Objective assessment of surgical training in flexor tendon repair: The utility of a low-cost porcine model as demonstrated by a single-subject research design

OBJECTIVES: This study evaluated the utility of a porcine flexor tendon model and standard biomechanical testing procedures to quantify the acquisition of surgical skills associated with Zone II flexor tendon repair in a trainee by benchmarking task performance outcomes relative to evidence-based standards. STUDY DESIGN: Single-subject repeated measures research design. Bench-top set-up of apparatus undertaken in a University Research laboratory. After initial directed learning, a trainee repaired 70 fresh flexor digitorum profundus tendons within the flexor sheath using either a Pennington or ventral-locking-loop modification of a two-strand Kessler core repair. Tendon repairs were then preconditioned and distracted to failure. Key biomechanical parameters of the repair, including the ultimate tensile strength (UTS), yield strength, 3 mm gap force and stiffness, were calculated. Repairs were divided into 3 categories, early (first 10 days), intermediate (ensuing 10 days), and late repairs (final 10 days), and potential changes in repair properties over the training period were evaluated using a general linear modeling approach. RESULTS: There was a significant change in the mechanical characteristics of the repairs over the training period, evidencing a clear learning effect (p < 0.05). Irrespective of the repair technique employed, early and intermediate repairs were characterized by a significantly lower UTS (29% and 20%, respectively), 3 mm gap (21% and 16%, respectively), and yield force (18% and 23%, respectively), but had a higher stiffness (33% and 38%, respectively) than late repairs (p < 0.05). The UTS of late repairs (47-48 N) were comparable to those published within the literature (45-51 N), suggesting surgical competence of the trainee. CONCLUSIONS: This simple, low-cost porcine model appears to be useful for providing preclinical training in flexor tendon repair techniques and has the potential to provide a quantitative index to evaluate the competency of surgical trainees. Further research is now required to identify optimal training parameters for flexor tendon repair and to develop procedure-specific standards for adequate benchmarking.