Cumulative operative burden is associated with poorer function after segmental bone transport for lower-extremity...

Segmental bone transport offers biological reconstruction and limb preservation for extensive lower-extremity long-bone defects, but treatment often involves prolonged external fixation, planned stages, and unplanned reoperations. We evaluated reconstructive and functional outcomes and examined the association between cumulative operative burden and final patient-reported function.

This retrospective single-centre study screened 44 patients treated between January 2012 and March 2023. Thirty-six patients, representing 37 reconstructed long bones, had complete final outcome ascertainment. ASAMI bone outcome was reported per reconstructed bone (n = 37); limb preservation and all functional and multivariable analyses were patient-level (n = 36). Outcomes included limb preservation, ASAMI bone and functional results, the Lower Extremity Functional Scale (LEFS), the Karlström-Olerud score, healing indices, treatment-related events, and the cumulative number of formal operations. Multivariable linear regression, bootstrap resampling, sensitivity analyses, and exploratory receiver operating characteristic analysis were performed.

Mean defect length was 10.32 ± 4.67 cm and the mean defect-to-bone length ratio was 26.3% ± 12.4%. Patients underwent a mean of 8.08 ± 4.21 operations (median, 7; range, 3-18). Mean follow-up after external-fixator removal was 5.69 ± 3.62 years. Limb preservation was achieved in 35 of 36 patients (97.2%). Combined excellent/good ASAMI bone and functional outcomes were 75.7% and 77.8%, respectively. Pin-site infection occurred in 17 patients and accounted for 32 fixation-element events; premature consolidation occurred in 11 patients and accounted for 18 episodes. After adjustment for age, defect length, and consolidation index, each additional operation was associated with a 1.94-point lower LEFS (β=-1.94, 95% CI - 3.12 to - 0.76; p=.002). Excluding the patient who underwent below-knee amputation and had an LEFS of 0 did not materially alter this association (n = 35; β=-1.86, 95% CI - 2.85 to - 0.86; p<.001). Older age was also independently associated with lower LEFS (β=-0.46 points/year; p=.006). Follow-up duration was not associated with LEFS and did not alter the principal association. Exploratory ROC analysis for LEFS < 40 yielded an AUC of 0.846 (bootstrap 95% CI 0.689-0.968); the internally derived ≥ 11-operation threshold was regarded as hypothesis-generating.

Segmental bone transport achieved high limb preservation and largely favourable ASAMI outcomes despite a substantial treatment burden. A greater cumulative number of operations was associated with lower final LEFS. Operation count should be interpreted as a summary marker of case complexity and the treatment course, not as evidence that repeated surgery alone caused poorer function.