Hook Group Research Articles

A Comparative evaluation of stress distribution in bone and mini-implant during en-masse retraction of anterior teeth in maxilla using forces from anchorage units (mini-implants and molar hook) to both canine hook and arch wire hook. An FEM study

The study aimed to compare and evaluate the stress that was distributed around mini-implant, molar hook and anterior dentition during its en-masse retraction from both canine hook and arch-wire hook. Four FEM models of maxilla were created to carry out en-masse retraction of the anterior teeth using forces from mini-implant and molar hook to both arch-wire hook and canine hook. The force of 200 grams was applied with Ni-Ti closed coil spring in all four models to carry out anterior teeth retraction. Stress distribution were then analyzed. The mini-implant group showed higher stresses on the implant when compared to the molar hook group. The molar hook groups showed more stress on the dentition than that of the mini-implant group. The models where the arch-wire hook used for retraction showed less stress values on the bone, teeth, dentition, PDL when compared with that of the canine hook.The arch-wire hook can be considered a better option than the canine hook. When forces were applied to the arch-wire hook lesser stresses were seen on bone, teeth, dentition, and PDL. The implant-supported group showed lesser stress values on teeth when compared with that of the molar hook group.

Intraoperative and early postoperative pain in cats that underwent ovariohysterectomy using a spay hook: a randomised, masked, experimental study

BackgroundThis study aimed to compare the feasibility and practicality of the ovariohysterectomy (OHE) technique in cats with or without a spay hook with respect to the incision size, surgical time, surgical variables, and intra- and postoperative pain. Twenty-nine female cats underwent OHE using a spay hook (spay hook group [SHG], n = 15) or without using a spay hook (control group [CG], n = 14) to achieve the ovaries and cervix. Physiological parameters were monitored during the intraoperative period, and postoperative pain was assessed using a multidimensional composite and visual analogue pain scales.ResultsThe SHG had a significantly shorter operative time than the CG. The variables in the intraoperative period showed no statistically significant difference between both groups, as well as the early postoperative pain.ConclusionsLess invasive OHE using a spay hook could potentially be a viable and feasible technique when performed by an inexperienced surgeon with appropriate training, especially in sterilisation campaigns, reducing the time to perform the procedure and increasing the number of animals spayed per time.

Can placement of hook at the upper instrumented level decrease the proximal junctional kyphosis risk in adolescent idiopathic scoliosis?

Proximal junctional kyphosis is a commonly encountered clinical and radiographic phenomenon after pediatric and adolescent spinal deformity surgery that may lead to postoperative deformity, pain, and dissatisfaction. The purpose of the study was to identify whether the placement of transverse process hooks is an effective way to prevent PJK. Adolescent idiopathic scoliosis patients who underwent posterior spinal fusion between November 2015 and May 2019 were retrospectively analyzed. A minimum 2-year follow-up was required. Demographic and surgical data included UIV level type of instrumentation (hook vs screw) were reported. Radiologic parameters included main curve Cobb angle, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), and proximal junctional angle (PJA) were assessed. Patients were divided into two groups based on the type of instrumentation at the UIV level whether placement of hook versus pedicle screw. Three hundred and thirty-seven patients were included with the mean age 14.2 ± 1.9years. Thirty patients (8.9%) were diagnosed with proximal junctional kyphosis radiographically. PJK incidence was found 3.2% (5/154) in the hook group and 13.3% (23/172) in the screw group and the difference found statistically significant. In the PJK group, preoperative thoracic kyphosis and the degree of kyphosis correction were also significantly higher than non-PJK patients. Placement of transverse process hooks at the UIV level in posterior spinal fusion surgery for AIS patients was associated with decreased risk of PJK. A larger preoperative kyphosis and greater degree of kyphosis correction correlated with PJK.

Development of New Die Design in Towing Hook Production

In this study, a new design has been developed for towing hook dies used in hot forging processes. For this objective, analysis studies were carried out with different process parameters and methods for new designs in dies for both hot forging process and product. After the analysis, the die designs were determined that produced the prototype products at the optimum speed, efficiency and quality. While designing a special die for hot forging operation, a new die design has been developed in which both processes can be performed using a single die with two stages, pre-shape and final shape. Compared to the dies studied for hook groups in the literature and our old dies currently being worked, it is aimed to eliminate the errors caused by the inability to calibrate the final shape such as early wear, short die life, burr residue formation. Such a technics specific to the part as specific to the towing hook was performed for the first time, and with the die design developed by comparing the results of analysis studies, field trials and prototype studies in the Q-Form simulation program, the production of towing hook at optimum efficiency was achieved.

Utilization of S1 Foraminal Hooks for Augmentation of S1 Screws in Adult Spinal Deformity Surgery: Comparative Study With Iliac Screws.

ObjectiveTo compare the outcomes of S1 foraminal hooks and iliac screws regarding fusion rate at the lumbosacral junction and protective effects on S1 screws. MethodsFrom January 2017 to December 2019, consecutive patients who underwent long fusions (uppermost instrumented vertebra at or above L1) to the sacrum for adult spinal deformity were enrolled. Patients were divided into S1 foraminal hook group and iliac screw group. Radiographic parameters and the incidence of pseudarthrosis and instrument failure at the lumbosacral junction were compared between the groups. ResultsTwenty-nine patients (male:female = 1:28) with a mean age of 73.6±6.8 years were evaluated. Sixteen patients (55.2%) had S1 foraminal hook fixation and 13 patients (44.8%) had iliac screw fixation. Lumbar lordosis, sacral slope, and sagittal vertical axis did not differ between the groups preoperatively and postoperatively. The rate of L5/S1 pseudarthrosis was significantly higher in S1 foraminal hook group (5 of 16, 31.3%), compared to iliac screw group (0 of 13, 0%; p=0.048). Instrument failure at the lumbosacral junction trended toward a higher rate in S1 foraminal hook group (6 of 16, 37.5%) than in iliac screw group (1 of 13, 7.7%), without statistical significance (p=0.09). Proximal junctional kyphosis/failure occurred less often in S1 foraminal hook group (2 of 16, 12.5%) than in iliac screw group (3 of 13, 30.8%) without statistical significance (p=0.36). ConclusionTreatment with S1 foraminal hooks achieved equivalent satisfactory sagittal correction with proportioned alignment compared to that with iliac screws. However, S1 foraminal hooks did not provide enough structural support to the lumbosacral junction in long fusions to the sacrum.

Shoulder Balance Following Correction Surgery for Adolescent Idiopathic Scoliosis: When Is It Achieved and Does the Type of Construct Matter?

This is a retrospective study. This study aims to determine (1) when shoulder rebalancing occurs after adolescent idiopathic scoliosis (AIS) correction surgery and (2) whether shoulder asymmetry was influenced by the use of pedicle screws or hooks. Postoperative shoulder imbalance is an important outcome of AIS correction surgery as it may influence a patient's appearance and satisfaction. Seventy AIS patients undergoing AIS correction surgery at a single institution were retrospectively reviewed. Radiographic parameters were measured from anteroposterior x-rays at preoperative, immediate postoperative, 6 months postsurgery, and 12 months postsurgery. Shoulder parameters measured were: radiographic shoulder height (RSH), clavicle angle, coracoid height difference (CHD), and T1 tilt. The Cobb angle of the proximal thoracic curve, major thoracic curve, and thoracolumbar/lumbar curve. The percentage of correction was also calculated. Lateral shoulder asymmetry (RSH and CHD) changed significantly from preoperative to up to 6 months postsurgery. T1 tilt, a measure of medial shoulder asymmetry, did not change significantly. Postoperatively, the hook group attained significantly better shoulder balance than the screw group in terms of RSH and CHD up to 12 months postsurgery. However, the percentage correction of the major thoracic curve was significantly greater in the screw group than the hook group (hook: 62.2±18.4% vs. screw: 76.0±16.0%, P=0.007). Lateral shoulder rebalancing occurs up to 6 months after surgery. While thoracic pedicle screws offer greater correction of major AIS curves, hook constructs offer better postoperative shoulder symmetry. III.

Evaluation of an occipito-cervico fusion with a new implant design: a biomechanical study

BackgroundA novel implant for occipitocervical fusion consisting of a median plate with an additional hook inserting in the foramen magnum was tested. Aim of this study was to test the stability of a new implant for occipitocervical fusion against the already available and employed median plate implant without hook.Material and method36 rigid polyurethane foams occipital artificial bones were used. The two occipital implants, namely the occipital plate with hook (Group 1) and the one without hook (Group 2), were applied to the artificial occiput trough three occipital screws and ensured into the experimental setup trough a crossbar. The test parameters were set using the testing machine software as follows: (1) test speed: 10 mm/ min, with 25 mm/ min maximum; (2) preload: 5 N; (3) force switch-off threshold: 90% force drop from F_max. Failure force and path were recorded. Failure force is defined as the maximum reaction force under which failure occurs (F_max), while failure path is the travel path during which failure occurs (dL).ResultsGroup 1 (plate with hook) showed a mean failure force of 459.3 ± 35.9 N and a mean failure path of 5.8 ± 0.3 mm Group 2 (plate without hook) showed a mean failure force of 323.9 ± 20.2 N and a mean failure path of 7.2 ± 0.4 mm. The Shapiro-Wilk test score was not significant (P > 0.1), assuming that data were normally distributed. Group 1 had a statistically significant greater F_max (+ 135.37; P > 0.0001) and less dL (− 1.52; P > 0.0001) compared to group 2.ConclusionsMedial plates with foramen magnum hooks showed to be more stable that plates without a hook. These new implants may represent a new tool in OCJ fixation, but further studies are required to investigate their behavior in an anatomical setting.

Anchor type at upper instrumented vertebra and postoperative shoulder imbalance in patients with Lenke type 1 adolescent idiopathic scoliosis.

To clarify the impact of anchor type at upper instrumented vertebra (UIV) on postoperative shoulder imbalance in patients with Lenke type 1 adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion. Subjects were 81 patients with Lenke type 1 AIS who underwent posterior spinal fusion between 2004 and 2013. Twenty-five patients agreed to participate in the study. We divided the patients into two groups: Hook group (15 patients with hooks at UIV who underwent surgery between 2004 and 2011) and PS group (ten patients with pedicle screws at UIV who underwent surgery between 2012 and 2013). To evaluate shoulder balance, first thoracic vertebra tilt angle (T1 tilt), clavicle angle (CA), and radiographic shoulder height (RSH) were measured. There were no significant differences in preoperative T1 tilt, CA, or RSH between the both groups. The postoperative 1-week, 2-year, and most recently observed T1 tilts were significantly smaller in the Hook group than in the PS group. There were no significant differences in postoperative 1-week, 2-year, and most recently observed CAs between the two groups. Although there were no significant differences in 1-week postoperative RSH between the groups, the 2-year postoperative RSH was significantly smaller in the Hook group than in the PS group. The most recently observed RSH tended to be smaller in the Hook group than in the PS group, but the difference was not significant. In the PS group, poor shoulder balance remained over the long term. The hooks at UIV adjusted postoperative shoulder balance.

Pelvic Obliquity Correction in Distraction-Based Growth Friendly Implants

DesignMulticenter retrospective review. ObjectiveTo evaluate radiographic outcomes and complication rates of patients treated with distraction based implants and pelvic fixation with either screws (sacral-alar-iliac [SAI] screws or iliac screws) or hooks (S hook iliac fixation). Summary of Background DataMultiple options exist for pelvic fixation in distraction-based growing rod systems; however, limited comparative data are available. MethodsEarly-onset scoliosis (EOS) patients of all diagnoses with distraction-based implants that had pelvic fixation from 2000 to 2013 were reviewed from two EOS multicenter databases. Patients were divided into two groups by type of pelvic fixation: (1) screw group (SAI screws or iliac screws) or (2) S hooks. Exclusion criteria were as follows: index instrumentation ≥10 years old and follow up <2 years. A total of 153 patients met the inclusion criteria. Mean age at index surgery was 6.1 years (range 1.0-9.9 years) and mean follow-up was 4.9 years. ResultsPelvic fixation in the 153 patients was as follows: screw group = 42 and S hook group = 111. When comparing patients with >20° of initial pelvic obliquity, the screw group had significantly more correction; mean 26° ± 13° for the screw group versus mean 17° ± 7° in the S hook group (p = .039). There was no significant difference in change in T1–S1 length (40 vs. 39 mm, p = .89) or correction of Cobb angle (30° vs. 24°, p = .24). The total complication rate for the screw group was 14% (6/42) versus 25% (28/111) in the S hook group, though this did not achieve significance (p = .25). The most common complications were device migration (13), implant failure (8), and implant prominence (4) for S hooks and implant failure (3), implant prominence (2), and device migration (1) for the screw group. ConclusionIn distraction-based growth-friendly constructs, pelvic fixation with screws achieved better correction of pelvic obliquity than S hooks. Complications were almost twice as common with S hooks than screws, though this did not reach statistical significance.

Comparison of the MyoRing implantation depth by mechanical dissection using PocketMaker microkeratome versus Melles\xa0hook via AS-OCT

BackgroundThis paper seeks to evaluate the depth and outcomes of MyoRing implantation using two mechanical dissection procedures including: PocketMaker microkeratome in opposition to the Melles hook method.MethodsThis retrospective study was carried out on 39 eyes of 38 keratoconus patients (28 male and 10 female) with the mean age of 28.97frac{+}{.}10.37 years and had undergone MyoRing implantation by the two mentioned methods. The MyoRing was inserted into the corneal pocket which was made manually in 18 eyes (Melles hook group) or with PocketMaker microkeratome in 21 eyes (PocketMaker group). The mean follow up time was 9.81frac{+}{.}3.7 months with pre-operative and post-operative ophthalmic examination including uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), keratometry readings and central corneal thickness measurement. AS-OCT (Casia, SS-1000, Tomey, Nagoya, Japan) imaging was used to measure MyoRing insertion depth, exactly.ResultsPre-operative and post-operative UCVA (LogMAR) mean change for the PocketMaker and Melles hook groups were recorded at 0.75 ± 0.32 and 0.78 ± 0.33, respectively. Similarly, BCVA (LogMAR) mean change were 0.27 ± 0.22 and 0.23 ± 0.22. Mean keratometry (Kmean) change were 6.06 ± 4.18 and 6.56 ± 3.55 respectively. UCVA change (P = 0.767), BCVA change (P = 0.77) and Kmean change (P = 0.693) showed that there was no statistically significant difference between both groups for any parameter. Depth measurements achieved from AS-OCT images showed that there was no statistically significant difference in pocket depth between two methods of MyoRing implantation (P = 0.413).ConclusionsThe results of Myoring implantation outcomes using mechanical dissection via PocketMaker microkeratome as against Melles hook are comparable.

(1 + 1) Newton–Hooke group for the simple and damped harmonic oscillator

It is demonstrated that, in the framework of the orbit method, a simple and damped harmonic oscillator is indistinguishable at the level of an abstract Lie algebra. This opens a possibility for treating the dissipative systems within the orbit method. An in-depth analysis of the coadjoint orbits of the (1 + 1) dimensional Newton-Hooke group is presented. Furthermore, it is argued that the physical interpretation is carried by a specific realisation of the Lie algebra of smooth functions on a phase space rather than by an abstract Lie algebra.

Utility of the Ginza forceps for superficial phlebectomy during endovenous laser ablation of the great saphenous vein.

To evaluate the efficiency of using the Ginza forceps (DVx, Tokyo, Japan), which have a long shaft and strong grip, for superficial phlebectomy with the stab avulsion technique, during simultaneous endovenous laser ablation (EVLA) of the great saphenous vein (GSV). The subjects were patients treated with EVLA performed by a single operator at one institution. All patients had a GSV diameter of 4-10mm and an EVLA length of the GSV of >20cm. We compared 59 limbs treated only with the Varady hook (Group A) with 46 limbs treated with the Ginza forceps (Group G). The mean operative times for Groups A and G were 55.4±17.1 vs. 48.5±13.5min, respectively (P=0.002), and the number of stab incisions was 5.9±2.9 (1-13) vs. 3.5±2.3 (1-11), respectively (P<0.001). The rates of nerve injury and thrombophlebitis were 1.7 vs. 0 and 3.4 vs. 0%, respectively. Performing superficial phlebectomy with the Ginza forceps reduced the operation time and the number of stab wounds. These initial results suggest that using the Ginza forceps for the procedure is safe and efficient.

Hybrid Instrumentation in Lumbar Spinal Fusion: A Biomechanical Evaluation of Three Different Instrumentation Techniques.

Study DesignEx vivo human cadaveric study.ObjectiveThe development or progression of adjacent segment disease (ASD) after spine stabilization and fusion is a major problem in spine surgery. Apart from optimal balancing of the sagittal profile, dynamic instrumentation is often suggested to prevent or impede ASD. Hybrid instrumentation is used to gain stabilization while allowing motion to avoid hypermobility in the adjacent segment. In this biomechanical study, the effects of two different hybrid instrumentations on human cadaver spines were evaluated and compared with a rigid instrumentation.MethodsEighteen human cadaver spines (T11–L5) were subdivided into three groups: rigid, dynamic, and hook comprising six spines each. Clinical parameters and initial mechanical characteristics were consistent among groups. All specimens received rigid fixation from L3–L5 followed by application of a free bending load of extension and flexion. The range of motion (ROM) for every segment was evaluated. For the rigid group, further rigid fixation from L1–L5 was applied. A dynamic Elaspine system (Spinelab AG, Winterthur, Switzerland) was applied from L1 to L3 for the dynamic group, and the hook group was instrumented with additional laminar hooks at L1–L3. ROM was then evaluated again.ResultsThere was no significant difference in ROM among the three instrumentation techniques.ConclusionBased on this data, the intended advantage of a hybrid or dynamic instrumentation might not be achieved.

A pedicle screw system and a lamina hook system provide similar primary and long-term stability: a biomechanical in vitro study with quasi-static and dynamic loading conditions.

For the stabilization of the thoracolumbar spine area, various stabilization techniques have been developed in recent decades. The aim of these techniques is to immobilize the treated segment to repositioning or correct the spine and guaranty long-term stability to achieve a reliable fusion. The aim of this study was to simulate in an in vitro experiment the postoperative long-term situation in elderly osteoporotic patients to compare two different stabilization principles; a pedicle screw system and a lamina hook system. Two comparable groups with respect to age and bone mineral density with each n=6 fresh-frozen human, bi-segmental thoracolumbar spine specimens (T11-L1) were used. Antero-posterior and lateral radiographs were taken before the test, to assess the spinal status. Then the intact specimens were biomechanically characterized with pure moments in the three anatomical planes in different states in terms of range of motion and neutral zone. After implantation of either, a pedicle screw system or a lamina hook system, the primary stability was determined under the same conditions. Subsequently the specimens were cyclically loaded under complex loading, using a custom-made set-up in a dynamic materials testing machine with increasing moments from 3 to 66Nm until 100,000 cycles or until one of the three defined "failure" criteria was reached. (1) A failure of a bony structure. (2) Exceeding of the threefold ROM of the primary stability after implantation in flexion plus extension. (3) Reaching of the ROM based on the intact state before implantation both in flexion plus extension. The results showed that the ROM was strongly reduced after instrumentation similar for both implant systems in all motion planes. The highest stabilization was found in flexion/extension. During cyclic loading with increasing moments, the ROM increased continuously for both systems. The number of load cycles until one of the failure criteria was reached varied only slightly between the two groups. In the pedicle screw group 30,000 (median) loading cycles (range 5000-80,000) with a corresponding moment of 24Nm (range 9-54) could be reached. In the lamina hook group 32,500 load cycles (range 20,000-45,000) could be achieved with a corresponding moment of 25.5Nm (range 18-33). There was a slight trend that the pedicle screw system is influenced more by bone mineral density. Both implant systems provide similar primary stability and similar long-term stability. In the pedicle screw group, there was a stronger correlation between bone mineral density and the reached number of load cycles.

A Novel Fluoroscopic View for Positioning the AO Clavicle Hook Plate Decreases Its Associated in situ Complications

Background: The goal of this study was to evaluate whether a modified fluoroscopic technique for positioning a hook plate affected the clinical results of treating Neer type II distal clavicle fractures and Rockwood type V acromioclavicular (AC) joint separations with this device. Methods: The study was a retrospective consecutive case series with data analysis. Sixty-four patients with a Neer type II distal clavicle fracture or a Rockwood type V AC joint injury treated between March 2009 and June 2013 were divided into 2 groups: traditional fluoroscopic technique (traditional view, 31 patients) or modified fluoroscopic technique (‘hook’ view, 33 patients). A visual analogue scale (VAS) score, the modified University of California-Los Angeles (UCLA) shoulder scale score, and radiographic osteolysis were the main outcome measures. Results: The traditional group included a significantly larger number of patients with acromial osteolysis than the hook view group: 23 patients (74.2%) vs. 11 patients (33.3%), respectively (p=0.01). Before plate removal, the hook group reported less pain and higher UCLA shoulder scale scores than the traditional group: average VAS score, 1.55 vs. 2.26, respectively; average UCLA score, 30.88 vs. 27.06, respectively. However, there was no significant difference after plate removal. Conclusions: The hook view allows more accurate bending of the hook plate around the contour of the acromion, resulting in decreased osteolysis, decreased pain, and better function with the plate in situ.

Traitement des disjonctions acromioclaviculaires sévères aiguës : la stabilisation arthroscopique non rigide procure une meilleure qualité de vie que l’ostéosynthèse par plaque crochet

IntroductionTreatment of acute high-grade acromioclavicular joint (ACJ) injuries with metal-hardware alters the biomechanics of the ACJ, implying a second surgery for hardware removal. The period during which the plate is present involves functional limitations, pain and a risk factor for the development of hardware-related injuries. Arthroscopy-assisted procedures compared to open-metal-hardware techniques offer: less morbidity, the possibility to treat associated lesions and no need for a second operation. The aim was to compare the quality of life (QoL) of patients with acute high-grade ACJ injuries (Rockwood grade III–V), managed arthroscopically with a non-rigid coracoclavicular (CC) fixation versus the QoL of patients managed with a hook plate, 24months or more after their shoulder injury. Patients and methodsA retrospective revision of high-grade ACJ injuries managed in three institutions was performed. Patients treated by means of an arthroscopy-assisted CC fixation or by means of a hook plate were included. The inclusion period was between 2008 and 2012. The QoL was evaluated at the last follow-up visit by means of the SF36, the visual analog scale (VAS), the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, the Constant score and the global satisfaction (scale from 0 to 10). The presence of scapular dyskinesis and remaining vertical instability were evaluated. Comparison between groups was performed. ResultsThirty-one patients were included: 20 arthroscopy group (ARTH group: 3 Rockwood III, 3 IV and 14 V) and 11 hook plate group (HOOK group: 5 Rockwood III and 6 V). The mean age was 36 [25–52] years old for the ARTH group and 41 [19–55] for the HOOK group (P=0.185). The mean results of the questionnaires were: (1) physical SF36 score (ARTH group 58.24±2.16 and HOOK group 53.70±4.33, P<0.001); (2) mental SF36 score (ARTH group 56.15±2.21 and HOOK group 53.06±6.10, P=0.049); (3) VAS (ARTH group 0.40±0.50 and HOOK group 1.45±1.51, P=0.007); (4) DASH (ARTH group 2.98±2.03 and HOOK group 4.79±5.60, P=0.200); (5) Constant score (ARTH group 95.30±2.45 and HOOK group 91.36±6.84, P=0.026); (6) global satisfaction (ARTH group 8.85±0.93 and HOOK group 8.00±1.18, P=0.035). There was evidence of scapular dyskinesis in 15% (3/20) of the patients of the ARTH group and in 18% (2/11) of the patients of the HOOK group (P=1.000). Remaining vertical ACJ instability was observed in 40% (8/20) of the patients of the ARTH group and in 36.36% (4/11) of the patients of the HOOK group (P=1.000). ConclusionPatients with acute high-grade ACJ injuries managed arthroscopically with a non-rigid CC fixation seem to have a better QoL than patients managed with a hook plate. Level of evidenceLevel IV. Therapeutic; retrospective comparative study.

Acute high-grade acromioclavicular joint injuries treatment: Arthroscopic non-rigid coracoclavicular fixation provides better quality of life outcomes than hook plate ORIF

IntroductionTreatment of acute high-grade acromioclavicular joint (ACJ) injuries with metal hardware alters the biomechanics of the ACJ, implying a second surgery for hardware removal. The period during which the plate is present involves functional limitations, pain and a risk factor for the development of hardware-related-injuries. Arthroscopy-assisted procedures compared to open-metal hardware techniques offer: less morbidity, the possibility to treat associated lesions and no need for a second operation. The aim was to compare the Quality of life (QoL) of patients with acute high-grade ACJ injuries (Rockwood grade III–V), managed arthroscopically with a non-rigid coracoclavicular (CC) fixation versus the QoL of patients managed with a hook plate, 24 months or more after their shoulder injury. Patients and methodsA retrospective revision of high-grade ACJ injuries managed in three institutions was performed. Patients treated by means of an arthroscopy-assisted CC fixation or by means of a hook plate were included. The inclusion period was between 2008 and 2012. The QoL was evaluated at the last follow-up visit by means of the SF36, the visual analog scale (VAS), the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, the Constant score and the global satisfaction (scale from 0 to 10). The presence of scapular dyskinesis and remaining vertical instability were evaluated. Comparison between groups was performed. ResultsThirty-one patients were included: 20 arthroscopy-group (ARTH group: 3 Rockwood III, 3 IV and 14 V) and 11 hook plate-group (HOOK group: 5 Rockwood III and 6 V). The mean age was 36 [25–52] year-old for the ARTH group and 41 [19–55] for the HOOK group (P=0.185). The mean results of the questionnaires were: (1) physical SF36 score (ARTH group 58.24±2.16 and HOOK group 53.70±4.33, P<0.001); (2) mental SF36 score (ARTH group 56.15±2.21 and HOOK group 53.06±6.10, P=0.049); (3) VAS (ARTH group 0.40±0.50 and HOOK group 1.45±1.51, P=0.007); (4) DASH (ARTH group 2.98±2.03 and HOOK group 4.79±5.60, P=0.200); (5) Constant score (ARTH group 95.30±2.45 and HOOK group 91.36±6.84, P=0.026); (6) global satisfaction (ARTH group 8.85±0.93 and HOOK group 8.00±1.18, P=0.035). There was evidence of scapular dyskinesis in 15% (3/20) of the patients of the ARTH group and in 18% (2/11) of the patients of the HOOK group (P=1.000). Remaining vertical ACJ instability was observed in 40% (8/20) of the patients of the ARTH group and in 36.36% (4/11) of the patients of the HOOK group (P=1.000). ConclusionPatients with acute high-grade ACJ injuries managed arthroscopically with a non-rigid CC fixation seem to have a better QoL than patients managed with a hook plate. Level of evidenceLevel IV therapeutic; retrospective comparative study.

Implant and spinal mobility influence on the spinal curvature correction in adolescent idiopathic Lenke I type scoliosis

Background and objectiveThere are still a few researches accomplished to evaluate the advantages and disadvantages of screw, hybrid, and hook techniques in the treatment of adolescent idiopathic scoliosis. As the results are controversial, researchers still look for optimally safe, least traumatizing and economically reasonable methods to treat spinal deformities. The aim of this study is to analyze postoperative spine deformity correction results for Lenke type 1 dependent on fixation type and preoperative bending films.Patients and methodsA retrospective study was performed. Patients admitted to the Children’s Hospital, Affiliate of Vilnius University Hospital Santariskiu Klinikos Orthopedic Department in the period of 1994–2013 were included; 74 cases were analyzed. Three groups according to spine implants were generated. The first included patients treated with pedicle screw fixation, the second – hybrid, and the third – hook fixation. Inclusion criteria: the adolescent age group (10–18), idiopathic scoliosis Lenke I type who undergone posterior spinal fusion with pedicle screws; hybrid fixation and hook application were evaluated in order to compare curve correction dependence on fixation type and curve flexibility. Thoracic and lumbar curve measurements on the coronal plane were performed using the Cobb technique applied on anterior posterior radiographs taken before and two days after surgery. Also, to measure curve flexibility, preoperative passive standing bending films were analyzed. Curve degrees in preoperative passive bending films were compared with the remaining postoperative spinal curves in groups separately. The remaining postoperative curves were compared respectively. ResultsIn total, 74 cases met the inclusion criteria, of them 67 (90.50%) girls and 7 (9.50%) boys. The mean preoperative thoracic Cobb angle was 51.07º (±6.20) in the screw group, 52.88º (±7.26) in the hybrid and 55.45º (±10.94) in the hook group. To compare the preoperative stiffness of the curves, the flexibility % was calculated, with no difference in the groups (p &gt; 0.05). The mean postoperative thoracic Cobb curve angle was 15.81º (±5.28), 21.63º (±6.89), and 27.55º (±8.25), respectively. The mean correction of the thoracic curve was 68.87% in the screw group, 58.76% in the hybrid and 50.27% in the hook group. The mean preoperative lumbar curve Cobb angle was 32.07º (±5.73) in the screw group, 32.50º (±12.33) in the hybrid and 34.74º (±7.50) in the hook group. The mean postoperative lumbar curve Cobb angle was 7.59º (±6.63), 10.94º (±7.52), and 16.06º (±6.89), respectively. The mean correction of the lumbar curve was 75.58% in the screw group, 66.27% in the hybrid and 53.53% in the hook group. The fixation level according to groups: screw Th4-L1, hybrid Th3-L3, hook Th3-L3. ConclusionsThe thoracic curve tends to recover more than the curve remaining in the lateral bending film. Only screw fixation is able to correct the lumbar curve for the Lenke type 1 as it is expected in the remaining lateral bending curve. Thoracic and lumbar deformity using screw fixation recovers on the average by 20% more than hook and by 10% more than hybrid application. The pedicular screw construct is shorter and is able to correct the thoracic curve whatever the modifier type (A, B or C); however, the lumbar curve correction drops when the modifier type is B or C. The other operative methods are less effective to correct both thoracic and lumbar curves whatever the modifier type and also tend to lose the correction % for types 1B or 1C.

Type of Anchor at the Proximal Fusion Level Has a Significant Effect on the Incidence of Proximal Junctional Kyphosis and Outcome in Adults After Long Posterior Spinal Fusion

Study DesignRetrospective review. ObjectivesTo compare the incidence of proximal junctional kyphosis (PJK) and the clinical, radiographic, and functional outcomes in adults undergoing long posterior spinal fusion with transverse process hooks versus pedicle screws at the uppermost instrumented vertebrae. Summary of Background DataProximal junctional kyphosis often occurs after instrumented long spinal fusion. Although there have been numerous studies of PJK development in adolescents with idiopathic scoliosis, few studies have focused on adults. MethodsThis study reviewed data on 47 consecutive adult patients who underwent long spinal fusion (five or more levels) with hooks or screws at the uppermost instrumented vertebrae, from 2004 through 2009, and had 2-year radiographic and clinical follow-up. The hook group (20 patients) and screw group (27 patients) were similar in terms of age, gender, and levels fused. Proximal junctional kyphosis was defined as a sagittal Cobb angle of at least 10° between the lower end plate of the uppermost instrumented vertebrae and the upper end plate of the 2 immediately superior vertebrae, and at least 10° of progression from the previous measurement. The groups' radiographs, complications, and functional outcomes (Scoliosis Research Society–22 Patient Questionnaire and the Oswestry Disability Index) were compared using Hotelling's t2 test (significance, p < .05). ResultsComparing immediate postoperative and final follow-ups, none of the 20 patients in the hook group versus 8 of 27 patients in the screw group (29.6%) developed PJK (p = .01). There were no statistical differences between groups in major or minor complications rates. At final follow-up, patients with hooks had significantly higher functional scores than those with screws (p < .05), and patients with PJK had significantly lower functional scores in all Scoliosis Research Society–22 Patient Questionnaire domains except satisfaction. ConclusionsTransverse process hooks were associated with a lower incidence of PJK and higher functional scores than pedicle screws.

Dynamical realizations of l-conformal Newton–Hooke group

The method of nonlinear realizations and the technique previously developed in [A. Galajinsky, I. Masterov, Nucl. Phys. B 866 (2013) 212, arXiv:1208.1403] are used to construct a dynamical system without higher derivative terms, which holds invariant under the l-conformal Newton–Hooke group. A configuration space of the model involves coordinates, which parametrize a particle moving in d spatial dimensions and a conformal mode, which gives rise to an effective external field. The dynamical system describes a generalized multi-dimensional oscillator, which undergoes accelerated/decelerated motion in an ellipse in accord with evolution of the conformal mode. Higher derivative formulations are discussed as well. It is demonstrated that the multi-dimensional Pais–Uhlenbeck oscillator enjoys the l=32-conformal Newton–Hooke symmetry for a particular choice of its frequencies.