The purpose of this study was to examine polyester 5-0 sutures for locking the rectus muscles to the porous implant and their influence on the rate of exposure and other complications in retinoblastoma patients. It has been confirmed that the techniques used to suture the rectus muscles can influence the exposure rate. However, few comparisons of different sutures have been conducted for the subsequent exposure of porous polyethylene implants. In this paper, we present the results of our study on the application of polyester 5-0 sutures for orbital implants.
The incidence of unwrapped orbital implant exposure varies in the literature due to the use of different suture materials, including 5-0 polyester sutures (2.0-9.6%), 5-0 Vicryl sutures (11.7%), 6-0 polyglactin 910 sutures (5-46%), and 5-0 catgut sutures (53.0%). In this case series, the authors found a reduced exposure rate (5.8%) in the 5-0 polyester suture cases, which is consistent with a previous report.
Absorbable sutures, including Vicryl, polyglactin, and catgut sutures, are also used to lock the four rectus muscles to the anterior surface of implants. However, there are some disadvantages regarding absorbable sutures. Polyglactin 910 sutures are associated with implant extrusion or migration with absorbable sutures[5, 9], partly because of the absorbable nature of the suture, which might lose its tensile strength, resulting in lower breaking points over time. Patients have also experienced the development of stitch abscesses[11, 15]. Therefore, most authors prefer to use braided nonabsorbable sutures to close surgical wounds. In contrast to absorbable sutures, polyester has an absolute higher breaking point. As a result, none of our patients experienced implant extrusion or migration with nonabsorbable 5-0 polyester sutures in our study.
Moreover, patients with 5-0 polyester sutures in our study experienced a relatively long period from porous implant placement to exposure (20.86±15.79 months). The time to exposure using absorbable sutures was as short as 136 days, ranging up to 12.5 months[1, 2]. The possible reasons for this include the fact that polyester sutures have higher knot and suture security and holding resistance, and nonabsorbable sutures are believed to be stronger. In contrast, absorbable sutures, such as Vicryl, hold tensile strength only for approximately two to three weeks in tissue and are completely absorbed by hydrolysis within 56–70 days, typically with the following decay schedule: 75% at 2 weeks, 50% at 3 weeks, and 25% at 4 weeks.
Patients who were given intravenous or local chemotherapy have been proven to have an increased risk of complications. However, this was not true in our study. We believe this might be because 5-0 polyester, which is a nonabsorbable suture, can strongly position the implant deep within the socket for a relatively long time compared to absorbable sutures. It has been proven that with the implant positioned deep within the socket, the tension on Tenon’s capsule and conjunctiva can be decreased.
Some limitations in this study need to be noted. This study was retrospective and follow-up duration was limited for some patients, which may have introduced some bias in the results. However, the median follow-up duration in our series was similar to or longer than the follow-up duration of most series in the currently available literature. The choice of suture used to lock the rectus muscles was based on the doctors' personal experience with polyester or other materials. A randomized, prospective study comparing different sutures is lacking in the available literature but would offer additional information about the tolerance and complication rates of these types of sutures.
In conclusion, in the current study, we demonstrated that polyester 5-0 sutures are relatively safe in lowering the rate of implant exposure. This study may provide a novel and optimal suggestion for patients with retinoblastoma following enucleation that potentially results in few side effects.