Increased Posterior Tibial Slope Correlates With Greater Odds of Reoperation and Failure After Meniscal Allograft Transplantation.

BACKGROUND

Higher posterior tibial slope (PTS) is associated with a greater rate of failure in meniscus root tears and anterior cruciate ligament reconstruction.

PURPOSE: To analyze the correlation of PTS with patient-reported outcomes (PROs) and rates of reoperation and failure in meniscal allograft transplantation (MAT).

STUDY

DESIGN

Cohort study (prognostic); Level of evidence, 3.

METHODS

A retrospective review of a prospectively maintained database was performed to assess outcomes after MAT in patients between 2003 and 2021 with minimum 2-year follow-up. PTS was measured on lateral knee radiographs, with medial PTS (MPTS) and lateral PTS (LPTS) measured on magnetic resonance imaging (MRI). PROs were collected preoperatively and at minimum 2-year follow-up. MAT failure was defined as revision MAT or conversion to arthroplasty. Multivariable regression was used to correlate PTS with PROs and rates of reoperation and failure. Failure and reoperation were further analyzed separately in medial and lateral MATs for MPTS and LPTS.

RESULTS

In total, 175 knees (174 patients) met inclusion criteria with a mean ± SD age of 27.4 ± 9.1 years and follow-up of 8.3 ± 3.8 years. By radiograph, the mean PTS was 8.8°± 3.2°; by MRI, the mean MPTS and LPTS were 5.1°± 2.7° and 5.8°± 3.3°, respectively. MRI measurements significantly underestimated radiographic measurements by 3.3°± 2.9°. Correlation coefficients demonstrated weak to moderate correlations between radiograph and MRI measurements, while intraclass correlation coefficients ranged from 0.920 to 0.931 for intrarater reliability and 0.855 to 0.952 for interrater reliability within MRI or radiographic measurements. There was no association between PTS and postoperative PROs. Sixty cases (34.3%) resulted in reoperation at a mean 2.5 ± 2.8 years, and 8 cases (4.6%) experienced failure at 8.9 ± 2.9 years. Higher radiographic PTS and MPTS were associated with greater odds of reoperation (odds ratio [OR], 1.126 [P = .024]; OR, 1.166 [P = .013]) and failure (OR, 1.654 [P = .001]; OR, 1.712 [P < .001]). Higher LPTS was associated with greater odds of failure (OR, 1.279; P = .018). In medial MAT, MPTS was associated with higher odds of reoperation and failure.

CONCLUSION

Increased PTS, as measured by radiographs and MRI, is correlated with greater risk of reoperation and failure after MAT, with increased MPTS on MRI significantly associated with medial MAT reoperation and failure. There is good to excellent inter- and intrarater reliability for radiographic and MRI PTS measurements, although MRI underestimates radiographic PTS on average 3.3°.