• The popliteal hiatus is a complex region, formed by the confluence of various structures connecting the meniscus, popliteal tendon, tibia and fibula.

• The main structures that can be found are the three popliteomeniscal fascicles (anterior, postero-inferior and postero-superior), the lateral and posterior meniscotibial ligaments, the popliteofibular ligament and the meniscofibular fascicle.

• These structures can be identified in most cases using magnetic resonance imaging, and their ‘static’ assessment can be performed.

• Arthroscopic assessment is useful in identifying and testing ‘dynamically’ the integrity of the structures around the popliteal hiatus.

• Injuries or abnormalities of the popliteal hiatus and its structures could result in meniscal hypermobility and subluxation; however, these injuries are often unrecognized.

• Possible abnormalities in this region, apart from the well-known bucket-handle meniscal tear, are the Wrisberg Type III discoid meniscus, and meniscal fascicles tears.

Cite this article: EFORT Open Rev 2021;6:61-74. DOI: 10.1302/2058-5241.6.200089

• Injuries to the quadriceps muscle group are commonly seen in sporting activities that involve repetitive kicking and high-speed sprinting, including football (soccer), rugby and athletics.

• The proximal rectus femoris is prone to avulsion injuries as rapid eccentric muscle contraction leads to asynchronous muscle activation and different force vectors through the straight and reflected heads.

• Risk factors for injury include previous rectus femoris muscle or hamstring injury, reduced flexibility of the quadriceps complex, injury to the dominant leg, and dry field playing conditions.

• Magnetic resonance imaging (MRI) is the preferred imaging modality as it enables the site of injury to be accurately located, concurrent injuries to be identified, preoperative grading of the injury, and aids surgical planning.

• Non-operative management is associated with highly variable periods of convalescence, poor return to preinjury level of function and high risk of injury recurrence.

• Operative treatment of proximal rectus femoris avulsion injuries with surgical repair or surgical tenodesis enables return to preinjury level of sporting activity and high functional outcomes.

• Surgical tenodesis of proximal rectus femoris avulsion injuries may offer an avenue for further reducing recurrence rates compared to direct suture anchor repair of these injuries.

Cite this article: EFORT Open Rev 2020;5:828-834. DOI: 10.1302/2058-5241.5.200055

• There is a concern regarding which grafts should be used in combined anterior cruciate ligament (ACL) and medial collateral ligament (MCL) reconstructions, with a paucity of recommendations focused on this specific topic.

• Expert opinions suggest the use of allograft-only reconstructions to limit donor-site morbidity or using at least one allograft and one autograft.

• When a hamstring tendon autograft is harvested, techniques that maintain both the integrity of the sartorius fascia and the gracilis are recommended because of the role that the ST-G-S (semitendinosus-gracilis-sartorius) complex plays in valgus stability in the setting of an MCL-deficient knee.

Cite this article: EFORT Open Rev 2020;5:221-225. DOI: 10.1302/2058-5241.5.190049

• Chondral and osteochondral defects in the knee are common and may lead to degenerative joint disease if treated inappropriately.

• Conventional treatments such as microfracture often result in fibrocartilage formation and are associated with inferior results. Additionally, microfracture is generally unsuitable for the treatment of defects larger than 2–4 cm².

• The osteochondral autograft transfer system (OATS) has been shown to produce superior clinical outcomes to microfracture but is technically difficult and may be associated with donor-site morbidity. Osteochondral allograft use is limited by graft availability and failure of cartilage incorporation is an issue.

• Autologous chondrocyte implantation (ACI) has been shown to result in repair with hyaline-like cartilage but involves a two-stage procedure and is relatively expensive.

• Rehabilitation after ACI takes 12 months, which is inconvenient and not feasible for athletic patients.

• Newer methods to regenerate cartilage include autologous stem cell transplantation, which may be performed as a single-stage procedure, can have a shorter rehabilitation period and is less expensive than ACI. Longer-term studies of these methods are needed.

Cite this article: EFORT Open Rev 2020;5:156-163. DOI: 10.1302/2058-5241.5.190031

• Up to 18% of multiligament knee injuries (MLKI) have an associated vascular injury.

• All MLKI should be assessed using the ankle brachial pressure index (ABPI) with selective arteriography if ABPI is < 0.9.

• An ischaemic limb following knee dislocation must be taken to the operating theatre immediately for stabilization and re-vascularization.

• Partial common peroneal nerve (CPN) injury following MLKI has better recovery than complete palsy.

• Posterior tibial tendon transfer is offered to patients with complete CPN palsy if there is no recovery at six months.

• Operative treatment with acute or staged reconstructions provides the best outcome in MLKI.

• Effective repair can only be performed within three weeks of injury.

• There is no difference between repair and reconstruction of medial collateral ligament and posteromedial corner.

• Posterolateral corner reconstruction has a lower failure rate than repair.

• Early mobilization following MLKI surgery results in fewer range-of-motion deficits.

Cite this article: EFORT Open Rev 2020;5:145-155. DOI: 10.1302/2058-5241.5.190012

• Clinical management of meniscal injuries has changed radically in recent years. We have moved from the model of systematic tissue removal (meniscectomy) to understanding the need to preserve the tissue.

• Based on the increased knowledge of the basic science of meniscal functions and their role in joint homeostasis, meniscus preservation and/or repair, whenever indicated and possible, are currently the guidelines for management.

• However, when repair is no longer possible or when facing the fact of the previous partial, subtotal or total loss of the meniscus, meniscus replacement has proved its clinical value. Nevertheless, meniscectomy remains amongst the most frequent orthopaedic procedures.

• Meniscus replacement is currently possible by means of meniscal allograft transplantation (MAT) which provides replacement of the whole meniscus with or without bone plugs/slots. Partial replacement has been achieved by means of meniscal scaffolds (mainly collagen or polyurethane-based). Despite the favourable clinical outcomes, it is still debatable whether MAT is capable of preventing progression to osteoarthritis. Moreover, current scaffolds have shown some fundamental limitations, such as the fact that the newly formed tissue may be different from the native fibrocartilage of the meniscus.

• Regenerative tissue engineering strategies have been used in an attempt to provide a new generation of meniscal implants, either for partial or total replacement. The goal is to provide biomaterials (acellular or cell-seeded constructs) which provide the biomechanical properties but also the biological features to replace the loss of native tissue. Moreover, these approaches include possibilities for patient-specific implants of correct size and shape, as well as advanced strategies combining cells, bioactive agents, hydrogels or gene therapy.

• Herein, the clinical evidence and tips concerning MAT, currently available meniscus scaffolds and future perspectives are discussed.

Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180103

• New indications for meniscal allograft transplantation (MAT) are being added, but the general expert opinion is that it is still a procedure reserved for symptomatic meniscal loss.

• Lateral MAT has better clinical outcomes and less failure risk compared to medial MAT.

• Ideal conditions (low-grade chondral lesions) make MAT a more survivable and successful procedure.

• Meniscal extrusion after MAT is common and does not seem to alter results.

• Midterm survivorship of a MAT is reported to be 85–90%, while long-term survivorship decreases to 50–70% depending on chondral status and concomitant procedures.

• Even if the procedure is a success, there are high possibilities of not being able to resume sports activities.

Cite this article: EFORT Open Rev 2019;4:115-120. DOI: 10.1302/2058-5241.4.180052

• The most frequent indications for arthroscopy in patients with total knee arthroplasty (TKA) are soft-tissue impingement, arthrofibrosis (knee stiffness), periprosthetic infection and removal of free bodies or cement fragments.

• When performing a knee arthroscopy in a patient with a symptomatic TKA, look for possible free/retained bone or cement fragments, which can be anywhere in the joint.

• Patellar tracking should be evaluated and soft-tissue impingement under the patella or between the femoral and tibial prosthetic components should be ruled out.

• Current data suggest that knee arthroscopy is an effective procedure for the treatment of some patients with symptomatic TKA.

• The approximate rates of therapeutic success vary according to the problem in question: 85% in soft-tissue impingement; 90% in arthrofibrosis; and 55% in periprosthetic infections.

• More clinical studies are needed to determine which patients with symptomatic TKA can be the best candidates for knee arthroscopy.

Cite this article: EFORT Open Rev 2019;4:33-43. DOI: 10.1302/2058-5241.4.180035.

• From the biomechanical and biological points of view, an arthroscopic meniscal repair (AMR) should always be considered as an option. However, AMR has a higher reoperation rate compared with arthroscopic partial meniscectomy, so it should be carefully indicated.

• Compared with meniscectomy, AMR outcomes are better and the incidence of osteoarthritis is lower when it is well indicated.

• Factors influencing healing and satisfactory results must be carefully evaluated before indicating an AMR.

• Tears in the peripheral third are more likely to heal than those in the inner thirds.

• Vertical peripheral longitudinal tears are the best scenario in terms of success when facing an AMR.

• ‘Inside-out’ techniques were considered as the gold standard for large repairs on mid-body and posterior parts of the meniscus. However, recent studies do not demonstrate differences regarding failure rate, functional outcomes and complications, when compared with the ‘all-inside’ techniques.

• Some biological therapies try to enhance meniscal repair success but their efficacy needs further research. These are: mechanical stimulation, supplemental bone marrow stimulation, platelet rich plasma, stem cell therapy, and scaffolds and membranes.

• Meniscal root tear/avulsion dramatically compromises meniscal stability, accelerating cartilage degeneration. Several options for reattachment have been proposed, but no differences between them have been established. However, repair of these lesions is actually the reference of the treatment.

• Meniscal ramp lesions consist of disruption of the peripheral attachment of the meniscus. In contrast, with meniscal root tears, the treatment of reference has not yet been well established.

Cite this article: EFORT Open Rev 2018;3:584-594. DOI: 10.1302/2058-5241.3.170059

• Turf toe is a condition that describes injury to the plantar metatarsophalangeal-sesamoid complex of the great toe.

• It is a relatively rare and debilitating condition, particularly seen in American footballers after the introduction of harder, artificial ‘turf’ surfaces.

• Turf toe represents a significant injury to the hallux and requires a high index of suspicion.

• If unrecognized, it can lead to chronic problems including reduced push-off strength, persistent pain, progressive deformity and eventual joint degeneration.

• Patients with chronic injuries may have worse outcomes, and therefore early, accurate diagnosis and initiation of treatment play a vital role.

• A multidisciplinary team approach is key for successful return to sport.

Cite this article: EFORT Open Rev 2018;3:501-506. DOI: 10.1302/2058-5241.3.180012