Head-neck Rotation Research Articles

Post-Traumatic Central or Axial Atlantoaxial Dislocation Presenting with “Atypical” Symptoms—Analyzing the Role of Dynamic Imaging on the Basis of Experience with 14 Patients Treated by Atlantoaxial Fixation surgery

This is a report of a series of 14 patients who presented with a range of "atypical" cranial, spinal, and systemic symptoms that started after they suffered a relatively severe injury to the head and/or neck several months or years before surgical treatment. The implications of diagnosing and treating central or axial atlantoaxial dislocation (CAAD) is discussed. Also, the role of dynamic rotatory and lateral head tilt imaging in the diagnosis and treatment is analyzed. Of the 14 patients, 7 were men and 7 were women, with an age range of 21-64 years (average, 42 years). Due to the severity of the presenting neurological and non-neurological symptoms, all the patients had lost their occupation and were heavily dependent on painkillers and/or antidepressant drugs. In addition to other characteristic clinical and radiological evidence, CAAD was diagnosed made based on the facetalignments on lateral profile imaging in the neutral head position. Dynamic head flexion-extension, lateral head tilt, and neck rotation imaging findings confirmed and subclassified CAAD. All 14 patients underwent atlantoaxial fixation surgery. A personalized self-assessment clinical scoring parameter and the World Health Organization Disability Assessment Schedule 2.0 was used to evaluate the outcome. One patient did not follow-up after surgery. At a minimum follow-up of 6 months after atlantoaxial fixation surgery, the remaining 13 patients experienced relief from all major symptoms. Diagnosing and treating CAAD can have major therapeutic implications for patients presenting with progressively worsening disabling clinical symptoms following relatively severe head and/or neck trauma.

Evaluation of Apparatus and Protocols to Measure Human Passive Neck Stiffness and Range of Motion

Understanding of human neck stiffness and range of motion (ROM) with minimal neck muscle activation (“passive”) is important for clinical and bioengineering applications. The aim of this study was to develop, implement, and evaluate the reliability of methods for assessing passive-lying stiffness and ROM, in six head-neck rotation directions. Six participants completed two assessment sessions. To perform passive-lying tests, the participant’s head and torso were strapped to a bending (flexion, extension, lateral bending) or a rotation (axial rotation) apparatus, and clinical bed, respectively. The head and neck were manually rotated by the researcher to the participant’s maximum ROM, to assess passive-lying stiffness. Participant-initiated (“active”) head ROM was also assessed in the apparatus, and seated. Various measures of apparatus functionality were assessed. ROM was similar for all assessment configurations in each motion direction except flexion. In each direction, passive stiffness generally increased throughout neck rotation. Within-session reliability for stiffness (ICC > 0.656) and ROM (ICC > 0.872) was acceptable, but between-session reliability was low for some motion directions, probably due to intrinsic participant factors, participant-apparatus interaction, and the relatively low participant number. Moment-angle corridors from both assessment sessions were similar, suggesting that with greater sample size, these methods may be suitable for estimating population-level corridors.

Association of Head-Neck Rotation With History of Pitching-Related Elbow Pain in Youth Baseball Players.

Prevention of pitching-related elbow pain in youth baseball players is important. Overhead pitching involves a whole-body motion, including head-neck rotation. A limited range of motion of head-neck rotation may cause inefficient pitching motion; however, this association is unclear. To determine whether the range of motion of head-neck rotation is associated with the history of pitching-related elbow pain in youth baseball players. Cross-sectional study; Level of evidence, 3. A total of 311 youth baseball players were selected and asked to complete a questionnaire survey about their age, weight, height, sex, baseball experience, main position, pitching side, and previous/current elbow pain during pitching. The range of motion of the upper and lower limb joints, head-neck rotation, and thoracic kyphosis angle were measured. Binomial logistic regression analysis was used to identify factors associated with the history of elbow pain related to pitching. There were 101 players with a history of pitching-related elbow pain (history group) and 142 players with no pitching-related elbow pain (no-history group). The history group had significantly lower values than the no-history group regarding the range of motion of head-neck rotation on the nondominant side (74.9°± 9° vs 77.7°± 9.6°; P = .02) and overall head-neck rotation (150.6°± 14.7° vs 154.9°± 18.4°; P = .04). Binomial logistic regression analysis identified head-neck rotation on the nondominant side (odds ratio [OR], 0.97 [95% CI, 0.94-1.00]), shoulder horizontal adduction on the dominant side (OR, 0.98 [95% CI, 0.96-1.00]), height (OR, 1.04 [95% CI, 1.00-1.08]), and playing position (pitcher) (OR, 0.40 [95% CI, 0.21-0.76]) as factors associated with a history of pitching-related elbow pain. Our cross-sectional analysis demonstrated that youth baseball players with a history of pitching-related elbow pain had limited head-neck rotation range of motion on the nondominant side, and this was a significant factor associated with the history of pitching-related elbow pain.

The effects of dual screen layout on neck-shoulder muscle activity and head-neck posture variability during computer tasks.

Larger dual screens have been widely used during office work and their biomechanical exposure should be explored. To investigate the biomechanical effect of two dual screen layouts on neck-shoulder muscle activity and the variability of head-neck posture in computer users. A preliminary study of the user-preferred dual screen angles was carried out in V-shaped and L-shaped layouts. Twenty healthy participants aged 19 to 26 years were recruited and assigned to perform reading, typing, and searching tasks for 30 minutes in both workstation layouts. Electromyography was measured at bilateral cervical erector spinae (CES), sternocleidomastoid (SCM), and upper trapezius (UT). The head-neck lateral bending, rotation, and flexion angles were recorded. The visual analog scale (VAS) was used to evaluate visual strain. The muscle activity at the left UT and right CES sites when using the V-shaped layout was significantly higher than the L-shaped. There were significant differences in head-neck rotation and flexion angles between the two layouts in reading and typing tasks. In the searching task, there was no significant difference in the head-neck rotation and flexion angles between the two layouts. The visual strain score was significantly higher in the V-shaped layout. The CES and UT muscles displayed higher levels of activation while using the V-shaped layout in comparison to the L-shaped layout. The head-neck rotation and flexion angles differed due to varied types of work when using V-shaped and L-shaped layouts.

Tracheal tubes intracuff pressure difference between neutral head-neck position and lateral rotation in patients with tracheal intubation

BackgroundTracheal tubes (TT) cuffs seal the airway to facilitate positive pressure ventilation and prevent aspiration due to subglottic secretions. Changes in head-neck position can affect TT intracuff pressure. An increase or decrease in TT intracuff pressure can cause many morbidities. The purpose of this study was to determine the effect of lateral head-neck rotation on TT intracuff pressure. MethodsForty (40) patients aged 18–64 years undergoing elective surgery under general anesthesia were selected in this study. After tracheal intubation, the TT cuff was inflated with a minimal occlusive volume technique. The TT was placed on the right side of the mouth. Changes in TT intracuff pressure were assessed before and after the position change. TT intracuff pressure was measured with a cuff inflator in the neutral head position. After lateral head-neck rotation (60°), the intracuff pressure was remeasured. ResultsThe mean intracuff pressure increased from 25.5 + 1.64 to 29.4 + 1.71 cmH2O after lateral head-neck rotation (p = 0.000). There was a significant difference between neutral position and lateral head rotation (p < 0.05). The use of a minimal occlusive volume technique with a volume of 4–7 cc was able to produce TT intracuff pressure between 22 and 28 cmH2O (normal range 20–30 cmH2O). The difference in TT intracuff pressure after lateral head-neck rotation was 3.9 ± 1.31 cmHO2. ConclusionTracheal tube intracuff pressure is significantly higher after the head-neck position change from neutral to lateral rotation. Measurement of intracuff pressure after lateral head rotation is beneficial to avoid possible adverse effects of position-related pressure changes.

Occupant safety effectiveness of proactive safety seat in autonomous emergency braking

The proactive safety seat (PSS) is a recently developed active safety system for securing occupant safety in out-of-seat position (OOSP), which was applied in the Hyundai Genesis G80 in 2020. However, there has not been sufficient quantifiable verification supporting the effectiveness of the PSS. The present study was performed to determine the effectiveness of the PSS for occupant safety in OOSP and to identify areas for additional improvement. Six test conditions were considered to determine the effectiveness of the PSS for augmentation of occupant safety in OOSP. Ten healthy men participated in the tests. Compared with the no PSS condition, maximum head excursion and neck rotation were significantly decreased in the PSS condition by 0.6–0.8-fold and 0.6–0.7-fold, respectively (P < 0.05). The PSS condition in which the seat pan was moved forward to the mid position showed a greater effect in reducing the characteristic motions related to submarining, compared with the condition in which the seat pan was moved rearward to the mid position (P < 0.05). These results suggested that PSS augments occupant safety in OOSP. This study provides valuable insights in ameliorating risks to the occupant in unintended seat positions before braking and/or collision.

Low-dose three-dimensional CT angiography for the evaluation of posterolateral protrusion of the vertebral artery over the posterior arch of the atlas: a quantitative anatomical comparison study of the rotational and neutral positions

To investigate the changes in relevant anatomical parameters of posterolateral protrusion of the vertebral artery (VA) between head-neck rotational and neutral positions using low-dose three-dimensional computed tomography angiography (3D-CTA). Low-dose 3D-CTA images obtained for various craniocervical diseases in 36 non-dominant VA side patients with neutral, left and right head-neck rotational positions were evaluated. The relevant parameters from superior and inferior views, including external diameter (ED), internal diameter (ID), transverse diameter (TD), heights and diameters of posterolateral protrusion of the VA over the posterior arch of the atlas in the neutral and rotational positions, were recorded and compared. There was no significant differences in the rotational angle (left/right: 31.23±6.60/29.94±6.09°, p>0.05). There were no significant differences in heights and diameters of bilateral VA between rotational and neutral positions (all p>0.05). The contralateral ID, ED, and TD of the rotational positions were significantly shorter than those of the neutral position (all p<0.05), while there were no significant differences in the three ipsilateral diameters (all p>0.05). Posterolateral protrusion of the VA is not uncommon in the population, and surgeons should be aware of its presence, especially the increased possibility of injury to the VA caused by head-neck rotation, during the operation; thus, preoperative evaluation by low-dose 3D-CTA should be considered.

Magnetic resonance imaging of severe idiopathic club foot treated with one-week accelerated Ponseti (OWAP) technique

PurposeThis study aims to evaluate changes in tarsal bones relationship after the use of one week accelerated Ponseti method in the treatment of severe idiopathic clubfoot using MRI. We hypothesize that one-week accelerated Ponseti is at least as effective as standard techniques in achieving the desirable MRI parameters. MethodsThis is a prospective study of 8 children with severe idiopathic clubfeet (Pirani 6) (4 unilateral and 4 bilateral) treated before the age of three months with one-week accelerated Ponseti technique, as described in a former study with minimum 2-year follow-up. The 8 corrected feet were compared with the 4 unilateral normal feet at clinical and radiological levels using a Pirani scoring system and an MRI, respectively. ResultsClinical results showed that Pirani score was 1.1 in the last follow up in comparison to Pirani 6 pretreatment (p < 0.05). MRI results indicated that the malleocalcaneal angle, axial malleocalcaneal index, coronal tibiocalcaneal angle, sagittal talocalcaneal angle, and talar head neck calcaneal rotation showed statistical difference between the two groups (p < 0.05). Sagittal malleocalcaneal index, sagittal tibiocalcaneal angle, talar head neck rotation related to talar body, and posterior calcaneal rotation showed no statistical difference between normal feet and clubfeet after correction (p value >0.05). ConclusionOne-week accelerated Ponseti technique showed to be as effective and safe as other treatment methods through clinical and MRI follow up data. MRI role was to confirm the efficiency of this innovative accelerated technique, but not used as a routine follow up.

Influence of Head-Neck Rotation on Elbow Flexor and Extensor Muscle Activity and Strength in Normal Adults

Influence of Head-Neck Rotation on Elbow Flexor and Extensor Muscle Activity and Strength in Normal Adults

Age-related kinematic performance should be considered during fast head-neck rotation target task in individuals aged from 8 to 85 years old.

Kinematic behavior during fast cervical rotations is a useful parameter for assessing sensorimotor control performances in neck-pain patients. However, the influence of age in asymptomatic individuals from children to older people still needs to be explored. Our aim was to assess the impact of age on sensorimotor control performance of the head-neck with execution time and kinematic variables (time of task, mean speed/acceleration/deceleration, overshoots (OSs), minimum/maximum speed) during standardized fast rotation target task using the DidRen Laser test. A total of 80 volunteers were stratified in four different age-groups: Children (8–14 years): n = 16; Young Adults (18–35 years): n = 29; Old Adults (36–64 years): n = 18; Seniors (65–85 years): n = 17. Results showed that to perform the test, Children were slower (69.0 (60.6–87.3)s) compared to Young Adults (49.6 (45.6–55.6)s) with p < 0.001, and Old Adults (51.7 (48.4–55.8)s) with p < 0.001. It was also slower in Seniors (57 (52.3–67.6)s) compared to Young Adults with p < 0.013. Mean speed was slower in Children (9.4 ± 2.3 °s−1) and Seniors (10.6 ± 2.4 °s−1) compared to Young Adults (13.7 ± 1.9 °s−1) with p < 0.001 and Old Adults (13.3 ± 2.4 °s−1) with p < 0.001. Mean acceleration was slower for Children (8.4(7.6–10.2) °s−2) compared to Young Adults (11.1 (8.8–15.3) °s−2) with p < 0.016, and Old Adults (12.0(8.4–15.3) °s−2) with p < 0.015. Mean deceleration was slower for Children (−1.9(−2.6–1.4) °s−2) compared to Young Adults (−2.9(−3.7–2.5) °s−2) with p < 0.001 and Old Adults (−3.2(−3.7–2.3) °s−2) with p < 0.003. The DidRen Laser test allows us to discriminate age-specific performances for mean speed, acceleration and deceleration. Seniors and Children needed to be slower to become as precise as Young Adults and Old Adults. No difference was observed for OSs which assesses accuracy of movement. Age should therefore be considered as a key parameter when analyzing execution time and kinematic results during DidRen Laser test. These normative data can therefore guide clinicians in the assessment of subjects with neck pain.

Effects of Head-Neck Positions on the Hand Grip Strength in Healthy Young Adults: A Cross-Sectional Study.

Background Assessment of hand grip strength is vital for the evaluation of upper limb impairments and effective exercise prescription. Present study primarily aimed to investigate the effect of head-neck positions on the hand grip strength in healthy young adults. Secondarily, the present study compared hand grip strength between left versus right hand in different head-neck positions. Methods Healthy young adults (age 19 – 30 year; n = 40) participated in this cross-sectional study. Hand grip strength was assessed in three head-neck positions (neutral, rotation left, and rotation right) using the standard adjustable Jamar hand dynamometer. Results Hand grip strength in both sides (left and right) was greatest in the head-neck neutral position. Hand grip strength measured in head-neck left rotation position displayed the least strength in both sides. There was no significant difference noted between left and right side hand grip strength measured in head-neck neutral and right rotation positions. However, there was a significant difference noted between left and right side hand grip strength measured in head-neck left rotation positions. There was no significant effect of head-neck positions on hand grip strength noted in both sides. Conclusions Hand grip strength was highest in the head-neck neutral position followed by head-neck rotation to the right. However, head-neck positions did not significantly affect hand grip strength in healthy young adults. Further studies assessing the hand grip strength in different neck positions in patients with neck pain and upper limb dysfunction may have significant implications for the assessment of hand grip strength.

Asociación entre el patrón postural cefálico y la inteligibilidad articulatoria del habla

RESUMEN Objetivo: el propósito de este estudio fue establecer un factor asociativo que relacione la morfología del sistema cráneo - cervical con el nivel de inteligibilidad articulatoria del habla en sujetos jóvenes. Métodos: estudio transversal, consideró una muestra de 42 jóvenes universitarios de un universo de 140, ambos sexos, sin antecedentes mórbidos y con un rango de edad entre 18 y 21 años. Se evalúo: a) inteligibilidad articulatoria mediante el coeficiente de variación periódica diadococinética, b) parámetros posturales estáticos tradicionales mediante método fotogramétrico y c) patrón postural cefálico mediante radiografía cefalométrica lateral. Resultados: se encontraron 36 sujetos con inteligibilidad adecuada y 6 alterada, donde la variable rotación cráneo cervical antero-posterior presentó diferencias estadísticamente significativas (p= 0,009) entre el grupo con inteligibilidad normal respecto al grupo con inteligibilidad alterada. El análisis de regresión lineal evidenció que sujetos que presentan rotación posterior de cabeza sobre cuello presentan mayor variabilidad en la emisión silábica del rendimiento diadocinético del habla (Sq r lineal = 0,128). Conclusión: se establece que la postura cefálica con presencia de rotación posterior de la cabeza sobre el cuello se asocia a la pérdida de inteligibilidad del habla en la muestra estudiada.

Natural mediotrusive contact: does it affect the masticatory and neck EMG activity during tooth grinding?

Objectives: There is scarce knowledge regarding the influence of a natural mediotrusive contact on mandibular and cervical muscular activity. The purpose of this study was to analyze the EMG activity of the anterior temporalis (AT) and sternocleidomastoid (SCM) muscles during awake grinding in healthy subjects with or without a natural mediotrusive occlusal contact.Method: Fifteen subjects with natural mediotrusive occlusal contact (Group 1) and 15 subjects without natural mediotrusive occlusal contact (Group 2) participated. Bilateral surface EMG activity of AT and SCM muscles was recorded during unilateral eccentric or concentric tooth grinding tasks. EMG activity was normalized against the activity recorded during maximal voluntary clenching in intercuspal position (IP) for AT muscles and during maximal intentional isometric head-neck rotation to each side, for SCM muscles.Results: EMG activity of AT and SCM muscles showed no statistical difference between groups. EMG activity of AT muscle was higher in the working side (WS) than in the non-WS (NWS) in Group 1 during concentric grinding (0.492 vs 0.331, p = 0.047), whereas no difference was observed in Group 2. EMG activity of SCM was similar between working and NWSs in both groups and tasks. Asymmetry indexes (AIs) were not significantly different between groups.Discussion: These findings in healthy subjects support the assumption that during awake tooth grinding, central nerve control predominates over peripheral inputs, and reinforce the idea of a functional link between the motor-neuron pools that control jaw and neck muscles.

Effect of natural mediotrusive contact on electromyographic activity of jaw and cervical muscles during chewing

Objective. This study evaluated the effect of a natural mediotrusive contact on the electromyographic (EMG) activity of the anterior temporalis and sternocleidomastoid muscles during chewing in healthy subjects. Materials and methods. The study sample included two groups of 15 subjects each (Group 1: with natural mediotrusive contact; Group 2: without natural mediotrusive contact). Bilateral surface EMG activity was recorded on anterior temporalis and sternocleidomastoid muscles during unilateral chewing of a half cookie and unilateral chewing of a piece of apple. Anterior temporalis and sternocleidomastoid muscle activity was normalized against activity recorded during maximal voluntary clenching in intercuspal position and maximal intentional isometric head–neck rotation to each side, respectively. The partial and total asymmetry indexes were also calculated. Data were analyzed using Mann-Whitney, Wilcoxon and unpaired t-test. Results. EMG activity of anterior temporalis and sternocleidomastoid muscles showed no significant difference between the groups. EMG activity of anterior temporalis was similar between working and non-working sides during chewing in both groups. EMG activity of sternocleidomastoid muscle was higher in the working side than in the non-working side in Group 2 subjects. Asymmetry indexes were not significantly different between groups. Conclusions. The similar EMG pattern and asymmetry indexes observed suggest the predominance of central nervous control over peripheral inputs on anterior temporalis and sternocleidomastoid motor neuron pools.

The Impact of Use of Dual Monitor Screens on 3D Head–Neck Posture and Activity of Neck Muscles

OCCUPATIONAL APPLICATIONS Computers with dual monitor screens are being increasingly used at many workplaces. Altered screen layout and increased viewing space associated with dual monitor screens may affect head–neck working postures and the activity of neck muscles. However, this problem has not been investigated in the past, and standard guidelines based on empirical data are not available for setting up a computer workstation with dual monitor screens. The present study compared the effects of single versus dual monitor screens on 3D head–neck postures and the activity of neck muscles in computer users. The results of this study have demonstrated that working on a video display unit workstation with dual monitor screens involved more rotated, asymmetric head–neck postures and higher activation of the anterior neck muscles than a video display unit workstation with a single monitor screen. TECHNICAL ABSTRACT Background: Among workstation design factors, placement of the computer monitor screen is the most frequently identified risk factor for neck and shoulder pain among video display unit users. One of the recent changes in video display unit workstation design that may influence the position of computer monitor screens is the use of dual monitors. Some studies have shown that user performance and efficiency was positively affected by the use of dual monitor screens; however, the effect of use of dual monitor screens on the biomechanical behavior of the head-neck region is currently unknown. Purpose: This study was aimed at understanding the effect of single versus dual monitor screens on 3D head–neck postures and the activity of neck muscles. Method: Ten healthy participants performed three types of video display unit tasks: (1) reading for 10 minutes, (2) typing for 5 minutes, and (3) performing search and find tasks for 10 minutes using single and dual monitor screens. An inertial motion-capture system was used to measure 3D head–neck postures. Activity of sternocleidomastoid and cervical trapezius muscles was recorded bilaterally using surface electromyography. Results: Use of dual monitor screens significantly increased head–neck rotation by 9.0° compared to the single monitor screen. The range of motion of head–neck rotation increased significantly by 8.4° using dual monitor screens compared to the single monitor screen. Corresponding to the increase in the head–neck rotation, a contralateral increase in the activity of the right sternocleidomastoid muscle was observed with the dual monitor screen layout. Activity of cervical trapezius muscle was not affected by the type of monitor layout. Conclusions: Increased activation of anterior neck muscles caused by asymmetrical, more rotated head–neck postures while operating a video display unit workstation with dual monitor screens may increase the risk of neck musculoskeletal disorders, especially with prolonged computer use.

Association between mouth opening and upper body movement with intake of different-size food pieces during eating

Head rotation is coordinated with mandibular movement during mouth opening, and the range of head rotation and mouth opening change with food size. However, past research did not include upper body movement, and no reports have related head and mandibular movement during realistic eating. The purpose of this study was to analyse head and mandibular movements with intake of different-sized food pieces during realistic eating.The test food consisted of apple cut into two different cube sizes (10mm and 20mm). Head and mandibular movements of 20 healthy young adults eating the apple pieces were simultaneously recorded in three dimensions by a wireless opto-electronic system. Reflective markers were attached to the upper lip and chin to measure the mouth opening range. Five markers were attached to eyeglasses frames to measure linear motion and rotation of the head. One marker was attached to the jugular notch of the sternum to measure linear motion of the upper body. Linear motion, and the inclination angle of the head and upper body, and mouth opening range were compared during intake of different-sized apple pieces.Mouth opening, head–neck rotation angle and the amount of upper body forward translation and inclination increased with larger apple pieces. However, isolated relative head motion was stabilized. We conclude that upper body forward motion and head–neck rotation assist mouth opening whilst stabilizing head orientation, and that the range of head–neck rotation angle, upper body translation and range of mouth opening change with food size during realistic eating.

Effects of Head-neck Rotation and Kinesio Taping of the Flexor Muscles on Dominant-hand Grip Strength

Purpose) The purposes of this study were to examine whether the asymmetrical tonic neck reflex affects the dominant-hand grip strength in healthy adults and to compare the results with the degree of grip strength achieved when Kinesio tape was applied to the flexor muscles of the dominant hands. (Subjects) The subjects were 20 men and 20 women who agreed to participate in the study. (Methods) Grip strength was measured using a Jamer dynamometer under 3 conditions: the neutral position, the head-neck system rotating toward the nondominant hand in the transverse plane, and after applying Kinesio tape to the flexor muscles of the dominant hand. (Results) In the neutral position, the grip strength of the dominant hand was significantly greater after applying Kinesio tape to the flexor muscles than that of the untaped dominant hand in the neutral position or the head-neck rotation condition in both males and females. (Conclusion) These results suggest that the muscle strength of the upper extremity in subjects with upper- extremity muscle weakness may be improved by clinical application of Kinesio taping as a supplementary measure.

The Gliding Nail, a Universal Implant in the Treatment of Proximal Femur Fractures

Due to the increase in the incidence of osteoporosis with age and the high biochemical load on the proximal femur, the pertrochanteric femur fracture is the typical fracture of the elderly. The number of different fracture types and the characteristic features of this patient population places high demands on any universally applicable implant. The rotational instability of the head–neck fragment in the case of a trochanter minor defect, in particular, is a significant factor in the care of pertrochanteric femur factures. The object of this study was to show that the gliding nail constitutes a universal implant for the care of proximal femur fractures with constantly maintained stability under load. Between March 1996 and April 2001, 501 patients with per- and subtrochanteric fractures and an average age of 76 were included in the study. All osteosyntheses were carried out using the gliding nail which has an I-beam cross-section profile blade. 73.2% were treated operatively for closed isolated per- or subtrochanteric femur fractures. All patients were restored to full weight-bearing postoperatively. The combined overall early and late complication rate following gliding nail synthesis was only 5.4%. Neither blade cut-out nor head–neck rotation was observed following gliding nail osteosynthesis. Three-month mortality rose from 2.4% in patients with no complications to 90% in patients with four complications. 92.1% of patients were independently mobile at the time of the follow-up examination. With its low complication rate and the ever-present possibility of full weight bearing, the gliding nail fulfills all the requirements of a modern implant for the treatment of proximal femur fractures. In our opinion, its most advantageous features are the high moment of resistance of the I-beam cross-section profile blade which ensures the possibility of gliding, the minimalized risk of proximal cut-out due to the large surface area with two planes of support in the bone, and its secure rotational stability in terms of both nail and bone. The impaction of the blade, which requires no reaming with its resulting loss of bone substance, is responsible for the excellent bone–implant interface.

Active range of motion of the head and cervical spine: a three-dimensional investigation in healthy young adults

Purpose. To define reference values for head–cervical range of motion (ROM) in healthy young adults, to assess the effect of sex, and to quantify the separate contribution of other body districts. Methods. Thirty women and 30 men performed maximal head and cervical spine flexion–extension, lateral bending, and axial rotation. Movements were detected using a digital optoelectronic instrument. Maximum head–cervical spine and thoracic motions were separated. Results. Flexion and extension were performed mainly in the sagittal plane. The movement was larger in women (136°) than in men (130°). During flexion, both sexes moved the head–neck and the thorax in the same direction. During extension, men moved only the head–cervical spine, while women moved the two analyzed districts in the opposite directions. Lateral bending was nearly symmetric, associated with head–cervical rotation and extension, and larger in women (91°) than in men (77°). Adjunctive thoracic motion was limited in the sagittal and frontal planes, but larger in the horizontal plane (opposite motions of about 20°). Head–neck rotation was symmetric, and associated with concomitant movements in both the sagittal and frontal planes. It was larger in women (162°) than in men (155°), and performed with limited adjunctive thoracic motions. Conclusions. The present values can be used as a first group of normative data for head–cervical ROM in young men and women.

Influence of head-neck rotation on static elbow flexion force of paretic side in patients with hemiparesis.

The purpose of this investigation was to examine the influence of bead and neck (HN) position in the transverse plane on the static production of elbow flexion force in the involved (paretic) upper extremity of patients with hemiparesis. Thirty-one patients who had experienced a cerebrovascular accident a mean of 44 days before testing participated in the study. Static elbow flexion force was tested with a hand-held dynamometer, twice with the HN rotated toward the paretic side and twice with the HN rotated toward the nonparetic side. Elbow flexion force did not differ with the HN in the two positions (F = 0.008, p = 931). Results of this study support the conclusion that HN position in the transverse plane does not influence the production of static elbow flexion force on the paretic side in patients with stroke. Clinicians, therefore, may wish to reexamine any emphasis they place on HN position for facilitating elbow flexion force production on the paretic side of patients with hemiparesis.