Pathological Fracture and Healing of Unicameral Bone Cysts
Pathological Fracture and Healing of Unicameral Bone Cysts
Sixty of 155 patients had pathological fracture at presentation. In univariate analysis, cyst in long bone (p <0.001), diameter more than 5 cm (p <0.001), multilocular cyst (p <0.001), ballooning of bone (p <0.001), cortical thickness less than 2 mm (p <0.001), age less than 20 years (p = 0.001), and male sex (p = 0.006) were associated with a significantly increased incidence of pathological fractures at presentation ( Table 3 ). Forty-three of 55 cases (78%) in humerus, 10 of 35 cases (29%) in femur, 2 of 10 cases (20%) in pelvis, 1 of 5 cases (20%) in tibia, 1 of 5 cases (20%) in fibula, 1 of 41 cases (2%) in calcaneus, and 2 of 4 cases in other bones had pathological fracture at presentation. In univariate analysis, UBC in humerus (43/55; 78%) had significantly more fractures than UBC at any other site (17/100; 17%) (p <0.001), whereas UBC in calcaneus (1/41; 2%) had significantly less fracture than at any other site (59/114; 52%) (p <0.001). In multivariate analysis, ballooning of bone (p = 0.011), cyst in long bone (p = 0.012), male sex (p = 0.013), cortical thickness less than 2 mm (p = 0.017), and multilocular cyst (p = 0.040) were significant risk factors for pathological fractures at presentation ( Table 3 ). One patient with femoral neck UBC developed avascular necrosis after a displaced pathological fracture, and was treated by curved intertrochanteric varus osteotomy.
Healing of UBC was less observed in the patients subjected to watchful waiting (23/77; 30%) than in operated patients (53/64; 83%) at the last follow up (p <0.001). In observed patients, fracture at presentation (p = 0.004), multilocular cyst (p = 0.010), ballooning of bone (p = 0.015), and history of biopsy (p = 0.019) were significantly associated with good healing of UBC at the last follow up in univariate analysis ( Table 4 ). Half of the patients (14/28 patients) with fracture at presentation and 57% of patients (8/14 patients) after biopsy showed healing with observation alone at the last follow-up. Five of these 28 patients were biopsied after fractures, with 4 of them showing healing at the last follow up. Multivariate analysis showed that fracture at presentation (p = 0.004) and history of biopsy (p = 0.013) were independent factors for good healing in observed patients ( Table 4 ). Healing of UBC was observed in 26 of 35 patients (74%) after operation with cannulated screw, 12 of 12 patients (100%) with curettage and graft, 3 of 3 patients (100%) with curettage, 2 of 3 patients (67%) with drilling, and 10 of 11 patients (91%) with other methods at the last follow up. There was a statistical significant difference between cannulated screw and other treatment methods for healing of UBC (p = 0.046) ( Table 5 ). UBC had healed in 40 of 50 patients (80%) after single surgery and in 13 of 14 patients (93%) after multiple surgeries (p = 0.244). In multivariate analysis for healing of UBC in humerus, latent phase UBC (p = 0.011) and treatment with surgery (p = 0.011) were significantly associated with good healing of UBC ( Table 6 ). In patients with UBC in humerus, 3 of 10 patients with active phase and 12 of 21 patients with latent phase were healed at last follow up with observation (p = 0.152), and 6 of 11 patients with active phase and 12 of 12 patients with latent phase were healed after surgery (p = 0.014).
Results
Sixty of 155 patients had pathological fracture at presentation. In univariate analysis, cyst in long bone (p <0.001), diameter more than 5 cm (p <0.001), multilocular cyst (p <0.001), ballooning of bone (p <0.001), cortical thickness less than 2 mm (p <0.001), age less than 20 years (p = 0.001), and male sex (p = 0.006) were associated with a significantly increased incidence of pathological fractures at presentation ( Table 3 ). Forty-three of 55 cases (78%) in humerus, 10 of 35 cases (29%) in femur, 2 of 10 cases (20%) in pelvis, 1 of 5 cases (20%) in tibia, 1 of 5 cases (20%) in fibula, 1 of 41 cases (2%) in calcaneus, and 2 of 4 cases in other bones had pathological fracture at presentation. In univariate analysis, UBC in humerus (43/55; 78%) had significantly more fractures than UBC at any other site (17/100; 17%) (p <0.001), whereas UBC in calcaneus (1/41; 2%) had significantly less fracture than at any other site (59/114; 52%) (p <0.001). In multivariate analysis, ballooning of bone (p = 0.011), cyst in long bone (p = 0.012), male sex (p = 0.013), cortical thickness less than 2 mm (p = 0.017), and multilocular cyst (p = 0.040) were significant risk factors for pathological fractures at presentation ( Table 3 ). One patient with femoral neck UBC developed avascular necrosis after a displaced pathological fracture, and was treated by curved intertrochanteric varus osteotomy.
Healing of UBC was less observed in the patients subjected to watchful waiting (23/77; 30%) than in operated patients (53/64; 83%) at the last follow up (p <0.001). In observed patients, fracture at presentation (p = 0.004), multilocular cyst (p = 0.010), ballooning of bone (p = 0.015), and history of biopsy (p = 0.019) were significantly associated with good healing of UBC at the last follow up in univariate analysis ( Table 4 ). Half of the patients (14/28 patients) with fracture at presentation and 57% of patients (8/14 patients) after biopsy showed healing with observation alone at the last follow-up. Five of these 28 patients were biopsied after fractures, with 4 of them showing healing at the last follow up. Multivariate analysis showed that fracture at presentation (p = 0.004) and history of biopsy (p = 0.013) were independent factors for good healing in observed patients ( Table 4 ). Healing of UBC was observed in 26 of 35 patients (74%) after operation with cannulated screw, 12 of 12 patients (100%) with curettage and graft, 3 of 3 patients (100%) with curettage, 2 of 3 patients (67%) with drilling, and 10 of 11 patients (91%) with other methods at the last follow up. There was a statistical significant difference between cannulated screw and other treatment methods for healing of UBC (p = 0.046) ( Table 5 ). UBC had healed in 40 of 50 patients (80%) after single surgery and in 13 of 14 patients (93%) after multiple surgeries (p = 0.244). In multivariate analysis for healing of UBC in humerus, latent phase UBC (p = 0.011) and treatment with surgery (p = 0.011) were significantly associated with good healing of UBC ( Table 6 ). In patients with UBC in humerus, 3 of 10 patients with active phase and 12 of 21 patients with latent phase were healed at last follow up with observation (p = 0.152), and 6 of 11 patients with active phase and 12 of 12 patients with latent phase were healed after surgery (p = 0.014).
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