Donor site morbidity of vascularized bone grafts from the medial femoral condyle for osseous revascularization

Fracture risk assessment of vascularized medial femoral condylar bone graft: A finite element analysis

BACKGROUND

Vascularized medial femoral condyle (MFC) bone graft is useful for pseudarthrosis and osteonecrosis, but has the risk of fracture as a complication. This study aimed to create multiple three-dimensional (3D) finite element (FE) femur models to biomechanically evaluate the fracture risk in the donor site of a vascularized MFC bone graft.

METHODS

Computer tomography scans of the femurs of nine patients (four males and five females) with no left femur disease were enrolled in the study. A 3D FE model of the left femur was generated based on the CT images taken from the patients. The descending genicular artery (DGA), the main nutrient vessel in vascularized MFC bone grafts, divides into the proximal transversal branch (TB) and the distal longitudinal branch (LB) before entering the periosteum. Thirty-six different bone defect models with different sizes and locations of the harvested bone were created.

RESULTS

The highest stress was observed in the proximal medial and metaphyseal portions under axial and external rotation, respectively. In the bone defect model, the stress was most elevated in the extracted region's anterior or posterior superior part. Stress increased depending on proximal location and harvested bone size.

CONCLUSION

Increasing the size of the bone graft proximally raises the stress at the site of bone extraction. For bone grafting to non-load-bearing areas, bone grafting distally using LB can reduce fracture risk. If TB necessitates a larger proximal bone extraction, it is advisable to avoid postoperative rotational loads.

Patient-Reported Lower Extremity Outcomes Following Fibula or Medial Femoral Condyle Free Flaps for Upper Extremity Defects

BACKGROUND

Free fibula flap (FFF) and medial femoral condyle (MFC) flap are commonly used for upper extremity osseous reconstruction, yet donor-site morbidity has never been systematically compared.

METHODS

Patients who underwent an FFF or MFC for upper extremity extra-carpal osseous reconstruction at 3 academic hand centers were retrospectively identified. Only patients who underwent reconstruction for a defect in which either flap type is routinely used or has been described in the literature were deemed eligible. Patients who agreed to participate were asked to complete the Lower Extremity Functional Scale (LEFS) and Lower Limb Core Scale (LLCS). The reported population norm median score of LEFS is 77 points. The LLCS population norm mean score is 90.52 points.

RESULTS

Twenty-one patients (10 MFC, 11 FFF) were enrolled. The median LEFS score for patients after MFC was 76 (interquartile range [IQR], 49-80) points and 75 (IQR, 56-79) points after FFF. The median LLCS score for patients after MFC was 96.4 (IQR, 87.9-100) points and 100 (IQR, 91-100) points after FFF. Median LEFS scores were slightly below the population norm, whereas median LLCS scores were above the norm for both FFF and MFC. All patients stated they would have the surgery again and that any dysfunction or pain in the leg was justified by the benefit in the arm.

CONCLUSIONS

When considering whether to use an MFC or FFF for upper extremity reconstruction, both flap types appear to result in modest and comparable donor-site morbidity.

[Medial femoral condyle free flap for reconstruction of carpometacarpal bone defect after giant cell tumour of tendon synovial sheath resection]

We report the case of a 23-year-old patient treated for a large giant cell tumour of the synovial sheaths of the ulnar edge of the hand and wrist invading the triquetrum, the hamatum, the ulnar part of the capitate as well as the bases of the 3rd, 4th and 5th metacarpals and the floor of the Guyon's canal and the carpal tunnel. A monobloc resection was performed in a healthy margin ; the loss of bone substance was 7×3.5cm. We performed a bone reconstruction using a cortico-cancellous medial femoral condyle free flap of 8×4cm. Postoperative follow-up was uneventful and bone consolidation was achieved at 2,5 months postoperatively. The cortico-cancellous medial femoral condyle free flap is an interesting option for treating small and medium size bone loss in the hand and wrist. Its use in its pure bone form or in its chimeric form with muscle, cartilage or skin opens up a wide range of choices for the reconstructive surgeon.