German S2e-Guideline "Knee Dislocation". / S2e-Leitlinie "Kniegelenkluxation".

Knee dislocation is a devastating form of multiligament injury of the knee. Due to its high complexity, there is a large number of different diagnostic and treatment strategies. With the aim of providing evidence-based treatment recommendations, the S2e guideline on knee dislocation is aimed at all professional groups involved in diagnostics and therapy (orthopaedic and trauma surgeons, physiotherapists, outpatient/inpatient surgeons, sports physicians, etc.) as well as those affected (patients with knee dislocation) and service providers (health insurance companies, pension insurance companies). In addition to the presentation of conceptual differences between the injury entities, this includes the special features of diagnostic testing, options for conservative and surgical therapy as well as aspects of follow-up treatment - against the background of the interdisciplinary treatment approach to a severe knee injury.

The treatment of posterolateral knee instability with combined arthroscopic popliteus bypass and PCL reconstruction provides good-to-excellent clinical results in the mid-term follow-up.

PURPOSE: The purpose of this study was to evaluate the clinical outcomes of patients who were treated with an arthroscopic popliteus bypass (PB) technique, in cases of a posterolateral rotational instability (PLRI) and a concomitant posterior cruciate ligament (PCL) injury of the knee. METHODS: This was a retrospective case series in which 23 patients were clinically evaluated after a minimum of 2 years following arthroscopic PB and combined PCL reconstruction. Lysholm, Tegner and Knee Injury and Osteoarthritis Outcome scores as well as visual analog scales (VAS) for joint function and pain were evaluated. Posterior laxity was objectified with stress radiography and a Rolimeter examination. Rotational instability was graded with the dial test. RESULTS: 23 patients were available for follow-up, 46.0 ± 13.6 months after surgery. The median time interval from the initial injury to the surgery was 6.0 (3.5;10.5) months. The postoperative Lysholm Score was 95.0 (49-100); the Tegner Score changed from 6.0 (3-10) before the injury to 5.0 (0-10) at the follow-up examination (p = 0.013). The side-to-side difference on stress radiography (SSD) of posterior translation changed from 10.4 (6.6-14.8) mm before the injury to 4.0 (0.2-5.7) mm postoperatively (p < 0.01). Rotational instability was reduced to grade A (82.6%) or B (17.4%) (IKDC). The Rolimeter SSD was 2.0 (0-3) mm at the follow-up examination. VAS Function 0 (0-5), VAS pain 0 (0-6). CONCLUSIONS: The arthroscopic PB graft technique provided good-to-excellent clinical results in the mid-term follow-up in patients with type A PLRI and concomitant PCL injury. However, an exact differentiation of lateral, rotational and dorsal instabilities of posterolateral corner (PLC) injuries is crucial, for the correct choice of therapy, as cases with lateral instabilities require more complex reconstruction techniques. Arthroscopic posterolateral corner reconstruction is a safe procedure with a high success rate in the mid-term follow-up. LEVEL OF EVIDENCE: IV.

The Popliteus Bypass provides superior biomechanical properties compared to the Larson technique in the reconstruction of combined posterolateral corner and posterior cruciate ligament injury.

PURPOSE: This study aimed to compare the biomechanical properties of the popliteus bypass against the Larson technique for the reconstruction of a combined posterolateral corner and posterior cruciate ligament injury. METHODS: In 18 human cadaver knees, the kinematics for 134 N posterior loads, 10 Nm varus loads, and 5 Nm external rotational loads in 0°, 20°, 30°, 60,° and 90° of knee flexion were measured using a robotic and optical tracking system. The (1) posterior cruciate ligament, (2) meniscofibular/-tibial fibers, (3) popliteofibular ligament (PFL), (4) popliteotibial fascicle, (5) popliteus tendon, and (6) lateral collateral ligament were cut, and the measurements were repeated. The knees underwent posterior cruciate ligament reconstruction, and were randomized into two groups. Group PB (Popliteus Bypass; n = 9) underwent a lateral collateral ligament and popliteus bypass reconstruction and was compared to Group FS (Fibular Sling; n = 9) which underwent the Larson technique. RESULTS: Varus angulation, posterior translation, and external rotation increased after dissection (p < 0.01). The varus angulation was effectively reduced in both groups and did not significantly differ from the intact knee. No significant differences were found between the groups. Posterior translation was reduced by both techniques (p < 0.01), but none of the groups had restored stability to the intact state (p < 0.02), with the exception of group PB at 0°. No significant differences were found between the two groups. The two techniques revealed major differences in their abilities to reduce external rotational instability. Group PB had less external rotational instability compared to Group FS (p < 0.03). Only Group PB had restored rotational instability compared to the state of the intact knee (p < 0.04) at all degrees of flexion. CONCLUSION: The popliteus bypass for posterolateral reconstruction has superior biomechanical properties related to external rotational stability compared to the Larson technique. Therefore, the popliteus bypass may have a positive influence on the clinical outcome. This needs to be proven through clinical trials.

Lateral extra-articular tenodesis in patients with revision anterior cruciate ligament (ACL) reconstruction and high-grade anterior knee instability.

BACKGROUND: Additional lateral extra-articular procedures can reduce the risk of failure of primary anterior cruciate ligament reconstruction (ACLR). There is limited evidence on the effect of lateral extra-articular procedures in revision ACL surgery. The purpose of this study was to evaluate the clinical outcome of patients with lateral extra-articular tenodesis (LET) in combination with revision ACLR for combined ACL graft failure and high-grade anterior knee instability. METHODS: Between 2016 and 2018, 75 patients with graft failure after primary ACLR and high-grade anterior knee instability who received revision ACLR were included in the retrospective study. High-grade anterior knee instability was defined as high-grade pivot-shift or side-to-side difference of more than six millimeters in Rolimeter®-testing. An additional modified Lemaire tenodesis was performed in 59 patients during revision ACLR. Seventy-three patients were clinically examined with a minimum of two years after revision surgery. RESULTS: Failure of the revision ACLR occurred in 8.2% (n = 6) of the cases. LET lead to significant decreased failure rates (five percent vs. 21%, p = .045) and decreased incidence of a positive pivot-shift in patients with revision ACLR and high-grade anterior knee instability in comparison to patients without LET. Also, postoperative functional scores were significantly increased in the group of additional LET. CONCLUSIONS: Additional LET in patients with revision ACLR and high-grade anterior instability significantly reduces the risk of failure of revision ACLR, the incidence of pivot-shift and increases postoperative functional outcome.

Anatomic Reconstruction of the Posterolateral Corner: An All-Arthroscopic Technique.

Injuries of the posterolateral corner (PLC) of the knee lead to chronic lateral and external rotational instability. Successful treatment of PLC injuries requires an understanding of the complex anatomy and biomechanics of the PLC. Several open PLC reconstruction techniques have been published. It is understood that anatomic reconstruction is superior to extra-anatomic techniques, leading to better clinical results. An open, anatomic, fibula-based technique for reconstruction to address lateral and rotational instability has been described. However, when an open technique is used, surgeon and patient are faced with disadvantages, such as soft tissue damage or exposure of vulnerable structures. Few arthroscopic techniques for tibia- or fibula-based reconstruction of rotational posterolateral instability have been described. A complete arthroscopic stabilization of the combined lateral and posterolateral rotational instability of the knee has not yet been described. We therefore present the first all-arthroscopic technique for complete PLC reconstruction, based on an open technique described previously. All relevant landmarks of the PLC can be arthroscopically visualized in detail, allowing safe and effective treatment of PLC injuries.

Kinematics of Different Components of the Posterolateral Corner of the Knee in the Lateral Collateral Ligament-intact State: A Human Cadaveric Study.

PURPOSE: To determine the static stabilizing effects of different anatomical structures of the posterolateral corner (PLC) of the knee in the lateral collateral ligament (LCL)-intact state. METHODS: Thirteen fresh-frozen human cadaveric knees were dissected and tested using an industrial robot with an optical tracking system. Kinematics were determined for 134 N anterior/posterior loads, 10 N m valgus/varus loads, and 5 N m internal/external rotatory loads in 0°, 20°, 30°, 60°, and 90° of knee flexion. The PLC structures were dissected and consecutively released: (I) intact knee joint, (II) with released posterior cruciate ligament (PCL), (III) popliteomeniscal fibers, (IV) popliteofibular ligament, (V) arcuat and popliteotibial fibers, (VI) popliteus tendon (PLT), and (VII) LCL. Repeated-measures analysis of variance was performed with significance set at P < .05. RESULTS: After releasing the PCL, posterior tibial translation increased by 5.2 mm at 20° to 9.4 mm at 90° of joint flexion (P < .0001). A mild 1.8° varus instability was measured in 0° of flexion (P = .0017). After releasing the PLC structures, posterior tibial translation further increased by 2.9 mm at 20° to 5.9 mm at 90° of flexion (P < .05) and external rotation angle increased by 2.6° at 0° to 7.9° at 90° of flexion (P < .05, vs II). Varus stability did not decrease. Mild differences between states V and VI were found in 60° and 90° external rotation tests (2.1° and 3.1°; P < .05). CONCLUSIONS: The connecting ligaments/fibers to the PLT act as a primary static stabilizer against external rotatory loads and a secondary stabilizer against posterior tibial loads (when PCL is injured). After releasing these structures, most static stabilizing function of the intact PLT is lost. The PLC has no varus-stabilizing function in the LCL-intact knee. CLINICAL RELEVANCE: Anatomy and function of these structures for primary and secondary joint stability should be considered for clinical diagnostics and when performing surgery in the PLC.