Reliability of radiographic measurements of knee motion following knee arthroplasty for use in a virtual knee clinic

Inter- and intra-rater reliability of knee flexion angle measurements on X-ray and MRI

Background

Range of motion (ROM) is an important aspect of orthopaedic patient assessment. It can be measured at the knee joint by determining the knee flexion angle (KFA) a patient can achieve at extremes of flexion and extension. As with any measurement, the accuracy and reliability of the method used determine its validity. The consistency of magnetic resonance imaging (MRI) scans as compared to the current gold standard of X-ray remains unknown in terms of KFA evaluation. The aim of this study was to assess and compare the reliability of measuring KFA between X-ray and MRI scans.

Methods

This study included 80 patients (94 knees) who had attended a specialist knee clinic due to varying knee pathologies and undergone both X-ray and MRI scans. Lateral and T1-weighted sagittal imaging views (respectively) were used to measure KFA by two trained observers independently at two separate time points, 8 weeks apart. The data was then statistically analysed and intra- and inter-observer reliability calculated using the intraclass correlation coefficient (ICC).

Results

The intra-observer reliability for X-ray was 0.96 (P<0.001) and that for MRI was 0.83 (P<0.001). The inter-observer reliability for X-ray was 0.99 (P<0.001) and that for MRI was 0.81 (P<0.001). All the intra-class correlation coefficients were graded as excellent in both the intra- and inter-observer reliability analysis. Overall, the mean KFA was notably higher on X-ray measurements than that on MRI scans. There was a statistically significant difference between Time 1 and Time 2 measurements (17.7° vs. 16.8°) for MRI data (P=0.022). No significant difference was found for X-ray measurements (46.4° vs. 45.6°) in this regard (P=0.182).

Conclusions

Both X-ray and MRI allow KFA to be measured with an excellent degree of reliability. However, X-ray measurements were overall superior to that of MRI mainly due to the larger field of view of the visible on-screen image which more readily identifies the anatomical landmarks required to measure KFA.

Can stretch sensors measure knee range of motion in healthy adults?

Study aim: There are currently limited methods available to access dynamic knee range of motion (ROM) during free-living activities. This type of method would be valuable for monitoring and progressing knee rehabilitation. Therefore, the aim of this study was to evaluate the functioning of stretch sensors for the measurement of knee ROM and to assess the level of the measurement error. Material and methods: Nine healthy participants were included in the study. Three stretch sensors (StretchSense™, Auckland, NZ) were attached on the participants’ right knees by Kinesiotape®. A Cybex dynamometer was used to standardise movement speed of the knee joint. Data was recorded through the StretchSense™ BLE application. Knee angles were obtained from the video clips recorded during the testing and were analysed by MaxTraq® 2D motion analysis software. The knee angles were then synchronised with the sensor capacitance through R programme. Results: Seven out of the nine participants presented with high coefficient of determination (R2) (>0.98) and low root mean square error (RMSE) (<5°) between the sensor capacitance and knee angle. Two participants did not confirm good relationship between capacitance and knee angle as they presented high RMSE (>5°). The equations generated from these 7 participants’ data were used individually to predict knee angles. Conclusions: The stretch sensors can be used to measure knee ROM in healthy adults during a passive, non-weight-bearing movement with a clinically acceptable level of error. Further research is needed to establish the validity and reliability of the methodology under different conditions before considered within a clinical setting.

Factors affecting the incidence and management of fixed flexion deformity in total knee arthroplasty: A systematic review

PURPOSE

This study aimed to systematically review the literature and identify factors which would contribute to the intraoperative correction of FFD to frame a potential surgical algorithm or predictive model to guide intraoperative decision-making.

METHODS

Electronic searches of six databases were undertaken in April 2016 according to the PRISMA guidelines, and the reference lists of studies searched. Quality of studies was assessed using the STROBE checklist, and the Downs and Black Scores.

RESULTS

Twenty-five studies investigating 10, 679 knees were found to satisfy the inclusion and exclusion criteria. These studies described a variety of pre-operative and intra-operative factors which contribute to the development or correction of post-operative FFD. The only patient predictor of post-operative FFD was pre-operative FFD. The intra-operative steps described to correct FFD were: distal femoral resection, soft-tissue balancing (in the posterior and medial compartments), sagittal component flexion and posterior condylar offset. However, no studies investigated these in an integrated model.

CONCLUSION

This review has identified various pre-, intra- and post-operative factors predictive of post-operative FFD. In practice, these factors are likely to interact, and therefore further investigation in an integrated model is crucial to developing a statistically sound and reliable intraoperative algorithm for surgeons to follow when correcting fixed flexion deformity.

Comparison of self-reported and measured range of motion in total knee arthroplasty patients

Total knee arthroplasty (TKA) is an established method used in the treatment of end-stage knee osteoarthritis. Range of motion (ROM) and relief from pain show success of TKA. One of the most important aims of this treatment is to achieve an adequate ROM. Numerous outcome instruments and patient-reported questionnaires are in use to evaluate of TKA patients. For this purpose, disease-specific questionnaires and self-reported ROM and function evaluation tools are also being developed. The most important criteria in musculoskeletal care is assessing the joint mobility of the patient's. Joint mobility can be measured with visual estimates, universal goniometer, X-ray radiography, digital gravity goniometers and applications found in smart phones. Apart from the reliability and validity of the method, obtaining the same results from different examiners is very important. The clinical follow-up of patients is an important part of postoperative care after TKA. The follow-up interval and duration remain dependent on the physician's anticipation of the clinical progress of the individual patient. Long-term surveillance of joint arthroplasty is necessary, but it has also become increasingly burdensome as greater numbers of TKAs are performed, and in younger populations. Patient self-reported questionnaires and self-goniometric measurement are used by many investigators to decrease this burden on the surgeon or staff, and in combination with telemedicine radiographs might be a reasonable option to routine clinic visits. They could reasonably be expected to lower the burden on both the patient and the clinician without eliminating contact and thus sacrificing quality of care. At the same time, it would reduce the financial burden too. Self-reported measured ROM can use in the routine follow-ups to reduce surgeons, physiotherapist and other staff.