132 surgeons of the same orthopaedic division. Compared with the majority of studies, in which a series of prostheses implanted by a single surgeon is usually reported, partici- pation of several independent surgeons in this study pro- vided a greater possibility for data reproducibility. Materials and methods This was a prospective case series of 233 TKA performed from 1993 to 1998 by various surgeons, using random rotation, in 197 patients (36 bilateral), with PFC ﬁxed- bearing prostheses. Indications to surgery were: 170 (72.9%) patients with knee arthritis with varus–valgus axial deviation \10 , 27 (11.6%) with rheumatoid arthritis, 16 (6.9%) with knee arthritis associated with varus–valgus axial deviation [10 , 11 (4.6%) with arthritis following tibial osteotomy, eight (3.6%) with consequences of tibial plateau fractures and one (0.4%) with failure of unicom- partmental prosthesis. Surgical technique and protocols All surgeries were conducted with the patient under general or spinal anesthesia using the same technique and the medial parapatellar approach and capsulotomy, with ischaemic limb (pneumatic tourniquet at 300 mmHg). After removing osteophytes and cruciate ligaments and after a partial release, the distal femoral cut was performed using an intramedullary guide. The cut, with a variation from 0 to 9 , was based on the angle measured in pre- operative planning [6]. Thereafter, the ligamentous balance was completed, and the tibial cut was performed. The deﬁnitive implant was cemented after choosing a polyeth- ylene liner of appropriate size and after evaluating the range of motion and ligamentous balance. The technique for selective resurfacing was chosen for treating the patella [7]: patellar substitution only in cases of severe cartilage damage, serious deformity and wrong- racking; patellar conservation in the remaining cases. The PFC system offers the choice of either posterior cruciate ligament substitution or retention [8, 9]. All implants were posterior cruciate ligament substituting. The prosthesis also allows the use of a femoral or tibial stem when an augmented stability is required. All patients received an antibiotic prophylaxis approximately 1 h before surgery with a single dose of a single antibiotic and an antithromboembolic with low molecular weight heparin for 30 days. Clinical evaluation 123 The Hospital for Special Surgery (HSS) knee score ques- tionnaire was used for clinical evaluation [10]. Patients J Orthopaed Traumatol (2011) 12:131–136 underwent clinical evaluation at the outpatient departments dedicated to prosthetic surgery. Evaluation was conducted prior to and after implantation at 3 and 6 months and then annually. In addition, personal identiﬁcation data, con- comitant pathologies and complications that occurred after implantation were recorded. When poor conditions of general health or a long distance from the place of resi- dence made the transfer of clinical and radiographic control at our hospital not possible, patients responded to a tele- phonic questionnaire. This is in agreement with the liter- ature that supports the quality of data obtained using the telephonic method [11]. Radiographic evaluation The Knee Society Roentgenographic Evaluation System [12] was used with the objective of obtaining a stand- ardised radiographic evaluation. All patients had an immediate postoperative radiographic control in the operating room, followed by a deﬁnitive radiographic evaluation with weight bearing in the anteroposterior (AP) and laterolateral (LL) projections at the same time as the clinical evaluations. X-rays were studied to observe implant position, alignment angle (a, b, c and d), eventual signs of periprosthetic fractures, mobilisation or loosening and the presence of osteolytic areas. Radiolucent lines were recorded (deﬁning radiolucent lines as the distance of the bone–prosthesis interface [2 mm). These lines were subdivided into not progressive, which indicates lack of mobilisation; and progressive, which is a sign of probable implant loosening. The analysis was performed on digitised X-rays present in our hospital’s database and on the ﬁlms produced by the patient, for X-rays taken in other hospitals. Statistical analysis and failure evaluation All data were collected in perspective through a dedicated computer programme created to manage prosthetic fol- low-up. This programme also allowed collection of radiographic parameters and successive statistic analysis. Clinical and radiographic data were analysed using means, standard deviations (SD) and conﬁdence intervals (CI). Statistical signiﬁcance for all data was set at P \ 0.05. The Kaplan–Meier method with two different endpoints was performed for survivorship analysis: The ﬁrst endpoint was prosthetic revision to provide a total evaluation of implant survival. An HSS score of 60 points was chosen as the second endpoint to give importance to patient satisfaction. Differences in cumulative survivor- ship in the patellar replacement group and the group with no patellar replacement were evaluated using the log-rank test.