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Biomedical subjects

V P Kumar

Publications and source records attributed to V P Kumar.

At least 37 records · Page 2Linked to original sources
PubMed1998

Neurovascular supply of the gracilis muscle: a study in the monkey and human.

A comparison of the gross anatomy, extramuscular nerve branches, and intramuscular blood supply of the gracilis muscle showed similar patterns in both monkey and human. The number and pattern of distribution of the extramuscular terminal branches to the muscle were similar. The intramuscular neural pattern demonstrated with the Sihler's staining technique was also similar in both species. In vivo electrical stimulation studies in the monkey revealed that stimulating each extramuscular terminal nerve branch produced a distinct segmental contraction of the muscle. Independent contraction with force generation was observed when the monkey muscle was split into anterior and posterior segments and stimulated through each of the two subdivisions of the main nerve trunk to the muscle. Angiograms verified that circulation was preserved in these two segments.

Animals↗
PubMed1997

Modified Sihler's technique for studying the distribution of intramuscular nerve branches in mammalian skeletal muscle.

BACKGROUND: A largely forgotten technique initially designed by Sihler for staining nerve tissue has not been fully explored for staining intramuscular nerve branches in skeletal muscles. METHODS: Fresh, long heads of triceps from locally bred New Zealand white rabbits were used for this study. Immediately after their removal, the muscles with their motor nerve branches from the radial nerve were fixed in 10% unneutralized formalin, followed by maceration and depigmentation in 3% aqueous potassium hydroxide, decalcification in Sihler's solution I, micro-dissection, staining in Sihler's solution II, destaining in Sihler's solution I, neutralization in 0.05% lithium carbonate, and clearance in increasing concentrations of glycerin. RESULTS: A clear three-dimensional orientation of the distribution of the intramuscular nerve branches within the muscle belly was visualized. It was found in all specimens that the long head of triceps in the rabbit was constantly innervated by three main intramuscular nerve branches and each of them supplied different amounts of muscle fibers with some variation. CONCLUSION: The Sihler's neural staining technique can be applied to the study of the distribution of intramuscular nerve branches in limb skeletal muscles. Extension of the technique may be utilised in the identification of neuromuscular compartments in skeletal muscles. Such information may be usefully applied in free muscle transfer of segments of skeletal muscle.

Animals↗
PubMed1997

Distribution of primary motor nerve branches and terminal nerve entry points to the forearm muscles.

BACKGROUND: The information available on innervation pattern of the human forearm muscles in standard anatomy texts, although adequate for routine procedures, is not detailed enough for surgical reconstruction in complex injuries of the limb and for paralytic conditions of the forearm from peripheral nerve and spinal cord injuries. METHODS: The innervation pattern in 10 cadaveric forearms was studied. The contributions of the main nerve trunks to each forearm muscle was examined. The location and number of the primary motor nerve branching points and of the terminal nerve entry points to each muscle were investigated. The location of both the primary nerve branching points and terminal nerve entry points was presented as a percentage of forearm length measured from the lateral humeral epicondyle to the radial styloid. RESULTS: Seven of 19 forearm muscles were innervated from a single branch from the main nerve trunk. The remaining 12 received more than one primary branch. Two of 19 forearm muscles had only one terminal nerve entry point. The others had two or more each. In 13 of 19 forearm muscles, the statistical median location of the primary motor nerve branching points was within the proximal one-third of the forearm length and either more proximally or distally for the remainder. The statistical median location of the terminal nerve entry points was within the proximal one-third in 9 forearm muscles and within the middle one-third of the forearm in 8 forearm muscles. In two, it was located proximal to the elbow and in the distal one-third of the forearm, respectively. CONCLUSIONS: In lacerations across the forearm, where main nerve trunks are divided, mere repair of the nerve trunks would not address the denervation of muscle or segments of muscle by the division of the primary (or secondary) nerve branches traversing the wound and which took origin proximal to the laceration either from the divided nerve trunks or from other undamaged nerve trunks. Although the main nerve trunks may be intact, segmental crush injuries will defunction muscles by direct muscle damage or by damage to the terminal nerve entry points to the muscle. Knowledge of the location of the nerve branches and the terminal nerve entry points facilitates the insertion of electrodes at the motor points of forearm muscles for functional electrical stimulation in upper motor neuron lesions. The information in this study may also be usefully applied in selective denervation procedures to balance muscles in spastic upper limbs.

Adult↗
PubMed1997

The anatomy of the anterior origin of the deltoid.

We studied the origin of the anterior deltoid from the lateral third of the clavicle and the leading anterior edge of the acromion in 18 cadaver shoulders by anatomical and histological methods. The main origin of the deltoid was from the superior surface of the anterior acromion, but muscle and tendinous attachments were also seen on the entire anterior surface of the acromion, its anteroinferior surface and on the whole width of the anterior surface of the clavicle. Mock arthroscopic acromioplasty was shown to detach deltoid fibres from the anterior surfaces, leaving the superior attachment in continuity. Potentially, arthroscopic subacromial and clavicular resection can detach deltoid fibres originating from the anterior and anteroinferior surfaces of the acromion and clavicle and thus weaken the anterior deltoid.

Acromion↗
PubMed1996

Infection of vascularized fibular grafts.

Between June 1978 and July 1991, 64 limb reconstructions were done using vascularized fibular grafts. Of these, 10 became infected. Five grafts were proven viable, whereas the other 5 were proven nonviable based on the survival of the skin in the composite osteocutaneous graft and from bone scans, angiograms, and biopsies. A distinct difference in the radiologic manifestation and clinical course of the infection was noted between the viable grafts and nonviable grafts. The viable grafts showed radiologic changes of osteomyelitis that were localized, and the graft incorporated, healed with antibiotics, and exhibited graft hypertrophy. In the nonviable grafts, the radiologic changes were extensive, evidence that resorption of the grafts had resulted. This suggests that, because of the poor prognosis associated with infection of the nonviable vascularized fibular grafts, the infected grafts should be removed early to minimize the morbidity and to shorten the protracted course associated with infection. With the infected viable grafts, efforts at salvaging the graft with multiple debridements and systemic antibiotics were rewarding.

Adolescent↗
PubMed1996

Elbow dislocation with ipsilateral radial shaft fracture. An unusual outcome.

The authors describe an uncommon injury of the upper limb, namely, dislocation of the elbow with fracture of the ipsilateral radial shaft, in a young man. After closed reduction of the joint, the radial head was found to be subluxated, and when a nonanatomic internal fixation of the radial shaft was undertaken, the radial head became dislocated. Repeat operation with removal of the implants and internal fixation with correction of rotation and angulation at the fracture site and reconstruction of the annular ligament restored normal anatomy.

Adult↗
PubMed1996

The Brunelli reversed flow pedicle flap from the thumb.

A reversed flow pedicle flap based on the dorsoulnar collateral vascular supply to the thumb, originally described by F. Brunelli, was used to cover a large volar defect of the little finger. The versatility of the flap, the possibility of innervation, and minimal donor-site morbidity give it advantages over the simple cross-finger and even the innervated cross-finger flaps.

Adult↗
PubMed1996

Terminal nerve branch entries (motor points) of forearm muscles: a comparative study between monkey and human.

A study of the number of muscles, the nerve branches innervating them and number and distribution of the motor points was carried out on the forearm of the monkey (Macaca fascicularis) and human. There were 8 flexor muscles and 11 extensor muscles in the human, while there were 7 flexors and 12 extensors in the monkey. The distribution of the branches of the median, ulnar and radial nerves were similar in both species. The number of motor points and their distribution in the flexor and extensor muscles also showed considerable similarity between the two species. The monkey is a suitable experimental animal model for the study of the clinical application of functional electrical stimulation of the paralyzed forearm and hand of patients with upper motor neuron lesions.

Animals↗
PubMed1996

Arthroscopy of the knee.

Arthroscopy of the knee was first performed early this century. However, it became generally accepted and grew to be a major contributor to orthopaedic surgery only during the last two decades. It has improved our understanding of numerous knee pathologies and allowed us to treat many of these disorders with considerably less morbidity. But there remain areas that warrant attention. Training in arthroscopic technique needs to be intensified and our knowledge of knee conditions should be improved if we are to avoid certain pitfalls and complications during arthroscopic surgery. Another issue that must be addressed is the inappropriate use and abuses of arthroscopic surgery of the knee. Improved audit, that insist on photographic documentation of the lesion before and after treatment is suggested to curb this latter problem.

Arthroscopes↗
PubMed1995

Surgical management of osteochondral fractures of the phalanges and metacarpals: a surgical technique.

We report a technique of reducing and stabilizing osteochondral fractures of the metacarpals and phalanges, using the principle that the space within a joint is only "potential." Accurate reduction of the fragment and accurate approximation of the capsular rent effectively traps and holds the fragment without the need for internal fixation. Preservation of all soft tissue attachment to the fragments and early supervised mobilization ensure healing of both the bony and hyaline cartilage components.

Adolescent↗
PubMed1995

Fatigue reduction by sequential stimulation of multiple motor points in a muscle.

The purpose of this study was to determine the optimal method of stimulating multiple motor points in a muscle in an attempt to improve fatigue resistance. The long head of triceps, which has 2 to 3 motor points, in an adult New Zealand white rabbit was used as the muscle model. The fatigue index, defined as the percentage of maximum force at time t, was compared during the fatigue tests. Five test groups were defined based on the stimulation pattern of the muscle: (1) Group A1: The proximal motor point was stimulated at 20 Hz; (2) Group A2: The distal motor point was stimulated at 20 Hz; (3) Group B: Both motor points were stimulated simultaneously at 20 Hz; (4) Group C: Both proximal and distal motor points were stimulated at alternate intervals of 10 seconds at 20 Hz; and (5) Group D: Both motor points were stimulated sequentially at 10 Hz. Each test was conducted for 6 minutes. In sequential stimulation (Group D), the fatigue index was significantly higher when compared with the other test groups at Minutes 4, 5, and 6. In groups A1, A2, B, and C, there were no significant differences in the fatigue indices. For optimal control of muscle contraction in functional electrical stimulation, electrodes should be inserted into all motor points for a given muscle. Sequential stimulation of these points can improve fatigue resistance.

Animals↗
PubMed1995

Clinical applications of functional electrical stimulation.

Functional Electrical Stimulation (FES) allows the restoration of controlled muscle contractions, and hence limb function via computer control, in patients with irrecoverable upper motor neuron lesions. Wide experience has been recorded in spinal cord injured paraplegics and tetraplegics and to a lesser extent in cerebrovascular accident victims. The electrodes, either surface or implanted, stimulate muscles electrically through a stimulator activated by a control source which is in turn activated by the remaining functions of the user. Future advances in electrode technology and control and command sources activation systems as well as development of "close-loop" systems need to be made if wide patient acceptance of this modality is to be ensured.

Cerebrovascular Disorders↗
PubMed1995

Post-traumatic differential osteoporosis of the patella.

The differential density developing after patella fractures between the proximal and distal poles has been attributed to avascular necrosis of the proximal fragment. Six cases are presented here where differential densities between the proximal and distal poles developed after trauma to the patella or knee. Based on the natural history of the condition, the rapidity of onset of the differential densities, osteoporosis of the whole patella later and complete resolution of the changes finally, we postulate that this phenomenon is due to a differential rate of osteoporosis of the proximal and distal parts of the patella because of the differences in their blood supply and not because of avascular necrosis of the proximal pole.

Adult↗
PubMed1995

Contractile characteristics on electrical stimulation of muscle with multiple motor points. An in vivo study in rabbits.

The purpose of this study was to investigate the significance of motor points in muscle and to determine their role in functional electrical stimulation. The long head of the triceps in adult female rabbits was used as the muscle model to study the contractile response to electrical stimulation of 1 motor point as opposed to simultaneous stimulation of multiple motor points in the muscle belly. The contractile response was studied with gradually increasing voltage amplitude and with or without added loads. Simultaneous stimulation of multiple motor points gave a consistently greater range of elbow extension when compared with stimulation of individual motor points. At low-voltage values, simultaneous stimulation of multiple motor points gave excursions obtainable only with high voltages on a single motor point. This pattern was observed with and without loads. These findings indicate that for optimal control of muscle contraction in functional electrical stimulation, electrodes may need to be inserted into multiple motor points for a given muscle. Stimulation for maximal muscle function then may be possible in the optimal low-voltage range without relying on spillover effect of high voltages. Nerve, muscle, and electrode damage also may be avoided.

Animals↗