Pediatric sports injuries differ from adult injuries due to the development characteristics of growing bone. The growing bone leads to potential injuries at each growing component. There has been confusion in the literature due to the number of terms, lack of familiarity with anatomy and pathology with pediatric injuries. This has led to crossover use of terms such as osteochondrosis (osteochondroses) with apophysitis (apophyseal injuries) as well as osteochondritis dissecans and avascular necrosis conditions. The aim of this article is to clarify these definitions using anatomy and flow charts and a review of the literature.
The anatomy terminology of pediatric bone can be seen in the pediatric elbow of a 12 year old patient in figure 1.
Figure 1 – Pediatric bone terminology
One of the common areas of discrepancy is the use of the terms apophysis and epiphysis. The apophysis is a non-articular terminal ending of bone that is connected via physis to the remainder of bone. These act as growth centres to react to increased load/demand of attaching musculotendinous structures. Whereas the epiphysis, is the terminal portion of pediatric bone that forms the articulation (joint). In a 2010 radiology article describing lower limb apophysitis there is an example of the misuse of epiphysis to describe the greater trochanter apophysis as an epiphysis (Figure 2 – Nomenclature confusion). The article otherwise does an excellent job displaying radiology findings of lower limb apophysitis injuries.
Figure 2 – Greater trochanter apophysis (arrow) incorrectly labelled as an epiphysis Arnaiz et al. 2011
The definition of osteochondrosis has been quite varied, however newer literature is looking to clarify and come to a consensus, with osteochondrosis referring to a process affecting the developing epiphysis leading to abnormal growth. The literature has often referred to apophysitis as a type of osteochondrosis, however this serves little purpose, as they appear to be part of a completely different process, different anatomical location and apophysitis are well-defined. Similar to epiphysis and apophysis – osteochondrosis should have articulating surface involvement as one of it’s prerequisites.
Table 1 – Osteochondrosis – definitions
|Osteochondrosis refers to idiopathic avascular necrosis of children
|Self-limiting developmental derangement of normal bone growth, primarily involving the centres of ossification in the epiphysis. Degenerative or necrotic condition. Aseptic ischemic necrosis.
|American Family Physician
|Refers to degenerative changes in the epiphyseal ossification centres of growing bones
|Noninflammatory, noninfectious derangements of bony growth at various ossification centres occurring during development
|Group of disorders that affect the progress of bone growth by bone necrosis
According to literature, osteochondrosis would include (as seen in Figure 3):
Figure 3 – Osteochondrosis flowchart based on literature use of term (Crossed out as not recommended)
However, the authors at sportmedschool.com propose, as does a recent articles such as Achar and Yamanaka (2019) to separate them into:
1)Osteochondrosis/Osteochondroses (see Figure 4)
2)Apophysitis and Apophysitis-like conditions (see Figure 7)
3)Physeal Injuries (see Figure 8)
Figure 4 – Osteochondrosis (recommended categorization)
Therefore, osteochondrosis would include diagnoses affecting articular pathology. Osteochondritis dissecans of the humeral head and the elbow, Panner’s disease and Kienbach’s disease would all be examples of osteochondroses in the upper limb. In the lower limb, osteochondroses include: Legg-Calve-Perthes, Kohler’s, Freiberg’s, as well as osteochondritis dissecans of the knee and talus. Of course, with all attempts to clarify terminology, there is potential room for debate. Both slipped capital femoral epiphysis and proximal humeral epiphysiolysis are technically physeal injuries, and although they can both progress to femoral head and humeral head collapse, the actual injury involves the physis.
Overuse in pediatric populations can lead to a number of injuries including osteochondroses, tendinopathy and stress fractures. However, the most common injuries in children and in early adolescence due to overuse are apophyseal injuries. The continual traction of the tendon on the apophysis leads to injury involving the physeal plate bridging the apophysis to the bone. MRI will show edema in this area, however xrays may show widening of the apophysis, fragmentation of the apophysis and/or avulsion of the apophyseal fragment (Figure 5 – Avulsion of Iliac crest apophysis).
Figure 5 – Avulsion of iliac crest apophysis – 16 yo male
As the apophyses have their own growth potential, they may respond to chronic traction stimulation by enlarging (figure 6), as seen in Osgoode Schlatter’s or tibia tuberosity apophysitis (the commonest of the apophyseal injuries).
Figure 6 – Tibial tuberosity bump seen on right knee (in background) in patient with Osgoode Schlatter’s
Similar in location to an enthesitis in adults, children will be tender over the tendon attachment site, that is the boney prominence of the apophysis as well as the underlying physis. Unlike epiphyses, these apophyses act as tendon attachments near the metaphysis of bones away from the articular surfaces.
Figure 7 – Apophysitis and Apophysitis-like conditions
Both slipped capital femoral epiphysis and proximal humeral epiphysiolysis represent injuries to the physis which can affect the articular surface, but secondary to the primary injury. Thus, the authors recommend categorizing these as physeal injuries as opposed to osteochondroses (see Figure 8). These physis injuries typically occur over time to repetitive compression or traction. A third type of physeal overuse injury can occur at the wrist at the radial physis. This is an injury called gymnast’s wrist, as it is often seen in gymnasts whose training involves a significant amount of weightbearing on the hands and upper limbs. Finally, there are acute injuries to the physis which can occur as a result of trauma. These are identified by the Salter-Harris classification.
Figure 8 – Physis Injuries
Metaphysis and Diaphysis Injuries:
The metaphysis is prone to compression in growing bones and thus, the commonly seen buckle/torus fractures of the wrist at the radial metaphysis (most common) and ulna. These fractures can occur in any bone including the femur, humerus, ribs, sternum, tibia and fibula. They are tender locally to palpation and can be identified on radiographs. The metaphysis is also the site of cortical desmoid or tug lesions injuries which can occur due to an acute traction force or from traction over time. These typically occur around the knee in the adolescent patient and involve the adductor magnus, gastrocnemius and/or soleus tendinous attachments pulling on the metaphysis of the femur or tibia (see figure 9 – metaphysis injuries).
Figure 9 – Injuries of the Metaphysis
Diaphyseal injuries include fractures, toddler’s fractures and greenstick fractures*. Fractures can occur with disruption in the cortex similar to those seen in adults however, there are two specific diaphyseal injuries that occur in children. The first is the toddler’s fracture which is a spiral fracture of the distal diaphysis of the tibia which can happen in young children 9 months to 3 years of age (Wang et al. 2022). These can occur from relatively innocuous mechanisms of injury such as tripping or catching a foot on furniture. The child may present non-weight bearing or limping. These are relatively stable, apparent on xray and recommendations are changing from full above-knee casting to removable splints as these are relatively stable fractures.
* Greenstick injuries may also occur at the metaphysis
The next clinical question to arise from terminology clarification is how to differentiate these diagnoses by examination. Pediatric bones should be palpated along their entire length with the joints above and below being examined for range of motion and tenderness. Osteochondroses affect the joint and therefore, the two common findings would be pain with passive range of motion and/or restriction in range of motion compared to the contralateral side. For elbows, knees, wrists and ankles osteochondroses may be associated with an effusion and warmth over the joint. Xrays are recommended to initially assess the joint. If negative and no improvement over several weeks, MRI should be obtained to further assess the involved joint. Apophyseal conditions on the other hand should have normal passive range of motion on the adjacent joint exam. They are point tender over the affected apophysis (See figure 10 – Lower limb apophysitis locations), and if acute or flared up may demonstrate weakness when the attached muscle is tested against resistance. These are typically diagnosed clinically and don’t require imaging although they can often be seen on xrays. If acute and there is concern for an avulsion, xray is recommended. Xray should otherwise be reserved for when there is concern for other diagnoses such as stress fracture. Also, it should be noted that heterotrophic changes of the apophysis can often be misidentified as tumours, including on MRI. This further highlights the importance of awareness of these injuries and how they might progress clinically and radiologically.
Figure 10 – Lower Limb Apophysitis
Physeal injuries can be difficult to assess on examination. However with clinical suspicion from the history, epiphysiolysis of the proximal humerus may be identified clinically by pain with palpation of the proximal humerus. There may be pain with range of motion of the shoulder as well. Xrays, especially bilateral humeral xrays may be helpful in making this diagnosis. An MRI will show edema in the proximity of the growth plate and potentially displacement. Slipped capital femoral epiphysis will often lead to referred pain to the distal quadriceps and occasionally knee. Therefore, the importance of screening joints above and below the area of pain localized by the patient is essential. Clinical examination may reveal loss of range of motion of the hip as well as pain with passive range of motion of the hip. Xrays including frog leg lateral views, may assist in the diagnosis. MRI has increased sensitivity and can identify the physeal injury as well as potential femoral head changes.
For an approach to pediatric MSK injuries and imaging, see figures 11 and 12, which differentiate based on whether the pain is localized vs. not well localized. Figure 12 also demonstrates the differentials that can be assessed with imaging in this population.
Figure 11 – Localized pain – Imaging consideration approach
Figure 12 – Non-localized pain – Imaging consideration approach
Finally there may be a role for POCUS in identifying injuries to the cortex such as torus/buckle, greenstick and torus fractures. If available, this presents a potential method for readily scanning the cortex of the affected bone to assess for cortical disruption. (Wang et al. 2022, Pountos et al. 2010) For early injury, where the fracture may not be obvious, ultrasound may be more sensitive than xray for small disruptions of the cortex. (Pountos et al., 2010)
The progression of terminology and its clarification is essential to appropriately categorizing pediatric sports injuries. As the pediatric skeleton is amenable to examination due to relative size compared to adults, these diagnoses are often identifiable through clinical examination. Pediatric bone-related injuries differ significantly from their adult counterparts due to the growing nature of their bones and flexibility of the tissue. Bone terminology is essential for both categorizing pediatric injuries but also for being aware of where to examine patients. Osteochondroses can be differentiated from their apophyseal counterparts based on articular involvement. The third category which has the potential for affecting articular involvement are physeal injuries. These can include chronic injuries, specifically slipped capital femoral epiphysis and proximal humeral epiphysiolysis, or acute/traumatic Salter-Harris fractures. The growing bone can also contribute to injuries of the diaphysis and metaphysis which are specific to children, namely greenstick, toddler’s and torus fractures. Future research on these injuries, their natural history and potential new treatments will benefit from more appropriate use of terminology.
Dr. Neil Dilworth, Dr. Kevin Asem, Dr. Wes Clayden, Dr. Alex Francella and Dr. Mark Leung(Jan 8, 2023 PR ML, AF, KA, WC)
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https://www.jasoncartermd.com/teaching/0015.htm – Figure 4 – Tibial tuberosity bump
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