Narrow, well-defined radiolucent lines commonly observed at the bone-implant interface of unicompartmental knee replacement tibial components have been referred to as physiological radiolucencies. These should be distinguished from pathological radiolucencies, which are poorly defined, wide and progressive, and associated with loosening and infection. We studied the incidence and clinical significance of tibial radiolucent lines in 161 Oxford unicondylar knee replacements five years after surgery. All the radiographs were aligned with fluoroscopic control to obtain views parallel to the tibial tray to reveal the tibial bone-implant interface. We found that 49 knees (30%) had complete, 52 (32%) had partial and 60 (37%) had no radiolucent lines. There was no relationship between the incidence of radiolucent lines and patient factors such as gender, body mass index and activity, or operative factors including the status of the anterior cruciate ligament and residual varus deformity. Nor was any statistical relationship established between the presence of radiolucent lines and clinical outcome, particularly pain, assessed by the Oxford Knee score and the American Knee Society score. We conclude that radiolucent lines are common after Oxford unicompartmental knee replacement but that their aetiology remains unclear. Radiolucent lines were not a source of adverse symptoms or pain. Therefore, when attempting to identify a source of postoperative pain after Oxford unicompartmental knee replacement the presence of a physiological radiolucency should be ignored

We randomised 62 knees to receive either cemented or cementless versions of the Oxford unicompartmental knee replacement. The implants used in both arms of the study were similar, except that the cementless components were coated with porous titanium and hydroxyapatite. The tibial interfaces were studied with fluoroscopically-aligned radiographs. At one year there was no difference in clinical outcome between the two groups. Narrow radiolucent lines were seen at the bone-implant interfaces in 75% of cemented tibial components. These were partial in 43%, and complete in 32%. In the cementless implants, partial radiolucencies were seen in 7% and complete radiolucencies in none. These differences are statistically significant (p < 0.0001) and imply satisfactory bone ingrowth into the cementless implants

Abstract. Introduction. Higher than expected rates of tibial loosening with the ATTUNE® total knee arthroplasty (TKA) implant has been reported. Component loosening can be associated with the development of radiolucency lines (RLL) and our study aim was to systematically assess the reported rates of these. Methodology. A systematic search was undertaken using the Cochrane methodology in four online databases. Identified studies were assessed and screened against predetermined inclusion criteria. Meta-analysis was conducted using a random-effects model. Results. Nine studies (n=2,727 TKAs) from 6,590 titles met the inclusion criteria: 1 Randomised Controlled Trial (n=74), 1 prospective cohort (n=200), 4 retrospective cohort (n=1,639), and 3 case-series (n=814). All used the 2013 ATTUNE® design. In meta-analysis: 8 studies (n=1,440 ATTUNE TKAs) reported an overall prevalence of 11% (95%CI: 6.4-18.3%) for medial tibia RLL; 7 studies (n=940) a 12.3% (95%CI: 4.0-32%) rate of any tibia RLL.; 5 studies (n=736) femoral RLL in 11% (95%CI: 7.2-106.5%) and 7 studies (n=896) any RLL in 20.7% (95%CI: 13.4-30.6%). Meta-analysis of 4 studies (n=1,036) comparing the ATTUNE® with another implant (PFC Sigma®, LCS®, or PERSONA®) showed a higher risk of medial tibia RLL (OR: 2.538; 95%CI: 1.397-4.611, P=0.002) and any RLL (OR: 2.725; 95%CI: 1.302-5.703, P=0.008) in the ATTUNE® group. Conclusions. The 2013 ATTUNE® TKA system is associated with high rates of radiolucency around the tibial and femoral components. Comparative studies suggesting these rates are more than double those of other systems. Radiolucency may be a herald of component loosening, therefore, close surveillance of this implant is recommended

Abstract. Introduction. Cementless fixation of Oxford Unicompartmental Knee Replacements (UKRs) is an alternative to cemented fixation, however, it is unknown whether cementless fixation is as good long-term. This study aimed to compare primary and long-term fixation of cemented and cementless Oxford UKRs using radiostereometric analysis (RSA). Methodology. Twenty-nine patients were randomised to receive cemented or cementless Oxford UKRs and followed for ten years. Differences in primary fixation and long-term fixation of the tibial components (inferred from 0/3/6-month and 6-month/1-year/2-year/5-year/10-year migration, respectively) were analysed using RSA and radiolucencies were assessed on radiographs. Migration rates were determined by linear regression and clinical outcomes measured using the Oxford Knee Score (OKS). Results. Preliminary analysis of Maximum Total Point Motion (MTPM) indicated cementless tibial components undergo significantly more migration than cemented components during the first 6 months (1.6mm/year, SD=0.92 versus 1.3mm/year, SD=1.1, p<0.001). Cementless migration was predominantly subsidence inferiorly (Mean=0.51mm/year, SD=0.29, p<0.001) and posteriorly (0.13mm/year, SD=0.21, p=0.03). Contrastingly, from 6 months to 10 years cemented components migrated significantly (MTPM=0.039mm/year, SD=0.11, p=0.04) whereas cementless components did not (MTPM=0.002mm/year, SD=0.02, p=0.744). Radiolucent lines occurred more frequently below cemented (10/13) than cementless (4/16) tibial components, but radiolucencies did not correlate with differences in migration or OKS. There was no significant difference in OKS between cemented and cementless. Conclusion. These results suggest that cementless tibial components migrate more than cemented before achieving primary fixation. However, long-term fixation of cementless tibial components appears to be as good, if not better, than cemented with the benefit of fewer radiolucent lines

The most common reasons for revision of unicompartmental knee arthroplasty (UKA) are loosening and pain. Cementless components may reduce the revision rate. The aim of this study was to compare the fixation and clinical outcome of cementless and cemented Oxford UKAs. . A total of 43 patients were randomised to receive either a cemented or a cementless Oxford UKA and were followed for two years with radiostereometric analysis (RSA), radiographs aligned with the bone–implant interfaces and clinical scores. The femoral components migrated significantly during the first year (mean 0.2 mm) but not during the second. There was no significant difference in the extent of migration between cemented and cementless femoral components in either the first or the second year. In the first year the cementless tibial components subsided significantly more than the cemented components (mean 0.28 mm (. sd. 0.17) vs. 0.09 mm (. sd. 0.19 mm)). In the second year, although there was a small amount of subsidence (mean 0.05 mm) there was no significant difference (p = 0.92) between cemented and cementless tibial components. There were no femoral radiolucencies. Tibial radiolucencies were narrow (< 1 mm) and were significantly (p = 0.02) less common with cementless (6 of 21) than cemented (13 of 21) components at two years. There were no complete radiolucencies with cementless components, whereas five of 21 (24%) cemented components had complete radiolucencies. The clinical scores at two years were not significantly different (p = 0.20). . As second-year migration is predictive of subsequent loosening, and as radiolucency is suggestive of reduced implant–bone contact, these data suggest that fixation of the cementless components is at least as good as, if not better than, that of cemented devices. Cite this article: Bone Joint J 2015; 97-B:185–91

The Cementless Oxford Unicompartmental Knee Replacement (OUKR) was developed to address problems related to cementation, and has been demonstrated in a randomised study to have similar clinical outcomes with fewer radiolucencies than observed with the cemented device. However, before its widespread use it is necessary to clarify contraindications and assess the complications. This requires a larger study than any previously published. We present a prospective multicentre series of 1000 cementless OUKRs in 881 patients at a minimum follow-up of one year. All patients had radiological assessment aligned to the bone–implant interfaces and clinical scores. Analysis was performed at a mean of 38.2 months (19 to 88) following surgery. A total of 17 patients died (comprising 19 knees (1.9%)), none as a result of surgery; there were no tibial or femoral loosenings. A total of 19 knees (1.9%) had significant implant-related complications or required revision. Implant survival at six years was 97.2%, and there was a partial radiolucency at the bone–implant interface in 72 knees (8.9%), with no complete radiolucencies. There was no significant increase in complication rate compared with cemented fixation (p = 0.87), and no specific contraindications to cementless fixation were identified. Cementless OUKR appears to be safe and reproducible in patients with end-stage anteromedial osteoarthritis of the knee, with radiological evidence of improved fixation compared with previous reports using cemented fixation. Cite this article: Bone Joint J 2013;95-B:181–7

Aims. The primary objective of this study was to compare migration of the cemented ATTUNE fixed bearing cruciate retaining tibial component with the cemented Press-Fit Condylar (PFC)-sigma fixed bearing cruciate retaining tibial component. The secondary objectives included comparing clinical and radiological outcomes and Patient Reported Outcome Measures (PROMs). Methods. A single blinded randomized, non-inferiority study was conducted including 74 patients. Radiostereometry examinations were made after weight bearing, but before hospital discharge, and at three, six, 12, and 24 months postoperatively. PROMS were collected preoperatively and at three, six, 12, and 24 months postoperatively. Radiographs for measuring radiolucencies were collected at two weeks and two years postoperatively. Results. The overall migration (mean maximum total point motion (MPTM)) at two years was comparable: mean 1.13 mm (95% confidence interval (CI), 0.97 to 1.30) for the ATTUNE and 1.16 mm (95% CI, 0.99 to 1.35) for the PFC-sigma. At two years, the mean backward tilting was -0.43° (95% CI, -0.65 to -0.21) for the ATTUNE and 0.08° (95% CI -0.16 to 0.31), for the PFC-sigma. Overall migration between the first and second postoperative year was negligible for both components. The clinical outcomes and PROMs improved compared with preoperative scores and were not different between groups. Radiolucencies at the implant-cement interface were mainly seen below the medial baseplate: 17% in the ATTUNE and 3% in the PFC-sigma at two weeks, and at two years 42% and 9% respectively (p = 0.001). Conclusion. In the first two postoperative years the initial version of the ATTUNE tibial component was not inferior with respect to overall migration, although it showed relatively more backwards tilting and radiolucent lines at the implant-cement interface than the PFC-sigma. The version of the ATTUNE tibial component examined in this study has subsequently undergone modification by the manufacturer. Level of Evidence: 1 (randomized controlled clinical trial). Cite this article: Bone Joint J 2020;102-B(9):1158–1166

Purpose of Study. To assess the incidence of radiolucency in cemented and cementless Oxford unicompartmental knee replacement at two years. Introduction. Most unicompartmental knee replacements (UKRs) employ cement for fixation of the prosthetic components. The information in the literature about the relative merits of cemented and cementless UKR is contradictory, with some favouring cementless fixation and others favouring cemented fixation. In addition, there is concern about the radiolucency that frequently develops beneath the tibial component with cemented fixation. The exact cause of the occurrence of radiolucency is unknown but it has been hypothesised that it may suggest suboptimal fixation. Method. Following ethical approval, 62 patients with medial OA were randomised to receive either cemented (n=32) or cementless components (n=30). All patients underwent an identical surgical procedure with either a cemented or cementless Oxford UKR. Patients were assessed clinically by a research physiotherapist and radiologically using screened radiographs. Thirty-eight patients from the trial with follow up of at least two years and well aligned radiographs were identified (cemented n=16, cementless n=22). Results. The patients in the two groups were well matched. Radiological and clinical assessment was at a mean of 2.25 years. There was no significant difference in the clinical scores between the two groups. The median OKS for the cemented group was 43 and for the cementless group was 42.5. Narrow radiolucent lines were seen at the bone-implant interfaces of 63% of the cemented tibial components; partial in 38% and complete in 25%. In the cementless implants, partial radiolucencies were seen in 4.5% and complete radiolucencies in none. The differences are statistically highly significant (p< 0.0001). The lack of radiolucency beneath the cementless tibial components implies satisfactory bone ingrowth and hence fixation. Conclusions. At 2 years the cementless components are well fixed and have similar clinical results to the cemented

Aims. This study compares the PFC total knee arthroplasty (TKA) system in a prospective randomized control trial (RCT) of the mobile-bearing rotating-platform (RP) TKA against the fixed-bearing (FB) TKA. This is the largest RCT with the longest follow-up where cruciate-retaining PFC total knee arthroplasties are compared in a non-bilateral TKA study. Patients and Methods. A total of 167 patients (190 knees with 23 bilateral cases), were recruited prospectively and randomly assigned, with 91 knees receiving the RP and 99 knees receiving FB. The mean age was 65.5 years (48 to 82), the mean body mass index (BMI) was 29.7 kg/m. 2. (20 to 52) and 73 patients were female. The Knee Society Score (KSS), Knee Society Functional Score (KSFS), Oxford Knee Score (OKS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), and 12-Item Short-Form Health Survey Physical and Mental Component Scores (SF-12 PCS, SF-12 MCS) were gathered and recorded preoperatively, at five-years’ follow-up, and at ten years’ follow-up. Additionally, Knee Injury and Osteoarthritis Outcome Scores (KOOS) were collected at five- and ten-year follow-ups. The prevalence of radiolucent lines (RL) on radiographs and implant survival were recorded at five- and ten-year follow-ups. Results. At the ten-year follow-up, the RP group (n = 39) had a statistically significant superior score in the OKS (p = 0.001), WOMAC (p = 0.023), SF-12 PCS (p = 0.019), KOOS Activities of Daily Living (ADL) (p = 0.010), and KOOS Sport and Recreation (Sport/Rec) (p = 0.006) compared with the FB group (n = 46). The OKS, SF-12 PCS, and KOOS Sport/Rec at ten years had mean scores above the minimal clinically important difference (MCID) threshold. There was no significant difference in prevalence of radiolucency between groups at five-years’ follow-up (p = 0.449), nor at ten-years’ follow-up (p = 0.08). Implant survival rate at 14 years postoperative was 95.2 (95% CI 90.7 to 99.8) and 94.7 (95% CI 86.8 to 100.0) for the RP and FB TKAs, respectively. Conclusion. At ten-year follow-up, the mobile-bearing knee joint arthroplasty had statistically and clinically relevant superior OKS, SF-12 PCS, and KOOS (Sport/Rec) than the fixed-bearing platform. No difference was seen in prevalence of radiolucent lines. There was a greater than 94% implant survival rate for both cohorts at 14 years. Cite this article: Bone Joint J 2018;100-B:1336–44

Introduction. Initial post-operative implant instability leads to impaired osseointegration, one of the most common reasons for aseptic loosening and revision surgery. In this study, we developed a novel murine model of implant instability and demonstrated the anabolic effect of immediate and delayed intermittent Parathyroid Hormone (iPTH) treatment in the setting of instability-induced osseointegration failure. Methods. 3D-printed titanium implants were inserted in an oversized drill-hole in the tibia of C57Bl/6 mice (n=54). After implantation, the mice were randomly divided in 3 treatment groups (control: PBS-vehicle; iPTH; delayed iPTH). Radiographic analysis was performed to confirm signs of implant loosening. Peri-implant tissue formation was assessed through histology. Osseointegration was assessed through µCT and biomechanical pullout testing. Results. Immediate iPTH treatment reduced radiolucencies and induced a distinct pedestal sign distal to the implant stem (white arrow Fig 1A). The PBS treated mice had fibrous tissue implant encapsulation, whereas new mineralized tissue and no fibrous tissue was observed with immediate iPTH treatment (Fig 1E). Delayed iPTH treatment was also able to exhibit significant peri-implant bone mineralization, osteoblasts, angiogenesis, and a reduction of fibrous tissue (Fig 2A-B). iPTH treatment increased the force required to pull out the implant significantly from 8.41 ± 8.15N in the PBS group to 21.49 ± 10.45N and 23.68 ± 8.99N, in the immediate and delayed iPTH treatment groups, respectively (Fig 2D). PBS vehicle resulted in a bone volume/trabecular volume (BV/TV) of 0.23 ± 0.03, while immediate and delayed iPTH treatment increased BV/TV significantly to 0.46 ± 0.07 and 0.34 ± 0.10, respectively (Fig 2E). Conclusion. Immediate iPTH treatment prevents peri-implant fibrous tissue formation and enhances peri-implant bone formation in our murine model of mechanical instability. Delayed iPTH treatment was able to resolve the peri-implant fibrous tissue and stimulate bone formation. This study potentially addresses a leading cause of aseptic loosening by demonstrating that initial implant instability can be rescued by iPTH even with delayed start of treatment. For any figures or tables, please contact authors directly

Aims

Loosening of components after total knee arthroplasty (TKA) can be associated with the development of radiolucent lines (RLLs). The aim of this study was to assess the rate of formation of RLLs in the cemented original design of the ATTUNE TKA and their relationship to loosening.

Aims

The aim of this study was to describe the pattern of revision indications for unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) and any change to this pattern for UKA patients over the last 20 years, and to investigate potential associations to changes in surgical practice over time.

Aims

Conflicting clinical results are reported for the ATTUNE Total Knee Arthroplasty (TKA). This randomized controlled trial (RCT) evaluated five-year follow-up results comparing cemented ATTUNE and PFC-Sigma cruciate retaining TKAs, analyzing component migration as measured by radiostereometric analysis (RSA), clinical outcomes, patient-reported outcome measures (PROMs), and radiological outcomes.

The relationship between post-operative bone density and subsequent failure of total knee replacement (TKR) is not known. This retrospective study aimed to determine the relationship between bone density and failure, both overall and according to failure mechanism. All 54 aseptic failures occurring in 50 patients from 7760 consecutive primary cemented TKRs between 1983 and 2004 were matched with non-failing TKRs, and 47 failures in 44 patients involved tibial failures with the matching characteristics of age (65.1 for failed and 69.8 for non-failed), gender (70.2% female), diagnosis (93.6% OA), date of operation, bilaterality, pre-operative alignment (0.4 and 0.3 respectively), and body mass index (30.2 and 30.0 respectively). In each case, the density of bone beneath the tibial component was assessed at each follow-up interval using standardised, calibrated radiographs. Failing knees were compared with controls both overall and, as a subgroup analysis, by failure mechanism. Knees were compared with controls using univariable linear regression. Significant and continuous elevation in tibial density was found in knees that eventually failed by medial collapse (p < 0.001) and progressive radiolucency (p < 0.001) compared with controls, particularly in the medial region of the tibia. Knees failing due to ligamentous instability demonstrated an initial decline in density (p = 0.0152) followed by a non-decreasing density over time (p = 0.034 for equivalence). Non-failing knees reported a decline in density similar to that reported previously using dual-energy x-ray absorptiometry (DEXA). Differences between failing and non-failing knees were observable as early as two months following surgery. This tool may be used to identify patients at risk of failure following TKR, but more validation work is needed. Cite this article: Bone Joint J 2014;96-B:1503–9

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.

Introduction. New implants for total knee arthroplasty (TKA) are frequently introduced with the promise of improved performance. Infrequently there is accompanying data to document relative performance. The goal of this study was to evaluate the outcomes of an implant widely used for decades (Existing TKA), compared to a new implant (New TKA) from the same manufacturer. Methods. From October 2011-March 2015, 19 sites prospectively enrolled and implanted 752 Subjects with Existing TKA. Between November 2012 and May 2015, 23 sites (18 sites had enrolled Existing TKAs), implanted 1131 Subjects with the New TKA. Demographics were similar between groups. Subjects were seen preoperatively, <1-year, 1-year, and 2-years to collect patient reported outcome measures (PROMs), radiographs and any complications. PROMs consisted of Knee Injury and Osteoarthritis Outcome Score (KOOS) (permits WOMAC scoring), Oxford Knee Score (OKS), Patient's Knee Implant Performance (PKIP) and EQ5D-3L and a p-value of 0.01 was established for statistical significance for PROMs comparisons. Kaplan-Meier (KM) implant survivorship (revision of any component for any reason) estimates were calculated. Results. The mean follow-up for the Existing and New groups was 2.2 years (SD: 0.7) and 2.5 years (SD: 0.8), respectively. The difference in KM survivorship was not statistically significant (p=0.9727, Figure 1). In the Existing TKA group, 11/752 Subjects required component revision with 6 involving removal of metal components for the following reasons: infection (4), pain (5), loosening (1) and instability (1). In the New TKA group, 19/1137 Subjects required component revision with 7 involving removal of metal components for the following reasons: infection (6), joint stiffness (6), pain (3), bone fracture (2), crepitus (1), and loosening (1). The 2-year PROMs were compared between groups and demonstrated similar or improved scores in favor of the New vs. Existing TKA. Mean outcomes for New TKA vs. Existing TKA at 2 years were: KOOS (ADL: 89.0 vs. 86.9, p=0.005; Pain: 89.0 vs. 87.1, p=0.018; Symptoms: 84.1 vs. 82.1, p=0.010; Sport/Rec: 63.9 vs. 58.8, p=0.001, QOL: 77.0 vs. 73.5, p=0.003), PKIP (Overall: 76.5 vs. 73.5, p=0.003; Confidence: 8.4 vs. 8.1, p=0.003; Stability: 8.6 vs. 8.3, p=0.006; Satisfaction: 8.3 vs. 8.1, p=0.053; Modify Activities: 6.6 vs. 6.4, p=0.335), OKS (42.0 vs. 41.1, p=0.023), and EQ5D-3L (0.88 vs. 0.88, p=0.906). There was no difference between the two groups in the percent of Subjects with immediate postop radiographic interface gaps or radiolucencies (metal-cement or the bone-cement interfaces). Conclusion. The implant survivorship and radiographic assessments showed similar outcomes between the two groups. The New TKA demonstrated modest improvements in PROMs across a broad spectrum of measures. For any figures or tables, please contact authors directly

Aims

The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs).

Aims

Porous metaphyseal cones can be used for fixation in revision total knee arthroplasty (rTKA) and complex TKAs. This metaphyseal fixation has led to some surgeons using shorter cemented stems instead of diaphyseal engaging cementless stems with a potential benefit of ease of obtaining proper alignment without being beholden to the diaphysis. The purpose of this study was to evaluate short term clinical and radiographic outcomes of a series of TKA cases performed using 3D-printed metaphyseal cones.

Aims

Wear of the polyethylene (PE) tibial insert of total knee arthroplasty (TKA) increases the risk of revision surgery with a significant cost burden on the healthcare system. This study quantifies wear performance of tibial inserts in a large and diverse series of retrieved TKAs to evaluate the effect of factors related to the patient, knee design, and bearing material on tibial insert wear performance.

Aims

To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period.