Traditional Screw Research Articles

Sustentacular screw placement with guidance during ORIF of calcaneal fracture: an anatomical specimen study

BackgroundThe sustentacular screw is essential to maintain the stability of the subtalar joint during ORIF (open reduction with internal fixation) of calcaneal fractures. Currently, the screw is still inserted based on surgeons’ anatomical experiences and nearly 40% of screws are misplaced from the sustentaculum. Previous studies demonstrated some methods of sustentacular screw placement through anatomical measurements or navigation system. The purposes of this study are to design an assistant guidance device that can effectively improve the accuracy of sustentacular screw placement and to compare the accuracy of this technique with traditional screw placement based on experience.MethodsA customized guidance device is designed, aiming to improve the accuracy of sustentacular screw placement. Twenty cadaveric specimens are used in the present study. Ten specimens are allocated into the guidance-assisted group, and others are included in the traditional screw insertion group. A total of 40 sustentacular screw placements are performed in each group. Fluoroscopic images are obtained after each screw placement. Only the screw that captures the sustentaculum both on the lateral and axial X-ray views was regarded as an accurate placement.ResultsThe accuracy rate in the guidance-assisted group is 87.5% (35 out of 40 times of insertions) while in the traditional screw insertion group, the accuracy rate is 65% (26 out of 40 times of insertions). A significant difference is found between the two groups (p = 0.018).ConclusionsThe guidance-assisted technique is a convenient approach that can effectively improve the accuracy of sustentacular screw placement during the ORIF of calcaneal fractures. This study provides a novel technique that significantly facilitates sustentacular screw insertion and improves its accuracy.

Clinical outcomes Tight rope versus traditional screw fixation for the treatment of injury of distal tibiofibular syndesmosis in ankle fracture

To compare the clinical effectiveness for Tight rope fixation and traditional screw fixation in treating injury of distal tibiofibular syndesmosis in ankle fractures. A retrospective study was carried out in patients with injury of distal syndesmosis in ankle fractures who received 2 surgical operations(observation group: 33 cases with Tight rope fixation; control group: 35 cases with traditional screw fixation) from May 2014 to February 2016. There were 18 males and 15 females, aged from 20 to 55 years old with an average of(32.4±5.2) years old in observation group; of them, 19 cases were caused by traffic accidents, 10 by sprain, and 4 by falling; according to Lauge-Hansen typing of ankle fractures, all of the 33 cases were pronation-extorsion fracture, 12 cases were III degree and 21 cases were IV degree. There were 19 males and 16 females, aged from 21 to 54 years old with an average of (32.8±5.5) years old in control group; of them, 20 cases were caused by traffic accidents, 11 by sprain, 4 by falling; according to Lauge-Hansen typing of ankle fractures, 1 case was with pronation-outreach, 34 cases with pronation-extorsion, 13 cases were III degree and 21 cases were IV degree. Fixation time and complication were compared between two groups and AOFAS scores were observed in two groups 3 and 6 months after the operation as well as final follow-up. All the patients were followed up from 8 to 24 months with an average of (16.3±3.8) months. Fixation time of observation group and control group were (10.1±2.8) min and (9.5±2.3) min(P>0.05) respectively. There were significant difference in complication and AOFAS of 3, 6 months postoperatively between two groups(P<0.05). In observation group, 23 case got excellent result, 9 good, 1 fair; and in control group, 18 cases got excellent results, 12 good, 5 fair; there was no significant difference between two groups(P>0.05). Tight rope for the treatment of injury of distal tibiofibular ligament union in ankle fractures has advantages such as easier techniques, earlier weight-bearing exercises without risk of screw breakage, thus is a new choice. However, it is still necessary to further study the angle, direction and tension of button steel plate.

Mobility and Constraint Analysis of Interconnected Hybrid Flexure Systems Via Screw Algebra and Graph Theory

This paper introduces a general method for analyzing flexure systems of any configuration, including those that cannot be broken into parallel and serial subsystems. Such flexure systems are called interconnected hybrid flexure systems because they possess limbs with intermediate bodies that are connected by flexure systems or elements. Specifically, the method introduced utilizes screw algebra and graph theory to help designers determine the freedom spaces (i.e., the geometric shapes that represent all the ways a body is permitted to move) for all the bodies joined together by compliant flexure elements within interconnected hybrid flexure systems (i.e., perform mobility analysis of general flexure systems). This method also allows designers to determine (i) whether such systems are under-constrained or not and (ii) whether such systems are over-constrained or exactly constrained (i.e., perform constraint analysis of general flexure systems). Although many flexure-based precision motion stages, compliant mechanisms, and microarchitectured materials possess topologies that are highly interconnected, the theory for performing the mobility and constraint analysis of such interconnected flexure systems using traditional screw theory does not currently exist. The theory introduced here lays the foundation for an automated tool that can rapidly generate the freedom spaces of every rigid body within a general flexure system without having to perform traditional computationally expensive finite element analysis. Case studies are provided to demonstrate the utility of the proposed theory.

Utilization of second sacral alar-iliac technique for lumbosacral fixation in patients with tuberculosis of lumbar and sacrum spine

Objective To evaluate the feasibility and clinical outcomes of second sacral alar-iliac (S2AI) technique utilized in patients with tuberculosis of Lumbosacral spine. Methods 24 cases (15 male, 9 female, aged 36-73 years old, average 47.1 years) of tuberculosis of Lumbosacral spine were collected for surgery using spinal and pelvic fixation system (S2AI or IS) between January 2014 and May 2016. Lumbosacral pain and restricted movement were noticed in all cases, of which 9 cases with radiating pain of lower limb and 7 cases with intermittent claudication, 2 cases with saddle anesthesia. Formal anti-tuberculosis medicine treatment was given for at least 2-3 weeks before operation. All patients with lumbosacropelvic fixation were compared by recording with ESR/CRP, preoperatively, postoperatively and the last following-up. The clinical effect oswestry disability index (ODI) score, visual analogue scale (VAS), ambulatory status, SF-36 scale and related complications of 2 groups were also compared. Results The average follow-up period was average 23.4 months in the two groups. The results show that operative time, blood loss, drainage time, hospitalization days and fusion time were not statistically significant; the recording of ESR, CRP, ODI, VAS scores and ambulatory status scores between S2AI and IS groups showed no significantly different, preoperatively, postoperatively and the last following-up. Comparisons within each group were improved at postoperatively and the last following-up related to preoperatively; The difference of the SF-36 scales in each group was statistically significant between preoperatively and the last following-up; There was no statistically difference in recurrence, sinus, pseudarthrosis between two groups, but The S2AI technique was associated with lower rates of symptomatic screw prominence compared to the IS technique. Conclusion Application of S2AI screw technique in the treatment of lumbosacral tuberculosis can achieve solid fixation and satisfactory clinical effect, and reduce the complications of traditional IS screws, which is an alternative method of posterior structure reconstruction of lumbosacral tuberculosis. Key words: Tuberculosis; Spinal diseases; Sacroiliac joint; Treatment outcome

High-density Electroencephalographic Acquisition in a Rodent Model Using Low-cost and Open-source Resources

Advanced electroencephalographic analysis techniques requiring high spatial resolution, including electrical source imaging and measures of network connectivity, are applicable to an expanding variety of questions in neuroscience. Performing these kinds of analyses in a rodent model requires higher electrode density than traditional screw electrodes can accomplish. While higher-density electroencephalographic montages for rodents exist, they are of limited availability to most researchers, are not robust enough for repeated experiments over an extended period of time, or are limited to use in anesthetized rodents.1-3 A proposed low-cost method for constructing a durable, high-count, transcranial electrode array, consisting of bilaterally implantable headpieces is investigated as a means to perform advanced electroencephalogram analyses in mice or rats. Procedures for headpiece fabrication and surgical implantation necessary to produce high signal to noise, low-impedance electroencephalographic and electromyographic signals are presented. While the methodology is useful in both rats and mice, this manuscript focuses on the more challenging implementation for the smaller mouse skull. Freely moving mice are only tethered to cables via a common adapter during recording. One version of this electrode system that includes 26 electroencephalographic channels and 4 electromyographic channels is described below.

High-density Electroencephalographic Acquisition in a Rodent Model Using Low-cost and Open-source Resources.

Advanced electroencephalographic analysis techniques requiring high spatial resolution, including electrical source imaging and measures of network connectivity, are applicable to an expanding variety of questions in neuroscience. Performing these kinds of analyses in a rodent model requires higher electrode density than traditional screw electrodes can accomplish. While higher-density electroencephalographic montages for rodents exist, they are of limited availability to most researchers, are not robust enough for repeated experiments over an extended period of time, or are limited to use in anesthetized rodents.1-3 A proposed low-cost method for constructing a durable, high-count, transcranial electrode array, consisting of bilaterally implantable headpieces is investigated as a means to perform advanced electroencephalogram analyses in mice or rats.Procedures for headpiece fabrication and surgical implantation necessary to produce high signal to noise, low-impedance electroencephalographic and electromyographic signals are presented. While the methodology is useful in both rats and mice, this manuscript focuses on the more challenging implementation for the smaller mouse skull. Freely moving mice are only tethered to cables via a common adapter during recording. One version of this electrode system that includes 26 electroencephalographic channels and 4 electromyographic channels is described below.

Transmission Theory Analysis of a Dynamic Spiral Combination Lifting Mechanism

For traditional screw transmission with long stroke length, the long screw is difficult to be processed, and the original space is large. Aiming at making up the defects, a novel dynamic combination screw transmission mechanism is put forward. The transmission principle, the parameter of extension ratio and meshing conditions of bracing screw and connecting screw are introduced. The carrying capacity is analyzed by simulation. The results show that number of connecting screw is key of parameter ratio and can be adjusted, and the large carrying capacity and accurate positioning meet the special requirement of big trip overloading linear drive applications.

Clinical outcomes of endobutton versus traditional screw fixation for distal tibiofibular syndesmosis in ankle fractures

Objective To compare the clinical outcomes for endobutton versus traditional screw fixation of distal tibiofibular syndesmosis in ankle fractures. Methods Sixty-nine cases of ankle fractures accompanied with distal tibiofibular syndesmosis injury hospitalized between November 2012 and November 2014 were reviewed retrospectively. Thirty-two cases (19 males and 13 females) aged (38.1±15.3) years (range, 22-62 years) underwent syndesmosis stabilization with endobutton system (endobutton group), and mechanism of injury was sprain injury in 20 cases, traffic injury in 7 and high fall injury in 5. Another 37 cases (20 males and 17 females) aged(33.9±11.1)years (range, 22-65 years) were managed with traditional screw fixation (tradition group), and mechanism of injury was sprain injury in 22 cases, traffic injury in 8 and high fall injury in 7. According to the Lauge-Hansen classification, all had pronation external rotation ankle fractures. Operation time, manipulation angle, tibiofibular clear space (TBCS), tibiofibular overlap distance (TBOL), complications and final follow-up evaluation of American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score were recorded. Results Comparison of endobutton group to tradition group showed no significant differences in operation time [10 min(5-17 min) ∶9 min(4-15 min)], TBOL [(9.1±1.8)mm ∶(8.2±2.3)mm], TBCS [(3.7±0.6)mm ∶(3.6±0.9)mm], total complication rate [6.3% ∶13.5%] and AOFAS score [(89.1±18.5)points ∶(86.6±12.4) points] (P>0.05), but endobutton technique was associated with a larger manipulation angle [(45.8±16.7)° ∶(28.5±5.6)°] and earlier full weight bearing [(6.8±1.6)weeks ∶(10.9±2.7)weeks] than traditional screw fixation (P<0.05). Conclusion Endobutton technique has comparative effect with traditional screw fixation and has advantages such as low demand in fixation angle, early weight bearing and no need for removal of implant. Key words: Ankle injuries; Fracture fixation, internal; Distal tibiofibular syndesmosis

Radiographic Outcomes of Lisfranc Injuries Treated with a Suture Button Device

Category: Trauma Introduction/Purpose: Disagreement exists as to the optimal treatment of Lisfranc injuries of the midfoot. Some authors suggest that primary arthrodesis should be the treatment of choice, whereas others are proponents of open reduction and internal fixation (ORIF). There has been increased interest in using a suture button device in lieu of traditional screw fixation, which in general must be removed. Biomechanical studies comparing screw fixation with suture button devices have had conflicting results. The aim of this study was evaluate patients with Lisfranc injuries treated with a suture button radiographically over time. Methods: 43 patients with a Lisfranc injury treated surgically with a suture button device (Tightrope, Arthrex, Naples, FL) by two fellowship-trained orthopaedic foot and ankle surgeons were identified via a database query for the CPT code 28615 (open treatment of tarsometatarsal joint dislocation). The distances between the first and second metatarsal (M1-M2) and between the medial cuneiform and the second metatarsal (C1-M2) were measured on anterior-posterior (AP) radiographs using standardized, readily-identifiable landmarks. All measurements were performed independently by two musculoskeletal radiologists and were averaged. Accuracy of reduction was assessed by comparing measurements on weightbearing AP radiographs of the uninjured foot with the operatively-treated foot at 6 weeks postoperatively, also weightbearing. Maintenance of reduction over time was assessed by comparing measurements at 6 weeks postoperatively with measurements taken at the time of last follow-up. Measurements were also compared between the injured foot preoperatively and at time of last follow-up. T-tests using SPSS software were performed for statistical analysis in comparing the means of the different measurements. Results: Average radiographic follow-up was 35.8 weeks (6.1-178.9). Accuracy of reduction was less than 1 mm for both the M1- M2 and C1-M2 measurements when comparing the uninjured foot with the surgically-treated foot at 6 weeks postoperatively; this difference was significant in the C1-M2 measurement (difference = 0.77 mm, p=0.032), but not in the M1-M2 measurement (difference = 0.44 mm, p=0.190). There was no significant difference in measurements between 6 weeks postoperatively and at final follow-up (difference in M1-M2=0.22 mm, p=0.435; difference in C1-M2=0.27 mm, p=0.352). There was significant improvement in the measured distances of the injured foot preoperatively to that measured at final follow-up in the C1-M2 measurements (difference in C1-M2=-0.82mm, p=0.021), while the difference in the M1-M2 measurements approached significance (difference in M1-M2= -0.56 mm, p=0.067). Conclusion: To our knowledge, this is the first and largest series assessing radiographic outcomes of Lisfranc injuries in patients treated surgically with a suture button device. After open reduction of Lisfranc injuries, the suture-button device used in this study appears to adequately maintain this reduction over time while patients are weightbearing and back to full activity. We therefore conclude that based on our results, the suture button appears to present an effective alternative to traditional screw fixation for treatment of Lisfranc injuries.

A new method for achieving compression in hindfoot arthrodesis.

When performing hindfoot arthodeses, one goal of fixation is often to achieve compression across the joint. Traditional lag screws are applied eccentrically, providing compression more on the edge of the fusion. A new technique, using a post in one bone and a lag screw through the post to the other bone, may offer better compression across more of the joint. There are three parts to this study comparing a post-and-screw construct to traditional lag screws. Synthetic bone models, representative of the talonavicular joint, were created and assessed for biomechanical measures of compression. Next, the post-and-screw construct was tested in cadavers, under conditions representing early weight bearing after arthrodesis surgery. Finally, 18 patients who had a talonavicular fusion with a post-and-screw construct with one surgeon were compared to the previous 18 patients fixed with traditional screws. In the synthetic bone model, the post-and-screw construct brought the centre of compression closer to the centre of the joint, suggesting compression was less eccentric. Neither traditional screws nor the post-and-screw construct were sufficiently strong to resist early weight bearing forces in cadaver specimens. In the clinical comparison, four patients had a painful nonunion when fixed with traditional screws, compared to none in the post-and-screw construct. A post-and-screw construct spreads the forces of compression more uniformly across an arthrodesis, even when placed eccentrically. Although not all the biomechanical measures were superior, the post-and-screw construct achieved higher levels of successful fusion in patients. This technology may offer improved outcomes in some clinical scenarios and deserves further study. Level 3.

Pedicle screw fixation after vertebroplasty augmentation for osteoporotic thoracolumbar burst frac-tures

Objective To evaluate the curative effects of pedicle screw fixation after vertebroplasty augmentation using polymethylmethacrylate (PMMA) for osteoporotic thoracolumbar burst fractures in com-parison with traditional pedicle screw fixation. Methods From January 2007 to August 2013, 25 patients with osteoporotic thoracolumbar burst fracture underwent pedicle screw fixation after vertebroplasty augmenta-tion using PMMA (augmentation group) and 32 patients with the same disorder underwent pedicle screw fix-ation directly (direct group). The two groups were compared in terms of perioperative indexes, visual analogue scale (VAS), Oswestry disability index (ODI), complications, cobb angle of the fixed segment, loss of vertebral body height, and spinal canal encroachment. Results These patients were followed up for an average of 37.5 months. Compared with the direct group, the augmentation group had significantly more pe-rioperative bleeding, shorter hospitalization, shorter time for pain relief and shorter time for ambulatory re-covery (P<0.05). The VAS, ODI, cobb angle of the fixed segment and loss of vertebral body height at 7-day, 3-, 6-, 12-, and 24-month were significantly improved in all the patients (P<0.05). The aug-mentation group had significantly better improvements in VAS, ODI, cobb angle of the fixed segment and loss of vertebral body height at 7-day, 3-, 6-, 12-, 24-,and 36-month than the direct group (P<0.05). None of the patients had complications of neural injury, pulmonary thrombosis or poor wound healing. Five patients in the direct group had to receive a second operation to remove the instrumentation due to pedicle screw loosening and back pain. Conclusions In the treatment of osteoporotic thoracolumbar burst fractures, pedicle screw fix-ation after vertebroplasty augmentation using PMMA can lead to less pain, quicker and better recovery, better fracture reduction and kyphosis correction, and less loss correction than traditional open pedicle screw fixation. Key words: Spinal fractures; Osteoporosis; Vertebroplasty; Cement; Polymethyl-methacrylate

Effects on Subtalar Joint Stress Distribution After Cannulated Screw Insertion at Different Positions and Directions

We investigated the effects on subtalar joint stress distribution after cannulated screw insertion at different positions and directions. After establishing a 3-dimensional geometric model of a normal subtalar joint, we analyzed the most ideal cannulated screw insertion position and approach for subtalar joint stress distribution and compared the differences in loading stress, antirotary strength, and anti-inversion/eversion strength among lateral–medial antiparallel screw insertion, traditional screw insertion, and ideal cannulated screw insertion. The screw insertion approach allowing the most uniform subtalar joint loading stress distribution was lateral screw insertion near the border of the talar neck plus medial screw insertion close to the ankle joint. For stress distribution uniformity, antirotary strength, and anti-inversion/eversion strength, lateral–medial antiparallel screw insertion was superior to traditional double-screw insertion. Compared with ideal cannulated screw insertion, slightly poorer stress distribution uniformity and better antirotary strength and anti-inversion/eversion strength were observed for lateral–medial antiparallel screw insertion. Traditional single-screw insertion was better than double-screw insertion for stress distribution uniformity but worse for anti-rotary strength and anti-inversion/eversion strength. Lateral–medial antiparallel screw insertion was slightly worse for stress distribution uniformity than was ideal cannulated screw insertion but superior to traditional screw insertion. It was better than both ideal cannulated screw insertion and traditional screw insertion for anti-rotary strength and anti-inversion/eversion strength. Lateral–medial antiparallel screw insertion is an approach with simple localization, convenient operation, and good safety.

Sacral Screw Strain in a Long Posterior Spinal Fusion Construct with Sacral Alar-Iliac versus Iliac Fixation

Introduction Long instrumented posterior fusion constructs to the lumbosacral spine have a significant rate of pseudoarthrosis and S1 screw failure. With the increasing popularity of Sacral Alar-Iliac (S2AI) fixation with its purported advantages of (1) decreased implant profile and (2) obviating the need for a lateral offset connector, the biomechanical properties with respect to S1 screw strain remain unknown. We set out to compare the biomechanical effect of S2AI versus traditional iliac screw fixation on S1 screw strain. Methods Five fresh-frozen human cadaveric specimens were instrumented from L2–pelvis, maintaining all osteoligamentous structures, with bilateral titanium 6.0 × 40-mm pedicle screws and 5.5-mm cobalt–chromium rods. Bilateral S1 pedicles were instrumented with 8.0 × 50-mm screws that were centrally cored out and two uniaxial strain gauges inserted at 0 and 90 degrees. S2AI fixation and/or iliac fixation with 8.0 × 80-mm titanium pedicle screws was performed to evaluate the following four different constructs: (1) bilateral S1 screws (control); (2) bilateral S2AI; (3) bilateral iliac; (4) hybrid (S2AI with contralateral iliac). Bilateral S1 screw strain was measured (microstrain), and pure moment loads (12.0 Nm) were applied in axial rotation (AR), flexion extension (FE), and lateral bending (LB). One way repeated measure ANOVA was used to analyze the S1 screw strain data. Results Compared with S1 screws alone, both S2AI fixation and iliac fixation significantly reduced sacral screw strain in FE by 58 and 67%, respectively ( p &lt; 0.05), in AR by 35 and 41%, respectively ( p &lt; 0.05), while no significant difference in LB for either construct ( p &gt; 0.05). Hybrid constructs demonstrated a significant reduction in only FE, with reduction in screw strain by 56% for S2AI fixation and 59% for iliac fixation, with no difference in AR and LB moments. When S2AI fixation and iliac fixation were compared, there was no significant difference in screw strain for all bending moments ( p &gt; 0.05). Similarly, hybrid constructs demonstrated no side-to-side significant difference between S2AI fixation and iliac fixation for all bending moments ( p &gt; 0.05). Conclusion Both S2AI fixation and iliac fixation provide significant reduction in S1 sacral screw strain compared with sacral fixation alone. Bilateral S2AI fixation is a viable and biomechanically comparable to alternative traditional iliac fixation, and presents another option to achieve protection of the S1 sacral screws for long segment constructs to the pelvis.

Pedicle screw placement in the lumbar spine: effect of trajectory and screw design on acute biomechanical purchase.

OBJECT Low bone mineral density in patients undergoing lumbar spinal surgery with screws is an especially difficult challenge because poor bone quality can severely compromise the maximum achievable purchase of the screws. A relatively new technique, the cortical bone screw trajectory, utilizes a medialized trajectory in the caudocephalad direction to engage a greater amount of cortical bone within the pars interarticularis and pedicle. The objectives of this cadaveric biomechanical study were to 1) evaluate a cortical screw system and compare its mechanical performance to the traditional pedicle screw system; 2) determine differences in bone quality associated with the cortical screw trajectory versus the normal pedicle screw insertion technique; 3) determine the cortical wall breach rate with both the cortical and traditional screw trajectories; and 4) determine the performance of the traditional screw in the cortical screw trajectory. METHODS Fourteen fresh frozen human lumbar spine sections (L1-5) were used in this study (mean age 57 ± 19 years). The experimental plan involved drilling and tapping screw holes for 2 trajectories under navigation (a traditional pedicle screw and a cortical screw) in both high-and low-quality vertebrae, measuring the bone quality associated with these trajectories, placing screws in the trajectories, and evaluating the competence of the screw purchase via 2 mechanical tests (pullout and toggle). The 3 experimental variants were 1) traditional pedicle screws placed in the traditional pedicle screw trajectory, 2) traditional pedicle screws placed in the cortical screw trajectory, and 3) cortical screws placed in the cortical screw trajectory. RESULTS A statistically significant increase in bone quality was observed for the cortical trajectories with a cortical screw (42%; p < 0.001) and traditional pedicle screw (48%; p < 0.001) when compared to the traditional trajectory with a traditional pedicle screw within the high-quality bone group. These significant differences were also found in the lowquality bone cohort. All mechanical parameter comparisons (screw type and trajectory) between high-quality and lowquality samples were significant (p < 0.01), and these data were all linearly correlated (r ≥ 0.65) to bone mineral density. Not all mechanical parameters determined from pullout and toggle testing were statistically significant between the 3 screw/trajectory combinations. The incidence of cortical wall breach with the cortical or traditional pedicle screw trajectories was not significantly different. CONCLUSIONS The data demonstrated that the cortical trajectory provides denser bone that allows for utilization of smaller screws to obtain mechanical purchase that is equivalent to long pedicle screws placed in traditional pedicle screw trajectories for both normal- and low-quality bone. Overall, this biomechanical study in cadavers provides evidence that the cortical screw trajectory represents a good option to obtain fixation for the lumbar spine with low-quality bone.

Results of ACL reconstruction with tibial Retroscrew fixation: Comparison of clinical outcomes and tibial tunnel widening

Summary. ACL reconstruction with the RetroScrew™ shows superior clinical outcomes compared to historical Achilles allograft studies with antegrade screws. Addition of antegrade screw augmentation to retrograde fixation causes an increase in tibial tunnel widening. Introduction. In traditional antegrade screw fixation of Anterior cruciate ligament (ACL) soft tissue allografts, the screw is secured in the opposite direction of graft tension, potentially altering the appropriate tension on the graft. The RetroScrew (Arthrex) is a bioabsorbable screw placed in a retrograde fashion, potentially improving the tension of the graft by placing the screw in a proximal-to-distal direction. In addition, the RetroScrew theoretically decreases tibial tunnel widening by closing the aperture of the tibial tunnel, which prevents ingress of synovial fluid. Early tunnel expansion has been implicated due to excessive transverse and longitudinal graft motion. The clinical effects of tunnel expansion have yet to be fully understood. The purpose of this study is to assess the clinical results and tunnel width after ACL soft tissue fixation in the tibia with the RetroScrew. Methods. Fifty-nine patients who underwent ACL reconstruction performed by two surgeons using the RetroScrew device returned for postoperative evaluation at an average of 25 months following surgery with a minimum follow-up of 12 months. Clinical evaluation, SF-36, IKDC and KT-1000 scores were recorded, and knee radiographs were used to measure tibial tunnel widening. Thirty-five patients had backup antegrade screw fixation in conjunction with the RetroScrew, and 24 patients had RetroScrew fixation alone. The results were compared to two previously reported studies on ACL reconstruction with Achilles tendon allograft that used antegrade screws. Results. The average IKDC score was 87 (range: 44–100), with mean KT-1000 side-to-side difference of 1.2 mm (range: 0–5 mm). Tibial tunnel widening was 4.93 mm (SD 3.32) on AP radiographs and 4.40 mm (SD 2.72) on lateral radiographs greater than the native tunnel drilling. Patients with additional backup fixation had significantly more tunnel widening than patients without backup fixation (P < 0.05). There was one failure based on KT-1000 measurements. When compared to previous studies using ACL allografts, RetroScrew patients had statistically superior Lachman exams, KT-1000 side-to-side differences and decreased tibial tunnel widening (P < 0.05) when antegrade fixation was excluded. Conclusion. Patients who underwent Achilles allograft ACL reconstruction with the RetroScrew had improved clinical results compared to historical controls using antegrade fixation. Tibial tunnel widening was increased when using additional antegrade screw fixation, suggesting that the amount of bioabsorbable material within the tibial tunnel was related to the degree of tunnel widening.

Comparative Study of Tricortical versus Quadricortical Syndesmosis Fixation in Ankle Fractures

Objective: To assess short-term functional results in 2 types of syndesmotic fixation, comparing the traditional rigid quadricortical syndesmotic screw fixation with a more dynamic tricortical screw fixation. Method: PATIENTS: Thirty nine patients (Age group: 20 to 50 yr) with closed ankle fractures in which the syndesmosis was found to be unstable clinically, radiographic and confirmed intra operatively. INTERVENTION: The unstable syndesmoses were fixed with either one cortical screw through both tibial cortices (n = 18) QSF or two cortical screws engaging only 1 cortex of the tibia (n = 21) TSF. The quadricortical and the tricortical screws were removed only in the case of discomfort. However, all quadricortical screws were removed at 6 month follow up. Rehabilitation was the same in both groups. DESIGN: Prospective, randomized single blinded clinical study. SETTING: Department of orthopaedics and traumatology MGM Medical College & M Y Hospital Indore. And G.R. Medical College & Jayarogya Hospital, Gwalior. Results: At the end of three months mean OM score was 65.35 (55 to75) For TSF group as compared to59.58 (55 to65) in QSF group. Mean values were similar between the two groups with respect to pain, swelling, support, running and jumping. The overall difference noted in two groups was due to difference in Mean value for functional parameter like stair climbing, Squatting and activities of daily living. At six months there was no significant difference in any parameter of OM score. Hence the overall scores were with non-significant difference {TSF76.42 (70 To 80) and QSF72.42 (65 to 80). A three months DID was 12.07 (9to17) in TSF and 9.75 (6to13) in QSF with significant difference in two groups. At six months difference was non significant 4.75 for TSF and 4.42 for QSF Group. The one set of tricortical screws and two Quadricortical were removed in patients due to infection. Quadricortical group was re-operated in 3 (16.66 %) cases for screw removal in case of

Research on the Impacts of Screw Speed on All-Metal Screw Pump

Compared with traditional screw pump,all-metal screw pump have more advantages in the oil extraction. In this paper, all-metal single screw pump's geometric model was made by PROE software; then the dynamic mesh technique was applied to mesh the model and constraint condition was applied in the ANSYS-FLUENT software. 3D flow field was numerical analyzed In that software, the impacts of screw speed on volume flow and volumetric efficiency were concluded, the conclusion can offer some valuable guidances to the all-metal single screw pump's design.

Concentric double cables fixation as an alternative suspension method for the endoscopic forehead lift

Fixation of the elevated eyebrow is an important final step in endoscopic forehead lifting. One of the most common methods of fixation includes temporal fasciae sutures for the tail of the eyebrow, and mini-screws for the body of the eyebrow. The concentric cables fixation is an alternative method for elevation of both the tail and the body of the eyebrow. This technique is compared to temporal fasciae suture and mini-screws fixation. Thirty-one patients were included in this study. They were divided into two groups; group I included patients who underwent fixation using fascia sutures and mini-screws, while group II patients underwent concentric cables suspension. Traditional screw and suture technique elevated the eyebrow tail by 7.2, 6.7, 6.3, and 6.0 mm, while the concentric cables resulted in 7.6, 6.8, 6.5, and 6.3 mm elevation at 1, 3, 6, and 12 months postoperatively, respectively. The mean values of brow body elevation were 6.8, 6.4, 6.2, and 5.9 mm for group I, while the mean values of group II were 6, 5.4, 4.8, and 4.7 mm. The concentric cables technique showed a fewer complications rate compared to traditional fixation. The concentric cables fixation offers an alternative inexpensive method to suspend the tail, and to a lesser extent the body, of both eyebrows simultaneously with long-term stability. A fewer complications rate was documented compared to traditional temporal fasciae sutures and mini-screws fixation.

Effect of physiological loads on cortical and traditional pedicle screw fixation.

Human cadaveric biomechanical study. To determine the fixation strength of laterally directed, cortical pedicle screws under physiological loads. Lateral trajectory cortical pedicle screws have been described as a means of obtaining improved fixation while minimizing soft-tissue dissection during lumbar instrumentation. Biomechanical data have demonstrated equivalent strength in a quasi-static model; however, no biomechanical information is available comparing the fixation of cortical with traditional pedicle screws under cyclic physiological loads. Seventeen vertebral levels (T11-L5) underwent quantitative computed tomography. On 1 side, a laterally directed, cortical pedicle screw was inserted with a traditional, medially directed pedicle screw placed on the contralateral side. With the specimen constrained in a testing apparatus, each screw underwent cyclic craniocaudal toggling under incrementally increasing physiological loads until 2 mm of head displacement occurred. Next, uniaxial pullout of each toggled screw was performed. The number of craniocaudal toggle cycles and load (N) required to achieve pedicle screw movement as well as axial pullout resistance (N) were compared between the 2 techniques. The mean trabecular bone mineral density of the specimens was 202 K2HPO4 mg/cm. Cortical pedicle screws demonstrated significantly improved resistance to toggle testing, requiring 184 cycles to reach 2 mm of displacement compared with 102 cycles for the traditional pedicle screws (P=0.002). The force necessary to displace the screws was also significantly greater for the cortical versus the traditional screws (398 N vs. 300 N, P=0.004). There was no statistical difference in axial pullout strength between the previously toggled cortical and traditional pedicle screws (1722 N vs. 1741 N, P=0.837). Laterally directed cortical pedicle screws have superior resistance to craniocaudal toggling compared with traditional pedicle screws. N/A.

Endobutton elastic fixation for treatment of chronic syndesmotic instability

Objective To observe the clinical efficacy of Endobutton elastic fixation for treatment of chronic syndesmotic instability.Methods From January 2011 to January 2013,13 cases of chronic syndesmotic instability were treated by Endobutton elastic fixation in our department.They were 9 men and 4 women,aged from 32 to 46 years (average,37.5 years).The duration from injury to the operative treatment ranged from 3 to 6 months (average,3.8 months).After debridement of the medial gutter and the inferior tibiofibular space,2 Endobutton plates instead of traditional metal screws were used to stabilize the syndesmosis.Follow-up included clinical evaluation,X-ray and CT examination and image-based PACS 5.0 system measurement at 3 days,8 weeks and 6 months postoperation.The American Orthopaedic Foot and Ankle Society (AOFAS) score system was used for postoperative efficacy evaluation at 6 months postoperation.Results The patients were followed for 6 to 28 months,with an average of 16.0 months.All the malleolus fractures healed after an average of 11.5 weeks (from 10 to 17 weeks).No infection,faulty wound healing or phlebothrombosis happened in this group.Reduction of the syndesmosis was confirmed by X-ray and CT scan 3 days,8 weeks and 6 months after the surgery.The mean AOFAS score improved significantly from 49.5 points to 71.6 points,with 7 excellent cases,5 fine cases and one fair case.Conclusions Endobutton elastic fixation for chronic syndesmotic instability can preserve physiological fretting of the syndesmosis and avoid removal of hardware and further separation of the syndesmosis.It may also lead to fine functional recovery of the ankle,absence of significant complications and satisfactory outcomes in a short-term. Key words: Ankle joint; Fracture fixation, internal; Joint instability