Goals of Treatment Management

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Management

Most articles concerning any aspect of physeal fractures discuss treatment in some way. This chapter and its references concern a broad overview of management applicable to all physeal fractures. Treatment of fractures at specific sites is discussed in Chapters 9–

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Contents

Goals of Treatment ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...131 Type of Fracture . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .133 Type.1... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..133 Type.2... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..133 Type.3... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..133 Type.4... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..134 Type.5... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..134 Type.6... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..134 Management Choices . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .134 Anesthesia.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .134 Repeat.Manipulations.... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...134 Open.Reduction... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..134 Internal.Fixation... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..134 Weightbearing.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .135 Position.of.Immobilization... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..135 Duration.of.Immobilization.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... .135 Time.of.Follow-up ... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...135 Type.of.Follow-up.... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...136 Additional Concepts . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .136 Chondrodiastasis.. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .136 Physeal.Cartilage.Glue... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..136 Interpositional.Fat. .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. ..136 Nonsteroidal.Anti-inflammatory.Agents. ... ... ... ... ... ... ... ... .136 Bioabsorbable.Implants.... . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ...136 Author’s Perspective. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .138 References . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .138

Goals of Treatment

The goals of treatment of all physeal fractures are to maintain function of the body part and normal growth of the particular physis involved. Mainte- nance of growth is obviously more important in a young child than in an older adolescent who has little growth remaining. Consistent attainment of these goals is most likely to occur when all fractured structures are anatomically reduced. Thus, the practical primary goal becomes to obtain and maintain ana- tomic reduction of both the physeal cartilage and the articular cartilage. These goals may be accomplished by nonoperative or operative means.

Reduction of fracture displacement and malalignment are important priorities. Significant displacement should not be accepted, except in the proximal humerus. Displaced articular surfaces (fracture types 4 and 5) must be anatomically reduced to maintain joint surface congruity. The degree of spontaneous correctability of angular deformity is directly proportional to the amount of growth remaining for that physis. Rotation malalignment is are not correct- ed by growth, except possibly in infants [14].

Many physeal fractures are undisplaced and re- spond well to temporary immobilization. Gentle closed reduction, using manual longitudinal traction if necessary, will be successful for most displaced or angulated physeal fractures. In both the Mizuta et al.

study [12] and the Olmsted County study [16], 93% of all physeal fractures were treated nonoperatively.

Fractures more likely to require open reduction are intra-articular fractures (types 4 and 5), particularly of the distal humerus, the radial head, and the capital epiphysis of the femur, and fractures of the distal femur, and proximal and distal tibia in children over four years of age [14]. Fractures at most of these sites are relatively infrequent (Table 4.11).

Ideally, physeal fractures should be reduced immediately, as each day of delay makes reduction more difficult. The younger the child, the more rapidly the

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healing callus blends with articular and physeal cartilage, making reduction progressively more difficult.

After three to four days, progressively more distraction force is necessary to achieve reduction. After six to seven days, soft tissues have become contracted in a shortened position and excessive distraction force is required [11, 18, 20]. Most displaced fractures present- ing after seven days, and those in which a good reduction was lost, should be accepted or treated by open reduction. After 10 days even open reduction becomes difficult as the healing callous blends with the physeal cartilage, and it may be more prudent to accept the displacement or angulation and deal with the chal- lenges (deformity and growth arrest) as they unfold.

In some situations, delay of treatment of several hours (for example until the next morning) to obtain more qualified surgical personnel or better facilities or equipment, may be appropriate. Open physeal fractures (which include all type 6 fractures) carry a higher risk of complications and obviously require immediate operative care.

The use of surgery for the initial treatment of physeal fractures is closely related to fracture type (Ta- ble 6.1). The higher the fracture type number, the greater the need for surgery. The rate of initial surgery for all fracture types combined was 7.3% in the Olm- sted County study [16] and 7.9% in the Mizuta series [12].

<<drawing>> <<drawing>>

4 5 6 Total

Number (%) 104 (10.9) 62 (6.5) 2 (0.2) 951 (100)

Immediate surgery (%) 18 (17.3) 12 (19.4) 2 (100) 69 (7.3)

Late surgery (%) 15 (14.4) 12 (19.4) 1 (50) 49 (5.2)

Table 6.1. Number and surgery performed on physeal fractures by type (Peterson classification) among children in Olmsted County, Minnesota, 1979–1988 [16]. (Redrawn from Peterson [15], with permission)

<<drawing>> <<drawing>

> <<drawing

1 2 3

Number (%) 147 (15.5) 510 (53.6) 126 (13.2)

Immediate surgery (%) 1 (0.7) 23 (4.5) 13 (10.3)

Late surgery (%) 0 (0) 12 (2.4) 9 (7.1)

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Type of Fracture

Differences of treatment apply according to type of fracture [11, 14, 17, 20]

Type 1

The type 1 fracture (Chapter 3A) has the least potential damage to the physis and therefore needs the least aggressive treatment. Closed reduction, when necessary, usually achieves satisfactory position and alignment of the fragments. Fractures of the metaphysis and physis heal rapidly, and cast immobilization for 2–3 weeks is sufficient and may be less in very young children. Displacement sufficient to require open reduction is unusual. Only 1 of 147 cases (0.7%) of type 1 fractures in the Olmsted County series [16] was treated by open reduction.

Since the physis is involved in the injury, the potential for growth arrest is present (3.4% in the Olm- sted County study [16]). Therefore, these fractures need follow-up long enough to ensure resumption of normal growth; at least three months is appropriate for most cases, longer for cases with metaphyseal comminution or multiple fracture lines extending to the physis. This varies depending on the severity of fracture, the site, and the patient’s age.

Type 2

Usually, the type 2 fracture (Chapter 3B) reduces eas- ily with manual closed reduction. Scraping of the metaphyseal fragment across the intact physis during reduction (Fig. 30.4), can be diminished by good patient relaxation to reduce muscle tension. This is probably best achieved by general anesthesia or regional anesthesia using an axillary or lumbar epidural block. The metaphyseal fragment (Holland sign) usually prevents overreduction. The intact periosteum on the side of the metaphyseal fragment imparts further stability to the reduced fracture, and internal fixation is often unnecessary.

In the young patient, incomplete reduction may be more acceptable than repeated overzealous manipulations, which may cause gouging of the physis. In the older patient, a more accurate reduction is sought, as there is less growth to achieve spontaneous correction. Occasionally, type 2 fractures cannot be satis- factorily reduced due to interposition of soft tissue, most often periosteum. Interposition of bone fragments, muscle, tendon, nerve, and vascular structures

has also been reported at various sites. All benefit from surgical extrication.

If the fragments are reduced and unstable, internal fixation is appropriate. This is best accomplished by pins or screws from metaphysis to metaphysis, avoiding the physis (Fig. 18.15). When the metaphyseal fragment is too small to accept metal, small-diameter pins may be placed from the epiphysis, across the physis, into the metaphysis [9]. Growth arrest is less likely if the pins are smooth (not threaded), are as perpendicular to the physis as feasible, are in the center of the physis avoiding the perichondral ring, and remain in place a short time, preferably no more than 3 weeks. Excision of the metaphyseal fragment may improve visualization of the physis, but does not reduce the likelihood of premature physeal arrest. In the Olmsted County study [16], 23 of 510 type 2 fractures (4.5%) were treated initially by surgery (Ta- ble 6.1).

The prognosis (Chapter 7) depends on the severity of fracture (comminution, displacement, etc.), the age of the patient, and the site of injury. When the physis is irregular and undulating, as in the distal femur or proximal tibia, displacement of the metaphyseal surface against the physeal surface produces scraping of these irregular surfaces, and an increased likelihood of physeal arrest. A smooth, flat physis, such as the distal radius, is much less prone to arrest. Follow-up until resumption of growth is documented is appropriate; at least 6 months, or longer if there is any roentgenographic abnormality of the physis.

Type 3

The type 3 fracture (Chapter 3C) is entirely within the physeal cartilage with no bone involved. It is sim- ilar to a type 2 fracture with a very small metaphyseal fragment. Although the major portion of most fractures is in the area of the hypertrophic zone (Fig. 30.1), well away from the germinal cell layer, all layers of the physis may be involved (Fig. 30.2). Thus, the prognosis for growth arrest is slightly greater than with type 2 fractures. Type 3 fractures should be managed by closed reduction whenever possible. Most are rea- sonably stable following reduction. Internal fixation requires crossing the physis in all cases not amenable to external fixation. In a young child, it is better to accept an imperfect reduction than risk the hazards of repeated attempts of reduction and of internal fixation across the physis, as there is ample time for re- modeling. In the Olmsted County study 13 of 126 cases (10.3%) were treated initially by surgery (Ta- ble 6.1).

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Type 4

In the type 4 fracture (Chapter 3D) the cartilage of the physis and the cartilage of the articular surface are both disrupted. The best result is achieved by anatomic reduction of the physeal cartilage to reduce the chance of growth arrest, and anatomic reduction of the articular surface to reduce the likelihood of de- generative arthrosis. These fractures occur more often in older children (Table 3D.1), when the physis is beginning to close, and growth arrest is less of a prob- lem. Anatomic reduction often requires open reduction [5] to visualize the articular surfaces, especially in young children. Rigid internal fixation prevents redisplacement and may reduce the formation of osse- ous callus, reducing the potential of physeal bar formation [7]. The most desirable internal fixation is epiphysis-to-epiphysis without crossing the physis, particularly in young children. In the Olmsted Coun- ty study [16], 18 of 104 cases (17.3%) were treated initially by surgery (Table 6.1).

Type 5

In the type 5 fracture (Chapter 3E) both physeal and articular cartilage are disrupted, and the likelihood of fragment displacement is greater (Fig. 30.6). Anatom- ic reduction and maintenance of reduction are essen- tial to align both the physis and the articular surface [13]. If there is residual displacement, open reduction [5] and internal fixation [7] are usually required.

Twenty percent of type 5 fractures (12 of 62 cases) were treated by open reduction in the Olmsted Coun- ty series (Table 6.1). Other authors [11] state that almost all will require open reduction. Closed reduction with percutaneous internal fixation may be acceptable in some situations with experienced sur- geons. Internal fixation is best accomplished from epiphysis to epiphysis and/or metaphysis to metaphysis (Fig. 20.21), particularly in young children. The prognosis for growth arrest is high, even with anatomic reduction. These fractures need observation for at least a year, even if earlier evaluation is good.

Type 6

Because type 6 fractures (Chapter 3F) are open injuries, all (100%) require initial debridement, often with wound packing and secondary closure, and sometimes with skin graft or flap closure. Physeal bar formation on the exposed bone surface can be expected.

All of these children must be followed until maturity, as most if not all develop growth arrest in the area of

exposed bone, with angular deformity and relative shortening of the involved bone. This arrest may take months or years to occur.

Management Choices

Several management choices deserve consideration.

Anesthesia

All reductions, whether closed or open, should be performed with gentleness afforded by adequate anesthesia to prevent further damage to the delicate physeal cartilage. Muscle relaxation helps to diminish compression of the germinal cells during reduction [11]. General anesthesia is appropriate in most cases.

Protocols for sedation and regional anesthesia vary according to the capabilities and the resources of individual treatment centers.

Repeat Manipulations

Rough handling of physeal tissue and repeat manipulations increase the risk of growth arrest and should be minimized or avoided. Complete anatomic reduction should not be insisted upon if its accomplishment increases risk of damage to the physis [2, 11]. Howev- er, incomplete reduction could be due to soft tissue interposition which is best treated by extrication of the tissue.

Open Reduction

Cases treated by open reduction are prone to secondary damage of the physeal cartilage. It should be considered only when satisfactory closed reduction cannot be obtained or maintained. The ideal incision allows visualization of both the physeal cartilage and articular cartilage (if fractured). Direct pressure on the physis by bone or instruments should be avoided.

Of all physeal fractures, approximately 7% undergo open reduction (Table 6.1) [12, 16]. Some fractures reduced by open reduction are stable and do not need internal fixation.

Internal Fixation

Internal fixation using wires, pins, nails, staples, screws, or other metallic devices traversing the physis to maintain reduction, should be used sparingly [2, 3, 9]. They result “often, if not invariably, in a distur- bance of growth” [2, 3]. Wires and pins are synony-

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mous, are the most commonly used internal fixation device for physeal fractures, and should be removed because they are prone to migrate, sometimes with disastrous results. One article alone [19] documents 41 referenced articles of pin migration. Factors re- sponsible for this increased risk of physeal closure due to the presence of internal fixation devices are:

1. Smooth versus threaded pins. Threaded pins will

“always” result in physeal arrest (Fig. 30.7) even if present only briefly (a few days). Dissenters to this view are few [8].

2. Number of devices. Multiple wires across the physis have a greater chance of producing arrest than a single wire. The number of penetrations across the physis while inserting the pins should also be kept to a minimum.

3. Position of devices. A wire across the center of the physis is less likely to cause arrest than one at the periphery [9].

4. Angle of device to physis. A wire perpendicular to the physis is less likely to cause arrest than one oblique to the physis (Fig. 30.8).

5. Size of device. A large rod that occupies a large percentage of the physis is more likely to cause arrest than a small diameter pin. The precise percentage of device to total area of physis is yet to be deter- mined.

6. Duration of device retention. Most physeal fractures have stabilized by callus formation in two to three weeks. Leaving metal devices across a physis for longer periods enhances the chance of arrest.

7. Metal composition. Some metal, such as titanium, may have bone bonding properties increasing the possibility of tethering the physis.

Weightbearing

Weightbearing can alter the position or alignment of an unprotected lower extremity physeal fracture.

However, it has never been shown that weightbearing adversely affects the integrity of the uninjured portion of the physis of a properly reduced and immobi- lized fracture. Obviously, a fracture secured with in- ternal fixation should not be put to the test of weightbearing for fear of altering the fixation device.

When the internal fixation is removed in two to three weeks, weightbearing will not further damage the physis. If premature growth arrest occurs, it is due to events incurred during fracture or fracture treatment, rather than to any subsequent weightbearing.

Position of Immobilization

The ideal position of immobilization is the one that provides the optimum stability of the reduction.

Compared with an adult, a position of greater joint flexion or extension may be accepted to insure stability in a child, since children regain motion more rapidly and are less likely to develop stiffness [11]. This is particularly true for physeal fractures since they rarely require more than four weeks immobilization, usually less. Thus, a dorsally angulated type 2 or 3 fracture of the distal radius can be reduced and the wrist held in 45–60 degrees flexion. Wrist motion is rapidly regained and carpal tunnel syndrome is rare. In children careful cast molding to support the reduced fracture, yet prevent pressure points, is more important than position of immobilization to prevent joint stiffness [11].

Duration of Immobilization

The duration of immobilization is variable, and depends on the location of fracture, its severity, the use of internal fixation, the child’s age, the presence of associated injuries or chronic illness, and sometimes on the child’s demeanor and ability to cooperate. Physeal cartilage healing is rapid and is generally structurally sound in three weeks. Immobilization may need to be longer if large areas of bone are also involved in the fracture (e.g., type 5 fractures), or if there are accom- panying shaft fractures. Over the course of my career I did not encounter physeal fracture displacement or redisplacement due to premature cast removal and, therefore, I progressively shortened the time of immobilization. In many instances, splints and braces can be utilized in place of casts, particularly after 10 days. This allows early resumption of motion [18].

Time of Follow-up

Displaced fractures treated by closed reduction without internal fixation (a large proportion of cases), require roentgenographic re-evaluation in three to five days, which is about the last chance to improve a redisplacement by closed means. Barring a second injury, any physeal fracture is unlikely to change position after 10 days. Fractures treated by open reduction and internal fixation (ORIF) need good intraopera- tive imaging and permanent films of good quality in appropriate planes at the conclusion of surgery, at conclusion of cast application, and not again until cast removal (barring additional trauma).

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Long term follow-up is variable depending on the severity of the fracture (displacement, comminution, open versus closed), the age of the patient, and the fracture type. See guidelines in this chapter for fracture type, Chapter 7 (prognosis), and chapters on specific sites (Chapters 9–29). If growth arrest is antici- pated at the time of initial fracture, roentgenographic re-examination in three months is appropriate because this is the earliest time a definitive growth dis- turbance can be recognized.

Some growth arrests become manifest later than expected. Parents should be instructed to observe for any angular deformity, length discrepancy, or func- tional change, and report it immediately. Reevalua- tion of all physeal fractures one year post injury is a good policy. Interim evaluations at six and nine months are appropriate after major injuries, particularly of the rapidly growing physes of the knee and ankle [21].

If the physis is completely normal at one year after fracture, growth arrest is less likely to show up later.

This is not true for potential growth arrest following infection, frostbite, burns, and irradiation. Any abnormality of the physis present at one year requires further evaluation, particularly in young children.

When the one year follow-up examination and roentgenographs are normal, girls with bone age greater than 13 years and boys of greater than 15 years require no further follow-up.

Type of Follow-up

Routine AP and lateral roentgenographs are appropriate in all cases. The Harris growth arrest lines (Chapter 31), when present, are excellent indicators of both normal and abnormal growth. Comparison views and scanograms can be extremely helpful in evaluating the status of the physes and growth. A single standing AP roentgenograph of both tibiae is usually sufficient to evaluate the physes of the tibiae and fibulae.

Additional Concepts

There are several treatment concepts which have been proposed which are worthy of consideration.

Chondrodiastasis

Applying a light traction across a physis causes elon- gation of the hypertrophic cell region. This response of the cartilage columns to applied tensile loads may

aid in preventing transphyseal bone bridge formation after physeal fracture [4]. This would require the application of an external fixator/lengthener, which is rarely feasible or considered following acute physeal fracture. No guidelines suggesting fractures appropriate for this management strategy have been proposed.

Physeal Cartilage Glue

The concept of gluing a fresh physeal fracture with fibrin adhesive seal is innovative, but needs more in- vestigation [1, 10].

Interpositional Fat

Fat inserted into a fresh physeal fracture might reduce the likelihood of physeal bar formation [6, 18]. Strict criteria will need to be established to determine which fractures, at which sites, and at what ages, might benefit.

Nonsteroidal Anti-inflammatory Agents

Nonsteroidal anti-inflammatory agents have been shown to inhibit callus formation. This appears to be due to their antiprostaglandin effect, diminishing in- growth of new vessels into the fracture site. These agents do not inhibit collagen formation nor prevent growth of cartilage cells. Thus, they may prove useful to prevent active callus formation after fracture of the growth plate, while still allowing cartilage cells to grow sufficiently to recover from the fracture [4, 22].

Bioabsorbable Implants

Bioabsorbable implants [23–37] are degraded in a bio- logic environment, and their breakdown products are incorporated into normal cellular physiologic and chemical processes. For orthopedic use the ideal bioabsorbable material should initially have mechanical characteristics equal to those of standard metallic implants. It should degrade with the healing process so that load is gradually transferred to the healing tissue, yet secure the fracture without arresting the physis.

Thus, there would be a race in time between physeal fracture healing and absorption of the pin, as well as a race between absorption of the pin and formation of a physeal bar. Hopefully, the growth pressure from the healing physeal fracture would break the biodegrad- able implant before a bar is formed [28]. The currently available polymers do not have all these characteristics, but improvements are ongoing [26].

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The clinical application of bioabsorbable materials has focused on the use of polymers known as alpha- polyesters or poly (alpha-hydroxy) acids. These include: polyglycolic acid (PGA) [23, 24, 30, 31, 35, 37], polylactic acid (PLA) [23], poly-L-lactic acid (PLLA) [35], and polydioxanone (PDS) [32, 34]. Combinations of these materials allow optimization of their biome- chanical properties for certain clinical uses [26, 33].

For physeal fracture stabilization, pins of 1.1–

4.5 mm diameter with lengths from 10 to 70 mm, and screws of 2.0–4.5 mm diameter with lengths of 6–

70 mm, are available for use in humans. The implants swell after a few hours in the body adding to the fixation. Fractures are reduced and held with Kirschner wires while the biodegradable pins are inserted. The material is radiolucent, thus it is advantageous to in- traoperatively document the position of the drill holes into which the devices are placed. Ideally, each K wire is then sequentially replaced by a biodegradable pin [31], reducing the number of transphyseal penetrations.

Biodegradable pins provide sufficient stability for the relatively short duration of healing physeal fractures [27, 30] and still yield on the pressure of growth.

The pressure of growth exceeds the tensile strength of the implant, and therefore is able to break the implant.

This usually occurs about three weeks after implantation. Regeneration of the growth cartilage within the pin canals left by the broken implants, preserves the growth potential [31, 32].

This ability of the pins to break due to growth plate pressure is related not only to the size of the pins (smaller is better), but also is related to the area of physis occupied by the absorbable devices [33]. One study [32] in rabbits showed growth retardation when 3.2 mm diameter rods occupied 7% or more of the growth plate, and no growth retardation when 2 mm diameter rods occupied 3% or less of the area of the physis. This limits the size and number of pins that can be used. The smaller diameter pins used in children have lesser amounts of material to degrade, compared with the larger pins used in adults. In human clinical trials, some authors [23, 25, 31, 37] have noted no interference with growth. Not all of these patients have been followed to maturity. Other authors [30, 34, 35], however, have noted physeal bridging and growth arrest.

The major advantage of bioabsorbable pins is that they do not incur the cost, or the pain of removal, as occurs with metallic pins. However, absorbable implants are more expensive than their metallic counterparts. PGA rods cost 20 times more than K-wires.

Compared with metallic counterparts that are not re-

moved, the total cost of treating a fracture with bioabsorbable implants increases 4–7%. If the metallic hardware is removed, the absorbable implants would be 2–9% less expensive to use [36].

Complications of Bioabsorbable Implants Nonbacterial Inflammatory Reaction

Transient inflammatory foreign body response con- sisting of local erythematous tissue fluid accumula- tion, or a frank discharging sinus yielding remnants of the degrading implant, have occurred two to four months postoperative in up to 8% with the use of PGA [24, 26, 30, 36, 37]. A small painless fluctuant swelling may be observed, but larger, painful accumulations are usually aspirated or drained surgically [36]. Bacte- rial cultures are negative. When the reaction resolves spontaneously it does not appear to affect fracture healing.

This foreign body reaction is most likely a mani- festation of the tissue response to the alpha-hydroxy polyesters. The clinical intensity of the reaction is in- fluenced by the individual’s ability to clear the degraded material from the site of implantation versus the rate of material degradation. Materials that degrade more slowly are less likely to cause a clinically significant response. Proposed risk factors for devel- oping a transient inflammatory response include the volume of material used (i.e., the size and number of implants used), implants colored with aromatic dye, the local vascular supply, and increasing age [30, 36].

Synovitis

Synovitis in adults has led to synovectomy and debridement of the ununited osteochondral fragment.

This has prompted the recommendation that PGA pins should be used with caution in an intra-articular location [36].

Wound Infection

Wound infection rates are low and seem to be equiva- lent to those associated with conventional internal fixation devices and techniques [36].

Osteolysis

Osteolysis without inflammatory reaction occurs in up to 14% of pediatric patients treated with PGA pins [29].

Loss of Fixation

In general, the loss of fixation depends as much on the method of fixation as on the material used [36]. Bio- degradable pins are not recommended for fixation in

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load bearing areas where they might be subjected to excessive mechanical stress [30]. One implant in a distal femoral physeal fracture failed (broke) during postoperative cast application. The patient was then treated in traction for four weeks followed by cast for four weeks [35]. Loss of reduction in another patient in whom bioabsorbable rods had been used was treated by reoperation using bioabsorbable screws [35].

Miscellaneous

In addition to the above mentioned potential complications, isolated cases of avascular necrosis, deep ve- nous thrombosis, and loss of joint motion have been recorded [30, 35].

Summary of Bioabsorbable Implants

The possibility of growth retardation from biodegradable implants across the physis is a function of the number of physeal cells destroyed by the intro- duction of the pins, as well as the inability of the growing physis to break the implant. For the present time, the cautious approach for the application of bioabsorbable pins would be their use in fracture of the upper extremity, where no weightbearing is required, and in adolescents who have little growth remaining [35]. Hopefully, improvements in materials for bioabsorbable fracture fixation will be forthcoming. Un- til then the available pins and screws should be used with care and with attention to the characteristics of each individual fracture.

Author’s Perspective

The best way to achieve optimal results in the treatment of physeal fractures is to utilize accepted stan- dards of clinical practice and commit to continuing education.

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