Hamstring graft size prediction: a prospective clinical evaluation.

BACKGROUND: Recently we retrospectively collected clinical data to predict hamstring graft diameter. Prospective data collection will improve and further define prediction of hamstring graft size. HYPOTHESIS: Clinical anthropometric data can be used to predict hamstring graft size. STUDY DESIGN: Cohort study (prevalence); Level of evidence, 1. METHODS: Fifty consecutive patients with anterior cruciate ligament deficiency scheduled for reconstruction using hamstring autograft were prospectively evaluated. Preoperatively we recorded height, weight, body mass index, age, gender, leg length, thigh length, shank length, bilateral thigh circumference, and Tegner score. Intraoperative measurements of both the gracilis and semitendinosus tendons were made, including absolute length before fashioning the graft and final diameter of the quadrupled graft using sizing tubes calibrated to 0.5 mm. Bivariate correlation coefficients (Pearson r) were calculated to identify relationships among clinical data and intraoperatively measured hamstring graft length and diameter. RESULTS: Strongest correlations for graft lengths were height and leg length measurements. Shorter persons with shorter leg, thigh, and shank lengths tended to have shorter gracilis and semitendinosus grafts. Likewise, the strongest correlations for graft diameter were weight and thigh circumference. Self-reported activity level and age did not correlate. Gender comparison revealed that women who were shorter, lighter, and had smaller body mass indices were more likely to have smaller graft diameters and shorter graft lengths. CONCLUSION: Patients weighing less than 50 kg, less than 140 cm in height, with less than 37 cm thigh circumference, and with body mass index less than 18 should be considered at high risk for having a quadrupled hamstring graft diameter less than 7 mm. When separated by gender, small graft diameters are most likely in older, short, female subjects with small thigh circumferences or young, skinny, male subjects with small thigh circumferences and low body mass index. Common clinical measurements can be used for preoperative identification of patients at risk for insufficient graft tissue and would be useful for patient counseling and alternative graft source planning.

Meniscal repair using an all-inside, rapidly absorbing, tensionable device.

PURPOSE: The purpose of this study was to evaluate the clinical success rate of all-inside meniscal repairs using a rapidly absorbing device in patients undergoing concurrent anterior cruciate ligament (ACL) reconstructions. METHODS: Patients with menisci repaired using the polydioxanone Mitek RapidLoc (Depuy Mitek, Raynham, MA) during concurrent ACL reconstruction were evaluated clinically 2 years following index surgery. We performed examinations on 38 meniscal tears in 30 patients using the International Knee Documentation Committee form and the Knee Disorders Subjective History visual analog scale. We also performed physical examinations for an effusion, joint line tenderness, McMurray's testing, and KT-1000 arthrometry (MEDmetric, San Diego, CA). RESULTS: The clinical success rate for meniscal repair was 86.8% (33 of 38) at a mean follow-up of 30.4 months (range, 21 to 56 months). Univariate analysis revealed sex as the only predictive variable for failure; all failures occurred in male patients. Nonpredictive variables included tear length, type, and configuration; a duration of more than 3 months, compartment, zone, ligament graft choice, age, follow-up, Tegner score, and visual analog scale score. CONCLUSIONS: The polydioxanone RapidLoc device was found to have a clinical success rate of 86.8%. These data suggest that the more rapidly absorbing polydioxanone device is effective for all-inside meniscal repair during concurrent ACL reconstruction. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Evoked electromyographic technique for quantitative assessment of the innervation status of laryngeal muscles.

OBJECTIVES: The purpose of this study was to develop a minimally invasive, noninjurious evoked electromyographic technique that could accurately quantitate the level of innervation of laryngeal muscles with recurrent laryngeal nerve stimulation. METHODS: A four-phase study was conducted in 24 canines, including 1) identification of the best stimulation-recording configuration, 2) statistical analysis of sensitivity and accuracy, 3) evaluation of safety, and 4) identification of the laryngeal muscle(s) that contribute to the evoked response. RESULTS: The results demonstrated that an entirely noninvasive technique is not feasible. The stimulating cathode must be invasive to ensure discrete activation of the recurrent laryngeal nerve, whereas both recording electrodes should remain on the surface with one overlying the thyroid ala. This configuration proved to be highly accurate, with an error rate of only 6% to 7%, and with sensitivity sufficient to detect a signal in a nerve with fewer than 1% of the axons intact. There was no evidence of nerve injury in any animal over the course of 350 stimulus needle penetrations. By use of neuromuscular blockade to identify those muscles generating the surface response, the thyroarytenoid muscle was found to be the primary contributor, whereas the posterior cricoarytenoid muscle was uninvolved. CONCLUSIONS: This evoked electromyographic technique could provide quantitative information regarding the extent of muscle innervation during denervation and regeneration in case of laryngeal paralysis.

Electrical stimulation of a denervated muscle promotes selective reinnervation by native over foreign motoneurons.

The effect of electrical stimulation of the denervated posterior cricoarytenoid (PCA) muscle on its subsequent reinnervation was explored in the canine. Eight animals were implanted with a planar array of 36 electrodes for chronic stimulation and recording of spontaneous and evoked electromyographic (EMG) potentials across the entire fan-shaped surface of a muscle pair. Normative EMG data were recorded from each electrode site before unilateral nerve section, and from the innervated partner after nerve section. After randomizing the animals to experimental and control groups, the right recurrent laryngeal nerve innervating the PCA abductor muscle and its adductor antagonists was sectioned and reanastomosed. The PCA muscle in four experimental animals was continuously stimulated during the 11-mo experiment, using a 1-s, 30-pps, biphasic pulse train composed of 1-ms pulses 2-6 mA in amplitude and repeated every 10 s. The remaining four animals served as nonstimulated controls. Appropriate reinnervation by native inspiratory motoneurons was indexed behaviorally by the magnitude of vocal fold opening and electromyographically by the potential across all electrode sites. Inappropriate reinnervation by foreign adductor motoneurons was quantitated by recording EMG potentials evoked reflexly by stimulation of sensory afferents of the laryngeal mucosa. All four experimental animals showed a greater level of correct PCA muscle reinnervation (P < 0.0064) and a lesser level of incorrect reinnervation (P < 0.0084) than the controls. Direct muscle stimulation also appeared to enhance the overall magnitude of reinnervation, but the effect was not as strong (P < 0.113). These findings are consistent with a previous report and suggest that stimulation of a mammalian muscle may profoundly affect its receptivity to reinnervation by a particular motoneuron type.