Use of Platelet-Derived Growth Factor for Delayed Perineal Wound Healing in Patients with Inflammatory Bowel Disease: A Case Series

Abstract

  Abdominoperineal resection (APR) is the operative procedure of choice in patients with anorectal complications of inflammatory bowel disease (IBD) where a restorative proctocolectomy is either undesirable or impossible to perform.

The challenge in these patients is poor perineal wound healing. A retrospective chart review was conducted of 118 patients (average age 44 years, range 28–73) with intractable IBD who underwent APR to evaluate perineal wound healing outcomes. Forty-four (44) had Crohn’s disease (CD) and 74 had ulcerative colitis (UC). Three months after surgery, the wounds of 10 patients (six with CD and four with UC) remained unhealed with a standard protocol of sterile gauze dressings, sitz baths, and irrigation as needed. In these patients, daily topical application of a small amount of platelet-derived growth factor (rhPDGF) was added to the regimen of care. Six of the 10 unhealed wounds healed following rhPDGF application (average 80 days). The four patients whose wounds did not heal after 6 to 12 months had CD and underwent surgical revision followed by topical rhPDGF application. These wounds healed after an average of 107 days. The results of this case series confirm that delayed perineal wound healing is common following APR, especially in patients with CD, and may confirm previously reported observations that the effects of rhPDGF are most encouraging in small area defects that can be filled. Studies to evaluate the safety, efficacy, and effectiveness of this treatment modality are warranted.

Potential Conflicts of Interest: none disclosed

  Abdominoperineal resection (APR) is currently the operative procedure of choice for patients with anorectal complications of medically refractory inflammatory bowel disease (IBD) where a restorative proctocolectomy is either undesirable or impossible to perform.¹ The historical challenge in these patients has been poor perineal wound healing. Traditional topical care of these wounds involves saline irrigation, wet-to-dry dressings, vacuum-assisted closure, or historically leaving the wound to heal by secondary intention.² In 2005, Christian et al³ retrospectively reviewed perineal wound complications following APR in 153 patients and found that 50% of patients with IBD experienced a wound complication and the overall rate of perineal complications was 35%. Complications in IBD patients after APR have been attributed to malnutrition, chronic inflammation that prohibits closure of the pelvic dead space, or preexisting drainage and sinus tracts from the rectum, which results in inoculation of the pelvic space, impairing wound healing. ^4,5

  Over the last two decades, understanding of the wound repair process has improved. Recombinant human platelet-derived growth factor isoform-BB (rhPDGF), a growth factor approved by the US Food and Drug Administration (FDA) for use on diabetic neuropathic ulcers, has been shown to improve healing rates compared to standard wound care in a large, prospective, randomized phase III trial (n = 382). ⁶ Moreover, the literature^7-19 contains several reports regarding use of rhPDGF in other wound types such as head and neck wounds, periodontal disease, recurrent burn contractures, foot and ankle fusions, and shoulder surgery. The use of topical rhPDGF in patients with perineal wounds has not been reported. The purpose of this retrospective case series is to evaluate the effect of topical rhPDGF in the management of patients with IBD and delayed healing of the perineal wound after APR.

Methods

  A retrospective record review of all patients who underwent APR between January 1996 and May 2007 for treatment of IBD by a single surgeon at The Mount Sinai Hospital (New York, NY) was conducted. Data abstraction and review were performed by two reviewers. Data were entered into an Excel spreadsheet and data analysis was performed using SPSS© (Chicago, IL). Mean and median of age, duration of disease, and time to wound healing were calculated. Gender, type of IBD, procedure, and surgical interventions related to the perineal wound were recorded. Duration of rhPDGF application also was recorded. Numerical data were analyzed using Student’s t-test and categorical data were compared using chi-square. Statistical significance was defined as P <0.05.

  Surgical procedures. Records showed that all operations were performed using simultaneous abdominal and perineal teams. The perineal rectal dissection was performed in the inter-sphincteric plane using electrocautery. After the rectum was removed, the residual levator muscles were re-approximated with interrupted absorbable sutures. The ischiorectal fat and residual external sphincter muscles also were re-approximated in layers with absorbable sutures and the skin then was closed primarily with interrupted absorbable sutures. Closed suction pelvic drains were placed in the pelvis from above; perineal drains were not used.

  In the postoperative period, perineal wounds initially were treated daily with dry sterile gauze dressings. Perineal wounds that had drainage were treated daily with saline irrigation or sitz baths and wet-to-dry dressings. Conservative treatment with wound care was continued for at least 3 months. If the wound remained unhealed after 3 months, daily topical application of growth factor becaplermin gel 0.01%, 100 µg/g (Regranex®, Systagenix Wound Management, Quincy, MA) was prescribed and wound irrigation was discontinued. The growth factor treatment was applied daily into the open perineal wound by the patient according to the product package insert directions. A thin layer (1 mm to 2 mm) of ointment was applied using a finger or a cotton applicator; the wound then was covered with a dry gauze dressing. Patients were allowed to shower as needed.

  Written informed consent was not obtained because rhPDGF is FDA approved for use on diabetic ulcers and was used in this series as an offlabel adjunct to conservative wound care for patients with delayed healing of the perineal wound. Operative revisions were performed as needed if wounds remained unhealed 6 to 12 months after surgery.

Results

  The records of 118 patients who underwent APR were reviewed. Of those, 44 had Crohn’s disease (CD) and 74 had ulcerative colitis (UC). None of the patients had anal or rectal cancer and none had received radiation to the pelvis or perineum. In all patients with UC, the indication for surgery was intractability. The indication for surgery in all patients in the CD group was intractability with severe perianal disease.

  In the CD group, six out of 44 patients (14%) had unhealed wounds after 3 months; four out of 74 wounds in patients (5%) in the UC group did not heal during that time period (P <0.05); in total, six men and four women, average age 44 years (range 28–73) (see Table 1). Of these patients, six out of 10 healed following the addition of rhPDGF to their treatment regimen. Median time from APR to rhPDGF addition was 89 days (range 42–171 days) and the median time from rhPDGF addition to complete wound healing was 80 days (range 42–147) (see Figure 1). No adverse events related to rhPDGF occurred. The remaining four patients in this series with delayed perineal wound healing required operative interventions: one gracilis myocutaneous flap and three perineal wound revisions. All four patients requiring surgical revision had CD. After revision of the perineal wound, rhPDGF was applied and the wounds healed after a median of 107 days (range 98–118 days).

Discussion

  Traditional management of perineal wounds following APR consists of the application of damp-to-dry gauze dressings.⁵ Alternative methods, such as the use of negative pressure wound therapy (NPWT), have been tried but anatomic challenges involving the perineal wound often compromise the tight seal required for this therapy.^4,5 Wound failure after 6 months usually requires surgical intervention and placement of a well-vascularized, nonirradiated tissue flap to a large defect, or skin grafting to clean granulating wounds.⁵ Infection and precarious vascularity are not uncommon with the application of flaps and may lead to healing failure.⁵

  In the last decade, the use of advanced wound treatment modalities including tissue-engineered products, hyperbaric oxygen, NPWT, electrical stimulation, and recombinant growth factors has been explored.²⁰ Growth factors are the engines, or modulating factors, that drive wound healing. ²¹ Known endogenous sources of PDGF include the alpha granules of platelets, vascular endothelial cells, smooth muscle cells, fibroblasts, neutrophils, and epithelial cells. ²² In 1998, the FDA approved rhPDGF, a recombinant protein produced in the yeast Saccharomyces cervisiae, for topical treatment of nonischemic diabetic neuropathic ulcers. It is currently the only growth factor approved for clinical use.^21,23 In a review of the current literature,²¹ PDGF has been found to stimulate the production of glycosaminoglycans, proteoglycans, and collagenase; it acts as a vasoconstrictor and induces replication of fibroblasts and smooth muscle cells. Over the first several days after an injury, its release from platelets and endothelial cells allows for directed and sequential migration of neutrophils, macrophages, and fibroblasts into and around damaged tissue. ²¹ In a 1993 study²⁴ evaluating the molecular properties of five families of peptide growth factors, it was noted that stimulation by PDGF of the newly arrived cells at the wound site results in endogenous production of the growth factor and provisional extracellular matrix (ECM) synthesis, fibroblast proliferation, and eventually collagen production. This stimulation continues for 2 to 3 weeks, after which PDGF contributes to wound remodeling by helping orchestrate active collagen turnover and cross-linking.²⁴

  The failure of perineal wounds to readily heal after APR for IBD has stimulated considerable discussion and served as an impetus for the development of a number of operative approaches to deal with the problem.^25-27 It is not unusual for the perineal wound to take many months to heal completely. In a 2005 retrospective case series²⁸ of 160 patients who underwent APR, 35% had major wound complications; when analyzed for persons without previous pelvic irradiation, the complication rate was 19%. A retrospective series²⁹ of 112 patients undergoing proctectomy for Crohn’s colitis found that early healing (within 12 weeks) of perineal wounds occurred in only 63% of the patients. Healing was delayed by more than 1 year in 21 patients (19%) and in 10 patients (9%) the perineal wounds never healed. Watts et al³⁰ reported that 24.7% of 93 patients who underwent proctectomy for UC had an unhealed perineal wound for more than 6 months after surgery. Manjoney et al³¹ have reported similar discouraging statistics.

  Many authors consider IBD to be a poor prognostic indicator for healing. ³² After 8 months, Strahen et al³³ found that the infected perineal wounds of only 20% of patients with IBD healed. Perineal wound healing problems also have been reported to be more common when the primary diagnosis is CD — particularly, Crohn’s colitis.^25,34 In patients with rectal cancer, the primary healing success rate ranges from 80% to 90%, whereas in IBD, the healing is usually only ~50%.^35,36 In the current study, patients with CD had a nearly three times higher incidence of delayed perineal wound healing than patients with UC (14% versus 5%, P <0.05). Furthermore, all patients requiring operative intervention of the perineal wound after 6 months had CD. This difference may be due to chronic perineal pathology in patients with CD.

  In a literature review of nine studies with 1,315 patients, Del Pino and Abcarian³² examined the cause, prevention, and management of the most common perineal complications and their failure to heal secondary to abdominoperineal resections. In a series³⁷ of patients with adenocarcinoma, perineal wound complications (16.5%) ranked second to urologic problems (21%) in overall frequency. Patients with IBD demonstrated an even higher morbidity, ranging from 25% to 80%, with highest rates observed for Crohn's disease.^33,38,39

  Perineal complications have been attributed to both patient- and technique-related risk factors.³² The former include poor nutritional status, ^40-43 IBD, ⁴⁴ and prior steroid use.^29,30 The technique-related risk factors include poor bowel preparation, fecal contamination, and hemorrhage.^45-47 The effects of fecal contamination were even more pronounced when cancer patient outcomes were compared to those of patients with IBD (50% versus 35%). It also was noted that patients with Crohn’s colitis fared worse — 30% experienced a delay in wound healing longer than 3 months and 10% developed perineal sinuses.⁴⁷ Factors not found to be associated with perineal wound problems were age and gender. ³²

  Jalan et al⁴⁸ retrospectively reviewed outcomes of 115 patients with UC and found poor healing was significantly associated with the use of open packing, female gender, and surgery during the first attack of UC, as well as the presence of perineal sepsis; 55% of the patients needed longer than 6 months to heal and 20% never healed. Factors that did not have any detrimental effect included patient age, severity of colitis, prolonged disease, and the extent of colonic involvement. Although a history of corticosteroid use did not adversely affect outcome in this study, this finding may have been due to the small number of patients in their series. ^28,48 An increased incidence of poor perineal wound healing with steroid use has been reported by others.^36,41

  Growth factors control many of the key cellular activities involved in the normal tissue repair process. The underlying rationale for growth factor therapy is based on the theory that in problematic and chronic wounds, the production of one or many growth factors is suboptimal. Hypothesizing a positive effect on wound healing, investigators have examined the benefits of exogenous growth factor application for wound healing by adding more of a growth factor that is lacking or by giving the surrounding tissue the ability to upregulate its own growth factor production.^21,37

  A meta-analysis4 of five randomized trials of nonhealing lower extremity ulcers in patients with diabetes found an increased incidence of ulcer healing using growth factors compared with placebo (50% versus 36%, P <0.007) and a decreased time to healing (14 weeks versus 20 weeks, P = 0.01) In isolated cases, a variety of nondiabetic chronic wounds have healed after rhPDGF application, including a Mohs surgery site, a skin donor site, defects from acute fingertip trauma,⁸ periodontal osseus deficits,⁹ ulcers secondary to lymphedema, recurrent burn contractures,¹⁰ pyoderma gangrenosum,^11,12 and three separate cases of successful treatment of ulcers in irradiated wounds.^7,13,14 A prospective randomized trial⁵ comparing rhPDGF with a topical antibiotic applied daily after 4-mm punch biopsy in healthy volunteers showed a faster rate of healing with PDGF (71% of wounds healed by postoperative day 10 with rhPDGF compared to 28% with the antibiotic, P = 0.0005). Results of a prospective randomized trial7 of rhPDGF compared to surgilube after postoperative abdominal wound separation (N= 21) demonstrated a 35% reduction in healing time in the growth factor group (P = 0.05). Encouraging results from a case series¹⁶ of eight infants with ulcerated hemangiomas in which rhPDGF was applied to perineal sites also have been reported. The majority of wounds had been refractory to conventional therapy but all wounds healed within 21 days of growth factor treatment and no tumor growth was observed despite concerns of applying an angiogenic growth factor to a hemangioma.

  Not all studies have shown improvement of ulcer healing with rhPDGF; this has led to concerns over true treatment efficacy. The studies in which rhPDGF performs best seem to be those in which small areas can be filled — eg, pharyngocutaneous fistulae, 4-mm punch biopsy sites, and periodontal defects, and in studies where differences in the degree of healing were maximal early in the research (3 months).¹⁵ This is consistent with PDGF’s biological role early in wound healing, acting as a mitogen for mesenchymal cells, and may explain the positive results of this case series, where small but persistent perineal sinuses closed during exposure to rhPDGF.

  Although manipulating the healing process through wound supplementation with agents that are natural contributors to the healing process is an appealing concept, it has thus far been too costly to carry out the experimental studies required for FDA approval.49 Also, although the cost of rhPDGF is high (~$640 per 15-g vial) and the overall cost effectiveness has not been addressed in this context, computer modeling techniques and European center data suggest that adding rhPDGF to standard wound care for diabetic neuropathic ulcers may reduce overall cost of care.⁵⁰

Clinical and Study Limitations

  As with any growth factor, PDGF application is contraindicated at known sites of neoplasms⁵¹ because in vitro PDGF is a mitogen²² and stimulates angiogenesis.⁵¹ Three phenomena are particularly concerning for poor oncological outcome with application: APR is associated with approximately twice the risk of recurrence compared to low anterior resection for rectal cancer,^53,54 rare cutaneous metastasis has been reported after APR,⁵⁵ and blockade (not stimulation) of the PDGF receptor improves local chemotherapy delivery in a mouse model.⁵⁰ In June 2008, the FDA announced the addition of a boxed warning to the becaplermin label to address the increased risk of cancer mortality in patients who use three or more tubes of the product. The retrospective study⁵⁶ that prompted FDA action compared cancer incidence and mortality among 1,622 patients exposed to becaplermin with 2,809 otherwise similar patients who were not exposed. Among the exposed patients, no significant increase in the incidence of cancer was noted but a five-fold increased risk of cancer mortality was noted in patients exposed to at least three tubes of becaplermin. The adjusted rate ratio for overall cancer incidence among becaplermin-treated patients was 1.2 (95% confidence interval [CI], 0.7 – 1.9), and the corresponding death rate ratio was 1.8 (95% CI, 0.7 – 4.9). For patients who had been exposed to three or more tubes of the gel, the adjusted mortality rate ratio was 5.2 (95% CI, 1.6 – 17.6), with an actual incidence rate of 3.9 cancer deaths per 1,000 person-years of treatment. For this reason, the authors of the current study did not use becaplermin in patients undergoing APR for cancer.   The limitations of this case series are those inherent to retrospective studies and the absence of a control arm. Although the observed results are encouraging, the safety, efficacy, and effectiveness of rhPDGF in the care of perineal wounds remains to be established.

Conclusion

  Delayed healing of the perineal wound in patients with IBD undergoing APR remains a difficult problem and care must be individualized. The results of this study are promising — 60% of perineal wounds with delayed healing closed with the addition of topical growth factor. The results observed in the current case series suggest that topical rhPDGF may facilitate wound healing in patients who do not have a malignancy and whose perineal wound does not respond to standard care.

Dr. Kurtz is a Clinical Fellow in Surgery, Urology, Massachusetts General Hospital and Harvard Medical School, Boston, MA. Dr. Svensson is a resident, Department of General Surgery, Allegheny General Hospital, Pittsburgh, PA. Dr. Heimann is Professor of Surgery, Mount Sinai School of Medicine, New York, NY. Please address correspondence to: Tomas M. Heimann, MD, FACS, Department of Surgery, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1259, New York, NY 10029; email: tomas.heimann@mssm.edu.

1. Murrell ZA, Dixon MR, Vargas H, Arnell TD, Kumar R, Stamos MJ. Contemporary indications for and early outcomes of abdominoperineal resection. Am Surg. 2005;71(10):837–40.

2. El-Gazzaz G, Kiran RP, Lavery I. Wound complications in rectal cancer patients undergoing primary closure of the perineal wound after abdominoperineal resection. Dis Colon Rectum. 2009;52(12):1962–1966.

3. Christian CK, Kwaan MR, Betensky RA, Breen EM, Zinner MJ, Bleday R. Risk factors for perineal wound complications following abdominoperineal resection. Dis Colon Rectum. 2005;48(1):43–48.

4. Opelka FG. Unhealed perineal wound. Clin Colon Rectal Surg. 2001;14:65–68.

5. Wiatrek RL, Thomas JS, Papaconstantinou H. Perineal wound complications after abdominoperineal resection. Colon Rectal Surg. 2008;21(1):76–86.

6. Wieman TJ, Smiell JM, Su Y. Efficacy and safety of a topical gel formulation of recombinant human platelet-derived growth factor-BB (becaplermin) in patients with chronic neuropathic diabetic ulcers. A phase III randomized placebo-controlled double-blind study. Diabetes Care. 1998;21(5):822–827.

7. Hom DB, Manivel JC. Promoting healing with recombinant human platelet-derived growth factor-BB in a previously irradiated problem wound. Laryngoscope. 2003;113(9):1566–1571.

8. Harrison-Balestra C, Eaglstein WH, Falabela AF, Kirsner RS. Recombinant human platelet-derived growth factor for refractory nondiabetic ulcers: a retrospective series. Dermatol Surg. 2002;28(8):755–759.

9. Nevins M, Giannobile WV, McGuire MK, et al. Platelet-derived growth factor stimulates bone fill and rate of attachment level gain: results of a large multicenter randomized controlled trial. J Periodontol. 2005;76(12):2205–2215.

10. Freedman BM, Oplinger EH. The use of becaplermin as a surgical alternative in difficult to manage wounds. WOUNDS. 2002;15(4):79–84.

11. Braun-Falco M, Stock K, Ring J, Hein R. Topical platelet-derived growth factor accelerates healing of myelodysplastic syndrome-associated pyoderma gangrenosum. Br J Dermatol. 2002;147(4):829–831.

12. Freedman BM, Oplinger EH. Use of becaplermin in progressive limb-threatening pyoderma gangrenosum. Adv Skin Wound Care. 2002;15(4):180–182.

13. Wollina U, Liebold K, Konrad H. Treatment of chronic radiation ulcers with recombinant platelet-derived growth factor and a hydrophilic copolymer membrane. J Eur Acad Dermatol Venereol. 2001;15(5):455–457.

14. Mast B. Complementary effects of becaplermin gel and HBO in an irradiated wound. Wound Repair Regen. 2002;10:A37.

15. Cohen MA, Eaglstein WH. Recombinant human platelet-derived growth factor gel speeds healing of acute full-thickness punch biopsy wounds. J Am Acad Dermatol. 2001;45(6):857–862.

16. Metz BJ, Rubenstein MC, Levy ML, Metry DW. Response of ulcerated perineal hemangiomas of infancy to becaplermin gel, a recombinant human platelet-derived growth factor. Arch Dermatol. 2004;140(7):867–870.

17. Shackelford DP, Fackler E, Hoffman MK, Atkinson S. Use of topical recombinant human platelet-derived growth factor BB in abdominal wound separation. Am J Obstet Gynecol. 2002;186(4):701–704.

18. Uggen C, Dines J, McGarry M, Grande D, Lee T, Limpisvasti O. The effect of recombinant human platelet-derived growth factor BB-coated sutures on rotator cuff healing in a sheep model. Arthroscopy. 2010;26(11):1456–1462.

19. DiGiovanni CW, Petricek JM. The evolution of rhPDGF-BB in musculoskeletal repair and its role in foot and ankle fusin surgery. Foot Ankle Clin. 2010;15(4):621–640.

20. Hollister C, Li VW. Using angiogenesis in chronic wound care with becaplermin and oxidized regenerated cellulose/collagen. Nurs Clin North Am. 2007;42(3):457–465,vii.

21. Cross KJ, Mustoe TA. Growth factors in wound healing. Surg Clin North Am. 2003;83(3):531–545, vi.

22. Miller MC, Nanchahal J. Advances in the modulation of cutaneous wound healing and scarring. BioDrugs. 2005;19(6):363–381.

23. Pierce GF, Mustoe TA, Altrock BW, Deuel TF, Thomason A. Role of platelet-derived growth factor in wound healing. J Cell Biochem. 1991;45(4):319–326.

24. Bennet NT, Schultz GS. Growth factors and wound healing: biochemical properties of growth factors and their receptors. Am J Surg. 1993;165(6):728–737.

25. Corman MI, Veidenheimer MC, Coller JA, Ross VH. Perineal wound healing after proctectomy for inflammatory bowel disease. Dis Colon Rectum. 1978;21(3):155–159.

26. Ferrari BT, DenBesten L. The prevention and treatment of the persistent perineal sinus. World J Surg. 2006;4(2):167–171.

27. Yamamoto T, Bain IM, Allan RN, Keighley MR. Persistent perineal sinus after proctocolectomy for Crohn's disease. Dis Colon Rectum. 1999;42(1): 96–101.

28. Bullard KM, Trudel JL, Baxter NN, Rothenberger DA. Primary perineal wound closure after preoperative radiotherapy and abdominoperineal resection has a high incidence of wound failure. Dis Colon Rectum. 2005;48(3):438–443.

29. Scammell BE, Keighley MRB. Delayed perineal wound healing after proctectomy for Crohn’s colitis. Br J Surg. 2005;73(2):150–152.

30. Watts JM, DeDombal FT, Goligher JC. Long term complications and prognosis following major surgery for ulcerative colitis. Br J Surg. 1966,53(12):1014–1023.

31. Manjoney DL, Koplewitz MJ, Abrams JS. Factors influencing perineal wound healing after proctectomy. Am J Surg. 1983;145(1):183–189.

32. Del Pino A, Abcarian H. The difficult perineal wound. Surg Clin North Am. 1997;7(1):155–174.

33. Strahan J, Wilson W, McMechan EW. A review of surgically treated ulcerative colitis. Ir J Med Sci. 1967;6(494):83.

34. Ritchie JK. Ileostomy and excisional surgery for chronic inflammatory disease of the colon: a survey of one hospital region. Gut. 1971;12(7):528–540.

35. Baudot P, Keighley MR, Alexander-Williams J. Perineal wound healing after proctectomy for carcinoma and inflammatory bowel disease. Br J Surg. 1980;67(4):275–276.

36. Lubbers EJ. Healing of the perineal wound after proctectomy for nonmalignant conditions. Dis Colon Rectum. 1982;25(4):351–357.

37. Rothenberger DA, Wong WD. Abdominoperineal resection for adenocarcinoma of the low rectum. World J Surg. 1992;16(3):478–485.

38. Berry AR, De Campos R, Lee EC. Perineal and pelvic morbidity following perimuscular excision of the rectum for inflammatory bowel disease. Br J Surg. 1986;73(8):675–677.

39. Broeders IA, Poen H, Ottow RT, van Vroonhoven TJ. Proctocolectomy with permanent ileostomy versus restorative proctocolectomy in ulcerative colitis; the past as background for the present. Ned Tijdschr Geneeskd. 1991;135(30):1354–1358.

40. Fullana F, Grande L, Fernandez-Llamazares J, Gonzalez-Mestre V, Salva JA. Skin prolylhydroxylase activity and wound healing. Eur Surg Res. 1993;25(6):370–375.

41. Mainous MR, Ditch EA. Nutrition and infection. Surg Clin North Am. 1994;74(3):659–676.

42. Meyer NA, Muller MJ, Herndon DN. Nutrient support of the healing wound. New Horiz. 1994;2(2):202–214.

43. Telfer NR, Moy RL. Drug and nutrient aspects of wound healing. Dermatol Clin. 1993;11(4):729–737.

44. Goligher JD, Duthie HL, Nixon HH. Surgery of the Anus, Rectum and Colon, 5th edition. London, UK: Balliere-Tindall;1984:906.

45. Baum ML, Anish DS, Chalmers TC, Sacks HS, Smith H Jr, Fagerstrom RM. A survey of clinical trials of antibiotic prophylaxis in colon surgery: evidence against further use of no-treatment controls. N Engl J Med. 1981;305(14):795–799.

46. Marks CG, Leighton M, Ritchie JK, Hawley PR. Primary suture of the perineal wound following rectal excision for adenocarcinoma. Br J Surg. 1976;63(4):322–326.

47. Broader JH, Masselink BA, Oates GD, Alexander-Williams J. Management of the pelvic space after proctectomy. Br J Surg. 1974;61(2):94–97.

48. Jalan KN, Smith AN, Ruckley CV, Falconer CW, Small WP, Prescott RJ. Perineal wound healing in ulcerative colitis. Br J Surg. 1969;56(10):749–753.

49. Leahy PJ, Lawrence WT. Biologic enhancement of wound healing. Clin Plast Surg. 2007;4(4):659–671.

50. Ghatnekar O, Persson U, Willis M, Odegaard K. Cost effectiveness of Becaplermin in the treatment of diabetic foot ulcers in four European countries. Pharmacoeconomics. 2001;19(7):767–778.

51. Becaplermin [Regranex®] gel 0.01% [package insert]. Raritan, New Jersey: Ortho-McNeil Pharmaceutical Inc; 1998.

52. Alvarez RH, Kantarjian HM, Cortes JE. Biology of platelet-derived growth factor and its involvement in disease. Mayo Clin Proc. 2006;81(9):1241–1257.

53. Krivokapic Z, Barisic G, Markovic V, et al. First thousand rectal cancer cases — local recurrence and survival. Acta Chir Iugosl. 2004;51(2):133–137.

54. Law WL, Chu KW. Abdominoperineal resection is associated with poor oncological outcome. Br J Surg. 2004;91(11):1493–1499.

55. Tan KY, Ho KS, Lai JH, et al. Cutaneous and subcutaneous metastases of adenocarcinoma of the colon and rectum. Ann Acad Med Singapore. 2006;35(8):585–587.

56. Regranex (becaplermin) gel 0.01% [prescribing information]. Raritan, N.J.: Ortho-McNeil Pharmaceutical, Inc.; 2005. Available at: www.regranex.com/prescribinginfo.php. Accessed January 24, 2009.