The association between posterior-inferior tibial slope and anterior cruciate ligament insufficiency.

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 degrees +/- 3.5 degrees ) than their negative controls (8.6 degrees +/- 2.7 degrees ) (P < .001). Male ACL-insufficient patients had a significantly greater PITS (10.8 degrees +/- 3.9 degrees ) than their negative controls (8.4 degrees +/- 3.4 degrees ) (P < .001). In the isolated ACL-insufficient patients, the high-grade pivot-shift patient group had a statistically significantly greater PITS (11.10 degrees +/- 3.85 degrees ) than the low-grade pivot-shift patient group (9.19 degrees +/- 3.58 degrees ) (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.

Shoulder adaptive changes in youth baseball players.

Shoulder adaptive changes in response to overhand throwing have been observed in adults, but the age of onset and progression of these adaptive changes have not been established. Two-hundred ninety-eight youth baseball players (8- to 28-year-olds) were studied to determine whether shoulder range of motion and laxity differences between the dominant and non-dominant shoulders exist between different age groups. The subjects were separated into 3 different age groups of 100 8- to 12-year-olds (Group 1), 100 13- to-14 year-olds (Group 2), and 98 15- to 28-year-olds (Group 3). For dominant shoulder external rotation with the humerus in abduction, all groups were significantly different from each other, with Group 2 having the greatest range and Group 1 having the smallest range (P < .05). When comparing dominant shoulder internal rotation in abduction among different groups, Group 3 and Group 2 motion was significantly less than that for Group 1 (P < .05.) When comparing dominant to non-dominant shoulder motion within each group, a significant increase in dominant shoulder external rotation in abduction was found in all 3 age groups (P < .05). Comparison of the differences in external rotation in abduction between the dominant and non-dominant shoulders demonstrated an increase with increasing age, Group 1 (1.5 +/- 6.8 degrees), Group 2 (9.6 +/- 15.3 degrees), and Group 3 (15.0 +/- 11.2 degrees; P < .05). Comparison of differences in internal rotation in abduction between dominant and non-dominant shoulders demonstrated a decrease with increasing age, Group 1 (4.6 +/- 8.2 degrees), Group 2 (8.4 +/- 14.5 degrees), and Group 3 (15.5 +/- 11.7 degrees; P < .05). For shoulder laxity, Groups 2 and 3 had significantly more inferior shoulder laxity when compared to Group 1. In summary, our results indicate that shoulder range of motion and laxity of youth baseball players are caused by adaptive changes that manifest during adolescence.