Psychosocial predictors of outcomes up to one year following total knee arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) aims to relieve pain and improve physical functioning of the knee, however, some patients continue to experience pain and impaired function following TKA which cannot be explained by surgical and implant factors. Psychological factors may influence the outcomes of TKA. The aim of this prospective study was to examine the psychosocial factors that predicted pain, stiffness and physical functioning up to one year following TKA. METHODS: One hundred and two patients completed pre-operative and one-year questionnaires which assessed a wide range of psychosocial and sociodemographic factors prior to surgery. The Oxford Knee Score (OKS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain, Stiffness and Physical Functioning subscales were used as outcome measures. Pearson correlation analysis and multiple linear regression were conducted to examine relationships between predictor and outcome variables. RESULTS: Regression analysis showed that regarding variance in WOMAC outcome measures post TKA, our model predicted 31% for physical functioning, 25% for pain and 29% for stiffness at one year. Regarding variance in OKS post TKA, the model predicted 36% at one year. Greater levels of depressive symptoms and neuroticism and worse pre-operative scores significantly predicted poorer outcomes. CONCLUSIONS: The findings indicate that pre-operative psychosocial factors are important in understanding outcomes of TKA. Psychosocial factors could be considered during pre-operative assessment. Further research conducted on psychological interventions is needed within this population to determine whether early and one-year outcomes can be improved.

Negative-pressure wound therapy II: negative-pressure wound therapy and increased perfusion. Just an illusion?

BACKGROUND: A recent study demonstrated that negative-pressure wound therapy increases underlying tissue pressure. This finding is incongruous with studies using laser Doppler that show that perfusion is immediately increased on initiation of suction. This study investigated perfusion in negative-pressure wound therapy using two alternative modalities. METHODS: Radioisotope perfusion imaging was used to determine perfusion beneath circumferential negative-pressure wound therapy dressings on 20 healthy hands (n = 20). Ten hands received suction pressures of -400 mmHg and 10 received -125 mmHg, with the contralateral hand used as a control without any suction. Transcutaneous partial pressure of oxygen was used to determine perfusion beneath noncircumferential negative-pressure wound therapy dressings on 12 healthy legs (n = 12), with each volunteer being sequentially randomized to receive suction pressures of -400 and -125 mmHg, respectively. RESULTS: Tissues undergoing circumferential negative-pressure wound therapy demonstrated a mean reduction in perfusion of 40 +/- 11.5 percent (p < 0.0005) and 17 +/- 8.9 percent (p < 0.0005) at suction pressures of -400 mmHg and -125 mmHg, respectively. Perfusion reduction at -400 mmHg was significantly greater than at -125 mmHg (p < 0.015). In the noncircumferential negative-pressure wound therapy group, there was a mean reduction in transcutaneous partial pressure of oxygen of 7.35 +/- 7.4 mmHg (p < 0.0005) and 5.10 +/- 7.4 mmHg (p < 0.0005) at suction pressures of -400 mmHg and -125 mmHg, respectively. There was a tendency for greater reductions in the -400 mmHg group, but this was not significantly different from the -125 mmHg group (p = 0.07). CONCLUSIONS: These findings demonstrate that perfusion beneath negative-pressure wound therapy decreases for increasing suction pressure. Thus, it is suggested that negative-pressure wound therapy should be used with caution on tissues with compromised vascularity, particularly when used circumferentially.