Osteoarthritis prevalence following anterior cruciate ligament reconstruction: a systematic review and numbers-needed-to-treat analysis

Evaluating Criteria for Symptoms Suggestive of Early Osteoarthritis Over Two Years Post-Anterior Cruciate Ligament Reconstruction: Data From the New Zealand Anterior Cruciate Ligament Registry

OBJECTIVE

The objectives were to determine the prevalence of meeting criteria for symptoms suggestive of early osteoarthritis (OA) after anterior cruciate ligament reconstruction (ACLR) and to characterize the longitudinal changes in these symptoms during the first two years post-ACLR.

METHODS

We analyzed data from 10,231 patients aged 14 to 40 years in the New Zealand ACL Registry who completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) at 6, 12, and 24 months post-ACLR. Symptoms suggestive of early OA were defined as scoring ≤85% on at least two of four KOOS subscales. Longitudinal patterns of change were categorized as persistent, resolution, new, inconsistent, or no symptoms across the three visits. Prevalence and odds ratios (ORs) of symptoms were compared across visits, sex, and age groups using generalized estimating equations, and longitudinal patterns of symptom change were analyzed using multinomial logistic regression.

RESULTS

Prevalence of meeting criteria of symptoms suggestive of early OA was 68% at 6 months, 54% at 12 months, and 46% at 24 months post-ACLR. Longitudinally, 33% had persistent symptoms, 23% had no symptoms, 29% showed symptom resolution, 6% developed new symptoms, and 9% had inconsistent symptoms. Women consistently showed higher odds of symptoms (OR range 1.17-1.52). Older age groups demonstrated higher odds of symptoms, particularly at 6 months (OR range 1.64-2.45).

CONCLUSION

Symptoms suggestive of early OA are highly prevalent within two years post-ACLR, with one third of patients experiencing persistent symptoms. These findings indicate that symptoms are more likely to persist rather than newly develop, emphasizing the importance of early identification and targeted interventions.

Biomechanical contributors to loading rates during gait following anterior cruciate ligament reconstruction

Post-traumatic knee osteoarthritis (PTOA) develops rapidly after anterior cruciate ligament reconstruction (ACLR) and both high and low vertical ground reaction force (vGRF) loading rates are associated with cartilage degeneration. However, the gait characteristics that influence vGRF linear and instantaneous loading rates after ACLR are unknown. Sixty-nine individuals with ACLR (sex: 72 % female, age: 20 ± 3 years, and time since ACLR: 26 ± 16 months) walked at a self-selected pace from which the vGRF linear (slope from heel strike to peak) and instantaneous (peak of the first time derivative) loading rates were calculated. Lasso regressions were utilized to objectively identify a subset of predictor variables that influence vGRF linear and instantaneous loading rates. The identified predictors were then utilized in multiple regressions to determine the unique variance attributable to each predictor by computing Δr2 when that predictor was removed from the model. Greater gait speed (Δr2=0.019), greater medial hamstring preparatory amplitude (Δr2=0.022), and lesser peak posterior ground reaction force (pGRF) (Δr2=0.103) were associated with greater vGRF linear loading rate. Greater gait speed (Δr2=0.072), greater medial hamstring preparatory amplitude (Δ r2 = 0.016), greater anterior ground reaction force (aGRF) immediately after heel strike (Δr2=0.054), and lesser peak pGRF (Δr2=0.019) were associated with greater vGRF instantaneous loading rates. Lesser pGRF and greater aGRF immediately after heel strike explain additional variance in vGRF linear and instantaneous loading rates beyond that explained by gait speed. Future investigations should evaluate the relationship between the aGRF immediately after heel strike and pGRF with indicators of cartilage degeneration.

Corticosteroid Injection up to 8 Weeks Before Anterior Cruciate Ligament Reconstruction Doubles the Incidence of Postoperative Infection

PURPOSE

To determine whether at least 1 corticosteroid injection (CSI) within 8 weeks before anterior cruciate ligament reconstruction (ACLR) increases the incidence of postoperative infection.

METHODS

A large globally federated research database (TriNetX) containing more than 200 million patient records was queried retrospectively for patients undergoing ACLR between October 1, 2010, and January 1, 2024, using diagnosis and procedure codes. A cohort of patients receiving CSI up to 8 weeks before ACLR were compared with a cohort of patients who did not receive a CSI before ACLR. One-to-one propensity score matching was performed on the basis of preoperative characteristics and comorbid diagnoses. Outcomes examined were incidence of postoperative infection at 90 days and 180 days. Postoperative infection was defined as a formal infection diagnosis or need for a washout surgery. Comparisons were performed using Pearson χ2 tests.

RESULTS

After matching, 2,439 patients were analyzed in each cohort with matched preoperative characteristics and comorbid diagnoses. Patients receiving a CSI in the 8 weeks before ACLR had a 90-day infection rate of 1.2% (30/2,439) compared with a control group infection rate of 0.6% (14/2,439) represented as an odds ratio of 2.1 (95% confidence interval 1.1-4.0, P = .015). After 180 days, the infection rates grew to 1.3% (33/2,439) for patients receiving CSI and 0.6% (15/2,439) for the control group with an odds ratio of 2.2 (95% confidence interval 1.2-4.1, P = .009).

CONCLUSIONS

CSIs given within 8 weeks of ACL-R approximately double the incidence of postoperative infection.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

HR-pQCT measurements of changes in periarticular bone density and microarchitecture one year after acute knee injury and after reconstructive surgery

ACL injuries commonly lead to post-traumatic osteoarthritis (PTOA), but the underlying mechanism is not well-understood. One theorized mechanism is pathological bone remodelling following an ACL tear, for which high-resolution peripheral quantitative computed tomography (HR-pQCT) is uniquely positioned to investigate in vivo in humans. In this study, we longitudinally investigate the one-year changes in periarticular bone density and microarchitecture in the human knee following an ACL tear and reconstructive surgery using data sampled from an on-going observational cohort study. We reduce the number of individual microarchitectural parameters using factor analysis and model one-year changes with mixed-effects models, adjusting for the effects of age, sex, meniscus status, and the baseline microarchitectural state. We find significant evidence of persistent bone density losses one year after both injury and surgery. We also observe significant increases in trabecular separation post-injury, indicating significant structural degradation, and significant increases in subchondral bone plate density post-surgery, a sign of early stiffening. Finally, we observe minimal significant contrasts for the effects of age, sex, and meniscus status, while we observe that the state of the microarchitecture at baseline has significant and varied effects on the subsequent changes, suggesting that the influence of PTOA risk factors on post-injury and post-surgery bone changes may be mediated through the state of the periarticular microarchitecture at injury and/or at surgery. In summary, we found that degradation of periarticular bone microarchitecture was observed post-injury, densification of the subchondral bone plate was observed post-surgery, and the state of the bone microarchitecture at baseline may mediate the influence of PTOA risk factors on post-injury microarchitectural adaptations.

Ultrasound-Based Statistical Shape Modeling for Quantifying Femoral Trochlear Bone Shape Post-ACLR

Objective

Traditional assessments of femoral bone shape are inaccessible and do not adequately describe the full complexity of concave bone shape. We aimed to develop and validate an ultrasound-based statistical shape model (SSM) and derived bone shape score (B-Score) to quantify femoral trochlear bone shape morphology associated with anterior cruciate ligament reconstruction (ACLR).

Design

Cross-sectional investigation involving 20 individuals with and 28 individuals without a history of ACLR. Bilateral ultrasound images of the femoral trochlear groove were acquired and analyzed. Both the SSM and B-Score were validated using 5-fold cross-validation, assessing reconstruction and classification accuracy, respectively.

Results

In held out test data, the SSM captured over 99% of the bone shape variance with minimal reconstruction error (RMSE = 0.027 ± 0.004 mm). On test data, the B-Score accurately quantified bone shape associated with ACLR, demonstrating high accuracy (92.42%), sensitivity (97.37%), specificity (85.71%), and AUROC (0.95). A B-Score threshold of 1.41 standard deviations from the mean healthy bone shape was identified for classifying ACLR history.

Conclusions

The ultrasound-based SSM and derived B-Score provide a valid and accessible method for quantifying femoral trochlear bone shape changes post-ACLR. This approach offers potential for early detection of bone shape changes associated with disease and injury, improving long-term outcomes for ACLR patients. Future research should focus on enhancing model generalizability and assessment of bone shape changes longitudinally.

The PIKASO trial (Preventing Injured Knees from Osteoarthritis: Severity Outcomes): Rationale and design features for a randomized controlled trial

Objective

Given the high burden and increasing prevalence of post-traumatic osteoarthritis (PTOA), identifying clinically beneficial strategies to prevent or delay its onset could improve the quality of life of those at high risk of developing the disease.

Methods

Preventing Injured Knees from OsteoArthritis: Severity Outcomes (PIKASO) is a multicenter blinded, parallel, two-arm randomized controlled trial of 512 individuals aged 18-45 years undergoing anterior cruciate ligament reconstruction (ACLR). This study is designed to evaluate the efficacy of a 12-month intervention of oral metformin vs. placebo in decreasing the rate of structural knee changes and pain. Participants will be asked to take up to 1500 ​mg/day of either metformin or placebo as tolerated. The primary outcomes are Knee injury and Osteoarthritis Outcome Score (KOOS) Pain subscale scores averaged between 12 and 24 months after randomization, and MRI derived cartilage structural change at 24 months. The trial will be deemed successful if at least one of the two primary outcomes reaches the preplanned effect size with sufficient statistical certainty. In this paper, we describe PIKASO elements according to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines.

Results

Our multidisciplinary team developed the methods and statistical analysis plan for a placebo controlled, randomized clinical trial to determine whether metformin alters pain and early osteoarthritic changes after ACLR.

Discussion

This manuscript outlines the rationale, study design, and implementation of the PIKASO trial aiming to prevent the onset of PTOA after ACLR.

Trial registration

clinicaltrials.gov NCT06096259.

The effects of short-term non-weightbearing and immobilization after anterior cruciate ligament reconstruction on articular cartilage: Long-term observation after reloading and remobilization

Non-weightbearing or immobilization after anterior cruciate ligament (ACL) reconstruction accelerates cartilage degeneration. However, it is unclear whether these adverse effects are reversed by reloading or remobilization. Moreover, it is unknown whether the combination of non-weightbearing and immobilization after ACL reconstruction has synergistic effects on cartilage degeneration. We aimed to determine 1) the long-term effects of reloading or remobilization following short-term non-weightbearing or immobilization after ACL reconstruction on cartilage degeneration and 2) the combined effects of non-weightbearing and immobilization on cartilage degeneration. We divided ACL-reconstructed rats into four groups: no intervention, non-weightbearing, joint immobilization, and non-weightbearing plus immobilization. Non-weightbearing and immobilization were performed for 2 weeks, after which all rats were reared without intervention. Untreated rats were used as controls. At 2, 4, or 12 weeks after starting the experiment, cartilage degeneration in the anterior, middle, and posterior regions of the medial tibial plateau was histologically assessed. Two weeks of non-weightbearing or immobilization after ACL reconstruction facilitated cartilage degeneration in the middle and posterior regions compared to those with no intervention. Cartilage degeneration was not reversed by 10 weeks of reloading or remobilization. Compared with non-weightbearing alone, combination of non-weightbearing and immobilization improved cartilage degeneration in the middle region, but worsened it in the posterior region. Cartilage degeneration induced by 2 weeks of non-weightbearing or immobilization after ACL reconstruction was not reversed by reloading or remobilization. Thus, to reduce cartilage degeneration, non-weightbearing and immobilization should be avoided after ACL reconstruction, even for short-term.

Early Gait Biomechanics Linked to Daily Steps After Anterior Cruciate Ligament Reconstruction

CONTEXT

Gait biomechanics and daily steps are important aspects of knee-joint loading that change after anterior cruciate ligament reconstruction (ACLR). Understanding their relationship during the first 6 months post-ACLR could help clinicians develop comprehensive rehabilitation interventions that promote optimal joint loading after injury, thereby improving long-term knee-joint health.

OBJECTIVES

To compare biomechanical gait waveforms throughout stance at early time points post-ACLR in individuals with different daily step behaviors at 6 months post-ACLR and to examine how these gait waveforms compare with those of uninjured controls.

DESIGN

Case-control study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 32 individuals with primary ACLR assigned to the low-step group (LSG; n = 13) or the high-step group (HSG; n = 19) based on their average daily steps at 6 months post-ACLR and 32 uninjured matched controls.

MAIN OUTCOME MEASURE(S)

Gait biomechanics were collected at 2, 4, and 6 months post-ACLR for the ACLR groups and at a single session for the control group. Knee-adduction moment, knee-extension moment (KEM), and knee-flexion angle (KFA) waveforms were calculated during gait stance and then compared via functional waveform analyses. Mean differences and corresponding 95% CIs between groups were reported.

RESULTS

Primary results demonstrated less KFA (1%-45% versus 79%-92% of stance) and greater KEM (65%-93% of stance) at 2 months and greater knee-adduction moment (14%-20% versus 68%-92% of stance) at 4 months post-ACLR for the HSG compared with the LSG. Knee-adduction moment, KEM, and KFA waveforms differed across various proportions of stance at all time points between the step and control groups.

CONCLUSIONS

Differences in gait biomechanics were present at 2 and 4 months post-ACLR between step groups, with the LSG demonstrating an overall more flexed knee and more profound stepwise underloading throughout stance than the HSG. The results indicate a relation between early gait biomechanics and later daily step behaviors post-ACLR.

Functional knee bracing provides protection to the anterior cruciate ligament in response to rotatory loads

BACKGROUND

The aim of the study was to quantify the effect of functional knee bracing on native knee kinematics and the in-situ force in the ACL in response to external loading.

METHODS

A robotic testing system was used to apply three external loads from full extension to 60° of flexion to eight fresh frozen human cadaveric knees: 1) a 134 N anterior load, 2) a combined 5-Nm internal rotation +5-Nm valgus torque, and 3) a combined 5-Nm external rotation +5-Nm valgus torque. For native and braced states, kinematics were recorded and the in-situ force in the ACL was determined.

FINDINGS

In response to the combined internal + valgus torque, ideal bracing significantly reduced internal rotation at each flexion angle and valgus rotation at 60° of flexion and reduced the in-situ force in the ACL at full extension and 30° of flexion. In response to the combined external + valgus torque, ideal bracing significantly reduced external rotation at each flexion angle and the in-situ force in the ACL at full extension. Ideal bracing had no effect on kinematics in the other degrees of freedom or on the in-situ force in the ACL in response to a 134 N anterior load.

INTERPRETATION

Ideal knee bracing provided a protective effect on the ACL in response to a combined 5-Nm internal rotation +5-Nm valgus torque but had minimal impact in response to anterior loading and valgus torque. Therefore, ideal functional knee bracing may improve rotatory stability and provide protection to the ACL.

Bilateral waveform analysis of gait biomechanics presurgery to 12 months following ACL reconstruction compared to controls

The purpose of this study was to compare gait biomechanics between limbs and to matched uninjured controls (i.e., sex, age, and body mass index) preoperatively and at 2, 4, 6, and 12 months following primary unilateral anterior cruciate ligament reconstruction (ACLR). Functional mixed effects models were used to identify differences in gait biomechanics throughout the stance phase between the a) ACLR limb and uninvolved limb, b) ACLR limb and controls, and c) uninvolved limb and controls. Compared with the uninvolved limb, the ACLR limb demonstrated lesser knee extension moment (KEM; within 8-37% range of stance) during early stance as well as lesser knee flexion moment (KFM; 45-84%) and greater knee flexion angle (KFA; 43-90%) during mid- to late stance at all timepoints. Compared with controls, the ACLR limb demonstrated lesser vertical ground reaction force (vGRF; 5-26%), lesser KEM (7-47%), and lesser knee adduction moment (KAM; 12-35%) during early stance as well as greater vGRF (39-63%) and greater KFA (34-95%) during mid- to late stance at all timepoints. Compared with controls, the uninvolved limb demonstrated lesser KFA (1-56%) and lesser KEM (12-54%) during early to mid-stance at all timepoints. While gait becomes more symmetrical over the first 12 months post-ACLR, the ACLR and uninvolved limbs both demonstrate persistent aberrant gait biomechanics compared to controls. Biomechanical waveforms throughout stance can be generally described as less dynamic following ACL injury and ACLR compared with uninjured controls.

Quadriceps-Strength-Testing Practices and Barriers During Return to Sport After ACL Reconstruction: A Survey of College Athletic Trainers

CONTEXT

Quadriceps strength is a key outcome for guiding rehabilitation and return to sport-specific activities after anterior cruciate ligament reconstruction (ACLR) surgery.

OBJECTIVE

(1) Describe the quadriceps-strength-testing practices and barriers college athletic trainers (ATs) are using and experiencing when returning patients to sport-specific activities after ACLR. (2) Compare testing methods between college ATs working in the National Collegiate Athletic Association (NCAA) Division I setting and other college settings.

DESIGN

Cross-sectional study.

SETTING

Online survey.

PATIENTS OR OTHER PARTICIPANTS

Two hundred forty-three full-time collegiate ATs who had primarily overseen/directed an ACLR rehabilitation in the past 5 years (age = 34.8 ± 10.7 years, length of AT practice = 11.7 ± 9.3 years, NCAA Division I setting = 56%).

MAIN OUTCOME MEASURE(S)

Our survey included 4 sections: demographics, general ACLR rehabilitation practices, quadriceps-strength-testing methods and criteria, and quadriceps-strength-testing barriers.

RESULTS

Knee-muscle strength was the most common (98%) outcome collegiate ATs used when determining whether an ACLR patient is ready to progress to sport-specific activities. Manual muscle testing was the most used testing method (57%), followed by isokinetic dynamometry (IKD) (48%), repetition maximum testing (35%) and handheld dynamometry (22%). Most ATs (63%-64%) used greater than 90% side-to-side symmetry as their return to sport-specific activities criterion. Lack of equipment needed (83%), lack of financial means (28%), and lack of training/education (20%) were the barriers that most limited ATs use of IKD testing, the gold standard testing method. Compared with ATs in other settings, a greater proportion of ATs working in the NCAA Division I setting used IKD testing (65% vs 28%) and a smaller proportion used manual muscle testing (47% vs 70%).

CONCLUSIONS

Although almost all college ATs considered knee-muscle strength an important outcome to assess when returning patients to sport-specific activities after ACLR, quadriceps-strength-testing practices were highly variable among ATs and may be affected by access to necessary resources.

Synovial biomarkers in the diagnosis of post-traumatic osteoarthritis following anterior cruciate ligament and meniscus injuries: protocol for a systematic review

INTRODUCTION

This review aims to synthesise research evidence regarding biomarkers in the synovial fluid that may predict the risk of post-traumatic osteoarthritis (PTOA) in young adults. Considering the high prevalence of knee joint injuries, particularly among youth sports athletes, this review will focus on anterior cruciate ligament and/or meniscal ruptures. These injuries are highly associated with PTOA, with studies indicating that even with surgical reconstruction, 50%-80% of affected individuals develop knee PTOA within a 10-year follow-up.

METHODS AND ANALYSIS

The results of this systematic review will be reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Diagnostic Test Accuracy guidelines. Comprehensive electronic searches will be conducted across five platforms: four bibliographic databases (PubMed, Cochrane Central Register of Controlled Trials, Web of Science Core Collection and Embase) and ClinicalTrials.gov registry. These searches will use combinations of predefined keywords, such as "knee", "synovial fluid", "post-traumatic osteoarthritis", "anterior cruciate ligament", "meniscus", "trauma", "inflammation" and "biomarker". We will include randomised clinical trials, non-randomised prospective or retrospective clinical studies, case controls, cohort studies and case series, ranging from database inception to 30 June 2024 and published in English. Two independent reviewers will screen and evaluate the retrieved studies to determine their eligibility. Any reviewer disagreements will be resolved through discussion and consensus or, if necessary, by consultation with a third reviewer. The data will be extracted from the included studies and analysed, with the risk of bias assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. A narrative synthesis will be performed to evaluate the strength and consistency of the findings, considering both the methodological quality of the included studies and the reliability of the results.

ETHICS AND DISSEMINATION

Ethical approval is not required for this review as it is a secondary study based on public and published data. The findings from this work will be submitted for publication in a peer-reviewed journal and presented at relevant academic conferences. Any amendments to the protocol arising from deviations during the study's execution will be documented and reported in the final publication.

PROSPERO REGISTRATION NUMBER

CRD42024534272.

Comparative Evaluation of Arthritic Changes in Post-operative Patients With Anterior Cruciate Ligament (ACL) Injuries: A Study of Exercising Versus Sedentary Individuals

BACKGROUND

Anterior cruciate ligament (ACL) injury has become quite a common injury affecting the knee in young and middle-aged individuals. ACL reconstruction is a common surgical intervention indicated after a grade 3 rupture. Meanwhile, early arthritic changes start to appear after five years post-ACL reconstruction. Increased knowledge about regular exercise after ACL reconstruction in the sedentary population can decrease or reduce the chances of having early arthritic changes in the knee. Therefore, a study is needed to find the prevalence of arthritic changes in the exercising and sedentary postoperative ACL injury patients.

MATERIALS AND METHODS

The population was divided into sedentary and exercising populations. The exercising population was further divided into low, moderate, and high-intensity exercises based on the target heart rate range and maximum heart rate. Radiographs just before surgery or immediate post-operative versus recent radiographs (after five years) were used to assess the knee joints of exercising and sedentary populations by using the Kellgren and Lawrence classification (KLC) to measure the severity of knee osteoarthritis.

RESULTS

In the exercising population, only 4(9.52%) of the individuals were found to have arthritic changes in their knee, whereas, in the sedentary population, 10(18.51%) of the individuals had arthritic changes in their knee post-ACL reconstruction after five years. Lack of regular exercise after ACL reconstruction showed early arthritic changes compared to those who were physically active, indicating the impact of physical activity.

CONCLUSIONS

This study concludes that a greater number of the sedentary population had arthritic changes in their knee joints post-surgery than those who were physically active, highlighting the significance of regular exercise.

Evaluating Gait with Force Sensing Insoles 6 Months after Anterior Cruciate Ligament Reconstruction: An Autograft Comparison

INTRODUCTION

Aberrant knee mechanics during gait 6 months after anterior cruciate ligament reconstruction (ACLR) are associated with markers of knee cartilage degeneration. The purpose of this study was to compare loading during walking gait in quadriceps tendon, bone-patellar tendon-bone (BPTB), and hamstring tendon autograft patients 6 months post-ACLR using loadsol single sensor insoles, and to evaluate associations between loading and patient-reported outcomes.

METHODS

Seventy-two patients (13 to 40 yr) who underwent unilateral, primary ACLR with BPTB, quadriceps tendon, or hamstring tendon autograft completed treadmill gait assessment, the International Knee Documentation Committee (IKDC) survey, and the ACL-Return to Sport after Injury (ACL-RSI) survey 6 ± 1 months post-ACLR. Ground reaction forces were collected using loadsols. Limb symmetry indices (LSI) for peak impact force (PIF), loading response instantaneous loading rate (ILR), and loading response average loading rate (ALR) were compared between groups using separate analyses of covariance. Survey scores were compared between groups using one-way ANOVAs. The relationships between IKDC, ACL-RSI, and LSI were compared using Pearson's product moment correlation coefficients.

RESULTS

There were no significant differences between graft sources for LSI in PIF, ILR, ALR, or impulse. Patient-reported knee function was significantly different between graft source groups with the BPTB group reporting the highest IKDC scores; however, there was no significant difference between groups for ACL-RSI score. There were no significant associations between IKDC score, ACL-RSI score, and biomechanical symmetry among any of the graft source groups.

CONCLUSIONS

Autograft type does not influence PIF, ILR, ALR, or impulse during walking 6 months post-ACLR. Limb symmetry during gait is not strongly associated with patient-reported outcomes regardless of graft source. Loadsols appear to be a suitable tool for use in the clinical rehabilitation setting.

Reliability and changes in knee cartilage T2 relaxation time from 6 to 24 months after anatomic anterior cruciate ligament reconstruction

The objectives of this study were to evaluate the reliability of cartilage T2 relaxation time measurements and to identify focal changes in T2 relaxation on the affected knee from 6 to 24 months after anatomic anterior cruciate ligament reconstruction (ACLR). Data from 41 patients who received anatomic ACLR were analyzed. A bilateral 3.0-T MRI was acquired 6 and 24 months after ACLR. T2 relaxation time was measured in subregions of the femoral condyle and the tibial plateau. The root-mean-square coefficient of variation (RMSCV) was calculated to evaluate the reliability of T2 relaxation time in the contralateral knee. Subregion changes in the affected knee T2 relaxation time were identified using the contralateral knee as a reference. The superficial and full thickness layers of the central and inner regions showed good reliability. Conversely, the outer regions on the femoral side and regions in the deep layers showed poor reliability. T2 relaxation time increased in only 3 regions on the affected knee when controlling for changes in the contralateral knee, while changes in T2 relaxation time were identified in 14 regions when not using the contralateral knee as a reference. In conclusion, evaluation of cartilage degeneration by T2 relaxation time after ACLR is most reliable for central and inner cartilage regions. Cartilage degeneration occurs in the central and outer regions of the lateral femoral condyle from 6 to 24 months after anatomic ACLR.

Neural-Targeted Rehabilitation Strategies to Address Neuroplasticity After Joint Injury

In patients with musculoskeletal injury, changes have been observed within the central nervous system that contribute to altered movement planning. This maladaptive neuroplasticity potentially explains the clinical disconnect where residual neuromuscular dysfunction and high rates of reinjury are often observed even after individuals clear return-to-activity functional testing. An improved understanding of these neural changes could therefore serve as a guide for facilitating a more complete recovery and minimizing risk of reinjury. Therefore, we propose a paradigm of neural-targeted rehabilitation to augment commonly used therapeutic techniques targeting sensorimotor function to better address maladaptive plasticity. Although most treatments have the capability to modify neural function, optimizing these treatments and combining them with integrative therapies (eg, implementation of motor learning strategies, transcranial direct current stimulation) may enhance neural efficiency and facilitate return to activity in patients with musculoskeletal injury. To complete this model, consideration of affective aspects of movement and associated interventions must also be considered to improve the durability of these changes.

Ligamental reconstruction improved the functional outcomes of patients with anterior cruciate ligament injury and early-stage symptomless osteoarthritis

BACKGROUND

The optimal treatment for anterior cruciate ligament (ACL) injuries with early-stage symptomless osteoarthritis (OA) remains unclear. This study aimed to compare the clinical outcomes of ACL reconstruction (ACLR) in patients with ACL injury in the presence and absence of early-stage symptomless OA.

METHODS

Medical records of patients with early-stage symptomless OA who sustained ACL injury and underwent ACLR from January 2018 to December 2020 at a single institution were retrospectively reviewed. Radiography and magnetic resonance imaging were performed preoperatively to identify ACL injury and OA. Patients with ACL injury and early-stage symptomless OA (combined group, n = 14) were matched at a 1:2 ratio with patients with ACL injury (isolated group, n = 32). Data on demographic characteristics, pain and functional outcomes (visual analogue scale, Tegner, Lysholm, and International Knee Documentation Committee scores and range of motion), and imaging outcomes were collected. Complications were recorded, and outcomes were compared between the groups.

RESULTS

Forty-six patients (26 males, 20 females) were included in this study, among whom 14 had ACL injury and early-stage symptomless OA, whereas 32 sustained isolated ACL injury (average follow-up duration: 3.4 ± 1.0 years). At the final follow-up, pain and functional outcomes similar to those in patients with isolated ACL-deficient knees were achieved in the combined group; acute-stage ACLR resulted in significantly better outcomes (p < 0.05). No significant radiographic progression of OA or complications were observed.

CONCLUSIONS

Knee function in patients with ACL injuries and early-stage symptomless OA who underwent ACLR was the same as that in patients with isolated ACL-deficient knees. Furthermore, ACLR had a beneficial effect on knee outcomes. The subgroup analysis revealed that acute-stage ACLR could lead to better outcomes in patients with ACL injuries and early-stage symptomless OA.

Associations between less knee kinematic variability and worse patient-reported outcomes following anterior cruciate ligament reconstruction

Individuals with anterior cruciate ligament reconstruction (ACLR) exhibit less knee kinematic variability while walking than uninjured controls, associated with deleterious changes in cartilage composition linked to an increased risk for early knee osteoarthritis (KOA). It is unknown whether less knee kinematic variability is also associated with worse knee-related patient-reported outcomes (PROs) consistent with KOA development. This study examined associations between kinematic variability during gait and PROs in individuals post-ACLR. Gait kinematics and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were collected from 45 participants 6-months post-ACLR (67% Females; 21.45 ± 4.56 years). Overground gait biomechanics using 3D motion capture were collected, and knee kinematics were extracted for post-processing. Sample entropy (SampEn) was used to calculate knee kinematic variability. Pearson's product-moment correlations were conducted to determine the associations between SampEn and KOOS sub-scores. Additionally, independent samples t-tests were performed to evaluate potential differences in SampEn outcomes between individuals with and without clinically relevant symptoms (defined in the introduction). Less sagittal plane kinematic variability is associated with greater pain (r = 0.37, p = 0.01) and symptoms (r = 0.32, p = 0.03). Symptomatic participants demonstrated less sagittal plane knee kinematic variability compared to asymptomatic participants (p = 0.01). The findings suggest less variable gait patterns 6-months post-ACLR may be linked to KOA-related symptoms.

Conservative treatment versus surgical reconstruction for ACL rupture: A systemic review

Background

Anterior cruciate ligament (ACL) rupture is a prevalent sports injury with rising rates attributed to increased population participation in sports activities. ACL rupture can lead to severe knee complications including cartilage damage, torn meniscus, and osteoarthritis. Current treatment options include conservative measures and surgical interventions. However, debates persist regarding the optimal approach.

Purpose

This analysis intended to compare the function, knee stability, and incidence rate of secondary surgery between conservative and surgical treatments in ACL rupture patients.

Methods

A systematic search was performed via Embase, Ovid Medline, PubMed, Cochrane Library, Web of Science, and Google Scholar for reporting outcomes of conservative and surgical treatments after ACL rupture. The outcomes included patient-reported outcome measures (PROMs), knee stability, the need for secondary meniscal surgery, delayed ACL reconstruction surgery, and revision ACL reconstruction surgery. Outcomes were analyzed using mean differences or odd ratios (OR) with 95 % CIs.

Results

11 studies were included with 1516 patients. For PROMs, our evidence indicated no differences in KOOS Pain, KOOS Symptoms, KOOS Sport/Rec, KOOS ADL, and KOOS QOL. (all p > 0.05). for knee stability, pivot shift (OR, 0.14; p < 0.001), Lachman test (OR, 0.06; p < 0.001), and tibia translation (p < 0.001) were evaluated, and the available evidence favored surgical treatment over conservative treatment. For the incidence rate of any secondary surgery after the first diagnosis, the surgical group showed a lower rate of meniscal surgery with statistical significance (OR, 0.37; p < 0.001). The average rate of revision ACL reconstruction is 5.80 %, while the rate of delayed ACL reconstruction after conservative treatment is 18.51 %.

Conclusion

Currently, there is insufficient empirical evidence to advocate a systematic surgical reconstruction for any patient who tore his ACL. This review found no differences in function outcomes between conservative and surgical treatments. Regarding knee stability and secondary meniscal surgery, the results prefer the surgical treatments. The occurrence rate of revision and delayed ACL reconstruction are non-negligible factors that must be fully understood by both surgeons and patients before choosing a suitable treatment.

Associations Between Body Mass Index, Gait Biomechanics, and In Vivo Cartilage Function After Exercise in Those With Anterior Cruciate Ligament Reconstruction

BACKGROUND

Both high body mass index (BMI) and anterior cruciate ligament reconstruction (ACLR) independently influence knee osteoarthritis risk. Preliminary evidence shows the combination of these risk factors leads to poorer recovery and altered biomechanical outcomes after ACLR, but few studies have directly evaluated early changes in cartilage health between normal-BMI and high-BMI groups in this population.

PURPOSE

To evaluate ultrasound-based measures of cartilage strain and compositional changes (via echo-intensity [EI]) in response to an incline walking stress test between normal-BMI and high-BMI individuals with ACLR. A secondary evaluation was conducted of associations between habitual walking biomechanics (ie, ground-reaction forces, sagittal knee kinetics and kinematics) and cartilage strain and EI outcomes.

STUDY DESIGN

Controlled laboratory study.

METHODS

Gait biomechanics and femoral trochlear ultrasound analyses were evaluated in 64 participants with ACLR who had normal BMI (BMI < 27.0; n = 40) and high BMI (BMI ≥ 27.0; n = 24). Ultrasound images were collected bilaterally before and after an incline treadmill walk, and medial and lateral trochlear strain and EI changes pre-post exercise were used to compare BMI groups and limbs. Gait outcomes included ground-reaction forces, peak sagittal plane knee moments, angles, and excursions and were used to determine associations with cartilage outcomes in the entire cohort.

RESULTS

High-BMI individuals with ACLR exhibited greater medial trochlear cartilage strain in the ACLR limb compared with normal-BMI individuals (approximately 6%; P < .01). In those with high BMI, the ACLR limb exhibited greater medial trochlear strain relative to non-ACLR limbs (approximately 4%; P < .05), but between-limb differences were not observed in the normal-BMI group (P > .05). Medial trochlear EI changes were greater bilaterally in those with high BMI compared with normal-BMI ACLR counterparts (approximately 10%; P < .01). Last, individuals who walked with greater peak knee flexion angles exhibited less medial cartilage strain (ΔR2 = 0.06; P = .025).

CONCLUSION

The data suggested that high BMI affects cartilage functional properties after ACLR, whereas smaller knee flexion angles were associated with larger medial cartilage strain.

CLINICAL RELEVANCE

High-BMI individuals with ACLR may represent a subset of patients exhibiting earlier declines in cartilage functional integrity in response to loading, necessitating additional or more targeted interventions to mitigate disease development.

No difference was found between double-bundle and single-bundle anterior cruciate ligament reconstructions in terms of osteoarthritis at 15-year follow-up

PURPOSE

The purpose of the study was to determine whether the grade of osteoarthritis (OA) is higher with single-bundle (SB) or double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. The hypothesis was that there will be no difference in the grade of OA between the techniques.

METHODS

This study was a randomised controlled trial (RCT) with a follow-up period of 15 years. Patients were randomly assigned to either the SB group (n = 78) or the DB group (n = 75). Surgical techniques were anatomic, and the rehabilitation protocol was standardised. Evaluation included Kellgren-Lawrence (KL) difference and absolute OA results. OA was defined as a KL grade of at least 2.

RESULTS

At 15-year follow-up, information was available on 101 patients (66%), of whom 56 (37%) were accepted in the final statistical analysis. No difference was found between the SB and DB techniques in terms of KL difference or absolute OA results. Significantly less OA was found in the contralateral knee (21%) than in the reconstructed knee (59%) (p < 0.001). Patients with meniscal tears who underwent partial meniscal resection during ACL reconstruction had a significantly higher rate of OA changes (82%) compared with patients with isolated ACL tears (33%) (p < 0.001). A longer delay between initial injury and surgery did not appear to affect the severity of the KL classification.

CONCLUSION

At 15-year follow-up, no difference was found between the DB and SB techniques in terms of OA.

LEVEL OF EVIDENCE

Level I.

Improved Quadriceps Torque Production With Optimized Biofeedback in Patients After Anterior Cruciate Ligament Reconstruction

Hogg, JA, Barger, NB, Bruce, JR, White, CC, Myer, GD, and Diekfuss, JA. Improved quadriceps torque production with optimized biofeedback in patients after anterior cruciate ligament reconstruction. J Strength Cond Res XX(X): 000–000, 2024—Optimizing performance through intrinsic motivation and attention for learning: prevention rehabilitation exercise play (OPTIMAL PREP) training strategies incorporate motor learning principles to enhance movement acquisition and retention. We aimed to use OPTIMAL PREP biofeedback to evaluate its potential to improve quadriceps and hamstring torque production in patients with anterior cruciate ligament reconstruction (ACL-R). Thirteen subjects 23 ± 19 months post ACL-R completed 5 concentric quadriceps/hamstrings repetitions on an isokinetic dynamometer for each limb and counterbalanced condition at 60°·s−1. For the control condition, subjects were instructed to perform the exercise “as hard and fast as possible.” For the OPTIMAL PREP condition, subjects were additionally told that “Research shows that if you focus on moving the line on the screen (external focus) you will exhibit greater quadriceps output (enhanced expectancies)” and were given the choice of graphical representation for the biofeedback (autonomy support). Quadriceps and hamstrings peak torque, rate of force development, and torque-angle waveforms were analyzed with 2 × 2 RMANOVAs (a priori >0.06). The ACL-R limb demonstrated increased quadriceps peak torque in the OPTIMAL PREP condition than in the control condition ( = 0.13, interaction p = 0.21, pairwise Cohen's d = 0.63). Anterior cruciate ligament reconstruction limb quadriceps deficits remained near terminal extension (14–45°; peak Cohen's d = 0.57, p < 0.001). For hamstrings peak torque, we observed moderate effects for condition (OPTIMAL PREP greater; = 0.10, p = 0.29) and limb (uninvolved greater; = 0.13, p = 0.22). Easily implementable OPTIMAL PREP training strategies improved ACL-R limb quadriceps torque production, resulting in between-limb parity. However, asymmetries still existed near terminal extension.

Evaluation under loading detects medial meniscus extrusion in patients with reconstructed anterior cruciate ligament and restricted knee extension

PURPOSE

Some patients who undergo anterior cruciate ligament (ACL) reconstruction experience abnormal mechanical stress in the meniscus. Medial meniscal extrusion (MME) is reflected in the pathological condition of the meniscus, which expands owing to repetitive mechanical stress. Thus, the effect of the reconstructed ACL on increasing MME under weight-bearing conditions remains unclear. This study investigated the effect of ACL reconstruction on meniscal extrusion under non-weight-bearing and weight-bearing conditions.

METHODS

Seventeen patients who underwent unilateral ACL reconstruction (ACL group) and 20 age-matched healthy volunteers (control group) were enrolled. Ultrasonography was performed in the supine, standing, and walking positions in preoperative and postoperative ACL patients. MME during walking was evaluated based on the dynamic behavior of extrusion, and kinetic and kinematic data were synchronously obtained. Moreover, the ACL group underwent magnetic resonance imaging (MRI) evaluation at two points: preoperatively and 12 months postoperatively, and the ultrasound findings were compared.

RESULTS

MME in the supine position measured using both ultrasonography and MRI was not significantly different preoperatively and postoperatively in the ACL group. However, postoperative MME and dynamic behavior of extrusion under standing and walking conditions were significantly higher than those in the preoperative state (dynamic behavior: 0.9 ± 0.4 mm preoperatively, 1.2 ± 0.4 mm postoperatively). Moreover, the deficits in knee extension during walking persisted postoperatively and were significantly higher than those in the control group.

CONCLUSION

MME in patients with ACL reconstruction including meniscus repair was different under mechanical stress compared to the non-weight bearing condition.

Return to Play After an Anterior Cruciate Ligament Reconstruction in the Collegiate Athlete: A Systematic Review Evaluating Return to Play Proportions and Associated Factors

OBJECTIVE: To estimate anterior cruciate ligament reconstruction (ACLR) return-to-play (RTP) factors and proportions across all National Collegiate Athletics Association (NCAA) sports. DESIGN: Systematic review with prognosis and etiology components. LITERATURE SEARCH: Two independent reviewers searched PubMed, Cochrane Library, and Embase databases using terms related to RTP, ACLR, and NCAA for articles published up to June 30, 2023. STUDY SELECTION CRITERIA: Articles were included if RTP proportions or factors affecting RTP were reported and if the study population included NCAA collegiate athletes recovering from an ACLR. DATA SYNTHESIS: The proportion represents the total number of athletes who returned to play after ACLR over the total number of ACLR athletes from each cohort. The cumulative proportion represents the aggregated total from each included study. When eligibility information was available (ie, athletes in their final year of eligibility), RTP proportions were adjusted. The Newcastle-Ottawa Scale (NOS) was used to assess the study quality and scored by 2 raters. RESULTS: Nine studies were included. RTP criteria varied across the studies. Proportions of RTP ranged from 69% to 92%, with a cumulative RTP proportion after ACLR of 84% (628/745). The primary factors associated with the proportion of RTP were scholarship status, competitive eligibility remaining, depth chart position, and surgical graft type. CONCLUSIONS: The cumulative proportion of RTP was 84% and was associated with patient-specific and operative factors. Psychological and functional factors were not routinely reported, and rehabilitation protocols were unknown. Data were not explicitly available for any athletes outside of Division I. The criteria for RTP after ACLR varied. J Orthop Sports Phys Ther 2024;54(10):1-9. Epub 10 September 2024. https://doi.org/10.2519/jospt.2024.12483.

Knee muscle strength and steadiness for individuals with anterior cruciate ligament reconstruction and knee osteoarthritis

BACKGROUND

Strength and neuromuscular decrements following knee musculoskeletal injury may accelerate knee osteoarthritis development. This study assessed isometric knee extensor and flexor strength and steadiness between individuals with knee injury, i.e., ligament reconstruction, and knee osteoarthritis to healthy age-matched controls.

METHODS

Four cohorts (1: knee injury and 2: age-matched controls, and 3: radiographic knee osteoarthritis and 4: age-matched controls) were recruited. Participants performed maximal voluntary isometric knee extensor and flexor contractions. Then, strength (e.g., peak and rate of torque development) and steadiness (e.g., peak power, mean, and median frequency) were derived from each raw torque-time curve and associated power spectral density. A Kruskal-Wallis H test and Spearman's rho correlation analysis assessed cohort differences and association between knee extensor and flexor strength and steadiness.

FINDINGS

The young adult control and knee injury cohorts exhibited greater knee extensor and flexor strength than the older, knee osteoarthritis cohort (p < 0.043). The knee injury cohort, despite being as strong as their healthy counterparts, were significantly less steady with a 92% increase in peak power frequency (p = 0.046). The osteoarthritis cohort exhibited 157% less total power compared to the knee injury and young control cohorts (p < 0.019). Knee extensor and flexor peak torque, rate of torque development, and mean torque exhibit a significant, positive relation with total power (p < 0.018).

INTERPRETATION

Individuals with knee injury and disease may exhibit weaker or less steady knee musculature, predisposing them to degenerative joint disease. Clinicians may need to restore knee extensor and flexor steadiness to facilitate better joint neuromuscular control.

Lower limb coordination patterns following anterior cruciate ligament reconstruction: A longitudinal study

BACKGROUND

Changes in lower limb joint coordination have been shown to increase localized stress on knee joint soft tissue-a known precursor of osteoarthritis. While 50% of individuals who undergo anterior cruciate ligament reconstruction (ACLR) develop radiographic osteoarthritis, it is unclear how underlying joint coordination during gait changes post-ACLR. The purpose of this study was twofold: to determine differences in lower limb coordination patterns during gait in ACLR individuals 2, 4, and 6 months post-ACLR and to compare the coordination profiles of the ACLR participants at each timepoint post-ACLR to uninjured matched controls.

METHODS

We conducted a longitudinal assessment to quantify lower limb coordination at 3 timepoints post-ACLR and compared the ACLR coordination profiles to uninjured controls. Thirty-four ACLR (age = 21.43 ± 4.24 years, mean ± SD; 70.59 % female) and 34 controls (age = 21.42 ± 3.43 years; 70.59% female) participated. The ACLR group completed 3 overground gait assessments (2,4, and 6 months post-ACLR), and the controls completed one assessment, at which lower limb kinematics were collected. Cross-recurrence quantification analysis was used to characterize sagittal and frontal plane ankle-knee, ankle-hip, and knee-hip coordination dynamics. Comprehensive general linear mixed models were constructed to compare between-limb and within-limb coordination outcomes over time post-ACLR and a between-group comparison across timepoints.

RESULTS

The ACLR limb demonstrated a more "stuck" sagittal plane knee-hip coordination profile (greater trapping time (TT); p = 0.004) compared bilaterally. Between groups, the ACLR participants exhibited a more predictable ankle-knee coordination pattern (percent determinism (%DET); p < 0.05), stronger coupling between joints (meanline (MNLine)) across all segments (p < 0.05), and greater knee-hip TT (more "stuck"; p < 0.05) compared to the controls at each timepoint in the sagittal plane. Stronger frontal plane knee-hip joint coupling (MNLine) persisted across timepoints within the ACLR group compared to the controls (p < 0.05).

CONCLUSION

The results indicate ACLR individuals exhibit a distinct and rigid coordination pattern during gait compared to controls within 6-month post-ACLR, which may have long-term implications for knee-joint health.

Persistent Early Knee Osteoarthritis Symptoms From 6 to 12 Months After Anterior Cruciate Ligament Reconstruction

CONTEXT

Early identification of knee osteoarthritis (OA) symptoms after anterior cruciate ligament reconstruction (ACLR) could enable timely interventions to improve long-term outcomes. However, little is known about the change in early OA symptoms from 6 to 12 months post-ACLR.

OBJECTIVE

To evaluate the change over time in meeting classification criteria for early knee OA symptoms from 6 to 12 months after ACLR.

DESIGN

Prospective cohort study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Eighty-two participants aged 13 to 35 years who underwent unilateral primary ACLR. On average, participants' first and second visits were 6.2 and 12.1 months post-ACLR.

MAIN OUTCOME MEASURE(S)

Early OA symptoms were classified using generic (Luyten Original) and patient population-specific (Luyten Patient Acceptable Symptom State [PASS]) thresholds on Knee injury and Osteoarthritis Outcome Score (KOOS) subscales. Changes in meeting early OA criteria were compared between an initial and follow-up visit at an average of 6 and 12 months post-ACLR, respectively.

RESULTS

Twenty-two percent of participants exhibited persistent early OA symptoms across both visits using both the Luyten Original and PASS criteria. From initial to follow-up visit, 18% to 27% had resolution of early OA symptoms, while 4% to 9% developed incident symptoms. In total, 48% to 51% had no early OA symptoms at either visit. No differences were found for change in early OA status between adults and adolescents.

CONCLUSIONS

Nearly one-quarter of participants exhibited persistent early knee OA symptoms based on KOOS thresholds from 6 to 12 months post-ACLR. Determining if this symptom persistence predicts worse long-term outcomes could inform the need for timely interventions after ACLR. Future researchers should examine if resolving persistent symptoms in this critical window improves later outcomes. Tracking early OA symptoms over time may identify high-risk patients who could benefit from early treatment.

Associations between Body Mass Index, Gait Mechanics and Trochlear Cartilage Thickness in Those with ACL Reconstruction

PURPOSE

High body mass index (BMI) is a strong predictor of posttraumatic osteoarthritis (OA) after anterior cruciate ligament reconstruction (ACLR). Altered gait mechanics are independently affected by BMI and ACLR, and influence OA risk. Yet, evidence directly assessing the impact of high BMI on gait or cartilage characteristics after ACLR are limited. Here, we evaluated if high BMI moderates associations between gait and trochlear cartilage structure in individuals with ACLR.

METHODS

Treadmill walking biomechanics were evaluated in 40 normal BMI and 24 high BMI participants with ACLR at self-selected speeds. Normalized and absolute peak and cumulative loads (i.e., impulse) were extracted for peak knee flexion and adduction moments (KFM, KAM) and vertical ground reaction force (GRF). Medial and lateral femoral cartilage thickness and medial/lateral thickness ratios were assessed via ultrasound.

RESULTS

Those with ACLR and high BMI walked with reduced normalized peak vertical GRFs, and greater absolute peak and cumulative loads compared with normal BMI individuals with ACLR. Those with ACLR and high BMI also exhibited thinner cartilage and greater medial/lateral ratios in ACLR limbs compared with contralateral limbs whereas normal BMI individuals with ACLR exhibited thicker ACLR limb cartilage. Lastly, greater peak KAM and KAM cumulative load were associated with thicker lateral cartilage and lesser medial/lateral thickness ratios, but only in the high BMI group.

CONCLUSIONS

We observed those with high BMI after ACLR exhibited trochlear cartilage structural alterations not observed in normal BMI patients, whereas differential associations between loading outcomes and cartilage thickness in ACLR knees were observed between groups. Those with high BMI after ACLR may require different therapeutic strategies to optimize joint health in this subset of patients.

Diagnosis and treatment of anterior cruciate ligament injuries: Consensus of Chinese experts part II: Graft selection and clinical outcome evaluation

Background

In the recent decade, there has been substantial progress in the technologies and philosophies associated with diagnosing and treating anterior cruciate ligament (ACL) injuries in China. The therapeutic efficacy of ACL reconstruction in re-establishing the stability of the knee joint has garnered widespread acknowledgment. However, the path toward standardizing diagnostic and treatment protocols remains to be further developed and refined.

Objective

In this context, the Chinese Association of Orthopaedic Surgeons (CAOS) and the Chinese Society of Sports Medicine (CSSM) collaboratively developed an expert consensus on diagnosing and treating ACL injury, aiming to enhance medical quality through refining professional standards.

Methods

The consensus drafting team invited experts across the Greater China region, including the mainland, Hong Kong, Macau, and Taiwan, to formulate and review the consensus using a modified Delphi method as a standardization approach. As members of the CSSM Lower Limb Study Group and the CAOS Arthroscopy and Sports Medicine Study Group, invited experts concentrated on two pivotal issues: "Graft Selection" and "Clinical Outcome Evaluation" during the second part of the consensus development.

Results

This focused discussion ultimately led to a strong consensus on nine specific consensus terms.

Conclusion

The consensus clearly states that ACL reconstruction has no definitive "gold standard" graft choice. Autografts have advantages in healing capability but are limited in availability and have potential donor site morbidities; allografts reduce surgical trauma but incur additional costs, and there are concerns about slow healing, quality control issues, and a higher failure rate in young athletes; synthetic ligaments allow for early rehabilitation and fast return to sport, but the surgery is technically demanding and incurs additional costs. When choosing a graft, one should comprehensively consider the graft's characteristics, the doctor's technical ability, and the patient's needs. When evaluating clinical outcomes, it is essential to ensure an adequate sample size and follow-up rate, and the research should include patient subjective scoring, joint function and stability, complications, surgical failure, and the return to sport results. Medium and long-term follow-ups should not overlook the assessment of knee osteoarthritis.

Medial Meniscal Extrusion After Anterior Cruciate Ligament Reconstruction (ACLR) Associated With Meniscal Repair and Preoperative Extrusion

INTRODUCTION

The risk of post-traumatic osteoarthritis remains high even after anterior cruciate ligament reconstruction (ACLR). Medial meniscal extrusion (MME) is a valuable clinical sign as an early morphological change. This study aimed to analyze MME before and after ACLR and investigate the factors affecting postoperative MME.

MATERIALS AND METHODS

This study included patients who underwent anatomical double-bundle ACLR between January 2016 and July 2021. MME was measured using MRI preoperatively and one year postoperatively. The medial meniscus (MM) treatments were categorized into three groups: no MM injury and no repair (no injury/no repair (N/N)), MM injury but no repair (injury/no repair (I/N)), and MM injury and repair (injury/repair (I/R)). We investigated the factors influencing MME after ACLR using multiple linear regression analysis and compared MME before and after ACLR using paired t-tests.

RESULTS

This study included 133 patients, of whom 90 (37 males and 53 females) were analyzed. The mean age of the patients at surgery was 27.5 years, and 41, 27, and 22 patients were assigned into N/N, I/N, and I/R groups, respectively. Preoperative MME (p<0.001) and I/R (p<0.001) had significant effects on postoperative MME in a regression analysis. Postoperative MME had greater effects than the preoperative MME in all cases (1.16 and 1.53 mm (p<0.01)) and in every MM treatment group (N/N: 1.02 and 1.32 mm (p<0.01), I/N: 1.16 and 1.44 mm (p<0.01), and I/R: 1.42 and 2.05 mm (p<0.001)).

CONCLUSIONS

Larger preoperative MME and receiving MM repair were significantly associated with a larger MME after ACLR. Postoperative MME in ACLR patients was significantly greater than preoperative MME.

Patient and Operative Risk Factors for Osteoarthritis After Primary Anterior Cruciate Ligament Reconstruction: A Cohort Study of 41,976 Patients

BACKGROUND

The reported incidence of posttraumatic knee osteoarthritis (PTOA) after primary anterior cruciate ligament reconstruction (ACLR) varies considerably. Further, there are gaps in identifying which patients are at risk for PTOA after ACLR and whether there are modifiable factors.

PURPOSE

To (1) determine the incidence of PTOA in a primary ACLR cohort and (2) identify patient and perioperative factors associated with the development of PTOA after primary ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data from the Kaiser Permanente ACLR Registry were used to conduct a cohort study. Patients who had undergone primary ACLR without a previous diagnosis of osteoarthritis were identified (2009-2020). The crude incidence of PTOA was calculated using the Aalen-Johansen estimator with a multistate model. The association of patient and operative factors with the development of PTOA after primary ACLR was modeled as a time to event using multistate Cox proportional hazards regression. Models stratified by age (<22 and ≥22 years) were also conducted because of the effect modification of age.

RESULTS

The study sample included 41,976 cases of primary ACLR. The incidence of PTOA was 1.7%, 5.1%, and 13.6% at 2, 5, and 10 year follow-ups, respectively. Risk factors for PTOA that were consistently identified in the overall cohort and age-stratified groups included a body mass index ≥30 versus <30 and an allograft or quadriceps tendon autograft versus a hamstring tendon autograft. Patients presenting with knee pain after ACLR were further identified when considering postoperative factors. Other risk factors for PTOA in the overall cohort included age ≥22 versus <22 years, bone-patellar tendon-bone autograft versus hamstring tendon autograft, hypertension, cartilage injury, meniscal injury, revision after primary ACLR with concomitant meniscal/cartilage surgery, multiligament injury, other activity at the time of injury compared with sport, and tibial tunnel drilling technique rather than the anteromedial portal.

CONCLUSION

Knee pain after ACLR may be an early sign of PTOA. Surgeons should consider the adverse associations of a higher body mass index and an allograft or quadriceps tendon autograft with the development of PTOA, as these were factors identified with a higher risk, regardless of a patient's age at the time of primary ACLR.

Association of Serum Biochemical Biomarker Profiles of Joint Tissue Inflammation and Cartilage Metabolism With Posttraumatic Osteoarthritis-Related Symptoms at 12 Months After ACLR

BACKGROUND

Anterior cruciate ligament injury and anterior cruciate ligament reconstruction (ACLR) are risk factors for symptomatic posttraumatic osteoarthritis (PTOA). After ACLR, individuals demonstrate altered joint tissue metabolism indicative of increased inflammation and cartilage breakdown. Serum biomarker changes have been associated with tibiofemoral cartilage composition indicative of worse knee joint health but not with PTOA-related symptoms.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine associations between changes in serum biomarker profiles from the preoperative sample collection to 6 months after ACLR and clinically relevant knee PTOA symptoms at 12 months after ACLR. It was hypothesized that increases in biomarkers of inflammation, cartilage metabolism, and cartilage degradation would be associated with clinically relevant PTOA symptoms after ACLR.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Individuals undergoing primary ACLR were included (N = 30). Serum samples collected preoperatively and 6 months after ACLR were processed to measure markers indicative of changes in inflammation (ie, monocyte chemoattract protein 1 [MCP-1]) and cartilage breakdown (ie, cartilage oligomeric matrix protein [COMP], matrix metalloproteinase 3, ratio of type II collagen breakdown to type II collagen synthesis). Knee injury and Osteoarthritis Outcome Score surveys were completed at 12 months after ACLR and used to identify participants with and without clinically relevant PTOA-related symptoms. K-means cluster analyses were used to determine serum biomarker profiles. One-way analyses of variance and logistic regressions were used to assess differences in Knee injury and Osteoarthritis Outcome Score subscale scores and clinically relevant PTOA-related symptoms between biomarker profiles.

RESULTS

Two profiles were identified and characterized based on decreases (profile 1: 67% female; age, 21.4 ± 5.1 years; body mass index, 24.4 ± 2.4) and increases (profile 2: 33% female; age, 21.3 ± 3.2 years; body mass index, 23.4 ± 2.6) in sMCP-1 and sCOMP preoperatively to 6 months after ACLR. Participants with profile 2 did not demonstrate differences in knee pain, symptoms, activities of daily living, sports function, or quality of life at 12 months after ACLR compared to those with profile 1 (P = .56-.81; η2 = 0.002-0.012). No statistically significant associations were noted between biomarker profiles and clinically relevant PTOA-related symptoms (odds ratio, 1.30; 95% CI, 0.23-6.33).

CONCLUSION

Serum biomarker changes in MCP-1 and sCOMP within the first 6 months after ACLR were not associated with clinically relevant PTOA-related symptoms.

Incidence of Osteoarthritis Between ACL Reconstruction With Different Graft Types and Between ACL Reconstruction and Repair: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background

Variation in stiffness, fixation methods, and donor-site morbidity after anterior cruciate ligament reconstruction (ACLR) with different graft types and with anterior cruciate ligament suture repair (ACLSR) can lead to differences in dynamic knee laxity and consequent differences in posttraumatic osteoarthritis (PTOA) development.

Purpose

To compare the incidence of PTOA between different graft types used for primary ACLR and between primary ACLR and ACLSR. It was hypothesized that the incidence of PTOA would vary between ACLR with different autografts and allografts and between ACLR and ACLSR.

Study Design

Systematic review; Level of evidence, 1.

Methods

A search of the literature was performed to identify all randomized controlled trials (RCTs) comparing radiographic evidence of PTOA after ACLR between different graft types-hamstring tendon (HT) autograft, bone-patellar tendon-bone (BPTB) autograft, quadriceps tendon autograft, and allograft-and between ACLR and ACLSR. The minimum follow-up was 2 years. Study quality was assessed using the modified Coleman Methodology Score. A meta-analysis was performed to determine whether there was a difference in the incidence of PTOA between the different graft types and between ACLR and ACLSR.

Results

Eleven randomized controlled trials were included in the meta-analysis-HT: 440 patients (mean follow-up, 9.7 years); BPTB: 307 patients (mean follow-up, 11.8 years); allograft: 246 patients (mean follow-up, 5 years); ACLSR, 22 patients (5 years). No study reporting the incidence after ACLR with quadriceps tendon was included. The study quality ranged from 70 to 88. The meta-analysis indicated no significant difference in the incidence of PTOA between graft types used for ACLR and between ACLR and ACLSR (risk ratios: HT vs BPTB, 1.05; HT vs allograft, 0.81; BPTB vs allograft, 0.82; HT vs ACLSR, not estimable [P > .05 for all]). The combined number of patients with PTOA in all studies per graft type showed that patients who underwent ACLR with a BPTB autograft had the highest percentage of PTOA (HT, 23.4%; BPTB, 29.6%; allograft, 8.1%; ACLSR, 0%). However, excluding studies with a follow-up <5 years resulted in similar outcomes for patients with an HT autograft and a BPTB autograft.

Conclusion

This meta-analysis reported no difference in the incidence of PTOA between graft types used for ACLR and between ACLR and ACLSR. More research is necessary to make a reliable conclusion about which technique is associated with the lowest incidence of PTOA after ACL surgery.

Longitudinal measurement of serum cartilage oligomeric matrix protein can detect the progression of cartilage degeneration in anterior cruciate ligament reconstruction patients

Background/objective

Cartilage oligomeric matrix protein (COMP) has utility as a diagnostic marker for osteoarthritis (OA). Our previous study revealed that the serum COMP level can be used to detect early cartilage change in non-OA patients with anterior cruciate ligament (ACL)-deficiency. However, there are still no studies on detecting the progression of cartilage degeneration in early OA. The aim of present study was to investigate whether serum COMP can detect the progression of cartilage degeneration after ACL reconstruction in non-OA patients.

Methods

Patients without cartilage degeneration of early OA at ACL reconstruction and whose serum COMP levels could be measured were included in the study. Cartilage degeneration of early OA were defined as International Cartilage Repair Society (ICRS) grade 1 to 4 in more than 2 compartments or ICRS grade 2 to 4 in 1 compartment. The patients were divided into two groups: those who had cartilage degeneration of early OA at second-look arthroscopy (cartilage degeneration progression group) and those who did not (non-progression group), and the serum COMP values between the two groups were compared.

Results

Thirty-one patients were included. There were 8 cases (25.8 %) in progression group and 23 cases (74.2 %) in non-progression group. There were significant differences between the two groups regarding age and change in serum COMP level. In terms of the rate of change in COMP, an increase of more than 1.24-fold was the cut-off value for detecting the progression of cartilage degeneration.

Conclusions

In this study, the increase in serum COMP levels was significantly greater in progressed cartilage degeneration group than non-progression group after ACL reconstruction. Longitudinal serum COMP measurement could detect the progression of cartilage degeneration.

Level of evidence

Level Ⅲ, retrospective comparative study.

Longitudinal Changes in Quadriceps Morphology over the First 3 Months after Anterior Cruciate Ligament Reconstruction

PURPOSE

Neuromuscular deficits and atrophy after anterior cruciate ligament reconstruction (ACLR) may be accompanied by changes in muscle composition and poor quadriceps muscle quality (QMQ). Quadriceps atrophy occurs after ACLR but improves within the first three postoperative months, yet this hypertrophy could be attributable to increases in noncontractile tissue (i.e., poor QMQ). The purposes of this study were to evaluate changes in QMQ after ACLR and to determine if changes in QMQ and cross-sectional area (CSA) occur in parallel or independently.

METHODS

A longitudinal prospective cohort design was implemented to evaluate QMQ and CSA in 20 individuals with ACLR and 12 healthy controls. Participants completed three testing sessions (baseline/presurgery, 1 month, and 3 months) during which ultrasound images were obtained from the vastus lateralis (VL) and rectus femoris (RF). QMQ was calculated as the echo intensity (EI) of each image, with high EI representing poorer QMQ. Anatomical CSA was also obtained from each image.

RESULTS

RF and VL EI were greater at 1 and 3 months in the ACLR limb compared with baseline and the contralateral limb and did not change between 1 and 3 months. VL and RF CSA in the ACLR limb were smaller at 1 and 3 months compared with the contralateral limb and controls (VL only) but increased from 1 to 3 months. Changes in QMQ and CSA were not correlated.

CONCLUSIONS

QMQ declines within the first month after ACLR and does not improve by 3 months although hypertrophy occurs, suggesting that these morphological characteristics change independently after ACLR. Poorer QMQ represents greater concentration of noncontractile tissues within the muscle and potentially contributes to chronic quadriceps dysfunction observed after ACLR.

No Association Between Injury-Related Fear and Isokinetic Quadriceps Strength in Individuals With a History of Anterior Cruciate Ligament Reconstruction

CONTEXT

Injury-related fear and quadriceps strength are independently associated with secondary anterior cruciate ligament (ACL) injury risk. It is not known whether injury-related fear and quadriceps strength are associated, despite their individual predictive capabilities of secondary ACL injury. The purpose of this study was to examine the association between injury-related fear and quadriceps strength in individuals at least 1 year after ACL reconstruction (ACLR).

DESIGN

Cross-sectional study.

METHODS

Forty participants between the ages of 18 and 35 years at least 1 year post unilateral primary ACLR. Participants completed the Tampa Scale of Kinesiophobia-11 (TSK-11) and a standard isokinetic quadriceps strength assessment using the Biodex Isokinetic Dynamometer. Pearson Product-Moment correlations were used to examine the linear association between the TSK-11 scores and peak torque (in nanometers per kilogram) for each limb and between the TSK-11 scores and limb symmetry indices for each limb. Pearson Product-Moment correlation coefficients (r) were interpreted as very high (.90-1.00), high (.70-.90), moderate (.50-.70), low (.30-.50), and no correlation (.00-.30).

RESULTS

The average TSK-11 score was 18.2 (5.3), average ACLR peak quadriceps torque was 1.9 (0.50) N·m/kg, average contralateral peak quadriceps torque was 2.3 (0.48) N·m/kg, and average limb symmetry index was 85.3% (12.6%). There was no statistically significant correlation between the TSK-11 and peak quadriceps torque on the ACLR limb (r = .12, P = .46), the TSK-11 and contralateral limb (r = .29, P = .07), or the TSK-11 and limb symmetry index (r = -.18, P = .27).

CONCLUSIONS

There was no association between kinesiophobia and peak isokinetic quadriceps strength in individuals at least 1 year post-ACLR. Both factors, independently, have been shown to influence risk of secondary injury in patients after ACLR.

Poincaré analysis detects pathological limb loading rate variability in post-anterior cruciate ligament reconstruction individuals

BACKGROUND

Post-ACLR individuals can experience repeated exposure to variable limb loading, which contributes to development of knee osteoarthritis. Variable limb loading can present as loading rate variability (LRV) and is magnified during tasks like fast walking when the system is stressed. Nonlinear measures that evaluate temporal variability have successfully detected changes in gait variability associated with altered motor control, however, appropriately describing and uncovering the nature of gait variability has been challenging. Here, Poincaré analysis, a nonlinear method unique in its ability to capture different aspects of variability, served to uncover and quantify changes in limb LRV. It was hypothesized that post-ACLR individuals' overloaded limbs would quantitatively and graphically demonstrate greater short-term stride-to-stride and long-term limb LRV during fast walking compared to the underloaded and healthy control limbs.

METHODS

Fourteen post-ACLR individuals and fourteen healthy controls completed a walking protocol on an instrumented treadmill where they walked at 1.0 m/s and 1.5 m/s for 5-minutes each. A Welch's test was performed to compare differences in short-term and long-term LRV metrics for the post-ACLR individuals' overloaded and underloaded limbs and the healthy controls' right limbs.

RESULTS

Analyses revealed that the post-ACLR individuals' overloaded limb exhibited significantly greater short-term and long-term values compared to the underloaded and healthy control limbs at 1.5 m/s (p<0.05). Additionally, the loading rate data was widely scattered across the plots for the overloaded limb, indicating greater LRV.

SIGNIFICANCE

Poincaré analysis successfully identified that post-ACLR overloaded limbs exhibited impaired motor control during fast walking based on quantitative and graphical changes in variability. This highlights the clinical applications of Poincaré analysis, with the plots potentially serving as an easy-to-interpret diagnostic tool for pathological limb LRV.

Femoral cartilage ultrasound echo-intensity is a valid measure of cartilage composition

This study aimed to create a conversion equation that accurately predicts cartilage magnetic resonance imaging (MRI) T2 relaxation times using ultrasound echo-intensity and common participant demographics. We recruited 15 participants with a primary anterior cruciate ligament reconstruction between the ages of 18 and 35 years at 1-5 years after surgery. A single investigator completed a transverse suprapatellar scan with the ACLR limb in max knee flexion to image the femoral trochlea cartilage. A single reader manually segmented the femoral cartilage cross-sectional area to assess the echo-intensity (i.e., mean gray-scale pixel value). At a separate visit, a T2 mapping sequence with the MRI beam set to an oblique angle was used to image the femoral trochlea cartilage. A single reader manually segmented the cartilage cross-sectional area on a single MRI slice to assess the T2 relaxation time. A stepwise, multiple linear regression was used to predict T2 relaxation time from cartilage echo-intensity and common demographic variables. We created a conversion equation using the regression betas and then used an ICC and Bland-Altman plot to assess agreement between the estimated and true T2 relaxation time. Cartilage ultrasound echo-intensity and age significantly predicted T2 relaxation time (F = 7.33, p = 0.008, R2 = 0.55). When using the new conversion equation to estimate T2 relaxation time from cartilage echo-intensity and age, there was strong agreement between the estimated and true T2 relaxation time (ICC2,k = 0.84). This study provides promising preliminary data that cartilage echo-intensity combined with age can be used as a clinically accessible tool for evaluating cartilage composition.

Modifying loading during gait leads to biochemical changes in serum cartilage oligomeric matrix protein concentrations in a subgroup of individuals with anterior cruciate ligament reconstruction

PURPOSE

Strong observational evidence has linked changes in limb loading during walking following anterior cruciate ligament reconstruction (ACLR) to posttraumatic osteoarthritis (PTOA). It remains unknown if manipulating peak loading influences joint tissue biochemistry. Thus, the purpose of this study is to determine whether manipulating peak vertical ground reaction force (vGRF) during gait influences changes in serum cartilage oligomeric matrix protein (sCOMP) concentrations in ACLR participants.

METHODS

Forty ACLR individuals participated in this randomized crossover study (48% female, age = 21.0 ± 4.4 years, BMI = 24.6 ± 3.1). Participants attended four sessions, wherein they completed one of four biofeedback conditions (habitual loading (no biofeedback), high loading (5% increase in vGRF), low loading (5% decrease in vGRF), and symmetrical loading (between-limb symmetry in vGRF)) while walking on a treadmill for 3000 steps. Serum was collected before (baseline), immediately (acute post), 1 h (1 h post), and 3.5 h (3.5 h post) following each condition. A comprehensive general linear mixed model was constructed to address the differences in sCOMP across all conditions and timepoints in all participants and a subgroup of sCOMP Increasers.

RESULTS

No sCOMP differences were found across the entire cohort. In the sCOMP Increasers, a significant time × condition interaction was found (F9,206 = 2.6, p = 0.009). sCOMP was lower during high loading than low loading (p = 0.009) acutely (acute post). At 3.5 h post, sCOMP was higher during habitual loading than symmetrical loading (p = 0.001).

CONCLUSION

These data suggest that manipulating lower limb loading in ACLR patients who habitually exhibit an acute increase in sCOMP following walking results in improved biochemical changes linked to cartilage health. Key Points • This study assesses the mechanistic link between lower limb load modification and joint tissue biochemistry at acute and delayed timepoints. • Real-time biofeedback provides a paradigm to experimentally assess the mechanistic link between loading and serum biomarkers. • Manipulating peak loading during gait resulted in a metabolic effect of lower sCOMP concentrations in a subgroup of ACLR individuals. • Peak loading modifications may provide an intervention strategy to mitigate the development of PTOA following ACLR.

Sustained Limb-Level Loading: A Ground Reaction Force Phenotype Common to Individuals at High Risk for and Those With Knee Osteoarthritis

OBJECTIVE

The objective of this study was to compare the vertical (vGRF), anterior-posterior (apGRF), and medial-lateral (mlGRF) ground reaction force (GRF) profiles throughout the stance phase of gait (1) between individuals 6 to 12 months post-anterior cruciate ligament reconstruction (ACLR) and uninjured matched controls and (2) between ACLR and individuals with differing radiographic severities of knee osteoarthritis (KOA), defined as Kellgren and Lawrence (KL) grades KL2, KL3, and KL4.

METHODS

A total of 196 participants were included in this retrospective cross-sectional analysis. Gait biomechanics were collected from individuals 6 to 12 months post-ACLR (n = 36), uninjured controls matched to the ACLR group (n = 36), and individuals with KL2 (n = 31), KL3 (n = 67), and KL4 osteoarthritis (OA) (n = 26). Between-group differences in vGRF, apGRF, and mlGRF were assessed in reference to the ACLR group throughout each percentage of stance phase using a functional linear model.

RESULTS

The ACLR group demonstrated lower vGRF and apGRF in early and late stance compared to the uninjured controls, with large effects (Cohen's d range: 1.35-1.66). Conversely, the ACLR group exhibited greater vGRF (87%-90%; 4.88% body weight [BW]; d = 0.75) and apGRF (84%-94%; 2.41% BW; d = 0.79) than the KL2 group in a small portion of late stance. No differences in mlGRF profiles were observed between the ACLR and either the uninjured controls or the KL2 group. The magnitude of difference in GRF profiles between the ACLR and OA groups increased with OA disease severity.

CONCLUSION

Individuals 6 to 12 months post-ACLR exhibit strikingly similar GRF profiles as individuals with KL2 KOA, suggesting both patient groups may benefit from targeted interventions to address aberrant GRF profiles.

Knee osteoarthritis: A review of animal models and intervention of traditional Chinese medicine

BACKGROUND

Knee osteoarthritis (KOA) characterized by degeneration of knee cartilage and subsequent bone hyperplasia is a prevalent joint condition primarily affecting aging adults. The pathophysiology of KOA remains poorly understood, as it involves complex mechanisms that result in the same outcome. Consequently, researchers are interested in studying KOA and require appropriate animal models for basic research. Chinese herbal compounds, which consist of multiple herbs with diverse pharmacological properties, possess characteristics such as multicomponent, multipathway, and multitarget effects. The potential benefits in the treatment of KOA continue to attract attention.

PURPOSE

This study aims to provide a comprehensive overview of the advantages, limitations, and specific considerations in selecting different species and methods for KOA animal models. This will help researchers make informed decisions when choosing an animal model.

METHODS

Online academic databases (e.g., PubMed, Google Scholar, Web of Science, and CNKI) were searched using the search terms "knee osteoarthritis," "animal models," "traditional Chinese medicine," and their combinations, primarily including KOA studies published from 2010 to 2023.

RESULTS

Based on literature retrieval, this review provides a comprehensive overview of the methods of establishing KOA animal models; introduces the current status of advantages and disadvantages of various animal models, including mice, rats, rabbits, dogs, and sheep/goats; and presents the current status of methods used to establish KOA animal models.

CONCLUSION

This study provides a review of the animal models used in recent KOA research, discusses the common modeling methods, and emphasizes the role of traditional Chinese medicine compounds in the treatment of KOA.

Quadriceps composition and function influence downhill gait biomechanics >1 year following anterior cruciate ligament reconstruction

BACKGROUND

Quadriceps dysfunction is common following anterior cruciate ligament reconstruction and contributes to aberrant gait biomechanics. Changes in quadriceps composition also occur in these patients including greater concentrations of non-contractile tissue. The purpose of this study was to evaluate associations between quadriceps composition, function, and gait biomechanics in individuals with anterior cruciate ligament reconstruction.

METHODS

Forty-eight volunteers with anterior cruciate ligament reconstruction completed gait biomechanics and quadriceps function and composition assessments. Gait biomechanics were sampled during downhill walking (-10° slope) on an instrumented treadmill. Quadriceps function (peak torque and rate of torque development) was assessed via maximal isometric contractions, while composition was evaluated via ultrasound echo intensity.

FINDINGS

Greater quadriceps peak torque was associated with a greater peak knee extension moment (r = 0.365, p = 0.015). Greater vastus lateralis echo intensity (i.e. poorer muscle quality) was associated with less knee flexion displacement (r = -0.316, p = 0.032). Greater echo intensity of the vastus lateralis (r = -0.298, p = 0.044) and rectus femoris (r = -0.322, p = 0.029) was associated with a more abducted knee angle at heel strike. Quadriceps peak torque explained 11-16% of the variance in echo intensity.

INTERPRETATION

Both quadriceps function and composition influence aberrant gait biomechanics following anterior cruciate ligament reconstruction. Quadriceps composition appears to provide insight into quadriceps dysfunction independent of muscle strength, as they associated with different gait biomechanics outcomes and shared minimal variance. Future research is necessary to determine the influence of changes in quadriceps composition on joint health outcomes.

Quadriceps and Hamstrings Activation Peaks Earlier as Athletes Repeatedly Hop, but There are Differences Depending on ACL Reconstruction Technique

Background

After Anterior Cruciate Ligament Reconstruction (ACLR) athletes face the challenge of regaining their previous competitive level while avoiding re-injury and early knee joint cartilage degeneration. Quadriceps and hamstrings strength reductions and neuromuscular alterations potentially related to risk of re-injury are present after ACLR and relate to deficits in muscle activation.

Design

Cross-sectional laboratory study.

Purpose

To examine quadriceps and hamstrings muscle activation during repeated hops in healthy pivoting-sport athletes and those who had undergone ACLR (bone-tendon-bone and semitendinosus graft) who had met functional criteria allowing return to training.

Methods

Surface electromyography (SEMG) was recorded from vastus medialis and lateralis and medial and lateral hamstrings bilaterally during 30 seconds' repeated hopping in male athletes on average eight months after ACLR surgery (5-12 months). All patients underwent hamstring (HS) (n=24) or bone-tendon-bone (BTB) reconstruction (n=20) and were compared to healthy controls (n=31). The SEMG signals were normalized to those obtained during maximal voluntary isometric contraction.

Results

A significant time shift in peak muscle activation (earlier) was seen for: vastus medialis and vastus lateralis activation in the control group, in the BTB group's healthy (but not injured) leg and both legs of the HS group. A significant time shift in peak muscle activation was seen for lateral hamstrings (earlier) in all but the BTB group's injured leg and the medial hamstrings in the control group only. Lower peak activation levels of the vastus lateralis (p\<0.001) and vastus medialis (p\<0.001) were observed in the injured compared to healthy legs and lower peak lateral hamstrings activity (p\<0.009) in the injured leg compared to control leg. Decline in medial hamstring peak activation (p\<0.022) was observed between 1st and 3rd phase of the hop cycle in all groups.

Conclusion

Repeated hop testing revealed quadriceps and hamstring activation differences within ACLR athletes, and compared to healthy controls, that would be missed with single hop tests.

Level of evidence

3.

Patients with higher numbers of allergies have lower levels of anti-inflammatory cytokines and increased pain at the time of ACL reconstruction

BACKGROUND

Synovial fluid biomarkers are well studied indicators of inflammation and healing in the setting of orthopedic injuries. However, it has not been studied if patients with one or more allergies have a difference in the concentrations of synovial fluid inflammatory cytokines compared to patients without allergies. The purpose of the current study is to analyze the concentration of 10 pro- and anti-inflammatory cytokines in the synovial fluid of isolated ACL injury patients with and without at least one allergy.

STUDY DESIGN

Retrospective Case-Control.

METHODS

A database of patients who underwent surgery for isolated ACL injury between September 2011 and July 2023 was analyzed. All patients had SF aspirated from the operative knee prior to the surgical incision and the concentrations of pre- and anti-inflammatory biomarkers were quantified. From this cohort, 24 patients were identified to have allergies by chart review. These patients were matched 1:1 to 24 patients without allergies based on age and sex.

RESULTS

There were no significant differences between the allergy and no allergy cohorts with respect to age (28.5 ± 10.3 vs. 29.5 ± 8.9, p = 0.76) and sex (70.8 % female vs. 70.8 % female, p = 1.00). The allergy cohort had a decreased concentration of TIMP-1 (492.41 ± 616.20 ng/mL vs. 1041.48 ± 942.04 ng/mL, p = 0.03) and IL-1Ra (101.70 ± 93.37 pg/mL vs. 359.94 ± 399.77 pg/mL, p = 0.01) compared to patients without allergies. A linear regression analysis found a significant association between increasing number of patients reported allergies and decreasing concentration of TIMP-1 (β = -231.59, p = 0.03) and IL-1Ra (β = -71.69p = 0.03) concentrations when controlling for age and sex. Finally, the allergy cohort was found to have a significantly higher value for the VAS pain scale at the time of surgery (26.84 ± 24.73 vs. 7.37 ± 10.98, p < 0.01) compared to those without an allergy.

CONCLUSION

Patients undergoing ACL reconstruction with at least one allergy were found to have decreased concentrations of the anti-inflammatory cytokines TIMP-1 and IL-1Ra in their synovial fluid compared to those without allergies on the day of surgery. Furthermore, an increase in total number of allergies was found to be an associated with a decrease in TIMP-1 and IL-1Ra levels. Finally, the allergy cohort also had a higher value for the VAS pain scale at the time of surgery, implicating the role of a patient's innate immune system to their biologic and symptomatic response to injury.

Quantitative Magnetic Resonance Imaging of Lateral Compartment Articular Cartilage After Lateral Extra-articular Tenodesis

BACKGROUND

Concerns have arisen that anterior cruciate ligament reconstruction (ACLR) with lateral extra-articular tenodesis (LET) may accelerate the development of posttraumatic osteoarthritis in the lateral compartment of the knee.

PURPOSE/HYPOTHESIS

The purpose of this study was to evaluate whether the augmentation of ACLR with LET affects the quality of lateral compartment articular cartilage on magnetic resonance imaging (MRI) at 2 years postoperatively. We hypothesized that there would be no difference in T1rho and T2 relaxation times when comparing ACLR alone with ACLR + LET.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A consecutive subgroup of patients at the Fowler Kennedy Sport Medicine Clinic participating in the STABILITY 1 Study underwent bilateral 3-T MRI at 2 years after surgery. The primary outcome was T1rho and T2 relaxation times. Articular cartilage in the lateral compartment was manually segmented into 3 regions of the tibia (lateral tibia [LT]-1 to LT-3) and 5 regions of the femur (lateral femoral condyle [LFC]-1 to LFC-5). Analysis of covariance was used to compare relaxation times between groups, adjusted for lateral meniscal tears and treatment, cartilage and bone marrow lesions, contralateral relaxation times, and time since surgery. Semiquantitative MRI scores according to the Anterior Cruciate Ligament OsteoArthritis Score were compared between groups. Correlations were used to determine the association between secondary outcomes (including results of the International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, Lower Extremity Functional Scale, 4-Item Pain Intensity Measure, hop tests, and isokinetic quadriceps and hamstring strength tests) and cartilage relaxation.

RESULTS

A total of 95 participants (44 ACLR alone, 51 ACLR + LET) with a mean age of 18.8 years (61.1% female [58/95]) underwent 2-year MRI (range, 20-36 months). T1rho relaxation times were significantly elevated for the ACLR + LET group in LT-1 (37.3 ± 0.7 ms vs 34.1 ± 0.8 ms, respectively; P = .005) and LFC-2 (43.9 ± 0.9 ms vs 40.2 ± 1.0 ms, respectively; P = .008) compared with the ACLR alone group. T2 relaxation times were significantly elevated for the ACLR + LET group in LFC-1 (51.2 ± 0.7 ms vs 49.1 ± 0.7 ms, respectively; P = .03) and LFC-4 (45.9 ± 0.5 ms vs 44.2 ± 0.6 ms, respectively; P = .04) compared with the ACLR alone group. All effect sizes were small to medium. There was no difference in Anterior Cruciate Ligament OsteoArthritis Scores between groups (P = .99). Weak negative associations (rs = -0.27 to -0.22; P < .05) were found between relaxation times and quadriceps and hamstring strength in the anterolateral knee, while all other correlations were nonsignificant (P > .05).

CONCLUSION

Increased relaxation times demonstrating small to medium effect sizes suggested early biochemical changes in articular cartilage of the anterolateral compartment in the ACLR + LET group compared with the ACLR alone group. Further evidence and long-term follow-up are needed to better understand the association between these results and the potential risk of the development of osteoarthritis in our patient cohort.

Ultrasound assessment of the infrapatellar fat pad can detect Hoffa-synovitis in patients following anterior cruciate ligament reconstruction: A pilot study

Introduction

Osteoarthritis (OA) commonly occurs following anterior cruciate ligament reconstruction (ACLR), affecting over 50 % of patients within 10-15 years post-ACLR. The Hoffa-synovitis of the infrapatellar fat pad (IPFP) has been implicated as a major contributor to OA pathogenesis. While MRI is typically used to evaluate the IPFP, it is cost-prohibitive for routine screening. This study aimed to validate ultrasound as an alternative for detecting IPFP Hoffa-synovitis in participants post-ACLR.

Methods

In this cross-sectional study, 15 participants (18-35 years, 1-5 years post-ACLR) underwent two imaging sessions separated by one week. First, a standardized bilateral anterior knee ultrasound assessment was used to examine IPFP echo-intensity. Second, MRI scans of both knees were graded by a board-certified musculoskeletal radiologist for Hoffa-synovitis according to the Anterior Cruciate Ligament Osteoarthritis Score grading system. IPFP echo-intensity were quantified on each ultrasound image, and a limb symmetry index (LSI) was calculated to assess between-limb differences. We used an independent t-test and Cohen's d effect sizes to compare IPFP echo-intensity LSI between people with and without MRI-confirmed Hoffa-synovitis.

Results

Four of the 15 participants (27 %) exhibited MRI-confirmed Hoffa-synovitis. Significantly higher IPFP echo-intensity LSI values were found in participants with Hoffa-synovitis (32.1 ± 12.1 %) compared to those without (10.5 ± 10.4 %), confirming the ultrasound's ability to distinguish between the two groups (t = -3.44; p = 0.004; d = 2.01).

Discussion

Ultrasound detects bilateral IPFP signal intensity alterations in participants post-ACLR with MRI-confirmed Hoffa-synovitis. This work should be seen as a proof-of-concept, and further validation in a larger, more diverse sample is essential for verifying these results.

Acutely Normalizing Walking Speed Does Not Normalize Gait Biomechanics Post-Anterior Cruciate Ligament Reconstruction

PURPOSE

To determine the effect of acutely increasing walking speed on gait biomechanics in ACLR individuals compared with their habitual speed and uninjured matched-controls.

METHODS

Gait biomechanics were collected on 30 ACLR individuals (20 females; age, 22.0 ± 4.2 yr; body mass index, 24.0 ± 3.0 kg·m -2 ) at their habitual speed and at 1.3 m·s -1 , a speed similar to controls, and 30 uninjured matched-controls (age: 21.9 ± 3.8, body mass index: 23.6 ± 2.5) at their habitual speed. Functional waveform analyses compared biomechanics between: i) walking at habitual speed vs 1.3 m·s -1 in ACLR individuals; and ii) ACLR individuals at 1.3 m·s -1 vs controls.

RESULTS

In the ACLR group, there were no statistically significant biomechanical differences between walking at habitual speed (1.18 ± 0.12 m·s -1 ) and 1.3 m·s -1 (1.29 ± 0.05 m·s -1 ). Compared with controls (habitual speed: 1.34 ± 0.12 m·s -1 ), the ACLR group while walking at 1.3 m·s -1 exhibited smaller vertical ground reaction force (vGRF) during early and late stance (13-28, 78-90% stance phase), greater midstance vGRF (47-61%), smaller early-to-midstance knee flexion angle (KFA; 1-44%), greater mid-to-late stance KFA (68-73, 96-101%), greater internal knee abduction moment (69-101%), and smaller internal knee extension moment (4-51, 88-96%).

CONCLUSIONS

Increasing walking speed to a speed similar to uninjured controls did not elicit significant changes to gait biomechanics, and ACLR individuals continued to demonstrate biomechanical profiles that are associated with PTOA development and differ from controls.

Physical Activity Associates with T1rho MRI of Femoral Cartilage After Anterior Cruciate Ligament Reconstruction

PURPOSE

Less physical activity has been associated with systemic biomarkers of cartilage breakdown after anterior cruciate ligament reconstruction (ACLR). However, previous research lacks analysis of deleterious cartilage compositional changes and objective physical activity after ACLR. The purpose of this study was to determine the association between physical activity quantified via accelerometer-based measures of daily steps and time in moderate-to-vigorous physical activity (MVPA), and T1rho magnetic resonance imaging (MRI) of the femoral articular cartilage, a marker of proteoglycan density in individuals with ACLR.

METHODS

Daily steps and MVPA were assessed over 7 d using an accelerometer worn on the hip in 26 individuals between 6 and 12 months after primary unilateral ACLR. Resting T1rho MRI was collected bilaterally, and T1rho MRI interlimb ratios (ILR: ACLR limb/contralateral limb) were calculated for lateral and medial femoral condyle regions of interest. We conducted univariate linear regression analyses to determine associations between T1rho MRI ILRs and daily steps and MVPA with and without controlling for sex.

RESULTS

Greater T1rho MRI ILR of the central lateral femoral condyle, indicative of less proteoglycan density in the ACLR limb, was associated with greater time in MVPA ( R2 = 0.178, P = 0.032). Sex-adjusted models showed significant interaction terms between daily steps and sex in the anterior ( P = 0.025), central ( P = 0.002), and posterior ( P = 0.002) medial femoral condyle.

CONCLUSIONS

Lesser physical activity may be a risk factor for maintaining cartilage health after ACLR; additionally, the relationship between physical activity and cartilage health may be different between males and females.

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

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

Outcomes >30 Years After Initial Nonoperative Treatment of Anterior Cruciate Ligament Injuries

BACKGROUND

It is unclear how anterior cruciate ligament (ACL) reconstruction (ACLR) affects the development of osteoarthritis (OA). This uncertainty is partly caused by the lack of long-term studies on ACL injuries treated primarily without reconstruction and the underreporting of symptomatic OA.

PURPOSE

To determine (1) the knee function, symptoms, and activity level, as well as the presence of radiographic and symptomatic OA; (2) how these clinical outcomes have changed over time; and (3) the frequency of subsequent knee surgeries after the index ACL injury in a cohort of patients with ACL injuries treated primarily without reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 100 patients underwent initial nonoperative treatment >30 years ago (mean, 33.2 ± 1.4 years). Of these, 81 patients (mean age, 59 ± 8 years) completed the Knee injury and Osteoarthritis Outcome Score (KOOS), Lysholm Knee Scoring Scale, and Tegner Activity Scale. Seventy-three patients underwent radiography to evaluate tibiofemoral and patellofemoral OA in the ACL-injured knee. Patients only underwent late ACLR if they experienced insufficient knee stability.

RESULTS

At 33 years after the ACL injury, the KOOS Activities of Daily Living subscore was better than population-based reference values, but scores were similar for the remaining KOOS subscales. Furthermore, 65% of patients had a good or excellent Lysholm score (≥84 points). The Tegner score decreased 4 points from before the injury to 33-year follow-up (P < .001). Most patients (75%) had evidence of radiographic tibiofemoral and/or patellofemoral OA, but only 38% were classified as having symptomatic OA (defined as radiographic OA in combination with a symptomatic knee according to cutoffs on the KOOS). Approximately 50% underwent meniscal surgery, and 29% subsequently underwent ACLR for recurrent instability. There were 2 patients who underwent total knee replacement.

CONCLUSION

Despite a high prevalence of radiographic OA, patients achieved acceptable subjective knee function and had a relatively low prevalence of symptomatic OA at >30 years after an ACL injury when an initial nonoperative treatment strategy was employed.