Pars Interarticularis Injury Treatment & Management

Updated: May 16, 2022
  • Author: Gerard A Malanga, MD; Chief Editor: Craig C Young, MD  more...
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Acute Phase

Rehabilitation Program

Physical Therapy

During the acute phase of rehabilitation for patients with spondylolysis, the focus is to reduce the pain. Instruction in posture and biomechanics with activities of daily living (ADL) can help to protect the injured pars, thus reducing symptoms and preventing further injury. A period of rest for an average of 2-4 weeks can provide beneficial effects by modulating pain, decreasing inflammation, and decreasing the risk for further progression of a pars stress reaction to a frank fracture.

Applying ice to the injured area for 20 minutes 3-4 times a day in conjunction with performing gentle ROM exercises and stretching of the quadriceps and hamstring muscles is strongly advised. Activity modification is recommended. The patient is advised to stop the activity or sport that evokes the back pain for an average of 2-4 weeks. [37, 48, 56] In particular, the patient should avoid any activities involving hyperextension.

A retrospective study by Selhorst et al found that in adolescent athletes with acute spondylolysis who were referred to physical therapy after less than 10 weeks of rest, the median period for full return to activity was almost 25 days shorter than it was for those referred to physical therapy after more than 10 weeks of rest, with no statistically significant difference in the risk of adverse reactions seen between the two groups. [57]


Indications for the use of a brace are lack of symptom improvement by 2-4 weeks, the presence of a true fracture, the presence of a spondylolisthesis, the need for pain control, and the lack of patient compliance to activity restrictions. [58]

There are no randomized, double-blinded studies of brace application in the treatment of spondylolysis; however, several authors have demonstrated good results. In 1985, a widely referenced study by Steiner and Micheli evaluated 67 patients with symptomatic spondylosis or low-grade spondylolisthesis via plain film or planar bone scan without a control group. [59] A rigid, antilordotic, modified Boston brace was applied for 23 hours per day for 6 months, followed by 6 months of weaning. Follow-up at an average of 2.5 years demonstrated good or excellent results, and 23% of patients showed bony healing on radiograph.

Furthermore, Blanda et al examined 62 patients with spondylolysis and found that 84% had excellent results with conservative treatment, which included using a lumbar brace, at an average follow-up of 4.2 years. [38] Overall, the results of bracing vary from complete healing with resolution of back pain to nonunion, persistence of pain, or progression to spondylolisthesis. Using return to sport as the end point, the success of bracing has ranged widely from 7-84%. [38, 60, 61, 62, 63]

In contrast to the above studies, several authors have reported on the treatment of patients with symptomatic spondylolysis using a soft brace or no brace instead of a rigid brace. Rigid braces do not have a stabilizing effect on the sagittal, vertical, and transverse intervertebral translations and provide gross limitation of body motion.

Morita et al studied 185 adolescents with spondylolysis and classified the pars defects into early, progressive, and terminal stages. [63] Conservative management included the use of a conventional lumbar corset for 3-6 months. Follow-up radiographs showed healing without the use of a rigid brace in 73% of the patients in the early stage, in 38.5% of those in the progressive stage, and in 0% of those in the terminal stage. [63]

Jackson et al also examined 7 athletes who had a positive bone scan with negative lumbosacral plain films and discovered that if the bony reaction was recognized early, healing at the subroentgenographic level could occur with rest and activity modification without the use of a brace. [64] Furthermore, Congeni et al examined 40 young athletes diagnosed with spondylolysis on bone scan and followed a treatment protocol of nonrigid bracing, specific educational guidelines instructing patients to avoid hyperextension activities, flexibility training, strengthening, and cardiovascular activities. [51] Only 2 of 40 patients needed to switch to a rigid brace after 4 weeks due to persistent pain. None of the patients required surgical intervention at a follow-up period ranging from 3 months to 5 years. [51]

Research on the biomechanical effects of bracing and its effect of immobilization on the spine has been performed. Axelsson et al studied 7 patients following posterolateral lumbosacral fusions without internal fixation. [65] These individuals were examined by roentgen stereophotogrammetric analysis in supine and erect positions 1 month postsurgery without lumbar support, with a molded rigid orthosis, and with a canvas corset with a molded plastic posterior support. Neither of the 2 types of lumbar support showed any evidence of a stabilizing effect on the sagittal, vertical, or transverse intervertebral translations.

Lantz and Schultz also reviewed 4 trunk movements in 5 young men wearing a lumbosacral corset, a chairback brace, and a molded plastic thoracolumbosacral orthosis (TLSO) in standing and sitting positions. [66] All 3 orthoses restricted some gross body motion, approximately one half to two thirds more than in patients without an orthosis. Both studies confirmed that a lumbosacral orthosis restricts gross motions of the trunk rather than intervertebral mobility in the lumbar spine.

Willems et al investigated whether plaster casts actually immobilize the lumbosacral joint. They studied 10 patients placed in a plaster cast and examined the lumbosacral joint of these patients, using a 3-dimensional (3-D) motion analysis system in static and dynamic test conditions. Willems et al found that plaster casting did decrease lumbosacral mobility during static test conditions and did not significantly decrease the mobility of the lumbosacral joint in dynamic test conditions. [67] Hence, the most consistent effect of the lumbosacral orthoses appears to be the limitation of gross body motion. The rigid bracing seems to be the most effective.

Sairyo et al assessed the efficacy of using a hard brace to restrict lumbar rotation and extension. They treated 37 patients younger than 18 years with incomplete pars interarticularis injury. They stratified the patients into 4 categories: early, progressive with high signal intensity, progressive with low signal intensity, and terminal defects. The union rates for early defect were 94%, progressive with high signal intensity were 64%, progressive with low signal intensity were 27%, and terminal were 0%. They also showed that based on CT findings, the mean time to heal was 3.2 months for the early-defects group, 5.4 months for the progressive with high signal intensity group, and 5.7 months for the progressive with low signal intensity group. They concluded that patients with early-stage defects are the best candidates for conservative treatment with a hard brace based on their findings. [68]

Based on current literature, the need for bracing is limited. Bracing can be considered in patients who continue to have symptoms despite a period of rest. For most of these patients, nonrigid bracing is adequate. The Sairyo et al study suggests that patients younger than 18 years with early defects on CT scan may be good candidates for rigid hard bracing for 3 months, owing to the high rate of union in their study. [68]

Surgical Intervention

During the acute phase, it is the general consensus in the medical community to attempt conservative management before implementing surgical intervention. Many studies support the nonsurgical approach.

Wiltse et al demonstrated that 12 of 17 young patients diagnosed with spondylolysis showed osseous healing with conservative treatment and no surgery. [8] Steiner and Micheli demonstrated radiologic healing in 18% of 67 patients with symptomatic spondylolysis or grade I spondylolisthesis. [59] Furthermore, Blanda et al examined 62 patients with spondylolysis and found 52 patients had excellent results with conservative treatment, with an average follow-up of 4.2 years. [38] In a longitudinal study of young athletes with early detected spondylolysis who were treated with conservative management, 29 of 32 respondents had good to excellent low back outcome scores at an average follow-up interval of 9 years. [69]

Early diagnosis is an important factor for a good prognosis in bone healing. Ciullo and Jackson studied gymnasts and found that the longer symptoms were present before treatment, the more likely that surgical intervention was needed. [70] Jackson also examined 7 athletes with positive bone scans and negative lumbosacral plain films. [64] Jackson discovered that if the bony reaction was recognized early, healing at the subroentgenographic level could occur with conservative treatment.

Furthermore, Morita et studied 185 adolescents with spondylolysis and classified the pars defects into early, progressive, and terminal stages. [23] Conservative management produced healing in 73% of the early stage cases, in 38.5% of the progressive stage cases, and in 0% of the cases with terminal defects.

These studies suggest that spondylolysis can successfully be treated using conservative treatment if diagnosed at an early stage.

Tatsumura et al studied factors associated with the failure of conservative therapy in adolescents and children with acute unilateral lumbar spondylolysis with bone marrow edema. They found that progressive pathological stage, contralateral pseudarthrosis, and L5 lesion level had a significant negative effect on the achievement of successful bony union. [71]

Sairyo et al described a new minimally invasive technique to repair pars interarticularis defects in 2 adults, in which they modified the established pedicle screw and hook-rod system technique. [72] Percutaneous insertion of bilateral pedicle screws was performed with the Sextant system; then, an illuminated tubular retractor was inserted through a small skin incision into the pars defect, and the nearby bursa and fibrocartilaginous mass were removed. The pseudoarthrosis at the spondylolytic level was decorticated, followed by implantation of bone grafts and attachment of the hook portion of the hook-rod system to the lamina. The rod was secured at the pedicle screws' tulip head. [72] Sairyo et al reported resolution of the patients' low back pain immediately postsurgery, with postoperative return to their work or sports activities by 3 months.

Gillis et al described an application of a minimally invasive surgery pars repair technique on 8 athletes which attempts to recreate the normal anatomy rather than fusing across a motion segment. The study reported that minimally invasive surgery advantages include less muscle tissue disruption and restoration of the natural anatomy which leads to a more rapid recovery, decreased perioperative pain, minimal blood loss, earlier mobilization and decreased hospital length of stay. At one year follow-up, 6 of the 8 athletes had been able to return to their previous sport activity level. [73]

Other Treatment

The use of external electrical stimulation for the healing of spondylolysis has been reported in 2 cases in the literature. Electrical stimulation has been used to heal fractures in all areas of the body. Although the literature supports the efficacy of electrical stimulation in healing fractures, the use of electrical stimulation for healing of spondylosis is not well studied and generally not necessary. [74]


Recovery Phase

Rehabilitation Program

Physical Therapy

Once the LBP is controlled during the acute phase of treatment, a therapy program can be initiated. If the patient’s symptoms significantly decrease with rest and activity modification, a regimen of hamstring and hip flexor stretching, abdominal strengthening, lumbar flexion exercises, and cross-training with extension precautions can be instituted. If the patient requires the use of a brace, an initial program of hamstring stretching while wearing the brace can be started.

As the symptoms continue to decrease, lumbar flexion exercises, abdominal strengthening, and hip flexor and hamstring stretching can be instituted without the use of the brace. Cross-training in nonextension activities can be performed, such as the stationary bike and hydrotherapy. [4, 23, 8, 48, 51, 59, 61, 63, 64, 65]

These exercises are eventually incorporated into a more comprehensive rehabilitation program that includes spinal stabilization exercises that help the patient in finding the neutral position of the spine (ie, the position that produces the least amount of pain). This position is dependent on the specific individual and is determined by the pelvic and spine posture that places the least stress on the elements of the spine and supporting structures. In classic spondylolysis pain, the neutral spine has a flexion bias. Dynamic lumbar stabilization exercises may be used to help provide dynamic muscular control and to protect the spine from biomechanical stresses, such as tension, compression, torsion, and shear. [75]

Surgical Intervention

See Maintenance Phase.


Maintenance Phase

Rehabilitation Program

Physical Therapy

The maintenance phase represents the final phase of the rehabilitation program for those affected by spondylolysis, spondylolisthesis, or pars interarticularis injuries. A home exercise regimen is prescribed and should be performed on a daily basis. An analysis of variables should be performed for each individual athlete so that further injuries can be prevented. Such variables include biomechanical errors, anthropomorphic features, posture, cardiovascular fitness, psychosocial factors, level of training, specific activities, medical pathology, and sports participation.

Biomechanical errors should be assessed with the specific requirements of the sport in mind. For example, movements in ballet dancing require maximal hip external rotation; therefore, a deficit may cause stretching of the abdominal muscles and thereby increase lumbar lordosis. Consequently, increased stress on the posterior elements of the spine may occur. [75, 76]

Anthropomorphic features involve looking at predictive factors that may lead to back injury. For example, hypermobility of the spine in lumbar extension in female gymnasts may be predictive of back injuries. [77, 78, 79] The posture of the athlete in the specific sport is also important to analyze, because it is well known that hyperextension of the back can cause increased stress on the posterior elements of the spine. A tight hip flexor muscle can also cause increased stress on the spine because it arises from the sides of the intervertebral discs and the adjacent ends of the vertebral bodies from T12-L4 and from the transverse processes of all the lumbar vertebrae. [80]

Intramuscular electromyography (EMG) recordings have shown that the only lumbar movement that consistently recruits the hip flexor is a deliberate increase in lumbar lordosis while an individual is standing erect. [81] Therefore, if this muscle is tight, it can promote an increase in lumbar lordosis and, hence, increased stress on the posterior elements of the spine. Another study also showed an association of LBP with tight hip flexors. [82]

Cardiovascular fitness should also be stressed in order to increase endurance and decrease fatigue. Psychosocial factors are also important to incorporate into the maintenance phase, because pain can be magnified by depression.

Medical pathology should also be evaluated, especially in female athletes who are at risk for the female athlete triad, which includes disordered eating patterns, amenorrhea, and osteoporosis. Eating disorders include anorexia nervosa and bulimia nervosa. The prevalence of eating disorders in female athletes is 5-10% higher than in female nonathletes, and some reports indicate the prevalence is as high as 15-62%. [83] The prevalence of primary amenorrhea is reported to be as high as 4-66% in female athletes, compared with 2-5% in the general population. [83]

Amenorrhea is postulated to occur as a result of poor diet and excessive exercise, which can cause hormonal changes that inhibit ovulation. Consequently, with low estrogen levels, early osteoporosis can occur; therefore, the risk for fracture is increased in this population.

Sports participation should also be examined. For instance, the athlete may be involved in more than one sport. The above variables should also be carefully analyzed for the second sport. Regardless of the sport, maintenance of proper spine positioning during play should focus on spinal stabilization and maintaining a neutral spine. The program should progress to a functional exercise regimen and then to sport-specific training. In general, the abdominal, gluteal, and back extensor muscles are the key muscles to strengthen and build endurance.

Surgical Intervention

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. [4, 56, 84] As discussed above, the prognosis of bone healing is dependent on the stage of the spondylolytic lesion. [23] Dubousset reported that if treatment is delayed for 3 months or more after the fracture occurs, nonoperative treatment is unsuccessful. [85] 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. [37] 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. [86, 87] Tension band wiring with 73-100% bony union has been reported. [37, 88]

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. [89, 90]

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. [37]

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. [37]

Complications of surgery include disc degeneration adjacent to previously fused segments; however, Szypryt et al reported that disc degeneration, either at the disc or adjacent disc., was uncommon in patients younger than 25 years. [91, 92] In fact, the investigators found that patients who are older than 25 years and who are not treated developed a higher prevalence of disc degeneration at the deranged motion segment, as well as at the adjacent segment when compared with age-matched healthy patients. [91] Other complications include slip progression after surgery and iatrogenic neurologic deficit. [37]


A consultation with a spine surgeon may be indicated if conservative management is unsuccessful.