Evaluation of a fiber-optic technique for recording intramuscular pressure in the human leg.

To evaluate a forward-sensing fiber-optic pressure technique for recording of intramuscular pressure (IMP) in the human leg and investigate factors that may influence IMP measurements used in diagnosing compartment syndromes. IMP in the tibialis anterior muscle was recorded simultaneously by a fiber-optic technique and needle-injection technique in 12 legs of 7 healthy subjects. Both measurement catheters were placed in parallel with the muscle fibers to the same depth, as verified by sonography. IMP recordings were performed at rest before, during and after applying a model of abnormally elevated IMP (simulated compartment syndrome). IMP was elevated by venous obstruction induced by a thigh tourniquet of a casted leg. IMP was also measured during injections of 0.1 ml of saline into the muscle through the catheters. IMP at baseline was 5.1 (SD = 2.6) mmHg measured with the fiber-optic technique and 7.1 (SD = 2.5) mmHg with the needle-injection technique (p < 0.001). It increased to 48.5 (SD = 6.9) mmHg and 47.6 (SD = 6.6) mmHg respectively, during simulated compartment syndrome. IMP increased significantly following injection of 0.1 ml of saline, measured by both techniques. It remained increased 1 min after injection. The fiber-optic technique was able to record pulse-synchronous IMP oscillations. The fiber-optic technique may be used for IMP measurements in a muscle with both normal and abnormally elevated IMP. It has good dynamic properties allowing for measurement of IMP oscillations. Saline injection used with needle-injection systems to ensure catheter patency compromises IMP readings at least one minute after injection.

Effects of electrical nerve stimulation on force generation, oxygenation and blood volume in muscles of the immobilized human leg.

BACKGROUND: Transcutaneous electrical stimulation of the common peroneal nerve may be an additional clinical tool for enhancing venous return by active and passive mechanisms of muscle action in the immobilized leg. PURPOSES: To determine the effects of electrical stimulation of the common peroneal nerve to (1) produce force during isometric ankle joint dorsiflexion, and (2) alter muscle oxygenation and blood volume in the resting human leg. METHODS: A novel electrical stimulator was applied to 28 legs of 14 healthy subjects. The force during isometric ankle joint dorsiflexion and myoelectric responses produced by stimulation-induced leg muscle contractions were investigated. Muscle oxygen saturation, blood volume and deoxygenated haemoglobin in the tibialis anterior and medial gastrocnemius muscles were measured by near-infrared spectroscopy during venous stasis (40 mmHg thigh tourniquet), with or without electrical stimulation. Results. The force produced during ankle joint dorsiflexion at the maximal stimulation intensity was 2.25 N (0.02-14.14) in the resting leg. Changes in muscle oxygen saturation during venous stasis, with or without electrical stimulation, were similar. Electrical stimulation during venous stasis caused 4-9% and 0.2-6% less increase in total muscle blood volume and deoxygenated hemoglobin compared to venous stasis alone. CONCLUSIONS: Nerve stimulation with a newly developed device partly counteracts increases in muscle blood volume and deoxygenated hemoglobin of the resting leg during venous stasis. CLINICAL RELEVANCE: The device stimulates active and passive mechanisms of leg muscle action that seems to enhance venous return in patients with impaired function.

Biopsychosocial function analyses changes the assessment of the ability to work in patients on long-term sick-leave due to chronic musculoskeletal pain: the role of undiagnosed mental health comorbidity.

AIMS: To study the prevalence of somatic and mental health comorbidity and the use of opioid medication among patients on long-term sick-leave due to chronic musculoskeletal pain (CMP); to compare an orthopaedic-based assessment of ability to work with a team assessment; to investigate the relationship between intensity of pain and psychosocial characteristics in this group. METHODS: A cross-sectional study was carried out with 174 consecutive patients on sick-leave for a mean of 21 months. All were referred from the Social Insurance Office for orthopaedic evaluation and assessment of the ability to work. Of them, only 83/174 patients were referred by the Office for psychiatric evaluation. RESULTS: Neck pain was the main cause of disability. Patients with neck pain often suffered pain in more than two sites, and greater intensity of pain. Thirty-four percent of all participants had been prescribed opioid medication before consultation. Degrees of disability, unemployment, low degree of education and to be an immigrant were related to intensity of pain. Unrecognized psychiatric disorders changed the main cause of inability to work in 69% of patients who underwent both orthopaedic and psychiatric evaluation. CONCLUSIONS: An evaluation based on biopsychosocial function is valuable in reaching an accurate assessment of the patient's diagnosis, and ability to work in CMP. Ability to work and degree of sick-leave in patients on long-term sick-leave is determined to a large extent by undiagnosed mental health comorbidities, and not solely somatic complaints.

Early loading in physiotherapy treatment after full-thickness rotator cuff repair: a prospective randomized pilot-study with a two-year follow-up.

OBJECTIVE: To describe the clinical changes following two different physiotherapy treatment protocols after rotator cuff repair. DESIGN: A prospective, randomized pilot study with a two-year follow-up. SUBJECTS: Five women and nine men, 55 (40-64) years old, were included. INTERVENTION: The progressive group (n = 7) started with dynamic, specific muscle activation of the rotator cuff the day after surgery as well as passive range of motion. After four weeks of immobilization the loading to the rotator cuff increased and in a progressive manner throughout the rehabilitation. In the traditional group (n = 7) the rotator cuff was protected from loading. Patients were immobilized for six weeks and started with passive range of motion the day after surgery. No specific exercises to the rotator cuff were introduced during this period. MAIN MEASURES: A clinical evaluation was made preoperatively, 3, 6, 12 and 24 months after surgery. Pain rating during activity and at rest, patient satisfaction, active range of motion and muscle strength, Constant score, hand in neck, hand in back and pour out of a pot, as well as Functional Index of the Shoulder were used. RESULTS: At two years follow-up, the progressive group and traditional group scored pain during activity visual analogue scale (VAS) 2/0 mm and pain at rest 0/0 mm, respectively. The groups attained 170/175 degrees in active abduction in standing and 70/90 degrees in passive external rotation while lying in supine. Using Constant score, the groups attained 82/77 points respectively. CONCLUSION: The present study showed that the progressive protocol produced no adverse effects compared with the traditional protocol.

Patient pain drawing is a valuable instrument in assessing the causes of exercise-induced leg pain.

AIM: We validated patientpain drawing (PPD) in establishing the diagnosis of chronic anterior compartment syndrome (CACS) in patients with exercise-induced leg pain. METHODS: The study comprised 477 consecutive patients, all suspected of having CACS. The diagnosis was based on the patient's history, a thorough clinical examination and measurements of intramuscular pressure (IMP) following an exercise test. Patients completed a PPD before their hospital visit. Two independent orthopaedic surgeons diagnosed the causes of leg pain based only on the PPD at least 1 year after admission. Based on the results of diagnostic tests, the patients were divided into three groups: CACS (n=79), CACS with comorbidity (n=89) and non-CACS (n=306). RESULTS: The sensitivity of the PPD to identify CACS correctly was 67% (observer 1) and 75% (observer 2). The specificity was 65% and 54%, respectively. The interobserver agreement (n=477) was 80%, and the kappa value was 0.55. The interobserver agreement was 77%, and the kappa value was 0.48 among 168 CACS patients with or without comorbidity. The interobserver agreement was 85%, and the kappa value was 0.56 in 79 CACS, and CACS was correctly diagnosed in 79% (observer 1) and 82% (observer 2). The test-retest showed the same results for the two observers, with an intraobserver agreement of 84%, while the test-retest reliability coefficient was 0.7. Comorbidity was found in 53% of CACS patients. CONCLUSION: PPD might be a valuable instrument in diagnosing the causes of exercise-induced leg pain. It is useful in identifying CACS with and without comorbidity.

Experiences of moving with persistent pain--a qualitative study from a patient perspective.

OBJECTIVE: The aim of the present study was to use a phenomenological approach to explore how patients with persistent musculoskeletal pain experienced moving with their pain. DESIGN: In-depth interviews were performed by a physical therapy researcher with many years' experience with the rehabilitation of patients with persistent musculoskeletal pain. SETTING: The patients took part in individual rehabilitation at two different physical therapy departments. All but one patient opted to be interviewed in a room at the physical therapy department. METHOD: The sample was purposive and consisted of 10 Swedish outpatients with heterogeneous nonmalignant persistent musculoskeletal pain. SUBJECTS: The interviews were analyzed according to a qualitative method known as the Empirical Phenomenological Psychological (EPP) method. The results were coded, analyzed, and described in typologies. RESULTS: The experience of moving with pain implied much more than pure physical movement. Pain was a threatening challenge to the informants' existence and identity. Three typologies were identified: failed adaptation, identity restoration, and finding the way out. CONCLUSIONS: In conclusion, to move with persistent pain was described by the informants as having deep existential impact on the individual's life. It was also evident that all of the informants experienced a dramatic change in their identity. These experiences would most likely affect the patients' chances of recovery. To help him/her through the rehabilitation process, we need to extend our knowledge about what it means to the patient in an existential context to be unable to move as before.

Kinesiophobia among patients with musculoskeletal pain in primary healthcare.

OBJECTIVES: To describe the occurrence of kinesiophobia and to investigate the association between kinesiphobia and pain variables, physical exercise measures and psychological characteristics in patients with musculoskeletal pain. DESIGN: A prospective descriptive study involving 2 selected physiotherapy departments within a primary healthcare setting in the south-west of Sweden. PATIENTS: Included were 140 of 369 (38%) consecutive patients (aged between 18 and 65 years) with musculoskeletal pain. METHODS: Questionnaires including background data, pain variables, physical exercise measures and psychological characteristics were sent to the patients prior to their appointment with the physiotherapist. A simple and a multiple logistic regression model were performed to identify associations among the variables where kinesiophobia was defined as the dependent variable. RESULTS: A high degree of kinesiophobia and psychological distress were observed in approximately 50% of the responders. According to the simple logistic regression analysis the factors that seemed to be associated with kinesiophobia were interference, disability, pain severity, pain intensity, life control, affective distress, depressed mood and solicitous response. The multiple logistic regression analysis showed no significant associations. CONCLUSION: Kinesiophobia is a commonly seen factor among patients with musculoskeletal pain, which ought to be taken into consideration when designing and performing rehabilitation programmes.

Changes in Muscle Oxygen Saturation Have Low Sensitivity in Diagnosing Chronic Anterior Compartment Syndrome of the Leg.

BACKGROUND: Near-infrared spectroscopy measures muscle oxygen saturation (StO2) in the skeletal muscle and has been proposed as a noninvasive tool for diagnosing chronic anterior compartment syndrome (CACS). The purpose of this study was to investigate the diagnostic value of changes in StO2 during and after exercise in patients with CACS. METHODS: The study comprised 159 consecutive patients with exercise-induced leg pain. Near-infrared spectroscopy was used to measure StO2 continuously before, during, and after an exercise test. One minute post-exercise, intramuscular pressure was recorded in the same muscle. The cohort was divided into patients with CACS (n = 87) and patients without CACS (n = 72) according to the CACS diagnostic criteria. Reoxygenation at rest after exercise was calculated as the time period required for the level of muscular StO2 to reach 50% (T50), 90% (T90), and 100% (T100) of the baseline value. RESULTS: The lowest level of StO2 during exercise was 1% (range, 1% to 36%) in the patients with CACS and 3% (range, 1% to 54%) in the patients without CACS. The sensitivity was 34% and the specificity was 43% when an StO2 level of ≤8% at peak exercise was used to indicate CACS. The sensitivity and the specificity were only 1% when an StO2 level of ≤50% at peak exercise was used to indicate CACS. The time period for reoxygenation was seven seconds (range, one to forty-three seconds) at T50, twenty-eight seconds (range, seven to seventy-seven seconds) at T90, and forty-two seconds (range, seven to 200 seconds) at T100 in the patients with CACS and ten seconds (range, one to forty-nine seconds) at T50, thirty-two seconds (range, four to 138 seconds) at T90, and forty-eight seconds (range, four to 180 seconds) at T100 in the patients without CACS. When thirty seconds or more at T90 was set as the cutoff value for a prolonged time for reoxygenation, indicating a diagnosis of CACS, the sensitivity was 38% and the specificity was 50%. CONCLUSIONS: Changes in muscle oxygen saturation during and after an exercise test that elicits leg pain cannot be used to distinguish between patients with CACS and patients with other causes of exercise-induced leg pain.

The amplitude of pulse-synchronous oscillations varies with the level of intramuscular pressure in simulated compartment syndrome.

BACKGROUND: Patients with compartment syndromes have elevated intramuscular pressure (IMP) due to increased volume in the affected muscle. However, the accuracy of IMP as a parameter in diagnosing chronic compartment syndrome has been questioned. It has been observed that arterial pulsations create oscillations in the IMP in patients with abnormally elevated IMP. The amplitude of the IMP oscillations appears to be related to a pathogenic mechanism of elevated IMP. Therefore, the purpose of the present study was to investigate the relation between the amplitude of pulse-synchronous IMP oscillations and the absolute level of IMP with a high-end fiber-optic system in a human experimental model of abnormally elevated IMP (simulated compartment syndrome) of the leg. The hypothesis that the amplitude of the IMP oscillations is correlated to the absolute level of IMP was tested. METHODS: IMP was measured at rest in the anterior tibial muscle in 12 legs of 7 healthy subjects (4 females and 3 males) with a mean age of 28 (range 23-38) years. The subject lay supine with his/her heel placed in a footrest. The foot was kept in a neutral position to avoid biased IMP readings. Measurements were performed at baseline and during 10 minutes with a model of abnormally elevated IMP (simulated compartment syndrome) applied. The abnormally elevated IMP was created by venous obstruction induced by a thigh tourniquet (65 mmHg) of a casted leg. Placement of the pressure-recording catheter was verified by sonography. RESULTS: The IMP increased from 4.7 (SD = 1.8) mmHg at baseline to 48.6 (SD = 7.1) mmHg when the model of elevated IMP was applied. The amplitude of the pulse-synchronous oscillations was undetectable at baseline. It increased to 3.9 (SD = 1.4) mmHg with increasing IMP when the model was applied. The amplitude of the oscillations showed a positive correlation (r = 0.59) with the absolute level of IMP. CONCLUSIONS: The amplitude of the pulse-synchronous IMP oscillations is correlated with the absolute level of IMP during abnormally elevated IMP. The oscillations of IMP may therefore be an additional parameter assuring the abnormally elevated IMP in the diagnosis of compartment syndromes.

The effect of the stay active advice on physical activity and on the course of acute severe low back pain.

BACKGROUND: Disability due to acute low back pain (ALBP) runs parallel with distress and physical inactivity. If low back pain persists, this may lead to long-term sick leave and chronic back pain. This prospective randomized study evaluated the effect on physical activity and on the course of ALBP of two different treatment advices provided in routine care. METHODS: Ninety-nine patients with acute severe LBP examined within 48 h after pain onset were randomized to the treatment advices "Stay active in spite of pain" (stay active group) or "Adjust activity to the pain" (adjust activity group). Pedometer step count and pain intensity (Numeric Rating Scale, NRS, 0-10) were followed daily during seven days. Linear mixed modeling were employed for statistical analyses. RESULTS: The step count change trajectory showed a curvilinear shape with a steep initial increase reaching a plateau after day 3 in both groups, followed by an additional increase to day 7 in the stay active group only. At day 1, the step count was 4560 in the stay active group compared to 4317 in adjust activity group (p = 0.76). Although there were no statistical differences between the two groups in the parameters describing the change trajectory for step count, the increase in step count was larger in the stay active group. At day 7 the step count was 9865 in the stay active group compared to 6609 in the adjust activity group (p = 0.008). The pain intensity (NRS) trajectory was similar in the two groups. Between day 1 and day 7 it decreased linearly from 5.0 to 2.8 in the stay active group (p < 0.001), and from 4.8 to 2.3 in the adjust activity group (p < 0.001). CONCLUSIONS: Patients with acute severe LBP advised to stay active in spite of the pain exhibited a considerable more active behavior compared to patients adjusting their activity to pain. This result confirms compliance to the treatment advice as well as the utility of the stay active advice to promote additional physical activity for more health benefits in patients with ALBP. There was minimal effect of the treatment advice on the course of ALBP. TRIAL REGISTRATION: ClinicalTrials.gov (NCT02517762).

Prediction of outcome in whiplash-associated disorders using West Haven-Yale Multidimensional Pain Inventory.

OBJECTIVE: To investigate the predictive capacity of the West Haven-Yale Multidimensional Pain Inventory (MPI) with regard to prolonged pain, using car occupants who had sustained a neck sprain in a traffic accident. DESIGN: A prospective cohort study including a one-year follow-up. PATIENTS: One hundred thirty adults were examined by a specialized neck-injury team after a first visit to an accident and emergency department. The subjects answered the MPI questionnaire within one month of the accident. OUTCOME MEASURES: One year later, the patients answered a questionnaire about residual neck pain. The main outcome was determined by the question, "Do you have residual pain which you relate to the accident?" RESULTS: One hundred twenty-three (95%) of the subjects completed the study. Ninety-seven reported pain of some degree that they related to the accident. All but one of the MPI variables differed significantly between the group with residual pain and the group without pain. The variable interference had the strongest correlation with the outcome. Its discriminative capacity was 81% for those with pain and 94% for those without pain one year later. CONCLUSIONS: The MPI may be used at an early stage to identify patients who may develop chronic neck-pain after a traffic accident, at least in those who want a follow-up session after an initial visit to an accident and emergency department.

Improved tibial cutting accuracy in knee arthroplasty.

Initial stability and development of long-term fixation for cementless tibial components at the knee both depend on the accuracy of fit between implanted components and prepared bone surfaces. Tibial surfaces prepared for total knee replacement with conventional saw-blades and guides were shown by Toksvig-Larsen to vary by over 2 mm, from a flat surface at the point of maximum variation, and all points varied with a standard deviation of up to 0.4 mm. Surface cutting errors are caused by flexion of the saw-blade and blade angulation from the ideal alignment, due to poor guidance or control by the saw-block or guide. Most conventional knee instrumentation relies on flat surface or slotted cutting blocks, constraining the moving saw-blade against one or two guide surfaces. Improved cutting action was achieved by constraining the saw from the pivot point of the blade, and controlling motion of this constraint with parallel action slides. Using this saw-guide and an improved saw-blade, tibial cuts were made in mock arthroplasty procedures on twenty four cadaveric tibiae in mortuo. Analysis of Variance and Tukey's HSD test showed that the improved saw technique yielded significantly better flatness (p < 0.03) and greatly improved roughness (p < 0.0005).

Unintentional forces developed during isometric test of the shoulder.

OBJECTIVE: To study unintentional, spontaneous forces developed during isometric shoulder strength testing. DESIGN: An experimental study. BACKGROUND: During torque measurements, subjects may apply forces in directions other than requested, thereby obscuring the interpretation of the results. METHODS: A shoulder strength test was performed with a strength test device permitting measurements of force in the requested direction as well as perpendicular to it. Nine fishermen and nine welders performed isometric abduction and elevation with the arm held in various angles. Moreover four rotational postures were investigated. RESULTS: Spontaneous force deviations from requested direction were found in almost all posture tested, with errors--defined as 100 times the ratio of the magnitude of intentional torque to the magnitude of unintentional (erroneous) torque generated perpendicular to it--of more than 30% found for some postures. Abduction in 45 degrees horizontal flexion was better controlled than abduction in 90 degrees horizontal flexion. Detailed analysis indicated some groupwise differences between fishermen and welders. Also pairwise comparison of handiness indicated some differences. CONCLUSIONS: Considerable deviations from requested direction of action can arise during strength tests. Thus, one must either monitor these deviations or minimize them by a proper design of the examination to get relevant data. As the error can differ between certain subject categories depending on posture this indicate a new tool for discriminating between musculo-skeletal problems. RELEVANCE: Muscle strength devices must be used with care as their measurement setups may mask the truce muscle action of the patients.

Using the Amplitude of Pulse-Synchronous Intramuscular Pressure Oscillations When Diagnosing Chronic Anterior Compartment Syndrome.

BACKGROUND: To diagnose chronic anterior compartment syndrome (CACS) among patients with exercise-induced leg pain, intramuscular pressure (IMP) is regarded as the gold standard. Two recent studies have suggested that the evidence for commonly used IMP criteria are weak, and the validity has therefore come under question. PURPOSE: To evaluate whether the amplitude of pulse-synchronous IMP oscillations at rest after an exercise test is a reliable parameter that may aid in diagnosing CACS. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A total of 89 consecutive patients with suspected CACS (mean age, 31 years) and 19 healthy subjects (mean age, 28 years) participated in this study. All participants performed an exercise test until they were unable to continue because of leg pain and/or muscle fatigue. The IMP was recorded continuously in the anterior compartment of the leg with a noninfusion pressure recording system, starting 15 to 30 seconds after discontinuation of exercise. To test the amplitude of pulse-synchronous IMP oscillations as an indicator of CACS, a peak-to-peak amplitude of >2 mm Hg was chosen as the cutoff value. The clinical diagnosis of CACS was considered reference standard. RESULTS: The mean ± SD IMP 1 minute after exercise was 54 ± 16 mm Hg in 53 patients with CACS, 17 ± 6 mm Hg in 36 non-CACS patients, and 18 ± 5 mm Hg in control subjects. The mean amplitude of the oscillations was 7.1 ± 3 mm Hg in patients with CACS, 1.3 ± 0.9 mm Hg in non-CACS patients, and 1.5 ± 0.6 mm Hg in control subjects 1 minute after exercise. The sensitivity of the amplitude to validate CACS was 96%, while the specificity was 94%. The positive predictive value was 96%, and the negative predictive value was 94%. CONCLUSION: The amplitude of the pulse-synchronous IMP oscillations at rest after an exercise test that elicits a patient's leg pain and muscle fatigue has high sensitivity to identify an abnormally elevated IMP. CLINICAL RELEVANCE: Oscillations are easily recorded during clinical routine IMP measurements. They ascertain the diagnosis of CACS, corroborate the level of IMP, and ensure catheter patency.