Knee dislocations (KD) and multiligamentous knee injuries (MLKI) are challenging injuries to manage due to the high incidence of associated neurovascular compromise, extensive peri-articular soft-tissue trauma, and long-term functional deficits. Knee-spanning external fixation (KSEF) is occasionally utilized in the acute management of these injuries with the aim of maintaining alignment, protecting vascular repairs, allowing soft-tissue recovery prior to definitive treatment, and protecting freshly reconstructed or repaired ligaments. Despite its use in 5% of MLKIs and up to 50% of KDs, the clinical indications, outcomes, and complications associated with KSEF in the setting of KD/MLKI remain incompletely defined. Furthermore, KD/MLKI treatment algorithms incorporating decision-making related to KSEF application are limited both institutionally and within the literature. Thus, the purpose of this study was to consolidate the existing evidence related to the use of KSEF in the setting of KD/MLKI to support clinical decision-making and identify avenues for future investigation. Following a narrative review of the literature, the identified indications for KSEF in the setting of KD/MLKI were vascular injury, knee fracture-dislocation, extensive soft-tissue injury, persistent instability following reduction, open KDs, and when bracing is not feasible due to patient factors such as morbid obesity. Both rigid and hinged KSEF constructs have been described, with hinged fixators potentially permitting early motion while providing joint stability. Reported complications of KSEF include arthrofibrosis, infection, heterotopic ossification, and compartment syndrome, though available data are primarily retrospective and heterogeneous. Other topics that have been addressed in the literature include biomechanics, cost, magnetic resonance imaging (MRI) compatibility, and psychological impact. However, further research is needed to clarify its specific role, define standardized indications, and compare outcomes with non-invasive or alternative fixation and immobilization strategies. Plain Language Summary: Knee dislocations and multiple ligament knee injuries are serious injuries that can cause damage to blood vessels, nerves, and soft tissues around the knee, leading to long-term challenges with movement. Doctors sometimes use a device called a knee-spanning external fixator to treat these injuries, which is a metal frame that surgeons place outside of the leg to hold the knee stable This article summarizes what doctors and researchers currently know about knee-spanning external fixators, including their risks and benefits, and explains why more research is needed to guide treatment decisions related to the use of these devices in the management of severe knee injuries. This device is mainly used when the knee is too unstable for a brace, when there is a blood vessel injury, when the skin around the knee is severely damaged, and when the patient has multiple other injuries that need to be managed before their knee injury. While knee-spanning external fixators can help protect the knee and allow it to heal, they also carry several risks like stiffness, infections where the pins enter the skin, unwanted bone growth in the knee, and excessive pressure build-up within the leg. There are also psychological and cost-related concerns associated with the use of these devices. Despite being used frequently, doctors and researchers have not reached a clear agreement about exactly when to use or avoid these devices.

Purpose: While rigid knee‐spanning external fixation is more commonly utilized in the treatment of complex knee injuries compared to hinged external fixation (HEF), HEF has the added benefit of providing stability while also permitting early controlled range of motion. However, there is limited existing literature on the indications for HEF of the knee. The aim of this study was to review the clinical indications for HEF in the management of acute and chronic knee dislocations (KD), tibiofemoral subluxations and knee fracture‐dislocations.Methods: Five databases, including PubMed, CINAHL, Cochrane, Scopus and SPORTDiscus, were systematically searched. Included studies were those that involved comparative or non‐comparative evaluation of patients with an HEF applied for an acute or chronic KD, tibiofemoral subluxation or knee fracture‐dislocation.Results: Fourteen studies ranging from 1998 to 2023 met inclusion criteria, with a total of 184 knees treated with HEF for an acute or chronic KD, tibiofemoral subluxation, or knee fracture‐dislocation. The most common primary indication for HEF was acute or chronic KD. The most common secondary indications included combined osseous and ligamentous deficiency, associated vascular or soft‐tissue injury, status post extensive capsular release for arthrofibrosis, and associated extensor mechanism disruption.Conclusion: While uncommon, HEF is a valuable option in the treatment of complex knee injuries where both stability and controlled mobilization are essential. Due to limitations in the available evidence, further high‐quality research is needed to establish guidelines for the utilization of HEF about the knee.Level of Evidence: Level IV.

An understanding of the embryonic and fetal formation of the knee can help elucidate the relationships between the various structures and clinical conditions. While there have been studies published on the steps of knee development by sectioning human embryos and fetuses, the goal of this review is to consolidate these findings and images into one cohesive work. The timing and appearance of the structures in the knee are outlined with a focus on the cruciate and meniscofemoral ligaments (MFLs). In particular, the posterior cruciate ligament is emphasized with its relationship to other intraarticular structures and congenital anomalies that may arise. The steps of embryological development are outlined by the 23 stages of Carnegie embryonic staging system, which are distinguished by morphological criteria seen on histology of embryo sections. These images highlight the mesenchymal tissue within the interzone of the knee that form the primitive cruciate ligaments and menisci and the subsequent development of the cavitations within the knee that start to give it an appearance similar to that of an adult knee. The steps of fetal development are outlined by the weeks of development with the histological images showing the development of articulations between structures. This review paper consolidates various sources throughout the literature to outline the embryological and fetal appearance and relationship of intraarticular structures in the knee, such as the cruciate and MFLs, and how their altered development may contribute to the congenital anomalies and clinical conditions that may arise.

Context: Hypermobility of the lateral meniscus is a relatively uncommon condition characterized by excessive, abnormal movement of the lateral meniscus in the knee joint. This literature review and case report aims to provide insights into the clinical presentation, diagnosis, and treatment options for peripheral lateral meniscocapsular tears that result in excessive lateral meniscal motion. Evidence Acquisition: A narrative review of the literature and the clinical expertise of the authors. Study Design: Narrative overview. Level of Evidence: Level 5. Results: A hypermobile lateral meniscus poses diagnostic challenges due to overlapping symptoms with other knee pathologies. The anatomy of the posterolateral meniscocapsular recess and popliteus hiatus can distort the ability to accurately diagnose tears of the peripheral attachments of the posterior horn of the lateral meniscus. In a primary care practice, recognition of this condition in patients presenting with recurrent mechanical catching or locking episodes, sometimes with a “normal” magnetic resonance imaging (MRI) scan, is crucial to refer to orthopaedics in a timely manner to prevent further damage. Arthroscopic meniscal repair can be an effective treatment option, facilitating a safe return to sports after rehabilitation. Conclusion: A hypermobile lateral meniscus and peripheral meniscocapsular tears of the lateral meniscus should be considered in the differential diagnosis of knee pain with recurrent locking episodes, even with an “unremarkable” MRI scan. Timely and accurate diagnosis and appropriate intervention, such as arthroscopic meniscal repair, can lead to better quality of life. Further research is needed to explore long-term outcomes and optimal management strategies for hypermobile lateral meniscal tears. Strength-of-Recommendation Taxonomy (SORT): Level C.

Background: Uniplanar coronal tibiofemoral subluxation (UCTFS) in the setting of multiple ligament knee injury (MLKI) or knee dislocation (KD) has rarely been discussed, and the potential for missed diagnosis may significantly impact long-term outcomes. Purpose: To describe the presentation, injury patterns, possible mechanical barriers for reduction, and management for isolated UCTFS after MLKI/KD. Study Design: Case series; Level of evidence, 4. Methods: A retrospective chart review was conducted at 4 institutions to identify patients with KD or MLKI who were evaluated with or developed subsequent UCTFS from January 2001 to January 2024. UCTFS was defined as medial or lateral translation of the tibial plateau in reference to the femoral condyle as seen on coronal imaging (radiograph, computed tomography scan, or magnetic resonance imaging scan), with normal alignment seen on the sagittal imaging. Medical records were reviewed for demographic data, clinical presentation, physical examination, diagnostic imagining, examination under anesthesia, surgical finding, and procedures performed. Results: A total of 15 cases were included. Of these, 12 patients were subluxed laterally and 3 medially. UCTFS was diagnosed at different time points with 10 patients within 1 week, 2 patients between 1 and 6 weeks, and 3 patients after 6 weeks from injury. The most common mechanism of injury was a fall (33%), and the most common pattern of injury was a KD-3L (26.6%). A mechanical blockage to reduction was found in 9 (60%) cases. These included medial soft tissue sleeve incarceration (n = 4), bucket-handle meniscal tears (n = 3), concomitant patellar dislocation (n = 2), and a displaced tibial spine fracture (n = 1). Some patients experienced subluxation due to several sources of mechanical block. Uniplanar external fixation was utilized in 7 patients for management of their initial ligamentous injuries, coronal instability, or a traumatic vascular injury. Hinged external fixation was utilized in 2 patients who presented in a chronic fashion to counter the propensity to subluxation while allowing early motion. Conclusion: UCTFS is a rare event that has several potential factors contributing to its cause, and ≥1 of these factors may need to be surgically addressed. Tibiofemoral subluxation can be found at various time points from injury, and awareness and monitoring for its development should be factored into the clinical decision-making. UCTFS is a challenging clinical dilemma that may require multiplanar or hinged external fixation to maintain reduction.