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Biomedical subjects

M Blauth

Publications and source records attributed to M Blauth.

At least 37 records · Page 2Linked to original sources

Three-dimensional motion analysis with Synex. Comparative biomechanical test series with a new vertebral body replacement for the thoracolumbar spine.

The authors present a new implant for vertebral body replacement in the thoracic and lumbar spine. Synex is a titanium implant designated for reconstruction of the anterior column in injury, post-traumatic kyphosis or tumour of the thoracolumbar spine and must be supplemented by a stabilizing implant. After positioning, the implant is distracted in situ, thus ensuring best contact with adjacent end-plates and three-dimensional (3D) stability, and minimizing the possibility of secondary dislocation or loss of correction. We compared the effectiveness of the Synex implant with that of the "Harms cage" (MOSS) in combination with two alternative stabilizing instrumentations: the USS and Ventrofix. In a 3D spinal loading simulator, we determined the bisegmental (T12-L2) neutral zone (NZ), elastic zone (EZ), and range of motion (ROM) of 12 human cadaveric spines. After corpectomy of L1, we tested the four possible combinations of stabilizing instrumentation and vertebral replacement implant: USS/Synex, USS/MOSS, Ventrofix/Synex, Ventrofix/MOSS. We analysed the differences between each of the instrumentations as well as differences compared to the intact spine. Comparing the two stabilizing implants, a significantly higher stability was achieved with the USS for flexion, extension, and lateral bending, regardless of whether Synex or MOSS was used as vertebral body replacement. No differences were observed for axial rotation. In addition, no implant combination was able to restore the rotational stability of the intact spine. Comparing the vertebral body replacing implants, significantly higher stability was noted with Synex in combination with USS for extension, lateral bending, and axial rotation. No differences between Synex and MOSS were observed in combination with Ventrofix. Posterior fixation was found to offer superior stability compared to anterior fixation. Synex was at least comparable to MOSS for suspensory replacement of the vertebral body in the thoracolumbar spine. The increased biomechanical stability demonstrated for Synex suggests that a more rigid construction would also be achieved in vivo. When using MOSS in combination with posterior stabilization, the induction of intervertebral compression via the posterior fixator is recommended. This surgical step was not necessary with Synex.

Biomechanical Phenomena↗

Whiplash-type neck distortion in restrained car drivers: frequency, causes and long-term results.

An analysis was made of 1176 whiplash-type neck distortions taken from a total of 3838 restrained car driver incident reports. The percentage of whiplash-type neck distortion among injured drivers increased from less than 10% in 1985 to over 30% in 1997. Most occurred in head-on crashes or crashes with multiple collisions; only 15% occurred in rear-end collisions. More than 1,000 questionnaires were sent to the injured to find out about the duration and type of complaints caused by their cervical spine injury. Although only 138 (12%) returned the questionnaire, which may not be a representative sample, a further analysis was carried out. Of the 138, 121 (88%) indicated that they had suffered or were still suffering from their symptoms. The percentages of the various complaints were as follows: pain (74%), tension (6%) and stiffness (5%) in the head (27%), neck (55%) and shoulder (8%). The duration of the complaints was longest after multiple collisions and when the onset of complaints was longer than 24 h after trauma. Women and elderly persons predominated slightly in the group with longer duration of complaints. A correlation between the severity of the accompanying injuries and duration of complaints was found. Lack of adequate follow-up for patients with less severe injuries posed considerable difficulties for this retrospective study. In order to better evaluate this problem, prospective studies are necessary, with documentation including diagnosis, treatments, complaint duration and type.

Accidents, Traffic↗

Bone bruise of the calcaneus. A case report.

A bone bruise to both calcanei after axial overloading is reported. Because radiographs were normal and weightbearing was not possible, magnetic resonance imaging was performed and showed characteristic findings for a bone bruise of the calcaneus more extended on the left side than the right side. Resolution of pain was within the first 2 weeks after trauma on the right side, whereas partial weightbearing was necessary for 4 months on the left side. Six months after trauma, complete resolution of magnetic resonance signal changes was evident. Bone bruises should be considered when radiographs are normal. Because bone bruises pose a potential risk for chondrolysis and stress fracture, mobilization and weightbearing should be increased gradually.

Adult↗

Upper extremity fractures in restrained front-seat occupants.

BACKGROUND: The aim of our study was to analyze the injury mechanism of upper extremity fractures in car crashes, to create a basis for developing prophylactic devices. METHODS AND RESULTS: During 1985-1995, 3,260 restrained car drivers (1,228 front-seat passengers) were injured in 9,380 crashes involving cars. A total of 179 drivers (5.5%) (front-seat passengers: n = 53, 4.3%) sustained fractures of the arm. The hand (25%), wrist (23%), and forearm (23%) were affected most often, and the elbow (9%), upper arm (10%), and shoulder (10%) were seldom affected. No considerable differences of the injury mechanism were found comparing drivers with front-seat passengers. Fractures were mainly caused by head-on collisions (n = 119, 51%) or multiple collisions (n = 78, 34%). In 73% of the crashes (n = 166), delta-v exceeded 30 km/h (18.6 mph). A lower Delta-v resulted mainly in fractures affecting the shoulder and wrist. CONCLUSION: Because more than half of the upper extremity fractures resulted from a direct impact to the hand, arm, or both, modifications to improve the energy absorption by padding dashboard and inner door or by additional airbags are promising.

Abbreviated Injury Scale↗

Unilateral osseous bridging between the arches of atlas and axis after trauma.

STUDY DESIGN: This is a case report. OBJECTIVE: To present a case of osseous bridging between C1 and C2 of posttraumatic origin and with an associated closed head injury and to discuss its pathogenesis and clinical outcome after surgical resection. SUMMARY OF BACKGROUND DATA: Heterotopic ossifications of posttraumatic origin in the spine are rare. To the authors' knowledge, no cases have been reported of spontaneous bony bridging between C1 and C2 with a posttraumatic origin. METHODS: Heterotopic ossifications were detected when pain and limited axial rotation (left/right 10 degrees/0 degree/20 degrees) were persistent, despite intensive physical therapy. Because heterotopic ossifications were ankylosing C1 and C2, the decision was to resect the osseous bridge in combination with a careful mobilization of the cervical spine. Functional computed tomography was performed for analysis of the postoperative results. RESULTS: Four months after surgery, clinical examination showed asymptomatic increased axial rotation. Functional computed tomography indicated that left C1-C2 axial rotation was reduced, possibly related to impingement caused by residual bony spurs. Pathologic changes in the surrounding soft tissue may be another important factor in the persistent limitation of rotation. CONCLUSIONS: Osseous bridging between C1 and C2 may be considered when persistent pain and limited axial rotation are observed after trauma. Operative resection, together with careful intraoperative and postoperative mobilization, may be the treatment of choice.

Abdominal Injuries↗

[Operative versus non operative treatment of odontoid non unions. How dangerous is it not to stabilize a non union of the dens?].

INTRODUCTION: Injuries precede the vast majority of all odontoid pseudarthroses. Because of specific anatomic conditions type II injuries lead more often than other types to non unions. For its development insufficient internal or external fixation and a persisting fracture gap are crucial. METHODS AND RESULTS: In 71 patients after operative stabilization of odontoid fractures with two anterior lag-screws we detected 8 non unions. In 3 patients the interval between accident and operation amounted to more than 5 weeks, seven times we did not succeed in closing the fracture gap. Technical mistakes like insufficient reduction (n = 1) or screw misplacement (n = 3) were additional reasons. According to the literature and own observations an os odontoideum must be considered in most instances as a pseudarthrosis after a lesion of the subdental synchondrosis in childhood. The most important diagnostic tool in odontoid non unions is a dynamic examination of the upper cervical spine under fluoroscopic control in maximum flexion and extension. We propose a classification of posttraumatic dens non unions into 4 types. Type I corresponds to a stable "non union" in approximate anatomical position of the dens and without signs of instability in the former fracture zone. Type II describes a relatively stable grossly displaced non union that is not to be reduced by simple, closed means. Type III means an unstable non union and Type IV a posttraumatic os odontoideum. CONCLUSIONS: Therapeutical recommendations need to be differentiated. Unstable non unions are most often responsible for persistent pain, may result in acute or chronic myelopathy++ and therefore - as well as ossa odontoidea - need operative fixation. In considerably displaced non unions a closed reduction manoeuver with long term traction should be tried. The operative treatment of choice is the posterior transarticular screw fixation C1/C2 desirably in a percutaneous technique. Tight, "stable" pseudarthroses in the sense of a persisting fracture gap in painfree patients should first be controlled radiologically. If the odontoid position remains unchanged, non operative treatment may be continued.

Bone Screws↗

[Treatment of recurrence of fibular ligament rupture. Results of a prospective randomized study].

Previous studies concerning ruptures of the lateral ligaments of the ankle dealt with acute first ruptures. There are a few articles about chronic instability of the ankle but no prospective investigations have been reported concerning the treatment of recurrent ruptures. Good results were obtained following after non-operative treatment of acute ruptures of the fibular ligaments of the ankle joint. This prospectively randomized study was commenced to test whether recidivations of the rupture of the lateral ligaments can also be treated non-operatively or if they are in need of operative repair. The second question to be answered was whether these injuries should be treated differently depending on the treatment of the first rupture. From December 1986 to November 1989, 109 patients with a recidivation of a rupture of the ankle joint lateral ligaments were included in this prospective trial at the Department of Trauma Surgery, Hannover Medical School. They were divided into two groups depending on the therapy used to treat the first injury: The relapse was classified as a second-stage-rupture in cases where treatment of the first ligament rupture did not involve an operation and as a rerupture if the initial rupture was surgically repaired. Half of each group was treated randomly either with surgical ligament repair or without. A total of 100 patients (92%) at an average age of 24 years (11 to 49 years) was seen for follow-up examination one year after the relapse: The follow-up included the patient's subjective assessment, a clinical examination, and stress radiography. A 70 point score was used for evaluation of the total result. Two wound infections requiring reoperation were observed in the operative treatment groups. The follow-up examination revealed better results in both operative treatment groups (A and C), which was statistically significant (P < 0.05). Patients with a second-stage-rupture showed a significantly higher (P < 0.001) stability by stress radiography after surgical treatment (group A) in contrast to non-operative treatment (group B). In addition, the subjective and clinical results indicated a tendency towards better results which were not statistically significant (P < 0.09 and P < 0.07). In cases of rerupture the patient's subjective assessment revealed significantly more (P < 0.05) complaints after non-operative treatment (group D). Clinical results were comparable, and radiologic assessment showed a tendency towards higher joint stability after surgical treatment (group C), although it was not statistically significant (P < 0.07). Based on the results presented, the authors recommend the surgical repair of ankle joint ligaments in cases of second-stage- or rerupture.

Adolescent↗

[Surgical treatment of injuries of the thoracolumbar transition. 1: Epidemiology].

The authors report on a prospective multicenter study with regard to the operative treatment of fractures and dislocations of the thoracolumbar spine. 18 traumatologic centers in Germany and Austria, forming the working group "spine" of the German Society of Trauma Surgery, are participating in this continuing study. Between September 1994 and December 1996 682 patients (64% male) with an average age of 39 1/2 (7-83) years were entered. The entry criteria included all patients with acute and operatively treated (within 3 weeks after trauma) fractures and dislocations of the thoracolumbar spine (Th 10-L 2). Part 1 of this publication outlines the protocol and epidemiologic data. The incidence of fractures and dislocations of the thoracolumbar spine and associated injuries were recorded according to a standardized protocol, as well as the different operative methods and complications, duration of hospital stay, rehabilitation and incapacity. The analysis of the clinical social and radiological course was a second focus. The most frequent mechanism of injury was a fall (50%) or traffic accident (22%). Most of the fractures occurred at the L 1 level (49%). All injuries were classified according to the ASIF (AO) classification. 65% sustained an A-type fracture (compression fracture). Associated injuries were observed in 35% and 6% were polytraumatized. Extremities and thorax were most frequently affected. Younger age and traffic accidents lead more often to C-type fracture (fracture dislocation) and polytrauma. An increased number of multisegmental or multilevel lesions were observed in polytraumatized patients. There were 16% with incomplete paraplegia (Frankel/ASIA B-D) and 5% with complete paraplegia (Frankel/ASIA A). The rate of patients with initial neurologic deficits significantly increased with the severity of spinal injury according to the Magerl classification. Until discharge a neurologic improvement (at least 1 Frankel/ASIA grade) was observed in 32% of the partially paralyzed (Frankel/ASIA B-D) and in 12% of the patients with complete paraplegia (Frankel/ASIA A). A neurologic deterioration occurred in 3 patients (0.4%). As a base for further follow-up and late results the individual starting point was determined by collecting relevant data of the patients' history: 277 (40.6%) patients suffered from simultaneous diseases, one half was spine related. At the time of injury 559 (82.0%) patients were employed; 429 (62.9%) doing manual work. 369 (54.1%) patients stated sportive activities before the injury and 561 (82.3%) designated their "back function" as normal. For the time before injury the patients scored an average of 93.4 points in the Hannover Spine Score (0-100 points concerning complaints and function of the back/spine).

Adolescent↗

[Trans-articular screw fixation of C1/C2 in atlanto-axial instability. Comparison between percutaneous and open procedures].

For posttraumatic atlantoaxial instabilities posterior transarticular screw fixation according to Magerl represents the treatment of choice. In order to be able to insert the screws steep enough the soft tissues of the neck have to be dissected down to C7. Several authors therefore described a percutaneous technique. We analysed 30 patients with a sagittal atlantoaxial instability treated with one of both methods between the years 1995 and 1998 to detect any differences of either technique. In 19 cases we used a modified percutaneous technique with special instruments as has been published by McGuire and Harkey. On lateral plain films the angle between the screws and the lower endplate of C2 was measured. 6 to 24 months after the accident 26 patients could be seen clinically and controlled radiologically, 4 patients had died in the meanwhile. The angle of the screws were significantly different with 10 degrees (percutaneous group 73.9 degrees, open group 63.9 degrees, p = 0.001). Time needed for the operative procedure averaged 35 minutes shorter with the cannulated technique (93 to 128 minutes, p = 0.05). All posterior fusions had healed radiologically. Active motion of the c-spine was restricted in both groups equally. We checked subjective criteria concerning pain and function with a visual analog scale and a special score. With these instruments advantages for the percutaneous procedure could be found (freedom of pain 43 points (percutaneous) versus 39 points (open), p = 0.05). We conclude that the soft tissue preserving percutaneous technique of screw application for C1/C2 posterior fusion allows for a better and easier placement of screws. It also leads to a shorter operating time and better subjective results. The method offers particularly advantages in cases where only a temporary stabilization of the C1/C2 complex without a regular fusion is needed.

Adult↗

[Inter-observer reliability in the classification of thoraco-lumbar spinal injuries].

The purpose of a fracture classification is to help the surgeon to choose an appropriate method of treatment for each and every fracture occurring in a particular anatomical region. The classification tool should not only suggest a method of treatment, it should also provide the surgeon with a reasonably precise estimation of the outcome of that treatment. But to use a classification before its workability has been proved is inappropriate and can lead to confusion and more conflicting results. Any classification system should be proved to be a workable tool before it is used in a discriminatory or predictive manner. The radiographs of fourteen fractures of the lumbar spine were used to assess the interobserver reliability of the AO classification system. The radiographs and CT scans were reviewed in twenty-two hospitals experienced with spinal trauma. The mean interobserver agreement for all fourteen cases was found to be 67% (41-91%), when only the three main types (A, B, C) were used. The corresponding kappa value of the interobserver reliability showed a coefficient of 0.33 (range, 0.30 to 0.35). The reliability decreased by increasing the categories. For some injuries the interobserver reliability was found to be over 90% and also for the recommended therapeutic procedure there was an acceptable agreement. But the decision between an posterior approach alone or an additionally anterior procedure seems to be the most important question in treatment of spinal injuries at that time.

Accidents↗

[Transpedicular implantation of screws in the thoracolumbar spine. Results of a survey of methods, frequency and complications].

Pedicular fixation has found great acceptance as a modality for spinal fusions. Being a "blind technique" it is associated with a potential high risk of neural and vascular morbidity. In an attempt to evaluate and/or establish a uniformly accepted concept of surgical management we designed a questionnaire composed of seventeen questions dealing with different pre-, intra- and postoperative procedures in transpedicular fixation. This was sent to 31 experienced surgeons organized in the working group "spine" of the german trauma association. Half of the answers to each question were similar. The other half however, showed a wide variation of thought. It is thus deduced that although some concepts are frequently applied there is no general agreement to an optimal method of surgical handling. Most surgeons use conventional operative cushions for positioning the patients (22/31). Access is usually proceeded by sharp dissection of the lumbodorsal fascia using a scalpel instead of catheterization (21/31), consciously avoiding traumatisation of paravertebral muscle insertion to the transverse processes (22/31), as well as sparing the dorsal branch of segmental arteries (25/31). Intraoperative orientation is attained by inspection coronary and fluoroscopy sagittal (15/31). Most surgeons remove cortical bone using a Rongeur (22/31), transpedicular drill hole is prepared by means of a k-wire (11/31), for orientation again the fluoroscope is made use of (15/31). On perforating the medial boundary of the pedicle thirteen operators correct the direction on drilling, on perforating the lateral boundary twelve medialise the screws on fixation, and eleven surgeons would leave the screws in place if firm holding is warranted. Half of the questioned surgeons simply lateralise the screws if cerebrospinal fluid leaked from the drill holes. If a malposition of the pedicle screws is not suspected no control computer tomography is performed (21/31). Regarding these facts a comparative evaluation of the different techniques used in transpedicular fixation is lacking. In our opinion further multicenter evaluation is necessary to establish a unified method and thus optimize postoperative results.

Bone Plates↗

[Transpedicular fusion of the thoraco-lumbar junction. Clinical, radiographic and CT results].

The aim of this retrospective study was to determine the late result after operative treatment of acute thoracolumbar fractures and fracture dislocations. 29 patients, treated between 1988 and 1995 at the Department of Trauma Surgery, Hannover Medical School with posterior stabilization and interbody fusion with transpedicular cancellous bone grafting, were reexamined 3 1/2 years after surgery. The incorporation and effect on the fusion was analyzed with spiral CT scan after implant removal and the patients were seen for clinical and conventional radiologic examination. We treated 24 type A, 4 type B and 1 type C lesion according to the Magerl classification. 27 patients were stabilized with an internal fixator, 2 with a plate system. The mean operative time totalled 2:50 hours, the intraoperative fluoroscopy time averaged 4:07 minutes and a mean blood loss counted 376 ml. 4 patients out of 6 with an incomplete neurologic lesion (Frankel/ASIA D) improved to Frankel/ASIA grade E. 2 complications were observed: 1 delayed wound healing and 1 venous thrombosis with secondary pulmonary embolism. Compared to the preoperative status our follow-up examinations demonstrated permanent social sequelae: The percentage of individuals able to do physical labor was reduced (15 to 5 patients; p < 0.01) whereas the share of unemployed or retired patients increased (2 to 12 patients; p < 0.01). The assessment of complaints and functional outcome with the "Hannover Spinal Trauma Score" reflected a significant difference (p < 0.001) between the status before injury (96.6/100 points) and at the time of follow-up (64.4/100 points). The correlation between the "Hannover Spinal Trauma Score" and the finger-ground-distance was found to be significant (Coefficient Spearman = -0.71; p < 0.01). The radiographic assessment of the segmental kyphosis (Cobb technique) demonstrated a significant (p < 0.001) mean restoration from an initial angle of -15.2 degrees (kyphosis) to -3.4 degrees (kyphosis). Serial postoperative radiographic follow-up showed progressive loss of correction; at follow-up examination we found a mean of 7.8 degrees (p < 0.005). In 16 patients with an additional posterior fusion with autogenous bone grafting an analogous loss of correction was noted. CT scans after implant removal demonstrated an interbody fusion and incorporation of the transpedicular bone graft in 10 (34%) patients. In another 10 (34%) patients the CT scans proved the interbody fusion at the anterior and posterior wall of the vertebral body via direct contact due to collapse of the disc space. In these patients the bone graft was not incorporated and no central interbody fusion could be found. In 9 (31%) patients neither interbody fusion nor incorporation of the transpedicular graft was achieved. A frequent interbody fusion could not be achieved with the technique of transpedicular bone grafting. In case of incomplete or complete thoracolumbar burst fractures the authors recommend a combined operation with restoration of the anterior column with a strut graft or body replacement.

Female↗

[Acceleration injuries of the cervical spine in seat-belted automobile drivers. Determination of the trauma mechanism and severity of injury].

The analysis of 1,176 whiplash-type neck distortions was sought from a total of 3,838 restrained car driver incident reports. The percentage of these injuries increased from less than 10% in 1985 to over 30% in 1997. These occurred mostly with head-on or with multiple collisions, and only in 15% with pure rear-end collisions. In 23.2%, delta v amounted 10 km/h or less, which corresponds to a very minor crash. The average delta v was the highest in the cases of head-on collisions. Letters were sent to the injured to find out about the duration and type of complaints caused by a cervical spine injury. Of the 138 patients who returned the questionnaires, 121 (88%) indicated that they had or were still suffering from their symptoms. Percentage of various complaints were as follows: pain (74%), tension (6%) and stiffness (5%) in the head (27%), neck (55%) and shoulder (8%). The duration of the complaints was longest after multiple collisions and when the onset of complaints was later than 24 hours after trauma. Women and elderly persons predominated slightly in the group with longer duration of complaints. A correlation between the severity of the accompanying injuries and duration of complaints occurred. Also, with this retrospective study there was considerable difficulties in the lack of adequate follow-up for these patients with less severe injuries. In order to better evaluate this problem, prospective studies are necessary which include documentation of diagnosis, treatment protocols, duration and type of complaints.

Acceleration↗

[Effect of a crosslink or cerclage on the mechanical stability of an internal fixator].

This study was performed to evaluate the effect of a cerclage or a crosslink on internal fixator mechanical stability in an unstable spine injury model. Nine human thoracolumbar spine specimens were instrumented either with an internal fixator alone (T12-L2) or together with a cerclage or a crosslink. Four modes of loading were used: flexion, extension, lateral bending, and axial rotation. Moments itself were generated using a specially designed loading jig and loading system. The maximum moment applied was 10 Nm, three load-unload cycles were performed. The flexibility was measured by a motion tracker and range of motion (ROM), elastic zone (EZ) and neutral zone (NZ) were calculated. Statistical analysis was performed using the paired t-test (p < 0.05). For flexion, extension and lateral bending all devices were significantly more stable (p < 0.01), for axial rotation all devices were significantly less stable compared to the intact specimen (p < 0.01). But the crosslink provided significantly more stability compared to the internal fixator alone (p < 0.001). The complete device, i.e. internal fixator + crosslink, was significantly more stable compared to internal fixator + cerclage (p < 0.05). In this study the use of a cerclage had no additional effect in stabilizing the internal fixator. The operative and financial expenditure using a crosslink seems to be justified in fractures with a high rotationally instability, i.e. in type A-3-, B-, and C-injuries according to Magerl et al. [18].

Bone Plates↗

[Complex injuries of the spine].

3 different types of complex spinal trauma are defined: Type I means a multilevel contiguous or non contiguous unstable injury, type II is described as a spinal injury with concomitant thoracic or abdominal lesion, type III stands for the coincidence of spinal injury and polytrauma. Overlapping of different types occurs. Type I: The incidence amounts according a german multicenter study to about 2.5%. Multilevel injuries need to be stabilized for a long distance from posterior. With a thorough analysis the segments to be fused are determined. Type II: The leading thoracic injury is a lung contusion which occurs in up to 50% of the cases. A CT scan of the thorax during the first diagnostic screening is recommended. Early reduction and stabilization from posterior should be aimed at. During the first two weeks anterior procedures are contraindicated. Abdominal injuries are to be found in 3-4% of all spinal injuries. All organs could be affected. A typical constallation is the "seat-belt syndrome" with lesions of the upper abdominal organs and a flexiondistraction injury of the upper lumbar spine. The main problem is to make the diagnosis of both components initially. Most of the patients may be treated in one operation by first taking care of the abdominal injury and than stabilizing the spine. The prognosis of this combination is favorable. Type III: In 17-18% of all polytraumatized patients lesions of the spine are to be diagnosed. From these only one third need surgical care. From 680 patients with operatively treated fractures of the thoracolumbar junction 6.2% were polytraumatized according to the multicenter study mentioned above. The risk of missing a spinal injury in polytrauma totals approximately 20%. Surgical stabilization should be performed in the primary phase (day-1-surgery). Additional injuries, potentially time consuming operations with a high blood loss sometimes necessitate a different approach. Non stabilized spinal injuries apparently do not have the same negative effect on the whole organism as long bone fractures. In the early phase of treatment on the C-spine only anterior procedures and on the thoracolumbar spine only posterior techniques should be applied.

Adolescent↗