BACKGROUND: Congenital absence of the menisci is a rare anatomical variation characterized by the absence or underdevelopment of one or both menisci in the knee joint. The menisci are crucial in load distribution, joint stability, and shock absorption. Understanding the clinical presentation, diagnosis, and management of this condition is important for optimal patient care.
METHODS: A 27-year-old male with a long-standing history of knee pain underwent diagnostic arthroscopy, revealing a congenital absence of the meniscus. The patient\'s clinical findings, imaging results, surgical procedures, and pertinent images are detailed. This case presents a unique aspect with the congenital absence of the meniscus, contributing valuable insights to the literature on rare anatomical anomalies.
CONCLUSIONS: This case of congenital absence of the menisci highlights the diagnostic challenges posed by rare anomalies. The diagnostic arthroscopy played a crucial role in identifying the absence of the meniscus and providing an explanation for the patient\'s persistent knee pain. The case underscores the importance of individualized treatment approaches, including physical therapy, for optimal management of rare meniscal anomalies. Further research is warranted to explore effective management strategies for the aforementioned cases and to expand our knowledge of these rare conditions.

Numerous studies on meniscal tears have been published, a pathology that continues to evolve in terms of treatment and patient outcomes. As our understanding of anatomy and biomechanics improves, new entities have emerged. The lateral meniscus, especially its posterior attachment, tends to be overlooked due to its greater mobility compared to the medial meniscus. Evaluating the instability of the posterior horn poses a challenge, even during arthroscopy, therefore, it is crucial to understand the posterior menisco-synovial detachment lesions, which are indeed real and, to date, haven\'t received enough attention in the existing literature. The aim is to describe a new entity affecting the posterior synovial attachment of the lateral meniscus, without injury to the posterior horn of the lateral meniscus (PHLM). We also aim to present a case report detailing the intraoperative diagnosis and management of a 20-year-old patient with a sports trauma that led to a combined anterior cruciate ligament (ACL) and lateral meniscus tear managed with arthroscopic ACL reconstruction and all-inside meniscal suture. Through conventional arthroscopic evaluation of the posterior capsule anatomy and dissections, we have identified a distinct lesion of the PHLM at the menisco-synovial junction. Further research is necessary in this field to understand the biomechanical repercussions and determine the ideal surgical management.

UNASSIGNED: Anterolateral knee laxity (ALLx) has been linked to tears of the lateral meniscus (LM) and anterior cruciate ligament (ACL) injury.
UNASSIGNED: To investigate the longitudinal relationship between the signal intensity (SI) of the repaired LM on magnetic resonance imaging (MRI) and residual ALLx after ACL reconstruction (ACLR).
UNASSIGNED: Cohort study; Level of evidence, 3.
UNASSIGNED: Included were 87 patients who underwent double-bundle ACLR and lateral meniscal repair (mean age, 23.5 years; body mass index, 23.7 kg/m2; 56 women) at a single institution between 2010 and 2019. Proton density-weighted (PDW) and T2-weighted (T2W) MRI was performed at 3, 6, and 12 months postoperatively, and the SI ratio (SIR) was calculated as (SI of the repaired LM)/(SI of the posterior cruciate ligament). At the 12-month follow-up, ALLx was evaluated using the pivot-shift test; an International Knee Documentation Committee grade ≥1 indicated residual ALLx.
UNASSIGNED: Overall, 12 patients (13.8%) exhibited ALLx at 12 months postoperatively. At 3 months postoperatively, the SIR on PDW images (SIR-PDW) was significantly higher in patients with ALLx versus those without ALLx (1.98 ± 0.77 vs 1.49 ± 0.52, respectively; P = .007); there was no difference in the SIR on T2W images between the groups. SIR-PDW at 3 months postoperatively was correlated negatively with patient age (r = -0.308, P = .004). When patients were stratified into a younger (≤22 years; n = 53; ALLx = 7 [13.2%]) and an older (>22 years; n = 34; ALLx = 5 [14.7%]) group, the area under the receiver operating characteristic curves (AUCs) for SIR-PDW in the younger group were statistically significant for predicting the prevalence of ALLx at all follow-up times (AUCs, 0.733-0.788) with optimal cutoff values of 2.00 at 3 months, 1.50 at 6 months, and 1.50 at 12 months. Logistic regression analysis revealed that if younger patients consistently had higher SIR-PDW values than the cutoff values, they were more likely to have residual ALLx (odds ratios, 10.24-23.57).
UNASSIGNED: For younger patients who underwent both ACLR and lateral meniscal repair, higher MRI SI of the repaired LM was associated with a higher prevalence of residual ALLx.

UNASSIGNED: Commonly cited discoid lateral meniscus (DLM) imaging definitions are based on adult magnetic resonance imaging (MRI) measurements. This pathology commonly presents in pediatric populations; however, whether accepted adult measurements reliably apply to children and adolescents is unknown.
UNASSIGNED: This purposes of the study were to determine (1) the utility of applying adult-accepted MRI definitions of DLM to pediatric patients, (2) whether sex differences affect the applicability of the criteria, and (3) whether MRI magnet strength and/or tear presence affect MRI measurements for diagnosing DLM in pediatric patients. It was hypothesized that MRI criteria for DLM would be similar in adults and pediatric patients.
UNASSIGNED: Case series; Level of evidence, 4.
UNASSIGNED: A total of 100 consecutive MRIs from pediatric patients with DLM were evaluated, with 91 scans included. Two study authors independently reviewed the MRIs, evaluating meniscal height and width on sagittal and coronal images, \"bow tie signs\" on sagittal images, tibial sagittal and coronal width, and tear presence. For analysis, MRI magnet strength was dichotomized into high (>1.5 T) and low (<1.5 T) groups.
UNASSIGNED: The mean age of the patients at MRI evaluation was 12.3 ± 3.4 years; 51% of the patients were male, and 56% of the scans were of left knees. Included patients with DLM showed a mean of 3.68 bow tie signs, a sagittal total anterior to posterior meniscal width/tibial width ratio of 73%, a coronal meniscal width/tibial width ratio of 30%, and a coronal, transverse width of the lateral meniscus at the midportion of the meniscal body of 20.6 ± 7.7 mm. The MRI tesla strength of the images included in this study ranged from 0.3 to 3. It was determined that high- versus low-resolution MRI scans did not affect the inter- or intraobserver reliability of the MRI measurments (P > .05). However, several measurements showed improved intraclass correlation coefficients with increased tesla strength.
UNASSIGNED: This study confirms that pediatric patients with DLM, diagnosed by board-certified pediatric sports medicine orthopaedic surgeons, have measurements on MRI consistent with adult DLM diagnostic criteria. This finding held true regardless of sex or MRI tesla strength. Pediatric patients with DLM had >3 bow tie signs, >70% sagittal tibial plateau coverage, >14 mm coronal width, and >20% coronal tibial plateau coverage on MRI.

BACKGROUND: An accessory extreme far anteromedial portal can improve visualisation and ease inferior leaf meniscectomy in patients with lateral meniscal anterior horn horizontal tears. However, the therapeutic outcomes of adding an accessory extreme far anteromedial portal remain unclear. This study aimed to evaluate the clinical efficacy of adding an accessory extreme far anteromedial portal for treating lateral meniscal horizontal tears involving the anterior horns.
METHODS: This retrospective study included 101 patients with anterior horn involvement in lateral meniscal horizontal tears who underwent arthroscopic unstable inferior leaf meniscectomy between January 2016 and December 2020. The pathologies were diagnosed using physical examinations and magnetic resonance imaging. The anterior horn involved in the lateral meniscal horizontal tears was treated using inferior leaf meniscectomy. The primary endpoints were changes in the visual analogue scale, Lysholm, International Knee Documentation Committee, and Tegner scores at the final follow-up. The secondary endpoint was meniscal cure rate at 3 months postoperatively. The preoperative and postoperative functional scores were compared. The occurrence of complications was recorded.
RESULTS: All patients were followed up for an average of 4.9 ± 1.2 years (range 2.3-7.5 years). After 4 months, none of the patients experienced pain, weakness, instability, or tenderness in the lateral joint line, achieving an imaging cure rate of 98%. At the final follow-up, significant postoperative improvements were observed in the average values of the visual analogue scale score (3.5 ± 0.7 vs. 0.7 ± 0.6), Lysholm score (62.7 ± 4.4 vs. 91.8 ± 3.1), International Knee Documentation Committee score (61.9 ± 3.7 vs. 91.7 ± 9.5), and Tegner score (2.0 ± 0.7 vs. 6.1 ± 0.7). Excellent Lysholm scores were obtained in 81 patients, and good outcomes were obtained in 18 patients, with an excellent-to-good rate of 98.0%.
CONCLUSIONS: Inferior leaf resection via the accessory far anteromedial portal is a safe treatment option for the involved anterior horn in lateral meniscal horizontal tears. This approach enhances visibility and facilitates surgical procedures, with minimal complications.

UNASSIGNED: Anterior cruciate ligament (ACL) tears are commonly seen with concomitant injuries to the posterolateral tibial plateau, while the occurrence of ACL injuries in posterolateral tibial plateau fractures (PTPFs) remains unclear.
UNASSIGNED: To (1) explore the incidence of knee ligament (anterior or posterior cruciate ligament, medial or lateral collateral ligament) and medial or lateral meniscus injuries in patients with PTPF and (2) find reliable PTPF-related parameters to predict the risk of knee ligament and meniscal injuries.
UNASSIGNED: Cross-sectional study; Level of evidence, 3.
UNASSIGNED: Patients diagnosed with PTPF who had computed tomography and magnetic resonance imaging (MRI) data were identified. Morphological parameters of the PTPF were measured on sagittal computed tomography images. Knee ligament and meniscal injuries were assessed using MRI. The association of ACL injuries with meniscal injuries was analyzed. Receiver operating characteristic (ROC) analysis was used to determine the value and cutoff point of the PTPF morphological parameters for diagnosing complete in-substance ACL tears.
UNASSIGNED: Overall, 113 patients with PTPF were included. ACL injuries were present in 94 (83.2%) patients, including 43 (38.1%) avulsion fractures and 28 (24.8%) complete in-substance tears. Patients with in-substance ACL tears had a higher incidence of lateral meniscus posterior horn tears compared with the other patients (PBonferroni < .001). ROC analysis revealed that both the fracture depression angle (cutoff point, 25.5°) and the posterior articular surface loss percentage (cutoff point, 37.5%) had a sensitivity >90% and a specificity >80% for the diagnosis of complete in-substance ACL tears.
UNASSIGNED: ACL injuries were seen in 83.2% of the study patients. Complete in-substance ACL tears were associated with an increased incidence of lateral meniscus posterior horn tears. Among PTPF parameters, fracture depression angle and posterior articular surface loss percentage showed a high predictive value for the presence of complete in-substance ACL tears, thereby reducing delays in diagnosis and treatment.

BACKGROUND: In younger patients, meniscal repair is recommended for isolated lateral meniscus tears that are most often due to acute trauma. But there is little published data on the outcomes of repairing this specific type of lesion. The goal of this study was to evaluate the clinical outcomes, report the failure rate of repairing radial tears of the lateral meniscus in stable knees and determine the risk factors for failure.
METHODS: All patients who had a stable knee and underwent arthroscopic repair of a radial lateral meniscus tear between April 2013 and December 2019 were reviewed retrospectively. Failure was defined as revision surgery for recurrence of symptoms (pain, locking) with intraoperative confirmation that the meniscus did not heal. The following data were collected: demographics (age, sex, BMI), time to surgery, clinical outcome scores (Tegner, Lysholm, IKDC), surgical details (repair technique, lesion zone, number of sutures).
RESULTS: Thirty patients were included having a mean age of 20.1years (14-31). The follow-up ranged from 24 to 110months (mean 66.8±25.2). An all-inside repair was done in 6 patients (20%); an outside-in technique was done in 17 patients (57%) and a combination of all-inside and outside-in was done in 7 patients (23%). Four patients (13%) had a recurrence of their symptoms later on, while participating in sports. All the recurrences were at the initial tear site. The time to revision surgery was 16, 19, 24 and 37months in these four patients (mean 24±9). All the other patients were able to resume sports at their pre-injury level. Significant improvement in the IKDC, Lysholm and Tegner functional scores were found between the preoperative and postoperative assessments. No statistically significant risk factors for failure were identified.
CONCLUSIONS: The functional healing rate after repair of a radial lateral meniscus tear in a stable knee was 86% at a mean follow-up of 5years, with the surgical technique having no impact on the long-term result. Most of the failures occurred within 2years of the repair procedure. We recommend repairing these tears as they have considerable healing potential.
METHODS: IV; retrospective observational cohort study.

The anatomy of the lateral meniscus underlies the understanding of its unique biomechanics. Moreover, the knowledge of its microscopic structure, its vascularization and its ligament insertions can make us understand the rationale for its surgical treatment. It is well known as the respect of the anatomy leads to better results in reconstructive surgery. Knowing the differences in the shape and in the areas of insertion of the meniscal roots can be useful in case of reinserting a root or when performing a meniscal transplant. Learning about the capsular insertions, the anchoring ligaments and the areas of greatest mobility of the lateral meniscus is useful during meniscal repair and replacement surgery. This information can let us choose the most appropriate technique and the best device to face any kind of meniscal lesion. In this article, we will consider both the micro and the macro meniscal structure in order to be able to give a description as complete as possible of this fundamental structure. We will consider the interrelation of the meniscus with the neighboring anatomical structures with which it contributes to the biomechanical control of the joint. It is important to understand the interrelation with both anterior and posterior cruciate ligament (PCL) given that frequently a combined meniscal and ligamentous reconstruction is necessary.

There is a paucity of studies in the literature pertaining about how to guide rehabilitation and return to sport (RTS) progression for football players that have sustained a lateral meniscus injury and subsequent surgery. These patients are clinically challenging. If they return to sport too soon, before the rehabilitation process is completed and RTS criteria have been met, functional outcomes could be non-optimal and/or associated with higher reinjury risk. The aims of this paper are (I) to provide a brief overview of the current trends in acute lateral meniscus tears surgery in football players and (II) to suggest a framework for clinicians on how to progress the player following lateral meniscus surgery. Post-operative rehabilitation approaches are different for meniscus repair and for the other surgical techniques. The main goal of all involved practitioners should be to balance the \"short term success\" with the \"long term protection\" of the athlete\'s health. Specific key goals and interventions in early-, mid-, and late-stage rehabilitation are provided. The most important principle is to manage the progressive increase in loading through multiple measurements including frequent medical control consultations and functional tests detailing movement quantity and quality. RTS monitoring needs to be comprehensive and interdisciplinary, incorporating state of the art tests, to achieve recovery of sport-specific fitness, optimal movement quality and on-field rehabilitation progression.

The menisci increase the stability of the tibio-femoral joint, distribute axial load, absorb shock, and provide nutrition and lubrification to the knee articular cartilage. Therefore, is it clear the importance of the meniscus on the overall knee function and the need to preserve it during arthroscopic surgery. However, according to many registry databases, meniscectomy is still the most performed meniscus surgery. In a percentage of patients, knee pain and swelling, as well as bone edema on the tibial plateau, could follow meniscus resection; this constellation of symptoms is known as \"post-meniscectomy syndrome\". If this syndrome is not promptly managed, a rapid worsening of the symptoms and develop of knee osteoarthritis could be expected. While dealing with such condition, the clinician must perform first an accurate clinical examination and a full radiological evaluation. If the patient is candidate for surgery, the replacement of the resected tissue should be performed: a meniscus allograft should be implanted in case of previous total meniscectomy or a meniscus scaffold if the patients has an history of a previous partial resection. The present article represents a comprehensive review of the literature and aims to discuss basic science, preoperative planning and evaluation, indication, surgical technique, and outcomes of the lateral collagen meniscus implant (CMI), a biologic scaffold aimed at replacing partial meniscal defects.