Nonanatomic Horn Position Increases Risk of Early Graft Failures After Lateral Meniscal Allograft Transplantation

The cause of early graft failure within 1 year of meniscal allograft transplantation (MAT) remains unclear. The association of early failure with a nonanatomic horn position of the allograft after lateral MAT with the keyhole technique has never been evaluated.

A nonanatomic horn position of an allograft would be a significant risk factor for a premature graft tear as compared with an anatomically positioned allograft.

Cohort study; Level of evidence, 3.

From October 2007 to October 2016, 208 patients (214 knees) with primary isolated lateral MAT in a single center were enrolled. A >5-mm or 10% discrepancy between pre- and postoperative horn position was defined as "nonanatomic," and the early failure rate was compared. Among 214 cases of lateral MAT, 54 were nonanatomically positioned, and 160 were anatomically positioned. The early failures (within 1 year after MAT) were defined as (1) grade 3 signal intensities (tears) over one-third of the allograft on magnetic resonance image or (2) removal of more than one-third of the allograft because of tears.

Among the early failure cases, 6 were in the nonanatomic group and 5 in the anatomic group. The failure rate was 11.1% (6 of 54) in the nonanatomic group and 3.1% (5 of 160) in the anatomic group, with a 5.1% (11 of 214) overall early failure rate. The nonanatomic horn position group had an increased risk of early graft failure as compared with the anatomically positioned group (odds ratio = 3.88; 95% CI, 1.13-13.26). Anteriorized and lateralized horn position was identified in the nonanatomic group as compared with the anatomic group. Differences in patient age, sex, body mass index, involved knee, cartilage status, alignment of lower extremity, and joint space width were not statistically significant between the groups.

Horn position discrepancy was associated with an increased risk of early graft failures. Meticulous insertion of a bone bridge is needed to ensure anatomically correct horn positioning to avoid early graft failure in lateral MAT with the keyhole technique.