Minimally invasive photopolymerization in intervertebral disc tissue cavities

Photopolymerized hydrogels are commonly used for a broad range of biomedical applications. As long as the polymer volume is accessible, gels can easily be hardened using light illumination. However, in clinics, especially for minimally invasive surgery, it becomes highly challenging to control photopolymerization. The ratios between polymerization- volume and radiating-surface-area are several orders of magnitude higher than for ex-vivo settings. Also tissue scattering occurs and influences the reaction. We developed a Monte Carlo model for photopolymerization, which takes into account the solid/liquid phase changes, moving solid/liquid-boundaries and refraction on these boundaries as well as tissue scattering in arbitrarily designable tissue cavities. The model provides a tool to tailor both the light probe and the scattering/absorption properties of the photopolymer for applications such as medical implants or tissue replacements. Based on the simulations, we have previously shown that by adding scattering additives to the liquid monomer, the photopolymerized volume was considerably increased. In this study, we have used bovine intervertebral disc cavities, as a model for spinal degeneration, to study photopolymerization in-vitro. The cavity is created by enzyme digestion. Using a custom designed probe, hydrogels were injected and photopolymerized. Magnetic resonance imaging (MRI) and visual inspection tools were employed to investigate the successful photopolymerization outcomes. The results provide insights for the development of novel endoscopic light-scattering polymerization probes paving the way for a new generation of implantable hydrogels.

Minimally invasive repair of Morgagni hernia - A multicenter case series

Children may benefit from minimally invasive surgery (MIS) in the correction of Morgagni hernia (MH). The present study aims to evaluate the outcome of MIS through a multicenter study. National institutions that use MIS in the treatment of MH were included. Demographic, clinical and operative data were analyzed. Thirteen patients with MH (6 males) were operated using similar MIS technique (percutaneous stitches) at a mean age of 22.2±18.3 months. Six patients had chromosomopathies (46%), five with Down syndrome (39%). Respiratory complaints were the most common presentation (54%). Surgery lasted 95±23min. In none of the patients was the hernia sac removed; prosthesis was never used. In the immediate post-operative period, 4 patients (36%) were admitted to intensive care unit (all with Down syndrome); all patients started enteral feeds within the first 24h. With a mean follow-up of 56±16.6 months, there were two recurrences (18%) at the same institution, one of which was repaired with an absorbable suture; both with Down syndrome. The application of MIS in the MH repair is effective even in the presence of comorbidities such as Down syndrome; the latter influences the immediate postoperative recovery and possibly the recurrence rate. Removal of hernia sac does not seem necessary. Non-absorbable sutures may be more appropriate.

Minimally invasive repair of Morgagni hernia - A multicenter case series

Children may benefit from minimally invasive surgery (MIS) in the correction of Morgagni hernia (MH). The present study aims to evaluate the outcome of MIS through a multicenter study. National institutions that use MIS in the treatment of MH were included. Demographic, clinical and operative data were analyzed. Thirteen patients with MH (6 males) were operated using similar MIS technique (percutaneous stitches) at a mean age of 22.2±18.3 months. Six patients had chromosomopathies (46%), five with Down syndrome (39%). Respiratory complaints were the most common presentation (54%). Surgery lasted 95±23min. In none of the patients was the hernia sac removed; prosthesis was never used. In the immediate post-operative period, 4 patients (36%) were admitted to intensive care unit (all with Down syndrome); all patients started enteral feeds within the first 24h. With a mean follow-up of 56±16.6 months, there were two recurrences (18%) at the same institution, one of which was repaired with an absorbable suture; both with Down syndrome. The application of MIS in the MH repair is effective even in the presence of comorbidities such as Down syndrome; the latter influences the immediate postoperative recovery and possibly the recurrence rate. Removal of hernia sac does not seem necessary. Non-absorbable sutures may be more appropriate.

Highly efficient neural differentiation of human somatic stem cells, isolated by minimally invasive periodontal surgery

Neural stem cells (NSCs) are potential sources for cell therapy of neurodegenerative diseases and for drug screening. Despite their potential benefits, ethical and practical considerations limit the application of NSCs derived from human embryonic stem cells (ES) or adult brain tissue. Thus, alternative sources are required to satisfy the criteria of ready accessibility, rapid expansion in chemically defined media and reliable induction to a neuronal fate. We isolated somatic stem cells from the human periodontium that were collected during minimally invasive periodontal access flap surgery as part of guided tissue regeneration therapy. These cells could be propagated as neurospheres in serum-free medium, which underscores their cranial neural crest cell origin. Culture in the presence of epidermal growth factor (EGF) and fibroblast growth factor-2 (FGF-2) under serum-free conditions resulted in large numbers of nestin-positive/Sox-2-positive NSCs. These periodontium-derived (pd) NSCs are highly proliferative and migrate in response to chemokines that have been described as inducing NSC migration. We used immunocytochemical techniques and RT-PCR analysis to assess neural differentiation after treatment of the expanded cells with a novel induction medium. Adherence to substrate, growth factor deprivation, and retinoic acid treatment led to the acquisition of neuronal morphology and stable expression of markers of neuronal differentiation by more than 90% of the cells. Thus, our novel method might provide nearly limitless numbers of neuronal precursors from a readily accessible autologous adult human source, which could be used as a platform for further experimental studies and has potential therapeutic implications.

Minimally invasive strabismus surgery (MISS) for inferior obliquus recession

PURPOSE: To present a novel, minimally invasive strabismus surgery (MISS) technique for inferior obliquus recessions. METHODS: Graded MISS inferior obliquus recessions were performed in 20 eyes of 15 patients by applying two small conjunctival cuts, one at the insertion of inferior obliquus and another where the scleral anchoring of the muscle occurred. RESULTS: The amount of recession was 12.2 +/- 2.3 mm (range 6 to 14 mm). The vertical deviation, which was measured in 25 degrees of adduction, decreased from preoperatively 12.8 degrees +/- 5.6 degrees to 2.7 degrees +/- 2.2 degrees (p < 0.0001) at 6 months. LogMAR visual acuity was preoperatively -0.10 +/- 0.17 and at 6 months -0.14 +/- 0.22 (p > 0.1). In one eye (2.5%) the two cuts had to be joined because of excessive bleeding. Binocular vision improved in eight patients, remained unchanged in six patients, and decreased from 30 to 60 arcsec in one patient (p > 0.1). Conjunctival and lid swelling were hardly visible on the first postoperative day in primary gaze position in 10/20 (50%) of eyes. Five of the eyes (25%) had mild and five (25%) moderate visibility of surgery. One patient out of 15 (7%) needed repeat surgery because of insufficient reduction of the sursoadduction within the first 6 months. The dose-effect relationship 6 months postoperatively for an accommodative near target at 25 degrees adduction was 0.83 degrees +/- 0.43 degrees per mm of recession. CONCLUSIONS: This study demonstrates that small-incision, minimal dissection inferior obliquus graded recessions are feasible and effective to improve ocular alignment in patients with strabismus sursoadductorius.

Minimally invasive strabismus surgery for rectus muscle posterior fixation

AIMS: To present a novel, minimally invasive strabismus surgery (MISS) technique for rectus muscle posterior fixation. METHODS: This study reports the results of 32 consecutive MISS rectus muscle posterior fixation surgeries performed on 19 patients by applying only two small L-shaped openings where the two retroequatorial scleromuscular sutures were placed. RESULTS: On the first postoperative day, in primary position, redness was hardly visible in 16 eyes (50%) and only moderate redness was visible in 6 eyes (19%). No serious complication occurred. Preoperative visual acuity and refraction remained unchanged at 6 months (p > 0.1). The preoperative convergence excess (n = 13) decreased from 10.3 +/- 4.1 to 5.2 +/- 4.0 degrees at 6 months (p < 0.005). In all patients operated on for gaze incomitance (n = 6) improvement was achieved at 6 months. CONCLUSIONS: This study shows that keyhole minimal-dissection rectus muscle posterior fixation surgery is feasible and effective to improve ocular alignment. The MISS technique seems to be superior in the direct postoperative period since only minimal conjunctival swelling and no corneal complications were observed.

Minimally invasive strabismus surgery for horizontal rectus muscle reoperations

AIMS: To study if minimally invasive strabismus surgery (MISS) is suitable for rectus muscle reoperations. METHODS: The study presents a series of consecutive patients operated on by the same surgeon at Kantonsspital St Gallen, Switzerland with a novel MISS rectus muscle reoperation technique. Surgery is done by applying two small radial cuts along the muscle insertion. Through the tunnel obtained after muscle separation from surrounding tissue, a recession, advancement or plication is performed. RESULTS: In 62 eyes of 51 patients (age 35.4 (SD 16.3) years) a total of 86 horizontal rectus muscles were reoperated. On the average, the patients had 2.1 strabismus surgeries previously. Preoperative logMAR visual acuity was 0.38 (0.82) compared with 0.37 (0.83) at 6 months (p>0.1). On the first postoperative day, in the primary gaze position conjunctival and lid swelling and redness was hardly visible in 11 eyes, discrete in 15 eyes, moderate in 11 eyes and severe in 15 eyes. One corneal dellen and one corneal erosion occurred, which both quickly resolved. The preoperative deviation at distance for esodeviations (n = 15) of 12.5 (8.5) degrees decreased to 2.6 (7.8) degrees at 6 months (p<0.001). For near, a decrease from 12.0 (10.1) degrees to 2.9 (1.6) degrees was observed (p<0.001). The preoperative deviation at distance for exodeviations (n = 35) of -16.4 (8.5) degrees decreased to -7.9 (6.5) degrees at 6 months (p<0.005). For near, a decrease from -16.5 (11.4) degrees to -2.9 (1.5) degrees was observed (p<0.005). Within the first 6 months, only one patient had a reoperation. At month 6, in four patients a reoperation was planned or suggested by us because of unsatisfactory alignment. No patient experienced persistent diplopia or necessitated a reoperation because of double vision. Stereovision improved at month 6 compared with preoperatively (p<0.01). CONCLUSIONS: The study demonstrates that a small-cut, minimal dissection technique allows to perform rectus muscle reoperations. The MISS technique seems to reduce conjunctival and lid swelling in the direct postoperative period.

Comparison of a new, minimally invasive strabismus surgery technique with the usual limbal approach for rectus muscle recession and plication

AIM: To present a novel, minimally invasive strabismus surgery (MISS) technique for rectus muscle operations. METHODS: In this prospective study with a non-concurrent, retrospective comparison group, the first 20 consecutive patients treated with MISS were matched by age, diagnosis and muscles operated on, with 20 patients with a limbal opening operated on by the same surgeon at Kantonsspital, St Gallen, Switzerland. A total of 39 muscles were operated on. MISS is performed by applying two small radial cuts along the superior and inferior muscle margin. After muscle separation from surrounding tissue, a recession or plication is performed through the resulting tunnel. Alignment, binocular single vision, variations in vision, refraction, and number and types of complications during the first 6 postoperative months were registered. RESULTS: Visual acuity decreased at postoperative day 1 in both groups. The decrease was less pronounced in the group operated on with MISS (difference of decrease 0.14 logMAR, p<0.001). An abnormal lid swelling at day 1 was more frequent in the control group (21%, 95% confidence interval (CI) 9% to 41%, 5/24 v 0%, 95% CI 0 to 13%, 0/25, p<0.05). No significant difference was found for final alignment, binocular single vision, other visual acuities, refractive changes or complications (allergic reactions, dellen formation, abnormal conjuctival findings). A conversion to a limbal opening was necessary in 5% (95% CI 2% to 17%, 2/39) of muscles. CONCLUSIONS: This study shows that this new, small-incision, minimal dissection technique is feasible. The MISS technique seems to be superior in the direct postoperative period as better visual acuities and less lid swelling were observed. Long-term results did not differ in the two groups.

Minimally invasive video-assisted thyroid surgery: how can we improve the learning curve?

Objective. Minimally invasive video-assisted thyroidectomy (MIVAT) is a technically demanding procedure and requires a surgical team skilled in both endocrine and endoscopic surgery. A time consuming learning and training period is mandatory at the beginning of the experience. The aim of our report is to focus some aspects of the learning curve of the surgeon who practices video-assisted thyroid procedures for the first time, through the analysis of our preliminary series of 36 cases. Patients and methods. From September 2004 to April 2005 we selected 36 patients for minimally invasive video-assisted surgery of the thyroid. The patients were considered eligible if they presented with a nodule not exceeding 35mm in maximum diameter; total thyroid volume within normal range; absence of biochemical and echographic signs of thyroiditis. We analyzed surgical results, conversion rate, operating time, post-operative complications, hospital stay, cosmetic outcome of the series. Results. We performed 36 total thyroidectomy. The procedure was successfully carried out in 33/36 cases. Post-operative complications included 3 transient recurrent nerve palsies and 2 transient hypocalcemias; no definitive hypoparathyroidism was registered. All patients were discharged 2 days after operation. The cosmetic result was considered excellent by most patients. Conclusions. Advances in skills and technology have enabled surgeons to reproduce most open surgical techniques with video-assistance or laparoscopically. Training is essential to acquire any new surgical technique and it should be organized in detail to exploit it completely.

Surgical optimisation and characterisation of a minimally invasive aortic banding procedure to induce cardiac hypertrophy in mice

Left ventricular pressure overload in response to aortic banding is an invaluable model for studying progression of cardiac hypertrophy and transition to heart failure. Traditional aortic banding has recently been superceded by minimally invasive transverse aortic banding (MTAB) which does not require ventilation so is less technically challenging. Although the MTAB procedure is superior, few laboratories have documented success and minimal information on the model is available. The aim of this study was to optimise conditions for MTAB and to characterise the development and progression of cardiac hypertrophy. Isofluorane proved the most suitable anaesthetic for MTAB surgery in mice and one week after surgery MTAB animals showed significant increases in systolic blood pressure (110±6 v's 78±3(mmHg), MTAB v's sham, n=7,p

Minimal invasive surgery for coronoid fracture: technical note.

Operative treatment of coronoid fracture often requires a large dissection of soft tissue, resulting in elbow stiffness and functional limitation. The authors present a minimal invasive, safe technique, useful in the case of isolated coronoid fracture associated with elbow dislocation. This technique does not require soft tissue dissection and allows an early unlimited resumption of sports activities.