An Atlas of the Knee Joint Proteins and Their Role in Osteoarthritis Defined by Literature Mining.

Osteoarthritis (OA) is the most prevalent rheumatic pathology. However, OA is not simply a process of wear and tear affecting articular cartilage but rather a disease of the entire joint. One of the most common locations of OA is the knee. Knee tissues have been studied using molecular strategies, generating a large amount of complex data. As one of the goals of the Rheumatic and Autoimmune Diseases initiative of the Human Proteome Project, we applied a text-mining strategy to publicly available literature to collect relevant information and generate a systematically organized overview of the proteins most closely related to the different knee components. To this end, the PubPular literature-mining software was employed to identify protein-topic relationships and extract the most frequently cited proteins associated with the different knee joint components and OA. The text-mining approach searched over eight million articles in PubMed up to November 2022. Proteins associated with the six most representative knee components (articular cartilage, subchondral bone, synovial membrane, synovial fluid, meniscus, and cruciate ligament) were retrieved and ranked by their relevance to the tissue and OA. Gene ontology analyses showed the biological functions of these proteins. This study provided a systematic and prioritized description of knee-component proteins most frequently cited as associated with OA. The study also explored the relationship of these proteins to OA and identified the processes most relevant to proper knee function and OA pathophysiology.

Bone marrow stromal and anterior cruciate ligament remnant cell co-culture-derived extracellular vesicles promote cell activity in both cell types.

The significance of anterior cruciate ligament (ACL) remnants during reconstruction remains unclear. Co-culturing ACL remnant cells and bone marrow stromal cells (BMSCs) may reduce apoptosis and enhance hamstring tendon activity. This study investigated whether extracellular vesicles (EVs), which facilitate cell-cell interactions, act as the active components, improving graft maturation in this co-culture. The effects of EVs on cell viability, proliferation, migration and gene expression in the rabbit ACL remnant cells and BMSCs were assessed using control (BMSC-only culture), co-culture (ACL remnant cells and BMSCs, CM) and co-culture without EVs (CM ∆ EVs) media. EVs were isolated from control (BMSC-EV) and co-culture (CM-EV) media and characterized. CM significantly enhanced the proliferation, migration and expression of transforming growth factor (TGF-ß)-, vascular endothelial growth factor (VEGF)-, collagen synthesis- and tenogenesis-related genes. However, CM-induced effects were reversed by the CM ∆ EVs treatment. CM-EV treatment exhibited higher potential to enhance proliferation, migration and gene expression in the ACL remnant cells and BMSCs than BMSC-EV and non-EV treatments. In conclusion, EVs, secreted under the coexistence of ACL remnant cells and BMSCs, primarily increase the cell viability, proliferation, migration and gene expression of collagen synthesis-, TGF-ß-, VEGF- and tenogenesis-related genes in both cell types.

Bone-patellar tendon-bone, hamstring, and quadriceps tendon autografts for anterior cruciate ligament reconstruction in skeletally immature patients: a systematic review.

INTRODUCTION: Historically, anterior cruciate ligament (ACL) ruptures in the paediatric age group were managed conservatively with bracing, casting, activity modification, and physical therapy. However, most of these patients had to reduce their sports activities, and secondary damages to the affected knee were prevalent. SOURCE OF DATA: Published scientific literature in Embase, Web of Science, PubMed, and Google Scholar databases. AREAS OF AGREEMENT: ACL reconstruction in children with open physes patients is debated. Any damage to the physes around the knee could lead to growth abnormalities and axial deviation of the knee. AREAS OF CONTROVERSY: Different grafts are available and suitable for ACL reconstruction in skeletally immature patients; however, which graft performs better remains unclear. GROWING POINTS: This systematic review compared bone-patellar tendon-bone (BPTB), hamstring tendon (HT), and quadriceps tendon (QT) autografts for ACL reconstruction in skeletally immature patients. The joint laxity, Patient-reported outcome measures (PROMs), return to sport, and complications were compared. AREAS TIMELY FOR DEVELOPING RESEARCH: In skeletally immature patients, HT, BPTB, and QT autografts for ACL reconstruction yielded good outcomes. Comparative studies are strongly required to establish the most suitable autograft.

Unraveling sex-specific risks of knee osteoarthritis before menopause: Do sex differences start early in life?

OBJECTIVE: Sufficient evidence within the past two decades have shown that osteoarthritis (OA) has a sex-specific component. However, efforts to reveal the biological causes of this disparity have emerged more gradually. In this narrative review, we discuss anatomical differences within the knee, incidence of injuries in youth sports, and metabolic factors that present early in life (childhood and early adulthood) that can contribute to a higher risk of OA in females. DESIGN: We compiled clinical data from multiple tissues within the knee joint-since OA is a whole joint disorder-aiming to reveal relevant factors behind the sex differences from different perspectives. RESULTS: The data gathered in this review indicate that sex differences in articular cartilage, meniscus, and anterior cruciate ligament are detected as early as childhood and are not only explained by sex hormones. Aiming to unveil the biological causes of the uneven sex-specific risks for knee OA, we review the current knowledge of sex differences mostly in young, but also including old populations, from the perspective of (i) human anatomy in both healthy and pathological conditions, (ii) physical activity and response to injury, and (iii) metabolic signatures. CONCLUSIONS: We propose that to close the gap in health disparities, and specifically regarding OA, we should address sex-specific anatomic, biologic, and metabolic factors at early stages in life, as a way to prevent the higher severity and incidence of OA in women later in life.

Early microRNA and metabolite changes after anterior cruciate ligament reconstruction surgery.

OBJECTIVES: Anterior cruciate ligament (ACL) reconstruction after injury does not prevent post-traumatic osteoarthritis (PTOA). Circulating microRNA (miRNA) and metabolite changes emerging shortly after ACL injury and reconstruction remain insufficiently defined, potentially harbouring early cues contributing to PTOA evolution. Moreover, their differential expression between females and males also may influence PTOA's natural trajectory. This study aims to determine alterations in plasma miRNA and metabolite levels in the early stages following ACL reconstruction and between females and males. METHODS: A cohort of 43 ACL reconstruction patients was examined. Plasma was obtained at baseline, 2 weeks, and 6 weeks post-surgery (129 biospecimens in total). High-throughput miRNA sequencing and metabolomics were conducted. Differentially expressed miRNAs and metabolites were identified using negative binomial and linear regression models, respectively. Associations between miRNAs and metabolites were explored using time and sex as co-variants, (pre-surgery versus 2 and 6 weeks post-surgery). Using computational biology, miRNA-metabolite-gene interaction and pathway analyses were performed. RESULTS: Levels of 46 miRNAs were increased at 2 weeks post-surgery compared to pre-surgery (baseline) using miRNA sequencing. Levels of 13 metabolites were significantly increased while levels of 6 metabolites were significantly decreased at 2 weeks compared to baseline using metabolomics. Hsa-miR-145-5p levels were increased in female subjects at both 2 weeks (log2-fold-change 0.71, 95%CI 0.22,1.20) and 6 weeks (log2-fold-change 0.75, 95%CI 0.07,1.43) post-surgery compared to males. In addition, hsa-miR-497-5p showed increased levels in females at 2 weeks (log2-fold-change 0.77, 95%CI 0.06,1.48) and hsa-miR-143-5p at 6 weeks (log2-fold-change 0.83, 95%CI 0.07,1.59). Five metabolites were decreased at 2 weeks post-surgery in females compared to males: L-leucine (-1.44, 95%CI -1.75,-1.13), g-guanidinobutyrate (-1.27, 95%CI 1.54,-0.99), creatinine (-1.17, 95%CI -1.44,-0.90), 2-methylbutyrylcarnitine (-1.76, 95%CI -2.17,-1.35), and leu-pro (-1.13, 95%CI -1.44,-0.83). MiRNA-metabolite-gene interaction analysis revealed key signalling pathways based on post-surgical time-point and in females versus males. CONCLUSION: MiRNA and metabolite profiles were modified by time and by sex early after ACL reconstruction surgery, which could influence surgical response and ultimately risk of developing PTOA.

Assessing the efficacy of the Stop OsteoARthritis (SOAR) program: A randomized delayed-controlled trial in persons at increased risk of early onset post-traumatic knee osteoarthritis.

OBJECTIVE: Assess the efficacy of an 8-week virtual, physiotherapist (PT)-guided knee health program (Stop OsteoARthritis (SOAR)) to improve knee extensor strength in individuals at risk of post-traumatic knee osteoarthritis (PTOA). METHOD: In this superiority, randomized delayed-control trial, persons aged 16-35 years, 1-4 years after a self-reported knee joint injury were randomly assigned (1:1) to receive the SOAR program immediately (experimental group) or after a 9-week delay (control group). SOAR includes 1) one-time Knee Camp (virtual PT-guided group education, knee assessment, 1:1 exercise and physical activity (PA) goal-setting); 2) Weekly personalized home-based exercise and PA program with tracking; 3) Weekly 1:1 PT counseling (virtual). The primary outcome was a change in isokinetic knee extensor strength (baseline to 9-weeks). Additional outcomes included change in self-reported knee-related quality-of-life (QOL), self-efficacy, self-management and kinesiophobia, and PA (accelerometer) at 9 and 18-weeks. Linear regression models estimated the effect of the 8-week intervention at the primary endpoint (9-week). RESULTS: 49 of 54 randomized participants completed the study (91%). Participants were a mean ± standard deviation age of 27 ± 5.0 years, and 2.4 ± 0.9 years post-injury. No mean between group differences for the primary (0.05; 95% confidence interval (CI): -0.10, 0.19) or other outcomes were seen at 9 weeks except for greater improvements in perceived self-management (Partner in Health Scale; 11.3/96, 95%CI: 5.5, 17.1) and kinesiophobia (Tampa Scale of Kinesiophobia; -4.4/33, 95%CI: -7.0, -1.8). CONCLUSION: For active persons with elevated risk of PTOA, an 8-week SOAR program did not change knee-related strength, QOL, self-efficacy, or PA, on average, but may benefit the ability to self-manage knee health and kinesiophobia.

Anterior cruciate ligament injury and age affect knee cartilage T2 but not thickness.

OBJECTIVE: To investigate the effect of unilateral anterior cruciate ligament (ACL) injury on cartilage thickness and composition, specifically laminar transverse relaxation time (T2) by magnetic resonance imaging (MRI), in younger and older participants and to compare within-person side differences in these parameters between ACL-injured and healthy controls. DESIGN: Quantitative double-echo steady-state 3 Tesla MRI-sequences were acquired in both knees of 85 participants in four groups: 20-30 years: healthy, HEA20-30, n = 24; ACL-injured, ACL20-30, n = 23; 40-60 years: healthy, HEA40-60, n = 24; ACL-injured, ACL40-60, n = 14 (ACL injury 2-10 years prior to study inclusion). Weight-bearing femorotibial cartilages were manually segmented; cartilage T2 and thickness were computed using custom software. Mean and side differences in subregional cartilage thickness, superficial and deep cartilage T2 were compared within and between groups using non-parametric statistics. RESULTS: Cartilage thickness did not differ within or between groups. Only the side difference in medial femorotibial cartilage thickness was greater in ACL20-30 than in HEA20-30. Deep zone T2 was longer in the ACL-injured than in the contralateral uninjured knees and than in healthy controls, especially in the lateral compartment. Most ACL-injured participants had side differences in femorotibial deep zone T2 above the threshold derived from controls. CONCLUSION: In the ACL-injured knee, early compositional differences in femorotibial cartilage (T2) appear to occur in the deep zone and precede cartilage thickness loss. These results suggest that monitoring laminar T2 after ACL injury may be useful in diagnosing and monitoring early articular cartilage changes.

Characterization of the CT-based risk factors for concomitant patellofemoral instability in patients with anterior cruciate ligament injury.

OBJECTIVES: Underestimation of concomitant patellofemoral instability in patients with anterior cruciate ligament (ACL) injury has aroused extensive attention. However, the characteristics of the combined injury is not well recognized. Hence, we aimed to characterize the features of the combined injury, and determine the radiographic risk factors. METHODS: Fifteen radiological parameters were identified after discussion and pilot-tested. Radiographic measurements were compared using the analysis of variance model with Tukey post hoc analysis. A stepwise binomial logistic regression was performed and a nomogram model combining the significant risk factors was created. The model performance was validated by C-index, calibration plot, and decision curve. RESULTS: A total of 204 patients (mean [SD] age, 25.1 [6.7] years; 108 [52.9%] male) were included. The final model was updated through regression analysis using 4 parameters as significant risk factors: lateral femoral condyle ratio (OR (95% CI), 1.194 (1.023 to 1.409)), medial anterior tibial subluxation (mATS) (OR (95% CI), 1.234 (1.065 to 1.446)), medial posterior plateau tibial angle (mPPTA) (OR (95% CI), 1.266 (1.088 to 1.500)), and trochlear depth (OR (95% CI), 0.569 (0.397 to 0.784)). C-index for the nomogram was 0.802 (95% CI, 0.731 to 0.873) and was confirmed to be 0.784 through bootstrapping validation. Calibration plot established a good agreement between prediction and observation. Decision curve analysis showed that if threshold probability was over 10%, using the nomogram adds more benefit than either all or none scheme. CONCLUSIONS: Lateral femoral condyle ratio, mATS, mPPTA, and trochlear depth are strong adverse predictors of patellofemoral instability in patients with ACL injury. CLINICAL RELEVANCE: This study characterizes the radiological features of the combined injury. Patellofemoral instability should be noted when treating ACL injuries. KEY POINTS: • The radiological characteristics of the combined ACL injury and patellofemoral instability is not well recognized. • Lateral femoral condyle ratio, mATS, mPPTA, and trochlear depth are predominant risk factors for patellofemoral instability in patients with ACL injury. • Patellofemoral instability should be noted when treating ACL injuries.

An in-vitro three-dimensional surgical simulation technique to predict tibial tunnel length in transtibial posterior cruciate ligament reconstruction.

BACKGROUND: During the transtibial posterior cruciate ligament (PCL) reconstruction, drilling depth excessively longer than the tibial tunnel length (TTL) is an important reason to cause popliteal neurovascular bundle injury when preparing the tibial tunnel. This study aims to develop an in-vitro three-dimensional surgical simulation technique to determine the TTL in anteromedial (AM) and anterolateral (AL) approaches. METHODS: A total of 63 knees' 3-dimensional (3D) computed tomography models were included in this study. The SuperImage system was used to reconstruct the 3D knee model and locate the tibial PCL site. The established 3D knee model and the coordinates of the tibial PCL site were imported into Rhinoceros 3D modeling software to simulate AM and AL tibial tunnel approaches with different tibial tunnel angles (TTA). The TTL and the tibial tunnel height (TTH) were measured in this study. RESULTS: In AM and AL tibial tunnel approaches, the TTL showed a strong correlation with the TTA (for AM: r = 0.758, p < 0.001; for AL: r = 0.727, p < 0.001). The best fit equation to calculate the TTL based on the TTA was Y = 1.04X + 14.96 for males in AM approach, Y = 0.93X + 17.76 for males in AL approach, Y = 0.92X + 14.4 for females in AM approach, and Y = 0.94X + 10.5 for females in AL approach. CONCLUSION: Marking the TTL on the guide pin or reamer could help to avoid the drill bit over-penetrated into the popliteal space to damage the neurovascular structure.

Inter-rater reliability in performing stifle goniometry in normal and cranial cruciate ligament disease affected dogs: a prospective randomized controlled study.

BACKGROUND: Goniometry can be performed clinically in dogs with cranial cruciate ligament disease (CCLD). The purpose of this study was (1) to compare reliability of stifle goniometry in dogs with CCLD and healthy dogs and (2) to investigate the effect of compliance on measurements. Dogs presented for surgical intervention for CCLD (CCL-Dogs; n = 15) and orthopedically healthy dogs (C-Dogs; n = 11) were enrolled in this prospective randomized controlled trial. In each dog, three observers randomly measured maximum stifle flexion (mSF) and maximum stifle extension (mSE) three times with a standard goniometer with the scale covered, while dog compliance was scored (Scores: C0: excellent - C4: poor). Intraclass correlation coefficient (ICC) was calculated for intra-/interobserver reliability. Effects on measurements were evaluated with mixed-effect models (MEM). RESULTS: Maximum stifle extension and mSE-compliance were significantly decreased in CCL-Dogs compared to C-Dogs (p ≤ 0.004), but mSF and mSF-compliance did not differ between groups. Intraobserver reliability was excellent for all dogs during mSE (ICC:0.75-0.99) and mSF (ICC:0.89-0.99). Interobserver reliability was excellent for mSF in both groups (ICC: C-Dogs:0.84, CCL-Dogs:0.9) and for mSE in CCL-Dogs (ICC:0.94) but only fair for mSE in C-Dogs (ICC:0.58). Robust MEM showed that the combined average of all mSE measurements of all three observers was affected by compliance in both groups (p < 0.001). This effect was not observed for single mSE-measurements by themselves. CONCLUSION: The results of this study indicate that compliance may affect goniometric stifle extension measurements in healthy and CCLD dogs. In a clinical setting, intra-/interobserver reliability was excellent for all measurements except for maximum stifle extension in healthy dogs.

Biomechanical effects of cranial closing wedge osteotomy on joint stability in normal canine stifles: an ex vivo study.

BACKGROUND: Cranial closing wedge osteotomy (CCWO) is a functional stabilisation technique for cranial cruciate ligament (CrCL) ruptures. This biomechanical study aimed to evaluate the influence of CCWO on the stability of the stifle joint. Eighteen Beagle stifle joints were divided into two groups: control and CCWO. The stifle joints were analyzed using a six-degree-of-freedom robotic joint biomechanical testing system. The joints were subjected to 30 N in the craniocaudal (CrCd) drawer and proximal compression tests and 1 Nm in the internal-external (IE) rotation test. Each test was performed with an extension position, 135°, and 120° of joint angle. RESULTS: The stifle joints were tested while the CrCLs were intact and then transected. In the drawer test, the CCWO procedure, CrCL transection, and stifle joint flexion increased CrCd displacement. The CCWO procedure and CrCL transection showed an interaction effect. In the compression test, the CCWO procedure decreased and CrCL transection and stifle joint flexion increased displacement. In the IE rotation test, CCWO, CrCL transection, and stifle joint flexion increased the range of motion. CONCLUSIONS: CCWO was expected to provide stability against compressive force but does not contribute to stability in the drawer or rotational tests. In the CCWO-treated stifle joint, instability during the drawer test worsened with CrCL transection. In other words, performing the CCWO procedure when the CrCL function is present is desirable for stabilizing the stifle joint.

Evaluation of Strength and Functional Ability of Soccer Players Two Years After Anterior Cruciate Ligament Reconstruction: A Cross-sectional Study.

OBJECTIVES: This study examines the strength and functional capacity of active soccer players two years post anterior cruciate ligament reconstruction (ACLR). METHODS: Sixteen players, two years post ACLR, participated. Isokinetic tests assessed Peak Torque (PT) for concentric and eccentric contractions, along with conventional (H/Qconv) and functional (H/Qfunc) H/Q ratios at various angular velocities. Functional ability was gauged through hop tests. Paired-Samples T Test compared PT and hop test values, as well as H/Qconv and H/Qfunc ratios between involved and non-involved limbs. Limb symmetry was evaluated using the Limb Symmetry Index (LSI). RESULTS: After two years, participants exhibited significant differences in concentric PT between limbs. The non-involved limb demonstrated superior performance at isokinetic speeds. Eccentrically, PT for knee extensors and flexors showed no significant disparities between the operated and non-operated limbs across all velocities tested. Most participants did not achieve LSI 90-110% for knee extensors and flexors. No noteworthy distinctions were observed in H/Qconv, H/Qfunc, and hop tests between limbs. The majority met LSI 90-110% in hop tests, except in the 30-second side hop (37%). CONCLUSIONS: Two years post ACLR, soccer players still manifest strength and functional deficits, heightening the risk of injury.

What makes an athlete? A scoping review: Assessing the use of the word athlete with anterior cruciate ligament rehabilitation review studies. Is there a standard?

The term athlete does not currently have an agreed definition or standardized use across the literature. We analyzed the use of the term "athlete" amongst review studies specific to Anterior Cruciate Ligament (ACL) rehabilitation to investigate if the term was justified in its use. A comprehensive review of a database was performed to identify review papers which used the term "athlete" in the title, and which were related to ACL rehabilitation and surveillance. These papers were analyzed and their source papers were extracted for review. Twenty-eight review papers were identified. Source studies were extracted and analyzed. After removal of duplicates 223 source papers were identified. Despite using the term "athlete" in the review study titles only 5/17 (10.7%) sufficiently justified the use of this term. The term athlete was used in 117/223 (52.5%) of the source studies. Of those, 78/117 source studies (66.7%) justified the term athlete. The remaining 39/117 (33.3%) papers where participants were stated to be athletes, gave no justification. The ambiguous use of the term athlete amongst published studies highlights the need for a definition or justification of the term to be used in studies. The lack of a standard definition leads to the potential for studies to dilute high quality data by the potentially differing rehabilitation requirements and access to resources available to those with varying exercise levels. The indiscriminate use of the term athlete could lead to participants with widely ranging physical activity levels being included in the same study, and being used to create clinical advice for all. Advice could potentially vary across those of differing physical activity levels.

People Are More Variable Than Their Hop Test Would Suggest: Hop Performance and Self-Reported Outcomes Over 11 Years Following ACL Reconstruction.

We aimed to report the trajectory of self-reported outcomes up to 11 years post-ACLR. We also explored the relationship between hop performance at 1 year and: (i) future self-reported knee outcomes; and (ii) risk of subsequent knee events. 124 participants (43 women, mean age 31 ± 8 years) were recruited at 1 year following hamstring-autograft ACLR. Hop performance was assessed with single-forward and side-hop tests. Follow-up was completed at 3 (n = 114), 5 (n = 89) and 11 years (n = 72) post-ACLR. Self-reported outcomes were assessed at each follow-up with the Knee injury Osteoarthritis Outcome Score (KOOS) pain and quality of life (QOL) subscales. Generalized linear mixed models estimated the relationship between hop performance and self-reported outcomes. Subsequent knee events (new injury/surgery) to either knee were recorded, with the relationship between hop performance and risk of subsequent knee events analyzed with Cox proportional hazards. Self-reported knee outcomes were stable (mean change < 10 points) across all timepoints but with major within-sample variability. There was a modest relationship between greater hop performance at 1 year and better future KOOS-pain (average marginal effect [AME] % improvement with + 1 cm single forward hop = 0.06% [95% CI 0.02-0.10]). A nonlinear spline relationship showed better single-forward hop performance was associated with better KOOS-QOL for scores < 108 cm, not present for higher hop scores > 108 cm. There were 21 index and 11 contralateral subsequent knee events. Hop performance was not related to risk of a subsequent knee event (hazard ratio index knee 0.99 [95% CI 0.98-1.02]). In conclusion, self-reported knee pain and quality of life were generally stable across the 11-year follow-up period. Greater hop performance at 1-year post-ACLR was related to better self-reported knee outcomes up to 11-year follow-up (of questionable clinical importance), but not associated with the risk of subsequent knee injury/surgery.

Location of Measurement Matters: Unveiling Regional Dynamics and Sex Differences in Patellar Tendon Strain In Vivo.

Patellar tendinopathy is more prevalent in males versus female athletes and commonly presents in the medial region of the tendon. Separate measures of patellar tendon strain in the medial, central, and lateral regions of the tendon, however, have not been quantified. The purpose was to investigate the differences in tendon strain between the medial, lateral, and central regions of the patellar tendon in healthy men and women. Strain in the medial and lateral regions of the patellar tendon in healthy participants (10 males, 10 females) was evaluated using ultrasound during isometric quadriceps contractions at 20%, 40%, 60%, 80%, and 100% of maximum voluntary contraction (MVIC) in 60° and 90° of knee flexion. Central strain was also measured at 60% MVIC in 90° of knee flexion. Mixed models were used to determine strain between tendon regions and sex at 60% MVIC in 90° of knee flexion. Sequential modeling was used to fit region, sex, %MVIC, and angle to predict strain. The central region had less strain compared with both medial and lateral regions. The lateral region had higher strain compared with the medial region regardless of sex. Females had higher strain compared with males, regardless of region. Knee position did not influence tendon strain. Patellar tendon strain differs by region and sex. The varying prevalence between sex and in location of patellar tendinopathy may in part be explained by the unbalanced strains. Differential assessment of regional patellar tendon strain may be of importance for understanding injury risk and recovery with exercise.

To achieve the unachievable-Patients' experiences of opting for delayed anterior cruciate ligament reconstruction after trying rehabilitation alone as primary treatment: A qualitative study.

INTRODUCTION: About 50% of patients who sustain an anterior cruciate ligament (ACL) injury are treated without ACL reconstruction (ACL-R). A significant proportion of these patients opt for late ACL-R. Patients' experience of changing treatment has not yet been investigated and presented in the scientific literature. AIM: To explore patients' experiences before and after changing treatment from ACL rehabilitation alone to ACL-R. METHOD: Fifteen patients were interviewed in semi-structured interviews, which were recorded, transcribed, and analyzed with qualitative content analysis, based on the method described by Graneheim and Lundman. Patients were between 26 and 58 years old, and had tried rehabilitation for a minimum of 9 months prior to ACL-R. RESULTS: Two themes, "Expecting what could not be achieved: the struggle to recover and not becoming stable", and "Internal completeness: expectations can be achieved", emerged from the analysis. Each theme was supported by three main categories and 5-6 subcategories. The first theme represents the journey before ACL-R, where patients experienced getting stronger, but perceived the knee as unstable. The second theme represents the journey after ACL-R, where patients expressed that they felt whole after their ACL-R, and where able to achieve their expections. Patients experienced a greater support from the healthcare system, and ultimately expressed a feeling of having achieved the unachievable after ACL-R. SUMMARY: Patients who cross over from ACL rehabilitation to ACL-R experienced rehabilitation alone as insufficient to achieve the desired outcomes, which resulted in a need to opt for delayed ACL-R. Healthcare providers need to support patients, who primarily choose to undergo rehabilitation alone and later opt for ACL-R, throughout the whole rehabilitation process.

In Vitro Assessment of Knee Joint Biomechanics Using a Virtual Anterior Cruciate Ligament Reconstruction.

Understanding the biomechanical impact of injuries and reconstruction of the anterior cruciate ligament (ACL) is vital for improving surgical treatments that restore normal knee function. The purpose of this study was to develop a technique that enables parametric analysis of the effect of the ACL reconstruction (ACLR) in cadaver knees, by replacing its contributions with that of a specimen-specific virtual ACLR that can be enabled, disabled, or modified. Twelve ACLR reconstructed knees were mounted onto a motion simulator. In situ ACLR graft forces were measured using superposition, and these data were used to design specimen-specific virtual ACLRs that would yield the same ligament force-elongation behaviors. Tests were then repeated using the virtual ACLR in place of the real ACLR and following that in ACL deficient knee by disabling the virtual ACLR. In comparison to the ACL deficient state, the virtual ACLRs were able to restore knee stability to the same extent as real ACLRs. The average differences between the anterior tibial translation (ATT) of the virtual ACLR versus the real ACLR were +1.6 ± 0.9 mm (p = 0.4), +2.1 ± 0.4 mm (p = 0.4), and +1.0 ± 0.9 mm (p = 0.4) during Anterior drawer, Lachman and Pivot-shift tests, respectively, which is small in comparison to the full ATT range of motion (ROM) of these knees. Therefore, we conclude that a virtual ACLR can be used in place of real ACLR during biomechanical testing of cadaveric knees. This capability opens the door for future studies that can leverage parameterization of the ACLR for surgical design optimization.

All-inside anterior cruciate ligament reconstruction with and without anterolateral ligament reconstruction: a prospective study.

BACKGROUND: There is no clear consensus regarding the superiority of a combined anterior cruciate ligament reconstruction (ACLR) with anterolateral ligament reconstruction (ALLR) versus an isolated ACLR. In this study, we compared the postoperative stability profile, complications, and patient-reported outcomes of these procedures. METHODS: Twenty-one patients with an anterior cruciate ligament (ACL) tear who were either treated by an isolated all-inside ACLR (n = 21) or a combined all-inside ACLR and ALLR (n = 20) were included. The outcomes were evaluated in the last follow-up and included the postoperative stability profile evaluated by the Lachman test, pivot shift test, and KT-1000 side-to-side difference, postoperative complications, and patient-reported outcomes evaluated by the International Knee Documentation Committee (IKDC) score and Lysholm knee scale. RESULTS: The baseline characteristics of the two groups were not significantly different. The residual Lachman and pivot shift were not significantly different between the two groups (P = 0.41 and P = 0.18, respectively). The mean KT-1000 side-to-side difference was 1.93 ± 1.9 mm in the isolated and 1.635 ± 0.91 mm in the combined group (P = 0.01). The mean improvement of the IKDC score was not significantly different between the isolated and combined groups (24.7 vs. 25.2, P = 0.28). The mean improvement of the Lysholm scale was not significantly different between the isolated and combined groups (33.5 vs. 34.1, P = 0.19). ACL re-rupture occurred in three patients of the isolated group and no patient of the combined group. CONCLUSION: The outcomes of patients in the present study support performing a combined ALL and ACL reconstruction.

Plastic and elastic biomechanical properties of anterior cruciate ligament autografts.

BACKGROUND: Anterior cruciate ligament (ACL) rupture is a common orthopedic injury, occurring in roughly 68.6 per 100,000 persons annually, with the primary treatment option being ACL reconstruction. However, debate remains about the appropriate graft type for restoring the native biomechanical properties of the knee. Furthermore, plastic graft elongation may promote increased knee laxity and instability without rupture. This study aims to investigate the plastic properties of common ACL-R graft options. METHODS: Patellar tendon (PT), hamstring tendon (HT), and quadriceps tendon (QT) grafts were harvested from 11 cadaveric knees (6 male and 5 female) with a mean age of 71(range 55-81). All grafts were mechanically tested under uniaxial tension until failure to determine each graft's elastic and plastic biomechanical properties. RESULTS: Mechanically, the QT graft was the weakest, exhibiting the lowest failure force and the lowest failure stress (QT < HT, p = 0.032). The PT was the stiffest of the grafts, having a significantly higher stiffness (PT > QT, p = 0.0002) and Young's modulus (PT > QT, p = 0.001; PT > HT, p = 0.041). The HT graft had the highest plastic elongation at 4.01 ± 1.32 mm (HT > PT, p = 0.002). The post-yield behavior of the HT tendon shows increased energy storage capabilities with the highest plastic energy storage (HT > QT, p = 0.012) and the highest toughness (HT > QT, p = 0.032). CONCLUSION: Our study agrees with prior studies indicating that the failure load of all grafts is above the requirements for everyday activities. However, grafts may be susceptible to yielding before failure during daily activities. This may result in the eventual loss of functionality for the neo-ACL, resulting in increased knee laxity and instability.

The significance of guiding anterior cruciate ligament revision: a modified femoral tunnel classification.

BACKGROUND: The positioning error of femoral tunnel was the key factor leading to the failure of anterior cruciate ligament (ACL) reconstruction. This study aimed to propose a new femoral tunnel classification to guide revision ACL reconstruction. METHODS: Totals of 150 patients with ACL reconstruction failure from 2017 to 2023 were enrolled in this retrospective study. According to the tunnel diameter, shape, posterior wall and the positioning relationship with the Lateral Intercondylar Ridge on the three-dimensional CT imaging, we divided the femoral tunnels into four types: Type I off-target type, Type II straddled type, Type III anatomical type, and Type IV irregular type. Finally, explored the inter-observer reliability within two groups of doctors (Group A, 12 high seniorities; Group B, 12 low seniorities), and evaluated the intra-observer reliability within 6 doctors after two months. Clinical evaluation was performed using the Lysholm score, Tenger activity score, Pivot Shift and anterior knee laxity measurements. RESULTS: Among 150 cases of femoral tunnel three-dimensional CT reconstructed imaging, 144 cases were successfully included in the classification system, and 6 cases were confirmed as uncertain type. We measured the Kappa (κ) coefficient of group A was significantly higher than that of group B (κ 0.72 VS 0.68), and the κ coefficient of group A was still higher than group B (κ 0.69 VS 0.62) after further dividing Type III anatomical type into three subtypes. In addition, the κ coefficients of intra-observer reliability were all exceeded 0.73. Clinical follow-up showed that 9 patients had good knee joint motor function and stability after operation. CONCLUSION: The new femoral tunnel classification was reliable and had clinical guiding significance based on three-dimensional CT imaging. LEVEL OF EVIDENCE: Level III.