Proximity of the posterior interosseous nerve during cortical button guidewire placement for distal biceps tendon reattachment.

PURPOSE: To assess the distance between the posterior interosseous nerve (PIN) and a distally and ulnarly directed guide pin for placement of a cortical button to reattach a distal biceps tendon. METHODS: We used 10 fresh frozen cadaveric upper limbs without deformities and identified the PIN through a dorsal approach. We performed a single incision anterior surgical approach, detached the biceps tendon, and drilled a 1.6-mm K-wire from the base of the biceps tendon insertion in 3 different trajectories, sequentially, measuring the following drilling angles: 30° distal and 30° ulnar, 30° ulnar, and 30° distal. In each testing scenario, we measured the minimum distance in millimeters between the tip of the K-wire and the PIN using a digital caliper through the dorsal incision. RESULTS: The mean and median distances from the guide wire to the PIN in each testing trajectory were each significantly different from each other, with the 30° ulnar direction leading to the greatest distance from the nerve. CONCLUSIONS: We found that the 30° ulnar drilling direction resulted in a significantly greater distance from the guide wire to the PIN, in comparison with the distal-ulnar and the distal-only trajectories. CLINICAL RELEVANCE: This study helps define the safe trajectory for guide wire placement in bicortical fixation of distal biceps tendon injuries.

Autograft versus allograft with or without demineralized bone matrix in posterolateral lumbar fusion in rabbits. Laboratory investigation.

OBJECT: Posterolateral spinal fusions are performed to treat different spinal disorders. Autograft continues to be the gold standard; it is, however, associated with donor site morbidity and limited sources. Allograft has been used, but has been reported to result in lower fusion rates. Demineralized bone matrix (DBM) has also been used and reportedly increases the fusion rate in a variety of critical defect models. Different forms of DBM are available, not all have been independently studied. To evaluate the effect of a xenogenic DBM added to allograft on the fusion rate of posterolateral lumbar spine arthrodesis the authors designed an experimental study comparing posterolateral fusion rate using autograft, allograft, and allograft plus a xenogenic DBM in a validated animal model. METHODS: A bilateral, 1-level (L4-5) intertransverse process fusion was performed in 45 male New Zealand rabbits. Iliac crest bone graft was harvested bilaterally from each rabbit. The rabbits were randomly assigned to 3 groups: Group I, Autograft, 15 rabbits; Group II, Allograft, 15 rabbits; and Group III, Allograft plus DBM in a paste form (Dynagraft). The animals were killed 8 weeks after surgery. Fusion was assessed radiographically and by manual palpation by 2 independent observers. The results were analyzed using the Fisher exact test and chi-square test. RESULTS: The fusion rate was 46.6% (7 of 15 rabbits) in the autograft group, 33.3% (5 of 15 rabbits) in the allograft group, and 33.3% (5 of 15 rabbits) in the allograft plus DBM group (p > 0.05). CONCLUSIONS: Autograft produced a higher fusion rate than allograft in this spinal fusion rabbit model, but the difference was not statistically significant. Allograft plus xenogenic DBM showed the same fusion rate as allograft alone.