Collagen Allograft Research Articles

Comparison of prognosis in two methods for the lingual nerve repair: direct suture with vein graft cuff and collagen allograft method

BackgroundNo studies have compared the outcomes of direct perineurial suture with vein graft cuff repair and indirect collagen allograft repair of the lingual nerve following an injury. Therefore, we evaluated and compared the outcomes of each over a 1-year observation period. We retrospectively assessed 20 patients who had undergone microneurosurgical repair of unilateral lingual nerve injuries at the Wakayama Medical University Hospital between May 2015 and March 2019. We utilized two different methods for lingual nerve repair, i.e., direct perineurial repair with a vein graft cuff and interpositional collagen allograft repair. Sensory and taste function in the lingual nerve were preoperatively evaluated using a static two-point discrimination test, superficial pain/tactile sensation test, tests for the pressure pain threshold (Semmens-Weinstein monofilament), test for thermal discrimination hot and cold sensation, and a taste discrimination test. These tests were performed again at 6 and 12 months postoperatively.ResultsCompared to the preoperative conditions, all patients showed improved sensory reactions. Functional sensory recovery outcomes were defined by Pogrel’s criteria, Medical Research Council Scale grades, and functional sensory recovery. In each group, all patients improved after the operation. However, the operation time was significantly shorter for an interpositional collagen allograft repair as compared to that for a direct perineurial repair with a vein graft cuff.ConclusionsThere were no statistically significant differences between the two repair Methods, except for the operation time. Both methods led to satisfactory results for all criteria. From an economic point of view, direct perineurial repair with a vein graft cuff is meaningful; however, the esthetic effect on the donor site should be considered. Conversely, interpositional collagen allograft repair has the advantage of a greatly shortened operation time.

Collagen Allografts Compared With Autologous Tissue in Tympanoplasty.

There are no direct comparisons between the success of collagen allografts versus traditional autografts for tympanic membrane (TM) repair. We sought to compare success rates in a large series of patients undergoing tympanoplasty using collagen allografts versus autologous tissues. Retrospective review. Academic medical center. Single institution retrospective chart review was performed for adult subjects with TM perforation undergoing tympanoplasty. Demographic, clinical, and surgical data were collected. Statistical analysis was completed using Rstudio. Each factor was examined to assess effect on graft success rate using logistic regression. Two hundred sixty-five surgeries met criteria with four main grafting materials or combinations thereof. The overall graft success rate was 81.1% with failure rate of 18.9%. There was no significant association between failure rates and: age, sex, perforation cause, size, and location, primary or revision status, middle ear status (wet or dry), concomitant procedures (mastoidectomy or ossiculoplasty), presence of active cholesteatoma, or surgical technique. Although not statistically significant, the odds of success for perichondrium + cartilage were 7.5 times higher than collagen allografts (p = 0.07, 95% confidence interval [CI] = 0.81-69.6). The odds of success for the postauricular (odds ratio [OR] = 6.4) and transcanal approaches (OR = 24.8) were significantly greater than for endaural (p = 0.007 and p = 0.008, respectively). In tympanoplasty surgeries performed on patients with TM perforation, we found no statistically significant difference in graft failure rates between collagen allograft and other grafting materials or combinations, though the higher odds ratio of success with cartilage + perichondrium may be clinically relevant.

Unacceptable failure of hemiarthroplasty combined with biological glenoid resurfacing in the treatment of glenohumeral arthritis in the young

Treatment of glenohumeral osteoarthritis in young patients is challenging. Total shoulder arthroplasty reliably addresses pain and dysfunction but compromises glenoid bone stock. Various efforts have been made to avoid a prosthetic glenoid component or to prevent glenoid erosion after hemiarthroplasty. Capsular interposition, meniscal allograft, and more recently, GraftJacket (Wright Medical Technology Inc, Arlington, TN, USA), a human dermal collagen allograft, have been proposed for interposition arthroplasty in young patients with glenohumeral osteoarthritis. From 2009 to 2010, GraftJacket was used for glenoid resurfacing combined with humeral resurfacing or a stemmed hemiarthroplasty in 6 patients with a mean age of 47 years (34-57 years). Before GraftJacket was available, 5 patients were treated with a meniscal allograft and 6 with capsular interposition arthroplasty. At a mean of 16 months (9-22 months) after the GraftJacket was implanted, 5 of the 6 patients were revised to a total shoulder arthroplasty or a reverse total shoulder arthroplasty. The sixth patient was dissatisfied but declined further surgery. The mean relative, preoperative Constant score decreased from 35% (range, 13%-61%) to 31% (range, 15%-43%) at revision or latest follow-up. Of the 5 patients with meniscal allograft, 3 underwent revision at a mean of 22 months (range, 12-40 months), and 4 of the 6 patients with capsular interposition were revised at a mean of 34 months (range, 23-45 months). The mean relative Constant scores preoperatively and at revision or latest follow-up were 44% (range, 19%-68%) and 58% (range, 9%-96%) for the meniscal allograft patients and 47% (range, 38%-62%) and 63% (range, 32%-92%) for the capsular interposition cases. In our hands, 3 different types of biological resurfacings combined with humeral hemiarthroplasty have an unacceptable early failure rate.

Endoscopic Management of Sphenoid Sinus Cerebrospinal Fluid Leaks

Cerebrospinal fluid (CSF) leaks that originate within the sphenoid sinus pose a unique surgical challenge due to difficulties with access and visualization The objective of this report is to illustrate concepts for the successful management of sphenoid sinus CSF leaks. Retrospective data analysis was performed on 9 patients who presented to a tertiary care medical center for endoscopic repair of a sphenoid sinus CSF leak from January 2002 to January 2006. The patient cohort included 7 women and 2 men with a mean age of 51.7 years. In 5 cases the CSF leak was caused by a previous neurosurgical procedure; the other 4 cases were idiopathic. An endoscopic pterygomaxillary fossa approach was required in 4 cases. A layered reconstruction of the sphenoid sinus wall with collagen allografts (cadaveric acellular dermal allograft, 8 patients; bovine collagen membrane, 1 patient) and mucosa under endoscopic visualization with intraoperative surgical navigation was performed in all cases. The reconstruction was buttressed with autologous bone in 2 cases and with cartilage in 2 cases. Fibrin sealant was used in 7 cases. Two patients developed transient diabetes insipidus after the repair. Two patients developed a recurrent CSF leak necessitating revision repair 2 and 15 months, respectively, after the initial repair procedure. The average hospital stay was 6.5 days. The mean length of follow-up was 21.1 months. This series demonstrates that minimally invasive endoscopic repair of sphenoid sinus CSF leaks may be accomplished with an acceptable rate of morbidity and excellent outcomes. Extended endoscopic approaches, including the pterygomaxillary fossa approach, may be useful in selected instances.

In vivo evaluation of a collagen corneal allograft derived from rabbit dermis.

This study evaluates epithelialization, clarity, intraocular inflammation, and fibroblast ingrowth of a collagen corneal allograft derived from rabbit dermis. Dermal collagen fibers were dispersed intact and chemically modified to make them soluble. The allografts consisted of a fibrous, opaque peripheral zone and a central clear area. Twelve New Zealand white rabbits underwent penetrating keratoplasty with implantation of an allograft. The grafts were evaluated daily for clarify, anterior segment inflammation, and extent of reepithelialization with a slit-lamp microscope. Epithelialization of the fibrous peripheral zone of the graft ranged from 0% to 90%. The central clear area did not epithelialize in any of the animals. Fibroblasts migrated into the peripheral zone in all eyes. Complications included ulceration of the central clear area in two eyes. There was no ulceration or leakage at the graft-host interface and no synechia, fibrous, or inflammatory retrocorneal membranes in any of the eyes. Our study is the first to describe the method of modifying dermal type I collagen into a clear corneal allograft. Survival of the corneal collagen allograft beyond 1 month may be limited by several factors including lack of epithelialization of the central clear area.

Human dermal collagen allografts: a three year histological study

A three year study of the histological appearances of glutaraldehyde treated human fibrous dermal collagen allografts is reported. There was no immune or inflammatory response and no fibrous capsule was noted. The implants were colonised by host fibroblasts and blood vessels. No collagen resorption was observed. This type of preparation may offer an alternative to autogenous dermis grafts, with the advantages that it is both cell free and does not cause donor site scarring.

Reconstruction of full-thickness loss skin wounds using skin collagen allografts

Sheets of allogeneic dermal collagen measuring 20 × 15 mm and prepared by trypsin treatment of full-thickness skin were grafted under skin flaps in rats. After 2 to 5 weeks the protective recipient skin was excised and replaced by split-thickness skin isografts which remained viable on their supportive collagen beds. On average such composite grafts maintained 84 per cent of their original size over 3 to 28 weeks and in contrast with split-thickness skin grafts achieved full-thickness reconstruction of the excised skin.

Incorporation of stored cell-free dermal collagen allografts into skin wounds: A short term study

Allogeneic dermal collagen has been evaluated as an alternative to skin autografts for the permanent replacement of lost or damaged skin in the rat. All non-collagenous structures were removed from full-thickness back skin by treatment with a solution of crystalline trypsin. Such dermal collagen preparations were grafted into skin wounds, examinated up to8/12 weeks after operation, and compared with excised wounds and skin isografts and allografts of the same initial size. The dermal collagen grafts, particularly when dressed with a sheet of dermal collagen, become recellularised, revascularised and re-epidermalised. Unlike the skin allografts, there was no evidence of cellular rejection. Whereas contracture of the excised wounds was delayed, but not suppressed, by applying a conventional dressing, collagen grafts maintained from 60 to 100 per cent of their original size. In contrast, equivalent skin isografts shrank to 50–60 per cent and showed persistent epidermal hyperplasia.

Incorporation of stored cell-free dermal collagen allografts into skin wounds: A short term study

Incorporation of stored cell-free dermal collagen allografts into skin wounds: A short term study

Histological Studies of Subcutaneous and Intraperitoneal Implants of Trypsin-Prepared Dermal Collagen Allografts in the Rat

The possibility of using allograft collagen for the permanent replacement of lost or damaged connective tissues has been examined in the rat. The cellular components of skin, which are known to be of major importance in allograft rejection, were removed by treating skin with a solution of crystalline trypsin at 15 degrees C. Non-collagenous structures were largely removed by 7 days, but the purification process continued up to 28 days without damage to the collagen fibrils. Dermal collagen allografts, which were implanted intraperitoneally or subcutaneously and biopsied 3-83 days after operation, became recellularized and revascularized without being being resorbed. In contrast to skin allografts, there was no evidence of cellular rejection of the collagen grafts, even when recipient animals had been sensitized to allogeneic skin from the same donor. Densensitization of collagen to collagenase, by treating dermal collagen with solutions of glutaraldehyde at concentrations ranging from 0.001-1.0 per cent, was also investigated in vitro and by implantation. The best results, in terms of preservation of the collagen bundle architecture and graft recellularization without persisting inflammation, were achieved with collaged pre-treated with a solution of 0.01% glutaraldehyde.

Skin collagen allografts in the rat.

THE factors involved in skin graft rejection have not been elucidated fully but it is known that the cellular components of skin, including the epidermis and its appendages, vascular endothelium and passenger leukocytes, are of primary importance in the process1. Such cellular elements can be removed by treating skin with a solution of crystalline trypsin to leave the dermal collagen component intact. A preliminary study of allografts of trypsin purified dermal collagen (hereafter referred to as dermal collagen) in the pig showed that although subcutaneous implants underwent some initial collagenolysis they achieved a state of permanence without lymphocytic infiltration occurring3. Since this concurred with the view that mature collagen shows low or no antigenicity, especially within species4–7, we thought it likely that trypsin prepared collagen could be transplanted in animals other than the pig without eliciting an immune response.