Comparison of postoperative clinical outcomes and knee stability of cruciate-retaining total knee arthroplasty using the tibia-first gap navigation technique with a computer-aided system and measured-resection technique: A retrospective analysis of a propensity-matched cohort.

Purpose: This study aimed to clarify whether the range of motion (ROM), anterior and posterior (AP) stability and other clinical measures changed in patients who underwent tibia-first total knee arthroplasty (TF-TKA) using navigation with a computer-aided system after surgery. Methods: This is a retrospective study and we conducted a matched cohort analysis of 60 measured resection (MR)-TKAs and 52 TF-TKAs performed by a single surgeon. All the surgeries used the same implant and approach. Baseline differences between the groups were adjusted using propensity score matching. We compared each patient's measured ROM and Oxford Knee Score (OKS) and performed knee AP laxity measurements by using a device during routine follow-ups. Results: A total of 40 MR-TKAs with a mean age of 73.5 ± 5.6 years and sex (male 10, female 30) were compared to 40 TF-TKAs with a mean age of 74.0 ± 5.7 years and sex (male 13, female 27) at 2-year follow-ups. Two years postoperatively, there was a significant difference in the AP laxity at 30° of knee flexion between both groups (7.0 ± 3.4 mm vs. 5.2 ± 2.3 mm, p < 0.01). In contrast, no differences were found between both groups for knee flexion (120.8 ± 9° vs. 116.7 ± 9.8°, p = 0.07) and OKS score (41.8 ± 6.9 vs. 41.0 ± 5.9, p = 0.61). Conclusion: The AP stability in the midflexion obtained using the tibia-first technique remained consistent even after 2 years. However, OKS and ROM were not significantly different from those of the MR-TKA group. Level of Evidence: Retrospective comparative LEVEL III study.

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.

Achieving Specified Laxity in a Noncruciate Total Knee: A Laboratory Design Study.

BACKGROUND: Noncruciate total knee arthroplasty designs, including ultracongruent, medially congruent, and medial pivot, are gaining increasing attention in total knee arthroplasty surgery. However, there is no consensus for the bearing surface design, whether there should be different medial, lateral, anterior, and posterior laxities, or whether the medial side should be a medial pivot. This study proposes the criterion of reproducing the laxity of the anatomic knee, defined as the displacements and rotations of the femur on the tibia in the loaded knee when shear and torque are applied. The purpose of this study was to determine the ideal tibial radii to achieve that goal. METHODS: The femoral component was based on the average knee from 100 mild arthritic knee scans. There were 8 tibial components that were designed with different sagittal radii: antero-medial, antero-lateral, postero-medial, and postero-lateral. Radii were defined as the percent height reduction from full conformity with the femoral profile. Components were 3-dimensional-printed. A test rig was constructed where the tibial component was fixed and shear and torque were applied to the femoral component. Displacements and rotations of the femoral component were measured at 0 and 45° of flexion, the latter representing any flexion angle due to the constant femoral sagittal radius. RESULTS: Displacements ranged from 0 to 11 mm, and rotations ranged from 1 to 11°. Anterior femoral displacements were higher than posterior due to the shallow distal-anterior femoral profile. The final femoral and tibial components with the most closely matched anatomic laxity values were designed and tested. CONCLUSIONS: A steeper distal-anterior femoral radius was an advantage. High medial-anterior tibial conformity was important. However, on the lateral side, the posterior sagittal tibial radius had to be shallower than ideal to allow femoral rollback in high flexion. This meant that the posterior laxity displacements on the lateral side were higher than anatomic, and there was no guidance for lateral femoral rollback.

Relationship Between Intraoperative Macroscopic Anterior Cruciate Ligament Findings, Perioperative Surgical Findings, and Postoperative Clinical Outcome After Cruciate-Retaining Total Knee Arthroplasty.

PURPOSE: To assess how intraoperative macroscopical anterior cruciate ligament (ACL) findings affect perioperative procedures, biomarkers, and postoperative anterior-posterior (AP) laxity and range of motion (ROM) after cruciate-retaining (CR) total knee arthroplasty (TKA) and to determine how chronic ACL deficiency may affect postoperative inflammatory biomarker, AP laxity, and ROM. METHODS: A total of 121 patients with varus knee osteoarthritis without a history of ACL injury who underwent ATTUNE® (DePuy Synthes, Warsaw, IN) CR TKA were analyzed. Intraoperative ACL findings were stratified into intact, damaged, and diminished, according to the tension by probing, synovial coverage, and vascularity. C-reactive protein (CRP) levels were examined at one, seven, and 14 days after surgery. Knee AP laxity measurements using Kneelax 3 (Monitored Rehab Systems, Haarlem, The Netherlands) and postoperative knee ROM were also compared. RESULTS: One-way ANOVA showed significant differences in CRP levels examined one day after surgery observed between the three groups (8.4 (3.8), 9.8 (4.3), and 13.2 (7.7) mg/dL, respectively; P = 0.018), with post hoc analysis showing that CRP levels one day after surgery were significantly greater in the diminished group than in the intact and damaged groups (P = 0.012 and 0.023, respectively). AP laxity in 30° of knee flexion was observed between the three groups (5.4 (2.3), 5.8 (2.5), and 7.1 (2.8) mm, respectively; P = 0.039), with post hoc analysis showing that AP laxity in 30° of knee flexion was significantly greater in the diminished group than in the intact group (P = 0.038). Knee ROM showed no significant differences. CONCLUSION: Intraoperative ACL diminishment was associated with higher CRP one day after surgery and midrange AP laxity one year after surgery.

Gait kinematics and knee stability 10-years following posterior-stabilised total knee arthroplasty comparable to healthy adults >55.

PURPOSE: The purpose of this study was to compare the long-term objective biomechanical and functional parameters of a high-flexion total knee arthroplasty (TKA) design against healthy older adults to determine whether knee biomechanics are comparable in both populations. METHODS: One cohort of patients with a primary TKA, and a cohort of healthy adults over 55 years old with no musculoskeletal deficits or arthritis participated. Bilateral knee range of motion (RoM) was assessed with a goniometer, and gait patterns were analysed with a three-dimensional-motion capture system. An arthrometer quantified the anterior-posterior laxity of each knee. Statistical analyses were performed in SPSS software (α = 0.05). RESULTS: Twenty-three knees were replaced in 20 patients. At 9.8 ± 3.1 years postoperatively, patients' knees had a statistically significantly poorer RoM than healthy controls' knees (n = 23) due to limited flexion; p < 0.0001. Patients also failed to achieve the same degree of knee flexion as controls during downhill gait. No kinematic differences were observed during mid-flexion in level nor downhill gait; a state that has been associated with instability (p = 0.614; not significant [n.s]). There were no differences between groups in knee laxity (n.s). CONCLUSION: Patients in this study had similar gait patterns to healthy older adults during mid-flexion and were no more likely than the healthy controls to exhibit anterior-posterior translation of the knee > 7 mm; a known risk factor of instability. However, the knee flexion range was poorer. This likely led to bilateral pathological knee flexion patterns during downhill gait. LEVEL OF EVIDENCE: Level III.

A three-headed plantaris muscle fused with Kaplan fibers: potential clinical significance.

The plantaris is a short, small muscle that usually originates at the popliteal surface of the femur and has a long, thin tendon that typically inserts into the calcaneal tuberosity. Its role and degree of development have been objects of debate for years. Some authors consider it a vestigial muscle while others believe it is a process of its development. The clinical significance of plantaris muscle is usually related to its morphological variation, which is common and well described in the literature. These variations are often a risk factor for many ailments and disorders. We would like to present another, very rare case of three-headed plantaris muscle (fused with distal Kaplan fibers), and consider what clinical implications it may have.

The effects of alteration in muscle activation on the iliotibial band during an exhaustive run.

PURPOSE: Long exhausted running causes pain at the lateral femoral epicondyle for some runners. The pain has been revealed to be related to the behavior of the iliotibial band (ITB) during running. The purpose of this study is to examine the effects of in-series musculature on the behavior of the ITB in healthy participants during an exhaustive run. METHODS: Twenty-five healthy participants (15 males, 10 females) were recruited in the current study. All participants performed a 30-minute exhaustive run at a self-selected speed with laboratory-provided footwear. Muscle activities of ITB-related muscles including tensor fascia latae (TFL), gluteus maximus (Gmax), gluteus medius (Gmed), biceps femoris (BF), and vastus lateralis (VL) were recorded using surface electromyography (EMG). RESULTS: Maximum amplitudes at the initial stage (the first minute), the mid stage (the 15-minute), and the end stage (the 30-minute) were compared during the exhaustive running. Significant decreases (p < 0.05) were observed in the maximum amplitudes of the TFL, Gmax, Gmed, and BF at the mid (decreased by ~ 15%) and end (decreased by ~ 30%) stages compared to the initial stage. The onset and the offset remained unaltered during the running (p ≥ 0.05). CONCLUSION: The behavior of the healthy ITB might be altered due to the activities of the in-series musculature. Excessive compression forces might be applied to the lateral femoral epicondyle from the ITB to provide stability for the knee joint during an exhaustive run. The findings could provide a basic understanding of the behavior of healthy ITB.

Posterior tibial plateau impaction fractures are not associated with increased knee instability: a quantitative pivot shift analysis.

PURPOSE: This study aimed to evaluate posterolateral tibial plateau impaction fractures and how they contribute to rotatory knee laxity using quantitative pivot shift analysis. It was hypothesised that neither the presence of nor the degree of involvement of the plateau would affect rotatory knee laxity in the ACL-deficient knee. METHODS: A retrospective review of prospectively collected data on 284 patients with complete anterior cruciate ligament (ACL) injuries was conducted. Posterolateral tibial plateau impaction fractures were identified on preoperative MRI. The patients were divided into two cohorts: "fractures" or "no fractures". The cohort with fractures was further categorised based on fracture morphology: "extra-articular", "articular-impaction", or "displaced-articular fragment". All data were collected during examination under anaesthesia performed immediately prior to ACL reconstruction. This included a standard pivot shift test graded by the examiner and quantitative data including anterior tibial translation (mm) via Rolimeter, quantitative pivot shift (QPS) examination (mm) via PIVOT tablet technology, and acceleration (m/sec2) during the pivot shift test via accelerometer. Quantitative examinations were compared with the contralateral knee. RESULTS: There were 112 patients with posterolateral tibial plateau impaction fractures (112/284, 39%). Of these, 71/112 (63%) were "extra-articular", 28/112 (25%) "articular-impaction", and 13/112 (12%) "displaced-articular". Regarding the two groups with or without fractures, there was no difference in subjective pivot shift (2 ± 0 vs 2 ± 0, respectively, n.s.), QPS (2.4 ± 1.6 mm vs 2.7 ± 2.2 mm, respectively, n.s.), anterior tibial translation measurements (6 ± 3 mm vs 5 ± 3 mm, respectively, n.s.), or acceleration of the knee during the pivot (1.7 ± 2.3 m/s2 vs 1.8 ± 3.1 m/s2, respectively, n.s.). When the fractures were further subdivided, subgroup analysis revealed no significant differences noted in any of the measured examinations between the fracture subtypes. CONCLUSION: This study showed that the posterolateral tibial plateau impaction fractures are commonly encountered in the setting of ACL tears; however, contrary to previous reports, they do not significantly increase rotatory knee laxity. This suggests that this type of concomitant injury may not need to be addressed at the time of ACL reconstruction. LEVEL OF EVIDENCE: Level III.

Re-rupture rate and the post-surgical meniscal injury after anterior cruciate ligament reconstruction with the Press-Fit-Hybrid®-technique in comparison to the interference screw technique: a retrospective analysis of 200 patients with at least 3 years follow-up.

BACKGROUND: There is currently no consensus regarding the preferred surgical procedure for the reconstruction of anterior cruciate ligament (ACL). The interference screw technique is widely used, but has been associated with a risk of graft damage. The Press-Fit-Hybrid®-technique is one of the alternatives for biological ACL-reconstruction with minimal implant requirements. The hypothesis of this retrospective analysis is, that the Press-Fit-Hybrid®-technique leads to better results with respect to re-rupture rate and secondary meniscal lesion than the interference-screw-technique. METHODS: To compare the re-rupture rate of the interference-screw-technique (IF) used until 2015 with the currently used Press-Fit-Hybrid®-technique (PFH), the last 100 patients of the IF-group and the first 100 patients of the PFH-group were retrospectively analyzed. Primary outcomes were re-rupture rate, complications and secondary meniscal injury. Additionally, laxity, Lachman and Pivot-shift and range of motion were evaluated. RESULTS: A mean follow-up of 4.2 and 5.3 years revealed 4% and 9% re-rupture rates and 1% and 2% complication rates in the PFH- and IF-group, respectively. In the PFH-group there were no re-ruptures in patients older than 23 years. Secondary meniscal injury post-surgery was 6% and 9% for the PFH and IF-group, respectively. Knee stability was similar in both groups. Range of motion was significantly better in the PFH-group, with 136° of flexion, 6 months after surgery. CONCLUSION: For ACL-reconstruction the Press-Fit-Hybrid®-technique is an alternative new method. Low level of secondary meniscal lesions after surgery and high stability, is known to prevent later arthrosis of the knee. The encouraging observed trend of the reduction of the re-rupture rate in revision surgery and in young patients using the Press-Fit-Hybrid®-technique in comparison to the interference-screw-technique must be confirmed with further studies. LEVEL OF EVIDENCE: Therapeutic Level III, retrospective cohort study.

Could anterior closed-wedge high tibial osteotomy be a viable option in patients with high posterior tibial slope who undergo anterior cruciate ligament reconstruction? A systematic review and meta-analysis.

PURPOSE: This study aims to examine the clinical and radiological outcomes of patients who underwent ACL reconstruction (ACLR) combined with anterior closed-wedge high tibial osteotomy (ACW-HTO) for posterior tibial slope (PTS) reduction to investigate the efficacy of this procedure in improving anterior knee stability and preventing graft failure in primary and revision ACLR. METHODS: A literature search was conducted in six databases (PubMed, Embase, Medline, Web of Science, Cochrane, and Scopus). The study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The initial screening identified 1246 studies. Each eligible clinical article was screened according to the Oxford Centre for Evidence-Based Medicine 2011 levels of evidence (LoE), excluding clinical studies of LoE V. Quality assessment of the articles was performed using the ROBINS-I methodological evaluation. This systematic review and meta-analysis was registered on the International Prospective Register of Systematic Reviews (PROSPERO). For the outcomes that were possible to perform a meta-analysis, a p < 0.05 was considered statistically significant. RESULTS: Five clinical studies were included in the final analysis. A total of 110 patients were examined. Pre- and post-operative clinical and objective tests that assess anteroposterior knee stability, PTS, clinical scores, and data on surgical characteristics, complications, return to sports activity, and graft failure after ACLR were investigated. A meta-analysis was conducted using R software, version 4.1.3 (2022, R Core Team), for Lysholm score and PTS outcomes. A statistically significant improvement for both these clinical and radiological outcomes (p < 0.05) after the ACW-HTO surgical procedure was found. CONCLUSION: ACLR combined with ACW-HTO restores knee stability and function with satisfactory clinical and radiological outcomes in patients with an anterior cruciate ligament injury associated with a high PTS and seems to have a protective effect from further ruptures on the reconstructed ACL. LEVEL OF EVIDENCE: Level IV.

Effect of iliotibial band and gastrocnemius activation on knee kinematics.

BACKGROUND: This paper aimed to evaluate the effects of iliotibial band (ITB) activation and gastrocnemius activation on knee kinematics and stability. A quantitative analysis needs to determine the effect of ITB and gastrocnemius activation in each of the six degrees of freedom of the knee joint. METHODS: Four cadaveric knee specimens were tested during squat motions with physiological loads. The quadriceps and hamstring muscles were activated in each situation. The ITB was intermittently activated using an actuator and a cable pulley system. The gastrocnemius was activated anatomically as part of the triceps surae complex together with the soleus and the plantaris muscle. During the squat motion, the Achilles tendon has increased tension which induced muscle activation in the calf muscles thus creating the activated situation. RESULTS: Introduction of the ITB resulted in a reduced laxity width during extension and an external tibial rotation (2.4°). The femur shifted less posterior in the lateral compartment when the ITB was activated. Activation of gastrocnemius as part of the calf muscles led to an increased laxity width. CONCLUSIONS: Knee stability and knee joint kinematics are affected significantly by the activation of the ITB and the gastrocnemius as part of the triceps surae complex. This points to the importance of muscles and stabilizing tissue structures such as the ITB in the evaluation of knee joint kinematics both in vitro and in vivo.

The effects of blood flow restriction on the quadriceps femoris and knee stability after anterior cruciate ligament reconstruction / 中华物理医学与康复杂志

Objective:To explore the effect of blood flow restriction training on the quadriceps femoris and on knee stability after anterior cruciate ligament reconstruction.Methods:Forty patients recovering from anterior cruciate ligament reconstruction were randomly divided into an experimental group and a control group, each of 20. In addition to routine rehabilitation training, the control group was given routine knee flexion and extension strength training, while the experimental group trained for an additional 20 minutes doing knee flexion and extension resistance training with the blood pressure in their groins at 70% of their individual arterial occlusive pressure. (The mean pressure was (123±11.23)mmHg). The training lasted 8 weeks, three times a week. Knee function and hamstring and quadriceps peak torque were assessed before and after the intervention using a Lysholm scale and Humac Norm isokinetic muscle strength tests.Results:There were no significant differences between the two groups in any of the measurements before the training. After the intervention, all of the measurements had improved significantly in both groups, with the average Lysholm score, H/Q% and peak torque of the experimental group significantly better than the control group′s averages.Conclusions:Blood flow restriction training can improve the effectiveness of quadriceps femoris strength, knee stability and knee function training after anterior cruciate ligament reconstruction.

A clinical practice review of therapeutic movement-based anterior cruciate ligament reconstruction return to sports bridge program: the biological, biomechanical and behavioral rationale.

This clinical practice review describes the biological, biomechanical and behavioral rationale behind a return to sport bridge program used predominantly with non-elite, youth and adolescent high school and college athletes following anterior cruciate ligament (ACL) reconstruction. Post-physiotherapy, this program has produced outcomes that meet or exceed previous reports. With consideration for athletic identity and the Specific Adaptations to Imposed Demands (SAID) principle, the early program focus was on restoring non-impaired bilateral lower extremity joint mobility and bi-articular musculotendinous extensibility. Building on this foundation, movement training education, fundamental bilateral lower extremity strength and power, and motor learning was emphasized with use of external focus cues and ecological dynamics-social cognition considerations. Plyometric and agility tasks were integrated to enhance fast twitch muscle fiber recruitment, anaerobic metabolic energy system function, and fatigue resistance. The ultimate goal was to achieve the lower extremity neuromuscular control and activation responsiveness needed for bilateral dynamic knee joint stability. The rationale and conceptual basis of selected movement tasks and general philosophy of care concepts are described and discussed in detail. Based on the previously reported efficacy of this movement-based therapeutic exercise program we recommend that supplemental programs such as this become standard practice following release from post-surgical physiotherapy and before return to sports decision-making.

Stability of the knee after posterior cruciate ligament reconstruction using peroneus longus tendon graft with three femoral insertion sites. A cadaveric study.

Introduction: Many kinds of grafts were used for single-bundle reconstruction of the posterior cruciate ligament (PCL). Recently, the peroneus longus tendon (PLT) was used in some clinical reports. This study aimed to test the best position of the femoral insertion in the case of using PLT for PCL reconstruction. Methods: Seventeen fresh frozen cadaveric knees were randomized into three groups. Group AL (6 knees): the femoral insertion in PCL reconstruction was at the footprint center of the anterolateral bundle (ALB). Group PM (5 knees): at the footprint center of the posteromedial bundle (PMB). And group MC (6 knees) was at the midpoint of the center of the anterolateral bundle and posteromedial bundle. The PCL of all knees was cut and a PCL reconstruction procedure was performed with autologous peroneus longus tendon (PLT). The stability of each knee was tested in three conditions: PCL was intact, PCL was resected, and PCL was reconstructed. The KT-1000 machine was used to measure the maximum posterior displacement of the tibia under force with the knees at 0, 30, 60, 90, and 120 degrees of flexion. Results: Average posterior displacement of the tibia under force for intact PCL of group AL was 1.6 mm, group MC was 1.2 mm, and group PM was 1.3 mm. After PCL was resected, the knee laxity was increased remarkably: posterior displacement of the tibia of group AL was 8.9 mm, group MC was 9.4 mm, and group PM was 13.6 mm. After PCL was reconstructed, group AL was 1.5 mm, group MC was 2.0 mm, and group PM was 5.6 mm. The results showed that after PCL reconstruction the group AL and group MC give better stability to the knee (p < 0.05, except knee at 120 degrees of flexion). Group AL got more stability than group MC, but the difference was not significant (p ≥ 0.164). Conclusion: In a single-bundle reconstruction of the PCL with the graft PLT, the femoral insertion at the footprint center of the ALB and the midpoint of the center of the ALB and PMB showed better stability than that at PMB.

Bilateral changes in knee joint laxity during the first year after non-surgically treated anterior cruciate ligament injury.

OBJECTIVES: Analyse changes in knee laxity between 3, 6, 12 and 24 months after non-surgically treated ACL injury and to analyse associations between knee laxity and knee function, self-reported knee stability, ACL-Return to Sport after Injury (ACL-RSI), fear and confidence at different timepoints during recovery. DESIGN: Prospective cohort study. PARTICIPANTS: 125 patients (67 males, mean age 25.0 ± 7.0 years) with acute ACL injury. MAIN OUTCOME: Laxity was measured using KT-1000 arthrometer. Self-reported knee function was assessed using the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF). Confidence and fear were assessed with questions from the ACL-RSI scale. Subjectively knee stability was assessed using SANE. RESULTS: Knee laxity increased bilaterally from 3 to 12 months, and in the non-involved knee from 3 to 24 months (p˂0.05), although mean change was below 1 mm. Side-to-side difference in knee laxity was correlated with IKDC-SKF (r = -0.283) and knee stability in rehabilitation/sport activities (r = -0.315) at 6 months, but not with confidence/fear. CONCLUSION: Knee laxity increased bilaterally during the first year after non-surgically treated ACL injury, though, the mean change in knee laxity was below 1 mm and the clinical significance is unknown. Knee laxity was weakly associated with knee function and perceived knee stability. LEVEL OF EVIDENCE: Level II TRIAL REGISTRATION: NCT02931084.

Graft Diameter Should Reflect the Size of the Native Anterior Cruciate Ligament (ACL) to Improve the Outcome of ACL Reconstruction: A Finite Element Analysis.

The size of the anterior cruciate ligament (ACL) often varies between individuals, but such variation is not typically considered during ACL reconstruction (ACLR). This study aimed to explore how the size of the ACL affects the selection of a suitable graft diameter. A finite element model of a human knee was implanted with intact ACLs of different dimensions (0.95, 1 and 1.05 times the size of the original ACL) and with grafts of different diameters, to simulate ACLR (diameter 7.5-12 mm in 0.5 mm increments). The knee models were flexed to 30° and loaded with an anterior tibial load of 103 N, internal tibial moment of 7.5 Nm, and valgus tibial moment of 6.9 Nm. Knee kinematics (anterior tibial translation (ATT), internal tibial rotation (ITR) and valgus tibial rotation (VTR)) and ligament forces were recorded and compared among the different groups. The results showed that, compared with the intact knee, a graft diameter of 7.5 mm was found to increase the ATT and VTR, but reduce the graft force. Increasing the graft diameter reduced knee laxity and increased the graft force. A 10% increase in the size of the ACL corresponded to a 3 mm larger graft diameter required to restore knee stability and graft force after ACLR. It was concluded that the graft diameter should be selected according to the dimensions of the native ACL, for better restoration of knee functionality. This study may help to improve the clinical treatment of ACL ruptures.

The efficacy and medium-term outcomes of ligament advanced reinforcement system compared with auto-grafts in anterior cruciate ligament reconstruction: At least 2 years follow-up.

Background: Graft choice is an important step in the pre-operative plan of anterior cruciate ligament reconstruction (ACLR). The four-strand hamstring tendon (4SHT) is the most widely used auto-graft, while the Ligament Advanced Reinforcement System (LARS) is the newest typical biomaterial for ACLR. The physical activity level (PAL) before injury can affect the efficacy and outcomes of ACLR. This study aims to compare the efficacy and functional outcomes between ACLR using LARS and 4SHT in patients different PALs. Methods: This was a prospective paired case-control study. ACL rupture patients included from 1 January 2017 to 31 December 2019 were subsequently divided into the high and plain PAL groups, according to their baseline PAL before injury. Clinical assessments included: Lachman test, pivot shift test, ligament laxity, Lysholm and International Knee Documentation Committee (IKDC) scores, and rate of returning to sports. The minimum follow-up was 2 years (y). Results: A total of 58 patients had accomplished the 2 y follow-up (missing rate: 6.5%). In the high PAL group (n = 22), the positive rate of A-P laxity of the LARS subgroup was lower than the 4SHG subgroup (p = 0.138), while the Lysholm score (p = 0.002), IKDC score (p = 0.043), and rate of returning to sports (p = 0.010) of the LARS were higher than the 4SHG at 1 year follow-up; the positive rates of A-P laxity (p = 0.009) and pivot test (p = 0.027) were lower in the LARS than the 4SHG at 2 y follow-up. In the plain PAL group (n = 36), the positive rate of A-P laxity in the LARS subgroup was lower than the 4SHG at 1 year follow-up (p = 0.017); the positive rates of A-P laxity (p = 0.001), Lachman (p = 0.034), and pivot tests (p = 0.034) in the LARS were also lower than the 4SHG at 2 y follow-up, but the IKDC score (p = 0.038) and rate of returning to sports (p = 0.019) in the 4SHG were higher than the LARS. Conclusion: In patients with high PAL, LARS can acquire better knee stability, sooner functional recovery, and returning to sports than 4SHG, while in patients without high PAL, 4SHG acquires better functional outcomes and a higher rate of returning to sports.

Knee wobbling during the single-leg-squat-and-hold test reflects dynamic knee instability in patients with anterior cruciate ligament injury.

We propose using the single-leg squat-and-hold (SLSH) task with kinematic analysis to objectively measure dynamic knee stability after anterior cruciate ligament (ACL) injury. There are three objectives of this study: to compare the knee kinematics of ACL-deficient patients and healthy controls by capturing knee wobbling during the SLSH task, to detect kinematic changes after ACL reconstruction, and to correlate the kinematic variables with self-reported knee function. Twenty-five ACL-deficient participants and 18 healthy matched participants were recruited. The knee kinematics involving both the magnitudes and frequency of motion fluctuation was captured during SLSH by 3D motion analysis system (Vicon). Compared to the limbs of the control participants, the ACL involved limbs exhibited a greater range of flexion-extension (4.33 ± 1.96 vs. 2.73 ± 1.15; p = 0.005) and varus-valgus (2.52 ± 0.99 vs. 1.36 ± 0.42; p < 0.001). It also inhibited higher frequency of flexion-extension (4.87 ± 2.55 vs. 2.68 ± 1.23; p = 0.003) and varus-valgus (3.83 ± 2.59 vs. 1.42 ± 0.55; p < 0.001). The range of flexion-extension (4.50 ± 2.24 vs. 2.90 ± 1.01; p = 0.018), frequency of flexion-extension (4.58 ± 2.53 vs. 3.05 ± 1.80; p = 0.038) and varus-valgus (3.46 ± 2.11 vs. 1.80 ± 1.23; p = 0.022) was reduced after ACL reconstruction. Increased frequency of knee varus-valgus was correlated with lower IKDC score (r = -0.328; p = 0.034). Knee wobbling was more prominent in ACL-deficient patients, which was associated with poor knee function. SLSH task with kinematic analysis appears to be a potential assessment method for monitoring dynamic knee stability after ACL injury.

The Association between Multidirectional Speed Performance, Dynamic Balance and Chronological Age in Young Soccer Players.

The ability to maintain a stable single-leg balance stance during a fast change of direction movement is a fundamental aspect both for improving sport-specific skills and for prevention strategies. The aim of this cross-sectional study was to investigate the associations between multidirectional speed performance (MDS), dynamic balance performance (DBP), and chronological age in young and uninjured soccer players. In addition, it was examined whether chronological age and balance can predict variance in speed performance. One-hundred forty-six young male soccer players (age range 11-19) performed the y-balance test (YBT) and the lower extremity functional test (LEFT). Descriptive statistics, Pearson correlation, and multiple regression analysis were executed. The analyses were carried out on the further variables: for the DBP, the YBT composite score % (CS dominant leg/CS non-dominant leg) and limb symmetry index % (LSI) were used; for the MDS, the LEFT time in seconds (s) was used. Findings revealed LEFT scores to have a significant association with chronological age (p = 0.000), CS dominant (p = 0.019) and LSI (p = 0.044) of the YBT. In addition, CS dominant and chronological age explained the variance of the LEFT by 44%, regardless of LSI. To conclude, MDS revealed a strong association with DBP of the dominant side but a small association with LSI. In addition, a small association was found between quick LEFT times and older players. Finally, MDS variance can be predicted from DBP of the dominant side and chronological age in young soccer players. The tests used in this study could be useful screening tools for the detection of performance deficits, the implementation of prevention training programs, and the optimization of selection strategies in soccer academies.

Can tibia-first total knee arthroplasty using computer-assisted system improve anterior and posterior knee stability?

BACKGROUND: Total knee arthroplasty (TKA) is a widely performed procedure to alleviate pain and restore function of patients with end-stage knee osteoarthritis. OBJECTIVE: The study aim was to determine if tibia-first (TF) total knee arthroplasty (TKA) using a novel computer-assisted surgery (CAS) system can yield better anterior and posterior (AP) knee stability. METHODS: Patients with knee osteoarthritis with obvious varus knee who met the indication for and underwent TKA from May 2019 to November 2020 were included. Forty-one measured resection (MR)-TKAs and 32 TF-TKAs were compared. The varus-valgus ligament balance and joint tension at a joint center-gap setting equal to the tibial-baseplate thickness were measured, and appropriate polyethylene inserts with 0∘, 30∘, 45∘, 60∘, 90∘, and 120∘ of knee flexion were placed. A Kneelax 3 arthrometer was used to measure knee AP laxity in the postoperative anesthetized patients with 30∘ and 90∘ of knee flexion. RESULTS: The horizontal gap balance was significantly closer in the TF-TKA group than the MR-TKA group for 0∘, 30∘, 45∘, and 60∘ of knee flexion. In contrast, no significant differences were observed for 90∘ and 120∘ of knee flexion. No significant differences in joint-gap tensions among all knee-flexion angles were observed. Translation was significantly smaller in the TF-TKA group than the MR-TKA group for AP laxity with 30∘ of knee flexion (8.8 ± 2.9 mm vs. 10.7 ± 3.1 mm, P= 0.0079). In contrast, no significant AP laxity was observed with 90∘ of knee flexion (7.2 ± 2.8 mm vs. 7.2 ± 3.5 mm). CONCLUSION: TF-TKA using a novel CAS system provided better AP knee stability with close to horizontal gap balances.