Aims. The aims were to assess whether joint-specific outcome after total knee arthroplasty (TKA) was influenced by implant design over a 12-year follow-up period, and whether patient-related factors were associated with loss to follow-up and mortality risk. Methods. Long-term follow-up of a randomized controlled trial was undertaken. A total of 212 patients were allocated a Triathlon or a Kinemax TKA. Patients were assessed preoperatively, and one, three, eight, and 12 years postoperatively using the Oxford Knee Score (OKS). Reasons for patient lost to follow-up, mortality, and revision were recorded. Results. A total of 94 patients completed 12-year functional follow-up (62 females, mean age 66 years (43 to 82) at index surgery). There was a clinically significantly greater improvement in the OKS at one year (mean difference (MD) 3.0 (95% CI 0.4 to 5.7); p = 0.027) and three years (MD 4.7 (95% CI 1.9 to 7.5); p = 0.001) for the Triathlon group, but no differences were observed at eight (p = 0.331) or 12 years’ (p = 0.181) follow-up. When assessing the OKS in the patients surviving to 12 years, the Triathlon group had a clinically significantly greater improvement in the OKS (marginal mean 3.8 (95% CI 0.2 to 7.4); p = 0.040). Loss to functional follow-up (53%, n = 109/204) was independently associated with older age (p = 0.001). Patient mortality was the major reason (56.4%, n = 62/110) for loss to follow-up. Older age (p < 0.001) and worse preoperative OKS (p = 0.043) were independently associated with increased mortality risk. An age at time of surgery of ≥ 72 years was 75% sensitive and 74% specific for predicting mortality with an area under the curve of 78.1% (95% CI 70.9 to 85.3; p < 0.001). Conclusion. The Triathlon TKA was associated with clinically meaningful greater improvement in knee-specific outcome when compared to the Kinemax TKA. Loss to follow-up at 12 years was a limitation, and studies planning longer-term functional assessment could limit their cohort to patients aged under 72 years. Cite this article: Bone Jt Open 2024;5(10):911–919

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

Stiffness is a common complication after total knee arthroplasty (TKA). Pathogenesis is not understood, treatment options are limited, and diagnosis is challenging. The aim of this study was to investigate if MRI can be used to visualize intra-articular scarring in patients with stiff, painful knee arthroplasties.

Aims. There are comparatively few randomized studies evaluating knee arthroplasty prostheses, and fewer still that report longer-term functional outcomes. The aim of this study was to evaluate mid-term outcomes of an existing implant trial cohort to document changing patient function over time following total knee arthroplasty using longitudinal analytical techniques and to determine whether implant design chosen at time of surgery influenced these outcomes. Methods. A mid-term follow-up of the remaining 125 patients from a randomized cohort of total knee arthroplasty patients (initially comprising 212 recruited patients), comparing modern (Triathlon) and traditional (Kinemax) prostheses was undertaken. Functional outcomes were assessed with the Oxford Knee Score (OKS), knee range of movement, pain numerical rating scales, lower limb power output, timed functional assessment battery, and satisfaction survey. Data were linked to earlier assessment timepoints, and analyzed by repeated measures analysis of variance (ANOVA) mixed models, incorporating longitudinal change over all assessment timepoints. Results. The mean follow-up of the 125 patients was 8.12 years (7.3 to 9.4). There was a reduction in all assessment parameters relative to earlier assessments. Longitudinal models highlight changes over time in all parameters and demonstrate large effect sizes. Significant between-group differences were seen in measures of knee flexion (medium-effect size), lower limb power output (large-effect size), and report of worst daily pain experienced (large-effect size) favouring the Triathlon group. No longitudinal between-group differences were observed in mean OKS, average daily pain report, or timed performance test. Satisfaction with outcome in surviving patients at eight years was 90.5% (57/63) in the Triathlon group and 82.8% (48/58) in the Kinemax group, with no statistical difference between groups (p = 0.321). Conclusion. At a mean 8.12 years, this mid-term follow-up of a randomized controlled trial cohort highlights a general reduction in measures of patient function with patient age and follow-up duration, and a comparative preservation of function based on implant received at time of surgery. Cite this article: Bone Joint J 2020;102-B(4):434–441

One of the main surgical goals when performing a total knee replacement (TKR) is to ensure the implants are properly aligned and correctly sized; however, understanding the effect of alignment and rotation on the biomechanics of the knee during functional activities is limited. Cardiff University has unique access to a group of local patients who have relatively high frequency of poor alignment, and early failure. This provides a rare insight into how malalignment of TKR's can affect patients from a clinical and biomechanical point of view to determine how to best align a TKR. This study aims to explore relationship clinical surgical measurements of Implant alignment with in-vivo joint kinematics. 28 patient volunteers (with 32 Kinemax (Stryker) TKR's were recruited. Patients undertook single plane video fluoroscopy of the knee during a step-up and step-down task to determine TKR in-vivo kinematics and centre of rotation (COR). Joint Track image registration software (University of Florida, USA) was used to match CAD models of the implant to the x-ray images. Hip-Knee-Ankle (HKA) was measured using long-leg radiographs to determine frontal plane alignment. Posterior tibial slope angle was calculated using radiographs. An independent sample t-test was used to explore differences between neutral (HKA:-2° to 2°), varus (≥2°) and valgus alignment (≤-2°) groups. Other measures were explored across the whole cohort using Pearson's correlations (SPSS V23). There was found to be no statistical difference between groups or correlations for HKA. The exploratory analysis found that tibial slope correlated with Superior/Inferior translation ROM during step up (r=−0.601, p<0.001) and step down (r=−.512, p=0.03) the position of the COR heading towards the lateral (r=−.479, p=0.006) during step down. Initial results suggest no relationship between frontal plane alignment and in-vivo. Exploratory analyses have found other relationships that are worthy of further research and may be important in optimizing function

Background. There is a paucity of long term data concerning the pre and postoperative patient reported function of total knee replacement. The aim of this study was to determine the mortality, implant survivorship, patient reported function and satisfaction in a cohort of 114 patients, from a single centre, who received a Kinemax total knee replacement more than 15 years ago. Methods. Patients completed a questionnaire incorporating validated disease- and joint-specific scores, patient satisfaction and overall health preoperatively, at 3 months, 1 year, 2 years and a minimum of 15 years following surgery. NHS National Strategic Tracing Service, hospital and primary care records were used to establish mortality and for implant survivorship in deceased patients. Results. 45 patients were alive at final follow up. The survivorship of the cohort with revision of the TKR as the endpoint was 84%. Four cases were revised for wear, three for loosening and one for peri-prosthetic fracture. There was a significant improvement in WOMAC Pain, Function and Stiffness Scores, Oxford Knee Score and Self-Administered Patient Satisfaction Scale between pre-operative and all post-operative time points, although patient satisfaction had decreased significantly by the time of final follow up. Conclusion. In this cohort, the Kinemax TKR showed satisfactory long term survivorship with functional scores demonstrating a high level of patient satisfaction at all follow up time points. Level of Evidence. 2

Objectives

Preservation of posterior condylar offset (PCO) has been shown to correlate with improved functional results after primary total knee arthroplasty (TKA). Whether this is also the case for revision TKA, remains unknown. The aim of this study was to assess the independent effect of PCO on early functional outcome after revision TKA.

Aims

Risk of revision following total knee arthroplasty (TKA) is higher in patients under 55 years, but little data are reported regarding non-revision outcomes. This study aims to identify predictors of dissatisfaction in these patients.

The April 2015 Knee Roundup360 looks at: Genetic determinants of ACL strength; TKA outcomes influenced by prosthesis; Single- or two-stage revision for infected TKA?; Arthroscopic meniscectomy: a problem that just won’t go away!; Failure in arthroscopic ACL reconstruction; ACL reconstruction in the over 50s?; Knee arthroplasty for early osteoarthritis; All inside meniscal repair; Steroids, thrombogenic markers and TKA

Total knee arthroplasty (TKA) is an established and successful procedure. However, the design of prostheses continues to be modified in an attempt to optimise the functional outcome of the patient. . The aim of this study was to determine if patient outcome after TKA was influenced by the design of the prosthesis used. A total of 212 patients (mean age 69; 43 to 92; 131 female (62%), 81 male (32%)) were enrolled in a single centre double-blind trial and randomised to receive either a Kinemax (group 1) or a Triathlon (group 2) TKA. . Patients were assessed pre-operatively, at six weeks, six months, one year and three years after surgery. The outcome assessments used were the Oxford Knee Score; range of movement; pain numerical rating scales; lower limb power output; timed functional assessment battery and a satisfaction survey. Data were assessed incorporating change over all assessment time points, using repeated measures analysis of variance longitudinal mixed models. Implant group 2 showed a significantly greater range of movement (p = 0.009), greater lower limb power output (p = 0.026) and reduced report of ‘worst daily pain’ (p = 0.003) over the three years of follow-up. Differences in Oxford Knee Score (p = 0.09), report of ‘average daily pain’ (p = 0.57) and timed functional performance tasks (p = 0.23) did not reach statistical significance. Satisfaction with outcome was significantly better in group 2 (p = 0.001). These results suggest that patient outcome after TKA can be influenced by the prosthesis used. Cite this article: Bone Joint J 2015;97-B:64–70

Summary Statement. Using current analysis/methodology, new implant technology is unlikely to demonstrate a large enough change in patient function to impact on the cost-effectiveness of the procedure. Purpose. Cost effectiveness is an increasingly important metric in today's healthcare environment, and decisions surrounding which arthroplasty prosthesis to implant are not exempt from such health economic concerns. Quality adjusted life years (QALYs) are the typical assessment tool for this type of evaluation. Using this methodology, joint arthroplasty has been shown to be cost effective, however studies directly comparing the QALY achieved by differing prostheses are lacking. Methods. Data was gathered in a single centre prospective double-blind randomised controlled trial comparing the outcome a modern implant, the Triathlon total knee replacement, with its traditionally designed predecessor the Kinemax, using the Short Form 6 dimensional (SF-6D) score and quality adjusted life year (QALY) methodology. The study cohort consisted of 64 patients that were randomised to a Triathlon and 60 randomised to a Kinemax. Results. There was a significant improvement in the SF-6D score for both groups at one year compared with pre-operative scores (p<0.0001). The calculated overall life expectancy for the study cohort was 15.1 years, which resulted in an overall QALY gain of 2.144 (95% CI 1.752–2.507). The modern implant group demonstrated only a small improvement in the SF-6D score compared to the traditional design at one year (0.141 versus 0.143, p=0.94). This difference in health gain resulted in the modern implant costing £298 less per QALY at one year, however this saving diminished to less than £30 per year over the lifetime of the cohort. Discussion. This study demonstrates that despite comparing 2nd and 4th generation design, modern implant technology does not influence the cost-effectiveness of TKA using the SF-6D and QALY methodology. As most implants demonstrate similar longevity, differences in patient function will likely carry the greatest influence on QALY. This type of analysis however assesses health status, and is not sensitive to joint specific function. Dramatic differences in patient outcome would be required to influence QALY score. Evolutionary design changes in implant technology are thus unlikely to influence QALY analysis following joint replacement, which has important implication for implant procurement

Mechanical alignment has been a fundamental tenet of total knee arthroplasty (TKA) since modern knee replacement surgery was developed in the 1970s. The objective of mechanical alignment was to infer the greatest biomechanical advantage to the implant to prevent early loosening and failure. Over the last 40 years a great deal of innovation in TKA technology has been focusing on how to more accurately achieve mechanical alignment. Recently the concept of mechanical alignment has been challenged, and other alignment philosophies are being explored with the intention of trying to improve patient outcomes following TKA.

This article examines the evolution of the mechanical alignment concept and whether there are any viable alternatives.

Mobile-bearing (MB) total knee replacement (TKR) was introduced to reduce the risk of aseptic loosening and wear of polyethylene inserts. However, no consistent clinical advantages of mobile- over fixed-bearing (FB) TKR have been found. In this study we evaluated whether mobile bearings have an advantage over fixed bearings with regard to revision rates and clinical outcome scores. Furthermore, we determined which modifying variables affected the outcome.

A systematic search of the literature was conducted to collect clinical trials comparing MB and FB in primary TKR. The primary outcomes were revision rates for any reason, aseptic loosening and wear. Secondary outcomes included range of movement, Knee Society score (KSS), Oxford knee score (OKS), Short-Form 12 (SF-12) score and radiological parameters. Meta-regression techniques were used to explore factors modifying the observed effect.

Our search yielded 1827 publications, of which 41 studies met our inclusion criteria, comprising over 6000 TKRs. Meta-analyses showed no clinically relevant differences in terms of revision rates, clinical outcome scores or patient-reported outcome measures between MB and FB TKRs. It appears that theoretical assumptions of superiority of MB over FB TKR are not borne out in clinical practice.

Cite this article: Bone Joint J 2013;95-B:1209–16.

The purpose of this study was to undertake a meta-analysis to determine whether there is lower polyethylene wear and longer survival when using mobile-bearing implants in total knee replacement when compared with fixed-bearing implants. Of 975 papers identified, 34 trials were eligible for data extraction and meta-analysis comprising 4754 patients (6861 knees). We found no statistically significant differences between the two designs in terms of the incidence of radiolucent lines, osteolysis, aseptic loosening or survival. There is thus currently no evidence to suggest that the use of mobile-bearing designs reduce polyethylene wear and prolong survival after total knee replacement.

Cite this article: Bone Joint J 2013;95-B:1057–63.

In the UK we have many surgeon inventors – surgeons who innovate and create new ways of doing things, who invent operations, who design new instruments to facilitate surgery or design new implants for using in patients. However truly successful surgeon inventors are a rare breed and they need to develop additional knowledge and skills during their career in order to push forward their devices and innovations. This article reviews my own experiences as a surgeon inventor and the highs and lows over the whole of my surgical career.

Two knee arthroplasty implants with very different design principles were previously available in our region. Kinemax is PCL retaining with a fixed bearing and cemented components. LCS is PCL sacrificing, fully uncemented and incorporates a rotating bearing. The aim of this study was to compare the outcome of these two radically different knee designs. Between 1994 and 2004, 300 consecutive patients were recruited and underwent a knee replacement performed by the senior author. Each patient was randomised via sealed envelopes to receive either LCS or Kinemax implants. All patients were followed up by an audit nurse and patient satisfaction and Knee Society Scores (KSSs) were recorded. By 2012, 135 patients had complete data at a minimum of 10-years of follow-up. The remaining 165 had either died before 10-year review or had not reached the 10-year mark. No patient was lost to follow-up. There were 69 patients in the Kinemax group and 68 in the LCS group. The pre-operative demographics were not significantly different between the two groups. At 10-years of follow-up, each implant design demonstrated significant improvements in the KSS (p=0.001 kinemax, p=0.001 LCS) over pre-operative values. No significant difference could be identified between the two designs at 10 years. There were only two revisions in the whole study population and both were for kinemax implants at less than five years post-operatively. In conclusion, there was no statistically significant difference in outcome between the two radically different knee designs at ten years with both designs performing equally well

We assessed the effect of mental disability on the outcome of total knee replacement (TKR) and investigated whether mental health improves post-operatively. Outcome data were prospectively recorded over a three-year period for 962 patients undergoing primary TKR for osteoarthritis. Pre-operative and one year Short-Form (SF)-12 scores and Oxford knee scores (OKS) were obtained. The mental component of the SF-12 was stratified into four groups according to level of mental disability (none ≥ 50, mild 40 to 49, moderate 30 to 39, severe < 30). Patients with any degree of mental disability had a significantly greater subjective physical disability according to the SF-12 (p = 0.06) and OKS (p < 0.001). The improvement in the disease-specific score (OKS) was not affected by a patient’s mental health (p = 0.33). In contrast, patients with mental disability had less of an improvement in their global physical health (SF-12) (p < 0.001). However, patients with any degree of mental disability had a significant improvement in their mental health post-operatively (p < 0.001).

Despite a similar improvement in their disease-specific scores and improvement in their mental health, patients with mental disability were significantly more likely to be dissatisfied with their TKR at one year (p = 0.001). Patients with poor mental health do benefit from improvements in their mental health and knee function after TKR, but also have a higher rate of dissatisfaction.

Cite this article: Bone Joint J 2013;95-B:360–6.

We assessed the effect of social deprivation upon the Oxford knee score (OKS), the Short-Form 12 (SF-12) and patient satisfaction after total knee replacement (TKR). An analysis of 966 patients undergoing primary TKR for symptomatic osteoarthritis (OA) was performed. Social deprivation was assessed using the Scottish Index of Multiple Deprivation. Those patients that were most deprived underwent surgery at an earlier age (p = 0.018), were more likely to be female (p = 0.046), to endure more comorbidities (p = 0.04) and to suffer worse pain and function according to the OKS (p < 0.001). In addition, deprivation was also associated with poor mental health (p = 0.002), which was assessed using the mental component (MCS) of the SF-12 score. Multivariable analysis was used to identify independent predictors of outcome at one year. Pre-operative OKS, SF-12 MCS, back pain, and four or more comorbidities were independent predictors of improvement in the OKS (all p < 0.001). Pre-operative OKS and improvement in the OKS were independent predictors of dissatisfaction (p = 0.003 and p < 0.001, respectively). Although improvement in the OKS and dissatisfaction after TKR were not significantly associated with social deprivation per se, factors more prevalent within the most deprived groups significantly diminished their improvement in OKS and increased their rate of dissatisfaction following TKR.

Cite this article: Bone Joint J 2013;95-B:52–8.

224 patients from the Cardiff and Vale NHS Trust who had total knee replacements at the NHS Treatment Centre in Weston-Super-Mare by surgeons from overseas appeared to have significantly worse results than those recorded in the published literature. We wished to establish whether a group of patients treated in the same hospital with the same prosthesis at a similar time by local NHS orthopaedic surgeons in substantive posts would have a similar outcome.

Follow-up of all 214 patients (223 knee replacements) treated in 2004 was conducted with questionnaires, clinical review and x-ray assessment. In cases of no response, contact was made with GPs to establish the outcome of the surgery.

The outcome of all patients was known and of the 125 knee replacements available for clinical review at six years (mean), 119 cases (96%) achieved satisfactory coronal alignment with reference to the published literature. There were six revisions, five for loosening and one for malalignment. The cumulative survival rate for re-operation at six years was 97.2% (95% confidence interval 95.2 to 99.1).

This study shows that the results of total knee replacement performed by a group of NHS orthopaedic surgeons were comparable with other institutions and were significantly better than those reported from the NHS Treatment Centre in Weston-Super-Mare, using the same facilities and implant over the same period of time. This work supports previous recommendations for single surgeon supervision of the patient pathway and appropriate follow-up procedures.

The incidence of anterior knee pain following total knee replacement (TKR) is reported to be as high as 49%. The source of the pain is poorly understood but the soft tissues around the patella have been implicated. In theory circumferential electrocautery denervates the patella thereby reducing efferent pain signals. However, there is mixed evidence that this practice translates into improved outcomes. We aimed to investigate the clinical effect of intra-operative circumpatellar electrocautery in patients undergoing TKR using the LCS mobile bearing or Kinemax fixed bearing TKR. A total of 200 patients were randomised to receive either circumpatellar electrocautery (diathermy) or not (control). Patients were assessed by visual analogue scale (VAS) for anterior knee pain and Oxford knee score (OKS) pre-operatively and three months, six months and one year post-operatively. Patients and assessors were blinded. There were 91 patients in the diathermy group and 94 in the control. The mean VAS improvement at one year was 3.9 in both groups (control; -10 to 6, diathermy;. -9 to 8, p < 0.001 in both cases, paired, two-tailed t-test). There was no significant difference in VAS between the groups at any other time. The mean OKS improvement was 17.7 points (0 to 34) in the intervention group and 16.6 (0 to 42) points in the control (p = 0.36). There was no significant difference between the two groups in OKS at any other time. We found no relevant effect of patellar electrocautery on either VAS anterior knee pain or OKS for patients undergoing LCS and Kinemax TKR