Numbness Around the Total Knee Arthroplasty Surgical Scar: Prevalence and Effect on Functional Outcome.

BACKGROUND: Numbness around the surgical scar can be a source of discomfort or dissatisfaction in a proportion of patients undergoing total knee arthroplasty (TKA). Literature reports wide variation in its prevalence and the consequence of numbness on the outcome of TKA is not clear. We investigated the prevalence of numbness, along with contributing factors, and assessed its effect on the functional outcome of TKA. METHODS: In total, 258 knees were included in this prospective patient-reported outcome measure case-control study. Demographic details, type and length of incision, pre-operative and 1-year post-operative Knee Society Scores were recorded and compared. RESULTS: The prevalence of numbness at 1 year was 53%, with a female preponderance. Patients older than 70 years were less affected. Discomfort due to numbness was recorded in 8.7% of the patients, 75% of which were female. The length of the incision correlated positively with the presence of numbness. The Knee Society Scores did not correlate with the presence or area of numbness. CONCLUSION: Our findings indicate a high prevalence of numbness after TKA. Nevertheless, numbness does not affect the functional outcome.

Testing the integration of ICF and behavioral models of disability in orthopedic patients: replication and extension.

OBJECTIVE: Disability from chronic illness is a major problem for society, yet the study of its determinants lacks an overall theoretical paradigm. Johnston (1996) has proposed conceptualizing disability as behavior and integrating biomedical and behavioral predictors. Dixon, Johnston, Rowley, and Pollard (2008) tested a model including constructs from the International Classification of Functioning, Disability and Health (ICF) and the theory of planned behavior (TPB) using structural equation modeling; it fitted better and explained more variance than the ICF or TPB alone. We replicated their study with a new sample from the same population (orthopedic patients awaiting joint replacement) and also tested the model after the patients had surgery. METHODS: Two weeks before surgery, 342 orthopedic patients who had joint pain (most with arthritis) completed a questionnaire, with 228 completing it again 1 year after surgery. The authors tested Dixon et al.'s best-fit models cross-sectionally (before and after surgery) and assessed the goodness of fit of these imposed models to our data using structural equation modeling. RESULTS: Findings strongly supported those of Dixon et al. Before surgery, results were very similar to Dixon et al. with all models accounting for significant variance and fitting well, but the integrated model fitted better and accounted for more variance. One year after surgery, Dixon et al.'s models showed even stronger fit to the data. CONCLUSIONS: Although behavioral and biomedical (ICF) models were supported, the integrated model provided a better explanation of disability in this population than either of these models alone and suggests biopsychosocial interventions to reduce disability.

Dysfunction of the posterior cruciate ligament in total knee arthroplasty.

PURPOSE: Total knee arthroplasty (TKA) is typically carried out either with retention (CR) of the posterior cruciate ligament (PCL) or with sacrifice of this ligament and implantation of a posterior stabilised (PS) prosthesis. This paper investigates a comparison of PCL function in knees treated for osteoarthritis with TKA where the PCL is preserved to those knees treated with TKA and posterior stabilisation. METHODS: One hundred and sixty-eight patients (232 knees) who had undergone TKA with either a PS or CR implant were included in the study. Clinical assessment included antero-posterior (AP) laxity and posterior sag assessment with an arthrometer. RESULTS: The mean AP laxity at 90° of flexion for CR TKAs was 6.5 mm (±3.1) and was the same [6.5 mm (±2.4)] as in the PS group. However, 56% of the PCL-preserved knees had a posterior sag of over 3 mm compared to 18% of the knees in the PS group. The American Knee Society Scores for either group showed that, although the mean function score was the same, the knee score was superior in the PS group (77 vs. 84). The range of motion was also superior in the PS group (111° vs. 105°). CONCLUSION: The use of the PS prosthesis for TKA provides a more predictable outcome with regard to posterior sag and a better maximum flexion than a CR implant.

Activity and affect: repeated within-participant assessment in people after joint replacement surgery.

OBJECTIVE: Between-participant research has shown that high negative affectivity predicts greater activity limitations and vice versa. This study examined both between- and within-participant associations of negative and positive affectivity with activity levels using ecological momentary assessment. METHOD: Participants were 25 people who had undergone joint replacement surgery 12 months previously. Participants made multiple reports of their activity and positive and negative affectivity over a single day using a computerized diary. Activity was also objectively recorded using an activity monitor. The following day, participants made a self-report of their activity over the measurement day and general positive and negative affectivity levels were recorded. RESULTS: Higher self-reported walking time over the whole measurement day was associated with higher general positive affectivity but not negative affectivity. However, using ecological momentary assessment, higher diary reports of negative affectivity predicted increased activity levels while positive affectivity neither predicted nor was predicted by activity. CONCLUSION: These findings demonstrate the importance of within-participant methodology in detecting subtle and immediate effects of individuals' mood on behavior that may differ from findings investigating between-participant effects over longer time periods.