Nicholas C. Clark

Proprioception in musculoskeletal rehabilitation. Part 1: Basic science and principles of assessment and clinical interventions

INTRODUCTIONnImpaired proprioception has been reported as a feature in a number of musculoskeletal disorders of various body parts, from the cervical spine to the ankle. Proprioception deficits can occur as a result of traumatic damage, e.g., to ligaments and muscles, but can also occur in association with painful disorders of a gradual-onset nature. Muscle fatigue can also adversely affect proprioception and this has implications for both symptomatic and asymptomatic individuals. Due to the importance of proprioception for sensorimotor control, specific methods for assessment and training of proprioception have been developed for both the spine and the extremities.nnnPURPOSEnThe aim of this first part of a two part series on proprioception in musculoskeletal rehabilitation is to present a theory based overview of the role of proprioception in sensorimotor control, assessment, causes and findings of altered proprioception in musculoskeletal disorders and general principles of interventions targeting proprioception.nnnIMPLICATIONSnAn understanding of the basic science of proprioception, consequences of disturbances and theories behind assessment and interventions is vital for the clinical management of musculoskeletal disorders. Part one of this series supplies a theoretical base for part two which is more practically and clinically orientated, covering specific examples of methods for clinical assessment and interventions to improve proprioception in the spine and the extremities.

Proprioception in musculoskeletal rehabilitation. Part 2: Clinical assessment and intervention

INTRODUCTIONnProprioception can be impaired in gradual-onset musculoskeletal pain disorders and following trauma. Understanding of the role of proprioception in sensorimotor dysfunction and methods for assessment and interventions is of vital importance in musculoskeletal rehabilitation. In Part 1 of this two-part Masterclass we presented a theory-based overview of the role of proprioception in sensorimotor control, causes and findings of altered proprioception in musculoskeletal conditions, and general principles of assessment and interventions.nnnPURPOSEnThe aim of this second part is to present specific methods for clinical assessment and interventions to improve proprioception in the spine and extremities.nnnIMPLICATIONSnClinical assessment of proprioception can be performed using goniometers, inclinometers, laser-pointers, and pressure sensors. Manual therapy, taping, and bracing can immediately enhance proprioception and should be used to prepare for exercise interventions. Various types of exercise (active joint repositioning, force sense, co-ordination, muscle performance, balance/unstable surface, plyometric, and vibration training) should be employed for long-term enhancement of proprioception.

Residual Impact of Previous Injury on Musculoskeletal Characteristics in Special Forces Operators

Background Musculoskeletal injuries are a significant burden to United States Army Special Operations Forces. The advanced tactical skill level and physical training required of Army Special Operators highlights the need to optimize musculoskeletal characteristics to reduce the likelihood of suffering a recurrent injury. Purpose To identify the residual impact of previous injury on musculoskeletal characteristics. Study Design Cross-sectional study; Level of evidence, 3. Methods Isokinetic strength of the knee, shoulder, and back and flexibility of the shoulder and hamstrings were assessed as part of a comprehensive human performance protocol, and self-reported musculoskeletal injury history was obtained. Subjects were stratified based on previous history of low back, knee, or shoulder injury, and within-group and between-group comparisons were made for musculoskeletal variables. Results Knee injury analysis showed no significant strength or flexibility differences. Shoulder injury analysis found internal rotation strength of the healthy subjects (H) was significantly higher compared with injured (I) and uninjured (U) limbs of the injured group (H, 60.8 ± 11.5 percent body weight [%BW]; I, 54.5 ± 10.5 %BW; U, 55.5 ± 11.3 %BW) (P = .014 [H vs I] and P = .05 [H vs U]). The external rotation/internal rotation strength ratio was significantly lower in the healthy subjects compared with injured and uninjured limbs of the injured group (H, 0.653 ± 0.122; I, 0.724 ± 0.121; U, 0.724 ± 0.124) (P = .026 [H vs I] and P = .018 [H vs U]). Posterior shoulder tightness was significantly different between the injured and uninjured limb of the injured group (I, 111.6° ± 9.4°; U, 114.4° ± 9.3°; P = .008). The back injury analysis found no significant strength differences between the healthy and injured groups. Conclusion Few physical differences existed between operators with prior knee or back injury. However, operators with a previous history of shoulder injury demonstrated significantly less shoulder strength than uninjured operators as well as decreased shoulder flexibility on the injured side. All operators, regardless of prior injury, must perform the same tasks; therefore, a targeted injury rehabilitation/human performance training specifically focused on internal rotation strength and tightness of the posterior capsule may help reduce the risk for recurrence of injury. Operators presenting with musculoskeletal asymmetries and/or insufficient strength ratios may be predisposed to musculoskeletal injury. Clinical Relevance Specific fitness programs to compensate for deficiencies in strength and flexibility need to be designed that may reduce the risk of injuries in Special Forces Operators.

Do not throw the baby out with the bathwater; screening can identify meaningful risk factors for sports injuries

Norway’s Professor Roald Bahr recently highlighted that screening does not predict which athlete will sustain an injury.1 Some interpreted this to mean screening is useless for injury prevention. However, screening remains essential in our efforts to protect athletes’ health. To extend what has been a robust discussion, we argue how screening can be important for an individual athlete , and offer potential reasons why and how individual screening tests still lack clinical utility.nnPrevious injury is a well-established injury risk factor. Figure 1 shows data on ACL (re)injuries from Krosshaug et al .2 Applying a traditional (predictive) diagnostic test on these data yields unimpressive results; a positive predictive value of only 29%, with most injuries occurring in previously uninjured athletes. If effective interventions target only previously injured athletes, it would be withheld from the majority of athletes who could benefit. Consequently, we agree with Bahr,1 that all athletes receive effective interventions.nnnnFigure 1 nThe relationship between unilateral ACL injuries and ACL reinjuries in a multiseason prospective cohort study in female football and handball players.xa0(Based on original data from Krosshaug et al .2 nnnnBut consider another perspective on the same risk factor ‘previous injury’. Regardless of the low predictive value, previous injury is …

12 Reporting of acute programme variables in rehabilitation strength training for anterior cruciate ligament injury: a systematic review

Strength training is a critical component of rehabilitation for adults with anterior cruciate ligament (ACL) injury. Programming of acute programme variables (APV; e.g. sets, repetitions (reps), load, tempo, rest period (RP)) in rehabilitation strength training (RST) for ACL injury will impact physiological responses to training and resolution of impairments, activity limitations, and participation restrictions, as well as influence short-/long-term outcomes. Evidence-based practice (EBP) in RST for ACL injury depends on whether APVs are adequately reported in the scientific literature for readers to replicate interventions in day-to-day clinical practice. The purpose of this systematic review (SR) was to determine the extent to which RST APVs are reported in studies for adults with ACL injury. This SR was part of a wider SR registered on PROSPERO; PRISMA guidelines were followed. Medical (PubMed, MEDLINE), allied health (PEDro, CINHAL), and sports (Sport DISCUS) databases were comprehensively searched using pre-defined keywords. Descriptive, observational, and experimental studies that used RST with an external mass of known magnitude for adults with ACL injury were included from 2006–2016. Case-studies, elastic/hydraulic/pneumatic resistance studies, mixed-modality studies, and paediatric studies were excluded. A study needed to report an APV for ≥51% of all its RST exercises to be counted and included for that specific APV in this SR. Proportions (%) were then calculated: (number of studies with a specific APV reported total number of studies in SR) × 100. A total of 298 records were identified. After removal of duplicates, 139 records were screened and 19 were eligible for full-text review (FTR). After FTR, 13 studies were included for final quantitative synthesis. Of the 13 studies, 0%–85% reported specific APVs (e.g. sets 85%, reps 77%, load 39%, tempo 8%, RP 31%). Most studies reported sets and reps. Less than 40% of studies reported load, tempo, and RP, which threatens large variation in application of RST due to readers’ attempts to interpolate omitted APVs Translation and replication of recent ACL RST studies to clinical practice is limited because of inadequate reporting of APVs Future ACL RST studies should present detailed reports of APVs to facilitate better transfer of research to practice.

14 Reliability and measurement precision of right and left 1rm single-leg leg press, knee flexion, and knee extension strength tests in uninjured adult agility sport athletes: clinical implications of between-limb measurements in knee injury control

Knee muscle strength (MS) tests are important in the knee injury control process for agility sport (AS) athletes. Test reliability must be known or data are not valid and clinical decisions are compromised. Reliability of one repetition maximum (1RM) single-leg (SL) leg press (LP), knee flexion (KF) and knee extension (KE) strength tests has not been reported in a single cohort. Knowledge of test reliability for both limbs (R, L) is important in case reliability is substantially different between limbs. The aim of this study was to determine the reliability and standard error of measurement (SEM) of the 1RM SL LP, KF and KE tests for both limbs of uninjured AS athletes. It was hypothesised that tests would have good reliability and small SEM for both limbs. This was a between-day (D1/D2) repeated measures study: 13 athletes participated (male n=6; female n=7; age 25.6±5.5u2009y; height 171.4±8.4u2009cm; body mass (BM) 71.8±13.4u2009kg). Tests employed Cybex VR1 equipment. Test order was: LP, KF, KE. Limb order was randomised for D1, repeated D2. Tests followed typical 1RM procedures: warm-up set (1×10), then consecutive trials with incremental load increases at set percent BM (% BM); 1RM defined as the highest load (kg) moved through the required arc-of-motion. Raw data were normalised to% BM: (load moved BM) × 100. Normality of data, (Shapiro-Wilk), systematic error (paired t-test), relative reliability (intraclass correlation coefficient 2,1 (ICC 2,1)), and absolute reliability (SEM;% BM) were assessed. Bonferroni-corrected α was set a priori: 0.008. Mean ±SD D1/D2 differences were (% BM): LP R 4.3±11.3, L 1.9±20.9; KF R 3.0±7.0, L 0.5±2.8; KE R 1.3±5.1, L 3.1±6.5. All data were normally distributed (p≥0.07). There were no differences between D1/D2 values for any test (p≥0.11). The ICC 2,1 was: LP R 0.98, L 0.94; KF R 0.75, L 0.95; KE R 0.87, L 0.78. The SEM was (% BM): LP R 7.3, L 14.2; KF R 4.9, L 1.9; KE R 3.4, L 4.4. There was no systematic error. All tests demonstrated good reliability, although ICCs between limbs for 1RM KF were very different. All tests yielded small SEMs, although SEMs between limbs for 1RM LP and KF were also very different. Knee injury control studies that measure 1RM LP, KF and KE in AS athletes should be sure to determine test reliability and SEM in both limbs to avoid compromised clinical decision-making for either limb.

10 Sex differences in lower limb motor performance relevant to knee injury control

Female agility-sport (AS) athletes experience higher noncontact knee injury incidence than males. Lower limb motor performance (LLMP) can help inform about AS athletes’ knee injury risk. No study has compared normalised single-leg hop (SLH) and dynamic balance (SLDB) performance between sexes. The aim of this study was to compare normalised LLMP for both limbs between male and female AS athletes using the adapted crossover hop for distance (ACHD), single hop for distance (SHD), vertical hop (VH) and Y-balance (YB) tests. It was hypothesised that males would perform better than females across tests. Thirteen male (age 21.6±3.8u2009y; height 178.3±8.3u2009cm; mass 81.0±10.9u2009kg) and 10 female (age 25.7±5.9u2009y; height 165.1±5.7u2009cm; mass 63.9±6.5u2009kg) athletes participated. Test order considered skill demand and cumulative fatigue: ACHD (cm), SHD (cm), VH (cm), YB (cm). Limb order (R, L) was randomised. All tests have reported reliability. Practice trials preceded three measured trials. Normalisation (% leg length (LL)) was performed for all trials: (test distance LL (cm)) × 100. Mean of measured trials was used for analyses. Variables were normally distributed (Shapiro-Wilk, p>0.05). Two variables had unequal variance between sexes (Levene, p<0.05). Mann-Whitney U was used to assess between-sex differences. Bonferroni-corrected α was set a priori: 0.004. Male median values (%LL): ACHD R 719.4, L 691.7; SHD R 212.5, L 212.5; VH R 41.0, L 49.7; YB anterior (YBA) R 61.3, L 58.7; YB posteromedial (YBPM) R 117.1, L 114.0; YB posterolateral (YBPL) R 114.6, L 113.5. Female median values (%LL): ACHD R 522.4, L 533.5; SHD R 181.1, L 178.6; VH R 31.8, L 33.7; YBA R 61.0, L 60.4; YBPM R 108.9, L 109.8; YBPL R 106.8, L 108.5. There were between-sex differences for SHD (R p=0.004, L p=0.004) and VH (R p=0.003, L p=0.002), a trend for ACHD (R p=0.006, L p=0.018). There were no between-sex differences for YBA (R p=0.620, L p=0.457), YBPM (R p=0.041, L p=0.193) or YBPL (R p=0.145, L p=0.094). Males performed better than females on both limbs for most SLH tests with no between-sex differences for any YB direction on either limb. Consideration is warranted for between-sex differences in knee injury incidence involving LLMP characteristics contained in SLH rather than SLDB performance.

THE EFFECT OF FUNCTIONAL FATIGUE ON KNEE FORCE SENSE IN UNINJURED ADULT MALE FOOTBALL PLAYERS

Background Intact proprioception (joint position sense (JPS), kinaesthesia, force sense (FS)) is critical for optimal neuromuscular control of knee functional joint stability. Fatigue is known to impair knee JPS and kinaesthesia, but research regarding the effect of fatigue on knee FS is lacking. Objective To determine the effect of functional fatigue on knee extension FS in uninjured, adult, male football players. It was hypothesized that functional fatigue would result in significant impairment of FS. Design Single-session, pre-/post-intervention repeated measures. Setting University sensorimotor control and biomechanics laboratory. Participants University team players (n=21; age (mean±SD) 21.0±1.2 years; height 178.7±7.2u2005cm; mass 76.8±11.5u2005kg; training×2/week; match×1/week) without history of knee intra-articular derangement or surgery. Interventions Functional fatigue was defined/induced using the previously published Functional Agility Short-Term Fatigue Protocol (FAST-FP). The FAST-FP incorporated acceleration-deceleration tasks typical of football training/match play. Main Outcome Measures Dominant leg (preferred kicking leg) knee extension FS was measured in Newtons (N). Players were seated on an isokinetic dynamometer set to isometric mode, the knee flexed 45°. A knee extension target trial-reproduction trial sequence was repeated five times, the difference between trials designated the absolute error (AE), the average AE used for data analyses. Reliability and measurement error for this procedure has been previously established. Force sense measurements were performed before and immediately after the FAST-FP. The FS and FAST-FP procedures were adjacent in the same laboratory space with minimal transition time between tasks. Results Force sense AE significantly increased following fatigue (pre-fatigue=10.9±5.8 N; post-fatigue=23.0±9.2 N; difference=12.1±7.9 N; P=0.00; d=1.59). Conclusions Dominant leg knee extension FS was significantly impaired following functional fatigue. Fatigue-induced impairment of FS could result in sub-optimal neuromuscular control and altered knee functional joint stability that affects knee injury risk.

PRE-SEASON MOTOR PERFORMANCE RELEVANT TO KNEE INJURY CONTROL IN AN ENGLISH ADULT NETBALL CLUB: A DESCRIPTIVE STUDY

Noncontact knee injuries are common in netball and can result in major disability and socioeconomic burden. Different types of single-leg balance (SLB) and single-leg hop (SLH) test have been widely used in a variety of knee sports medicine contexts. Knowledge of SLB and SLH test performance can help inform the clinician regarding an athletes risk of knee injury. There is, however, a gap in the scientific literature regarding SLB and SLH test performance in adult netball players. Therefore, the purpose of this study was to describe pre-season performance of a battery of SLB and SLH tests considered clinically important in knee injury control in an English adult netball club. The Illinois Agility Test (IAT) was also performed to represent netball-related agility. After university ethics approval was obtained and informed consent completed, 23 female netball players participated (mean±standard deviation (SD): age 29±6u2005y; height 171.6±7.0u2005cm; mass 68.2±9.8u2005kg; defence n=10; centre n=2; attack n=11). All reported being uninjured, available for selection and registered for pre-season training. Test order was: barefoot eyes closed balance (ECB; sec), shod triple hop for distance (THD; cm), single hop for distance (SHD; cm) and vertical hop (VH; cm). Leg order was right (R), left (L). The IAT was conducted last. Practice trials and then three measured trials were performed. Appropriate between-trial rest periods were ensured. All tests have previously reported reliability. The mean of measured trials was used for descriptive statistics. All players successfully completed all tests. Mean±SD values were: ECB, R 22.5±15.8u2005s, L 29.6±15.5u2005s; THD, R 463.1±53.2u2005cm, L 464.6±38.7u2005cm; SHD, R 167.0±18.0u2005cm, L 166.4±15.7u2005cm; VH, R 20.0±3.7u2005cm, L 19.5±3.1u2005cm; IAT, 19.5±1.3u2005sec. Across all tests, mean data were comparable to mean data published by other research groups for females of similar age playing in other agility-focused team sports at similar levels of competition. Because the present data were comparable to data from other research groups, the present data were accepted and corroborated as a representation of the motor performances contained within each of the tests. The present and new data can, therefore, be used at several points during the knee injury control decision-making process for adult female netball players.