Introduction. High flexion knee arthroplasties have been designed to allow up to 155 degrees flexion and enable high flexion activities such as kneeling and squatting. To date randomised controlled trials have shown no difference in range of movement (ROM) between high flexion and standard designs. Objectives. The aim of this study was to determine if there is a difference in functional outcome and ROM between the standard and high flexion design of the PFC Sigma TKA system. Methods. 84 patients with the diagnosis of osteoarthritis undergoing primary total knee arthroplasty were randomised to receive either a PFC Sigma or PFC Sigma RP-F total knee arthroplasty. ROM, Oxford Knee Score, Knee Society Score, Patella score and SF-12v2 were assessed independently before and at one year after surgery. Patients were blinded to the implant they received. Results. 42 patients in each group were included in this study and underwent surgery. 77 patients (92%) completed their one-year follow-up. There was no statistically significant difference in preoperative scores between groups. At one year there was a statistically significant difference in ROM between the groups with a mean of 105 degrees in the PFC Sigma and 114 degrees in the PFC Sigma RP-F group (p=0.01). There was also a statistically significant difference in flexion with 106 degrees and 115 degrees respectively (p=0.007). The difference in improvement in ROM and flexion was also statistically significant between the groups (p=0.009 and p=0.008). There was no statistically significant difference in any of the functional outcome scores. Conclusions. This is the first randomised controlled trial to show a statistically significant difference in ROM and flexion between a standard and a high flexion design TKA. Further follow-up will be carried out to determine if these differences persist over time and to evaluate the long-term survival of the different designs

The PFC Sigma Cobalt Chrome Sigma (PFCSCC) was introduced in 2006, an update of the PFC Sigma designed to reduce backside wear. To help identify any significant early failures following its introduction, we prospectively identified all recipients over a one-year period. The patient's clinical, demographic and radiographic data, American Knee Society scores (AKSS), Oxford Knee scores (OKS) and SF-12 scores was recorded pre-operatively and at one, three and five years. 233 patients underwent 249 primary knee arthroplasties with the PFCSCC. Seventeen patients (19 knees) died and 29 patients (30 knees) were also lost to follow up at the five year point. The mean age was 66.6 (34–80) with 47.6% of the cohort being male. The mean five year follow-up was 1836 days (1530–2307). Five knees (2.2%) were revised for infection and three were revised for pain. The 5–year cumulative survival rate was 96.6% for any failure and 98.6% for aseptic failure. AKSS 32.6 (0–86.6) preoperatively, 80.7 (29–95) 5 years P < 0.001. OKS was 39.0 (22–53) preoperatively, 23.5 (4.7–42.3) 5 years P < 0.001. These results demonstrate a good early survivorship when compared to the old design PFC Sigma, however further follow-up to ten years is required

Introduction: The Depuy Pressed Fit Condylar (PFC) total knee arthroplasty (TKA) is well established with reported 10-year survival rates of 93–97%. The PFC was modified, leading to the introduction of the Sigma TKA in 1997. The theoretical advantages of the Sigma system include increased contact area between the femoral component and the tibial insert. We report the first 5-year clinical and radiographic follow-up data for the Sigma TKA. Methods: Over a ten-month period, 211 Sigma TKAs were performed in 179 patients. Patients were seen at a specialist nurse-led clinic at admission and at 6 months, 18 months, 3 years and 5 years after surgery. Data were recorded prospectively at each visit. Radiographs were obtained at the 5-year follow-up appointment. Results: Of 211 knees, 187 (150 patients) were alive at 5 years. 5 were lost to follow up. 5 knees (2.4%) were revised: 4 for infection and 1 underwent change of polyethylene insert at 4.9 years. 5-year survival with an endpoint of revision for any reason was 97.4%; with an endpoint of revision for aseptic loosening it was 99.5%. The median American Knee Society score was 93/100 at 5 years compared with 25/100 at admission. Of 145 radiographs, 17 (11.7%) showed radiolucent lines. None showed radiographic loosening of either component. 28 (19.3%) had alignment outside the range of 7±3° valgus. Discussion: These results suggest that the Sigma TKA gives excellent clinical results after five years. Further follow-up studies are required to see if this performance is maintained in the long term

The Depuy Sigma Total Knee Arthroplasty (TKA) was introduced in 1997 as a modification of the Pressed Fit Condylar (PFC) TKA. It is the most commonly used TKA in England and Wales, accounting for 34.9% of all primary TKAs performed in 2006. The PFC has reported 10-year survival rates of 90–95%. This study reports the first clinical and radiological outcomes at 7–9 years following TKA using the PFC Sigma prosthesis. Three hundred and eighteen consecutive Sigma TKAs were performed in 275 patients between October 1998 and March 2000. Patients were prospectively followed up in a specialist nurse-led clinic. Final review was performed in December 2007 or January 2008, i.e. 7–9 years post surgery. Outcome measures included American Knee Society Scores, Radiographic Scores and Oxford Knee Scores. Survival analysis was performed using the life table method. Of 318 Sigma knees, 225 (193 patients) were alive at 7–9 years. 6 knees in 5 patients were lost to follow up. 7 knees (2.2%) were revised: 6 for infection within the first two years and 1 at 59 months who underwent isolated change of polyethylene insert. The 9-year survival was 97.7% with revision for any reason as endpoint and 99.6% with revision for aseptic failure as endpoint. The mean American Knee Society Knee score was 84/100 at 7–9 years compared with 33/100 pre-operatively. 0f 140 radiographs, 48 knees had radiolucent lines but no knee showed radiological evidence of loosening. These results suggest that the Sigma TKA gives excellent clinical results up to 9-years

The DuPuy Sigma total knee arthroplasty (TKA) is a modification of the well-established Press Fit Condylar (PFC) TKA and is used extensively in the UK and worldwide. This study reports the first 10-year clinical and radiological follow-up data for the Sigma PFC. A total of 235 consecutive Sigma TKAs were performed in 203 patients between October 1998 and October 1999, in our unit. Patients were seen at a specialist nurse-led clinic 1 week before admission and at 6 months, 18 months, 3 years, 5 years and 7-10 years after surgery. Data was recorded prospectively at each clinic visit. Of 235 knees, 171 (147 patients) were alive at 10 years. Twelve were lost to follow up. Eight knees (3.4%) were revised; four for infection and four underwent isolated change of polyethylene insert. Ten-year survival with an end point of revision for any reason was 95.9%, and with an endpoint of revision for aseptic failure was 98.7%. The mean American Knee Society score was 62 at 8-10 years compared with 31 out of 100 pre-operatively. Our results show that the PFC Sigma knee arthroplasty performs well over the first 10 years post-implantation

This study reports the first 10-year clinical and radiological follow-up data for the Sigma PFC. The DuPuy Sigma total knee arthroplasty (TKA) is a modification of the well established Press Fit Condylar (PFC) TKA and is used extensively in the UK and worldwide. It is the most commonly used TKA in England and Wales, where it accounts for 34% of all primary TKA. A total of 235 consecutive Sigma TKAs were performed in 203 patients between October 1998 and October 1999, in our unit. Patients were seen at a specialist nurse led clinic 7 to 10 days before admission and at 6 months, 18 months, 3 years, 5 years and 7-10 years after surgery. Data was recorded prospectively at each clinic visit. Radiographs were obtained at the 5 year and 8-10 year follow-up appointment. Of 235 knees 171 (147 patients) were alive at 10 years. Twelve were lost to follow up. Nine knees (3.8%) were revised; five for infection and four underwent change of polyethylene insert. Ten-year survival with and end point of revision for any reason was 95.9%, and with and endpoint of revision for aseptic failure was 98.7%. The mean American Knee Society score was 62 at 8-10 years compared with 31 out of 100 pre-operatively. Of 109 radiographs, 47 knees had radiolucent lines but none showed radiological evidence of loosening. Our results show that the PFC Sigma knee arthroplasty performs well over the first 10 years post implantation

The aims of this study were to assess the clinical outcomes especially range of motion of the knee after total knee arthroplasty with sigma RP-F versus LCS RP. 110 knees underwent total knee arthroplasty with LCS, and 59 knees with PFC sigma RP-F. We performed a prospective clinical trial. At the time of the one-year follow-up, we compared the clinical outcomes of two groups. In LCS group, LCS AP glide type group was excluded. Range of motion, the knee score, functional score and HSS score etc. were assessed. 91 knees were available. The mean active non-weight-bearing range of motion at one year was 124 (95% confidence interval) in the fifty-six knees that underwent a LCS and 127 (95% confidence interval) in the thirty-six knees that underwent a PFC sigma RP-F (p=0.55). There were no significant differences in the knee score (the mean 94.12 in LCS, 93.54 in RP-F, p=050), functional score(the mean 62.58 in LCS, 65.14 in RP-F, p=0.91) and HSS score (the mean 87.73 in LCS, 87.85 in RP-F, p=0.50). Although PFC sigma RP-F has the design that is advantageous in knee flexion, we found no significant differences between the groups with regard to range of motion or clinical outcomes

This retrospective study evaluates the midterm results of the Rotating Platform PFC Sigma Total Knee Arthroplasty System. We reviewed 161 cases in 147 patients with an average follow-up of 5 years (4 to 7 years) operated on at our institution between June 2001 and June 2004. Patient outcomes were measured using the Oxford and American Knee Society Scores and radiographs underwent independent radiological evaluation. Average pre-operative Oxford Scores improved from 43(29-55) to 21 (13 - 44) postoperative;y and average Knee Society Scores improved from 57 (43-70) preoperatively to 80 (58-90) at last follow up. Range of movement improved from 91 degrees (70 - 110) to 113 degrees (75 - 130). There were 5 complications reported; one superficial infection treated with antibiotics, one patient required manipulation under anaesthesia at 3 months for post operative stiffness, which improved. There was one arthrotomy for dislocation of the bearing immediate postoperatively. There was one case of DVT and one non-fatal PE. There were no deep infections. The PFC Sigma Knee Rotating Platform system offers excellent mid-term results in our review

Aim: To report the intermediate clinical and radiological results of a consecutive series of knee arthroplasies using PFC Sigma endoprosthesis. Methods: 525 total knee replacements (469 patients) were performed from Aug 97 to Jun 01 using the PFC Sigma components. Cruciate retaining femoral component was used in 219 knees. All patients were prospectively followed up at 6 weeks, 3 months and yearly. Pre operative HSS knee scores and Oxford knee scores were compared with annual scores. Quality of life was assessed using SF12 questionnaire. Knee Society scores were used to assess the radiographs. The average follow up was 61 months (36–84). 11 patients lost to follow up. Results: Of the 469 patients, 64% were females. Mean age was 74.2 yrs(59–90). Valgus deformity of at least 10 deg was present in 87 (16.5%). Patella resurfacing was performed in 80.5%. A lateral release was performed in 20 patients. Post operative mobilisation was standardised in all patients. 34 patients developed radiologically proven DVT. 24 patients died to unrelated causes. 21 were lost to follow up. 16 (3%) patients developed superficial and 6 developed deep infection. 4 patients underwent revision surgery (3 – infection,1- catastrophic failure). The HSS scores improved from 29(16–65) to 86(59–97) at final follow up (p=0.004). Pre operative Oxford knee scores improved from 10(6–31) to 43(37–48) at last follow up (p=0.008). Radiological knee society score for the femur were less than 5 in 477/478 patients and 7 in 1 patient. The scores for the tibia were less than 5 in 475/478 patients and 6 in 3 patients. Average femoral flexion was 1– 9.2 deg (3.9), knee valgus angle 0.5 – 7.4 (3.5) degrees and the tibial slope was 3.1 deg(0–7.1). SF 12 health scores revealed a good functional outcome of both the physical and mental components. With failure defined as repeat revision because of aseptic loosening, the rate of survival at 5 years months was 99.1% and overall survival at 5 years with removal or repeat revision of any component for any reason as the end point was 97.5%. Conclusion: Our prospective study of patients with primary knee arthroplasties supports the use of the PFC Sigma total knee proshesis. Our results show excellent clinical outcome comparable with other prostheses. A longer follow-up is needed to establish the durability and longevity of this prosthesis given its excellent intermediate term results

Aim: PFC Sigma total knee was introduced in 1997 incorporating a number of design changes. We report our medium-term results of a consecutive series of PFC sigma knees performed between Nov 1997 and Dec 1998. Method: Between November 1997 and December 1998 a consecutive series of 166 TKAs (156 patients)were carried out using the PFC Sigma total knee replacement system at Wrightington Hospital. Out of the 156 patients 9 were lost to follow-up. This left 147 patients (156 knees) with a mean follow-up of 90 months (range 84 – 96 months). 137 patients (88%) had primary osteoarthritis, 14(9%) had R.A and 5(3%) had post-traumatic arthritis. The mean age was 70 yrs (53 – 88 yrs).85 were female and 62 male. All patients were followed at 3 months, 6 months,1 year and then yearly. Clinical evaluation was done by American Knee Society and Oxford knee scores. Knee society score was used to assess the postoperative radiographs. Results: The mean Knee society score improved from the preoperative mean of 45 (range 30 – 65) to postoperative mean of 84 points(range 45 – 92). The mean preoperative functional score was 38(range 25 –5) and mean postoperative functional score was 73 points(range 50–95). According to the final scoring 90 % of the knees were rated excellent, 4% good, 4 % fair and 2 % poor. The mean preoperative Oxford knee score was 43 (range 33–52) and mean postoperative score was 17 (14–29). Range of motion improved from a mean of 90(range 50–125) to 105(range 65–130). There was no significant difference (p = 0.03) in the American Knee Society score and Oxford knee score when comparing patients with and without resurfacing of the patella and PCL-retaining with PCL-substituting implants.1 knee (0.6%) was revised within 18 months due to aseptic loosening.1 knee(0.6%) had superficial wound infection which cleared with oral antibiotics.2 patients(2 knees) developed deep infection out of which one resolved following early debridement, the other developed chronic infection requiring long term suppressive antibiotics. 3 patients had proven below knee deep venous thrombosis; one of them developed a non-fatal pulmonary embolism. Radiological review using radiological knee society scoring showed radiolucent lines under 35 % of the tibial components(56 knees)and 11 % of Femoral components(18 knees). For survivorship analysis, the actuarial life- table method was used with calculation of the numbers at risk and the survival rates at annual intervals. The 95% confidence limits were calculated by the method of Rothman. The survivorship at the end of eight year follow-up was 99.40. None of the patellar components failed. Conclusion: Our study shows excellent clinical results of PFC Sigma Total knee replacement after almost eight years follow-up. We plan to continue monitoring this cohort of patients for long-term results

We set out to demonstrate the 10-year survivorship of the PFC sigma TKA in a young patient group. Demographic and clinical outcome data were collected prospectively at 6 months, 18 months, 3 years, 5 years and 8–10 years post surgery. The data were analysed using Kaplan Meier survival statistics with end point being regarded as death or revision for any reason. 203 patients were found to be < 55 years at the time of surgery. Four patients required revision and four patients died. Another four patients moved away from the region and were excluded from the study. A total of 224 knees in 199 patients (101 male and 98 females.) 168 patients had a diagnosis of Osteoarthritis and 28 with inflammatory arthritis. Average age 50.6 years range 28–55 years (median 51). Ten-year survivorship in terms of revision 98.2% at ten years 95% confidence interval. Our results demonstrate that the PFC Sigma knee has an excellent survival rate in young patients over the first 10 years. TKR should not be withheld from patients on the basis of age

We set out to demonstrate the 10-year survivorship of the PFC sigma TKA in a young patient group. Demographic and clinical outcome data were collected prospectively at 6 months, 18 months, 3 years, 5 years and 8-10 years post surgery. The data were analysed using Kaplan Meier survival statistics with end point being regarded as death or revision for any reason. 203 patients were found to be ≤55 years at the time of surgery. Four patients required revision and four patients died. Another four patients moved away from the region and were excluded from the study. A total of 224 knees in 199 patients (101 male and 98 females.) 168 patients had a diagnosis of Osteoarthritis and 28 with inflammatory arthritis. Average age 50.6 years range 28-55 years (median 51). Ten-year survivorship in terms of revision 98.2% at ten years 95% confidence interval. Our results demonstrate that the PFC Sigma knee has an excellent survival rate in young patients over the first 10 years. TKR should not be withheld from patients on the basis of age

Aims: We present the results of the PFC Sigma knee replacement at a mean follow-up of 2.75 years (range: 1 to 6 years). Clinician and radiographic evaluation was carried out using the American Knee Society Clinical Rating and Radiographic Scoring Systems. Patient outcome was assessed using the Oxford-12 and SF-12 health-status questionnaires. Methods: A consecutive series of 293 Total Knee Replacements (TKR) in 247 patients was followed prospectively between September 1996 and September 2002. Our series included 138 females and 109 males with a mean age of 73.2 years. We operated on 214 patients with osteoarthritis, 20 with rheumatoid arthritis, 12 with post-traumatic arthritis and on one patient with erosive arthritis. The patella was resurfaced in 36 knees. 11 patients died during the follow-up period. Results: Subjective patient satisfaction score was based on improvement in pain and functional status. It was marked as excellent in 183 knees, good in 75, fair in 26 and poor in 9. Active extension lag improved from a mean of 8.5 to 3.3 degrees and flexion from 98.5 to 107.1 degrees. The mean Oxford-12 score improved from 44.17 to 24.68 and the SF-12 from 30.05 to 34.99. Radiolucent zones were observed around 2 tibial components. Post-operative complications included wound-healing problems in 25 patients, wound infection in 12, cardio-respiratory in 12, DVT in 11, non-fatal PE in 3, resolved CPN palsy in 3 and 1 death. Prosthesis complications included stiffness in 31, chronic pain in 18 (4 CRPS) and instability in 3 knees. 13 patients underwent MUA and 6 arthroscopic excision of intra-articular adhesions. 2 prosthetic infections were confirmed by bone-scan. Revision surgery was undertaken in 3 patients, 1 for established infection, 1 patella replacement and 1 tibial insert exchange. Conclusions: The early results of the PFC Sigma Knee Replacement show a high degree of patient satisfaction with a low rate of serious complications. Survivorship analysis will be undertaken in the future

Background. Although the wear of conventional polyethylene liner becomes a serious problem in a long term follow up after total knee arthroplasty, there are few reports of measuring the polyethylene wear. Questions/purposes. Is it possible to measure the linear wear rates in the non-cross-linked polyethylene liner used in the Press Fit Condylar (PFC) Sigma total knee system? Does the polyethylene wear influence on the clinical results?. Patients and Methods. The senior author and his colleagues performed total knee arthroplasties using the PFC knee system between 1997 and 2009. A follow-up was performed at minimum of 6 years after surgery, and 113 knee replacements (Female: 59 including 93 knee replacements, Male: 16 including 20 knee replacements) were clinically assessed and examined using X-ray imaging. An X-ray table was useful to make the X-ray accurately enter the tibial component at a parallel angle for anteroposterior image of radiograph when measuring the wear on knee prosthesis (Fig.1). The average follow-up period was 11.5 ± 3.4 years (range: 6.0–17.0) postoperatively. Results. There was no loosening found in the knee prostheses. However, revision surgery was performed for a case with consistent varus instability. The wear rate in the polyethylene liner was an average of 0.08 ± 0.07 (range, 0.01–0.26) mm/year on the medial joint and 0.04 ± 0.03 (range, 0.0–0.11) mm/year on the lateral joint with significant difference. The X-ray imaging was useful to measure the wear accurately. Conclusion. The medium-to-long term clinical results of the PFC Sigma Design total knee system with minor changes added have been good thus far for almost 20 years. The wear rate in the non-cross-linked polyethylene liner was very low. In the future, the extra long-term results will need to be researched further. <Figure Legend>. Fig. 1 Measurement of polyethylene wear of the prosthetic knee joint. All measurements on the radiographs of the two-dimensional position of the polyethylene liner were performed by a single researcher with use of a computerized measurement system which had a computerized digitizer with an accuracy of ± 0.01 mm. Only the anteroposterior radiographs of the knee joint were used for the measurements. The thickness of polyethylene liner was measured in both the lateral (a) and medial (b) parts of the liner in each radiograph with correction of magnification by known tibial component medial-lateral diameter (c). The polyethylene wear rate was determined by comparing the thickness in the follow-up radiograph with the thickness in the initial three-week postoperative radiograph at the same locations. The thickness of the polyethylene was measured at its shortest distance in the same flexion angle of the knee joints. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

This study was conducted to assess the results in two subgroups:a) the effect of the PFC Sigma as compared to the PFC total knee replacement in lowering patella lateral release rates and b) the results of severe fixed flexion deformity correction with emphasis on some technical operative details. Data is collected prospectively on all patients undergoing total knee replacements for an ongoing research programmer. As part of this project, we assessed the patella lateral release rate in 954 knees performed between April 1994 and January 2000. Lateral release was reached in 55 out of 592 PFC knees compared with 25 out of 362 Sigma knees. The overall lateral release rate was 8.3%. Using the Chi squared test, there is a statistically significant lower lateral release rate using the Sigma system and the study also demonstrated a low overall lateral release rate in our entire series. The biomechanics of the PFC Sigma system and some operative technical points will be discussed in the talk. As regards the fixed flexion deformity group data was once again collected prospectively on the Knee Society Scoring form. The results are as follows:. Preoperative flexion deformity > 20 degrees = 53 knees, (Range 20 to 60 degrees),. Preoperative Mean Knee Score = 17.2,. Postoperative flexion deformity < 5 degrees=91%. Postoperative Mean Knee Score = 90.04. These numbers and results are comparable to other large series and some technical operative details will be discussed in the talk

The objective of this study was to determine the location of polyethylene post position and/or axis of polyethylene (PE) bearing rotation in order to maximize the rotational freedom of the PE bearing in a posterior-stabilized mobile-bearing TKA. Kinematic data obtained in a previous study involving subjects implanted with the PFC Sigma RP (PS) was used in two mathematical models to determine the optimal configuration of the implant’s features. An inverse dynamics mathematical model used the kinematic input to calculate interactive forces between the implant components. The second mathematical model used the femur-polyethylene and polyethylene-tibial plate interactive forces in a forward solution giving the amount of polyethylene bearing rotation. Researchers altered the location of cam/post interaction and/or bearing rotation to determine the criteria for optimal bearing rotation. During flexion, the maximum femur-polyethylene contact force calculated by the inverse model was 1.9 x BW, at maximum flexion. Maximum quadriceps, patello-femoral, and patellar ligament forces were approx. 2.9 x BW, 2.8 x BW, and 1.5 x BW at maximum flexion, respectively. We determined that the sample group experienced an average maximum bearing rotation of approximately 3.5°. Maximum bearing rotation reached approx 12.5° (10°–15°) with a 5mm lateral shift in cam/post engagement. Bearing rotation reached approximately 17.5° (15°–20°) by shifting the bearing axis 5mm posterior to that of the current design. Shifting the cam/post mechanism or bearing axis by greater than 5mm in any direction produced undesirable results. The mathematical models used in this study were verified by comparing kinematic results obtained from a 3-D model-fitting program whereby models are matched to their respective silhouettes in a 2-D fluoroscopic image. Results from this study show that the rotational freedom of the PE bearing can be optimized by shifting its axis of rotation posterior to its present location

Septic knee prosthesis revision is particularly challenging either for the eradication of the infection and for functional recovery of the patient.

18 patients treated from year 2000 to 2003, treated according to the same medical and surgical protocol have been reviewed. In all cases the following steps have been followed:

- removal of the septic prosthesis, debridement and implant of an articulated pre-formed cement spacer;

At a mean 18 months follow-up, we observed:

- no infection recurrence in all cases (one patient is lost to follow-up);

Two-stage septic knee prosthesis revision, according to a the described protocol, allows to obtain high infection eradication rate and acceptable functional recovery, in the medium term follow-up.

Introduction

Previous studies comparing cruciate retaining (CR) and cruciate sacrificing - posterior stabilised (PS) TKRs have failed to demonstrate a difference in outcomes based on numbers of patients recruited.

This large study compares clinical outcomes in groups having PS and CR TKR and reports the results at 1 and 2 years post-operatively.

Objectives. The Attune total knee arthroplasty (TKA) has been used in over 600 000 patients worldwide. Registry data show good clinical outcome; however, concerns over the cement-tibial interface have been reported. We used retrieval analysis to give further insight into this controversial topic. Methods. We examined 12 titanium (Ti) PFC Sigma implants, eight cobalt-chromium (CoCr) PFC Sigma implants, eight cobalt-chromium PFC Sigma rotating platform (RP) implants, and 11 Attune implants. We used a peer-reviewed digital imaging method to quantify the amount of cement attached to the backside of each tibial tray. We then measured: 1) the size of tibial tray thickness, tray projections, peripheral lips, and undercuts; and 2) surface roughness (Ra) on the backside and keel of the trays. Statistical analyses were performed to investigate differences between the two designs. Results. There was no evidence of cement attachment on any of the 11 Attune trays examined. There were significant differences between Ti and CoCr PFC Sigma implants and Attune designs (p < 0.05); however, there was no significant difference between CoCr PFC Sigma RP and Attune designs (p > 0.05). There were significant differences in the design features between the investigated designs (p < 0.05). Conclusion. The majority of the earliest PFC Sigma designs showed evidence of cement, while all of the retrieved Attune trays and the majority of the RP PFC trays in this study had no cement attached. This may be attributable to the design differences of these implants, in particular in relation to the cement pockets. Our results may help explain a controversial aspect related to cement attachment in a recently introduced TKA design. Cite this article: A. Cerquiglini, J. Henckel, H. Hothi, P. Allen, J. Lewis, A. Eskelinen, J. Skinner, M. T. Hirschmann, A. J. Hart. Analysis of the Attune tibial tray backside: A comparative retrieval study. Bone Joint Res 2019;8:136–145. DOI: 10.1302/2046-3758.83.BJJ-2018-0102.R2

Aims. The mean age of patients undergoing total knee arthroplasty (TKA) has reduced with time. Younger patients have increased expectations following TKA. Aseptic loosening of the tibial component is the most common cause of failure of TKA in the UK. Interest in cementless TKA has re-emerged due to its encouraging results in the younger patient population. We review a large series of tantalum trabecular metal cementless implants in patients who are at the highest risk of revision surgery. Methods. A total of 454 consecutive patients who underwent cementless TKA between August 2004 and December 2021 were reviewed. The mean follow-up was ten years. Plain radiographs were analyzed for radiolucent lines. Patients who underwent revision TKA were recorded, and the cause for revision was determined. Data from the National Joint Registry for England, Wales, Northern Island, the Isle of Man and the States of Guernsey (NJR) were compared with our series. Results. No patients in our series had evidence of radiolucent lines on their latest radiological assessment. Only eight patients out of 454 required revision arthroplasty, and none of these revisions were indicated for aseptic loosening of the tibial baseplate. When compared to data from the NJR annual report, Kaplan-Meier estimates from our series (2.94 (95% confidence interval (CI) 1.24 to 5.87)) show a significant reduction in cumulative estimates of revision compared to all cemented (4.82 (95% CI 4.69 to 4.96)) or cementless TKA (5.65 (95% CI 5.23 to 6.10)). Our data (2.94 (95% CI 1.24 to 5.87)) also show lower cumulative revision rates compared to the most popular implant (PFC Sigma Cemented Knee implant fixation, 4.03 (95% CI 3.75 to 4.33)). The prosthesis time revision rate (PTIR) estimates for our series (2.07 (95% CI 0.95 to 3.83)) were lower than those of cemented cases (4.53 (95% CI 4.49 to 4.57)) from NJR. Conclusion. The NexGen trabecular (tantalum) cementless implant has lower revision rates in our series compared to all cemented implants and other types of cementless implants, and its use in younger patients should be encouraged. Cite this article: Bone Jt Open 2024;5(4):277–285