Clinical and Radiographic Differentiation of Pediatric Patellar Sleeve Fractures and Other Inferior Pole Pathologies

• Published in: The American journal of sports medicine 2022-03, Vol.50 (4), p.977-983
• Main Authors: Devana, Sai K., Trivellas, Andromahi, Bennett, Abbie, Jackson, Nicholas, Beck, Jennifer J.
• Format: Article
• Language: English
• Subjects: Child; Cross-Sectional Studies; Female; Fractures, Bone - diagnostic imaging; Humans; Knee Injuries - diagnostic imaging; Male; Osteochondritis; Patella - diagnostic imaging; Patella - injuries; Pediatrics; Sports medicine
• ISSN: 0363-5465; 1552-3365
• DOI: 10.1177/03635465221073995

Background: Inferior pole patellar sleeve fractures (PSFs) are rare injuries that occur in skeletally immature patients that may be missed or falsely diagnosed as an inferior pole fracture (IPF) or Sinding-Larsen-Johansson syndrome (SLJS). Purpose: The objective of this study was to evaluate and compare clinical and radiographic features of patients with PSF, IPF, and SLJS. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Retrospective review of skeletally immature patients diagnosed with PSF, IPF, and SLJS between 2011 and 2019 at a single urban academic center was performed. Chart and radiographic review was completed. Between-group differences were assessed using analysis of variance, Kruskal-Wallis test, and Fisher exact test, as appropriate to variable distributions. Results: In total, 125 patients (82% male) were included, with a mean (SD) age of 10.7 (2) years (16 PSF, 51 IPF, 58 SLJS). There were no significant differences in patient characteristics between the 3 groups. One hundred percent of the patients with PSF (P < .001) and IPF (P < .001) had acute trauma, compared with 24% of patients with SLJS. Fewer patients with PSF had an intact straight leg raise (38%) compared with those with IPF (94%; P < .001) and SLJS (98%; P < .001). Fewer patients with SLJS had knee swelling (41%) compared with those with PSF (93%; P < .001) and IPF (94%; P < .001). More patients with PSF had knee effusion (81%) compared with those with IPF (37%; P = 0.011) and SLJS (3%; P < .001). More patients with SLJS were able to bear weight (88%) compared with those with IPF (12%; P < .001) and PSF (0; P < .001). Radiographically, compared with those with IPF and SLJS, patients with PSFs had increased mean prepatellar swelling (6.1 [P < .001] and 6.5 [P < .001] vs 12.9 mm), intra-articular effusion (6.1 [P = .014] and 4.9 [P = .001] vs 9.2 mm), maximum fragment size (26 [P = .004] and 17.7 [P < .001] vs 45.3 mm), and maximum fragment displacement (1.24 [P = .002] and 1.45 [P = .003] vs 13.30 mm), respectively. Compared with those with SLJS (1.10), patients with PSF (1.92; P < .001) and IPF (1.22; P < .001) had patella alta with higher mean Insall-Salvati ratios >1.2. Conclusion: Differences in clinical features such as ability to straight leg raise, knee swelling, knee effusion, ability to bear weight, and radiographic features, such as prepatellar swelling, intra-articular effusion, fragment displacement/size/shape/location, and patellar height, can all b