Lumbar Spine Stress Fracture in a Young Athlete

Conor P. O'Brien, MB, MSc, PhD; Charles Williams, MB; George Duffy, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 25 - NO. 8 - AUGUST 97

In Brief: An 18-year-old rugby player suffered pain at the left lumbosacral junction after intensifying his level of practice. Plain radiographs were negative, but single-photon-emission computed tomography and three-dimensional bone scan images showed a lesion on the left neural arch of L-5. After conservative treatment and 10 pain-free weeks, he resumed training. One week later, symptoms recurred, and standard computed tomography showed a vertical fracture through the S-1 facet. This rare fracture illustrates the need to consider the unusual injury, especially in younger athletes who participate in high-level sports.

Stress fractures are common injuries among athletes, especially when participants increase their training frequency, duration, or intensity or abruptly change the nature of their activity. College freshman athletes are a good example; as they engage in more intense levels of training and competition than they are accustomed to, they have a higher incidence of these injuries than older college athletes (1). Physicians need to be alert to the possibility of stress fractures in such athletes. The following case report is an unusual example of such an injury.

Case History

Scrummaging Defined In rugby, two 15-player teams attempt to carry or kick an inflated oval ball over the opponent's goal line for a score. During two 40-minute halves, players may tackle the opponent, pass laterally, and kick and run with the ball, but forward passing and blocking are not permitted. Minor infractions lead to a scrummage, or scrum, in which the eight forwards from each team form a tight formation and the ball is tossed among them. They then push and shove against each other until a player can heel the ball out of the scrum to a back who starts the team's offense. To practice scrummaging, eight players push against an electrically driven machine set to provide about 1,000 kilopascals (kPa) (about 150 psi) of resistance. After the players push the machine a fixed distance, the setting is increased, and the players try to hold their position against the machine. In this "hold" phase, the players resist forces of up to 4,000 kPa (about 600 psi).

An 18-year-old, second-row rugby player joined an amateur rugby club at the beginning of the season in September. A promising, 6-ft 4-in, 200-lb athlete, he was promoted to the senior team within a few weeks. His new team trained three evenings a week, and each session involved about 20 practice scrums against a mechanical scrummaging machine (see "Scrummaging Defined"). Over a period of time, he noted pain in his low back associated with scrummaging.

Physical exam and imaging studies. Following one practice, the pain became sufficiently acute that he presented at a sports medicine clinic with nonspecific low-back pain localized to the lower lumbar region. Clinical examination revealed limitation in spine flexion and extension. Palpation of his lumbar spine revealed pain near the left lumbosacral junction. Plain radiographs of his lumbar spine were obtained; they showed no sign of a recent fracture or degenerative change. There was no evidence of a pars interarticularis defect.

Using technetium-99m methylene diphosphonate, single-photon-emission computed tomography (SPECT), and bone scan images (figure 1) of the pelvis and lumbar region were obtained. The study showed evidence of a hot focal lesion on the left neural or posterior arch of L-5. The differential diagnosis was a facet joint injury and pars interarticularis defect.

Treatment, recovery, relapse. The patient was treated conservatively for 3 weeks with rest, nonsteroidal anti-inflammatories, and local physiotherapy modalities four times each week.

After being pain free for 10 weeks, he resumed rugby training and, within one week, had renewed low-back pain in the left lumbosacral region. When he presented for treatment, repeat SPECT bone scans confirmed the persistence of the previously identified hot lesion. A computed tomography (CT) scan (figure 2) of the area was subsequently performed and demonstrated a vertical fracture through the S-1 facet, extending to the articular surface with displacement and loss of congruity.

The patient stopped playing rugby. After 14 weeks he was again pain free and began an isokinetic back rehabilitation program.

Young Athletes in High-Level Sports

This case highlights a growing problem as more young individuals engage in high-level, competitive sports. The injury in this case may represent a fatigue or stress fracture caused by repetitive loading at the L-5 and S-1 posterior arch. High-intensity rugby scrummaging over a period of weeks stressed a skeletally immature spine and provoked the fracture.

Rugby players are at particular risk of low-back injuries, which appear to account for 5% to 10% of all rugby-related injuries (2). Low-back injuries in the sport are not surprising considering the punishment of the scrum. The force generated by scrummaging rugby players is between 1,000 and 3,500 kilopascals (kPa) (about 150 to 575 psi) on impact, but can increase to 4,000 kPa (about 600 psi) during each scrum.

Fatigue fractures such as this one usually follow a common pattern: overuse, followed by inadequate rest and a premature return to activity, resulting in a full-blown fracture of the subchondral bone. The metatarsals, navicular, tibia, and fibula are the most common sites of sports-related stress fractures. Pars interarticularis stress fractures are the next most common (3). Lumbar stress fracture through a facet is a rare injury; to our knowledge, in fact, it has not been previously described.

Look for the unusual. The rarity of this fracture underscores the necessity of considering the unusual when a younger athlete is injured while participating in high-level sports. The fact that our patient's fracture was not revealed by plain and oblique radiographs confirms the need for a thorough evaluation of young athletes. If symptoms persist, it is always worth considering special imaging studies.

The unusual should also be considered among older players. The pattern of injuries among rugby players is changing because Rugby Union, one of the oldest amateur field sports in the world, became a professional or open sport in August 1995. Professional sports have a higher incidence of injury than lower-level sports (4) because increased training and play subject the athletes to more of the stresses that can fatigue bones. Physicians need to consider rare overuse pathologies in injured athletes in professional and high-level amateur sports, particularly if the site of the injury is atypical.

References

1. Goldberg B, Pecora C: Stress fractures: a risk of increased training in freshmen. Phys Sportsmed 1994;22(3):68-78
2. O'Brien CP: Retrospective survey of rugby injuries in Leinster province of Ireland 1987-1989. Br J Sports Med 1992;26(4):243-244
3. Brukner P, Bradshaw C, Khan KM, et al: Stress fractures: a review of 180 cases. Clin J Sports Med 1996;6(2):85-89
4. Gerrard DF, Waller AE, Bird YN: The New Zealand Rugby Injury and Performance Project: II. Previous injury experience of rugby-playing cohort. Br J Sports Med 1994;28(4):229-233

Dr O'Brien practices at the Blackrock Clinic and is in the Department of Neurophysiology at Beaumont Hospital, both in Dublin, Ireland; he is also a team physician with the Irish Olympic team and a fellow of the American College of Sports Medicine. Dr Williams is a consultant in the Department of Radiology in the Blackrock Clinic and is a fellow of the faculty of radiology at the Royal College of Surgeons Ireland. Dr Duffy is a consultant in general and nuclear medicine at the Blackrock Clinic and is a fellow of the Royal College of Physicians Ireland. Address correspondence to Conor P. O'Brien, MB, MSc, PhD, Suite 26, Blackrock Clinic, Dublin, Ireland.

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