Table 3.

Summary of the largest 11 keywords clusters.

Cluster-ID	Size	Silhouette	Mean (Year)	Label (LLR)	Included keywords (top 5)
0	95	0.6	2010	stem cells	stem cells; mesenchymal stem cell; bone tissue engineering; bone regeneration
1	73	0.669	2006	Steroid induced osteonecrosis	steroid induced osteonecrosis; systemic lupus erythematosus; avascular necrosis; apoptosis; idiopathic osteonecrosis
2	69	0.608	2012	association study	association study; avascular necrosis; susceptibility; polymorphism; case-control study
3	62	0.67	2013	apoptosis	apoptosis; inhibition; oxidative stress; osteoblast; damage
4	61	0.816	2001	blood flow	blood flow; smooth muscle cell; renal transplantation; femoral head; animal models
5	50	0.763	2008	necrosis	necrosis; therapy; osteonecrosis of the femoral head; acute lymphoblastic leukemia; femoral head
6	35	0.839	2005	peroxisome proliferator-activated receptor-gamma	peroxisome proliferator-activated receptor-gamma; messenger RNA; RNA interference; differentiation induced gene; adenovirus vector
7	30	0.844	2009	mechanism	follow up; bone mineral density; bone loss; gsk3 beta; osteoporosis
8	30	0.914	2002	follow up	mechanism; mitochondria; endothelin 1; chemistry; Raman spectroscopies
9	23	0.845	2009	broiler	broiler; knee osteoarthritis; musculoskeletal disorders; endoplasmic reticulum stress; outcome
10	20	0.837	2007	steroid-induced osteonecrosis	steroid-induced osteonecrosis; polylactic-co-glycolic acid; kidney-tonifying yang; receptor tyrosine kinase; transforming growth factor-beta 2