Comparison of pain, functional and psychological trajectories between total and unicompartmental knee arthroplasties: secondary analysis of a 6-month prospective observational study

Introduction Unicompartmental knee arthroplasty (UKA) treats osteoarthritis in one knee compartment, while total knee arthroplasty (TKA) addresses all compartments. The debate focuses on UKA's advantages of quicker recovery and fewer complications versus TKA's lower long-term revision rates, emphasizing the need for thorough outcome evaluations. The aim of the present study is to describe and compare the pain, functional and psychological trajectories during a 6-month postoperative rehabilitation period between total and unicompartmental knee arthroplasties. Materials and Methods 115 participants who had undergone either TKA or UKA were recruited. Outcome measurements were performed at 1, 4, 12 and 24 weeks post-surgery. Measurements included pain intensity (Visual Analog Scale), range of motion, walking speed (4 m walking test), physical performance (30-s chair stand test), health functioning (Western Ontario and McMaster Universities Osteoarthritis Index), pain catastrophizing (pain catastrophizing scale), fear of movement (Tampa Scale of Kinesiophobia), anxiety and depression (Hospital Anxiety and Depression Scale). A mixed-effects model was used to estimate the influence of type of surgery (either unicompartmental or total knee arthroplasty) to pain, function, and psychological trajectories. Results Both TKA and UKA groups showed significant improvements across the six-month rehabilitation period except for anxiety symptoms in the TKA group, and fear of movement and depression in the UKA group. Between group analysis revealed that in the acute phase UKA patients showed improved range of motion and TKA patients displayed faster walking speed but higher fear of movement. Overall, the type of surgery does not significantly influence the overall rehabilitation pain, functional and psychological trajectories. Conclusions Despite differences in the acute phase, there are no differences in pain, functional and psychological trajectories throughout the six-month rehabilitation period. These results should be acknowledged to better inform patients and to improve patient education during the perioperative period. Trial registration number NCT03378440 (2017-12-18), retrospectively registered. Level of evidence Level II.