The effects of ACL injury on knee proprioception: a meta-analysis

Whole-body kinematics of squats two decades following anterior cruciate ligament injury

BACKGROUND

Kinematic studies suggest that injury of the anterior cruciate ligament (ACL) leads to long-lasting movement deficits or compensations to unload the injured knee. This study evaluated lower body kinematics during squats in individuals who suffered unilateral ACL-injury more than 20 years ago.

METHOD

Using motion capture, we compared maximum squat depth, time to complete the squat task, detailed kinematics, estimated kinetic-chain joint moments 0- 80° knee flexion, and weight distribution between legs across three groups with (ACLR, n = 27) and without ACL-reconstructive surgery (ACLPT, physiotherapy only, n = 28), and age-matched non-injured asymptomatic Controls (n = 31, average age across groups 47 years).

RESULTS

ACLPT demonstrated significantly reduced squat depth compared to Controls (p = 0.004), whereas ACLR performed similarly to Controls (p = 1.000). Other outcome variables were comparable between groups. All participants nevertheless demonstrated asymmetric weight distribution between legs but without systematic unloading of the injured side in the ACLgroups.

CONCLUSION

Expected compensatory strategies were not found in the ACL-groups, while poorer squat performance in the ACL-deficient group may depend on pure knee-joint mechanics, or lifestyle factors attributed to a less stable knee decades after ACL-injury.

Individuals early after anterior cruciate ligament reconstruction show intact motor learning of step length via the split-belt treadmill

BACKGROUND

Rupturing the anterior cruciate ligament is an orthopedic injury that results in neuromuscular impairments affecting sensory input to the central nervous system. Traditional physical therapy after anterior cruciate ligament reconstruction aims to rehabilitate orthopedic impairments but fails to address asymmetric gait mechanics that are present post-operatively and are linked to the development of post-traumatic osteoarthritis. A first step towards developing gait interventions is understanding if individuals after anterior cruciate ligament reconstruction have the capacity to learn new walking mechanics.

METHODS

The split-belt treadmill offers a task-specific approach to examine neuromuscular adaptations in patients after injury. The potential for changing spatiotemporal gait mechanics via split-belt treadmill adaptation has not been tested early after anterior cruciate ligament reconstruction; nor has the ability to retain and transfer newly learned gait mechanics. Therefore, we used a split-belt treadmill paradigm to compare gait adaptation, retention, and transfer to overground walking between 15 individuals 3-9 months after anterior cruciate ligament reconstruction and 15 matched control individuals.

FINDINGS

Results suggested individuals after anterior cruciate ligament reconstruction were able to adapt and retain step length symmetry changes as well as controls. There was also evidence of partial transfer to overground walking, similar to controls.

INTERPRETATION

Despite disruption in afferent feedback from the joint, individuals early after anterior cruciate ligament reconstruction can learn a new gait pattern using sensorimotor adaptation, retain, and partially transfer the learned gait pattern. This may be a critical time to intervene with gait-specific interventions targeting post-operative gait asymmetries.

Proprioception After Primary Repair of the Anterior Cruciate Ligament

BACKGROUND

Primary repair of the anterior cruciate ligament (ACL) has some potential advantages over the reconstruction technique, which include but are not limited to better knee sensation due to preservation of the natural ACL tissue in patients compared with tendon graft. Proprioception is impaired after ACL injuries and the sense of the joint position is lost.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare arthroscopic ACL primary repair and ACL reconstruction techniques clinically and functionally and analyze the differences in proprioception. It was hypothesized that primary repair would restore knee joint proprioception more successfully because the original tissue of the ACL is preserved.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 63 patients (34 underwent reconstruction and 29 underwent primary repair between 2017 and 2020) and 33 healthy controls, as well as the healthy knees of the operated groups, were evaluated between 24 and 48 months (mean, 29 months) postoperatively. Patients with proximal femoral avulsion tears and stump quality suitable for repair underwent primary repair, and those with tears outside these criteria underwent reconstruction using hamstring tendon autograft. Proprioception was evaluated using the active joint position sensation method during weightbearing, with a digital inclinometer used to measure differences between the target and achieved flexion angles of 15°, 30°, and 60°.

RESULTS

At 15° of knee flexion, the deviation angles for the healthy knee of the reconstruction and primary repair groups were significantly smaller than those of the control group (P < .001), but there was no statistically significant difference between the groups in terms of deviation angle at 30° and 60° of flexion. The deviation angle of the operated knees was statistically significantly larger in the reconstruction group than in the primary repair group at all angles. The deviation angles at 15°, 30°, and 60° were 2.83°, 2.66°, and 2.66° in the reconstruction group and 1.00°, 1.00°, and 1.33° in the primary repair group, respectively (P < .001). There was no statistically significant difference between the reconstruction and primary repair groups in terms of clinical scores.

CONCLUSION

Primary ACL repair can preserve proprioception in a well-selected patient group. In short-term follow-up, primary repair of the ACL in patients with proximal femoral avulsion tears and stump quality suitable for repair appears to be proprioceptively protective. Future studies are needed to clarify the long-term consequences of primary repair on proprioception in a larger population.

Risk factors of knee reinjury after anterior cruciate ligament reconstruction

PURPOSE

This study aimed to investigate whether the return to level I sports, concomitant injuries, foot-related problems, and other factors would increase the risk of knee reinjury after anterior cruciate ligament reconstruction (ACLR).

METHODS

This study used a prospective cohort study design. Online enrolment from August 2018 to January 2019 in ACL Community Indonesia recruited 148 patients who had undergone ACLR less than one month prior to injury. Knee injury occurrence after ACLR was diagnosed through a physical examination and positive MRI or arthroscopic findings.

RESULTS

During the study, 55 knee reinjuries occurred. The proportional hazards model analysis revealed that the risk of knee reinjury at 12 and 24 months for patients who returned to level I sports (hazards ratio (HR)=3.17 and HR=3.90, respectively) was significantly higher than that of the patients who did not return to sports and that the risk for those who returned to level II/III sports did not significantly increase at 12 or 24 months. Patients with concomitant meniscus injury had a significantly higher risk of knee reinjury at 12 and 24 months (HR=3.33 and HR=2.25, respectively) than those without, and the risk of knee reinjury for patients with concomitant posterior cruciate ligament injury was significantly higher at 12 months (HR=3.05) but not at 24 months. Fewer knee symptoms after ACLR were significantly associated with a lower risk of knee reinjury (HR=0.98) at 12 and 24 months.

CONCLUSIONS

The return to level I sports, concomitant meniscus and posterior cruciate ligament injury, and knee symptoms after ACLR may increase the risk of knee reinjury for post-ACLR patients.

Is proprioception affected in those with persistent intra-articular temporomandibular disorders? A cross-sectional study exploring joint position sense and force sense of the jaw

BACKGROUND

Proprioception is an important component of normal jaw function, although to date it is unknown if and how proprioception is affected in those with intra-articular temporomandibular disorders (IA-TMDs). This challenges effective management of this subgroup.

OBJECTIVES

Determine whether differences in local joint position sense and force sense exist between individuals with IA-TMD and those without a jaw problem.

DESIGN

Cross-sectional study.

METHOD

Sixty age and sex matched participants were recruited (n = 30 IA-TMD, n = 30 healthy controls). Temporomandibular joint position sense was tested to one target (50% of maximal mouth opening) using a ruler. Temporomandibular force sense was tested to two targets (50% and 70% of maximal molar pain-free bite force) using a bite sensor. Constant, absolute and variable errors were calculated for each outcome and compared between groups using p-values and 95% confidence intervals for effect size (d).

RESULTS

Significantly greater degrees of constant, absolute and variable error were seen for force sense testing at the 50% target (p < 0.05). No statistically significant difference was observed between groups for joint position sense, or for constant or variable force sense error at the 70% target (p > 0.05). Despite this, all joint position sense and force sense measures demonstrated possible clinical significance (upper limits 95% CI d ≥ 0.5).

CONCLUSIONS

Force sense, particularly at lower levels, appears impaired in those with IA-TMD. Joint position sense and force sense at higher levels appear less affected, although may still be important to consider in the management of IA-TMD in some patients.

Sensorimotor Dysfunction Following Anterior Cruciate Ligament Reconstruction- an Afferent Perspective: A Scoping Review

Background

Sensorimotor dysfunction is thought to occur following anterior cruciate ligament (ACL) injury which may have implications on future reinjury risk. Dysfunction has been demonstrated within the efferent component of the sensorimotor system. However, no reviews have examined the two main components of the afferent system: the visual and somatosensory systems.

Hypothesis/Purpose

This study aimed to report differences in function (central processing and local processing) within the (1) somatosensory and (2) visual systems between individuals following anterior cruciate ligament reconstruction (ACLR) and healthy controls (between-subject). The study also aimed to report differences in function within the two systems between the two limbs of an individual following ACLR (within-subject).

Study Design

Scoping review.

Methods

A search was conducted in PubMed, SPORTDiscus, CINAHL, Medline and Embase up until September 2021. Level I-IV studies assessing somatosensory and visual systems were included if they compared ACLR limbs to the uninjured contralateral limb (within-subject) or a healthy control limb (between-group). The function of somatosensory and visual systems was assessed across both central processing (processing of information in the central cortex) and local processing (all other assessments outside of central processing of information).

Results

Seventy studies were identified (52 somatosensory, 18 visual). Studies examining somatosensory central processing demonstrated significant differences; 66% of studies exhibited within-subject differences and 100% of the studies exhibited between-group differences. Studies examining local somatosensory processing had mixed findings; 40% of the 'joint position sense (JPS)' and 'threshold to detect motion (TTDM)' studies showed significant within-subject differences (JPS=0.8°-3.8° and TTDPM=0.2°-1.4°) and 42% demonstrated significant between-group differences (JPS=0.4°-5° and TTDPM=0.3°-2.8°). Eighty-three percent of visual central processing studies demonstrated significant dysfunction between-groups with no studies assessing within-subject differences. Fifty percent of the studies examining local visual processing demonstrated a significant between-group difference.

Conclusion

Significant differences in central processing exist within somatosensory and visual systems following ACLR. There is mixed evidence regarding local somatosensory and visual processing. Increased compensation by the visual system and local visual processing dysfunction may occur in conjunction with somatosensory dysfunction.

Anterior cruciate ligament repair versus reconstruction: A clinical, MRI and patient-reported outcome comparison

BACKGROUND

There has been a resurgence in anterior cruciate ligament (ACL) repair for proximal tears using modern surgical techniques and technology. This study aims to compare ACL repair with reconstruction using MRI, clinician-measured and patient-reported outcome measures (PROMs).

METHODS

A post-hoc analysis was performed on prospectively collected data from 20 consecutive primary ACL repairs by the senior author. This was compared with an age and sex-matched cohort of 20 ACL reconstructions by the same surgeon using PROMs, return-to-sport (RTS) testing, and MRI signal noise quotient (SNQ).

RESULTS

Repairs demonstrated equivalent post-operative PROMs to reconstructions as measured by International Knee Documentation Committee subjective score (78.5 ± 17.1 vs. 83.7 ± 13.3, P = 0.333), Tegner Activity Scale (5.9 ± 1.8 vs. 6.1 ± 2.6, P = 0.646) and Lysholm score (89.8 ± 10.0 vs. 89.6 ± 10.4, P = 0.762). There was no difference in repairs and reconstructions passing quadriceps strength criteria (50% vs. 53%, P = 0.097). A greater proportion of repairs passed hamstrings strength criteria (86% vs. 60%, P = 0.023) and hamstrings-to-quadriceps ratio (71% vs. 20%, P = 0.003). There were no differences across hop and Y-balance testing. Repairs had earlier RTS assessment (8.2 ± 2.8 months vs. 10.6 ± 1.4 months, P = 0.020). On 12-month MRI, repairs demonstrated higher femoral (8.8 ± 5.7 vs. 4.6 ± 2.9, P = 0.009) and tibial SNQ (10.0 ± 5.7 vs. 4.3 ± 4.2, P = 0.001), with no mid-substance difference (12.3 ± 8.5 vs. 7.6 ± 5.2, P = 0.074). There were no graft failures.

CONCLUSIONS

When patient selection is optimized for proximal tears, ACL repairs demonstrate equivalent PROMs and better objective outcomes to reconstructions at an earlier timepoint. Repair tissue quality on MRI shows higher signal at tibial and femoral attachments.

Exploring the Nexus of lower extremity proprioception and postural stability in older adults with osteoporosis: a cross-sectional investigation

Background

Osteoporosis, characterized by reduced bone mass and micro-architectural deterioration, poses a significant public health concern due to increased fracture susceptibility. Beyond bone health, this cross-sectional study aimed to assess and compare lower extremity proprioception and postural stability in individuals with and without osteoporosis and to explore their correlation within the osteoporosis group.

Method

In this prospective cross-sectional study, 80 participants were divided into two groups: osteoporosis (n = 40) and control (n = 40). The demographic characteristics and clinical parameters of the participants were as follows: Age (years) - Osteoporosis group: 65.04 ± 4.33, Control group: 65.24 ± 4.63; Sex (%) - Osteoporosis group: Male 30%, Female 70%; Control group: Male 30%, Female 70%; Body mass index (kg/m2) - Osteoporosis group: 23.7 ± 3.2, Control group: 24.5 ± 4.6; T-score (Lumbar) - Osteoporosis group: -2.86 ± 1.23, Control group: 0.27 ± 0.58; T-score (hip) - Osteoporosis group: -2.28 ± 0.79, Control group: 0.68 ± 0.86. Joint Position Sense (JPS) at the hip, knee, and ankle was assessed using a digital inclinometer, and postural stability was measured using computerized force platforms.

Result

Osteoporosis participants exhibited higher errors in hip (5.63° vs. 2.36°), knee (4.86° vs. 1.98°), and ankle (4.46° vs. 2.02°) JPS compared to controls. Postural stability measures showed increased anterior-posterior sway (10.86 mm vs. 3.98 mm), medial-lateral sway (8.67 mm vs. 2.89 mm), and ellipse area (966.88 mm2 vs. 446.19 mm2) in osteoporosis participants. Furthermore, correlation analyses within the osteoporosis group unveiled significant positive associations between lower extremity proprioception and postural stability. Specifically, hip JPS exhibited a strong positive correlation with anterior-posterior sway (r = 0.493, p = 0.003), medial-lateral sway (r = 0.485, p = 0.003), and ellipse area (r = 0.496, p < 0.001). Knee JPS displayed a moderate positive correlation with anterior-posterior sway (r = 0.397, p = 0.012), medial-lateral sway (r = 0.337, p = 0.032), and ellipse area (r = 0.378, p < 0.001). Similarly, ankle JPS showed a moderate positive correlation with anterior-posterior sway (r = 0.373, p = 0.023), medial-lateral sway (r = 0.308, p = 0.045), and ellipse area (r = 0.368, p = 0.021).

Conclusion

These findings underscore the interplay between proprioceptive deficits, compromised postural stability, and osteoporosis, emphasizing the need for targeted interventions to improve fall prevention strategies and enhance the quality of life for individuals with osteoporosis.

Is remnant preservation in anterior cruciate ligament reconstruction superior to the standard technique? An overview of systematic reviews

BACKGROUND

Anterior cruciate ligament injury is a common knee joint injury. Anterior cruciate ligament reconstruction is a common surgical treatment to treat anterior cruciate ligament injury. It may have certain advantages to retain the ligament stump during the operation, but the results of systematic evaluation on whether to retain the ligament stump are different. The conclusion is still controversial, and the quality needs to be strictly evaluated.

OBJECTIVE

To evaluate the methodological quality, risk of bias, reporting quality and evidence quality of the systematic review of remnant preservation in anterior cruciate ligament reconstruction, and to provide reference for clinical work.

METHODS

We systematically searched the system evaluations in 8 electronic databases, the languages were limited to Chinese and English, and the time limit was from the establishment of the database to June 2023. Two reviewers independently screened literature and extracted data. The methodological quality, risk of bias, reporting quality and quality of evidence were evaluated by AMSTAR-2, ROBIS, PRISMA and GRADE tools.

RESULTS

A total of 14 systematic reviews were included. The evaluation of results showed that the methodological quality of the included systematic reviews was relatively low, of which 5 were low quality and 9 were critically low quality. A small number of systematic reviews were low risk of bias. The system evaluation reports are relatively complete, but the lack of program registration is a common problem. A total of 111 pieces of clinical evidence were extracted from the included 14 systematic reviews. The quality of evidence was generally low, with only 7 pieces of high-quality evidence, 45 pieces of medium-quality evidence, and the rest were low and very low-quality evidence. Among the reasons for relegation, imprecision is the most common, followed by inconsistency and indirectness. The existing evidence shows that patients after anterior cruciate ligament reconstruction with remnant preservation have certain advantages in knee joint function, joint stability and proprioception recovery, which may be a more effective surgical method. However, it may also increase the incidence of postoperative complications and adverse reactions.

CONCLUSION

Compared with Standard Technique, Remnant Preservation in Anterior Cruciate Ligament Reconstruction has more advantages in restoring joint function and stability and proprioception. But the potential risks should also be considered by surgeons. At present, the quality of evidence is generally low, and the reliability of the conclusion is insufficient. It still needs to be verified and further in-depth research is needed.

Limb Symmetry Index of Single-Leg Vertical Jump vs. Single-Leg Hop for Distance After ACL Reconstruction: A Systematic Review and Meta-analysis

CONTEXT

The limb symmetry index (LSI) is recommended as a milestone of return to play (RTP), and relying on the LSI value of a single-leg hop for distance (SLHD) test may overestimate rehabilitation status. Identifying a more reliable functional test can help to carefully make decisions for RTP.

OBJECTIVE

The aim was to compare the LSI value of the SLHD test with that of a single-leg vertical jump (SLVJ) test after anterior cruciate ligament reconstruction (ACLR) and determine which test provides lower LSI values.

DATA SOURCES

The PubMed, Web of Science, Embase, and Cochrane Library databases were searched from inception to July 2022.

STUDY SELECTION

Observational studies with participants who had both SLHD and SLVJ tests after ACLR and LSI values of an SLHD and SLVJ were included. Disagreements were resolved after discussion between the 2 researchers.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Data on the primary outcomes (LSI values of the SLVJ and SLHD tests) were collected. Means and standard deviations (SDs) for each variable of interest were used to calculate standardized mean differences (SMDs).

RESULTS

A total of 12 studies met the inclusion criteria for the meta-analysis. A total of 587 patients underwent SLHD and SLVJ tests at different time points after ACLR. Compared with the SLHD test, the SLVJ test provided lower LSI values (SMD -0.42; 95% confidence interval (CI) -0.67 to -0.17). Subgroup analysis found that the SLVJ test provided a lower LSI value than the SLHD test in a specific period (approximately 7-18 months after ACLR, SMD -0.53; 95% CI -0.91 to -0.14) and a similar LSI value at other times.

CONCLUSION

The SLVJ test provided lower LSI values in a specific period (7-18 months after ACLR).

Comparison of Impairments, Activity Limitations, Balance, and Quality of Life between Patients with and without Meniscus Repair or Partial Meniscectomy Post-ACL Reconstruction

(1) Background: The anterior cruciate ligament (ACL) is a crucial ligament in the knee joint. This study compares the differences in knee range of motion (ROM), knee proprioception error, balance, function, and quality of life (QOL) among participants with and without meniscus repair or partial meniscectomy nine months post ACL reconstruction. (2) Methods: In this cross-sectional study, 57 male participants were selected through convenience sampling from a tertiary care hospital. Knee flexion and extension ROM were assessed using a digital goniometer; a digital inclinometer was used to assess knee proprioception error; the Y balance test was used to evaluate balance; the lower extremity functional scale (LEFS) was used to assess activity; and QOL was assessed using the ACLQOL questionnaire. (3) Results: There were no significant differences in outcomes except balance. The YB composite score had a moderate negative correlation with knee proprioception error with an R-value of -0.372 **. (4) Conclusions: Nine to 12 months post ACL reconstruction, the isolated ACL reconstruction participants had better lower-quarter single-leg balance than those who underwent ACL reconstruction and meniscal repair or partial meniscectomy. The remaining parameters, like knee ROM, knee proprioception error, LEFS score, and ACLQOL scores, were similar between these two groups.

Test-retest reliability of quantitative sensory testing, active joint position sense, and functional hop testing in amateur adult athletes with unilateral anterior cruciate ligament reconstruction

OBJECTIVES

The somatosensory system fulfils a critical role in functional knee joint stability (FKJS) by providing afferent feedback necessary for neuromuscular control. Individuals with anterior cruciate ligament reconstruction (ACLr) have altered somatosensory function. Somatosensory characteristics are assessed by proprioception and quantitative sensory testing. The purpose of the study was to examine intra-rater and inter-rater reliability of methods used to assess somatosensory characteristics and FKJS in amateur adult athletes with unilateral ACLr.

DESIGN

Repeated measures.

SETTING

University.

PARTICIPANTS

8 female, 4 male with unilateral autogenous ACLr.

MAIN OUTCOME MEASURES

Bilateral measurements at 5 lower extremity locations and the anterior forearm: light touch (LT), vibration sense (VS), pressure pain threshold (PPT); knee active joint position sense (AJPS); adapted crossover hop for distance (ACHD). Intraclass correlation coefficients (ICC) determined reliability, defined as: poor (<0.50), moderate (0.50-0.75), good (0.75-0.90).

RESULTS

ACLr-side intra-rater/inter-rater ICCs ranged: LT, -0.27-0.80/-0.01-0.84; VS, 0.12-0.90/0.25-0.90; PPT, 0.49-0.98/0.86-0.99; AJPS, 0.15-0.79/0.55-0.87; ACHD, 0.98/0.99. Uninjured-side intra-rater/inter-rater ICCs ranged: LT, 0.12-0.66/-0.09-0.64; VS, 0.35-0.89/0.05-0.81; PPT, 0.65-0.99/0.45-0.95; AJPS, 0.07-0.81/0.37-0.99; ACHD, 0.99/0.98.

CONCLUSIONS

Intra-rater and inter-rater reliability was poor to good for both limbs. Overall, PPT and the ACHD demonstrated the highest ICCs. Some somatosensory assessments can be employed with confidence, while others should be used with caution.

The effect of compression and combined compression-tactile stimulation on lower limb somatosensory acuity

Background

Lower limb somatosensation and proprioception are important for maintaining balance. Research has shown that compression garments or exposure to textured surfaces, can enhance somatosensation however, little is known about the effect of combined compression and texture on somatosensory acuity in the lower limb. This study aimed to assess the effects of combined compression socks with a plantar textured sole, on lower limb somatosensory acuity.

Methods

Thirty participants completed a somatosensory acuity task (active movement extent discrimination apparatus; AMEDA) under three conditions: barefoot (control condition), standard knee-high compression sock (compression sock), and knee-high compression sock with internal rubber nodules situated on the sole (textured-compression sock). Somatosensory acuity was assessed between the different sock conditions for the (i) entire group, (ii) high performers, and (iii) low performers. It was hypothesized that low performers would see gains wearing either sock, but the greatest improvement would be in the textured-compression sock condition.

Results

AMEDA scores were not significantly different between conditions when the entire group was analyzed (p = 0.078). The low performers showed an improvement in somatosensory acuity when wearing the compression sock (p = 0.037) and the textured compression sock (p = 0.024), when compared to barefoot, but there was no difference between the two sock conditions (p > 0.05). The high performers did not show any improvement (p > 0.05 for all).

Conclusion

These findings demonstrate that additional sensory feedback may be beneficial to individuals with lower baseline somatosensory acuity but is unlikely to provide benefit for those with higher somatosensory acuity.

Comparison of Pre- and Postoperative Motor-proprioceptive Abilities in Patients with Gonarthrosis

Both surgeons and patients want to achieve a high level of satisfaction and the best possible functional results within a short time after knee TEP surgery. By using a tool that digitally records various measurement parameters of balance and motor function preoperatively and postoperatively on a mobile basis and with little time expenditure, progressive results can be compared. Individual factors can thus be determined and these can influence the progress in regeneration and training progress perioperatively.In a prospective study, 100 patients before and 66 patients after installation of a cement-retained knee TEP were evaluated for the following parameters: balance, maximum strength, and power. All measurements were performed with the KMP measurement platform from MotoSana. The second measurements were performed in each case after a standardised follow-up treatment.It was shown that there are significant relationships between personal factors such as age, height, body weight and with baseline values and performance measures: maximum strength and power. Furthermore, it was shown that postoperative improvement could be achieved for the most part around balance support. All patients who previously had to hold on with one hand or both hands no longer needed support after surgery to maintain the single-leg stance for the specified time of 15 s. For a more detailed analysis of the balance parameters, the samples were adjusted and only the patients who did not hold on for support pre- and postoperatively were counted. In patients with low and medium initial stance, the sway area increased at the second measurement session, and in patients with large sway areas, it decreased, and the stance became more stable. In the area of maximum strength and power, patients with high baseline values still had higher values after AHB compared with the other patients, but lower values compared with their own baseline values.Patients who already had very good motor skills before surgery were able to achieve a greater increase in motor skills compared to the weaker group. However, all patients failed to reach their preoperative baseline values after completion of the AHB. Deficits in balance were still detectable in all groups. By using the presented force plate, measurement-based coordinated rehabilitation procedures are possible during and after completion of the AHB. Rehabilitation with individualised improvement of balance and motor function could be expected to prevent dissatisfaction after knee arthroplasty, e.g. due to muscular imbalance in femoropatellar pain syndromes.

Changes in proprioception at different time points following anterior cruciate ligament injury or reconstruction

PURPOSE

To investigate the changes in 30° and 60° position sense in patients with anterior cruciate ligament (ACL) injury at different time points after injury and reconstruction.

METHODS

Patients were divided into six groups according to time after ACL injury and reconstruction: group A (ACL injury 1.5-6 months), group B (ACL injury 6-12 months), group C (ACL injury > 12 months), group D (postoperative ACL reconstruction 1-6 months), group E (postoperative ACL reconstruction > 6 months), and group F consisting of 14 healthy adults (control group). The ability of the affected leg to reproduce the same joint position during knee flexion was tested using active joint position sense assays to assess proprioception in both the lower extremities of the patient or between groups.

RESULTS

Proprioception decreased rapidly during the early stages of ACL injury. Significant difference in the affected side at 30° compared to the healthy side (Group A: 4.70 (4.78, 9.00) vs 4.15 (3.35, 6.13), P = 0.03; Group B: 2.90 (0.48, 4.56) vs 8.30 (4.18, 10.43), P = 0.001; Group E: 6.25 (2.55, 11.60) vs 9.60 (3.90, 12.73), P = 0.009). However, no significant differences were detected for a double lower limb contrast of 60° (Group A: 5.1 (1.00, 8.00) vs 3.00 (0.75, 3.55), P = 0.044). Finally, the affected side of patients in groups C, D and E had significant differences in position perception at 30° compared with healthy subjects (P < 0.01), and the affected side of patients in groups C and E had significant differences in position sense at 60° compared with healthy subjects (P < 0.01).

CONCLUSION

ACL injury had a greater impact on the patient's 30° position sense, with only a small impact for 60°. Further, the early and middle proprioception recovery stages after ACL injury were the best before surgery. Finally, proprioception recovery training should be performed soon after injury.

Known-group validity of passive knee joint position sense: a comparison between individuals with unilateral anterior cruciate ligament reconstruction and healthy controls

BACKGROUND

Knee joint position sense (JPS) might be negatively affected after injuries to the anterior cruciate ligament (ACL). Recent systematic reviews suggest further investigation of psychometric properties, including validity, of knee JPS tests following ACL reconstruction (ACLR). This study investigated the known-group validity by comparing knee JPS errors between individuals who underwent unilateral ACLR and healthy controls.

METHODS

This cross-sectional study involved 36 men, including 19 after ACLR (ACLR group) and 17 healthy controls (control group). In both groups, the absolute error (AE), constant error (CE) and variable error (VE) of passive knee JPS were calculated in the flexion and extension directions, for two target angles (30° and 60° flexion) per direction. Discriminative validity was evaluated by comparing JPS errors between the operated and non-operated knees in the ACLR group. Known-group validity was evaluated by comparing JPS errors between the operated knees in the ACLR group and the asymptomatic non-dominant knees of healthy controls.

RESULTS

Mean AE, CE and VE for all tests were 4.1°, - 2.3° and 3.6° for the operated knees in the ACLR group, 5.5°, - 2.6° and 3.3° for the non-operated knees in the ACLR group and 4.6°, - 2.6° and 3.3° for the non-dominant knees in the control group, respectively, regardless of the test direction and target angle. The operated knees in the ACLR group did not show significantly greater JPS errors compared to the contralateral knees in the ACLR group and to the non-dominant knees in the control group (p ≥ 0.05). On the other hand, the non-operated knees showed significantly greater AE for the 0°-60° flexion test (p = 0.025) and CE for the 0°-30° flexion test (p = 0.024) than the operated knees in the ACLR group. JPS errors did not significantly differ in the operated knees in the ACLR group based on the direction of movement and the target angle. However, the errors were significantly higher when the knee was moved through a greater range compared to that of a lesser range between the starting and target angles.

CONCLUSION

The ACLR knees did not show greater passive JPS errors than the contralateral or control knees. The direction of movement and target angle did not influence the JPS acuity after ACLR. However, higher JPS errors were evident when the knee was moved through a greater range compared to a lesser range of motion. Further studies investigating the psychometric properties of standardized JPS tests following ACLR are warranted.

Spontaneous healing of acute ACL ruptures: rate, prognostic factors and short-term outcome

INTRODUCTION

Anterior cruciate ligament (ACL) reconstruction is considered the first line treatment in ACL rupture. However, some patients return to high intensity sport activities and show a normal knee function without ACL reconstruction. Therefore, aim of this study was to evaluate the rate and prognostic factors of spontaneous healing in patients with ACL rupture and the short-term functional outcome.

METHODS

The rate, prognostic factors and short-term functional results of spontaneous healing in patients with ACL rupture were evaluated in 381 patients. Morphology of ACL rupture and extent of posterior tibial slope (PTS) were classified by MR- and x-ray imaging. In patients with normal knee stability in anesthesia examination and healed ACL during the arthroscopy 6 weeks after trauma ACL reconstruction was canceled. IKDC -, Tegner Activity Score, KT 1000 testing and radiological characteristics were collected 12 months postoperatively in these patients.

RESULTS

14.17% of the patients with ACL rupture showed a spontaneous healing after 6 weeks. Femoral ACL-rupture (p < 0.02) with integrity of ligament stump > 50% (p < 0.001), without bundle separation (p < 0.001) and decreased PTS (p < 0.001) was found significantly more often in patients with a spontaneous healed ACL. The average IKDC score was high at 84,63 in patients with healed ACL at 1 year follow-up, but KT 1000 testing was inferior compared to non-injured side.

CONCLUSION

Spontaneous healing of a ruptured ACL happened in 14% of the patients. Especially in low-demand patients with femoral single bundle lesions without increased posterior tibial slope delayed ACL surgery should be considered to await the possibility for potential spontaneous ACL healing.

Effectiveness of early onset of rehabilitation on the postural stability after anterior cruciate ligament reconstruction

PURPOSE

The objective of this study was to evaluate the early onset of rehabilitation on restoring the postural stability of patients after anterior cruciate ligament reconstruction (ACLR) at the 3rd postoperative month.

METHODS

Forty patients after ACLR and twenty healthy controls took part in the investigation. The patients were divided into two groups, depending on the start of their proprioceptive rehabilitation program: an experimental group - on the 5th day after the surgery and a control group - on around the 30th postoperative day. Postural stability was investigated by static posturographic tests on stable and foam surfaces with open and closed eyes.

RESULTS

The patients from the experimental group showed lower amplitudes and velocities of the postural sways than the patients from the control group at the 3rd postoperative month. We found that the early start of the proprioceptive rehabilitation affects more the amplitude than the velocity of the postural sway which remains significantly high in both directions compared to the conventional rehabilitation.

CONCLUSION

The early start of the rehabilitation has a beneficial role in the recovery of the postural stability in the 3rd postoperative month, especially in more challenging conditions for keeping the equilibrium, which contributes to the minimizes the risk of a second anterior cruciate ligament injury after patients' return to their usual sport and daily activities routine.

Sacroiliac joint pain increases repositioning error during active straight leg-raising

PURPOSE

This study aimed to compare the repositioning error (RE) of patients with unilateral sacroiliac joint pain (SIJP) to that of patients with low back pain (LBP) and a healthy control (HC) group. Differences between the symptomatic and asymptomatic sides were also investigated.

METHODS

Sixty-six patients with SIJP, LBP, and HC were included in this study. An active straight leg-raising repositioning test (ASLR-Rt) was performed. ASLR was performed three times each on the left and right sides, targeting a set base angle. RE was calculated as the difference between the base angle and the participant's attempt to adjust the target angle. RE was expressed as constant error (CE) and absolute error (AE).

RESULTS

The CE of the SIJP group (median [interquartile range]) (6.9 [4.6‒10.4]) was significantly higher than that in the LBP group (3.2 [1.3‒7.1]) and the HC group (2.7 [0.3‒4.6]) (P = 0.009, d = 0.91, P < 0.001, d = 1.30). The AE of the SIJP group (7.3[5.0‒10.4]) was also significantly higher than that in the LBP (3.7[2.8‒7.1]) and HC groups (3.0[1.9‒4.2]) (P = 0.003, d = 1.04; P = 0.001, d = 1.57). Comparing the symptomatic and asymptomatic sides in the SIJP group, the symptomatic side (8.0[6.0‒10.6]) was significantly higher than the asymptomatic side (5.7[3.6‒8.1]) in terms of CE (P = 0.05, d = 0.51).

CONCLUSION

Patients with SIJP increased RE during ASLR, which may be related to impaired proprioception and decreased motor control.

A prospective study of joint position sense after anterior cruciate ligament injury, reconstruction with a bone-patella tendon-bone graft, and rehabilitation

BACKGROUND

Disruption of the anterior cruciate ligament (ACL) is associated with significant biomechanical and neuromuscular changes including deficits in joint proprioception. While previous studies have assessed joint position sense (JPS) in ACL deficient knees, methods have varied and few have done so with prospective study designs. The specific aim of this investigation was to determine the effect(s) of ACL reconstruction and recovery time may have on JPS.

METHODS

In this prospective study, we assess the effects of ACL reconstruction and rehabilitation on joint position sense in a temporal study. Twelve patients with unilateral ACL injuries were assessed pre-operatively and at 2, 4, 8 months post-op. JPS measurements were performed, while the subject was standing, with passive-active (P-A) and active-active (A-A) tests. Comparisons between the injured/reconstructed and contralateral, uninjured knee were evaluated in terms of real and absolute mean errors.

RESULTS

There were no statistically significant differences between the injured/reconstructed and contralateral/normal side with P-A or A-A testing at 2, 4, or 8 months.

CONCLUSION

We conclude that there is no difference in joint position sense between the injured and contralateral leg after ACL disruption and reconstruction beginning as early as 2 months post-op. This study provides further evidence that knee proprioception is not altered by ACL injury and reconstruction.

LEVEL OF EVIDENCE

II.

Quadriceps Dysfunction Following Joint Preservation Surgery: A Review of the Pathophysiologic Basis and Mitigation Strategies

PURPOSE OF REVIEW

To characterize quadriceps muscle dysfunction associated with knee joint preservation surgery, with a focus on its pathophysiology and promising approaches to mitigate its impact on clinical outcomes.

RECENT FINDINGS

Quadriceps dysfunction (QD) associated with knee joint preservation surgery results from a complex interplay of signaling, related to changes within the joint and from those involving the overlying muscular envelope. Despite intensive rehabilitation regimens, QD may persist for many months postoperatively and negatively impact clinical outcomes associated with various surgical procedures. These facts underscore the need for continued investigation into the potential detrimental effects of regional anesthetic and intraoperative tourniquet use on postoperative quadriceps function, with an outward focus on innovation within the field of postoperative rehabilitation. Neuromuscular stimulation, nutritional supplementation, cryotherapy, blood flow restriction (BFR), and open-chain exercises are all potential additions to postoperative regimens. There is compelling literature to suggest that these modalities are efficacious and may diminish the magnitude and duration of postoperative QD. A clear understanding of QD, with respect to its pathophysiology, should guide perioperative treatment and rehabilitation strategies and influence ongoing rehabilitation-based research and innovation. Moreover, clinicians must appreciate the magnitude of QD's effect on diminished clinical outcomes, risk for re-injury and patients' ability (or inability) to return to pre-injury level of activity following knee joint preservation procedures.

A reliable and efficient adaptive Bayesian method to assess static lower limb position sense

BACKGROUND

Lower limb proprioception is critical for maintaining stability during gait and may impact how individuals modify their movements in response to changes in the environment and body state, a process termed "sensorimotor adaptation". However, the connection between lower limb proprioception and sensorimotor adaptation during human gait has not been established. We suspect this gap is due in part to the lack of reliable, efficient methods to assess global lower limb proprioception in an ecologically valid context.

NEW METHOD

We assessed static lower limb proprioception using an alternative forced choice task, administered twice to determine test-retest reliability. Participants stood on a dual-belt treadmill which passively moved one limb to stimulus locations selected by a Bayesian adaptive algorithm. At the stimulus locations, participants judged relative foot positions and the algorithm estimated the point of subjective equality (PSE) and the uncertainty of lower limb proprioception.

RESULTS

Using the Bland-Altman method, combined with Bayesian statistics, we found that both the PSE and uncertainty estimates had good reliability.

COMPARISON WITH EXISTING METHOD(S)

Current methods assessing static lower limb proprioception do so within a single joint, in non-weight bearing positions, and rely heavily on memory. One exception assessed static lower limb proprioception in standing but did not measure reliability and contained confounds impacting participants' judgments, which we experimentally controlled here.

CONCLUSIONS

This efficient and reliable method assessing lower limb proprioception will aid future mechanistic understanding of locomotor adaptation and serve as a useful tool for basic and clinical researchers studying balance and falls.

A reliable and efficient adaptive Bayesian method to assess static lower limb position sense

Background

Lower limb proprioception is critical for maintaining stability during gait and may impact how individuals modify their movements in response to changes in the environment and body state, a process termed "sensorimotor adaptation". However, the connection between lower limb proprioception and sensorimotor adaptation during human gait has not been established. We suspect this gap is due in part to the lack of reliable, efficient methods to assess global lower limb proprioception in an ecologically valid context.

New Method

We assessed static lower limb proprioception using an alternative forced choice task, administered twice to determine test-retest reliability. Participants stood on a dual-belt treadmill which passively moved one limb to stimulus locations selected by a Bayesian adaptive algorithm. At the stimulus locations, participants judged relative foot positions and the algorithm estimated the point of subjective equality (PSE) and the uncertainty of lower limb proprioception.

Results

Using the Bland-Altman method, combined with Bayesian statistics, we found that both the PSE and uncertainty estimates had good reliability.

Comparison with Existing Methods

Current methods assessing static lower limb proprioception do so within a single joint, in non-weight bearing positions, and rely heavily on memory. One exception assessed static lower limb proprioception in standing but did not measure reliability and contained confounds impacting participants' judgments, which we experimentally controlled here.

Conclusions

This efficient and reliable method assessing lower limb proprioception will aid future mechanistic understanding of locomotor adaptation and serve as a useful tool for basic and clinical researchers studying balance and falls.

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.

Primary Proximal ACL Repair: A Biomechanical Evaluation of Different Arthroscopic Suture Configurations

Purpose: Several suture techniques have been described in the past for direct ACL repair with poor healing capacity and a high re-rupture rate. Therefore, we investigated a refixation technique for acute primary proximal ACL repair. The purpose of this study is to compare the biomechanical properties of different suture configurations using a knotless anchor. Methods: In this study, 35 fresh-frozen porcine knees underwent proximal ACL refixation. First, in 10 porcine femora, the biomechanical properties of the knotless anchor, without the ligament attached, were tested. Then, three different suture configurations were evaluated to reattach the remaining ACL. Using a material testing machine, the structural properties were evaluated for cyclic loading followed by loading to failure. Results: The ultimate failure load of the knotless anchor was 198, 76 N ± 23, 4 N significantly higher than all of the tested ACL suture configurations. Comparing the different configurations, the modified Kessler–Bunnell suture showed significant superior ultimate failure load, with 81, 2 N ± 15, 6 N compared to the twofold and single sutures (50, 5 N ± 14 N and 37, 5 ± 3, 8 N). In cyclic loading, there was no significant difference noted for the different configurations in terms of stiffness and elongation. Conclusions: The results of this in vitro study show that when performing ACL suture using a knotless anchor, a modified Kessler–Bunnell suture provides superior biomechanical properties than a single and a twofold suture. Within this construct, no failure at the bone–anchor interface was seen. Clinical relevance: Since primary suture repair techniques of ACL tears have been abandoned because of inconsistent results, ACL reconstruction remains the gold standard of treating ACL tears. However, with the latest improvements in surgical techniques, instrumentation, hardware and imaging, primary ACL suture repair might be a treatment option for a select group of patients. By establishing an arthroscopic technique in which proximal ACL avulsion can be reattached, the original ACL can be preserved by using a knotless anchor and a threefold suture configuration. Nevertheless, this technique provides an inferior ultimate failure load compared to graft techniques, so a careful rehabilitation program must be followed if using this technique in vivo.

Lower Extremity Somatosensory Function Throughout Concussion Recovery: A Prospective Cohort Study

OBJECTIVE

Balance impairments may suggest somatosensory disruption beyond concussion clinical recovery, but somatosensory subsystems have never been directly assessed. Our objective was to examine somatosensory function between individuals with a concussion and healthy matched-controls at acute (<7 days) and asymptomatic (<72 hours of being symptom-free) time points.

SETTING

Laboratory.

PARTICIPANTS

Participants with a concussion and matched controls ( n = 24; 58% male, age: 19.3 ± 1.1 years, mass: 70.3 ± 16.4 kg, height: 177.3 ± 12.7 cm).

DESIGN

Prospective cohort.

MAIN MEASURES

Somatosensory assessments on the dominant limb at both time points included: (1) plantar touch sensation threshold via Semmes-Weinstein monofilaments, (2) plantar pressure pain threshold via algometry, and (3) knee absolute passive joint repositioning (PJR) error via Biodex across 3 arcs (105°-75°, 30°-60°, 90°-45° knee-flexion). We used mixed-model analyses of variance, post hoc Tukey honestly significant difference t tests with mean difference, 95% CI, and Hedges' g effect sizes to examine outcomes.

RESULTS

Touch sensation had a group effect with the concussion cohort needing 0.95 grams of force (gf) more relative to controls (95% CI: 0.03 to 1.87; P = .043). No touch sensation interaction was present, but medium and large effects were observed for greater gf needed among the concussed cohort at the acute (1.11 gf; 95% CI: 0.17 to 2.05; g = 0.96) and asymptomatic time points (0.79 gf; 95% CI: -0.15 to 1.73; g = 0.73). No plantar pressure pain threshold effects were observed ( P ≥ .311), with negligible pressure difference magnitudes at the acute (0.26 pound force [lbf]/cm 2 ; 95% CI: -1.54 to 2.06; g = 0.13) and medium magnitudes at the asymptomatic time points (0.99 lbf/cm 2 ; 95% CI: -0.81 to 2.80; g = 0.42) for the concussed cohort needing more pressure to detect pain. The 30° to 60° PJR had a time effect, with asymptomatic time point having 3.12° better accuracy (95% CI: 1.23° to 5.02; P = .002). The concussed cohort had small-to-medium magnitude differences relative to controls at the acute time point for PJR during 105° to 75° (0.89°; g = 0.30) and 90° to 45° (0.62°; g = 0.17), but not 30° to 60° (-1.75°; g = -0.40).

CONCLUSIONS

Individuals with a concussion exhibited large effects for diminished plantar touch sensation and small to medium effects for inhibited plantar pressure pain sensation compared with controls, which may indicate altered somatosensory function. Negligible PJR differences suggest knee joint position sense is not altered post-concussion. Pre- and postconcussion examination is warranted to understand causal somatosensory mechanisms.

The ligamentum mucosum: A new classification

The ligamentum mucosum (LM) is a ligamentous structure within the synovial layer of the knee joint capsule. For a long time LM was perceived as the vestigial remnant from the embryological development of the knee. However, last years have shown increased interest in this structure due to its potentially significant clinical role. Fifty-one, 12 females (mean age 83.1 ± 3.4 years) and 39 males (mean age 84.2 ± 6.8 years) fixed in 10% formalin were examined. Upon dissection, the following morphological features of the LM were assessed: the types of LM, morphometric measurement and histological analysis of each type. The LM was present in 66.7% of all examined specimens. Three different types were recognized: Type I (55.9%)-single band with attachment to the intercondylar notch, Type IIa-bifurcated ligament with attachment to the anterior cruciate ligament, Type IIb-bifurcated ligament with both attachments to the intercondylar notch, Type III-double ligament with two independent bands and attachments to the intercondylar notch and to the knee joint capsule. The LM is variable and probably evolutionary changes are the reason. In our study we propose the new clinically useful classification supported by its anatomical and histological characteristics. Type IIa seems to be the most important from the clinical point of view, as it may be responsible for clinical issues and should be paid attention while diagnosing patients suffering from anterior cruciate ligament torn or anterior knee pain.

Is augmentation the best solution in partial anterior cruciate ligament tears? A literature systematic review and meta-analysis

Purpose

The appropriate management of partial anterior cruciate ligament (ACL) tears is still debated. There is a tendency in orthopedic clinical practice to prefer complete ACL reconstruction, while few surgeons perform ACL augmentation. The purpose of the present study is to evaluate the current evidence on the effectiveness of ACL augmentation compared with standard ACL reconstruction to assess whether ACL augmentation may be the treatment of choice in partial ACL injury.

Methods

According to PRISMA guidelines, literature research was performed in PubMed/Medline, Cochrane Library, Embase, Scopus, and Web of Science databases. A PICOS model was used, and a preliminary search resulted in 1101 articles. The methodological quality was assessed through ROBINS-I. A meta-analysis was conducted on postoperative Tegner, Lysholm scores and KT-1000 values between ACL augmentation and ACL reconstruction, and a p < 0.05 has been assumed as statistically significant. PROSPERO, ID: CRD42022343502.

Results

Seven papers were included. A total of 472 knees underwent ACL reconstruction, and 311 underwent ACL augmentation. A statistically significant discrepancy was found in the postoperative Tegner score in favor of ACL augmentation compared with ACL reconstruction (p < 0.05). Regarding the postoperative Lysholm score and KT-1000 measurement, no statistically significant difference was shown between ACL reconstruction and ACL augmentation (p > 0.05).

Conclusions

ACL augmentation has proved to be an effective and safe procedure and should be preferred to ACL reconstruction in partial ACL tears for the tendency to achieve better functional outcomes.

Dual-Task Interference Slows Down Proprioception

It is well-known that multitasking impairs the performance of one or both of the concomitant ongoing tasks. Previous studies have mainly focused on how a secondary task can compromise visual or auditory information processing. However, despite dual tasking being critical to motor performance, the effects of dual-task performance on proprioceptive information processing have not been studied yet. The purpose of the present study was, therefore, to investigate whether sensorimotor task performance would be affected by the dual task and if so, in which phase of the sensorimotor task performance would this negative effect occur. The kinematic variables of passive and active knee movements elicited by the leg drop test were analyzed. Thirteen young adults participated in the study. The dual task consisted of performing serial subtractions. The results showed that the dual task increased both the reaction time to counteract passive knee-joint movements in the leg drop test and the threshold to detect those movements. The dual task did not affect the speed and time during the active knee movement and the absolute angle error between the final and the target knee angles. Furthermore, the results showed that the time to complete the sensorimotor task was prolonged in dual tasking. Our findings suggest that dual tasking reduces motor performance due to slowing down proprioceptive information processing without affecting movement execution.

Four-Week Application of Kinesiotaping Improves Proprioception, Strength, and Balance in Individuals With Complete Anterior Cruciate Ligament Rupture

ABSTRACT

Kielė, D and Solianik, R. Four-week application of kinesiotaping improves proprioception, strength, and balance in individuals with complete anterior cruciate ligament rupture. J Strength Cond Res 37(1): 213-219, 2023-Kinesiotaping (KT) is common in musculoskeletal rehabilitation, but whether it is efficacious for surgically untreated anterior cruciate ligament (ACL) ruptures is unknown. Therefore, we evaluated whether a strategy of physiotherapy plus KT would be superior to a strategy of physiotherapy alone on subsequent proprioception and motor function. Men aged 28.1 ± 6.7 years with complete ACL ruptures were randomized to either a control (physiotherapy) or an experimental group (physiotherapy + KT) for a 4-week period. Changes in balance were assessed on the injured leg using a force platform. Knee angle reproduction, maximal voluntary contraction (MVC), and rate of force development (RFD) were measured using dynamometry, and pain was recorded using a visual analog scale. Decreases in knee pain and improvements in angle reproduction were observed in both groups ( p < 0.05), with a greater effect on angle reproduction in the experimental group ( p < 0.05). Both groups demonstrated increased isometric knee flexor MVC and RFD values ( p < 0.05), but an increase in RFD of the knee extensors was observed only in the experimental group ( p < 0.05). Furthermore, the MVC of concentric knee flexors at 60°·s -1 increased only in the experimental group ( p < 0.05), whereas concentric MVC at 180°·s -1 -resulting in greater hamstring-to-quadriceps ratios-increased in both groups ( p < 0.05). Balancing ability on the injured leg increased only in the experimental group ( p < 0.05). Thus, KT plus physiotherapy was beneficial in the treatment of proprioception, strength, and static balance in these individuals with an ACL rupture.

Effects of body orientation and direction of movement on a knee joint angle reproduction test in healthy subjects: An experimental study

BACKGROUND

Joint position sense test assess patient mobility and proprioceptive ability. Yet, application used under different conditions may biases reproduction error resulting in different therapeutic consequences.

OBJECTIVE

To investigate knee angle reproduction test under different test conditions.

METHODS

25 healthy subjects (mean ± SD, age = 25 ± 2 years, activity level: 9 ± 2 training hours/week) performed knee angle reproduction test in the sitting and prone position, while changing the knee angle starting (i) from flexion and (ii) extension, (iii) inducing vibration on the semitendinosus tendon.

RESULTS

Absolute mean knee angle reproduction error showed significant difference for body position and vibration (Position: 95% CI 0.71 to 2.32; p< 0.001. No Vibration & Vibration: 95% CI -1.71 to -0.12; p= 0.027). Relative knee angle reproduction error was significant different in all conditions (No Vibration & Vibration: 95% CI -3.30 to -0.45; p= 0.010. Body orientation: 95% CI 1.08 to 3.93; p< 0.001. Direction of movement: 95% CI 0.56 to 3.41; p= 0.007).

CONCLUSION

Body orientation and movement direction influence the resulting knee angle reproduction error in healthy subjects. Practitioners are advised to use standardised test procedures when comparing different within- and between-patient results.

TRIAL REGISTRATION

DOI 10.17605/OSF.IO/AFWRP.

Quadriceps Weakness is Associated with Neuroplastic Changes Within Specific Corticospinal Pathways and Brain Areas After Anterior Cruciate Ligament Reconstruction: Theoretical Utility of Motor Imagery-Based Brain-Computer Interface Technology for Rehabilitation

Persistent quadriceps weakness is a problematic sequela of anterior cruciate ligament reconstruction (ACLR). The purposes of this review are to summarize neuroplastic changes after ACL reconstruction; provide an overview of a promising interventions, motor imagery (MI), and its utility in muscle activation; and propose a framework using a brain-computer interface (BCI) to augment quadriceps activation. A literature review of neuroplastic changes, MI training, and BCI-MI technology in postoperative neuromuscular rehabilitation was conducted in PubMed, Embase, and Scopus. Combinations of the following search terms were used to identify articles: "quadriceps muscle," "neurofeedback," "biofeedback," "muscle activation," "motor learning," "anterior cruciate ligament," and "cortical plasticity." We found that ACLR disrupts sensory input from the quadriceps, which results in reduced sensitivity to electrochemical neuronal signals, an increase in central inhibition of neurons regulating quadriceps control and dampening of reflexive motor activity. MI training consists of visualizing an action, without physically engaging in muscle activity. Imagined motor output during MI training increases the sensitivity and conductivity of corticospinal tracts emerging from the primary motor cortex, which helps "exercise" the connections between the brain and target muscle tissues. Motor rehabilitation studies using BCI-MI technology have demonstrated increased excitability of the motor cortex, corticospinal tract, spinal motor neurons, and disinhibition of inhibitory interneurons. This technology has been validated and successfully applied in the recovery of atrophied neuromuscular pathways in stroke patients but has yet to be investigated in peripheral neuromuscular insults, such as ACL injury and reconstruction. Well-designed clinical studies may assess the impact of BCI on clinical outcomes and recovery time. Quadriceps weakness is associated with neuroplastic changes within specific corticospinal pathways and brain areas. BCI-MI shows strong potential for facilitating recovery of atrophied neuromuscular pathways after ACLR and may offer an innovative, multidisciplinary approach to orthopaedic care.

Level of Evidence

V, expert opinion.

Current study on the influence of psychological factors on returning to sports after ACLR

It is considered that psychological factors are important in determining exercise regression outcomes of patients with anterior cruciate ligament reconstruction (ACLR). This review summarizes the definition and research progress of current undefined psychological factors related to returning to sports (RTS) after ACLR, as well as the application of corresponding measuring scales, and common psychological interventions in the field. The aim is to understand and clarify the impact of psychological factors in the ACL injury and rehabilitation, and to provide a theoretical basis for the application of psychological evaluation and intervention in the later stage. It is believed that there are still many prospects for the research in this field.

Knee osteoarthritis, joint laxity and PROMs following conservative management versus surgical reconstruction for ACL rupture: a meta-analysis

INTRODUCTION

Patients whose rupture of the anterior cruciate ligament (ACL) can be managed conservatively or undergo reconstruction surgery.

SOURCE OF DATA

Current scientific literature published in Web of Science, PubMed and Scopus.

AREAS OF AGREEMENT

Several studies published by July 2022 compare surgical and conservative management following ACL rupture. The latest evidence suggests that surgical management may expose patients to an increased risk of early-onset knee osteoarthritis (OA).

AREAS OF CONTROVERSY

The state of art does not recommend a systematic ACL reconstruction to all patients who tore their ACL. After the initial trauma, surgical reconstruction may produce even greater damage to the intra-articular structures compared to conservative management.

GROWING POINTS

The state of art does not recommend systematic surgical reconstruction to all patients who tore their ACL. The present study compared surgical reconstruction versus conservative management for primary ACL ruptures in terms of joint laxity, patient reported outcome measures (PROMs) and rate of osteoarthritis.

AREAS TIMELY FOR DEVELOPING RESEARCH

ACL reconstruction provides significant improvement in joint laxity compared to conservative management, but is associated with a significantly greater rate of knee osteoarthritis, despite similar results at PROM assessment.

High return to sport rate and few re-ruptures at long term in professional footballers after anterior cruciate ligament reconstruction with hamstrings

PURPOSE

Anterior cruciate ligament (ACL) ruptures are considered high burden injuries in sports with high pivotal activity, especially for professional footballers. A lack of evidence exists about long-term follow up of professional elite athletes who underwent ACL reconstruction. The purpose of the study is to analyze the return to play and the career of professional footballers who underwent ACL reconstruction with hamstrings, to evaluate re-rupture and reoperation at either indexed and contralateral knee, and to assess the long-term clinical subjective outcomes and satisfaction.

METHODS

Twenty-eight professional footballers that underwent 33 ACL reconstructions were retrospectively included in the study. All surgical interventions were performed using hamstring tendons graft and an over the top technique. Inclusion criteria were: inability to compete due to joint instability caused by total or subtotal ACL lesion, patients contracted to a professional football team at time of surgery. Exclusion criteria were: multi-ligament reconstruction or concomitant meniscal allograft transplantation. Patients were contacted by phone and a brief questionnaire about surgery was administered. Subsequently, a Lysholm knee scoring scale was obtained. After that, an online research was performed on publicly available websites in order to retrieve information of the patients included after surgery.

RESULTS

In all cases, ACL Reconstruction was performed with hamstring tendons using a non-anatomic Double-Bundle technique in 16 cases (49%), an Over-The-Top Single-Bundle technique in 9 cases (27%), and an Over-The-Top Single-Bundle plus Lateral Plasty technique in 8 cases (24%); moreover, a meniscal lesion was present in 20 cases (61%). Three (9%) of the 33 ACL reconstruction failed (2/16 Double-Bundle, 1/9 Single- Bundle, 0/8 Single-Bundle + Lateral Plasty; p = n.s.), with two of them within 12 months from surgery. Other procedures, mainly arthroscopic meniscectomies, were performed in 10 cases (30%). The first official match was played after an average of 8.0 ± 3.6 (4.6-18.2) months in 31 cases (94%). Patients were evaluated after 12.6 ± 3.3 years (6.7-17.5) from the indexed ACL reconstruction. The average Lysholm score was 94.2 ± 8.3.

CONCLUSIONS

In our small case-series, professional soccer players were able to return to play at a competitive level with a hamstrings over the top technique. Patients with long careers had a high percentage of reoperation on the contralateral knee.

LEVEL OF EVIDENCE

IV.

Bridge-Enhanced Anterior Cruciate Ligament Repair for Mid-Substance Tear With Concomitant Lateral Meniscus Radial Repair

In recent years, repair of the injured anterior cruciate ligament (ACL) has been subject to a renewed interest as novel arthroscopic techniques have been developed. Specifically, the bridge-enhanced ACL repair is a technique composed of a resorbable protein-based implant combined with autologous blood that is used to bridge the gap between 2 torn edges of a mid-substance ACL tear. This implant is believed to help facilitate healing of a primary suture repair and suture cinch and has since demonstrated noninferiority to ACL reconstruction with autograft at 2-year follow-up. The purpose of this Technical Note is to describe a step-by-step surgical technique of a mid-substance ACL repair using the bridge-enhanced ACL repair system in a case with a concomitant lateral meniscus radial repair.

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.

Limb and sex-related differences in knee muscle co-contraction exist 3 months after anterior cruciate ligament reconstruction

Interlimb and sex-based differences in gait mechanics and neuromuscular control are common after anterior cruciate ligament reconstruction (ACLR). Following ACLR, individuals typically exhibit elevated co-contraction of knee muscles, which may accelerate knee osteoarthritis (OA) onset. While directed (medial/lateral) co-contractions influence tibiofemoral loading in healthy people, it is unknown if directed co-contractions are present early after ACLR and if they differ across limbs and sexes. The purpose of this study was to compare directed co-contraction indices (CCIs) of knee muscles in both limbs between men and women after ACLR. Forty-five participants (27 men) completed overground walking at a self-selected speed 3 months after ACLR during which quadriceps, hamstrings, and gastrocnemii muscle activities were collected bilaterally using surface electromyography. CCIs of six muscle pairs were calculated during the weight acceptance interval. The CCIs of the vastus lateralis/biceps femoris muscle pair (lateral musculature) was greater in the involved limb (vs uninvolved; p = 0.02). Compared to men, women exhibited greater CCIs in the vastus medialis/lateral gastrocnemius and vastus lateralis/lateral gastrocnemius muscle pairs (p < 0.01 and p = 0.01, respectively). Limb- and sex-based differences in knee muscle co-contractions are detectable 3 months after ACLR and may be responsible for altered gait mechanics.

Changes in Dynamic Postural Stability After ACL Reconstruction: Results Over 2 Years of Follow-up

Background:

The anterior cruciate ligament (ACL) is crucial for knee proprioception and postural stability. While ACL reconstruction (ACLR) and rehabilitation improve postural stability, the timing in improvement of dynamic postural stability after ACLR remains relatively unknown.

Purpose:

To evaluate changes in dynamic postural stability after ACLR out to 24 months postoperatively.

Study Design:

Case series; Level of evidence, 4.

Methods:

Patients undergoing ACLR were prospectively enrolled, and dynamic postural stability was assessed within 2 days before surgery, at 3-month intervals postoperatively to 18 months, then at 24 months. Measurements were made on a multidirectional platform tracking the patient’s center of mass based on pelvic motion. The amount of time the patient was able to stay on the platform was recorded, and a dynamic motion analysis score, reflecting the patient’s ability to maintain one’s center of mass, was generated overall and in 6 independent planes of motion.

Results:

A total of 44 patients with a mean age of 19.7 ± 6.2 years completed the study protocol. Overall mean dynamic postural stability improved significantly at 3, 6, 9, and 12 months after surgery, with continued improvement out to 24 months. Notable improvements occurred in medial/lateral and anterior/posterior stability from baseline to 6 months postoperatively, while internal/external rotation and flexion/extension stability declined initially after surgery from baseline to 3 months postoperatively before stabilizing to the end of the study period.

Conclusion:

Overall dynamic postural stability significantly improved up to 12 months after ACLR. Improvement in postural stability occurred primarily in the medial/lateral and anterior/posterior planes of motion, with initial decreases in the flexion/extension and internal/external rotational planes of motion.

Risk factors of young males with physically demanding occupations having accumulated damage of anterior cruciate ligament

Objective

To present the clinical characteristics of accumulated anterior cruciate ligament (ACL) damage among young male patients undergoing routine exercise, and to evaluate the related risk factors.

Methods

A retrospective study involving ACL‐accumulated damage from June 2015 to December 2019 was conducted. Baseline characteristics, such as age, body mass index (BMI), training parameters, and clinical signs, were recorded. The results of the radiologic examinations and related standardized tests were obtained to evaluate the research outcomes. These results were compared using Student's t‐test or Chi‐square test, and the impact of risk factors on the patient's injury were analyzed.

Results

A total of 86 men with accumulated ACL damage were included in this study. Exercise pain (86 [100%]), synovitis (80 [93.0%]), and intra‐articular effusion (79 [91.9%]) were the most common clinical symptoms. Loosening of ligaments, decreased tension, mild hyperplasia, and intercondylar fossa effusion were observed using radiography, magnetic resonance imaging, and arthroscopy. Age, BMI, training intensity, length of training, and knee hyperextension were identified as risk factors for accumulated ACL damage.

Conclusion

This study suggests that accumulated ACL damage has differentiated clinical symptoms, imaging features, and risk factors compared to common ACL injuries.

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.

Brain Response to a Knee Proprioception Task Among Persons With Anterior Cruciate Ligament Reconstruction and Controls

Knee proprioception deficits and neuroplasticity have been indicated following injury to the anterior cruciate ligament (ACL). Evidence is, however, scarce regarding brain response to knee proprioception tasks and the impact of ACL injury. This study aimed to identify brain regions associated with the proprioceptive sense of joint position at the knee and whether the related brain response of individuals with ACL reconstruction differed from that of asymptomatic controls. Twenty-one persons with unilateral ACL reconstruction (mean 23 months post-surgery) of either the right (n = 10) or left (n = 11) knee, as well as 19 controls (CTRL) matched for sex, age, height, weight and current activity level, performed a knee joint position sense (JPS) test during simultaneous functional magnetic resonance imaging (fMRI). Integrated motion capture provided real-time knee kinematics to activate test instructions, as well as accurate knee angles for JPS outcomes. Recruited brain regions during knee angle reproduction included somatosensory cortices, prefrontal cortex and insula. Neither brain response nor JPS errors differed between groups, but across groups significant correlations revealed that greater errors were associated with greater ipsilateral response in the anterior cingulate (r = 0.476, P = 0.009), supramarginal gyrus (r = 0.395, P = 0.034) and insula (r = 0.474, P = 0.008). This is the first study to capture brain response using fMRI in relation to quantifiable knee JPS. Activated brain regions have previously been associated with sensorimotor processes, body schema and interoception. Our innovative paradigm can help to guide future research investigating brain response to lower limb proprioception.

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.

Wavelet analysis reveals differential lower limb muscle activity patterns long after anterior cruciate ligament reconstruction

The purpose of this study was to test whether differences in muscle activity patterns between anterior cruciate ligament-reconstructed patients (ACLR) and healthy controls could be detected 10 to 15 years post-surgery using a machine learning classification approach. Eleven ACLR subjects and 12 healthy controls were recruited from an ongoing prospective randomized clinical trial. Surface electromyography (EMG) signals were recorded from gastrocnemius medialis and lateralis, tibialis anterior, vastus medialis, rectus femoris, biceps femoris, and semitendinosus muscles. Muscle activity was analyzed using wavelet analysis and examined within four sub-phases of the hop test, as well as an average of the task as a whole. K-nearest neighbor machine learning combined with a leave-one-out validation was used to classify the muscle activity patterns as either ACLR or Control. When muscle activity was averaged across the whole hop task, activity patterns for all muscles except the tibialis anterior were identified as being different between the study cohorts. ACLR patients demonstrated continuous muscle activities that spanned take-off, airborne, and landing hop phases versus healthy controls who displayed timed and regulated islets of muscle activities specific to each hop phase. The most striking features were 25-50% greater relative quadriceps intensity and approximately 66% diminished biceps femoris intensity in ACLR patients. The current findings are in contrast to previous work using conventional co-contraction and muscle activation onset EMG measures of the same dataset, underscoring the sensitivity and potential of the wavelet approach coupled with machine learning to reveal meaningful adaptation strategies in this at-risk population.

Measuring the force perception in knee flexor/ extensor muscles in patients with anterior cruciate ligament injury and healthy subjects

BACKGROUND

Force perception as a contributor to the neuromuscular control of the knee joint may be altered after anterior cruciate ligament (ACL) injury.

OBJECTIVE

This study aimed to compare the force perception accuracy in the knee joints of patients with ACL injury and healthy subjects.

METHODS

Twenty-six patients with ACL injury and 26 healthy subjects participated in this case-control study. Participants were asked to produce 50% of the maximum voluntary isometric contraction of the knee muscles as a target force and reproduce it in their limbs in flexion and extension directions.

RESULTS

There were significant interactions between group and condition as well as group, condition, and limb in the force perception error respectively (P< 0.05). The highest amount of error was seen in the contralateral limb of the ACL injury group when the reference force was produced in the injured limb (P< 0.05).

CONCLUSION

The findings revealed that the force perception accuracy in the knee flexor/extensor muscles of individuals with ACL injury is impaired. Moreover, error is most evident when the patient produces force in the injured limb and replicates it in the uninjured limb in both flexion and extension directions. Therefore, the rehabilitation programs should encompass neuromuscular training in both quadriceps and hamstrings after ACL injury.

An obstacle clearance test for evaluating sensorimotor control after anterior cruciate ligament injury: A kinematic analysis

Sensorimotor deficits, particularly proprioceptive, are often reported following rupture of the anterior cruciate ligament (ACL). High secondary injury rates and long-term negative consequences suggest that these deficits are not properly identified using current assessment methods. We explored a novel obstacle clearance test to evaluate sensorimotor control in individuals following ACL reconstruction (ACLR) and rehabilitation. Thirty-seven post-ACLR individuals, 23 nonathletic asymptomatic controls (CTRL), and 18 elite athletes stepped over a hurdle-shaped obstacle, downward vision occluded, aiming for minimal clearance. Kinematic outcomes (3D motion capture) for the leading and trailing legs, for two unpredictably presented obstacle heights, were categorized into Accuracy: vertical foot clearance and minimal distance from the obstacle; Variability: end-point and hip/knee trajectory; and Symmetry: trunk/hip/knee crossing angles, hip-knee-ankle movement, and velocity curves. Accuracy was worse for CTRL compared with both other groups. ACLR had less leading and trailing vertical foot clearance with their injured compared with their noninjured leg. ACLR and athletes had less crossing knee flexion in their injured/nondominant legs compared with their contralateral leg, both leading and trailing. ACLR showed greater trunk flexion when crossing with their injured leg, both leading and trailing. For the leading leg, ACLR showed greater asymmetry for the hip-knee-ankle velocity curve compared with elite athletes. Trailing leg trajectory variability was lower for ACLR compared with CTRL and athletes for higher obstacles. Clinical significance: Sensorimotor deficits in individuals post-ACLR were reflected by greater asymmetry and less variable (more stereotypical) trajectories rather than limb positioning ability. This consideration should be addressed in clinical evaluations.