Associations between pre-operative radiographic changes and outcomes after total knee joint replacement for osteoarthritis.
OBJECTIVE
To assess the influence of pre-operative X-ray changes on the response to total knee joint replacement (TKR).


METHODS
We included patients from one centre who underwent primary TKR (n = 478) for osteoarthritis in 2006 and 2007. The International Knee Society score (IKSS) and short form health survey were collected pre-operatively and at 1 and 2 years after surgery. Pre-operative radiographs were read to assess Kellgren and Lawrence (K-L) grading, individual radiographic features using the OARSI atlas, and subchondral bone attrition using the Ahlbach method. The main independent variable was a modified (K-L) grade. The outcome variables were the IKSS pain and function scores. Covariates included demographic features, co-morbidities, baseline pain and function, prosthesis type, and the use of patella resurfacing. Multivariable linear regression models were created to assess the relationships between pre-operative X-ray findings and pain and function outcomes.


RESULTS
On average, pain and function improved greatly following surgery. However, pain relief was unsatisfactory in about 30%, and functional improvement suboptimal in about 50%. OR (95% CI) for ongoing moderate-severe pain at 12 months for modified K-L grades; <3: 5.39 (1.23-15.69), 3a: 2.62 (1.21-5.67), 3b: 1.81 (1.00-3.26), 4a: 2.06 (1.05-4.05) when compared to 4b. OR (95% CI) for poor function at 12 months were; 3a: 2.81 (1.23-6.39) and 4a: 2.45 (1.22-4.91), when compared to 4b.


CONCLUSIONS
Patients with more severe radiographic knee damage at the time of surgery are most likely to have substantial gains in terms of both pain relief and improved function as a result of a TKR.
Department of Orthopaedics, St. Vincent's Hospital Melbourne, Australia. mmdowsey@unimelb.edu.au
M M
MM
Dowsey
M
M
Nikpour
P
P
Dieppe
P F M
PF
Choong
D000203:Activities of Daily Living; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D015519:Bone Density; D001862:Bone Resorption; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D008297:Male; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D054850:Osteophyte / Q000000981:diagnostic imaging / Q000473:pathology; D010146:Pain / Q000209:etiology / Q000503:physiopathology; D010147:Pain Measurement; D011183:Postoperative Complications; D057234:Preoperative Period; D011859:Radiography; D020127:Recovery of Function; D016896:Treatment Outcome