Introduction Rotator cuff tears are one of the most common musculoskeletal problems affecting the adult population and can cause significant pain and disability. Large tears often require surgical repair but repair failure remains a significant clinical problem with failure rates reported as high as 94%.⁴ Hence, there is a growing need for an effective clinical solution.

Implanted scaffolds are an increasingly popular option to improve the biomechanical properties and native repair process. Over 20 scaffolds are commercially available and these are derived from mammalian tissue, synthetic polymers or a combination thereof.

Despite increasing scaffold use, several concerns regarding their efficacy, safety, biocompatibility and mechanism of action remain. In this in vitro study we have assessed the interactions of human tenocytes from rotator cuff tear patients with 8 commercially available scaffolds. We hypothesise that there will be a difference in cell adhesion and proliferation between the 8 scaffolds. By using diseased human tenocytes, we hypothesise that this in vitro model will more accurately represent human rotator cuff cell response in vivo. In the absence of comparative clinical studies, this model may provide surgeons with information to help them select the most appropriate scaffold for their patients.

Methods Tenocytes were extracted from tissue biopsies taken from 2 patients with large-massive rotator cuff tears who were undergoing subacromial decompression surgery. Tenocytes were seeded onto the prepared scaffolds and incubated in supplemented growth media for 28 days.³ Initial cell attachment was assessed using AlamarBlue^® assay on day 1. Cell proliferation was measured using AlamarBlue^® assay every 3 days over the 28-day period.

Results Finely meshed X-Repair and Poly-Tape scaffolds demonstrated the greatest cell attachment at day 1 (p < 0.05). Other scaffolds performed similarly, with no significant difference.

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Abstract 95 Figure 1

Cell proliferation over 28 days

GraftJacket demonstrated statistically increased rate of cell proliferation, particularly during the first 2 weeks. Cell proliferation on all scaffolds was similar after 28 days.

Discussion Initial cell attachment was greatest on synthetic scaffolds with straight, regularly oriented, and densely packed fibres. The parallel orientation and dimensions of these synthetic fibres mimic those of native collagen tendon fibres and may account for increased initial cell attachment.

Cell proliferation during the first 2 weeks was greatest on non-crosslinked, non-irradiated, human-derived dermis, GraftJacket. These results confirm favourable outcomes from several clinical studies that used GraftJacket to augment rotator cuff repair.^1,2,5 Cell proliferation appeared to be similar on all scaffolds after 28 days, most likely due to cell confluence on the substratum. In terms of biological versus synthetic materials, no clear trend was observed in terms of cell proliferation, but factors such as scaffold structure, collagen source, polymer type and industrial processing techniques could be suggested as possible modulators of cell attachment and growth.

References 1 Barber, et al. Arthroscopy. 2012;28:8–15

2 Bond, et al. Arthroscopy. 2008;24:403–409

3 Chard, et al. Ann Rheum Dis. 1987;46:385–390

4 Galatz, et al. J Bone Joint Surg Am. 2004;86:219–224

5 Wong, et al . J Shouler Elbow Surg. 2010;19:104–9