Aim. There is controversy regarding the use of Antibiotic-loaded cement (ALBC) as compared to non-antibiotic-loaded cement (NALBC) to reduce the overall infection rate without affecting implant survival or adding additional risks on fixation for primary total knee arthroplasty (TKA). Method. To conduct the analysis, we utilized the Catalan Arthroplasty Registry (RACat) for the TKAs implanted between 2005 and 2017. The primary variable recorded was the use of cement with or without antibiotics. Other recorded variables included were age, sex, diabetes mellitus, obesity, Charlson index and type of hospital. We analyzed the effect of ALBC vs. NALBC in reducing the risk of prosthetic infection at 3, 6, 12, and 24 months as well as prosthetic survival due to mechanical causes at 1, 5, and 10 years. Univariate and multivariable analyses of risk factors were conducted. Thereby, an interactive predictive model that determines the risk of prosthetic infection based on each patient's characteristics was created. Results. A total of 28,287 TKAs from the RACat were analyzed. In that total, there were 19,788 NALBC and 8,499 ALBC. The infection rates for TKAs with NALBC vs. those with ALBC at 3, 6, 12, and 24 months were respectively: 1.69% vs. 1.39% (p=0.132); 1.81% vs. 1.56% (p=0.147); 2.14% vs. 1.73% (p=0.030); 2.51% vs. 1.86% (p=0.001). A statistically significant reduction in periprosthetic infection rate was observed in the ALBC group at 12 and 24 months. No differences were observed between the two groups in terms of prosthetic mechanical survival. Being younger, male and having had previous knee surgery or having a high comorbidity index all led to a higher risk of prosthetic revision due to infection. Conclusions. The use of ALBC as a fixation method for TKA leads to a reduction in the risk of prosthetic infection without altering the mechanical survival of the implant. The creation of a predictive model helps determine the individualized risk of prosthetic infection based on the patient's characteristics

Aim. Despite a preoperative workup with no evidence to suspect a prosthetic joint infection (PJI) before revision surgery, routinely obtained intraoperative cultures still can be unexpectedly positive. The purpose of this study was (1) to assess the incidence of unexpected positive intraoperative cultures in presumed aseptic knee and hip revisions and (2) to determine whether a difference exists between the infection-free implant survival rate of patients with and without unexpected positive intraoperative cultures. Method. We selected patients who underwent a one-stage revision total knee arthroplasty (TKA) or total hip arthroplasty (THA) for different reasons. Three or more separate intraoperative cultures were obtained during each procedure. A negative result was defined as less than two positive cultures with the same microorganism. An unsuspected PJI was defined as having two or more positive cultures with the same microorganism. Patients’ medical records were reviewed to collect demographics, preoperative laboratory results, culture results, and the occurrence of infection during follow-up. Results. A total of 340 and 339 patients with a presumed aseptic knee and hip revision, respectively, were analyzed. The incidence of unsuspected PJIs was 7.9% and 12.1% in the knees and hips, respectively. Of these unsuspected PJIs, the infection-free prosthetic survival rate at 2 year follow-up was 88% (95%CI 59–97) and 92% (95%CI 73–98) in knees and hips, respectively. In the knee group, the infection-free prosthetic survival rate of patients with an unsuspected PJI was significantly lower compared to that of patients with negative intraoperative culture results (88% (95%CI 59–97) versus 97% (95%CI 93–99) with p=0.01). In the hip group, there was no such a difference (92% (95%CI 73–98) versus 93% (95%CI 88–96) with p=0.41). Conclusions. We found incidences of unsuspected PJI and infection-free prosthetic survival rates that are comparable with previous studies. During follow-up after one-stage revision TKA, a higher incidence of infection was observed in patients with an unsuspected PJI. This difference was not observed in the hip revisions

Background. The clinical benefit of chronic suppression with oral antibiotics as a salvage treatment for periprosthetic joint infection is unclear. The purpose of this study was to compare infection-free prosthetic survival rates between patients who received chronic oral antibiotics and those who did not following irrigation and debridement with polyethylene exchange or two-stage revision for periprosthetic joint infection. Methods. We reviewed the records on all irrigation and debridement procedures with polyethylene exchange and two-stage revisions performed at our institution from 1996 to 2010 for hip or knee periprosthetic joint infection. Of 625 patients treated with a total of 655 eligible revisions, ninety-two received chronic oral antibiotics for a minimum of six months and were eligible for inclusion in our study. These patients were compared with a matched cohort (ratio of 1:3) who did not receive chronic oral antibiotics. Results. The five-year infection-free prosthetic survival rate was 68.5% (95% confidence interval = 59.2% to 79.3%) for the antibiotic-suppression group and 41.1% (95% CI = 34.9% to 48.5%) for the non-suppression group (hazard ratio = 0.63, p = 0.008). Stratification by the type of surgery and the infecting organism showed a higher five-year survival rate for the patients in the suppression group who underwent irrigation and debridement with polyethylene exchange (64.7%) compared with those in the non-suppression group who underwent irrigation and debridement with polyethylene exchange (30.4%, p < 0.0001) and a higher five-year survival rate for the patients in the suppression group who had a Staphylococcus aureus infection (57.4%) compared with those in the non-suppression group who had a Staphylococcus aureus infection (40.1%, p = 0.047). Conclusions. Chronic suppression with oral antibiotics increased the infection-free prosthetic survival rate following surgical treatment for periprosthetic joint infection. Patients who underwent irrigation and debridement with polyethylene exchange and those who had a Staphylococcus aureus infection had the greatest benefit

The objective of this study was to compare the results of two consecutive series of patients with either intra-medullary uncemented stems (UCS) distal femoral endoprosthetic replacement or the Compress. ®. (CMP) distal femoral implant. Patients were divided into two groups: those who received UCS prosthesis (Group-1: 54 patients) and those who received CMP prosthesis (Group-2: 42 patients).The most frequent diagnosis was osteosarcoma. Age and gender were similar both groups. In Group-1, at a mean follow-up of 144 months, 37 prostheses were still in place. The overall Kaplan-Meier prosthetic survival rates were 79% at five and 62 % at ten years. Most of failures were long term complications. Aseptic loosening was the primary cause of late prosthetic failure. On Cox regression analysis, prosthetic stem diameter under 13mm was a significant negative prognostic factor for prosthetic survival (p=0.016). In Group-2, at a mean follow-up of 84 months, 36 prostheses were still in place. The overall rate of CMP prosthesis survival was 86% at 5 years. All complications were during the first postoperative year, being femoral fracture the main revision cause. The patients who retained the prosthesis had mainly good or excellent MSTS functional results in both groups

Introduction. Periprosthetic joint infection (PJI) represents the costliest complication in Orthopedics. Studies of mixing vancomycin to bone graft at Impaction Bone Grafting (IBG) have shown high local concentration for 3 weeks. Patients and methods. 55 consecutive revisions PJI, age 68 (SD 10.9), (9 one-stage and 46 two-stage) were retrospectively analyzed. All cases were revised using IBG. Most cases had vancomycin mixed in graft or added locally in joint. All had bone cement containing Gentamycin and Vancomycin. Follow up 2–16 years included clinical Merle d'Aubigne-Postel score, radiology and laboratory tests. We analyzed surgical time, bleeding, hospitalization time, infection eradication and prosthetic survival for one- and two-stage revision procedures. One patient was lost to follow up and 6 died (2 one- and 4 2-stage) before 2 years. Values are mean and SD. Analyses done by students t-test. Results. Preoperatively scores for 1- and 2-stage groups were 11.7 (0.79) and 10.2 (1.27) respectively. Follow up scores were 17.5 (0.38) and 15.9 (0.73) respectively. Total intra-operative blood loss (ml) for one- and two-stage procedures were 1638 (780) and 2764 (828) respectively p<0.05. Total surgery time (minutes): 238 (206) and 409 (108) respectively p<0.05. Total hospitalization time (days): 13 (6.2) and 34 (13) p<0.05. Radiology at follow-up showed no signs of PJI, signs of mechanical loosening in one. There were no persistent or new PJI, no revision for mechanical loosening. Two revision for any reason in the 2-stage and one in the 1-stage group. Five reoperations without component exchange for periprosthetic fracture, all in the 2-stage group. Conclusion. No mechanical loosening and no persistent or new PJI are favourable results. Blood loss, hospitalization- and surgery-time were substantially increased for the two-stage group. Muscle atrophy, osteoporotic development and decrease general physical condition are all well-known side effects of two-stage procedure. Revision one-stage hip PJI using IBG avoids increased suffering and resources connected to the two-stage procedure. Literatures have not shown eradication of PJI, to be clearly superior after two- compared to one-stage procedures. Reconstitution of bone defects and the possibility of very high local antibiotic concentration are substantial advantages when using IBG. We recommend a careful one-stage IBG procedure using antibiotic loaded graft for none “difficult to treat” cases

Aims

The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases.

Aims

The proximal tibia (PT) is the anatomical site most frequently affected by primary bone tumours after the distal femur. Reconstruction of the PT remains challenging because of the poor soft-tissue cover and the need to reconstruct the extensor mechanism. Reconstructive techniques include implantation of massive endoprosthesis (megaprosthesis), osteoarticular allografts (OAs), or allograft-prosthesis composites (APCs).

Oxford Unicompartmental knee arthroplasty (UKA) is now performed using a minimally invasive surgical (MIS) technique. Although early results are encouraging, the studies assessing outcome could be criticised for the restricted number of patients and limited follow-up. Aim of this study was to assess clinical outcome and prosthetic survival rate inpatients with minimally invasive Oxford medial UKA. This prospective study assessed 500 consecutive patients, who underwent cemented Oxford UKA for medial OA using MIS technique. Patients were assessed using objective and functional Knee Society Score (KSS). This study has confirmed preliminary findings that Oxford UKA using a minimally invasive approach is safe, reliable and effective

In this review of a limited series of 24 hip replacements done over a six-year period is reviewed, the rationale and theoretical motivation are discussed and the results reported. The mean follow-up is 30 months (10 to 66). There were twice as many male as female patients. Their mean age was 46.8 years. Results were scored on a Charnley/D’Aubigne system. There were technical difficulties but they were not insurmountable. Disciplined preoperative planning is required. The results are promising but some questions remain about long-term effects of metal debris and long-term prosthetic survival

Haemophilia care has steadily improved over the years and especially so during the last decade. The routine use of prophylactic treatment has undoubtedly resulted in a significant improvement in the life-style, quality of life and life expectancy of these patients. However despite our best efforts there is still a group of young adults who have a severe degree of knee joint destruction as a result of repeated articular bleeding episodes during their early years. The knee is the most common joint affected in haemophilia (50%). The repeated articular bleeding episodes during the patients' early years leads to the onset of pain and significant functional disability at a time when they require the best possible quality of life. The major objective of total joint replacement is to reduce the level of pain in the affected joint and, in addition, a significant reduction in the frequency and number of joint bleeds, which improves both function and mobility. The results of 60 primary total knee replacements performed in 42 patients with severe haemophilia between 1983 and 2003 were reviewed retrospectively. Functional results were assessed using the Hospital for Special Surgery (HSS) knee score both pre- and post-operatively. Kaplan-Meier survivorship analysis was used to calculate prosthetic survival. The mean age of patients was 43.35 (range 25-70yrs). The overall prevalence of infection was less than 2%. The HSS clinical score was excellent or good for 95% of the knees. We believe that total joint replacement is a safe and effective procedure in the management of haemophilic joint arthropathy. The latest techniques using continuous infusion and recombinant factor replacement have gone a long way to reducing the complications rate and to achieving results that match those of the general population

Purpose: To review short-term results in 25 patients that underwent total ankle replacement with implantation of a second generation prosthesis. Materials and methods: We reviewed 25 patients with ankle arthritis treated by total ankle replacement (TAR). Mean age of the patients was 58.2 years and mean follow-up 29.5 months. The cause of arthritis was posttraumatic in 17 cases. In all cases a HINTEGRA prosthesis was implanted. In 6 cases Achilles tendon lengthening was also performed. Review was carried out by anamnesis, clinical examination and radiological control. The ankle and hindfoot AOFAS scale was used to quantify clinical and functional results. Results: Mean AOFAS score improved from 24.0 to 80.1 points. No significant differences were found between cases of traumatic and non-traumatic origin. Pain was the parameter with the best evolution. Mean ankle mobility went from 19° to 26°. Five cases required revision surgery: 2 ankle arthrodeses due to prosthetic loosening, 2 Achilles tendon lengthenings and one release of tibio-talar impingement. Prosthetic survival rate at 29.5 months’ follow-up was 92%. All patients, except for the 2 cases that required arthrodesis, were satisfied or very satisfied. Conclusions: Total ankle replacement is an effective method for the treatment of ankle arthritis. Short term results are similar or better than those seen with arthrodesis

Aims

Intraoperative pressure sensors allow surgeons to quantify soft-tissue balance during total knee arthroplasty (TKA). The aim of this study was to determine whether using sensors to achieve soft-tissue balance was more effective than manual balancing in improving outcomes in TKA.

Acetabular revision in patients with bone deficiency is often difficult because of the poor quality and quantity of the acetabular bone stock. The purpose of this study was to evaluate the midterm clinical and radiographic outcomes of acetabular revision with use of an impaction bone-grafting technique and a cemented polyethylene cup. Results: thirty consecutive acetabular revisions were performed with impaction bone-grafting and use of a cemented cup in twenty-eight patients with bone deficiency. The average age at the revision was sixty-eight years. The minimum duration of follow-up of all reconstructions that were still functioning or that were followed until the time of death was three years (mean, 8.1 years; range, three to fifteen years). The acetabular bone defects were classified as cavitary in fifteen hips and as combined segmental-cavitary in fifteen hips according to AAOS classification. One hip had a repeat revision. Radiographic analysis that had not been revised showed loosening in four hips. All these four hips were treated by bulk bone graft covering more than 50% of cups. Kaplan-Meier analysis demonstrated a prosthetic survival rate, with aseptic loosening as the end point, of 72% at fourteen years and, with revision as the endpoint, of 100% at ten years and 83% at fourteen years. Impaction bone-grafting was an excellent option to manage acetabular revision surgery. However, excessive bulk bonegraft should not be used

We reviewed our experience with diaphyseal endoprostheses to determine the survival of this type of reconstruction and factors affecting that survival. Method: We retrospectively studied 44 patients who underwent endoprostheticreconstruction of diaphyseal bone defects after excision of primary sarcomas between 1979 and 2002 with more than 2 years follow up. Results: There were 27 males and 17 females, the median age at diagnosis was 25 years (8–75) and the median bone defect was 18cm (10–27.6).There were 33 femoral reconstructions, 6 tibial and 5 humeral. The cumulative overall survival for all patients was 67% at 10 years and prosthetic reconstruction using revision surgery as an end point was 62% at 10 years. The cumulative risk offailure of reconstruction including; infection, fracture, aseptic loosening, local recurrence and amputation was 45% at 10 years but for amputation only was 13% at 10 years. The patient age, the type of prosthesis ;whether cemented oruncemented, site of defect (femur, tibia, and humerus) and length of defect did not influence prosthetic survival. Conclusion: We concluded that the use endoprostheses for reconstruction of diaphyseal bone defects remains a valuable method of reconstruction with predictable results and compares favourably with other forms of reconstruction of massive diaphyseal bone defects

Limb-sparing surgery has become the preferred surgical treatment of malignant bone tumours of the knee. In patients with intra-articular extension of their tumour, extra-articular limb sparing surgery can prevent the knee from amputation. In a retrospective study between January 1985 and December 2007, we performed 34 extra-articular tumour resections of the knee-joint for a bone- or soft tissue tumour in the distal femur or proximal tibia with (suspect) intra-articular tumour extension into the knee on MRI. Contra-indications were extension of the tumour into the extensor mechanism and/or tumour involvement of the neurovascular bundle. Osteosarcoma (23/34) was the most common primary malignancy. Mean age was 36 years (17–70) and the mean follow up was 9 years (1–19). Patient survival rates at 5 years and 10 years are 78% and 58% respectively, mean patient survival was 47 months (8–211). In 12 (35%) patients, the primary implanted prosthesis failed during follow up. Prosthetic survival rates including minor revision surgery were 63% at 5 years and 36% at 10 years. Six (18%) patients had local recurrence of their malignancy, 5 of them in the popliteal fossa. Local recurrence was significantly correlated with marginal margins (P< 0.05). Fifteen patients had major complications (44%) mainly deep infection in proximal tibia resections and aseptic loosening in distal femur resections. Aseptic loosening was significantly correlated with non HA-coated stems (P< 0.05). Functional outcome scores according to MSTS (mean 81, (65–93)) and TESS (mean 85, (56–98)) of survivors are good. Our results suggest that extra-articular tumour resections of the knee-joint can provide a functional endoprosthesis and can be an alternative for primary amputation. However it is a technical demanding procedure with acceptable local recurrence and high complication rates in patients with, in general, poor survival

A retrospective study focusing on long-term follow up of 28 patients with a malignant bone tumour in the distal femur was conducted. Patients with a mean age of 50 (18–90) were clinically and radiologically followed-up for a mean period of 64 months (7–144). Osteosarcoma was the most common primary bone tumour, occurring in 15 patients. The 5-year survival for all patients was 80,9%. At final follow-up, 19 patients were still alive and had a mean follow up of 74,6 months (7–137). Clinical evaluation was done with the MSTS questionnaire (mean score: 70,0 (26,7–93,3)) and the use of the TESS (mean score: 82,5 (45–99,2) and SF-36 (mean Physical Component Score (PCS): 46,6 (27,1–56,5), mean Mental Component Score (MCS): 53,7 (range 37,0–62,1) was introduced. There were 12 complications: 5 aseptic loosenings, two deep prosthetic infections, two luxations, one prosthetic fracture and two fissures. Six failures were re-operated. An overall prosthetic survival at 5-years of 77,0 % was found. A total of eight (29%) prostheses were considered to have failed after a mean follow up of 27,4 months (0–97). Risk factors in failure of the prosthetics were: non HA-coated stem and top stem-ratio > 1.2. Not length of the endoprosthesis and base stem-ratio. The top-ratio had a mean value of 1,14 (1,00–1,52) and for the four patients with an aseptic loosening the mean top-ratio was 1,23 (1,12–1,51) which was significantly different (p< 0,05 Mann-Whitney U test). Our results suggest that of the MUTARS endoprosthesis has a good 5-year survival. The use with a HA coating is preferable. The use of a stem-cortex ratio (> 1.2) at the top of the prosthetic stem can be predictor for aseptic loosening. The addition of the TESS and SF-36 scores give more insight information in how patients undergo their disease: half do not feel disabled

Background. Modular endoprostheses today represent a standard treatment option in the management of musculoskeletal tumors of the lower extremities. Long-term results of these reconstructions, however, are often limited by the course of the underlying disease. We therefore report our experiences in cancer patients with megaprostheses of the lower limb after a minimum of 15 years. Materials and Methods. 62 patients, 34 men and 28 women, with a mean age of 26 years (median, 20; range, 6–83) were included in this investigation with a mean follow-up of 230 months (median, 228; range, 180–342). Endoprosthetic reconstructions of the proximal femur (11), the distal femur (28), the total femur (2) or the proximal tibia (21) were indicated for osteosarcoma (43), chondrosarcoma (5), malignant fibrous histiocytoma (3) or other tumors (11). All patients have received either a KMFTR (22) or a HMRS (40) modular prosthesis; 23 patients had a muscle flap, 14 had a fibular transposition osteotomy and 4 have received an artificial LARS ligament for soft-tissue reconstruction. Results. 7 patients (11.3%) died throughout the follow-up period, but none succumbed to primary disease. One patient (1.6%) developed a local recurrence after 31 months that was resected. Overall, 56 patients (90.3%) underwent revision of their prosthesis; 50 (80.7%) had multiple revisions up to a maximum of 12 operations (mean, 3 per patient). The median overall prosthetic survival to first revision was 40 months; the corresponding 5-, 10- and 15-year survival rates were 35.5%, 14.5% and 12.9%, respectively. 3 patients (5.4%) had an infection, 8 (14.3%) had a soft-tissue related failure, 30 (53.6%) had a mechanical or structural failure and 15 (26.8%) had an aseptic loosening. The 15-year survival rates of these respective endpoints were 87.1% for infection, 79.0% for soft-tissue related failure, 32.3% for mechanical or structural failure and 56.5% for aseptic loosening. 59 patients (95.2%) have retained their prosthesis; 2 patients (3.2%) underwent secondary amputation due to an irresolvable complication, another one (1.6%) for a second malignancy. Conclusion. Modular prosthetic reconstructions of the lower extremities have a high revision rate in the long-term, primarily due to mechanical failures. Given that patients survive their malignant disease the rate of secondary implant removal, however, tends to be low, providing satisfactory function and body integrity. Further advances in implant design, soft tissue management and infection prophylaxis are required to reduce revision rates

Purpose: Prosthetic arthroplasty is the most common method of reconstruction of segmental bone defects following resection of bone sarcomas about the knee. The purpose of this study was to determine the survivorship of the reconstructions in short- and long-term follow-up. Methods: A retrospective study was performed on all patients diagnosed with a bone sarcoma between 1984 and 1995 who were treated with a limb-sparing osteoarticular resection and rotating hinge prosthetic knee arthroplasty. Prosthetic survival was calculated with endpoints of analysis based on any event, any prosthesis-related event and aseptic loosening of the prosthesis, which led to prosthetic revision, removal or limb amputation. Results: A total of 154 reconstructions were performed involving the distal femur (n=111) and proximal tibia (n=43). The median resection length was 155 mm (105–250mm) for the distal femur and 117 mm (85–150 mm) for the proximal tibia. All implants were fixed with polymethylmethacrylate cement. Early complications (within one year postoperatively) developed in fewer than 2 % of patients. Aseptic loosening accounted for the majority of events resulting in prosthetic failures (distal femur = 17 [median failure 34 mos]; proximal tibia = 10 [median failure 100 mos]). Polyethylene bushing wear was observed in seven patients (median time to replacement = 156 months). Conclusion: The early outcome of prosthetic arthroplasty was extremely favorable supporting this method of reconstruction following excision of high-grade bone sarcomas about the knee. Long-term survival of these prostheses is suboptimal and can be anticipated to be poor for the proximal tibia. Aseptic loosening continues to be the primary cause of prosthetic failure about the knee

We report the outcome of 135 knees with medial compartment osteoarthritis treated by Oxford meniscal-bearing unicompartmental arthroplasty. They have been performed in a Distict General hospital by a single surgeon. All the knees had an intact anterior cruciate ligament, a correctable varus deformity and the lateral compartment was uninvolved or had minor osteoarthritic changes. At review 29 knees were in patients who had died and 106 were in those who were still living. The mean elapsed time since operation was 5.82 years (range 2–12 yrs). Using revision as the end point the outcome for every knee was established. Five knees have been revised, giving a cumulative prosthetic survival rate at ten years of 94.04% (95% confidence interval 84.0 to 97.8). The causes for revision were aseptic loosening in three, progressive valgus deformity in one and dislocation of the bearing in one. Knee rating and patient function were assessed using the modified Knee Society Scoring system. The mean Knee score was 92.2 (51–100), and mean Functional score was 76.2 (51–100). 90% of the patients did not require blood transfusion. Two patients had deep vein thrombosis and three knees had superficial wound infection that responded to antibiotics. Intraoperatively, one patient had fracture of the proximal tibia which was fixed with two partially threaded cancellous screws. 92% of patients were fully satisfied with the procedure and 91% of them said that they would undergo a similar procedure in the opposite knee. The implant survival is comparable to that reported by the designers of the prosthesis and not significantly different from those for total knee replacement. Uni-compartmental knee replacement with all its advantages offers a viable alternative in patients with medial gonarthrosis. Appropriate patient selection and good surgical technique are the key factors

Maltracking or subluxation is one of the complication of patellofemoral arthroplasty (PFA). The purpose of this investigation was to measure femoral component rotational alignment in PFA using a standard computed tomography (CT) scanner. Second, apply this technique to two groups; a control group of patients with well functioning PFA and a study of a group of patients with patellofemoral problems as maltracking or subluxation. Data was analyzed from our center that has continuously performed PFA for isolated patellofemoral degenerative disease since 1978. Patients were included if they had a minimum four year follow up. A total of 124 patients (149 knees) were treated with PFA. There were 39 men and 85 women who had a mean age of 64 years (range, 46 to 78 years). A pre-operative and post-operative CT scan is performed in our center for all the patients since this period to assess femoro-patellar malalignment. The trochlear twist angle was determined using the single axial CT image through the femoral epi-condyles. To determine whether the femoral component was in excessive internal or external rotation, measurements were done on the post-operative CT scan and the trochlear twist angle of the femoral component was compared to the pre-operative trochlear twist angle. At a mean follow up of 13 years (range, 4 to 30 years), overall prosthetic survival and preservation was 91 per cent. There were 112 knees (75 per cent) with good or excellent clinical results (Knee Society score of 80 points or more). Revision to total knee replacement for femoro-tibial disease progression was necessary in 9 knees (6 per cent). Complications related to the patellofemoral arthroplasty (28 knees) included : residual pain or mechanical symptom 10 (7 per cent) requiring other ancillary procedures ; maltracking or subluxation 18 (12%) with component revision in 10 knees; Radiographic findings show 2 component loosenings and 1 patella fracture. There was no incidence of infection or component wear. The group with patellofemoral complications had excessive (p less than 0.01) femoral internal component rotation. This excessive combined internal rotation was directly proportional to the severity of the patellofemoral complication. Small amounts of internal rotation (1–4 degrees) correlated with pain. Moderate combined internal rotation (5–10 degrees) with lateral tracking and patellar tilting. Large amounts of combined internal rotational (10–17 degrees) correlated with patellar sub-luxation, early patellar dislocation or late patellar prosthesis failure (fracture of the patella or loosening of the patella button). The control group (112 knees without complications) was in external rotation (10-0 degrees). This study showed that increasing amounts of excessive internal rotational malalignment resulted in more severe patellofemoral complications