Relative Range Of Motion Research Articles

Effect of Distal Tibiofibular Syndesmosis Overcompression on the Biomechanical Properties of the Ankle Bones: An In Vitro Cadaveric Model

Category: Trauma; Ankle Introduction/Purpose: Overtightening of the distal tibiofibular syndesmosis during open reduction and internal fixation (ORIF) of ankle fractures remains a clinical concern, and there are limited data delineating the effect of syndesmosis overcompression on subsequent range of motion of the ankle joint bones. The primary objective of the current study was to determine the effect of syndesmotic overcompression on the relative range of motion (ROM) of the tibia, fibula, and talus, and to determine the syndesmotic fixation construct that most accurately restores native motion. Methods: Ten cadaveric lower limbs were utilized (78.3±13.0 yrs, 4F; 6M). A musculoskeletal simulator at ±7.5 Nm was used to test flexibility in dorsiflexion-plantarflexion, inversion-eversion, and internal-external rotation. After intact testing, syndesmotic probes were used to arthroscopically measure the intact position of the distal tibiofibular syndesmosis. The force needed to compress the syndesmosis just beyond the intact position represented the intact force (100%), and overcompression was defined as 150% of the intact force. The anterior inferior tibiofibular ligament (AITFL), interosseus membrane (IOM), and posterior inferior tibiofibular ligament (PITFL) were then sectioned. Testing was repeated for destabilized, IOM reconstruction at 100% compression and 150% overcompression, IOM reconstruction plus AITFL fixation at 100% compression and 150% overcompression, and AITFL fixation alone. ROM data was reported as a percentage of the intact condition. Repeated measures ANOVA and Bonferroni post hoc test were performed to assess differences between conditions with p< 0.05. Results: Average force needed to compress the syndesmosis was 71.0 ± 22.2 N. There was a significant increase in distal tibiofibular ROM in internal and external rotation for all conditions compared to intact (Figure 1) (p < 0.05). In the axial plane, reconstruction of the IOM membrane did not restore the intact condition and was similar to the destabilized treatment, regardless of compression force. The addition of AITFL fixation significantly reduced distal tibiofibular motion compared to IOM reconstructions alone, but still did not approach the intact condition. Overcompression of the syndesmosis did not significantly affect relative ROM of the ankle bones in any plane (p>0.05). Changes in the proximal tibiofibular ROM were similar in magnitude and direction as the distal tibiofibular ROM for all conditions. Conclusion: In the current study, overcompression of the distal tibiofibular syndesmosis did not restrict relative ROM of the tibia, fibula, or talus. Reconstructing the AITFL in addition to the IOM decreased tibiofibular ROM, particularly in the axial plane. In the clinical setting, surgical reconstruction with dynamic fixation of the distal tibiofibular syndesmosis may result in increased ROM and mechanical stress at the proximal tibiofibular articulation.

A wearable inertial system to evaluate Tai Chi training motor effects in patients with Parkinson's disease.

Physical therapy is strongly recommended for patients with neurological disorders. Tai Chi-based treatments seem to improve physical functions like gait speed and balance. However, assessments after treatment rely on semi-quantitative clinical scales affected by subjectivity with controversial results. This study aims at investigating whether Tai Chi could be a valid alternative to traditional physiotherapy rehabilitation. We propose a wearable system composed of two inertial devices able to objectively measure the effect of the rehabilitation treatment on the range of movement of the trunk. Seventeen patients with Parkinson's Disease (PD) were recruited and assessed. They have been randomly divided into two groups: group 1 followed a Tai Chi-based treatment, while group 2 underwent a traditional physiotherapy rehabilitation. The two groups have been assessed before (t0) and after the treatment (t1). No statistical differences have been found in the relative range of motion between the upper and lower sensors between the two groups at the baseline. Both treatments resulted in a significant improvement in the trunk range of movement (on the right side). Notably, the improvement in the effect size of the treatment was greater in group 1 than in group 2. In fact, even if both the groups benefited from their treatment group 1 gained larger mobility of the trunk if compared to group 2. Interestingly, no differences have been accounted adopting the traditional UPDRS III for motor symptoms of PD, strengthening the idea that objective measurement coming from wearable biomedical sensors could detect information otherwise neglected by traditional clinical tools.Clinical Relevance- This study preliminary confirms that beneficial motor effects after a Tai Chi rehabilitation program are comparable and quite better than after traditional physiotherapy, promoting Tai Chi as a valid alternative treatment for PD patients.

Finite Element Analysis and Validation of Segments C2-C7 of the Cervical Spine

As an important part of the human spine, the cervical spine has a complex structure and easily suffers from diseases. Analysis of the biomechanical mechanism of cervical spine structure using the finite element model is not only helpful for the diagnosis, treatment and prevention of cervical spine diseases but also has positive significance for the performance evaluation of cervical spine implants. In this paper, a method of establishing a cervical C2-C7 finite element model based on CT image data is studied. Through the preprocessing of cervical CT images, the C2-C7 three-dimensional finite element model of the cervical spine was established. The pure moment loads of 0.33 Nm, 0.5 Nm, 1 Nm, 1.5 Nm and 2 Nm were applied to simulate flexion/extension, and the moment of 1 Nm was used to simulate the left and right lateral bending and axial rotation of the cervical spine. The relative range of motion (ROM) between each vertebral body was calculated. At the same time, the stress on some segments under axial load was analyzed. The results were basically consistent with the experimental data of in vitro studies, which verified the validity of the model.

Cervical Alignment of Patients with Basilar Invagination: A Radiological Study.

ObjectiveTo investigate the cervical alignment and the relative range of motion (ROM) in patients with basilar invagination (BI).MethodsA total of 40 BI cases (38.1 years old ± 17.9 years old, 19 male and 21 female) and 80 asymptomatic individuals (33.8 years old ± 10.8 years old, 40 male and 40 female) were included. The Skull‐C2/Skull‐BV, Skull‐C7, C2‐C7/BV‐C7 wall angles, C0‐C2/C0‐BV, C0‐C7, C1‐C7, and C2‐C7/BV‐C7 angles were measured in dynamic X‐ray images (including neutral, extension, and flexion positions). Correlation between the upper and lower cervical curvatures were analyzed. The total, extension, and flexion ROMs of these angles were calculated, respectively.ResultsThe BI patients had a smaller C0‐C2/C0‐BV angle (18.2° ± 16.4° vs 30.9° ± 9.3°), but larger C2‐C7/BV‐C7 (32.2° ± 16.1° vs 19.4° ± 10.6°) and C2‐C7/BV‐C7 wall angles (37.8° ± 17.2° vs 23.6° ± 10.2°) than the control group in neutral position. The upper and lower curvatures correlated negatively in neutral (r = −0.371), extension (r = −0.429), and flexion (r = −0.648) positions among BI patients, as well as in extension position (r = −0.317) among control group. The BI patients presented smaller total ROMs in Skull‐C2/Skull‐BV (12.3° ± 16.6° vs 19.7° ± 10.9°), C0‐C2/C0‐BV (8.1° ± 11.1° vs 17.6° ± 10.5°), and C0‐C7 angles (57.8° ± 14.2° vs 78.3° ± 17.9°), but a larger total ROM in C2‐C7/BV‐C7 wall angle (52.8° ± 13.9° vs 27.0° ± 16.1°) than the control group. The BI patients also presented smaller extension ROMs in Skull‐C2/Skull‐BV (6.9° ± 9.4° vs 12.5° ± 9.3°), Skull‐C7 (24.5° ± 10.9° vs 30.7° ± 12.5°), and C0‐C2/C0‐BV angles (4.4° ± 7.8° vs 9.9° ± 8.6°) than the control group. Moreover, the BI patients showed smaller absolute values of flexion ROMs in Skull‐C2/Skull‐BV (−5.2° ± 9.4° vs −7.3° ± 8.0°), C0‐C2/C0‐BV (−3.2° ± 8.8° vs −7.7° ± 8.7°), and C0‐C7 angles (−33.2° ± 13.0° vs −52.8° ± 19.2°), but a larger absolute value of flexion ROM in C2‐C7/BV‐C7 wall angle (−33.9° ± 14.8° vs −8.2° ± 15.1°).ConclusionThe cervical spine was stiffer in BI patients than the asymptomatic individuals, especially in the upper cervical curvature. The negative correlation between upper and lower cervical curvatures was more obvious in BI patients.

Study of the kinematic variables of unilateral and habitual mastication of healthy individuals.

To describe and compare the temporal-spatial kinematic variables of mandibular movement during deliberate unilateral and habitual mastication in healthy young-adult individuals. The study sample was composed of eight male healthy volunteers aged 19 to 24 years. The kinematic data were obtained using a motion analysis system - Qualisys Track Manager (QTM) ProReflex MCU. Recordings were performed during deliberate unilateral mastication (UM) and habitual mastication (HM) of firm-consistency gummy candy. The following variables were analyzed: (1) masticatory sequence: duration, number of masticatory cycles, and chewing rate; (2) masticatory cycle: duration, vertical and medial-lateral mandibular range of motion in relation to the skull, and maximum velocity during the opening and closing phases. Data of the variables were compared during UM and HM by the paired t test, and the effect sizes ('d' Cohen) were calculated. Regarding the variables of the masticatory sequence, smaller chewing rate was observed for UM compared with that for HM (1.19±0.21Hz and 1.29±0.16Hz, respectively, p=0.004, d=0.53). Smaller values of maximum velocity during the opening (MU=67.4 mm/s and MH=80.02, p=0.053, d=0.80) and closing (MU=71.77±9.35mm/s and MH=3.51±7mm/s, p=0.014, d=0.79) phases of the masticatory cycle were observed in deliberate unilateral mastication compared with those in habitual mastication. Kinematic variables associated with the sequence and cycle of mastication are influenced by the chewing pattern adopted - deliberate unilateral or habitual.

Arthroplasty of the distal ulna distal in managing patients with post-traumatic disorders of the distal radioulnar joint: measurement of quality of life

ObjectiveTo measure the quality of life and clinical–functional results from patients diagnosed with osteoarthrosis of the distal radioulnar joint who underwent surgical treatment using the technique of total arthroplasty of the ulna, with a total or partial Ascension® prosthesis of the distal ulna. MethodsTen patients were evaluated after 12 months of follow-up subsequent to total or partial arthroplasty of the distal ulna. All of them presented post-traumatic osteoarthrosis and/or chronic symptomatic instability of the distal radioulnar joint. The study was prospective. Seven patients had previously undergone wrist procedures (two cases with Darrach, three with Sauvé–Kapandji and two with ligament reconstruction of the fibrocartilage complex) and three presented fractures of the distal ulna that evolved with pain, instability and osteoarthrosis of the distal radioulnar joint. The following were assessed: quality of life (DASH scale); percentage degree of palm grip strength (kgf) and pronosupination range of motion in relation to the unaffected side; pain (VAS); return to work; subjective evaluation of radiography; and complications. ResultsThe patients presented a mean range of motion of 174.5° (normal side: 180°). Quality of life was analyzed by applying the DASH questionnaire and the mean value found was 5.9. The mean pain score using the VAS was 2.3. The mean degree of palm grip strength (kgf) was 50.7, which represented 90.7% of the strength on the unaffected side. The complication rate was 10%: this patient presented slight dorsal instability of the ulna and persistent pain, and did not return to work. This patient is still being followed up in the outpatient clinic and occupational therapy sector, with little improvement. He does not wish to undergo a new procedure. The mean length of follow-up was 16.8 months, with a minimum of 10 and maximum of 36 months. ConclusionThis concept is subject to the test of time. Implantation of a prosthesis is a very interesting addition to the surgical arsenal for those who are specialists in hand surgery. Arthroplasty of the distal ulna is a safe and effective method with clinical–functional and quality-of-life improvements for patients and presents a low complication rate.

Artroplastia de ulna distal no manejo dos pacientes com distúrbios pós‐traumáticos da articulação radioulnar distal: mensuração da qualidade de vida

ObjectiveTo measure the quality of life and clinical‐functional results from patients diagnosed with osteoarthrosis of the distal radioulnar joint who underwent surgical treatment using the technique of total arthroplasty of the ulna, with a total or partial Ascension® prosthesis of the distal ulna. MethodsTen patients were evaluated after 12 months of follow‐up subsequent to total or partial arthroplasty of the distal ulna. All of them presented post‐traumatic osteoarthrosis and/or chronic symptomatic instability of the distal radioulnar joint. The study was prospective. Seven patients had previously undergone wrist procedures (two cases with Darrach, three with Sauvé‐Kapandji and two with ligament reconstruction of the fibrocartilage complex) and three presented fractures of the distal ulna that evolved with pain, instability and osteoarthrosis of the distal radioulnar joint. The following were assessed: quality of life (DASH scale); percentage degree of palm grip strength (kgf) and pronosupination range of motion in relation to the unaffected side; pain (VAS); return to work; subjective evaluation of radiography; and complications. ResultsThe patients presented a mean range of motion of 174.5° (normal side: 180°). Quality of life was analyzed by applying the DASH questionnaire and the mean value found was 5.9. The mean pain score using the VAS was 2.3. The mean degree of palm grip strength (kgf) was 50.7, which represented 90.7% of the strength on the unaffected side. The complication rate was 10%: this patient presented slight dorsal instability of the ulna and persistent pain, and did not return to work. This patient is still being followed up in the outpatient clinic and occupational therapy sector, with little improvement. He does not wish to undergo a new procedure. The mean length of follow‐up was 16.8 months, with a minimum of 10 and maximum of 36 months. ConclusionThis concept is subject to the test of time. Implantation of a prosthesis is a very interesting addition to the surgical arsenal for those who are specialists in hand surgery. Arthroplasty of the distal ulna is a safe and effective method with clinical‐functional and quality‐of‐life improvements for patients and presents a low complication rate.

Lower Extremity Strength and the Range of Motion in Relation to Squat Depth

The purpose of this study was to determine which variables of the range of motion (ROM) and strength of the hip, and ankle are associated with squat depth. In total, 101 healthy subjects (64 males, 37 females) participated in the study. Outcome measures consisted of the ROM of hip flexion, hip internal rotation, external rotation, ankle dorsiflexion with an extended and flexed knee joint, and strength of the hip flexor and ankle dorsiflexor. Squat depth was measured using SIMI motion analysis software. Pearson correlation was used to determine the relationship between variables and squat depth. Multiple stepwise regression analysis was performed to determine variables associated with squat depth. The multiple regression model indicated that ankle dorsiflexion with a flexed knee and the hip flexion ROM were significantly associated with squat depth in male subjects (R2 = 0.435) and ankle dorsiflexion with an extended knee and dorsiflexor strength were significantly associated with squat depth in female subjects (R2 = 0.324). Thus, exercises to increase the ROM of the ankle dorsiflexion, hip flexion, and dorsiflexor strength can be recommended to improve squat performance. Future studies should assess an increased ROM of the ankle dorsiflexion, hip flexion, or dorsiflexor strength effect on deep squat performance.

Cervical spine injuries and flexibilities following axial impact with lateral eccentricity.

Determine the effects of dynamic injurious axial compression applied at various lateral eccentricities (lateral distance to the centre of the spine) on mechanical flexibilities and structural injury patterns of the cervical spine. 13 three-vertebra human cadaver cervical spine specimens (6 C3-5, 3 C4-6, 2 C5-7, 2 C6-T1) were subjected to pure moment flexibility tests (±1.5 Nm) before and after impact trauma was applied in two groups: low and high lateral eccentricity (1 and 150 % of the lateral diameter of the vertebral body, respectively). Relative range of motion (ROM) and relative neutral zone (NZ) were calculated as the ratio of post and pre-trauma values. Injuries were diagnosed by a spine surgeon and scored. Classification functions were developed using discriminant analysis. Low and high eccentric loading resulted in primarily bony fractures and soft tissue injuries, respectively. Axial impacts with high lateral eccentricities resulted in greater spinal motion in lateral bending [median relative ROM 3.5 (interquartile range, IQR 2.3) vs. 1.4 (IQR 0.5) and median relative NZ 4.7 (IQR 3.7) vs. 2.3 (IQR 1.1)] and in axial rotation [median relative ROM 5.3 (IQR 13.7) vs. 1.3 (IQR 0.5), p < 0.05 for all comparisons] than those that resulted from low eccentricity impacts. The developed classification functions had 92 % classification accuracy. Dynamic axial compression loading of the cervical spine with high lateral eccentricities produced primarily soft tissue injuries resulting in more post-injury spinal flexibility in lateral bending and axial rotation than that associated with the bony fractures resulting from low eccentricity impacts.

Critical Factors in Opening Pharmaceutical Packages: a Usability Study among Healthcare Workers, Women with Rheumatoid Arthritis and Elderly Women

This cross-sectional study compared the usability of pharmaceutical packages to determine the critical factors involved in packages with different opening mechanisms. Four packaging types (a bottle with a screw cap, a box with a pill plate, disposable plastic droppers with a container and a jar with a hinge cap) were evaluated by 45 women (nurses, older women and women with rheumatoid arthritis). Usability was evaluated for subjective measures related to the ease of opening and for objective measures related to the time needed to open the packaging, electrical muscular activity (electromyography, EMG) and ranges of motion of the upper extremities.Of the arthritic women, 13% were unable to open the screw-cap bottle, and 20% did not succeed in opening the plastic dropper packaging. Everyone else, except one older woman handling the plastic dropper packaging, managed to open all the packages. Regarding the ease of opening, the participants gave the plastic dropper packaging the lowest rating (p < 0.001). The arthritic women used greater relative biomechanical strain while opening the screw cap bottle and the box with pill plate compared with the other participants (p < 0.05), with the relative muscular strain in the forearm varying by 29–40% for the maximal EMG activity and the relative range of motion in the wrist being 70–90% of the maximal range of motion.These findings revealed both subjectively and objectively measured features on the usability of pharmaceutical packages. The comprehensibility of the opening mechanism and the ease of handling the package should be considered when user-friendly products are being created. Copyright © 2013 John Wiley & Sons, Ltd.

Biomechanical evaluation of posterior lumbar dynamic stabilization: an in vitro comparison between Universal Clamp and Wallis systems

Treatment of chronic low back pain due to degenerative lumbar spine conditions often involves fusion of the symptomatic level. A known risk of this procedure is accelerated adjacent level degeneration. Motion preservation devices have been designed to provide stabilization to the symptomatic motion segment while preserving some physiologic motion. The aim of this study was to compare the changes in relative range of motion caused as a result of application of two non-fusion, dynamic stabilization devices: the Universal Clamp (UC) and the Wallis device. Nine fresh, frozen human lumbar spines (L1-Sacrum) were tested in flexion-extension, lateral bending, and axial rotation with a custom spine simulator. Specimens were tested in four conditions: (1) intact, (2) the Universal Clamp implanted at L3-4 (UC), (3) the UC with a transverse rod added (UCTR), and (4) the Wallis device implanted at L3-4. Total range of motion at 7.5 N-m was determined for each device and compared to intact condition. The UC device (with or without a transverse rod) restricted motion in all planes more than the Wallis. The greatest restriction was observed in flexion. The neutral position of the L3-4 motion segment shifted toward extension with the UC and UCTR. Motion at the adjacent levels remained similar to that observed in the intact spine for all three constructs. These results suggest that the UC device may be an appropriate dynamic stabilization device for degenerative lumbar disorders.

Efeito da crioterapia e termoterapia associados ao alongamento estático na flexibilidade dos músculos isquiotibiais

The objective of the present study was to analyze the effect of cryotherapy and muscular warming on the flexibility of the hamstring muscles associated with three minutes of static stretching. Forty young male and female volunteers were randomly included in one of four groups: Group 1 – Control group, Group 2 – Three minutes of static stretching, Group 3 – Stretching preceded by warming using shortwave diathermy (20 minutes), and Group 4 – Stretching preceded by applying cryotherapy (20 minutes) to the posterior thigh region. The program consisted of three series of stretching during five consecutive days and flexibility was assessed by goniometric evaluations of the extensor angle of the knee at the beginning of the protocol, at the end of the day and at the end of the protocol. The intergroup comparison was made through ANOVA post-hoc Tukey and the intragroup by paired t test, all with 5% level of significance. The three experimental groups significantly increased their range of motion in relation to the control group. However, differences were not observed among groups submitted to the different stretching programs. In conclusion, increases in flexibility were due to stretching and did not depend on previous application of hyperthermia and/or hypothermia.

Efeito da crioterapia e termoterapia associados ao alongamento estático na flexibilidade dos músculos isquiotibiais

The objective of the present study was to analyze the effect of cryotherapy and muscular warming on the flexibility of the hamstring muscles associated with three minutes of static stretching. Forty young male and female volunteers were randomly included in one of four groups: Group 1 – Control group, Group 2 – Three minutes of static stretching, Group 3 – Stretching preceded by warming using shortwave diathermy (20 minutes), and Group 4 – Stretching preceded by applying cryotherapy (20 minutes) to the posterior thigh region. The program consisted of three series of stretching during five consecutive days and flexibility was assessed by goniometric evaluations of the extensor angle of the knee at the beginning of the protocol, at the end of the day and at the end of the protocol. The intergroup comparison was made through ANOVA post-hoc Tukey and the intragroup by paired t test, all with 5% level of significance. The three experimental groups significantly increased their range of motion in relation to the control group. However, differences were not observed among groups submitted to the different stretching programs. In conclusion, increases in flexibility were due to stretching and did not depend on previous application of hyperthermia and/or hypothermia.

Influência da estimulação elétrica nervosa transcutânea (TENS) associada ao alongamento muscular no ganho de flexibilidade

CONTEXTUALIZACAO: O aumento da tolerância a dor provocada pelo alongamento e um fator importante no ganho de flexibilidade. A Estimulacao Eletrica Nervosa Transcutânea (TENS) e uma importante terapia no tratamento da dor, porem seu uso durante alongamento nao foi investigado. OBJETIVO: Avaliar o efeito da associacao alongamento e TENS nos musculos isquiotibiais de mulheres saudaveis sobre ganho de flexibilidade. MATERIAIS E METODOS: Trinta mulheres foram aleatoriamente distribuidas em tres grupos (n=10): controle (C) e grupos de alongamento (Al e Al+TENS). Estes ultimos foram submetidos a alongamento estatico (tres repeticoes de 30 segundos) por duas semanas, sendo um deles (Al+TENS) submetido a aplicacao de TENS por dez minutos (100hz; 40µs) antes da manobra, com estimulacao presente durante a mesma. A flexibilidade foi avaliada pela extensao passiva do joelho antes e apos cada sessao, sendo retiradas fotografias para analise pelo software AUTOCAD. A dor percebida foi avaliada com uma Escala Numerica de 0 a 10 pontos. Os dados foram analisados mediante o teste t de Student, para amostras independentes e analise de variância, considerando nivel de significância estatistica o valor de p<0,05. RESULTADOS: Os grupos Al e Al+TENS tiveram aumento da ADM em relacao ao C, mas nenhuma diferenca foi encontrada entre os dois primeiros quanto: ganho de flexibilidade apos duas semanas (Al+TENS: 17,53o±9,25/Al: 12,76o±8,75); ganho diario de flexibilidade (Al+TENS: 6,00o±1,79/Al: 5,20o±3,17); e dor percebida durante alongamento (mediana de cinco para ambos). CONCLUSOES: O uso da TENS associada ao alongamento nao promove maior ganho de flexibilidade muscular, em relacao ao alongamento isolado.

Influência do resfriamento e do aquecimento local na flexibilidade dos músculos isquiotibiais

Influence of local cooling and warming on the flexibility of the hamstring muscles Objective: The aim of this study was to analyze the acute and chronic effects of cooling and warming on hamstring muscle flexibility. Method: Forty volunteers were randomly included in one of four groups (n=10): 1) control group; 2) stretching group, using a sustain-and-relax technique on the hamstring muscles, for two consecutive weeks; 3) stretching group preceded by applying cryotherapy (25 minutes) to the posterior thigh region; 4) stretching group preceded by warming using shortwave diathermy (25 minutes). Muscle flexibility was assessed using a board coupled to a goniometric system specially prepared for evaluating the extensor angle of the knee. Results: The three experimental groups significantly increased their range of motion in relation to the control group. The mean daily gains (considered to be acute effects) showed significant differences in favor of the group subjected to cooling, in comparison with the other two (increases of 2.6 ± 0.9°, 4.3 ± 1.5° and 2.4 ± 0.7° for groups 2, 3 and 4, respectively, p= 0.008). With regard to chronic effects, there were no significant differences between the three experimental groups, but they all differed from the control group (increases of 1.5 ± 0.5°, 11.1 ± 6.1°, 14.4 ± 5.4° and 14.4 ± 6.2°, for groups 1, 2, 3 and 4, respectively). Conclusion: Stretching sessions applied daily significantly increased hamstring muscle flexibility. The acute effects were greatest in the group subjected to cooling, in comparison with the groups with stretching alone and stretching plus warming. The chronic effects were not influenced by warming or by cooling.

Verification of assemblability between toleranced parts

It is desirable for the assemblability of parts to be verified by the computer during the design stage when the tolerances on the parts are stored together with their geometric models and their assembled state. In this case, tolerances would need to be assigned systematically during the design stage while considering the assemblability in advance, which is an example of concurrent engineering activity. To realize the concepts described above, a new method was proposed to determine assemblability when tolerance information and the geometric model of the parts of an assembly in the assembled state are given. This method determines assemblability by subdividing the range of relative motion between parts until there exists a subdivided region that does not cause interference.

Biomechanical Model with Joint Resistance for Impact Simulation

Based on a general methodology using naturalco-ordinates, a three-dimensional whole body responsemodel for the articulated human body is presented inthis paper. The joints between biomechanical segmentsare defined by forcing adjacent bodies to share commonpoints and vectors that are used in their definition.A realistic relative range of motion for the bodysegments is obtained introducing a set of penaltyforces in the model rather than setting up newunilateral constraints between the system components.These forces, representing the reaction momentsbetween segments of the human body model when thebiomechanical joints reach the limit of their range ofmotion, prevent the biomechanical model from achievingphysically unacceptable positions. Improved efficiencyin the integration process of the equations of motionis obtained using the augmented Lagrange formulation.The biomechanical model is finally applied indifferent situations of passive human motion such asthat observed in vehicle occupants during a crash orin an athlete during impact.

Angular-momentum transfer in collisional ionization.

The double-differential cross sections for ionization in [ital e][sup [minus]]+H([ital nl]) collisions are reported as a function of the impact energy [ital E] of the projectile, final energy [ital E][sub [ital f]], and angular momentum [ital L][sub [ital f]] of the ejected electron. This process is assumed to occur via an energy-changing and angular-momentum-changing binary collision between the Rydberg electron in a prepared state ([ital nl]) and the projectile electron [ital e][sup [minus]] or H(1[ital s]). The atomic projectile can also be excited during this process. Systematic trends in the variation of the classical ionization cross sections with final angular momentum [ital L][sub [ital f]] of the ejected electron are discussed and are in accord with a previous quantal treatment, whereby the nondipole ([Delta][ital l][gt]1) transitions are much more important in the low- and intermediate-energy range of relative motion, and that the value of the final angular momentum of the ejected electron depends mainly on the initial value of the principal quantum number [ital n] of the Rydberg atom.

STABILITY IN RELATION TO HUMERAL HEAD RETROVERSION AFTER SURGICAL TREATMENT OF RECURRENT ANTERIOR SHOULDER DISLOCATIONS

This study reports the influence of the retroversion angle on the postoperative stability in 50 patients operated on for recurrent shoulder dislocations. Fifty-two shoulders were reviewed by radiographic and clinical examinations. Particular attention was focused on humeral head retroversion, shoulder stability, and range of motion in relation to surgical technique. The retroversion angle was significantly reduced in 30 of 47 shoulders, for which satisfactory radiographs could be achieved. Mean humeral head retroversion was 24 degrees for both dominant and nondominant shoulders. Forty-eight of 52 reexamined shoulders became stable. Four had remaining instability following a Putti-Platt procedure, with a mean retroversion angle of 18 degrees. A reduced humeral head retroversion is therefore proposed as an important factor in creating instability, and may be one explanation for failed stability after soft tissue repair. Irrespective of the type of surgical procedure (Bristow or Putti-Platt), there was a significant decrease in range of shoulder rotation in the operated shoulder compared to the contralateral stable shoulder and to reference values for normal controls. However, decreased rotation was not found to impair shoulder function, and 48 of the 50 reexamined patients generally improved after surgery.