We report the largest multicentre series analysing the use of bone scans investigating painful post-operative Total Knee Replacements (TKR). We questioned the usefulness of reported scintigraphic abnormalities, and how often this changed subsequent management. 127 three-phase bone-scans were performed during a two-year period. Early and late flow phases were objectively classified. Reported incidences of infection and loosening were determined. Reports were subjectively summarised and objectively analysed to establish the usefulness of this investigation. Eight cases were excluded.

Scans were classified as: 33% (39) normal, 53% (63) as possibly abnormal, 6% (7) probably abnormal, and 8% (10) as definitely abnormal. Thirteen patients (11%) underwent revision TKR surgery. Intra-operative analysis revealed loosening of one femoral component, and massive metallosis of the patella in another. Cultures were negative in all cases. The sensitivity and specificity of a definitely abnormal investigation in predicting need for revision surgery was 23% and 82% (respectively). High instances of ambiguously reported abnormalities were observed.

This investigation has no role to play in the routine investigation of a painful TKR. It is unnecessary in investigation of periprosthetic infection and should not be used in a routine assessment of a painful TKR. If used it should be limited until an experienced revision surgeon has made a full assessment.

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. Methods. Well-functioning primary TKAs (n = 11), failed non-fibrotic TKAs (n = 5), and patients with a clinical diagnosis of fibrosis. 1. (n = 8) underwent an MRI scan with advanced metal suppression (Slice Encoding for Metal Artefact Correction, SEMAC) with gadolinium contrast. Fibrotic tissue (low intensity on T1 and T2, low-moderate post-contrast enhancement) was quantified (presence and tissue thickness) in six compartments: supra/infrapatella, medial/lateral gutters, and posterior medial/lateral. Results. Fibrotic tissue was identified in all patients studied. However, tissue was significantly thicker in fibrotic patients (4.4 mm ± 0.2 mm) versus non-fibrotic (2.5 mm ± 0.4 mm) and normal TKAs (1.9 mm ± 0.2 mm, p = < 0.05). Significant (> 4 mm thick) tissue was seen in 26/48 (54%) of compartments examined in the fibrotic group, compared with 17/30 (57%) non-fibrotic, and 10/66 (15%) normal TKAs. Although revision surgery did improve range of movement (ROM) in all fibrotic patients, clinically significant restriction remained post-surgery. Conclusion. Stiff TKAs contain intra-articular fibrotic tissue that is identifiable by MRI. Studies should evaluate whether MRI is useful for surgical planning of debridement, and as a non-invasive measurement tool following interventions for stiffness caused by fibrosis. Revision for stiffness can improve ROM, but outcomes are sub-optimal and new treatments are required. Cite this article: Bone Joint J 2020;102-B(10):1331–1340

Between December 1998 and December 1999 twenty-one patients with painful knee arthroplasties underwent assessment by radionuclide arthrography. There were eleven female and ten male patients, with an average age of 60 years at the time of the index procedure. The index procedure was a primary total knee arthroplasty, primary medial unicompartmental knee arthroplasty and revision medial UKA in seventeen, three and one patients respectively. Nineteen arthroplasties were uncemented and two were hybrids. All patients had previously been investigated by clinical examination, serological testing, fluoroscopic AP and lateral radiographs, and Tc99 bone scan with equivocal results. The presence of radionuclide about the tibial stem was considered diagnostic of tibial loosening. Nine patients underwent revision knee arthroplasty. The presence of radionuclide about the tibial stem correctly predicted a loose tibial component in four of five cases. Similarly, the absence of radionuclide about the tibial stem correctly predicted a stable tibial component in four of four cases. In the single misdiagnosed case the tibial component did not have a large central stem, had focal osteolysis about several screws, but remained stable. Radionuclide arthrogram is a useful tool in the investigation of painful knee arthroplasty. Radionuclide about the tibial stem is the key predictor of tibial component loosening

Aims

To perform an incremental cost-utility analysis and assess the impact of differential costs and case volume on the cost-effectiveness of robotic arm-assisted unicompartmental knee arthroplasty (rUKA) compared to manual (mUKA).

The December 2013 Knee Roundup. 360 . looks at: Conflict of interest and hyaluronic acid; Will time indeed tell in microfracture?; Contralateral knee pain and joint replacement outcomes; Patient satisfaction and knee replacement?; Hope in the cytokines for painful TKRs?; Pain severity, cytokines and osteoarthritis?; Quadriceps weakness and pain; and spontaneous osteonecrosis of the knee

Introduction: We describe a CT method that allows the seven alignment characteristics of a knee arthroplasty to be defined in a single investigation. Method: A multislice CT scanner, scans in 2.5mm slices from the acetabular roof to the dome of the talus with the legs in a standard position. The mechanical and anatomical axes are identified, from 3 dimensional landmarks, in both AP and lateral planes. The coronal and sagittal alignment of the pros-theses is then measured against the axes. The rotation of the femoral component is measured relative to the transepicondylar axis. Tibial rotation was measured with reference to the posterior tibial condyles and the tibial tuberosity. Coupled femorotibial rotational alignment was assessed by superimposition of the femoral and tibial axial images. The results of 100 scans show a low inter and intra observer error rate whilst independent assessment shows a mean measurement error of 3mm in a three dimensional plane. The radiation dose is 2.7mSV. Conclusions: The technique provides the only currently available measure of all the alignment characteristics required to assess the quality of a knee arthroplasty. It will become a gold standard in planning revision surgery and provide a valuable tool in assessing alignment of painful knee replacements

Plain radiographs are a poor indication of the overall coronal, sagittal and axial alignment of a total knee arthroplasty (TKA). We describe a new CT method that allows the mechanical axis in both planes to be defined and seven alignment characteristics to be defined. A GE Light Speed multislice CT scanner performed a high-speed helical scan from the acetabular roof to the talus in 100 patients following TKA. The knees were scanned in a supine position with the legs in a neutral position. The images were reformatted in coronal, sagittal and axial planes and the mechanical and anatomical axes identified. The femoral component (varus/ valgus, flexion/extension, rotation) as well as the tibial – (varus/valgus, posterior slope and rotation) are measured. Coupled femoro-tibial rotational alignment was assessed by superimposition of the femoral and tibial axial images. The accuracy of this technique has been checked by using a mechanical FARO-arm. The technique has a low intraobserver error rate of 9% (in each case less than 1 degree) and an accuracy of 3mm in a three-dimensional plane, as determined against an independent FARO arm technique. The CT analysis of 100 patients shows normal tibial baseplate rotation to be 8–12 degrees from the tibial tuberosity. Conclusion: The CT protocol is the first single radiographic investigation that characterizes all the alignment parameters of a TKA. It sets an excellent standard in planning revision knee surgery and provides a valuable tool in assessing alignment of painful knee replacements as well as in outcome measures of TKA

Femoral component fracture is a rarely reported but devastating complication of total knee arthroplasty. It has occurred most frequently with Whiteside Ortholoc II replacements uncemented knee replacements. Presentation may be with acute pain, progressive pain or returning deformity. It occurs more commonly in the medial condyle of the femoral component. It is rarely seen in cemented replacements. All currently available literature describing fractures of condylar replacements, both cemented and uncemented. Predisposing factors include varus deformity either pre or post operatively. The mechanism of failure is thought to be failure of the infiltration of bone into the replacement. This is often due to polyethylene wear or metallosis causing abnormal tissue reaction with or without osteolysis. We present the case of a fractured Press Fit Condylar (PFC) cemented implant (DePuy, Johnson&Johnson, Raynham, Massachusettes, USA) affecting the medial condyle. To our knowledge this is only the third reported case of fracture in a PFC implant, and the first in a cemented PFC implant. Our patient was a 64 year old male who presented with unresolving knee pain post total knee arthroplasty, caused by fatigue fracture of the medial condyle of the femoral component. This was identified as loosening on plain radiographs and replaced with a revision prosthesis with a good post operative result. Given our aging population and with the increase of joint arthroplasty, this case sheds light on a potentially under recognised and increasingly important cause of knee pain following arthroplasty

Introduction: Pain is one of the most important outcome measures that contributes to patient dissatisfaction following total knee arthroplasty (TKA) and unexplained pain poses a difficult problem to manage. This paper focuses on a group of patients with unexplained knee pain post arthroplasty to identify any predictors of a poor pain outcome. Methods: A prospective study of 622 primary TKAs performed on 512 patients using cemented press fit condylar prosthesis was the basis to examine a group of patients that reported moderate or severe pain at 5 years. Demographic and operative variables as well as American Knee Society Scores were collected prospectively. Data was available for 462 knees at 5 years. After exclusion of patients with mild pain, two groups were generated; 374 with no pain and 28 with moderate or severe unexplained pain. Univariate linear analysis was performed to identify possible predictors of poor outcome and this was further refined using multiple regression analysis to remove the effect of confounding factors. Results: Comparison of the pain and no pain group found the following to be significant predictors of poor outcome: Staged approach to bilateral disease when compared to simultaneous bilateral surgery (13% vs 2%, P< 0.01), age below 60 (17% vs 7%, P< 0.01) and performing lateral release (13% vs 5%, P< 0.01). Other factors which had no predictive effect were gender, body mass index, operating surgeon, patella component, instability and range of motion. Conclusions: Avoiding surgery in patients aged below 60 and performing simultaneous bilateral TKA instead of a staged approach to bilateral disease, should aid selection of patients for improved outcome in terms of pain. Good surgical technique to avoid lateral release is also recommended to improve outcome