Charge sensing and controllable tunnel coupling in a Si/SiGe double quantum dot.

We report integrated charge sensing measurements on a Si/SiGe double quantum dot. The quantum dot is shown to be tunable from a single, large dot to a well-isolated double dot. Charge sensing measurements enable the extraction of the tunnel coupling t between the quantum dots as a function of the voltage on the top gates defining the device. Control of the voltage on a single such gate tunes the barrier separating the two dots. The measured tunnel coupling is an exponential function of the gate voltage. The ability to control t is an important step toward controlling spin qubits in silicon quantum dots.

Long-term results after ankle arthrodesis: clinical, radiological, gait analytical aspects.

In a retrospective study the results of operatively treated ankle joints were critically discussed. In a period from January 1, 1977 to December 31, 1994, a total of 35 arthrodeses were carried out. Seventeen patients were followed up clinically, radiologically and with a gait analysis. Not only the radiological surgical result was of interest, but also the heel-toe movement of the stiffened foot in the individually adapted orthopedic footwear compared to standard footwear. A significantly improved heel-toe movement was found in orthopedic shoes, although there is a reduction of movement in the hindfoot in the sagittal plane.

Injuries in mountain biking.

Despite still growing attraction mountain biking as a matter of sports traumatology still lacks relevant data based on large cross-sectional surveys. To obtain an overview of risk factors, types, and main body sites of injuries occurring in mountain biking we assessed the results of a questionnaire answered by 3873 athletes. A total of 8133 single lesions were reported by 3474 athletes, 36% of whom regularly participated in competitions. The incidence of injuries in mountain biking is comparable to that in other outdoor sports, the majority of injuries being minor. Mountain biking athletes were found to have an overall injury risk rate of 0.6% per year and 1 injury per 1000 h of biking. The main risk factors included slippery road surface, cyclist's poor judgement of the situation, and excessive speed, representing personal factors that could be altered by preventive measures. Of all injuries 14% were due to collision with some part of the bike, especially the pedals and the handlebar. While 75% of the injuries were minor, such as skin wounds and simple contusions, 10% were so severe that hospitalization was required. A breakdown of the injuries according to body site and frequency of occurrence is presented.

[Outcome of surgically treated lateral clavicle fractures]. / Ergebnisse operativ behandelter lateraler Klavikulafrakturen.

This retrospective study presents the results of 41 patients with a lateral clavicle fracture eight years after the treatment at the Staatliche Orthopädische Klinik of the LMU München in the time between 31.10.1979 and 31.10.1994. It could be shown that the lateral clavicle fractures, due to their variety, hold a special position among the clavicle fractures and thus need a differentiated therapeutic procedure. Among the operation methods the K-wire stabilisation with cerclage was the most often chosen operation technique i.e. in 24 cases. The K-wire without cerclage was used in two cases. Twelve fractures were treated with AO-plate-osteosynthesis. Three fractures had to be treated by resection, as they produced two pseudarthrosis and one serious AC-arthrosis during the conservative therapy. 92.7% of the subjective results of the 41 checked up patients were good and very good. The clinical follow-up of 36 and the radiological follow-up of 33 patients revealed in 97% a good and very good outcome in the Boenisch-Score.

[Pattern and risk of injuries of profile athletes in snow boarding]. / Verletzungsmuster und -risiken von Profisportlern im Snowboardsport.

During winter 1994/95 and 1995/96 a retrospective study was carried out in which datasets supported by questionnaires from 31 female and 64 male professional snowboarders were evaluated. Included were personal data and details of other types of sports. Also the personal style preferred and equipment used was integrated. Particularly of interest were the localization and causes of injury-patterns with the degrees of severity and overexertion disorders. Among the professionals the most frequent injuries occurred in the metacarpals and fingers (37.3%), the shoulder (36.0%), knee joints (33.3%) and the ankles (28%). The predominating pattern of severe joint injuries were capsular/ligament lesions and fractures. Overexertion syndromes in the knee were predominant, followed by thigh and ankle-joint strains. In the alpine group the incidence of injuries and strains, the knee was the most frequent. 75 professionals suffered 195 traumas. In relation to 1000 snowboarding hours, the risk of injury among the professionals is 0.8. Self induced injuries were mostly cause of misjudgement in specific situations (40.1%).

[Clinical and radiological results after arthroscopic partial medial meniscectomy. Are there risk factors?]. / Klinische und radiologische Ergebnisse nach arthroskopischer partieller Innenmeniskusresektion. Gibt es prädisponierende Faktoren?

In a retrospective study 100 patients underwent a clinical and radiological follow-up 7 years and 7 months after an arthroscopic partial medial meniscectomy. None of these patients had associated intraarticular lesions apart a minor chondral damage of the medial compartment. The follow-up showed excellent clinical results in 96% of patients according to the modified Marshall Score. The radiological results demonstrated a deterioration or development of osteoarthritis of the operated knee joint in 33% of patients, with a statistical significance between radiological and clinical results (p < 0.05). The age of the patients at time of operation and any angular deformity of the knee joint had no statistical significant influence on the radiological results. Women had a statistically significant higher risk to deteriorate or develop gonarthrosis after partial medial meniscectomy than men (p < 0.05). The arthroscopic partial medial meniscectomy leads to excellent subjective and functional results, but it could not totally prevent the increase or development of degenerative changes in the medial knee compartment.

Late results after arthroscopic partial medial meniscectomy.

In a retrospective study, 100 patients underwent a clinical and radiological follow-up examination after a minimum of 7 years (range 7.0-9.3 years) following an arthroscopic partial medial meniscectomy. None of these patients had associated intra-articular lesions, apart from minor chondral damage (max. grade 2 Outerbridge classification; < 1 cm2) of the medial compartment at the time of the primary arthroscopy. According to the modified Marshall score, the follow-up evaluation showed excellent clinical results in 96%. Nevertheless, the radiological outcome, as measured by comparing preoperative and postoperative X-rays, demonstrated a development or progression of the osteoarthritis of the affected knee joint in 33%, with a statistically significant correlation between the radiological and clinical outcomes (P < 0.05). The age of the patients at the time of operation and any angular deformity of the knee joint did not influence the radiological results. Women had a statistically significantly higher risk of developing gonarthrosis after partial medial meniscectomy than men (P < 0.05). The arthroscopic partial medial meniscectomy led to excellent subjective and functional results but could not prevent the increase or development of late degenerative changes in the medial knee compartment.

[Injury and exertion patterns in football on artificial turf]. / Das Verletzungsspektrum und die Uberlastungsschäden beim Fussballsport auf Kunstrasen.

This controlled non-selected cross-sectional study supplies a basic survey on the topic analysing 1783 injuries in 433 of 736 athletes out of a closed collective. Aged 11 to 40 years and having played an average of 3.7 years an artificial turf the players had sustained 38% skin injuries (58% in the legs), 28% sprains (64% in the ankle joints, 21% in the knee joints) and 17% muscle injuries. 76% of all injuries were minor, i.e. leading to an interruption of under one week, only 8% were severe with a break of over 3 weeks. The average risk of injury was 6 per 1000 hours of participation, similar to that in football on natural grass. More than half of the players protocol pain in the joints, muscles or column persisting even one day after the game, which only led to medical assistance in 3% of all cases. Playing football on artificial grass displays a specific pattern of injuries and exertion syndromes without a higher rate or grade of injuries and therefore shows no medical need for restriction.

[Mid-term outcome after surgically managed re-rupture of the anterior cruciate ligament]. / Mittelfristige Ergebnisse nach operativ versorgter Reruptur des vorderen Kreuzbands.

This retrospective study shows the results in 30 patients of revision surgery on their reruptured ACL. The follow-up time was 30 months on average (range 10-54 months). The follow-up examination included subjective (Lysholm score, Tegner activity level rating score), clinical and radiological criteria and also instrumental laxity testing with the KT-1000 arthrometer. The overall evaluation was done according to the IKDC score. The follow up showed subjective and objective results almost equal to those after primary surgery on ACL. The IKDC score revealed certain abnormal and highly abnormal results, which demonstrated that revision ACL surgery gives poorer results than primary surgery. Nevertheless, we recommend reconstruction of a torn ACL even in a revision case to restore the knee function and prevent further menisceal and chondral damage and degeneration.

Muscular imbalance and shoulder pain in volleyball attackers.

OBJECTIVE: In overhead sports such as volleyball, baseball, or tennis shoulder problems are very common. The aim of this study was to identify features which may correlate with shoulder problems in volleyball attackers. METHODS: 30 competitive volleyball attackers (mean age 25 years) were included in the study; 15 were suffering from shoulder pain and 15 had no history of shoulder pain. The results were compared with those of a control group of 15 recreational athletes without any overhead sports activities. RESULTS: Volleyball attackers have a different muscular and capsular pattern at the playing shoulder compared to the opposite shoulder. Their playing shoulder is depressed, the scapula lateralised, and the dorsal muscles and the posterior and inferior part of the shoulder capsule shortened. These differences were of more significance in volleyball attackers with shoulder pain than in volleyball players without shoulder pain. In contrast to recreational athletes without any overhead sports activity, there were no significant difference in the comparison of the two shoulders. The histories, clinical and sonographic findings did not reveal further typical features for volleyball attackers with shoulder pain. CONCLUSIONS: Muscular balance of the shoulder girdle is very important in this sport. It is therefore imperative to include adequate stretching and muscular training programme for the prevention, as well as for therapy, of shoulder pain in volleyball attackers.

[Intermediate-term treatment outcome after fractures of the proximal radius]. / Mittelfristige Behandlungsergebnisse nach Frakturen des proximalen Radius.

The treatment of fractures of the proximal radius is controversial. This retrospective elaborates on indications for operative or conservative treatment, dependent on fracture type. A new classification of fracture and a new evaluation score for follow-up examination are presented. The study shows very good results for conservative treatment of type A1-fractures without dislocation of fragments and good results for operative treatment of type A2-fractures. Type A3-fractures (multifragment fractures) demand reconstruction. If that is not possible, the primary resection of the radial head leads to better results than its secondary resection. The implantation of silastic prostheses of the radial head leads to worse results in primary (2 cases) and secondary resection (2 cases) than resection of radial head alone.

[Results of cementless acetabular revision surgery]. / Ergebnisse zementfreier Hüftpfannenwechseloperationen.

The great number of hip revision arthroplasties and the cementless fixation of arthroplasties has led to more and cementless hip revision operations with bone transplantation. This retrospective study shows the results of a clinical and radiological follow-up of 34 patients with an average age of 71 years and 4 months at their hip revision arthroplasty. The subjective and clinical result in the Harris-Hip-Score 3 years and 9 months (1 year 4 months-6 years 3 months) after surgery shows 67% of the patients content with the result of the revision arthroplasty. The Harris-Hip-Score shows an average of 41.1 points preoperatively and 73.2 points at the follow-up examination. The loosening-rate was 11.8%, all arthroplasties which seemed loosened radiologically had also a bad result clinically. No correlation could be shown between the age of the patients and the clinical results as well as between an additional stem revision (15 patients) and the clinical result in the Harris-Hip-Score. All revision operations were done with bone transplantation and demonstrate, that the concept of cementless fixation of acetabular component gives satisfactory results.

[Concomitant injuries with anterior cruciate ligament rupture. A retrospective study]. / Begleitverletzungen frischer vorderer Kreuzbandrupturen. Eine retrospektive Studie.

We identified 107 consecutive patients with anterior cruciate ligament (ACL) rupture who underwent arthroscopy after trauma. The results of the preoperative clinical examination and the arthroscopic findings of associated injuries to the knee are shown. Some 55% of the acute ACL ruptures involved a tear of the lateral meniscus, 45% of the medial meniscus, and 34% had a lesion of the medial collateral ligament. The most frequent combination of injuries with ACL rupture was a tear in both menisci and a lesion of the medial collateral ligament with a tear in the lateral meniscus. The preoperative examination revealed the ACL rupture in 94% of uses but the lateral meniscal lesion in only 32%. At the time of operation 29% of all associated injuries had not been discovered. These results show that--independent of the time of reconstruction of the thorn ACL--acute rupture of the ACL is an indication for arthroscopy.

[Chronic shoulder pain in the volleyball attack player]. / Der chronische Schulterschmerz des Volleyballangriffsspielers.

30 competitive volleyball attackers of the German third league, 15 with shoulder pain (group I) and 15 without shoulder pain (group II) were examined clinically and sonographically. Anamnesis was also carried out. The results were compared with those of a control of 15 non-volleyball players not subject to stress caused by overhead use of their arms. On the visual analog scale the average pain was 5.1 (SD 1.4). The average history of pain was 2.7 (SD 2.7) years. Cause for the pain was "spiking without warming up" (n = 7) or "unknown" (n = 8). Spiking respectively serving caused new pain sensation in 14 (11) attackers. Players of group I stretched shorter than those of group II. Pain was located laterally to the greater tuberculum (n = 8), at the origin of the deltoid muscle (n = 3), at the bicipital groove (n = 2) or in the area of the ventral glenoid (n = 2). Pain was caused by active anteversion above 160 degrees (n = 3), active abduction above 140 degrees (n = 2) or both (n = 10). The playing shoulder was depressed in all 30 volleyball attackers. By measuring the distance from the epicondylus radii to the acromion of the other side by maximal forced horizontal adduction, the distance from the margo medialis scapula to the spine, the distance from the tip of middle finger to the lumbar spine by maximal internal rotation of the shoulder up the back showed significant differences between both sides and between the groups. The spiking arm scapula is significantly lateralised compared to the opposite side and compared to sportsmen.(ABSTRACT TRUNCATED AT 250 WORDS)

[Stress-related clinical and ultrasound changes in shoulder joints of handball players]. / Belastungsabhängige klinische und sonographische Veränderungen an den Schultergelenken von Handballspielern.

This prospective clinical and ultrasound study was performed to show specific overuse injuries or changes in the periarticular structures of shoulder joints. Therefore, 11 male handball players with an average age of 23 years and 6 months were evaluated via a standardised shoulder exam sheet and an ultrasound examination before, one hour after, 10-12 hours after, 16-20 hours after and 22-24 hours after specific handball training. Characteristic changes were found in respect of bursitis subacromialis and tendinitis of biceps tendon up to 16-20 hours after training, which were fully reversible 22-24 hours after the stress. The effusion was visible for more than 24 hours after the training but was reversible 60 hours after stress. This study shows characteristic pariarticular changes in the shoulder joint of handball players without any clinical finding in physical examination, so that the ultrasound changes seem to be a physiological reaction to the specific stress. These changes should therefore not be misinterpreted especially if there are no clinical symptoms.

[Results of surgical treatment of peroneal tendon dislocations]. / Ergebnisse der operativen Behandlung bei Peronealsehnenluxationen.

Dislocation of the peroneal tendons is a very uncommon injury and therefore the diagnosis will often be missed and the patient will not be treated sufficiently. This results in a chronic situation which handicaps the patients in their everyday life and in their sports activities. The diagnosis of the acute injury is often "sprain of the ankle" or "rupture of the fibular ligaments". The first one is often treated insufficiently by a tape for a short time, and the second one is treated surgically and the dislocation recognized only during the operation for the first time. Considering the results of the follow-up examination (clinically, X-ray and ultrasonic), surgical treatment of the dislocation of the peroneal tendons is mandatory. The risks during and after the operation are negligible. Surgical treatment enables the patients to return to their everyday life and sports activities without any complaints.

[Pattern of injuries in skiing worldwide. Can current guidelines for adjusting ski bindings reduce injuries in the future?]. / Verletzungsmuster beim Skifahren weltweit. Können die derzeitigen Einstellrichtlinien die Verletzungen auch in Zukunft reduzieren?

World wide injuries show an overall reduction in skiing injuries. Updating the work of Hauser and Gläser (20) the average injury value declines from about 7 injuries per 1000 ski days in 1960 to 2 injuries per 1000 ski days in 1990. A stagnation can be reported for the past 5 years and no dramatic reduction is to be expected. Important, however is the trend of increasing knee injuries. As the risk for knee injuries was prevalent for female skiers (36, 15, 12) we also found a higher number of combined knee injuries especially including the medial collateral ligament (MCL). As the current binding adjustments do not focus on them, we are having a closer look about the advantages and disadvantages of each method. The final result is a suggestion for a radical change. By means of a new binding setting method and the demand for more responsibility to the skier we try to create a new skiing safety idea consisting of the setting table, a recommended binding release test and a gear binding. This is supposed to serve as the basis for a new safety approach.

[Results following percutaneous intramedullary pin fixation in distal radius fractures]. / Ergebnisse nach percutaner intramedullärer Bohrdrahtspickung bei distalen Radiusfrakturen.

42 distal radius fractures have been submitted to further examination after percutaneous intramedullary pin fixation. The outcome were 95.3% of very good to good anatomic results and 90.5% of satisfying functional results. This showed the close link between the radiological-anatomical and functional results. The success of the treatment was very acceptable, although the Morbus Sudeck as the major complication--with 7.2%--was still relatively frequently observed. It could be seen that particularly fractures at the risk of dislocation with smash zone constituted an indication for the percutaneous intramedullary pin fixation, that is to say all fractures for which a retention is primarily difficult. It constitutes a supplement, as well as an extension to the therapy of the distal radius fractures.

Surgical treatment of dislocations of the acromioclavicular joint in the athlete.

The treatment of the sports related dislocation of the acromioclavicular joint remains controversial. This study was carried out to determine whether or not a combined surgical procedure consisting of repair and polydioxanone (PDS)-cord augmentation of the coracoclavicular ligaments, fixation of the acromioclavicular joint with a single Kirschner wire as well as the repair of the acromioclavicular ligament permitted return to athletic activity. Athletes were examined with regard to their range of motion, pain and their ability to return to the performance level achieved before the injury. During the period 1986-1989, 21 athletes were treated. Follow-up averaged 22 months. Return of athletes to previous performance level was related to their original degree of activity. Two recreational once-a-week athletes did not return to this level, 19 patients, including five competitive athletes, continued their previous activities. There was no correlation between coracoclavicular ossification or post-traumatic arthritis and a good or excellent result. We recommend the operative treatment of acromioclavicular separations in athletes.

[Results of a combined surgical procedure in complete Tossy III acromioclavicular joint dislocation]. / Ergebnisse eines kombinierten Operationsverfahrens bei der kompletten AC-Gelenkluxation Tossy III.

This paper presents the results of a follow-up examination of 31 patients who had undergone reconstructive surgery for complete acromioclavicular (AC) dislocation between 1 September 1986 and 30 June 1989. The operation performed consisted in suturing of coracoclavicular and acromioclavicular ligaments with a coracoclavicular PDS cord augmentation and a transarticular K-wire left in place for 6 weeks. The follow-up investigation included a questionnaire on subjective assessment and daily problems with the treated shoulder, a clinical examination and a X-ray of both shoulders with 10 kg weight on each side. Good and very good results were found in 93% for clinical patterns, in 90% for subjective opinion, and in 79% for radiological examination. No correlation could be found between clinical results and radiological results, even concerning AC joint arthrosis following the operation.