Biomedical subjects

Moshe Kon

Publications and source records attributed to Moshe Kon.

7 recordsLinked to original sources

PubMed2003

The nerve supply to the clavicular part of the pectoralis major muscle: an anatomical study and clinical application of the function-preserving pectoralis major island flap.

The purpose of this study was to investigate the nerve supply to the clavicular part of the pectoralis major muscle so that the innervation to this part can be maintained in the muscle-preserving pectoralis major island-flap transfer. Although methods have been described that include a limited portion of the muscle while leaving the upper parts undisturbed with an intact motor innervation, reports on anatomical studies of this nerve supply are brief. The distal distribution of the nerves, the spatial relationship to the main vascular pedicle, and the ways to preserve them during surgical procedures remain unclear. Surgically relevant features of the clavicular part of the pectoralis major muscle were studied by dissection. The nerve supply to this part was examined on 11 sides of eight formalin-fixed cadavers. Two fresh cadavers were used for dissection, intraarterial polymer injection, and application of a nerve-preserving surgical technique. In all subjects, a separate nerve innervated the clavicular and upper medial sternocostal portions of the pectoralis major muscle. This nerve arises craniomedial to the main vascular pedicle of the flap and divides into several branches. These branches run in a fascia on the deep surface of the pectoralis major muscle, superficial to the origin and distal course of the vascular pedicle. Most branches to the clavicular part end medial to the coracoid process. The course of the branches to the upper sternocostal part is more medial. Based on their anatomical findings, the authors propose a surgical technique for transfer of the pectoralis major island flap to the head and neck area through a tunnel in the deltopectoral groove, lateral to the origin of the vascular pedicle. Head and neck reconstruction was performed using this technique. The presented method is a muscle-preserving procedure that maintains maximal donor-site function and morphology.

Cadaver↗

PubMed2003

Preservation of rat skeletal muscle function during storage for 16 h at 4 degrees C is not improved by pre-storage perfusion.

The aim of this study was to investigate if the preservation of isolated skeletal muscles for 16 h at 4 degrees C could be improved by pre-storage perfusion (PSP). Two rat muscle models were used: the soleus (SOL) and a posterior strip of the cutaneous trunci (CT). The effects of a 10 min PSP (at 25 degrees C) with University of Wisconsin solution (UW) or HTK-Bretschneider solution (HTK) on muscle function were analysed. The perfusion model was validated by the demonstration that the SOL and CT could be perfused with donor blood, UW and HTK at a flow rate of 0.2 ml x min(-1) x g(-1) muscle for 10 min without any immediate adverse effects on muscle weight, function (maximum tetanus tension) and cytoarchitecture (multivariate analysis of variance, P >0.05; n =6). For each muscle type and for each solution, six perfused and six non-perfused muscles were stored for 16 h at 4 degrees C. In the perfused groups, the storage and perfusion solution were matched. For both muscle types, the function (maximum tetanus tension), weight and cytoarchitecture of pre-storage perfused muscles was not preserved any better than that of non-perfused muscles, irrespective of the solution used (multivariate analysis of variance, P >0.05). We conclude that PSP for 10 min with UW and HTK does not improve the preservation of function of rat skeletal muscles during storage for 16 h at 4 degrees C.

Animals↗

PubMed2003

Can angiogenesis induced by chronic electrical stimulation enhance latissimus dorsi muscle flap survival for application in cardiomyoplasty?

In cardiomyoplasty, the latissimus dorsi muscle is lifted on its primary neurovascular pedicle and wrapped around a failing heart. After 2 weeks, it is trained for 6 weeks using chronic electrical stimulation, which transforms the latissimus dorsi muscle into a fatigue-resistant muscle that can contract in synchrony with the beating heart without tiring. In over 600 cardiomyoplasty procedures performed clinically to date, the outcomes have varied. Given the data obtained in animal experiments, the authors believe these variable outcomes are attributable to distal latissimus dorsi muscle flap necrosis. The aim of the present study was to investigate whether the chronic electrical stimulation training used to transform the latissimus dorsi muscle into fatigue-resistant muscle could also be used to induce angiogenesis, increase perfusion, and thus protect the latissimus dorsi muscle flap from distal necrosis. After 14 days of chronic electrical stimulation (10 Hz, 330 microsec, 4 to 6 V continuous, 8 hours/day) of the right or left latissimus dorsi muscle (randomly selected) in 11 rats, both latissimus dorsi muscles were lifted on their thoracodorsal pedicles and returned to their anatomical beds. Four days later, the resulting amount of distal flap necrosis was measured. Also, at predetermined time intervals throughout the experiment, muscle surface blood perfusion was measured using scanning laser Doppler flowmetry. Finally, latissimus dorsi muscles were excised in four additional stimulated rats, to measure angiogenesis (capillary-to-fiber ratio), fiber type (oxidative or glycolytic), and fiber size using histologic specimens. The authors found that chronic electrical stimulation (1) significantly (p < 0.05) increased angiogenesis (mean capillary-to-fiber ratio) by 82 percent and blood perfusion by 36 percent; (2) did not reduce the amount of distal flap necrosis compared with nonchronic electrical stimulation controls (29 +/- 5.3 percent versus 26.6 +/- 5.1 percent); (3) completely transformed the normally mixed (oxidative and glycolytic) fiber type distribution into all oxidative fibers; and (4) reduced fiber size in the proximal and middle but not in the distal segments of the flap. Despite the significant increase in angiogenesis and blood perfusion, distal latissimus dorsi muscle flap necrosis did not decrease. This might be because of three reasons: first, the change in muscle metabolism from anaerobic to aerobic may have rendered the muscle fibers more susceptible to ischemia. Second, because of the larger diameter of the distal fibers in normal and stimulated latissimus dorsi muscle, the diffusion distance for oxygen to the center of the distal fibers is increased, making fiber survival more difficult. Third, even though angiogenesis was significantly increased in the flap, cutting all but the single vascular pedicle resulted in the newly formed capillaries not receiving enough blood to provide nourishment to the distal latissimus dorsi muscle. The authors' findings indicate that chronic electrical stimulation as tested in these experiments could not be used to prevent distal latissimus dorsi muscle flap ischemia and necrosis in cardiomyoplasty.

Animals↗

PubMed2003

Reliability of a structured method of selecting abstracts for a plastic surgical scientific meeting.

There is no generally accepted method for assessing abstracts that are submitted for a medical scientific meeting. This article describes the development and prospective evaluation of such a method applied to the 220 abstracts submitted for the 2000 Annual Meeting of the European Association of Plastic Surgeons. Structured abstracts were evaluated in three categories: aesthetic surgery, basic research, and clinical study. Each anonymous abstract was assessed separately by 10 reputable European plastic surgeons. These reviewers used a structured rating questionnaire which resulted in a score given by each reviewer to each abstract between -6 and +6. The scores of all 10 reviewers were added for each abstract, and the papers were accepted in each of the three categories on the basis of this abridged score. To evaluate the reliability of this structured method of selection, the interrater agreement among the reviewers was tested by means of kappa analysis and the Cronbach alpha coefficient. The kappa values for agreement among reviewers regarding acceptability of abstracts were low, but the alpha coefficient indicated an acceptable degree of reliability of the average reviewers' ratings for all categories. Using a structured questionnaire can be helpful in the objective assessment of abstracts for a scientific meeting and may facilitate comparison of abstracts. Meritocratic dichotomy of abstracts by the reviewers is advocated to further improve reliability of the rating. Even though reliability generally increases with the number of reviewers, the annual increase of submitted abstracts may necessitate a decrease in the number of reviewers for each abstract.

Abstracting and Indexing↗

PubMed2002

Reducing the vascular delay period in latissimus dorsi muscle flaps for use in cardiomyoplasty.

Although the mechanism by which vascular delay benefits skin flaps is not completely understood, this topic has been extensively studied and reported on in the literature. In contrast, little has been documented about the effects of vascular delay in skeletal muscle flaps. Recent animal studies tested the effectiveness of vascular delay to enhance latissimus dorsi muscle flap viability for use in cardiomyoplasty and found that it prevented distal flap necrosis. However, these studies did not define the optimal time period necessary to achieve this beneficial effect. The purpose of this study was to determine how many days of "delay" can elicit the beneficial effects of vascular delay on latissimus dorsi muscle flaps. To accomplish this, 90 latissimus dorsi muscles of 45 male Sprague-Dawley rats were randomly subjected to vascular delay on one side or a sham procedure on the other. After predetermined delay periods (0, 3, 7, 10, and 14 days) or a sham procedure, all latissimus dorsi muscles were elevated as single pedicled flaps based only on their thoracodorsal neurovascular pedicle. Latissimus dorsi muscle perfusion was measured using a Laser Doppler Perfusion Imager just before and immediately after flap elevation. The muscles were then returned to their original vascular beds, isolated from adjacent tissue with Silastic film, sutured into place to maintain their original size and shape, and left there for 5 days. After 5 days, the latissimus dorsi muscle flaps were dissected free, scanned again (Laser Doppler Perfusion Imager-perfusion measurements), and the area of distal necrosis was measured using digitized planimetry of magnified images. The authors' results showed that delay periods of 3, 7, 10, and 14 days significantly increased (p < 0.05) blood perfusion and decreased (p < 0.05) distal flap necrosis when compared with sham controls. On the basis of these findings, the authors conclude that in their rat latissimus dorsi muscle flap model the beneficial effects of vascular delay are present as early as 3 days. If these findings also hold true in humans, they could be useful in cardiomyoplasty by allowing surgeons to shorten the amount of time between the vascular delay procedure and the cardiomyoplasty procedure in these very sick patients.

Animals↗

PubMed2002

Proximal row carpectomy: a worthwhile salvage procedure.

After proximal row carpectomy 11 patients were evaluated in the six ensuing years for pain relief, satisfaction, ranges of movement, grip and precision grip strength, and radiographic picture. The median follow-up period was 3.1 years (range 4 months to 6 years). They were operated on for scaphoid non-union with radiocarpal arthritis, late stage Kienböck's disease, chronic scapholunate dissociation and scapholunate advanced collapse wrist deformity. The mean disabilities of the arm, shoulder and hand (DASH) scoring list, which indicates the patient's degree of disability 28% (range 2%-64%) of maximum disability for the function and symptom score. Flexion, extension, and radial and ulnar deviation of the wrist improved to 47% (range 21%-76%), 67% (range 41%-81%), 39% (range 25%-55%), and 81% (range 44%-90%) of the opposite wrist. Mean grip strength, 70% (range 22%-117%) of the opposite site, while the three precision grips improved between 72% and 79%. A review of previous studies of proximal row carpectomy showed results comparable with those of our study. Compared with other treatments, it is a dependable, relatively-simple procedure that gives reliable relief of pain, preserves functional ranges of movement and grip strength, and allows most patients to return to work.

Adult↗

PubMedDate not supplied

A technique for sequential segmental neuromuscular stimulation with closed loop feedback control.

In dynamic myoplasty, dysfunctional muscle is assisted or replaced with skeletal muscle from a donor site. Electrical stimulation is commonly used to train and animate the skeletal muscle to perform its new task. Due to simultaneous tetanic contractions of the entire myoplasty, muscles are deprived of perfusion and fatigue rapidly, causing long-term problems such as excessive scarring and muscle ischemia. Sequential stimulation contracts part of the muscle while other parts rest, thus significantly improving blood perfusion. However, the muscle still fatigues. In this article, we report a test of the feasibility of using closed-loop control to economize the contractions of the sequentially stimulated myoplasty. A simple stimulation algorithm was developed and tested on a sequentially stimulated neo-sphincter designed from a canine gracilis muscle. Pressure generated in the lumen of the myoplasty neo-sphincter was used as feedback to regulate the stimulation signal via three control parameters, thereby optimizing the performance of the myoplasty. Additionally, we investigated and compared the efficiency of amplitude and frequency modulation techniques. Closed-loop feedback enabled us to maintain target pressures within 10% deviation using amplitude modulation and optimized control parameters (correction frequency = 4 Hz, correction threshold = 4%, and transition time = 0.3 s). The large-scale stimulation/feedback setup was unfit for chronic experimentation, but can be used as a blueprint for a small-scale version to unveil the theoretical benefits of closed-loop control in chronic experimentation.

Algorithms↗