Ulrich Moritz

A stabilometric technique for evaluation of lower limb instabilities

Stabilometry is a technique designed to register pos tural equilibrium control. This investigation used a com puterized strain gauge force plate to measure sway movements in the frontal plane with the patient standing on one leg. Fifty-five young healthy individuals were studied as a reference group and to determine the reproducibility of the method. The clinical population consisted of 14 patients with unilateral injuries to the lateral ligaments of the ankle. These were measured, both with and without an ankle brace. The different parameters used to describe the body sway could well discriminate between the injured and the uninjured leg. When the brace was used the effect was obvious and none of the parameters showed any significant differ ence compared to the uninjured leg.

The Effect of Physiotherapy on Standing Balance in Chronic Anterior Cruciate Ligament Insufficiency

Body sway movements in the frontal plane in a single- limbed stance test were used to assess postural control in 26 patients with chronic anterior cruciate ligament insufficiency. The injured and the noninjured legs were tested before the patients were committed to physio therapy for 3 to 6 months. Follow-up tests were made after 3, 12, and 36 months. Significant disturbance of the balance of both legs was found before training, com pared with a reference group of normal subjects. Values of the noninjured leg were normalized after 3 months of training, but the injured leg still showed an increased body sway. Normal balance parameters on the injured side were found at examination after 12 months. Follow-up examination after 36 months proved persis tent normalization of the single-limbed balance on both sides.

Proprioception in the nearly extended knee. Measurements of position and movement in healthy individuals and in symptomatic anterior cruciate ligament injured patients

Proprioception of the knee was measured in 19 healthy individuals to evaluate whether there were any differences between extension and flexion movements from two different starting positions. The threshold before detecting a passive movement, visual estimation on a protractor of a passive change in position (30o angular change) and active reproduction of the same angular change were registered. The reference population was tested twice to study normal variation and reproducibility, followed by the evaluation of 20 patients with chronic, symptomatic and unilateral anterior cruciate ligament (ACL)-deficient knees. In the normal population no differences were found between the right and the left leg, men and women, or measurements made at the first and at the second test occasion. The thresholds from a starting position of 20o were lower for extension than for flexion. When comparing the thresholds for extension between the 20o and the 40o starting position, lower values were lower from the 40o starting position. than from the 20o starting position. The active reproduction of an angular change of 30o was more accurate during flexion (30o–60o) than during extension (60o-30o). There were no differences in the reproduction tests or in thresholds from the 40o starting position between the patients and the normal group, but the patients had higher thresholds from the 20o starting position, in movements towards both extension 1.0o (range 0.5o–12.0o) and flexion 1.5o (range 0.5o–10.0o) than the normal group 0.75o (range 0.5o–2.25o) (P=0.01) and 1.0o (range 0.5o–3.0o) (P=0.06), respectively. Thus, information of passive movements in the nearly extended knee position was more sensitive towards extension than towards flexion in threshold tests and the sensitivity improved closer to full extension, which implies a logical joint protective purpose. In this nearly extended knee position, which is the basis for most weight-bearing activities, patients with symptomatic ACL-deficient knees had an impaired awareness in detecting a passive movement. There were no differences in the more flexed position or in the reproduction tests between the patients and the normal group, and reproduction tests in the present form seem less appropriate to use in the evaluation of ACL injuries.

Wrist positions and movements as possible risk factors during machine milking.

High prevalence of hand and wrist symptoms has been found in females working with machine milking. Therefore the aim of this study was to quantify the positions and movements of the wrist during machine milking, and to compare tethering and loose-housing systems with respect to this. Biaxial electrogoniometers and data loggers were used for recording flexion and deviation angles of both the right and left wrists in 11 healthy milkers. For each individual 25 min of representative work was recorded in each system. High values of dorsiflexion and radial deviation were found, which might induce an increased risk of carpal tunnel syndrome. Moreover, the velocity and repetitiveness were close to those values described in repetitive work with a high risk of elbow and hand disorders in the fish-processing industry and giro-form data entry work. According to our findings, the load on the upper extremities has increased with respect to dorsiflexed hand position and repetitiveness when milking in the modern loose-housing milking system. This is probably due to the change of the working position and/or the higher productivity (number of cows that milked per time unit) in the loose-housing system as compared to the old-fashioned tethering system. These negative effects on wrist positions and movements should be considered when building new milking systems.

Stabilometry and one-leg hop test have high test-retest reliability

The purpose of this study was to investigate the reliability of repeated measurements and a possible learning or tiring process in single‐limb stabilometry and one‐leg hop test. An additional purpose was to study the correlation between different stabilometric variables. Seventy‐five healthy subjects were examined twice with a median interval of 7 d, and with three consecutive measurements on each occasion. Single‐limb stabilometry and one‐leg hop test were found to have high reliability (ICC r= 0.68–0.83 and 0.96, respectively). The correlation between consecutive measurements was acceptable to high in stabilometry (r= 0.42–0.90, P=0.002–P<0.001) and high in the one‐leg hop test (r=0.91–0.97, P<0.001). A learning process over time was observed. The correlation between the stabilometric variables was high (r=0.73–0.95, P<0.001).

Electromyographic fatigue in neck/shoulder muscles and endurance in women with repetitive work

EMG was recorded with surface electrodes from the trapezius and deltoid muscles during a static endurance test at approximately 20% of maximal voluntary contraction. Objective parameters for localized muscular fatigue were derived from the time course of the root mean square (RMS) and mean power frequency (MPF) of the EMG recordings. Isotonic regression is introduced as a tool for assessment of such parameters. The most pronounced sign of fatigue for trapezius was an increase in the RMS values, while for deltoid it was a decrease in the MPF values. This could be explained by the different functions of the two muscles. The endurance time for a group of 11 women in industrial work with repetitive short-cycled work tasks who were diagnosed with neck/shoulder disorders (tension neck) was significantly shorter (p less than 0.05) than for a group with the same work, but without neck/shoulder disorders (n = 11), and shorter than for a control group (n = 11). Regarding the EMG fatigue measures, there were no significant differences between the three groups. We did not find any relationships between endurance time and the EMG parameters. The results indicate that neck/shoulder disorders were not associated with divergent mechanisms for developing fatigue in the muscles, as recorded with surface EMG.

Rehabilitation following acute anterior cruciate ligament injuries – a 12-month follow-up of a randomized clinical trial

The efficacy of two non‐operative rehabilitation programs was studied in a consecutive randomized controlled clinical trial of 100 patients after 12 months subsequent to an acute anterior cruciate ligament (ACL) injury. Follow up of randomization to two training models was evaluated after 3 and 12 months: A self‐monitored training program (SM) of traditional mobility and muscle strength training of the injured leg was compared to a supervised (SV) training model exercising postural function in closed kinetic‐chains. Nearly 50% of the patients in the SM group required supervision after 6 weeks. An intention‐to‐treat analysis was performed and showed significantly better values in most of the results of the supervised group at 3 and 12 months. An alternative analysis of subgroups showed a significant difference between transferred male patients and original SV male patients at 3 months but not at 12 months, indicating the importance of initial guiding after an ACL injury. No such difference was observed in the female patients.

Does calf-muscle fatigue affect standing balance ?

The purpose of this study was to find out whether fatiguing calf‐muscle exercise affects postural sway during standing. Thirteen healthy subjects with a mean age of 25 years participated. Body sway in one leg stance was measured on a force plate before and after fatiguing exercises of the calf muscles of the subjects right leg. Repeated measurements for up to 10 min after exercises showed no increase of body sway. The results indicate that postural control in quiet standing can be maintained by compensatory mechanisms activated during muscle fatigue. A significant decrease of body sway over time on the non‐fatigued leg indicated a learning effect. A similar decrease was not observed on the fatigued leg, indicating interference of compensatory mechanisms on learning.

Pressure pain thresholds and electromyographically defined muscular fatigue induced by a muscular endurance test in normal women.

OBJECTIVE This study was undertaken to examine the relation between muscular tenderness measured as pressure pain thresholds (PPTs) and electromyographic (EMG) signs of fatigue before and after a local standardized static muscle contraction. DESIGN Pressure pain thresholds were measured in the shoulder region before, immediately after, and 10 minutes after a standardized static endurance test while monitoring the EMG signs of local muscular fatigue and its recovery. The study did not address local biochemical issues. SETTING The study was conducted at the Department of Rehabilitation, Lund University Hospital, Lund, Sweden. SUBJECTS Twenty-five healthy female volunteers without musculoskeletal problems participated in this study. INTERVENTION A static endurance test was performed, which consisted of a submaximal unilateral activation of the right trapezius and deltoid muscles for as long as possible. OUTCOME MEASURES Bilateral PPTs over the trapezius and deltoid muscles were measured with an electronic pressure algometer. Established surface EMG parameters of local muscular fatigue were assessed. The Borg Rating of Perceived Exertion scale was used. RESULTS The average endurance time was 330 seconds. Immediately after the test, significant bilateral increases in the normalized PPTs over both muscles were found, although the increase was more pronounced on the test side: over the right trapezius muscle by 13% (p <0.001), over the right deltoid muscle by 23% (p <0.001), and over the left trapezius and deltoid muscles by 6% (p = 0.04) and (p = 0.009), respectively. These increases persisted 10 minutes after the end of the test. The subjects developed significant signs of fatigue as defined by EMG criteria in both muscles on the right side during the test. The recovery from fatigue was approximately half complete 15 seconds after the end of the test and complete or almost complete 10 minutes thereafter. CONCLUSIONS Pressure pain thresholds over shoulder muscles remained elevated up to 10 minutes after a unilateral static endurance test. This time course was completely different from that of EMG-defined muscle fatigue, which showed a fast recovery. These findings indicate that the mechanisms of recovery from fatigue and nociception are independent of each other. The bilateral PPT increases might be explained by central antinociceptive mechanisms activated by static muscle work.

Upper extremity muscular load during machine milking

Abstract Epidemiological studies have shown a high prevalence of wrist and hand disorders associated with machine milking. The occurrence of tingling, numbness and reduced muscle strength indicates peripheral nerve involvement. This has been confirmed by clinical examination revealing median nerve entrapment at the carpal tunnel and/or the elbow level. In a previous study, we showed that machine milking implied high values of dorsiflexion and radial deviation of the wrist, which may be associated with an increased risk of developing such conditions as carpal tunnel syndrom. To evaluate the impact of the muscle tension on the nerve structures bilateral electromyographic recordings (EMG), of the biceps muscle and the flexor and extensor muscles of the forearm were performed in eleven healthy subjects milking both in a traditional and a more modern system. The peak loads for the flexor and extensor muscles were close to their maximum capacity which, in combination with positions and movements of the hand and forearm, might contribute to the development of nerve injuries in addition to other tissue lesions such as tendinitis. Milking in the traditional tethering system was associated with higher peak loads than milking in the more modern loose-housing system. On the other hand, the modern milking system, which had a considerably higher productivity, implied higher “static” load and a lower relative duration of muscular rest, as compared to the traditional system. Relevance to industry Electromyography (EMG) was used to assess the muscular load during milking in two different milking systems. The results of this study will provide the basis for developing new techniques adapted to the demands of the work and antropometrics of the female milkers in order to reduce the risk of injuries in the upper extremity.