• Hip instability following total hip arthroplasty (THA) remains a major challenge and is one of the main causes of revision surgery.

• Dual mobility (DM) implants have been introduced to try to overcome this problem. The DM design consists of a small femoral head captive and mobile within a polyethylene liner.

• Numerous studies have shown that DM implants reduce the rate of dislocation compared to fixed-bearing inserts.

• Early designs for DM implants had problems with wear and intra-prosthetic dislocations, so their use was restricted to limited indications.

• The results of the latest generation of DM prostheses demonstrate that these problems have been overcome. Given the results of these studies presented in this review, surgeons may now consider DM THA for a wider patient selection.

Cite this article: EFORT Open Rev 2019;4:541-547. DOI: 10.1302/2058-5241.4.180045

• Advanced hemophilic knee arthropathy is a frequent and devastating manifestation of severe hemophilia with significant implications for activities of daily living.

• Hemophilic arthropathy is caused by repeated bleeding, resulting in joint degeneration, pain, deformity and disability.

• In patients with hemophilia and advanced disease, total knee arthroplasty (TKA) has proven to be the most successful intervention, improves physical function and reduces knee pain.

• Hemophilic patients carry additional risks for complications and required specific pre/postoperative considerations. Expert treatment center should be used to improve patient outcome.

• Hemophilic patients present significant surgical challenges such as joint destruction, bone loss, severe ankylosis and oligoarticular involvement. The surgeon performing the arthroplasty must be experienced to manage such problems.

• The Kinematic Alignment (KA) technique for total knee arthroplasty (TKA) is an alternative surgical technique aiming to resurface knee articular surfaces.

• The restricted KA (rKA) technique for TKA applies boundaries to the KA technique in order to avoid reproducing extreme constitutional limb/knee anatomies.

• The vast majority of TKA cases are straightforward and can be performed with KA in a standard (unrestricted) fashion.

• There are some specific situations where performing KA TKA may be more challenging (complex KA TKA cases) and surgical technique adaptations should be included.

• To secure good clinical outcomes, complex KA TKA cases must be preoperatively recognized, and planned accordingly.

• The proposed classification system describes six specific issues that must be considered when aiming for a KA TKA implantation.

• Specific recommendations for each situation type should improve the reliability of the prosthetic implantation to the benefit of the patient.

• The proposed classification system could contribute to the adoption of a common language within our orthopaedic community that would ease inter-surgeon communication and could benefit the teaching of the KA technique. This proposed classification system is not exhaustive and will certainly be improved over time.

Cite this article: EFORT Open Rev 2021;6:881-891. DOI: 10.1302/2058-5241.6.210042

• Although hip and knee joint replacements provide excellent clinical results, many patients still do not report the sensation and function of a natural joint. The perception that the joint is artificial may result from the anatomical modifications imposed by the surgical technique and the implant design. Moreover, the joint replacement material may not function similarly to human tissues.

• To restore native joint kinematics, function, and perception, three key elements play a role: (i) joint morphology (articular surface geometry, bony anatomy, etc.), (ii) lower limb anatomy (alignment, joint orientation), and (iii) soft tissue laxity/tension.

• To provide a ‘forgotten joint’ to most patients, it is becoming clear that personalizing joint replacement is the key solution. Performing a personalized joint replacement starts with patient selection and preoperative optimization, followed by using a surgical technique and implant design aimed at restoring the patient’s native anatomy, creating optimal implant-to-bone stress transfer, restoring the joint’s native articular range of motion without imposed limitations, macro- and micro-stability of the soft tissues, and a bearing whose wear resistance provides lifetime survivorship with unrestricted activities. In addition, the whole perioperative experience should follow enhanced recovery after surgery principles, favoring a rapid and complication-free recovery.

• As a new concept, some confusion may arise when applying these personalized surgery principles. Therefore, the Personalized Arthroplasty Society was created to help structure and accelerate the adoption of this paradigm change. This statement from the Society on personalized arthroplasty will serve as a reference that will evolve with time.

• Bone remodelling around a stem is an unavoidable long-term physiological process highly related to implant design. For some predisposed patients, it can lead to periprosthetic bone loss secondary to severe stress-shielding, which is thought to be detrimental by contributing to late loosening, late periprosthetic fracture, and thus rendering revision surgery more complicated.

• However, these concerns remain theoretical, since late loosening has yet to be documented among bone ingrowth cementless stems demonstrating periprosthetic bone loss associated with stress-shielding.

• Because none of the stems replicate the physiological load pattern on the proximal femur, each stem design is associated with a specific load pattern leading to specific adaptive periprosthetic bone remodelling. In their daily practice, orthopaedic surgeons need to differentiate physiological long-term bone remodelling patterns from pathological conditions such as loosening, sepsis or osteolysis.

• To aid in that process, we decided to clarify the behaviour of the five most used femoral stems. In order to provide translational knowledge, we decided to gather the designers’ and experts’ knowledge and experience related to the design rationale and the long-term bone remodelling of the following femoral stems we deemed ‘legendary’ and still commonly used: Corail (Depuy); Taperloc (Biomet); AML (Depuy); Alloclassic (Zimmer); and CLS-Spotorno (Zimmer).

Cite this article: EFORT Open Rev 2018;3:45-57. DOI: 10.1302/2058-5241.3.170024

• Over the years, with a better understanding of knee anatomy and biomechanics, superior implant designs, advanced surgical techniques, and the availability of precision tools such as robotics and navigation, a more personalized approach to total knee arthroplasty (TKA) has emerged.

• In the presence of extra-articular deformities, performing personalized TKA can be more challenging and specific considerations are required, since one has to deal with an acquired pathological anatomy.

• Performing personalized TKA surgery in patients with extra-articular deformities, the surgeon can: (1) resurface the joint, omitting the extra-articular deformity; (2) partially compensate the extra-articular deformity with intra-articular correction (hybrid technique), or (3) correct the extra-articular deformity combined with a joint resurfacing TKA (single stage or two-stage procedure).

• Omitting the acquired lower limb malalignment by resurfacing the knee has the advantages of respecting the joint surface anatomy and preserving soft tissue laxities. On the other hand, it maintains pathological joint load and lower limb kinematics with potentially detrimental outcomes.

• The hybrid technique can be performed in most cases. It circumvents complications associated with osteotomies and brings lower limb axes closer to native alignment. On the other hand, it creates some intra-articular imbalances, which may require soft tissue releases and/or constrained implants.

• Correcting the extra-articular deformity (through an osteotomy) in conjunction with joint resurfacing TKA represents the only true kinematic alignment technique, as it aims to reproduce native knee laxity and overall lower limb axis.