Survival analysis of microfracture in the osteoarthritic knee-minimum 10-year follow-up.
OBJECTIVE
The aim of this study was to evaluate the survival of microfractures in patients with degenerative osteoarthritic knees and to analyze the factors affecting length of time before total knee arthroplasty (TKA) is performed.


METHODS
This study reviewed 134 knees in 124 patients in whom microfracture was performed and for whom a minimum of 10 years of follow-up data were available. Mean follow-up was 11.2 years. The survival rate was evaluated. Failure was defined as the need for TKA. Another definition of failure was substantial symptoms in a patient whose pain score during follow-up was lower than the preoperative pain score or <60. We evaluated factors affecting survival, including size of the cartilage defect and severity of the preoperative varus deformity. The mechanical axis percentage (MA%) was defined as the percentage by which the mechanical axis bisected the total width of the tibia.


RESULTS
The survival rate was 88.8% at 5 years and 67.9% at 10 years. Fifty-one patients proceeded to TKA a mean of 6.8 years after microfracture, and 6 knees were categorized as clinical failures. Age, gender, body mass index (BMI), and presence of meniscus lesions did not affect the survival of microfractures. Survival of microfractures in patients with a cartilage defect on the medial femoral condyle <2 cm(2) in size was better than that of microfractures in patients with larger defects. Survival of microfractures in patients with MA% >25% was better than that of patients with MA% <25%.


CONCLUSIONS
Among 134 knees, 51 knees (38.1%) proceeded to TKA a mean of 6.8 years after microfracture in this study, and 6 knees were categorized as clinical failures. The survival rate was 88.8% at 5 years and decreased over time to 67.9% at 10 years. When considering microfracture, surgeons must consider factors affecting survival, such as size of the cartilage defect and severity of the preoperative varus deformity.


METHODS
Level IV, therapeutic case series.
Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, Seoul, Korea.
Dae Kyung
DK
Bae
Sang Jun
SJ
Song
Kyoung Ho
KH
Yoon
Dong Beom
DB
Heo
Tae Jin
TJ
Kim
D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D054544:Arthroplasty, Subchondral; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D013997:Time Factors