Screw Breakage Research Articles

Does Lumbar Interbody Fusion Modality Affect the Occurrence of Complications in an Osteoporotic Spine Under Whole-Body Vibration? A Finite Element Study

To evaluate the effects of 3 lumbar interbody fusion techniques on the occurrence of complications in an osteoporotic spine under whole-body vibration. A previously developed and validated nonlinear finite element model of L1-S1was modified to develop anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), and transforaminal lumbar interbody fusion (TLIF) models with osteoporosis. In each model, the lower surface of the sacrum was absolutely fixed, a follower load of 400N was applied through the axis of the lumbar spine, and an axial sinusoidal vertical load of ±40N (5 Hz) was imposed on the superior surface of L1, to perform a transient dynamic analysis. The maximal values of intradiscal pressure, shear stress on annulus substance, disc bulge, facet joint stress, and screw and rod stress, along with their dynamic response curves, were collected. Among these 3 models, the TLIF model generated the greatest screw and rod stress, and the PLIF model generated the greatest cage-bone interface stress. At the L3-L4 level, compared with the other 2 models, the maximal values and dynamic response curves of intradiscal pressure, shear stress of annulus ground substance, and disc bulge were all lower in the ALIF model. However, the facet contact stress at the adjacent segment in the ALIF model was higher than that in the other 2 models. In an osteoporotic spine under whole-body vibration, TLIF has the highest risk of screw and rod breakage, PLIF has the highest risk of cage subsidence, and ALIF has the lowest risk of upper adjacent disc degeneration, but the highest risk of adjacent facet joint degeneration.

Transarticular Fixation Using Bioabsorptive Screws for Cervical Lesions.

Transarticular screw fixation is a method for posterior cervical fixation. It is ergonomic because neither connectors nor rods are needed. Biomechanical studies have shown that its fixation force is not inferior to that of lateral mass screws. More information is needed on the surgical outcome of procedures using bioabsorptive screws. We investigated the long-term surgical and radiological outcomes of posterior cervical decompression and fusion using bioabsorptive screws for transarticular fixation.Of 10 patients who underwent cervical spine transarticular fixation using bioabsorptive screws, nine presented with cervical degenerative spondylosis and one with a traumatic cervical spine injury. The mean postoperative follow-up period was 57.1 months. Transarticular screw fixation was successful in all 10 patients; no intraoperative complications were encountered. Bilateral screw breakage was discovered in a patient with cervical spine instability and associated dystonia due to cerebral palsy; there was no symptom deterioration, facet joint breakage, or instability exacerbation. Facet fusion was obtained in the nine other patients. At the patients' last visit, their clinical symptoms were significantly improved. Whole cervical spine alignment (-4.21 ± 7.2 to -5.2 ± 8.7) and the fused segment angle (mean, -0.1 ± 9.9 to -1.2 ± 13.7) did not significantly worsen postoperatively (mean: -0.1 ± 9.9 to -1.2 ± 13.7). Transarticular fixation using bioabsorptive screws is safe and associated with good long-term outcomes. In patients with exacerbation of local instability after posterior decompression, additional transarticular fixation using bioabsorbable screws is a treatment option.

Hybrid pedicle screw and modified cortical bone trajectory technique in transforaminal lumbar interbody fusion at L4-L5 segment: finite element analysis

BackgroundInvestigate the biomechanical properties of the hybrid fixation technique with bilateral pedicle screw (BPS) and bilateral modified cortical bone trajectory screw (BMCS) in L4-L5 transforaminal lumbar interbody fusion (TLIF).Methods Three finite element (FE) models of the L1-S1 lumbar spine were established according to the three human cadaveric lumbar specimens. BPS-BMCS (BPS at L4 and BMCS at L5), BMCS-BPS (BMCS at L4 and BPS at L5), BPS-BPS (BPS at L4 and L5), and BMCS-BMCS (BMCS at L4 and L5) were implanted into the L4-L5 segment of each FE model. The range of motion (ROM) of the L4-L5 segment, von Mises stress of the fixation, intervertebral cage, and rod were compared under a 400-N compressive load with 7.5 Nm moments in flexion, extension, bending, and rotation.Results BPS-BMCS technique has the lowest ROM in extension and rotation, and BMCS-BMCS technique has the lowest ROM in flexion and lateral bending. The BMCS-BMCS technique showed maximal cage stress in flexion and lateral bending, and the BPS-BPS technique in extension and rotation. Compared to the BPS-BPS and BMCS-BMCS technique, BPS-BMCS technique presented a lower risk of screw breakage and BMCS-BPS technique presented a lower risk of rod breakage.Conclusion The results of this study support that the use of the BPS-BMCS and BMCS-BPS techniques in TLIF surgery for offering the superior stability and a lower risk of cage subsidence and instrument-related complication.

The late-term results in our patients operated for lumbar spine fractures

Aim: The current study aimed to evaluate the late-term results of patients operated for lumbar spine fractures in our clinic. 
 Material and Method: 134 patients from January 2012 to January 2020 were treated with “short-segment pedicle instrumentation” for lumbar fractures in our neurosurgery department. Patients with a burst fracture of a single lumbar vertebra were included. The final sample consisted of 67 patients who were followed up over the years with radiographs before and after surgery and CT scans at the final follow-up. 
 Results: The results showed that 60% of the patients were rated as Denis P1, 35% as P2, and 5% as P3. Screw breakage was observed in seven patients, and 67 patients underwent revision surgery. Furthermore, the fractured vertebral body’s height was improved at the final follow-up stage, and an increase was witnessed from the preoperative figure of 16.4 mm to 25.8 at the final follow-up. At the final follow-up, the average Cobb angle was -11.6° preoperatively, and 6.3° after the operation and the correction loss was 12.1° which was severe in the middle part of the vertebra. By the final follow-up, disc spaces were narrowed below and above the fractured vertebra, and no correlation was found between clinical outcomes and adjacent disc degeneration. 
 Conclusion: We concluded that short-segment pedicle instrumentation produced satisfactory long-term results for lumbar fractures. To achieve adequate outcomes, correct management of complications and evaluation of various factors must be focused on.

Radiological outcomes of PEEK rods in patients with lumbar degenerative diseases: A minimum 5-year follow-up.

To determine the long-term radiological outcomes of PEEK rods in patients with lumbar degenerative diseases. Radiological outcomes of cohort cases with lumbar degenerative diseases following PEEK rods were retrospectively studied. Disc height index (DHI) and range of motion (ROM) were measured by x-rays. The CT scans and reconstruction were used to determine screw breakage, rods fracture, screw loosening and intervertebral bony fusion status. The MRI scans were used to evaluate the changes of intervertebral discs at the non-fusion segments and adjacent segments in terms of Pfirrmann Classification. A total of 40 patients completed the mean of 74.8 ± 9.6 months follow-up, with 32 patients undergoing hybrid surgery and 8 patients undergoing non-fusion surgery. The mean DHI changed from preoperative 0.34 to 0.36 at the final follow-up and the ROM declined from 8.8° preoperatively to 3.2° at the final visit, however, both had no statistical differences. Of the 40 levels underwent non-fusion procedure, 9 levels showed disc rehydration with 7 patients from Grade 4 to Grade 3 and 2 patients from Grade 3 to Grade 2. The other 30 cases did not show distinctive change. No screw loosening or rods breakage were detected during the follow-up periods. PEEK rods have obvious protective effects on degenerated intervertebral disc of non-fusion segments and the incidence of complications related to internal fixation is low. PEEK rods pedicle screw system is safe and effective in the treatment of lumbar degenerative diseases.

Short-term Complications of Open Latarjet Procedure for Recurrent Anterior Shoulder Dislocation.

Anterior dislocation is the most common type of shoulder dislocation, and even after appropriate treatment, recurrence after a primary traumatic anterior dislocation is highly frequent. Surgical options for treating recurrent anterior dislocations mainly include Bankart arthroscopic and Latarjet open surgery. We aimed to evaluate the outcomes and complication rates of the open Latarjet procedure in a series of patients with recurrent anterior shoulder dislocation. A total of 55 patients with recurrent anterior shoulder dislocation who underwent an open Latarjet procedure were included in this retrospective cohort study. Shoulder range of motion and postoperative complications, including neurapraxia, re-dislocation, hematoma, infection, dehiscence, implant failure, and pain, were evaluated. The mean age of the patients was 27.7 ± 6.5 years . The mean time interval after the first dislocation was 3.4 ± 2.7 years . The mean preoperative and postoperative forward flexion (P = 0.200), abduction (P = 0.200), external rotation (P = 0.066), and internal rotation (P = 0.310) were not significantly different. Postoperative complications included 1 case of postoperative musculocutaneous nerve neurapraxia, 1 case of re- dislocation, 1 case of wound dehiscence, and 2 cases of screw breakage. Postoperative pain was also recorded in 11 (20%) patients that were either in the form of occasional night pain (n = 6) or activity-dependent pain (n = 5). Open Latarjet procedure is an efficient procedure for the treatment of recurrent anterior shoulder dislocation. However, its rate of complications remains relatively high, and surgeons must consider this drawback in their decision-making and address patients' expectations.

Removal or retention of minimally invasive screws in thoracolumbar fractures? Systematic review and case–control study

BackgroundThere is uncertainty regarding delayed removal versus retention of minimally invasive screws following percutaneous fixation for thoracolumbar fractures. We conducted a systematic review and case–control study to test the hypothesis that delayed metalwork removal following percutaneous fixation for thoracolumbar fractures improves outcome.MethodsA systematic review was performed in accordance with the PRISMA guidelines. Our case–control study retrospectively evaluated 55 consecutive patients with thoracolumbar fractures who underwent percutaneous fixation in a single unit: 19 with metalwork retained (controls) and 36 with metalwork removed. Outcomes were the Oswestry Disability Index (ODI), a supplemental questionnaire, and complications.ResultsThe systematic review evaluated nine articles. Back pain was reduced in most patients after metalwork removal. One study found no difference in the ODI after versus before metalwork removal, whereas three studies reported significant improvement. Six studies noted no significant alterations in radiological markers of stability after metalwork removal. Mean complication rate was 1.7% (0–6.7). Complications were superficial wound infection, screw breakage at the time of removal, pull-out screw, and a broken rod. In the case–control study, both groups were well matched. For metalwork removal, mean operative time was 69.5 min (range 30–120) and length of stay was 1.3 days (0–4). After metalwork removal, 24 (68.6%) patients felt better, 10 (28.6%) the same and one felt worse. Two patients had superficial hematomas, one had a superficial wound infection, and none required re-operation. Metalwork removal was a significant predictor of return to work or baseline household duties (odds ratio 5.0 [1.4–18.9]). The ODI was not different between groups.ConclusionsThe findings of both the systematic review and our case–control study suggest that removal of metalwork following percutaneous fixation of thoracolumbar fractures is safe and is associated with improved outcome in most patients.

Biomechanical comparative analysis of conventional pedicle screws and cortical bone trajectory fixation in the lumbar spine: An in vitro and finite element study.

Numerous screw fixation systems have evolved in clinical practice as a result of advances in screw insertion technology. Currently, pedicle screw (PS) fixation technology is recognized as the gold standard of posterior lumbar fusion, but it can also have some negative complications, such as screw loosening, pullout, and breakage. To address these concerns, cortical bone trajectory (CBT) has been proposed and gradually developed. However, it is still unclear whether cortical bone trajectory can achieve similar mechanical stability to pedicle screw and whether the combination of pedicle screw + cortical bone trajectory fixation can provide a suitable mechanical environment in the intervertebral space. The present study aimed to investigate the biomechanical responses of the lumbar spine with pedicle screw and cortical bone trajectory fixation. Accordingly, finite element analysis (FEA) and in vitro specimen biomechanical experiment (IVE) were performed to analyze the stiffness, range of motion (ROM), and stress distribution of the lumbar spine with various combinations of pedicle screw and cortical bone trajectory screws under single-segment and dual-segment fixation. The results show that dual-segment fixation and hybrid screw placement can provide greater stiffness, which is beneficial for maintaining the biomechanical stability of the spine. Meanwhile, each segment's range of motion is reduced after fusion, and the loss of adjacent segments' range of motion is more obvious with longer fusion segments, thereby leading to adjacent-segment disease (ASD). Long-segment internal fixation can equalize total spinal stresses. Additionally, cortical bone trajectory screws perform better in terms of the rotation resistance of fusion segments, while pedicle screw screws perform better in terms of flexion-extension resistance, as well as lateral bending. Moreover, the maximum screw stress of L4 cortical bone trajectory/L5 pedicle screw is the highest, followed by L45 cortical bone trajectory. This biomechanical analysis can accordingly provide inspiration for the choice of intervertebral fusion strategy.

Use of calcaneal plates in the treatment of posterior pelvic ring injuries and displaced iliac blade fractures- A case series

IntroductionThe operative fixation of pelvic ring injuries and associated acetabulum fractures presents a challenging scenario to most of the orthopaedic trauma surgeons. Current development of anatomically contoured reconstruction (ACR) plates gained popularity in fixing complex pelvic ring fractures. This study was done to assess the functional and radiological outcomes using of lateral wall stainless steel (LWSS) calcaneal plates in posterior pelvic ring injuries and displaced iliac blade fractures. Materials and methodsRetrospectively selected eight cases of pelvic ring injuries planned for fixing posterior pelvic instability and iliac blade fractures using LWSS plates. Mean follow-up was 18 months (Range 12–26 months). ResultsAverage time for radiological bony union achieved in 18 weeks (Range 13–22). Seven patients returned to their normal work. Average Majeed score was 60 (Range 50–68). Mean duration of surgery was 160 min (Range 120–200). ConclusionThis technique can be routinely used as supplementary fixation for posterior pelvic ring instability and iliac blade fractures. LWSS calcaneal plates showed no screw breakage or implant failure. Further this technique was cost effective in developing countries with limited resources.

Micro-locking plate external fixation for the treatment of proximal phalanx comminuted fractures

To explore clinical efficacy of external placement of micro-locking plate combined with small incision reduction in treating proximal phalanx comminuted fractures. From January 2018 to December 2019, 17 patients with proximal phalanx comminuted fractures were treated with micro-locking plate combined with small incision open reduction, including 13 males and 4 females, aged from 16 to 64 years old with an average of (37.2±20.1) years old. Two patients were accompanied by soft tissue extrusion and opening injuries, which were treated with fixed treatment after the first-stage emergency debridement. Curative effect was evaluated according to total active flexion scale (TAFS) of American Hand Surgery Association at 6 months after operation;and fracture healing, nailing, local soft tissue healing, complications were observed. All patients were followed up from 6 to 12 months with an avaerge of(9.3±3.6) months. Two patients occurred delayed union, 1 occurred local skin necrosis and was treated with the second-stage skin grafting to repair wound surface. No external screw breakage or infection was reported, skin soft tissue healed favorably and reached bony union, the union time from 12 to 24 weeks with an average of (15.7±2.1) weeks. According to TAFS standard, 9 patients got excellent result, 5 good and 3 poor at 6 months after operation. External micro-locking plate combined with small incision reduction in treating proximal phalanx comminuted fracture, which has advantages of good condition of skin and soft tissue, simple operation, early functional exercise, good range of motion of interphalanx joint, and function score of recovery period is high.

Factors associated with hardware failure after lateral thoracolumbar fusions – A ten year case series

ObjectiveThoracolumbar lateral interbody fusions (tLLIF) are one tool in the spine surgeon’s toolbox to indirectly decompress neuroforamina while also improving segmental lordosis in a biomechanically distinct manner from posterior fusions. When part of a concomitant posterior construct, hardware failure (HF), sometimes requiring revision surgery, can occur. We sought to study the relationship between tLLIF and HF. MethodsWe conducted a retrospective study on consecutive patents who underwent tLLIF at a single academic center between January 2012 and December 2021 by seven unique neurosurgeons. Patients were excluded if they had no posterior instrumentation within their construct or if they had less than six months of follow-up. Hardware failure was defined as screw breakage or rod fracture seen on postoperative imaging. Results232 patients were identified; 6 (2.6 %) developed HF throughout a mean follow-up of 1182 days (range =748–1647 days). Adjacent segment disease was the most common pathology addressed (75 patients (32.3 %)). The amount of posterior instrumentation both in the surgery in question and in the total construct were significantly higher in the HF cohort (4.33 ± 1.52 levels, 5.83 ± 3.36 levels) versus the non-HF cohort (2.08 ± 0.296 levels, p = 0.014; 2.86 ± 0.316 levels, p = 0.003, respectively). The number of interbody devices added in the index surgery and in the entire construct were both significantly higher in the HF cohort (3.33 ± 0.666 interbody devices, 3.33 ± 0.666 devices) than in the non-HF cohort (1.88 ± 0.152 interbody devices, p = 0.002; 2.31 ± 0.158 devices, p = 0.036, respectively). Higher amounts of lateral levels of fusion approached significance for association with HF (HF: 2.67 ± 0.844 levels, no HF: 1.73 ± 1.26 levels, p = 0.076). On multivariate analysis, only the number of interbody devices added in the index surgery was predictive of HF (Odds ratio=2.3, 95 % confidence interval=1.25–4.23, p = 0.007). ConclusionGreater levels of posterior fusion, and greater numbers of interbody devices in an index surgery and in a construct as a whole, were associated with higher rates of HF in our cohort of patients with tLLIF. Greater numbers of lateral segments fused in this population may also be related to HF.

Clinical study of a new biodegradable magnesium internal fixation screw in treatment of osteonecrosis of the femoral head

To investigate the safety and efficacy of a new biodegradable magnesium internal fixation screw for vascularized iliac bone flap grafting in treatment of osteonecrosis of the femoral head (ONFH). Patients with ONFH admitted between July 2020 and February 2021 were selected as the research objects, and 20 patients (20 hips) met the selection criteria and were included in the study. The patients were divided into two groups ( n=10) by central random method. The iliac bone flap was fixed with a new biodegradable magnesium internal fixation screw in the trial group, and the iliac bone flap was wedged directly in the control group. There was no significant difference ( P>0.05) in gender, age, and side, type, Association Research Circulation Osseous (ARCO) stage, and disease duration of ONFH between the two groups. The operation time and intraoperative blood loss of the two groups were recorded. Laboratory tests were performed at each time point before and after operation, including white blood cell (WBC), electrolytes (K, Ca, P, Mg), blood urea nitrogen (BUN), serum creatinine (Scr), glomerular filtration rate (eGFR), lymphocyte ratio (CD4/CD8), immunoglobulin G (IgG), IgM, alanine transaminase (ALT), aspartate aminotransferase (AST). After operation, Harris score was used to evaluate the hip joint function. CT of the hip joint and X-ray films in anteroposterior and frog positions of the pelvis were used to review the iliac bone flap position, fusion, and screw biodegradation in the trial group. The vital signs of the two groups were stable, the incisions healed by first intention, and no adverse events occurred after operation. One patient in the control group refused to return to the hospital for follow-up at 3 months after operation, and 1 patient in the trial group refused to return to the hospital for follow-up at 1 year after operation. The rest of the patients completed the follow-up at 2 weeks, 3 months, 6 months, and 1 year after operation. Laboratory tests showed that there was no significant difference in WBC, electrolytes (K, Ca, P, Mg), BUN, Scr, eGFR, CD4/CD8, IgG, IgM, ALT, and AST between the two groups at each time point before and after operation ( P>0.05). The operation time and intraoperative blood loss of the trial group were significantly less than those of the control group ( P<0.05). The Harris scores of the two groups at 1 year significantly increased when compared with the values before operation and at 6 months after operation ( P<0.05). There was no significant difference in Harris score between the two groups at each time point ( P>0.05). Postoperative CT of hip joint and X-ray films of pelvis showed that the iliac bone flap reached osseous fusion with the fenestration of the head and neck junction of femoral head in the two groups at 1 year after operation, and no loosening or shedding of iliac bone flap was observed during follow-up. In the trial group, there were signs of dissolution and absorption of the new biodegradable magnesium internal fixation screws after operation, and the diameter of the screws gradually decreased ( P<0.05); no screw breakage or detachment occurred during follow-up. In the treatment of ONFH with vascularized iliac bone flap grafting, the new biodegradable magnesium internal fixation screws can fix the iliac bone flap firmly. Compared with the traditional iliac bone flap wedging directly, it has a shorter operation time, less intraoperative blood loss, and can obtain similar joint function.

Are The Lateral Wall Reduction And Ideal Tip-Apex Distance Important In Reverse Oblique And Transverse Intertrochanteric Femoral Fractures (31-A3) Treated With Gamma Nail?

Purpose: Reverse oblique and transverse intertrochanteric femoral fractures (31A3 AO/OTA classification) have their own mechanical and anatomical properties. The aim of our study is to verify whether the reduction of the lateral femoral wall and ideal tip-apex distance are important predictive factors in the future of these fractures treated by gamma nails in terms of healing and complication rates. Methods: The radiological and clinical outcomes of 35 fractures of this type treated by short and long gamma nail from June 2014 to April 2021 were retrospectively reviewed. The elements considered were the quality of the lateral femoral wall reduction, the tip-apex distance (TAD), the lag screw position and overall quality reduction using the Baumgaertner criteria. Union, nonunion, cutout, screw sliding, nail or screw breakage were also radiographically evaluated during follow-up. Results: The union rate was 97%. A significant association was not observed between the state of reduction of the lateral wall and the three types of complications considered (cutout: p=0.31; sliding screw: p=1.00; varus displacement: p=0.30), and the linear regression model obtained indicates that in subjects with a non-reduction of the lateral wall, the consolidation time is increased on average by approximately 3 months (β= 2.99; 95%CI: 1.79-4.20, p&lt;0.001). No significant association was found between TAD and complications (cut-out: p=1.00; sliding screw: p=1.00; varus displacement: p=0.13). Conclusion: Anatomic reduction of the lateral wall and an ideal TAD ≤ 25mm might not be as significant for 31A3 fractures treated with gamma nails. Acceptable reduction of the lateral wall and stable internal fixation are sufficient elements to achieve fracture healing and functional recovery.

CFR-PEEK Pedicle Screw Instrumentation for Spinal Neoplasms: A Single Center Experience on Safety and Efficacy

(1) Background: Surgery for spinal metastases has gained a decisive role in modern oncological treatment. Recently, carbon-fiber-reinforced (CFR) polyethyl-ether-ether-ketone (PEEK) pedicle screw systems were introduced, reducing artifacts on imaging and showing less perturbation effects on photon radiation. Preliminary clinical experience with CFR-PEEK implants for spinal metastases exists. The aim of this monocentric study is to report on the safety and efficacy of CFR-PEEK pedicle screw systems for spinal neoplasms in a large cohort of consecutive patients. (2) Methods: We retrospectively analyzed prospectively the collected data of consecutive patients being operated on from 1 August 2015 to 31 October 2021 using a CFR-PEEK pedicle screw system for posterior stabilization because of spinal metastases or primary bone tumors of the spine. (3) Results: We included 321 patients of a mean age of 65 ± 13 years. On average, 5 ± 2 levels were instrumented. Anterior reconstruction was performed in 121 (37.7%) patients. Intraoperative complications were documented in 30 (9.3%) patients. Revision surgery for postoperative complications was necessary in 55 (17.1%) patients. Implant-related complications, such as intraoperative screw breakage (3.4%) and screw loosening (2.2%), were rare. (4) Conclusions: CFR-PEEK is a safe and efficient alternative to titanium for oncological spinal instrumentation, with low complication and revision rates in routine use and with the advantage of its radiolucency.

Efficacy of Far Cortical Locking Screws in Treating Distal Tibia Fractures in Comparison With That of Standard Locking Screws

There are no clinical studies about treatment of distal tibia fractures using far cortical locking (FCL) screws, even though it has been shown to be superior to standard locking screws in biomechanical studies. We compared the efficacy of FCL screws to that of traditional locking screws. Twenty-five distal tibia fractures were treated with minimally invasive plate osteosynthesis using traditional locking screws, whereas 20 were treated using FCL screws. We retrospectively compared time taken for callus formation and radiographic bone union between 2 groups. The effect of age, sex, diabetes, and smoking history on bone healing was analyzed. Complications were also noted. As a result, there was no significant difference in age (p = .292), sex (p=1.0), diabetes (p=1.0), or smoking history (p = .704) between 2 groups. Time to callus formation was 77.5 days in the FCL group, and 96 days in the traditional group (p = .023). Average time to bone union was 134.8 days, and 163.1 days in the FCL group and the traditional group, respectively (p = .017). There was one case of screw loosening in the FCL group, and one case of screw breakage in the traditional group. This study suggests that FCL screws promote quicker healing of distal tibia fractures than traditional locking screws.

Four-Corner Arthrodesis with a Dorsal Locking PEEK Plate: A Retrospective Case Series.

Background Four-corner arthrodesis (4CA) can be performed with a variety of methods. To our knowledge, fewer than 125 cases of 4CA with a locking polyether ether ketone (PEEK) plate have been reported, necessitating further study. Purpose The purpose of this study was to evaluate the radiographic union rate and clinical outcomes in a series of patients who received 4CA with a locking PEEK plate. Methods We re-examined 39 wrists in 37 patients at a mean follow-up of 50 months (median: 52 months, range: 6-128). Patients completed the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), Patient-Rated Wrist Evaluation (PRWE), and participated in measurements of grip strength and range of motion. Anteroposterior, lateral, and oblique radiographs of the operative wrist were examined for union, screw breakage and/or loosening, and lunate change. Results The mean QuickDASH score was 24.4 and the mean PRWE score was 26.5. Mean grip strength was 29.2 kg or 84% of the nonoperative hand. Mean flexion, extension, radial deviation, and ulnar deviation were : 37.2, 28.9, 14.1, and 17.4 degrees, respectively. Eighty-seven percent of wrists achieved union; 8% had nonunion; and5% had indeterminate union. There were seven cases of screw breakage and seven cases of screw loosening (as defined by lucency or bony resorption surrounding screws). Twenty-three percent of wrists required reoperation (four total wrist arthrodesis and five reoperations for other reasons). Conclusion 4CA with a locking PEEK plate has clinical and radiographic outcomes similar to other methods. We observed a high rate of hardware complications. It is unclear whether this implant offers a clear advantage over other methods of fixation used in 4CA. Type of Study/Level of Evidence Level IV, therapeutic study.

Management of Feline Femoral, Tibial and Humeral Fractures Using a 3.5 mm Titanium Interlocking Nail.

Our objectives were to report complications associated with stabilization of long-bone fractures in cats using a 3.5-mm titanium interlocking nail and to examine the influences of signalment, fracture type and fixation evaluations on the occurrence of complications. Retrospective clinical study. Medical and radiographic records of cats with long-bone fractures treated with an interlocking nail were reviewed. Data included age, sex, weight, cause of the fracture, fractured bone(s) and fracture type. Complications were classified as minor and major complications. Fisher's exact tests and logistic regression analysis were used to test whether certain variables of signalment and interlocking nail configuration had an effect on the occurrence of complications. Sixty-seven fractures of 67 cats were examined in this study. Forty-eight femora, sixteen tibiae and three humeri were included. Complications occurred in 11/67 fractures. Major complications occurred in 8/67 fractures and included screw breakage (n = 3), nail breakage (n = 2), nail bending (n = 1), screw loosening (n = 1), non-union (n = 1). Statistical analysis showed a significant difference between fracture types and the occurrence of major complications (p = 0.02). In conclusion, use of this commercially available standard 3.5-mm titanium interlocking nail for stabilization of comminuted and oblique humeral, femoral and tibial fractures in cats is feasible.

P18. Characterization of sacropelvic fixation using novel porous fusion/fixation implants in combination with thoracolumbar instrumentation

<h3>BACKGROUND CONTEXT</h3> Sacropelvic fixation is often used at the distal end of long constructs in adult deformity surgery in order to provide biomechanical support to the base of the constructs, with the aim of reducing complications such as pseudarthrosis of the L5-S1 joint and hardware failure or loosening. <h3>PURPOSE</h3> The objective of this study was to investigate configurations in which a porous fusion/fixation (PFF) implant was employed to enhance sacropelvic fixation. <h3>STUDY DESIGN/SETTING</h3> Finite element study. <h3>OUTCOME MEASURES</h3> The outputs analyzed in this comparison were: (a) range of motion (ROM) of L5-S1 and sacroiliac joint (SIJ) with respect to PED; (b) the maximal von Mises stresses in S1 pedicle screws; (c) the maximal von Mises stresses in either the S2 alar-iliac screws or in PFF implants in a S2 alar-iliac trajectory; (d) the maximal stresses in the posterior rods between the pedicle screws in L5 and S1 (ie, lumbosacral junction). <h3>METHODS</h3> Three instrumented T10-pelvis models were created from an intact validated model: (1) pedicle screws and rods in T10-S1, and PFF implants inserted bilaterally in a S2 alar-iliac trajectory (PFFI); (2) pedicle screws and rods in T10-S1, PFF implants inserted bilaterally in a S2 alar-iliac trajectory, and triangular implants inserted bilaterally above the PFFI in a sacro-alar-iliac trajectory (PFFI-IFSAI); and (3) pedicle screws and rods in T10-S1, PFF implants inserted bilaterally in a S2 alar-iliac trajectory, and PFF implants in a SAI trajectory stacked cephalad to those in the S2 alar-iliac position (2-PFFI). These configurations were compared against two baseline models: (1) pedicle screws and rods in T10-S1 (PED); and (2) pedicle screws and rods in T10-S1, and S2 alar-iliac screws (S2AI). All the instrumented models were used to simulate pure moments of 7.5 Nm to the upper endplate of the T10 vertebra in flexion, extension, left and right lateral bending, and left and right axial rotation. Double leg stance was simulated by fixing both acetabula of the models. <h3>RESULTS</h3> Sacropelvic fixation demonstrated a greater decrease in ROM of both L5-S1 and SIJ with respect PED. S2AI and PFFI had similar results in terms of L5-S1 and SIJ motion. PFFI-IFSAI did not affect the ROM between L5 and S1 but did reduce that of the SIJ. 2-PFFI further decreased L5-S1 motion and demonstrated a behavior similar to PFFI – IFSAI in terms of SIJ motion. S2AI fixation showed a slight increase of the stresses on S1 pedicle screws and on implants in the S2AI position with respect to PFFI. PFFI-IFSAI slightly decreased the stresses in S1 pedicle screws and on implants in the S2AI position with respect to PFFI. 2-PFFI significantly decreased the stresses on these implants (28-62 MPa for S1 pedicle screws and up to 66% for implants in the S2AI position) with respect to other configurations. In the posterior rods, the von Mises stresses were found to be highest when PFF implants were used with respect to S2AI, though all stresses were below those found in S1 pedicle screws in PED. <h3>CONCLUSIONS</h3> This study confirmed that sacropelvic fixation is able to reduce ROM at L5S1 and lower instrumentation stresses suggesting a reduced risk of pseudarthrosis at the joint and screw breakage, respectively. Moreover, outcomes suggest that PFF implants increase stability of the L5-S1 and SIJ, and reduce the risk of screw breakage. Clinical evaluation should be performed to confirm the applicability of results to patient outcomes. <h3>FDA DEVICE/DRUG STATUS</h3> iFuse Implant System (SI-BONE, Santa Clara, CA) (Approved for this indication), iFuse Bedrock Granite Implant System (SI-BONE, Santa Clara, CA) (Investigational/Not Approved).

P121. Carbon fiber reinforced PEEK implants for spine tumors: a single center experience

<h3>BACKGROUND CONTEXT</h3> Titanium is the most common material used to manufacture spinal implants; however, its metallic properties are associated with imaging artifacts on CT and MRI scans which impede treatment planning and clinical follow among oncologic patients. Carbon fiber-reinforced Polyether ether ketone (CFR-PEEK) based spinal implants are an alternative to titanium, offering less image artifact as its titanium counterparts while maintaining similar biomechanical and biocompatibility properties. Its use in the management of spinal tumors has been reported, however the perceived advantages related to improved imaging quality, radiation treatment planning, and detection of tumor recurrence have not been fully assessed. <h3>PURPOSE</h3> We report our experience at the MD Anderson Cancer Center with the use of CFR-PEEK implants in the treatment of oncological patients. <h3>STUDY DESIGN/SETTING</h3> Retrospective single-arm single-center study. <h3>PATIENT SAMPLE</h3> All consecutive patients from September 2019 to July 2021 who were operated for spine conditions and had carbon fiber-reinforced implants. <h3>METHODS</h3> We performed a retrospective review of the medical records and imaging studies of patients treated with CFR-PEEK implants from September 2019 to July 2021. Histology type, tumor location, construct features, time of follow up, type of adjuvant radiation, recurrences, overall survival and hardware related complications were recorded. <h3>RESULTS</h3> Seventy-one consecutive patients were assessed (20 primary tumors, 47 metastases, 4 others). The median time for followup was 5.4 months (Q1 1.13, Q3 11.9, IQR 10.77). Of those 6 patients received conventional external beam radiotherapy, 31 received spinal stereotactic radiosurgery with a median time to radiation of 35 days among primary tumors and 30 days among metastatic cases. A total of 4 patients with primary tumors presented recurrence at a median time of 4.7 months (N=4, Q1 2.7, Q3 7, IQR 4.3) and 7 patients with metastatic disease presented recurrence at a median time of 3.4 months (N=6, Q1 2.0, Q3 5.1, IQR 3.1). Hardware complications were observed in a total of 5 cases (7.04%) and included screw loosening, intraoperative screw breakage and loosened set screw. Imaging review demonstrated significant reduction in imaging artifact and enhanced detection of local recurrence when compared to similar cases operated with standard titanium spinal instrumentation. <h3>CONCLUSIONS</h3> Carbon fiber reinforced PEEK implants provided safe and effective spinal stabilization for patients with both primary and metastatic tumors while integrating into postoperative imaging and radiation planning. The associated reduction in imaging artifacts enhanced postoperative radiation planning and the ability to detect local recurrence. <h3>FDA DEVICE/DRUG STATUS</h3> Carbon fiber thoracolumbar screws and rods (Icotec AG, Altstätten, Switzerland) (Approved for this indication)

The lesser trochanter “Sling fixation technique” in proximal intramedullary nailing of unstable intertrochanteric fractures: A polymer-based cerclage wiring

IntroductionLesser trochanter (LT) fixation to restore the continuity of the posteromedial fragment using a cerclage wire has been reported to provide a more stable reduction in the treatment of unstable femoral neck fractures with LT involvement. However, LT fixation is not commonly performed due to the complications associated with the traditional monofilament cerclage metal wires. In this study, we investigate the clinical and radiological outcomes of a new technique for LT fixation in conjunction with Intramedullary (IM) fixation with nail and screws when compared to isolated IM fixation. The Sling Fixation Technique involves a new wiring technique and the use of a polymer-based cerclage cable characterized by iso-elastic properties that is hypothesized to provide better clinical and radiographic outcomes. Patients and methodsThis prospective observational study included 30 patients who underwent proximal IM nailing from July 2019 to April 2020. Thirty consecutive patients (30) were assigned to 2 different treatment groups. Fifteen (15) patients were treated with the IM Nailing and Sling Fixation Technique and 15 with IM nailing only. Patients were comparable for demographic features, fracture pattern, age, gender and associated medical comorbidities. Clinical outcomes were analyzed in terms of time needed to achieve complete weight bearing, Harris hip score (HHS), Barthel Index (BI) and Radiographic Union Scale for Hip (RUSH). The follow-up period was one year. ResultsTime for fracture healing and to achieve weight-bearing in the “Sling” group were shown to be significantly shorter than in the IM group. The Sling group showed furthermore better HHS, BI and RUSH scores when compared to the IM group at 1, 3, 6, and 12 months from the surgery. No complications such as wiring breakage, cut-outs, breakage or pullout of the fixation screws were observed; one case of heterotrophic ossification was reported. ConclusionIn cases of unstable intertrochanteric fractures of the proximal femur with lesser trochanter involvement, the Sling fixation technique using an isoelastic polymer-based wire showed superior results in terms of stability and consequently better clinical and radiographic outcomes than IM nailing only.