Clinical measurements of proprioception, muscle strength and laxity in relation to function in the ACL-injured knee

Influence of strength and balance ability on functional performance in the involved and uninvolved sides after anterior cruciate ligament reconstruction

BACKGROUND

The restoration and management of the uninvolved side have been emphasized to prevent a second anterior cruciate ligament (ACL) injury and to ensure that athletes return to sports after ACL reconstruction.

OBJECTIVE

To determine the factors influencing the single leg hop test (SLHT) and single leg vertical jump test (SLVJT) at 1 year postoperatively after ACL reconstruction in both the involved and uninvolved sides.

METHODS

Ninety-four patients who underwent ACL reconstruction were assessed at 1 year postoperatively. Multiple regression models included eight independent variables with two dependent variables (SLHT and SLVJT.), each on the involved and uninvolved side.

RESULTS

On the involved side, the Y balance test (YBT), extensor peak torque per body weight (PT/BW), Biodex balance system anteroposterior index (BBS-API), and sex accounted for 53.9% of the variance in SLHT (P= 0.002), and extensor PT/BW and YBT accounted for 26.3% of the variance in SLVJT (P= 0.027). On the uninvolved side, YBT, sex, age, BBS-API, and flexor PT/BW accounted for 47.0% of the variance in SLHT (P= 0.046), and flexor PT/BW, YBT, and age accounted for 44.9% of the variance in SLVJT (P= 0.002).

CONCLUSION

Knee extensor strength on the involved side and flexor strength on the uninvolved side influence the two functional performance tests. The YBT was an important factor in the two functional performance tests in both sides. Anteroposterior stability was the only factor that influenced the SLHT bilaterally.

Quadriceps strength, patellar tendon quality, relative load exposure, and knee symptoms in male athletes before the anterior cruciate ligament reconstruction

Introduction

Anterior cruciate ligament (ACL) injuries cause knee instability, knee pain, weight-bearing adjustments, and functional deficits but their association to patellar tendon quality is unknown. Our purpose was to investigate quadriceps strength, patellar tendon quality, relative load exposure, perceived knee stability, knee pain, extension angle, and time from ACL injury; in addition to examining their relative associations.

Methods

Injured and uninjured legs of 81 male athletes of different sports with a unilateral ACL injury (18-45 years) were examined. Participants reported location and intensity of knee pain and their perceived stability using a numerical rating scale (NRS 0-10). Strength was tested with an isokinetic device. Tendon quality was measured using ultrasound tissue characterization. Means ± standard deviation (SD) of perceived knee stability, knee extension angle, knee pain, isokinetic quadriceps strength in relation to body mass, proportion of echo-types (I-IV), tendon volume, and number of days from ACL injury to assessment are reported. Values of effect sizes (ES) and correlations (rs) were calculated.

Results

ACL injured leg demonstrated reduced reported knee stability (6.3 ± 2.5), decreased knee extension angle (-0.7 ± 3.1° vs. -2.7 ± 2.2°; ES = 0.7; P < 0.001), greater knee pain (NRS 3.1 ± 2.2 vs. 0.0 ± 0.1; ES = 2.0; P < 0.001), and 22% lower quadriceps strength (228.0 ± 65.0 vs. 291.2 ± 52.9 Nm/kg: ES = 1.2; P < 0.001) as compared to the uninjured leg. However, patellar tendons in both legs displayed similar quality. Quadriceps strength was associated with stability (rs = -0.54; P < 0.001), pain (rs = -0.47; P < 0.001), extension angle (rs = -0.39; P < 0.001), and relative load exposure (rs = -0.34; P < 0.004). Echo-types distribution was beneficially associated with time from ACL injury (rs range: -0.20/ -0.32; P < 0.05).

Discussion

ACL injured athletes displayed knee pain, extension deficit, and weaker quadriceps in the injured leg. While there were no differences in patellar tendon quality between legs, longer time from ACL injury showed better tendon quality.

The posterior cruciate ligament index as a reliable indirect sign of anterior cruciate ligament rupture is associated with the course of knee joint injury

PURPOSE

The objective of this study was to clarify the clinical value of the posterior cruciate ligament index (PCLI) in anterior cruciate ligament (ACL) rupture, to explore the relationship between the PCLI and course of disease, and to identify the influencing factors of the PCLI.

METHODS

The PCLI was defined a quotient of the X (the tibial and femoral PCL attachments) and the Y (the maximum perpendicular distance from X to the PCL). A total of 858 patients were enrolled in this case-control study, including 433 patients with ACL ruptures who were assigned to the experimental group and 425 patients with meniscal tears (MTs) who were allocated to the control group. Some patients in the experimental group have collateral ligament rupture (CLR). Information, such as the patient's age, sex, and course of disease, was recorded. All patients underwent magnetic resonance imaging (MRI) preoperatively, and the diagnosis was confirmed with the aid of arthroscopy. The PCLI and the depth of the lateral femoral notch sign (LFNS) were calculated based on the MRI findings, and the characteristics of the PCLI were explored.

RESULTS

The PCLI in the experimental group (5.1 ± 1.6) was significantly smaller than that in the control group (5.8 ± 1.6) (P < 0.05). The PCLI gradually decreased with time and was only 4.8 ± 1.4 in patients in the chronic phase (P < 0.05). This change was not due to the decrease in X but rather the increase in Y. The results also showed that the PCLI was not related to the depth of the LFNS or injuries of other structures in the knee joint. Furthermore, when the optimal cut-off point of the PCLI was 5.2 (area under the curve = 71%), the specificity and the sensitivity were 84% and 67%, respectively, but the Youden index was just 0.3 (P < 0.05).

CONCLUSION

The PCLI decreases due to the increase in Y instead of the decrease in X with time, especially in the chronic phase. The change in X in this process may be offset during imaging. In addition, there are fewer influencing factors that lead to changes in the PCLI. Therefore, it can be used as a reliable indirect sign of ACL rupture. However, it is difficult to quantify the diagnostic criteria of the PCLI in clinical practice. Thus, the PCLI as a reliable indirect sign of ACL rupture is associated with the course of knee joint injury, and it can be used to describe the instability of the knee joint.

LEVELS OF EVIDENCE

III.

Aquatic vs. land-based exercise after arthroscopic partial meniscectomy in middle-aged active patients with a degenerative meniscal tear: A randomized, controlled study

BACKGROUND

Awareness of the value of aquatic exercise (AE) in the postoperative rehabilitation has increased, and several inherent advantages of AE, such as adjustment of both resistance and muscle strengthening parameters makes good rationale for its inclusion in postoperative rehabilitation. This study aimed to determine and compare the benefits of AE and land-based exercise (LBE) on pain, functionality, and quality of life after arthroscopic partial meniscectomy (APM).

METHODS

This randomized controlled study included 30 middle-aged (35-50), physically active patients who were randomized into LBE (n = 15) and AE (n = 15) groups after APM for a degenerative meniscal tear. Visual analogue scale (VAS), Short Form-36 (SF-36), single-leg hop test and Lysholm questionnaire scores in addition to isokinetic muscle strength values were evaluated at baseline, at fourth week immediately after cessation of exercise program and at eighth week follow-up visits. The exercise sessions were conducted in 1-h sessions per day, three days a week for a total of four weeks.

RESULTS

Significant improvement was observed in the VAS, single-leg hop test, Lysholm questionnaire, and most of SF-36 subscale scores in both groups at both fourth and eighth follow-ups. Isokinetic dynamometer revealed significant improvement in the peak torque values for extension at angular velocities of 60° and 180° at both follow-ups in the AE group. LBE group showed significant improvement in the peak torque value for extension only at an angular velocity of 60° only at fourth week follow-up. There was no significant difference between groups for any of these parameters at any of the follow-ups.

CONCLUSION

Both AE and LBE programs had significantly improved pain, function, isokinetic muscle strength, and quality of life in patients after APM. Either type of exercise is essential as part of the rehabilitation protocol for good clinical outcomes after APM and should not be neglected (level II).

CLINICALTRIALS REGISTRATION NUMBER

NCT04925726.

Patellofemoral Angle, Pelvis Diameter, Foot Posture Index, and Single Leg Hop in Post-Operative ACL Reconstruction

Background and Objectives: Anterior cruciate ligament (ACL) injuries occur as a result of the deterioration of the static and dynamic stability of the knee. One of the structures involved in providing static stability is the patellofemoral angle (Q angle). The aim of this study was to investigate the relationships between Q angle, pelvis diameter, lower extremity length, and foot posture index (FPI) in patients who had undergone ACL reconstruction (ACLR) with the semitendinosus/gracilis (ST/G) technique on both the operated and non-operated sides. Materials and Methods: Twenty-five male recreational athletic patients between the ages of 18 and 35 who had undergone semitendinosus/gracilis (ST/G) anterior cruciate ligament reconstruction at least 6 months earlier were included in the study. Femur length, lower extremity length, pelvis diameter, and Q angle measurements, total foot posture index (FPI) scores, and single leg hop (SLH) and triple hop distance (THD) test results were determined on the operated and non-operated sides. Results: When the findings of the patients were evaluated statistically between the operated and non-operated sides, no significant differences were found in Q angle, femur length, and lower extremity length (p > 0.05). In terms of FPI scores, a significant difference was found only in the inversion/eversion of the calcaneus (CALC) parameter (p < 0.05). When the single hop test (SLHT) results were evaluated statistically on the operated and non-operated sides, the results were in favor of the non-operated side (p < 0.05). In the correlation analysis conducted for both the operated and non-operated sides, positive and significant correlations were found only between SLH and THD (p < 0.05). No significant difference was found in the other parameters. Conclusions: The fact that ST/G ACLR 6th month post-operative findings revealed similar results in Q angle, lower extremity length, and total FPI scores between the operated and non-operated sides showed that the 6-month process did not cause a difference in these parameters. However, it was found that the operated sides showed lower findings compared to non-operated sides for SLHTs, although these findings were within normal ranges in terms of the limb symmetry index.

Relationship between Locomotive Syndrome and Musculoskeletal Pain and Generalized Joint Laxity in Young Chinese Adults

This study aims to investigate the prevalence of locomotive syndrome (LS) and to examine the relationship of LS with musculoskeletal symptoms (pain, generalized joint laxity (GJL)) in young Chinese adults. Our study population (n = 157; mean age of 19.8 ± 1.2 years) comprises college student residents at Tsinghua University in Beijing, China. Three screening methods were used to evaluate LS: 25-question Geriatric Locomotive Function Scale (GLFS-25), a two-step test, and a stand-up test. Musculoskeletal pain was assessed by self-report and visual analog scale (VAS), and joint body laxity was evaluated using the GJL test. The prevalence of LS was 21.7% of all participants. Musculoskeletal pain affected 77.8% of the college students with LS and was strongly associated with LS. A total of 55.0% of college students with LS had four or more site joints that were positive for GJL, and higher scores of GJL were associated with a higher prevalence rate of LS. Young Chinese college students have a relatively high prevalence of LS, and musculoskeletal pain and GJL were significantly related to LS. The present results suggest that we need early screening of musculoskeletal symptoms and LS health education in young adults to prevent the mobility limitations of LS in the future.

Importance of Lower Extremity Muscle Performance and Knee Proprioception During First 60 Degrees of Knee Flexion at Three Months After Anterior Cruciate Ligament Reconstruction

Background: Knee proprioception and neuromuscular control may be important factors contributing to re-injury occurrences. Objectives: To examine lower extremity muscular performance and knee proprioception preoperatively and 3 months after anterior cruciate ligament (ACL) reconstruction. Methods: Twelve participants underwent ACL reconstruction using the hamstring tendon. All participants were assessed for knee proprioceptive sense using an isokinetic dynamometer at 15° and 60° of knee flexion. Lower extremity muscular performance was examined using the single-leg squat test (SLS) with two-dimensional motion analysis in frontal and sagittal planes. Results: Mean absolute error angle at a 15-degree-target angle was significantly lower at three months after ACL reconstruction compared with the preoperative state (P = 0.04). Maximal knee flexion angle of the injured The SLS test showed a lesser knee flexion angle of the injured knee at three months after ACL reconstruction (P = 0.01), and injured knee proprioception at 60 degree-flexion did not significantly improve at the three month-postoperative stage. Conclusions: At three months after ACL reconstruction by hamstring graft tendon, knee proprioceptive sense at an inner range of knee extension improved. However, proprioception at the middle range did not significantly develop. The range of hip and knee motions using SLS related to strength changes that the knee extensor needs to improve, especially in the middle range.

Properties of tests for knee joint threshold to detect passive motion following anterior cruciate ligament injury: a systematic review and meta-analysis

BACKGROUND

Threshold to detect passive motion (TTDPM) tests of the knee joint are commonly implemented among individuals with anterior cruciate ligament (ACL) injury to assess proprioceptive acuity. Their psychometric properties (PMPs), i.e. reliability, validity and responsiveness, are however unclear. This systematic review aimed to establish the PMPs of existing knee joint TTDPM tests among individuals with ACL injury.

METHODS

The databases PubMed, AMED, CINAHL, SPORTDiscus, Web of Science, Scopus, CENTRAL and ProQuest were searched to identify studies that assessed the properties of knee joint TTDPM tests in individuals with ACL injury. The risk of bias for each included study was assessed at the outcome level for each test. Overall quality and levels of evidence for each property were rated according to established criteria. Meta-analyses with mean differences were conducted using random-effects models when adequate data were available.

RESULTS

Fifty-one studies covering 108 TTDPM tests and 1632 individuals with unilateral ACL injury were included. A moderate-to-strong level of evidence indicated insufficient quality for all of the following: convergent validity, known-groups validity, discriminative validity, responsiveness between subgroups, and responsiveness to intervention. Subgroup meta-analyses for known-groups validity did however find that a starting angle of 15° resulted in significantly worse TTDPM for knees with ACL injury compared to those of asymptomatic persons (mean difference 0.28°; 95% CI 0.03 to 0.53; P = 0.03), albeit based on only three studies. Due to the lack of evidence, it was not possible to estimate the quality of reliability, measurement error, and criterion validity, nor responsiveness from a criterion and construct approach.

CONCLUSIONS

Among persons with ACL injury, existing tests of knee joint TTDPM lack either sufficient quality or evidence for their reliability, validity and responsiveness. Significantly worse thresholds for ACL-injured knees compared to those of asymptomatic controls from a 15° starting angle and trends towards significance for some validity measures nevertheless encourage the development of standardised tests. Further research investigating the influence of modifiable test components (e.g. starting angle and motion direction) on the PMPs of knee joint TTDPM tests following ACL injury is warranted.

Comparison of Shear Wave Elastography and Dynamometer Test in Muscle Tissue Characterization for Potential Medical and Sport Application

Skeletal muscle status and its dynamic follow up are of particular importance in the management of several diseases where weight and muscle mass loss and, consequently, immobilization occurs, as in cancer and its treatment, as well as in neurodegenerative disorders. But immobilization is not the direct result of body and muscle mass loss, but rather the loss of the maximal tension capabilities of the skeletal muscle. Therefore, the development of a non-invasive and real-time method which can measure muscle tension capabilities in immobile patients is highly anticipated. Our aim was to introduce and evaluate a special ultrasound measurement technique to estimate a maximal muscle tension characteristic which can be used in medicine and also in sports diagnostics. Therefore, we determined the relationship between the results of shear wave elastography measurements and the dynamometric data of individuals. The measurements were concluded on the m. vastus lateralis. Twelve healthy elite athletes took part in our preliminary proof of principle study—five endurance (S) and seven strength (F) athletes showing unambiguously different muscle composition features, nine healthy subjects (H) without prior sports background, and four cancer patients in treatment for a stage 3 brain tumor (T). Results showed a high correlation between the maximal dynamometric isometric torque (Mmax) and mean elasticity value (E) for the non-athletes [(H + T), (r = 0.795)] and for the athletes [(S + F), (r = 0.79)]. For the athletes (S + F), the rate of tension development at contraction (RTDk) and E correlation was also determined (r = 0.84, p < 0.05). Our measurements showed significantly greater E values for the strength athletes with fast muscle fiber dominance than endurance athletes with slow muscle fiber dominance (p < 0.05). Our findings suggest that shear wave ultrasound elastography is a promising method for estimating maximal muscle tension and, also, the human skeletal muscle fiber ratio. These results warrant further investigations with a larger number of individuals, both in medicine and in sports science.

Effect of Integrative Neuromuscular Training for Injury Prevention and Sports Performance of Female Badminton Players

Objectives

Investigate the effects of integrated neuromuscular training (INT) on injury prevention and the performance of professional female badminton athletes by comparing their preintervention and postintervention tests. The study hypothesized that integrated neuromuscular training can improve the asymmetry and improve the sport performance of female badminton players.

Methods

According to pretest value based on functional movement screening, 38 participants were divided into a high-risk group (HG) and a low-risk group (LG) with 22 and 16 people in each group. Two groups of athletes took part in an 8-week INT program consisting of four 90-min sessions each week. The asymmetries in movement, physical fitness, and special abilities were tested before and after the intervention. Independent sample t-test was used for the statistical analysis.

Results

This research found indicated that 8 weeks of INT influenced FMS scores in both groups (HG and LG). The change of inline lunge (ES_H = 0.42, ES_L = 0.21) and trunk stability push-up (ES_H = −0.58, ES_L = −0.20) showed significant differences (P < 0.05), and the change of the FMS scores (ES_H = 0.81, ES_L = 0.65), deep squat (ES_H = 0.6, ES_L = 0.3), and rotation stability (ES_H = −0.65, ES_L = −0.72) showed very significant differences (P < 0.01). Compared to the pretest, most of the physical fitness parameters improved significantly in the HG and LG groups except strength index, and special abilities of the HG and LG group women badminton athletes showed a substantial increase.

Conclusion

Integrated neuromuscular training can effectively improve the asymmetry of female badminton athletes' limbs, prevent sports injury, and improve the athlete's performance ability. However, athletes in different risk groups have certain differences in the degree of improvement in their motor skills.

No significant improvement in neuromuscular proprioception and increased reliance on visual compensation 6 months after ACL reconstruction

Purpose

To determine the contributions of proprioceptive and visual feedbacks for postural control at 6 months following ACLR, and to determine their associations with knee laxity, isokinetic tests and clinical scores.

Study design

Level IV, Case series.

Methods

Fifty volunteers who received ACLR between May 2015 and January 2017 were prospectively enrolled, and at 6 months following ACLR, postural stability was assessed. Somatosensory ratios (somatic proprioception), and visual ratios (visual compensation), were calculated to evaluate the use of sensory inputs for postural control. Univariable regression analyses were performed to determine associations of somatosensory and visual ratios with knee laxity, isokinetic tests and clinical scores.

Results

At 6 months following ACLR, the somatosensory ratio did not change, while the visual ratio decreased significantly from 5.73 ± 4.13 to 3.07 ± 1.96 (p = 0.002), indicating greater reliance on visual cues to maintain balance. Univariable analyses revealed that the somatosensory ratio was significantly lower for patients who performed aquatic therapy (β = -0.50; p = 0.045), but was not associated with knee laxity, muscle strength or clinical scores. An increased visual ratio was associated with patients who received hamstrings tendon autografts (β = 1.32; p = 0.049), but was not associated with knee laxity, muscle strength or clinical scores.

Conclusion

At 6 months following ACLR, visual ratios decreased significantly, while somatosensory ratios did not change. This may suggest that there is little or no improvement in neuromuscular proprioception and therefore greater reliance on visual cues to maintain balance. The clinical relevance of this study is that posturography can provide useful information to help research following ACLR and to predict successful return to play.

Effect of Different Knee Braces in ACL-Deficient Patients

Knee braces are often used during rehabilitation after ACL injury. There are two main concepts, rigid and soft braces, but studies comparing the two show conflicting results. Most studies used movement tasks with low translational or rotational loads and did not provide joint kinematics. Therefore, the purpose of this study was to investigate the influence of two different knee braces (rigid vs. soft) on knee joint kinematics in ACL-deficient patients compared to an unbraced control condition using two tasks (walking and 180° cutting) provoking knee movements in the frontal and transverse planes. 17 subjects with ACL-deficient knees participated in this study. 3D knee joint kinematics were recorded. To provoke frontal plane knee joint motion a laterally tilting plate was applied during a walking task. Both braces reduced the maximum valgus angle compared to the unbraced condition, stabilizing the knee joint against excessive valgus motion. Yet, no differences in peak abduction angle between the two braces were found. However, a significant extension deficit was observed with the rigid brace. Moreover, both braces increased transverse plane RoM and peak internal rotation angle, with the effects being significantly larger with the rigid brace. These effects have been associated with decreased knee stability and unphysiological cartilage loading. Therefore, the soft brace seems to be able to limit peak abduction with a lesser impact on physiological gait compared to the rigid brace. The cutting task was selected to provoke transverse plane knee movement and large external knee rotation was expected. However, none of the braces was able to reduce peak external knee rotation. Again, an increase in transverse plane RoM was observed with both braces. Based on these results, no brace outmatched the other in the second task. This study was the first attempt to clarify the effect of brace design for the stabilization of the knee joint during movements with frontal and transverse plane loading. However, to provide physicians and patients with a comprehensive guideline for brace usage, future studies will have to extent these findings to other daily or sportive movement tasks.

Evaluating Postoperative Muscle Strength Using Surface Electromyography in Hip Fracture Patient

Background

To compare the muscle strength of patients with a hip fracture according to the presence of sarcopenia after surgery and the correlation of measured values between a Biodex and surface electromyography (sEMG) in postoperative measurement of muscle strength.

Methods

Seventy-one patients who underwent hip fracture surgery were included in this study. Muscle mass was measured using dual energy X-ray absorptiometry and the grip strength was evaluated using a dynamometer. The diagnosis of sarcopenia followed the Asian Working Group for Sarcopenia criteria. We evaluated the Biodex to assess muscle strength according to the presence of sarcopenia and at the same time measured the sEMG to evaluate the correlation of muscle strength between Biodex and sEMG.

Results

We assigned 34 patients with sarcopenia and 37 without sarcopenia to 2 groups. In the comparison of muscle strength using Biodex and sEMG between the 2 groups, it was confirmed that muscle strength of sarcopenia group was decreased compared with that of the non-sarcopenia group, although there was no statistical significance between the groups. However, Biodex and sEMG showed very close correlation with muscle strength in all variables.

Conclusions

We suggest that using sEMG for the evaluation of muscle strength after hip fracture surgery may be an excellent tool alternative to isokinetic testing machines such as the Biodex.

Patient Characteristics and Predictors of Return to Sport at 12 Months After Anterior Cruciate Ligament Reconstruction: The Importance of Patient Age and Postoperative Rehabilitation

Background:

Preventing and mitigating the risk of reinjury after anterior cruciate ligament reconstruction (ACLR) rest on variables including age, surgical restoration of knee stability, adequate physical function, and thorough and complete postoperative rehabilitation, but to what degree these factors influence return to sport is unclear.

Purpose:

To investigate factors predictive of return to sport 12 months after ACLR. The factors specifically evaluated were strength, hop function, self-reported knee function, patient age, and quality of postoperative rehabilitation.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

This study evaluated 113 patients approximately 12 months after ACLR using a rehabilitation grading tool, the subjective International Knee Documentation Committee (IKDC) form, and a return-to-sport battery consisting of maximal isokinetic quadriceps and hamstring strength and 4 functional hop tests. Mann-Whitney U tests and chi-square analyses were used to determine differences between patients who had or had not returned to sport. A subsequent binary logistic hierarchical regression determined the factors predictive of a patient’s return to sport. In those patients who had returned to sport, relationships between either age or level of rehabilitation and passing the return-to-sport battery were also investigated.

Results:

Complete rehabilitation (adjusted odds ratio [OR], 7.95; P = .009), age ≤25 years (adjusted OR, 3.84; P = .024), and higher IKDC scores (P < .001) were predictive of return to sport at 12 months. In participants who had returned to sport, 21% passed the return-to-sport battery compared with only 5% who did not. Of those who had returned to sport, 37% who underwent complete rehabilitation passed the return-to-sport battery as opposed to 5% who underwent incomplete rehabilitation. In patients aged ≤25 years, only 48% underwent complete rehabilitation, despite having returned to sport. Additionally, in this group of patients, 40% underwent complete rehabilitation and passed the physical performance battery as opposed to only 4% who did not undergo complete rehabilitation.

Conclusion:

Younger patients and higher subjective IKDC scores were predictive of return to sport. Patients who completed 6 months of rehabilitation incorporating jumping and agility tasks had a higher rate of return to sport, suggesting that postoperative rehabilitation is important in predicting return to sport. Specialists and physical therapists alike should stress the importance of thorough postoperative rehabilitation and adequate neuromuscular strength and function to patients whose goals are to return to sport.

The Effects of Cryotherapy on Knee Joint Position Sense and Force Production Sense in Healthy Individuals

The proprioceptive information received from mechanoreceptors is potentially responsible for controlling the joint position and force differentiation. However, it is unknown whether cryotherapy influences this complex mechanism. Previously reported results are not universally conclusive and sometimes even contradictory. The main objective of this study was to investigate the impact of local cryotherapy on knee joint position sense (JPS) and force production sense (FPS). The study group consisted of 55 healthy participants (age: 21 ± 2 years, body height: 171.2 ± 9 cm, body mass: 63.3 ± 12 kg, BMI: 21.5 ± 2.6). Local cooling was achieved with the use of gel-packs cooled to -2 ± 2.5°C and applied simultaneously over the knee joint and the quadriceps femoris muscle for 20 minutes. JPS and FPS were evaluated using the Biodex System 4 Pro apparatus. Repeated measures analysis of variance (ANOVA) did not show any statistically significant changes of the JPS and FPS under application of cryotherapy for all analyzed variables: the JPS’s absolute error (p = 0.976), its relative error (p = 0.295), and its variable error (p = 0.489); the FPS’s absolute error (p = 0.688), its relative error (p = 0.193), and its variable error (p = 0.123). The results indicate that local cooling does not affect proprioceptive acuity of the healthy knee joint. They also suggest that local limited cooling before physical activity at low velocity did not present health or injury risk in this particular study group.

ACL status in arthroplasty patients, why not to preserve?

Introduction: Only 70–85% of patients that had total knee arthroplasty (TKA) are satisfied with their knees. The need for a near to normal knee kinematics is crucial and maybe the solution to their needs. Addressing the cruciate ligaments during surgery along with the extent of arthrosis may give a solution to this problem.

Material and methods: One hundred consecutive patients in whom a total knee arthroplasty was indicated and performed were prospectively documented. During the knee replacement surgery, the condition of the anterior and posterior cruciate ligaments and the degree of osteoarthritis (OA) in the medial and lateral compartments as well as in the patello-femoral joint were documented using the Outerbridge classification. The patients’ average age was 72.3 years, with the majority being female. In all patients, a total bi-compartmental knee replacement was indicated.

Results: Our results showed that in 78% of all patients the anterior, and in 98% the posterior cruciate ligament was still intact. Seventy-one percent of cases suffered from grade 4 medial osteoarthritis, 19% from grade 3 and 10% from grade 2. Thirty-six of patients suffered from grade 4 lateral osteoarthritis, 36% from grade 3, 24% from grade 2 and 4% from grade 1. Grade 4 patello-femoral osteoarthritis was present in 32% of all patients, grade 3 in 60% and grade 2 in 8% of all patients.

Discussion: The goal of arthroplasty is to approximate the function of a normal knee. The retention of the anterior cruciate ligament (ACL) allows for better knee, kinematics, improved proprioception, increased flexion and an overall improvement in knee function. The decreased constraint that is possible with retention of both cruciates may decrease implant stresses and improve the implant survivorship. The distribution of OA shows that the medial and patello-femoral compartments of the joint are primarily affected. This could also allow for a more conservative and patient-tailored prosthetic design.

Is ACL reconstruction a prerequisite for the patients having recreational sporting activities?

OBJECTIVE

Whether surgical or conservative treatment is more effective in allowing patients to return to physical activity after anterior cruciate ligament (ACL) injury is controversial. We sought to compare mid-term outcome measures between isolated ACL tear patients who underwent reconstruction followed by closed kinetic chain exercises and those who underwent neuromuscular training only.

METHODS

We retrospectively evaluated patients with ACL tears who underwent post-surgery CKC strength training after ACL reconstruction (Group A), and patients who only underwent neuromuscular training (Group B) with a minimum follow-up time of 5 years. Surgical techniques, rehabilitation, assessment of subjective knee function, one-leg hop test, assessment of joint position sense, muscle strength, and the health profile of the patient were evaluated.

RESULTS

Overall, 43 patients were included in Group A (mean age, 32.56 ± 4.89; Tegner activity scale, 5) and 39 patients in Group B (31.67 ± 7.27; 5). Patients in both groups returned to their regular physical activity level after a similar time frame (Group A: average, 12 months; Group B, average, 13.4 months). The mean Lysholm knee score was 88.52 ± 7.65 in Group A and 86.21 ± 13.72 in Group B. Mean distances for the one-leg hop test for Group A were 135.21 ± 31.66 and 145.36 ± 42.10 mm in the reconstructed and uninjured knees, respectively. In Group B, the mean hop distances were 132.47 ± 28.13 and 147.89 ± 21.45 mm in the rehabilitated and uninjured knees, respectively. No statistical difference was observed between the groups for any of the parameters evaluated, including assessment of subjective knee function, one-leg hop test, assessment of joint position sense, muscle strength, and the health profile.

CONCLUSION

Our data suggest that early surgical reconstruction may not be a prerequisite to returning to recreational physical activities after injury in patients with ACL tears.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Does gender make a difference in knee rotation proprioception and range of motion in healthy subjects?

BACKGROUND

Knee proprioception is an integral component of neuromuscular control system that stabilizes the joints, reducing incidence of injury. Knee injuries' incidences differ between genders. Knee rotation is a component of different knee injury mechanisms. Gender differences in knee proprioception in internal (IR) and external (ER) rotations are not sufficiently studied.

OBJECTIVE

To check whether proprioceptive acuity in IR and ER directions of knee rotation is inherently lower in women compared to men. Moreover, to assess gender difference in ranges of knee rotation.

METHODS

Thirty volunteers (15 women and 15 men) participated. Knee proprioception acuity and ranges of knee rotation were assessed using the knee rotatory kinesthetic device (KRKD). Proprioception was tested using absolute judgment task, subject's ability to discriminate different rotation movements (stimuli) randomly presented, then just notable difference (JND) was calculated; least difference accurately discriminated in 75% of trials.

RESULTS

Women had lower proprioception acuity in IR than men (1.70∘± 0.79∘ and 1.12∘± 0.32∘, p= 0.011) respectively. Active IR (women: 41.29∘± 7.46∘, men 32.80∘± 3.64∘, p= 0.000), and passive IR (women: 53.43∘±11.67∘, men: 37.94∘± 5.22∘, p= 0.000) were higher in women compared to men. Active ER (women: 49.71∘± 11.37∘, men: 39.16∘± 5.46∘, p= 0.003), and passive ER (women: 62.29∘± 13.74∘, men: 48.89∘± 7.09∘, p= 0.002) were, also, higher in women.

CONCLUSION

Gender difference in knee proprioception acuity was found in IR, which is the direction of rotation that anterior cruciate ligament (ACL) stabilize. Women's ranges of knee rotation are greater than men in both IR and ER.

Validation of Joint Position Sense of Dorsi-Plantar Flexion of Ankle Measurements Using a Smartphone

Objectives

This study evaluated and validated the reliability of smartphones as measuring equipment for the dorsi-plantar flexion of ankle joint position sense (JPS) ability.

Methods

The subjects were 20 healthy young students in their 20s. We confirmed the concurrent validity by comparison with existing electrogoniometer data. The reliability of the smartphone was confirmed using the test-retest method.

Results

In the case of dorsiflexion, there was no significant difference between the smartphone and electrogoniometer groups (p > 0.05). Regarding the correlation, it was significantly high (r = 0.65, p < 0.05), and ICC(3,1) was good (ICC(3,1) = 0.79). For the case of plantar flexion, there was no significant difference between the smartphone and electrogoniometer groups (p > 0.05), the correlation was significantly high (r = 0.69, p < 0.05), and the ICC(3,1) was very good (ICC(3,1) = 0.82). In the case of dorsiflexion, there was no significant difference between test and retest (p > 0.05), the correlation was intermediate (r = 0.59, p < 0.05), and the ICC(3,1) value was good (ICC(3,1) = 0.74). For plantar flexion, there was no significant difference between test and retest (p > 0.05), the correlation was significantly high (r = 0.63, p < 0.05), and the ICC(3,1) was good (ICC(3,1) = 0.76).

Conclusions

The results showed that smartphones provide high validity and reliability as measurement equipment for JPS of dorsi-plantar flexion of the ankle. Finally, the study also considers that smartphone-based JPS measuring methods may replace the traditional and expensive methods that are currently being used for the same purpose.

A statistically compiled test battery for feasible evaluation of knee function after rupture of the Anterior Cruciate Ligament - derived from long-term follow-up data

Purpose

Clinical test batteries for evaluation of knee function after injury to the Anterior Cruciate Ligament (ACL) should be valid and feasible, while reliably capturing the outcome of rehabilitation. There is currently a lack of consensus as to which of the many available assessment tools for knee function that should be included. The present aim was to use a statistical approach to investigate the contribution of frequently used tests to avoid redundancy, and filter them down to a proposed comprehensive and yet feasible test battery for long-term evaluation after ACL injury.

Methods

In total 48 outcome variables related to knee function, all potentially relevant for a long-term follow-up, were included from a cross-sectional study where 70 ACL-injured (17–28 years post injury) individuals were compared to 33 controls. Cluster analysis and logistic regression were used to group variables and identify an optimal test battery, from which a summarized estimator of knee function representing various functional aspects was derived.

Results

As expected, several variables were strongly correlated, and the variables also fell into logical clusters with higher within-correlation (max ρ = 0.61) than between clusters (max ρ = 0.19). An extracted test battery with just four variables assessing one-leg balance, isokinetic knee extension strength and hop performance (one-leg hop, side hop) were mathematically combined to an estimator of knee function, which acceptably classified ACL-injured individuals and controls. This estimator, derived from objective measures, correlated significantly with self-reported function, e.g. Lysholm score (ρ = 0.66; p<0.001).

Conclusions

The proposed test battery, based on a solid statistical approach, includes assessments which are all clinically feasible, while also covering complementary aspects of knee function. Similar test batteries could be determined for earlier phases of ACL rehabilitation or to enable longitudinal monitoring. Such developments, established on a well-grounded consensus of measurements, would facilitate comparisons of studies and enable evidence-based rehabilitation.

Association between sensory function and hop performance and self-reported outcomes in patients with anterior cruciate ligament injury

Background

In patients with anterior cruciate ligament (ACL) deficiency (ACLD) or reconstruction (ACLR), sensory deficits are commonly assessed as knee kinesthesia using time-consuming laboratory equipment. Portable equipment such as that used for evaluation of vibration sense would be preferable. In contrast to kinesthesia, vibration sense is not well studied in these patients.

Objectives

1) To study the association between kinesthesia and vibration sense to investigate if one sensory measurement can replace the other; and 2) to determine the clinical relevance by investigating associations between the sensory measurements and functional performance and patient-reported outcomes in patients with ACLD or ACLR.

Methods

Twenty patients with ACLD and 33 patients with ACLR were assessed with knee kinesthesia, vibration sense, the one-leg hop test for distance, as well as the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Tegner Activity Scale.

Results

There were no significant correlations between kinesthesia and vibration sense (r= −0.267, p>0.269) or between the sensory measures and hop performance (r= −0.351, p>0.199). In patients with ACLD, worse knee kinesthesia was associated with worse scores on KOOS subscales pain (r= −0.464, p=0.046) and activities of daily living (r= −0.491, p=0.033), and worse vibration sense was associated with worse scores on KOOS subscale quality of life (r= −0.469, p=0.037) and worse knee confidence (item Q3 from subscale quality of life) (r_s=0.436, p=0.054). In patients with ACLR, worse vibration sense was associated with worse scores on KOOS subscales pain (r= −0.402, p=0.020) and activities of daily living (r= −0.385, p=0.027).

Conclusion

Kinesthesia and vibration sense cannot be used interchangeably as measures of sensory function in patients with ACLD or ACLR. Both sensory measurements were weakly related to hop performance. Adequate sensory function appears to have importance for perceived function in patients with ACLD or ACLR and may therefore be a factor that needs to be addressed in rehabilitation programs for these patients.

Motion Task Selection for Kinematic Evaluation After Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To examine the different motion tasks and the protocols used to objectively quantify dynamic stability in terms of knee kinematics at different stages of anterior cruciate ligament reconstruction (ACLR) recovery.

METHODS

A systematic search was done using OVID in Embase, Cochrane Central Register of Controlled Trials, Medline, PsychINFO, and AMED. A combination of the following keywords and their variations were used: anterior cruciate ligament, motion tasks (e.g., jump, hop, gait), and stability. The inclusion criteria were as follows: (1) ACLR subjects were recruited, (2) at least 1 motion task was performed and kinematics data were recorded, and (3) uninjured subjects or the contralateral uninjured limbs were included as a control group. Exclusion criteria were as follows: (1) non-English language publications, (2) retrospective studies and review articles, (3) animal studies, and (4) cadaveric studies.

RESULTS

The search returned 2,195 studies, and 56 were included in this review according to the criteria. A total of 1,086 ACLR subjects were included. Pivoting, landing, walking, running, stair negotiation, and squats were assessed using optoelectronic motion capture, electrogoniometry, or video-radiography.

CONCLUSIONS

The appropriate selection of motion tasks is an integral factor in dynamic stability testing as it evokes different kinematic outcomes in relation to the different stages of ACLR recovery. Stair negotiation and landing tasks are best performed during the early stages of recovery, and landing and pivoting are recommended 6 months after ACLR surgery.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Mapping current research trends on neuromuscular risk factors of non-contact ACL injury

The aim of this systematic review was (i) to identify neuromuscular markers that have been predictive of a primary non-contact ACL injury, (ii) to assess whether proposed risk factors have been supported or refuted in the literature from cohort and case-control studies, and (iii) to reflect on the body of research that aims at developing field based tools to assess risk through an association with these risk factors. Electronic searches were undertaken, of PubMed, SCOPUS, Web of Science, CINAHL and SPORTDiscus examining neuromuscular risk factors associated with ACL injury published between January 1990 and July 2015. The evidence supporting neuromuscular risk factors of ACL injury is limited where only 4 prospective cohort studies were found. Three of which looked into muscular capacity and one looked into muscular activation patterns but none of the studies found strong evidence of how muscular capacity or muscular activation deficits are a risk factor for a primary non-contact ACL injury. A number of factors associated to neural control and muscular capacity have been suggested to be related to non-contact ACL injury risk but the level of evidence supporting these risk factors remains often elusive, leaving researchers and practitioners uncertain when developing evidence-based injury prevention programs.

Development of Manual Measurement System with Stereo Markers for Lachman Test

The objective of this paper is to develop a manual measurement system (MMS) for the Lachman test using stereo markers. A novel calculation method that is fit for stereo markers is proposed to analyze knee joint motion in real-time based on the extraction of markers attached on the femur and tibia. In our experiments, knee extension movement and tibial translation are performed with imitation bones to evaluate the accuracy of the system. Further, a simulation of the Lachman test is performed in vivo measurement. The mean error of the knee extension movement in ten cases (range 0° to 90°) was 0.41° with a standard deviation of 0.44°. The mean error of the tibial translation was approximately 0.3 ± 0.9 mm. Experimental results confirmed the acceptable performance of the proposed measurement system, which can be considered for application in clinical manual tests.

Neuroplasticity following anterior cruciate ligament injury: a framework for visual-motor training approaches in rehabilitation

SYNOPSIS

The neuroplastic effects of anterior cruciate ligament injury have recently become more evident, demonstrating underlying nervous system changes in addition to the expected mechanical alterations associated with injury. Interventions to mitigate these detrimental neuroplastic effects, along with the established biomechanical changes, need to be considered in the rehabilitation process and return-to-play progressions. This commentary establishes a link between dynamic movement mechanics, neurocognition, and visual processing regarding anterior cruciate ligament injury adaptations and injury risk. The proposed framework incorporates evidence from the disciplines of neuroscience, biomechanics, motor control, and psychology to support integrating neurocognitive and visual-motor approaches with traditional neuromuscular interventions during anterior cruciate ligament injury rehabilitation. Physical therapists, athletic trainers, strength coaches, and other health care and performance professionals can capitalize on this integration of sciences to utilize visual-training technologies and techniques to improve on already-established neuromuscular training methods.

LEVEL OF EVIDENCE

Therapy, level 5.

The effects of knee injury on skeletal muscle function, Na+, K+-ATPase content, and isoform abundance

While training upregulates skeletal muscle Na(+), K(+)-ATPase (NKA), the effects of knee injury and associated disuse on muscle NKA remain unknown. This was therefore investigated in six healthy young adults with a torn anterior cruciate ligament, (KI; four females, two males; age 25.0 ± 4.9 years; injury duration 15 ± 17 weeks; mean ± SD) and seven age- and BMI-matched asymptomatic controls (CON; five females, two males). Each participant underwent a vastus lateralis muscle biopsy, on both legs in KI and one leg in CON. Muscle was analyzed for muscle fiber type and cross-sectional area (CSA), NKA content ([(3)H]ouabain binding), and α1-3 and β1-2 isoform abundance. Participants also completed physical activity and knee function questionnaires (KI only); and underwent quadriceps peak isometric strength, thigh CSA and postural sway assessments in both injured and noninjured legs. NKA content was 20.1% lower in the knee-injured leg than the noninjured leg and 22.5% lower than CON. NKA α2 abundance was 63.0% lower in the knee-injured leg than the noninjured leg, with no differences in other NKA isoforms. Isometric strength and thigh CSA were 21.7% and 7.1% lower in the injured leg than the noninjured leg, respectively. In KI, postural sway did not differ between legs, but for two-legged standing was 43% higher than CON. Hence, muscle NKA content and α2 abundance were reduced in severe knee injury, which may contribute to impaired muscle function. Restoration of muscle NKA may be important in rehabilitation of muscle function after knee and other lower limb injury.

Association between sensory function and medio-lateral knee position during functional tasks in patients with anterior cruciate ligament injury

BACKGROUND

Patients with anterior cruciate ligament (ACL) injury often exhibit reduced movement quality during functional tasks in the form of a knee-medial-to-foot position (KMFP). This movement pattern is suggested to be more common in women than in men, but the possible contributing sensorimotor factors for this altered knee position are poorly studied in these patients. The aim of this study was to evaluate the association between sensory function and medio-lateral knee position during functional tasks in men and women with ACL injury.

METHODS

Fifty-one patients (23 women) aged 18-40 years with ACL injury were included in this cross-sectional study. Measures of sensory function were assessed by the threshold to detection of passive motion (TDPM) for knee kinesthesia and by the vibration perception threshold (VPT) for vibration sense. Movement quality was assessed by visual observation of the position of the knee relative to the foot during the following four functional tasks with different degrees of difficulty: the single-limb mini-squat, stair descending, the forward lunge, and the drop-jump. Spearman's rank correlation coefficient was used to determine the relationship between the sensory measures and the medio-lateral knee position during the functional tasks. Differences in TDPM and/or VPT between subjects with good and poor movement quality were evaluated using the independent t-test. Separate gender analyses were performed.

RESULTS

Worse TDPM was associated with a KMFP during the drop jump in men. Worse VPT at the toe and ankle was associated with a KMFP during stair descending and the forward lunge in women, but no associations were found in men.

CONCLUSION

Worse kinesthesia, measured by TDPM, might be associated with KMFP during the drop jump in men with ACL injury while worse vibration sense, measured by the VPT, at the foot and ankle might be related to KMFP in women. Further studies are needed to confirm these results.

The effects of cryotherapy on proprioception system

Proprioception plays an important role in the complex mechanism of joint control. Contemporary sport activities impose extremely high physical demands on athletes. Winter sports are played in areas with excessively low temperatures. Moreover, many athletes are subjected to treatments that involve local lowering of the body temperature before, during, and after physical activity. This work reviews the current knowledge regarding the influence of local cryotherapy on the proprioception system. The reviewed literature identified several tests that evaluate different aspects of proprioception. There is no universally agreed protocol, or clear set of criteria for test conditions. The outcomes of different tests and assessments of cryotherapy procedures using different cold modalities are poorly correlated. In general, the published results on the mechanism of cryotherapy effects on proprioception are not uniquely conclusive and are frequently contradictory. Additional high-quality research is required to explicitly answer the following questions: (1) whether local cryotherapy influences all aspects of proprioception; (2) whether the current methods of evaluation are adequate for the exploration of the relationship between cryotherapy and proprioception; and (3) whether the application of local cryotherapy is safe for athletes regarding proprioception. The review clearly showed that there is no comprehensive model relating cryotherapy and proprioception.

Genome-wide association study identifies genomic regions of association for cruciate ligament rupture in Newfoundland dogs

Cranial cruciate ligament rupture (CCLR) is the most common cause of pelvic limb lameness in dogs. To investigate the genetic basis of canine CCLR, we conducted a genome-wide association study using a canine SNP array in Newfoundland pedigree dogs with and without CCLR (n = 96). We identified three main chromosomal regions of CCLR association (on chromosomes 1, 3 and 33). Each of these regions was confirmed by Sequenom genotyping in a further cohort of Newfoundlands (n = 271). The results, particularly SNPs identified in the SORCS2 and SEMA5B genes, suggest that there may be neurological pathways involved in susceptibility to canine CCLR.

The immediate effects of open kinetic chain knee extensor exercise at different loads on knee anterior laxity in the uninjured

BACKGROUND

There is evidence that anterior laxity may be affected by knee extensor open kinetic chain (OKC) exercise with responses being load-dependent. The aim of this study is to evaluate the immediate and short-term changes in passive knee anterior laxity following a single session of OKC knee extensor exercise.

METHODS

Thirty two participants were randomly allocated to perform either high load (20 sets of 2 repetitions) or low load (2 sets of 20 repetitions) knee extensor OKC exercise with knee anterior laxity assessed before exercise, immediately after exercise and 45 and 90min after exercise with a KT-2000 arthrometer using a 133N force.

RESULTS

A significant effect of time was observed on knee laxity (p<0.001). However, a significant interaction of time and group was not found (p=0.54) and so the results presented here are for the combined (low and high load) group mean±standard deviation knee anterior laxity (mm) in the exercised leg: 7.2±2.2 (baseline), 8.2±2.3 (immediate post exercise, 14% change from baseline), 8.1±2.3 (45min post exercise, 12% change from baseline), and 7.7±2.2/0.29 (6.9) (90min post exercise, 7% change from baseline).

CONCLUSION

OKC knee extensor exercise at high loads and low loads causes an immediate increase in knee laxity that begins to decrease within 90min.

Robotic knee laxity testing: reliability and normative data

PURPOSE

To evaluate the reliability of the GeNouRoB knee arthrometer and present normative values of knee anterior laxity using this device on young females.

METHODS

Anterior laxity in both knees was tested in two groups of young, uninjured females using the hamstrings electromyography biofeedback feature of the device. There were 13 participants in the group tested for reliability and 23 for the normative study. Laxity (mm of movement of the proximal tibia in the anterior direction relative to the femur) was calculated at test forces of 134 N and 250 N with values presented for the unstandardised and standardised (relative to stabilisation force) conditions.

RESULTS

The relative reliability (95% limits of agreement) of the device for laxity at a test force of 134 N was 2 to 3mm. Left knee anterior laxity was almost 1mm greater than the right.

CONCLUSIONS

The relative reliability of the GeNouRoB arthrometer is comparable to the KT device. In agreement with previous work on the nonrobotic KT arthrometer, the knee anterior laxity values found with the GeNouRoB are greater in the left as compared to the right knee.

Enhanced proprioceptive acuity at the knee in the competitive athlete

STUDY DESIGN

Controlled laboratory study: cross-sectional.

OBJECTIVE

To determine if proprioception, measured by the threshold to detection of passive motion (TDPM), differed in individuals who regularly participate in moderate-intensity exercise for fitness as compared to individuals involved in high-intensity skilled exercise.

BACKGROUND

Previous research has been equivocal as to whether exercise training is associated with superior proprioceptive acuity, in particular, exercise that includes dynamic postural challenges such as cutting and pivoting.

METHODS

Two groups of 25 healthy individuals (18-32 years old) were recruited. One group consisted of individuals who performed moderate-activity level exercises for 5 to 10 hours per week. Participants in the other group performed high-activity level exercises, including high-speed cutting and pivoting activities, at least 10 hours per week. Proprioception was determined using TDPM, in which the knee was slowly extended or flexed at an angular velocity of 0.5°/s or less from a starting position of 40° of knee flexion.

RESULTS

Individuals participating in competitive, high-intensity skilled exercise demonstrated better acuity (average of both limbs) of TDPM (mean ± SD, 0.81° ± 0.38°; P<.001) than those participating in moderate-intensity exercise for fitness (1.53° ± 0.58°). A low but statistically significant association (r = -0.38, P = .006) was found between weekly duration of exercise and proprioceptive threshold as measured by TDPM.

CONCLUSION

These results suggest that perceptual thresholds of passive movement may be enhanced, depending on activity level and associated postural challenge, and that higher level and increased amount of exercise may promote enhanced neurosensory processing in these individuals. Consequently, high-intensity skilled training may deserve further emphasis in orthopaedic rehabilitation.

Barriers to predicting the mechanisms and risk factors of non-contact anterior cruciate ligament injury

High incidences of non-contact anterior cruciate ligament (ACL) injury, frequent requirements for ACL reconstruction, and limited understanding of ACL mechanics have engendered considerable interest in quantifying the ACL loading mechanisms. Although some progress has been made to better understand non-contact ACL injuries, information on how and why non-contact ACL injuries occur is still largely unavailable. In other words, research is yet to yield consensus on injury mechanisms and risk factors. Biomechanics, video analysis, and related study approaches have elucidated to some extent how ACL injuries occur. However, these approaches are limited because they provide estimates, rather than precise measurements of knee - and more specifically ACL - kinematics at the time of injury. These study approaches are also limited in their inability to simultaneously capture many of the contributing factors to injury.This paper aims at elucidating and summarizing the key challenges that confound our understanding in predicting the mechanisms and subsequently identifying risk factors of non-contact ACL injury. This work also appraise the methodological rigor of existing study approaches, review testing protocols employed in published studies, as well as presents a possible coupled approach to better understand injury mechanisms and risk factors of non-contact ACL injury. Three comprehensive electronic databases and hand search of journal papers, covering numerous full text published English articles were utilized to find studies on the association between ACL and injury mechanisms, ACL and risk factors, as well as, ACL and investigative approaches. This review unveils that new research modalities and/or coupled research methods are required to better understand how and why the ACL gets injured. Only by achieving a better understanding of ACL loading mechanisms and the associated contributing factors, one will be able to develop robust prevention strategies and exercise regimens to mitigate non-contact ACL injuries.

Proprioception of the wrist joint: a review of current concepts and possible implications on the rehabilitation of the wrist

STUDY DESIGN

Narrative review. Recent years have brought new research findings on the subject of wrist joint proprioception, which entails an understanding of the wrist as part of a sensorimotor system where afferent information from nerve endings in the wrist joint affects the neuromuscular control of the joint. An understanding of proprioception is also essential to adequately rehabilitate patients after wrist injuries. The aim of this narrative review was to give the reader a background of proprioception as it relates to neuromuscular control and joint stability, what is presently known in relation to the wrist joint and how these findings may be applied to the field of wrist rehabilitation.

LEVEL OF EVIDENCE

5.

Muscle strength quantification in small animals: a new transcutaneous technique in rabbits

The objective of this study was to develop a new, simple, and noninvasive technique to measure the force produced by dorsi-flexion of the foot in small animals. In addition, this study aimed to quantitatively describe changes in muscle and soft tissue structures using histomorphometry. The recovery of the dorsi-flexing muscles in the tibialis anterior compartment in New Zealand White rabbits was evaluated after musculoskeletal trauma by measuring isometric contractions after submaximal transcutaneous electrical stimulation of the peroneal nerve. The trauma included muscle and bone trauma that was treated with limb shortening followed by distraction osteogenesis. Muscle contractions were initiated at an amplitude of 5.1 mA for a duration of 2.56 ms at intervals of 50 ms. Based on consecutive measurements of the force on days 5, 10, 15, 20, 25, and 30 postsurgery, a positive trend in recovery of the stimulated force produced by dorsi-flexion of the foot was observed. The muscle strength at 30 days postsurgery was compared to that measured presurgery (baseline): 55% of the animals had dorsi-flexion strength that was 60% below that of the presurgery baseline muscle strength; 36% of the animals had dorsi-flexion strength that was greater than 60% of the baseline measure, indicating that there was a significant decrease in force produced by dorsi-flexion of the foot after trauma on all testing days (p < 0.01) and that a severe muscular injury was set with limited recovery. This technique provides a new option for examining muscle regeneration and rehabilitation in small animals.

Validation of a method to measure the proprioception of the knee

INTRODUCTION

Proprioception is an important mechanism in knee stability and function. After an injury like an anterior cruciate ligament (ACL) rupture changes appear in knee proprioception which play a major role in rehabilitation. There are several methods to measure proprioception; the threshold to detect passive motion (TTDPM) is often used to quantify proprioception. In this study the reliability and validity were tested of an apparatus, which measures the TTDPM based on the Lund technique of Fridén and Roberts (Sweden).

MATERIALS AND METHODS

Sixteen healthy participants were tested on both legs, from start position 20 degrees and 40 degrees, towards extension (TE) and flexion (TF). The same measurement was repeated 12 (6-21) days later.

RESULTS

An overall mean TTDPM of 0.58 degrees (95% confidence interval CI=0.53-0.62 degrees ) was found. Thresholds were different depending on direction of motion and start position. TTDPM in 20 degrees TE (0.51 degrees, CI=0.48-0.56 degrees) and in 40 degrees TF (0.54 degrees, CI=0.50-0.58 degrees ) were significantly lower than TTDPM in 40 degrees TE (0.68 degrees , CI=0.63-0.74 degrees) and in 20 degrees TF (0.58 degrees, CI=0.54-0.63 degrees). Thresholds were rising with age. Women had higher thresholds than men.

CONCLUSION

The method is a reliable and valid way to measure proprioception. The next step is to use this method on patients with an ACL-rupture and compare these results with healthy subjects.

Gender differences in passive knee biomechanical properties in tibial rotation

The anterior cruciate ligament (ACL) is the most commonly injured knee ligament with the highest incidence of injury in female athletes who participate in pivoting sports. Noncontact ACL injuries commonly occur with both internal and external tibial rotation. ACL impingement against the lateral wall of the intercondylar notch during tibial external rotation and abduction has been proposed as an injury mechanism, but few studies have evaluated in vivo gender-specific differences in laxity and stiffness in external and internal tibial rotations. The purpose of this study was to evaluate these differences. The knees of 10 male and 10 female healthy subjects were rotated between internal and external tibial rotation with the knee at 60 degrees of flexion. Joint laxity, stiffness, and energy loss were compared between male and female subjects. Women had higher laxity (p = 0.01), lower stiffness (p = 0.038), and higher energy loss (p = 0.008) in external tibial rotation than did men. The results suggest that women may be at greater risk of ACL injury resulting from impingement against the lateral wall of the intercondylar notch, which has been shown to be associated with external tibial rotation and abduction.

Reliability of the KT1000 arthrometer and the Lachman test in patients with an ACL rupture

The underlying study is a cross sectional study on the reliability of the KT1000 arthrometer and the Lachman test to determine the within-session inter-rater reliability and intra-rater reliability of the KT1000 arthrometer and the Lachman test. Twenty patients with a complete tear of the anterior cruciate ligament (ACL) were examined in a single session each. During the assessment, two physical therapists measured the anterior-posterior translation of the knee using both the KT1000 arthrometer and the Lachman test. One examiner performed a repeated measurement of each test for determination of intra-rater reliability. The examiners were blinded to the findings of their colleague. The intraclass correlation coefficient (ICC) was used to describe the degree of reliability of the measurements. High ICCs were found for the intra-rater reliability and the inter-rater reliability of the Lachman test (ICC=1.0 and 0.77). For the KT1000 arthrometer both ICCs were clearly lower (ICC=0.47 and 0.14). The KT1000 arthrometer shows inadequate reliabilities, even when measurements are repeated within a single measurement session. Contrastingly, the Lachman test is a reliable measurement to determine the anterior-posterior laxity of the ACL deficit knee. The results of the present study suggest good within-session intra-rater reliability as well as inter-rater reliability for the Lachman test.

Proprioceptive comparison of allograft and autograft anterior cruciate ligament reconstructions

The aim of this study is to search if there is any proprioceptive difference between auto and allograft anterior cruciate ligament (ACL) reconstructions, and also to determine if there is any relationship between instrumented anterior knee laxity and proprioception after an ACL reconstruction. The following four groups were constituted for this purpose: group I, control group; group II, autograft reconstructions; group III, allograft reconstructions and group IV, people with injured ACLs. Each group consisted of 20 patients/volunteers. Two subgroups were constituted according to the findings of KT-1,000 laxity testing in group II and III; patients/volunteers found to have a laxity of 3 mm or less were enrolled in the normal subgroup and those with a laxity of more than 3 mm were enrolled in the lax subgroup. Two proprioceptive tests were used: threshold to detect passive motion (TDPM) and joint position sense (JPS) by using Cybex Norm dynamometer. Patients underwent ten tests and the discrepancy in degrees was averaged for ten trials. Comparisons were made to evaluate the proprioceptive differences between groups/subgroups; ANOVA and t test was used for comparisons where appropriate, and the significance was set at P < 0.05. There was a significant difference in degrees between patients with injured ACLs and the other three groups in TDPM evaluations (injured: 1.93 degrees vs. control: 1.03 degrees , autograft: 1.01 degrees , allograft: 0.96 degrees ; P < 0.001). Auto and allograft reconstructions were not different from each other and controls. Allo and autograft ACL reconstructions are not different from each other according to proprioceptive measurements. Also, proprioception is not correlated to postoperative anterior knee laxity; many variables involve joint proprioception and mostly the anterior knee laxity may not be the sole determining element, and a lax ACL still may fulfill some of its afferent arc functions as long as it bridges the femur and tibia.

Test-retest reliability of knee kinesthesia in healthy adults

Background

Sensory information from mechanoreceptors in the skin, muscles, tendons, and joint structures plays an important role in joint stability. A joint injury can lead to disruption of the sensory system, which can be measured by proprioceptive acuity. When evaluating proprioception, assessment tools need to be reliable. The aim of this study was to assess the test-retest reliability of a device designed to measure knee proprioception.

Methods

Twenty-four uninjured individuals (14 women and 10 men) were examined with regard to test-retest reliability of knee kinesthesia, measured by the threshold to detection of passive motion (TDPM). Measurements were performed towards extension and flexion from the two starting positions, 20 degrees and 40 degrees knee joint flexion, giving four variables. The mean difference between test and retest together with the 95% confidence interval (test 2 minus test 1), the intraclass correlation coefficient (ICC_2,1), and Bland and Altman graphs with limits of agreement, were used as statistical methods for assessing test-retest reliability.

Results

The intraclass correlation coefficients ranged from 0.59 to 0.70 in all variables except one. No difference was found between test and retest in three of the four TDPM variables. TDPM would need to decrease between 10% and 38%, and increase between 17% and 24% in groups of uninjured subjects to be 95% confident of detecting a real change. The limits of agreement were rather wide in all variables. The variables associated with the 20-degree starting position tended to have higher intraclass correlation coefficients and narrower limits of agreement than those associated with 40 degrees.

Conclusion

Three TDPM variables were considered reliable for observing change in groups of subjects without pathology. However, the limits of agreement revealed that small changes in an individual's performance cannot be detected. The higher intraclass correlation coefficients and the narrower limits of agreement in the variables associated with the starting position of 20 degrees knee joint flexion, indicate that these variables are more reliable than those associated with 40 degrees. We, therefore, recommend that the TDPM be measured with a 20-degree starting position.