Extrusion of the anterior segment of the medial meniscus extrusion initiates knee osteoarthritis: evaluation using magnetic resonance imaging.

PURPOSE: Meniscus extrusion contributes to the progression of knee osteoarthritis (OA). It is not clear which site of the medial meniscus (MM) extrusion (MME) is greatest. Moreover, the relationship between sites of MME and progression of OA has not yet been elucidated. The purpose of this study was to determine which sites of MME that showed the greatest extrusion and to investigate the relationship between the presence of MM tears and MME, the relationship between the progression of OA and MME. METHODS: A cohort of 111 patients were studied retrospectively. The OA grade was classified using the Kellgren-Lawrence (K-L) grade. MME was measured at 13 positions from the anterior to the posterior segment using magnetic resonance imaging (MRI) with slices perpendicular to the MM (radial MRI). The relationship between the K-L grade and the site of the MME was investigated. The patients were grouped as follows: The patients over 40-years-old were grouped as follows: patients with the K-L grade ≤1 and without a MM tear (Group En (early, no meniscus tear)); patients with the K-L grade ≤1 with a MM tear (Group Ep (early, positive meniscus tear)); patients with the K-L grade ≥2 and without a MM tear (Group An (advanced, no meniscal tear)); patients over-40 years-old with the K-L grade ≥2 and with a MM tear (Group Ap (advanced, positive meniscus tear)). And patients between 15 and 39-years-old with no abnormal findings on MRI were defined as control group (Group C). RESULTS: In the Groups En and Ep, MME was greatest in the anterior segment, and was greater in Group Ep than in Group En. In Groups Ap and Group C, extrusion was greatest in the middle segment. CONCLUSION: The results suggest that MME predominantly occurred in the anterior segment with increasing age, after that, MM extruded at the middle segment with progression of OA and MM tear.

Graft quality and clinical outcomes of intraoperative bone tunnel communication in anatomic double-bundle anterior cruciate ligament reconstruction.

BACKGROUND/OBJECTIVE: In anatomic double-bundle anterior cruciate ligament reconstruction, it is crucial to create two separate bone tunnels within the footprints of the anterior cruciate ligament at the femur and tibia. This can occasionally be difficult to accomplish and the adverse effects of bone tunnel communication are unclear. The purpose of this study was to examine the effects of intraoperative bone tunnel communication on graft quality and clinical outcome. METHODS: Fifty-two patients (52 knees) who underwent anatomic double-bundle anterior cruciate ligament reconstruction with hamstring tendons were included. The mean age of the patients was 30.7 years. Clinical assessments were performed 1 year after surgery. Bone tunnel communication was evaluated using computed tomography 10 days after surgery. Graft quality was evaluated using magnetic resonance imaging 6 months after surgery and the signal/noise quotient was calculated using the region of interest technique. RESULTS: Bone tunnel communication was observed in the femur of one knee (1.9%) and the tibias of 10 knees (30.8%). The knees with tibial bone communication were classified into Group C (N = 16), and the knees without tibial bone tunnel communication were classified into Group N (N = 36). No significant differences were observed between Groups C and N in terms of clinical outcome. The signal/noise quotient of the distal portion of the posterolateral graft in Group C was significantly higher than that of Group N. CONCLUSION: Bone tunnel communication in anatomic double-bundle anterior cruciate ligament reconstruction did not affect clinical outcome, but it did affect posterolateral graft quality. LEVEL OF EVIDENCE: Level 4, case series, therapeutic studies.

Sagittal view of the tibial attachment of the anterior cruciate ligament on magnetic resonance imaging and the relationship between anterior cruciate ligament size and the physical characteristics of patients.

BACKGROUND: It is necessary to create bone tunnels within the native footprint during anatomic anterior cruciate ligament (ACL) reconstruction. Predicting the size of the ACL preoperatively may be useful in order to determine the diameter of the bone tunnels preoperatively or during surgery. The tibial insertion site of the ACL includes a depressed area, the ACL fovea, which is generally observed in the sagittal view on magnetic resonance imaging (MRI). The purposes of this study were to measure the anteroposterior diameter of the ACL fovea in the sagittal view on MRI and to investigate its associations with the physical characteristics of patients. METHODS: One hundred patients (100 knees; 50 males and 50 females; mean age, 33 years) were included in this study. The anteroposterior diameter of the ACL fovea was measured in the sagittal view on MRI. The relationships between the diameter of the ACL fovea and physical characteristics including height, weight, and body mass index (BMI) were analyzed. RESULTS: The mean diameter of the ACL fovea was 16.1 mm in male patients and 14.3 mm in female patients, which were comparable to the previously reported values. There were significant positive correlations between the diameter of the ACL fovea and height and weight, but not BMI. The number of knees in which the diameter of the ACL fovea was <13 mm was 14 (14 %), and females were more likely to have ACL fovea diameter <13 mm. CONCLUSIONS: The study indicated that it is possible to predict the size of the ACL before surgery by measuring the diameter of the ACL fovea on MRI. Physical characteristics of patients correlated with the diameter of the ACL fovea. Especially in female patients, it is important to consider the size of the ACL preoperatively.

Radial displacement of the lateral meniscus before and after anterior cruciate ligament reconstruction.

INTRODUCTION: The purpose of this study was to investigate radial displacement (RD) of the lateral meniscus in patients with anterior cruciate ligament (ACL) injury by using magnetic resonance imaging both pre- and post-operatively. MATERIALS AND METHODS: This study included 59 knees that had undergone ACL reconstruction. The length that extruded from the lateral tibial plateau was measured in the coronal plane. RESULTS: Mean pre-operative RD was 1.8 mm, and mean post-operative RD was 2.4 mm (P < 0.001). Mean pre-operative RD was 1.6 mm in the group with lateral meniscus tears <1 cm, and 2.8 mm in the group with tears ≥1 cm (P = 0.033); the corresponding post-operative values were 2.1 and 3.2 mm (P = 0.038), respectively. Mean pre-operative RD was 1.9 mm in the longitudinal tear group and 2.4 mm in the radial tear, flap tear, or complex tear group (P = 0.21); the corresponding post-operative values were 2.2 and 4.1 mm (P = 0.036), respectively. CONCLUSION: We found that RD of the lateral meniscus was not a rare finding, and that RD was related to the meniscus status. Moreover, RD did not improve after ACL reconstruction. Thus, the treatment for meniscus tear should be carefully assessed. Level of evidence Level 4, case series, therapeutic studies.

Effects of articular cartilage and meniscus injuries at the time of surgery on osteoarthritic changes after anterior cruciate ligament reconstruction in patients under 40 years old.

INTRODUCTION: The development of osteoarthritis (OA) after anterior cruciate ligament (ACL) reconstruction is an unsolved problem. Articular cartilage and meniscus injuries are particularly important factors that contribute to OA progression. AIM: The purpose of this study was to investigate how articular cartilage and meniscus injuries at the time of surgery affected the development of OA under limited conditions retrospectively. Exclusion criteria of this study were (1) age 40 years or over, (2) previous surgery, (3) another combined knee ligament injury, and (4) unstable reconstructed knees. MATERIAL: This study included 49 knees in 46 patients (average 26 years; range, 13-39 years) who had undergone isolated ACL reconstruction. Mean follow-up period was 3.9 years (range, 2-8 years). We classified patients into two groups, cartilage-damaged and non-damaged. Patients were also classified into two groups on the basis of treatment for meniscus: meniscectomy group and meniscus intact group. OA changes were investigated using weigh-bearing anteroposterior radiographs taken before surgery and at evaluation. OA changes were evaluated in terms of joint space narrowing, atrophy, sclerosis, cysts, spurs, flattening of the femoral condyle, concavity of the tibial condyle, and sharpening of the eminence. Each parameter was scored, and the total number of points was recorded as the OA score. RESULTS: Differences between the preoperative OA score and that at evaluation were defined as the increase of the OA score. OA progressed in 28 knees (57%). OA score was higher at evaluation than before surgery (P < 0.001). In the cartilage-damaged group, the Lysholm score at evaluation was lower (P < 0.05) and the increase in the OA score was higher than in the non-damaged group (P < 0.05). The increase in the OA score was higher in the meniscectomy group (P < 0.05). CONCLUSION: We concluded that patients with cartilage damage and who had undergone meniscectomy show more progression of OA. These patients require long-term follow-up. LEVEL OF EVIDENCE: Level 4, case series, therapeutic studies, investigating the results of treatment.

The effect of medial collateral ligament insufficiency on the reconstructed anterior cruciate ligament: a study in the rabbit.

The treatment for severe combined anterior cruciate ligament (ACL) and medial collateral ligament (MCL) ruptures is disputed. Using a rabbit model, we examined the effect of insufficiency of medial structures on the reconstructed ACL in combined ACL and MCL injury. 40 rabbits were divided into 2 groups. In both groups, ACL was subjected to in situ freeze-thaw treatment. In group F, only freeze-thaw treatment of ACL was given. In group FM, partial resection of MCL was also done. We killed 5 rabbits on each of 4 occasions: immediately after the operation (time 0), at 6, 12 and 24 weeks postoperatively. At each time, we measured valgus instability and mechanical properties of the ACL. Valgus instability in group FM persisted from time 0 to 24 weeks, and was significantly greater than that in group F. The tensile strength and tangent modulus of the ACL in group FM were lower than those in group F. We found that continuous valgus instability reduces the mechanical properties of the in situ frozen ACL.