Literature Review
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The incidence of spondylolysis has been reviewed in separate studies. In one study, a significant number of athletes with low back pain were diagnosed with spondylolysis (pars fracture) under the age of 18. This is a common diagnosis in teenage athletes.(ref #14)

The development of sponylolysis is due to biomechanical vulnerability of the area that develops the fracture (ref #39, ref #53, ref #59, ref #62, ref #63). This concept provides that the pars is thin, the posterior arch is not at maximum strength and the disc is less resistant to shear force. In additon, extension sports are involved (gymnastics, etc) due to shear stresses in the pars with extension of the spine and repeated microfracture with repeated extension (ref #39, ref #40, ref #45)

The clinical pattern could involve the following anatomic combinations.

A stress reaction in bone is an impending stress fracture and may be detected on a SPECT scan. A pars defect is a formal fracture through the anatomic zone called the pars interarticularis.

Many patients with an acute pars fracture can be treated conservatively with bracing, temporary restriction of activity, and physical therapy. The vast majority of patients improve and return to sports (ref #24). The statistical progression of low grade slips is low and once symptoms are resolved the majority of adolescents return to their sport (ref #6, ref #9).The lower grade slips are grade I and II, the higher grade slips are III and IV.

Surgical management of lower grade slips can involve direct repair of the pars fracture (ref #1, ref #2, ref #3, ref #10, ref #12, ref #17, ref #21, ref #22, ref #23, ref #27, ref #28, ref # 32, ref #41, ref #49) or fusion in the postion of the slip or with reduction of the slip to normal anatomic position (ref #29, ref #30, ref #35, ref #37, ref #47, ref #54). The results of surgery are in general good for low grade slips. Higher grade slips often involve greater magnitude of surgery and the results depend on the preoperative condition of the patient and the nature of the partiuclar operation employed (ref #5, ref #7, ref #11, ref #13, ref #25, ref #31, ref #36, ref #42, ref #44, ref #46, ref #55, ref #56, ref #57).

Complications
Complications in surgery for adolescent spondylolisthesis depend on the grade of the slip and the nature of the operation and surgical approach. The general risks of spine surgery are death, paralysis, failure to improve, failure to fuse, hardware failure, nerve root injury, spinal fluid leak, infection, etc.

Author’s Comment
The diagnosis of stress fractures (stress reaction in bone) in adolescent athletes is often made on a SPECT scan. The completed pars defects (completed fractures) are found on CAT scans. The presence of a slip implies the presence of the pars fractures in this age group in the overwhelming majority of cases. Most athletes can be treated non-operatively with a good prognosis. Occasionally, direct repair of the pars defects or a posterolateral fusion are necessary to provide symptom relief. The more advanced slips (grade III and IV) may require more significant surgery.

References
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