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.

Background: Posterolateral rotatory instability (PLRI) is a common mechanism of recurrent elbow instability. While the essential lesion is a deficiency in the lateral ulnar collateral ligament (LUCL), there are often associated concomitant bony lesions, such as an Osborne-Cotterill lesions (posterior capitellar fractures) and marginal radial head fractures, that compromise stability. Currently, there is no standard treatment for posterior capitellar deficiency associated with recurrent PLRI. Methods: We conducted a retrospective review of five patients with recurrent PLRI of the elbow associated with a posterior capitellar impaction fracture engaging with the radial head during normal range of motion. The patients were treated surgically with LUCL reconstruction or repair and off-label reconstruction of the capitellar joint surface using a small metal prosthesis designed for metatarsal head resurfacing (HemiCAP toe classic). Results: Five patients (three adolescent males, two adult females) were treated between 2007 and 2018. At a median follow-up of 5 years, all patients had complete relief of their symptomatic instability. No patients had pain at rest, but two patients had mild pain (visual analog scale 1–3) during physical activity. Three patients rated their elbow as normal, one as almost normal, and one as greatly improved. On short-term radiographic follow-up there were no signs of implant loosening. None of the patients needed reoperation. Conclusions Recurrent PLRI of the elbow associated with an engaging posterior capitellar lesion can be treated successfully by LUCL reconstruction and repair and filling of the capitellar defect with a metal prosthesis. This treatment option has excellent clinical results in the short-medium term.Level of evidence: IV.