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Introduction: Accurate assessment of anterior cruciate ligament (ACL) function is vital for guiding treatment. Nevertheless, the presence of tibial subluxation in the neutral position of a patient with an ACL injury may potentially introduce a confounding factor. This study aims to investigate whether tibial subluxation in the neutral position affects the diagnosis of anterior instability in patients with ACL injuries, potentially impacting the reliability and diagnostic accuracy of stress radiography. Methods: This study included 88 patients: 30 with acute complete ACL tears (acute group), 28 with chronic complete ACL tears (chronic group), and 30 patients who underwent knee arthroscopic surgery other than ACL reconstruction (control group). Side-to-side differences (SSD) in stress radiography were measured using the Telos load status and the SSD of the gap between the Telos load and unload statuses. Diagnostic accuracy of the two methods was assessed using areas under the receiver operating characteristic curves (AUCs). Results: The load SSD (5.92 ± 5.28 mm) was higher than the load-unload SSD (4.27 ± 5.99 mm) in the chronic group (P = 0.017). The load SSD demonstrated a significantly higher diagnostic value than that of the load-unload SSD in the combined group (AUC = 0.920 vs. 0.830; P = 0.012) and chronic group (AUC = 0.913 vs. 0.754; P = 0.002). After adjusting the symptoms for radiographic duration from 6 to 3 months in the chronic group, the load SSD exhibited a significantly higher diagnostic value (AUC = 0.902) than that of the load-unload SSD (AUC = 0.740; P < 0.001). Conclusion: The load SSD provides superior diagnostic accuracy compared to the load-unload SSD in ACL tear cases, where static anterior tibial subluxation may result in false negatives. Although load-unload SSD may have diagnostic value within the first 3 months post-injury, the load SSD method provides a reliable assessment of ACL function for patients beyond this timeframe. [ABSTRACT FROM AUTHOR]

Among the graft options for anterior cruciate ligament reconstruction (ACLR), hamstring autografts are widely regarded as the preferred choice for primary ACLR among orthopedic surgeons worldwide. However, concerns persist regarding postoperative knee flexor weakness. We aimed to compare knee extensor and flexor strengths between hamstring autograft and tibialis anterior allograft groups in ACLR patients, who were propensity score-matched based on baseline characteristics. A retrospective analysis included 58 matched pairs who underwent isokinetic strength tests at 6 and 12 months post operation. Isokinetic muscle strength tests found no significant difference in knee extensor and flexor strength at 6 months post operation between the hamstring autograft and tibial anterior allograft groups. At 12 months, the hamstring autograft group exhibited significantly greater knee flexor deficit (total work and average power) compared to the allograft group, despite no differences in extensor strength or patient-reported outcomes. This study highlights the impact of hamstring autograft harvesting on muscle strength and recovery following ACLR in short-term period. [ABSTRACT FROM AUTHOR]

Background: Consensus has not yet been reached regarding combined anterior cruciate ligament reconstruction (ALLR) with revisional anterior cruciate ligament reconstruction (RACLR). We aimed to compare the clinical outcomes between patients who underwent isolated RACLR and those who underwent RACLR combined with ALLR. Methods: Between June 2010 and June 2021, 49 patients who underwent RACLR were retrospectively reviewed over a 24-month follow-up. Patients were categorized into the isolated RACLR (n = 37, group 1) or combined ALLR group (n = 12, group 2). Clinical outcomes were evaluated with several patient-reported outcome measures (PROMs) and minimal clinically important differences (MCIDs) for each PROM. The side-to-side difference (SSD) of the anterior instability was measured. The pivot-shift test was performed. Results: Baseline characteristics showed no differences between the groups. PROMs showed no significant differences between the groups at the 2-year follow-up. Group 2 was superior to group 1 in the MCID achievement rate for Lysholm knee and International Knee Documentation Committee (IKDC) subjective scores at 24 months postoperatively. At the final follow-up, the proportion of IKDC grade A in SSD for anterior laxity was higher in group 2 than in group 1 (58.3% versus [vs.] 18.3%, p = 0.009), and the proportion of pivot-shift grade 0 was also higher in group 2 (66.7% vs. 27.0%, p = 0.013). The "near return to activity" rate was also higher in group 2 than in group 1 (83.3% vs. 45.9%, p = 0.043). Conclusions: Combining ALLR with RACLR in non-athletes results in a higher proportion of patients with less mechanical graft failure and satisfactory clinical outcomes. [ABSTRACT FROM AUTHOR]

Background: Unintended secondary changes in the posterior tibial slope (PTS) and tibial torsion angle (TTA) may occur after medial open-wedge high tibial osteotomy (MOWHTO). In surgical procedures using patient-specific instruments (PSIs), it is essential to reproduce the PTS and TTA that were planned in simulations. Purpose: To analyze the factors causing unintended sagittal and axial alignment changes after MOWHTO. Study Design: Case series; Level of evidence, 4. Methods: Overall, 63 patients (70 knees) who underwent MOWHTO using a PSI between June 2020 and June 2023 were retrospectively reviewed. Preoperative and postoperative computed tomography scans were 3-dimensionally reconstructed. Simulated osteotomy was performed so that the weightbearing line could pass through the target point. A PSI gapper was 3-dimensionally printed to fit the posteromedial corner of the osteotomy gap in the simulated HTO model. After MOWHTO using the PSI gapper, the actual postoperative model was compared with the preoperative or simulation model. This assessment included PTS, TTA, hinge axis, and osteotomy-related parameters. Cortical breakage around the lateral hinge was evaluated to assess stability. Results: The mean PTS and TTA did not change in the simulation. However, significant changes were observed in the actual postoperative PTS and TTA (change, –2.4°± 2.2° and −3.9°± 4.7°, respectively). The PTS was reduced, while the TTA decreased with internal rotation of the distal fragment. The difference in the axial hinge axis angle (AHA) between the simulation and actual surgery was the factor most correlated with the difference in the PTS (r = 0.625; P <.001). In regression analysis, the difference in the AHA was the only factor associated with the difference in the PTS (β = 0.558; P =.001), and there were no factors that showed any significant associations with the difference in the TTA. In subgroup analyses for the change in the TTA, the correction angle and anterior osteotomy angle were significantly higher in the more internal rotation group (P =.023 and P =.010, respectively). The TTA change was significantly higher in the unstable group with lateral cortical breakage (P =.018). The unstable group was more likely to show an internal rotation of ≥5° (odds ratio, 5.0; P =.007). Conclusion: The AHA was associated with a difference in the PTS between the simulation and actual surgery. The change in the TTA was caused by a combination of multiple factors, such as a large correction angle and anterior osteotomy angle, but mainly by instability of the lateral cortical hinge. [ABSTRACT FROM AUTHOR]

Purpose: To compare the outcomes of treating large cartilage defects in knee osteoarthritis using human allogeneic umbilical cord blood‐derived mesenchymal stem cell (hUCB‐MSC) implantation or arthroscopic microdrilling as a supplementary cartilage regenerative procedure combined with high tibial osteotomy (HTO). Methods: This 1‐year prospective comparative study included 25 patients with large, near full‐thickness cartilage defects (International Cartilage Repair Society grade ≥ IIIB) in the medial femoral condyles and varus malalignment. Defects were treated with hUCB‐MSC implantation or arthroscopic microdrilling combined with HTO. The primary outcomes were pain visual analogue scale and International Knee Documentation Committee subjective scores at 12, 24 and 48 weeks. Secondary outcomes included arthroscopic, histological and magnetic resonance imaging assessments at 1 year. Results: Fifteen and 10 patients were treated via hUCB‐MSC implantation and microdrilling, respectively. Baseline demographics, limb alignment and clinical outcomes did not significantly differ between the groups. Cartilage defects and total restored areas were significantly larger in the hUCB‐MSC group (7.2 ± 1.9 vs. 5.2 ± 2.1 cm2, p = 0.023; 4.5 ± 1.4 vs. 3.0 ± 1.6 cm2, p = 0.035). The proportion of moderate‐to‐strong positive type II collagen staining was significantly higher in the hUCB‐MSC group compared to that in the microdrilled group (93.3% vs. 60%, respectively). Rigidity upon probing resembled that of normal cartilage tissue more in the hUCB‐MSC group (86.7% vs. 50.0%, p = 0.075). Histological findings revealed a higher proportion of hyaline cartilage in the group with implanted hUCB‐MSC (p = 0.041). Conclusion: hUCB‐MSC implantation showed comparable clinical outcomes to those of microdrilling as supplementary cartilage procedures combined with HTO in the short term, despite the significantly larger cartilage defect in the hUCB‐MSC group. The repaired cartilage after hUCB‐MSC implantation showed greater hyaline‐type cartilage with rigidity than that after microdrilling. Level of Evidence: Level II, Prospective Comparative Cohort Study. [ABSTRACT FROM AUTHOR]

Purpose: To analyse whether valgus laxity and clinical outcomes differ depending on whether the superficial medial collateral ligament (sMCL) is released or transected during medial open‐wedge high tibial osteotomy (MOWHTO). Methods: Consecutive patients who underwent MOWHTO and subsequent radiological follow‐up for at least 2 years were retrospectively evaluated. The patients were divided into release and transection groups, according to the sMCL manipulation technique. Each patient was assessed for the following variables on valgus stress radiographs taken before surgery and at the 12‐ and 24‐month follow‐ups: the absolute value of valgus (ABV) and side‐to‐side difference (SSD) between the affected and normal sides. The differences between preoperative SSD and those at 12 and 24 months were respectively calculated and defined as delta SSD (ΔSSD). The Visual Analogue Scale, Lysholm knee, International Knee Documentation Committee subjective, and Knee Injury and Osteoarthritis Outcome scores were used to evaluate patient‐reported outcomes. Results: Eighty‐five patients were included in the study. Forty‐two patients (49.6%) underwent sMCL release, and the remaining 43 patients (50.4%) underwent sMCL transection. No significant differences were observed in the ABV and SSD of valgus laxity at the different time points between the two groups (n.s.). Furthermore, no significant differences were observed in the ΔSSD at the 12‐ and 24‐month follow‐ups between the two groups (n.s.). Significant improvement from preoperative values was observed in all patient‐reported outcomes (p < 0.001), with no significant differences between the two groups at any time point (n.s.). Conclusion: Significant improvements in clinical outcomes were observed, regardless of the technique used. Postoperative valgus laxity did not occur with either technique. The transection technique, which can be performed more simply and quickly, demonstrated similar clinical outcomes and valgus laxity to the release technique. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to analyse the factors associated with additional postoperative alignment changes after accurate bony correction by selecting only patients with well‐performed bony correction as planned and develop a method of incorporating significant factors into preoperative planning. Methods: Among 104 consecutive patients who underwent medial open wedge high tibial osteotomy (MOWHTO) between October 2019 and July 2022, 61 with well‐performed bony corrections were retrospectively reviewed. The major criterion for well‐performed bony correction was a difference of <1° between the simulated medial proximal tibial angle (MPTA) and the actual postoperative MPTA as measured in three dimensions. Radiographic parameters, such as the joint line convergence angle (JLCA) and joint line obliquity (JLO), were measured preoperatively and postoperatively, utilising standing and supine whole lower extremity anteroposterior, valgus and varus stress radiographs. Multiple linear regression analysis identified the factors affecting alignment changes, and a prediction model was developed. A method for applying this prediction model to preoperative planning was proposed. Results: Preoperative JLCA on standing (preJLCAstd), preoperative JLCA on 0° valgus stress radiograph (vgJLCA0), and preoperative JLO (preJLO) were significantly correlated with JLCA change (∆JLCA) (p < 0.001, p < 0.001, p = 0.006). The prediction model was estimated as ∆JLCA = 0.493 × (vgJLCA0) − 0.727 × (preJLCAstd) + 0.189 × (preJLO) − 1.587 in. (R = 0.815, modified R2 = 0.646, p < 0.001). The proposed method resulted in a reduced overcorrection rate (p = 0.003) and an improved proportion of acceptable alignments (p = 0.013). Conclusion: PreJLCAstd, vgJLCA0 and preJLO can be used to estimate ∆JLCA. PreJLO was recently identified as a significant factor associated with additional alignment changes. Utilising the proposed preoperative planning and a prediction model with these factors shows promise in calibrating postoperative alignment after MOWHTO. Level of Evidence: Level III, retrospective cohort study. [ABSTRACT FROM AUTHOR]

Medial meniscus posterior root tears (MMRTs), defined as tears or avulsions that occur within 1 cm of the tibial attachment of the medial meniscus posterior root, lead to biomechanically detrimental knee conditions by creating a functionally meniscal-deficient status. Given their biomechanical significance, MMRTs have recently been gaining increasing interest. Accordingly, numerous studies have been conducted on the anatomy, biomechanics, clinical features, diagnosis, and treatment of MMRTs, and extensive knowledge has been accumulated. Although a consensus has not yet been reached on several issues, such as surgical indications, surgical techniques, and rehabilitation protocols, this article aimed to comprehensively review the current knowledge on MMRTs and to introduce the author's treatment strategies. [ABSTRACT FROM AUTHOR]

The extent to which resection of unstable leaf should be performed in horizontal cleavage meniscus tear has not yet been elucidated. The purpose of this study was to compare the clinical outcomes of partial meniscectomy for horizontal cleavage tear of medial meniscus between complete resection of inferior leaf including the periphery up to the joint capsule and partial resection leaving stable peripheral torn meniscal tissue. A total of 126 patients who underwent partial meniscectomy for horizontal cleavage tear of medial meniscus were divided into two groups: group C (n = 34), treated with the complete resection of the inferior leaf; and group P (n = 92), treated with partial resection of the inferior leaf. The minimum follow-up duration was 3 years. Functional outcomes were evaluated using the Lysholm knee scoring scale, International Knee Documentation Committee (IKDC) subjective knee evaluation form, and knee injury and osteoarthritis outcome score (KOOS). Radiologic assessments were performed using the IKDC radiographic assessment scale and measurement of the height of the joint space in the medial compartment of the tibiofemoral joint. The functional outcomes including the Lysholm knee, IKDC subjective score, activities of daily living and sport and recreation subscale of KOOS were worse in group C than in group P (p < 0.001). The radiologic outcomes including postoperative IKDC radiographic scale (p = 0.003) and the postoperative joint space on the affected side (p < 0.001) were also worse in group C than in group P. In the horizontal cleavage tear of medial meniscus, complete resection of the inferior leaf including the periphery up to the joint capsule showed inferior clinical outcomes compared with partial resection leaving stable peripheral rim of torn meniscus at minimum 3-year follow-up. If the peripheral part of the inferior leaf is stable in horizontal cleavage tear of medial meniscus, partial resection of the inferior leaf preserving peripheral rim can be recommended. [ABSTRACT FROM AUTHOR]

Despite the clinical benefits over nonoperative treatment or meniscectomy, the clinical outcomes of surgical repair for medial meniscus posterior root tear (MMRT) remain suboptimal, which may be attributed to the insufficient restoration of meniscal hoop tension during surgery.To analyze the clinical outcomes of surgical repair of MMRT based on the appearance of the meniscal tension observed immediately after surgery.Cohort study; Level of evidence, 3Electronic medical records of patients who underwent arthroscopic transtibial pull-out repair of MMRT between 2010 and 2021 were retrospectively reviewed. Patients with at least a 2-year follow-up and whose overall meniscal status after the surgical repair could be evaluated via arthroscopic images or videos were eligible to be included. Patients were classified based on the presence of the curtain-cliff sign, potentially implying insufficient postoperative meniscal hoop tension (group 1, patients without the curtain-cliff sign; group 2, patients with the curtain-cliff sign). Regression analysis was performed to evaluate whether the curtain-cliff sign reflects postoperative meniscal extrusion. Subsequently, comparative analyses were conducted between the 2 groups regarding baseline demographic data, clinical scores, intraoperative data, and radiologic parameters.A total of 79 patients were included (group 1, 59 patients; group 2, 20 patients). Regression analysis revealed a significant association between the curtain-cliff sign and postoperative meniscal extrusion, suggesting its potential to reflect the postoperative meniscal tension. In the between-group comparisons, there were no differences in baseline demographic data, preoperative clinical scores, and preoperative radiologic variables. However, at the final follow-up, group 2 showed a significantly lower International Knee Documentation Committee subjective score compared with group 1 (group 1, 61.7 ± 14.4; group 2, 52.9 ± 12.5; P = .017), while no significant differences were found in the visual analog scale for pain score and Lysholm score. Additionally, group 2 exhibited significantly higher postoperative meniscal extrusion compared with group 1, which was measured at both the midpoint of the medial femoral condyle (group 1, 4.0 ± 1.1 mm; group 2, 5.1 ± 1.5 mm, P = .004) and the posterior border of the medial collateral ligament (group 1, 4.4 ± 1.2 mm; group 2, 5.7 ± 1.5 mm; P = .004), with more pronounced progression compared with the preoperative status at these sites. Consistently, the progression of both the osteoarthritis grade and the hip-knee-ankle angle compared with preoperatively was significantly greater in group 2.In patients in whom the restoration of meniscal tension appears insufficient immediately after surgical repair of MMRT, relatively poor clinical outcomes can be anticipated. The findings of this study suggest that efforts to reinforce meniscal tension may be required during surgical repair of MMRT in some cases, especially those showing the curtain-cliff sign. [ABSTRACT FROM AUTHOR]