Proximal Wrist Research Articles

A biomechanical model of the wrist joint for patient-specific model guided surgical therapy: Part 2.

An enhanced musculoskeletal biomechanical model of the wrist joint is presented in this article. The computational model is based on the multi-body simulation software AnyBody. Multi body dynamic musculoskeletal models capable of predicting muscle forces and joint contact pressures simultaneously would be valuable for studying clinical issues related to wrist joint degeneration and restoration. In this study, the simulation model of the wrist joint was used for investigating deeper the biomechanical function of the wrist joint. In representative physiological scenarios, the joint behavior and muscle forces were computed. Furthermore, the load transmission of the proximal wrist joint was investigated. The model was able to calculate the parameters of interest that are not easily obtainable experimentally, such as muscle forces and proximal wrist joint forces. In the case of muscle force investigation, the computational model was able to accurately predict the computational outcome for flexion and extension motion. In the case of force distribution of the proximal wrist joint, the model was able to predict accurately the computational outcome for an axial load of 140 N. The presented model and approach of using a multi-body simulation model are anticipated to have value as a predictive clinical tool including effect of injuries or anatomical variations and initial outcome of surgical procedures for patient-specific planning and custom implant design. Therefore, patient-specific multi-body simulation models are potentially valuable tools for surgeons in pre- and intraoperative planning of implant placement and orientation.

Volar Central Portal in Wrist Arthroscopy.

Background Nowadays, the wrist is not limited to a dorsal visualization; the joint can be thought of as a "box," which can be visualized from almost every perspective. The purpose of this study was to describe a new volar central portal for the wrist, following three principles: a single incision that allows access to both the radiocarpal and midcarpal joints, centered on the lunate, with the volar structures at risk protected not only by retractors, but also by tendons. Description of Technique The incision begins in the distal wrist crease and extended 1.5 cm proximally up to the proximal wrist crease, following the axis of the third intermetacarpal space. The flexor superficialis tendons are identified and retracted toward the radial side. Next, the fourth and fifth flexor digitorum profundus tendons are retracted toward the ulnar side, while the third and second tendons are retracted toward the radial side. The volar central midcarpal portal is performed under direct vision just over the anterior horn of the lunate through the Poirier space. The volar central radiocarpal portal is created under the lunate through the interval between the ulnocarpal ligaments and the short radioulnar ligament. Methods An anatomical study was performed on 14 cadaver specimens. Two data were recorded: iatrogenic injuries of the structures at risk and the distances to the structures at risk. Results The median (interquartile range [IQR]) distances from the volar central radiocarpal portal to the median nerve, palmar cutaneous branch of the median nerve, and ulnar neurovascular bundle were 10.5 (7.8-15.0), 18.5 (15.8-20.3), and 7.0 (5.0-10.5) mm, respectively. The median (IQR) distances from the volar central midcarpal portal to the median nerve, palmar cutaneous branch of the median nerve, and ulnar neurovascular bundle were 7.0 (4.8-10.3), 16.0 (14.8-19.0), and 4.5 (3.8-9.0) mm, respectively. No iatrogenic injuries were observed. Conclusion The volar central portal is reproducible and safe. The risk of iatrogenic injury is low. The capsule is pierced through one of its thinner portions, and both the radiocarpal and midcarpal joints can be inspected through one single incision.

Flexor pollicis longus repair in a patient with Linburg-Comstock anomaly: A case report

Background: We present a patient with this anomaly who sustained a saw cut injury to his hand resulting in severance of the FPL and bilateral digital nerves of the thumb. Methods: A 36-year old male laborer who sustained a saw cut injury to his dominant right hand presented to the emergency department. The wound extended from the skin edge of the first web to the base of first metacarpal in the palm at Urbaniak zone 3. The FPL tendon and both digital nerves were cut. In the operating room, the wound was enlarged with Z incisions and a dissection deep into the wound was conducted. The cut end of the FPL tendon was found and secured using a different technique. Bilateral digital nerve repair was performed with interpositional grafting of the lateral antecubital cutaneous nerve bundles. Results: At the end of the rehabilitation program, the thumb recovered full range of motion, and physical examination revealed synchronous flexion movement (synkinesis) of the thumb and index finger. Conclusion: Flexor pollicis longus tendon lacerations are common in the clinical practice of hand surgeons. Making a separate proximal wrist incision is a very useful technique to reach a proximal tendon stump. Otherwise, aggressive maneuvers may cause additional damage to the tendons involved and result in unpredicted outcomes. The attempts to retrieve the tendon at the injury site resulted in failure and gave a tethering sensation to the surgeon who recalled the Linburg-Comstock anomaly.

The total wrist arthroplasty

Traditional management of wrist arthritis consists of proximal row carpectomy, partial carpal fusions, or, in the event of pancarpal arthritis, total wrist fusion. Although proximal row carpectomy and partial wrist fusions preserve some motion at the wrist while relieving pain symptoms, the quality of results obtained from these procedures is not predictable or optimal in many instances. Total wrist fusions are credited with universal pain relief at the expense of wrist motion. However, critical analysis of the results of total wrist arthrodesis shows that the results are not always consistent with what has been claimed and that pain relief is unpredictable at best. In a recent study, 14 of 22 patients who had undergone wrist arthrodesis had residual pain, and 4 of these patients had severe pain 6 years later. In another study, only 6 of 36 patients remained pain-free 4 years after wrist arthrodesis. Moreover, many patients do not like loss of motion in their wrists. In a study of wrist arthrodesis, only 40% of patients were satisfied at 1 year. In another study, 100% of patients who had wrist arthrodesis indicated that they would have a procedure performed so they could move their wrists again. Management of hip, knee, ankle, and shoulder joints has evolved from arthrodesis to arthroplasty. The wrist joint awaits the same pattern of evolution with the advent of reliable designs. In this presentation, I will first describe the design rationale of the Stryker ReMotion Total Wrist arthroplasty along with historical antecedents. Next, I will outline the technique of implantation with tips and tricks for special situations. Finally, I will discuss 10-year results and comment on future prospects of total wrist arthroplasty.

The Management of Kienböck Disease: A Survey of the ASSH Membership.

Background The purpose of this study was to determine the current trends and common practices for the treatment of Kienböck disease at different stages. Question/Purpose To determine the current trends and common practices by hand surgeons for the treatment of Kienböck disease. Methods A survey with hypothetical Kienböck disease cases stratified by the Lichtman staging system was distributed to the American Society for Surgery of the Hand (ASSH) members. Questions and responses reflected common treatment strategies. Results Of a total of 375 worldwide respondents, preferred treatments of Kienböck disease were as follows: for Stage I disease, an initial trial of splinting was favored (74%), followed by radial shortening osteotomy for continued symptoms. For Stage II disease, 63% of surgeons preferred surgical intervention, particularly radial shortening osteotomy. For Stage IIIa with negative ulnar variance, 69% chose radial shortening osteotomy. Responses were heterogeneous for Stage IIIa Kienböck with positive variance, and capitate shortening osteotomy and vascularized bone grafting were preferred. Salvage procedures predominated for Stage IIIb disease, including proximal row carpectomy (PRC; 42%), intracarpal arthrodesis (21%), and total wrist fusion (10.7%). Similarly, Stage IV disease was treated by 87% of respondents by either PRC or wrist fusion. Without regard to stage of disease, 90% of participants reported using the same Lichtman staging to guide treatment and would also alter treatment strategy based upon ulnar variance. Conclusions Most respondents used Lichtman staging and ulnar variance to guide treatment decisions. Results indicate that the most common surgical treatments were radial shortening osteotomy for early disease and PRC in later stages. Level of Evidence Level IV, Economic/Decision Analysis.

Morphometry and anatomical variations of flexor digitorum superficialis

Abstract Introduction: Flexor digitorum superficialis (FDS) takes its origin by two heads: humero ulnar and radial.. The FDS is considered to be potential flexor of proximal interphalangeal, metacarpophalnageal and wrist joints through its insertion to the middle phalanges of lateral 4 fingers. Aim of the study was to conduct a morphometric study on FDS and to evaluate its variants in cadaveric limbs. Materials and Methods: The study was carried out on 25 right and 23 left upper limbs belonging to formalin fixed adult cadavers. Lengths of humeral, ulnar, radial heads of the muscle as well as its tendons were separately measured using digital caliper. Mean length of muscle bellies of humeral head, tendinous length and musculotendinous length tabulated. Results: A unique muscle belly arising from the deeper surface of left FDS as a tendon, proximal to flexor retinaculum, entering in the palm after passing through the carpal tunnel was observed. The muscle was inserted into the middle phalanx of index finger. Conclusion: Studies on absolute length of FDS are rare. The present study has significant influence on length tension relationship of afore mentioned muscle. The hazardous effects of anomalous belly of FDS and its consequences were also discussed.

Imaging of compound palmar ganglion with pathologic correlation

Compound palmar ganglion, or chronic flexor tenosynovitis, most commonly of tuberculousorigin, is a rare extrapulmonary manifestation of tuberculosis (TB). The flexor synovialsheath is not a common site for TB but, once involved, causes rapid involvement of all flexortendons. We discuss the case of a 70-year-old farmer who presented to us with pain and progressive swelling of the palmar aspect of the wrist. On clinical examination, swelling both above and below the proximal wrist crease was found, with positive cross-fluctuation. Onultrasonography and magnetic resonance imaging, features suggestive of compound palmarganglion were present. The patient underwent surgical resection (extensive tenosynovectomy)and chemotherapy. Post-operative histopatholgical findings correlated with the radiological features.

Distal Scaphoid Resection for Degenerative Arthritis Secondary to Scaphoid Nonunion: A 20-Year Experience

To evaluate the long-term results of distal scaphoid excision for degenerative arthritis secondary to scaphoid nonunion and compare them with our original results published in 1999. Nineteen patients who were treated by distal scaphoid resection arthroplasty from 1987 through 2010 were included. The mean follow-up was 15 years (range, 10-25 y) vs 4 years in the previous study. Clinical evaluation included measurement of the visual analog pain scale, wrist range of motion, and grip strength. Radiographs were taken at follow-up to assess for signs of arthritis and wrist collapse. The outcomes of this procedure include increased grip strength and total arc of motion, a small decrease in revised carpal height ratio, and a small increase in radiolunate angle. Two patients failed distal scaphoid resection arthroplasty necessitating proximal row carpectomy (1) and wrist arthrodesis (1) for recalcitrant pain. More than half of the remaining patients developed midcarpal arthritis on radiographs that was asymptomatic. No patients developed radiolunate arthritis. This study showed that distal scaphoid resection arthroplasty produced favorable, long-term clinical results and did not result in noteworthy wrist collapse. Midcarpal arthritis, which may develop after the procedure, did not cause appreciable deterioration in patient outcomes. This procedure also did not eliminate the option of using additional, more conventional reconstructive procedures if needed. Therapeutic IV.

Upper extremity orthoses use in amyotrophic lateral sclerosis/motor neuron disease: three case reports.

Central to the armamentarium of a hand therapist is evaluation for successful orthotic use. Orthoses can have a profound effect on quality of life in persons with amyotrophic lateral sclerosis (ALS)/motor neuron disease (MND). The purposes of orthoses are to decrease the effects of muscle imbalance, provide assistance in performance of activities of daily living (ADLs), prevent joint contracture, and relieve pain. There are few published accounts on the usefulness of orthoses and ALS. The purpose of this paper is to expand the body of literature by describing three successful cases. Three cases illustrate effects on weakened proximal muscles, wrist extensors, thenar musculature, and intrinsic muscles. The primary outcome measure is patient report, but functional rating scales, goniometry, quality of life scores, and pinch strength when obtainable are described. Due to the progressive nature of the disease, outcome measures can be inconclusive. Patient report of increased life satisfaction and ability to participate in daily life is the critical outcome in these case examples. In all cases, satisfaction increased. Some of the stated changes include the following: ability to manipulate objects, grip, eat, wipe face, hold phone, use iPad®, and adjust hat. Upper extremity orthotic use can be a beneficial adjunct contributing to the quality of life for individuals with ALS/MND. We have observed positive responses in pain control, contracture management, functional positioning, and increased independence with the use of orthoses. Designing appropriate means of studying effects of orthosis intervention is deficient in the current scientific literature.

Outcomes assessment of lunate replacement arthroplasty with intrinsic carpal ligament reconstruction in Kienböck's disease.

With advanced Kienböck's disease, hyaline cartilage delamination or bone fragmentation render the lunate unsalvageable. Common surgical options are proximal row carpectomy, scaphotrapeziotrapezoid fusion, scaphocapitate fusion, or total wrist fusion. The purpose of this study was to prospectively evaluate the clinical and radiographic outcomes of one alternative: lunate prosthetic replacement arthroplasty combined with reconstruction of the scapholunate and lunotriquetral interosseous ligaments using the flexor carpi radialis tendon. Eligible patients with advanced Kienböck's disease and an unsalvageable lunate were included in this prospective study on a self-selected basis, forming a study group of 13 consecutive patients, 6 males and 7 females with a mean age of 40. Clinical and radiographic measurements were compared at a mean follow-up of 30.3months from surgery with a paired, single-tailed, Student's t test using a p value of 0.05 as statistically significant. Mean preoperative/postoperative clinical measurements were as follows: wrist flexion 29.2°/43.3°, wrist extension 24.2°/53.3°, absolute value grip strength 12.3/31.5kg, grip strength vs. contralateral 36.5/85.2%, and DASH scores 39.1/7.7. Mean initial/immediate postoperative/final radiographic measurements were the following: scapholunate angle 64.2°/46.7°/46.4°, radioscaphoid angle 64.6°/42.1°/45°, and modified carpal height ratio 1.20/1.62/1.59. Preoperative to postoperative differences were all statistically significant. Although these subjective and objective results reflect substantial improvement, there remain recognizable deficiencies in both prosthetic design and surgical strategy that require further modification.

Minimally invasive plate osteosynthesis for distal radius fractures

Background:Fractures of distal radius are common injury in all age groups. Cast treatment with or without close reduction is a viable option. However, the results are often unsatisfactory with restricted function. The open reduction and internal fixation often results in extensive soft tissue dissection and associated high rates of infect and delayed/nonunion. The distractor/external fixator have reported good functional and anatomical results but the incidence of pin traction infection nerve injury and cosmedic deformity are high. We introduced a modified operative technique for minimally invasive plate osteosynthesis (MIPO) for distal radial fracture and evaluated the functional outcomes and complications.Materials and Methods:22 distal radial fractures (10 left, 12 right) were treated using the MIPO technique and two small incisions with a palmar locking plate from August 2009 to August 2010. The wrist function was assessed according to Dienst wrist rating system, and postoperative complications were recorded.Results:According to Dienst wrist rating system, 13 patients showed excellent results, 6 cases showed good results and 3 patients had moderate results. No patient had poor results. Thus, the excellent and good rate was 86.4%. One patient had anesthesia in the thenar eminence and this symptom disappeared after 3 months. One patient had delayed healing in the proximal wrist crease. Two patients had mild pain on the ulnar side of the wrist and two patients had limited wrist joint function.Conclusion:The MIPO technique by using two small palmar incisions is safe and effective for treatment of distal radial fractures.

Osteoporosis and risk of fracture, analysis on a population admitted in rehabilitation post-acute

In the context of osteoporosis the presence of a fragility fracture (vertebral or non-vertebral) constitutes a condition of severe osteoporosis; the most common fractures due to this disease are the responsibility of the proximal femur (hip), spine and wrist representing one of the leading causes of disability in the elderly population, as well as one of the greatest contributions to health care costs. By analyzing a population of patients hospitalized at a rehabilitation ward for post-acute outcomes of hip fracture fragility it was able to observe the effectiveness of preventive intervention, the risk of vertebral fractures and the importance of comorbidity.

AB0332 An audit to examine whether there is a correlation between levels of anti-cyclic citrullinated peptide (CCP) antibody titres and joint findings on musculoskeletal ultrasound scan in rheumatoid arthritis

BackgroundAnti-CCP antibodies (Abs) currently make an important part of the workup in patients with suspected rheumatoid arthritis (RA) and can be detected prior to the development of symptoms [1]. They...

Free autogenous palmaris longus tendon transplantation in treatment of cicatricial ectropion

Objective To investigate the method and effect of free autogenous palmaris longus tendon transplantation in the treatment of moderate and severe cicatricial ectropion.Methods The autogenous palmaris longus tendon was obtained through a small lateral proximal wrist band incision (lengths from 4 cm to 6 cm).The graft was properly sutured to the exposed tarsus and the attachments of inner and outer canthus.Local skin flap was rotated to cover the tendon and to repair the wound.Results Six man (8 eyes) with moderate and severe cicatricial ectropion were treated in our department,all case of ectropion were rectified after operation.The eyeballs were well contacted with lower eyelid and no recurrence of eetropion,epiphora and corneal exposure during 6 to 18 months' follow-up.The tension of the lower eyelid was abiding with satisfied effects.Conclusions The palmaris longus tendon is easy to obtain and there is no harm to the donor site.The cicatricial ectropion could be repaired with self-palmaris longus tendon transplantation with lasting effect and the recurrence rate is lower,which is well worthy popularizing. Key words: Palmaris longus tendon; Graft; Cicatricial ectropion

Effect of Hand Size on the Stimulation Intensities Required for Median and Ulnar Sensory Nerve Conduction Studies

ObjectivesTo examine the effect of hand size on median and ulnar sensory nerve conduction study (NCS) stimulation intensities and pain scores. DesignProspective, single group design to compare main outcomes by using a standard distance of 14cm versus the proximal wrist crease in 3 different hand sizes. SettingElectrodiagnostic laboratory in a department of rehabilitation medicine. ParticipantsHealthy volunteers (N=25) aged 20 to 30 years. InterventionsHand size was determined, based on the distance between the proximal wrist crease and the base of the long finger, resulting in 3 groups (≤11cm, >11–12cm, >12cm) with 12 hands per group. Antidromic median and ulnar sensory NCSs were performed. The nerves were randomly stimulated at the proximal wrist crease and 14cm from the recording electrode. Main Outcome MeasuresSupramaximal stimulation intensities and 10-cm visual analog scale (VAS) pain scores at each stimulating site were recorded and compared. ResultsThirty-six hands from 25 young healthy volunteers were studied. There was no correlation between the body mass index (BMI) and stimulation intensity, and BMI and VAS (r<0.3) in both median and ulnar nerves. Overall analysis showed that the stimulation intensity and VAS at 14cm were significantly greater than at the proximal wrist crease. Subgroup analysis showed the same result in all groups for the median sensory NCS, but in only the small hand group for the ulnar sensory NCS. ConclusionsWhen the same distance is used for NCSs regardless of patient size, smaller individuals required greater stimulation and reported greater discomfort. This may reflect greater nerve depth and suggests that one size fits all may not be the best approach with NCSs.

Minimally invasive palmar locking plate for treatment of distal radius fractures

Objective To investigate the clinical effects,feasibility,points for attention and complications of treating distal radial fractures through minimally invasive palmar locking plate.Methods A total of 22 patients with distal radial fractures managed by minimally invasive palmar locking plate from August 2009 to August 2010 were enrolled in the study.According to AO classification,there were five patients with type A2 fractures,three with type A3,four with type B1,seven with type B3,two with type C1 and one with type C2.Two vertical or parallel palmar incisions of 2 cm long were performed.The distal transverse incision was along the proximal wrist crease,while the distal and proximal vertical incisions were close to the radial side of flexor carpi radialis.Then,palmar locking plate was inserted through deep pronator quadratus.Results Follow-up period was 10-18 months(mean,12 months).According to Dienst function evaluation criteria,the results were excellent in 13 patients,good in six,fair in three and poor in zero,with excellence rate of 86％.Complications were as follows:one patient had delayed healing of proximal wrist crease incision;one patient had numbness of thenar eminence and the symptom was disappeared three months postoperatively;two patients remained pain on ulnar side of the wrist joint;two patients had limited function of the wrist joint.Conclusions Minimally invasive palmar locking plate is safe,mini-invasive and reliable when treating distal radial fractures,which is conducive to early functional exercise.Furthermore,the method achieves satisfactory appearance of the incision which meets the minimal invasion and thus deserves clinical practice. Key words: Radius fractures; Surgical procedures,minimally invasive; Volar plate

Anatomical basis and clinical application of the ulnar forearm free flap for head and neck reconstruction

This study was designed to investigate the anatomical features and applications of the ulnar forearm flap in head and neck reconstructive surgery. A prospective study was designed to include 50 ulnar forearm free flap transplants in 50 patients. Patient defects requiring reconstructive surgery involved the buccal mucosa, tongue, floor of the mouth, upper or lower gums, lips, soft palate, and scalp. Twenty ulnar forearm flaps were analyzed along the entire ulnar artery to determine the anatomy and distribution of the ulnar artery septocutaneous perforators. All 50 flaps were successfully transplanted into their respective sites. The mean diameters of the ulnar artery and vein were 2.3 ± 0.6 mm and 1.7 ± 0.6 mm, respectively. Arterial and venous size mismatch was experienced in 12 and 33 flaps, respectively. The mean number of sizable perforators was 4.3 ± 1.2, and most of the first perforators were located within 5 cm of the proximal wrist crease. None of the patients experienced long-term complications concerning the ulnar nerve. The ulnar forearm flap is a reliably consistent source of free flap transfer because it harbors constant septocutaneous perforators and produces minimal donor site morbidities for head and neck reconstructive surgery.

Functional Outcome of Open Reduction of Chronic Perilunate Injuries

Perilunate injuries are complex and occasionally go unrecognized acutely. Open reduction and internal fixation is a valid treatment option for these injuries. The purpose of this study was to evaluate the functional outcome of treating chronic perilunate injuries with open reduction and internal fixation. Between 1998 and 2007, we treated 24 patients for chronic perilunate injuries. We excluded 5 patients from this study because they underwent proximal row carpectomy or limited wrist arthrodesis. We treated the remaining 19 patients with open reduction and internal fixation. Mean time from injury to surgery was 29 weeks. All patients were men, with a mean age of 27 years. A total of 13 patients had fracture dislocations (group 1); of these, 11 were transscaphoid and 2 were transscaphoid transcapitate fracture dislocations. Six patients had perilunate dislocations (group 2). Postoperative follow-up averaged 58 months. All carpal fractures healed at an average of 18 weeks. At final evaluation, the average pain scores during rest, daily activities, and manual work on a 20-point visual analog scale were 0, 2, and 3, respectively, with no significant difference between groups. The active extension and flexion of the wrist averaged 39% and 52% of the uninjured side, respectively. Grip strength averaged 87% of the uninvolved extremity. According to the Mayo wrist scoring system, 58% of all patients (69% of group 1 and 33% of group 2) achieved good to excellent results. A total of 18 patients returned to their original work activities; 14 patients (74%) were very satisfied. No patients required secondary procedures. Despite late presentation, patients with chronic perilunate injuries can be treated with open reduction internal fixation, with satisfactory results. Patients with lesser arc injuries have less successful outcome. Patients with irreducible dislocations or major articular damage may require wrist salvage procedures.

Magnetic resonance imaging of triangular fibrocartilage

Due to their small size and complex structure, diagnosing injury of the proximal wrist ligamentous structures can be challenging. The triangular fibrocartilage complex (TFCC) is an example of one such structure, for which lesions may be missed unless high-resolution magnetic resonance imaging (MRI) obtained via a standard matrix with a small field of view or high-resolution imaging matrix (small spatial scale matrix elements/large matrix size) is utilized. While there have been recent advances in increasing MRI spatial resolution, attempts at improved visualization by isolated increase in the spatial resolution will be ineffective if the signal-to-noise ratio (SNR) of the images obtained is low. Additionally, high contrast resolution is important to facilitate a more precise visualization of these structures and their pathology. Thus, a balance of the three important imaging factor qualifications of high spatial resolution, high SNR, and high contrast resolution must be struck for optimized TFCC and wrist imaging. The goal of this article, then, is to elucidate the theory and techniques of effective high-resolution imaging of the proximal ligamentous structures of the wrist, balancing SNR and high contrast resolution constraints, and focusing on imaging of the TFCC as a prototypical example.

Investigation of Vibratory Detection Thresholds on Proximal Phalange and Wrist in Blind and Visually Impaired Teenagers

The paper presents results concerning vibratory detection thresholds measured on a wrist and proximal phalange and ngertips of the index, middle and ring ngers for blind and visually impaired teenagers. Subjects with vision dysfunctions were divided into two groups: congenitally blind and visually impaired. The study tested 10 handicapped individuals (5 congenitally blind and 5 visually impaired) and 10 sighted persons making reference groups chosen to be adequate in terms of age, gender, body mass and height. To date, no study has described results of such experiments for blind/visually handicapped teenagers. Vibratory perception thresholds were tracked using the Bekesy algorithm. The thresholds were investigated as a function of stimulating force frequency and magnitude or an area of a stimulating probe. Threshold values obtained for the wrist were higher than values obtained for proximal phalange and ngertips. It was shown that the performance of blind/visually impaired teenagers was not better than their sighted counterparts. Suggestions about technical form and physical parameters of a vibrating device signalling places particularly dangerous for blind/visually handicapped people were formulated.