Orbital floor repair with lyophilized porcine dermis Keith Webster, B.D.S., London, England JOINT DEPARTMENTS OF ORAL AND MAXILLOFACIAL SURGERY, EASTMAN DENTAL HOSPITAL, UNIVERSITY COLLEGE HOSPITAL. LONDON Various implants have been used to repair defects in orbital walls. Few are fully biocompatible. The indications for repair of a defect of the orbital iioor are reviewed, and the suitability in selected cases of placement of lyophilized porcine dermis (xenograft) is discussed. (OR&L SURC ORAL MED ORAL PATHOL 1988;65:161-4) S urgical intervention in fractures of the orbital floor, be they isolated, part of fractures of the zygomatic complex, or in Le Fort II and III frac- tures, is controversial. In cases of fractures of the orbital floor associated with fractures of the facial skeleton, surgical exploration is rarely indicated as a primary procedure. Banks’ and Van Herk and Hovinga2 conclude that placement of an implant on the orbital floor is unnecessary in a recent fracture and is useful only in the management of old untreated fractures. In isolated fractures of the orbital floor the placement of an implant on the orbital floor will not, with certainty, prevent enoph- thalmos or residual diplopia.3 Lyle4 has shown that diplopia may persist even after ocular level is restored and adhesions between the globe and the orbital floor are eliminated. INDICATIONS Dulley and Fellss suggest that the indications for surgical intervention are: diplopia not resolving sig- nificantly in the early days after injury; a fracture with a large herniation of tissue into the antrum; incarceration of tissue in the fracture with resulting globe retraction and increased applanation tension on attempted upward gaze; and enophthalmos great- er than 3 mm. The opinion of other authors differs. McCof states that exploration should be performed in any fracture in which orbital involvement is suspected. de Man,’ in a series of 163 patients, found no indication for early diagnostic exploration of the fractured orbital floor if there were no clinical or radiographic signs of fracture within 14 days of the accident. Great emphasis is placed on the state of the periorbita. The removal of the whole orbital floor with preservation of the pcriorbita does not produce enophthalmos or diplopia. Janakarajah and Sukumaran* found that only 11% of orbital fractures required implants to provide support along with fracture reduction. Converse and Smith9 advocated exploration of the floor on clinical grounds alone, although if there is doubt a delay of 24 hours is advised. Kroll and Wolper*” suggested that radiographic evidence of a blow-out fracture with a normal clinical picture does not of itself dictate the need for surgical intervention. METHODS AND MATERIAL When intervention is decided upon, the principal treatment is to free incarcerated tissue from the orbital floor and so return the continuity of the periorbita and the eyeball to its normal position. Vertical limitation of eyeball motility (a positive forced duction test), with or without enophthalmos, is usually due to fat herniation. The extraocular musculature arises from the anulus of Zinn, a fibrous double-pierced tendinous funnel at the orbital apex. Therefore restriction of the inferior extraocular mus- cles is usually due to adhesions, edema, and fibrosis between the periorbita and the disrupted periosteum of the orbital floor. The surgical approach to the orbital floor is also controversial. Rowe” suggested that supporting the orbital floor from below is indicated where comminu- tion has occurred and fragments are still attached to the periosteum, or where there has been a trapdoor and the fragments can be repositioned from below. 161
Transcript
Orbital floor repair with lyophilized porcine dermis Keith Webster, B.D.S., London, England
JOINT DEPARTMENTS OF ORAL AND MAXILLOFACIAL SURGERY, EASTMAN DENTAL HOSPITAL, UNIVERSITY COLLEGE HOSPITAL. LONDON
Various implants have been used to repair defects in orbital walls. Few are fully biocompatible. The indications for repair of a defect of the orbital iioor are reviewed, and the suitability in selected cases of placement of lyophilized porcine dermis (xenograft) is discussed. (OR&L SURC ORAL MED ORAL PATHOL 1988;65:161-4)
S urgical intervention in fractures of the orbital floor, be they isolated, part of fractures of the zygomatic complex, or in Le Fort II and III frac- tures, is controversial. In cases of fractures of the orbital floor associated with fractures of the facial skeleton, surgical exploration is rarely indicated as a primary procedure. Banks’ and Van Herk and Hovinga2 conclude that placement of an implant on the orbital floor is unnecessary in a recent fracture and is useful only in the management of old untreated fractures. In isolated fractures of the orbital floor the placement of an implant on the orbital floor will not, with certainty, prevent enoph- thalmos or residual diplopia.3 Lyle4 has shown that diplopia may persist even after ocular level is restored and adhesions between the globe and the orbital floor are eliminated.
INDICATIONS
Dulley and Fellss suggest that the indications for surgical intervention are: diplopia not resolving sig- nificantly in the early days after injury; a fracture with a large herniation of tissue into the antrum; incarceration of tissue in the fracture with resulting globe retraction and increased applanation tension on attempted upward gaze; and enophthalmos great- er than 3 mm.
The opinion of other authors differs. McCof states that exploration should be performed in any fracture in which orbital involvement is suspected.
de Man,’ in a series of 163 patients, found no indication for early diagnostic exploration of the fractured orbital floor if there were no clinical or radiographic signs of fracture within 14 days of the
accident. Great emphasis is placed on the state of the periorbita. The removal of the whole orbital floor with preservation of the pcriorbita does not produce enophthalmos or diplopia.
Janakarajah and Sukumaran* found that only 11% of orbital fractures required implants to provide support along with fracture reduction. Converse and Smith9 advocated exploration of the floor on clinical grounds alone, although if there is doubt a delay of 24 hours is advised. Kroll and Wolper*” suggested that radiographic evidence of a blow-out fracture with a normal clinical picture does not of itself dictate the need for surgical intervention.
METHODS AND MATERIAL
When intervention is decided upon, the principal treatment is to free incarcerated tissue from the orbital floor and so return the continuity of the periorbita and the eyeball to its normal position. Vertical limitation of eyeball motility (a positive forced duction test), with or without enophthalmos, is usually due to fat herniation. The extraocular musculature arises from the anulus of Zinn, a fibrous double-pierced tendinous funnel at the orbital apex. Therefore restriction of the inferior extraocular mus- cles is usually due to adhesions, edema, and fibrosis between the periorbita and the disrupted periosteum of the orbital floor.
The surgical approach to the orbital floor is also controversial. Rowe” suggested that supporting the orbital floor from below is indicated where comminu- tion has occurred and fragments are still attached to the periosteum, or where there has been a trapdoor and the fragments can be repositioned from below.
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162 Webster Oral Surg February 1988
Fig. 1. The 9800 orbital CT scan shows discontinuity in inferior orbital wall (arrows.
However, penetrating injuries to the globe can occur in this method if the orbital floor is not fully visualized.
The insertion of a graft to restore a defect is deemed essential when a portion of the orbital floor has been lost, the periorbita is disrupted, and use of the antral approach will provide only a temporary support. Grafting is not without complications. Gold- man and Hessburg’* list the following complications:
persistent enophthalmos, depression of the globe, persistent diplopia on upward gaze, extrusion of the implant, infection and chronic formation of fist&as, retraction of lower eyelid, and eetropion, intraorbital hemorrhage, lymphedema of the lower eyelid, rejec- tion of the implant, dacryocystitis, and blindness.
Graft materials are classified as follows: auto- grafts, allografts, xenografts, and alloplasts.
Autografts
Rowe and Killey13 advocated rotating a fragment of the orbital floor to bridge the defect. Kayel* used the contralateral antral wall, whereas Converse and SmithIs advocated use of the perpendicular plate of the ethmoid. Longacre and KahP thought that iliac grafts showed considerable absorption and that split rib grafts were better tolerated. Hotte3 used cancel- lous bone from the contralateral mastoid.
Allografts
Lyophilized human dura has been used for repair of the orbital floor.17 In the experimental work of Iannetti and D’Arco18 human dura was transplanted into the peritoneum of rabbits (thus constituting a xenograft). These authors showed that the dura was absorbed and replaced by fibrous tissue, leaving evidence of a nonspecific chronic inflammatory response. Fragments removed from the area of a previous implant showed no signs of chronic inllam- mation, and it was difficult to distinguish then trans- plant from host tissue. No rejection of the implant occurred in a series of 52.
Volume 65 Orbital floor repair with lyophilized porcine dermis 163 Number 2
Alloplasts
According to Conley,19 alloplasts date back to 1565, when Petronius repaired palatal defects with gold plates; Vitallium and silicone rubber are in- cluded in this group.
Xenogratts
The use of heterogenous dura as a xenograft is well documented, and in the dental field porcine dermal collagen (Zenoderm, Ethicon Ltd., Edin- burgh, Scotland) has been used successfully in the closure of oroantral fistulas and as a dressing for denuded mucous membranes. Lyophilized porcine dermis (Zenoderm) is a xenograft derived from porcine corium, which is treated by proteolytic enzyme digestion to remove noncollagenous elements and with glutaraldehyde immersion to retard absorp- tion as well as to reduce antigenicity by cross-linking of the collagen molecules. The collagen matrix is lyophilized and sterilized by gamma radiation before it is used. The finished product is reconstituted in 0.9% saline.
As to tissue compatibility, biopsies of inguinal hernia repairs were investigated.” Macroscopically the implant was replaCed by fibrous-like tissue. Histologically no acute inflammatory response was noted. Macrophages were found in close proximity to implant fragments, and the histologic changes indi- cated absorption and replacement by host fibrous tissue. Dermal testing of the host showed no immedi- ate or delayed hypersensitivity. The material, having been in place for 3 to 4 months, showed histologic features similar to those noted in human collagen implants in place up to 1 year.21 However, demarca- tion between implant and host was indistinct, sug- gesting a greater degree of incorporation than had previously been observed.
CASE REPORT
A 64-year-old woman was seen in the emergency depart- ment with a complaint of pain and swelling around her left eye subsequent to a fall. Her medical history revealed that she had had a T2 NO MO breast adenocarcinoma removed by local excision a year earlier.
On examination there was a marked left periorbital ecchymosis and associated subconjunctival hemorrhage. Paresthesia in the distribution of the infraorbital nerve was noted. Plain radiographs showed no discontinuity of the orbital rim, but a hanging drop appearance on the occipi- tomental film was noted. An ophthalmic examination revealed limitation in action of the inferior rectus muscle along with a slight lateral divergence of vision at 30 cm. An orbital computed tomography (CT) scan (Fig. 1) showed the orbital floor defect with herniation of fat into the
antrum. Air within the orbit is well demarcated, but no evidence of retrobulbar hematoma was present. The diplo- pia remained unresolved, and at 8 days the orbital floor was explored via a subciliary approach. A large blow-out fracture of the floor was found with herniated orbital contents; the septum was also disrupted. The orbital contents were freed, and a Zenoderm patch was sutured to the periosteum to bridge the dehiscence.
Postoperatively a mild ectropion developed but then resolved, as did the diplopia. The extraocular movements, as demonstrated by Hess charts, were normal. A postoper- ative CT scan showed a defect filled with a substance of a density similar to that of muscle, whereas previously fat herniation had been present (Fig. 2).
DISCUSSION
In this operation the objective was to support the disrupted orbital septum to prevent orbital contents from being incarcerated in the defect, rather than to reconstruct the orbital wall. The material used had the salient features of flexibility and pliability, which allowed it to be fixed in position while still supporting the overlying orbital tissues during the period of repair. The biocompatibility of the material is impor- tant, and this technique avoids the necessity of a second operative site.
The postoperative CT scan showed that the xeno- graft had been successful in bridging the defect, and no herniation of orbital contents was present. Unlike silicone rubber and other nonbiocompatible im- plants, Zenoderm material has allowed natural fibrous repair tissue to bridge the defect. The scan does not show reconstitution of the bony orbital floor, but the organization of the resulting fibrous tissue may be expected to include osteogenesis.
In the case of alloplasts such as silicone rubber, any bone regeneration will occur outside the bounds of the graft and thus make the material redundant. Autografts will induce new bone formation but involve morbidity to the donor site.
In terms of mechanical support the acute inflam- matory reaction that occurs around antral packs may not be an ideal environment for uncomplicated repair.
Thus the lyophilized porcine dermis (Zenoderm) is flexible and biointegrated and shows good adapta- tion to the defect. It is not to be used in reconstruc- tion of the orbital floor but merely to support the repair process in a disrupted orbital septum. There- fore this method should be restricted to small defects where clinical features suggest intervention.
I would like to thank Professor M. Harris, Dr. N. F. Ferraro, and Mr. P. Banks for their comments and Dr. B. Kendall, Consultant Radiologist to the National Hospital
164 Webster
for Nervous Diseases, for his expert interpretation of the CT scans.
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Keith Webster, B.D.S. 43 Hawarden Hill Dollis Hill Lane London, NW2 7BR United Kingdom
