Lumbar Facet Fracture in an Adolescent Ice Hockey Player

William O. Shaffer, MD; Michael R. Taylor, PAC, ATC; Murali Sundaram, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 27 - NO. 12 - NOVEMBER 1999

In Brief: A 14-year-old boy was checked hard as he was winding up to shoot in an ice hockey game. He experienced low-back pain during the game but when examined later for complaints of pain and fever, he denied trauma. Plain x-rays were normal, but a bone scan showed increased uptake at L-3. MRI evaluation revealed a lumbar mass; a CT scan showed the mass to be a hematoma and edema secondary to a facet fracture. Acute severe back pain in a hockey player should prompt a careful history and a search for musculoskeletal injury. When trauma in the lumbar spine is suspected and plain radiographs are nondiagnostic, CT scans are more precise than MRI for diagnosing injury.

The popularity of ice hockey continues to grow. From June 1997 to June 1998, the latest season for which data are available, 394,006 players and 30,105 teams nationwide competed in hockey (1). To date, the primary focus of injury recognition, prevention, and treatment in hockey has been on the head and cervical spine (2-9), and particularly on catastrophic cervical-spine injuries (3-9). Injuries to the lumbar spine have not received as much attention.

Bone injury in the lumbar spine is infrequently reported; most complaints of low-back pain in ice hockey players reflect muscle problems (10-12). Complaints of low-back pain are often minimized—if not dismissed—when patients have other signs and symptoms.

Because hockey can be an aggressive, fast-paced sport involving frequent collisions (see "Hitting in Amateur Ice Hockey: Is It Worth the Risk?" page 35), bone or significant soft-tissue injury should be suspected if acute back pain occurs after a violent check or collision (13-15). This case report of lumbar spine facet fracture in an ice hockey player illustrates the need for obtaining an accurate history and using the correct tests to aid diagnosis and treatment.

Case History

A 14-year-old male ice hockey player presented for evaluation of a suspected lumbar "mass" revealed by magnetic resonance imaging (MRI). After careful questioning, the patient related that the back pain had begun after a high school hockey tournament 3 weeks earlier, in which he had been "checked hard" on several occasions. He remembered one severe hit as he wound up to take a shot on goal, and later felt back pain that worsened with trunk rotation.

The patient had originally complained of dull, nonradiating low-back pain and intermittent fevers, which had persisted for 2 weeks after the tournament. When he was initially examined by his pediatrician, 2 weeks after the injury, he denied trauma. The pediatrician diagnosed his low-grade fever as a viral syndrome. Symptomatic treatment provided no relief, and the fever and dull back pain persisted. A complete blood count was normal, and a sedimentation rate was elevated. A radioisotope bone scan was performed because of the possibility of diskitis. The bone scan showed increased uptake in the left L-3 posterior element, but a plain radiographic series of the lumbar spine was reported as normal.

The pediatrician referred the patient to an orthopedic surgeon, who ordered an MRI because of the back pain, fever, and abnormal bone scan in the apparent absence of trauma. The MRI revealed a soft-tissue mass adjacent to the lumbar spine (figure 1). The patient was referred to our center because such findings are often indicative of a soft-tissue sarcoma.

Physical examination. When examined by two of us (W.O.S. and M.R.T.), the patient was found to be a well-nourished 14-year-old with normal gait and posture. He exhibited a mild decrease in both active and passive forward flexion and extension of his lumbar spine and had mild point tenderness over L3-4. The patient's muscle strength and reflexes were normal, and he did not show tension signs; ie, straight-leg raising was negative for neural tension.

Imaging studies. The MRI revealed a heterogeneous mass with edema along the erector spinal muscle planes on the left side adjacent to the L-3 facet (see figure 1). A computed tomography (CT) scan of the patient's lumbar spine (figure 2) showed the mass to be a hematoma and edema secondary to facet fracture rather than a sarcoma.

Treatment. The patient was fitted with a brace and told not to play hockey for 3 months. After 6 weeks, he was told that he could wear the brace part time. Healing was uneventful, and the boy's back pain resolved in the next 6 weeks. A follow-up CT scan at 6 months revealed complete healing of the facet fracture (figure 3).

Discussion

Acute, severe back pain in a hockey player should lead to a search for a bone, articular surface, ligament, or muscle injury. This young man had not volunteered information about his hockey injury because he feared not being allowed to play. The relevant history was obtained only after we discovered that the patient was an avid hockey player and that his father was the team coach.

Appropriate imaging. When trauma is suspected and plain radiographs are nondiagnostic, the proper imaging modality should be used. CT and MRI in combination are not usually necessary to solve a clinical problem; however, exceptional circumstances require that both modalities be used to view anatomically complex areas or to resolve discordance between the radiographic findings and clinical presentation. CT is the preferred method of characterizing an internal flat-bone lesion that is poorly seen or hidden in a radiograph (16-18); it is more precise than MRI in identifying a traumatic bone injury. In this patient, findings on the technetium bone scan suggested an abnormality in the facet joint. Had a CT scan been obtained to assess the abnormality, the facet fracture would have been recognized and appropriate management undertaken without using MRI.

It is possible that the orthopedic surgeon who first saw this patient was concerned by the size of the soft-tissue mass and thus ordered the MRI, the correct modality for examining potential tumors. The depth, size, and heterogeneity of the presumed mass were worrisome because they suggested a sarcoma. However, its location and the suggestion of subacute hemorrhage on the T1-weighted images raised the possibility that the mass was a hematoma known as pseudomalignancy of soft tissues. Increased signals on a T1-weighted pulsing sequence in a soft-tissue mass, whether homogeneous or heterogeneous, have a limited differential diagnosis that includes hematoma and hemorrhage within a sarcoma. Recognition of the strengths and limitations of CT and MRI, together with heightened suspicion about possible trauma, led to the correct diagnosis.

Key lessons. Main lessons in this case were:

• The physician should obtain a sport-specific medical history from any young athlete who has acute back symptoms. An appropriate history will facilitate proper diagnosis and treatment.
• The MRI appearance of a fracture can alarm and mislead the clinician. Edema seen on MRI can indicate benign illness, trauma, or a benign tumor; however, edema along muscle planes is consistent with trauma rather than a tumor.
• When an athlete's torso is in rotation, spinal facets are loaded, and application of additional external force (eg, checking) can cause a facet to fracture. Rotational injuries to the trunk associated with cross-checking can result in bone injury and injury to ligaments or muscles.

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Dr Shaffer is an associate professor in the department of orthopedic surgery, Mr Taylor is a certified physician assistant and a certified athletic trainer, and Dr Sundaram is a professor in the department of radiology, all at the Saint Louis University School of Medicine in St Louis. Dr Shaffer is also director of the university spine service, a fellow of the American Academy of Orthopaedic Surgery and North American Spine Society, and a member of the International Society for the Study of the Lumbar Spine. Mr Taylor is a fellow of the American Academy of Physician Assistants, and Dr Sundaram is a fellow of the Royal College of Radiology and the American College of Radiology. Address correspondence to William O. Shaffer, MD, Saint Louis University School of Medicine, Dept of Orthopedic Surgery, 3635 Vista Ave at Grand Blvd, St Louis, MO 63110-0250; e-mail to shafferw@slu.edu.