At Issue: Pegged implants vs. unpegged implants

At Issue posed the following questions to a panel of experts: In evisceration and enucleation surgery, do you use pegged or unpegged implants? Why?

RICHARD L. ANDERSON, MD, FACS
Unpegged quasi-integrated implants

	Richard L. Anderson

I now use only unpegged quasi integrated implants. Unfortunately, I jumped on the integrated pegged coral hydroxyapatite implant bandwagon several years ago. While the pegged implants provided good motility, they also provided many complications. I have removed more pegs than I have placed in my career. The concept that exposed hardware will not cause problems and infections with time is fallacious. No matter what material is used, eventually irritation, chronic discharge, infection and extrusion are predictable complications. Integrated implants were popular 70 to 80 years ago. The old Cutler integrated pegged implant had the best motility I have ever seen. However, virtually none survived. It seems that we seldom learn from our mistakes and everything recycles. Almost any implant works for several years, and then we start seeing the complications.

Porous implants are good in theory and in reality, as they allow for vascular and fibrous ingrowth resulting in less chance of migration. However, any sharp or irregular surfaces anteriorly, such as are present on the coral hydroxyapatite and some other porous implants, will lead to erosions and extrusions. The irregular sharp surfaces cut and erode through Tenon’s and conjunctiva by rubbing on the prosthesis. In eviscerations, the sclera helps protect against sharp surfaces, but even sclera can be cut and erosions occur with time. Scuba divers know how the sharp edges of coral abrade and cut skin. Believing conjunctiva and Tenon’s are more resistant to coral than skin is fallacious.

It is time to recycle back to quasi- integrated, completely covered implants with smooth anterior surfaces. For many years I was happy with the Iowa quasi-integrated implant, which provided excellent motility and few complications. Lee Allen invented this implant, and I helped him redesign this implant and called it the Universal implant. It had smoother anterior mounds, with better volume and retention. We had excellent results with the Universal implant, but shortly after marketing it, the coral hydroxyapatite implant arrived on the scene and quasi-integrated implants were abandoned.

The Quad motility implant is easy to place, provides excellent motility without pegging and has a low exposure extrusion rate, according to Dr. Anderson. Images: Anderson RL

Several years ago, in response to the many complications with pegging and coral hydroxyapatite implants, I asked Porex Medical to design the Quad Motility Implant (Figure 1). This implant is similar to the Universal implant and was made of porous polyethylene. We further improved this implant by having the mounds and anterior surface smoothed of irregular surfaces to further decrease the chance of erosion and extrusion. This implant is easy to place, provides excellent motility without pegging and has a low exposure extrusion rate (Figure 2). In a personal series of over 100 Quad Motility Implants over 9 years, we have had only four exposures. Two required removal and replacement with a smaller implant, and two were salvaged with a patch graft. We, our ocularists and our patients, have been happy with the results of the Quad Motility Implant. It is time to go back to quasi-integrated implants and eliminate pegging forever.

For Your Information:

• Richard L. Anderson, MD, FACS, can be reached at the Center for Facial Appearances, 1002 East South Temple, No. 308, Salt Lake City, UT 84102; 801-363-3355; fax: 801-363-9613; e-mail: rick@centerforfacialappearances.com. Dr. Anderson has no financial interest in any of the products mentioned.

YOON-DUCK KIM, MD, PHD
Porous orbital implants

	Yoon-Duck Kim

In evisceration or enucleation surgery, I have used porous orbital implants such as hydroxyapatite or porous polyethylene MedPor (Porex Medical) on most patients who can afford the expense of the implant. However, I do not recommend pegging the implants to my patients these days for several reasons.

1. The majority of patients are satisfied with their motility with an unpegged porous implant and do not request a motility peg.
2. The reported complication rate of peg placement of porous implants was 37.5% to 48%. Of the complications described, discharge was the most common problem. The other complications of motility peg placement include pyogenic granuloma, peg falling out, poor transfer of movement, clicking, conjunctival overgrowth, peg drilled on an angle or off center, popping peg, conjunctival edema and protruding visible peg shaft. The most serious complication reported was implant infection requiring implant removal. I suspect some of these complications are related to the mechanical forces on the peg causing inflammation, conjunctival breakdown, exposure and infection. I have several referred cases of exposure after peg or MCP (motility coupling post) placement that needed implant removal (attaching photos).

Two cases of exposure after peg or MCP (motility coupling post) placement that needed implant removal. Images: Kim Y

Even though I do not recommend pegging, the reason I keep using porous orbital implant for my patients is that I can always drill a peg when my patient requires a peg placement for better prosthetic movement. There is no doubt that pegging of the porous orbital implant improves the range of prosthetic movement. However, the peg placement has potential problems, and these problems should be discussed with the patient before pegging.

For Your Information:

• Yoon-Duck Kim, MD, PhD, can be reached at Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Hwon-Dong, Kangnam-Ku, Seoul, Korea 135-710; 82-2-3410-3561, 3569; fax: 82-2-3410-0074; e-mail: ydkim@smc.samsung.co.kr. Dr. Kim has no financial interest in any of the products mentioned.

MARK R. LEVINE, MD
Advances in anophthalmic surgery

	Mark R. Levine

Advances in enucleation and evisceration surgery over the past 16 years, especially the introduction in 1989 of hydroxyapatite orbital implants by Dr. Arthur Perry, has revolutionized anophthalmic surgery. Before this, there were three different types of implants: (1) the buried implant of acrylic or silicone in the muscle cone behind posterior Tenon’s to establish a centrally placed implant; (2) a quasi-integrated implant such as the Allen implant and Iowa implant, leading to the Universal implant. The latter two use mounds that are coupled to concavities on the posterior surface of the prosthesis. The mounds were later reduced in size to form the Universal implant; and (3) an exposed integrated implant that, when successful, was most effective but more often than not led to implant extrusion from infection or epithelial breakdown.

Dr. Perry in 1989 designed a well-tolerated integrated hydroxyapatite orbital implant made from sea coral. The porous nature of the material allowed fibrovascular ingrowth throughout the implant and permitted insertion of a coupling device without inflammation or infection seen with exposed integrated implants. This, therefore, was a true buried integrated implant. Since that time, porous enucleation implants have been fabricated from natural or synthetic hydroxyapatite, aluminum oxide and polyethylene. In addition, surgeons wrap these implants and facilitate muscle attachment to reduce the risk of implant exposure. These materials include polyglactin mesh, bovine pericardium, sclera, dermis, autogenous fascia lata, temporalis fascia and posterior auricular muscle. Fenestrating the wrapping material allows the attached muscles to be in contact with the implant or posterior fat to improve implant vascularization.

An elective secondary procedure is performed to place the coupling peg or post to improve prosthetic motility. The pegging systems range from polycarbonate peg modified to a peg and sleeve system to a titanium peg system, as titanium is more biocompatible and better tolerated by human soft tissue than polycarbonate. This pegging can only be performed after implant vascularization, which takes about 6 months from implant surgery and can be verified by technetium bone scan, MRI scans with gadolinium or CT scanning with contrast. Failure to demonstrate vascularization will ultimately lead to infection, inflammation, and epithelial breakdown and extrusion.

Although porous implants represent a significant advancement in anophthalmic surgery, there are limitations. Complications include implant exposure, discharge, conjunctival thinning, pyogenic granuloma, implant infection, and persistent pain and discomfort. These complications seem to be related more to surgical technique, wrapping material and host factors. In addition, implant exposure rate (37.5%) after peg placement is much higher than the exposure rate in unpegged implants. Unique complications associated with pegging include pegs falling out, pyogenic granuloma around the peg or in the peg hole, improper peg placement causing poor transfer of movement, conjunctival overgrowth of the peg, and excess movement with clicking or popping.

With the rising popularity of porous implant is an associated cost. Hydroxyapatite implants today cost approximately $650 and porous polyethylene implants $520, compared with acrylic and silicone enucleation spheres that cost $15 to $50. There are charges for nonautogenous wrapping material ranging from $100 to $500, imaging studies to establish vascularization, facility charges for pegging, ocularist expenses and reoperation for complications.

With this as a review, the fundamental question of improved ocular motility between porous and nonporous implants needs to be addressed: Is there enough motility enhancement to justify the potential complications, reoperations and cost involved?

An excellent article in Ophthalmology in 2003, a report from the American Academy of Ophthalmology written by Philip Custer, MD, and colleagues, addressed this issue. The conclusion stated: “Based on one randomized clinical trial, spherical alloplastic nonporous and nonpegged porous enucleation implants provide similar implant and prosthetic motility when they are implanted using similar surgical techniques. Coupling the prosthesis to a porous implant with a motility peg or post appears to improve prosthetic motility, but there are few available data in the literature that documents the degree of improvement.” Case studies suggest that exposure rate of porous enucleation implants is similar to or higher than reported for acrylic spheres and silicone spheres. In addition, as mentioned earlier, implant exposure rate after peg placement is much higher than the exposure rate in unpegged implants, as described by Jordan et al.

In today’s medical world, with declining reimbursements, pragmatic cost cutting and the possibility of pay-for-performance looming ahead, surgeons must be able to increase their surgical caseload per day in an efficient manner while minimizing complications and reoperations.

Presently, my preference for enucleation is an 18 to 20 mm porous implant wrapped with autogenous fascia lata with anterior placement of the extraocular muscles. Access holes for extraocular muscle insertion and a posterior hole allow for good vascularization. The anterior placement of the extraocular muscles combined with autogenous fascia lata favors fewer complications. Slight vaulting of the prosthesis ensures less prosthetic drag without impairing motility. If the patient is dissatisfied with the motility, consideration is given to pegging, but to date few patients have asked for motility enhancement.

In evisceration surgery, my preference is an 18mm porous implant because of the shorter operating time and good motility. The 360° expansion sclerotomies at the equator of the scleral pouch allow for better vascularization, with absolutely no tension on the scleral suture line for closure. The prosthesis is slightly vaulted to reduce drag. Patients have been pleased with the motility and have not asked for pegging, which always remains an option.

Implant pegging, when needed, is best performed on enucleation patients, as the complication rate is less than in evisceration pegging. In addition, these patients should not be diabetic or have systemic diseases such as sarcoidosis and collagen vascular disease, as these entities may lead to healing difficulties.

Finally, an elderly patient should receive an acrylic sphere for both enucleation and evisceration. The prosthesis is slightly vaulted. In these cases, cost and longevity become a factor.

In conclusion, the search for the ideal implant has improved significantly over the past 16 years with the hope that further modification in design and technique will achieve the goal of excellent functional and cosmetic results.

For Your Information:

• Mark R. Levine, MD, can be reached at Ophthalmic Consultants of Cleveland, 1611 S. Green Road, South Euclid, OH 44121; 216-291-9770; fax: 216-295-0550; e-mail: m.levine@eye-lids.com.

References:

• Perry AC. Integrated orbital implants. Adv Ophthalmic Plast Reconstr Surg. 1990;8:75-81.
• Custer PL, Kennedy RH, et al. Orbital implants in enucleation surgery: a report by the American Academy of Ophthalmology. Ophthalmology. 2003;110(10):2054-2061.
• Custer PL, Trinkaus KM, Fornoff J. Comparative motility of hydroxyapatite and alloplastic enucleation implants. Ophthalmology. 1999;106(3):513-516.
• Jordan DR, Chan S, et al. Complications associated with pegging hydroxyapatite orbital implants.
• Ophthalmology. 1999;106(3):505-512.
• Jordan DR. Problems after evisceration surgery with porous orbital implants: experience with 86 patients. Ophthal Plast Reconstr Surg. 2004;20(5):374-380.
• Remulla HD, Rubin PA, et al. Complications of porous spherical orbital implants. Ophthalmology. 1995;102(4):586-593.

WILLIAM J. LIPHAM, MD
Options with porous implants

	William J. Lipham

I typically use porous implants for both enucleation and evisceration, unless an individual has active endophthalmitis or there is a potential risk of infection after trauma. By placing porous integrated implants, surgeons are allowing patients the opportunity to eventually pursue pegging if that is their desire.

My preference is to use porous polyethylene or MedPor ocular implants. It has been my experience that pegging these implants at a later date is superior to hydroxyapatite implants. While hydroxyapatite implants are excellent integrated implants that allow for blood vessel ingrowth within the orbit, it has been my experience, as well as others, that pegging systems for hydroxyapatite are slightly more difficult to place due to the implant’s potential to crack and break upon insertion of a pegging device. Porous polyethylene is a relatively soft material that allows placement of a self-tapping screw composed of titanium into its anterior surface, with no potential for disruption of the implant. With both implant types, however, there is an increased risk of exposure and potential infection of the implant with peg placement because a defect is made in the conjunctiva.

For this reason, I discuss the risks, benefits and alternatives of pegging the implant with my patients before proceeding with this option. Typically, I prefer to wait 1 year after placement of the original ocular implant before placing a titanium peg. While I have never had a frank exposure or infection after placement of a peg, I find that only 7.5% to 10% of my patients elect this option. Typically these are younger individuals who are more concerned with cosmeses. Deleterious side effects that I discuss with the patient before placement of the peg include exposure and infection as well as a small amount of bleeding from around the peg, which can be noted on the surface of the prosthesis, as well as a clicking sound that can be heard while the patient moves their eyes in various positions of gaze.

For Your Information:

• William J. Lipham, MD, can be reached at Minnesota Eye Consultants, 710 E. 24th St., Suite 106, Minneapolis, MN 55404; 612-813-3600; fax: 612-813-3636; e-mail: wjlipham@mneye.com.

THOMAS C. NAUGLE JR., MD
No eviscerations, no pegs

	Thomas C. Naugle Jr.

First, I no longer perform eviscerations. Although motility is generally superb, the specter of sympathetic ophthalmia always looms. The reported incidence of sympathetic ophthalmia with evisceration varies greatly, but it is real. At three meetings over the past 10 years and an audience of approximately 200 physicians, four hands were raised when asked if they had personally treated sympathetic ophthalmia after evisceration. A colleague of mine described a patient who had evisceration surgery and developed sympathetic ophthalmia. Despite aggressive treatment with steroids and antimetabolites at a referral center, the patient became blind. Other methods can produce reasonably similar motility.

Additionally, I no longer use peg implants, as I dislike opening the tight seal that is produced by using hydroxyapatite and a graft barrier to infection, and exposure with possible extrusion. I prefer using a cap graft obtained from the mastoid postauricular area, which is placed between the implant and the overlying Tenon’s capsule and conjunctiva. I have seen several infections after pegging procedures. I have also seen an unacceptable number of patients with granuloma formation around the peg in these procedures. Meticulously trimming the granulomatous tissue combined with antibody steroid drops seemed to help only temporarily in some cases, with further granuloma formation and infections in some cases. It seems that when mucosal surfaces rub against nonautogenous surfaces, granuloma formation can occur.

Although some motility may be sacrificed without pegging, it is comforting to perform the previously described procedure and know that, generally speaking, problems will be minimal.

Since performing the aforementioned procedure with a cap graft from the retroauricular mastoid area with a hydroxyapatite implant, I have experienced no exposures of the implant and no extrusions. My colleagues who perform this procedure report similar results.

For Your Information:

• Thomas C. Naugle Jr., MD, can be reached at 2633 Napoleon Ave., Suite 814, New Orleans, LA 70115; 504-899-1715; fax: 504-897-2162.

JOHN D. NG, MD, FACS
Pegging for one out of 20 patients

	John D. Ng

My primary procedure is enucleation; however, I perform evisceration under specific circumstances such as in an ill patient who cannot tolerate a more involved procedure under general anesthesia.

My preferred implant is the MedPor Plus, a spherical, high-density, porous polyethylene implant with imbedded Bioglass synthetic bone graft particulate. In most adults, I implant a 20-mm diameter implant with a small scleral cap attached with 6-0 polyglactin sutures. The extraocular muscles are secured to the edges of the scleral cap during the procedure. Alternatively, I also use the MedPor Plus SST implant, which has a smooth anterior surface and preformed suture holes. This eliminates the need for a scleral cap. Both implants are easy to use, do not cause particle tattooing that can occur with more brittle materials and are easy to insert into the intraconal space or scleral cavity. I have had good success with these implants with only one exposure, and no implant extrusions or migrations in more than 160 cases. The one exposure case occurred after an extruding hydroxyapatite implant was replaced. The patient eventually needed a dermis fat graft for an implant.

Both the MedPor Plus and MedPor Plus SST implant can be pegged for improved motility. In my opinion, the improved motility is most noticeable with the small saccadic ocular refixation movements. Surgeons have advocated pegging during the initial placement of the implant. However, my preference is to place a titanium peg only after the implant is fully vascularized. I usually confirm vascularization with a technetiumor MRI scan. Once the implant is fully vascularized, the risk of infection in “dead spaces” within the implant is decreased. Many surgeons recommend waiting at least 6 months after implant placement before pegging to ensure enough time for vascularization. However, in otherwise healthy individuals, I am comfortable pegging implants at 3 months after surgery, as the surgical technique and implants used may allow full vascularization by that time.

I have found pegging the porous polyethylene implants easier than the hydroxyapatite implants. The former can easily have pilot holes created with successively larger hypodermic needles before screwing in the peg sleeve. I often need to use a power drill to create pilot holes in the hydroxyapatite implants.

In practicality, only one out of 20 patients on average undergoes pegging. Patients are usually satisfied with their motility without the peg, and they do not want to increase the risk of adverse effects from pegging. Potential problems include pyogenic granuloma, chronic discharge, infection, clicking and discomfort.

For Your Information:

• John D. Ng, MD, FACS, can be reached at OHSU, Ophthalmic Facial Plastics Division, Casey Eye Institute, 3375 SW Terwilliger Blvd., Portland, OR 97239; 503-494-3010; fax: 503-494-3011; e-mail: NGJ@ohsu.edu. Dr. Ng has no financial interest in any products or companies mentioned. Dr. Ng has a small grant for a pilot study from Porex Inc. Porex Inc. supports Health for Humanity, a nonprofit charitable socioeconomic health development organization, of which Dr. Ng is a member.

References:

• Holck DEE, Dahl T, Foster JA, Ng JD. Rate of vascularization of porous polyethylene spherical orbital implants containing synthetic bone graft particulate determined by MRI. Poster presented at: American Academy of Ophthalmology annual meeting; October 2004; New Orleans.
• Holck DEE, Ng JD. Unpublished data.

CARLOS R. POU, MD, FACS
Evisceration with no pegs

	Carlos R. Pou

I always try to eviscerate when it is necessary to amputate an eye or its contents. I leave enucleation only for cases in which an eye has a malignant tumor, a patient has a severely phthisical eye or a pediatric patient has a microphthalmic eye. Even in cases in which there is an eye with low residual volume, I have successfully used a procedure in which I eviscerate the eye, and after releasing the front part of the sclera from the posterior part to accommodate a good size implant (ie, 18 mm), I cover whatever is left of the anterior scleral pocket opening with a sheeth of autogenous fascia lata overcoming a wound closure with tension.

Evisceration gives a well-centralized implant with no need to work on extraocular muscle reattachment, and it gives the best saccadic eye movement possible without the need to peg an implant. I find no need to peg implants when I perform an evisceration. I understand drilling a hole in an orbital implant brings an added risk of infection that in the case of porous implants (ie, MedPor or hydroxyapatite) is difficult to treat. Most of the time, these implants need to be removed; a procedure to remove these porous implants is difficult and potentiates the risk of losing the scleral pocket when an evisceration has been done. In my series of cases in which evisceration has been done with a traditional form or in the way described here, patients are satisfied with their prosthesis movement and do not seek peg implantation. Concerning sympathetic ophthalmia, retrospective series have shown this condition to be rare, and in some cases its occurrence, frequency and presentation are questioned after evisceration procedures.

For Your Information:

• Carlos R. Pou, MD, FACS, can be reached at the Instituto Cirugia Orbitofacial, Centro Internacioanal de Mercadeo, Guaynabo, Puerto Rico 00968; 787-781-4700; fax: 787-781-1590; e-mail: crpou@instituto-orbitofacial.com.

ALLEN M. PUTTERMAN, MD
MedPor implant, no pegs

	Allen M. Putterman

Due to the slight risk of sympathetic ophthalmia, I do not do eviscerations. In enucleations, I use a MedPor implant and attach the four recti muscles to the implant and cap the front of the implant with an autogenous fascia lata graft. I do not peg the implant because the ocular mobility is acceptable to my patients and me without the peg.

For Your Information:

• Allen M. Putterman, MD, SC, can be reached at 111 N. Wabash St., Suite 1722, Chicago, IL 60602; 312-372-2256; fax: 312-372-1762; e-mail: puttermanmd@hotmail.com.