Development and inhibition of the target phenomenon in tenotomized rat muscle

Summary The sequence of development of the target phenomenon in tenotomized gastrocnemius muscle was studied: the presence of target fibres was preceded by the occurrence of contraction bands and of moth eaten appearance of the fibres. This phenomenon was far more pronounced and occurred earlier in type II than in type I fibres.This target phenomenon and the contraction artefacts could be inhibited in the tenotomized muscles by simultaneous neurotomy or immobilization of the muscle with a plaster cast. Delayed denervation inhibited also the target phenomenon, if performed less than 5 days after the tenotomy. These series of experiments seem to indicate that the target phenomenon occurs in more irritable muscle fibres and that muscular activity is needed for its development.     

Comparison of the short-term and long-term results of the Ponseti method in the treatment of idiopathic pes equinovarus

Purpose

Congenital club foot is one of the most common birth defects involving the musculoskeletal system. At present two methods are used for the treatment of this deformity: French and Ponseti method. The purpose of this study was to compare the short-term (up to three years) and long-term (three to seven years) results of treatment with the Ponseti method.

Methods

A total of 195 consecutive infants (143 boys and 52 girls) with idiopathic club foot treated with the Ponseti method in the period of 2005–2012 were included in this study; the total number of feet was 303. The severity of the foot deformity was classified according to Diméglio. When relapse occurred up until three years of age, we started with the casting again. If conservative treatment was unsuccessful we proceeded to surgical treatment.

Results

Primary correction was attained in all cases. Surgical correction of relapses was performed in 30 % of patients according to the Ponseti method (re-tenotomy of the Achilles tendon and transposition of the tibialis anterior) and in 70 % by alternative techniques. The number of relapses indicated for surgery increased with increasing period of follow-up: whereas in patients where the treatment started already in 2005 relapses occurred in 72 %, in patients included in 2011 the number of recurrences only reached 3 %.

Conclusions

It follows from our results that it is impossible to cure all club feet with casting, tenotomy of the Achilles tendon and transposition of the tibialis anterior only.     

Diabetic foot off loading and ulcer remission: Exploring surgical off-loading

IntroductionDiabetic peripheral neuropathy leads to foot deformity, soft tissues damage, and gait imbalance, all of which can increase the mechanical stress imposed on the foot and give rise to Charcot neuroarthropathy. The current International Working Group of the Diabetic Foot International Guidelines on offloading focus on managing neuropathic foot ulcers related to pressure: only 2 of their 9 recommendations deal with surgical interventions. We assess the role of surgical techniques in off-loading to heal and possibly prevent diabetic foot ulceration.MethodsWe systematically analysed published data from January 2000 to November 2020 to assess methods of surgical offloading and associated outcomes for the surgical reconstruction. We tried to identify healing, remission-rates, return to ambulation, complications and limitations.ResultsFive discrete categories of surgical offloading are used in recalcitrant ulcers: 1. Lesser toe tenotomies; 2. Metatarsal head resection ± Achilles tendon release; 3. Hallux procedures; 4. Bony off-loading procedures in the form of exostectomy; and 5. Complex surgical foot reconstruction. Adjuvant modalities including surgically placed antibiotic delivery systems show promise, but further studies are required to clarify their role and effect on systemic antibiotic requirements.Conclusions and implicationsSurgery is important to mechanically stabilise and harmonise the foot for long term off-loading and foot-protection. Surgery should not be reserved for recalcitrant cases only, but extended to ulcer prevention and remission. Further comparative studies will benefit surgical decision making to avoid recurrence and define time point when surgical off-loading could protect against irretrievable tissue loss/re-ulceration.     

Intratympanic application of botulinum toxin: experiments in guinea pigs for excluding ototoxic effects

The aim of the study was to exclude ototoxic side effects of intratympanally applied botulinum toxin. The background is that a transection of the tensor tympani tendon (tenotomy) may relieve symptoms of tinnitus due to myoclonic tensor contractions. Moreover, there are certain indications that in some cases tenotomy may influence the course of Menière’s disease positively. In such cases, a temporary (probatory) inactivation of the muscle with botulinum toxin might be better than a definitive surgical solution. Although in theory botulinum toxin should not have ototoxic side effects, a study on animals (guinea pigs) should prove this assumption. On eight guinea pigs (16 ears), the middle ear spaces (bullae) were opened and botulinum toxin was introduced. Hearing thresholds were measured via ABR recordings, prior to 1 and 3 weeks, respectively, after botulinum toxin application. Histological examinations of the middle ear mucosa were performed on each animal. In our series, the hearing thresholds remained essentially unchanged. Furthermore, no middle ear pathologies could be found in histology. No negative effects of botulinum toxin on hearing could be observed in our series. This is a precondition for the further development of the concept of intratympanical applications of the drug, to inactivate the tensor tympani muscle or for other options. This study was performed in accordance with the PHS Policy on Human Care and Use of Laboratory Animals, and the Animal Welfare Act (7 U.S.C et. Seq.); the animal use protocol was approved by the institutional Animal Care and Use Committee (IACUC) of Rostock University.     

Morphological properties of experimentally produced target fibres in tenotomized rat gastrocnemius muscle

Summary The gastrocnemius muscles of 3 groups of 10 rats, sacrified 5, 7, and 12 days respectively, following tenotomy, were submitted to different types of fixation, fixative and embedding.The occurrence of target fibres is shown not to be an artefact due to the histological procedures. Further examination demonstrates that the target phenomenon occurs in the shortest fibres on the medial side of both heads of the gastrocnemius muscle and that is consists mainly of a disarrangement of the contractile elements of the muscle fibres. This study argues that this phenomenon represents some kind of myotonic state of a pathological muscle.     

Effects of tenotomy surgery on congenital nystagmus waveforms in adult patients. Part II. Dynamical systems analysis

Congenital nystagmus (CN) is an aperiodic oscillatory eye movement disorder of unknown etiology. We examined the effect of horizontal rectus tenotomy with simple re-attachment on the dimensionality of the dynamical mechanism underlying CN. The correlation dimensions (CDs) were calculated from eight patients who had tenotomy surgery. We found no significant differences in the CDs that could be associated with the surgery. The change in dimensionality was less than 5% on average. The results suggest that the tenotomy has no effect, or only a quite small effect, on the underlying mechanism of the CN beats.     

Influence of isaxonine on the target phenomenon,muscle fibre size and neuromuscular junction in the tenotomized and denervated gastrocnemius muscle of the rat

Summary Isaxonine is reported to accelerate the rate of peripheral nerve regeneration, stimulate axonal sprouting and promote motor and sensory function recovery. The target phenomenon in muscle fibers is the morphological expression of increased stretch activity in a diseased muscle. It can be produced in the gastrocnemius muscle of the rat by tenotomy and is inhibited by simultaneous denervation. The influence of isaxonine on this experimental model was studied.Twenty Wistar rats were submitted to bilateral section of the Achilles tendon and section of the left sciatic nerve. In ten rats, treated with isaxonine, the qualitative and quantitative changes in the gastrocnemius muscle were compared with the control group over a period of 3 weeks. No statistical differences were observed in the occurrence and inhibition of the target phenomenon, the muscle fibre size and the neuromuscular junction. Isaxonine has no direct effect on a diseased muscle with an intact nerve supply, nor in the early stages afte complete denervation.Supported by grant no. 3.000.4.82 from FGWO     

Muscarinic receptor regulation in the sympathetically innervated avian expansor secundariorum

We sought to examine further the regulation of muscarinic receptors in the developing expansor secundariorum, a smooth muscle of the avian wing. [³H]Quinuclidinyl benzilate binding was used as a measure of muscarinic receptors present in the muscle, which gradually decline in density from hatch during the following few weeks. Receptor loss can be prevented by denervation of the muscle immediately after hatch, but receptor density is not recovered by denervation in older birds. As the major innervation is provided by sympathetic, noradrenergic fibres with no evidence of a cholinergic input, the action of several pharmacological agents known to affect noradrenergic transmission was examined. Reserpine partially prevented the early receptor decline but phenoxybenzamine and dimethylphenylpiperazinium did not significantly affect receptor density. The muscle was also immobilized by tenotomy, since this unique muscle is attached to the shoulder by a long, discrete tendon. Tenotomy significantly retarded the normal developmental receptor loss. It is suggested that in this muscle, muscarinic receptor density is regulated by noradrenergic nerves, possibly by a mechanism involving the transmitter, noradrenaline.