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Biomedical subjects

J Styf

Publications and source records attributed to J Styf.

At least 19 recordsLinked to original sources
PubMed2005

Non-invasive monitoring of muscle blood perfusion by photoplethysmography: evaluation of a new application.

AIM: To evaluate a specially developed photoplethysmographic (PPG) technique, using green and near-infrared light sources, for simultaneous non-invasive monitoring of skin and muscle perfusion. METHODS: Evaluation was based on assessments of changes in blood perfusion to various provocations, such as post-exercise hyperaemia and hyperaemia following the application of liniment. The deep penetrating feature of PPG was investigated by measurement of optical radiation inside the muscle. Simultaneous measurements using ultrasound Doppler and the new PPG application were performed to elucidate differences between the two methods. Specific problems related to the influence of skin temperature on blood flow were highlightened, as well. RESULTS: Following static and dynamic contractions an immediate increase in muscle perfusion was shown, without increase in skin perfusion. Liniment application to the skin induced a rapid increase in skin perfusion, but not in muscle. Both similarities and differences in blood flow measured by Ultrasound Doppler and PPG were demonstrated. The radiant power measured inside the muscle, by use of an optical fibre, showed that the near-infrared light penetrates down to the vascular depth inside the muscle. CONCLUSIONS: The results of this study indicate the potentiality of the method for non-invasive measurement of local muscle perfusion, although some considerations still have to be accounted for, such as influence of temperature on blood perfusion.

Adult↗
PubMed2004

Muscle blood flow in response to concentric muscular activity vs passive venous compression.

AIM: To measure muscle blood flow (MBF) using photoplethysmography (PPG) following concentric muscular activity of the leg (active treatment) or passive venous compression (passive treatment) with or without venous obstruction. METHODS: In study A, blood flow in the anterior tibial muscle was measured in 15 healthy subjects with a mean age of 30 years. In study B, blood flow in the gastrocnemius muscle was measured in nine healthy subjects with a mean age of 34 years. Subjects performed concentric muscular activity in one leg. Passive venous compression by a venous foot pump was applied in the contralateral leg. RESULTS: MBF increased significantly following concentric muscular activity, but not following passive venous compression. MBF decreased in both legs when venous obstruction, induced by a thigh tourniquet, was applied. However, MBF was significantly higher following concentric muscular activity than passive venous compression. CONCLUSION: We conclude that concentric muscular activity produces higher MBF values than passive venous compression.

Adolescent↗
PubMed2004

Abnormally elevated intramuscular pressure impairs muscle blood flow at rest after exercise.

We used photoplethysmography (PPG) to measure the relative changes in the anterior tibial muscle blood flow (MBF) in response to exercise when intramuscular pressure (IMP) was elevated (the test leg) or when IMP was normal (the control leg). The elevated IMP was induced by applying venous obstruction of 40 mmHg or 65 mmHg (thigh tourniquet) of a casted leg in eight healthy subjects. Subjects performed dorsiflexion of both feet in sitting position with or without venous obstruction. IMP at rest after exercise increased to 39.4+/-7.9 mmHg or to 58.3+/-8.4 mmHg, respectively. MBF at rest before exercise was 100%. At rest after exercise, it increased to 184+/-52.6% in the test leg when IMP was 39.4 mmHg, and to 279+/-108.3% in the control leg. MBF at rest after exercise was 156+/-58.2% in the test leg when IMP was 58.3 mmHg and 303+/-95.3% in the control leg. The abnormally elevated IMP induced by venous obstruction of a casted leg reduced MBF at rest after exercise. PPG seems to be a suitable method to measure changes in MBF in response to exercise and in experimental conditions with abnormally elevated IMP.

Adult↗
PubMed2001

The influence of fracture etiology and type on fracture healing: a review of 104 consecutive tibial shaft fractures.

This study was conducted to determine retrospectively the factors which influence fracture healing and risk for nonunion in patients with tibial shaft fractures. One hundred consecutive patients with 104 tibial shaft fractures and a mean age of 40 (14-85) years were reviewed. Fractures were classified according to the AO classification system. There were 22 open fractures and 52 comminuted fractures. Thirty-eight fractures were caused by high-energy trauma. Fracture pattern, soft-tissue condition, level of energy of the trauma, malalignment, and treatment methods were identified. The influence of these factors on the time of hospital stay and sick-leave, delayed union, and nonunion were calculated. Normal healing occurred in 61 fractures with a mean healing time of 17 weeks, delayed union in 27 with a mean of 35 weeks, and nonunion in 16 with a mean of 69 weeks. The relative risk of developing nonunion in open fractures was 8.2 (CI = 2.9-10.5) and 2.9 (CI = 1.2-3.2) in fractures exposed to high-energy trauma. This study showed that the soft-tissue condition and level of trauma energy are good predictors for the development of complications. Considering these risk factors at an early stage in the planning of treatment might reduce the risk of nonunion. ergy level of the trauma, fracture comminution, initial fracture displacement, treatment method, contamination, and associated injuries will influence fracture healing. Conservative treatment has in general been recommended for undisplaced closed or grade I open fractures caused by low-energy trauma [15, 18, 21]. However, conservative treatment of a tibial shaft fracture means immobilization of the lower leg for a long period of time, especially if healing is delayed. Thus, it is important to consider the risk of healing complications when planning the appropriate treatment method in the early stage after the injury. The purpose of this study was to analyze complications such as delayed union and nonunion and to identify factors which affect the healing of tibial shaft fractures.

Adolescent↗
PubMed2001

A non-invasive measure of changes in blood flow in the human anterior tibial muscle.

We used photoplethysmography (PPG) to monitor blood flow changes in the human anterior tibial muscle during arterial occlusion and during isometric and concentric contractions. Single-fibre laser-Doppler flowmetry (LDF) was used as a reference in 12 healthy subjects (5 men, 7 women; mean age 24 years). Post-exercise hyperaemic muscle blood flow (MBF) was measured immediately after isometric dorsiflexion of the ankle joint at maximal contraction for 1 min and full range-of-motion dorsiflexion and plantar flexion of the ankle joint for 1 min. A thigh tourniquet was applied for the evaluation of post-occlusive reactive hyperaemia. The MBF (baseline = 100%) was [mean (SD)] 150 (31)% (P = 0.003) by PPG (880 nm) and 182 (66)% (P = 0.012) by LDF. After 1 min of maximal isometric contraction, MBF increased to 150 (51)% (P = 0.003) by PPG (880 nm) and to 169 (43)% (P = 0.005) by LDF. After 1 min of maximal concentric contractions, MBF increased to 158 (59)% (P = 0.003) by PPG (880 nm) and to 170 (99)% (P = 0.008) by LDF. Skin blood flow, PPG (560 nm), did not change significantly after isometric or concentric contractions. The results indicate that reactive hyperaemia after exercise and arterial occlusion can be assessed in the human anterior tibial muscle using PPG.

Adult↗
PubMed2001

Effects of limb elevation and increased intramuscular pressure on human tibialis anterior muscle blood flow.

The effects of limb elevation and increased intramuscular pressure (IMP) on blood flow in the tibialis anterior muscle and leg neuromuscular function were studied in eight healthy subjects. Muscle blood flow (MBF) was measured by photoplethysmography using a custom-designed probe. IMP was elevated bilaterally by vein obstruction (60-65 mmHg) lasting 30 min induced by a thigh tourniquet of casted legs. Skin sensibility of the feet and the amplitude and area of the compound muscle action potentials from the extensor digitorum brevis muscle were evaluated. The subject kept one leg elevated 32 cm above heart level and the contralateral leg at heart level. All recordings were made before, during and after vein obstruction. IMP increased to 40 mmHg in the vein-obstructed casted legs. Perfusion pressure decreased from [mean (SD)] 42 (5.8) mmHg to 17 (6.4) mmHg in the elevated leg and from 65 (9.9) mmHg to 43 (8.4) mmHg in the non-elevated leg. MBF decreased by 50% in the elevated leg and by 42% in the non-elevated leg. Subjects experienced sensory dysfunction and muscular weakness in the elevated leg. In conclusion, increased IMP, induced by venous obstruction of a casted leg, reduced perfusion pressure and MBF, and resulted in a diminished amplitude and area of the compound muscle action potentials. Limb elevation above heart level combined with venous stasis of a casted leg further reduced perfusion pressure and MBF, and induced sensory dysfunction and muscular weakness.

Action Potentials↗
PubMed2001

Postural control and torque of the knee joint after healed tibial shaft fracture.

Muscular atrophy occurs as a consequence of trauma and immobilisation. This cohort comparison study was conducted to evaluate the limb function after healed tibial shaft fractures, which were treated by casting versus nailing. Balance (as centre of pressure) and muscle strength (as torque of the knee joint during knee extension) have been measured in 27 patients with tibial shaft fractures with a mean age of 39 (19-73) years, 1 year after fracture healing. Fourteen patients were treated by intramedullary nailing 'nailed group' and 13 by plaster cast with or without minimal internal fixation 'casted group'. Centre of pressure was measured on a force platform. Knee extension torque was measured during isometric and concentric muscle actions by an isokinetic dynamometer. Centre of pressure tended to be more towards the uninjured leg in patients who had been treated by plaster cast (P<0.05). Side-to-side differences for isometric torque were significantly higher within the casted group (P<0.05). Patients with tibial shaft fractures treated by intramedullary nailing showed better postural control, one-leg standing test, and side-to-side differences for isometric muscle strength compared with patients treated by cast. Therefore, we recommend intramedullary nailing as a better method of treatment for tibial shaft fractures, with regard to recovery of muscle function.

Adult↗
PubMed2001

Early active rehabilitation after surgery for lumbar disc herniation: a prospective, randomized study of psychometric assessment in 50 patients.

In a randomized study, using psychometric assessment, we evaluated two training programs before and after surgical treatment of lumbar disc herniation. 26 patients were treated according to an early active training program (treatment group). 24 patients followed a traditional less active training program (control group). Before surgery, the patients filled in the following questionnaires 3 and 12 months after surgery: Multidimensional Pain Inventory (MPI), State and Trait Anxiety Inventory, and Beck Depression Inventory. Pain was assessed by the patient's pain drawing and a visual analog scale. Both groups improved as regards pain severity and state of anxiety. The MPI parameter, pain interference, improved more in the early active treatment group than in the control group. This suggests that the early active training program has a positive effect on the way patients cope with pain in their daily lives.

Adolescent↗
PubMed2001

Salvaged limbs after tibial shaft fractures with extensive soft-tissue injury: a biopsychosocial function analysis.

BACKGROUND: The purpose of this study was to perform a biopsychosocial function analysis of the outcome in patients with a salvaged leg after tibial shaft fractures associated with extensive soft-tissue injury. METHODS: A retrospective review of 18 consecutive patients with tibial shaft fractures and extensive soft-tissue damage with a mean Injury Severity Score of 31 was undertaken. All patients were assessed for their physical function, psychological status, and general function. RESULTS: The range of motion and torque of the ankle joint were severely affected. The knee joint was affected, but only with regard to the torque during concentric muscular activities. Nottingham Health Profile scores showed that the general and social function for these patients were significantly affected. Five of 18 patients suffered from depression. CONCLUSION: Salvage procedures should be advocated if possible, but careful selection of patients on the basis of mental and social factors is crucial for the outcome.

Adaptation, Psychological↗
PubMed2000

The effects of limb elevation and increased intramuscular pressure on nerve and muscle function in the human leg.

In this study we investigated the effects of increased intramuscular pressure (IMP) on nerve and muscle function in the leg and foot. In study A, muscle pressure was increased by inducing venous stasis in both legs, placed in plaster casts, of eight healthy subjects having a mean age of 29 years. The results from elevated and non-elevated limbs were compared. In study B, two different models for increasing IMP were studied in nine healthy subjects having a mean age of 32 years. The results of increased IMP and decreased blood perfusion pressure on local (= leg) and distal (= foot) function of muscle and nerve induced by venous stasis of a leg in a plaster cast and by external compression of the contralateral leg were compared. Contraction pressure of the tibialis anterior muscle in the leg was recorded. A biphasic compound muscle action potential was measured from the extensor hallucis brevis and the extensor digitorum muscles as an indication of foot muscle function. Muscle contraction pressure was 87 (SD 38) mm Hg in the vein-obstructed leg and 133 (SD 42) mm Hg in the externally compressed leg (P<0.05). In both studies the skin sensibility of the feet was significantly lower in the vein-obstructed elevated leg after 30 min (P<0.05). Vein stasis in an elevated human leg in a plaster cast defines a model for simulating imminent acute compartment syndrome with reversible neuromuscular dysfunction.

Action Potentials↗
PubMed2000

Displaced tibial shaft fractures: a prospective randomized study of closed intramedullary nailing versus cast treatment in 53 patients.

Of 53 patients with unilateral, displaced and closed or grade 1 open tibial shaft fractures, 27 patients (group I) were randomized to treatment with an intramedullary nail and 26 patients (group II) to treatment with a plaster cast. 12 fractures in the latter group were considered stable enough for treatment with only a cast (group IIa), while 14 fractures in group II showed redisplacement during reduction under anesthesia or at 1 week follow-up. Therefore, these fractures were stabilized with cerclage or screws (group IIb), which was a prerequisite for continuing cast treatment. The mean time-to-union was 19 weeks for group I, and 25 weeks for group II. 6 patients in group I and 16 in group II had delayed union. The Nottingham Health Profile index scores on physical mobility, social isolation, work ability, and sexual life were significantly better in group I than in group II at 3 months after injury. Delayed union, malunion, and restricted range of motion at the ankle joint were common complications when these fractures were treated with a cast. We recommend intramedullary nailing for these fractures.

Activities of Daily Living↗
PubMed2000

Wound closure by dermatotraction after fasciotomy for acute compartment syndrome.

Intramuscular pressure (IMP) was measured in 16 patients during secondary wound closure by dermatotraction with external tissue extension (ETE). Secondary wound closure was done 4-16 days after fasciotomy for acute compartment syndrome. The traction between wound edges was 2.5 N in the first six patients and 3.5 N in the following 10 patients. Mean (SD) IMP was 6.9 (3.5) mmHg before wound closure. It increased to 12.3 (1.4) mmHg in the 2.5 N group and to 24.7 (7.0) mmHg in the 3.5 N group when dermatotraction was applied. Mean (SD) leg perfusion pressure in the 2.5 N group decreased by 7% to 69.3 (10.9) mmHg and in the 3.5 N group by 23% to 62.2 (7.4) mmHg. None of the patients needed a skin graft. We conclude that dermatotraction by ETE raises IMP intraoperatively sufficiently to preserve adequate limb perfusion pressures.

Acute Disease↗
PubMed1999

Effects of isokinetic muscle activity on pressure in the supraspinatus muscle and shoulder torque.

Work-related shoulder pain is an increasing problem. Work in overhead positions, which causes high pressure in the supraspinatus muscle, has been shown to increase the shoulder load. It is not known how different types of muscle activity in the shoulder affect pressure in the muscle. The aim of this study was to investigate the difference between contraction modes. This has not been done before for shoulder muscles. The results are relevant from several aspects, both clinical and experimental. Pressure in the supraspinatus muscle and torque generation in the shoulder during isokinetic concentric and eccentric activity were measured in nine healthy human subjects. Torque and arm position were measured continuously with a computerized ergonometer. The contraction velocity was 60 degrees per second, and the range of movement was 0-120 degrees of abduction. Electromyographic measurements were recorded with a surface electrode above the supraspinatus muscle belly. Intramuscular pressure was recorded with a microcapillary infusion technique. Peak intramuscular pressure did not differ significantly between the two modes of contraction, but the peak was reached at 115 degrees (SD = 15 degrees) of abduction during concentric activity and at 6 degrees (SD = 7 degrees) of abduction during eccentric activity. The ratio between intramuscular pressure and torque was 3.0 mm Hg/Nm (0.40 kPa/Nm) during concentric activity and 2.3 mm Hg/Nm (0.31 kPa/Nm) during eccentric activity. The peak torque occurred at 44 degrees of abduction during concentric muscle activity and at 74 degrees of abduction during eccentric activity. Intramuscular pressure was higher during isometric contraction than during eccentric and concentric activity, and the torque was in between the two latter contraction modes. We conclude that the supraspinatus muscle is heavily loaded not only in high arm positions during concentric contraction but also during eccentric contraction in arm positions of 0-30 degrees of abduction.

Adult↗
PubMed1999

Early mobilization versus immobilization after ankle ligament stabilization.

Functional outcome, stability at radiographic investigation and ankle joint torque after anatomical reconstruction of the lateral ankle ligaments were evaluated in patients with early postoperative mobilization versus those with cast immobilization. Thirty patients with chronic lateral ligament instability of the ankle underwent anatomical reconstruction of the ligaments. Postoperatively the patients were randomly allocated to two groups: Group A (n=15) were immobilized in a below-knee plaster for 6 weeks and Group B (n=15) underwent early controlled range of motion training using an Air-Cast ankle brace. The functional results were evaluated using a scoring scale and objective results using standardized stress radiographs. Also eccentric and concentric muscle torque at 60 degrees/s was measured in plantar flexion and dorsiflexion, respectively. The functional results were satisfactory in 12/15 ankles in Group A and 14/15 in Group B (n.s.). All the patients with satisfactory results regained normal range of motion. Patients with unsatisfactory results had either residual pain or recurrent instability. In Group B, the strength measurements revealed significantly higher peak torque values after three months in plantar flexion at 60 degrees/s. Six months postoperatively, the torque values did not differ significantly between the groups. Also, there was no group difference in the laxity of the ankle joint, including both anterior talar translation test and talar tilt test, at the two-year follow-up. One patient had a superficial wound infection. We conclude that after the reconstruction of chronic lateral ligament instability of the ankle the functional and stability results were equally good with early postoperative mobilization and 6-week immobilization. However, using early mobilization plantar flexion strength was regained earlier than with cast immobilization, without any risk of short- or medium-term complications, such as increased ankle laxity. We recommend early mobilization after anatomical reconstruction of the lateral ankle ligaments.

Adolescent↗
PubMed1999

The effects of functional knee bracing on muscle function and performance.

When applied, knee braces compress the soft tissues of the thigh and leg. External compression may abnormally elevate intramuscular pressure beneath the straps of the knee brace, decrease local muscle blood flow and muscular oxygenation, and induce premature muscle fatigue. Functional knee braces may give valuable support to athletes with unstable knees. They may also be a valuable rehabilitative tool in patients following surgery for knee joint instability. However, prophylactic and functional knee braces do not improve performance and may even inhibit performance in asymptomatic athletes. Athletes and coaches should be aware of the serious adverse effects of knee bracing.

Athletic Injuries↗
PubMed1998

Early active training after lumbar discectomy. A prospective, randomized, and controlled study.

STUDY DESIGN: A prospective, randomized, and controlled study was conducted. OBJECTIVES: To evaluate two training programs, both of which started immediately after lumbar discectomy. SUMMARY OF BACKGROUND DATA: In previous studies, patients began physiotherapy between 4 weeks and 60 months after surgery. No studies have been conducted to evaluate a physiotherapy program that begins immediately after surgery. METHOD: Twenty-six patients were treated according to an early active training program. Twenty-six patients were treated with a traditional, less active training program (control group). All patients were examined immediately before and after surgery and 3, 6, 12, and 52 weeks after surgery by an unbiased observer. Two years after surgery, patients completed a questionnaire. Range of motion of the lumbar spine and straight leg raising were measured. pain intensity and location was measured by a visual analog scale. The duration of sick leave was documented. RESULTS: Six and 12 weeks after surgery, patients with dominating residual leg pain had significantly less intense pain in the early active training group than those in the control group (P < 0.05). Twelve weeks after surgery, range of motion of the lumbar spine was significantly more increased in the early active training group (P < 0.01). One year after surgery, there was no significant difference between the groups regarding the duration of sick leave, results in a positive straight leg raising, or pain intensity. Twenty-two (88%) patients in the early active training group and 16 (67%) in the control group were satisfied with the treatment outcome 2 years after surgery (P < 0.10). CONCLUSIONS: Patients rehabilitated according to the early active training program had a better short-term outcome of objective values. At 2 years' follow-up, more patients were satisfied with the result of the operation. The early active treatment program is recommended.

Adult↗
PubMed1998

Evaluation of techniques for measuring negative intramuscular pressures in humans.

Negative external pressure has been used previously in experiments on the blood circulation in humans and is currently being considered as a counter-measure to the musculoskeletal deconditioning which occurs during the exposure to microgravity. Intramuscular pressure (IMP) measurement is an important tool for determining the effectiveness of the transmission of negative pressure. Therefore two IMP techniques, a fibre optic transducer-tipped catheter and a fluid-filled teflon catheter with side holes, were evaluated using laboratory and human tests for measuring negative pressures. For the laboratory tests, both catheters were placed inside a lower leg negative pressure (LLNP) chamber and pressures of 0, -20, -50, -80, -100 and back to 0 mmHg were applied. Both catheters measured pressures equally and remained stable over 1 min at all pressure levels. When the teflon catheter was infused at rates commonly used for IMP recordings at normal atmospheric pressures, the drip rate at the catheter tip increased inversely with the magnitude of negative pressure. The cables and pressure tubings of the catheters within the LLNP chamber were not affected by the negative pressures. For tests in humans, the catheters were inserted side by side in the tibialis anterior muscle in eight legs of four human volunteers. The leg was placed in the LLNP chamber and pressures of 0, -20, -50, -80 and back to 0 mmHg were applied. The teflon catheter was used without infusion. Both catheters measured IMP similarly at rest and both remained stable over 1 min at all pressure levels; also the IMP during muscle contractions and immediately following contractions was similarly recorded by both catheters. We concluded that both catheter systems are suitable for recording negative pressures over a wide range. As is the case with recordings at normal atmospheric pressures, the fibre optic transducer-tipped catheter system may be preferred when recording IMP in a negative pressure environment when complex limb movements are involved.

Adult↗