Journal List > J Korean Bone Joint Tumor Soc > v.17(2) > 1051993

Choo, Lee, and Oh: Pathologic Fracture of Unicameral Bone Cyst

Abstract

Purpose

The purpose of this study is to observe unicameral bone cyst (UBC) outcome after the fracture has healed and if there is any identifiable prognostic factors.

Materials and Methods

13 UBC patients with pathologic fracture from 2001 to 2010 were reviewed. The mean follow up were 26 months (3–90 months). There were 11 male and 2 female patients and the mean age of the patients were 10.2 years old (6–16 years). 9 involved proximal humerusand 2 involved humerus shaft and 1 involved proximal femur and 1 involved proximal tibia. The treatment of UBC fracture was conservative cast application to heal the fracture initially, and 1 patient was treated with primary auto bone graft and open reduction with internal fixation. 5 patients were treated with steroid injection during follow up period and 2 patients with auto bone graft. We analyzed the change of UBC during pathologic fracture healing period and prognostic factor about age, the size of UBC, the involvement of physis.

Results

The mean duration of the fracture healing was 8.2 months. Complete healing were occurred at 4 patients (31%). No stati-scal difference was checked with age about UBC healing (p=0.42). But, more larger size about UBC and more closer to physis, the healing was difficult (p=0.05, p=0.03).

Conclusion

While pathologic fracture of UBC was possibly healed, active treatment should be applied especially those cysts that involvescloser area of the physis or large size.

References

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Figure 1.
Completely healed case. (A) It was initial x-ray. (B) After treatment, the cystic lesion was completely resolved after duration 46 months.
jkbjts-17-58f1.tif
Figure 2.
Partially healed case. (A) It was initial x-ray (B) After treatment, the cystic lesion was partially resolved after duration 4 months.
jkbjts-17-58f2.tif
Figure 3.
Recurrence case. (A) It was initial x-ray. (B) After treatment, the cystic lesion was partially resolved and fracture site was healed after duration 8 months. (C) But, after follow up 30 months, cystic lesion was recurred with another pathologic fracture.
jkbjts-17-58f3.tif
Figure 4.
The measurement of cyst size. The maxium length was measured from medial cortex of cyst to lateral cortex (A). The maxium height was measured from upper margin of cyst to lower margin of cyst (B). Size=1/4×3.14×A×B.
jkbjts-17-58f4.tif
Figure 5.
Involvement of physis. (A) Physis was not contacted (Grade I). (B) Physis was partially contacted (Grade II). (C) Physis was all contacted (Grade III).
jkbjts-17-58f5.tif
Table 1.
Demographic Data
  Sex Age (yrs) SBC site Size (cm2) Grade of physis involvement* Follow up duration (months) Result
1 M 11 Humerus shaft 26.3 III 24 Recurred
2 M 7 Proximal humerus 14.4 I 46 Complete
3 M 9 Proximal humerus 9.6 II 3 Partial
4 F 6 Proximal femur 9.2 III 30 Recurred
5 M 9 Proximal tibia 12.2 II 18 Partial
6 M 14 Proximal humerus 12.2 II 4 Partial
7 F 10 Proximal humerus 11.5 II 90 Complete
8 M 10 Proximal humerus 12.9 II 55 Partial
9 M 14 Proximal humerus 23.2 III 12 Recurred
10 M 6 Proximal humerus 3.6 I 20 Recurred
11 M 9 Proximal humerus 5.1 I 8 Complete
12 M 12 Proximal humerus 3.4 II 6 Partial
13 M 16 Humerus shaft 4.7 I 23 Complete
Average   10.2   11.4   26.1  

* Grade I, physis was not contacted; Grade II, physis was partially contacted; Grade III, physis was all contacted.

Table 2.
Clinical Outcome according to Age of Onset
Age (yrs) No. Pt Complete Improving Recur
<10 6 2 2 2
≥10 7 2 3 2
Table 3.
Clinical Outcome according to Size of the Cyst
Size (cm2) No. Pt Complete Improving Recur
<7 4 2 1 1
7–15 7 2 4 1
>15 2 0 0 2
Table 4.
Clinical Outcome according to Involvement of Physis
Grade No. Pt Complete Improving Recur
I 4 3 0 1
II 6 1 5 0
III 3 0 0 3
Table 5.
Clinical Outcome according to Treatment Method
Treatment No. Pt Complete Improving Recur
Conservative 7 2 3 2
Steroid injection 5 1 2 2
Bone graft 2 2 0 0
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