J Reconstr Microsurg 2015; 31(05): 364-368
DOI: 10.1055/s-0035-1546420
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Torsional Stability of the Femur after Harvest of the Medial Femoral Condyle Corticocancellous Flap

Matthew R. Endara
1   The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, Maryland
,
Benjamin J. Brown
1   The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, Maryland
,
John Shuck
1   The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, Maryland
,
Malick Bachabi
1   The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, Maryland
,
Brent G. Parks
1   The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, Maryland
,
James P. Higgins
1   The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, Maryland
› Institutsangaben
Weitere Informationen

Publikationsverlauf

15. September 2014

20. Dezember 2014

Publikationsdatum:
13. März 2015 (online)

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Abstract

Background Increasingly large segments of medial femoral condyle (MFC) corticocancellous flaps have been harvested for transfer. Biomechanical evaluations demonstrated no osseous stability impairment under axial loading regardless of flap size harvested. The purpose of this study was to determine the donor site's response to torsional forces.

Methods Dual-energy X-ray absorptiometry (DEXA) scanning was performed on 16 pairs of cadaver legs followed by removal of all soft tissues, except knee capsule and ligaments. Specimens were randomly assigned to three groups with bone harvest defects measuring 3, 5, or 7 cm in length and a control group with no osseous resection. Torsional load was applied until fracture or ligamentous failure.

Results Bone failure rates were 12.5, 12.5, 28.6, and 55.6% for control, 3, 5, and 7 cm groups, respectively. Bone failure rate increased with increasing harvest size; the 7 cm group demonstrated a significantly higher rate compared with the other groups combined (55.6 vs. 17.4%; p = 0.03). Failure torque was 45.5, 29.35, 27.4, and 30.83 Nm for the control, 3, 5, and 7 cm groups, respectively (p = 0.11). Harvest of any size segment resulted in a significant decrease in failure torque (p = 0.01). Bone mineral density (BMD) and Z-scores were no different among groups (p = 0.79 and 0.59, respectively). A direct relationship was identified between force required for failure and BMD (p = 0.02) and Z-scores (p = 0.05) but not for failure location and BMD (p = 0.09) or Z-scores (p = 0.94).

Conclusion MFC corticocancellous flap harvest of any size decreases donor site failure torque. Flap harvests > 7 cm demonstrate a higher frequency of iatrogenic fracture and therefore warrant caution with torsional loading of the knee postoperatively. Routine preoperative DEXA scans may not be warranted.