Martin, R. Kyle

Abstract The application of artificial intelligence (AI) and machine learning to the field of orthopaedic surgery is rapidly increasing. While this represents an important step in the advancement of our specialty, the concept of AI is rich with statistical jargon and techniques unfamiliar to many clinicians. This knowledge gap may limit the impact and potential of these novel techniques. We aim to narrow this gap in a way that is accessible for all orthopaedic surgeons. With this manuscript, we introduce the concept of AI and machine learning and give examples of how it can impact clinical practice and patient care. Level of evidence VI.

Background: Increased lateral posterior tibial slope (LPTS) is associated with increased rates of anterior cruciate ligament (ACL) injury and failure of ACL reconstruction. It is unknown if ACL deficiency influences the developing proximal tibial physis and slope in skeletally immature patients through anterior tibial subluxation and abnormal force transmission. Purpose: To assess the natural history of LPTS in skeletally immature patients with an ACL-injured knee. Study Design: Case series; Level of evidence, 4. Methods: A total of 38 participants from a previous study on nonoperative management of ACL injury in skeletally immature patients were included. During the initial study, bilateral knee magnetic resonance imaging (MRI) was performed within 1 year of enrollment and again at final follow-up. All patients were younger than 13 years at the time of enrollment, and final follow-up occurred a mean 10 years after the injury. MRI scans were retrospectively reviewed by 2 reviewers to determine bilateral LPTS for each patient and each time point. Linear mixed models were used to assess LPTS differences between knees, change over time, and association with operational status. Subgroup analyses were performed for patients who remained nonoperated throughout the study. Results: A total of 22 patients had ACL reconstruction before final follow-up and 16 remained nonoperated. In the entire study population, the mean LPTS was higher in the injured knee than in the contralateral knee at final follow-up by 2.0° ( P < .001; 95% CI, 1.3°–2.6°). The mean LPTS increased significantly in the injured knee by 0.9° ( P = .042; 95% CI, 0.03°–1.7°), while the mean LPTS decreased in the contralateral knee by 0.4° ( P = .363; 95% CI, –0.8° to 0.4°). A significant difference in LPTS was also observed in the nonoperated subgroup. No significant association was observed between LPTS and operational status. Conclusion: Lateral posterior tibial slope increased more in the ACL-injured knee than in the contralateral uninjured knee in a group of skeletally immature patients. Lateral posterior tibial slope at baseline was not associated with the need for surgical reconstruction over the study period.

Objectives Cross-country (CC) skiing consists of two main techniques: classic and skating. Hip motion during the skating technique is similar to that in ice skating and is considered a risk factor for femoroacetabular impingement (FAI) in ice hockey players. We aimed to compare the presence of CAM-type FAI in a cohort of elite junior CC (EJCC) skiers with a control group of non-athlete (NA) high school students. Methods Observational cohort study: EJCC skiers and NAs were recruited from a sports school and a regular high school, respectively. Baseline demographics and training history were obtained via a questionnaire. Bilateral hip MRI was performed and the alpha angle was measured in three planes. CAM deformity was defined as an alpha angle>55° on at least two MRI planes per hip. Results A total of 20 EJCC skiers and 10 NAs participated. All participants were male, aged 16–19 years. Average training volume was 528.10±68.34 hours per year for the EJCC skiers compared with 153.50±57.09 for the NAs (p<0.001). The prevalence of CAM deformity in at least one hip on MRI was 50% in both groups (10 CC skiers and 5 NAs). The average alpha angles were 52.4±6.1° in the EJCC group and 52.5±4.9° in the NA group (p=0.94). Conclusion Radiographic evidence of CAM-type FAI was not more common in the CC skiers compared with NAs. The type, rather than volume or intensity of training, maybe a more important risk factor for the development of CAM-type FAI in young athletes.

Abstract In 2018, the best available evidence has failed to show any significant clinical or functional difference between autograft and allograft for posterior cruciate ligament reconstruction. Autograft patients may have higher complication rates. Both groups show good functional outcome after reconstruction.