Outcomes of retrograde fibular strut allograft intramedullary insertion for treating humeral unicameral bone cysts.

BACKGROUND

Many unicameral bone cysts (UBCs) can be resolved or treated conservatively. Managing persistent symptomatic UBCs in the humerus is particularly challenging. An effective surgical method with low complications is significant for treatment. This study evaluated the effectiveness of inserting a fibular strut allograft retrogradely into the humerus UBC, focusing on cyst healing, concurrent pathologic fracture union, and complications.

METHODS

We conducted a retrospective analysis of medical records from 2001 to 2020 to review cases of UBCs who underwent surgery at our referral hospital. In cases where cysts persisted despite 3 steroid injections and were symptomatic or presented with a pathologic fracture, surgical intervention was considered. Of the initial 43 patients, 15 met the inclusion criteria for this study, and they were treated with retrograde insertion of a fibular strut allograft into the medullary canal, comprising 10 males and 5 females. A cyst filled with bone within 24 months is considered healed in radiographic appearance. When areas of radiolucency remain, it is called residual. Fracture union was identified by observing the bridging of at least 3 of the 4 cortical views by bone performed 3 months after surgery. The Musculoskeletal Tumor Society scoring system was used to evaluate patients' functional outcomes.

RESULTS

After a mean of 54.7 months of follow-up, 13 patients demonstrated complete cyst healing. None of the patients exhibited delayed healing. Two patients displayed cyst healing with residual, which remained stable throughout the last follow-up. All fracture cases achieved union within 3 months postoperation. The patients exhibited favorable functional outcomes, with a mean Musculoskeletal Tumor Society score of 29.6 (28-30).

CONCLUSION

Retrograde fibular strut allograft insertion into the medullary canal effectively manages symptomatic UBCs in the humeral bone, especially those in or extending to the middle or distal regions. A comparative study is recommended for further validation.