High Primary Stability Research Articles

Metal-Free Fixation for Free Bone-Block Reconstruction of Chronic Anteroinferior Shoulder Instability

Background: Anterior shoulder instability is common and may cause a considerable effect on quality of life. For cases with glenoid bone loss, there is still a controversial discussion regarding the optimal treatment. Most of the recent methods are using metal implants to attach the needed graft to the glenoid with reported disadvantages such as metal impingement, damage to the humeral head, cartilage destruction, and premature arthritis. Indications: (1) Erosion-type defects with significant bone loss (>15%-20%); (2) chronic fragment-type defects if the size of the fragment is not large enough for an anatomical reconstruction; and (3) non-reconstructible, multifragmented acute fragment type of lesions. Technique Description: After placing the patient in a lateral decubitus position and fixing the arm in a traction devise, 3 arthroscopic entries are established: a posterior portal, an anterosuperior portal, and an anteroinferior portal. A harvested tricortical iliac crest bone graft is provided with 2 drilling holes which match the drilling holes through the glenoid. The tapes are then placed from the posterior to the anterior side of the glenoid, and then the graft is passed from the anterior to the posterior side, thus compressing the cancellous side of the bone block onto the glenoid defect. A following interconnection of the sutures creates a continuous loop. The end of the tapes was loaded into a pretied racking hitch knot system, which creates sliding knots between the 2 pair of tapes, whereon the knots can be reduced to the glenoid in a symmetrical fashion. Finally, the reconstruction of the anterosuperior labrum can be done, to cover the bone block with enough soft tissue. Results: First short-term results show radiographic consolidation after 3 months and an increased median glenoid estimated surface area at 12 months. The functional scores showed good outcomes, and there were no serious complications reported. Discussion/Conclusion: The presented arthroscopic reconstruction of the glenoid using a tricortical bone graft and high-strength fiber tapes provides a metal-free technique which results in a high primary stability of the construct and should therefore be considered when treating anterior shoulder instability with significant bone loss.

A New System for Periprosthetic Fracture Stabilization-A Biomechanical Comparison.

In recent years, an increase in periprosthetic femur fractures has become apparent due to the increased number of hip replacements. In the case of Vancouver type B1 fractures, locking plate systems offer safe procedures. This study compared the distal lateral femur plate (LOQTEQ®, aap Implantate AG) with a standard L.I.S.S. LCP® (DePuy Synthes) regarding their biomechanical properties in fixation of periprosthetic femur fractures after hip arthroplasty. We hypothesized that the new LOQTEQ system has superior stability and durability in comparison. Eighteen artificial left femurs were randomized in two groups (Group A: LOQTEQ®; Group B: L.I.S.S. LCP®) and tested until failure. Failure was defined as 10° varus deformity and catastrophic implant failure (loosening, breakage, progressive bending). Axial stiffness, loads of failure, cycles of failure, modes of failure were recorded. The axial stiffness in Group A with 73.4 N/mm (SD +/− 3.0) was significantly higher (p = 0.001) than in Group B (40.7 N/mm (SD +/− 2.8)). Group A resists more cycles than Group B until 10° varus deformity. Catastrophic failure mode was plate breakage in Group A and bending in Group B. In conclusion, LOQTEQ® provides higher primary stability and tends to have higher durability.

Fixation of intraoperative proximal femoral fractures during THA using two versus three cerclage wires - a biomechanical study

BackgroundIntraoperative proximal femoral fractures (IPFF) are relevant complications during total hip arthroplasty. Fixation using cerclage wires (CW) represents a minimally-invasive technique to address these fractures through the same surgical approach. The goal of treatment is to mobilise the patient as early as possible, which requires high primary stability. This study aimed to compare different cerclage wire configurations fixing IPFF with regard to biomechanical primary stability.MethodsStandardised IPFF (type II, Modified Mallory Classification) were created in human fresh frozen femora and were fixed either by two or three CW (1.6 mm, stainless steel). All cadaveric specimens (n = 42) were randomised to different groups (quasi-static, dynamic) or subgroups (2 CW, 3 CW) stratified by bone mineral density determined by Dual Energy X-ray Absorptiometry. Using a biomechanical testing setup, quasi-static and dynamic cyclic failure tests were carried out. Cyclic loading started from 200 N to 500 N at 1 Hz with increasing peak load by 250 N every 100 cycles until failure occurred or maximum load (5250 N) reached. The change of fracture gap size was optically captured.ResultsNo significant differences in failure load after quasi-static (p = 0.701) or dynamic cyclic loading (p = 0.132) were found between the experimental groups. In the quasi-static load testing, all constructs resisted 250% of the body weight (BW) of their corresponding body donor. In the dynamic cyclic load testing, all but one construct (treated by 3 CW) resisted 250% BW.ConclusionsBased on this in vitro data, both two and three CW provided sufficient primary stability according to the predefined minimum failure load (250% BW) to resist. The authors recommend the treatment using two CW because it reduces the risk of vascular injury and shortens procedure time.

Prospective clinical results of an additive ligament bracing for stabilizing simple and complex elbow instabilities.

Ligament bracing augments ligament repair using a non-absorbable suture tape. Although biomechanically an increase in primary stability has been proven, there is a lack of clinical evidence. Purpose of this study was to evaluate clinical results of patients treated with ligament bracing due to primary elbow instability, including an analysis of complications. Furthermore, clinical results for patients treated with and without early functional mobilization were compared. This prospective case-series evaluated clinical and functional results from patients treated with ligament bracing due to primary elbow instability. Clinical outcome measures were range of motion (ROM) as well as objective and subjective elbow scores [Mayo Elbow Performance Score (MEPS); Disabilities of Arm, Shoulder and Hand Score (DASH score)]. Stability was evaluated sonographically by humero-radial gapping under varus stress. This study involved 34 patients treated with ligament bracing. After a mean follow-up of 12.9months ROM was 112° ± 29, MEPS 88 ± 13 points, DASH 91 ± 11 points, and 84% were satisfied with their result. Lateral joint gapping was 2.4mm. No significant difference was observed regarding a postoperative mobilization with and without limitations. Most common complication after ligament bracing was elbow stiffness including heterotopic ossifications in four patients (12%). Operatively treated elbow instability with additional ligament bracing results in good clinical outcomes with high patient satisfaction and recovery of elbow stability. The high primary stability of the ligament bracing allows early functional mobilization without bracing, which facilitates postoperative rehabilitation. Elbow stiffness with heterotopic ossification seems to be a potential complication. Furthermore, the optimal tensioning of the ligament bracing remains challenging, including the risk of an over tensioning. III.

Impact of lattice versus solid structure of 3D-printed multiroot dental implants using Ti-6Al-4V: a preclinical pilot study.

PurposeVarious studies have investigated 3-dimensional (3D)-printed implants using Ti-6Al-4V powder; however, multi-root 3D-printed implants have not been fully investigated. The purpose of this study was to explore the stability of multirooted 3D-printed implants with lattice and solid structures. The secondary outcomes were comparisons between the 2 types of 3D-printed implants in micro-computed tomographic and histological analyses.MethodsLattice- and solid-type 3D-printed implants for the left and right mandibular third premolars in beagle dogs were fabricated. Four implants in each group were placed immediately following tooth extraction. Implant stability measurement and periapical X-rays were performed every 2 weeks for 12 weeks. Peri-implant bone volume/tissue volume (BV/TV) and bone mineral density (BMD) were measured by micro-computed tomography. Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were measured in histomorphometric analyses.ResultsAll 4 lattice-type 3D-printed implants survived. Three solid-type 3D-printed implants were removed before the planned sacrifice date due to implant mobility. A slight, gradual increase in implant stability values from implant surgery to 4 weeks after surgery was observed in the lattice-type 3D-printed implants. The marginal bone change of the surviving solid-type 3D-printed implant was approximately 5 mm, whereas the value was approximately 2 mm in the lattice-type 3D-printed implants. BV/TV and BMD in the lattice type 3D-printed implants were similar to those in the surviving solid-type implant. However, BIC and BAFO were lower in the surviving solid-type 3D-printed implant than in the lattice-type 3D-printed implants.ConclusionsWithin the limits of this preclinical study, 3D-printed implants of double-rooted teeth showed high primary stability. However, 3D-printed implants with interlocking structures such as lattices might provide high secondary stability and successful osseointegration.

Are the Insertion Torque Value and Implant Stability Quotient Correlated, and If So, Can Insertion Torque Values Predict Secondary Implant Stability? A Prospective Parallel Cohort Study.

Primary stability is the most important prognostic index for predicting osseointegration. It is generally thought that to achieve high primary stability, it is necessary to insert an implant with a high insertion torque (IT). To date, it has not yet been determined whether IT and implant stability quotient (ISQ) values are correlated. The primary aim of the study was to determine the correlation between IT and ISQ values at the time of implant insertion (T0); at 2 months, the time of healing (T1); and at 6 (T2) and 12 months (T3) after loading. The secondary aims were to determine the influence of different macroscopic implant designs and of a different insertion arch on this correlation; and to assess whether implants inserted with a high IT, that is, > 50 Ncm, had higher levels of implant stability at 2-, 6-, and 12-month follow-ups. STROBE guidelines were followed. Partially or monoedentulous patients were randomly assigned to receive taper thread on straight-body implants with microthreads (group A) or without microthreads (group B). At implant insertion, IT and ISQ values were recorded. At 2-, 6-, and 12-month follow-ups, the ISQ values were recorded. A spring-style torque wrench was used to assess the IT. The Osstell device was used to determine the ISQ values. Descriptive statistics, Pearson correlation, and t test were used. P was set at ≤ .005. Two hundred fifty subjects were assessed; 142 were included. Two hundred sixty-eight implants were inserted (group A, 137 implants; group B, 131 implants). No subject dropped out, and no implant failed. A statistically significant correlation between ISQ and IT was determined at the time of implant insertion (T0; P = .000). The implant morphology and arch did not influence the correlation. An IT > 50 did not determine a higher secondary stability. There is a strong correlation between IT and primary stability, but IT is not correlated with the secondary stability. A different implant macroscopic design and a different arch of insertion did not influence this correlation. Moreover, implants inserted with IT > 50 Ncm do not result in greater secondary stability.

Surgical management of traumatic spondylolisthesis of the axis

Purpose: AThe optimal treatment modality for traumatic spondylolisthesis (TSA) of the axis (second cervical vertebra) remains controversial. Many conservative and anterior techniques have been used to treat these injuries.
 Case report: We describe a 29– year–old woman who presented to the emergency department with severe neck pain after falling down a flight of stairs. Cervical plain radiographs and computer tomography (CT) scan demonstrated a major C2 body anterior dislocation with bilateral C2 pedicle fractures. A Crutchfield extension was applied, with four kilograms of traction initially, with the neck in slight extension. After two hours of traction, plain radiographs showed near–anatomical reduction. The same day the patient underwent an anterior C2/C3 discectomy and autologous bone fusion with a cervical spine locking plate (CSLP). There were no neurological deficits postoperatively and the patient was asymptomatic. She was discharged home on postoperative day eight with a Philadelphia collar for 6 weeks.
 Conclusion: Anterior C2/C3 discectomy and fusion may be feasible and safe in unstable TSA, with the benefit of high primary stability, anatomical reduction, a high union rate, and favorable clinical outcome

Accuracy and primary stability of tapered or straight implants placed into fresh extraction socket using dynamic navigation: a randomized controlled clinical trial.

To compare the accuracy and primary stability of tapered and straight implants undergoing immediate implant placement with dynamic navigation. Patients with compromised anterior teeth in maxilla were recruited and allocated randomly into (1) tapered implant group (TI group) and (2) straight implant group (SI group). Implants were inserted into fresh sockets with dynamic navigation. Three-dimensional platform deviation, apex deviation, angular deviation, insertion torque value (ITV) and implant stability quotient (ISQ) were recorded. Twenty patients with 20 implants were included. The overall platform, apex, and angular deviation were 0.87 ± 0.35mm, 0.81 ± 0.34mm, and 2.40 ± 1.31°, respectively. The accuracy was 0.86 ± 0.26mm, 0.76 ± 0.33mm, and 2.49 ± 1.54° for TI, and 0.89 ± 0.44mm, 0.88 ± 0.36mm, and 2.31 ± 1.01° for SI, with no significant difference (p = 0.85, 0.45, 0.76). Sagittal root position classification (SRP) class I may obtain greater error in numerical values in straight implants (0.97 ± 0.47mm vs. 0.6 ± 0.16mm, 0.92 ± 0.36mm vs. 0.73 ± 0.36mm, 2.48 ± 1.19° vs. 1.71 ± 0.14°). The overall ISQ was 60.74. ISQ was 60.48 for TI and 60.96 for SI, with no significant difference. Acceptable ITV (> 15Ncm) was achieved in most of the included patients (SI 7/10, TI 9/10). High accuracy and primary stability of immediate implant placement could be achieved both in tapered and straight implants with dynamic navigation systems. Tapered and straight implants did not reach a consensus on which was better in immediate implant regarding to accuracy and primary stability. Our study demonstrated implant macrodesign did not affect accuracy and primary stability in immediate implant using dynamic navigation.

Comparing the secondary stability of dental implants: immediate gradual loading versus early loading protocol in the posterior maxilla

Abstract Introduction Loading of dental implants has been performed in different protocols to achieve a high success rate and to decrease oral handicap timing. Many factors can contribute to the proper selection of loading protocol. Objectives This study evaluated the effect of early and immediate gradual loading protocols on the secondary stability of dental implants, which was measured by resonance frequency analysis. Material and Methods Ten patients each received two implants in the posterior maxillary region. At one side implants were loaded by progressive gradual loading using healing caps while the other side implants were loaded by early loading protocol. The secondary stability of dental implants measured using resonance frequency analysis afters 6 weeks from implantation day. Results There was no statistically significant difference between (Progressive loading protocol) and (early loading protocol) groups where (p=0.863). The highest mean value was found in (Progressive loading protocol) (77.86 ± 15.74), while the lowest mean value was found in (early loading protocol) (76.29 ± 17.63). Conclusion Trans mucosal healing is possible in the posterior maxilla with a very high success rate, especially if the implant was inserted with high primary stability. However, strict oral hygiene measure is mandatory to avoid plaque accumulation which may lead to mucositis. Progressive loading with a healing cap is not of a great benefit to the patients in terms of bone training, and it might cause pain while replacing healing caps.

Potential Circumferential Bone Engagement following Tooth Extraction in the Posterior Mandible: Computed Tomography Assessment.

Background and Objectives: Immediate implant placement (IIP) is a popular surgical procedure with a 94.9–98.4% survival rate and 97.8–100% success rate. In the posterior mandible, it poses a risk of injury to adjacent anatomical structures if the implant engages apical bone. This study sought to assess the implant dimensions that allow for circumferential bone engagement at each position in the posterior mandible without additional apical drilling. Materials and Methods: An observational, cross-sectional study design was used. The pre-extraction cone beam computed tomography scans of 100 candidates for IIP were analyzed. Measurements of each root of the posterior mandibular second premolar, first molar, and second molar were taken from three aspects: buccolingual, mesiodistal, and vertical. Two-sided p values < 0.05 were considered statistically significant. Results: A total of 478 mandibular teeth and 781 roots were assessed. Based on Straumann® BLX/BLT implant-drilling protocols, predicted rates of radiological circumferential engagement (RCE) were 96% for implants 5 mm in diameter in the second premolar root position; 94% for implants 4.0–4.2 mm in diameter in the first molar root position; and 99% for implants 4.5–4.8 mm in diameter in the second molar root position. Corresponding rates of achieving an available implant length (AIL) of 10 mm were 99%, 90%, and 86%. Patients <40 years old were at higher risk of lower RCE and lower AIL (p < 0.005) than older patients for all roots measured. Conclusions: The high primary stability prediction rates based on the calculation of RCE and AIL support the use of IIPs without further apical drilling in the posterior mandible in most cases.

Winkelstabile Platte zur Behandlung der Insuffizienzfrakturen des Beckens („minimally invasive posterior locked compression plate“)

OperationszielBelastungsstabile Versorgung des Beckenringes mit hoher Primärstabilität.IndikationInstabilität und ausbleibende Mobilisierbarkeit bei osteoporotischen Beckenbrüchen.KontraindikationenDekubitalgeschwüre, Infekte.OperationstechnikMinimal-invasive winkelstabile Versorgung durch 4,5 LCP (locked compression plate, DePuy Synthes, Zuchwil, Schweiz) von dorsal.WeiterbehandlungSofortige Mobilisation mit Vollbelastung, Röntgenverlaufskontrolle.EvidenzDie Nachuntersuchung eines Kollektivs von 34 Patienten zeigte keine Implantatlockerungen sowie eine vergleichsweise niedrige Strahlenexposition.Video onlineDie Online-Version dieses Beitrags (10.1007/s00113-021-01039-x) enthält das Video zur hier beschriebenen Operationstechnik „Winkelstabile Platte zur Behandlung der Insuffizienzfrakturen des Beckens“.

Evaluation of Insertion Torque and Initial Stability of Single Thread Implants versus Double and Triple Thread Implants: An Animal Study

Aim: This study aimed to evaluate the insertion torque and initial stability of single thread implants versus double and triple thread implants. Methods: Forty two osteotomies were prepared in fresh bovine bone. The implants used in this study were 3 types according to the thread lead design,single thread implant, double and triple thread implants (n=14). Implants were inserted in bone blocks until reaching insertion torques (30 Ncm, 40Ncm and 50Ncm) then calibration of the part of implant inserted within bone was performed. The primary stability was assessed via resonance frequency analysis using the Osstell ISQ device. The removal torque of each implant is measured at torque 50N/cm. intergroup and intragroup comparisons were performed. The significance level was set at p ≤ 0.05 for all tests. Results: Regarding , implant insertion torque the highest value was found in single thread group followed by double thread group, while the lowest value was found in triple thread group. Primary stability results and removal torque revealed that, the highest value were found in triple thread group, followed by double thread group, while the lowest value were found in single thread group and there was a significant difference between different groups (p < 0.001) in all measured outcomes. Conclusions: When primary stability is a concern, as in low bone quality, double and triple threaded implants can provide greater primary stability and insertion torque. Double threaded implants combine optimum insertion speed and high primary stability and insertion torque in compromised situations.

Outcomes of a 1-Year Prospective Single-Arm Cohort Study Using a Novel Macro-Hybrid Implant Design in Extraction Sockets: Part 1.

A novel macro-hybrid implant design was introduced to afford high apical primary stability and more coronal space to preserve the circumferential extraction socket architecture. This study presents 1-year data from a prospective single-arm cohort study. The data was distilled based on the following criteria: (1) single-tooth immediate tooth replacement therapy (ITRT) in the maxillary anterior and premolar regions in intact (Type 1) extraction sockets that were (2) treated with the dual-zone grafting technique. The clinical and radiographic outcomes of 48 ITRT implants were evaluated. The mean ± SD labial plate dimension changes were 0.33 ± 0.41 mm at the implant abutment interface (L1) and 0.34 ± 0.40 mm at 5.0 mm below (L2). The mean labial plate dimension (thickness) at the 1-year recall was 2.27 ± 0.88 mm (L1) and 1.95 ± 0.95 mm (L2). At ITRT, the ridge contour at the free gingival margin and 3.0 mm below it were 7.54 ± 0.93 mm and 9.44 ± 2.36 mm, respectively; after final restoration delivery, the corresponding values were 7.45 ± 0.95 mm and 10.23 ± 2.30 mm, respectively. The peri-implant soft tissue thickness (PISTT) at the time of implant-level impression-making was 3.29 ± 0.73 mm, with an average Pink Esthetic Score of 12.79. A macro-hybrid implant design showed high levels of primary stability (~60 Ncm), stable ridge contour at 1 year, a labial plate dimension between 1.5 and 2.0 mm, and PISTT > 3.0 mm, which may be a critical factor in providing stable, long-term esthetic outcomes.

Double plating - surgical technique and good clinical results in complex and highly unstable proximal humeral fractures

IntroductionA stable fixation of highly unstable proximal humerus fractures remains challenging and complication rates, especially secondary varus dislocation, remains high. Different techniques of double plate osteosynthesis have been suggested for the treatment of complex proximal humeral fractures as they are well established for other fractures. The aim of this study was to evaluate an operative technique using an angular stable lateral plate supported by a one-third tubular plate positioned anteriorly at the lesser tuberosity for unstable proximal humeral fractures. Patients and methodsRetrospectively, patients treated with a double plate osteosynthesis were included between January 2014 and December 2017. Out of 31, 25 patients (80.6%) with an average age of 53.1 years ± 12.5 were available for follow-up. 60% of the patients were male. The clinical evaluation consisted of a physical examination and standardised questionnaire including subjective and objective shoulder scores like the Constant-Murley Shoulder Score, Simple Shoulder Score, and Subjective Shoulder Value. ResultsAfter a mean follow-up of 30.9 months (range, 12-76 months) eighteen patients (72%) had either excellent or good results regarding the Constant-Murley Shoulder Score with a mean value of 77 points ± 17. Average Simple Shoulder Score was 76% ± 0.2 and Subjective Shoulder Value 72% ± 0.2%. Mean NSA at time of follow-up 135° ± 13°. Nine patients had an implant-removal, five in combination with arthrolysis after a mean of 7.2 months. Three patients underwent surgery for secondary arthroplasty. The study shows a complication rate of 16%. No revision-surgery because of secondary varus dislocation was reported. DiscussionArthroplasty is the less favourable treatment for a younger, active cohort of patients with highly unstable proximal humeral fractures as results are not as good and options for revision are limited. Double plate osteosynthesis can be used in addition to calcar screws, bone graft augmentation, cement augmentation and additional free screws for more multidirectional stability and shows good clinical results despite a higher rate of avascular necrosis and high primary stability with comparable complication-rates to single plate osteosynthesis. It seems to be a valid alternative to primary fracture arthroplasty and can prevent secondary varus displacement.

C-Nail versus plate osteosynthesis in displaced intra-articular calcaneal fractures\u2014a comparative retrospective study

BackgroundLocking plate osteosynthesis via an L-shaped lateral approach is the gold standard in treating displaced intra-articular calcaneal fractures. High complication rates are known for this approach. The most frequent complications are wound edge necrosis and superficial wound infections. To reduce complication rates, a locking intramedullary nail (C-Nail) was developed that can be implanted minimally invasively via a sinus tarsi approach.We compared the postoperative complication rate and the outcome of plate osteosynthesis versus C-Nail in displaced intra-articular calcaneal fractures.MethodsAll patients with calcaneal fractures who received osteosynthesis with either plate or C-Nail between January 2016 and October 2019 in our institution were retrospectively analyzed. A subgroup analysis was performed with matched pairs (matching Sanders type, age, Böhler’s angle postoperative in normal range, 33 pairs). Endpoints were postoperative complication rate, bone healing, full weight-bearing and functional outcome. Treatment groups were compared using Fisher’s exact test for binary data, and Mann-Whitney U-test for continuous data. A p-value < 0.05 was considered statistically significant.ResultsOne hundred and one calcaneal fractures were included (C-Nail n = 52, plate n = 49). Patients with C-Nail developed significantly less postoperative complications (p = 0.008), especially wound edge necrosis (p < 0.001). Screw malposition was found more often in the C-Nail group. The rates of achieving full weight-bearing as well as bone healing were comparable in both groups, but in each case significant faster in the C-nail subgroup. The results of the matched-pairs analysis were comparable.ConclusionsThe postoperative complication rate was significantly lower in the C-Nail group. The C-Nail appears to be a successful alternative in the treatment of calcaneal fractures, even in Sanders IV fractures because of the minimal-invasive implantation as well as the high primary stability. Long-term analysis of this new implant including elaboration on functional outcome is planned.Trial registrationDeutsches Register Klinischer Studien (DRKS) DRKS00020395. Date of registration 3 January 2020.

Comparative Evaluation of Primary Stability between Different Diameters Multi-Scale Roughness Dental Implant by Solid Rigid Polyurethane Simulation

Background: Implant primary stability is determined by screw characteristics and surgical procedure. The aim of the present study was to evaluate, on a polyurethane model, the insertion torque (IT), removal torque (RT), and resonance frequency analysis (RFA) of multi-scale roughness dental implants of different diameters. Methods: Two implant sizes were tested on two polyurethane blocks (20 pounds per cubic foot (PCF) and 30 PCF): 3.0 diameter and 13 mm length and 5.0 diameter and 13 mm length. The IT, RT, and RFA were assessed. Results: A significant difference of IT and RT was present in favor of wider implants at both polyurethane densities. No statistical difference was present between the 5.0 diameter and 3.0 diameter implants at both polyurethane densities. A statistically increased RFA was reported for 5.0 implant 30 PCF polyurethane blocks. Conclusions: Multi-scale roughness dental implants of both diameters showed high insertion torque and primary stability on polyurethane blocks, which is valuable for implant loading protocols.

Influence of the dental implant macrogeometry and threads design on primary stability: an in vitro simulation on artificial bone blocks

The implant macrogeometry and thread profile represent one of the most important factors for a successful achievement of primary stability during the positioning procedure. The aim of the present investigation was to evaluate the insertion torque (IT), removal torque (RT) and Implant stability Quotient (ISQ) of two different implant macrogeometry and thread profile on solid rigid polyurethane model. Two different implants macrogeometries were tested: K2 (Group I) with 11° angle, 1.17 mm pitch and self-cutting V thread profile and K3 (Group II) implants with 30° angle, 0.71 mm pitch and spyral thread profile. A total of 120 specimens (n = 60 for each group) were positioned into different conditions of solid rigid polyurethane blocks. The insertion torque (IT), removal torque (RT) and ISQ were measured for each specimen. All specimens achieved the positioning into solid rigid polyurethane blocks for both of groups with no loss of stability. A significantly higher IT, RT and ISQ were detected in Group II (p < 0.05). In both groups the mean values for IT, RT and ISQ appeared promising from a clinical point of view. In spite of different macrogeometry and thread profile, both implant types achieved high primary stability on solid rigid polyurethane block to support the functional loading for a clinical application.

Evaluation of Biomechanical and Stress Distribution of Different Dental Implant Designs: Primary Stability and Photoelastic Analysis

ObjectivesThis study aimed to evaluate and compare the stress distribution and primary stability of three different designs of dental implants. Material and Methods24 implants Neodent® were used (n=8): G1 – Alvim CM; G2 – Drive CM; G3 – Facility, submitted to insertion torque (IT) and pullout test, on 20 PCF (0.24 g/cm3) and 40 PCF (0.64 g/cm3) polyurethane blocks. For the stress distribution, by means of photoelasticity, axial and oblique loads (model at 30° inclination) of 100 N were performed, for reading and quantifying the fringe orders. According to the distribution data, a parametric or non-parametric analysis was performed (α=0.05). ResultsThe IT was lower in G3 (p<0.05) compared to G1 and G2, in 20 and 40 PCF polyurethanes. In the pullout, no difference (p>0.05) was observed between G1 and G2, in both 20 and 40 PCF polyurethanes. In the comparisons between polyurethanes, higher values (p<0.05) were obtained in the 40 PCF for IT and pullout. In the axial loading, lower stresses were observed in the cervical third and higher stresses in the middle and apical third of the implants. With the oblique inclination of the models, higher stresses were generated in the opposite side of the load, in the cervical third of G1, followed by G3 and G2. ConclusionThe results allow to affirm that G1 and G2 exhibit high primary stability and satisfactory stress distribution. Although G3 generates stresses comparable to other implants, its indication is limited in low density bones.

A Long-Term Follow-Up of Post-Operative Periprosthetic Humeral Fracture in Shoulder Arthroplasty.

BackgroundDuring the last decades, the growing number of shoulder replacement has increased the associated complications. Periprosthetic fractures have a low incidence but can be a severe clinical condition, especially in elderly population. There are still no guidelines to define the best treatment protocol for post-operative periprosthetic humeral fractures. Factors associated to these fractures and consequently the decision-making for the best treatment seem to be patient-related but also correlated with the type of implant. The aim of this study is to analyze the patient’s risk factors, fracture pattern, implant type and treatment, evaluating the outcome with a long-term follow-up.MethodsA retrospective study was performed on more than 2700 shoulder prostheses implanted over 10 years in two specialized centers, identifying 19 patients who underwent surgery for post-operative periprosthetic fracture. Gender, age, comorbidities, type of prosthetic implant, type of fracture, and cortical index of each patient were evaluated. All patients underwent surgery and were evaluated with a mean follow-up of 5 years with radiographic controls and functional assessment with the Constant–Murley score.ResultsComplete healing was achieved in 18 of 19 patients. All patients presented a lower Constant–Murley score than the pre-fracture score, there were no significant differences between prosthetic implants, and the cortical index was lower than the threshold level in more than 60% of cases.ConclusionThe results of this study showed that a correct preoperative planning is essential to evaluate the type of implant and possible signs of stem mobilization. With a stable stem, it is preferable to maintain it and proceed to a synthesis. The decision process is more complex in periprosthetic fractures with a reduced cortical index, when some radiolucency lines are present in stems with high primary stability, because it is not always indicative of an unstable stem.Level of EvidenceTherapeutic III

Treatment of a Displaced Occipital Condyle Fracture - A Case to be discussed

Before the advent of computed tomography, occipital condyle injuries were solely a postmortem diagnosis. Nowadays, CT is well established in the diagnostic workflow of trauma management, allowing accurate planning and proper treatment. Anderson and Montesano as well Tuli developed radiologic classifications, each based on a small number of cases, in regards to the stability of the lesion and also provided treatment recommendations. In this case study we present a 24-year-old man suffering massive trauma to the head and thorax from a agricultural vehicle accident, leading to a displaced avulsion fracture of the right occipital condyle with high atlanto-occipital instability (Anderson Montesano type III). However, the patient did not develop any neurological deficit. Within the scope of the damage control polytrauma algorithm, the atlanto-occipital instability was initially stabilized in a HALO fixator. For devinitive treatment, we decided on an internal occipito-cervical fixation with a permanent fusion of the injured C0/C1-segment without reduction of the dislocated fragment at a time 14 days after the accident. The fixation construct spanned from the occiput to C3 in order to achieve a high primary stability. At 3-months follow-up, CT scans showed bony healing of the right condyle in an unchanged displaced position and a successful posterior fusion of C0/C1. After one year, a complete implant removal was done.