When is surgery indicated for the treatment of pars interarticularis injury?

Updated: Jan 22, 2019
  • Author: Gerard A Malanga, MD; Chief Editor: Craig C Young, MD  more...
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Answer

Indications for surgery include (1) persistent pain unrelieved by rest and immobilization for more than 6 months, (2) progression to spondylolisthesis, (3) spondylolisthesis of greater than grade II in a patient about to undergo the preadolescent growth spurt, and (4) any significant neurologic abnormalities. [3, 54, 81] As discussed above, the prognosis of bone healing is dependent on the stage of the spondylolytic lesion. [11] Dubousset reported that if treatment is delayed for 3 months or more after the fracture occurs, nonoperative treatment is unsuccessful. [82] Surgical options include direct repair of the spondylolytic defect, fusion in situ, reduction and fusion, and vertebrectomy.

Ideal candidates for direct repair of the pars defect are those with early lesions, with lysis but no listhesis, and with the lytic defect between L1-L4. L5 lytic defects have been reported to yield less predictable results due to the fact that many L5 defects occur because of a developmentally weakened and elongated pars. [24] Surgical techniques generally employ debridement of the lytic defect, application of large amounts of autogenous iliac crest cancellous bone graft, and tension band wiring or screw fixation from the cephalad portion of the posterior element to the free-floating caudal fragment. Bone healing of 75% to greater than 90% and symptomatic relief in 70-90% of the patients have been reported with the screw fixation technique. [83, 84] Tension band wiring with 73-100% bony union has been reported. [24, 85]

Ideal candidates for a fusion-in-situ procedure are patients with a low-grade spondylolisthesis that remains symptomatic despite nonoperative measures or those with a high-grade spondylolisthesis and acceptable sagittal balance. Reports of fusion rates of 83-95% and good or excellent results in 75-100% of the patients have been reported. [86, 87]

Decompression and fusion are indicated when severe neurologic signs of compression are present, such as radiating leg pain, numbness, and weakness with corresponding imaging studies demonstrating nerve root or thecal sac compression. Reduction is indicated to prevent the complications of progression of slip, pseudoarthrosis, and cosmetic deformity associated with in-situ fusion; hence, reduction of high-grade slips is often performed. Reduction (closed or open) serves to correct lumbosacral kyphosis and to diminish the sagittal translation seen in high-grade slips. Also, correction of lumbosacral kyphosis decreases the compensatory hyperlordosis above the fusion site. [24]

Spondyloptosis, complete slippage of one vertebra on the next lower vertebra, is an indication for vertebrectomy. This condition has a high rate of neurologic dysfunction, such as cauda equina syndrome. The Gaines procedure (stage 2) is commonly used. The first stage is anterior resection of the L5 vertebral body. Several days later, the second stage involves posterior resection of the remainder of the L5 pedicles and posterior elements after distraction via Harrington outriggers. Pedicle screws are placed in L4 and S1, and reduction is performed. This procedure is associated with iatrogenic neurologic deficits due to the preexisting neurologic dysfunction from the slipped vertebra. Reports of 25-30% of patients developing neurologic deficits postoperatively have been reported. [24]


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