The patellar tendon wavy sign as a new secondary sign of ACL tear on MRI

Exploring Anatomo-Morphometric Characteristics of Infrapatellar, Suprapatellar Fat Pad, and Knee Ligaments in Osteoarthritis Compared to Post-Traumatic Lesions

Several studies have investigated cartilage degeneration and inflammatory subchondral bone and synovial membrane changes using magnetic resonance (MR) in osteoarthritis (OA) patients. Conversely, there is a paucity of data exploring the role of knee ligaments, infrapatellar fat pad (IFP), and suprapatellar fat pad (SFP) in knee OA compared to post-traumatic cohorts of patients. Therefore, the aim of this study was to analyze the volumetric and morphometric characteristics of the following joint tissues: IFP (volume, surface, depth, femoral and tibial arch lengths), SFP (volume, surface, oblique, antero−posterior, and cranio−caudal lengths), anterior (ACL) and posterior cruciate ligament (PCL) (volume, surface, and length), and patellar ligament (PL) (volume, surface, arc, depth, and length). Eighty-nine MR images were collected in the following three groups: (a) 32 patients with meniscal tears, (b) 29 patients with ACL rupture (ACLR), and (c) 28 patients affected by end-stage OA. Volume, surface, and length of both ACL and PCL were determined in groups a and c. A statistical decrease of IFP volume, surface, depth, femoral and tibial arch lengths was found in end-stage OA compared to patients with meniscal tear (p = 0.002, p = 0.008, p < 0.0001, p = 0.028 and p < 0.001, respectively) and patients with ACLR (p < 0.0001, p < 0.0001, p = 0.008 and p = 0.011, respectively). An increment of volume and surface SFP was observed in group b compared to both groups a and c, while no differences were found in oblique, antero−posterior, and cranio−caudal lengths of SFP among the groups. No statistical differences were highlighted comparing volume, surface, arc, and length of PL between the groups, while PL depth was observed to be decreased in end-OA patients compared with meniscal tear patients (p = 0.023). No statistical differences were observed comparing ACL and PCL lengths between patients undergoing meniscectomy and TKR. Our study confirms that IFP MR morphometric characteristics are different between controls and OA, supporting an important role of IFP in OA pathology and progression in accordance with previously published studies. In addition, PL depth changes seem to be associated with OA pathology. Multivariate analysis confirmed that OA patients had a smaller IFP compared to patients with meniscal tears, confirming its involvement in OA.

[Research progress of lateral femoral notch sign in diagnosis of anterior cruciate ligament rupture]

Objective

To summarize the relationship between lateral femoral notch sign (LFNS) and anterior cruciate ligament (ACL) rupture.

Methods

The relevant literature of LFNS at home and abroad in recent years was retrospectively reviewed, and its mechanism, diagnostic criteria and influencing factors in diagnosis of ACL rupture were summarized and analyzed.

Results

The LFNS is associated with rotational stability of the knee. As an indirect sign of ACL rupture, the LFNS has high clinical diagnostic value, especially the diagnosis of ACL rupture with lateral meniscus injury.

Conclusion

The diagnostic criteria and influencing factors of LFNS in diagnosis of ACL rupture are still unclear and controversial, which needs further study.

Tibial tubercle-trochlear groove (TT-TG) distance is a reliable measurement of increased rotational laxity in the knee with an anterior cruciate ligament injury

BACKGROUND

The aims of this study were: 1. To evaluate the use of the tibial tubercle-trochlear groove (TT-TG) distance as a measurement showing rotational instability after anterior cruciate ligament (ACL) injury. 2. To determine the effect of concomitant anterolateral ligament (ALL) injury on TT-TG distance.

METHODS

Knee magnetic resonance (MR) images of 251 patients were retrospectively evaluated to compare the study group (131 patients) who underwent ACL reconstruction due to acute complete ACL injury and the control group (120 patients) without any trauma and/or patellofemoral instability. The rate of secondary signs of ACL injury (Anterolateral ligament injury, Kissing lesion, Anterior tibial translocation, Buckling of the posterior cruciate ligament (PCL)) in the study group was noted. The relationship between the TT-TG distance and other secondary signs was examined.

RESULTS

TT-TG distance was measured as 10.83 ± 1.2 mm, 12.88 ± 1.1 mm, 14.17 ± 1.5 mm in control, isolated ACL and ACL + ALL groups, respectively (p < 0.05). TT-TG distance was significantly higher in the patients with ALL injury and kissing lesions than the patients without these lesions (p ˂ 0.05). TT-TG distance did not differ significantly between the patients with and without anterior tibial translocation or buckling of the PCL (p ˃ 0.05). TT-TG distance measurements showed significant interobserver 0.994 (0.992-0.996) and intraobserver 0.997 (0.996-0.998) correlation.

CONCLUSIONS

TT-TG distance measurement can be used as a reliable quantitative measure of the increased rotational instability after ACL injury. TT-TG distance increases significantly if there is an ALL injury accompanying the ACL injury.