Evaluation of lidocaine for brachial plexus blockade in eastern box turtles (Terrapene carolina carolina).

OBJECTIVE: To evaluate latency and duration of a brachial plexus block technique in eastern box turtles performed with 2% lidocaine at three dose rates. STUDY DESIGN: Prospective, randomized, blinded crossover study. ANIMALS: Adult eastern box turtles, two for drug dose evaluation and a group of six (three male, three female) weighing 432 ± 40 g (mean ± standard deviation) for the main study. METHODS: Animals were randomly assigned to four brachial plexus blocks with lidocaine at 5, 10 and 20 mg kg-1 or 0.9% saline (treatments LID5, LID10, LID20 and CON, respectively), separated by 1 week. Treatment side was randomized and blocks were performed unilaterally. Baseline observations of mentation, heart rate (HR), respiratory rate (fR), skin temperature and limb response to manipulation or toe pinch were evaluated. Assessments were made every 10 minutes until 1 hour of normal sensory and motor function to the treated thoracic limb, or for a total of 2 hours if no block was evident. RESULTS: Motor and sensory blockade was achieved in treatments LID10 and LID20 in one turtle, with a latency of 10 minutes and duration of 50 minutes for both doses. Raising of the ipsilateral lower palpebra occurred with both blocks. Turtles administered lidocaine experienced higher HR compared with CON, and HR decreased over time for all individuals. Mentation and fR were not changed with any lidocaine dose. CONCLUSIONS: The technique was unreliable in producing brachial plexus motor and sensory blockade at the lidocaine doses evaluated in this study. HR was higher in lidocaine-administered turtles but remained within normal limits for the species. No change in mentation or fR was observed among treatments. CLINICAL RELEVANCE: General anesthesia with systemic analgesia is recommended for surgical procedures involving the chelonian thoracic limb. Further studies are needed to optimize a brachial plexus block in this species.

Feasibility of a blind perineural injection technique for brachial plexus blockade in eastern box turtles (Terrapene carolina carolina): a cadaver study.

OBJECTIVE: To describe the anatomy of the brachial plexus in eastern box turtles (Terrapene carolina carolina), develop a blind perineural injection technique for brachial plexus blockade and evaluate the distribution of three volumes of new methylene blue dye for injection in cadavers. STUDY DESIGN: Prospective, randomized, blinded cadaveric study. ANIMALS: A total of 24 frozen-thawed box turtle cadavers; two turtles identified with shoulder injuries were subsequently excluded from the study. The remaining 22 turtles weighed 397 (190-581) g, median (range). METHODS: The brachial plexus and regional anatomy were identified by dissection of seven cadavers to determine anatomic landmarks for a perineural injection technique. This technique was tested by randomizing 15 cadavers into one of three groups to be injected bilaterally with one of three volumes (0.1, 0.2 or 0.3 mL) of methylene blue dye 1% aqueous solution. Investigators blinded to the assigned group dissected cadavers 15 minutes after injection and used staining of the four cervical spinal nerves (C5-C8; 25% for each nerve) to record a staining score of the brachial plexus (0-100%). RESULTS: Based on descriptions of the anatomy of the brachial plexus, an injection technique was designed. Injections of 0.1 mL methylene blue dye resulted in nine/10 injections with 100% nerve stained, and one/10 injection with 50% (two) nerves stained. All injections of 0.2 or 0.3 mL of methylene blue dye resulted in 100% nerves stained. CONCLUSIONS AND CLINICAL RELEVANCE: Perineural injection of the brachial plexus with 0.1, 0.2 or 0.3 mL methylene blue dye was successful in 29/30 injections in box turtle cadavers weighing 190-581 g. Further studies are needed to determine the minimum volume of injectate that can be successfully used for this technique, and to evaluate its application and efficacy in live turtles.

The multi-suture technique for rotator cuff repair: a biomechanical evaluation.

Multi-suture fixation of supraspinatus rotator cuff tears provides excellent fixation and biomechanical failure characteristics.

Olecranon fractures repaired with FiberWire or metal wire tension banding: a biomechanical comparison.

PURPOSE: Tension band constructs are commonly used for olecranon fracture fixation. The purpose of this study was to determine if a tension band constructed of FiberWire (Arthrex, Naples, FL), a high-strength polyester and polyethylene suture, will provide fixation that is equivalent to an 18-gauge metal wire tension band. METHODS: The following 4 fixation methods were biomechanically tested in cadaveric elbows with a simulated transverse olecranon fracture: (1) Kirschner wires (K-wires) with an 18-gauge metal wire tension band, (2) K-wires with a FiberWire tension band, (3) intramedullary screw with an 18-gauge metal wire tension band, and (4) intramedullary screw with a FiberWire tension band. Each elbow underwent all 4 repair methods. The K-wire repairs were performed first followed by the intramedullary screw repairs. The order of the tension band (FiberWire or metal wire) was randomly assigned. Specimens were tested under cyclic loading conditions that simulated stresses generated by (1) active range of motion and (2) pushing up from a chair. Fracture displacement was recorded by using transducers placed at the articular surface of the fracture and on the posterior surface of the olecranon. RESULTS: There were no significant differences in fracture displacement associated with the use of a high-strength suture or metal wire tension band under conditions simulating active range of motion or a more vigorous physiologic stress. Also, there were no significant differences associated with the use of an intramedullary screw versus K-wire fixation under either condition. CONCLUSIONS: The biomechanical characteristics of high-strength suture tension bands are equivalent to 18-gauge metal wire tension bands when used with either an intramedullary screw or K-wires. The fatigue patterns of high-strength suture tension bands and metal wire tension bands are similar. There is not a significant difference between the biomechanical strength of intramedullary screw fixation constructs and K-wire constructs. CLINICAL RELEVANCE: FiberWire tension bands may be used in place of metal wire tension bands without sacrificing fixation strength.

Biomechanical evaluation of 4 techniques of distal biceps brachii tendon repair.

BACKGROUND: Recent technical improvements have led the way to a resurgence of the single-incision approach for repair of distal biceps tendon injuries. There has been no biomechanical evaluation of all these techniques with comparison to the standard 2-incision bone tunnel technique. HYPOTHESIS: There will be no difference under cyclic loading and ultimate failure between the 2-incision bone tunnel technique, suture anchor repair, interference screw, and EndoButton techniques for the repair of distal biceps tendon ruptures. STUDY DESIGN: Controlled laboratory study. METHODS: Sixty-three fresh-frozen cadaveric elbows were randomly assigned to 4 treatment groups (bone tunnel, EndoButton, suture anchor, interference screw). Cyclic loading was then performed from 0 degrees to 90 degrees at 0.5 Hz for 3600 cycles with a 50-N load. A differential variable reductance transducer was placed between the radius and distal tendon to determine displacement. The construct was then pulled to failure at 120 mm/min. RESULTS: A multiple analysis of variance revealed no statistically significant difference for displacement among the 4 repair techniques. Displacement using the bone tunnel was 3.55 mm, EndoButton was 3.42 mm, suture anchor was 2.33 mm, and interference screw was 2.15 mm. There was a statistically significant greater load to failure with EndoButton (440 N) than suture anchor (381 N), bone tunnel (310 N), or interference screw (232 N) (P < .001). CONCLUSION: The EndoButton technique had the highest load to failure. CLINICAL RELEVANCE: These data demonstrate the EndoButton to be the strongest repair technique, with no failures during cycling at physiologic loads and with the largest load to failure. These findings are important in maximizing surgical results and stability and suggest that the construct can tolerate early postoperative active range of motion.

Medial opening wedge tibial osteotomy and the sagittal plane: the effect of increasing tibial slope on tibiofemoral contact pressure.

BACKGROUND: Altering the tibial slope in an anterior cruciate ligament-deficient knee has been shown to affect anterior-posterior tibial translation. The effects on articular contact pressure of altering tibial slope during a high tibial osteotomy are unknown. HYPOTHESES: Performing an opening wedge osteotomy anterior to the midaxial line will increase tibial slope. Increasing tibial slope with a high tibial osteotomy in an anterior cruciate ligament-deficient knee redistributes tibiofemoral joint contact pressures onto the posterior tibial plateau. STUDY DESIGN: Controlled laboratory study. METHODS: Medial opening wedge high tibial osteotomies were performed, and a plate fixation with a known diameter inset was placed along the medial tibia in an anterior position and a posterior position on 9 cadaveric knees. Medial and lateral tibiofemoral contact pressures were measured at the resulting 2 different tibial slopes in both ligament-intact and ligament-deficient states using thin electronic sensors. RESULTS: Anterior plate application resulted in an increase in posterior tibial slope by an average of 6.6 degrees (P < .001) compared with posterior plate placement. After medial opening wedge high tibial osteotomy, the mean peak lateral tibiofemoral contact pressure (3.4 MPa) was significantly greater (P = .002) than was the mean peak medial pressure (2.6 MPa). In ligament-intact specimens, altering the tibial slope did not significantly shift peak contact pressures. However, in ligament-deficient knees, increasing tibial slope by an average of 5.5 degrees significantly redistributed the location of peak intra-articular pressure, shifting it posteriorly by 24% (P = .003). CONCLUSION: Increasing tibial slope in anterior cruciate ligament-deficient knees with a high tibial osteotomy redistributes pressure into the posterior tibial plateau. CLINICAL RELEVANCE: In knees with chronic anterior cruciate ligament deficiency, posteromedial compartment degeneration is observed. Inadvertent redistribution of contact pressure into this area may be a cause of pain and premature clinical failure after medial opening wedge tibial osteotomy.

A biomechanical evaluation of an anatomical coracoclavicular ligament reconstruction.

BACKGROUND: Despite numerous surgical techniques described, there have been few studies evaluating the biomechanical performance of acromioclavicular joint reconstructions. PURPOSE: To compare a newly developed anatomical coracoclavicular ligament reconstruction with a modified Weaver-Dunn procedure and a recently described arthroscopic method using ultrastrong nonabsorbable suture material. STUDY DESIGN: Controlled laboratory study. METHODS: Forty-two fresh-frozen cadaveric shoulders (72.8 +/- 13.4 years) were randomly assigned to 3 groups: arthroscopic reconstruction, anatomical coracoclavicular reconstruction, and a modified Weaver-Dunn procedure. Bone mineral density was obtained on all specimens. Specimens were tested to 70 N in 3 directions, anterior, posterior, and superior, comparing the intact to the reconstructed states. Superior cyclic loading at 70 N for 3000 cycles was then performed at a rate of 1 Hz, followed by a load to failure test (120 mm/min) to simulate physiologic states at the acromioclavicular joint. RESULTS: In comparison to the intact state, the modified Weaver-Dunn procedure had significantly (P < .05) greater laxity than the anatomical coracoclavicular reconstruction or the arthroscopic reconstruction. There were no significant differences in bone mineral density (g/cm(2)), load to failure, superior migration over 3000 cycles, or superior displacement. The anatomical coracoclavicular reconstruction had significantly less (P < .05) anterior and posterior translation than the modified Weaver-Dunn procedure. The arthroscopic reconstruction yielded significantly less anterior displacement (P < .05) than the modified Weaver-Dunn procedure. CONCLUSION: The anatomical coracoclavicular reconstruction has less anterior and posterior translation and more closely approximates the intact state, restoring function of the acromioclavicular and coracoclavicular ligaments. CLINICAL RELEVANCE: A more anatomical reconstruction using a free tendon graft of both the trapezoid and conoid ligaments may provide a stronger, permanent biologic solution for dislocation of the acromioclavicular joint. This reconstruction may minimize recurrent subluxation and residual pain and permit earlier rehabilitation.

The biomechanical evaluation of four fixation techniques for proximal biceps tenodesis.

PURPOSE: The purpose of this study was to compare the cyclic displacement and ultimate failure strength of 4 proximal biceps tendon tenodesis fixation methods: the open subpectoral bone tunnel (SBT) biceps tenodesis, the arthroscopic suture anchor (SA) tenodesis, the open subpectoral interference screw (SIS) fixation technique, and the arthroscopic interference screw (AIS) technique. TYPE OF STUDY: Biomechanical experimental control. METHODS: Twenty fresh-frozen cadaver shoulders were dissected free of soft tissues, leaving the proximal humerus and the proximal biceps tendon as a free graft. Specimens were randomized to 1 of 4 groups with 5 total specimens in each group. A proximal biceps tenodesis was performed according to the techniques listed above. The specimens were mounted for an axial pull of the biceps tendon on a servohydraulic materials testing system with a 100-N load cycled at 1 Hz for 5,000 cycles, followed by an axial load to failure test. Cyclic displacement, ultimate load to failure, and site of failure were recorded for each specimen. RESULTS: The mean cyclic displacement recorded for each experimental group was as follows: SBT group, 9.39 +/- 2.82 mm; AIS group, 5.26 +/- 2.60 mm; SIS group, 1.53 +/- 0.60 mm; and SA group, 3.87 +/- 2.11 mm. The mean ultimate failure loads after 5,000 cycles were as follows: SBT group, 242.4 +/- 51.33 N; AIS group, 237.6 +/- 27.58 N; SIS group, 252.4 +/- 68.63 N; and SA group, 164.8 +/- 37.47 N. Each specimen failed at the tenodesis site. CONCLUSIONS: The SBT group showed statistically significant greater displacement than the other tenodesis methods. There were no statistically significant differences in ultimate failure strength between any of the biceps tenodesis methods tested. CLINICAL RELEVANCE: The data serve as a guide to the surgeon performing a proximal biceps tenodesis in choosing a fixation method.

Arthroscopic single-row versus double-row suture anchor rotator cuff repair.

BACKGROUND: Recurrent defects after open and arthroscopic rotator cuff repair are common. Double-row repair techniques may improve initial fixation and quality of rotator cuff repair. PURPOSE: To evaluate the load to failure, cyclic displacement, and anatomical footprint of 4 arthroscopic rotator cuff repair techniques. HYPOTHESIS: Double-row suture anchor repair would have superior structural properties and would create a larger footprint compared to single-row repair. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty fresh-frozen cadaveric shoulders were randomly assigned to 4 arthroscopic repair techniques. The repair was performed as either a single-row technique or 1 of 3 double-row techniques: diamond, mattress double anchor, or modified mattress double anchor. Angle of loading, anchor type, bone mineral density, anchor distribution, angle of anchor insertion, arthroscopic technique, and suture type and size were all controlled. Footprint length and width were quantified before and after repair. Displacement with cyclic loading and load to failure were determined. RESULTS: There were no differences in load to failure and displacement with cyclic loading between the single-row repair and each double-row repair. All repair groups demonstrated load to failure greater than 250 N. A significantly greater supraspinatus footprint width was seen with double-row techniques compared to single-row repair. CONCLUSIONS: The single-row repair technique was similar to the double-row techniques in load to failure, cyclic displacement, and gap formation. The double-row anchor repairs consistently restored a larger footprint than did the single-row method. CLINICAL RELEVANCE: The arthroscopic techniques studied have strong structural properties that approached the reported performance of open repair techniques. Double-row techniques provide a larger footprint width; although not addressed by this study, such a factor may improve the biological quality of repair.