Original article
The Association Between Posterior-Inferior Tibial Slope and Anterior Cruciate Ligament Insufficiency

Presented at the Annual Meeting of the Arthroscopy Association of North America, Orlando, Florida, April 22–25, 2004.
https://doi.org/10.1016/j.arthro.2006.04.098Get rights and content

Purpose: The purpose of this study was to determine whether an increased posterior-inferior tibial slope (PITS) is associated with anterior cruciate ligament (ACL) rupture and whether an increased PITS results in worse pivot-shift grades in ACL-insufficient patients. This study also examined the difference in PITS between men and women. Methods: We radiographically measured the PITS angle of 100 ACL-insufficient patients and 100 patients with patellofemoral pain (control patients). The mean PITS of male and female cases and control patients was compared to determine whether sex had an influence on the mean PITS angle. The measured PITS was compared with the pivot-shift grade with patients under anesthesia in a subgroup of 87 isolated ACL-insufficient patients with no other knee injury. Results: Female ACL-insufficient patients had a significantly greater PITS (12.0° ± 3.5°) than their negative controls (8.6° ± 2.7°) (P < .001). Male ACL-insufficient patients had a significantly greater PITS (10.8° ± 3.9°) than their negative controls (8.4° ± 3.4°) (P < .001). In the isolated ACL-insufficient patients, the high-grade pivot-shift patient group had a statistically significantly greater PITS (11.10° ± 3.85°) than the low-grade pivot-shift patient group (9.19° ± 3.58°) (P = .03). Conclusions: An increased PITS is associated with ACL rupture. A higher pivot-shift grade is associated with an increased degree of PITS. Female patients did not have a significantly greater mean PITS angle than male patients. Level of Evidence: Level III, prognostic case-control study.

Section snippets

Methods

Our patient group consisted of 100 patients (66 male and 34 female patients) who were diagnosed with ACL insufficiency and examined in our practices between 1998 and 2003. The patients’ histories, physical examinations, and magnetic resonance imaging findings were used to confirm the diagnosis and ensure that no other ligamentous compromise or capsular injury occurred and that the ACL injury was via a noncontact mechanism. The 4 senior authors (M.F.S., G.R.B., M.I.F., and J.R.B.) conducted all

Results

The negative control group of 100 patients with patellofemoral pain had a mean PITS of 8.5° ± 3.0°, with a mean PITS of 8.6° ± 2.7° in the female group (n = 51) and 8.4° ± 3.4° in the male group (n = 49). The case group of 100 ACL-insufficient patients had a mean PITS of 11.2° ± 3.8°, with a mean PITS of 12.0° ± 3.5° in the female group (n = 34) and 10.8° ± 3.9° in the male group (n = 66). ANOVA determined that the mean PITS of the ACL-insufficient case group was significantly greater than that

Discussion

Prior studies have concluded that shearing forces exist that act across the tibiofemoral joint during stance. Shoemaker and Markolf17 proved in a cadaveric model that anterior tibial translation could occur with axial loading alone when the ACL and the medial meniscus have been transected. Dejour and Bonnin2 conducted a prospective case-control study that showed that there was 6 mm of increased anterior tibial translation for every 10° of increased PITS when patients were placed in the lateral,

Conclusions

The results of our study suggest that an increased degree of PITS is indeed associated with noncontact ACL rupture in both male and female patients. We demonstrated no significant difference in the mean PITS between men and women in our ACL-insufficient case group. Increased PITS is associated with increased pivot-shift grades on examination with patients under anesthesia.

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    The authors report no conflict of interest.

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