Clinical outcome

The main outcome measure used in this study was defined as the revision rate. The overall probability of requiring a revision and the probabilities of having a revision arthroscopy, an osteotomy, or a total knee replacement at 4 years following the initial knee chondroplasty procedure were taken from the RCT [25] after accounting for 2 patients lost to follow-up (one from each treatment group [1 patient from the Mechanical shaver group had died and 1 patient from the Coblation group was lost to follow-up] and applied to the model. The RCT reported a lower revision rate with Coblation, 14% compared with 48% with MSD. Of the 18 patients who had revisions for persistent knee problems, there were 8 total knee replacements, 4 osteotomies, and 2 arthroscopies in the MSD group; and 1 total knee replacement, 2 osteotomies, and 1 arthroscopy in the Coblation group [25]. In addition, patients treated with Coblation reported a significantly higher KOOS at the end of the follow-up period (71.8 points vs. 53.2 points, respectively; P < 0.001), see Table ​Table1.1. At the 10 year follow-up, an additional 7 patients required revision surgery, there were 3 unicondylar/total knee replacements and 1 osteotomy procedure required in the MSD group while 3 revision procedures were required in the Coblation group [26]. Although results of the RCT did not state the specific revision procedures required in the Coblation group, a worst case scenario was assumed and total knee replacement procedures were assumed for all 3 revision procedures. Furthermore, with comparable baseline KOOS scores, the Coblation group had a significantly higher KOOS score compared to the MSD group (50.8 points vs. 33.1 points, respectively; p < 0.001).

Revisions and clinical outcomes at 4 year follow-up

KOOS Knee Injury and Osteoarthritis Outcome Score; MSD mechanical shaver debridement; TKA total knee replacement

^aOutcomes are from the randomized controlled trial [25]

^bStatistically significant difference in post-operative KOOS score between Coblation and MSD (p value < 0.001)