Overview
The epiphysis and epiphyseal plate are both growth structures of immature bones, and epiphyseal plate injuries are customarily called epiphyseal injuries (rnjury epiphysis), where the fracture line can affect both the epiphysis or epiphysis in addition to the epiphyseal plate. Each epiphysis and its epiphyseal plate together form the epiphyseal complex, and growth and blood supply are interdependent, so any one of these injuries may have a causal effect on the other. The longitudinal growth of the long bones of the extremities is the result of the proliferation of disc-shaped epiphyseal plates that are under pressure at both ends, and the inherent growth potential of these plates is so great that impairment of their function can severely affect epiphyseal development, resulting in limb shortening or joint deformity. Approximately 15% of pediatric fractures involve epiphyseal injuries, more in boys than in girls, because boys are more likely to be traumatized and the epiphyseal plate closes later in males than in females. Some epiphyseal injuries can result in premature closure of the epiphyseal plate, causing impaired epiphyseal growth and producing limb deformity and shortening. In addition to trauma, bacterial infections and other diseases can also cause this disease. If these injuries are not well understood, clinical errors in diagnosis and underestimation of prognosis can easily occur. In order to correctly diagnose and manage these injuries, clinicians must have a basic understanding of epiphyseal development.
Anatomy and anatomy and physiology
There are two ways for blood vessels to enter the epiphysis (Figure 1), one common way is that the side of the epiphysis is covered with soft tissue and blood vessels enter the epiphysis directly through the soft tissue at a site far from the epiphyseal plate, and more than one vessel often enters. In this case, the blood vessels are less likely to be damaged when the epiphysis is separated. In the other case, the entire epiphysis is within the joint, covered by articular cartilage, and the blood vessels enter through the articular cartilage immediately adjacent to the edge of the plate. The femoral epiphysis and the radial head epiphysis fall into this category, which is known as the intra-articular epiphysis. Once the epiphysis is separated, the blood vessels are often damaged, causing ischemia of the epiphysis and the epiphyseal plate.
2. Blood supply to the epiphyseal plate The blood supply to the epiphyseal plate is divided into two groups: one group comes from the epiphyseal system, where branches of the epiphyseal artery cross the bone plate into the germinal cell layer, forming terminal vascular collaterals that provide nutrition for cartilage development. Therefore, the impaired blood supply to the epiphysis directly affects the ability of the epiphyseal plate to proliferate. Another group of vessels in the epiphyseal plate comes from the epiphyseal system, where the terminal branches of the epiphyseal artery and the trophoblastic artery enter the cellular degeneration layer of the epiphyseal plate in the form of collaterals. The role of this group of vessels is to remove the degenerated and dead chondrocyte remnants through the assistance of macrophages and, more importantly, to promote the deposition of new bone to complete the final process of osteogenesis within the cartilage. If there is a problem with this group of vessels, the cartilage matrix cannot calcify and the mast cells cannot accumulate to form bone.
3. Anatomy and physiology The epiphysis is in the process of growth and maturation, and the articular end of the bone consists of articular cartilage, epiphysis, unclosed cartilage plate – epiphyseal plate and epiphysis. The articular cartilage is immature hyaline cartilage, which is supplied by synovial fluid and partly by osteophytes in the epiphyseal nucleus, but the nutrition of mature cartilage mainly comes from synovial fluid, and the subchondral bone plate at the junction of bone and cartilage becomes a barrier for blood transport. After birth, the bony ends of the fetal long bones successively appear in their center as secondary ossification centers, i.e., epiphyses, producing bone tissue that gradually expands in all directions, preserving cartilage forever at one end, i.e., the articular cartilage described above. The cartilage between the epiphysis and the epiphysis is called the epiphyseal plate. The cartilage of the epiphyseal plate remains proliferative for a long period of time so that the cartilage continues to proliferate and the cartilage simultaneously degenerates and then ossifies, not only keeping the cartilage of the epiphyseal plate at a certain thickness, but also the process of ossification makes the backbone grow. After puberty, the epiphyseal plate cartilage loses its proliferative capacity and completely ossifies, forming an epiphyseal remnant, from which the long bones stop growing. The epiphyseal plate structure can be divided into three layers based on histological and functional characteristics: the growth layer, the maturation layer, and the transformation layer (Figure 2). The growth layer is associated with the longitudinal and lateral development of the bone. At the beginning, chondrocytes are small but vascular and provide undifferentiated cells, which grow slowly. Gradually, chondrocytes divide and proliferate, and the cells become larger both longitudinally and laterally and arrange themselves into columnar growth along the long axis of the bone, dividing the growth layer into a stationary zone and a columnar zone. The columnar cell zone occupies half of the thickness of the epiphyseal plate. When entering the mature layer, the chondrocytes become hypertrophic and lose their proliferative capacity, the cell matrix of this layer becomes thinner and the cartilage matrix calcifies, dividing this layer into the hypertrophic and calcified zones. The last layer is the chondrocyte transformation layer. There are two different theories about the end of mature chondrocytes. In one view, calcification of the cartilage matrix causes the chondrocytes to degenerate and die from lack of nutrients, but the layer has blood vessels that grow in and provide the necessary osteoblasts for ossification; in the other view, the chondrocytes transform into osteoblasts, which are wrapped around the remaining calcified cartilage matrix to produce bone tissue and form bone trabeculae. This layer is divided into a zone of vascular ingrowth and a zone of ossification. In the epiphysis, these trabeculae are called primitive trabeculae, which remain briefly and are successively destroyed and resorbed by osteoclasts, while new trabeculae are formed and gradually matured by shaping. The process of osteogenesis consists of the gradual expansion of the secondary ossification centers to the ends of the diaphysis, resulting in continuous bone lengthening, but the expansion of the secondary ossification centers depends on the continuous proliferation and maturation of chondrocytes at the ends of the diaphysis.
Diagnostic points
Overview of diagnostic points
Epiphyseal development and injury characteristics: Because the function, stress characteristics and ossification time of epiphysis are different in each part, therefore, the age of onset and injury characteristics are different, some injuries only appear in a certain age, and some injury types only occur in a certain part, so it is helpful to understand these rules for clinical diagnosis.
1, the pivotal dentition dentition originated from the pivotal vertebral body, in the embryonic stage manifested as the pivotal vertebrae upward upright cartilaginous protrusion. About in the embryonic 6th month on both sides of its ossification center, at birth usually has been fused into a cylinder, but at the tip there is still a cleft remains, 2 years old can appear again an ossification center, generally before the age of 12 years can complete ossification. The base of the pivotal vertebra and the odontoid are separated by a cartilaginous plate, which begins to ossify at age 4 and forms an ossified joint at age 7, but about 1/5 of the cartilaginous plate is incompletely ossified, resulting in some cartilage remaining between the odontoid and the vertebral body, which becomes a weak point and is susceptible to fracture under external force, and is called a separation of the odontoid epiphysis before ossification (Figure 2). It has been reported that odontoid fractures account for 75% of pediatric cervical spine injuries. The absence of characteristic clinical manifestations, fewer symptoms, lighter signs, and the inability of the pediatric patient to clearly express his or her symptoms and history of injury constitute the main reasons for clinical underdiagnosis of a separated dentate epiphysis, which is usually followed by mild occipital greater nerve pain or sensory hypersensitivity. Atlantoaxial fracture is a serious cervical spine injury that often leads to atlantoaxial instability and acute injury to the cervical spinal cord or even death. However, damage to the atlantoaxial spine and its intervertebral joints and connecting ligaments, with disruption of normal anatomic function and limitation of motor function in between, is called traumatic instability. This traumatic instability is the cause of secondary spinal cord injury or nerve root injury.
2.Shoulder The proximal humeral epiphysis has three ossification centers, the humeral head, the greater tuberosity and the lesser tuberosity, which appear at the age of half, three and four years, in that order. The greater tuberosity and the humeral head epiphysis fuse into one at the age of about five years, and an arc-shaped translucent fissure is visible between the two before complete fusion, which should not be mistaken for a fracture line. The epiphyseal plate of the humeral head is conical, with the base underneath and slightly tilted backward with the direction of the head, thus the anterior-posterior view shows two epiphyseal lines, and the distal epiphyseal line is easily mistaken for the fracture line.
3. Elbow The most common epiphyseal injury in the elbow is a fracture or separation of the epiphysis of the humeral epicondyle (epiphysis), which occurs mostly after preschool. The fracture line through the epiphysis is parallel to the epiphyseal line and can easily be overlooked or mistaken for the epiphyseal line. The latter is located immediately adjacent to the epiphysis, while the fracture fragment is located lower and at a certain distance from the epiphysis. Because the epiphysis is not ossified at birth, a fracture of the distal humeral epiphysis can be misdiagnosed as a dislocation of the elbow joint. After the appearance of the epiphysis, the separation of the epiphysis needs to be distinguished from an epiphyseal fracture or an epicondylar fracture combined with elbow dislocation. It is easy to distinguish the separation of the epiphysis from the latter two injuries by mastering the characteristics that the epiphysis of the epicondyle does not rotate and the humeral radial joint always maintains a normal alignment relationship. If there is a hazy visible bone fragment or triangular bone fragment next to the separated medial epicondyle prominence, it should be considered as a total epiphyseal separation or medial condyle fracture, and delayed treatment of medial condyle fracture will seriously affect the recovery of joint function.
The distal epiphyseal separation is the most common epiphyseal plate injury, and all of them are type II injuries. The distal bone block is mainly displaced to the dorsal side, and in many cases, the anteroposterior radiographs are normal, but only the lateral radiographs show different degrees of dorsal translation of the epiphysis.
The separation of the femoral head epiphysis is not common, but it is more commonly reported abroad as endocrine-related pathological slipped epiphysis, which is not difficult to diagnose by X-ray. As the femoral head has not yet ossified in newborns, the separation of the epiphysis in birth injury can be easily misdiagnosed as hip dislocation, and the feeling of intra-articular bone rubbing is an important basis for diagnosis.
6. Knee Distal femoral epiphyseal plate injuries are mostly seen in older children and can occur from type I to type VI injuries, but type II, III and IV injuries are more common, and these types of injuries are clinically found to occur in the distal femoral bone, and the distal epiphysis has a tendency to reset itself, therefore, when the clinical signs are suspicious of fracture and the X-ray examination is negative, further search for fracture should be conducted. The widening or narrowing of the epiphyseal plate on the affected side has diagnostic significance, with the widening being consistent with a transient epiphyseal separation and the narrowing being considered a type V injury. If the above tests are negative, lateral stress can be carefully applied to the knee under anesthesia, and the image intensifier can be used to observe for ligament rupture or epiphyseal movement. The upper tibial epiphysis is mostly a type III injury, and total epiphyseal separation is extremely rare, probably due to the unique morphologic structure of the epiphyseal plate and the protection of ligaments across the epiphyseal plate on both sides. Early ossification of the tibial tuberosity often presents as an irregular patchy bone island, which should be clinically differentiated from an avulsion fracture of the humeral tuberosity or a chronic pulling injury of the tuberosity epiphyseal cartilage (Osgood-Schlatter disease).
The distal epiphysis of the fibula and tibia can have various types of epiphyseal plate injuries. For the transient epiphyseal separation of the external ankle due to internal rotation injury or rotational epiphyseal separation due to external rotation torque, both are easily overlooked because of the small displacement and should be judged by the mechanism of injury and clinical signs. Ogden VII type injury is a fracture of the avulsed epiphysis of the medial or lateral ankle, and should be distinguished from the inferior ankle paraphyseal center, which is mostly symmetrical on both sides, with regular and rounded bone fragments, dot-like in the early stage of ossification and triangular in the later stage, with neater edges. There are two less common types of injuries to the lower tibial epiphysis, both of which occur in adolescents nearing the fusion stage of the epiphysis: the Tillaux fracture and the triplane fracture. The former is a type III injury in which the anterolateral epiphysis of the lower tibia is separated and the anterior wall of the bone is attached to the outer ankle by ligaments, usually with little displacement. Tillaux fractures are similar to triplanar fractures in the anteroposterior view and can be distinguished from triplanar fractures in the lateral view, but sometimes the fracture lines in the coronal and sagittal views are not clear and can be mistaken for type II injuries. Therefore, the suspected cases should be further examined on oblique films or CT films.
Typing and staging
In the late 19th century, after the application of X-ray diagnosis in clinical practice, it was possible to recognize epiphyseal plate injuries and distinguish them from fractures. 1898, after reviewing a large number of X-ray films, Poland concluded that there were four types of epiphyseal plate injuries. 1963, Salter-Harris further divided epiphyseal plate injuries into five types on the basis of the above, which have been commonly adopted in clinical practice. Subsequently, at the suggestion of Rang, Salter added the cartilaginous ring at the edge of the epiphyseal plate (also called Ranvier’s cartilaginous groove) as type VI epiphyseal plate injury. The characteristics of each type of injury are described below (Figure 3).
Type I: The fracture line passes through the cellular degeneration layer of the epiphyseal plate cartilage maturation zone, which is the weakest layer of cartilage strength. Most of the pathological epiphyseal separations in neonates, infections or rickets are of this type of injury. Type II: Similar to type I injury, the fracture line mainly passes through the chondrocyte degeneration layer of the epiphyseal plate and folds toward the epiphysis before reaching the edge of the epiphyseal plate, with small pieces of epiphyseal bone on the side of the separated epiphysis and soft tissue hinges on the side of the bone pieces, and most proximal humeral epiphyseal separations are of this type. Type III: Intra-articular fracture, the fracture line starts from the articular surface through the epiphysis into the cartilage growth and maturation zone of the epiphyseal plate, and then 900 turns along the chondrocyte degeneration of the epiphyseal plate straight to the edge of the epiphyseal plate. This type of injury is less common and occurs in the epiphysis at both ends of the tibia. Type IV: It is also an intra-articular fracture in which the fracture line starts at the articular surface and goes through the epiphysis (or epiphyseal cartilage), the whole epiphyseal plate and the epiphysis, and most of the humeral epicondyle fractures and inner ankle fractures are of this type of injury. This type of fracture is unstable, and poor repositioning can easily produce complications. Type V: It is a cartilage compression fracture of the epiphyseal plate caused by vertical crushing violence, which occurs in the epiphysis of the knee and ankle, and is often not found positively on X-ray, making early diagnosis difficult. Due to severe destruction of the cells of the cartilage growth layer and extensive damage to the nutrient vessels from the epiphysis, the epiphyseal plate often loses its growth function and closes prematurely. Type VI: This is a cartilaginous ring or Ranvier’s cartilaginous groove injury of the epiphyseal plate, commonly seen in ankle mower injuries or ligament avulsion fractures of the femoral condyle, with X-rays showing fractures or defects at the edge of the epiphyseal plate, often involving the adjacent epiphysis and metaphysis, which can be treated improperly to form local bridges and secondary deformities.
Ogden noted that Salter’s five-type classification, although a more practical approach, did not include all growth mechanism injuries. He found that epiphyseal fractures and large periosteal defects can temporarily or permanently affect the growth of the nearby epiphyseal plate and diaphysis and should be classified as growth-agency injuries, and therefore devised a more extensive classification scheme of nine types, with each type of injury subdivided into several subtypes, to make the classification more comprehensive and to explain the small number of type I and II fractures with localized premature epiphyseal plate closure or bone bridge formation. The first six types are essentially the same as Salter-Harris’ 6 types of injury, with the addition of three types of growth-agency injuries that do not involve the epiphyseal plate.
The characteristics of each type of injury are briefly described below (Figure 4) Type 1A: The fracture line passes through the cellular degenerative layer of the cartilage maturation zone of the epiphyseal plate. Type 1B: The fracture line passes through the ossification layer of the cartilage transformation zone of the epiphyseal plate. type 1C: Type 1A fracture combined with partial injury to the cartilage growth zone of the epiphyseal plate. Type 2A: The fracture line first passes through the cellular degeneration layer of the epiphyseal plate cartilage maturation zone and then folds toward the epiphysis. Type 2B: Type 2A fracture combined with a fragment of the epiphysis on the side receiving tension. Type 2C: The fracture line passes through the primary cancellous layer of the epiphysis and the separated epiphysis with a thin layer of epiphyseal bone, which may or may not have a triangular bone fragment; this type of injury often occurs when the epiphysis of the finger bone is separated. Type 2D: Type 2A fracture combined with partial epiphyseal plate cartilage growth layer injury. Type 3A: fracture line through the cartilage of the epiphyseal plate in the cellular degenerative layer. Type 3B: Transverse fracture line through the primary cancellous bone of the epiphysis. Type 3C: Type 3A fracture combined with a cartilaginous ring crush or avulsion injury. Type 3D: The fracture involves the epiphyseal cartilage that has not yet ossified without passing through the articular surface, such as an avulsion fracture of the epiphyseal cartilage of the sciatic tuberosity. type 4A: The fracture line begins at the articular surface and passes through the epiphysis (or epiphyseal cartilage), the entire epiphyseal plate, and the epiphysis. Type 4B: Type 4A and 3A compound epiphyseal injuries occur on both sides of the same epiphysis. It is more likely to occur in the distal femoral epiphysis. Type 4C: The fracture line first passes through the epiphyseal cartilage on X-ray and then successively enters the full epiphyseal plate cartilage and the epiphysis. 4D: A unicondylar or bicondylar comminuted fracture with two or more larger bone fragments, each containing three components: the epiphysis, the epiphyseal plate, and the epiphysis. This injury often occurs in rotary mower accidents. Type 5: Compression fracture of the cartilage growth zone of the epiphyseal plate. Type 6: Fracture or defect of the periphyseal plate cartilage ring. Type 7A: Simple nucleus pulposus fracture, not involving the epiphyseal plate, with the fracture line passing through the epiphyseal cartilage and nucleus pulposus.7B: The fracture line passes only through the epiphyseal cartilage at the periphery of the nucleus pulposus, with no positive radiographic findings.7 Type 7 injuries often occur in the inner and outer ankle, humeral tuberosity, and femoral condyles.8 Type 8: Transverse fracture of the epiphysis, which can affect epiphyseal bone growth and contouring, and is mostly transient in nature. Type 9: Large-scale destruction or defect of the periosteum, which affects bone remodeling and intra-membranous osteogenic function.
Differential diagnosis
The diagnosis of epiphyseal injury is based on the presence of swelling and pain in children after trauma to one end of the bone, and the possibility of epiphyseal injury should be alerted by taking X-rays, at least frontal and lateral, and if necessary, the normal side limb as a control. This classification has great clinical significance because it takes into account the mechanism of injury, distinguishes the fracture line through different epiphyseal cell layers, and predicts the degree of impact on bone growth.
Type I The fracture line is not visible on the X-ray, and the cells of the epiphysis and epiphyseal plate are separated from the epiphysis. The section is wavy, passing through the hypertrophic and calcified areas of the mature layer (Figure 6), and the primitive sprouting germ cells of the growth layer of the epiphyseal plate are connected to the epiphysis without damage. This injury is mostly caused by shear violence, and the mature layer of the epiphyseal plate is weak and prone to separation here. Type I injuries, most often seen in young infants, because their epiphyseal plates are thicker and their epiphyseal nuclei are smaller. In general, displacement of the separated epiphysis is smaller than other types of epiphyseal injuries because the child is young and their periosteum is hypertrophic and attached around the epiphyseal plate (Ranvier’s band) impeding displacement. The small displacement makes the X-ray diagnosis difficult, and sometimes a mild widening of the epiphyseal plate thickness may be the only sign, and the diagnosis is even more difficult if the secondary ossification centers are small, when the diagnosis relies mainly on clinical manifestations.
2.Type II This is the most common type of epiphyseal injury. It is characterized by the plane of fracture first separating along the epiphyseal plate and then bringing a triangular portion of the epiphysis, i.e., epiphyseal separation plus partial fracture of the epiphysis, which makes it easier to diagnose than the above-mentioned type I. The part of the epiphyseal plate separating is the same as type I, in the hypertrophic and calcified area, and then turning to the epiphysis, and the triangular bone fragment can be large or small, with the periosteum on that side intact, while the periosteum on the opposite side has been torn. The mechanism of injury is caused by shear forces plus bending moments. It occurs mostly in children over 10 years of age, when their epiphyseal plates are relatively thin.
3, type III This type of injury, from the articular surface through the epiphysis, successively through the resting, splitting, columnar to hypertrophy and calcification zone of the epiphyseal plate, and finally in this zone epiphyseal separation (Figure 7) that is, intra-articular fracture plus epiphyseal separation. This injury is uncommon, caused by intra-articular shear, and usually occurs in the distal tibia.
4, Type IV The fracture line involves the articular surface, the epiphysis, the full epiphyseal plate, and part of the epiphysis (Figure 8), i.e., intra-articular fracture plus epiphyseal plate and epiphysis fracture. If the secondary ossification center is small, a type IV injury is not easily recognized and may be mistaken for a type II injury. If there is a smaller epiphyseal bone fragment and no epiphyseal separation is clinically and radiographically proven, the diagnosis should be type IV, not type II, injury.
5, Type V Severe destruction of the chondrocytes of the epiphyseal plate by compression due to strong crushing violence. This injury is rare, but the consequences are very serious, often leading to deformed bone growth. Because there is no displacement of the injury, X-ray is difficult to diagnose, often mistaken for a “sprain”, until later when there is a growth disorder, recall the history of previous injuries, the disease is not thought of. In addition to mechanical factors, it can also be caused by electric shock injury and radiation, the former is a thermal effect, the latter is due to ischemic necrosis. Where a child has a falling limb injury or an injury involving the vicinity of the epiphysis, and there are no obvious abnormalities on X-ray, but pain and swelling persist for a period of time, that is, one should be alert to the possibility of an epiphyseal plate crush injury, and the parents need to be informed of the possibility of bone growth disorders and regular follow-up for early detection of deformities. At the same time, the child should not be weight-bearing for 3 weeks to avoid further aggravation of the injury.
Complications
1. Bone growth and dysfunction (1) In addition to the complications of general fracture, epiphyseal plate injury is a more important and unique complication that can lead to bone growth and dysfunction. The prognosis is related to the age of the injury, the growth potential of the epiphyseal plate and the extent of involvement, and the epiphysis with a small age of onset and a large growth potential is damaged, and once the complications occur the degree of deformity is serious. (2) Although epiphyseal plate injuries can lead to bone growth disorders, most patients with epiphyseal injuries eventually recover function satisfactorily, and only 5% to 10% of the patients have serious growth effects. (3) There are two causes of epiphyseal plate growth curtailment: (1) premature closure of the epiphyseal plate due to damage to the cartilage in the epiphyseal growth area or impaired blood supply; (2) misalignment healing of type III and IV epiphyseal plate fractures, local formation of bone bridges and curtailment of growth (4) After epiphyseal injury, bone growth disorders occur in about 15% of cases, and the vast majority are caused by type III-V injuries. If the epiphyseal plate of a single bone stops growing (such as the femur), there will be unequal lengths of limbs on both sides. If it consists of two bones (calf or forearm) and one of them is involved, there will be unequal lengths between the tibiofibula or ulnar radius of the same limb, resulting in angular deformities of nearby joints, such as inversion or valgus of the ankle joint; ulnar or radial deformity of the wrist joint. If a portion of the epiphyseal plate undergoes growth disturbance, for example, if the medial epiphyseal plate at the upper end of the tibia stops growing while the rest grows normally, an angular deformity occurs, with inversion of the knee. If the central epiphyseal plate stops growing and a fracture is formed, but the area is not large enough to cause a break in the central bone bridge due to the growth of the surrounding portion without deformity. The treatment of premature epiphyseal closure should be based on the patient’s age, knowledge of his potential growth capacity, familiarity with the site, nature and extent of the deformity, and the choice of different methods.
2, treatment (1) osteotomy: simple angular deformity, commonly used wedge-shaped osteotomy to give correction. If the skeleton is not mature, the deformity can reoccur after the operation, requiring multiple osteotomies to correct.
(2) Contralateral limb shortening: the lower limb on the affected side is shortened and then the relatively long lower limb on the opposite side is also shortened to obtain limb length balance and improve the limping gait. One of the commonly used methods is epiphyseal fixation (Figure 10). An incision is made on both sides of the corresponding epiphysis, and subperiosteal stripping is done in the direction of the epiphysis, along with sharp separation of the cartilage membrane at the epiphyseal plate, and a rectangular bone flap is removed, with 2/3 of the flap in the epiphysis and 1/3 in the epiphysis, 1 cm deep and 1 cm wide; the exposed epiphyseal plate cartilage is scraped away with a scraping spoon to remove as much as possible; then the rectangular bone flap is rotated 180° and embedded in the defect area, and the periosteum is sutured to the original location. The growth capacity of the normal lateral epiphysis must be accurately estimated before surgery so that equal length of the two lower limbs can be achieved. This method causes artificial shortening of the length and is often unacceptable to the parents of the child. The epiphyseal temporary block method seems to be theoretically reasonable, i.e., the epiphyseal plate is fixed with suture nails around the epiphysis to delay the growth of the epiphysis, and then the suture nails are removed after the limb has shortened to a certain extent, hoping that the epiphysis can still grow. However, clinical practice and animal experimental results show that the epiphyseal plate has lost its ability to proliferate after surgery. It is also possible to shorten the epiphysis, i.e., to remove the overgrown portion of the femoral or tibial stem and then make an internal fixation. This procedure should be performed after the epiphysis has matured.
(3) Epiphyseal retraction and lengthening: This is a practical surgical method that can be used for shortening or shortening combined with angular deformity caused by complete cessation of epiphyseal plate growth, especially for tibial epiphysis lengthening. The epiphyseal bridge should be removed from the epiphyseal plate before the retraction is performed, and the epiphysis is gradually retracted using an external bone fixation device, resulting in epiphyseal separation, which can lengthen the limb by 4~6 cm or even longer. This method often causes adverse consequences such as Achilles tendon contracture and early closure of the normal epiphyseal plate after surgery, so the age of the child is limited to 14~16 years old, after puberty is appropriate. This method can also correct the angular deformity, with slow pulling on the convex side of angularity and slightly faster pulling on the concave side to give compensation.
(4) Removal of fat filling of the bone bridge within the epiphyseal plate: Some of the epiphyseal plates are damaged and growth is impaired, and the angular deformity is getting heavier. If the partially closed bone bridge is removed, do the chondrocytes regenerate again and the deformity is corrected? A preliminary experiment was done with young rabbits at 4 weeks of age, in which 2/3 of the distal femoral epiphyseal plate was removed from the left and right sides, and the excised space was filled with free fat on one side and injected with a clot on the other side. The fat-filled side showed epiphyseal growth at 1 week postoperatively, and the regeneration of the epiphyseal plate was complete by 4 weeks postoperatively. On the opposite side, the clot was injected and a large bone bridge was formed, resulting in complete growth arrest. This indicates that free fat prevents bone bridge formation and that the remaining epiphyseal plate chondrocytes have the ability to regenerate. In addition to taking plain X-rays, it is best to use CT or MRI to determine the exact site and extent of the bone bridge before the epiphyseal plate resection and fat-filling surgery, and X-rays can also be taken for tomography. The operation is performed under an operating microscope or magnifying glass, and the surgical light needs to be directed into the bone cavity to achieve a good field of vision. The marginal bone bridge is easier to remove (Figure 11). After determining the site of the bone bridge, the local bone mass is then removed, which includes the peripheral bone, membranous epiphysis, epiphysis and bone bridge, at which time the epiphyseal plate cartilage can be seen and then some bone is subconsciously scraped from the upper and lower sides of the epiphyseal plate and the cave is filled with free fat. If the bridge is surrounded by a normal epiphyseal plate, the surgical operation is more difficult (Figure 12). The epiphysis is first windowed in the nearby epiphysis, taking care that the Ranvier area remains intact, and the epiphysis is caved in to show the epiphyseal plate and bone bridge on one side of the epiphysis, with insertion of an injection needle if necessary, and intraoperative radiographs are taken to locate it. To excise the bone bridge, it is best to use a dental drill to grind with little damage and constantly flush with saline so as not to damage the normal bone and cartilage by heat production from abrasion, and to subconsciously excise the epiphyseal plate on the upper and lower side to ensure complete excision of the bone bridge. Free fat is adequately filled. This procedure can be used not only for traumatic causes but also for premature closure of the epiphysis due to septic osteomyelitis. There are indications even if the bridge is quite large, especially in infants and children. However, this method is not applicable to the upper end of the femur, mainly because of the aseptic necrosis caused by surgical disruption of the blood supply to the femoral head. Some operators do not use fat and use silicone rubber filling instead, because some of the fat becomes necrotic and can lead to surgical failure.
(5) Other: limb lengthening can also be done by tibial lengthening, femoral lengthening, and after the epiphyseal plate closes, the tibial epiphysis is truncated and drawn and lengthened. For severe joint deformity, unicondylar resection and allograft bone grafting can be used.
Overview of treatment
1. Treatment principles
Type I and II injuries are mainly closed repositioning, only individual unstable fractures or those with failed repositioning due to soft tissue embedded in the broken end need surgical treatment. Children have strong bone shaping ability, so it is not necessary to force anatomical repositioning, and most of them can be corrected spontaneously with growth and development. Type III and IV injuries are intra-articular fractures, which require restoration of joint surface flatness and epiphyseal plate alignment and often require surgical treatment. Type III injuries with a milder original displacement can be treated by trial repositioning, and the fracture is stable without surgery. Type V injuries are difficult to diagnose early, and the suspected cases should be braked locally for 3~4 weeks, and the affected limb should be free from weight-bearing for 1~2 months.
(1) Reset method Closed reset should be performed under general anesthesia, so that the muscles are completely relaxed and the overlapping bone ends can be fully retracted. The resetting technique should be gentle, avoiding violent extrusion of the epiphyseal plate to avoid medical trauma to the epiphyseal plate, and “folding the top” method should be used to reset the overlapping displacement of the broken end that is difficult to overcome completely.
(2) Timing of repositioning The sooner the fracture is repaired, the better; delay will increase the difficulty of repositioning. Forced repositioning is not advisable if the injury is more than 7-10 days old, especially for type I and II injuries, which are more preferable to be osteotomized and orthopedic later. For old fractures more than two weeks old, there is a risk of damage to the epiphyseal plate even with incisional repositioning, so type I and II injuries should be surgically orthopedic as far as possible, while type III and IV injuries should be incisionally repositioned as far as possible.
(3) Fixation method Do not peel off the periphyseal membrane of the epiphyseal plate to avoid damage to the chondrocytes and blood flow in the Ranvier area, and do not use instruments to pry and press the epiphyseal plate. Internal fixation is performed with a kerfing needle, which is inserted as vertically as possible, without crossing the epiphyseal plate laterally (Figure 9). Screws should only be used to fix the epiphysis or the larger secondary ossification center and should not cross the epiphyseal plate, otherwise the local cavity may form a bone bridge after removal of the nail and curb local bone growth. The internal fixation should be removed promptly after bone healing.
Timing of removal of fixation The healing speed of epiphyseal plate fracture is similar to that of epiphysis, about 3~4 weeks, which is only about half of the healing time of the same bone stem.
5. Follow-up The treating physician should warn the child’s family that this injury may lead to skeletal growth disorder, and the final result can only be concluded after 1~2 years.
2. Precautions (1) Type I and II injuries Early closed manipulative repositioning, gentle repositioning, and abstain from roughness to avoid increasing epiphyseal injury. It is not necessary to force anatomical repositioning, and the residual deformity can be corrected later through reconstruction. For example, in the case of angular deformity, the normal physiological stress stimulates the epiphyseal plate, which responds differently in different epiphyseal plate areas. In order to make the stress pass vertically through the articular surface, the epiphyseal plate grows eccentrically and selectively, and the concave side of angularity grows faster than the convex side, so that the angular deformity is gradually corrected. The maximum acceptable angle formation is 30°, but rotation cannot be corrected.
(2) Type III and IV injuries Treatment is mainly by incision and internal fixation. Sometimes type III is well aligned and more stable, and can also be treated non-operatively. When open repositioning, the blood supply to the epiphysis must be protected, and extensive periosteal and soft tissue stripping should not be done to reveal clearly. This may damage the activity of the cells surrounding the Ranvier area, which may lead to early epiphyseal plate closure. Blunt instruments should not be used to compress the epiphysis to reset it to avoid aggravating the injury.
(3) The epiphysis is repaired more quickly after injury. Type I-IV healing time is about half of the healing time of that epiphyseal fracture, so the later the epiphyseal injury is repositioned the more difficult it is. More than 10 d after the injury, it is almost impossible to reposition type I and II injuries by manipulation, violent repositioning or incisional repositioning, which may damage the epiphyseal plate. Therefore, for type I and II injuries more than 10 d after injury, do not try to reposition the epiphysis by manipulation, but let the deformity heal and correct it by osteotomy later. Type Ⅲ and Ⅳ injuries are different, displaced old injury is bound to cause growth disorders, in order to achieve anatomical repositioning and joint surface flattening, delayed open repositioning should also be implemented.
(4) Children with epiphyseal injuries should be followed up regularly until the epiphysis matures. Sometimes the growth of the epiphyseal plate does not stop completely immediately after trauma, but grows slowly for 6 months after the injury and then stops, and even the growth disorder does not show up until adolescence. Close observation should be made within 2 years after the injury, and X-ray films should be taken once in 1-2 years afterwards.
(5) Prognosis ① type of injury ② age of the child at the time of injury: once the epiphyseal growth disorder occurs with improper treatment or serious injury, the younger the age, the more serious the future deformity. ③ blood supply to the epiphysis, the worse the blood circulation the worse the prognosis, especially the femoral head and radial tuberosity ④ treatment methods, rough manipulation or prying and wrenching of displaced epiphysis with instruments may cause growth disorders. ⑤ Infection after open epiphyseal plate injury is bound to lead to premature closure of the epiphyseal plate destruction. (6) Stretching epiphysis injury. The ligaments and tendons attached to such epiphyses are separated by sprains or sudden muscle contractions causing avulsion of the epiphysis, such as avulsion of the medial epicondyle of the humerus and avulsion of the epiphysis of the lesser trochanter of the femur, and these injuries do not cause growth disturbances.