Effects of tibial plateau angle and spacer thickness applied during in vitro canine total knee replacement on three-dimensional kinematics and collateral ligament strain.

OBJECTIVE: To quantify the 3-D kinematics and collateral ligament strain of stifle joints in cadaveric canine limbs before and after cranial cruciate ligament transection followed by total knee replacement (TKR) involving various tibial plateau angles and spacer thicknesses. SAMPLE: 6 hemi-pelvises collected from clinically normal nonchondrodystrophic dogs (weight range, 25 to 35 kg). PROCEDURES: Hemi-pelvises were mounted on a modified Oxford knee rig that allowed 6 degrees of freedom of the stifle joint but prevented mechanical movement of the hip and tarsal joints. Kinematics and collateral ligament strain were measured continuously while stifle joints were flexed. Data were again collected after cranial cruciate ligament transection and TKR with combinations of 3 plateau angles (0°, 4°, and 8°) and spacer thicknesses (5, 7, and 9 mm). RESULTS: Presurgical (ie, normal) stifle joint rotations were comparable to those previously documented for live dogs. After TKR, kinematics recorded for the 8°, 5-mm implant most closely resembled those of unaltered stifle joints. Decreasing the plateau angle and increasing spacer thickness altered stifle joint adduction, internal rotation, and medial translation. Medial collateral ligament strain was minimal in unaltered stifle joints and was unaffected by TKR. Lateral collateral ligament strain decreased with steeper plateau angles but returned to a presurgical level at the flattest plateau angle. CONCLUSIONS AND CLINICAL RELEVANCE: Among the constructs tested, greatest normalization of canine stifle joint kinematics in vitro was achieved with the steepest plateau angle paired with the thinnest spacer. Furthermore, results indicated that strain to the collateral ligaments was not negatively affected by TKR.

Virtual patient simulations and optimal social learning context: a replication of an aptitude-treatment interaction effect.

BACKGROUND: Virtual patients (VPs) offer valuable alternative encounters when live patients with rare conditions, such as cranial nerve (CN) palsies, are unavailable; however, little is known regarding simulation and optimal social learning context. AIM: Compare learning outcomes and perspectives between students interacting with VPs in individual and team contexts. METHODS: Seventy-eight medical students were randomly assigned to interview and examine four VPs with possible CN damage either as individuals or in three-person teams, using Neurological Examination Rehearsal Virtual Environment (NERVE). Learning was measured through diagnosis accuracy and pre-/post-simulation knowledge scores. Perspectives of learning context were collected post-simulation. RESULTS: Students in teams submitted correct diagnoses significantly more often than students as individuals for CN-IV (p = 0.04; team = 86.1%; individual = 65.9%) and CN-VI (p = 0.03; team = 97.2%; individual = 80.5%). Knowledge scores increased significantly in both contexts (p < 0.001); however, a significant aptitude-treatment interaction effect was observed (p = 0.04). At pre-test scores ≤25.8%, students in teams scored significantly higher (66.7%) than students as individuals (43.1%) at post-test (p = 0.03). Students recommended implementing future NERVE exercises in teams over five other modality-timing combinations. CONCLUSION: Results allow us to define best practices for integrating VP simulators into medical education. Implementing NERVE experiences in team environments with medical students in the future may be preferable.