Advances in meniscus tissue engineering: Towards bridging the gaps from bench to bedside.

Meniscus is vital for maintaining the anatomical and functional integrity of knee. Injuries to meniscus, commonly caused by trauma or degenerative processes, can result in knee joint dysfunction and secondary osteoarthritis, while current conservative and surgical interventions for meniscus injuries bear suboptimal outcomes. In the past decade, there has been a significant focus on advancing meniscus tissue engineering, encompassing isolated scaffold strategies, biological augmentation, physical stimulus, and meniscus organoids, to improve the prognosis of meniscus injuries. Despite noteworthy promising preclinical results, translational gaps and inconsistencies in the therapeutic efficiency between preclinical and clinical studies exist. This review comprehensively outlines the developments in meniscus tissue engineering over the past decade (Scheme 1). Reasons for the discordant results between preclinical and clinical trials, as well as potential strategies to expedite the translation of bench-to-bedside approaches are analyzed and discussed.

Non-invasive regional parameter identification of degenerated human meniscus.

Accurate identification of local changes in the biomechanical properties of the normal and degenerative meniscus is critical to better understand knee joint osteoarthritis onset and progression. Ex-vivo material characterization is typically performed on specimens obtained from different locations, compromising the tissue's structural integrity and thus altering its mechanical behavior. Therefore, the aim of this in-silico study was to establish a non-invasive method to determine the region-specific material properties of the degenerated human meniscus. In a previous experimental magnetic resonance imaging (MRI) study, the spatial displacement of the meniscus and its root attachments in mildly degenerated (n = 12) and severely degenerated (n = 12) cadaveric knee joints was determined under controlled subject-specific axial joint loading. To simulate the experimental response of the lateral and medial menisci, individual finite element models were created utilizing a transverse isotropic hyper-poroelastic constitutive material formulation. The superficial displacements were applied to the individual models to calculate the femoral reaction force in an inverse finite element analysis. During particle swarm optimization, the four most sensitive material parameters were varied to minimize the error between the femoral reaction force and the force applied in the MRI loading experiment. Individual global and regional parameter sets were identified. In addition to in-depth model verification, prediction errors were determined to quantify the reliability of the identified parameter sets. Both compressibility of the solid meniscus matrix (+141 %, p ≤ 0.04) and hydraulic permeability (+53 %, p ≤ 0.04) were significantly increased in the menisci of severely degenerated knees compared to mildly degenerated knees, irrespective of the meniscus region. By contrast, tensile and shear properties were unaffected by progressive knee joint degeneration. Overall, the optimization procedure resulted in reliable and robust parameter sets, as evidenced by mean prediction errors of <1 %. In conclusion, the proposed approach demonstrated high potential for application in clinical practice, where it might provide a non-invasive diagnostic tool for the early detection of osteoarthritic changes within the knee joint.

More knee reinjuries after ACL reconstruction compared to nonsurgical treatment of the ACL. A 2-year follow-up of the NACOX prospective cohort study.

PURPOSE: To describe knee reinjuries and surgeries within 2 years after an acute anterior cruciate ligament (ACL) injury, in patients treated with or without ACL reconstruction (ACLR). METHODS: Two years follow-up of 275 patients (52% females, mean age 25.2 [SD 7.0] years) about knee reinjuries and surgeries were analysed from the prospective NACOX cohort study, aiming to describe recovery after an acute ACL injury treated according to clinical routine. Knee reinjury was defined as increase or new symptoms due to new trauma. At 2 years after injury, 169 (61%) had undergone an ACLR. Results are presented with descriptive statistics and risk ratios (RR). RESULTS: Thirty-two patients sustained reinjuries within 2 years; 6 in the non-ACLR group, and 26 in the ACLR group (7 before and 19 after ACLR). Twelve patients in the ACLR group sustained a graft rupture and three did an ACL revision. Patients with non-ACLR, aged 21-25 years, had a 5.9-fold higher risk for reinjury than those aged 15-20 years (RR 5.9 [1.3-26.9]; p = 0.012). Twenty-four patients had surgery in the non-ACLR group and 36 patients in the ACLR group (excluding primary ACLR), where six were before ACLR and 30 were after ACLR. CONCLUSION: Twelve percent sustained a knee reinjury and 21% underwent knee surgery within 2 years after the index ACL injury. There was a higher reinjury incidence in the ACLR group, but no difference in incidence of surgeries. Thus, ACLR did not reduce the risk of traumatic reinjuries or surgeries, which is important for treatment decision considerations. LEVEL OF EVIDENCE: Level I.

Biomechanical comparison of the tensile strength of fixation implants used for pull-out repair of medial meniscus posterior root tear.

PURPOSE: Medial meniscus posterior root tears (MMPRT) pull-out repair aims to restore the meniscus' anatomical structure. Different implants are utilized for thread fixation in the pull-out repair technique for MMPRT. However, biomechanical evidence comparing the fixation strengths of these implants remains unavailable. This study investigated the tensile strength of three fixation implants in porcine knee models of MMPRT pull-out repair. METHODS: This study categorized 30 porcine MMPRT models undergoing pull-out repair into three groups (10 specimens each) based on the implant utilized for fixation, including double spike plate, metallic interference screw (IFS), and resorbable IFS fixed group. A tensile tester was used to track the suture wire threaded to the medial meniscus anterior root. The displacement length was recorded after 10 and 20 loading cycles (10-30 N, 100 mm/min cross-head speed). Each specimen was then stretched to failure (50 mm/min cross-head speed), failure modes were recorded, and structural properties (maximum load, linear stiffness, elongation at failure, and elongation at yield) were compared. Fisher's exact test and one-way analysis of variance were utilized to assess the differences. RESULTS: No significant differences in displacement length, upper yield load, maximum load, linear stiffness, elongation at yield, elongation at failure, and frequency of failure mode were observed between the three groups. CONCLUSION: All implants were comparable in terms of fixation strength. Thus, resorbable interference screws may be particularly useful in this technique and does not require implant removal surgery. LEVEL OF EVIDENCE: IV.

The residual laxity of medial collateral ligament after magic point pie crusting MCL released in arthroscopic management of medial meniscus.

Background: In order to do arthroscopic surgery on medial meniscus injuries, there must be enough joint space and good visibility for instrumentation. There is a possibility of iatrogenic cartilage damage if the medial joint space is reduced. Therefore, a medial collateral ligament (MCL) releasing procedure may be necessary for the majority of individuals with medial knee tightness. The MCL residual laxity after pie-crusting release during arthroscopic medial meniscus repair in medial knee tightness were studied in this study. Methods: Between July 2022 and June 2023, fourteen patients (4 male, 10 female) underwent medial meniscus surgery with pie-crusting release of the superficial MCL. Mean age was 50 ± 10 years (range, 35-63 years). Medial meniscal lesions were meniscus root tear in 10 cases (71.5 %), longitudinal tear in 2 (14.5 %), horizontal tear in 1 (7 %) and radial tear in 1 (7 %). Preoperatively, valgus stress radiographs were obtained. During surgery if arthroscopic exploration revealed medial joint space narrowing after applying valgus force with the knee in 20 degrees of flexion, pie-crusting MCL release was performed. At the 3-month follow-up, valgus stress radiographs were obtained. Residual MCL laxity was assessed by comparing preoperative and 3-month follow-up medial joint space width measurements. Result: At the 3-month follow-up, no significant increase in the medial joint space width on valgus stress radiograph was observed in comparison to the preoperative. The medial joint space width on valgus stress radiograph was 7.42 ± 1.16 mm preoperatively and 7.47 ± 1.15 mm at 3-month postoperatively (p value = 0.914). All patients had no intraoperative iatrogenic cartilage injury and no saphenous nerve injury after operation. Conclusions: The magic point pie-crusting MCL release is a reliable and useful procedure to arthroscopic surgery in patients with medial meniscal injury and medial knee tightness. Furthermore, percutaneous pie-crusting MCL release had no effect on residual valgus laxity at the last follow-up.

Anterior bone tunnel position increases meniscus migration in medial meniscus posterior root repair: A cadaveric study of suture length changes.

Purpose: This study investigated differences in the migration of meniscus sutured with pull-out sutures for treating medial meniscus posterior root tears (MMPRTs) according to the bone tunnel position, using cadaveric knees. Methods: Six knees of three donors fixed using Thiel's method were included in this study. The MMPRTs were created, and a single suture was performed at the torn meniscus using an arthroscopic procedure. The suture was pulled out through the tibial bone tunnel, and the meniscus displacement was measured as the change in length during 0-120° of knee flexion. Three types of bone tunnels (anatomical, anterior and posterior) were created for each knee, and the sutures were pulled out of each tunnel three times. After completing all measurements, the proximal tibia was extracted and micro-computed tomography was performed to evaluate the tunnel position. Results: A significantly smaller change in suture length was observed in the posterior group compared to the other two groups (anatomical group, 5.17 ± 1.8 mm; anterior group, 7.50 ± 3.2 mm; posterior group, 1.17 ± 1.0 mm; p > 0.01). In addition, a significant correlation between the anteroposterior tunnel position and suture length change was observed (r = -0.720; p = 0.001). Conclusions: When pull-out sutures were used to repair MMPRTs, the suture length change was approximately 5 mm during knee flexion and extension when the bone tunnel was located at the anatomical attachment site. This change was larger when the tunnel position was anterior, and smaller when the tunnel position was posterior. Level of Evidence: LEVEL Ⅲ case-control study.

Ultrasounds outperform magnetic resonance imaging in quantifying meniscal extrusion in patients with knee osteoarthritis.

Purpose: The aim of this study was to quantify meniscal extrusion through ultrasound (US) evaluation in supine and standing positions and to compare the results with those documented through magnetic resonance (MR) imaging in patients affected by knee osteoarthritis (OA). Methods: Sixty patients (38 men, 22 women, mean age 60.8 ± 9.7 years) with knee OA were enrolled and underwent a 1.5 T MR evaluation and an US examination of the symptomatic OA knee for the evaluation of the medial and lateral meniscus extrusion both in the supine clinostatic position (clino-US) with the knee fully extended and in the standing weight-bearing orthostatic position (ortho-US). For the three imaging evaluations (MR, clino-US and ortho-US), both semi-quantitative and quantitative measurements were performed. Results: The quantitative analysis documented higher values of medial meniscal extrusion at the ortho-US evaluation (5.2 ± 2.3 mm) compared to MR (4.2 ± 2.2, p < 0.0005) and clino-US (4.5 ± 2.3, p < 0.0005) and of the lateral meniscus at the ortho-US evaluation (4.3 ± 1.8) compared to MR (3.3 ± 1.6, p < 0.0005) and clino-US (3.8 ± 1.6, p < 0.0005). The semi-quantitative analysis confirmed the same trend for both menisci. Higher extrusion values were documented in women and more advanced OA, as well as in older patients with higher body mass index, the latter being underestimated the most by the MR approach. Conclusion: US outperforms MR imaging in quantifying meniscal extrusion in patients with knee OA. Moreover, the highest values of meniscal extrusion have been documented using US in standing position compared to the supine position, underlining the importance of the weight-bearing assessment of meniscal extrusion in knee OA patients. Level of Evidence: II.

Approaching ramp lesions from the different world of posterior knee compartment: A review of evidence with a proposal of a new classification and treatment.

Ramp lesions (RLs) are peripheral lesions that occur in the posterior part of the medial meniscus or where it attaches to the joint capsule. The classification of the medial meniscus RLs has been the focus of numerous studies and publications. This review provides an overview of RL's current classification and treatment options in anterior cruciate ligament deficient knees. The study also aims to present a more practical classification system for RLs to assist in treatment decision-making. For the first time, we also presented a new surgical treatment for incomplete inferior and double-complete RL based on the posterior knee arthroscopy that provides direct access to the posterior meniscal borders, enabling effective treatment and stronger biomechanical repair. Level of Evidence: Level V.

The Incidence of Injuries to Ramp Semimembranosus Complex Lesions After ACL Injury: An MRI Study.

Background: Medial meniscal ramp lesions have recently been an area of interest because of their recognized prevalence in association with anterior cruciate ligament (ACL) ruptures. Anatomically, the medial meniscal ramp is composed of the meniscocapsular ligament in continuity with the semimembranosus muscle and the meniscotibial ligament. Diagnosis of ramp semimembranosus complex (RSC) injuries remains challenging, and their prevalence is likely to be underestimated in comparison with ramp lesions. Purpose: To determine the prevalence of RSC lesions after a complete ACL rupture. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A retrospective database analysis was performed. The cohort consisted of the first 100 patients with complete ACL rupture confirmed by magnetic resonance imaging (MRI) who underwent knee arthroscopy for ACL reconstruction in 2019. The semimembranosus lesions were identified using MRI by 2 independent radiologists specializing in musculoskeletal imaging. The ramp lesions were initially diagnosed using MRI and then confirmed during arthroscopy by an experienced knee surgeon. The magnitude of rotatory instability was recorded using the pivot-shift test. A multivariate analysis was used to determine the lesions associated with the semimembranosus complex. Results: Of 100 patients, 53 showed lesions of the RSC; among them, 30 ramp lesions were confirmed after arthroscopic evaluation, and 40 semimembranosus lesions (23 without ramp lesion and 17 with ramp lesion) were found using MRI. A positive pivot shift was present in 57% of patients with combined RSC injury (P = .04) compared with 36% in patients without an RSC lesion. Conclusion: Lesions of the RSC were found in more than half of ACL ruptures in this retrospective cohort. Rotational instability could be associated with combined ACL and RSC injury.

Fast rehabilitation does not worsen clinical, radiological, and arthroscopic outcomes after medial meniscus posterior root repair: A retrospective comparative study.

Background/Objective: The main surgical treatment for medial meniscus posterior root tear (MMPRT) has shifted from meniscectomy to meniscus repair; however, there is no clear consensus regarding the optimal postoperative management strategy after MMPRT repair. This study aimed to perform a comparative analysis of patients who received conventional rehabilitation or fast rehabilitation following MMPRT repair. Methods: The current retrospective cohort study compared clinical, radiological, and arthroscopic outcomes after conventional rehabilitation (group A, January 2020 to April 2020, 24 patients) with those after fast rehabilitation (group B, May 2020 to August 2020, 24 patients) in patients who underwent pullout repair for MMPRT. Partial weight-bearing and range of motion exercises were allowed 2 weeks postoperatively in group A and 1 week postoperatively in group B. In patients with an average weight of approximately 60 kg, full weight bearing was allowed 4 weeks postoperatively in group A and 3 weeks postoperatively in group B. Results: At 12 months postoperatively, the clinical scores, including International Knee Documentation Committee and Japanese Knee Injury and Osteoarthritis Outcome Score, significantly improved in both groups (p < 0.01). Although meniscus healing was achieved in both groups, medial meniscus extrusion significantly progressed by 0.9 mm in group A and 0.8 mm in group B (p < 0.01, compared with preoperative extrusion). There were no significant differences in clinical scores, arthroscopic meniscal healing status, or medial meniscus extrusion progression on magnetic resonance images between the groups. Conclusion: A fast rehabilitation protocol can be safely implemented without compromising patient outcomes after pullout repair for MMPRT.

Evaluation of healing after arthroscopic repair of lateral meniscal tears around the popliteal hiatus.

BACKGROUND: The popliteal hiatus stabilizes the lateral meniscus (LM). Variable failure rates for LM repairs have been reported in knees with lateral meniscal tears (LMTs), which may be attributable to low vascularity around the popliteal hiatus. An effective repair method is essential to enhance the biological healing and stability of LMTs around the popliteal hiatus. HYPOTHESIS: Arthroscopic repair of LMTs, including the popliteus tendon around the popliteal hiatus, is expected to produce a low reoperation rate and effective treatment, both clinically and radiographically. MATERIAL AND METHODS: From June 2011 to August 2020, 93 patients (mean age 27.9 ± 13.5 years) who underwent arthroscopic repair of LMTs including the popliteus tendon around the popliteal hiatus were enrolled. Patients with LMTs were divided into three groups: isolated LMTs, discoid LMTs, and LMTs with ACL injury. Patients had a minimum clinical follow-up of 2 years (mean 37.9 ± 19.3 months) and Tegner activity, Lysholm knee, and Hospital for Special Surgery (HSS) scores were evaluated for all patients. The widths of the popliteal hiatus and LM extrusion were measured on the sagittal and coronal planes using preoperative and postoperative magnetic resonance imaging (MRI). RESULTS: The Tegner activity (2.6 ± 1.2-4.5 ± 1.3), Lysholm (67.9 ± 14.2-88.1 ± 6.4), and HSS scores (79.8 ± 11.5-93.7 ± 5.1) were significantly improved in all knees (p < 0.001). The width of the popliteal hiatus measured on MRI was significantly decreased, when comparing the preoperative and postoperative MRI for all knees (sagittal plane, 2.9 ± 1.4-1.5 ± 0.5 mm; coronal plane, 3.8 ± 2.5 to 1.9 ± 1.0 mm) (p < 0.05). The LM extrusion measured on the sagittal plane of postoperative MRI was also significantly reduced after arthroscopic repair (24.8 ± 3.1-23.7 ± 2.8 mm) (p = 0.001). Five reoperations (5/93, 5.3%) were performed, suggesting a clinical failure. CONCLUSION: Arthroscopic repair of isolated, discoid and post-traumatic LMTs including the popliteus tendon around the popliteal hiatus, is an effective surgical treatment for LM stabilization. LEVEL OF EVIDENCE: Level IV, retrospective series.

Study on the correlation between shear wave elastography and MRI grading of meniscal degeneration.

BACKGROUND: Shear Wave Elastography (SWE) offers quantitative insights into the hardness and elasticity characteristics of tissues. The objective of this study is to investigate the correlation between SWE of the menisci and MRI-assessed degenerative changes in the menisci, with the aim of providing novel reference source for improving non-invasive evaluation of meniscal degenerative alterations. METHODS: The participants in this study were selected from patients who underwent knee joint MRI scans at our hospital from February 2023 to February 2024. The anterior horns of both the medial and lateral menisci were evaluated using SWE technique. The differences in elastic values of meniscus among different MRI grades were compared. The correlation between elastic values and MRI grades, as well as various parameters, was analyzed. Using MRI Grade 3 as the gold standard, the optimal cutoff value for meniscal tear was determined. The intraclass correlation coefficient (ICC) was employed to evaluate the reliability of repeated measurements performed by the same observer. RESULTS: A total of 104 female participants were enrolled in this study, with 152 lateral menisci (LM) and 144 medial menisci (MM) assessed. For the male group, 83 individuals were included, with 147 LM and 145 MM evaluated. The results demonstrated statistically significant differences in the elasticity values of the menisci at the same anatomical sites across different MRI grades (P < 0.001). Within the same grade, the MM had higher elasticity values than the LM, showing a statistically significant difference (P < 0.001). The elasticity values of the menisci were higher in males compared to females. There were statistically significant positive correlations between the elasticity values of the menisci and age, BMI, and MRI grade. The ICC for repeated measurements within the observer demonstrated good reliability (> 0.79). CONCLUSIONS: The meniscal elasticity values measured by SWE exhibit a significant positive correlation with the grades of degeneration assessed by MRI. Furthermore, the elasticity values of the meniscus are found to increase with advancing age and elevated BMI.

Suture Tying Force for Cut-Out during Radial Meniscus Tear Repair: A Biomechanical Evaluation of Failure Loads during the Knot-Tying Process.

OBJECTIVE: The purpose of the study was to determine average tensile forces resulting in suture failure while tying a knot during repair of complete radial meniscus tears and to compare the failure tensile force based on meniscus tissue location: the peripheral (red-red) versus inner (white-white). DESIGN: This study was designed as a cadaveric biomechanical study using 24 menisci harvested from fresh frozen cadaveric knees with midbody radial tears. Tears were repaired using 2-0 nonabsorbable suture in both the inner meniscus and the peripheral meniscus. A force gauge was used to measure the tension of a surgeon's knot until failure of either the suture or the meniscus tissue. Statistical analysis was performed comparing suture failure tensile forces between inner and peripheral sutures using 2-sample t test. RESULTS: Suture repairs primarily failed due to meniscal tissue cut-out after suture tensioning (96%). There was no statistical difference in failure mode between medial and lateral meniscus for both the inner (100% cut-out) and the peripheral (92% cut-out; P = 0.703) sutures. The peripheral sutures failed as significantly higher loads (54 ± 26 N) than the inner sutures (36 ± 11 N, P = 0.006). The peripheral meniscus tissue tolerated significantly higher tension at failure (36 ± 7 N) than the inner meniscus (26 ± 7 N, P < 0.001). CONCLUSION: When tying parallel sutures to repair a radial meniscus tear, suture tensile forces above 30 N may tear through meniscus tissue. Surgeons should not use suture tying forces above 30 N when repairing radial meniscus tears with parallel sutures. The peripheral meniscus can withstand higher knot-tying forces than the inner meniscus, so surgeons should consider tying the peripheral suture before the inner suture.

Exercise Induced Endothelial Mesenchymal Transition (EndMT) Facilitates Meniscal Fibrocartilage Regeneration.

The meniscus is a semilunar wedge-shaped fibrocartilage tissue within the knee joint that is important for withstanding mechanical shock during joint motion. The intrinsic healing capacity of meniscus tissue is very limited, which makes meniscectomy the primary treatment method in the clinic. An effective translational strategy for regenerating the meniscus after total or subtotal meniscectomy, particularly for extensive meniscal lesions or degeneration, is yet to be developed. The present study demonstrates that the endothelial mesenchymal transition (EndMT) contributes to meniscal regeneration. The mechanical stimulus facilitated EndMT by activating TGF-ß2 signaling. A handheld bioprinter system to intraoperatively fabricate a porous meniscus scaffold according to the resected meniscus tissue is developed; this can simplify the scaffold fabrication procedure and period. The transplantation of a porous meniscus scaffold combined with a postoperative regular exercise stimulus facilitated the regeneration of anisotropic meniscal fibrocartilaginous tissue and protected the joint cartilage from degeneration in an ovine subtotal meniscectomy model. Single-cell RNA sequencing and immunofluorescence co-staining analyses further confirmed the occurrence of EndMT during meniscal regeneration. EndMT-transformed cells gave rise to fibrochondrocytes, subsequently contributing to meniscal fibrocartilage regeneration. Thus, an efficient translational strategy to facilitate meniscal regeneration is developed.

[High tibial osteotomy on varus knee osteoarthritis with medial meniscus posterior root injury].

OBJECTIVE: To explore clinical effect of distal tibial tubercle-high tibial osteotomy (DTT-HTO) in treating knee osteoarthritis (KOA) with medial meniscus posterior root tear (MMPRT). METHODS: A retrospective analysis was performed on 21 patients with varus KOA with MMPRT from May 2020 to December 2021, including 3 males and 18 females, aged from 49 to 75 years old with an average of (63.81±6.56) years old, the courses of disease ranged from 0.5 to 18.0 years with an average of(5.9±4.2) years, and 4 patients with grade Ⅱ, 14 patients with grade Ⅲ, and 3 patients with grade Ⅳ according to Kellgren-Lawrence;14 patients with type 1 and 7 patients with type 2 according to MMPRT damage classification. The distance of medial meniscusextrusion (MME) and weight-bearing line ratio (WBLR) of lower extremity were compared before and 12 months after operation. Visual analogue scale (VAS), Western Ontarioand and McMaster Universities (WOMAC) osteoarthritis index, and Lysholm knee score were used to evaluate knee pain and functional improvement before operation, 1, 6 and 12 months after operation, respectively. RESULTS: Twenty-one patients were followed up for 12 to 18 months with an average of (13.52±1.72) months. MME distance was improved from (4.99±1.05) mm before operation to (1.87±0.76) mm at 12 months after operation (P<0.05). WBLR was increased from (15.49±7.04)% before operation to (62.71±2.27)% at 12 months after operation (P<0.05). VAS was decreased from (7.00±1.14) before operation to (2.04±0.80), (0.90±0.62) and (0.61±0.50) at 1, 6 and 12 months after operation. WOMAC were decreased from preoperative (147.90±9.88) to postoperative (103.43±8.52), (74.00±9.54) and (47.62±9.53) at 1, 6 and 12 months, and the difference were statistically significant (P<0.05). Lysholm scores were increased from (46.04±7.34) before oepration to (63.19±8.93), (81.10±6.41) and (89.29±3.04) at 1, 6 and 12 months after operation(P<0.05). CONCLUSION: For the treatment of varus KOA with MMPRT, DTT-HTO could reduce medial meniscus protrusion distance, improve the ratio of lower limb force line, and effectively reduce knee pain and improve knee joint function.

The Impact of Age and Gender on Anterior Cruciate Ligament Injuries and Associated Knee Lesions: A Retrospective Study.

OBJECTIVES: This study aimed to evaluate the anterior cruciate ligament (ACL)-associated lesions in knee sports injuries in magnetic resonance imaging (MRI) and the effect of genders and ages on the patterns of the associated lesions in Arar, Northern Border region, Saudi Arabia. METHODS: This retrospective cohort study enrolled MRI of knee sports injuries with diagnosed ACL lesions during the period from January 2018 to December 2023 in Prince Abdulaziz Bin Musaed Hospital and Alkhibrah Health Center in Arar. RESULTS: A total of 505 knee MRI images were enrolled in the study. There were 104 (20.5%) females and 401 (79.5%) males with an average age of 34.5 years (range: 10-85 years) in this study. ACL lesions were reported in 191 (37.8%) cases. ACL was reported to be associated with other knee lesions in 185 (96.8%) cases. Joint effusion and posterior horn medial meniscus (PHMM) lesions were the most associated lesions found in 112 (58.9%) and 108 (56.5%) cases, respectively. Aging was found to significantly increase the incidence of PHMM and joint effusion associated with ACL tears, with estimated relative risks of 1.4 and 1.5 (odds ratio: 2.19 and 2.6), respectively. Also, the female gender was found to significantly increase the incidence of PHMM and associated ligament injuries with estimated relative risks of 1.5 and 4.1 (odds ratio: 3.6 and 5.1), respectively. CONCLUSION: Tears of ACL are prevalent patterns of knee sports injuries with different types of associated injuries, which can be affected by the ages and genders of the patients.

Prospective Assessment of Outcomes After Femoral Condyle Osteochondral Allograft Transplantation With Concurrent Meniscus Allograft Transplantation.

Background: Osteochondral allograft transplantation (OCAT) and meniscus allograft transplantation (MAT) have each become more commonly implemented for the treatment of young to middle-aged patients with complex knee pathology. Evidence regarding tibiofemoral OCAT in the setting of concurrent MAT is limited. Purpose/Hypothesis: The purpose of this study was to characterize outcomes for femoral condyle OCAT with concurrent MAT (OCAT+MAT) in the ipsilateral compartment of patients after evidence-based shifts in practice. It was hypothesized that OCAT+MAT would be associated with successful outcomes characterized by statistically significant and clinically meaningful improvements in patient-reported outcome measures (PROMs) of knee pain and function in >80% of patients for at least 2 years after transplantation. Study Design: Case series; Level of evidence, 4. Methods: With institutional review board approval and documented informed consent, patients who underwent primary OCAT+MAT between 2016 and 2020 and enrolled in a lifelong registry for prospective collection of outcomes after OCAT were included. Patients with minimum 2-year follow-up data regarding complications, failures, adherence, and PROMs were analyzed. Patients who required OCAT and/or MAT revision or conversion to arthroplasty were defined as experiencing treatment failures. Results: A total of 23 consecutive patients (mean age, 37.1 years; mean body mass index, 28 kg/m2; 14 men) met the inclusion criteria, with a mean follow-up of 51 months (range, 24-86 months). The initial treatment success rate was 78% based on 5 initial treatment failures, and the overall success rate was 83% based on a successful revision OCAT. All failures occurred in the medial compartment. Older patient age (42.2 vs 32.1 years; P = .046) and nonadherence to postoperative restriction and rehabilitation protocols (P = .033; odds ratio, 14) were significant risk factors for treatment failure. All measured PROMs achieved significant improvements (P < .001) and minimum clinically important differences at a minimum of 2 years postoperatively. Conclusion: OCAT+MAT was associated with successful short- to mid-term outcomes in 83% of cases. Evidence-based shifts in practice were implemented before the enrollment of this patient cohort. Older patients and those who were not adherent to postoperative restriction and rehabilitation protocols had a significantly higher risk for treatment failure and subsequent conversion to arthroplasty.

A Prospective, Randomized, Double-Blind Clinical Trial to Investigate the Efficacy of Autologous Bone Marrow Aspirate Concentrate During Arthroscopic Meniscectomy in Patients With Early Knee Osteoarthritis.

BACKGROUND: Despite being recognized as a safe procedure with minimal reported complications, injecting autologous bone marrow aspirate concentrate (BMAC) as an adjuvant to arthroscopic partial meniscectomy (APM) for symptomatic patients with meniscal tears and concomitant knee osteoarthritis (OA) has not been studied in randomized controlled trials. PURPOSE: To compare patient-reported outcome measure (PROM) scores and radiographic outcomes in symptomatic patients with meniscal tears and concomitant mild knee OA who underwent APM with and without an autologous BMAC injection administered at the time of surgery. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Enrolled patients aged ≥18 years determined to have a symptomatic meniscal tear with concomitant mild knee OA suitable for APM and meeting inclusion and exclusion criteria were randomized into 2 groups: BMAC and control (no BMAC). The primary endpoint of the study was the International Knee Documentation Committee (IKDC) score at 1 year postoperatively. Secondary endpoints included radiographic outcomes (Kellgren-Lawrence grade) at 1 year postoperatively and various PROM scores, including those for the IKDC, Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale, and Veterans RAND 12-Item Health Survey, at 3 months, 6 months, 1 year, and 2 years after meniscectomy. RESULTS: Of the 95 enrolled patients, 83 (87.4%) were included for final analysis. No significant differences were found between the groups with regard to patient characteristics, intraoperative variables, concomitant procedures, preoperative PROM scores, or preoperative radiographic findings. At 1 year postoperatively, the BMAC group failed to demonstrate significantly better IKDC scores (P = .687) or radiographic outcomes (P > .05 for all radiographic measures) compared with the control group. Secondary PROM scores also did not significantly differ between the groups (P > .05 for all PROMs). However, there were higher achievement rates of the minimal clinically important difference for the KOOS Sport (100.0% vs 80.0%, respectively; P = .023) and KOOS Symptoms (92.3% vs 68.0%, respectively; P = .038) at 1 year postoperatively in the BMAC group than in the control group. All PROMs, excluding the VR-12 mental score, showed significant improvements compared with baseline at all postoperative time points for both the BMAC and control groups. CONCLUSION: The addition of an autologous BMAC injection during APM did not result in significant changes in IKDC scores or radiographic outcomes at the 1-year postoperative mark. Secondary PROM scores were generally comparable between the 2 groups, but there was higher minimal clinically important difference achievement for the KOOS Sport and KOOS Symptoms at 1 year postoperatively in the BMAC group. In patients with symptoms consistent with a meniscal tear who had concomitant mild OA, the addition of BMAC to arthroscopic debridement did not affect the outcome. REGISTRATION: NCT02582489 (ClinicalTrials.gov).

Arthroscopic Centralization of the Medial Meniscus Reduces Load on a Posterior Root Repair Under Dynamic Varus Loading: A Biomechanical Investigation.

BACKGROUND: In addition to the integrity of the meniscal hoop function, both the anterior and posterior meniscus roots as well as the meniscotibial and meniscofemoral ligaments are crucial in restraining meniscal extrusion. However, the interaction and load sharing between the roots and these peripheral attachments (PAs) are not known. PURPOSES: To investigate the influence of an insufficiency of the PAs on the forces acting on a posterior medial meniscus root repair (PMMRR) in both neutral and varus alignment and to explore whether meniscal centralization reduces these forces. STUDY DESIGN: Controlled laboratory study. METHODS: In 8 fresh-frozen human cadaveric knees, an arthroscopic transosseous root repair (step 1) was performed after sectioning the posterior root of the medial meniscus. The pull-out suture was connected to a load cell to allow measurement of the forces acting on the root repair. A medial closing-wedge distal femoral osteotomy was performed to change the mechanical axis from neutral to 5° of varus alignment. The meniscus was completely released from its PAs (step 2), followed by transosseous arthroscopic centralization (step 3). Each step was tested in both neutral and varus alignment. The specimens were subjected to nondestructive dynamic varus loading under axial compression of 300 N in 0°, 15°, 30°, 45°, and 60° flexion. The changes in force acting on the PMMRR were statistically analyzed using a mixed linear model. RESULTS: Axial loading in neutral alignment led to an increase of the force of root repair of 3.1 ± 3.1 N (in 0° flexion) to 6.3 ± 4.4 N (in 60° flexion). In varus alignment, forces increased significantly from 30° (3.5 N; 95% CI, 1.1-5.8 N; P = .01) to 60° (7.1 N; 95% CI, 2.7-11.5 N; P = .007) flexion, in comparison with neutral alignment. Cutting of the PAs in neutral alignment led to a significant increase of root repair forces in all flexion angles, from 7.0 N (95% CI, 1.0-13.0 N; P = .02) to 9.1 N (95% CI, 4.1-14.1 N; P = .003), in comparison with the intact state. Varus alignment significantly increased the forces in the cut states from 4.8 N (95% CI, 1.0-8.5 N; P = .02) to 11.1 N (95% CI, 4.2-18.0 N; P = .006) from 30° to 60° flexion, in comparison with the neutral alignment. Arthroscopic centralization led to restoration of the native forces in both neutral and varus alignment, with no significant differences between the centralized and intact states. CONCLUSION: An insufficiency of the PAs of the medial meniscus, as well as varus alignment, led to increased forces acting on a PMMRR. These forces were reduced via an arthroscopic meniscal centralization. CLINICAL RELEVANCE: Performing arthroscopic meniscal centralization concomitantly with PMMRR may reduce failure of the repair by reducing the load of the root.

Prevalence of Abnormalities and Normal Variants in the Adolescent Knee on MRI in a Population-Based Cohort of 3800 Knees.

BACKGROUND: Many adolescents experience knee pain, and only some undergo detailed imaging. In this population, the prevalence of abnormalities and normal variants on magnetic resonance imaging (MRI) scans is unknown. PURPOSE: To investigate the prevalence of abnormalities and normal variants of the knee on MRI scans and their relationship with participant characteristics in the general young adolescent population. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: This study was part of an open population-based cohort study that focuses on health, growth, and development from fetal life until adulthood. Between 2017 and 2020, adolescents aged 12 to 15 years underwent MRI of both knees. These MRI scans were assessed in a standardized way for abnormalities and normal variants to determine their prevalence. Logistic regression was used to analyze the presence of abnormalities and normal variants in relation to sex, height, weight, body mass index-standard deviation (BMI-SD), and ethnicity. RESULTS: A total of 1910 participants (median age, 13.5 years; interquartile range, 13.4-13.7 years; 52% girls) were included in this study. Of them, 370 (19.4%) participants had at least 1 abnormality or normal variant. Bone marrow edema around the knee was the most prevalent finding, affecting 140 (7.3%) participants. In 107 (5.6%) participants, nonossifying fibromas were found. A total of 43 (2.3%) participants had characteristics of Osgood-Schlatter disease, 16 (0.8%) showed characteristics of Sinding-Larsen-Johansson syndrome, and osteochondritis dissecans was found in 13 (0.7%) participants. Variants such as discoid menisci were found in 40 (2.1%) participants and a bipartite patella in 21 (1.1%) participants. There were multiple associations between abnormalities or variants and participant characteristics, including bone marrow edema being more often present in boys (odds ratio [OR], 2.44; 95% CI, 1.69-3.52) and those with a lower BMI-SD (OR, 0.85; 95% CI, 0.73-0.98). Osgood-Schlatter and osteochondritis dissecans were more often present in boys (OR, 4.21 [95% CI, 2.01-8.85] and OR, 13.18 [95% CI, 1.71-101.58], respectively). Discoid menisci were associated with a non-Western ethnicity (OR, 2.06; 95% CI, 1.07-3.96) and higher BMI-SD (OR, 2.34; 95% CI, 1.76-3.11). CONCLUSION: Abnormalities and normal variants on MRI scans of the knees are common in adolescents. Physicians who are involved in the treatment of adolescents with knee pain need to be aware of this prevalence so that these children will not be overtreated or misdiagnosed.