## 4 Discussion  
The incidence of enchondromas is underestimated in the general population because, in many cases, enchondromas are asymptomatic and do not require treatment. Enchondroma usually arises in the metaphysis of the tubular bones, most often affecting the bones of the hand, followed by the humerus and femur [18]. The proximal phalanges are most commonly involved, followed by the middle phalanges, the metacarpal bones and the distal phalanges. Carpal bones are affected in only 1-3% of cases of hand enchondroma [1]. Although all 15 cases included in this study had solitary enchondromas, cases of multiple enchondromas were described in 3.4% of the cases. Enchondromas are thought to be tumors that begin to form before the 54 th day of intrauterine life, which then separates into the bones of the same digit ray during the embryological development of the hand [19]. Multiple enchondromas should not be confused with [PERSON]'s disease or [PERSON]'s syndrome. [PERSON]'s disease is characterized by multiple enchondromatosis with a typically asymmetrical distribution, most commonly found in the phalanges and metacarpals of the hand [20]. [PERSON] syndrome is a rare genetic abnormality characterized by multiple enchondromatosis and vascular abnormalities, the most common being spindle cell hemangioma (SCH), a painful, aggressive and frequently disabling lesion [21]. The treatment of choice for enchondroma is tumor curettage. The autologous bone graft used to consolidate bone defects is still considered the gold standard because it is the only biological material that possesses osteoinductive, osteogenic and osteoconductive properties, fully integrated and transformed into trabecular bone [7; 22]. However, a large number of complications are reported at the bone graft donor site, especially in the iliac crest. Complications include persistent postoperative pain, damage to the lateral femoral cutaneous nerve or ilioinguinal nerve, development of a hematoma or infection [23]. Autologous bone graft requires a longer operating time, sometimes a more laborious type of anesthesia and higher costs [24; 25]. The postoperative recovery protocol depends on the strength of the remaining bone and the stability of the bone fixation mechanism. That is the reason why in some cases, fixation was performed with low-profile miniplates, which allow early motion from 5 th day postoperatively [13]. In seven of our study cases, because of the large bone defect affecting over \(\frac{1}{2}\) of the cortical circumference, it was decided to use miniplates for osteosynthesis that allowed the early active and passive motion. Analyzing the results of this study, we found that there are no differences between DASH and TAM score values in patients receiving autologous bone graft or bone substitute, but the bone graft group recorded higher postoperative pain according to the VAS score, longer operative time and significantly higher costs. An additional advantage of using injectable bone substitutes could be the immediate mechanical stability they provide [12; 26]. [PERSON] et al. reported good results following the use of calcium phosphate bone substitutes in 19 patients with enchondroma of the hand, as the material resorbed, on average, in 10 weeks and was progressively replaced by trabecular bone [27]. [PERSON] reported good functional results after using calcium phosphate in the treatment of a series of patients with enchondroma of the hand or foot [28]. A possible disadvantage of synthetic bone substitutes could be its delayed integration, insufficient defect consolidation or immune rejection, complications not encountered in this study [29]. In the cases studied by us, we observed that in Takigawa type B enchondromas, we did not need bone grafting or bone substitutes to obtain good results. This could be due to smaller dimensions of the tumor with unicritical affecting. The type A and D enchondromas from our study benefitted from curettage and filling of bone defect with autologous bone graft or injectable bone substitute with similar results.