Nonconsecutive Pars Interarticularis Defects
Lumbar spondylolysis is a well-recognized condition occurring in adolescents because of repetitive overuse in sports. Nonconsecutive spondylolysis involving the lumbar spine is rare. In contrast to single-level pars defects that respond well to conservative treatment, there is no consensus about the management of multiple-level pars fractures; a few reports indicated that conservative management is successful, and the majority acknowledged that surgery is often required. The current study presents a rare case of pars fracture involving nonconsecutive segments and discusses the management options.
In this case report, we review the patient’s history, clinical examination, radiologic findings, and management, as well as the relevant literature. An 18-year-old man presented to the clinic with worsening lower back pain related to nonconsecutive pars fractures at L2 and L5. After 6 months of conservative management, diagnostic computed tomography–guided pars block was used to localize the symptomatic level at L2, which was treated surgically; the L5 asymptomatic pars fracture did not require surgery. At the last follow-up 2 years after surgery, the patient was playing baseball and basketball, and denied any back pain.
This article reports a case of rare nonconsecutive pars fractures. Conservative management for at least 6 months is recommended. Successful management depends on the choice of appropriate treatment for each level. Single-photon emission computed tomography scan, and computed tomography–guided pars block are valuable preoperative tools to identify the symptomatic level in such a case.
Radiographic assessment using standing anteroposterior, lateral, and oblique radiographs of the thoracolumbar spine is useful in the initial assessment. A SPECT scan of the lumbosacral spine is highly sensitive for identifying spondylolytic defects when plain radiographs are within normal limits, yet a high index of suspicion remains given the patient’s history and physical examination findings.9,10 Increased radionuclide uptake within the pars indicates a stress reaction and, possibly, a more acute pathology. The plain radiographs of the patient showed only L5 spondylolysis. However, a SPECT scan showed only increased uptake in L2 pars on both sides. These findings suggested chronic L5 and acute L2 pars defects. A thin-cut CT scan gives the best visualization of pars defect and can help in differentiating chronic defect with sclerotic margins versus acute defect with hazy irregular margins. In the current case, the CT scan showed changes consistent with unilateral chronic L5 and bilateral acute L2 pars defects.
The origin of the pain in spondylolysis is from the tissues rich in nociceptive nerve endings in the loose posterior arch. A CT-guided pars block is a very useful diagnostic preoperative tool that confirms the symptomatic level in cases of multilevel pars defect, especially if they are noncontiguous. In this case, the diagnostic preoperative bilateral L2 pars block confirmed that the pain generator was the acute L2 rather than the chronic L5 pars defect. This step assured that surgical treatment involving only the L2 level would be beneficial in alleviating the patient’s back pain after the failure of 6 months of conservative treatment.
Most patients with single-level spondylolysis respond to conservative treatment, especially after early diagnosis and treatment. The traditional nonoperative treatment of children and adolescents with a symptomatic spondylolytic lesion was a period of rest and progressive increased activity with physical therapy. Immobilization with an LSO was reserved for individuals who did not respond to rest and physical therapy.11 However, multiple studies revealed early immobilization achieved results superior to activity restriction alone, and individuals who underwent a period of activity restriction prior to bracing were more likely to experience persistent symptoms.12-14 Our patient underwent conservative treatment for 6 months, in the form of LSO, cessation of sport activities, and physical therapy, which failed to give him relief of his back pain.
Surgical intervention is warranted for adolescents with persistent, debilitating pain intractable to at least a 6-month period of nonoperative management. Additional indications for surgical management are those individuals who present with neurologic deficits and isthmic spondylolisthesis. Surgical treatment involves direct pars repair with iliac crest bone graft and use of a sublaminar hook/pedicle screw construct, cerclage wire, or pars screw.15-18
In contrast to single-level pars defects that respond well to conservative treatment, there are conflicting reports regarding the management of multiple-level pars fractures; a few reports suggest good outcome with conservative management, but the majority state that surgery is often required and conservative measures are rarely useful.1-4,6 Nayeemuddin and colleagues19 reported a case of a 16-year-old football player who presented with a 4-month history of constant low back pain related to bilateral L3 and L5 pars defects that responded to 1 year of conservative management, when the more acute fractures at L3 showed complete bony union and the patient had symptomatic pain relief and was able to return to full sporting activity.
Chang and colleagues2 reported 10 patients with adjacent 2-level bilateral spondylolysis treated successfully using a pedicle screw–hook construct with autogenous bone grafting. Ogawa and colleagues5 reported adjacent 2-level spondylolysis in 5 patients and 3-level spondylolysis in 2 patients, who were treated successfully by segmental wire fixation and bone grafting. Ivanic and colleagues15 retrospectively reviewed 113 patients with spondylolysis who were treated with direct repair using a hook-screw construct and showed a pseudoarthrosis rate of 13.3%. Superior fusion rates were observed in patients 14 years and younger compared with older patients, particularly those 20 years and older.15 Roca and colleagues16 prospectively analyzed 19 consecutive cases of spondylolysis that were repaired using a hook-screw construct. Twelve of 13 patients (92%) who were 20 years or younger at the time of the study (average age, 17.2 years) had fusion, whereas, in 6 patients 21 years and older (average age, 27.5 years), no cases of fusion were observed. The patients 20 years or younger had significantly better clinical results than those obtained in the patients 21 years and older. The authors concluded that pedicle screw–hook fixation is a useful alternative in the treatment of spondylolysis in adolescents, but did not recommend this procedure in patients older than 20 years.16
