Background: The purpose of this study is to describe anterolateral rotatory instability (ALRI) as a possible etiology of primary osteoarthritis (OA) of the elbow. Methods: We examined 76 fresh frozen cadaveric elbows (male:female, 56:20; mean age, 81 years) for patterns of cartilage erosion that could be due to ALRI. These included erosions on the lateral trochlear ridge (LTR) lesion, crescent rim of the radial head (RC) lesion or the ventral capitellum (VC) lesion. The extent and location of the lesions were mapped by image processing of photographs of the humeral and radial articular surfaces, and the degeneration of the articular surface was graded. Results: Ten of 76 specimens (13%) had one or more lesions consistent with ALRI. LTR lesions were most common and were seen in 10 of 10 specimens (100%), typically involving the distal 30% of the LTR. RC lesions were seen in 9 of 10 and were located on anteromedial crescent of the radial head ranging from 6 to 10 o’clock. VC lesions were seen in 8 of 10 specimens directed anteroinferiorly about 60° to the long axis of the humerus. Conclusions ALRI is a possible mechanism initiating primary OA of the elbow. It has a characteristic pattern of triple lesions involving the LTR, the RC, and the VC.Level of evidence: IV.

Background: The purpose of this study is to describe anterolateral rotatory instability (ALRI) as a possible etiology of primary osteoarthritis (OA) of the elbow. Methods: We examined 76 fresh frozen cadaveric elbows (male:female, 56:20; mean age, 81 years) for patterns of cartilage erosion that could be due to ALRI. These included erosions on the lateral trochlear ridge (LTR) lesion, crescent rim of the radial head (RC) lesion or the ventral capitellum (VC) lesion. The extent and location of the lesions were mapped by image processing of photographs of the humeral and radial articular surfaces, and the degeneration of the articular surface was graded. Results: Ten of 76 specimens (13%) had one or more lesions consistent with ALRI. LTR lesions were most common and were seen in 10 of 10 specimens (100%), typically involving the distal 30% of the LTR. RC lesions were seen in 9 of 10 and were located on anteromedial crescent of the radial head ranging from 6 to 10 o’clock. VC lesions were seen in 8 of 10 specimens directed anteroinferiorly about 60° to the long axis of the humerus. Conclusions ALRI is a possible mechanism initiating primary OA of the elbow. It has a characteristic pattern of triple lesions involving the LTR, the RC, and the VC.Level of evidence: IV.

Background: The purpose of this study is to describe anterolateral rotatory instability (ALRI) as a possible etiology of primary osteoarthritis (OA) of the elbow. Methods: We examined 76 fresh frozen cadaveric elbows (male:female, 56:20; mean age, 81 years) for patterns of cartilage erosion that could be due to ALRI. These included erosions on the lateral trochlear ridge (LTR) lesion, crescent rim of the radial head (RC) lesion or the ventral capitellum (VC) lesion. The extent and location of the lesions were mapped by image processing of photographs of the humeral and radial articular surfaces, and the degeneration of the articular surface was graded. Results: Ten of 76 specimens (13%) had one or more lesions consistent with ALRI. LTR lesions were most common and were seen in 10 of 10 specimens (100%), typically involving the distal 30% of the LTR. RC lesions were seen in 9 of 10 and were located on anteromedial crescent of the radial head ranging from 6 to 10 o’clock. VC lesions were seen in 8 of 10 specimens directed anteroinferiorly about 60° to the long axis of the humerus. Conclusions ALRI is a possible mechanism initiating primary OA of the elbow. It has a characteristic pattern of triple lesions involving the LTR, the RC, and the VC.Level of evidence: IV.

Background: The purpose of this study is to describe anterolateral rotatory instability (ALRI) as a possible etiology of primary osteoarthritis (OA) of the elbow. Methods: We examined 76 fresh frozen cadaveric elbows (male:female, 56:20; mean age, 81 years) for patterns of cartilage erosion that could be due to ALRI. These included erosions on the lateral trochlear ridge (LTR) lesion, crescent rim of the radial head (RC) lesion or the ventral capitellum (VC) lesion. The extent and location of the lesions were mapped by image processing of photographs of the humeral and radial articular surfaces, and the degeneration of the articular surface was graded. Results: Ten of 76 specimens (13%) had one or more lesions consistent with ALRI. LTR lesions were most common and were seen in 10 of 10 specimens (100%), typically involving the distal 30% of the LTR. RC lesions were seen in 9 of 10 and were located on anteromedial crescent of the radial head ranging from 6 to 10 o’clock. VC lesions were seen in 8 of 10 specimens directed anteroinferiorly about 60° to the long axis of the humerus. Conclusions ALRI is a possible mechanism initiating primary OA of the elbow. It has a characteristic pattern of triple lesions involving the LTR, the RC, and the VC.Level of evidence: IV.