Effects of training and using an audio-tactile sensory substitution device on speech-in-noise understanding

Understanding speech in background noise is challenging. Wearing face-masks, imposed by the COVID19-pandemics, makes it even harder. We developed a multi-sensory setup, including a sensory substitution device (SSD) that can deliver speech simultaneously through audition and as vibrations on the fingertips. The vibrations correspond to low frequencies extracted from the speech input. We trained two groups of non-native English speakers in understanding distorted speech in noise. After a short session (30-45 min) of repeating sentences, with or without concurrent matching vibrations, we showed comparable mean group improvement of 14-16 dB in Speech Reception Threshold (SRT) in two test conditions, i.e., when the participants were asked to repeat sentences only from hearing and also when matching vibrations on fingertips were present. This is a very strong effect, if one considers that a 10 dB difference corresponds to doubling of the perceived loudness. The number of sentence repetitions needed for both types of training to complete the task was comparable. Meanwhile, the mean group SNR for the audio-tactile training (14.7 ± 8.7) was significantly lower (harder) than for the auditory training (23.9 ± 11.8), which indicates a potential facilitating effect of the added vibrations. In addition, both before and after training most of the participants (70-80%) showed better performance (by mean 4-6 dB) in speech-in-noise understanding when the audio sentences were accompanied with matching vibrations. This is the same magnitude of multisensory benefit that we reported, with no training at all, in our previous study using the same experimental procedures. After training, performance in this test condition was also best in both groups (SRT ~ 2 dB). The least significant effect of both training types was found in the third test condition, i.e. when participants were repeating sentences accompanied with non-matching tactile vibrations and the performance in this condition was also poorest after training. The results indicate that both types of training may remove some level of difficulty in sound perception, which might enable a more proper use of speech inputs delivered via vibrotactile stimulation. We discuss the implications of these novel findings with respect to basic science. In particular, we show that even in adulthood, i.e. long after the classical "critical periods" of development have passed, a new pairing between a certain computation (here, speech processing) and an atypical sensory modality (here, touch) can be established and trained, and that this process can be rapid and intuitive. We further present possible applications of our training program and the SSD for auditory rehabilitation in patients with hearing (and sight) deficits, as well as healthy individuals in suboptimal acoustic situations.

Change in the temporal coordination of the finger joints with ulnar nerve block during different power grips analyzed with a sensor glove

Ulnar nerve injuries can cause deficient hand movement patterns. Their assessment is important for diagnosis and rehabilitation in hand surgery cases. The purpose of this study was to quantify the changes in temporal coordination of the finger joints during different power grips with an ulnar nerve block by means of a sensor glove. In 21 healthy subjects, the onset and end of the active flexion of the 14 finger joints when gripping objects of different diameters was recorded by a sensor glove. The measurement was repeated after an ulnar nerve block was applied in a standardized setting. The change in the temporal coordination of the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints with and without the nerve block was calculated within the same subject. In healthy subjects, the MCP joints started their movement prior to the PIP joints in the middle and ring finger, whereas this occurred in the reverse order at the index and little finger. The DIP joint onset was significantly delayed (P<0.01). With the ulnar nerve block, this coordination shifted towards simultaneous onset of all joints, independent of the grip diameter. The thumb and index finger were affected the least. With an ulnar nerve block, the PIP joints completed their movement prior to the MCP joints when gripping small objects (G1 and G2), whereas the order was reversed with larger objects (G3 and G4). The alterations with ulnar nerve block affected mainly the little finger when gripping small objects. With larger diameter objects, all fingers had a significant delay at the end of the PIP joint movement relative to the MCP and DIP joints, and the PIP and DIP joint sequence was reversed (P<0.01). Based on the significant changes in temporal coordination of finger flexion during different power grips, there are biomechanical effects of loss of function of the intrinsic muscles caused by an ulnar nerve block on the fine motor skills of the hand. This can be important for the diagnosis and rehabilitation of ulnar nerve lesions of the hand.

[Diagnostic ability of power measurement of different grip forms for distal median nerve lesion]

BACKGROUND

Peripheral lesions of the median nerve cause characteristic changes of the grip function of the hand. For evaluating grip force changes, measurement by dynamometers (JAMAR dynamometer and pinch dynamometer) is of high relevance. In this study the ability of grip force measurements of different grip forms was evaluated to discriminate between a simulated median nerve lesion and healthy subjects.

MATERIAL AND METHODS

In 21 healthy subjects, the grip force of power grip was measured by the JAMAR dynamometer at the second stage including measurement of force at the fingertips and the thenar by a sensor glove. With a pinch dynamometer the power of palmar abduction, precision grip, pincer grip and pinch grip was determined. Measurements were performed with and without median nerve block at the wrist.

RESULTS

In power grip of the JAMAR dynamometer at the second stage a significant reduction of the grip force of 13.4% was found (p < 0.03). The power distribution between the fingers D2-D5 did not change with median nerve block. The most relevant reduction of grip force in median nerve block compared with the healthy control was measured in palmar abduction (72.1%, p < 0.0002), followed by precision grip 31.0% (p < 0.0001), pincer grip 23.6% (p < 0.0004) and pinch grip 18.8% (p < 0.0002).

CONCLUSIONS

For the discrimination between healthy subjects and subjects with a median nerve block there was a limited relevance of the measurement of the power grip and force distribution at the fingers by the JAMAR dynamometer. However, the best distinction was observed by dynamometric measurement of other grips than power grip, such as palmar abduction, precision grip, pincer grip and pinch grip. The results could be relevant for the clinical diagnostics and rehabilitation of median nerve lesion, complementing the widespread measurement of the power grip by other grip forms.

[Linked Prosthesis for the Proximal Interphalangeal Joint: 17-Year Long-Term Results]

BACKGROUND/PURPOSE

Joint replacement is a widely used procedure to treat painful osteoarthritis of the proximal interphalangeal joint. From 1996 to 1999, 16 patients received 19 hinged, piston-based DIGITOS prostheses in our department. In 2007, the 7-year clinical course of 14 patients (17 devices) was published in this journal. Now 12 of these patients (15 devices) have been followed with an average history of 17 years, and the preoperative data has been compared with the results after 7 and 17 years, respectively.

PATIENTS AND METHODS

The patients were 10 women and 2 men, whose average age at the time of the preoperative examination was 63 (48-69) years. Replacements were performed on the index (6), middle (6), and ring finger (3). There were 14 idiopathic osteoarthritic changes and 1 posttraumatic osteoarthritic change. Follow-up included a clinical (range of motion in the proximal interphalangeal joint, extension lag, pain) and radiological examination. In addition, the DASH score was obtained and the patients were asked whether or not they would undergo the same surgery again. The results after 7 and 17 years were reviewed for statistically significant differences.

RESULTS

While there were significant changes regarding extension lag and flexion in the first 7 years after replacement of the proximal interphalangeal joint, only minor changes were observed between 7 and 17 years after surgery. While the prosthesis was in its correct position in the first 2 years after implantation, all prostheses exhibited radiolucent lines after 4 years and periprosthetic osteophytes after 5 years. 17 years after surgery, the radiolucent lines had not increased at all and the osteophytes had increased insignificantly compared with the 7-year findings. None of the patients reported pain; all of them said that they would undergo the same surgical procedure again.

CONCLUSION

While there were significant clinical and radiological changes in the first 7 years after replacement of the proximal interphalangeal joint by a linked DIGITOS prosthesis, only minor changes were observed between 7 and 17 years after surgery.

[Simulated Total Wrist Fusion and its Influence on Hand Grip Function]

BACKGROUND

Wrist fusion is still a common treatment for patients with advanced stage arthritis. Since patients are often intimidated by the functional limitations, we intended to evaluate the influence of the lack of wrist motion in different positions on the dynamic grip function and the grip strength of the hand.

METHODS

We simulated wrist fusion in 20° extension and 20° flexion and evaluated the following grip types: fist closure, 2 different power grips, pinch grip and precision grip. A TUB sensor glove was used, which allowed us to dynamically record the range of motion (ROM) of the finger joints as well as grip strength. Nineteen healthy subjects participated and all types of grips were performed using a standardised protocol with and without simulated wrist fusion.

RESULTS

Lack of wrist motion in 20° extension had no relevant effect on the fingers' ROM, grip speed or strength. Simulated fusion in 20° flexion also had no influence on ROM or grip speed, rejecting our hypothesis that a tenodesis effect of the extensors in flexion would decrease ROM in the finger joints and grip speed. However, we were able to show a significant decrease of grip strength in flexion compared with extension or healthy wrists. The decrease averaged between 23 and 42% of healthy values, depending on the grip type. There was no change in strength distribution among the fingers.

CONCLUSION

We didn't find any impact of lack of wrist motion on finger movement during forceful hand grip at normal speed. However, a significant loss of grip strength in flexed position of the wrist joint should be considered in patients with an indication for bilateral wrist fusion.

[Midterm results following denervation of the ankle]

BACKGROUND

Complications related to arthrodesis of the ankle or total ankle replacement require a critical assessment of the indication. Using denervation of the ankle, we have the possibility to delay the above-named surgical treatment for a number of years. The aim of this follow-up study was to review the results of ankle denervation after several years.

METHODS

Within a follow-up examination, we were able to evaluate the results of 45 patients an average of 102 months following ankle denervation.

RESULTS

A total of 82.2% of patients indicated an improvement of pain for an average of 60.9 months; 71.1% of patients reported that the operation was worthwhile. The AOFAS score improved from an average 37.9 (range 26-68) preoperatively to 55.6 (range 24-84) at follow-up.

CONCLUSIONS

Ankle denervation can achieve good ankle pain reduction in the treatment of ankle arthrosis. Denervation should be considered a long-term treatment concept.

Dynamic aspects during the cylinder grip--flexion sequence of the finger joints analyzed using a sensor glove

The purpose of this study was to assess whether there is a universal pattern of movement of the finger joints while performing a cylinder grip. A sensor glove was used to record the finger joint motion of 48 participants. Our observations showed that when examining the fingers, flexion motion began either at the metacarpophalangeal (MP) or proximal interphalangeal (PIP) joints, with the distal interphalangeal (DIP) joints always last to move (p = 0.0052). The sequence of the joints at the end of the gripping motion was different than at the beginning. Here, the only statistically significant observation was that the DIP joints fully flexed only once the MP joints had flexed fully. Apart from that, it was completely variable which joint reached its final position first or last. The analysis also revealed that synchronization of four identical joints (i.e. the four PIP joints) was significantly higher than synchronization of the 12 finger joints. Although synchronization was already high at the beginning of the flexion motion, it increased significantly by the time the joints completed their movement.

[Early results after palmar multi-axial plate osteosynthesis for treatment of distal radius fractures]

In a prospective study a total of 49 fractures in 47 patients were treated with open reduction and palmar plate osteosynthesis. The results were evaluated radiologically, clinically and with the disability of arm-shoulder-hand (DASH) score. The emphasis was on early postoperative results. The patients consisted of 11 men and 36 women aged 21–85 years old. Very good or good results were achieved in 79.6% of the patients, a fair result in 16.3% and a poor result in 4.1% according to the Lidström criteria. In 65.9% of cases very good or good functional results were achieved, in 22.7% fair and in 11.4% only poor results. The DASH score showed high patient satisfaction in 70.2%, moderate satisfaction in 25.5% and only little satisfaction in 4.3% of patients. Complications occurred in 14.3% of patients and the average duration of sick leave was 45.8 days. Open reduction of distal radius fractures using palmar plates with multi-axial angular stability shows good radiological and functional results even shortly after the operation.

[The dynamics of motion sequences of the finger joints during fist closure]

The purpose of this study was to analyse motion patterns of the finger joints dynamically while making a fist. 10 subjects were examined using the TUB-sensor glove, which was equipped with 14 joint angle sensors. The median time it takes the finger joints to complete flexion until reaching the state of a closed fist ranges between 0.5 to 1.0 s. A specific pattern can be seen for every finger. The PIP and DIP joints appear to be linked, with the DIP trailing the PIP joint. At the thumb the IP is trailing the MCP joint. The MCP joint shows more variation at the beginning of flexion: while in some cases it initiates movement in a finger, in other cases its flexion falls behind the PIP joint movements. The completion of flexion is achieved by the MCP joints, with the PIP and DIP joints reaching their end of motion first. The range of motion (ROM) at the MCP joints shows a finger-dependent median of 79-97°. At the PIP joints the median lies between 87° and 90°, at the DIP joints between 52° and 68°. At the thumb it is 21° for the MCP and 24° for the IP joint. The linkage between PIP and DIP joints can also be seen when analysing the ROM. The coupling ratio amounts to 0.77 at the index finger, 0.75 at the middle and ring finger and 0.57 at the small finger.

DIGITOS-Fingermittelgelenkprothese - Langzeitergebnisse

Most important methods for the surgical treatment of painful arthritis of the proximal interphalangeal joint are the joint fusion or the implantation of a prosthesis. There are a lot of different models for joint replacement. Sixteen patients received 19 middle joint replacements performed with the DIGITOS-prosthesis between 1996 and 1999. Over a period of seven years, 14 patients with 17 prostheses have been observed prospectively. In the 7-year follow-up, a minimal radiolucent line at the bone-cement junction and huge periarticular osteophytes could be found in every case. No cortical penetration, luxation, or implant fractures were recorded. The preoperative median range of motion was 50 degrees. Postoperatively, there was an improvement to 60 degrees. The range of motion decreased to 50 degrees after one year and to as little as 30 degrees after seven years. Preoperatively, eleven patients had pain with activity and three had pain without activity. During the whole follow-up period there were only two patients who had pain at work. All patients were satisfied with the results of the operation throughout the control period and would choose the same treatment again.

Einschätzung der Verletzungsschwere sowie der Dauer der Arbeitsunfähigkeit bei Handverletzungen mit dem HISS-Bewertungsschema

BACKGROUND

The estimation of the time off work depending on the injury pattern and severity is of major interest in the treatment of hand injuries. The predictive value of the HISS score (Hand Injury Severity Scoring System) was evaluated.

MATERIAL AND METHODS

According to this score, 184 work-related injuries (1999 to 2002) were analyzed prospectively, excluding injuries of both hands. The median age was 37.9 years (18 to 65 years), 11 % of the patients were female.

RESULTS

A significant correlation was established between the HISS score and the time off work (p < 0.0001, r = 0.51). The score also correlated with the degree of work incapacity (p < 0.0001).

CONCLUSION

Our data confirm the predictive value of the HISS score for the early estimation of the time off work resulting from hand injuries. However, the estimation is limited to injuries distal to the wrist.

[Treatment of flexor tendon injuries in children]

In contrast to the standard therapy of flexor tendon injuries in adults, the postoperative treatment program for children remains a controversial topic. Some prefer immobilization therapy in a variety of forms and for different periods of time. Others prefer early mobilization programs. We present results for twenty-eight children with thirty-seven flexor tendon injuries. The average age was 5.8 years. After primary tendon suture in children six years and younger (group A), our postoperative program consisted of immobilization for three weeks. The older children (group B) were treated with an early passive mobilization program. Follow-up examinations were carried out on twenty six of the children at three months and at 3.7 years. Three months after surgery, the children in group A showed only average results while those in group B presented good finger motion. After 3.7 years both groups showed good results.

[Reconstruction of bone defect by vascularized fibular transfer after failed wrist arthroplasty]

A bone defect of 14 cm resulted after wrist implant removal because of loosening in a 46-year-old patient. Performing wrist arthrodesis the defect was reconstructed by a vascularized fibular transfer. Solid bone fusion was complete in six weeks. Free function of the digits was seen because of length reconstruction.

Correlation of bone mineral density with strength and microstructural parameters of cortical bone in vitro

The aim of this study was to evaluate the influence of microstructural parameters, such as porosity and osteon dimensions, on strength. Therefore, the predictive value of bone mineral density (BMD) measured by quantitative computed tomography (QCT) for intracortical porosity and other microstructural parameters, as well as for strength of cortical bone biopsies, was investigated. Femoral cortical bone specimens from the middiaphysis of 23 patients were harvested during total hip replacement while drilling a hole (dia. 4.5 mm) for the relief of the intramedullary pressure. In vitro structural parameters assessed in histological sections as well as BMD determined by quantitative computed tomography were correlated with yield stress, and elastic modulus assessed by a compression test of the same specimens. Significant correlations were found between BMD and all mechanical parameters (elastic modulus: r = 0.69, p < 0.005; yield stress: r = 0.64, p < 0.005). Significant correlations between most structural parameters assessed by histology and yield stress were discovered. Structural parameters related to pore dimensions revealed higher correlation coefficients with yield stress (r = -0.69 for average pore diameter and r = -0.62 for fraction of porous structures, p < 0.005) than parameters related to osteons (r = 0.60 for osteon density and average osteonal area, p < 0.005), whereas elastic modulus was predicted equally well by both types of parameters. Significant correlations were found between BMD and parameters related to porous structures (r = 0.85 for porosity, 0.80 for average pore area, and r = 0.79 for average pore diameter in polynomial regression, p < 0.005). Histologically assessed porosity correlated significantly with parameters describing porous structures and haversian canal dimensions. Our results indicate a relevance of osteon density and fraction of osteonal structures for the mechanical parameters of cortical bone. We consider the measurement of BMD by quantitative computed tomography to be helpful for the estimation of bone strength as well as for the prediction of intracortical porosity and parameters related to porous structures of cortical bone.

[Infected animal bite injuries of the extremities]

The appearance of animal bite injuries varies in regard to location and extent. Injuries with puncture wounds involving the extremities carry great risk of infection. Managing the complications often requires substantial medical treatment and increased costs. The aim of this study is the evaluation of the course of disease, medical care, and treatment costs in patients with infected bite injuries. In the year 2000, 16 patients were treated for infection after bite injuries of the extremities. Fourteen patients received substandard therapy because of incorrect assessment of the extent of the bite wound. Because of infection, the average time needed for treatment before returning to work was 3 months, including 12 days of hospitalization and 16 days of out-patient treatment. The average treatment costs exceeded 6,100 Euro for the health insurance companies. Because of its increasing prevalence and inadequate treatment, this type of injury has become a serious public health problem.

The total synthesis of C-glycosides with completely resolved seven-carbon backbone polyol stereochemistry: stereochemical correlations and access to L-configured and other rare carbohydrates

The de novo synthesis of a full set of hydroxymethyl C-glycosides from only two precursors is described. The seven-carbon target molecules contain five stereocentres and bridge the stereochemical gap between natural D-configured and non-natural L-configured series of hexoses. Key steps include hydroxylation, differential protection, stereoselective reduction and desymmetrization of 8-oxabicyclo[3.2.1]oct-6-enes. C-Terminus differentiation and C-terminus excision of the seven-carbon polyol backbone lead to hexoses, including those of the L-series. A stereochemical and genetic classification of C-glycosides is presented.

[Dorsal V-ligament reconstruction in scapholunate instability]

In dynamic and static scapholunate instability after trauma, the repair of the scapholunate ligament is important to avoid scapholunate advanced collapse of the wrist. Direct suture even of fresh-torn ligaments can be technically demanding and occasionally unreliable, thus reconstruction may require additional tissue beside the ligament. Eighteen patients suffering from dynamic (n = 10) and static (n = 8) scapholunate instability were treated by a dorsal ligament reconstruction six months after trauma. A clinical wrist score according to Cooney showed an average of 86 points (maximum 100) within a follow-up of nineteen months after surgery. X-ray films documented no significant loss of scapholunate reduction. Using local tissue only, this method is always possible, very reliable and easy to perform.

[Results of basal joint arthrosis treatment--comparison of Epping ligament reconstruction with trapeziectomy alone]

Objective of this study is to compare clinical and radiological results of two different methods of treatment for trapeziometacarpal osteoarthrosis of the thumb. Eighteen patients received operative treatment. An operation according to Epping was performed in eleven cases (collective I), while nine cases were treated with a trapeziectomy only (collective II). The mean follow-up of the first collective was 40 months and 15 months for the second one. The results of the two patient groups were subjected to statistical comparison in a retrospective study. This revealed no significant differences with regard to active range of motion, power, and subjective symptoms, classified according to the Buck-Gramcko score. With a mean of 49 points for the first and 50 points for the second collective, both achieved very good results. However, the mean operating time was significantly shorter in the patients treated with a trapeziectomy only, while the mean distance between the base of the first metacarpal bone and the scaphoid bone was significantly greater in this group. This is surely due to the shorter follow-up of the patients who underwent trapeziectomy only, since further proximalisation has to be expected. We were able to demonstrate that both methods yield equally good results, and hence the simpler technique of trapeziectomy alone should be given preference, at least in the standard situation of a patient, whose intermetacarpal ligaments offer sufficient stability after trapeziectomy.

Functional treatment of physeal and periphyseal injuries of the metacarpal and proximal phalangeal bones

BACKGROUND/PURPOSE

Hand fractures are common injuries in infants. Complications are rare because of potent remodeling dimension and rapid healing of growing bone. There is limited remodeling capacity for angular and rotational deformity so displaced fractures often require open reduction and internal fixation.

METHODS

The authors present a splint system for a protected reduction and mobilization program of displaced proximal phalanx and metacarpal fractures. The custom-molded 2-component thermoplastic splint allows motion of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints. It has been developed to allow bone healing and recovery of motion at the same time. In this study, the authors evaluated the clinical and radiologic results of a series of 11 consecutive infants with displaced metacarpal fractures and 13 displaced proximal phalanx fractures who received functional treatment.

RESULTS

Fracture consolidation and full active motion was achieved simultaneously in 4 weeks in 21 children; 2 infants required physiotherapy, and 1 child was lost to follow-up. No further growth abnormality was seen within a 12-month observation period.

CONCLUSION

When there is no damage of soft tissue the functional mobilization program can lead to good results treating displaced physeal and periphyseal hand injuries of proximal phalanx and metacarpal fractures. J Pediatr Surg 36:611-615.

Prediction of strength of cortical bone in vitro by microcomputed tomography

OBJECTIVE

The aim of this study was to evaluate the predictive value of bone mineral density and intracortical porosity measured by microcomputed tomography for the strength of cortical bone biopsies.

DESIGN

Experimental study comparing the predictive value of bone mineral density and of intracortical porosity determined in vitro by microcomputed tomography for the mechanical properties of cortical bone cylinders.

BACKGROUND

The assessment of cortical bone strength might be relevant for the prediction of fracture risk or the choice of suitable therapy strategies in orthopaedic surgery. The predictive value of cortical density for the mechanical properties is discussed controversially. The relevance of intracortical porosity measured by histomorphometry has been established, but the predictive value of porosity determined by microcomputed tomography remains to be explored.

METHODS

Femoral cortical bone specimens from the mid diaphysis of 24 patients were harvested during total hip replacement procedure at the location, where a diaphyseal hole (diameter 4.5 mm) was drilled in order to reduce the intramedullary pressure. In vitro intracortical porosity and bone mineral density measurements by microcomputed tomography were compared with strength and elastic modulus assessed by a compression test transverse to the Haversian systems of the same specimens.

RESULTS

Significant negative correlations were found between porosity measured by microcomputed tomography scans and yield stress, stiffness and elastic modulus (P<0.001), however, the positive correlations between bone mineral density and mechanical parameters were stronger (P<0.0001). The mechanical parameter best predicted by mineral density as well as by porosity was yield stress (r=0.72,P<0.0001;r=-0.64,P<0.001).

CONCLUSIONS

Bone mineral density determined by microcomputed tomography imaging in vitro may be a potent method to predict mechanical properties of cortical bone non-destructively. The application in vivo remains to be explored.

[Problems of malunited fractures of the distal radius]

The essential problematic of the distal fracture of the radius lies in the quality of its reduction and retention. 35 patients with distal fractures of the radius and strain fractures of the styloid process of the ulna were followed up with regard to their functional and radiological results and their subjective symptoms. Patients with intra-articular fractures were found to have significantly poorer functional results compared to those with extra-articular fractures. 29 out of 35 patients developed a nonunion of the styloid process of the ulna in the form of a compensatory false position with a significant dorsal tilt of the articular surface of the radius. Their functional results were also significantly poorer than those of the other 6 patients. The patients whose radii were shortened by more than 2 mm also had significantly poorer functional results and a median dorsal tilt of 5 degrees of the articular surface. Where the dorsal inclination of the articular surface of the radius exceeded 5 degrees, a significant increase in the scapholunar angle, which averaged 62 degrees, was found. On the basis of these figures, we conclude that in the reduction of the distal fracture of the radius, shortening by not more than 2 mm and a dorsal inclination of the articular surface of the radius, taken laterally, of not more than 5 degrees should be tolerated in order to minimise functional impairments of the wrist.

Predictive value of Singh index and bone mineral density measured by quantitative computed tomography in determining the local cancellous bone quality of the proximal femur

OBJECTIVE

The purpose of this study was to assess the predictive value of the Singh index as well as quantitative computed tomography for the in vitro local mechanical competence of the cancellous bone of the proximal femur.

DESIGN

An experimental study examining the relation between mechanical properties and bone mineral density of the femoral neck determined in vitro and the clinical estimated Singh index on X-rays.

BACKGROUND

Evaluation of the predictive value of the Singh index, an inexpensive and simple technique for the mechanical properties of the cancellous bone of the proximal femur.

METHODS

The bone quality of the proximal femur of 34 patients undergoing total hip replacement was estimated by roentgenography using the Singh index. Bone mineral density was quantified by quantitative computed tomography using cylindrical cancellous bone biopsies harvested during the total hip replacement procedure by a new biopsy method. The mechanical properties of the bone specimens (Young's modulus, strength and maximum energy absorption E(max)) were measured by mechanical testing of the bone biopsies.

RESULTS

A strong correlation of the Singh index versus material properties of cancellous bone was noted (r=0.66 for Young's modulus, r=0.73 for strength and r=0.69 for E(max), P<0.0001). The correlations of bone mineral density measured by quantitative computed tomography versus Young's modulus, strength and energy absorption E(max) were significant. Strength was predicted best (r=0.82; P<0.0001), followed by E(max) (r=0.79; P<0.0001) and Young's Modulus (r=0.73; P<0.0001).

CONCLUSIONS

We conclude, that assessment of bone mineral density by quantitative computed tomography is a reliable and precise method for the estimation of cancellous bone material properties. The Singh index provides a rough estimate for the mechanical competence of the proximal femur. It is inexpensive, simply to assess and can in some cases replace the measurement of bone mineral density, notably in cases of marked decrease in bone density.

[Measuring grip strength of the hand with a sensor glove by gripping with submaximal and maximal strength]

Grip strength measurements with the aid of dynamometers are dependent on the cooperation and motivation of the individual examined. Recognising a simulated loss of grip is a hitherto unresolved problem. With a sensor glove developed at the Berlin University of Technology, the force distribution pattern of any form of grip can be captured via ten pressure sensors and evaluated by computer. In five subjects, the force distribution patterns at submaximum and maximum force of five different grips were determined in three successive measurements each. The data were recorded in force-time diagrams. For each act of grasping, the measurements produced a curve with near-constant measuring signals within a defined period (plateau). The difference in the plateau heights of successive grips and the structures of the individual plateaux (oscillation, standard deviation) were used as distinguishing criteria. The dynamics of the measuring signals showed statistically significant differences between grips with submaximum and maximum force (p < 0.0001).

Prediction of cortical bone porosityIn Vitro by microcomputed tomography

The high importance of intracortical porosity for mechanical strength of cortical bone has been established. The contribution of other parameters of microstructure such as osteon dimensions for strength is in discussion. The aim of this study was to evaluate the predictive value of microcomputed tomography (µCT) for porosity and other microstructural parameters of cortical bone in cortical bone biopsies. Femoral cortical bone specimens from the middiaphysis of 24 patients were harvested during the procedure of total hip replacement at the location where normally one hole (Ø 4.5 mm) for the relief of the intramedullary pressure is placed.In vitro intracortical porosity and bone mineral density (BMD) measurements by µCT were compared with structural parameters assessed in histological sections of the same specimens. A strong correlation was found between intracortical porosity measured by µCT and histological porosity (r=0.95,P<0.0001). Porosity measured by µCT was also a strong predictor for other parameters describing dimensions of porous structures. BMD^-1 was associated with osteonal area (r=-0.76,P<0.0001). We consider the measurement of porosity by µCT as a very potent procedure for assessing intracortical porosity and parameters related to porous structures of cortical bone nondestructivelyin vitro.

Predictive value of bone mineral density and morphology determined by peripheral quantitative computed tomography for cancellous bone strength of the proximal femur

Peripheral quantitative computed tomography (pQCT) is an established diagnostic method for assessment of bone mineral density in the diagnosis of osteoporosis. However, the capacity of structural parameters of cancellous bone measured by high-resolution computed tomography remains to be explored. In 33 patients, bone mineral density (BMD) of the proximal femur was measured in vitro by pQCT using cylindrical biopsies from the intertrochanteric region harvested before the implantation of an artificial hip joint. By digital image analysis of CT scans, parameters derived from histomorphometry describing the microarchitecture of cancellous bone were measured. The biopsies were also loaded to failure by an uniaxial compression test to determine the biomechanical parameters, Young's modulus, strength, and maximum energy absorption (E(max)). Strong correlations were found for BMD vs. mechanical parameters (r = 0.73 for Young's modulus, r = 0.82 for strength, and r = 0.79 for E(max); p < 0.001, n = 29). The morphological parameters, bone volume per trabecular volume (BV/TV), apparent trabecular thickness (app.Tb.Th), apparent trabecular separation (app.Tb.Sp), and trabecular number (Tb.N), correlated significantly with all mechanical parameters. The combination of morphological parameters with BMD in a multivariate regression model led to an overall, but only moderate, increase in R(2) in all cases. Our data confirm the high predictive value of BMD for the mechanical competence of cancellous bone of the intertrochanteric region. However, quantification of cancellous bone structure by image analysis of CT scans may provide additional qualitative information for the analysis of bone strength.

[Reproducibility of measuring the finger joint angle with a sensory glove]

Joint angles are measured using goniometers according to the neutral-zero method. These measurements are dependent on the examiner and are thus subject to great variation. With a newly developed sensor glove, the grip patterns of the hand can be captured with a computer-assisted technique. In a comparative study involving five subjects, the joint angles during power grip around a cylindrical body and while clenching a fist were determined by nine examiners at three different times, using the conventional technique according to the neutral-zero method. In the same experimental design, the joint angles were measured with the sensor glove. As a criterion for the reproducibility of the measurements, the intraclass correlation coefficient (ICC) was calculated by means of an analysis of variance. The ICC is a value which approximates 1 if the reliability of the measurements is high. At 0.94, the ICC of the data determined with the sensor glove was markedly higher than the mean ICC for all examiners of 0.50 using the conventional method. Besides the measurement of the finger joint angles, the sensor glove allows the dynamic recording of joint movements of all finger joints during different grip patterns of the hand.

Prediction of cortical bone porosity in vitro by microcomputed tomography

The high importance of intracortical porosity for mechanical strength of cortical bone has been established. The contribution of other parameters of microstructure such as osteon dimensions for strength is in discussion. The aim of this study was to evaluate the predictive value of microcomputed tomography (mCT) for porosity and other microstructural parameters of cortical bone in cortical bone biopsies. Femoral cortical bone specimens from the middiaphysis of 24 patients were harvested during the procedure of total hip replacement at the location where normally one hole (Ø 4.5 mm) for the relief of the intramedullary pressure is placed. In vitro intracortical porosity and bone mineral density (BMD) measurements by mCT were compared with structural parameters assessed in histological sections of the same specimens. A strong correlation was found between intracortical porosity measured by mCT and histological porosity (r = 0.95, P <0.0001). Porosity measured by mCT was also a strong predictor for other parameters describing dimensions of porous structures. BMD?1 was associated with osteonal area (r = -0.76, P <0.0001). We consider the measurement of porosity by mCT as a very potent procedure for assessing intracortical porosity and parameters related to porous structures of cortical bone nondestructively in vitro.

The effectiveness of ADCON-T/N, a new anti-adhesion barrier gel, in fresh divisions of the flexor tendons in Zone II

In a prospective randomized clinical trial, ADCON-T/N was investigated with regard to its effectiveness in fresh traumatic injuries of the flexor tendons in Zone II of the hand. Thirty patients participated in the trial. Following a standardized technique of tendon repair, the total active motion (TAM) and total extension lag (TEL) were determined after 12 weeks and evaluated according to the Buck-Gramcko score. Excellent results were achieved in 15 out of 16 patients in the ADCON-T/N group and 12 out of 14 in the control group. However, no statistically significant difference was found between the mean TAM and TEL in the two groups.

[Soft tissue reconstruction after scalping injury caused by a dog bite]

The reconstruction of soft-tissue damage on the part of the head which is covered with hair is aimed not only at repairing the damage in such a way that it will withstand mechanical strain but also at the restoring the hair on the scalp. In a 5-year-old boy with a scalping injury involving second- and third-degree soft-tissue damage over an area of 20 x 12 cm after a dog bite, surgery was initially performed to transform the damage into purely second-degree damage, which was then repaired with a split skin graft. One year later, the scalp containing the hair was stretched with the aid of two skin expanders over a period of 3 months, so that the split skin graft area could be removed and the hair on the scalp restored.

[Conservative management of articular metacarpophalangeal joint fractures]

We present a splint system for a protected mobilization program after closed reduction of articular proximal phalangeal base fractures. This therapy consists of the periarticular soft tissue and functional anatomy. The soft-tissue around the base of the proximal phalanx leads to a circular stabilization effect. This so called Zancolli Complex (Metacarpophalangeal Retention Apparatus) can be used with the effect of a brace treatment. Treating 31 patients with articular fractures of the proximal phalanx way we found good functional results within a mean follow up period of 2 years after the accident.

[DIGITOS-prosthesis for the proximal interphalangeal joint. A 2-year follow-up]

The treatment of osteoarthrosis of the proximal interphalangeal joint by prosthesis bears several specific problems. With the DIGITOS-prosthesis a new implant is now available. It is a cemented modular hinged prosthesis. We report our experiences with this implant from a prospective clinical trial. Seven patients with osteoarthrosis of the proximal interphalangeal joint had ten prosthetic middle joint replacements performed with DIGITOS-prostheses. Over an observation period of two years, the functional results were found to be good. The mean preoperative range of motion in the affected joints was 51.5 degrees. Three months after surgery, this had improved to 60.5 degrees, but then decreased to 53.0 degrees after one year and to 49.5 degrees, i.e. the original range of motion, by the end of the second postoperative year. No implant became loose. Nearly all patients were free from pain. The only serious complication was an iatrogenic lesion of the middle slip of the extensor aponeurosis resulting in a buttonhole deformity. In spite of these encouraging two-year results, the further follow-up has to be observed carefully.

Dynamic treatment of displaced proximal phalangeal fractures

We report a splint system for a protected mobilization program (termed dynamic treatment) of proximal phalangeal fractures. This program can be used for nonoperative treatment or after operative treatment. Intra-articular fractures of the proximal phalanx at the metacarpophalangeal joint were included. The custom-molded 2-component thermoplastic splint allows motion of the proximal and distal interphalangeal joints. It was developed to allow bone healing and recovery of motion at the same time. We evaluated the clinical and radiologic results of a consecutive series of 48 displaced proximal phalangeal fractures in 45 patients who received dynamic treatment. Fracture consolidation was achieved in all patients and bone healing and recovery of full active motion was achieved simultaneously in all but 4 patients by 6 weeks. The advantage of this splint system is the variability of its application. The splint can be used both for nonsurgical and surgical management. It can be removed to change dressings and for radiologic evaluations. The period of dynamic treatment can be determined individually in each case.

Dynamic changes in serum erythropoietin levels in solid tumour patients undergoing 41.8 degrees C whole body hyperthermia and/or chemotherapy

Whole Body Hyperthermia (WBH) has been shown to have physiological effects on myeloid and megakaryocytic haematopoietic tissue via both cytokine induction, as well as hormonal changes. In order to extend this knowledge base to the erythroid cells, endogenous erythropoietin (EPO) levels were studied in 17 cancer patients receiving 41.8 degrees C WBH and/or chemotherapy, as well as in 53 anaemic and non-anaemic control patients. Pre-treatment EPO levels showed a 'blunted' EPO response in cancer patients compared to the control patients. Post-treatment data demonstrated a significant chemotherapy induced increase in EPO levels with a peak at 36 to 48 hours (independent of changes in haemoglobin) and 10 to 13 days post chemotherapy (simultaneously with a drop in haemoglobin levels). The early change in EPO levels was not influenced by the addition of 41.8 degrees C (x 60 min) WBH to the same chemotherapy regimen, i.e., ifosfamide, carboplatin, and etoposide. Taken collectively, our data show that endogenous EPO levels in cancer patients can be effected by chemotherapy (independent of changes in haemoglobin). This EPO response to chemotherapy is not impacted on by 41.8 degrees C WBH. A relevant secondary conclusion can also be derived from this investigation, i.e., caution should be exercised as to the use of EPO levels during chemotherapy as predictors of exogenous EPO efficacy.

Influence of circadian rhythm on 41.8 degrees C whole body hyperthermia induction of haematopoietic growth factors

It has previously been reported by the authors that the induction of a series of cytokines by 41.8 degrees C Whole Body Hyperthermia (WBH), i.e., interleukin (IL)-1 beta, IL-6, IL-8, IL-10, tumour necrosis factor alpha, and granulocyte colony stimulating factor (G-CSF). As cytokine levels are known to fluctuate as a function of time, i.e. circadian rhythm, the influence of circadian time structure on specific haemotopoetic growth factors is studied, i.e. granulocyte macrophage colony stimulating factor (GM-CSF), G-CSF and IL-3. Samples derived from four cancer patients undergoing extracorporeal WBH resulted in the following observations: G-CSF is induced by WBH, but unaffected by circadian rhythm, IL-3 fluctuates with circadian rhythm, but is unaffected by WBH. Specifically, a biphasic temporal pattern of IL-3 (i.e. with a peak at 2:00 and 5:00 a.m. and a nadir concentration at 5:00 p.m.) was found by analysis of variance. GM-CSF was below the lower detection limit pre and post WBH. The data show the importance of measuring cytokines as a function of time to circumvent conflicting results in the inter-relationship of 'true' cytokine induction and circadian rhythm. The implications of the differential induction of G-CSF, GM-CSF, and IL-3 for myeloprotection after WBH are discussed.

Systemic hyperthermia and ICE chemotherapy for sarcoma patients: rationale and clinical status

Preclinical studies are consistent with the concept that 41.8 degrees C whole body hyperthermia (WBH) can enhance the therapeutic index of specific chemotherapeutic agents. These laboratory investigations resulted in 2 phase I clinical studies, which also support this hypothesis. These trials were extended to 2 sequential phase II investigations of WBH plus ifosfamide, carboplatin and etoposide (ICE) for refractory sarcoma patients. The first study (involving 12 patients) using extra-corporeal WBH was prematurely closed to adopt a less toxic WBH technology, i.e., the radiant heat Aquatherm. To date, 12 patients have been accrued to the Aquatherm trial. Projections regarding reduced morbidity were correct. The response rate for ICE/WBH is currently 63%. The review to follow will summarize the results of these trials, as well as the laboratory and clinical data which serve to explicate the dramatic clinical results observed to date.

Optimization of chemotherapy administration for clinical 41.8 degrees C whole body hyperthermia

Preclinical data is consistent with the concept that the timing of chemotherapy during radiant heat-whole body hyperthermia (WBH) should affect therapeutic index. In order to test this hypothesis, a controlled clinical investigation was initiated. Patients received carboplatin (CBDCA) on an early or late schedule with respect to achieving target temperature (i.e. 41.8 degrees C) in alternating treatment cycles. The first cycle was randomized between patients regarding the early or late schedule for two planned sets per patient (i.e. four cycles). Ifosfamide, etoposide and granulocyte colony stimulating factor were delivered during all cycles with a standardized schedule. A total of 53 cycles involving 17 patients were analyzed. Detailed toxicity evaluation (i.e. delay in therapy secondary to thrombocytopenia, need for platelet transfusions, and days of hospitalization) taken collectively demonstrated a statistically and clinically significant advantage to delivering CBDCA 10 min after target temperature, during the plateau phase of WBH.

[Acetabular fractures in the elderly - primary endoprosthesis]

In the Department of Traumatology at the University of Ulm, 26 elderly patients with displaced acetabular fractures were treated with primary implantation of a hip joint endoprosthesis between 1986 and 1996. The principles of operative therapy are stabilization of the acetabular ring, grafting of acetabular defects with autogenous corticocancellous bone and cranial buttressing with a reinforcing ring. This concept permits immediate mobilization of elderly patients and full weight-bearing and thus results in favorable early postoperative results. Secondary complications typically caused by immobilization can therefore be avoided.

[Acetabular fractures in elderly persons. Primary endoprosthetic treatment]

In the Department of Traumatology at the University of Ulm, 26 elderly patients with displaced acetabular fractures were treated with primary implantation of a hip joint endoprosthesis between 1986 and 1996. The principles of operative therapy are stabilization of the acetabular ring, grafting of acetabular defects with autogenous corticocancellous bone and cranial buttressing with a reinforcing ring. This concept permits immediate mobilization of elderly patients and full weight-bearing and thus results in favorable early postoperative results. Secondary complications typically caused by immobilization can therefore be avoided.