[Medial discoid meniscus in a pediatric patient. Case report and review of the literature]. / Menisco discoide medial en paciente pediátrico. Presentación de un caso y revisión de la literatura.

Discoid meniscus is a congenital morphological variant of the meniscus, which tends to occur more frequently in its lateral form than in the medial form. This anomaly is characterized by central hypertrophy of the meniscus and a larger diameter than the normal meniscus, resulting in an abnormal shape and greater coverage of the tibial plateau. The clinical presentation of this condition varies depending on the stability of the meniscus. In pediatric patients, in particular, it is common to experience progressive and atraumatic symptoms, such as pain and limited mobility. Diagnosis is based on imaging studies, with magnetic resonance imaging being the preferred tool, where the "bowtie sign" is a classic finding. Surgery is recommended for symptomatic patients, with a focus on preserving the peripheral portion of the meniscus. Saucerization is the most commonly used technique, followed by stability assessment to determine if additional procedures are required. In this case, a 9-year-old patient with a medial discoid meniscus presented symptoms following trauma. Despite this atypical presentation, a successful outcome was achieved through arthroscopic surgery, underscoring the importance of accurate diagnosis and proper management of this condition in pediatric patients. Understanding the anatomical and pathophysiological characteristics of the discoid meniscus is essential for an effective therapeutic approach.

El menisco discoide es una variante morfológica congénita del menisco, que suele presentarse con mayor frecuencia en su forma lateral que en la medial. Esta anomalía se caracteriza por la hipertrofia central del menisco y un diámetro mayor que el menisco normal, lo que resulta en una forma anormal y una mayor cobertura del platillo tibial. La presentación clínica de esta condición varía según la estabilidad del menisco. En pacientes pediátricos, en particular, es común experimentar síntomas progresivos y atraumáticos, como dolor y limitación de la movilidad. El diagnóstico se basa en estudios de imagen, siendo la resonancia magnética la herramienta preferida, donde el "signo del corbatín" es un hallazgo clásico. Se recomienda la cirugía para pacientes sintomáticos, con un enfoque en preservar la porción periférica del menisco. La saucerización es la técnica más utilizada, seguida de la evaluación de la estabilidad para determinar si se requiere un procedimiento adicional. En el presente caso, se describe a un paciente de nueve años con un menisco discoide medial que manifestó síntomas después de un traumatismo. A pesar de esta presentación atípica, se logró un resultado exitoso mediante una cirugía artroscópica, lo que resalta la importancia de un diagnóstico preciso y un manejo adecuado de esta condición en pacientes pediátricos. La comprensión de las características anatómicas y patofisiológicas del menisco discoide es esencial para un enfoque terapéutico efectivo.

Asymmetric Deficit of Knee Flexion: An Occasional Symptom of Discoid Lateral Meniscus in Children.

PURPOSE: A knee flexion deficit can be the unique symptom and sign of discoid lateral meniscus (DLM) in children. The aim of this study was to investigate the accuracy of this clinical sign. The hypothesis was that deficit of knee flexion was associated with anterior rim disinsertion and posteriorly fixed DLM. METHODS: A retrospective, single-center study was conducted in a larger series of 114 operated knees for symptomatic DLM from 2007 to 2018. A focus was done on 9 knees with a deficit of knee flexion without snapping. History and clinical examination with grading of instability, preoperative magnetic resonance imaging, and arthroscopic findings were studied. RESULTS: Among 35 knees with DLM grade 3 of instability, 26 had an isolated extension deficit. Nine knees in 5 boys and 4 girls with a mean age of 9 years (range 6 to 12) had a flexion deficit. It was the only symptom of DLM in 6, and it was associated to extension deficit in 3. In the history, 8 knees were grade 2 (snapping knee) before evolving toward a flexion deficit. All had a complete DLM with posterocentral (n=7) or central (n=2) shift at magnetic resonance imaging analysis. All had DLM with posterior shift fixed during arthroscopic evaluation. Moreover, looking at the entire series, 1 knee was a false negative and had a full flexion despite a posterior and fixed DLM during arthroscopic evaluation. The sensitivity of asymmetrical knee flexion to predict posterior fixed DLM was 90%. CONCLUSIONS: An asymmetric deficit in knee flexion is highly suggestive of DLM with anterior detachment and fixed posterior meniscal shift (specificity and positive predictive value of 100%). Given this could be the only clinical sign of DLM, specific attention therefore must be paid in the assessment of knee flexion by measuring the distance between heel and bottom on both sides, especially in a knee without snapping currently but with a history of snapping (grade 3). LEVEL OF EVIDENCE: Level III.

Evaluation of knee bone morphology in juvenile patients with complete discoid lateral meniscus using magnetic resonance imaging.

PURPOSE: The characteristic two-dimensional bone morphology in patients with a discoid lateral meniscus (DLM) has been described. However, the associated three-dimensional imaging findings have not been characterized. This study was performed to identify differences in the knee bone morphology between juvenile patients with a DLM and those with a normal meniscus using magnetic resonance (MR) imaging. METHODS: The DLM group comprised 33 consecutive juvenile patients (33 knees) with a complete DLM, and the control group comprised 24 juvenile patients (24 knees) with normal menisci on the basis of MR imaging findings. Each MR image was evaluated to determine the anterior obliquity of the lateral tibial plateau (AOLTP), posterior obliquity of the lateral tibial plateau (POLTP), lowest point of the lateral femoral condyle (LPLFC), posterior lateral condylar angle (PLCA) and posterior medial condylar angle (PMCA). Statistical analyses were performed to determine the differences between the two groups. RESULTS: The POLTP was significantly larger, the LPLFC was significantly more lateral, and the PLCA was significantly smaller in the DLM group than in the control group (p < 0.001, p < 0.001 and p < 0.001 respectively). However, there was no statistically significant difference in the AOLTP or PMCA between the two groups (p = 0.429 and p = 0.148, respectively). CONCLUSIONS: Hypoplasia of the lateral femoral condyle and posterior lateral tibial plateau is recognized in juvenile patients with a complete DLM on coronal and axial MRI images. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Discoid lateral meniscus: current concepts.

The discoid meniscus is a congenital morphological abnormality encountered far more commonly on the lateral than the medial side. The discoid lateral meniscus (DLM) is more prevalent in Asia with an incidence of 10%-13%, than in the Western world with an incidence of 3%-5%. DLM can be bilateral in more than 80% cases. Due to its abnormal shape and size, the discoid meniscus is prone to tearing and has an impact on gait mechanics. The discoid meniscus has deranged collagen arrangement and vascularity which can have implications for healing after a repair. Patients with a DLM may or may not be symptomatic with mechanical complaints of locking, clicking, snapping or pain. Symptoms often arise due to a tear in the body of the meniscus or a peripheral detachment. Asymptomatic patients usually do not require any treatment, while symptomatic patients who do not have locking are managed conservatively. When a peripheral detachment is present, it must be stabilised while preserving the meniscus rim to allow transmission of hoop stresses. Rehabilitation after surgery is highly individualised and return to sports is possible after more than 4 months in those undergoing a repair. The functional outcomes and onset of radiographic arthritis after saucerisation and repairing a discoid meniscus are better in the long term, compared with a subtotal meniscectomy. However, there is no compelling evidence currently favouring a repair as results deteriorate with increasing follow-up. Poor prognosis is reported in patients undergoing a total meniscectomy, a higher age at presentation and valgus malalignment.

Predictive factors for developing osteochondritis dissecans after surgery for discoid lateral meniscus are younger age and shorter meniscal width.

PURPOSE: This study aimed to identify the predictive factors for postoperative osteochondritis dissecans (OCD) in juvenile and adolescent knees with discoid lateral meniscus (DLM). METHODS: In total, 242 patients with symptomatic DLM who underwent surgery were identified. Inclusion criteria were set as follows: (1) age ≤ 17 years with an open growth plate, (2) follow-up magnetic resonance imaging, and (3) absence of preoperative OCD. Consequently, 52 patients were retrospectively investigated. Average age during surgery, body mass index (BMI), and follow-up duration were 12 years [95% confidence interval (CI) 11-13], 19.2 kg/m2 (95% CI 18.4-20.1), and 27.3 months (95% CI 20.9-33.7), respectively. Age, sex, sports activities, BMI, symptomatic OCD in other joints, postoperative rehabilitation, preoperative shift of DLM by Ahn's classification, surgical procedures (saucerization alone or with stabilization, and subtotal meniscectomy), and postoperative meniscal width were analyzed as possible predictive factors. RESULTS: Postoperatively, 42 patients without OCD and 10 with OCD were observed. In univariate analysis, younger age [odds ratio (OR) 1.5; p = 0.003], subtotal meniscectomy (OR 6.3; p = 0.027), and shorter meniscal width (OR 2.7; p = 0.005) were predictive factors for postoperative OCD. Multivariate analysis demonstrated that younger age (OR 1.6; p = 0.009) and shorter meniscal width (OR 1.5; p = 0.003) were predictive factors. CONCLUSIONS: To prevent postoperative OCD after DLM surgeries, achieving stabilization with adequate meniscal width is necessary for juvenile knees. LEVEL OF EVIDENCE: III.

Meniscoplasty leads to good mid-term to long-term outcomes for children and adolescents with discoid lateral meniscus.

PURPOSE: To date, there have been limited studies reporting the mid- to long-term outcomes of meniscoplasties for discoid lateral meniscus. The current study aims to evaluate the mid- to long-term outcomes of arthroscopic meniscoplasty for discoid lateral meniscus in children and adolescents. METHODS: In the study, all patients under the age of 21 years who had undergone arthroscopic meniscoplasty with or without meniscal repair or partial meniscectomy for symptomatic lateral discoid meniscus were included. All patients were then followed up for a minimum of 5 years (median 84 months; range 68-110 months). The Lysholm scores and Ikeuchi scores were collected pre-operatively and at final follow-up and were compared. RESULTS: A total of 24 knees were included in the study. The median duration of follow-up was 84.0 months (range 68-110 months). The Lysholm score improved from 53 (range 11-95) pre-operatively to 100.0 (range 60-100) at final follow-up (p < 0.001). Based on the Ikeuchi score pre-operatively, 15 knees were rated as poor (62.5%), 7 knees were rated as fair (29.2%), and 2 knees were rated as good (8.4%). The Ikeuchi score improved significantly at the final follow-up, such that 1 knee was rated as good (4.2%) and 23 knees were rated as excellent (95.8%) (p < 0.001). When analysing the effect of concomitant meniscal repair or partial meniscectomy on the outcomes at final follow-up, there was no apparent difference in the improvement in Lysholm score or Ikeuchi score when comparing between patients who had meniscoplasty alone and patients who had concomitant meniscal repair, as well as when comparing between patients who had meniscoplasty alone and patients who had concomitant partial meniscectomy. CONCLUSION: Meniscoplasty leads to good mid-term to long-term outcomes for children and adolescents with discoid lateral meniscus. Concomitant procedures such as meniscal repair or partial meniscectomy do not improve or worsen the mid- to long-term outcomes in these patients. LEVEL OF EVIDENCE: IV.

A predictive model with radiographic signs can be a useful supplementary diagnostic tool for complete discoid lateral meniscus in adults.

PURPOSE: To investigate the diagnostic accuracy of radiographic signs for complete discoid lateral meniscus and whether a predictive model combining the radiographic signs can improve its diagnostic accuracy in adults. METHODS: A total of adult 119 knees with complete discoid lateral meniscus confirmed by arthroscopy and 119 age- and sex-matched knees with normal meniscus were included. The radiographic signs of lateral joint space, fibular head height, lateral tibial spine height, lateral tibial plateau obliquity, lateral femoral condyle squaring, lateral tibial plateau cupping, lateral femoral condyle notching, and the condylar cut-off sign were evaluated. The receiver-operating characteristic (ROC) curves and area under the curve (AUC) were evaluated for best accuracy. A prediction model was developed by multivariable regression with generalized estimating models, and was validated using data from 111 knees of children with complete discoid lateral meniscus and 111 normal controls. RESULTS: The fibular head height, lateral joint space, lateral tibial plateau obliquity, and the condylar cut-off sign were significantly different between the complete discoid lateral meniscus and the normal groups (p < 0.05). Among the four radiographic signs, the fibular head height showed the highest accuracy with 78.9% sensitivity and 57.3% specificity. The prediction models developed by logistic regression showed significantly improved accuracy for complete discoid lateral meniscus compared to the fibular head height (sensitivity: 69.8%, specificity: 82.9%, p = 0.001). For validation, the AUC of children seemed to be larger than that of adults, which indicated that the prediction models could be applied for children to detect complete discoid lateral meniscus. CONCLUSION: Among several radiographic signs, the fibular head height can be used as a screening tool for complete discoid lateral meniscus. The prediction models combined with lateral joint space, fibular head height, lateral tibial plateau obliquity, and/or the condylar cut-off sign yielded a much higher diagnostic value than each radiographic sign. Therefore, fibular head height and prediction models combined with radiographic signs can provide improved diagnostic value for complete discoid lateral meniscus. LEVEL OF EVIDENCE: III.

Saucerization and Repair of Discoid Lateral Menisci With Peripheral Rim Instability: Intermediate-term Outcomes in Children and Adolescents.

BACKGROUND: Historically, total meniscectomy was recommended as the treatment for a symptomatic discoid meniscus. Improved meniscal repair techniques and inferior long-term outcomes associated with meniscectomy have resulted in a trend toward meniscal preservation, with saucerization and repair of meniscocapsular tears. Reoperation rates after treatment of torn discoid menisci vary, with some series reporting high rates of reinjury and reoperation. The purpose of this study is to describe the intermediate-term outcomes of pediatric patients treated with saucerization and meniscocapsular repair of discoid lateral menisci with peripheral rim instability. METHODS: A single-institution retrospective review was performed of consecutive patients less than 18 years of age treated with saucerization and repair for a meniscocapsular tear of a discoid lateral meniscus from 2013 to 2017. All patients had a minimum 24-month follow-up. A chart review was performed to describe tear location and repair type. The primary outcomes were revision meniscus surgery and Pedi-International Knee Documentation Committee and Tegner activity scores obtained at the final follow-up. RESULTS: In total, 32 knees in 30 patients, including 15 males and 15 females with a mean age of 12 years (range, 5 to 17 y), were included. Tear patterns included anterior meniscocapsular (14 knees), posterior meniscocapsular (16 knees), and both anterior and posterior meniscocapsular (2 knees). Arthroscopic saucerization and meniscocapsular repair were performed in all knees. Repair types were outside-in (10 knees), inside-out (8 knees), all-inside (8 knees), and hybrid (6 knees). The mean follow-up was 54 months (range, 30 to 86 mo). Three knees (9%) underwent revision meniscus surgery, including 2 all-inside repairs and 1 partial meniscectomy. At the final follow-up, mean International Knee Documentation Committee score was 96 (range, 82 to 100). A total of 89% of patients reported returning to the same or higher level of activity following surgery. CONCLUSIONS: Saucerization of discoid lateral menisci with repair of meniscocapsular tears is associated with low rates of revision surgery and good intermediate-term outcomes. LEVEL OF EVIDENCE: Level IV.

Rare Variant Double-Layered Lateral Meniscus Detected During Arthroscopy in a Young Gymnast After a Hyperextension Knee Injury: A Case Report.

CASE: A 15-year-old high-level gymnast sustained a hyperextension knee injury and was diagnosed with a lateral meniscus tear on advanced imaging. During arthroscopy, a redundant meniscus was encountered overlying an otherwise normal, intact lateral meniscus, consistent with a double-layer lateral meniscus. The redundant meniscus was resected, and the patient was able to return to gymnastics at her previous high level of competition. CONCLUSIONS: Abnormalities of the lateral meniscus may be poorly characterized or undetected on preoperative imaging studies. When the decision is made to proceed with surgery, a vigilant diagnostic arthroscopic examination can facilitate the detection and treatment of unanticipated pathology.

Factors Related to Postoperative Osteochondritis Dissecans of the Lateral Femoral Condyle After Meniscal Surgery in Juvenile Patients With a Discoid Lateral Meniscus.

PURPOSE: The purpose was to assess the incidence of postoperative osteochondritis dissecans (OCD) and the related epidemiologic factors following meniscal surgery for juvenile discoid lateral meniscus (DLM). METHODS: The study was a retrospective review of 103 knees in 89 patients with a mean age of 12.1 years who underwent arthroscopic meniscal surgery for DLM. Mean follow-up was 4.2 years. The surgical procedures were either saucerization, saucerization with repair or subtotal meniscectomy, depending on the type of DLM tear. Postoperative OCD lesions were identified radiographically. Age, sex, weight, Lysholm score, Tegner activity scale, exercise frequency, and surgical procedure were compared between the postoperative OCD diagnosis group and non-OCD control group. RESULTS: Postoperative OCD was diagnosed in 8/103 (7.8%) knees following DLM surgery. The incidence of postoperative OCD was significantly greater for patients age less than 10 years old, and male sex, low weight, Lysholm score, Tegner activity scale preinjury and after returning to sports, and exercise frequency per week on univariate analyses. On multivariate analyses, postoperative OCD occurred more commonly with subtotal meniscectomy than with saucerization or saucerization with repair, and in patients less than 11 years of age. Receiver operating characteristic curve analysis revealed a cutoff value of age at surgery of 10 years. CONCLUSIONS: Subtotal meniscectomy and patients younger than 10 years at the time of surgery are at greater risk for postoperative OCD. To decrease this risk, if possible, we recommend performing saucerization or saucerization with repair in patients undergoing surgery for DLM. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Isolated meniscus extrusion associated with meniscotibial ligament abnormality.

PURPOSE: The purpose of this study was to describe meniscus extrusion, present imaging characteristics, and provide clinical correlations for patients with isolated meniscus extrusion. METHODS: Of the 3244 MRI reports identified as having meniscus extrusion, 20 patients were identified to have isolated meniscus extrusion (0.62%). Patients with moderate to severe chondromalacia, meniscus tears, intra-articular fractures, tumours, and ligament tears were excluded. Radiographs were reviewed and graded using Kellgren-Lawrence (K-L) scores. MRI's were reviewed for the extent of extrusion and whether or not the meniscotibial ligament was intact. Clinical presentation and management were recorded. RESULTS: The study population consisted of 12 females and 8 males with a mean age of 40.5, diagnosed with meniscus extrusion and minimal concomitant knee pathology. 68% of patients were considered symptomatic as their knee pain correlated with the side of their meniscus extrusion and no other reason for pain was identified. The mean amount of meniscus extrusion was 2.5 mm (SD ± 1.1 mm) with 45% (9 of 20) having 3 + mm of extrusion. Meniscotibial ligament abnormality was identified in 65% of cases (13 of 20). Patients with 3 + mm of meniscus extrusion were much more likely to have associated meniscotibial ligament abnormality (100%, 9 of 9) compared to those with < 3 mm of extrusion (36%, 4 of 11) (RR 2.75, p = 0.048). The mean K-L grade obtained at the initial visit was 0.9 (95% CI 0.7-1.4) and the mean K-L grade obtained on final follow-up was 1.3 (95% CI 0.8-2.8) (n.s.) at a mean of 44.7 months. No correlation was found between K-L grade, gender, age, acute injury, and BMI in relation to meniscotibial ligament abnormality or amount of meniscal extrusion. CONCLUSIONS: Meniscus extrusion often occurs in the presence of significant knee pathology, predominantly with meniscus tears or osteoarthritis. Isolated meniscus extrusion is a rare occurrence that may present clinically with knee pain, commonly to the side in which the extrusion occurs. In patients with three or more millimetres of meniscus extrusion, an intact meniscus and minimal knee pathology, meniscotibial ligament abnormality is likely. This may provide an opportunity to treat the meniscotibial ligament abnormality with meniscus centralisation technique and decrease the amount of meniscus extrusion.

Prediction of the Peripheral Rim Instability of the Discoid Lateral Meniscus in Children by Using Preoperative Clinicoradiological Factors.

BACKGROUND: The discoid lateral meniscus (DLM) in children often presents peripheral rim instability (PRI) and is susceptible to tear or subluxation, which manifests symptoms and leads to a poor prognosis. We aimed to investigate the association between preoperative clinical and MRI findings and the intraoperative findings of PRI. METHODS: Children and adolescents aged younger than 16 years who underwent surgical treatment for DLM were retrospectively reviewed. Cases of bucket-handle tear were not included because they would confound the stability of the peripheral rim. Total 60 knees from 47 children were included. PRI was additionally subdivided based on the location, such as anterior, middle, and posterior, during the investigation. RESULTS: In multivariate analyses, both central (inward) (P=0.004) and external (outward) (P=0.029) displacement of lateral meniscal margin, and peripheral tear of the anterior body (P=0.022) were significant predictors of PRI, regardless of the location. The predictive factors for PRI based on each location were female gender (P=0.004), subjective symptom of clicking sound (P=0.023), and central displacement of the anterior meniscal margin (P=0.034) for anterior PRI; flexion contracture >10 degrees (P=0.017) and peripheral tear of the middle body (P<0.001) for middle PRI; and central displacement of the posterior meniscal margin (P=0.036) and peripheral tears of the anterior (P=0.029) and middle bodies (P=0.047) for posterior PRI. CONCLUSIONS: We evaluated the preoperative clinical and MRI findings that predict PRI of pediatric DLM. Displacements of the DLM, not only centrally (inward) but also externally (outward), seem to be significant predictive factors for PRI. Furthermore, some clinical findings were associated with PRI, even predicting the locations. Although the actual surgical procedure should be determined by meticulous probing during arthroscopy, preoperative prediction of the presence and location of PRI would help decrease the risk of oversight during surgery. LEVEL OF EVIDENCE: Level III-Diagnostic Study.

Meniscal allograft transplantation in the paediatric population: early referral is justified.

PURPOSE: The need for meniscal allograft transplantation (MAT) in children is rare, and as a result, there is a paucity of evidence detailing survivorship and clinical outcome. MAT has been shown to significantly reduce pain and improve function in the adult population. The aim of this study was to document the outcomes of a single surgeon case series of MAT in the paediatric population. METHODS: Analysis of a prospective meniscal allograft transplantation (MAT) group database of 280 patients was performed. Twenty-three patients met the inclusion criteria-undergoing MAT aged 18 years or younger. RESULTS: Fourteen were female and nine were male with median age of 17 (range 8-18). Thirteen (57%) were right knee and nineteen (83%) were lateral. Additional procedures included high tibial osteotomy, anterior cruciate ligament reconstruction, and microfracture procedures. The median follow-up was 3.8 years (range of 0.2 to 7.8 years). There have been no cases of graft failure. All patients demonstrated improvement in all the modalities of the KOOS outcome scores. At 5 years, the Lysholm score had improved from 57.9 to 87.6 (SD 12.1), Tegner activity score had improved from 2 to 5 (range 4-7) and IKDC score had improved from 40.6 to 78.6 (SD 15.8). Four patients required secondary surgical intervention. No patients developed a superficial or deep infection. CONCLUSION: Meniscal allograft transplantation in children is founded on the successful results of MAT in the adult population. We have demonstrated in this series that MAT can improve function and reduce pain in the paediatric population, and is, therefore, a viable treatment option for the management of the symptomatic paediatric meniscal-deficient knee. Early referral should be considered in the patients with post-meniscectomy syndrome, pain on weight bearing with a history of previous menisectomy. LEVEL OF EVIDENCE: IV.

Management of Long-Term Complications in the Setting of Lateral Meniscal Deficiency After Saucerization of a Discoid Lateral Meniscus in an Adolescent Patient: A Case Report and Review of the Literature.

CASE: A 14-year-old adolescent with bilateral discoid menisci who had previously undergone discoid meniscal saucerization presented with pain and mechanical knee symptoms bilaterally. She had a torn left discoid lateral meniscus, a right lateral meniscal deficiency with an associated osteochondral defect, and valgus collapse of the right femur. She underwent successful repair of the left discoid meniscus as well as a femoral osteotomy, a meniscal transplant, and an osteochondral allograft transplantation in the right knee. CONCLUSION: New treatment paradigms following initial interventions for discoid menisci are discussed. Patients may benefit from longer follow-up after discoid meniscal surgery, and providers should consider joint-preserving techniques early in the setting of meniscal deficiency.

Bilateral Hypoplasia of Both Medial and Lateral Menisci Partially Fused With the Cartilage Surface of the Tibial Plateau.

Hypoplastic meniscus is an extremely rare abnormality. The authors present the first case of meniscal hypoplasia with a partial fusion of meniscus and tibial cartilage. A 22-year-old man underwent surgery for a chronic patellar dislocation. Preoperative magnetic resonance imaging and arthroscopy incidentally revealed hypoplasia of both medial and lateral menisci. Moreover, the posterior horn of the medial meniscus and middle body of the lateral meniscus were fused with the cartilage surface of the tibia. Magnetic resonance imaging of the contralateral knee showed similar meniscal anomalies. This case presents an interesting and extremely rare abnormality of the meniscus. [Orthopedics. 2018; 41(6):e884-e887.].

Arthroscopic treatment for symptomatic lateral discoid meniscus: The effects of different ages, groups and procedures on surgical outcomes.

BACKGROUND: There is a paucity of literature regarding the results of arthroscopic saucerization, with or without stabilization, for lateral discoid meniscus (LDM) in children, and differences in clinical outcomes between adults and children. The purpose of this study was to compare the clinical outcomes following arthroscopic treatment of symptomatic LDM in children versus adults. Secondly, outcomes of different surgical procedures (saucerization only and saucerization with repair or centralization) were also compared. METHODS: Fifty-two consecutive patients with LDM were evaluated and divided into two groups. Group 1 had 16 patients (18 knees; nine males, seven females) aged <13 years; Group 2 had 36 patients (38 knees; 19 males, 17 females) aged ≥13 years. All patients were arthroscopically treated with saucerization only, or saucerization with repair or centralization for LDM. They had a mean follow-up of 30 months (range 24-72). Clinical outcomes were compared preoperatively and at final follow-up (minimum two years) after surgery using patient-reported outcome scores, International Knee Documentation Committee (IKDC) scores, and Lysholm scores. Radiographic evaluation was also performed for degenerative changes using Kellgren-Lawrence classification. RESULTS: The IKDC scores at final follow-up in Group 1 demonstrated better clinical outcomes when compared with those in Group 2 (91.1 ±â€¯9.49 vs. 73.7 ±â€¯16.4, P = 0.001). No significant intergroup difference was noted at the follow-up for radiographic osteoarthritic grade according to Kellgren-Lawrence classification. Similarly, no differences were found at final follow-up between saucerization only and saucerization with repair or centralization. There were no significant differences in IKDC score of repair and centralization at final follow-up. CONCLUSIONS: Clinical outcomes in children aged <13 years was significantly better than those aged ≥13 years. Arthroscopic saucerization only or saucerization with repair or centralization for discoid meniscus was effective in improving knee function and preventing early degenerative changes during short-term follow-up periods.

Does discoid lateral meniscus have inborn peripheral rim instability? Comparison between intact discoid lateral meniscus and normal lateral meniscus.

INTRODUCTION: Little is known about peripheral rim instability (PRI) of adult discoid lateral meniscus (DLM). We compared PRI of the intact DLM (iDLM) to those of intact normal lateral meniscus (LM) in adult patients and also investigated whether there was any association between PRI and DLM tears. MATERIALS AND METHODS: We investigated PRI in 17 DLMs and 60 normal LMs without tears during arthroscopic surgery for medial compartmental pathologies between June 2012 and October 2015. We also investigate PRI of torn DLM (tDLM) excluding peripheral tear to compare the PRI between intact and torn DLM. Stability parameters were measured using a probing hook and arthroscopic ruler at the anterior, middle, and posterior parts of the peripheral rim of the menisci: translating the anterior horn (AH) and mid-body (MB) and lifting the posterior horn (PH). RESULTS: AH and PH instabilities were greater in the iDLM group than in the iLM group (2.2 ± 1.4 vs. 0.9 ± 1.4 mm, p = 0.006 and 3.4 ± 1.7 vs. 1.7 ± 1.2 mm, p = 0.004, respectively). However, there was no significant difference in MB instability between two groups. In addition, no significant difference was observed in all the parameters between the iDLM and tDLM groups. CONCLUSION: Both iDLM and tDLM had greater PRI of the AH and PH than the iLM in adult patients. Thus, the DLM is prone to tear and careful inspection is needed not to overlook PRI of a DLM even if the peripheral attachment is intact. LEVEL OF EVIDENCE: Level 3, comparative study of anatomical instability of living subjects.

Regeneration of lateral discoid meniscus after arthroscopic partial meniscectomy in an adult patient.

Arthroscopic partial resection is indicated for patients who have symptomatic discoid meniscus with overall satisfactory clinical outcomes. Reports regarding regeneration of discoid meniscus after arthroscopic surgery are limited. There are only two reports for children in the literature. To the authors' knowledge, the present study is the first report in the literature to report regeneration of discoid lateral meniscus after arthroscopic partial meniscectomy in an adult patient. The diagnosis was confirmed by both magnetic resonance imaging and arthroscopy. Surgeons should be aware that regeneration of discoid meniscus can occur in adult as well as pediatric patients.Level of evidence V.

Prediction Models to Improve the Diagnostic Value of Plain Radiographs in Children With Complete Discoid Lateral Meniscus.

PURPOSE: To develop prediction models to improve the diagnostic utility of plain radiographs for the diagnosis of complete discoid lateral meniscus by combining previously reported radiographic findings. METHODS: Patients ages 5 to 16 years with complete discoid lateral meniscus confirmed by arthroscopy or magnetic resonance imaging were included. Patients with insufficient radiographs were excluded. Normal control subjects were randomly sampled by age and sex matching. Subjects were divided into 2 groups considering skeletal maturation (5-9 and 10-16 years). Radiographic variables included were lateral joint space, height of the fibular head, height of the lateral tibial spine, obliquity and cupping of the lateral tibial plateau, condylar cutoff sign, and squaring and notching of the lateral femoral condyle. Prediction models were developed by regression analyses. The cutoff value (COV) for best accuracy was determined with its sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). RESULTS: A total of 162 knees (126 patients) with complete discoid lateral meniscus and 151 age- and sex-matched knees (151 subjects) with normal meniscus were included. In subjects 5 to 9 years old, the prediction model was risk score = [-20.08 * height of the fibular head/femoral interepicondylar distance (FIED)] + [-42.26 * height of the lateral tibial spine/FIED]. The COV of -8.47 showed the best accuracy (74.4%), with sensitivity of 85.9%; specificity, 60.4%; PPV, 72.4%; and NPV, 78.0%. In subjects 10 to 16 years old, the prediction model was risk score = [77.04 * lateral joint space/FIED] + [-34.55 * height of the fibular head/FIED] + [-56.58 * height of the lateral tibial spine/FIED] + [-16.44 * condylar cutoff sign]. The COV of -18.03 showed the best accuracy (85.4%), with sensitivity of 79.6%; specificity, 90.4%; PPV, 87.6%; and NPV, 83.9%. CONCLUSIONS: The prediction models combining the plain radiographic findings showed higher diagnostic values than the diagnostic values of the individual radiographic findings. The results of this study provide improved diagnostic utility of plain radiography for the detection of completed discoid lateral meniscus in children. LEVEL OF EVIDENCE: Level III, diagnostic study.

High tibial osteotomy accelerates lateral compartment osteoarthritis in discoid meniscus patients.

PURPOSE: The valgus high tibial osteotomy (HTO) in patients with medial osteoarthritis and discoid lateral meniscus can result in increased load on the lateral compartment and hence a higher chances of tear. This may accelerate the progression of osteoarthritis on lateral compartment. We, therefore, carried out the case control study with a hypothesis that an HTO would accelerate the progression of osteoarthritis (OA) on lateral compartment in patients with complete discoid meniscus. METHODS: The records of all patients with open wedge HTO from 2008 to 2012 were evaluated for complete lateral discoid meniscus. The patient who had a valgus HTO with or without partial meniscectomy for medial compartmental OA was included for this study. Cases to control were chosen to match age, body mass index (BMI), pre-operative osteoarthritis grade, and deformity angles in ratio 1:2. Patient's records were studied for demographic data, clinical examination records, and pre-operative knee functional scores and radiological scores and were compared with post-operative data. RESULTS: Thirty-six patients out of 674 patients, who underwent an HTO, consisted of discoid meniscus group. 72 patients were chosen as control group. Four patients showed progression of OA on the lateral compartment in discoid group compared to none in control group. Although control groups showed a little bit better functional outcomes, there were no statistical differences between two groups (n.s.). CONCLUSION: The high tibial osteotomy could result in accelerated lateral compartment osteoarthritis in patients with complete discoid meniscus, and the procedure should be used with caution in such patients. LEVEL OF EVIDENCE: IV.