Anterior cruciate ligament (ACL) instability poses a considerable challenge in traumatology and orthopedic medicine, demanding precise diagnostics for optimal treatment. The pivot-shift test, a pivotal assessment tool, relies on subjective interpretation, emphasizing the need for supplementary imaging. This study addresses this limitation by introducing a machine learning classification algorithm integrated into a mobile application, leveraging smartphones\' built-in inertial sensors for dynamic rotational stability assessment during knee examinations. Orthopedic specialists conducted knee evaluations on a cohort of 52 subjects, yielding valuable insights. Quantitative analyses, employing the Intraclass Correlation Coefficient (ICC), demonstrated robust agreement in both intraobserver and interobserver assessments. Specifically, ICC values of 0.94 reflected strong concordance in the timing between maneuvers, while signal amplitude exhibited consistency, with the ICC ranging from 0.71 to 0.66. The introduced machine learning algorithms proved effective, accurately classifying 90% of cases exhibiting joint hypermobility. These quantifiable results underscore the algorithm\'s reliability in assessing knee stability. This study emphasizes the practicality and effectiveness of implementing machine learning algorithms within a mobile application, showcasing its potential as a valuable tool for categorizing signals captured by smartphone inertial sensors during the pivot-shift test.

OBJECTIVE: The impact of posterolateral tibial plateau impaction fractures (TPIF) on posttraumatic knee stability in the setting of primary anterior cruciate ligament (ACL) tear is unknown. The main objective was to determine whether increased bone loss of the posterolateral tibial plateau is associated with residual rotational instability and impaired functional outcome after ACL reconstruction.
METHODS: A cohort was identified in a prospective enrolled study of patients suffering acute ACL injury who underwent preoperative standard radiographic diagnostics and clinical evaluation. Patients were included when scheduled for isolated single-bundle hamstring autograft ACL reconstruction. Exclusion criteria were concurrent anterolateral complex (ALC) reconstruction (anterolateral tenodesis), previous surgery or symptoms in the affected knee, partial ACL tear, multi-ligament injury with an indication for additional surgical intervention, and extensive cartilage wear. On MRI, bony (TPIF, tibial plateau, and femoral condyle morphology) and ligament status (ALC, concomitant collateral ligament, and meniscus injuries) were assessed by a musculoskeletal radiologist. Clinical evaluation consisted of KT-1000, pivot-shift, and Lachman testing, as well as Tegner activity and IKDC scores.
RESULTS: Fifty-eight patients were included with a minimum follow-up of 12 months. TPIF was identified in 85% of ACL injuries (n = 49). The ALC was found to be injured in 31 of 58 (53.4%) cases. Pearson analysis showed a positive correlation between TPIF and the degree of concomitant ALC injury (p < 0.001). Multiple regression analysis revealed an increased association of high-grade TPIF with increased lateral tibial convexity (p = 0.010). The high-grade TPIF group showed worse postoperative Tegner scores 12 months postoperatively (p = 0.035).
CONCLUSIONS: Higher degrees of TPIFs are suggestive of a combined ACL/ALC injury. Moreover, patients with increased posterolateral tibial plateau bone loss showed lower Tegner activity scores 12 months after ACL reconstruction.
METHODS: III.

OBJECTIVE: To analyze the MRI features, in particular bone bruises pattern, of Anterior Cruciate Ligament (ACL) injured footballers, and to correlate them with the characteristics of injury mechanism and situation obtained from direct video footage.
METHODS: Nineteen professional football (soccer) players that sustained ACL injury while playing during an official match of First League Championship were included in the study. The video of injury was obtained from the Television broadcast. Knee Magnetic Resonance (MRI) was obtained within 7 days from the injury. BB and meniscal lesions were analyzed on MRI, while a video-analysis of mechanisms of ACL injury and injury dynamic were assessed from the videos.
RESULTS: The most commonly involved Bone Bruise areas in the knee were the Posterior Lateral Tibial Plateau (LTp) in 16 cases (84%) and the Central Lateral Femoral Condyle (LFc) in 11 cases (58%). Three patients (16%) had bone bruise in the Posterior Medial Tibial Plateau (MTp) while none (0%) had bone bruise in the Medial Femoral Condyle. Based on the bone bruise pattern, 11 (58%) had simultaneous LFc and LTp and were defined \"Typical\" while 8 (42%) had other locations or no bone bruise and were defined \"Atypical\". 9 out of 11 injuries (82%) of athletes with \"Typical\" pattern occurred with a \"Pivoting\" action\", in contrast to only 1 case (12%) in those with \"Atypical\" bone bruise pattern (p = 0.0055). The most common situational mechanism pattern on video analysis was \"pressing\" (n = 7) accounting for the 47% of the \"indirect\" ACL injuries. In terms of movement pattern, ten injuries (52%) occurred during a \"Pivoting\" movement (7 pressing, 1 dribbling, 1 tackled, 1 goalkeeping), whereas the remaining were classified as \"Planting\" in four cases, \"Direct Blow\" in four cases and \"Landing\".
CONCLUSIONS: A well-defined and consistent bone bruise pattern involving the posterior tibial plateau and central femoral condyle of lateral compartment is present in footballers that sustained non-contact and indirect ACL injuries during pivoting with sudden change of direction/deceleration, while heterogeneous patterns were present in those with direct contact or injury mechanisms involving high horizontal velocity.
METHODS: Level IV.

OBJECTIVE: To determine whether isokinetic muscle recovery following ACLR using a hamstring tendon (HT) would be equivalent (non-inferior) in knees that had high-grade pivot-shift and adjuvant modified Lemaire procedure versus knees that had minimal pivot-shift and no adjuvant modified Lemaire procedure.
METHODS: We evaluated 96 consecutive patients that underwent primary ACLR. Nine were excluded because of contralateral knee injury, and of the remaining 87, ACLR was performed stand-alone in 52 (Reference group), and with a Lemaire procedure in 35 (Lemaire group) who had high-grade pivot-shift, age < 18, or genu recurvatum > 20°. At 6 months, isokinetic tests were performed at 240°/s and 90°/s to calculate strength deficits of hamstrings (H) and quadriceps (Q). At 8 months, patients were evaluated using IKDC, Lysholm, and Tegner scores.
RESULTS: Compared to the Reference group, the Lemaire group were younger (23.0 ± 2.5 vs 34.2 ± 10.5, p = 0.021) with a greater proportion of males (80% vs 56%, p < 0.001). The Lemaire group had no complications, but the Reference group had one graft failure and one cyclops syndrome. Strength deficits at 240°/s and at 90°/s were similar in both groups, but mixed H/Q ratios were lower for the Lemaire group (1.02 ± 0.19 vs 1.14 ± 0.24, p = 0.011). IKDC and Lysholm scores were similar in both groups, but Tegner scores were higher in the Lemaire group (median, 6.5 vs 6.0, p = 0.024).
CONCLUSIONS: ACLR with a modified Lemaire procedure for knees with rotational instability grants equivalent isokinetic muscle recovery as stand-alone ACLR in knees with no rotational instability. For ACL-deficient knees with high-grade pivot-shift, a Lemaire procedure restores rotational stability without compromising isokinetic muscle recovery.
METHODS: Level III, comparative study.

Conventional anatomical single bundle anterior cruciate ligament (ACL) reconstruction technique with round tunnels could not simulate morphology of native insertion, while studies about ACL reconstruction technique with modified tunnels based on morphology of anatomical insertion are rare. The purpose of this study was to demonstrate an ACL reconstruction technique with rounded rectangle tibial tunnel and oval femoral tunnel and compare clinical outcomes with conventional technique. A prospective comparative study was performed in 80 consecutive subjects who underwent ACL reconstruction with the conventional round tunnels (RT-Group, n=40) or modified tunnels (MT-Group, n=40). For the modified surgery, the tunnel was modified with a bone file based on the anatomical direction and area of the remnant insertion fibers. Graft maturity were evaluated by MR images at 12 months postoperatively and patients were examined for functional scores, physical examinations at 2-year follow-up. The primary variable was the pivot-shift test. No serious complications were experienced in either group. Seventy patients (87.5%) were examined at 2-year follow-up, significant improvements were seen in both groups compared with the preoperative values in terms of all clinical assessments. Tegner scores, pivot-shift test results and SNQ value in the MT-Group were significantly better than RT-Group (P=0.04, P=0.03 and P=0.001, respectively). There were no significant differences in Lysholm scores, IKDC scores, KT-2000 measurements and Lachman tests. We successfully developed the ACL reconstruction technique with rounded rectangle tibial tunnel and oval femoral tunnel, which was superior to conventional technique in terms of postoperative Tegner scores, pivot-shift tests and early graft maturity.

OBJECTIVE: The purpose of this study was to quantitatively compare the results of pivot-shift test between knees with anterior cruciate ligament (ACL) injury with and without anterolateral capsule (ALC) injury detected on MRI. ALC injury was hypothesized to worsen rotatory knee laxity.
METHODS: 82 patients with unilateral ACL injury were enrolled in this study. The pivot-shift test was performed under anesthesia before ACL reconstruction. Two evaluations were conducted simultaneously: IKDC clinical grading and the quantitative evaluation using an electromagnetic measurement system that determined tibial acceleration (m/s2). Two examiners identified the ALC injury on magnetic resonance imaging (MRI) and stratified patients into two groups: ALC-injured (ALC+) and ALC-intact (ALC-). ALC injury was diagnosed if the signal intensity on coronal T2-weighted sequences is increased. After confirming the reliability of the MRI, the difference in the pivot-shift between two groups was assessed.
RESULTS: Because of the poor agreement between examiners with respect to the ALC evaluations (κ coefficient of 0.25 and 58.5% concordance), the result from each examiner was analyzed separately. Examiner 1 found ALC injury in 42/82 knees (51%). The two groups had similar clinical grading (glide/clunk/gross: ALC+ group 21/18/3cases vs. ALC- group 21/16/3cases) (n.s.). Tibial acceleration during pivot-shift was also similar in the ALC+ (1.4 ± 1.2 m/s2) and ALC- (1.7 ± 1.3 m/s2) groups (n.s.). Examiner 2 found ALC injury in 28/82 knees (34%). Differences in clinical grading were not observed (glide/clunk/gross: ALC+ group 16/9/3 vs. ALC- group 26/25/3) (n.s.). However, the tibial acceleration in the ALC+ group (1.2 ± 0.8 m/s2) was significantly lower than that in the ALC- group (1.7 ± 1.3 m/s2, p = 0.03).
CONCLUSIONS: Concomitant ALC injury in knees with ACL injury was not consistently detected on MRI and did not affect rotatory knee laxity.
METHODS: Case-control study, level III.

This article describes the complex anatomic structures that pass across the lateral aspect of the knee, particularly the iliotibial tract and the underlying anterolateral ligament and capsule. It provides data on their strength and roles in controlling tibiofemoral joint laxity and stability. These findings are discussed in relation to surgery to repair or reconstruct the anatomic structures, or to create tenodeses with similar effect.

BACKGROUND: Segond\'s fracture is a well-recognised radiological sign of an anterior cruciate ligament (ACL) tear. While previous studies evaluated the role of the anterolateral ligament (ALL) and complex injuries on rotational stability of the knee, there are no studies on the biomechanical effect of Segond\'s fracture in an ACL deficient knee. The aim of this study was to evaluate the effect of a Segond\'s fracture on knee rotation stability as evaluated by a navigation system in an ACL deficient knee.
METHODS: Three different conditions were tested on seven knee specimens: intact knee, ACL deficient knee and ACL deficient knee with Segond\'s fracture. Static and dynamic measurements of anterior tibial translation (ATT) and axial tibial rotation (ATR) were recorded by the navigation system (2.2 OrthoPilot ACL navigation system B. Braun Aesculap, Tuttlingen, Germany).
RESULTS: Static measurements at 30° showed that the mean ATT at 30° of knee flexion was 5.1 ± 2.7 mm in the ACL intact condition, 14.3 ± 3.1 mm after ACL cut (P = 0.005), and 15.2 ± 3.6 mm after Segond\'s fracture (P = 0.08). The mean ATR at 30° of knee flexion was 20.7° ± 4.8° in the ACL intact condition, 26.9° ± 4.1° in the ACL deficient knee (P > 0.05) and 30.9° ± 3.8° after Segond\'s fracture (P = 0.005). Dynamic measurements during the pivot-shift showed that the mean ATT was 7.2 ± 2.7 mm in the intact knee, 9.1 ± 3.3 mm in the ACL deficient knee(P = 0.04) and 9.7 ± 4.3 mm in the ACL deficient knee with Segond\'s fracture (P = 0.07). The mean ATR was 9.6° ± 1.8° in the intact knee, 12.3° ± 2.3° in the ACL deficient knee (P > 0.05) and 19.1° ± 3.1° in the ACL deficient knee with Segond\'s lesion (P = 0.016).
CONCLUSIONS: An isolated lesion of the ACL only affects ATT during static and dynamic measurements, while the addition of Segond\'s fracture has a significant effect on ATR in both static and dynamic execution of the pivot-shift test, as evaluated with the aid of navigation.

Purpose of this paper is to provide an overview of the latest research on the anterolateral ligament (ALL) and present the consensus of the ALL Expert Group on the anatomy, radiographic landmarks, biomechanics, clinical and radiographic diagnosis, lesion classification, surgical technique and clinical outcomes. A consensus on controversial subjects surrounding the ALL and anterolateral knee instability has been established based on the opinion of experts, the latest publications on the subject and an exchange of experiences during the ALL Experts Meeting (November 2015, Lyon, France). The ALL is found deep to the iliotibial band. The femoral origin is just posterior and proximal to the lateral epicondyle; the tibial attachment is 21.6 mm posterior to Gerdy\'s tubercle and 4-10 mm below the tibial joint line. On a lateral radiographic view the femoral origin is located in the postero-inferior quadrant and the tibial attachment is close to the centre of the proximal tibial plateau. Favourable isometry of an ALL reconstruction is seen when the femoral position is proximal and posterior to the lateral epicondyle, with the ALL being tight upon extension and lax upon flexion. The ALL can be visualised on ultrasound, or on T2-weighted coronal MRI scans with proton density fat-suppressed evaluation. The ALL injury is associated with a Segond fracture, and often occurs in conjunction with acute anterior cruciate ligament (ACL) injury. Recognition and repair of the ALL lesions should be considered to improve the control of rotational stability provided by ACL reconstruction. For high-risk patients, a combined ACL and ALL reconstruction improves rotational control and reduces the rate of re-rupture, without increased postoperative complication rates compared to ACL-only reconstruction. In conclusion this paper provides a contemporary consensus on all studied features of the ALL. The findings warrant future research in order to further test these early observations, with the ultimate goal of improving the long-term outcomes of ACL-injured patients. Level of evidence Level V-Expert opinion.

BACKGROUND: The effect of an anterolateral ligament (ALL) reconstruction on rotational knee stability and corresponding anterior cruciate ligament (ACL) graft forces using multiple knee loading conditions including the pivot-shift phenomenon has not been determined.
OBJECTIVE: First, to determine the rotational stability and ACL graft forces provided by an anatomic bone-patellar tendon-bone ACL reconstruction in the ACL-deficient knee alone and with an associated ALL/iliotibial band (ITB) injury. Second, to determine the added rotational stabilizing effect and reduction in ACL graft forces provided by an ALL reconstruction.
METHODS: Controlled laboratory study.
METHODS: A 6 degrees of freedom robotic simulator was used to test 7 fresh-frozen cadaveric specimens during 5 testing conditions: intact, ACL-sectioned, ACL-reconstructed, ALL/ITB-sectioned, and ALL-reconstructed. Lateral and medial tibiofemoral compartment translations and internal tibial rotations were measured under Lachman test conditions, 5-N·m internal rotation, and 2 pivot-shift simulations. Statistical equivalence within 2 mm and 2° was defined as P < .05.
RESULTS: Single-graft ACL reconstruction restored central tibial translation under Lachman testing and internal rotation under 5-N·m internal rotation torque ( P < .05). A modest increase in internal rotation under 5-N·m internal rotation torque occurred after ALL/ITB sectioning of 5.1° (95% CI, 3.6° to 6.7°) and 6.7° (95% CI, 4.3° to 9.1°) at 60° and 90° of flexion, respectively ( P = .99). Lateral compartment translation increases in the pivot-shift tests were <2 mm. ALL reconstruction restored internal rotation within 0.5° (95% CI, -1.9° to 2.9°) and 0.7° (95% CI, -2.0° to 3.4°) of the ACL-reconstructed state at 60° and 90° of flexion, respectively ( P < .05). The ALL procedure reduced ACL graft forces, at most, 75 N in the pivot-shift tests and 81 N in the internal rotation tests.
CONCLUSIONS: Although the ALL reconstruction corrected the small abnormal changes in the internal rotation limit at high flexion angles, the procedure had no effect in limiting tibiofemoral compartment translations in the pivot-shift test and produced only modest decreases in ACL graft forces. Accordingly, the recommendation to perform an ALL reconstruction to correct pivot-shift abnormalities is questioned.
CONCLUSIONS: The small changes in rotational stability after ALL/ITB sectioning would not seem to warrant the routine addition of an ALL reconstruction in primary ACL injuries. Clinical exceptions may exist, as in grossly unstable grade 3 pivot-shift knees and revision knees. However, the concern exists of overconstraining normal tibial rotations.