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Physeal injuries in children
ORTHOPAEDICS V: PAEDIATRICS
Physeal injuries in children
primary ossification centres form in the middle of the bone. This primary ossification centre expands towards the proximal and distal ends of the bone. The peripheral extensions of the primary ossification centre at either ends of the bone gives rise to the growth plate or the physis, a cartilaginous disc separating the epiphysis from the metaphysis. The physis is responsible for the longitudinal growth of long bones. When skeletal maturity is reached, physes are resorbed and replaced by bone.
Arijit Mallick Hari Prem
Physeal structure (Figure 1) Histologically, a physis is formed with chondrocytes surrounded by extracellular matrix. Chondrocytes are arranged in a columnar fashion along the longitudinal axis of the long bone and grow towards the metaphysis where the endochondral ossification occurs. A physis is divided from distal to proximal into zones according to the rate of growth, numbers and distribution of chondrocytes. It is important to understand these zones in order to understand various types of physeal injuries. These are the: reserve zone (also known as germinal zone or resting zone) proliferative zone hypertrophic zone zone of endochondral ossification The hypertrophic zone is further subdivided into: zone of maturation zone of degeneration zone of provisional calcification There are two important structures on the periphery of the physis2 (Figures 1 and 2), which are the: groove of Ranvier: a circumferential notch described by Ranvier which provides chondrocytes to the periphery for lateral growth perichondrial ring of LaCroix: a dense fibrous tissue, where the periosteum of the bone is attached to the perichondrium of epiphysis and gives mechanical support to the bone-physis interface.1
Abstract Fractures involving the physis account for up to one-third of paediatric fractures. It is also the structure which needs to be preserved to ensure normal growth. The relative strength of the physis changes with age and it becomes weaker as the child grows older, making physeal injuries more common in adolescence. It is important to understand the physeal anatomy and its relevance to different types of physeal injuries. SaltereHarris system is a clinically useful approach to classifying and describing physeal injuries. Each physeal injury should be treated as a distinct entity taking into account the patient’s age, location of injury, type of injury, growth potential of the affected part, degree of displacement and time elapsed since injury. Its treatment ranges from conservative management to operative fixation. Manipulation of physeal fractures should be as gentle as possible to prevent growth plate damage leading to growth disturbances. These complications can be difficult and complex to manage. The management involves two phases: the first phase should ensure reduction, maintenance of reduction, and bone healing; the second phase involves monitoring the growth with long-term follow-up, to detect any deformities from growth arrests or disturbances. Counselling parents about the potential risk of future growth arrest and deformity is important.
Keywords Bony bars; growth arrest; paediatric fracture; physis; SaltereHarris
Introduction The weakest area in a child’s bone is the physis or the growth plate. It is also a structure which needs to be preserved to ensure normal growth after the injury. As long as the epiphysis remains more cartilaginous, it acts as a shock absorber and forces are transmitted to metaphysis. Hence there is a higher chance of torus fracture (buckle fracture) in younger children.1 The relative strength of the physis changes with age and it becomes weaker as the child grows older, making physeal injuries more common in adolescence.
Blood supply to the physis (Figure 2) It is important to know the vascular distribution in the various zones to understand it’s contribution to the prognosis in physeal injuries.3,4 Blood supply to the physis comes from three sources:3 epiphyseal circulation metaphyseal circulation perichondrial circulation. Epiphyseal circulation: small branches come out from the main epiphyseal artery, enter the epiphysis and pass through small cartilage canals into the reserve zone. None of the branches from the epiphyseal arteries penetrates beyond the proliferative zone to supply the hypertrophic zone. Dale and Harris4 mentioned two types of epiphyseal circulation (Figure 2): Type A: The epiphysis is almost completely covered with articular cartilage and is dependent on blood supply through the perichondrium, making it vulnerable to ischaemia after physeal separation. Examples include the proximal humerus and proximal femur (Figure 2, bottom right). Type B: The epiphysis is only partly covered with articular cartilage and has blood supply which enters it directly.
Relevant anatomy At around 6 weeks of gestation the long bones are formed from mesenchymal anlage. Then at around 8 weeks of gestation
Arijit Mallick FRCS (T&O) is a Senior Foot and Ankle Fellow at the Royal Orthopaedic Hospital, Birmingham, UK. Conflicts of interest: none declared. Hari Prem FRCS (T&O) is a Consultant Foot and Ankle Surgeon at the Royal Orthopaedic Hospital, Birmingham, UK. Conflicts of interest: none declared.
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These arteries pass vertically towards the boneecartilage junction of the physis. However, no vessels pass from the metaphysis into the hypertrophic zone. Perichondrial circulation: the groove of Ranvier and the perichondrial ring of LaCroix, are richly supplied with blood from perichondrial arteries. Significance of vascularity and zone of physeal injuries5 The strength of the physis is related to the morphology of the cells and to the intercellular matrix. Owing to good vascularity, there is an abundance of extracellular matrix in the reserve and proliferative zones helping them resist shear forces better. On the other hand, extracellular matrix formation is significantly less in the hypertrophic zone due to its avascularity, and it has reduced capacity to withstand shear, bending and tension forces. Hence more physeal injuries occur through the hypertrophic zone. Beyond that, the zone of endochondral ossification is reinforced by calcification and hence is stronger.4,5
Figure 1 Structure of the physis.
Incidence of physeal injuries6e9 Physeal fractures account for up to 30% of all paediatric fractures. Boys are affected twice as often as girls, probably because their physes remain open longer and they are exposed to more traumas due to athletic activities.1,6e9 The peak incidence is around 14 years in boys and 11 years in girls. The upper limb is most likely to be affected, with the distal radius being the most common site of fractures in children and ankle the second most common site.6e9
Classification Various radiograph-based classification systems have been described, of which the SaltereHarris system is most widely used. SaltereHarris (SH) system10 (Figure 3) This classification is based on five fracture patterns. It helps guide the treatment as well as the prognosis. There is progressively more chance of growth arrest as you move up through the classification. This classification system also has a good reproducibility. Types IeV was described by Robert Salter and Robert Harris in 1963:10 Type I: transverse fracture through the physis Type II: fracture through the physis and the metaphysis, sparing the epiphysis Type III: fracture through physis and epiphysis, sparing the metaphysis Type IV: fracture through the physis, metaphysis, and epiphysis Type V: compression fracture of the growth plate (resulting in a decrease in the perceived space between the epiphysis and metaphysis on X-ray)
Figure 2 Blood supply of the physis. (a) The three sources of blood supply to physis: epiphyseal, metaphyseal and perichondrial. (b) Two types of epiphyseal blood supply as described by Dale and Harris.
These are at lesser risk of ischaemia following injury. Examples include the distal radius, proximal tibia (Figure 2, Bottom left), distal tibia and distal femur. Metaphyseal circulation: the metaphysis is richly supplied with blood from the terminal branches of the nutrient artery.
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ORTHOPAEDICS V: PAEDIATRICS
Figure 3 Classifications of physeal SH, SaltereHarris.
Ogden VII: epiphyseal fractures from articular surface through epiphyseal cartilage and into secondary ossification centre, but not involving the physis Ogden VIII: metaphyseal fractures affecting later growth through vascular insult Ogden IX: severe fragmentation of the diaphysis causing periosteal damage interrupting blood supply to the physis, which may affect later growth
Rang added Type VI to the original classification11 (Figure 3): Type VI: avulsion injury to the peripheral portion of the physis (after which a bridge formation may result in significant angular deformity due to its peripheral location) Ogden7,8 included three further injuries, to the original physeal injury classification of Salter and Harris, which could affect growth mechanisms (Figure 3):
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Peterson retained SaltereHarris types I through IV as Peterson types II, III, IV, and V and added two new types12 (Figure 3): Peterson I: fracture across metaphysis with extension into physis but no extension along the physis Peterson VI: fracture where a portion of physis is missing and it some cases it may be associated with loss of the adjoining metaphysis and epiphysis
Individual physeal injury and its treatment Results of treatment of physeal injuries depend on the severity of injury, its anatomic location, age of the patient and timing of intervention. The age of the child is an important factor, because remodelling potential depends on the number of years of growth remaining before closure of the physis.13e17 Different physes have different growth potentials. For example, the distal physis of femur contributes 70% of the growth in length of the femur while the capital femoral physis has only a 30% contribution. Physeal injuries become ‘sticky’ and unite very quickly, in both good and unacceptable positions. Therefore, these fractures should preferably be reduced within 24 hours of presentation where possible and should not be left for a ‘next available clinic’ or treated expectantly. Reduction should be early and gentle, avoiding any additional iatrogenic trauma to the original trauma. If an acceptable reduction is not possible with gentle manipulations, open reduction should be considered promptly. If an injury is several days old or if the original reduction is lost, a careful decision has to be made to assess if the deformity justifies a late attempt at reduction, given the chances of it not being likely to move with gentle manipulation. Frequently CT scans are undertaken to determine the exact nature of the severely comminuted epiphyseal and metaphyseal fragments, which may not be seen and properly evaluated on plain radiographs.
Figure 5 CT scan of SaltereHarris Type II.
arthrography may be required to confirm diagnosis. In infants, even if it is displaced it is invisible due to the lack of an ossific nucleus at the bone end. However, in infants there is remodelling to normal alignment, even if the displacement is not reduced. Type I fractures are often stable and treated by closed means. Maintaining a satisfactory alignment between the metaphysis and epiphysis will give a generally excellent prognosis. Healing is rapid for Type I fractures, occurring within 2e3 weeks of injury. Problems are rare, with the exception of completely displaced proximal femur epiphysis, which has a high risk of avascular necrosis. Type II is the commonest SaltereHarris pattern (75%). The metaphyseal fragment is known as the Thurston Holland fragment (Figure 5). The treatment for this type of displaced fractures involves careful gentle closed reduction and immobilization, which can involve transfixing K-wires. Occasionally a flap of periosteum may be entrapped between the epiphysis and the metaphysis, blocking reduction. This requires careful surgical exploration to remove the entrapped periosteum before appropriate reduction and immobilization. The prognosis for healing with this type of injury is good.
Types I and II Type I accounts for 6% of all physeal injuries. These are rare and are observed most frequently in infants. These commonly involve the proximal or distal humerus and the distal femoral physes but can also be seen in distal radius (Figure 4) Slipped upper femoral epiphysis (SUFE) can be regarded as a Type I injury. An undisplaced Type I fracture will appear normal on plain radiograph. Therefore, careful clinical assessment and sometimes the use of an ultrasound scan or MRI scan or
Remodelling potential in Type I and Type II injuries Generally a bigger residual angular deformity is better tolerated in the upper extremity than in the lower extremity. Similarly residual valgus deformity is tolerated better than varus, and flexion deformity can be tolerated better than those in extension. About 74% of remodelling occurs at the physis and 26% at diaphysis.13e17 When the asymmetry is in the plane of joint motion (flexion and extension), spontaneous correction of angular deformities is greatest. An accurate reduction is more important at the ankle and knee because most of the time the deformity is not in the plane of motion of these joints. Types III and IV Type III accounts for 8% of all physeal injuries. They are more commonly seen in older children where the growth
Figure 4 Radiograph of SaltereHarris Type I.
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ORTHOPAEDICS V: PAEDIATRICS
fracture in the ankle (Figure 7) or in separation of the lateral condyle of the distal humerus. Type IV ankle fractures of the tibia are also seen together with triplane fractures. If treated properly, the prognosis is good, but patients should have long-term follow-up to detect growth disturbance. Overall, the situation is more complex with Type III and Type IV injuries. Type III and Type IV injuries involve the articular surface and hence anatomic reduction is essential. These injuries require prompt and accurate reduction and some form of fixation, either by open reduction and internal fixation or by percutaneous fixation. Inaccurate reduction causes a mismatch of the layers (physis, epiphysis, metaphysis) and can result in a non-union and the lateral condyle fracture is particularly prone to it. Open reduction internal fixation (ORIF) can be considered for many weeks after injury as remodelling at the articular surface will not occur although outcomes become increasingly poor with time.13e17 Type V happens when there is a compression injury to the physis. The initial radiographs are usually normal and these injuries are recognized in hindsight, when an angular deformity or a leg length discrepancy develops later due to physeal fusion. An example for this is recurvatum deformity due to growth arrest affecting the proximal tibial physis.
Figure 6 CT scan of SaltereHarris Type III.
Complications of physeal fractures
plates have started to close. When part of the physis is open it forms a weak site susceptible to fracture compared to the part of the bone with a closed physis (Figure 6). Displaced injuries may result in a physeal bar formation, leading to growth disturbance and joint incongruity and possible arthritis. Treatment usually involves an anatomic open reduction and stabilization with wires or screws to restore articular congruency. We must endeavour to avoid penetration of the joint and the physis with the screws wherever possible. Hence the screws are applied parallel to the physis. When treated properly, the prognosis is good. Type IV accounts for 10% of all physeal injuries. Examples of this fracture pattern can be seen in medial malleolus
The complications associated with physeal fractures will be similar to those of any other fractures, along with the specific complication of physeal growth arrest which can lead to angular deformity or limb length discrepancy (LLD) or growth acceleration. The acceptable limit of angulation or displacement following physeal injury varies between its anatomical location (Table 1). Growth disturbance Disturbance of normal physeal growth can happen after a physeal injury due to physical loss of the physis, disruption of normal physeal architecture and function (without loss of the physis), or formation of a bony bridge or physeal bar.14e16
Figure 7 Radiograph showing SaltereHarris Type IV and its surgical fixation (note that the screws are placed parallel to the physis).
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contour and the sharply defined radiolucency between epiphyseal and metaphyseal bone on radiographs. This happens because of alteration in normal enchondral ossification caused by the physeal injury. There may be an asymmetric growth arrest line indicating angular deformity, but the arrest line will not taper to the physis itself. This indicates an altered physeal growth (either asymmetric acceleration or deceleration) but not a complete cessation of growth.
General tolerances for physeal fracture displacement and angulation (Nelson and Wongworawat’ 2009)16 Region
Degree of angulation/ displacement
Distal femur (SHI or SHII)
5 e10 varus/valgus 10 e20 flexion/extension Anatomic reduction
Intra-articular fractures (SHIII or SHIV) Distal tibia (SHI or SHII)
Distal tibia (SHIII or SHIV) Distal tibia (triplane SHII, posterior metaphyseal spike) Distal tibia (triplane SHIV anterolateral epiphyseal fragment) Proximal humerus
If >2 years’ growth remaining 15 plantar tilt 10 valgus for laterally displaced fractures 0 varus for medially displaced fractures If <2 years’ growth remaining <5 angulation in any plane <1 mm displacement or <2 mm gap <2 mm displacement
Growth arrest with formation of a bony bridge or a physeal bar As the Type I and II fracture lines spare the reserve and proliferative zones, growth disturbances are generally thought to be uncommon, although published studies do not always reflect this view. Type III and IV fractures, traverse all the zones and are more prone to growth arrest and formation of bony bars, especially if the displaced fragment is not anatomically reduced. Established physeal bars are typically characterized by sclerosis in the region of the arrest. If asymmetric growth has occurred, there may be tapering of a growth arrest line to the area of arrest, angular deformity, epiphyseal distortion, or shortening. This distinction in the direction of the growth arrest line is important, because the consequences and treatment are different from those caused by complete growth arrest.
<2 mm displacement
70 angulation, 100% displacement if <5 years 40 e70 angulation, if 5e12 years 40 angulation and 50% displacement if >12 years <2 mm
Evaluation of physeal growth arrest Evaluation with CT scanning with sagittal and coronal reconstructions may demonstrate clearly an area of bone bridging the physis between the epiphysis and metaphysis. Three basic patterns of physeal arrests are recognized (Figure 8): Central: an island of arrest within the remaining physis. Central arrests are most likely to cause tenting of the articular surface, although it may also result in angular deformity if eccentrically located and occasionally in limb length inequality. Peripheral: it is located at the perimeter of the affected physis. This type of arrest primarily causes progressive angular deformity and variable shortening. Linear: it is a lesion with anatomic characteristics of both a central and peripheral arrest. Specifically, the affected area extends up to the perimeter of the physis, but there is normal physis on either side of it. Linear arrests most commonly develop after SaltereHarris Type III or IV physeal fractures of the medial malleolus.
Distal humerus (lateral condyle, SHII or SHIV) Distal humerus (medial condyle, <2 mm SHII or SHIV) Distal humerus (transphyseal) No numeric recommendations, but CRPP recommended if unstable or significantly displaced Distal humerus (T-condylar, SHIII <1 mm or SHIV) Proximal radius (radial neck, SHI <45 angulation 50% displacement and SHII 50 e60 clinical pronation or Supination Proximal radius (involving radial <2 mm intra-articular gap/step head) SHIII and SHIV Proximal ulna (olecranon) <5 mm Distal radius 30 angulation, if < than 10 years 15 angulation, if >10 years old CRPP, closed reduction percutaneous pinning; SH, SaltereHarris.
Treatment of bony bars Treatment depends on the age of the patient, location of the physis and the area of physeal involvement. In an adolescent with little growth remaining, observation may be the best method. LLD should be assessed by a scanogram. An estimation of predicted growth remaining in the contralateral unaffected physis should be made and appropriate lengthening or epiphysiodesis should be carefully timed, especially in the lower limbs.
Table 1
Growth disruption without formation of a bony bridge or a physeal bar Some physeal injuries do not create a bony bar but still cause a slowing of growth in a part of the physis resulting in an angular deformity. Complete cessation of growth is uncommon. The hallmark of this phenomenon is the loss of normal physeal
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Figure 8 Types of bar formation in the physis.
64% in SaltereHarris Type IV. Surgical fixation lowered the incidence of growth disturbance from 37% to 27%.
In younger age group with significant growth remaining, surgical options will be: arrest of the remaining growth of the injured physis e this could be considered in older children with mild angular deformity and expected minor LLD arrest of the remaining growth of the physis and corresponding physes of contralateral bones to address both LLD and angular deformity combination of physeal arrest with opening or closing wedge osteotomies to correct angular deformities lengthening or shortening of involved bone (shortening can only be considered for the femur) resection of bony bar and interposition material guided bone and physeal growth to correct angular and linear growth discrepancy with use of ‘8’ plates or staples, which straddle the physis and slow growth on side of fixation. 3. Growth acceleration Physeal fractures with epiphyseal displacements can on rare occasion result in accelerated growth of the affected bone and is usually very short lived due to rapid healing of the physis. Hence this increased growth is rarely of any significance.
Distal tibia Leary JT et al have reported the incidence of premature physeal closure (PPC) in distal tibial physeal injuries.15 Their series showed an overall incidence of PPC was 12%, with 0% PPC in SaltereHarris I; 25% PPC in SaltereHarris II; 10% PPC for all SaltereHarris III; 18% in SaltereHarris IV. They also highlighted that high-energy injuries are associated with growth disturbance in any type of physeal injury, reporting the rate of PPC by mechanism of injury as 8% from sports, 86% from motor vehicle accidents and 6% from falls. Russo et al16 showed that the patients with displaced Saltere Harris Type II distal tibia fractures pose a challenging problem with a high rate of growth arrest (43% overall). Initial displacement, the injury mechanism and residual displacement were predictive factors associated with growth arrest. Surgical fixation does not reduce the incidence of PPC.16 With 2e4 mm of displacement who were treated conservatively, 33% had a PPC and with more than 4 mm of displacement treated with ORIF had a PPC rate of 55%.
Data on specific physeal injuries and growth disturbances
Distal radius According to Cannata et al17 shortening of 1e6.5 cm occurred in 4.4% of distal radial physeal fractures and in 50% of distal ulna physeal fractures. Patients with length discrepancy of less than 1 cm were asymptomatic, as were patients with ulnar styloid nonunion. Of the patients with greater than 1 cm of length discrepancy, only 20% had severe functional deficits.
Proximal femur Approximately, 2% of paediatric hip dislocations have separation of the proximal femoral physis. This is a high-energy injury, with a reported avascular necrosis rate of 100%, and frequently catastrophic outcomes. This should be treated with anatomical reduction, either by closed or open means.
Conclusion
Distal femur Most of these fractures are caused by high-velocity motor vehicle accidents with severe displacement or multiple associated fractures with a high risk of physeal arrest. An anatomic reduction is desirable and an incompletely reduced epiphyseal injury is associated with poor outcomes.13,14 According to the meta-analysis by Basener et al14 52% of distal femoral physeal injuries showed growth disturbance ranging from 36% in SaltereHarris Type I to
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Physeal injuries are common in our day-to-day practice and when treated properly, usually have a favourable outcome without significant long-term sequelae. They must be treated gently and expertly to maximize restoration of normal limb function and longitudinal growth. Depending on the severity and nature of physeal injury, long-term follow-up to identify the development of physeal growth disturbance is important. A
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REFERENCES 1 Bright RW, Burstein AH, Elmore SM. Epiphyseal-plate cartilage: a biomechanical and histological analysis of failure modes. J Bone Joint Surg Am 1974; 56: 688e703. 2 Langenskiold A. Role of the ossification groove of Ranvier in normal and pathological bone growth: a review. J Pediatr Orthop 1998; 18: 173. 3 Trueta J, Morgan JD. The vascular contribution to osteogenesis: studies by the injection method. J Bone Joint Surg 1960; 43B: 97. 4 Dale GG, Harris WR. Prognosis of epiphyseal separation: an experimental study. J Bone Joint Surg Br 1958; 40-B: 116e22. 5 Moen CT, Pelker RR. Biomechanical and histological correlations in growth plate failure. J Pediatr Orthop 1984; 4: 180e4. 6 Rennie L, Court-Brown CM, Moka JYQ, Beattie TF. The epidemiology of fractures in children. Injury 2007; 38: 913e22. 7 Ogden JA. Skeletal injury in the child. New York: Springer-Verlag, 2000. 8 Ogden JA. Injury to the growth mechanisms of the immature skeleton. Skeletal Radiol 1981; 6: 237e53. 9 Mann DC, Rajmaira S. Distribution of physeal and non-physeal fractures of long bones in children aged 0 to 16 years. J Pediatr Orthop 1990; 10: 713.
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10 Salter R, Harris W. Injuries involving the epiphyseal plate. J Bone Joint Surg Am 1963; 45A: 587e622. 11 Rang M. The growth plate and its disorders. Baltimore: Williams & Wilkins, 1969. 12 Peterson CA, Peterson HA. Analysis of the incidence of injuries to the epiphyseal growth plate. J Trauma 1972; 12: 275e81. 13 Arkader A, Warner Jr WC, Horn BD, Shaw RN, Wells L. Predicting the outcome of physeal fractures of the distal femur. J Pediatr Orthop 2007; 27: 703e8. 14 Basener CJ, Mehlman CT, DiPasquale TG. Growth disturbance after distal femoral growth plate fractures in children: a metaanalysis. J Orthop Trauma 2009; 23: 663e7. 15 Leary JT, Handling M, Talerico M, Yong L, Bowe JA. Physeal fractures of the distal tibia: predictive factors of premature physeal closure and growth arrest. J Pediatr Orthop 2009; 29: 356e61. 16 Russo F, Moor MA, Mubarak SJ, Pennock AT. SaltereHarris II fractures of the distal tibia: does surgical management reduce the risk of premature physeal closure? J Pediatr Orthop 2013; 33: 524e9. 17 Cannata G, De Maio F, Mancini F, Ippolito E. Physeal fractures of the distal radius and ulna: long-term prognosis. J Orthop Trauma 2003; 17: 79e80. 172e9; discussion.
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Physeal injuries in children
primary ossification centres form in the middle of the bone. This primary ossification centre expands towards the proximal and distal ends of the bone. The peripheral extensions of the primary ossification centre at either ends of the bone gives rise to the growth plate or the physis, a cartilaginous disc separating the epiphysis from the metaphysis. The physis is responsible for the longitudinal growth of long bones. When skeletal maturity is reached, physes are resorbed and replaced by bone.
Arijit Mallick Hari Prem
Physeal structure (Figure 1) Histologically, a physis is formed with chondrocytes surrounded by extracellular matrix. Chondrocytes are arranged in a columnar fashion along the longitudinal axis of the long bone and grow towards the metaphysis where the endochondral ossification occurs. A physis is divided from distal to proximal into zones according to the rate of growth, numbers and distribution of chondrocytes. It is important to understand these zones in order to understand various types of physeal injuries. These are the: reserve zone (also known as germinal zone or resting zone) proliferative zone hypertrophic zone zone of endochondral ossification The hypertrophic zone is further subdivided into: zone of maturation zone of degeneration zone of provisional calcification There are two important structures on the periphery of the physis2 (Figures 1 and 2), which are the: groove of Ranvier: a circumferential notch described by Ranvier which provides chondrocytes to the periphery for lateral growth perichondrial ring of LaCroix: a dense fibrous tissue, where the periosteum of the bone is attached to the perichondrium of epiphysis and gives mechanical support to the bone-physis interface.1
Abstract Fractures involving the physis account for up to one-third of paediatric fractures. It is also the structure which needs to be preserved to ensure normal growth. The relative strength of the physis changes with age and it becomes weaker as the child grows older, making physeal injuries more common in adolescence. It is important to understand the physeal anatomy and its relevance to different types of physeal injuries. SaltereHarris system is a clinically useful approach to classifying and describing physeal injuries. Each physeal injury should be treated as a distinct entity taking into account the patient’s age, location of injury, type of injury, growth potential of the affected part, degree of displacement and time elapsed since injury. Its treatment ranges from conservative management to operative fixation. Manipulation of physeal fractures should be as gentle as possible to prevent growth plate damage leading to growth disturbances. These complications can be difficult and complex to manage. The management involves two phases: the first phase should ensure reduction, maintenance of reduction, and bone healing; the second phase involves monitoring the growth with long-term follow-up, to detect any deformities from growth arrests or disturbances. Counselling parents about the potential risk of future growth arrest and deformity is important.
Keywords Bony bars; growth arrest; paediatric fracture; physis; SaltereHarris
Introduction The weakest area in a child’s bone is the physis or the growth plate. It is also a structure which needs to be preserved to ensure normal growth after the injury. As long as the epiphysis remains more cartilaginous, it acts as a shock absorber and forces are transmitted to metaphysis. Hence there is a higher chance of torus fracture (buckle fracture) in younger children.1 The relative strength of the physis changes with age and it becomes weaker as the child grows older, making physeal injuries more common in adolescence.
Blood supply to the physis (Figure 2) It is important to know the vascular distribution in the various zones to understand it’s contribution to the prognosis in physeal injuries.3,4 Blood supply to the physis comes from three sources:3 epiphyseal circulation metaphyseal circulation perichondrial circulation. Epiphyseal circulation: small branches come out from the main epiphyseal artery, enter the epiphysis and pass through small cartilage canals into the reserve zone. None of the branches from the epiphyseal arteries penetrates beyond the proliferative zone to supply the hypertrophic zone. Dale and Harris4 mentioned two types of epiphyseal circulation (Figure 2): Type A: The epiphysis is almost completely covered with articular cartilage and is dependent on blood supply through the perichondrium, making it vulnerable to ischaemia after physeal separation. Examples include the proximal humerus and proximal femur (Figure 2, bottom right). Type B: The epiphysis is only partly covered with articular cartilage and has blood supply which enters it directly.
Relevant anatomy At around 6 weeks of gestation the long bones are formed from mesenchymal anlage. Then at around 8 weeks of gestation
Arijit Mallick FRCS (T&O) is a Senior Foot and Ankle Fellow at the Royal Orthopaedic Hospital, Birmingham, UK. Conflicts of interest: none declared. Hari Prem FRCS (T&O) is a Consultant Foot and Ankle Surgeon at the Royal Orthopaedic Hospital, Birmingham, UK. Conflicts of interest: none declared.
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These arteries pass vertically towards the boneecartilage junction of the physis. However, no vessels pass from the metaphysis into the hypertrophic zone. Perichondrial circulation: the groove of Ranvier and the perichondrial ring of LaCroix, are richly supplied with blood from perichondrial arteries. Significance of vascularity and zone of physeal injuries5 The strength of the physis is related to the morphology of the cells and to the intercellular matrix. Owing to good vascularity, there is an abundance of extracellular matrix in the reserve and proliferative zones helping them resist shear forces better. On the other hand, extracellular matrix formation is significantly less in the hypertrophic zone due to its avascularity, and it has reduced capacity to withstand shear, bending and tension forces. Hence more physeal injuries occur through the hypertrophic zone. Beyond that, the zone of endochondral ossification is reinforced by calcification and hence is stronger.4,5
Figure 1 Structure of the physis.
Incidence of physeal injuries6e9 Physeal fractures account for up to 30% of all paediatric fractures. Boys are affected twice as often as girls, probably because their physes remain open longer and they are exposed to more traumas due to athletic activities.1,6e9 The peak incidence is around 14 years in boys and 11 years in girls. The upper limb is most likely to be affected, with the distal radius being the most common site of fractures in children and ankle the second most common site.6e9
Classification Various radiograph-based classification systems have been described, of which the SaltereHarris system is most widely used. SaltereHarris (SH) system10 (Figure 3) This classification is based on five fracture patterns. It helps guide the treatment as well as the prognosis. There is progressively more chance of growth arrest as you move up through the classification. This classification system also has a good reproducibility. Types IeV was described by Robert Salter and Robert Harris in 1963:10 Type I: transverse fracture through the physis Type II: fracture through the physis and the metaphysis, sparing the epiphysis Type III: fracture through physis and epiphysis, sparing the metaphysis Type IV: fracture through the physis, metaphysis, and epiphysis Type V: compression fracture of the growth plate (resulting in a decrease in the perceived space between the epiphysis and metaphysis on X-ray)
Figure 2 Blood supply of the physis. (a) The three sources of blood supply to physis: epiphyseal, metaphyseal and perichondrial. (b) Two types of epiphyseal blood supply as described by Dale and Harris.
These are at lesser risk of ischaemia following injury. Examples include the distal radius, proximal tibia (Figure 2, Bottom left), distal tibia and distal femur. Metaphyseal circulation: the metaphysis is richly supplied with blood from the terminal branches of the nutrient artery.
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Figure 3 Classifications of physeal SH, SaltereHarris.
Ogden VII: epiphyseal fractures from articular surface through epiphyseal cartilage and into secondary ossification centre, but not involving the physis Ogden VIII: metaphyseal fractures affecting later growth through vascular insult Ogden IX: severe fragmentation of the diaphysis causing periosteal damage interrupting blood supply to the physis, which may affect later growth
Rang added Type VI to the original classification11 (Figure 3): Type VI: avulsion injury to the peripheral portion of the physis (after which a bridge formation may result in significant angular deformity due to its peripheral location) Ogden7,8 included three further injuries, to the original physeal injury classification of Salter and Harris, which could affect growth mechanisms (Figure 3):
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Peterson retained SaltereHarris types I through IV as Peterson types II, III, IV, and V and added two new types12 (Figure 3): Peterson I: fracture across metaphysis with extension into physis but no extension along the physis Peterson VI: fracture where a portion of physis is missing and it some cases it may be associated with loss of the adjoining metaphysis and epiphysis
Individual physeal injury and its treatment Results of treatment of physeal injuries depend on the severity of injury, its anatomic location, age of the patient and timing of intervention. The age of the child is an important factor, because remodelling potential depends on the number of years of growth remaining before closure of the physis.13e17 Different physes have different growth potentials. For example, the distal physis of femur contributes 70% of the growth in length of the femur while the capital femoral physis has only a 30% contribution. Physeal injuries become ‘sticky’ and unite very quickly, in both good and unacceptable positions. Therefore, these fractures should preferably be reduced within 24 hours of presentation where possible and should not be left for a ‘next available clinic’ or treated expectantly. Reduction should be early and gentle, avoiding any additional iatrogenic trauma to the original trauma. If an acceptable reduction is not possible with gentle manipulations, open reduction should be considered promptly. If an injury is several days old or if the original reduction is lost, a careful decision has to be made to assess if the deformity justifies a late attempt at reduction, given the chances of it not being likely to move with gentle manipulation. Frequently CT scans are undertaken to determine the exact nature of the severely comminuted epiphyseal and metaphyseal fragments, which may not be seen and properly evaluated on plain radiographs.
Figure 5 CT scan of SaltereHarris Type II.
arthrography may be required to confirm diagnosis. In infants, even if it is displaced it is invisible due to the lack of an ossific nucleus at the bone end. However, in infants there is remodelling to normal alignment, even if the displacement is not reduced. Type I fractures are often stable and treated by closed means. Maintaining a satisfactory alignment between the metaphysis and epiphysis will give a generally excellent prognosis. Healing is rapid for Type I fractures, occurring within 2e3 weeks of injury. Problems are rare, with the exception of completely displaced proximal femur epiphysis, which has a high risk of avascular necrosis. Type II is the commonest SaltereHarris pattern (75%). The metaphyseal fragment is known as the Thurston Holland fragment (Figure 5). The treatment for this type of displaced fractures involves careful gentle closed reduction and immobilization, which can involve transfixing K-wires. Occasionally a flap of periosteum may be entrapped between the epiphysis and the metaphysis, blocking reduction. This requires careful surgical exploration to remove the entrapped periosteum before appropriate reduction and immobilization. The prognosis for healing with this type of injury is good.
Types I and II Type I accounts for 6% of all physeal injuries. These are rare and are observed most frequently in infants. These commonly involve the proximal or distal humerus and the distal femoral physes but can also be seen in distal radius (Figure 4) Slipped upper femoral epiphysis (SUFE) can be regarded as a Type I injury. An undisplaced Type I fracture will appear normal on plain radiograph. Therefore, careful clinical assessment and sometimes the use of an ultrasound scan or MRI scan or
Remodelling potential in Type I and Type II injuries Generally a bigger residual angular deformity is better tolerated in the upper extremity than in the lower extremity. Similarly residual valgus deformity is tolerated better than varus, and flexion deformity can be tolerated better than those in extension. About 74% of remodelling occurs at the physis and 26% at diaphysis.13e17 When the asymmetry is in the plane of joint motion (flexion and extension), spontaneous correction of angular deformities is greatest. An accurate reduction is more important at the ankle and knee because most of the time the deformity is not in the plane of motion of these joints. Types III and IV Type III accounts for 8% of all physeal injuries. They are more commonly seen in older children where the growth
Figure 4 Radiograph of SaltereHarris Type I.
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fracture in the ankle (Figure 7) or in separation of the lateral condyle of the distal humerus. Type IV ankle fractures of the tibia are also seen together with triplane fractures. If treated properly, the prognosis is good, but patients should have long-term follow-up to detect growth disturbance. Overall, the situation is more complex with Type III and Type IV injuries. Type III and Type IV injuries involve the articular surface and hence anatomic reduction is essential. These injuries require prompt and accurate reduction and some form of fixation, either by open reduction and internal fixation or by percutaneous fixation. Inaccurate reduction causes a mismatch of the layers (physis, epiphysis, metaphysis) and can result in a non-union and the lateral condyle fracture is particularly prone to it. Open reduction internal fixation (ORIF) can be considered for many weeks after injury as remodelling at the articular surface will not occur although outcomes become increasingly poor with time.13e17 Type V happens when there is a compression injury to the physis. The initial radiographs are usually normal and these injuries are recognized in hindsight, when an angular deformity or a leg length discrepancy develops later due to physeal fusion. An example for this is recurvatum deformity due to growth arrest affecting the proximal tibial physis.
Figure 6 CT scan of SaltereHarris Type III.
Complications of physeal fractures
plates have started to close. When part of the physis is open it forms a weak site susceptible to fracture compared to the part of the bone with a closed physis (Figure 6). Displaced injuries may result in a physeal bar formation, leading to growth disturbance and joint incongruity and possible arthritis. Treatment usually involves an anatomic open reduction and stabilization with wires or screws to restore articular congruency. We must endeavour to avoid penetration of the joint and the physis with the screws wherever possible. Hence the screws are applied parallel to the physis. When treated properly, the prognosis is good. Type IV accounts for 10% of all physeal injuries. Examples of this fracture pattern can be seen in medial malleolus
The complications associated with physeal fractures will be similar to those of any other fractures, along with the specific complication of physeal growth arrest which can lead to angular deformity or limb length discrepancy (LLD) or growth acceleration. The acceptable limit of angulation or displacement following physeal injury varies between its anatomical location (Table 1). Growth disturbance Disturbance of normal physeal growth can happen after a physeal injury due to physical loss of the physis, disruption of normal physeal architecture and function (without loss of the physis), or formation of a bony bridge or physeal bar.14e16
Figure 7 Radiograph showing SaltereHarris Type IV and its surgical fixation (note that the screws are placed parallel to the physis).
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contour and the sharply defined radiolucency between epiphyseal and metaphyseal bone on radiographs. This happens because of alteration in normal enchondral ossification caused by the physeal injury. There may be an asymmetric growth arrest line indicating angular deformity, but the arrest line will not taper to the physis itself. This indicates an altered physeal growth (either asymmetric acceleration or deceleration) but not a complete cessation of growth.
General tolerances for physeal fracture displacement and angulation (Nelson and Wongworawat’ 2009)16 Region
Degree of angulation/ displacement
Distal femur (SHI or SHII)
5 e10 varus/valgus 10 e20 flexion/extension Anatomic reduction
Intra-articular fractures (SHIII or SHIV) Distal tibia (SHI or SHII)
Distal tibia (SHIII or SHIV) Distal tibia (triplane SHII, posterior metaphyseal spike) Distal tibia (triplane SHIV anterolateral epiphyseal fragment) Proximal humerus
If >2 years’ growth remaining 15 plantar tilt 10 valgus for laterally displaced fractures 0 varus for medially displaced fractures If <2 years’ growth remaining <5 angulation in any plane <1 mm displacement or <2 mm gap <2 mm displacement
Growth arrest with formation of a bony bridge or a physeal bar As the Type I and II fracture lines spare the reserve and proliferative zones, growth disturbances are generally thought to be uncommon, although published studies do not always reflect this view. Type III and IV fractures, traverse all the zones and are more prone to growth arrest and formation of bony bars, especially if the displaced fragment is not anatomically reduced. Established physeal bars are typically characterized by sclerosis in the region of the arrest. If asymmetric growth has occurred, there may be tapering of a growth arrest line to the area of arrest, angular deformity, epiphyseal distortion, or shortening. This distinction in the direction of the growth arrest line is important, because the consequences and treatment are different from those caused by complete growth arrest.
<2 mm displacement
70 angulation, 100% displacement if <5 years 40 e70 angulation, if 5e12 years 40 angulation and 50% displacement if >12 years <2 mm
Evaluation of physeal growth arrest Evaluation with CT scanning with sagittal and coronal reconstructions may demonstrate clearly an area of bone bridging the physis between the epiphysis and metaphysis. Three basic patterns of physeal arrests are recognized (Figure 8): Central: an island of arrest within the remaining physis. Central arrests are most likely to cause tenting of the articular surface, although it may also result in angular deformity if eccentrically located and occasionally in limb length inequality. Peripheral: it is located at the perimeter of the affected physis. This type of arrest primarily causes progressive angular deformity and variable shortening. Linear: it is a lesion with anatomic characteristics of both a central and peripheral arrest. Specifically, the affected area extends up to the perimeter of the physis, but there is normal physis on either side of it. Linear arrests most commonly develop after SaltereHarris Type III or IV physeal fractures of the medial malleolus.
Distal humerus (lateral condyle, SHII or SHIV) Distal humerus (medial condyle, <2 mm SHII or SHIV) Distal humerus (transphyseal) No numeric recommendations, but CRPP recommended if unstable or significantly displaced Distal humerus (T-condylar, SHIII <1 mm or SHIV) Proximal radius (radial neck, SHI <45 angulation 50% displacement and SHII 50 e60 clinical pronation or Supination Proximal radius (involving radial <2 mm intra-articular gap/step head) SHIII and SHIV Proximal ulna (olecranon) <5 mm Distal radius 30 angulation, if < than 10 years 15 angulation, if >10 years old CRPP, closed reduction percutaneous pinning; SH, SaltereHarris.
Treatment of bony bars Treatment depends on the age of the patient, location of the physis and the area of physeal involvement. In an adolescent with little growth remaining, observation may be the best method. LLD should be assessed by a scanogram. An estimation of predicted growth remaining in the contralateral unaffected physis should be made and appropriate lengthening or epiphysiodesis should be carefully timed, especially in the lower limbs.
Table 1
Growth disruption without formation of a bony bridge or a physeal bar Some physeal injuries do not create a bony bar but still cause a slowing of growth in a part of the physis resulting in an angular deformity. Complete cessation of growth is uncommon. The hallmark of this phenomenon is the loss of normal physeal
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Figure 8 Types of bar formation in the physis.
64% in SaltereHarris Type IV. Surgical fixation lowered the incidence of growth disturbance from 37% to 27%.
In younger age group with significant growth remaining, surgical options will be: arrest of the remaining growth of the injured physis e this could be considered in older children with mild angular deformity and expected minor LLD arrest of the remaining growth of the physis and corresponding physes of contralateral bones to address both LLD and angular deformity combination of physeal arrest with opening or closing wedge osteotomies to correct angular deformities lengthening or shortening of involved bone (shortening can only be considered for the femur) resection of bony bar and interposition material guided bone and physeal growth to correct angular and linear growth discrepancy with use of ‘8’ plates or staples, which straddle the physis and slow growth on side of fixation. 3. Growth acceleration Physeal fractures with epiphyseal displacements can on rare occasion result in accelerated growth of the affected bone and is usually very short lived due to rapid healing of the physis. Hence this increased growth is rarely of any significance.
Distal tibia Leary JT et al have reported the incidence of premature physeal closure (PPC) in distal tibial physeal injuries.15 Their series showed an overall incidence of PPC was 12%, with 0% PPC in SaltereHarris I; 25% PPC in SaltereHarris II; 10% PPC for all SaltereHarris III; 18% in SaltereHarris IV. They also highlighted that high-energy injuries are associated with growth disturbance in any type of physeal injury, reporting the rate of PPC by mechanism of injury as 8% from sports, 86% from motor vehicle accidents and 6% from falls. Russo et al16 showed that the patients with displaced Saltere Harris Type II distal tibia fractures pose a challenging problem with a high rate of growth arrest (43% overall). Initial displacement, the injury mechanism and residual displacement were predictive factors associated with growth arrest. Surgical fixation does not reduce the incidence of PPC.16 With 2e4 mm of displacement who were treated conservatively, 33% had a PPC and with more than 4 mm of displacement treated with ORIF had a PPC rate of 55%.
Data on specific physeal injuries and growth disturbances
Distal radius According to Cannata et al17 shortening of 1e6.5 cm occurred in 4.4% of distal radial physeal fractures and in 50% of distal ulna physeal fractures. Patients with length discrepancy of less than 1 cm were asymptomatic, as were patients with ulnar styloid nonunion. Of the patients with greater than 1 cm of length discrepancy, only 20% had severe functional deficits.
Proximal femur Approximately, 2% of paediatric hip dislocations have separation of the proximal femoral physis. This is a high-energy injury, with a reported avascular necrosis rate of 100%, and frequently catastrophic outcomes. This should be treated with anatomical reduction, either by closed or open means.
Conclusion
Distal femur Most of these fractures are caused by high-velocity motor vehicle accidents with severe displacement or multiple associated fractures with a high risk of physeal arrest. An anatomic reduction is desirable and an incompletely reduced epiphyseal injury is associated with poor outcomes.13,14 According to the meta-analysis by Basener et al14 52% of distal femoral physeal injuries showed growth disturbance ranging from 36% in SaltereHarris Type I to
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Physeal injuries are common in our day-to-day practice and when treated properly, usually have a favourable outcome without significant long-term sequelae. They must be treated gently and expertly to maximize restoration of normal limb function and longitudinal growth. Depending on the severity and nature of physeal injury, long-term follow-up to identify the development of physeal growth disturbance is important. A
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10 Salter R, Harris W. Injuries involving the epiphyseal plate. J Bone Joint Surg Am 1963; 45A: 587e622. 11 Rang M. The growth plate and its disorders. Baltimore: Williams & Wilkins, 1969. 12 Peterson CA, Peterson HA. Analysis of the incidence of injuries to the epiphyseal growth plate. J Trauma 1972; 12: 275e81. 13 Arkader A, Warner Jr WC, Horn BD, Shaw RN, Wells L. Predicting the outcome of physeal fractures of the distal femur. J Pediatr Orthop 2007; 27: 703e8. 14 Basener CJ, Mehlman CT, DiPasquale TG. Growth disturbance after distal femoral growth plate fractures in children: a metaanalysis. J Orthop Trauma 2009; 23: 663e7. 15 Leary JT, Handling M, Talerico M, Yong L, Bowe JA. Physeal fractures of the distal tibia: predictive factors of premature physeal closure and growth arrest. J Pediatr Orthop 2009; 29: 356e61. 16 Russo F, Moor MA, Mubarak SJ, Pennock AT. SaltereHarris II fractures of the distal tibia: does surgical management reduce the risk of premature physeal closure? J Pediatr Orthop 2013; 33: 524e9. 17 Cannata G, De Maio F, Mancini F, Ippolito E. Physeal fractures of the distal radius and ulna: long-term prognosis. J Orthop Trauma 2003; 17: 79e80. 172e9; discussion.
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