Pattern of Bone Generation after Irradiation in Vascularized Tissue Engineered Constructs.

BACKGROUND: Regenerative medicine modalities provide promising alternatives to conventional reconstruction techniques but are still deficient after malignant tumor excision or irradiation due to defective vascularization. METHODS: We investigated the pattern of bone formation in axially vascularized tissue engineering constructs (AVTECs) after irradiation in a study that mimics the clinical scenario after head and neck cancer. Heterotopic bone generation was induced in a subcutaneously implanted AVTEC in the thigh of six male New Zealand rabbits. The tissue construct was made up of Nanobone (Artoss GmbH; Rostock, Germany) granules mixed with autogenous bone marrow and 80 µL of bone morphogenic protein-2 at a concentration of 1.5 µg/µL. An arteriovenous loop was created microsurgically between the saphenous vessels and implanted in the core of the construct to induce axial vascularization. The constructs were subjected to external beam irradiation on postoperative day 20 with a single dose of 15 Gy. The constructs were removed 20 days after irradiation and subjected to histological and immunohistochemical analysis for vascularization, bone formation, apoptosis, and cellular proliferation. RESULTS: The vascularized constructs showed homogenous vascularization and bone formation both in their central and peripheral regions. Although vascularity, proliferation, and apoptosis were similar between central and peripheral regions of the constructs, significantly more bone was formed in the central regions of the constructs. CONCLUSION: The study shows for the first time the pattern of bone formation in AVTECs after irradiation using doses comparable to those applied after head and neck cancer. Axial vascularization probably enhances the osteoinductive properties in the central regions of AVTECs after irradiation.

Level I lymph node involvement in patients with N1b papillary thyroid carcinoma: a prospective study.

Most of the studies on the incidence, pattern, and predictive factors of lymph node (LN) metastasis with papillary thyroid carcinoma (PTC) have been performed retrospectively and no common consensus has been reached regarding the predictors for the involvement of level I LNs. This study was conducted prospectively to determine the incidence and the possible predictors of level I involvement in N1b PTC patients. The study included 30 consecutive patients with N1b stage of PTC. All the patients underwent neck dissection (ND) including level I. The relation between involvement of level I LNs and various clinicopathological variables was studied. Unilateral neck dissection was performed in 24 patients and bilateral neck dissection in six patients leading to 36 NDs. Level I was excised in all patients, with five specimens (14%) positive for metastasis. Levels II, III, IV, V, VI, and VII were positive in 52.8, 58.3, 58.3, 33.3, 63, and 22.2%, respectively. Level I involvement was significantly related to the number of lymph node levels affected (p = 0.003) and macroscopic extranodal invasion (p = 0.04). It was not related to the involvement of other individual levels, gender, age, size of the largest thyroid nodule, size of the largest LN involved, or histo-pathological variant of the tumor. This study suggests that including level I in therapeutic neck dissection for N1b PTC patients might be recommended in selected cases of multiple level involvement and macroscopic extranodal invasion requiring sacrifice of internal jugular vein, spinal accessory nerve, or sternomastoid muscle.

Axially vascularised mandibular constructs: Is it time for a clinical trial?

Applying regenerative therapies in the field of cranio-maxillofacial reconstruction has now become a daily practice. However, regeneration of challenging or irradiated bone defects following head and neck cancer is still far beyond clinical application. As the key factor for sound regeneration is the development of an adequate vascular supply for the construct, the current modalities using extrinsic vascularization are incapable of regenerating such complex defects. Our group has recently introduced the intrinsic axial vascularization technique to regenerate mandibular defects using the arteriovenous loop (AVL). The technique has shown promising results in terms of efficient vascularization and bone regeneration at the preclinical level. In this article, we have conducted a narrative literature review about using the AVL to vascularize tissue-engineering constructs at the preclinical level. We have also conducted a systematic literature review about applying the technique of axial vascularization in the field of craniofacial regeneration. The versatility of the technique and the possible challenges are discussed, and a suggested protocol for the first clinical trial applying the AVL technique for mandibular reconstruction is also presented.

LigaSure hemorrhoidectomy versus stapled hemorrhoidopexy: a prospective, randomized clinical trial.

PURPOSE: This study was designed to compare the outcome of LigaSure hemorrhoidectomy and stapled hemorrhoidopexy for prolapsed hemorrhoids. METHODS: Consecutive patients with grade III or IV hemorrhoids were randomly assigned to undergo either LigaSure hemorrhoidectomy or stapled hemorrhoidopexy. Data on patient demographic and clinical characteristics, operative details, postoperative pain score on a visual analog scale, number of parenteral analgesic injections, duration of hospital stay, and time to return to work were all prospectively collected. Postoperative complications and recurrence of prolapse were also recorded. Patients were regularly followed for a total period of 12 months. RESULTS: A total of 68 patients completed the study (34 per group). Patient demographic and clinical characteristics were similar in the 2 groups. No significant differences between LigaSure hemorrhoidectomy and stapled hemorrhoidopexy were observed in mean operating time, postoperative pain score, number of parenteral analgesic injections, duration of hospital stay, or time to return to work. The groups were also similar regarding postoperative complications, except that at 4 weeks postoperatively, residual prolapse was observed in 8 patients (23.5%) in the stapled hemorrhoidopexy group vs. 2 patients (5.9%) in the LigaSure group (P = .040). Rate of recurrence of prolapse at 1 year was higher with stapled hemorrhoidopexy (4 patients, 11.8%) than with the LigaSure procedure (1 patient, 2.9%), but the difference was not significant (P = .163). CONCLUSIONS: LigaSure hemorrhoidectomy and stapled hemorrhoidopexy yield comparable good results, with a short operative time and minimal side effects in the treatment of grade III and IV hemorrhoids, but with a lower rate of residual prolapse for the LigaSure procedure. Both procedures offer low levels of postoperative pain and therefore are excellent therapeutic options for prolapsed grade III and IV hemorrhoids. A larger controlled study is needed to reach solid conclusions regarding risk of postoperative recurrence of hemorrhoidal prolapse.

Assessment of parathyroid autotransplantation for preservation of parathyroid function after total thyroidectomy.

BACKGROUND: Hypoparathyroidism with permanent hypocalcemia is a well-recognized complication after thyroid surgery. AIM: This study was conducted to assess the role of immediate parathyroid autotransplantation in the preservation of parathyroid function after total thyroidectomy. PATIENTS AND METHODS: Twenty-eight patients had autotransplantation of parathyroid glands resected or devascularized during total thyroidectomy. Data were collected prospectively regarding demographics, indication for surgery, operative procedure, pathologic diagnosis, number of glands transplanted, and subsequent course. Thyroid nodules were evaluated by ultrasonography, radionuclide scanning, and/or fine-needle aspiration cytology. All patients had serum ionized calcium, phosphorus, and intact parathyroid hormone (PTH) levels measured preoperatively and monitored regularly postoperatively for a period of 14 weeks and again at 6 months after operation. Patients were categorized into three groups according to the number of glands transplanted: one (group 1, n = 6), two (group 2, n = 14), or three glands (group 3, n = 8). In three other volunteers, one parathyroid gland was transplanted in the brachioradialis and subjected to electron microscopy 1, 2, and 4 weeks after transplantation. RESULTS: Total thyroidectomy was performed for malignant disease in 16 patients (57.1%) and for benign disease in 12 (42.9%) patients. All patients reverted to asymptomatic normocalcemia without the need for any medications within 4 to 14 weeks. Normal levels of serum markers were regained slower when one gland was transplanted compared with two or three glands (P <.01). Electron microscopic examination showed evidence of ischemic degeneration in the transplanted tissues 1 week postoperatively. Regeneration started by the second week and coincided with normalization of PTH levels. Optimum resting and nearly normal status of parathyroid tissue was achieved by the fourth week. CONCLUSIONS: This study showed that active PTH production coincides with regeneration of parathyroid cells and that autotransplantation of at least two resected or devascularized glands during total thyroidectomy nearly eliminates permanent postoperative hypoparathyroidism, thus improving the safety of total thyroidectomy performed for malignant or benign disease.