Distal Biceps Brachii Tendon Transfer for Re-establishing Extrinsic Finger Function: Feasibility Study in Cadavers.

PURPOSE: To determine the anatomic feasibility of transferring the biceps brachii tendon into either the extensor digitorum communis (EDC) or flexor digitorum profundus (FDP), determine the excursion imparted to EDC and FDP tendons after transfer, and compare the work capacity of the cadaver biceps to previously published data on the biceps as well as the recipient muscles by calculating the physiologic cross-sectional area (PCSA). METHODS: Four fresh-frozen cadaver shoulder-elbow-wrist specimens were used to measure tendon excursion that can be obtained with transfer of the distal biceps tendon into either the EDC or FDP. Two cadavers had distal biceps-to-EDC transfer performed, and the other 2 had distal biceps-to-FDP performed. Passive ranging of each elbow from flexion to extension and active loading at 90° of elbow flexion were then performed on each specimen to determine tendon excursion. An analysis of the PCSA of the biceps muscle was performed on each specimen. RESULTS: Distal biceps-to-EDC transfer resulted in an average of 24 mm of tendon excursion with passive loading, and 24 mm of tendon excursion with active loading. Distal biceps-to-FDP transfer resulted in an average of 24 mm of tendon excursion with passive loading, and 24 mm of tendon excursion with active loading. The average PCSA was 3.6 cm2. CONCLUSIONS: Transfer of the distal biceps tendon into the EDC or FDP is anatomically feasible and provides roughly 24 mm of tendon excursion to the tendon units. The PCSA in the specimens used is slightly lower than other published data; it closely approximates the PCSA of the EDC, but is only half of the PCSA of the FDP in previously published data. CLINICAL RELEVANCE: The findings suggest potentially novel transfer options for restoring finger flexion and extension in patients lacking FDP or EDC function.

Comparison of radiation exposure in lumbar pedicle screw placement with fluoroscopy vs computer-assisted image guidance with intraoperative three-dimensional imaging.

BACKGROUND/OBJECTIVE: Little is known about the long-term effects of chronic exposure to ionizing radiation. Studies have shown that spine surgeons may be exposed to significantly more radiation than that observed in surgery on the appendicular skeleton. Computer-assisted image guidance systems have been shown in preliminary studies to enable accurate instrumentation of the spine. Computer-assisted image guidance systems may have significant application to the surgical management of spinal trauma and deformity. The objective of this study was to compare C-arm fluoroscopy and computer-assisted image guidance in terms of radiation exposure to the operative surgeon when placing pedicle screw-rod constructs in cadaver specimens. METHODS: Twelve single-level (2 contiguous vertebral bodies) lumbar pedicle screw-rod constructs (48 screws) in 4 fresh cadavers were placed using standard C-arm fluoroscopy and computer-assisted image guidance (Stealth Station with Iso-C(3D)). Pedicle screw-rod constructs were placed at L1-L2, L3-L4, and L5-S1 in 4 fresh cadaver specimens. Imaging was alternated between C-arm fluoroscopy and computer-assisted image guidance with StealthStation Iso-C(3D). Radiation exposure was measured using ring and badge dosimeters to monitor the thyroid, torso, and index finger. Postprocedure CT scans were obtained to judge accuracy of screw placement. RESULTS: Mean radiation exposure to the torso was 4.33 +/- 2.66 mRem for procedures performed with standard fluoroscopy and 0.33 +/- 0.82 mRem for procedures performed with computer-assisted image guidance. This difference was statistically significant (P= 0.012). Radiation exposure to the index finger and thyroid was negligible for all procedures. The accuracy of screw placement was similar for both techniques. CONCLUSIONS: Computer-assisted image guidance systems allow for the safe and accurate placement of pedicle screw-rod constructs with a significant reduction in exposure to ionizing radiation to the torso of the operating surgeon.