Additional Screw Research Articles

Optimizing compression: Comparing eccentric plate holes and external tensioning devices

ObjectiveElimination of interfragmentary motion in fracture fixation using plates to impart compression and promote primary bone healing through absolute stability has been well described as a reliable and successful method to treat simple transverse and short oblique fracture morphologies. Our hypothesis is that dynamic compression plating augmented by external compression techniques would produce and maintain a significantly greater amount of compression than using the plate alone. MethodsSimple transverse diayphyseal fractures were simulated in nine 4th generation composite bone models. A load cell was placed within the transverse fracture osteotomy and stabilized and compressed using either eccentric screw placement in a dynamic compression plate alone or augmented with an opposite segment Verbrugge clamp or articulated tensioning device (ATD) compressing using a screw outside of the plate. Dynamic plate compression was evaluated independently and in conjunction with the external compression techniques. Statistical analyses were carried out using a linear mixed effects model and pairwise comparisons between conditions with a significance set at a P-value <0.05. ResultsBoth of the external compression techniques (Verbrugge and ATD) achieved significantly higher compression than the plate compression technique alone with 78% (P<0.001) and 134% (P<0.001) more compression respectively. The measured compression across the osteotomy after screw application and removal of external compression decreases by 17% for the Verbrugge device (P=0.215) and by 22%, after removal of the ATD device (P=0.038). For both techniques, adding additional screws in eccentric (load) position further increases compression. ConclusionPlate compression is a reliable method for inducing compression across transverse and short oblique fractures. Augmenting plate compression technique with external compression techniques (Verbrugge clamp or ATD) allows for a significantly greater compressive load to be achieved. Compression lost after removal of the external compression device indicates that the maximal compression attainable across a fracture may not be reliably maintained with standard dynamic compression plating techniques.

Fixed-Angle, Posteriorly Connected Anterior Cage Reconstruction Improves Stiffness and Decreases Cancellous Subsidence in a Spondylectomy Model.

An idealized biomechanical model. The aim of this study was to evaluate the biomechanical properties of a construct designed to minimize intervertebral cage subsidence and maximize stiffness. Reconstruction after vertebral resection typically involves posterior segmental fixation and anterior interbody support. However, poor bone density, adjuvant radiation, or the oncologic need for endplate resection make interbody device subsidence and resultant instrumentation failure a significant concern. An idealized thoracolumbar spondylectomy reconstruction model was constructed using titanium segmental instrumentation and Delrin plastic. In vivo mechanical stress was simulated on a custom multi-axis spine simulator. Rigid body position in space was measured using an optical motion-capture system. Cancellous subsidence was modeled using a 1 cm thick wafer of number 3 closed-cell Sawbones foam at one endplate. Ten foam specimens were tested in a control state consisting of posterior segmental fixation with a free interbody cage. Ten additional foam specimens were tested in the test state, with the Delrin interbody cage "connected" to the posterior rods using two additional pedicle screws placed into the cage. Foam indentation was quantified using a precision digital surface-mapping device, and subsidence volume calculated using geometric integration. The control group exhibited significantly greater foam indentation after cycling, with a mean subsidence volume of 1906 mm [95% confidence interval (95% CI) 1810-2001] than the connected cage group subsidence volume of 977 mm (95% CI 928-1026 mm; P < 0.001]. Construct stiffness was greater in the connected cage group (3.1 Nm/degree, 95% CI 3.1-3.2) than in the control group (2.3 Nm/degree, 95% CI 2.2-2.4; P < 0.001). In an idealized spondylectomy model, connecting the anterior column cage to the posterior instrumentation using additional pedicle screws results in a construct that is nearly 40% stiffer and exhibits 50% less cancellous subsidence compared with a traditional unconnected cage. N/A.

No effect of additional screw fixation of a cementless, all-polyethylene press-fit socket on migration, wear and clinical outcome: a 6.5 years randomized controlled radiostereometric analysis trial

No effect of additional screw fixation of a cementless, all-polyethylene press-fit socket on migration, wear and clinical outcome: a 6.5 years randomized controlled radiostereometric analysis trial

Comparison of the Mechanical Characteristics of a Universal Small Biplane Plating Technique Without Compression Screw and Single Anatomic Plate With Compression Screw

To better understand the mechanical characteristics of biplane locked plating in small bone fixation, the present study compared the stability under cyclic cantilever loading of a 2-plate locked biplane (BPP) construct without interfragmentary compression with that of a single-plate locked construct with an additional interfragmentary screw (SPS) using surrogate bone models simulating Lapidus arthrodesis. In static ultimate plantar bending, the BPP construct failed at significantly greater load than did the SPS construct (556.2 ± 37.1 N versus 241.6 ± 6.3 N, p = .007). For cyclic failure testing in plantar bending at a 180-N starting load, the BPP construct failed at a significantly greater number of cycles (158,322 ± 50,609 versus 13,718 ± 10,471 cycles) and failure load (242.5 ± 25.0 N versus 180.0 ± 0.0 N) than the SPS construct (p = .002). For cyclic failure testing in plantar bending at a 120-N starting load, the results were not significantly different between the BPP and SPS constructs for the number of cycles (207,646 ± 45,253 versus 159,334 ± 69,430) or failure load (205.0 ± 22.4 N versus 185.0 ± 33.5 N; p = .300). For cyclic testing with 90° offset loading (i.e., medial to lateral bending) at a 120-N starting load, all 5 BPP constructs (tension side) and 2 of the 5 SPS constructs reached 250,000 cycles without failure. Overall, the present study found the BPP construct to have superior or equivalent stability in multiplanar orientations of force application in both static and fatigue testing. Thus, the concept of biplane locked plating, using 2 low profile plates and unicortical screw insertion, shows promise in small bone fixation, because it provides consistent stability in multiplanar orientations, making it universally adaptable to many clinical situations.

Unilateral Stand-Alone Cage for the Treatment of Foraminal Stenosis in Patients with Degenerative Scoliosis. A Case Series of 20 Patients

Object: Neuroforaminal stenosis has been documented frequently in patients with degenerative lumbar scoliosis. Pedicle screw fixation with posterior lumbar interbody fusion is usually performed although a debate has been started on the need for unilateral or bilateral screws, or interbody fusion only. Trabecular Metal is a porous tantalum biomaterial with good osteoconductive properties, which may be suitable for unilateral interbody fusion aiming at enlargement of neuroforamen. Methods: From July 2011 until January 2013, 20 consecutive patients with degenerative scoliosis-related foraminal stenosis were treated with unilateral stand-alone Trabecular Metal cages (Zimmer TM 500) without additional pedicle screw fixation. All patients presented with leg pain, with or without low back pain. Patients underwent CT and MRI to confirm neuroforaminal stenosis on the concave side of the degenerative scoliosis. All patients were followed-up and examined at 2 months after surgery (follow-up moment 1). Long-term follow-up (moment 2; mean 36 months) was available of 17 patients; 2 patients died of unrelated disease and 1 patient was lost to follow-up. On both follow-up moments, neutral and dynamic flexion-extension images were documented. Based on these images, the position of the cage was determined and the Cobb’s angle of the segmental scoliosis (angle between the cranial endplate of the upper vertebral body and the caudal endplate of the lower vertebral body) was measured. The clinical outcome was measured by the patients’ global perceived recovery according to the 7-point Likert scale; “complete recovery” and “almost complete recovery” were determined as good results. Results: Most of the patients were operated on L3L4 and L4L5 (70%). The mean duration of surgery was 56 ± 15 minutes. Surgical complications occurred in 5 patients, namely cerebrospinal fluid leakage (4 patients) and nerve root injury (1 patient) with sensory deficit. Good outcome (Likert 1 or 2) was reported by 14 patients (70%) on the shortterm follow-up (moment 1), and by 9 patients (53%) on the long-term follow-up (moment 2). Whenever Likert 1-3 was dichotomized, 95% of the patients on the short-term and 83% of the patients on the long-term reported at least some benefit from the operation. The mean Cobb’s angle improved significantly from 13.4 ± 5.1o pre-operatively, to 6.1 ± 3.5o at moment 1, and 7.1 ± 3.6o at moment 2 (P < 0.001). On follow-up moment 1 and 2, radiographic examination showed subsidence in 3 and 9 patients, respectively. Pseudarthrosis around the stand-alone cage was only seen at follow-up moment 2 in 3 patients. Conclusions: Instrumented fusion with bilateral pedicle screw fixation and interbody fusion may not always be necessary in patients with scoliosis-related foraminal stenosis. Unilateral stand-alone TM cages could be an alternative strategy in a subgroup of patients leading to correction of Cobb’s angle and improvement of symptoms in most cases. However, the long-term result is moderately satisfying and could be explained by the development of cage subsidence over time.

Three finned press-fit cup: Does its initial fixation strength provide an adequate stability? Clinical midterm results of 685 implants

Introduction: One of the major causes of loosening of cementless acetabular cup implants is insufficient initial stability. A technical proposal to decrease the risk of suboptimal first stability is a circumferential finned design of the cup. This design aims to improve periacetabular bone contact and prevent rotational micromotion of the cup when optimal press-fit cannot be obtained. Materials and Methods: We retrospectively reviewed a group of 712 consecutive patients who underwent total hip arthroplasty from June 2006 to June 2014. In all patients, a titanium cup, characterized by three anti-rotational circumferential fins at the superior pole, was implanted. Results: Five hundred and ninety-two patients, for a total of 685 hips, were evaluated at a mean follow-up of 58 months (range 12-96 months). At 1-year follow-up, the average score increased to 82.90 (range 100-70) and at the final follow-up (58 months, range 12-96 months), it was 80.12 (range 100-66). In 22 cases (3%), screws to obtain a secure primary stability of the cup were used. Nineteen complications (2.6%) needing revision surgery were observed. Survivorship at 10 years was 98.7% (95% confidence interval [CI], 98.7-99.7%) with revision for aseptic cup loosening as an endpoint and 96.7% (95% CI, 98.3-95.1%) with revision for all causes of revision as the second endpoint. Discussion: In our group of patients, we did not observe the cases of very early cup loosening. The only two-cup revision, do to loosening of osteolysis, was observed 26 and 32 months before surgery. Conclusion: Our very low rate of additional screws represents an indirect sign of finned cup first stability. Three-finned cup design clinically confirmed to improve initial cup stability.

Optimizing Stability in Femoral Neck Fracture Fixation.

Optimizing stability of femoral neck fracture fixation is important in obtaining a successful outcome. The mechanical problems and strategies for achieving optimal stability differ depending on patients' age and degree of osteoporosis. Femoral neck fractures in younger adults usually result from high-energy trauma and have a vertical fracture pattern. Strategies for optimizing fixation stability in this group include placing additional screws at right angles to the fracture plane and medial buttress plate augmentation. In elderly patients, screw position relative to the intact cortical femoral neck bone is of critical importance. Additional strategies for optimizing fixation stability in this group include the concept of length stable fixation, use of adjunctive calcium phosphate cement, and use of novel fixed angle fixation implants.

First Metatarsalphalangeal Joint Arthrodesis: A Retrospective Comparison of Two Methods of Fixation.

First metatarsalphalangeal joint arthrodesis is a well established and successful treatment; however there still remains controversy over the best choice of construct. We performed a retrospective study of patients undergoing first metatarsalphalangeal fusion over eighteen months (n=52) using either dorsal non-locking plate with additional compression lag screw fixation or dorsal non-locking plate alone. We found when assessing clinical criteria, patients with dorsal non-locking plates and additional compression lag screw fixation had a significantly higher rate of fusion (100% vs 77.8%), significantly higher rate of fusion within the first two months (55.6% vs 83.3%), significantly earlier time to fusion (52.2 days vs 75.6 days), and significantly lower rate of non-union (0% vs 22.2%). When blindly assessing radiographic criteria, the patients treated with the plate and compression screw had a significantly higher rate of fusion and lower rate of non-union (0% vs 33%). There was no statistically significant difference between the frequencies of complications in the groups. We believe that the interfragmentary compression is a crucial factor in achieving good union rates and recommend the use of non-locking pre-contoured plating with additional interfragmentary compression screw as the fixation method of choice for these procedures.

Unilateral laminoplasty with lateral mass screw fixation for less invasive decompression of the cervical spine: a biomechanical investigation.

To compare the stabilization behavior of additional unilateral mass screw fixation with current standard procedures in patients with cervical spondylotic myelopathy (CSM) in a biomechanical study. Ten human C2-C7 cervical specimens were tested under various segment conditions: native (NAT), laminoplasty (LP), laminoplasty with unilateral (LPU) or bilateral (LPB) stabilization, laminectomy with bilateral stabilization (LCB), and laminectomy. The instrumented level was from C3 to C6. For each segment condition, in vitro flexibility tests were performed using a spinal simulator and an applied load of ±2.5 Nm. The three-dimensional kinematics of the entire cervical segment in three main loading directions [flexion-extension (FE), lateral bending (LB), and axial rotation (AR)] was measured with an ultrasonic motion analysis system. Analysis of variance followed by a post hoc test was used to determine differences under the specific segment conditions to assess the parameters range of motion (ROM) and neutral zone (NZ). For FE, the total ROM of laminoplasty (-6.3% difference to NAT) and laminectomy (+6.4%) remained at the level of native (p > 0.56), whereas the instrumentations LPU (-37.1%), LPB (-44%), and LCB (-43.2%) lead to significant reductions (p < 0.01) without significant differences in LPU to LPB and LCB (p > 0.38). The same results were found with LB. For AR, the stabilization of all instrumentations was less pronounced, but had the same tendency seen for FE and AR. The results for the NZ showed equivalent values as that for ROM. The degree of stabilization was as expected for LC and LCB; namely, no stabilization for LC and maximal stabilization for LCB. LPU exhibited almost the same degree of stabilization as LCB. LPU could be a new treatment option for less invasive decompression for multilevel CSM.

Screw augmentation reduces motion at the bone-implant interface: a biomechanical study of locking plate fixation of proximal humeral fractures

Shear forces at the bone-implant interface lead to a loss of reduction after locking plate fixation of proximal humeral fractures. The aim of the study was to analyze the roles of medial support screws and screw augmentation in failure loads and motion at the bone-implant interface after locking plate fixation of proximal humeral fractures. Unstable 3-part fractures were simulated in 6 pairs of cadaveric humeri and were fixed with a DiPhos-H locking plate (Lima Corporate, Udine, Italy). An additional medial support screw was implanted in 1 humerus of every donor. The opposite humerus was stabilized with a medial support screw and additional bone cement augmentation of the 2 anteriorly directed head screws. Specimens were loaded in the varus bending position. Stiffness, failure loads, plate bending, and the motion at the bone-implant interface were evaluated using an optical motion capture system. The mean load to failure was 669 N (standard deviation [SD], 117 N) after fixation with medial support screws alone and 706 N (SD, 153 N) after additional head screw augmentation (P = .646). The initial stiffness was 453 N/mm (SD, 4.16 N/mm) and 461 N/mm (SD, 64.3 N/mm), respectively (P = .594). Plate bending did not differ between the 2 groups. However, motion at the bone-implant interface was significantly reduced after head screw augmentation (P < .05). The addition of bone cement to augment anteriorly directed head screws does not increase stiffness and failure loads but reduces motion at the bone-implant interface. Thus, the risk of secondary dislocation of the head fragment may be reduced.

The Anterior "Triple-/Quadruple" Technique for C1/C2 Trauma in the Elderly: First Experience with 16 Patients

In geriatric patients the management of odontoid type II fractures is complicated by osteoporosis and atlantoaxial arthritis (spondylarthritis C1/C2) with an increased lever arm. Furthermore, a few of the odontoid fractures are accompanied by an atlas fracture resulting in the "atlantoaxial unhappy triad". Posterior C1/C2 spondylodesis with bilateral Magerl screws and C1 hooks is a strong biomechanical construct, however, the posterior approach is associated with several drawbacks such as increased risk of infection and increased blood loss. In contrast, the anterior bilateral C1/C2 transarticular screw fixation with additional odontoid screw fixation is also a known technique. Advantages of the anterior approach are shorter surgery time, lower intraoperative blood loss and lower risk of infection. In this retrospective study, all geriatric patients with an atlantoaxial arthritis and odontoid or combined atlantoaxial fracture treated at our institution between 01/2012 and 12/2014 with an anterior screw fixation were included. Following closed reduction, the surgical management was performed over a standard right anterior approach. At the end of surgery, operation time and blood loss were documented. During the hospital stay radiological follow-up of the upper cervical spine were performed to analyse the screw position. We also report the length of stay on intensive care unit, the hospital course and demographic data of the patients. Follow-up was planned after 6 weeks, 6, 12 and 18 months. During follow-up COMI evaluation and X-rays of the cervical spine were made. This study included 16 patients who underwent surgery for C1-C2 lesions. There were 9 females and 7 males. Median age at the time of operation was 76 years. At the time of surgery, fractures were classified as follows: 8 patients showed an "atlantoaxial unhappy triad", 8 patients had a type II odontoid fracture complicated by osteoporosis and atlantoaxial arthritis (spondylarthritis C1/C2). Average time for operative treatment was 100 ± 36.35 minutes with a median intraoperative fluoroscopy time of 161 seconds. The intraoperative blood loss was minimal (45 ± 22.80 ml). Length of stay was documented with 10 (± 4.60) days whereby the patients spent on average 0.8 days in the intensive care unit postoperatively. No serious morbidities, such as esophageal perforation, carotid artery laceration, neurological deterioration, and airway obstruction were reported. All cases of transient dysphagia resolved gradually and spontaneously without therapy. In 4 cases (25 %) we detected a penetration of the atlantooccipital joint without functional impairment. In one case we have seen an implant failure. The technique of anterior screw fixation of odontoid and bilateral transarticular C1-C2 anterior screw fixation provides a fast surgery without higher morbidity. Based on our findings, this technique and its feasibility is an alternative to known posterior C1/C2 spondylodesis in the elderly.

Interfragmentary lag screw fixation in locking plate constructs increases stiffness in simple fracture patterns

BackgroundThe aim of the current biomechanical cadaver study was to quantify the influence of an additional lag screw on construct stiffness in simple fracture models at the distal femur stabilised with a locking plate. MethodsFor biomechanical testing paired fresh frozen human femora of 5 donors (mean age: 71 (SD 9) years) were chosen. Different locking plate configurations either with or without interfragmentary lag screw were tested under torsional load (2/4Nm/deg) or axial compression forces (500/1000N). FindingsData show that plate constructs with interfragmentary lag screw reveal similar axial and torsional stiffness values compared to intact bone as opposed to bridging plate constructs that showed significantly lower stiffness for both loading conditions. InterpretationThe current biomechanical testing unveils that the insertion of a lag screw combined with a locking plate dominates over a bridging plate construct at the distal femur in terms of axial and torsional stiffness.

Surgical treatment and rehabilitation of medial Hoffa fracture fixed by locking plate and additional screws: A retrospective cohort study

PurposeHoffa fracture fixed by only using a single plate or lag screws might be not strong enough to achieve direct stability. The goal of this study is to determine the functional outcome of the surgical treatment and rehabilitation of medial Hoffa fracture by a locking plate combined with cannulated or lag screws. MethodsA total of 13 patients suffering isolated medical Hoffa fractures were identified during the study period (2005.February-2013.February) and retrospectively analyzed. All the fractures were treated by open reduction via the medial approach, and internal fixation by a locking plate combined with cannulated or lag screws. Early active rehabilitation including tele-rehabilitation for rural patients with restricted weight bearing was instituted after the surgical treatment. The radiological and functional outcome analysis was performed by using Knee Society Score (KSS), the range of movement (ROM), and the stability of fixation of the patients during 24 month follow-up. ResultsThe bone union of medial Hoffa fractures was achieved in all patients. The articular surface of medial femoral condyle was anatomically reduced. There was no loss of reduction and fixation. All patients achieved satisfactory knee joint function and regained their walking ability with good clinical results through early postsurgical rehabilitation. Ten patients (77%) had 0°–130° range of motion with full extension; two patients (15%) had 0°–115° range of motion; one patient (8%) had 0°–110° range of motion. The KSS of all the patients were more than 80, and the scores of seven patients (54%) were more than 85. ConclusionFixation with a locking plate and cannulated or lag screws for medial Hoffa fracture seemed to be effective and reliable for achieving anatomical reduction, and gave satisfactory functional results when coupled with aggressive rehabilitation.

Est-il avantageux d’ajouter une vis supplémentaire au travers du calcar dans l’enclouage verrouillé de l’humérus proximal ?

BackgroundThe objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck. HypothesisThe additional calcar screw improves stiffness and failure load. MethodsFourteen fresh-frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc®-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load to failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05). ResultsNo significant differences was observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases. DiscussionThe use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck. Level of evidenceLevel III. Experimental biomechanical study with human specimen.

Use of self-tapping metal screws for temporary fixation of a resorbable plate system in maxillofacial surgery.

Resorbable plate systems have been used in maxillofacial surgery to obviate the need for plate removal. However, resorbable plates and screws are very costly, and refixation with additional screws may be necessary when reduction or repositioning of the bone segment is inaccurate. Here we report the use of self-tapping metal screws for temporary fixation of a resorbable plating system in maxillofacial surgery to avoid the use of additional screws following inaccurate fixation or the reuse of resorbable screws, which may result in loosening.

Is there any advantage in placing an additional calcar screw in locked nailing of proximal humeral fractures?

BackgroundThe objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck. HypothesisThe additional calcar screw improves stiffness and failure load. MethodsFourteen fresh frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc®-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load-to-failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05). ResultsNo significant differences were observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases. DiscussionThe use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck. Level of evidenceLevel III. Experimental biomechanical study with human specimen.

Effect of minimally invasive transpedicular bone grafting additional vertebral pedicle screw fixation in the treatment of thoracolumbar fracture

Objective To explore the effect of minimally invasive transpedicular bone grafting additional vertebral pedicle screw fixation in the treatment of thoracolumbar fracture. Methods 60 patients with thoracolumbar fracture were randomly divided into the observation group and the control group,30 cases in each group. The control group received traditional open inter vertebral four nail pedicle screw fixation combined with posterolateral bone graft fusion for treatment while the observation group was treated by minimally invasive transpedicular bone grafting additional vertebral pedicle screw fixation,to analyze the clinical effects. Results The imaging parameters of postoperation[the sagittal index(1.9±7.1)°,Cobb's angle(4.2±3.5)°, change of vertebral body height(90.2 ±6.5)%]in the observation group were significantly better than those of the control group(t= 6.78,6.80,7.02,all P<0.05).The imaging parameters 3 months after operation[the sagittal index(4.9±3.2)°,Cobb's angle(7.0±2.7)°, change of vertebral body height(87.6±4.1)%]in the observation group were significantly better than those of the control group(t = 6.78,6.80,7.02,all P<0.05).The operation time,incision length,bleeding volume,postoperative drainage,postoperative hospital stay of the observation group were(141.9±14.2)min,(10.8±1.7)cm,(105.7±12.3)mL,(5.6±4.1)mL,(6.6± 1.1)d,respectively, which were significantly better than those of the control group(t= 7.72,7.89,5.68,all P<0.05). Conclusion Minimally invasive transpedicular bone grafting additional vertebral pedicle screw fixation has a significant effect in the treatment of thoracolumbar fractures, which is safe and reliable. Key words: Spinal Fractures; Bone Transplantation; Fracture Fixation, Internal

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.

Use of templates and self-tapping metal screws for temporary fixation of a resorbable plate system.

Resorbable plate systems combine the benefits of rigid internal fixation with the convenience of biodegradation; thus, precluding the need for removal and reducing their interference with craniofacial growth. However, in surgeries involving maxillofacial bone, when reduction or repositioning of the bone segment is inaccurate, refixation and rebending of the plate may be necessary. Here, we report using a temporary plate with self-tapping metal screws to avoid repeated rebending of the resorbable plate and using additional screws following inaccurate fixation in maxillofacial surgeries.

Minimally Invasive Spine Metastatic Tumor Resection and Stabilization: New Technology Yield Improved Outcome.

Spinal metastases compressing the spinal cord are a medical emergency and should be operated on if possible; however, patients' medical condition is often poor and surgical complications are common. Minimizing surgical extant, operative time, and blood loss can potentially reduce postoperative complications. This is a retrospective study describing the patients operated on in our department utilizing a minimally invasive surgery (MIS) approach to decompress and instrument the spine from November 2013 to November 2014. Five patients were operated on for thoracic or lumbar metastases. In all cases a unilateral decompression with expandable tubular retractor was followed by instrumentation of one level above and below the index level and additional screw at the index level contralateral to the decompression side. Cannulated fenestrated screws were used (Longitude FNS) and cement was injected to increase pullout resistance. Mean operative time was 134 minutes and estimated blood loss was minimal in all cases. Improvement was noticeable in neurological status, function, and pain scores. No complications were observed. Technological improvements in spinal instruments facilitate shorter and safer surgeries in oncologic patient population and thus reduce the complication rate. These technologies improve patients' quality of life and enable the treatment of patients with comorbidities.