Update from post 30/10/2021
There is no doubt that the pathology associated with knee pain around the patella tendon is different in children and adults. However, recent research suggests that it is not perhaps as different as we first thought. In adolescents, tendons attach to bones at the apophyses. These are non-articular, cartilaginous prominences for the attachment of tendons or ligaments, which appear after birth (timing dependent upon which bone site), and do not contribute to bone length. The softer cartilage is gradually replaced by bone at different stages of a child’s development and knowledge of that process and the timing of ossification is key to accurate diagnosis in the child.
Prior to ossification, the cartilaginous attachment is not as robust and is therefore susceptible to injury through traction-type forces generated by repetitive jumping and running. In the knee, for example, pain at the insertion of the patella tendon to the tibia was therefore described as a traction or overuse apophysitis (Osgood Schlatter’s Disease) thought to be associated with bony pathology and not tendinopathy. In contrast, after ossification, the bone becomes more robust, and it is the tendon that becomes relatively “weak” by comparison and more susceptible to injury.
This, therefore, has led to the idea that children, before maturation got pain due to partial bony avulsion at the apophysitis, and adults got tendinopathy. However, emerging research over recent years has highlighted that many of the changes in imaging that were thought to be pathological, such as fragmentation of the tibial tuberosity (Ducher, 2010) seen on x-ray, are in fact potentially just a process of normal bone development.
In an excellent systematic review by Sørensen et al., (2021), the authors highlighted that the findings on imaging vary with different imaging modalities. X-rays are more likely to report fragmentation, versus ultrasound studies have shown patellar tendon thickening and increased Doppler flow in both the patella tendon, infrapatellar bursa, and the attachment to the tibia. MRI findings reflected findings more indicative of tendinitis.
Ossicles are observed in the imaging reports of patients with symptomatic OSD, but not in asymptomatic controls. Once thought to be a self-limiting condition, evidence supports restricted activity and symptoms for a median of 4 years (Guldhammer, 2019) in these population groups. The presence of ossicles, the presence of Doppler signal, and those with associated bursitis on ultrasound may help predict which children will go on to develop symptoms of longer duration.
So, I am eating my words…..children do get tendinopathy and bursitis associated with apophysitis.
Management of children with conditions like Osgood Schlatter’s Disease is well documented. The principles of activity modification to allow symptoms to settle, followed by a graduated return to sport is no different for an adult with tendinopathy. Strength deficits should be addressed starting often with isometrics. Education is key if the patient is not to return to sport and recreate the same training errors.
This should include information about the condition and the risks of spikes in workloads, inadequate recovery, single-sport specialisation, low Vit D, poor nutritional intake, and lack of sleep. Being realistic about time frames for recovery with children and their parents is essential to good outcomes.
If you would like to learn more about growth-related injuries or return to sport and play in the active child, then visit https://angelajacksonphysio.thinkific.com/courses/Activekids
