When an X-ray taken after an injury or because of pain reveals a “bone lesion”, parents often focus first on the name. A practical question soon follows: can the child still play sport?
The answer depends on more than whether the lesion is benign. Two benign lesions can have very different mechanical effects. One may be an incidental finding that does not substantially affect bone strength; another may thin the outer layer of bone and increase fracture risk.
For this reason, I would not automatically ban sport or offer reassurance based only on the word “benign”. First, we need to understand what the lesion is, where it is and how much it changes the bone.
Benign does not automatically mean fragile or insignificant
Common findings in children include non-ossifying fibromas, unicameral bone cysts and osteochondromas, also called exostoses. Less common lesions include aneurysmal bone cysts, fibrous dysplasia, enchondromas and chondroblastomas.
A review published in 2025 specifically examined return to sport with benign bone lesions. It found no single rule: non-ossifying fibromas and osteochondromas are generally associated with a lower fracture risk, whereas unicameral bone cysts, aneurysmal bone cysts and some forms of fibrous dysplasia warrant more caution and specialist assessment before higher-risk sports. [1]
The diagnosis alone does not provide a simple green or red light. Size, location and X-ray characteristics matter within each diagnosis.
Non-ossifying fibromas: a common example
A non-ossifying fibroma is often found incidentally near the knee on an X-ray taken for another reason. Most are self-limiting and do not need surgery.
For sport, an important consideration is how much healthy bone remains around the lesion. A small lesion towards the edge of the bone, with a well-preserved outer layer, is different from a large lesion occupying much of the bone's diameter and thinning that layer.
Size contributes to risk assessment, but I would not use a single percentage as an automatic threshold for banning football, basketball or skiing. Assessment should combine the X-ray findings, location, pain, any previous fracture and the activity involved. The return-to-sport review places non-ossifying fibromas among generally low-risk lesions once the diagnosis and characteristics have been established. [1,2]
Bone cysts require a different assessment
A unicameral bone cyst can weaken the bone more substantially. It may first be discovered when a fracture occurs through it, particularly in the upper humerus or femur.
Assessment goes beyond the size of the cyst. Its location, proximity to the growth plate, thickness of the outer bone layer, any fracture and changes over time also matter. Treatment is not standardised: observation, minimally invasive procedures and surgery have different indications depending on risk and the individual child. [3]
A bone cyst does not necessarily mean months without activity. Before authorising a sport involving collisions, jumping or a substantial fall risk, however, it is reasonable to assess the bone's structural strength.
What about an osteochondroma?
A solitary osteochondroma often does not reduce bone strength in the same way as a large cystic lesion. It can nevertheless cause other problems: local irritation or impingement, pain around tendons or bursae, restricted movement, or vulnerability to a direct blow.
Again, the diagnosis alone is not enough. An asymptomatic osteochondroma away from important structures may be compatible with normal sporting activity. A painful lesion where protective equipment, ski boots or other equipment presses against it needs a different assessment.
The sport itself changes the decision
“Sport” is not a single activity. Swimming, running, gymnastics, football, rugby, skiing and mountain biking place different stresses on bone and involve different injury risks.
When assessing return to sport, I therefore consider at least five factors:
- a sufficiently certain diagnosis;
- the lesion's location and structural characteristics;
- pain or a previous fracture;
- the type and intensity of sport;
- the likely consequences of a fall or direct impact on that bone.
A restriction can therefore be temporary or apply only to certain activities, rather than becoming a general ban on movement.
If the lesion was found by chance
An incidental finding can seem contradictory: the child was playing sport comfortably yesterday, yet suddenly appears fragile after an X-ray.
The X-ray did not create the risk. It provided information that needs interpretation. If the appearance is typical of a low-risk benign lesion and the bone remains structurally sound, the finding should not automatically lead to stopping activity. If the lesion is large, atypical, painful or at a high-risk site, however, previous participation in sport does not make it safe to ignore.
After a fracture through the lesion
If the bone has fractured through the lesion, healing the fracture comes first. The remaining lesion and the risk of another fracture then need reassessment.
Return to sport therefore depends on more than the disappearance of pain. It must be compatible with bone healing, recovered function and the remaining mechanical risk.
Establish the diagnosis, then assess structural risk
The nature of the lesion must be clarified first: we need sufficient confidence about what we are looking at. Once it has been established as benign, the sporting question is whether it weakens the bone enough to justify changing the child's activities at that point.
In many cases, sport will not need to stop. In others, location, thinning of the outer bone layer, pain or a previous fracture may make a temporary restriction or treatment appropriate. The decision follows from those findings, rather than the label “benign” alone.
References
[1] Kafchinski LA, Crawford AE, Stolzenberg L, Gould SJ. Common Benign Bone Lesions and Return to Sports: A Case Report and Scoping Review. The American journal of sports medicine. 2025. PubMed: 39741486 · DOI.
[2] Walker K, Smith JB, Todi N, Brown D, Randall RL. Non-Ossifying Fibromas: A 2025 Review. Journal of clinical medicine. 2025. PubMed: 41010632 · DOI.
[3] Ge J, Tian K. Management strategies and outcomes of pediatric unicameral bone cyst: a narrative review. Frontiers in pediatrics. 2026. PubMed: 42063443 · DOI.
Disclaimer: this article provides general information. It does not replace individual medical assessment or constitute medical clearance for sport or return to play.
Related information
Read more about non-ossifying fibroma, juvenile bone cyst and solitary osteochondroma.
