An 18-year-old female came to clinic after twisting her knee during her varsity soccer practice 3 days previously. She had planted her foot and then turned her body causing pain in the lateral and anterior area of the left knee. She had stopped practice and iced the area. She did not hear a popping sounds, nor felt the joint catch. She had pain with walking but was improving. She had a soccer tournament the following weekend and wanted to return to play. The past medical history showed previous muscle strains, and a right sided ankle sprain. She had been playing high-intensity soccer for many years.
The pertinent physical exam revealed a medium-build female with a mild gait abnormality when walking. She had mild tenderness near the lateral joint line but her collateral and cruciate ligament tests were normal. She had mild pain during the maneuvers but nothing significant.
The diagnosis of a left lateral ligamentous injury was made but because of the high level of participation a radiograph was taken. The radiologic evaluation of the knee showed no bony abnormalities other than a tiny right notch osteophyte. The patient had not had any problems with her knee previous so it was felt this was an incidental finding. She was counseled about working with her athletic trainer and returning to play when pain free.
The terminology of abnormal calcification of soft tissues and uses of the terms is often muddied. Especially as the causes may be similar and multiple adjacent tissues may be involved.
- An exostosis is an abnormal proliferation of bone from the joint. They can appear in various forms and in many locations.
- An osteophyte is also known as a bone spur and is type of exostosis. Osteophytes are thought to be periosteal or synovial mesenchymal stems cells that become calcified. They usually have a more narrow or pointed projection from the joint. Osteophytes are a very common feature of osteoarthritis.
- Enthesophytes are abnormal bony projections at the attachment of a tendon or ligament. These are often due to trauma and examples commonly occur at the knee or heel, such as Osgood Schlater disease.
Exostosis variants include:
- Osteochrondroma – usually a solitary, non-tender, slow-growing mass in long bones (more commonly lower extremity). Radiographically they can be sessile or stalked in appearance.
This is the most common skeletal tumor (10-15%). They occur especially during the bony growth period. Complications occur in about 4% of patients and include fractures, bony deformation, and compression causing neurovascular problems.
- Hereditary multiple exostosis – an autosomal dominant disorder with multiple masses in all parts of the body except the head. They are very common in the lower extremity particularly the knee. Short stature may also be seen.
- Trevor’s disease – usually affects the tarsal bones or epiphyses of long bones. More common in lower extremities and usually unilateral.
- Nora’s lesion – also known as bizarre parosteal osteochondromatous proliferation seen in the hands and feet. Generally seen in adults.
- Subungual exostosis – these occur in both the hands and feet with feet more commonly affected particularly the great toe. These are felt to be traumatically related and the bony projection comes from the nail bed. These are usually seen in teens and adults.
Normal variations or congenital anomalies can be mistaken for exostoses such as the supracondylar process of the humerus, os intermetarsale or even the bony projection within the central spinal canal that tethers and splits the spinal cord in half in diastematomyelia. Periosteal reactions can also appear similar to exostoses and include entities such as osteomyelitis, osteoid osteoma, or osteosarcoma. Myositis ossificans from trauma can cause calcification of the muscle but if deep can also show abnormal ossification of the periosteum.
Risk factors for osteophytes include age (older), body mass index (heavier), physical activity (heavy physical activity), diet (low amounts of various nutrients) and genetic factors.
Osteophytes or bone spurs are usually thought of in older people who have osteoarthritis. However they can occur in young people. A cross-sectional, case-controlled study of young adults (<18-36 years) found that being an athlete had a higher risk of radiographic evidence of osteophytes in the knee (odds-adjusted ratio = 2.8) and if a patient had anterior cruciate ligament surgery (odds adjusted ratio = 7.0). While this study isn’t representative of the general population, it does show that young athletes are at risk for development of osteophytes even at a young age. While this study didn’t find a difference in males and females overall for osteophytes, young female athletes are at higher risk for knee injuries particularly in sports with “cutting” type activities such as basketball or soccer.
Questions for Further Discussion
1. What are common benign bone tumors? A review can be found here
2. What is the long-term outcome of ACL repair? A review can be found here
3. What are the positive aspects of organized sports activities?
- Symptom/Presentation: Lower Extremity Trauma
- Specialty: Orthopaedic Surgery and Sports Medicine |
Radiology / Nuclear Medicine / Radiation Oncology
- Age: Teenager
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
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Richardson RR. Variants of exostosis of the bone in children. Semin Roentgenol. 2005;40(4):380-390. doi:10.1053/j.ro.2005.01.020
DaCambra MP, Gupta SK, Ferri-de-Barros F. Subungual exostosis of the toes: a systematic review. Clin Orthop Relat Res. 2014;472(4):1251-1259. doi:10.1007/s11999-013-3345-4
Roemer FW, Jarraya M, Niu J, Silva J-R, Frobell R, Guermazi A. Increased risk for radiographic osteoarthritis features in young active athletes: a cross-sectional matched case-control study. Osteoarthr Cartil. 2015;23(2):239-243. doi:10.1016/j.joca.2014.11.011
Nasr B, Albert B, David CH, Marques da Fonseca P, Badra A, Gouny P. Exostoses and vascular complications in the lower limbs: two case reports and review of the literature. Ann Vasc Surg. 2015;29(6):1315.e7-1315.e14. doi:10.1016/j.avsg.2015.02.020
Wong SHJ, Chiu KY, Yan CH. Review Article: Osteophytes. J Orthop Surg (Hong Kong). 2016;24(3):403-410. doi:10.1177/1602400327
Perez-Palma L, Manzanares-Cespedes MC, de Veciana EG. Subungual Exostosis Systematic Review and Meta-Analysis. J Am Podiatr Med Assoc. 2018;108(4):320-333. doi:10.7547/17-102
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa