Arthroscopic Repair of Extruded Meniscus Tears: Impact on Symptom Relief and Functional Improvement – A 2-Year Follow-Up Study

Introduction

The knee joint’s physiological function relies on the meniscus, a crucial anatomical component. The primary role of load bearing is to offer shock absorption and maintain joint stability. Regrettably, meniscus tears and extrusions impair the fundamental functioning of the meniscus [1]. Tearing or extrusion of the menisci can lead to alterations in knee mechanics, potentially triggering or expediting the progression of osteoarthritis [2].

Meniscus extrusion (ME) refers to the movement of the meniscus away from the margin of the knee joint [3]. During extrusion, the meniscus deviates from its original position between the tibiofemoral joint and protrudes into the groove, resulting in reduction of its mechanical functionality [2]. Physiological extrusion can be observed in both the medial and lateral menisci. Various patient- and joint-related characteristics influence the extent of extrusion. Higher levels of ME are associated with increasing age, body mass index (BMI), osteoarthritis, and meniscus tears [4,5]. Knee discomfort may be caused as a secondary effect of medial meniscus protrusion. Once the meniscus is displaced, the femoral condyle and tibial plateau make direct contact, causing degeneration of cartilage in the tibiofemoral joint and the progression of arthrosis [6].

Magnetic resonance imaging (MRI) is often regarded as the most reliable method for assessing ME [7]. Medial meniscus extrusion that extends more than 3 mm beyond the margin of the tibial plateau at the level of the medial collateral ligament on MRI has been linked to a notable increase in articular cartilage loss and the production of osteophytes [8–10].

The objective of extruded meniscus treatment is to minimize extrusion while also addressing the underlying cause of extrusion [11]. Allaire et al showed that a knee that had undergone knee meniscectomy following a meniscus root tear had extruded meniscus formations [12]. While modern surgical techniques can effectively fix the meniscus root at its anatomical attachment location, non-anatomical repair methods are unable to restore the contact area or average contact pressures of a healthy knee or anatomically repaired meniscus [9,13]. Recent biomechanical research indicates that employing peripheral stabilizing sutures can enhance the contact mechanics of the knee and decrease extrusion levels [14].

The aim of extruded meniscus treatment is to minimize extrusion and apply the treatment method appropriate to the tear pattern. Non-anatomical repair methods that do not provide meniscus centralization may not improve contact mechanics and reduce extrusion levels. Meniscus extrusion can result from a tear in the root or from various types of tears in the meniscus, such as radial, longitudinal, horizontal, oblique, or complex tears, without involving the root [15]. The purpose of this study was to determine if radiographic extrusion drops below 3 mm following arthroscopic repair of meniscus tears that are extruded more than 3 mm and do not involve a root tear, as there is currently no existing literature on this topic.

This retrospective study from a single center in Turkey aimed to evaluate 2-year outcomes of 21 patients undergoing knee arthroscopic repair of extruded meniscus tears without root tears.

Material and Methods

ETHICS APPROVAL AND INFORMED CONSENT:

Approval for the study was granted by the Local Ethics Committee, and informed consent was obtained from all the patients (2023/1292). The study retrospectively examined patients who underwent knee arthroscopy from January 2011 to January 2022. The data were obtained from the data system of Ankara Training and Research Hospital. Patients outside of this time range were excluded from the study, while all other patients were assessed. We enrolled patients who were assessed and had extruded meniscus tears without arthroscopically-treated root tears and had complete data.

STUDY DESIGN AND DATA COLLECTION:

Our study included male and female patients aged 18–55 years who had preoperative and postoperative MRI data. We specifically focused on patients with extruded meniscus tears larger than 3 mm but without root tears. Additionally, we only included patients who received arthroscopic meniscus repair without meniscectomy. Exclusion criteria were: age under 18 years or older than 55 years, tdid not have preoperative or postoperative MRI results, with meniscus tears of 3 mm or less, with meniscus root tears, underwent partial or total meniscectomy, did not undergo meniscus repair, had revision meniscus surgery, and those with knee-related issues. We also excluded patients with residual effects from fractures (Figure 1).

The study retrospectively recorded demographic information of the patients from the hospital data system. The patients’ radiographs, which were taken in the anteroposterior and lateral positions with 30 degrees of flexion while standing with weight bearing, were assessed using the Kellgren-Lawrence (K-L) scale. The radiographs were categorized into 5 distinct groups ranging from stages 0 to 4. The study analyzed the degree of extrusion of the meniscus and the specific type of tear in the meniscus by examining the preoperative and postoperative knee MRIs of the patients included in the study. Meniscal extrusion is defined as meniscal tissue extending 3 mm or more beyond the edge of the tibial plateau, as measured by MRI.

One of the authors conducted radiological measurements. To prevent inter-rater mistakes, an additional author conducted measurements of all radiological parameters as well. To evaluate consistency between different raters, the measurements were conducted again 6 weeks later by the same authors. Reliability was assessed by calculating intraclass coefficient correlations (ICCs). The intraobserver reliability coefficient for MRI meniscal extrusion measures was determined to be 0.847, while the interobserver reliability coefficient was found to be 0.812.

ORTHOPEDIC SURGICAL METHODS:

While the patient was in supine position and the knee was flexed, access to the knee was made through the anterolateral and anteromedial portals. Meniscus tear was determined arthroscopically. The torn ends of the meniscus were freshened with a shaver and meniscus rasp. The meniscus tear was repaired using the all-inside and outside-in method. During arthroscopy, the size and location of the meniscus tear, the method used, and the number of stitches were recorded.

CLINICAL FOLLOW-UP:

Prior to surgery, the patients’ functional state was assessed using the non-disease-specific Lysholm knee scoring scale and the IKDC (The International Knee Documentation Committee) questionnaire, which were administered in person. The subjective IKDC questionnaire score, a score of 95–100 was graded excellent, 90–94 was excellent, 80–89 was good, 70–79 was fair, and less than 70 was poor, according to IKDC subjective classification. The Lysholm score consists of 8 items: limping, climbing stairs, squatting, locking, instability, pain, swelling, and use of support.

The patients were administered the preoperative Lysholm knee grading scale and IKDC questionnaire once again during their 12-month postoperative follow-up, and the results were documented. Therefore, the scores before and after the operation were compared.

STATISTICAL ANALYSIS:

The data analysis was conducted using SPSS 20 software. The normality of the data was assessed using the Kolmogorov-Simirnov test. The categorical data were analyzed using Fischer’s exact test, while the quantitative data was analyzed using either an unpaired t test or one-way ANOVA, depending on whether the data followed a normal distribution or not. A significance level of P<0.05 was deemed acceptable to establish the presence of a statistically significant difference.

Results

DEMOGRAPHIC CHARACTERISTICS AND CLINICAL PRESENTATION OF PATIENTS:

Of the individuals that took part in the study, 66.7% (n=14) were male and 33.3% (n=7) were female. The average age of the participants was 34.86 ± 2.66 (range, 19–55) years. The right knee of 13 patients (61.9%) included in the study and the left knee of 8 patients (38.1%) were operated on due to extruded meniscus tear (Table 1).

RADIOGRAPHIC OUTCOMES:

While the average preoperative extrusion amount of the patients was 4.01, the postoperative average extrusion amount was 3.30 (Table 2). Following the repair procedure, extrusion levels were observed to decrease significantly (P<0.001).

In the control MRI taken after the surgery, 61.9% (n=13) of the patients showed meniscus extrusion of less than 3 mm, which is the critical value. It was observed that adequate meniscus centralization could not be achieved after surgery in 38.1% of the patients (n=8). No significant relationship was found between the type of meniscus tear and the inability to achieve adequate centralization (P=0.904). There was no statistically significant relationship between the type of repair and failure to provide adequate centralization (P=0.063). No statistically significant relationship was found between the time elapsed after the operation and the inability to achieve adequate centralization (P=0.804).

The patients included in the study were evaluated according to the Kellgren-Lawrence (K-L) scale during the preoperative and final postoperative follow-ups, and were divided into 5 different groups stages 0–4. The patients were then divided into 5 groups based on their stage of knee degeneration, ranging from stage 0 to stage 4. Table 3 shows that 12 patients were assessed as stage 0, 6 patients as stage 1, and 3 patients as stage 2, based on the Kellgren-Lawrence (K-L) scale. Based on the radiographs obtained during the latest follow-up, it was observed that 2 patients advanced from stage 0 to stage 1, 2 patients advanced from stage 1 to stage 2, and 1 patient advanced from stage 2 to stage 3.

FUNCTIONAL OUTCOMES:

Patients were evaluated with the Lysholm score before and after the repair procedure. The average Lysholm score of the patients, whose preoperative Lysholm score was 61, was 74.3 after the surgery. Patients were evaluated with the IKDC score before and after the repair procedure. The mean IKDC score of the patients, whose preoperative IKDC score was 59.76, was 72.45 after the surgery. After the repair, there was a clear increase in the evaluation scores of both patient evaluation forms (P<0.001) (Tables 4, 5).

Discussion

LIMITATIONS:

This study has certain limitations. First, it was retrospective. Second, the number of patients was small. Third, the repair method applied to patients may be a combination of inside-out or outside-in methods. Furthermore, since our study had a small sample size, it would be more precise to compare our results with studies that have been conducted using bigger samples. However, extruded meniscus tear without root tear is a very rare condition and the primary pathology is often overlooked. This study emphasizes that more attention should be paid to extruded meniscus tears without root tears.

Conclusions

Arthroscopic treatment of extruded meniscus tears can enhance functional status and increase patients’ functional status. Nevertheless, there was no successful meniscus centralization in patients whose osteoarthritis level progressed from stage 1 to stage 2. This study discovered that radiological extrusion did not diminish beyond the critical threshold of 3 mm, which is associated with the development of osteoarthritis. This highlights the necessity of taking these elements into account when devising a treatment plan. Our study’s results align with previous related studies. While arthroscopic repair effectively reduces extrusion without employing meniscus centralization techniques like tibial fixation, it cannot achieve an extrusion level lower than the desired optimal amount.