Aims. Both the femoral and tibial component are usually cemented at revision total knee arthroplasty (rTKA), while stems can be added with either cemented or press-fit (hybrid) fixation. The aim of this study was to compare the long-term stability of rTKA with cemented and press-fitted stems, using radiostereometric analysis (RSA). Methods. This is a follow-up of a randomized controlled trial, initially involving 32 patients, of whom 19 (nine cemented, ten hybrid) were available for follow-up ten years postoperatively, when further RSA measurements were made. Micromotion of the femoral and tibial components was assessed using model-based RSA software (RSAcore). The clinical outcome was evaluated using the Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score (KOOS), and visual analogue scale (pain and satisfaction). Results. The median total femoral translation and rotation at ten years were 0.39 mm (interquartile range (IQR) 0.20 to 0.54) and 0.59° (IQR 0.46° to 0.73°) for the cemented group and 0.70 mm (IQR 0.15 to 0.77) and 0.78° (IQR 0.47° to 1.43°) for the hybrid group. For the tibial components this was 0.38 mm (IQR 0.33 to 0.85) and 0.98° (IQR 0.38° to 1.34°) for the cemented group and 0.42 mm (IQR 0.30 to 0.52) and 0.72° (IQR 0.62° to 0.82°) for the hybrid group. None of these values were significantly different between the two groups and there were no significant differences between the clinical scores in the two groups at this time. There was only one re-revision, in the hybrid group, for infection and not for aseptic loosening. Conclusion. These results show good long-term fixation with no difference in micromotion and clinical outcome between fully cemented and hybrid fixation in rTKA, which builds on earlier short- to mid-term results. The patients all had type I or II osseous defects, which may in part explain the good results. Cite this article: Bone Joint J 2022;104-B(7):875–883

Aims

The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthroplasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinematics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA).

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.

Periprosthetic joint infection (PJI) is one of the most feared and challenging complications following total knee arthroplasty. We provide a detailed description of our current understanding regarding the management of PJI of the knee, including diagnostic aids, pre-operative planning, surgical treatment, and outcome.

Cite this article: Bone Joint J 2015;97-B(10 Suppl A):20–9.

Instability is the reason for revision of a primary total knee replacement (TKR) in 20% of patients. To date, the diagnosis of instability has been based on the patient’s symptoms and a subjective clinical assessment. We assessed whether a measured standardised forced leg extension could be used to quantify instability.

A total of 25 patients (11 male/14 female, mean age 70 years; 49 to 85) who were to undergo a revision TKR for instability of a primary implant were assessed with a Nottingham rig pre-operatively and then at six and 26 weeks post-operatively. Output was quantified (in revolutions per minute (rpm)) by accelerating a stationary flywheel. A control group of 183 patients (71 male/112 female, mean age 69 years) who had undergone primary TKR were evaluated for comparison.

Pre-operatively, all 25 patients with instability exhibited a distinctive pattern of reduction in ‘mid-push’ speed. The mean reduction was 55 rpm (sd 33.2). Post-operatively, no patient exhibited this pattern and the reduction in ‘mid-push’ speed was 0 rpm. The change between pre- and post-operative assessment was significant (p < 0.001). No patients in the control group exhibited this pattern at any of the intervals assessed. The between-groups difference was also significant (p < 0.001). This suggests that a quantitative diagnostic test to assess the unstable primary TKR could be developed.

Cite this article: Bone Joint J 2014;96-B:1339–43.