Relationship between radiological grading and clinical status in knee osteoarthritis. A multicentric study.

Background: Controversy exists regarding the relationship between radiographic findings and clinical status in knee osteoarthritis. Although the surgical indication for total knee arthroplasty (TKA) should be based on pain, clinical status, and the deterioration of quality of life, the radiographic study is the most commonly used criterion for preoperative evaluation. The objective of this study is to find out the relationship between the Ahlbäck classification and clinical status in patients undergoing TKA.

Methods: 1329 protocols were collected from preoperative studies in four multicentric working groups (the Interax, Duracon, Scorpio, and Triathlon Spanish groups) in 30 Spanish hospitals. Mean age was 70.4 years (SD: 6.8; range: 35 to 98); 76.3% of patients were women. Patients entered the study whenever the surgeon found that medical treatment was insufficient to control pain and functional limitation. Data were collected using electronic Case Report Forms, and included Ahlbäck grading scores, Hospital for Special Surgery Knee Score (HSS), SF-12, and other clinical and epidemiologic variables.

Results: According to the Ahlbäck grading system, patients were divided as follows: 243 grade I (18.3%), 358 grade II (26.9%), 416 grade III (31.3%), 241 grade IV (18.1%), and 71 grade V (5.3%). As for HSS, the following scores were obtained: <60 points in 925 patients (69.6%), 60 to 69 points in 286 patients (21.5%), 70 to 84 points in 112 patients (8.4%) and 85 to 100 points in 6 patients (0.5%). Scores showed a statistically significant difference depending on Ahlbäck grade, with a clear tendency towards decrease in HSS scores as the Ahlbäck grade increases (p<0.001). However, the HSS score difference between Ahlbäck grades I and V was of 9.56 points only. Comparing the status of the patients at the start (1994) and at the end (2010) of the data collection process, we observed that patients who underwent surgery in the last years were older and showed a lower Ahlbäck grade.

Conclusions: We found a relationship between Ahlbäck grading and the preoperative clinical score. The range of variability of the HSS score between the different Ahlbäck grades is small.