Central Screw Research Articles

Antegrade Versus Retrograde Technique for Fixation of Scaphoid Waist Fractures: A Comparison of Screw Placement

Background Scaphoid waist fractures are often treated using headless compression screws using dorsal or volar approaches. Objectives The purpose of this study is to compare differences in screw position using a volar (retrograde) or dorsal (antegrade) approach. Patients and Methods A total of 82 patients were retrospectively evaluated: 41 treated with a volar and 41 with a dorsal approach were selected. Postoperative radiographs were reviewed by three observers who rated screw location in the proximal pole, waist, and distal pole. Results Thirty-four patients (83%) in the antegrade group had central screw placement in the waist of the scaphoid in posteroanterior and lateral planes compared with 14 (34.9%) in the retrograde group ( p < 0.05). For the antegrade group, the screw was central in 217 of 246 zones (88.2%) compared with 127 of 246 (51.6%) in the retrograde group ( p < 0.05). Conclusions The dorsal antegrade approach appears to allow the surgeon to achieve central screw placement along all three scaphoid regions. Level of Evidence This is Level III study.

Central screw use delays implant dislodgement in osteopenic bone but not synthetic surrogates: A comparison of reverse total shoulder models

Adequate glenoid baseplate fixation in reverse total shoulder arthroplasty (rTSA) is important to achieve, but may prove challenging in the context of glenoid bone loss or osteopenia. Current rTSA testing standards rely upon synthetic bone surrogates, but it is unclear if these models accurately recapitulate the mechanics of osteoporotic bone. Additionally, it also unknown if the use of a central screw effectively provides resistance to micromotion in the milieu of poor quality bone. The purpose of this experiment was to create a novel cyclic load test protocol that elicited clinically relevant failures, so that comparisons of relative motion between baseplates and bones could be made with: (1) synthetic bones and poor quality cadaveric bones, and (2) the use or omission of a central screw. rTSA components were implanted into cadaveric and synthetic bones with and without a central screw. To model a range of loads that may be experienced during abduction, increasing cyclic loads were applied to shoulder joints in 30° of humeral abduction. Cycles and loads prior to permanent deformation exceeding 150 µm, 1 mm, and joint failure were determined using measurements from the test frame and from 3-D motion analysis. Synthetic bones demonstrated significantly more resistance to micromotion in comparison to cadaveric bones. Use of the central screw improved resistance to dislodgement, which was only observed in the cadaveric specimens. This study highlights the need for biomechanical testing with cadaveric specimens, especially when assessing osteopenic or osteoporotic populations.

Skeletal and dentoalveolar changes in the transverse dimension using microimplant-assisted rapid palatal expansion (MARPE) appliances

Conventional rapid palatal expansion (RPE) has been proven to be a reliable treatment for correcting transverse maxillary deficiency in young patients. However, side effects including dental tipping and risk of periodontal problem limited its application to young patients after the pubertal growth spurt. Surgically assisted rapid palatal expansion (SARPE), a supplement to RPE, could be applied in skeletally mature patients. However, SARPE was an invasive method, and the morbidity, risks and cost related to surgical treatment might discourage many adult patients. The use of Microimplant-Assisted Rapid Palatal Expansion (MARPE) appliance, which can potentially avoid surgical intervention, is gaining popularity in treatment of maxillary transverse deficiency (MTD) in young adolescent patients. However, the literature on the skeletal and dentoalveolar changes with this appliance is scarce. To evaluate the immediate skeletal and dentoalveolar changes in the transverse dimension with the maxillary skeletal expander (MSE), a MARPE appliance with hybrid anchorage, using cone-beam computed tomography (CBCT). Twenty-two patients (11 males and 11 females, mean age 14.97 ± 6.16 years) with transverse maxillary deficiency were treated using the MSE (Biomaterials Korea, Inc., Seoul, Korea). The appliance consisted of a central expansion screw that were welded to four tubes that served as guides for microimplant placement. The microimplants were 1.8 mm in diameter and 11 mm in length. The longer length of microimplants permitted bicortical engagement of the palatal and nasal floor, reducing the force transmitted to the anchored teeth during expansion. The appliance activation varied with age and skeletal maturity of the patient. The expansion was terminated when 2–3 mm of overexpansion was achieved. CBCT scans were taken before treatment (T1) and immediately after expansion (T2). Measurements were taken to evaluate the amount of total expansion, skeletal expansion, and angular dental tipping at the first molar region. A total expansion of 5.41 ± 2.18 mm was achieved, 59.23 ± 17.75% of which was attributed to skeletal expansion (3.15 ± 1.64 mm) with the first molars exhibiting buccal tipping of 2.56 ± 2.64°. The use of MARPE appliances such as MSE can be used to correct transverse maxillary deficiency in adolescent patients with minimal dentoalveolar side effects.

Micromotion of implant-abutment interfaces (IAI) after loading: correlation of finite element analysis with in vitro performances.

Micromotion between IAI affects long-term survival rate of dental implants. The use of practical implants for mechanical test is costly. Finite element analysis (FEA) could test the micron level deformation changes, but whether it reflects the in vitro mechanical performances remains unknown. This study aims to investigate the correlation between IAI micromotion of FEA and in vitro performances. The two-step-two-component FEA method was used to test the relative deformation between IAI for three implant designs (M1, M2, and M3) during torque loading and cyclic oblique loading. The micromotion was divided into directions that perpendicular to (x-axis) and parallel to (y-axis) IAI. In vitro experiments on the micromotion relevant performance of IAI microleakage (tested by toluidine blue releasing with a spectrometer) and IAI locked condition (tested by abutment removal force tests after detaching the central screws) were also conducted for the identical implant systems (G1, G2, and G3). One-way ANOVA and Pearson's correlation tests were performed for data analysis. FEA illustrated that the three implant systems performed different micromotion patterns. Significant differences were found in the IAI microleakage and removal force among the groups. Positive correlations were found between FEA and in vitro outcomes. Therefore, the two-step-two-component FEA method is an appropriate method to evaluate the IAI micromotion after loading. Graphical abstract The correspondence of IAI micromotion between FEA analysis and in vitro performances.

Calcar buttressed screw fixation for femoral neck fracture

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; The incidence of neck of femur fracture among elderly population is increasing day by day. Femoral neck fracture has always been an unsolved fracture&lt;strong&gt; &lt;/strong&gt;as far as treatment and results are concerned. There are different views regarding the optimal method of internal fixation in femoral neck fractures. Biomechanical data from literature suggest that calcar fixation is superior to central screws placement. This study aims to analyse the functional and radiological outcome of femoral neck fractures treated by calcar buttressed screw fixation described by Filipov as biplane double supported screw fixation.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; This is a prospective study conducted in our institution from May 2015 to May 2018.The study included 43 patients (31 male, 12 female) with femoral neck fracture. Three 6.5-mm cannulated screws were laid in two medially diverging oblique planes. The distal and the middle screws were supported on the calcar. The distal screw had additional support on the posterior neck cortex. Patients were followed up for average period of 2 years. Functional outcome was evaluated using Harris Hip score.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Bone union occurred in 40 patients (93%) with average period of 3-4 months.&lt;strong&gt; &lt;/strong&gt;51.2% of cases had&lt;strong&gt; &lt;/strong&gt;excellent outcome. 23.2% of cases had good and 16.3% of cases had fair outcome. 9.3% of cases ended with poor outcome. Non union was reported in 3 patients (7%) and AVN in one patient. Various factors like age, Garden and Pauwel fracture types, time of presentation and time of surgery were statistically significant to the final functional outcome in our study.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; By providing additional calcar buttress compared to conventional method, this technique of screw fixation enhances femoral neck fracture fixation strength and reduces the fixation failure. &lt;/p&gt;

Structures at Risk During Percutaneous Screw Fixation for Talonavicular Fusion.

Talonavicular (TN) fusion using screws dorsomedially and dorsolaterally can cause neurovascular injury. The purpose of our cadaveric study was to evaluate the safety of percutaneous screw insertion in relation to dorsal neurovascular structures. Ten fresh-frozen cadaver legs were used for this study. Percutaneous cannulated screws were inserted to perform isolated TN arthrodesis. The screws were inserted at 3 consistent sites: a "medial screw" at the dorsomedial navicular where it intersected at the medial plane of the first cuneiform, a "central screw" at the edge of the dorsal navicular between the medial and intermediate cuneiforms, and a "lateral screw" at the edge of the dorsal navicular between the intermediate and lateral cuneiforms. Superficial and deep dissections were carried out to identify any injured nerves, arteries, and/or tendons. The medial screw injured the anterior tibialis tendon in 2 cases (20%), the central screw injured the extensor hallucis longus tendon in 3 cases (30%), and the lateral screw injured the anterior branch of the superior peroneal nerve (SPN), the lateral branch of the SPN, and the medial branch of the distal peroneal nerve (DPN) once each in a total of 3 cases (30%). Despite no direct injury, the central screw indicated a potential risk of neurovascular injury: closest distance to the anterior SPN was 2 mm and to the medial DPN 2 mm. Although neurovascular injury risk exists for all of these screw placements, TN fusion with a central screw introduced a potentially decreased risk of neurovascular injury at the expense of increased risk of tendon injury compared to the lateral screw. Based on these results, we recommend a careful dissection be performed prior to percutaneous screw insertion.

Effect of Screw Length and Geometry on Interfragmentary Compression in a Simulated Proximal Pole Scaphoid Fracture Model.

Background: The objective of this study was to determine interfragmentary compression forces based on screw length and geometry for simulated proximal scaphoid fractures. Methods: Sixty-four foam model simulated fractures were stabilized with screws of various length (10 mm, 18 mm, 20 mm, or 24 mm) and geometry (central threadless or fully threaded) across a proximal fracture. Interfragmentary compression was measured at the simulated fracture site upon fixation. An independent sample t test and 1-way analysis of variance were performed to assess differences in interfragmentary compression. Results: Fixation utilizing a 10-mm screw generated significantly less interfragmentary compression than fixation utilizing a 20-mm or 24-mm screw. When accounting for both screw length and geometry, an 18-mm central threadless screw generated greater interfragmentary compression than a 20-mm and 24-mm fully threaded screw; there was no significant difference in compression between an 18-mm and 24-mm central threadless screw. Conclusions: The design of headless compression screws allows for maximal interfragmentary compression at the screw midpoint; we questioned whether a short screw centered on the fracture site resulted in superior compression to a longer, noncentered screw. Our data suggest that centering a small screw (10 mm) along a proximal fracture generates significantly less interfragmentary compression than a longer, noncentered screw. Our results demonstrate that balance between maximizing screw length and centering the screw on the fracture is vital toward maximizing interfragmentary compression for the fixation of proximal third scaphoid fractures.

Case Report: Controlled Hip Dislocation. Slipped Capital Femoral Epiphysis

BACKGROUND: The epiphysiolysis of the femoral head is the displacement of the epiphysis with respect to the metaphysis, in anterosuperior direction; it is etiology is unknown, frequent in adolescents, peripubertal period, and with high body mass index, average age between 12 and 18 years. It is incidence is variable, 0.2 (Japan) to 10 (United States) per 100 000 inhabitants. It is characterized by progressive pain in the hip, with irradiation to the groin or knee, is associated with lameness; with the early detection, an adequate treatment can be established, the most accepted one is the in situ fixation with central screws. CASE REPORT: A 14-year-old female patient with no pathological history attended the Children's Orthopedic Service due to the chronic lancinating pain of the right hip, which increases with walking, it is diagnosed by clinical examination and complementary exams of femoral head epiphysiolysis. Surgical dislocation of the hip and anatomical open reduction with placement of spongy screws was performed. EVOLUTION: On the third day of surgery, hospital discharge is decided; walking with crutches and without support during a postoperative month. The osteosynthesis remained for a year with monthly controls and corresponding physiotherapy; it has been evidenced favorable evolution; hip mobility arches preserved, normal ambulation, without complications CONCLUSIONS: The initial treatment of a patient with epiphysiolysis of stable femoral head depends on the evolution time and is done by fixing with screws or needles with of anatomical dislocation of the hip and osteoplasty of femoral neck remodeling. Most patients do not develop necrosis or chondro- lysis and long-term results with in situ fixation are usually excellent, unlike patients with late diagnosis.

Safe Zone for Percutaneous Screw Fixation - Talonavicular Fusion

Category: Hindfoot Introduction/Purpose: Talonavicular fusion has been established as a reliable intervention for degenerative, inflammatory, and traumatic joint lesions as well as hindfoot deformities. In order to achieve optimal fusion, various versions of the procedure have been introduced in literature and have remained a topic of contention, with the most common variation involving the insertion of 1 to 3 screws dorsomedially and dorsolaterally. Dorsolateral screw placements commonly cause neurovasculature injury. The purpose of our cadaveric study was first to establish the safety of the dorsolateral percutaneous screw insertion in relation to these dorsal neurovascular structures, and then subsequently to standardize the ideal placement of the dorsolateral screw by comparing two insertion sites based on consistent bony landmarks. Methods: Ten fresh-frozen cadaver legs amputated at the knee were used for this study. Percutaneous cannulated screws were inserted to perform isolated talonavicular arthrodesis. The screws were inserted at 3 consistent sites: “medial screw” at dorsomedial navicular where it intersected at the medial plane of the first cuneiform, “central screw” at the edge of dorsal navicular between medial and intermediate cuneiforms, and “lateral screw” at the edge of dorsal navicular between intermediate and lateral cuneiforms. Superficial and deep dissections were carried out to identify any injured nerves, arteries, and tendons. Results: The mean age at death in our sample of cadavers was 80.1 ± 7.5 years (range 68 to 92) and had the BMI of 21.8 ± 2.4 (range 18.1 to 25.1). There were 5 males (50.0%) and 5 females (50.0%). The medial screw injured the anterior tibialis tendon in 2 cases (20.0%), the central screw injured the extensor hallucis longus tendon in 3 cases (30.0%), and the lateral screw injured the anterior branch of SPN, lateral branch of SPN, and medial branch of DPN once each in a total of 3 cases (30.0%). Conclusion: TN fusion with central screw placement at the interspace between the medial and intermediate cuneiforms protects the neurovasculatures of the foot to a superior extent than lateral screws between the intermediate and lateral cuneiforms.

Bone preserving technique for reverse arthroplasty: The preferred management option for osteoarthritis with glenoid bone loss in patients 70 and older

Elderly patients with shoulder arthritis and glenoid bone loss represent a challenging patient population. Surgical treatment options include hemiarthroplasty, anatomic total shoulder arthroplasty (TSA) with bone grafting or augmentation, and reverse total shoulder arthroplasty (RSA). The RSA has multiple advantages compared to anatomic TSA, particularly in an older patient population with glenoid bone loss.RSA with an augmented glenoid baseplate is ideal for the treatment of patients who have glenoid bone loss. The augmented base plate has many advantages including bone preservation, longer central and peripheral screws, ability to dial the augment to match the region of bone deficiency, and lateralization to improve tensioning on the deltoid and rotator cuff. Additionally, a bone preserving RSA is possible with an augmented glenoid baseplate in patients with no glenoid bone loss.

Guide broche par impression 3D pour la fixation percutanée rétrograde du scaphoïde. Comparaison à la technique conventionnelle lors d’une étude cadavérique

Central screw placement in the scaphoid is the key of a rigid and safe percutaneous retrograde fixation of scaphoid fractures. Cannulated compression screws are most frequently used. This technique requires perioperative control of the position of the guide wire. The standard fluoroscopic method has many disadvantages: irradiation, multiple passes needed to obtain a proper position of the wire in two planes, and duration of the surgical procedure. The purpose of this study was to compare a patient-specific 3 dimensional-printed wire-guide (PS) and the standard fluroscopic technique (FT) in cadaver specimen. Twelve cadaver wrists were divided into two groups. In the FT group (6 wrists), the wire was inserted using the standard fluoroscopic method. In the PS group (6 wrists), a patient specific wire-guide was used. Preoperative CT scan allowed reconstruction of cutaneous envelope and identification of ideal path for the wire into the scaphoid. Based on these data, we modelized a “mold-guide”, including a wire guide sleeve aligned with the planned ideal path, and printed it using 3D-printing technology. Fluoroscopy was used in the latter group only to check the absence of prominence of the head screw. To assess the accuracy of screw placement in both groups, we analysed on postoperative CT scans the angular deviation of the screw with the ideal screw axis planned on preoperative CT scans (performed in both groups). Moreover, the operative time, the fluoroscopic time, and the number of trial guide wire placements were evaluated. The angular deviation between the screw position and the ideal screw axis was significantly lower in the PS group than in the FT group (respectively P = 0.001 et P = 0.02 for coronal and sagittal planes). The duration of procedure was significatively lower in the PS group (5.3 min) than in the FT group (17 min) (P = 0.007). Number of trial placements and fluoroscopic time were also significatively lower in the PS group. The use of a patient-specific 3D-printed guide for scaphoid percutaneous fixation allows a more accurate placement of the screw than with the standard fluoroscopic method. As several trial placements of the guide wire are not necessary, the operative time is decreased and the procedure is getting simpler. This new technique is promising and should be evaluated in clinical practice.

Three-dimensional comparison of alternative screw positions versus actual fixation of scaphoid fractures

PurposeThe recommended technique for the fixation of a scaphoid waist fracture involves a headless compression screw placed in the proximal fragment center. This is usually accomplished by placing a longitudinal axis screw as visualized by fluoroscopy. The screw length has been shown to have a biomechanical advantage. An alternative to these options, which has been debated in the literature, is a screw placed perpendicular to the fracture plane and in its center. The perpendicular screw may have a biomechanical advantage despite the fact that it may be shorter. This study examined the differences in location and length in actual patients between a screw in the center of the proximal fragment with a longitudinal axis screw, and the actual fixating screw. These were then compared to a perpendicular axis screw. MethodsPre- and post-operative CT scans of 10 patients with scaphoid waist fractures were evaluated using a 3D computer model. Comparisons were made between the length, location and angle of actual and virtual screw alternatives; namely, a screw along the central third of the proximal fragment (central screw axis) where the scaphoid longitudinal axis was calculated mathematically (longitudinal screw axis) and a screw placed at 90° to the fracture plane and in its center (perpendicular screw axis). ResultsThe longitudinal axis screw was found to be significantly longer than the other axes (28.3mm). There was a significant difference between the perpendicular axis screw and the location and angle of the other screw axis, but it was only shorter than the longitudinal screw (23.6mm versus 25.5mm for the actual screw; ns.). ConclusionsA computed longitudinal axis screw is longer than a central or actual screw placed longitudinally by visual inspection by the surgeon. Although it needs to be placed using computer assisted (CAS) techniques, it may have the biomechanical advantages of a longer screw in a similar trajectory. The perpendicular screw was found to be significantly different in position and angle but not shorter than the actually placed screw. It has biomechanical advantages and does not require visualization with CAS methods, making it the more attractive alternative.

Computational analysis of the safe zone for the antegrade lag screw in posterior column fixation with the anterior approach in acetabular fracture: A cadaveric study

ObjectiveThe fluoroscopically-guided procedure of antegrade posterior lag screw in posterior column fixation through anterior approach is technique-dependent and requires an experienced surgeon. The purpose of this study was to establish the safe zone for the antegrade posterior lag screw by using computational analysis. MethodThe virtual three-dimensional model of 178 hemi-pelvises was created from the CT data (DICOM format) by using Mimics® program, and were used to measure the safe zone of antegrade lag screw fixation on the inner table of the iliac wing, and the largest diameter of cylindrical implant inside safe zone. The central point (point A) of the cylinder was assessed and was compared with the intersection point (point B) between the linea terminalis and the anterior border of the sacroiliac articulation. ResultsThe safe zone was triangular with an average area of 670.4mm2 (range, 374.8–1084.5mm2). The largest diameter of the cylinder was a mean 7.4mm (range, 5.0–10.0mm). When height was under 156.3cm, the diameter of the cylindrical implant was smaller than 7.0mm (p<0.001, regression coefficient=0.09). The linear distance between points A and B was 32.5mm (range, 19.2–49.3mm). Point A was far enough away from the well-positioned anterior column plate to prevent collision between the two. ConclusionThe safe zone was shaped like a triangle, and was large enough for multiple screws. Considering the straight-line distance between points A and B, the central screw can be fixed without overlapping with the well-positioned anterior column plate at the point between holes 2 and 3.

Effect of Screw Perpendicularity on Compression in Scaphoid Waist Fractures.

Background Central and perpendicular (PERP) screw orientations have each been described for scaphoid fracture fixation. It is unclear, however, which orientation produces greater compression. Questions/Purposes This study compares compression in scaphoid waist fractures with screw fixation in both PERP and pole-to-pole (PTP) configurations. PERP orientation was hypothesized to produce greater compression than PTP orientation. Methods Ten preoperative computed tomography scans of scaphoid waist fractures were classified by fracture type and orientation in the coronal and sagittal planes. Three-dimensional models of each scaphoid and fracture plane were created. Simulated Acutrak 2 (Acumed, Hillsboro, OR) screws were placed into the models in both PERP and PTP orientations. Engagement length and screw angle relative to the fracture were measured. Compression strength was calculated from the shear area, average density, and angle acuity. Results The PTP angle between screw and fracture ranged from 36 to 84 degrees. By definition, the PERP screw-to-fracture angle was 90 degrees. Perpendicularity of the PTP screw to the fracture was positively correlated to compression strength. PERP screws had greater compression than PTP screws when the PTP screw-to-fracture angle was < 80 degrees (106 vs. 80 N), but there was no difference in compression when the PTP screw-to-fracture angle was > 80 degrees, approximating the PERP screw. Conclusion Increasing screw perpendicularity resulted in higher compression when the screw-to-fracture angle of the PTP screw was < 80 degrees. Maximum compression was obtained with a screw PERP to the fracture. The increased compression gained from PERP screw placement offsets the decreased engagement length. Clinical Relevance These results provide guidelines for optimal screw placement in scaphoid waist fractures.

Glenoid Bone-Grafting in Revision to a Reverse Total Shoulder Arthroplasty: Surgical Technique.

Reverse shoulder arthroplasty has emerged as a very good treatment option for patients in salvage situations, such as the revision setting with glenoid bone loss. For patients undergoing revision shoulder arthroplasty, perform the preoperative evaluation with radiographs, computed tomography (CT), and digital templating software as they play a key role (Video 1). Perform all operations with the patient in the beach-chair position. Glenoid exposure is the key to the operation. Use bone graft if the glenoid is thought to be inadequate for stable fixation in an acceptable position. When a peripheral defect contributes to either glenoid anteversion (anterior) or retroversion (posterior), but the implant has ≥50% contact with the native bone, consider using a structural autograft from the local humerus (preferred), if available, or a structural allograft (Video 1). In shoulders with a peripheral defect with <50% contact with the native glenoid and substantial alterations in glenoid version, consider using a structural autograft from the proximal part of the humerus (preferred), if available, or the iliac crest (Figs. 2-A, 2-B, 2-C, and 3; Video 1). In shoulders with a central defect with ≥30% contact between the baseplate and the native glenoid, with adequate primary stability of the central screw and/or peg, use morselized local autograft (preferred), if available, or corticocancellous allograft, to restore the lateral offset of the native glenoid and implant-bone contact area. As a large central or global deficiency can lead to excessive glenoid medialization (Figs. 4-A, 4-B, and 4-C), use a structural tricortical autograft from the iliac crest to restore glenoid structure and support implantation, as well as increase the offset of the glenoid component, enhancing stability and potentially reducing the risk of scapular notching8. For a superior deficiency with <50% contact between the implant and the native bone and a loss of neutral tilt, avoid superior tilt as it is critical to obtain either neutral or inferior tilt of the glenoid (keep this in mind when placing the central cannulated Kirschner wire for drilling the central screw) and use structural autograft for larger defects to prevent superior tilt, with the source of the graft preferentially from the humeral neck resection; however, if there is not adequate proximal humeral bone, a tricortical graft from the ipsilateral iliac crest can be used. In our practice, glenoid bone-grafting was performed in 29% of the 143 shoulders revised using reverse components2.

Total Joint Replacement of the Trapeziometacarpal Joint

Objective: Total joint arthroplasty of the trapeziometacarpal (TMC) joint is an option for the treatment of degenerative or posttraumatic osteoarthritis (OA) of the thumb. The purpose of this study is to analyze, retrospectively, results over 5 years for patients with OA of the TMC joint treated by arthroplasty with prosthesis. Materials and Methods: Fourteen patients (13 female and 1 male) with OA of the TMC were treated surgically by 1 surgeon from 2000 to 2011. The average age of the patients was 68 years; the youngest was 56 years. Indications for surgery were severe pain, loss of pinch strength, diminished thumb motion, and deformity (Eaton and Littler stages III and IV). Contraindications were history of acute or chronic infection, pantrapezial arthritis, and scaphotrapezial arthritis. The TMC joint of all patients were totally replaced by the “Mathys” cementless bipolar prosthesis. The postoperative care included 3 weeks immobilization of the thumb followed by a rehabilitation program. The average follow-up time was 60 weeks. All patients were evaluated by objective and subjective parameters. Objective assessment included range of motion at the TMC joint (flexion-extension, abduction-adduction, and opposition), grip and pinch strength (tip pinch and key pinch), and loosening. Subjective assessment was pain related to activity of daily living and patient satisfaction after surgery. The residual pain was assessed by visual analogue scale (VAS). Radiographic follow-up included evaluation for migration and loosening of the stem and cup, and joint subluxation as defined by Wachtl. Results: The average range of motion for the TMC joint was 90% when compared with the contralateral side. Power of oppositional pinch was average 4.8 kg (88% of the contralateral hand), tip pinch was 5.6 kg (91% of contralateral hand), and key pinch was 6.2 kg (90% of contralateral hand). Ten patients were free of pain, 3 patients reported mild pain after heavy work (2 of 10 of VAS). Only 1 patient complained of prolonged pain (4 of 10 of VAS) due to the development of trapezoid arthritis. He was successfully treated with a cortisone injection. Osteolysis developed around the 2 cups and the 3 stems of the implants. One patient had posttraumatic loosening of the stem which was revised and tightened. There were no radiological signs of subluxation or periprosthetic fractures. The first 2 patients in this study were surgically treated 16 years ago, and they currently actively work with no complaints or complications. Conclusions: Data from our study with a minimum of 5 years of follow-up demonstrate that patients have excellent, pain-free range of motion, with no significant radiologic signs of implant loosening, periprosthetic osteolysis, or complications. In 1 case of stem loosening, the implant’s design allowed retightening of the central screw of the stem without requiring replacement with a new one. Total joint arthroplasty with prosthesis is a promising option for long-term restoration of the stability and mobility in a compromised TMC joint.

Different Types of Properties of Cane Juice Centrifugation

The affirmation of rotator for the specific kind of suspension needs some key data. The particles, which are open in different sizes, their task in the medium, outstanding thickness, thickness, etc are the major norms. It includes a central screw type transport which clears the saved solids. The speed keeps up could be around 8000 rpm in the level of 70-75% mud moisture. In this paper we are examining centrifugation of stick juice in the sugar business.

A rabbit model of lumbar distraction spinal cord injury

Background ContextExcessive spinal distraction is a major cause of distraction spinal cord injury (SCI) during spinal deformity correction surgery. However, the lack of animal models of gradable and replicable distraction SCI has hampered research about how it occurs and how it can be prevented. The rabbit is a suitable choice for a model because it is more similar to humans than the rat, the most often used for studies of distraction SCI. The rabbit is readily acquired and reasonably affordable to maintain. PurposeThe study aims to develop a gradable and replicable animal model of human lumbar distraction SCI. Study DesignThis is an animal laboratory study. MethodsWe built a spine distractor designed to vary the percentage of spine distraction by changing the movement between the bony landmarks of the spine. Anesthetized rabbits underwent surgery to expose the vertebral segments from T12 through L4. The distractor was mounted onto the T12 and L4 vertebral segments, and distraction was effected by turning the distractor's central screw to 0% (control), 10%, 20%, or 30% of the length from the L1 to the L4 vertebral segments, with eight rabbits in each group. Cortical somatosensory evoked potentials were recorded, and neurologic function was evaluated before the distractor was mounted and after the distractor was dismounted. The rabbits were killed, and spinal cord samples were taken for biochemical, histopathologic, and stereologic studies. ResultsWith increasing percentage distraction, the extent of distraction SCI increased as measured by recordings of cortical somatosensory evoked potentials, neurologic function, and biochemical, histopathologic, and stereologic studies. ConclusionsOur model can be widely applied to studies of the causes of and treatment for distraction SCI.

Graphical method for profiling hob mill that generate cycloid worms

The hob mill for generating ordered curls of cycloid surface with non involute profiles may be profiled based on the fundamental theorems of surface enveloping - Olivier - as surface reciprocally enveloping with point like contact. In this paper, is proposed a methodology based on a complementary theorem of the surface enveloping in a graphical expression developed in a graphical design environment - CATIA. The graphical method presented in this paper is developed in two stages: determining of the rack gear model based on the solid model of the surface to be generated, using an original algorithm, following this, based on 3D modelling is determined the solid model of the primary peripheral surface of the hob mill. An application for a cycloid worm is presented - a central screw of helical pumps. In order to prove the quality of method, the analytical and graphical solutions are comparatively presented.

Comparison of Head Center Position and Screw Fixation Options Between a Jumbo Cup and an Offset Center of Rotation Cup in Revision Total Hip Arthroplasty: A Computer Simulation Study

Jumbo acetabular cups are commonly used in revision total hip arthroplasty (THA). A straightforward reaming technique is used which is similar to primary THA. However, jumbo cups may also be associated with hip center elevation, limited screw fixation options, and anterior soft tissue impingement. A partially truncated hemispherical shell was designed with an offset center of rotation, thick superior rim, and beveled anterior and superior rims as an alternative to a conventional jumbo cup. A three dimensional computer simulation was used to assess head center position and safe screw trajectories. Results of this in vitro study indicate that a modified hemispherical implant geometry can reduce head center elevation while permitting favorable screw fixation trajectories into the pelvis in comparison to a conventional jumbo cup.