KNEE ARTHROPLASTY Total knee arthroplasty with rotating-hinge Endo-Model prosthesis: clinical results in complex primary and revision surgery F. Sanguineti • T. Mangano • M. Formica • F. Franchin Received: 4 May 2014 / Published online: 2 September 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Introduction Rotating-hinge knee implants are highly constrained devices able to provide the stability needed for arthroplasty in case of severe bone loss and complex instability. Notable doubts still exist in using rotating-hinge devices, mainly due to risk of mechanical failure and risk of infection. Materials and methods We retrospectively evaluated the functional and clinical outcomes in a series of patients treated with the rotating-hinge Endo-Model prosthesis either for primary or revision total knee arthroplasty. Between 1997 and 2009 we implanted 123 Endo-Model prosthesis (118 patients) at our institution. At the time of this study we could evaluate 45 prosthesis (25 primary and 20 revision TKAs) from the clinical and radiological site, with average follow-up of 42.2 months. Results During the follow-up period, three patients reported complications, which in two cases finally led to revision with explantation. Mean survival of the implants attested at 93.3 %. The average post-operative clinical Knee Society score in the evaluated series was 94.2, the functional one 78.7. The average range of motion was 0°– 108°. No signs of joint instability or misalignment were noted. Pain was present in a minority of patients, but always at a mild/occasional extent. No evidences of loos- ening or implant failure have been reported. No substantial divergences in the outcomes have been found across dif- ferent patient categories after stratification in agreement with the Knee Society. Conclusions Coherent with previously published works, we confirm the Endo-Model prosthesis to provide excellent pain relief, restoration of walking capacity and intrinsic knee stability both in complex primary and in revision knee arthroplasty, with good or excellent results in the majority of patients and acceptable complication rate. Keywords Total knee arthroplasty Á Endo-Model Á Rotating-hinge Á Revision knee surgery Á Primary knee arthroplasty Introduction Constraint is defined as the effect of elements of the knee implant design that provide stability needed in presence of a deficient soft tissue envelope. The choice of an adequate constraint degree, while planning a total knee arthroplasty, represents one of the fundamental factors upon which the successful outcome depends [1, 2]. In severely affected knee with serious bony and ligamentous defects, a high constrained total knee device represents a treatment option able to restore and maintain the correct anatomical axis as well as to confer the joint stability impossible to obtain with lower constraint implants [3]. Rotating-hinge designs are described to deal with such instances of severe loss of bone stock, gross ligamentous instability, combined deformities, oncologic surgery and salvage situations both in primary and revision surgery. By mean of the rotational degree of freedom and design features these implants provide high constraint and great inherent stability while avoiding patellofemoral instability and torsional stresses to load at the prosthesis/cement/bone interface [1, 3]. This finally leads to longer survival and better clinical outcomes F. Sanguineti Á T. Mangano (&) Á M. Formica Á F. Franchin Department of Orthopaedics and Traumatology, University of Genova, School of Medicine, Padiglione 40, Largo Rosanna Benzi 10, 10132 Genova, Italy e-mail: twmangano@gmail.com 123 Arch Orthop Trauma Surg (2014) 134:1601–1607 DOI 10.1007/s00402-014-2061-1