Osteoarthritis Surgery
Given the risks inherent to surgical intervention for osteoarthritis of the knee and/or hip, particularly for older adult patients in whom such intervention is most likely, identification of predictors of good functional recovery is an important focus of arthritis-related research. The following studies addressed various aspects of this issue.
Abstract 886 Evaluating the Impact of the Process of Care on the Outcome of Total Knee Replacement Surgery: a Multinational Comparison
EA Lingard, JN Katz, EA Wright, CB SledgeKinemax Outcomes Group Boston, MA
Lingard and colleagues prospectively examined the influence of public care versus private care systems on functional outcomes in a multi-center study of 800+ patients spanning 3 nations (US, UK and Australia) who were referred for total knee replacement (TKR). Self-report measures of symptoms and function included the WOMAC, SF-36 and Knee society clinical rating scores. The results reported are that restricted knee flexion, low SF 36 mental health score, United kingdom (UK) center, female gender and obesity were significantly associated with lowest preoperative functional status. Low preoperative WOMAC function score, low preoperative SF 36 mental health score, UK center and co-morbid conditions were significant determinants of lower functional status 3 months following TKR. The authors conclude that poorer functional outcomes are associated with receiving care in systems dependent upon public funding.
Editorial Comment: Although the question of what extent does the health care system influence functional outcomes for those who undergo total joint arthroplasty is important, this study lacks the power to have done specific comparisons of public versus private systems within each nation. Furthermore, care setting may have been confounded by the aggregation of patients with poorer pre-operative function in public rather than privately funded systems. The predictive importance of lower pre-operative function and low mental health scores is apparent as significant predictors of function 3 months following TKR.
Abstract 1175Who is a Good Candidate for THR? Developing a Predictive Model for the Outcome of Patients Undergoing Total Hip Replacement
WC Beauchamp, JR Stieber, MJ Kallan, SA Hurst, RH Fitgerald, DA Albert Philadelphia, PA
This study utilized data from a national registry of hip arthroplasty that included 5869 patients who underwent this procedure between 1995 and 1997. Patients who reported use of assistance with walking prior to surgery, particularly for those with a greater duration of pain and less so for stiffness, reported the greatest improvement in functional score 3 months following total hip replacement. The authors conclude that the patients who suffer the most debilitation from their operative hip are those who experience the greatest benefit from the surgery.
Editorial Comments: The results of this study are expected and are consistent with the common practice of delaying surgery and reserving surgical replacement for those with pain and disability despite maximal medical therapy.
Abstract 1953 Determinants of Physical Functional Status Following Total Hip Replacement in a Population-Based Cohort
JN Katz, H Kaul, CB Phillips, AH Fossel, E Guadagnoli, RA Lew Boston, M
This study included a random sample of Medicare beneficiaries who received primary or revision total hip replacement (THR) in 1995 who were interviewed by telephone or mail in 1998-1999. 900 primary and 564 revision THR recipients completed surveys, who were a mean age of 73 years and 63% women. Although multiple variables were examined including socio-demographic characteristics and mental health indices, the presence of musculoskeletal co-morbidity (assessed by the sum of the number of painful joint regions) was the most powerful predictor of self-reported function 3-4 years following THR.
Editorial Comment: The results of this study have direct and broad-reaching implications regarding post-operative function in general, but particularly for older adult patients with arthritis in multiple locations. It offers a longer view of post-operative outcomes than the other studies presented.
Abstract 1542 Total Hip and Knee Replacement: Preoperative Function and Post-Operative Costs
Y St. Pierre, PR Fortin, D Ferland, JN Katz, M Tanzer, MH Liang, NN Mahomed, AE Clarke Montreal, Canada, Boston, MA, Toronto, Canada
This study addressed the question of the influence of preoperative function with post-operative direct and indirect costs. The study included 222 patients evaluated for THR or TKR at two hospitals and were followed for 6 months following surgery. Baseline function was assessed using the WOMAC instrument. Costs were summed over the hospitalization through discharge from rehabilitation up to 6 months following surgery. The results suggest that patients with poorer pre-operative function with an estimated 20% higher direct costs and 6% higher odds of incurring lost productivity for every 10 WOMAC higher points. The authors conclude that worse pre-operative functional status results in higher post-operative costs, both due to direct costs and lost productivity.
Editorial Comment: This prospective study provides us with the economic prospective of the costs associated with hip and knee osteoarthritis. The study did not, however, estimate the extent to which costs incurred were directly attributable to the surgical hip or due to co-morbidities and generalized deconditioning that may accompany advanced OA.
Summary: The above studies begin to address the important question of who is likely to benefit from total joint arthroplasty. In examining this question, it is important to factor in the disease for which surgery is being recommended (OA vs RA or other disease), the number of co-morbid arthritis joints, the number and specific type of co-morbid medical conditions. Furthermore, several of these studies have illustrated the importance of addressing psychosocial issues in studying this issue. Although the results of these studies may seem contradictory on the surface (better post-operative function is associated with better pre-operative function in one study while associated with greater pre-operative disability in another), these differences may be attributable to difference in the measures used to define pre-operative functional status or differences in post-operative outcomes (e.g. functional status achieved versus change in function from baseline). Overall, this is an important area of arthritis research that should focus on functional outcomes in the immediate, short-term and long-term points along the pathway of recovery.