Development and biomechanical analysis of an axially controlled compression spinal rod for lumbar spondylolysis.

BACKGROUND: To elucidate the differences in mechanical performance between a novel axially controlled compression spinal rod (ACCSR) for lumbar spondylolysis (LS) and the common spinal rod (CSR). METHODS: A total of 36 ACCSRs and 36 CSRs from the same batch were used in this study, each with a diameter of 6.0 mm. Biomechanical tests were carried out on spinal rods for the ACCSR group and on pedicle screw-rod internal fixation systems for the CSR group. The spinal rod tests were conducted following the guidelines outlined in the American Society for Testing and Materials (ASTM) F 2193, while the pedicle screw-rod internal fixation system tests adhered to ASTM F 1798-97 standards. RESULTS: The stiffness of ACCSR and CSR was 1559.15 ±â€…50.15 and 3788.86 ±â€…156.45 N/mm (P < .001). ACCSR's yield load was 1345.73 (1297.90-1359.97) N, whereas CSR's was 4046.83 (3805.8-4072.53) N (P = .002). ACCSR's load in the 2.5 millionth cycle of the fatigue four-point bending test was 320 N. The axial gripping capacity of ACCSR and CSR was 1632.53 ±â€…165.64 and 1273.62 ±â€…205.63 N (P = .004). ACCSR's torsional gripping capacity was 3.45 (3.23-3.47) Nm, while CSR's was 3.27 (3.07-3.59) Nm (P = .654). The stiffness of the pedicle screws of the ACCSR and CSR group was 783.83 (775.67-798.94) and 773.14 (758.70-783.62) N/mm (P = .085). The yield loads on the pedicle screws of the ACCSR and CSR group was 1345.73 (1297.90-1359.97) and 4046.83 (3805.8-4072.53) N (P = .099). CONCLUSION: Although ACCSR exhibited lower yield load, stiffness, and fatigue resistance compared to CSR, it demonstrated significantly higher axial gripping capacity and met the stress requirement of the human isthmus. Consequently, ACCSR presents a promising alternative to CSR for LS remediation.

Successful Treatment of Cervical Spondylolysis with Grade-II Spondylolisthesis using Single-Level ACDF: A Case Report.

BACKGROUND Cervical spondylolysis with spondylolisthesis is a rare disorder. According to previous reports, the spondylolisthesis is usually Meyerding Grade I, with only a limited number of cases receiving surgical treatment. We hereby report a special case of cervical spondylolysis with Grade-II spondylolisthesis, treated with single-level anterior cervical discectomy and fusion (ACDF), and present a literature review related to this problem. CASE REPORT Here, we report the case of a 52-year-old man who complained of posterior neck pain and numbness of the bilateral upper limbs. Radiological examination showed bilateral spondylolysis of the C6 and Meyerding Grade-II spondylolisthesis of C6 on C7 with instability. The patient underwent a single-level C6/C7 ACDF surgery. The symptoms of neck pain and bilateral upper-limb numbness were relieved immediately after surgery. The immediate postoperative radiological examination showed successful restoration of sagittal alignment. At 3-month follow-up, the patient had returned to normal life without any symptoms. At 2-year follow-up, computed tomography showed that C6-C7 fusion had been achieved and alignment was maintained. CONCLUSIONS Cervical spondylolysis, as an uncommon spinal disorder, has been regarded as a congenital abnormity, and has unique radiological characteristics. For most of the cases with cervical spondylolysis, even with Grade-II spondylolisthesis, single-level ACDF can achieve good clinical and radiological outcomes.

Buck technique supplemented by temporary intersegmental pedicle screw fixation to repair lumbar spondylolysis in youth.

BACKGROUND: Lumbar spondylolysis is a bone defect in the pars interarticularis of the lumbar vertebral, which is a common cause of low back pain in youth. Although non-surgical treatment is a mainstream option, surgery is necessary for patients with persistent symptoms. Buck technique is widely used as a classical direct repair technique, but it cannot achieve reduction of low-grade spondylolisthesis and reconstruction of lumbosacral sagittal balance. We have described a novel surgical procedure based on Buck technique with temporary intersegmental pedicle screw fixation, and report a series of clinical outcomes in 5 patients to provide a reference for the clinical treatment of young lumbar spondylolysis. METHODS: Five young patients with symptomatic lumbar spondylolysis with a mean age of 19.20 ± 5.41 years underwent surgical treatment after an average of 7.60 ± 1.52 months of failure to respond to conservative treatment, using a new surgical procedure based on Buck technique combined with temporary intersegmental pedicle screw fixation. RESULTS: Five patients were successfully operated without serious complications such as nerve and vascular injury. The average operation time was 109.00 ± 7.42 min, the interpretative average blood loss was 148.00 ± 31.14 ml, and the average fusion time was 11.20 ± 1.64 months. All patients were followed up for 2 years after surgery, and the visual analogue score (VAS) of low back pain and Oswestry disability index (ODI) scores were significantly improved compared with those before surgery, and the Henderson's evaluation were rated excellent or good. After the removal of the internal fixation, it was observed that temporary intersegmental fixation could repair the isthmus, reduce lumbar spondylolisthesis, and reconstruct the sagittal balance of the lumbosacral vertebrae while preserving lumbar motion and preventing intervertebral disc degeneration. Postoperative MRI indicated the Pfirrmann classification of the affected discs: 1 case from grade III to grade II, 3 cases from grade II to grade I, and 1 case remained grade II. CONCLUSIONS: Buck technique supplemented by temporary intersegmental pedicle screw fixation is a highly applicable and effective method for the treatment of adolescent lumbar spondylolysis. The isthmic fusion is accurate, and temporary intersegmental fixation can effectively prevent disc degeneration and reconstruct the sagittal balance of lumbosacral vertebra.

Biportal endoscopic bone graft repair and percutaneous screw fixation for lumbar spondylolysis-technical note and clinical outcomes.

BACKGROUND: Lumbar spondylolysis involves a bony defect in the vertebral pars interarticularis, predominantly affecting the lower lumbar spine. This condition is a significant etiological factor in lumbar instability and recurrent lower back pain, particularly in young individuals. While conservative treatments are the primary intervention, they often fail to provide relief, necessitating surgical approaches. Notwithstanding, executing bone grafting and fixation in the pars interarticularis defect simultaneously through minimally invasive surgery remains challenging. METHOD: This study elucidates the biportal endoscopic spinal surgery (BESS) technique, innovatively applied for bone graft repair and percutaneous cannulated screw fixation in a patient with lumbar spondylolysis. We offer a detailed walkthrough of the technical procedures supplemented with follow-up radiographic evidence. RESULTS: The BESS technique facilitated meticulous clearance of the defect site, coupled with bone grafting and cannulated screw fixation, effectively addressing lumbar spondylolysis through a minimally invasive approach. This method holds promise for achieving substantial osseous fusion at the vertebral pars interarticularis defect site. CONCLUSION: The BESS procedure for lumbar spondylolysis ensures a clean and prepared defect site for grafting and encourages successful osseous fusion, spotlighting its potential as a viable surgical strategy in managing this condition.

Factors associated with non-fusion after direct pars repair of lumbar spondylolysis with pedicle screw and lamina hook: a clinical and CT-assessed study.

BACKGROUND: Pedicle screw and lamina hook (PSLH) technique is an effective and popular method for direct pars repair of lumbar spondylolysis. There is a lack of studies to explore factors that may influence the healing of spondylolysis after direct pars repair surgery. The present study aimed to investigate the factors associated with non-fusion after direct pars repair of lumbar spondylolysis with PSLH technique. METHODS: A total of 55 subjects (average age 21.1 ± 6.3 years, a total of 120 pars defects) diagnosed with symptomatic spondylolysis and underwent pars repair surgery with PSLH were followed up and their clinical data were analyzed. Subjects were divided into a non-fusion group and fusion group according to whether the pars defect had bony fusion at last follow-up assessed by CT. Radiographic data, data related to spondylolysis and clinical outcomes were collected and compared between groups. RESULTS: The mean follow-up time of the 55 patients was 24.8 ± 12.0 (12-64) months. Among the 120 pars defects, 101 defects were successfully fused and 19 were not fused according to CT. The fusion rate was 84.2%. Multivariable logistic regression analysis showed the factors correlated with non-fusion after pars repair surgery: whether the spondylolysis segment was associated with spina bifida occulta (SBO) (P = 0.001), stage of the defect (P = 0.047), width of the defect (P = 0.002), and disc degeneration (P = 0.014). CONCLUSION: Direct pars repair by PSHL is a reliable treatment for lumbar spondylolysis with a fusion rate of 84.2%. Association with SBO of the spondylolysis segment, a terminal stage of the defect, a wider defect gap, and grade III disc degeneration may be factors associated with non-fusion after direct pars repair of lumbar spondylolysis with PLSH. Non-fusion patients after pars repair appear to have worse clinical results compared to fusion patients.

Direct Repair of Symptomatic Lumbar Spondylolysis Using Rod-Screw-Cable System.

OBJECTIVE: To assess the efficacy of a new direct lysis repair technique using internal fixation with rod, screws, and Songer cable in symptomatic lumbar spondylolysis. METHODS: Between December 2015 and January 2020, patients who were diagnosed with symptomatic lumbar spondylolysis and surgically treated with a rod-screw-cable system were recruited. Pedicle screwing by the Magerl technique was performed in all included patients, followed by direct lysis repair with bone allograft and demineralized bone matrix by stabilizing the posterior lamina and spinous process using a rod-screw-cable system. Clinical outcome was measured using the visual analog scale and Oswestry disability index preoperatively and 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively. RESULTS: Sixteen patients were included in this study-11 men and 5 women (mean age: 47 years; range, 26-67 years). The lytic defects were at L4 and L5 in 6 and 10 patients, respectively. The mean follow-up period was 41 months (24-62 months). The visual analog scale values were 7.3, 6.1, 4.3, 3.3, 2.1, and 1.9 preoperatively and 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively, respectively. The Oswestry disability index values were 59.8%, 55.4%, 41.7%, 32.4%, 21.1%, and 16.9% for the same periods, respectively. No patient had an increase in the slip after surgery. There were no significant complications such as implant failure. CONCLUSIONS: Our technique provides rigid intra-segmental repair of spondylolysis without intersegmental motion interference, even if the patient is older or has disc degeneration.

Comparing the Wiltse approach and classical approach of pedicle screw and hook internal fixation system for direct repair of lumbar spondylolysis in young patients: A case-control study.

The aim of this study was to investigate the clinical effect of direct isthmus repair via Wiltse approach and classical approach in the treatment of simple lumbar spondylolysis in young patients. Thirty-three patients with simple lumbar spondylolysis underwent direct isthmic repair via the Wiltse approach (n = 17) or the classical approach (n = 16). The operation time, intraoperative blood loss, postoperative drainage volume, hospital stay, fusion rate, visual analogue scale (VAS), and the Oswestry disability index were evaluated and compared between the 2 groups. The amount of intraoperative blood loss, postoperative drainage volume, and the duration of hospital stay in the Wiltse group were lower than those in the classical group (P < .05). There was no significant difference in Oswestry disability index score between the Wiltse group and the classical group at 3 months, 6 months, and 1 year after operation, but the visual analogue scale score in the Wiltse group was lower than that in the classical group at 6 months after surgery (P < .05). The Wiltse approach was comparable to the classical approach in terms of bone graft fusion time and fusion rate. The Wiltse approach for isthmus repair can achieve the same or even better clinical effect than the classical approach, and the Wiltse approach is more minimally invasive. Pedicle screw-hook internal fixation system combined with autogenous iliac bone graft via Wiltse approach is a feasible, safe, and effective minimally invasive surgical method for the repair of isthmic spondylolysis in young patients.

Staphylococcal enterotoxin C as a novel strategy for treating lumbar spondylolysis in adolescents: Description of technique.

Lumbar spondylolysis is one of the most common causes of low back pain and primarily affects children and adolescents. Traditional posterior lumbar fixation and interbody fusion surgery has always been the most effective method to treat spondylolysis. However, traditional surgical management has limitations of large trauma, complex operation, high cost, postoperative biomechanical deterioration, and resulting complications. In order to avoid the trauma and complications of surgical treatment, and reduce the cost of treatment. Based on the successful clinical experience of using staphylococcal enterotoxin C (SEC) to treat nonunion after a limb fracture, we identified a minimally invasive method to effectively treat lumbar spondylolysis. A novel minimally invasive therapeutic approach is presented herein of an SEC injection guided by C-arm fluoroscopy to treat lumbar spondylolysis. We describe a novel technique applied in a patient with lumbar spondylolysis, who showed significantly improved low back pain symptoms and a computed tomography scan, including osseous fusion of the bilateral isthmus at L4 after SEC therapy. This is the first reported case description of using an SEC injection to treat lumbar spondylolysis with a successful clinical outcome.

Endoscopic-assisted fusion for lumbar pars fracture repair in an adolescent patient.

Minimally invasive repair of pars defects can be achieved via means of cannulation followed by tubular decortication. Given these injuries typically occur in pediatric and adolescent patients, minimal disruption to surrounding tissue during the repair is ideal. The use of an endoscopic approach to assist with repair and fusion across the pars defect is a novel consideration in the pediatric demographic, and in this case report we highlight our experience and rationale for this in treating a 14-year-old male athlete with lumbar 5 pars fracture. Radiographic evidence of bony fusion was seen by the third postoperative month. In this case report we demonstrate the invasive nature of this repair can be minimized further than current convention with successful radiographic and clinical outcomes.

Clinical Outcomes of Isobar TTL System with Isthmic Bone Grafting and Pedicle Screw-Vertebral Plate Hook with Direct Repair of Defect for Lumbar Spondylolysis: A Matched-Pair Case Control Study.

OBJECTIVE: Although direct isthmic repair, such as PSVPH, did not affect the mobility of the fixed segment and adjacent segment, it has a relatively low rate of isthmic fusion compared with conventional fusion. The Isobar TTL dynamic internal fixation system has been widely used in clinical practice and has achieved satisfactory clinical results. However, the use of the Isobar TTL system in combination with direct isthmic repair for lumbar spondylolysis has rarely been reported. The aim of this study was to compare the clinical and radiologic outcomes between patients who underwent Isobar TTL system and PSVPH with direct repair of defect for lumbar spondylolysis. METHODS: Stepwise propensity score matching (PSM) for age and sex were performed to keep comparable clinical data between groups in this retrospective and matched-pair case control study. A total of 50 patients diagnosed with lumbar spondylolysis underwent surgical implantation of the Isobar TTL group (n = 25) or PSVPH group (n = 25) from June 2009 to June 2016. Clinical outcomes were assessed using the Oswestry disability index (ODI), and visual analog score (VAS). Radiographic evaluations included range of motion (ROM) and the disc heights of stabilized segment and adjacent segment, adjacent segment degeneration (ASD) and bony fusion. Three-dimensional reconstruction of lumbar CT scan was obtained to evaluate bone fusion of the isthmic at final follow-up. The independent Student's t test and chi-square test were applied to compare the differences between groups. RESULTS: A total of 25 patients from TTL group were matched to 25 patients in PSVPH group for age, sex, body mass index (BMI), defect side, spondylolisthesis meyerding, and follow-up duration. The intervertebral space height (IH) of stabilized segment at postoperative 1 week and final follow-up in the TTL group was higher than those in the PSVPH group, respectively (P = 0.030; P = 0.013). The ROM of stabilized segment at final follow-up in the TTL group was significantly lower than that in the PSVPH group (P < 0.001). The bony fusion rate at the final follow-up was 88.0% (22/25 cages) in the TTL group and 80.0% (20/25 cages) in the PSVPH group. The ODI score at final follow-up in the TTL group was significantly lower than that in the PSVPH group (P = 0.007). CONCLUSION: Overall, our data suggest that the Isobar TTL system outcomes are comparable to those in the PSVPH, with a similar high bony fusion rate as PSVPH, especially its wider indications as a new surgery.

Percutaneous Direct Pars Repair in Young Athletes.

BACKGROUND: Lumbar pars defects are common in adolescent athletes and are often due to recurrent axial loading and traumatic stressors. OBJECTIVE: To present an updated case series of young athletes who underwent percutaneous direct pars repair after failure of conservative management. METHODS: A single-center, nonrandomized, retrospective observation study of athletes who were referred for minimally invasive direct pars repair after failure of at least 6 months of conservative management was performed. Summary demographic information, clinical features of presentation, perioperative and intraoperative radiographic imaging, and visual analog scale back pain scores were collected and analyzed. RESULTS: A total of 21 patients were included (mean age [± SD] 17.47 ± 3.02 years, range 14-25 years), 6 of whom were female (29%). All patients presented with bilateral pars fractures, with L5 being the most frequent level involved (n = 13). The average follow-up time was 31.52 ± 9.38 months (range 3-110 months). The visual analog scale score for back pain was significantly reduced from 7.62 ± 1.83 preoperatively to 0.28 ± 0.56 at the final postoperative examination (P < .01). Fusion was noted in 20 of the 21 patients on final follow-up (95%). CONCLUSION: Percutaneous direct pars repair is a safe and effective means in treating young adolescents who have failed conservative management. The advantages included minimized muscle and soft tissue dissection, reduced blood loss, and early mobilization and recovery. In young athletes who desire return to high-level physical activity, this surgical technique is of particular benefit and should be considered in this patient population.

Bilateral spondylolysis of inferior articular processes of lumbar vertebra with no active sports history: Case report and review of literature.

Lumbar spondylosis, though mostly occurs at pars interarticularis of vertebrae, it rarely occurs at articular processes. Like the ones in pars interarticularis, articular process fractures are stress fractures that are usually seen in people participated in active sprts activity. Most of the time, nonoperative treatment is adequate. When conservative treatment fails, removal of fragments accomplishes pain relief. In this report, we present a case with bilateral spondylolysis of inferior articular processes at 3rd lumbar vertebrae and discuss with regards to the literature.

A Technical Pitfall of Decompression with Direct Repair of a Ragged Edge Using the Smiley-Face Rod Method†:†A Case Report.

The smiley-face rod method has been reported to be a successful technique for reducing slippage and repairing pars defects in lumbar spondylolisthesis. However, we encountered a patient who developed right L5 radiculopathy with muscle weakness after use of the smiley-face rod method. The patient was a 19-year-old female judo player who had undergone direct repair surgery using the smiley-face rod method for terminal-stage lumbar spondylolysis. Postoperatively, she developed paresthesia on the lateral side of the right thigh with weakness of the right tibialis anterior and extensor hallucis longus. Computed tomography showed right foraminal stenosis at L5 with the floating lamina shifted ventrally and apophyseal ring fracture. In this case, the spondylolysis fracture angle differed between the left and right sides, with the fracture line on the right side running more sagittally. As a result, the floating lamina was shifted ventrally on the right side by compression and the right L5 intervertebral foraminal space was narrowed due to the ventral shift in the floating lamina and the apophyseal ring bone fragment. The shape of the fracture line should be examined carefully before surgery to avoid this technical pitfall. J. Med. Invest. 69 : 308-311, August, 2022.

Does Direct Surgical Repair Benefit Pars Interarticularis Fracture? A Systematic Review and Meta-analysis.

BACKGROUND: Promising results have been shown in previous studies from direct pars interarticularis repair. These include Scott wiring, Buck repair, pedicle screw repair, and Morscher techniques. In addition, several minimally invasive techniques have been reported to show high union rates, low rates of implant failure and wound complications, shorter length of stay, a lower postoperative pain score with faster recovery, and minimal blood loss. OBJECTIVES: To compare the evidence on techniques for direct pars interarticularis repair. STUDY DESIGN: Systematic review and meta-analysis. SETTING: Review article. METHODS: We conducted a comprehensive search of databases to identify studies assessing outcomes of direct pars interarticularis defect repair. Two authors independently screened electronic search results, performed study selection, and extracted data for meta-analysis. Sensitivity and subgroup analyses were performed to assess risk of bias. RESULTS: Forty studies were included in the final analysis. Union rate was higher in the pedicle screw repair group (effect size [ES] 95%; 95% CI, 86% to 100%), followed by the Buck repair group (ES 93%; 95% CI, 86% to 98%), Scott wiring (ES 85%; 95% CI, 63% to 99%), and Morscher method group (ES 63%; 95% CI, 2% to 100%). Positive functional outcome was higher for the Morscher method (ES 91%; 95% CI, 86% to 96%), followed by the Buck repair group (ES 85%; 95% CI, 68% to 97%), pedicle screw repair (ES 84%; 95% CI, 59% to 99%) and Scott repair group (ES 80%; 95% CI, 60% to 95%). Complication rates were highest among the Scott repair group (ES 12%; 95% CI, 4% to 22%) and Morscher method group (ES 12%; 95% CI, 0% to 34%). LIMITATIONS: Heterogeneity of the included studies were noted. However, we performed sensitivity analyses from the available data to address this issue. CONCLUSION: Our results indicate that pedicle screw repair and Buck repair may be associated with a higher union rate and lower complication rates compared to the Scott repair and Morscher method. Ultimately, the choice of technique should be based on the surgeon's preference and experience.

Diagnosis and Management of Spondylolysis and Spondylolisthesis in Children.

¼: Spondylolysis is defined as a defect of the pars interarticularis, and spondylolisthesis is defined as a slippage of a vertebra relative to the immediately caudal vertebra. ¼: Most cases of spondylolysis and low-grade spondylolisthesis can be treated nonoperatively. Depending on a patient's age, nonoperative treatment may include a thoracolumbosacral orthosis (TLSO), physical therapy, and activity modification. Bracing and physical therapy have been found to be more effective than activity modification alone. ¼: Patients with dysplastic spondylolisthesis are at higher risk for progression and should be monitored with serial radiographs every 6 to 9 months. ¼: Operative management is recommended for symptomatic patients with failure of at least 6 months of nonoperative management or patients with high-grade spondylolisthesis. ¼: Surgical techniques include pars defect repair, reduction, and fusion, which may include posterior-only, anterior-only, or circumferential fusion.

Clinical Results of Restoration of Pars Interarticularis Defect in Adults with Percutaneous Intralaminar Screw Fixation.

OBJECTIVE: This study aims to report the clinical outcomes associated with the percutaneous intralaminar screw repair performed for pars defects in adults. METHODS: Adult patients who got their lumbar L5 spondylolysis repaired via modified Buck's procedure between 2017 and 2020 were retrospectively evaluated. The preoperative and postoperative clinical outcomes at 1, 3, 6, and 12 months were evaluated for patients with and without fusion using the visual analog scale, Oswestry Disability Index, and the Short-Form Health Survey 36 (SF-36). At 12 months, the fusion status of all the patients was assessed using bilateral direct X-rays. RESULTS: Thirty patients with spondylolysis were identified (11 men and 19 women). All patients had bilateral L5 pars defects, and at 12 months, the fusion rate was 60% (18/30). There was no difference between the fusion and nonfusion groups in terms of their visual analog scale, Oswestry Disability Index, and SF-36 physical component summary and SF-36 mental component summary scores (P > 0.05). Within-group comparisons of the 2 groups revealed significant changes at follow-up (P < 0.05). CONCLUSIONS: Minimally invasive repair of lumbar spondylolysis with percutaneous intralaminar screw fixation restores the motion segment and can provide early resumption of physical activity with minimal muscle damage, smaller skin incision, and less soft tissue dissection.

Management of lumbar spondylolysis in the adolescent athlete: a review of over 200 cases.

BACKGROUND: Spondylolysis is a defect of the pars interarticularis of vertebrae, most commonly seen at L5 and L4. The etiology of spondylolysis and isthmic spondylolisthesis is generally considered to be a result of repetitive mechanical stress to the weak portion of the vertebrae. A higher incidence of spondylolysis is observed in young athletes. Symptomatic spondylolysis can be successfully treated conservatively, but there is currently a limited consensus on treatment modalities and a lack of large-scale clinical trials. PURPOSE: The purpose of the present study was to investigate the optimal treatment algorithm for symptomatic spondylolysis in adolescent athletes and evaluate the functional outcomes of those undergoing the nonoperative treatment. STUDY DESIGN: A retrospective review. PATIENT SAMPLE: Two hundred one adolescent patients ranging from age 10 to 19 involved in athletics OUTCOME MEASURES: Injury characteristics (age, mechanism, time), sports played, bone stimulator use, bony healing at 3 months on computed tomography (CT) scans, return to sports, corticosteroid injection use. METHODS: Two hundred one adolescent athlete patients (62 females and 139 males) diagnosed with spondylolysis between 2007 and 2019 were retrospectively reviewed. Diagnosis was based on plain radiography followed by magnetic resonance imaging. All patients were treated conservatively with cessation of sports activity, thoracolumbosacral orthosis, and external bone stimulator for three months after diagnosis. CT scans were obtained for the 3-month follow-up visits to assess bony healing. Subsequently the patients received 6 weeks of rehabilitation focused on core strengthening. Symptomatic patients after the treatment were referred for steroid injections and continued with the rehabilitation protocol. RESULTS: The most common age of injury was 15 years old, following a strong normal distribution. The most commonly played sport was football, followed by baseball/softball. The primary mechanism of injury was weight training closely followed by a football injury. The first quarter of the calendar year had the highest incidence of injuries with the most injuries occurring in March and the least occurring in December. One hundred fifty-two athletes reported using bone stimulators as prescribed, and these patients showed a significantly higher rate of bony healing on follow-up CT scans than those who did not use bone stimulators. One hundred ninety-seven patients (98%) returned to sports or similar level of activities. Thirty-seven patients (18%) received facet or epidural steroid injections due to continued pain and one patient underwent a surgical procedure. Follow-up CT scans showed 49.8% bony healing. CONCLUSIONS: Conservative treatment of spondylolysis in adolescent athletes with cessation of sports, thoracolumbosacral orthosis, and bone stimulator followed by rehabilitation was associated with excellent outcomes in terms of return to sports.

Risk factor analysis of disc and facet joint degeneration after intersegmental pedicle screw fixation for lumbar spondylolysis.

BACKGROUND: Patients who do not respond to conservative treatment of the isthmus are often treated with surgery. We used direct repair plus intersegment pedicle screw fixation for the treatment of lumbar spondylolysis. The aim of this observational study was to assess the effects of this technique and evaluate various risk factors potentially predicting the probability of disc and facet joint degeneration after instrumentation. METHODS: The study included 54 male L5 spondylolysis patients who underwent pars repair and intersegment fixation using pedicle screws. Bony union was evaluated using reconstruction images of computed tomography. Radiographic changes, including disc height, vertebral slip, facet joint and disc degeneration in the grade of adjacent and fixed segments, were determined from before to final follow-up. Logistic regression analysis was performed to identify factors associated with the incidence of disc and facet joint degeneration. RESULTS: Bony union was achieved in all cases. Logistic regression analysis revealed that instrumentation durations of greater than 15.5 months and 21.0 months were significant risk factors for the incidence of L4/5 and L5S1 facet degeneration, respectively. CONCLUSIONS: Intersegmental pedicle screw fixation provides good surgical outcomes and good isthmic bony union rates in patients with lumbar spondylolysis. The duration of fixation was confirmed as a risk factor for facet joint degeneration. Once bony union is achieved, instrument removal should be recommended.

Direct Pars Repair with Cannulated Screws in Adults: A Case Series and Systematic Literature Review.

OBJECTIVE: Lumbar spondylolysis occurs in 5%-8% of adults. This study aimed to report clinical and radiographic outcomes of direct pars repair in adults with lumbar spondylolysis. METHODS: We conducted a retrospective review of all patients treated for lumbar spondylolysis via open fracture reduction and direct pars repair with cannulated screws using a lag technique. Demographics, clinical presentation, perioperative and intraoperative imaging, and postoperative data were collected. We subsequently performed a systematic review to describe radiographic and clinical outcomes following direct pars repair. RESULTS: Three patients were identified (mean age 40.3 years; range, 21-72 years; 2 male). All patients had bilateral L5 pars fractures treated via open, direct repair with cannulated screws. There were no intraoperative complications. Length of stay was <24 hours for each patient. All patients reported back/radicular symptom relief and returned to full-time manual labor by latest follow-up. Noncontrast lumbar computed tomography performed 14-20 months postoperatively confirmed that all patients had good bilateral screw placement without fracture. Two patients (21 and 28 years old at surgery) had evidence of fusion across fracture sites, while 1 patient exhibited radiolucency around the screws and no progression of spondylolisthesis. Additionally, we reviewed 8210 articles and included 15 in a systematic review of direct pars repair. Fusion rates were 67%-100%, with improved average Oswestry Disability Index and visual analog scale back pain scores by latest follow-up. CONCLUSIONS: Lumbar spondylolysis treatment with open fracture reduction and direct pars repair with cannulated screws in adults is safe and may result in mechanical back/radicular pain relief, even in the absence of radiographic fusion.

Comparison of two internal fixation systems in lumbar spondylolysis by finite element methods.

BACKGROUND AND PURPOSE: Internal fixation surgeries are currently the most effective treatments for lumbar spondylolysis, but the optimal fixation method is still on debate. This study was designed to compare the biomechanical characteristics of two fixation methods for lumbar spondylolysis, the pedicle screw-U shape rod (PSUSR) internal fixation system, and the pedicle screw-vertebral plate hook (PSVPH) internal fixation system, through three-dimensional finite element analysis, expecting to provide clinical guidance. METHODS: Four finite element models (A, B, C, D) of L4-S1 vertebral body of a female patient were reconstructed by CT image segmentation. (A: intact model. B: spondylolysis model. C: spondylolysis model with PSUSR internal fixation. D: spondylolysis model with PSVPH internal fixation). Six physiological motion states were simulated by applying 500N concentrated force and 10Nm moment load to four models. The biomechanical advantages of the two internal fixation systems were evaluated by comparing the range of motion (ROM), maximum stress, maximum strain, and maximum displacement of the models. RESULTS: Compared to model B, the ROM decreased by 35.7%-57.1% in model C and 39.7%-64.8% in model D. The maximum displacements of model C and D both decreased. The maximum stresses in both vertebral and the internal fixation system are greater in model C than those in model D. The maximum stress and strain reduction of L5-S1 intervertebral disc in model D was greater than that in model C. Model D restores the articular cartilage stresses to the normal levels of model A. The maximum stress and maximum displacement of the bone graft in model C are greater than those in model D. CONCLUSIONS: The PSVPH internal fixation system has better biomechanical properties than PSUSR internal fixation system in several mechanical comparisons. Experimental results suggest that PSVPH internal fixation system can effectively treat lumbar spondylolysis while preserving segmental mobility, and can be the treatment of choice.