CAPAbility: comparison of the JOURNEY II Bi-Cruciate Stabilised and GENESIS II total knee arthroplasty in performance and functional ability: protocol of a randomised controlled trial

Comparison of the Journey II bicruciate stabilised (JII-BCS) and GENESIS II total knee arthroplasty for functional ability and motor impairment: the CAPAbility, blinded, randomised controlled trial

OBJECTIVES

To determine if a newer design of total knee replacement (TKR) (Journey II BCS) produces superior patient-reported outcomes scores and biomechanical outcomes than the older, more established design (Genesis II).

SETTING

Patients were recruited from an NHS University Hospital between July 2018 and October 2019 with surgery at two sites. Biomechanical and functional capacity measurements were at a University Movement and Exercise Laboratory.

PARTICIPANTS

80 participants undergoing single-stage TKR.

INTERVENTIONS

Patients were randomised to receive either the Journey II BCS (JII-BCS) or Genesis II TKR.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome was the Oxford Knee Score (OKS), at 6 months. Secondary outcomes were: OKS Activity and Participation Questionnaire, EQ-5D-5L and UCLA Activity scores, Timed Up and Go Test, 6 min walk test, lower limb kinematics and lower limb muscle activity during walking and balance.

RESULTS

This study found no difference in the OKS between groups. The OKS scores for the JII-BCS and Genesis II groups were mean (SD) 42.97 (5.21) and 43.13 (5.20) respectively, adjusted effect size 0.35 (-2.01,2.71) p=0.771In secondary outcome measures, the Genesis II group demonstrated a significantly greater walking range-of-movement (50.62 (7.33) vs 46.07 (7.71) degrees, adjusted effect size, 3.14 (0.61,5.68) p=0.02) and higher peak knee flexion angular velocity during walking (mean (SD) 307.69 (38.96) vs 330.38 (41.40) degrees/second, adjusted effect size was 21.75 (4.54,38.96), p=0.01) and better postural control (smaller resultant centre of path length) during quiet standing than the JII-BCS group (mean (SD) 158.14 (65.40) vs 235.48 (176.94) mm, adjusted effect size, 59.91 (-105.98, -13.85) p=0.01.).

CONCLUSIONS

In this study population, the findings do not support the hypothesis that the Journey II BCS produces a better outcome than the Genesis II for the primary outcome of the OKS at 6 months after surgery.

TRIAL REGISTRATION NUMBER

ISRCTN32315753.

CT measures of femoral and tibial version and rotational position of femoral and tibial components of knee replacements: limitations in reliability and suitability for routine clinical practice

OBJECTIVES

Rotational malalignment of knee replacements as measured on CT is understood to be associated with poor outcomes. The aim of this study is to measure the inter-rater and intra-rater reliability of measures of femoral and tibial version in the native arthritic knee and postoperative TKR component position using CT.

METHODS

Eighty patients underwent CT of the knee before and after total knee replacement. Preoperative femoral and tibial version and component rotation were independently measured by two musculoskeletal radiologists.

RESULTS

Mean differences between and within raters were small (< 1.6°). Maximum 95% limits of agreement for inter-rater and intra-rater comparisons were 8.1° and 7.6° for preoperative femoral version, 9.0° and 7.9° for postoperative femoral rotation, 26.0° and 20.5° for preoperative tibial version, and 24.9° and 23.6° for postoperative tibial rotation respectively. Postoperative ICCs varied from 0.68 to 0.81 (lower 95% CI:0.55-0.72) for both intra- and inter-rater comparisons. Preoperative ICCs were lower: 0.55-0.75 (lower 95% CI:0.40-0.65).

CONCLUSION

The lower 95% confidence level for ICC of version and rotational measurements using the Berger protocol of TKRs on CT are all less than 0.73 and that the normal range of differences between observers is up to 9° for the femoral component and 26° for the tibial component. This suggests that CT measurements derived from the Berger protocol may not be consistent enough for clinical practice.

KEY POINTS

• CT is commonly used to measure the rotational profile of knee replacements in symptomatic patients using the Berger protocol. • The limits of agreement for both femoral and tibial component rotation are wide even for experienced observers. • CT measurements of the rotation of knee arthroplasty are not reliable enough for routine clinical use.