Two types of laminolysis in adolescent athletes
© The Author(s) 2012
Received: 13 October 2011
Accepted: 1 July 2012
Published: 20 July 2012
Bony defects in the spine are divided into three main types: spondylolysis, pediculolysis, and laminolysis. Lumbar spondylolysis is a well-known stress fracture that occurs frequently in adolescent athletes. Pediculolysis means stress fracture of the pedicle, which sometimes occurs subsequent to unilateral spondylolysis. Laminolysis is a rarely reported stress fracture similar to spondylolysis and pediculolysis that sometimes causes low back pain (LBP). However, its pathomechanism has not been elucidated. Recently, we encountered four adolescent athletes with symptomatic laminolysis. Mean age was 15.8 (range 15–17) years. All subjects reported severe LBP exacerbated by extension of the lumbar spine, and radiology revealed two types of laminolysis: hemilaminar type and intralaminar type. To elucidate the mechanisms of each type, we reviewed a biomechanical study, and found that the hemilaminar type was thought to be subsequent to contralateral spondylolysis, while the intralaminar type might be a result of a stress fracture due to repetitive extension loading.
KeywordsLaminolysis Spondylolysis Retroisthmic cleft Lumbar spine Laminar fracture Stress fracture
Bony defects in the posterior elements of the spine are divided into three main types: spondylolysis, pediculolysis, and laminolysis. Lumbar spondylolysis is a well-known stress fracture which occurs frequently in adolescent athletes [1, 2], and is found in around 6 % of the general adult population [3, 4]. Pediculolysis means stress fracture of the pedicle, which sometimes occurs subsequent to unilateral spondylolysis . Laminolysis is a defect in the lamina, similar to spondylolysis and pediculolysis, and is reported to cause low back pain (LBP) in adolescent athletes . Although laminolysis is regarded as a stress fracture , its pathomechanism has not been clearly elucidated.
We have previously reported two cases of laminolysis . Here, we present four cases, including the previous two cases, of adolescent athletes with laminolysis. On the basis of radiological and biomechanical findings for the defects, we propose two main types of laminolysis.
Four adolescent athletes (mean age, 15.8 years; range 15–17 years) with laminolysis complained of LBP which prolonged for more than six months. All experienced severe LBP exacerbated by extension of the lumbar spine. For diagnosis, we performed plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) for all patients. On the basis of radiological findings, we divided the cases into two types depending on the site of laminolysis: hemilaminar type (cases 1 and 2) and intralaminar type (cases 3 and 4). All patients provided informed consent to participate in the study.
Various types of bony defects in the spine have been reported [1, 4, 5, 7]. They are termed spondylolysis, pediculolysis, and laminolysis according to the defect site. All are regarded as stress fractures, and constitute the main factors of LBP in adolescent sports players. In particular, Micheli and Woods reported that 47 % of adolescent patients with LBP who visited a sports clinic had lumbar spondylolysis . Laminolysis is often described as an incidental finding , and sometimes causes LBP in athletes .
Here, we found two types of laminolysis: hemilaminar type (cases 1 and 2) and intralaminar type (cases 3 and 4). The former has a cleft in the unilateral pars and the latter has a coronal fracture line though both laminae. In a biomechanical study, Sairyo et al. reported that extension loading causes a more coronally oriented fracture line, while rotational loading causes a more sagittally oriented fracture line . Therefore, the intralaminar type is considered to result from a stress fracture due to repetitive extension loading. In the presence of hemilateral spondylolysis, axial rotation of the contralateral pedicle and pars interarticularis increases stress an average of 6.8-fold, with a 12.6-fold increase being the highest .
Patients with spondylolysis are treated conservatively; relative rest, abstinence from sports, and use of a trunk brace. Similar to spondylolysis, conservative treatment is effective for pain relief in patients with laminolysis. From a biomechanical perspective, reducing extension loading should be an effective way to treat intralaminar-type laminolysis. In addition, to prevent hemilaminar-type laminolysis, patients with unilateral spondylolysis need be carefully followed.
Conflict of interest
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