Darbandi, Azad D.

Background: While the biomechanical properties of the native medial patellofemoral ligament (MPFL) have been well studied, there is no comprehensive summary of the biomechanics of MPFL reconstruction (MPFLR). An accurate understanding of the kinematic properties and functional behavior of current techniques used in MPFLR is imperative to restoring native biomechanics and improving outcomes. Purpose: To provide a comprehensive review of the biomechanical effects of variations in MPFLR, specifically to determine the effect of graft choice and reconstruction technique. Study Design: Systematic review. Methods: A systematic review was performed in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A total of 32 studies met inclusion criteria: (1) using ≥8 human cadaveric specimens, (2) reporting on a component of MPFLR, and (3) having multiple comparison groups. Results: Gracilis, semitendinosus, and quadriceps grafts demonstrated an ultimate load to failure (N) of 206.2, 102.8, and 190.0 to 205.0 and stiffness (N/mm) of 20.4, 8.5, and 21.4 to 33.6, respectively. Single-bundle and double-bundle techniques produced an ultimate load to failure (N) of 171 and 213 and stiffness (N/mm) of 13.9 and 17.1, respectively. Anchors placed centrally and superomedially in the patella produced the smallest degree of length changes throughout range of motion in contrast to anchors placed more proximally. Sutures, suture anchors, and transosseous tunnels all produced similar ultimate load to failure, stiffness, and elongation data. Femoral tunnel malpositioning resulted in significant increases in contact pressures, patellar translation, tilt, and graft tightening or loosening. Low tension grafts (2 N) most closely restored the patellofemoral contact pressures, translation, and tilt. Graft fixation angles variably and inconsistently altered contact pressures, and patellar translation and tilt. Conclusion: Data demonstrated that placement of the MPFLR femoral tunnel at the Schöttle point is critical to success. Femoral tunnel diameter should be ≥2 mm greater than graft diameter to limit graft advancement and overtensioning. Graft fixation, regardless of graft choice or fixation angle, is optimally performed under minimal tension with patellar fixation at the medial and superomedial patella. However, lower fixation angles may reduce graft strain, and higher fixation angles may exacerbate anisometry and length changes if femoral tunnel placement is nonanatomic.

Background: Approximately 90% of patients who undergo arthroscopic rotator cuff repair (RCR) are satisfied with their pain levels and function after surgery. However, a subset of patients experience continued symptoms that warrant revision surgery. Preoperative risk factors for RCR failure requiring revision surgery have not been clearly defined. Purpose: To (1) determine the rate of RCR failure requiring revision surgery and (2) identify risk factors for revision surgery, which will help surgeons to determine patients who are at the greatest risk for RCR failure. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: A systematic review and meta-analysis in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were performed. The initial search resulted in 3158 titles, and 533 full-text articles were assessed for eligibility. A total of 10 studies met the following inclusion criteria: (1) human clinical studies, (2) arthroscopic RCR, (3) original clinical research, and (4) evaluation of preoperative risk factors for revision. Results: After a full-text review, a total of 16 risk factors were recorded and analyzed across 10 studies. Corticosteroid injection was the most consistent risk factor for revision surgery, reaching statistical significance in 4 of 4 studies, followed by workers’ compensation status (2/3 studies). Patients with corticosteroid injections had a pooled increased risk of revision surgery by 47% (odds ratio, 1.44 [95% CI, 1.36-1.52]). Patients with workers’ compensation had a pooled increased risk of revision surgery by 133% (odds ratio, 2.33 [95% CI, 2.09-2.60]). Age, smoking status, diabetes, and obesity were found to be risk factors in half of the analyzed studies. Conclusion: Corticosteroid injections, regardless of the frequency of injections, and workers’ compensation status were found to be significant risk factors across the literature based on qualitative analysis and pooled analysis. Surgeons should determine ideal candidates for arthroscopic RCR by accounting for corticosteroid injection history, regardless of the frequency, and insurance status of the patient.