Grade III pivot shift as an early sign of knee decompensation in chronic ACL-injured knees with bimeniscal tears.

PURPOSE: To analyse possible associations between the preoperative pivot shift (PS) test and both patient and injury characteristics in anterior cruciate ligament (ACL)-injured knees, considering previously neglected meniscal injuries such as ramp and root tears. The hypothesis was that a preoperative grade III PS was associated with the amount of intra-articular soft-tissue damage and chronicity of the injury. METHODS: The cohort involved 376 patients who underwent primary ACL reconstruction (239 males/137 females; median age 26). Patients were examined under anesthesia before surgery, using the PS test. During arthroscopy, intra-articular soft-tissue damage of the injured knee was classified as: (1) partial ACL tear; (2) complete isolated ACL tear; (3) complete ACL tear with one meniscus tear; and (4) complete ACL and bimeniscal tears. Chi-square and Mann-Whitney U tests were used to evaluate whether sex, age, body mass index, sport at injury, mechanism of injury, time from injury and intra-articular damage (structural damage of ACL and menisci) were associated with a grade III PS. Intra-articular damage was further analyzed for two sub-cohorts: acute (time from injury ≤ 6 months) and chronic injuries (> 6 months). RESULTS: A grade III PS test was observed in 26% of patients. A significant association with PS grading was shown for age, time from injury and intra-articular soft-tissue damage (p < 0.05). Further analyses showed that grade III PS was associated with intra-articular damage in chronic injuries only (p < 0.01). In complete ACL and bimeniscal tears, grade III PS was more frequent in chronic (53%) than in acute knee injuries (26%; p < 0.01). Patients with chronic complete ACL and bimeniscal tears had a grade III PS 3.3 [1.3-8.2] times more often than patients in the acute sub-cohort. CONCLUSION: In ACL-injured patients, a preoperative grade III PS was mainly associated with a higher amount of intra-articular soft-tissue damage and chronicity of the injury. Patients with complete chronic ACL injuries and bimeniscal tears were more likely to have a preoperative grade III PS than their acute counterparts. This suggests that grade III PS may be an early sign of knee decompensation of dynamic rotational knee laxity in chronic ACL-injured knees with bimeniscal lesions. LEVEL OF EVIDENCE: Level III.

The aspiration test reveals an instability of the posterior horn of the lateral meniscus in almost one-third of ACL-injured patients.

PURPOSE: Anterior cruciate ligament (ACL) injuries often lead to associated injuries of the posterior horn of the lateral meniscus (PHLM). Arthroscopic, assessment of PHLM instability may be difficult in the absence of a visible meniscus damage. The main objective of this prospective multi-center study was to compare the ability of the probing and aspiration tests to identify PHLM instability in a population of patients undergoing ACL reconstruction (ACLR) and a control group of patients with an intact ACL undergoing knee arthroscopy. METHODS: A prospective case-control analysis was performed in three sports medicine centers. One-hundred and three consecutive patients operated for a primary isolated ACLR without structural lateral meniscus damage other than a root tear were included. They were compared to a control group of 29 consecutive patients who had a knee arthroscopy with an intact ACL and no structural lateral meniscus lesion. The probing and aspiration tests were consecutively executed according to previously published methods. RESULTS: In the control group, no lateral meniscus lesions were visualized during arthroscopy, and both probing and aspiration tests were negative in all patients. In the group of ACL-injured patients, a Forkel type I-III posterolateral meniscus root tear (PLMRT) was found in 12 patients (12%). In this subgroup, the probing test was positive in 4/12 patients (33%) and the aspiration test in 5 additional patients (75%). In 15 patients (15%), an elongation of the posterior root of the lateral meniscus (defined as type IV PLMRT as an addendum to the Forkel classification) could be observed during arthroscopy. In this subgroup, only 1 patient displayed a PHLM instability with the probing test (7%), whereas the aspiration test was positive in 13/15 patients (87%). In the remaining 76 patients (74%), no structural lesion of the PHLM could be identified. Nevertheless, an instability of the PHLM could be identified in 8 of them (11%) with the probing test, and the aspiration test was positive in 2 additional knees (13%) of this apparently normal subgroup. Altogether, in the entire ACL injury cohort, a positive probing test was observed in 13/103 patients (13%) and a positive aspiration test in 32/103 knees (31%) (p < 0.01). CONCLUSION: Careful observation and examination of the PHLM with the aspiration test revealed a substantial amount of previously undiagnosed lateral meniscus instabilities in ACL-injured knees. The prevalence of PHLM instability as evaluated by the aspiration test was high (31%). The aspiration test was superior to the probing test in detecting an instability of the PHLM in a population of ACL-injured patients. LEVEL OF EVIDENCE: II.

The aspiration test: an arthroscopic sign of lateral meniscus posterior horn instability.

The suspensory mechanism of the posterior horn of the lateral meniscus (PHLM) is an anatomically complex structure including the popliteomeniscal fascicles, the meniscotibial posterior root attachment and the meniscofemoral ligaments. Damage to one or several of these structures - either through knee trauma or congenital abnormalities-can result in an instability of the PHLM that may lead to lateral knee pain, locking sensations or lack of rotational control of the knee (e.g. after anterior cruciate ligament injuries). The diagnosis of PHLM instability is complex due to the lack of reliable clinical tests and imaging signs. Direct visual dynamic inspection via arthroscopy thus remains the gold standard. However, arthroscopic probing of the PHLM is not always reliable and the precise quantification of the amount of subluxation of the PHLM can be difficult. Therefore, the main objective of this report was to describe a quick and easy arthroscopic screening test called "the aspiration test" in order to help surgeons to detect PHLM instability. During the exploration of the lateral tibiofemoral compartment with the knee kept in the figure of 4 position, the arthroscope is placed in the antero-lateral portal and directed towards the lateral tibiofemoral compartment. The aspiration test is then performed by activating the aspiration of the 4-mm shaver when located in the intercondylar notch. In case of a PHLM instability, an excessive displacement of the PHLM is observed. After repair, a second aspiration test allows to verify that the PHLM has been stabilized.

Medial meniscus ramp and lateral meniscus posterior root lesions are present in more than a third of primary and revision ACL reconstructions.

PURPOSE: The purpose of this study was (1) to describe the meniscus tear pattern in anterior cruciate ligament (ACL)-injured patients, with a special focus on medial meniscus (MM) ramp lesions and lateral meniscus (LM) root tears and (2) to determine whether patient and injury characteristics were associated with meniscus tear patterns. METHODS: Data from 358 cases of ACL primary and revision reconstruction surgeries were extracted from a center-based registry. During arthroscopy, the presence of associated meniscus lesions was documented by systematically inspecting the anterior and posterior tibiofemoral compartments. With a special focus on MM ramp lesions and LM root tears, groups of different injury tear patterns were formed. Chi-square tests were used to determine whether these groups differed with respect to various patient and injury characteristics, including gender, previous ipsilateral ACL injuries, the injury's relation to sport, person contact during injury and the type of ACL tear. Median age at surgery and body mass index were compared between groups using the Kruskal-Wallis test. Significance was set at p < 0.05. RESULTS: Two hundred and thirty-nine ACL injuries (67%) showed additional meniscal injuries, of which 125 (52%) involved the MM ramp and/or the LM root. Ramp lesions were more frequent in males (23% vs 12% in females, p < 0.01), in contact injuries (28% vs 16% in non-contact, p < 0.05) and in complete ACL tears (21% vs 5% in partial, p < 0.05). Combined injuries of the MM ramp and the LM root showed a higher percentage of contact injuries compared to non-contact injuries (10% vs 4%, p < 0.05). CONCLUSION: Two-thirds of all ACL injuries showed a concomitant meniscus injury, of which half involved the biomechanically relevant, but previously often undiagnosed RLMM or the PRLM. These findings provide evidence that until recently about half of ACL-associated meniscus injuries were not properly identified. Ramp lesions were more frequent in males, contact injuries and in complete ACL tears. These findings stress the need for a systematic assessment and a better understanding of the pathomechanism of these specific injuries which may have an important impact on knee biomechanics and the outcome of ACL reconstruction. LEVEL OF EVIDENCE: III.

Ramp lesions of the medial meniscus are associated with a higher grade of dynamic rotatory laxity in ACL-injured patients in comparison to patients with an isolated injury.

PURPOSE: The purpose of this study was to compare preoperative knee laxity between two groups of patients with primary or revision ACL reconstruction with or without an associated ramp lesion of the medial meniscus. METHODS: Two-hundred and seventy-five patients with an ACL reconstruction (243 primaries; 32 revisions) were prospectively screened using direct arthroscopic visualisation and divided into a ramp lesion group (RLG) and a control group (CG) regardless of the presence of other associated meniscal tears. All patients were clinically examined under anaesthesia before surgery by grading the Lachman and pivot shift tests. RESULTS: Fifty-eight patients were included in the RLG. The CG included 217 patients. With all meniscus lesions included, there were no significant differences between the two groups. After excluding all other meniscus lesions in both groups except for ramp lesions in the RLG, the prevalence of a grade III pivot shift was higher in the RLG (32 remaining patients; 47% grade III) compared to the CG (91 remaining patients; 24% grade III, p = 0.02). The difference of patients with a grade III pivot shift between the CG and RLG remained significant after removal of revision ACL reconstructions (CG, 85 remaining patients; 25% grade III-RLG, 27 remaining patients; 44% grade III, p = 0.05). CONCLUSION: Patients with an isolated ramp lesion of the medial meniscus in association with an ACL injury displayed a higher amount of dynamic rotational laxity as expressed by the pivot shift test in comparison to patients with isolated ACL injury and no ramp lesion. The association between ramp lesions of the medial meniscus and increased pivot shift grading suggests that it is important to diagnose and repair them during ACL reconstruction surgery. LEVEL OF EVIDENCE: III.