Case series. Level IV evidence.

Background Idiopathic clubfoot correction is commonly performed using the Ponseti method and is widely reported to provide reliable results. However, a relapsed deformity may occur and often is treated in children older than 2.5 years with repeat casting, followed by an anterior tibial tendon transfer. Several techniques have been described, including a whole tendon transfer using a two-incision technique or a three-incision technique, and a split transfer, but little is known regarding the biomechanical effects of these transfers on forefoot and hindfoot motion. Questions/purpose We used a cadaveric foot model to test the effects of three tibialis anterior tendon transfer techniques on forefoot positioning and production of hindfoot valgus. MethodsTen fresh-frozen cadaveric lower legs were used. We applied 150 N tension to the anterior tibial tendon, causing the ankle to dorsiflex. Three-dimensional motions of the first metatarsal, calcaneus, and talus relative to the tibia were measured in intact specimens, and then repeated after each of the three surgical techniques. Results Under maximum dorsiflexion, the intact specimens showed 6°(95% CI, 2.2°-9.4°) forefoot supination and less than 3°(95% CI, 0.4°-5.3°) hindfoot valgus motion. All three transfers provided increased forefoot pronation and hindfoot valgus motion compared with intact specimens: the three-incision whole transfer provided 38°( 95% CI, 33°-43°; p \ 0.01) forefoot pronation and 10°( 95% CI, 8.5°-12°; p \ 0.01) hindfoot valgus; the split transfer, 28°(95% CI, 24°-32°; p \ 0.01) pronation, 9°( 95% CI, 7.5°-11°; p \ 0.01) valgus; and the two-incision transfer, 25°(95% CI, 20°-31°; p \ 0.01) pronation, 6°( 95% CI, 4.2°-7.8°; p \ 0.01) valgus.

PurposeDetermining the magnitude of displacement in pediatric lateral humeral condyle fractures can be difficult. The purpose of this study was to (1) assess the effect of forearm rotation on true fracture displacement using a cadaver model and to (2) determine the accuracy of radiographic measurements of the fracture gap.MethodsA non-displaced fracture was created in three human cadaveric arms. The specimens were mounted on a custom apparatus allowing forearm rotation with the humerus fixed. First, the effect of pure rotation on fracture displacement was simulated by rotating the forearm from supination to pronation about the central axis of the forearm, to isolate the effects of muscle pull. Then, the clinical condition of obtaining a lateral oblique radiograph was simulated by rotating the forearm about the medial aspect of the forearm. Fracture displacements were measured using a motion-capture system (true-displacement) and clinical radiographs (apparent-displacement).ResultsDuring pure rotation of the forearm, there were no significant differences in fracture displacement between supination and pronation, with changes in displacement of <1.0 mm. During rotation about the medial aspect of the forearm, there was a significant difference in true displacements between supination and pronation at the posterior edge (p < 0.05).ConclusionOverall, true fracture displacement measurements were larger than apparent radiographic displacement measurements, with differences from 1.6 to 6.0 mm, suggesting that the current clinical methods may not be sensitive enough to detect a displacement of 2.0 mm, especially when positioning the upper extremity for an internal oblique lateral radiograph.Electronic supplementary materialThe online version of this article (doi:10.1007/s11832-014-0553-8) contains supplementary material, which is available to authorized users.