Mechanoreceptors of the ligaments and tendons around the knee

Chronic lateral ankle instability using anterior tibiofibular ligament distal fascicle transfer augmentation repair: an anatomical, biomechanical, and histological study

Background: The transfer of the anterior tibiofibular ligament distal fascicle (ATiFL-DF) for the augmentation repair of the anterior talofibular ligament (ATFL) shows potential as a surgical technique. However, evidences on the benefits and disadvantages of this method in relation to ankle joint function are lacking. Purpose: This study aimed to provide comprehensive experimental data to validate the feasibility of ATiFL-DF transfer augmentation repair of the ATFL. Methods: This study included 50 embalmed ankle specimens to measure various morphological features, such as length, width, thickness, and angle, for evaluating similarities between the ATiFL-DF and ATFL. Furthermore, 24 fresh-frozen ankle specimens were examined for biomechanical testing of the ATiFL-DF transfer augmented repair of the ATFL. Finally, 12 pairs of ATiFL-DF and ATFL tissues from fresh-frozen ankle specimens were treated with gold chloride staining to analyze mechanoreceptor densities. Results: Anatomical studies found that the lengths and thicknesses of the ATFL and ATiFL-DF are similar. Biomechanical outcomes showed that performing ATiFL-DF transfer for ATFL repair can improve the stability of the talus and ankle joints. This is evident from the results of the anterior drawer, axial load, and ultimate failure load tests. However, performing ATiFL-DF transfer may compromise the stability of the distal tibiofibular joint, based on the Cotton and axial load tests at an external rotation of 5°. Analysis of the histological findings revealed that mechanoreceptor densities for four types of mechanoreceptors were comparable between the ATiFL-DF and ATFL groups. Conclusion: ATiFL-DF transfer is a viable method for augmenting ATFL repair. This technique helps to improve the stability of the talus and ankle joints while compensating for proprioception loss. Although ATiFL-DF transfer augmented repair of the ATFL may negatively affect the stability of the distal tibiofibular joint, this procedure can enhance the stability of the talus and ankle joints.

Corticomuscular cross-recurrence analysis reveals between-limb differences in motor control among individuals with ACL reconstruction

Surgical reconstruction of the anterior cruciate ligament (ACL) and subsequent physical therapy can help athletes return to competition; however, re-injury rates remain disproportionately high due, in part, to lingering biomechanical and neurological factors that are not fully addressed during rehabilitation. Prior reports indicate that individuals exhibit altered electrical activity in both brain and muscle after ACL reconstruction (ACLR). In this investigation, we aimed to extend existing approaches by introducing a novel non-linear analysis of corticomuscular dynamics, which does not assume oscillatory coupling between brain and muscle: Corticomuscular cross-recurrence analysis (CM-cRQA). Our findings indicate that corticomuscular dynamics vary significantly between involved (injured) and uninvolved legs of participants with ACLR during voluntary isometric contractions between the brain and both the vastus medialis and lateralis. This finding points to a potential lingering neural deficit underlying re-injury for athletes after surgical reconstruction, namely the dynamical structure of neuromuscular (brain to quad muscle) coordination, which is significantly asymmetric, between limbs, in those who have ACLR.

Microstructural analysis on the innervation of the anterior, medial, and lateral human hip capsule: Preliminary evidence on its neuromechanical contribution

OBJECTIVE

Capsular repair aims to minimize damage to the hip joint capsular complex (HJCC) and subsequent dislocation risk following total hip arthroplasty (THA). Numerous explanations for its success have been advocated, including neuromuscular feedback loops originating from within the intact HJCC. This research investigates the hypothesis that the HJCC contributes to hip joint stability by analyzing HJCC innervation.

METHOD

Twenty-nine samples from the anterior, medial, and lateral aspects of the midportion HJCC of 29 individuals were investigated stereologically and immunohistochemically to identify encapsulated mechanoreceptors according to a modified Freeman and Wyke classification, totaling 11,745 sections. Consecutive slices were observed to determine the nerve course within the HJCC.

RESULTS

Few encapsulated mechanoreceptors were found in the HJCC subregions and overlying tissues across the cohort studied. Of regions studied, no significant regional differences in the density of mechanoreceptors were found. No significant difference in mechanoreceptor density was found between sides (left, 10.2×10-4/mm3, 4.0×10-4 - 19.0×10-4/mm3; right 12.9×10-4/mm3, 5.0×10-4 - 22.0×10-4/mm3; mean, 95% confidence intervals) sexes (female 10.4×10-4/mm3, 4.0×10-4 - 18.0×10-4/mm3; male 11.6×10-4/mm3, 5.0×10-4 - 20.0×10-4/mm3; mean, 95% confidence intervals), nor in correlation with age demographics. Myelinated nerves coursed consistently within the HJCC in various orientations.

CONCLUSION

Sparse mechanoreceptor density suggests that the HJCC contributes to a limited extent to hip joint stabilization. HJCC nerve terminals may potentially contribute to neuromuscular feedback loops with associated muscles to mediate joint stability in tandem with the active and passive components of the joint.

Isolated medial patellofemoral ligament reconstruction improves static bipedal balance control in young patients with recurrent lateral patellar instability

BACKGROUND

Knee stability can be safely and reliably restored using medial patellofemoral ligament (MPFL) reconstruction, which is widely recognized in patients with recurrent lateral patellar instability. However, the literature regarding its influence on static balance control is limited. Thus, this study aimed to assess the impact of MPFL reconstruction on balance control and determine its functional significance.

METHODS

The study comprised 26 patients with recurrent lateral patellar instability, scheduled for MPFL reconstruction, and 26 matched healthy controls who underwent double-leg stance static posturographic tests pre- and postoperatively on a vertical force platform. Four test conditions were performed with their eyes open and closed, without and with foam support to evaluate the balance control of all participants. The International Knee Documentation Committee subjective knee form, Lysholm knee scoring scale, Tampa scale for kinesiophobia, and active range of motion of the affected knee were synchronously obtained and assessed.

RESULTS

More postural sway was observed in patients compared to the healthy controls, 11 ± 5 days preoperatively (p < 0.01). However, 374 ± 23 days postoperatively, postural sway between the patients and control subjects was comparable (p > 0.05). Patients following MPFL reconstruction demonstrated better postural stability (p < 0.01). Significant ameliorations were found in all clinical assessments in the study patients postoperatively (p < 0.01).

CONCLUSIONS

Patients with recurrent lateral patellar instability have inefficient balance control. Static bipedal balance control can be improved under surface perturbation in these patients one year after isolated MPFL reconstruction that enhances the possibility of normal restoration of postural stability. Structural recovery of the ligament could help restore the sensorimotor efficiency and generate the compensatory and anticipatory balance regulation strategies, thereby improving joint function.

Relationship Between Mechanoreceptors in the Posterior Cruciate Ligament and Patient Age or Osteoarthritis Severity

Background

Mechanoreceptors in the posterior cruciate ligament (PCL) can produce proprioception, which is an important reason why patients choose cruciate-retaining total knee arthroplasty (TKA). The number of mechanoreceptors in the PCL of patients with knee osteoarthritis (OA) is unknown.

Purpose

To provide a theoretical basis for estimating the number of mechanoreceptors in the PCL by evaluating the relationship between this number and patient age or OA severity.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

An overall 28 PCLs from patients with knee OA were collected at the time of TKA and grouped according to patient age (group A, 60-69 years [n = 8]; group B, 70-79 years [n = 12]; group C, ≥80 years [n = 8]) and OA based on Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (group I, ≤80 [n = 8]; group II, 81-120 [n = 10]; group III, >120 [n = 10]). Hematoxylin and eosin and S-100 immunohistochemical staining were performed on the slices near the tibial attachment of the PCL, and the number of mechanoreceptors in each slice was counted. Multifactor analysis of variance was used to evaluate the relationship between the number of mechanoreceptors and patient age or WOMAC score.

Results

The number of mechanoreceptors (mean ± SD) in groups A, B, and C was 24.00 ± 15.19, 30.92 ± 11.41, and 23.38 ± 11.39, respectively, with no significant between-group differences. The number of mechanoreceptors in groups I, II, and III was 43.50 ± 4.99, 25.00 ± 5.27, and 15.20 ± 5.61, with significant differences between groups I and II, groups I and III, and groups II and III (P < .001 for all).

Conclusion

In patients with knee OA, age had no significant effect on mechanoreceptor count, but the number of mechanoreceptors in the PCL decreased significantly with higher (worse) WOMAC score. These findings suggest that in patients of any age with high WOMAC scores, there may be little value as it relates to knee proprioception in performing a PCL-retaining TKA.

Sensory-motor training versus resistance training in the treatment of knee osteoarthritis: A randomized controlled trial

OBJECTIVE

To compare the effectiveness of sensory-motor training and resistance training in patients with knee osteoarthritis.

DESIGN

Randomized controlled trial.

SETTING

Istanbul University, Department of Physiotherapy and Rehabilitation.

SUBJECTS

Forty-eight participants with knee osteoarthritis.

INTERVENTIONS

Following baseline assessment, participants were randomly allocated to sensory-motor training (n  =  24) and resistance training (n = 24). Both groups received training three times a week for 8 weeks.

MAIN MEASURES

The primary outcome measure was the Western Ontario and McMaster Universities Arthritis Index (WOMAC). The secondary outcome measures were pain level, muscle strength, proprioception, range of motion, quality of life, and patient satisfaction with treatment. Patients were assessed before and after four- and eight-week interventions.

RESULTS

There was no significant difference between the groups' total WOMAC scores after four- and eight-week interventions (respectively, p = 0.415, p = 0.828). There was a significant improvement in pain level during movement and in the energy subscale SF-36 for resistance training after the four-week intervention (respectively, p = 0.012, p = 0.007). After the eight-week intervention, a significant difference was noted in favor of resistance training in the secondary outcome measure quality of life (QoL). No significant difference was found in other secondary outcomes.

CONCLUSIONS

At the end of the treatment, it was observed that sensory-motor training had a similar effect in the treatment of knee osteoarthritis symptoms to resistance training. These findings may suggest that sensory-motor training is an effective new method to treat patients with knee osteoarthritis.

Inhibition of knee joint sensory afferents alters covariation across strides between quadriceps muscles during locomotion

Sport-related injuries to articular structures often alter the sensory information conveyed by joint structures to the nervous system. However, the role of joint sensory afferents in motor control is still unclear. Here, we evaluate the role of knee joint sensory afferents in the control of quadriceps muscles, hypothesizing that such sensory information modulates control strategies that limit patellofemoreal joint loading. We compared locomotor kinematics and muscle activity before and after inhibition of knee sensory afferents by injection of lidocaine into the knee capsule of rats. We evaluated whether this inhibition reduced the strength of correlation between the activity of vastus medialis (VM) and vastus lateralis (VL) both across strides and within each stride, coordination patterns that limit net mediolateral patellofemoral forces. We also evaluated whether this inhibition altered correlations among the other quadriceps muscle activity, the time-profiles of individual EMG envelopes, or movement kinematics. Neither the EMG envelopes nor limb kinematics was affected by the inhibition of knee sensory afferents. This perturbation also did not affect the correlations between VM and VL, suggesting that the regulation of patellofemoral joint loading is mediated by different mechanisms. However, inhibition of knee sensory afferents caused a significant reduction in the correlation between vastus intermedius (VI) and both VM and VL across, but not within, strides. Knee joint sensory afferents may therefore modulate the coordination between the vasti muscles but only at coarse time scales. Injuries compromising joint afferents might result in altered muscle coordination, potentially leading to persistent internal joint stresses and strains.NEW & NOTEWORTHY Sensory afferents originating from knee joint receptors provide the nervous system with information about the internal state of the joint. In this study, we show that these sensory signals are used to modulate the covariations among the activity of a subset of vasti muscles across strides of locomotion. Sport-related injuries that damage joint receptors may therefore compromise these mechanisms of muscle coordination, potentially leading to persistent internal joint stresses and strains.

Test-Retest Reliability of a Passive Joint Position Sense Test After ACL Reconstruction: Influence of Direction, Target Angle, Limb, and Outcome Measures

Background:

The joint position sense (JPS) is an element of proprioception and defined as an individual’s ability to recognize joint position in space. The JPS is assessed by measuring the acuity of reproducing a predetermined target angle. The quality of psychometric properties of knee JPS tests after anterior cruciate ligament reconstruction (ACLR) is uncertain.

Purpose/Hypothesis:

The purpose of this study was to evaluate the test-retest reliability of a passive knee JPS test in patients who underwent ACLR. We hypothesized that the passive JPS test would produce reliable absolute error, constant error, and variable error estimates after ACLR.

Study Design:

Descriptive laboratory study.

Methods:

Nineteen male participants (mean age, 26.3 ± 4.4 years) who had undergone unilateral ACLR within the previous 12 months completed 2 sessions of bilateral passive knee JPS evaluation. JPS testing was conducted in both the flexion (starting angle, 0°) and the extension (starting angle, 90°) directions in the sitting position. The absolute error, constant error, and variable error of the JPS test in both directions were calculated at 2 target angles (30° and 60° of flexion) by using the angle reproduction method for the ipsilateral knee. The standard error of measurement (SEM), smallest real difference (SRD), and intraclass correlation coefficients (ICCs) with 95% Cis were calculated.

Results:

ICCs were higher for the JPS constant error (operated and nonoperated knee, 0.43-0.86 and 0.32-0.91, respectively) compared with the absolute error (0.18-0.59 and 0.09-0.86, respectively) and the variable error (0.07-0.63 and 0.09-0.73, respectively). The constant error of the 90°-60° extension test showed moderate to excellent reliability for the operated knee (ICC, 0.86 [95% CI, 0.64-0.94]; SEM, 1.63°; SRD, 4.53°), and good to excellent reliability for the nonoperated knee (ICC, 0.91 [95% CI, 0.76-0.96]; SEM, 1.53°; SRD, 4.24°).

Conclusion:

The test-retest reliability of the passive knee JPS tests after ACLR varied depending on the test angle, direction, and outcome measure (absolute error, constant error, or variable error). The constant error appeared to be a more reliable outcome measure than the absolute error and the variable error, mainly during the 90°-60° extension test.

Clinical Relevance:

As constant errors have been found reliable during the 90°-60° extension test, investigating these errors—in addition to absolute and variable errors—to reflect bias in passive JPS scores after ACLR is warranted.

Study of the nerve endings and mechanoreceptors of the medial meniscotibial ligament of the knee: A structural and distribution analysis

BACKGROUND

The aim of the present study is to describe the morphology and distribution of the nerve endings of the meniscotibial ligament (MTL) of the knee, in order to understand the interaction between the proprioceptive system and knee mechanics.

METHODS

Twenty medial MTLs were obtained from deceased organ donors. The ligaments were measured, weighed and cut. Sections (10 mm) were prepared on hematoxylin and eosin-stained slides for analysis of tissue integrity, and 50 mm sections were submitted to immunofluorescence with the protein gene product (PGP) 9.5 as primary antibody and Alexa Fluor 488 as secondary antibody, followed by microscopic analysis.

RESULTS

The medial MTL was identified in 100% of the dissections, with average length, width, thickness and weight of 7.07 ± 1.34 mm, 32.25 ± 3.09 mm, 3.53 ± 0.27 mm and 0.67 ± 0.13 g, respectively. The hematoxylin and eosin-stained histological sections exhibited typical ligament structure, with dense well-organized collagen fibers and vascular tissue. All the specimens analyzed contained type I (Ruffini) mechanoreceptors and free (type IV) nerve endings, varying from parallel to intertwined fibers. Nerve endings not classified with different irregular shapes were also found. Most type I mechanoreceptors were found close to the MTL insertions on the tibial plateau, while the free nerve endings were found adjacent to the capsule.

CONCLUSION

The medial MTL showed a peripheral nerve structure, primarily type I and IV mechanoreceptors. These findings suggest that the medial MTL is important for proprioception and medial knee stabilization.

Effect of dog-related parameters on the flexion test outcome: A large cohort retrospective study on physiological and orthopedic pathological-related factors

Objectives

This retrospective study evaluates the dog-related factors of variation influencing the outcome of the flexion test (FT), when performed to localize pain to a joint area, on a large group of canine orthopedic patients.

Materials and methods

The selection criteria for this retrospective study were dogs undergoing a FT in a referral orthopedic clinic between 2009 and 2020 with a complete medical record. The canine FT, described in a previously published protocol, was performed on dogs presented with an orthopedic problem. In summary, a dog's joint, identified as suspected of an orthopedic problem according to the clinical examination, was flexed for 1 min before walking 15 m on a hard and even surface. The FT was considered positive if the lameness increased after the application of the FT and negative when it remained unchanged. Statistical analysis was performed to determine which of the following criteria could influence the outcome of the flexion test: age, gender, neutered status, weight category, tested joint and initial lameness score.

Results

Over 1,161 patients' files were collected and analyzed for this research. The FT showed 82.8% (95%IC: 80.5-84.9) of true positives and 17.2% of false negatives. None of the patient's intrinsic characteristics influenced the outcome of the test (age, gender, neutered status, and weight category). The orthopedic parameters, such as the initial lameness score and the tested joint, showed to have a statistically significant influence on the outcome of the test.

Clinical relevance

The FT is an easy-to-perform technique presenting reliable results on most joints. This test presents an interest when performed in addition to a complete orthopedic examination to localize pain to a joint area. Only the orthopedic pathological-related parameters such as the lameness score and the tested joint seem to influence the outcome of the FT. The FT is not influenced by the physiological-related characteristic of the patient (age, weight category, sex, and neutered status).

Clinical application of modified Crain classification in the Design of Anterior Cruciate Ligament Reconstruction with remnant preservation

BACKGROUND

To investigate the clinical application of modified Crain classification in anterior cruciate ligament (ACL) reconstruction (ACLR) with remnant preservation.

METHODS

The subjects were 70 patients with ACL injury who underwent ACLR from May 2016 to June 2018, and their general data were recorded. They were randomly divided into modified remnant-preserved ACLR group (group M, n = 35) and non remnant-preserved ACLR group (group N, n = 35). ACLR program with remnant preservation was designed based on modified Crain classification in group M, while ACL remnants were completely cleaned during ACLR in group N. Subsequently, the two groups were compared in terms of operation time, complications, as well as Lysholm score, international knee documentation committee (IKDC) score and positive rate of Lachman test of knee joint before operation and at 3, 6 and 12 months after operation.

RESULTS

Both the groups showed good postoperative efficacy, and none had complications like limited knee extension or cyclops lesion. The comparison results found that group M (72.49 ± 7.64 min) required longer operation time than group N (66.06 ± 6.37 min) (P < 0.05). Lysholm score and IKDC score at 3, 6 and 12 months after operation in the two groups were significantly higher than those before operation (P < 0.05); group M had higher Lysholm score and IKDC score at 3 months and 6 months after operation compared with group N (P < 0.05). Additionally, the positive rate of Lachman test at 3, 6 and 12 months after operation in both groups was significantly lower than that before operation (P < 0.05), but there was no significant difference between group M and group N.

CONCLUSION

With the modified Crain classification, many remnant-preserved reconstruction techniques can be rationally used to completely preserve the remnant ligament tissue during operation and improve knee joint function and joint stability with few complications.

Guided-Motion Bicruciate-Stabilized Total Knee Arthroplasty Reproduces Native Medial Collateral Ligament Strain

Background and Objectives: Guided-motion bicruciate-stabilized (BCS) total knee arthroplasty (TKA) includes a dual cam-post mechanism with an asymmetric bearing geometry that promotes normal knee kinematics and enhances anterior-posterior stability. However, it is unclear whether the improved biomechanics after guided-motion BCS TKA reproduce soft tissue strain similar to the strain generated by native knees. The purpose of this cadaveric study was to compare medial collateral ligament (MCL) strain between native and guided-motion BCS TKA knees using a video extensometer. Materials and Methods: Eight cadaver knees were mounted onto a customized knee squatting simulator to measure MCL strain during flexion in both native and guided-motion BCS TKA knees (Journey II-BCS; Smith & Nephew, Memphis, TN, USA). MCL strain was measured using a video extensometer (Mercury® RT RealTime tracking system, Sobriety s.r.o, Kuřim, Czech Republic). MCL strain level and strain distribution during knee flexion were compared between the native and guided-motion BCS TKA conditions. Results: The mean and peak MCL strain were similar between native and guided-motion BCS TKA knees at all flexion angles (p > 0.1). MCL strain distribution was similar between native and BCS TKA knees at 8 of 9 regions of interest (ROIs), while higher MCL strain was observed after BCS TKA than in the native knee at 1 ROI in the mid portion of the MCL at early flexion angles (p < 0.05 at ≤30° of flexion). Conclusions: Guided-motion BCS TKA restored the amount and distribution of MCL strain to the values observed on native knees.

Restoration of the Joint Line Configuration Reproduces Native Mid-Flexion Biomechanics after Total Knee Arthroplasty: A Matched-Pair Cadaveric Study

Background: Recent evidence supports that restoration of the pre-arthritic condition via total knee arthroplasty (TKA) is associated with improved post-TKA performance and patient satisfaction. However, whether the restored pre-arthritic joint line simulates the native mid-flexion biomechanics remains unclear. Objective: We performed a matched-pair cadaveric study to explore whether restoration of the joint line via kinematically aligned (KA) TKA reproduced native knee biomechanics more accurately than the altered joint line associated with mechanically aligned (MA) TKA. Methods: Sixteen fresh-frozen cadaveric knees (eight pairs) were affixed onto a customized knee-squatting simulator for measurement of femoral rollback and medial collateral ligament (MCL) strain during mid-flexion. One knee from each cadaver was randomly designated to the KA TKA group (with the joint line restored to the pre-arthritic condition) and the other to the MA TKA group (with the joint line perpendicular to the mechanical axis). Optical markers were attached to all knees and rollback was analyzed using motion capture cameras. A video extensometer measured real-time variations in MCL strain. The kinematics and MCL strain prior to and following TKA were measured for all specimens. Results: KA TKA was better for restoring the knee kinematics to the native condition than MA TKA. The mid-flexion femoral rollback and axial rotation after KA TKA were consistently comparable to those of the native knee. Meanwhile, those of MA TKA were similar only at ≤40° of flexion. Furthermore, KA TKA better restored the mid-flexion MCL strain to that of the native knee than MA TKA. Over the entire mid-flexion range, the MCL strain of KA TKA and native knees were similar, while the strains of MA TKA knees were more than twice those of native knees at >20° of flexion. Conclusions: The restored joint line after KA TKA effectively reproduced the native mid-flexion rollback and MCL strain, whereas the altered joint line after MA TKA did not. Our findings may explain why patients who undergo KA TKA experience superior outcomes and more natural knee sensations during daily activities than those treated via MA TKA.

Kinematically aligned total knee arthroplasty restores more native medial collateral ligament strain than mechanically aligned total knee arthroplasty

PURPOSE

Kinematically aligned total knee arthroplasty (KA TKA) targets restoration of patient-specific alignment and soft tissue laxity. However, whether KA TKA reproduces native soft tissue strain remains unclear. This cadaveric study tested the hypothesis that KA TKA would better restore the quantitative strain and strain distribution of medial collateral ligament (MCL) to the native healthy knee compared to mechanically aligned (MA) TKA.

METHODS

Twenty-four fresh-frozen cadaver knees (12 pairs) were mounted on a customized knee squatting simulator to measure MCL strain during flexion. For each pair, one knee was assigned to KA TKA and the other to MA TKA. During KA TKA, the amount of femur and tibia resected was equivalent to implant thickness without MCL release using the calipered measuring technique. MA TKA was performed using conventional measured resection techniques. MCL strain was measured using a video extensometer (Mercury® RT RealTime tracking system, Sobriety s.r.o, Czech Republic). MCL strain and strain distribution during knee flexion were measured, and the measurements compared between native and post-TKA conditions.

RESULTS

Mean and peak MCL strain were similar between KA TKA and native knees at all flexion angles (p > 0.1 at all flexion angles) while mean strain at all flexion angles and peak strain at ≥ 60º of MA TKA were approximately twice those of the native knees (p < 0.05 at ≥ 60º of flexion). In addition, greater MCL strain was observed in 4 of 12 regions of interest (ROI) after MA TKA (M1, M2, P1 and P2) compared to the native knee, whereas after KA TKA, MCL strain measurements were similar at all but 1 ROI (P2).

CONCLUSIONS

KA TKA restored a more native amount and distribution of MCL strain compared to MA TKA. These findings provide clues for understanding why patients may experience better performance and more normal knee sensations after KA TKA compared to MA TKA.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

Remnant preservation may improve proprioception after anterior cruciate ligament reconstruction

Aim

Our aim was to evaluate the literature investigating proprioception improvement after anterior cruciate ligament reconstruction (ACLR) and test the hypothesis that ACL tibial remnant-preserving reconstruction (ACLR-R) is more beneficial than standard technique (ACLR-S) in terms of postoperative proprioceptive function with various reported tests, including joint position sense (JPS) and threshold to detect passive motion (TTDPM).

Methods

An online search was performed in Embase, MEDLINE/PubMed, Cochrane, SPORTDiscus, and Web of Science databases before 5 October 2020, on the basis of the guidelines of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. Key terms [(‘ACLR’ or ‘ACL-R’ or ‘anterior cruciate ligament reconstruction’) AND (‘remnant’ or ‘stump’) AND (‘proprioception’ or ‘proprioceptive’)] were used. The Oxford Centre for Evidence-Based Medicine and The McMaster Critical Review Form for Quantitative Studies were used for quality assessment. In total, four articles comparing proprioceptive functions between ACLR-R and ACLR-S were included, two of which were randomized clinical trials rated as level of evidence II, and two were retrospective cohort studies rated as level of evidence III. The outcomes were then compared. Evaluation of proprioception involved joint position sense (JPS) [reproduction of active positioning (RAP) and reproduction of passive positioning (RPP)] and threshold to detect passive motion (TTDPM) tests.

Results

Only four studies were included, with a total of 234 patients (119 ACLR-R patients and 115 ACLR-S patients). High heterogeneity in characteristics and outcome measurements was observed among the studies. Three studies performed sparing technique, and one performed tensioning technique. One study tested RAP and reported better results at an average of 7 months follow-up in ACLR-R (P < 0.05). Three studies tested RPP, one of which measured RPP within 12 months after surgery and reported better results in ACLR-R than in ACLR-S (P < 0.05). The other two studies reported similar results; however, the findings of one study were statistically insignificant. TTDPM was tested in one study, with no statistically significant difference found.

Conclusion

The current literature, although limited, reported proprioception improvement after ACLR-R (compared with ACLR-S) in terms of JPS. However, owing to the heterogeneity of the relevant studies, further research is required to determine remnant preservation effect on knee proprioceptive restoration.

Level of evidence

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

Does posterior cruciate ligament sacrifice influence dynamic balance after total knee arthroplasty? Comparison of cruciate-retaining and cruciate-substituting designs in bilaterally operated patients

PURPOSE

This study aimed to evaluate whether the posterior cruciate ligament sacrifice during total knee arthroplasty (TKA) has any effect on postoperative standing balance or not.

METHODS

The patients who underwent bilateral TKA with either CR or PS design were analyzed. 30 patients (10 PS, 20 CR) were included for the final analysis. TKA designs were compared in terms of Lysholm score, range of motion, and balance characteristics including somatosensorial, vestibular, and visual balance scales, adaptation, limits of stability, and weight-bearing/squat tests by computerized dynamic posturography.

RESULTS

The mean follow-up time was 59 months for CR, 49 months for PS group. The average Lysholm score values were 94 for CR and 95 for PS group, indicating functionally similar patient groups. The average knee flexion was found significantly higher in PS group (114°) compared to CR group (102°) (p = 0.009). In the CR group, motor adaptation tests (toes up/toes down) were found to be better (p = 0.034). In the on-axis velocity parameter (linear goal orientation) of limits of stability test, PS group patients were found to be more successful (p = 0.035).

CONCLUSIONS

The use of CR implants can be recommended in patients with a high risk of falling since they provide better motor adaptation providing rapid reactions to rapid surface changes. Better linear goal orientation in PS group, providing a faster movement in an intended direction, should be considered when planning the ideal implant for the patients with relevant activities.

Anterior and Posterior Cruciate Ligaments Mechanoreceptors: A Review of Basic Science

Proprioception is a specialized sensory modality encompassing the movement of the joint and its position in space, and it involves the conversion of mechanical deformation of tissues into neural signals. Mechanoreceptors are specialized nerve structures able to transmit mechanical deformation through electrical signals to dorsal root ganglion sensory neurons and are abundant in the muscles, tendons and ligaments of the knee joint. They are believed to play an important role in knee proprioception and dynamic knee stability. Proprioception should always be taken into consideration for successful reconstruction of the cruciate-deficient knee and for pain and function management in the arthritic knee. Advances in histological methods of detection are numerous and continue to highlight the presence and role of mechanoreceptors after ligament reconstruction, depending on choice of graft. In this review, we present the current knowledge of anterior and posterior cruciate ligaments and grafts mechanoreceptors, and their role in proprioception of knee joint, focusing on each type of mechanoreceptors.

Proprioceptive and Clinical Outcomes after Remnant Preserved Anterior Cruciate Ligament Reconstruction: Assessment with Minimal Confounding Factors

Objective

To evaluate the proprioceptive and clinical function of the knee joint after anterior cruciate ligament reconstruction (ACLR) with various amounts of remnant preserved with as few confounding factors as possible.

Methods

This retrospective study included 46 patients who underwent ACLR with remnant preservation between March 2013 and February 2019. These patients had less than 6 months injury‐to‐surgery interval and no concomitant injuries. The researchers divided these subjects into two groups based on the length of the remnant preserved after ACLR, with group A defined as having more than 1/3 of the original length preserved and group B defined as less than 1/3 of the original length preserved. Clinical scores were obtained using the Lysholm knee scoring scale and the Tegner activity scale. The Lysholm score was calculated preoperatively, at 3, 6, and 12 months postoperatively, and at the last follow up. The Tegner score was calculated preoperatively, at 12 months postoperatively and at the last follow up. Anterior laxity was measured using the KT2000 arthrometer preoperatively and at 12 months postoperatively. Proprioceptive function was evaluated through reproduction of passive positioning (RPP) and threshold to detection of passive motion (TDPM). Both RPP and TDPM were measured at the angle of 15° at 3, 6, and 12 months postoperatively. Unpaired t‐tests were performed to investigate the difference in each parameters between the two groups.

Results

In the present study, 20 patients were classified into group A and 26 into group B. All patients were followed up for an average of 34.70 ± 12.79 months. All 46 patients were satisfied with the outcome of the surgery and no complications were reported at the end of the study. No significant differences were found between the two groups in terms of the Lysholm score and anterior laxity by KT2000 at all time points. The Tegner score was significantly higher in group A at 12 months postoperatively and at the final follow‐up. In addition, group A's RPP was significantly better than that of group B's when tested at the angles of 15° and 30° at 3 months postoperatively, and at the angle of 15° at 6 months postoperatively. Group A's TDPM was also significantly better than that of group B's at all three tested angles at 3 months postoperatively, and at the angle of 15° at 6 months postoperatively.

Conclusion

Patients with ACLR with more than 1/3 of the original length preserved demonstrated a higher activity level 12 months postoperatively and better proprioceptive function at 15° of extension at 3 and 6 months postoperatively.

Editorial Commentary: Blood Flow Restriction Therapy Continues to Prove Effective

Blood flow restriction (BFR) training continues to look promising to try and maintain muscle mass or to rebuild muscle mass and strength after injury or surgery. Because additional potential benefits include pain control, increased gene expression (leading to atrophy reduction), and muscle excitation, our use of the modality favors earlier over middle- or late-phase postoperative use. We initiate BFR therapy 2-14 days postoperatively, often with reduced cuff pressure in the first several sessions before increasing to the recommended therapeutic occlusion level. We have observed the greatest benefit for individuals who are non-weight-bearing for 6 to 8 weeks and who may have more postoperative restrictions due to the nature of the surgery. Compared with the opposite thigh, we have seen instances in which quadriceps girth has been preserved, although not increased, following the non-weight-bearing period. Ideally, we use 1 to 3 low-load resistance training exercises per session at least 2 times per week for 6 weeks. We also employ BFR following osteotomy or any procedure where bone drilling is used, as researchers have observed improved bone health. Additional benefits relevant to the early postoperative phase, such as effusion and pain reduction, have not been clearly established. Anecdotally, we have seen effusion levels temporarily increase during treatment but then resolve to baseline within 30 to 60 minutes of tourniquet deflation. Further high-level research is necessary to objectively validate BFR use and which patients may best benefit from it.

Properties of Knee Joint Position Sense Tests for Anterior Cruciate Ligament Injury: A Systematic Review and Meta-analysis

Background:

Knee proprioception is believed to be deficient after anterior cruciate ligament (ACL) injury. Tests of joint position sense (JPS) are commonly used to assess knee proprioception, but their psychometric properties (PMPs) are largely unknown.

Purpose:

To evaluate the PMPs (reliability, validity, and responsiveness) of existing knee JPS tests targeting individuals with ACL injury.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

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

Results:

Included were 80 studies covering 119 versions of knee JPS tests. Meta-analyses indicated sufficient quality for known-groups and discriminative validity (ACL-injured knees vs knees of asymptomatic controls and contralateral noninjured knees, respectively), owing to significantly greater absolute errors for ACL-injured knees based on a strong level of evidence. A meta-analysis showed insufficient quality for responsiveness, which was attributed to a lack of significant change over time after diverse interventions with a moderate level of evidence. Statistical heterogeneity (I² > 40%) was evident in the majority of meta-analyses. All remaining PMPs (reliability, measurement error, criterion validity, convergent validity, and other PMPs related to responsiveness) were assessed qualitatively, and they failed to achieve a sufficient quality rating. This was a result of either the study outcomes not agreeing with the statistical cutoff values/hypotheses or the level of evidence being rated as conflicting/unknown or based on only a single study.

Conclusion:

Knee JPS tests appear to have sufficient validity in differentiating ACL-injured knees from asymptomatic knees. Further evidence of high methodologic quality is required to ascertain the reliability, responsiveness, and other types of validity assessed here. We recommend investigations that compare the modifiable methodologic components of knee JPS tests on their PMPs to develop standardized evidence-based tests.

Mechanoreceptors observed in a ligamentous structure between the posterior horn of the lateral meniscus and the anterior cruciate ligament

PURPOSE

A histological study of a structure between the posterior horn of the lateral meniscus and the anterior cruciate ligament.

METHODS

Bilateral fresh-frozen cadaveric knees of two male donors (age 71 and 76 years) with no history of prior knee injury were examined. All dissections were performed by one experienced orthopaedic surgeon. Haematoxylin and Eosin staining was used to reveal tissue morphology. Goldner trichrome staining was used to evaluate the connective tissue. S100 and PGP 9.5 labelling were used for immunohistochemical analysis.

RESULTS

In all cadaveric knees, a structure between the posterior horn of the lateral meniscus and the anterior cruciate ligament was identified. Histological analysis confirmed the ligamentous nature of this structure. Furthermore, Golgi tendon organs were observed within the ligamentous structure.

CONCLUSION

This is the first study showing the presence of mechanoreceptors within the ligamentous structure between the posterior horn of the lateral meniscus and the anterior cruciate ligament. The ligamentous structure could contribute to stability of the knee by providing proprioceptive input, while preservation of the ligamentous structure might ensure a better functional outcome after surgery.

Long-term Effect of a Single Subcritical Knee Injury: Increasing the Risk of Anterior Cruciate Ligament Rupture and Osteoarthritis

BACKGROUND

Rupture of the anterior cruciate ligament (ACL) is a well-known risk factor for the development of posttraumatic osteoarthritis (PTOA), but patients with the "same injury" can have vastly different trajectories for the onset and progression of disease. Minor subcritical injuries preceding the critical injury event may drive this disparity through preexisting tissue pathologies and sensory changes.

PURPOSE

To investigate the role of subcritical injury on ACL rupture risk and PTOA through the evaluation of pain behaviors, joint mechanics, and tissue structural change in a mouse model of knee injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten-week-old male C57BL/6J mice were allocated to naïve control and subcritical knee injury groups. Injury was induced by a single mechanical compression to the right hindlimb, and mice were evaluated using joint histopathology, anteroposterior joint biomechanics, pain behaviors (mechanical allodynia and hindlimb weightbearing), and isolated ACL tensile testing to failure at 1, 2, 4, or 8 weeks after injury.

RESULTS

Subcritical knee injury produced focal osteochondral lesions in the patellofemoral and lateral tibiofemoral compartments with no resolution for the duration of the study (8 weeks). These lesions were characterized by focal loss of proteoglycan staining, cartilage structural change, chondrocyte pathology, microcracks, and osteocyte cell loss. Injury also resulted in the rapid onset of allodynia (at 1 week), which persisted over time and reduced ACL failure load (P = .006; mean ± SD, 7.91 ± 2.01 N vs 9.37 ± 1.01 N in naïve controls at 8 weeks after injury), accompanied by evidence of ACL remodeling at the femoral enthesis.

CONCLUSION

The present study in mice establishes a direct effect of a single subcritical knee injury on the development of specific joint tissue pathologies (osteochondral lesions and progressive weakening of the ACL) and allodynic sensitization. These findings demonstrate a predisposition for secondary critical injuries (eg, ACL rupture) and an increased risk of PTOA onset and progression (structurally and symptomatically).

CLINICAL RELEVANCE

Subcritical knee injuries are a common occurrence and, based on this study, can cause persistent sensory and structural change. These findings have important implications for the understanding of risk factors of ACL injury and subsequent PTOA, particularly with regard to prevention and management strategies following an often underreported event.

The effects of partial meniscectomy and meniscal repair on the knee proprioception and function

PURPOSE

Aim of our study was to compare the effects of partial meniscectomy and meniscus repair on knee proprioception and function.

METHODS

The study included 46 patients with clinical and radiological diagnosis of meniscal tear and accompanying anterior cruciate ligament (ACL) rupture. The patients were evaluated under two groups: group 1: partial meniscectomy and ACL reconstruction, and group 2: meniscal repair and ACL reconstruction. Proprioceptive and functional evaluation of all patients was performed prior to surgery and on postoperative 12th month.

RESULTS

Group 1 consists of 18 male and 1 female patients with an average age of 28.78 ± 3.50. Group 2 consists of 23 male and 4 female patients with an average age of 27.14 ± 3.65. Preoperative evaluation revealed significant differences in knee joint position sense values on wide range of knee motion (15°, 30°, 45°, 60°, and 75°) in both groups. The statistically significant difference was observed in only the range of knee motion of 60° in patients underwent meniscal repair (group 2), whereas in the range of knee motion of 45°, 60°, and 75° in patients underwent partial meniscectomy (group 1) at 12th-month control. According to Lysholm knee scoring system, significantly better results were achieved with meniscal repair compared to the partial meniscectomy at 12th-month control.

CONCLUSION

In case of ACL rupture accompanied by meniscal tear, the meniscal repair should be sutured, if possible, in order to obtain better results in terms of knee function and proprioception.

Increased visual distraction can impair landing biomechanics

Failed jump landings represent a key mechanism of musculoskeletal trauma. It has been speculated that cognitive dual-task loading during the flight phase may moderate the injury risk. This study aimed to explore whether increased visual distraction can compromise landing biomechanics. Twenty-one healthy, physically active participants (15 females, 25.8 ± 0.4 years) completed a series of 30 counter-movement jumps (CMJ) onto a capacitive pressure platform. In addition to safely landing on one leg, they were required to memorize either one, two or three jersey numbers shown during the flight phase (randomly selected and equally balanced over all jumps). Outcomes included the number of recall errors as well as landing errors and three variables of landing kinetics (time to stabilization/TTS, peak ground reaction force/pGRF, length of the centre of pressure trace/COPT). Differences between the conditions were calculated using the Friedman test and the post hoc Bonferroni-Holm corrected Wilcoxon test. Regardless of the condition, landing errors remained unchanged (p = .46). In contrast, increased visual distraction resulted in a higher number of recall errors (chi² = 13.3, p = .001). Higher cognitive loading, furthermore, appeared to negatively impact mediolateral COPT (p < .05). Time to stabilization (p = .84) and pGRF (p = .78) were unaffected. A simple visual distraction in a controlled experimental setting is sufficient to adversely affect landing stability and task-related short-term memory during CMJ. The ability to precisely perceive the environment during movement under time constraints may, hence, represent a new injury risk factor and should be investigated in a prospective trial.

Immunohistochemical analysis of sensory corpuscles in human transplants of the anterior cruciate ligament

Background

Sensory nerve endings in ligaments play an important role for the proprioceptive function. Clinical trials show that the sense of body position does not fully recover in the knee joint after reconstructive surgery of the ruptured anterior cruciate ligament. The aim of this study is to identify sensory corpuscles in autogenous and allogenous transplants of the ligament and to compare their quantity between the used allografts and autografts.

Methods

Thirty-three patients were included in this study. Three patellar tendon allografts, 14 patellar tendon autografts and 12 semitendinosus autografts were harvested during revision surgery after traumatic rerupture of the graft. The control consisted of 4 healthy anterior cruciate ligaments after fresh rupture. After haematoxylin staining, immunohistochemical analysis was performed using antibodies against S100, p75 and PGP9.5. Microscopical examination was carried out, and the number of mechanoreceptors was counted. Statistical analysis was performed using the Mann-Whitney U test.

Results

Two types of mechanoreceptors were identified in each graft: Ruffini corpuscles and free nerve endings. The number of Ruffini corpuscles per square centimeter was the highest in the control. Comparing the grafts, the highest number of receptors could be detected in the semitendinosus autograft. The amount of free nerve endings was higher in the semitendinosus and patellar tendon autografts than in the control; the allografts showed the lowest number of receptors. With increasing time after reconstruction, the number of both types of receptors showed a decrease in the semitendinosus graft, whereas it increased in the patellar tendon graft and allograft. The number of mechanoreceptors in the semitendinosus and patellar tendon graft decreased over time after graft-failure, whereas it increased slightly in the allograft.

Conclusion

This study was the first to identify mechanoreceptors in human transplants of the anterior cruciate ligament. The partial increase in the number of receptors over time after reconstruction could indicate a reinnervation of the grafts.

Arthroscopic all-inside ATiFL's distal fascicle transfer for ATFL's superior fascicle reconstruction or biological augmentation of lateral ligament repair

PURPOSE

Tendon grafts are often utilized for reconstruction of the lateral ligaments unamenable to primary repair. However, tendon and ligaments have different biological roles. The anterior tibiofibular ligament's (ATiFL) distal fascicle may be resected without compromising the stability of the ankle joint. The aim of this study is to describe an all-arthroscopic and intra-articular surgical technique of ATiFL's distal fascicle transfer for the treatment of chronic ankle instability.

METHODS

Five unpaired cadaver ankles underwent arthroscopic ATiFL's distal fascicle transfer using a non-absorbable suture and a knotless anchor. Injured or absent ATiFL's distal fascicle were excluded from the study. Following arthroscopy, the ankles were dissected and evaluated for entrapment of nearby adjacent anatomical structures. The ligament transfer was also assessed. The distance between the anterolateral (AL) portals and the superficial peroneal nerve (SPN) was measured and the shortest distance was reported.

RESULTS

All specimens revealed successful transfer of the tibial origin of the ATiFL's distal fascicle onto the talar insertion of anterior talofibular ligament's (ATFL) superior fascicle. The fibular origin of the ATiFL's distal fascicle remained intact. There were no specimens with SPN or extensor tendon entrapment. The median distance between the proximal AL portal and SPN was 3.8 mm. The median distance between the distal AL portal and SPN was 3.9 mm.

CONCLUSION

An all-arthroscopic approach to an ATiFL's distal fascicle transfer is a reliable method to reconstruct the ATFL's superior fascicle. Transfer of ATiFL's distal fascicle avoids the need for tendon harvest or allograft. The lack of injury to nearby adjacent structures suggests that it is a safe procedure. The clinical relevance of the study is that ATiFL's distal fascicle can be arthroscopically transferred to be used as a biological reinforcement of the ATFL repair, or as an ATFL reconstruction.

Immunofluorescence analysis of sensory nerve endings in the interosseous membrane of the forearm

The human interosseous membrane (IOM) is a fundamental stabilizer during forearm rotation. To investigate the dynamic aspects of forearm stability, we analyzed sensory nerve endings in the IOM. The distal oblique bundle (DOB), the distal accessory band (DAB), the central band (CB), the proximal accessory band (PAB), the dorsal oblique accessory cord (DOAC) and the proximal oblique cord (POC) were dissected from 11 human cadaver forearms. Sensory nerve endings were analyzed at two levels per specimen as total cell amount/mm² after immunofluorescence staining with low-affinity neurotrophin receptor p75, protein gene product 9.5, S-100 protein and 4',6-diamidino-2-phenylindole on an Apotome microscope, according to Freeman and Wyke's classification. Sensory nerve endings were significantly more commonly found to be equally distributed throughout the structures, rather than being epifascicular, interstitial, or close to the insertion into bone (P ≤ 0.001, respectively). Free nerve endings were the predominant mechanoreceptor in all six structures, with highest density in the DOB, followed by the POC (P ≤ 0.0001, respectively). The DOB had the highest density of Pacini corpuscles. The DOAC and CB had the lowest amounts of sensory innervation. The high density of sensory corpuscles in the DOB, PAB and POC indicate that proprioceptive control of the compressive and directional muscular forces acting on the distal and proximal radioulnar joints is monitored by the DOB, PAB and POC, respectively, due to their closed proximity to both joints, whereas the central parts of the IOM act as structures of passive restraint.

Effects of Kinesio taping of the knee on proprioception, balance, and functional performance in patients with anterior cruciate ligament rupture: A retrospective case series

To investigate whether Kinesio tape (KT) application improves proprioception, balance, and functional performance in patients with anterior cruciate ligament rupture (ACLr).This retrospective analysis included 48 male patients with surgically-untreated ACLr who attended the Sports Medicine and Rehabilitation Center, Qingdao Municipal Hospital, China between June 2017 and June 2018. KT was applied to induce a detoning effect on the quadriceps muscle and toning effect on the ischiocrural muscles. Proprioception, balance, and functional performance were assessed before and 1 and 7 days after KT application using the Lysholm scale, anteroposterior shift of the tibia (APST), active angle reproduction test (AART), modified star excursion balance test (mSEBT), and single-hop distance (SHD).KT resulted in significant improvements in Lysholm scale at 1 day (83.00 [6.50] vs. 76.00 [5.25], P < .001) and APST (8.00 [2.00] vs. 10.00 [2.00] mm, P < .001), AART (3.00 [1.00] vs. 4.00 [1.75] degrees, P < .001), SEBT (96.08 [6.62] vs. 83.92 [7.31] %, P < .001) and SHD (120.96 [6.94] vs. 106.46 [9.03] %, P < .001) at 3 hours (median [interquartile range]). However, significant deficits remained when compared with the healthy side. Except for mSEBT posterolateral direction, those effects were maintained at 7 days.KT has benefits in people with ACLr but cannot fully compensate for functional deficits. KT could be used to assist knee strengthening during rehabilitation.

Study of the Nerve Endings and Mechanoreceptors of the Anterolateral Ligament of the Knee

PURPOSE

To describe the morphology and distribution of the anterolateral ligament of the knee (ALL) nerve endings, aiming to understand the interaction between the proprioceptive system and knee mechanics.

METHODS

Twenty ALLs were obtained from fresh frozen cadavers. The ligaments were measured, weighed, and cut. Sections (10 μm) were prepared in hematoxylin and eosin-stained slides to analyze tissue integrity, and 50-μm sections were subjected to immunofluorescence with the protein gene product 9.5 as primary antibody and Alexa Fluor 488 as secondary antibody, followed by microscopic analysis.

RESULTS

The ALL was identified in 100% of the dissections, exhibiting a mean (± standard deviation) length of 4.0 ± 0.4 cm, a mean width of 5.5 ± 0.8 mm, and a mean weight of 0.9 ± 0.2 g. The histological sections in hematoxylin and eosin showed dense, well-organized collagen and the presence of vascular tissue. All the specimens analyzed contained type I (Ruffini-like) mechanoreceptors and free nerve endings (type IV), varying from parallel to intertwined fibers. Unclassified nerve endings with different irregular shapes were also found. The neural elements occupied 0.6% ± 0.3% of the ligament area, and most were observed near the origin of ALL insertions.

CONCLUSION

The ALL exhibits a peripheral nerve structure, primarily type I and IV mechanoreceptors. These findings suggest that the ALL is important for the proprioception and anterolateral stabilization of the knee.

CLINICAL RELEVANCE

It is important to understand ALL innervation and infer how an injury could compromise the proprioceptive role of the lateral compartment, as the ligaments contribute dynamically to stability through proprioceptive control of muscle forces. The findings confirm that the ALL is highly innervated by mechanoreceptors and may have a proprioceptive role in conjunction with the lateral collateral ligament in the lateral region of the knee.

Can texture change joint position sense at the knee joint in those with poor joint position accuracy?

Purpose: Skin contributes to joint position sense (JPS) at multiple joints. Altered cutaneous input at the foot can modulate gait and balance and kinesiology tape can enhance proprioception at the knee, but its effect may be dependent on existing capacity. The effect of texture at the knee, particularly in those with poor proprioception, is unknown. The aim of this study was to determine the effect of textured panels on JPS about the knee. Materials and methods: Eighteen healthy females were seated in an adjustable chair. Their left leg (target limb) moved passively from 65° to a target of flexion (115° or 90°) or extension (40°). Their right leg (matching limb) was passively moved towards this target angle and participants indicated when their limbs felt aligned. We tested three textured panels over the knee of the matching limb and two control conditions. The target limb maintained a control panel. Directional error, absolute error and variable error in matching between limbs were calculated. Results: On average textured panels over the knee increased JPS error compared to control pants for participants with poor JPS. These participants undershot the target at 90° of flexion significantly more with textured panels (-11° ± 3°) versus control (-7° ± 3°, p = 0.04). Conclusions: For participants with poor JPS accuracy, increased JPS error at 90° with a textured panel suggests these individuals utilised altered cutaneous information to adjust joint position. We propose increased error results from enhanced skin input at the knee leading to the perception of increased flexion.

Psychometric properties of knee proprioception tests targeting healthy individuals and those with anterior cruciate ligament injury managed with or without reconstruction: a systematic review protocol

INTRODUCTION

An anterior cruciate ligament (ACL) injury affects knee proprioception and sensorimotor control and might contribute to an increased risk of a second ACL injury and secondary knee osteoarthritis. Therefore, there is a growing need for valid, reliable and responsive knee proprioception tests. No previous study has comprehensively reviewed all the relevant psychometric properties (PMPs) of these tests together. The aim of this review protocol is to narrate the steps involved in synthesising the evidence for the PMPs of specific knee proprioception tests among individuals with an ACL injury and knee-healthy controls.

METHODS AND ANALYSIS

The Preferred Reporting Items for Systematic reviews and Meta-Analyses will be followed to report the review. A combination of four conceptual groups of terms-(1) construct (knee proprioception), (2) target population (healthy individuals and those with an ACL injury managed conservatively or with a surgical reconstruction), (3) measurement instrument (specific knee proprioception tests) and (4) PMPs (reliability, validity and responsiveness)-will be used for electronic databases search. PubMed, AMED, CINAHL, SPORTDiscus, Web of Science, Scopus, the Cochrane Central Register of Controlled Trials and ProQuest will be searched from their inception to November 2018. Two reviewers will independently screen titles, abstracts and full text articles, extract data and perform risk of bias assessment using the updated COnsensus-based Standards for the selection of health Measurement INstruments risk of bias checklist for the eligible studies. A narrative synthesis of the findings and a meta-analysis will be attempted as appropriate. Each PMP of knee proprioception tests will be classified as 'sufficient', 'indeterminate' or 'insufficient'. The overall level of evidence will be ascertained using an established set of criteria.

ETHICS AND DISSEMINATION

Ethical approval or patient consent is not required for a systematic review. The review findings will be submitted as a series of manuscripts for peer-review and publication in scientific journals.

PROSPERO REGISTRATION NUMBER

CRD42018108014.

Neurophysiological correlates of motor planning and movement initiation in ACL-reconstructed individuals: a case-control study

INTRODUCTION

Current evidence suggests that the loss of mechanoreceptors after anterior cruciate ligament (ACL) tears might be compensated by increased cortical motor planning. This occupation of cerebral resources may limit the potential to quickly adapt movements to unforeseen external stimuli in the athletic environment. To date, studies investigating such neural alterations during movement focused on simple, anticipated tasks with low ecological validity. This trial, therefore, aims to investigate the cortical and biomechanical processes associated with more sport-related and injury-related movements in ACL-reconstructed individuals.

METHODS AND ANALYSIS

ACL-reconstructed participants and uninjured controls will perform repetitive countermovement jumps with single leg landings. Two different conditions are to be completed: anticipated (n=35) versus unanticipated (n=35) successful landings. Under the anticipated condition, participants receive the visual information depicting the requested landing leg prior to the jump. In the unanticipated condition, this information will be provided only about 400 msec prior to landing. Neural correlates of motor planning will be measured using electroencephalography. In detail, movement-related cortical potentials, frequency spectral power and functional connectivity will be assessed. Biomechanical landing quality will be captured via a capacitive force plate. Calculated parameters encompass time to stabilisation, vertical peak ground reaction force, and centre of pressure path length. Potential systematic differences between ACL-reconstructed individuals and controls will be identified in dependence of jumping condition (anticipated/ unanticipated, injured/uninjured leg and controls) by using interference statistics. Potential associations between the cortical and biomechanical measures will be calculated by means of correlation analysis. In case of statistical significance (α<0.05.) further confounders (cofactors) will be considered.

ETHICS AND DISSEMINATION

The independent Ethics Committee of the University of Frankfurt (Faculty of Psychology and Sports Sciences) approved the study. Publications in peer-reviewed journals are planned. The findings will be presented at scientific conferences.

TRIAL STATUS

At the time of submission of this manuscript, recruitment is ongoing.

TRIAL REGISTRATION NUMBER

NCT03336060; Pre-results.

A Comprehensive Review of the Fabella Bone

The fabella is a sesamoid bone that is embedded in the lateral head of the gastrocnemius muscle and often articulates directly with the lateral femoral condyle. It is present in 10-30% of the general population with a higher incidence in Asians. The fabella can lead to various pathologies such as fabella pain syndrome and common fibular nerve palsy. Conservative treatment involves physical therapy or injecting local anesthetics or steroids around this bone. However, if symptoms persist, then a fabellectomy can be performed. Physicians should be aware of the fabella bone and the multiple pathologies associated with it in order to provide the best treatment and management for patients.

Effects on proprioception by Kinesio taping of the knee after anterior cruciate ligament rupture

INTRODUCTION

The use of Kinesio tape (KT) to improve proprioception is a matter of considerable debate. In comparison, the rupture of the anterior cruciate ligament is a sufficiently well-investigated injury with a proven compromise of proprioception. The objective of the present study was to assess a supportive effect on proprioception after KT application, taking the anterior cruciate ligament (ACL) rupture as an example.

MATERIALS AND METHODS

Forty-eight patients who had suffered an ACL rupture, confirmed clinically and by magnetic resonance imaging, and who were treated conservatively or were awaiting surgery were included in this study. In all patients, a gait analysis was performed on the affected leg before and after KT application. In addition, the IKDC score, the Lysholm score, stability using the Rolimeter, and the angle reproduction test were determined.

RESULTS

Thirty-nine men and nine women who had had an ACL rupture for at least 3 weeks were included in the study. Significant improvements were achieved on the affected knee joint for the gait analysis parameters touchdown and unrolling, cadence, stability and stance phase as well as an extension of the hip joint. The Lysholm score improved from 79.3 to 85.8 (p < 0.001) and the IKDC score from 60.2 to 71.3 points (p < 0.001). Significant improvements were achieved in the Rolimeter and angle reproduction test.

CONCLUSIONS

The use of KT has a positive effect on proprioception in patients with an anterior cruciate ligament rupture. Therefore, the application may improve gait pattern as well as the subjective function of the affected knee joint.

Effect of cognitive challenge on the postural control of patients with ACL reconstruction under visual and surface perturbations

Our study aimed to evaluate the effect of cognitive challenge on double-leg postural control under visual and surface perturbations of patients with anterior cruciate ligament reconstruction (ACLR) cleared to return to sport. Double-leg stance postural control of 19 rehabilitated patients with ACLR (age: 24.8 ± 6.7 years, time since surgery: 9.2 ± 1.6 months) and 21 controls (age: 24.9 ± 3.7 years) was evaluated in eight randomized situations combining two cognitive (with and without silent backward counting in steps of seven), two visual (eyes open, eyes closed) and two surface (stable support, foam support) conditions. Sway area and sway path of the centre of foot pressure were measured during three 20-s recordings for each situation. Higher values indicated poorer postural control. Generally, postural control of patients with ACLR and controls was similar for sway area and sway path (p > 0.05). The lack of visual anchorage and the disturbance of the plantar input by the foam support increased sway area and sway path (p < 0.001) similarly in both groups. The addition of the cognitive task decreased sway area and sway path (p < 0.001) similarly in both groups. Patients with ACLR who recently completed their rehabilitation have normalized postural control during double-leg stance tests. The use of a dual task paradigm under increased task complexity modified postural control, but in a similar way in patients with ACLR than in healthy controls. Double-leg stance tests, even under challenging conditions, are not sensitive enough to reveal postural control differences between rehabilitated patients with ACLR and controls.

Protecting the PCL During Total Knee Arthroplasty Using a Bone Island Technique

BACKGROUND

Prior studies have shown that the posterior cruciate ligament (PCL) may be partially resected during cruciate retaining (CR) total knee arthroplasty (TKA) using highly experienced hands and standard surgical technique; therefore, proper surgical technique is aimed at preservation and balance of the PCL during CR TKA. The central objective of this study is to evaluate the effectiveness of a simple surgical technique to prevent PCL damage during performance of a CR TKA.

METHODS

Sixty embalmed cadaver specimens were randomized into 2 groups, experimental and control. The control group consisted of standard tibial resection without the use of an osteotome. The experimental group utilized an osteotome in addition to standard technique to preserve a bone island anterior to the tibial attachment of the PCL.

RESULTS

In the control group, PCL damage was noted in 73% (22/30) of specimens. In the experimental group, where an osteotome was used, PCL damage was found in 23% (7/30) of specimens. The use of an osteotome was found to have an absolute risk reduction of 50% when compared to the control group which did not use an osteotome to protect the PCL.

CONCLUSION

In the setting of minimal surgical experience, the use of an osteotome to preserve the PCL during CR TKA by forming a bone island was found to be an effective means of protecting the PCL over standard technique. In addition, standard technique with the use of a Y-shaped PCL retractor was found to provide questionable protection to the PCL.