cm,.the.left.11 .3.cm ..
The.tibial.length.difference.was.1 .6.cm,.the.metal.markers.were.8 .2.cm.apart,.and.the.overall.growth.of.the.tibia.was.
102%.compared.with.the.right ..Since.the.difference.in.tibial.length.from.1 .4.cm.at.age.7+9,.to.1 .6.cm.at.age.13+1.fluctu- ates.1–2.mm.yearly,.it.is.most.likely.a.reflection.of.measuring.vagaries ..f.Scanogram.at.age.13.years.1.month ..The.num- bers. in. the. proximal. tibiae. represent. the. actual. measurement. and. the. growth. since. the. previous. scanogram .. The.
metal.markers.are.8 .2.cm.apart.and.the.physis.has.grown.well.away.from.the.cranioplast.plug ..g.When.the.data.from.e.
are.transferred.to.a.bar.graph,.it.is.apparent.that.the.initial.burst.of.accelerated.growth.was.followed.by.return.to.nor- mal.growth,.reflected.as.a.falling.percentage.because.all.calculations.were.made.from.the.original.numbers ..The.tibiae.
grew.equally.after.age.7.years.9.months ..h.When.the.data.are.transferred.to.a.Green.and.Anderson.chart.(interpolated.
back.to.the.date.of.fracture,.dotted lines),.it.becomes.apparent.that.age.13.years.1.month.is.crucial ..If.both.tibiae.con- tinue.to.grow.equally.until.maturity,.he.would.be.left.with.a.1 .6.cm.tibial.length.discrepancy ..However,.should.the.left.
distal.tibial.physis.close.earlier.than.the.right.(a.definite.possibility),.the.length.discrepancy.will.increase ..This.is.com- pounded.by.the.fact.that.tall.children.(he.is.two.standard.deviations.above.normal).tend.to.continue.growing.for.a.
longer.time.than.the.lines.on.the.chart.indicate ..Determining.the.need.for,.and.the.timing.of,.surgical.arrest.of.the.distal.
right.tibial.physis.requires.very.close.follow-up.at.this.stage ..In.such.a.case,.knowledge.of.the.height.of.the.parents.and.
any.older.brothers.is.of.value ..Note.that.the.left.femur.was.1.cm.shorter.than.the.right.at.time.of.bar.excision.(a) ..This.
must.be.included.in.the.decision.making ..Also.note.that.the.dotted.lines.suggest.the.bar.formed.at.the.time.of.fracture ..
However,.the.bar.could.have.formed.at.any.time.during.the.interval.between.the.fracture.and.bar.excision ..This.would.
decrease.the.slope.of.the.dotted.line.for.the.left.tibia
Clinical Series
Reports by Klassen and Peterson in 1976 [33], 1982 [32], and 2000 [31] and by Peterson in 1987 [67], 1990 [64], and 1993 [62] are summarized in the section on the Mayo Clinic Experience.
Bright (1982) [7] reported the use of Silastic in 100 patients and noted renewed longitudinal growth in 81% of patients operated at a mean age of 9.4 years,
but “this was not always equivalent to growth on the normal, uninjured side.”
In 1983, Langenskiöld and Österman [43] reported 29 cases, all due to fracture. This report expanded previous reports by Langenskiöld in 1975 (11 cases) [36], by Langenskiöld and Österman in 1979 (25 cas- es) [44], and by Langenskiöld in 1981 (28 cases) [39].
One bar was operated 7 years 10 months after frac- ture. Fat was used in all cases.
Fig. 33.17
Repeat.MRI.of.the.case.shown.in.Figs ..31 .18.and.33 .4 ..
The.repeat.MRI.is.possible.because.the.markers.used.
were. titanium ..a. Four. months. post. bar. excision. the.
epiphysis.is.growing.away.from.the.cranioplast.(black.
ball. in. center. of. the. metaphysis) .. The. white. area. be- tween.the.cranioplast.plug.and.the.epiphysis.appears.
similar.to.the.adjoining.physeal.cartilage ..b.One.year.
post. bar. excision. the. physis. continues. to. grow. away.
from.the.cranioplast.and.the.cartilage.appearing.tissue.
between.the.epiphysis.and.cranioplast.is.wider ..c.Three.
years.4.months.post.bar.excision,.age.14.years.4.months,.
the. physis. continues. to. grow. away. from. the. cranio- plast ..Bone.is.filling.the.area.between.the.cranioplast.
and.the.physis,.leaving.only.a.thin.line.of.nonosseous.
tissue. between. the. two .. Both. the. distal. femoral. and.
proximal. tibial. physes. are. in. the. process. of. closing ..
(From.Peterson.HA.[61],.with.permission)
Botte et al. (1986) [4] reported 15 patients (mean age 10.2 years) with Silastic interposition material and followed 3 years, showed that “growth potential”
was successful in 80% and that angulation improve- ment in 50% of patients.
Coleman (1986) [15] reported “complete correction from the physolysis” with patients avoiding further surgery in 6 of 18 patients (33%) followed an average of 5 years. Fat was the interposition material. He not- ed “a common trend in all patients was premature closure.”
Talbert and Wilkins (1987) [76] reported 33 bar ex- cisions in 29 patients using Silastic elastomer, and fol- lowed at least one year. There were 10 excellent, 6 good, 5 fair, and 8 poor results. The best results were in patients who were younger, who had shorter inter- val time between injury and surgery, and whose bars were smaller and peripherally located.
Hume and Bernstein (1988) [26] reported 29 bar excisions at an average age of 9 years, using Silastic as the interposition material. After a 4.5-year follow-up the results were 17 excellent (resumption of growth, with no bar reformation or increase in angular defor- mity), 4 good (no bar reformation, some persistent growth retardation, and no increase in angular defor- mity), 2 fair (no bar reformation, but persistent growth retardation or an increase in angular deformity), and 6 failures (bar reformation). They concluded that 90%
were excellent and good, but since correction of angu- lar deformity cannot be assured, corrective osteotomy should be included in the preoperative plan.
Macksound and Bright (1989) [48] reported 21 bar excisions of the distal radius, at an average age of 10.8 years, all filled with Silastic. The operation was a
“success” in patients 2.2 years younger than in those in whom it “failed.” Renewed growth of 5 mm or more was present in 76% of patients, and 8 patients achieved more than 50% of their predicted growth.
Vickers (1989) [78] reported 80 cases, spanning 17 years, using fat. Growth was reestablished in 90%
of cases, true recurrences were rare, and premature physiologic closure of the liberated physis was fre- quent close to the end of the growth period.
Williamson and Staheli (1990) [81] reported 22 cases due to fracture, treated with buttock fat.
These 22 cases probably included 11 cases reported by Kvidera and Staheli [35] in 1981. There were 11 excel- lent results (93% growth, compared with the contra- lateral physis, in all cases), 5 good (>89% growth in all cases), 2 fair (initially 96% growth, but final growth was only 46%), and 4 poor (no growth).
Dunn (1999) [17] reported 9 bar excisions at aver- age age 9.8 years, five using fat and 4 using cranio-
plast. “All physes resumed growth,” but only 4 were followed to maturity. No preference of interposition material was expressed.
Complications Bar Reformation
The most common unfavorable result of bar excision is bar reformation (recurrence) [31, 39]. A recurrent bar may form at any time, early or late, up to 5 years after initial excision [7], which underscores the need for careful follow-up. It is usually difficult to deter- mine if removal of too little of the bar or too much of the physis played a part in the recurrence. Although bar reformation may occur after excision of a bar of any size, it is more likely to occur with large bars (those that occupy 50% or more of the entire physis), and possibly with peripheral bars. Bar excisions of bars secondary to type 6 fractures, usually have prompt recurrent closure [53]. Other factors that may be associated with bar reformation are the patient’s health and the rate of growth of the physis at the time of excision. In addition to a possible specific bar refor- mation, the affected physis commonly matures (com- plete closure) earlier than the normal one [7, 31, 33].
Bar reformation signals a less-than-desirable out- come, but any added length gained is beneficial, and the bar reformation does not preclude application of all other types of bar management. If the bar reforma- tion occurs soon after excision, and significant growth remains, bar reexcision offers some hope of success (Figs. 33.14, 33.18) [8, 22, 23, 32, 38]. Langenskiöld [39] reported 5 cases of bar reformation treated by re- excision: in four “valuable growth occurred.” Brough- ton et al. [8] reported 3 cases; one had partial success and two failed. It is assumed that the possibility of re- establishing growth from bar reexcision will be less good than from the initial excision. If a bar reforms near maturity, or if the entire physis ceases growing on the injured side earlier than its contralateral coun- terpart (a fairly common finding), physeal arrest on the contralateral side should be considered.
Technical Errors
Fracture of the medial portion of the distal tibial
epiphysis has been noted after too-generous removal
of epiphyseal bone of a medial distal tibial bar. A re-
ferral case, in which a large bar had been completely
replaced with bone wax, resulted in recurrent trans-
cutaneous extrusion of small bits of wax until the wax
was entirely surgically removed.
Fig. 33.18
Bar.recurrence.and.reexcision ..a.Scanogram.of.a.4.years.7.months.old.girl ..The.right.femur.is.19.mm.and.the.right.tibia.
16.mm.shorter.than.the.left.(35.mm.leg.length.discrepancy) ..The.right.distal.femoral.and.proximal.tibial.physes.are.
abnormal ..Note.relative.overgrowth.of.the.normal.proximal.right.fibula ..Knee.function.is.normal ..b.Coronal.tomogram.
shows.central.arrest.of.both.the.distal.femoral.and.proximal.tibia.physes.with.“tenting,”.mild.in.the.femur,.moderate.in.
the.tibia ..c.Intraoperative.roentgenograph.following.excision.of.both.bars.through.separate.medial.incisions.and.me- taphyseal.cortical.windows ..The.distance.between.the.femoral.markers.is.17.mm.and.between.the.tibial.markers.is.
18.mm.(arrows) ..Cranioplast.has.been.placed.in.the.area.of.the.excised.bars.and.the.cortical.windows.replaced ..A.Jones.
bandage. with. a. posterior. plaster. splint. was. applied. for. 48.hours. after. which. the. patient. resumed. ambulation .. . (Continuation see next page)
Postoperative Infection
As in any orthopaedic surgery, postoperative infec- tion can occur (3% in Bright’s series) [7]. In the au- thor’s experience it occurred in only three patients, all in whom infection was the cause of the original bar.
Infection following bar excision is chronic and re- quires debridement and antibiotics like other bone infections. Once the infection is cleared, bar manage- ment proceeds using any of the previously discussed methods (Chapter 32).
Results: The Mayo Clinic Experience
1)From 1968 through 1996, 178 patients were treated by bar excision at Mayo Clinic (Fig. 33.19). Most, but not all, bars were caused by fracture. The vast majority of surgeries were performed by 3 staff pediatric ortho- pedists, Drs. A.J. Bianco, R.A. Klassen, and H.A. Pe- terson, with little variation in technique. Bar excision was at the knee (distal femur and proximal tibia) in 50% of the cases (Table 33.5), whereas these sites ac- counted for only 2.2% of all physeal injuries in the
1) This section has been reproduced, in part, from Peterson [66, 68],with permission.
Fig. 33.18 (continued)
d. Scanogram. 2.years. 3.months. post. surgery,. age. 6.years. 10.months .. The. leg. length. discrepancy. has. decreased. to.
23.mm.(16.mm.in.the.femur.and.7.mm.in.the.tibia) ..The.operated.right.leg.has.grown.113%.as.compared.with.the.nor- mal.left.leg ..e.Close-up.of.right.knee.at.same.time.as.d ..Both.operated.physes.are.open,.the.physeal.tenting.is.reduced,.
and.the.epiphyses.have.grown.away.from.the.cranioplast ..The.femoral.markers.are.47.mm.apart,.the.tibial.40.mm ..The.
proximal.tibia.has.grown.more.than.the.proximal.fibula.(note.normal.proximal.tibia-fibula.relationship.as.compared.
with.a.and.c ..f.Scanogram.4.years.8.months.postoperative,.age.9.years.3.months ..Since.surgery,.the.right.femur.has.
grown.9 .8.cm,.the.left.9 .9.cm;.the.right.tibia.8 .6.cm,.the.left.8 .2.cm ..The.right.lower.extremity.is.now.32.mm.shorter.and.
overall.growth.since.surgery.is.101 .7%.compared.with.the.normal.left ..Though.this.remains.an.excellent.result,.the.
.diminished.rate.of.growth.as.compared.with.d.is.of.concern ..g.Close-up.of.right.knee.at.same.time.as.f ..The.femoral.
markers.are.78.mm.apart;.the.tibial.52.mm ..Although.this.represents.continuing.growth,.the.physes.are.not.as.distinct ..
Note.one.of.the.femoral.markers.placed.too.laterally.in.the.metaphysis.is.now.nearly.outside.the.cortex,.due.to.remod- eling.(compare.with.c.and.e) ..h.Coronal.tomogram,.taken.at.the.same.time.as.g.shows.indistinct.physes.with.recurrent.
bars ..i. At. age. 9.years. 5.months. the. recurrent. bars. of. both. physes. were. reexcised .. Note. distinct. physes. without. . bars .. New. metal. markers. and. cranioplast. inserted ..j. Postoperative. roentgenograph. shows. new. metal. markers. are.
34.mm.apart.in.femur.and.17.mm.apart.in.tibia ..A.long-leg.cast.was.applied.for.3.weeks.because.the.previously.placed.
cranioplast. plugs,. now. located. in. the. diaphyses,. were. removed. and. the. cavities. filled. with. cancellous. bone .. . k.Scanogram.at.age.11.years.8.months,.7.years.from.the.first.bar.excision.and.2.years.3.months.from.the.second ..The.
new.metal.markers.are.55.mm.apart.in.the.femur.and.32.mm.in.the.tibia ..The.right.femur.is.15.mm.and.the.right.tibia.
11.mm.shorter.than.the.left,.for.a.total.discrepancy.of.26.mm.(compare.with.the.35.mm.discrepancy.in.a) ..The.right.leg.
has.grown.26 .8.cm.(103 .5%),.the.left.25 .9.cm ..Unfortunately,.this.girl.matured.early.and.all.physes.are.now.closed ..There.
was.no.surgery.on.the.left.leg ..Had.she.continued.to.grow.another.year.or.two,.physeal.arrest.of.the.normal.left.knee.
would.have.been.an.option.to.equalize.the.leg.lengths ..Knee.function.remains.normal ..A.few.weeks.following.the.re- moval.of.cranioplast.at.the.second.operation.(i).the.right.femur.fractured.at.the.site.of.cranioplast.removal.and.was.
treated.by.a.long.leg.cast.for.6.weeks ..This.left.the.mild.femoral.diaphysis.deformity ..This.was.the.only.complication.
encountered.from.cranioplast.removal.and.contributed.to.our.recommendation.to.not.remove.cranioplast ..Note:.This.
case.illustrates.the.utility.and.proper.placement.of.metal.markers,.the.necessity.for.diligent.frequent.and.continuous.
follow-up.evaluation,.and.the.beneficial.reexcision.of.recurrent.bar.formation ..(Reproduced.from.Peterson.HA.[70],.
with.permission) ..(Continuation see next page)
Fig. 33.18 (continued)
