Novel mechanisms of range of motion improvement in response to plantar flexor stretch training in men

The process of neuromuscular adaptation in response to muscle stretch training has not been clearly described. In the present study, changes in muscle (at fascicular and whole muscle levels) and tendon mechanics, muscle activity and the excitability of the motor neurone pool were examined during plantar flexor stretches after 3 wk of twice-daily stretch training (4 × 30-s straight-knee calf muscle stretches; 41.0 ± 1.2 sessions). No changes were observed in a control group (N=9), however stretch training elicited a 19.9% increase in dorsiflexion range (ROM) and 28% increase in passive joint moment at volitional stretch termination (N=12). Only a trend toward a decrease in passive moment during stretch (-9.9%, p=0.15) was observed and no changes in maximum EMG amplitude, EMG amplitude at stretch termination or joint angle at EMG onset were detected during a maximal stretch. Decreases in Hmax:Mmax elicited by tibial nerve stimulation were observed at plantar flexed (gastrocnemius medialis and soleus) and neutral (soleus only) joint angles, but not with the ankle dorsiflexed (i.e. with the muscle on stretch). There was an increase in muscle (12.2%) and fascicle (22.6%) strain and a decrease in muscle stiffness (-18%) during stretch to a target joint angle, and an increase in muscle length at stretch termination (13%) without a change in fascicle rotation, tendon elongation or tendon stiffness after the training. A lack of change in peak active joint moment and RFD at any joint angle was taken to indicate a lack of change in series compliance of the muscle-tendon unit. These results indicate that improvements in ROM were underpinned by increases in the maximum tolerated passive joint moment (‘stretch tolerance’) and muscle/fascicle elongation rather than by changes in volitional muscle activation or motor neurone pool excitability. Changes in the muscles’ passive elastic properties are not likely to be explained by changes within the series elastic component

Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans

The neuromuscular adaptations in response to muscle stretch training have not been clearly described. In the present study, changes in muscle (at fascicular and whole muscle levels) and tendon mechanics, muscle activity, and spinal motoneuron excitability were examined during standardized plantar flexor stretches after 3 wk of twice daily stretch training (4 x 30 s). No changes were observed in a nonexercising control group (n = 9), however stretch training elicited a 19.9% increase in dorsiflexion range of motion (ROM) and a 28% increase in passive joint moment at end ROM (n = 12). Only a trend toward a decrease in passive plantar flexor moment during stretch (-9.9%; P = 0.15) was observed, and no changes in electromyographic amplitudes during ROM or at end ROM were detected. Decreases in Hmax:Mmax (tibial nerve stimulation) were observed at plantar flexed (gastrocnemius medialis and soleus) and neutral (soleus only) joint angles, but not with the ankle dorsiflexed. Muscle and fascicle strain increased (12 vs. 23%) along with a decrease in muscle stiffness (-18%) during stretch to a constant target joint angle. Muscle length at end ROM increased (13%) without a change in fascicle length, fascicle rotation, tendon elongation, or tendon stiffness following training. A lack of change in maximum voluntary contraction moment and rate of force development at any joint angle was taken to indicate a lack of change in series compliance of the muscle-tendon unit. Thus, increases in end ROM were underpinned by increases in maximum tolerable passive joint moment (stretch tolerance) and both muscle and fascicle elongation rather than changes in volitional muscle activation or motoneuron pool excitability

Novel mechanisms of range of motion improvement in response to plantar flexor stretch training in men

The process of neuromuscular adaptation in response to muscle stretch training has not been clearly described. In the present study, changes in muscle (at fascicular and whole muscle levels) and tendon mechanics, muscle activity and the excitability of the motor neurone pool were examined during plantar flexor stretches after 3 wk of twice-daily stretch training (4 × 30-s straight-knee calf muscle stretches; 41.0 ± 1.2 sessions). No changes were observed in a control group (N=9), however stretch training elicited a 19.9% increase in dorsiflexion range (ROM) and 28% increase in passive joint moment at volitional stretch termination (N=12). Only a trend toward a decrease in passive moment during stretch (-9.9%, p=0.15) was observed and no changes in maximum EMG amplitude, EMG amplitude at stretch termination or joint angle at EMG onset were detected during a maximal stretch. Decreases in Hmax:Mmax elicited by tibial nerve stimulation were observed at plantar flexed (gastrocnemius medialis and soleus) and neutral (soleus only) joint angles, but not with the ankle dorsiflexed (i.e. with the muscle on stretch). There was an increase in muscle (12.2%) and fascicle (22.6%) strain and a decrease in muscle stiffness (-18%) during stretch to a target joint angle, and an increase in muscle length at stretch termination (13%) without a change in fascicle rotation, tendon elongation or tendon stiffness after the training. A lack of change in peak active joint moment and RFD at any joint angle was taken to indicate a lack of change in series compliance of the muscle-tendon unit. These results indicate that improvements in ROM were underpinned by increases in the maximum tolerated passive joint moment (‘stretch tolerance’) and muscle/fascicle elongation rather than by changes in volitional muscle activation or motor neurone pool excitability. Changes in the muscles’ passive elastic properties are not likely to be explained by changes within the series elastic component

Large increase in arthroscopic meniscus surgery in the middle-aged and older population in Denmark from 2000 to 2011

Background - Arthroscopic meniscal surgery is the most common orthopedic procedure, and the incidence has increased in Denmark over the last 10 years. Concomitantly, several randomized controlled trials have shown no benefit of arthroscopic procedures including arthroscopic partial meniscectomy in middle-aged and older individuals suffering from knee pain with or without knee osteoarthritis. We examined the annual incidence of meniscal procedures together with age, sex, and diagnosis for patients who underwent meniscal procedures in the period 20002011 in Denmark. Methods - Data on age, sex, diagnosis, and surgical procedures were extracted from the Danish National Patient Register for the years 2000-2011, for all records containing meniscal surgery as a primary or secondary procedure. Results - The overall annual incidence of meniscal procedures per 100,000 persons in Denmark doubled from 164 in 2000 to 312 in 2011 (i.e. 8,750 procedures to 17,368 procedures). A 2-fold increase was found for patients aged between 35 and 55, and a 3-fold increase was found for those older than 55. Middle-aged and older patients accounted for 75% of all 151,228 meniscal procedures carried out between 2000 and 2011. Interpretation - The incidence of meniscal procedures performed in Denmark doubled from 2000 to 2011, with the largest increase in middle-aged and older patients. This increase contrasts with the mounting evidence showing no added benefit of arthroscopic partial meniscectomy over non-surgical treatments. Our observations illustrate the long delay in the dissemination, acceptance, and implementation of research evidence into the practice of arthroscopic surgery

Down on one knee: soft tissue knee injuries across the lifespan

Joint injury is a potent risk factor for osteoarthritis, the most important musculoskeletal disease affecting humankind. Yet the population incidence of soft tissue knee injury is not well documented. Using health-care register data from Sweden, Peat and colleagues report that soft tissue knee injuries are common, peak in adolescence and early adulthood, have a second spike in women who are 35 to 49 years old, and continue throughout the lifespan. The study highlights the need for more knowledge on the natural history of knee injuries, their impact on knee osteoarthritis development and progression, and the potential for prevention programs to reduce the incidence of these injuries

Assessing baseline dependency of anchor-based minimal important change (MIC): don’t stratify on the baseline score!

Purpose: The minimal important change (MIC) of a patient-reported outcome measure (PROM) is often suspected to be baseline dependent, typically in the sense that patients who are in a poorer baseline health condition need greater improvement to qualify as minimally important. Testing MIC baseline dependency is commonly performed by creating two or more subgroups, stratified on the baseline PROM score. This study’s purpose was to show that this practice produces biased subgroup MIC estimates resulting in spurious MIC baseline dependency, and to develop alternative methods to evaluate MIC baseline dependency. Methods: Datasets with PROM baseline and follow-up scores and transition ratings were simulated with and without MIC baseline dependency. Mean change MICs, ROC-based MICs, predictive MICs, and adjusted MICs were estimated before and after stratification on the baseline score. Three alternative methods were developed and evaluated. The methods were applied in a real data example for illustration. Results: Baseline stratification resulted in biased subgroup MIC estimates and the false impression of MIC baseline dependency, due to redistribution of measurement error. Two of the alternative methods require a second baseline measurement with the same PROM or another correlated PROM. The third method involves the construction of two parallel tests based on splitting the PROM’s item set. Two methods could be applied to the real data. Conclusion: MIC baseline dependency should not be tested in subgroups based on stratification on the baseline PROM score. Instead, one or more of the suggested alternative methods should be used

Declining trends in arthroscopic meniscus surgery and other arthroscopic knee procedures in Denmark : a nationwide register-based study

Background and purpose — A doubling of arthroscopic meniscal procedures was observed in Denmark from 2000 to 2011, but arthroscopic meniscal procedures for degenerative meniscal tears are no longer recommended. We performed an updated investigation of Danish meniscal procedure trends in the private and public healthcare sectors in Denmark from 2006 to 2018, including trends for other arthroscopic knee procedures. Patients and methods — We extracted data on the 5 most commonly registered arthroscopic knee procedures (diagnostic arthroscopy, meniscal surgery, anterior cruciate ligament reconstruction, synovectomy, and cartilage resection) from the Danish National Patient Register from January 1, 2006 to December 31, 2018, linked with the Danish Population Statistic Register, to obtain data on age and sex. Results — 414,253 arthroscopic knee procedures were registered during 315,290 surgeries on 244,113 individual patients in the study period. For meniscal procedures, the highest incidence was observed in 2010 (319 per 105 persons/year, 95% CI 314–323) and the lowest in 2018 (173 per 105 persons/year, CI 169–176), corresponding to relative decrease of 46% from 2010 to 2018. Remaining arthroscopic procedures also showed declining trends, with lowest incidence for all procedures in 2018. Interpretation — A large decrease in the incidence for arthroscopic meniscal procedures was observed from 2010 to 2018, possibly in response to mounting evidence of limited benefit of this procedure for degenerative knee disease. All other investigated arthroscopic knee procedures also declined in the same period