The Murphy Modification to Offload Ulceration Secondary to Digital Deformity

Orthopaedic and Rheumatological Institute, Cleveland Clinic

The Murphy Modification Jennifer Gerres DPM, PGY-1

Introduction

✤ Lifetime ulcer incidence: 25%

✤ Mortality post amputation: 13 to 40% at 1 year

✤ Quality of Life

✤ Economic Implications

✤ 1 in 10 health care dollars

The lifetime incidence of ulceration may be as high as 25%

Indeed, and the mortality rate post amputation at one year is between 13 to 40% and only increases

This can and does place a strain upon the quality of life; not only the physical health, but also mental health. How one perceives oneself. Social, family—can be a burden, economic.

American Diabetes association has a calculator, called the Diabetes Cost Calculator, which is readily available on its site. This calculator can estimate state by state the exact economic burden diabetes plays.

The statistics are from 2006, but still relevant. 2006 is estimated at $5,926,000,000 (FIVE BILLION, NINE HUNDRED AND TWENTY-SIX MILLION) DOLLARS IN THE STATE OF OHIO

MEDICAL COSTS OF $3,857,000,000 (THREE BILLION EIGHT HUNDRED AND FIFTY-SEVEN MILLION) DOLLARS

Lost productivity valued at $2,069,000,000 (TWO BILLION AND SIXTY-NINE MILLION) DOLLARS

Combined 10th, 11th, and 13th congressional districts: 1,163,600,000 (ONE BILLION ONE HUNDRED AND SIXTY-THREE MILLION SIX HUNDRED THOUSAND DOLLARS)

Objectives

✤ Elevated plantar pressures in the presence of diabetic peripheral neuropathy increases ulceration risk

✤ Numerous conservative modalities have been employed to minimize the risk

✤ Retrospective case series of 4 patients

✤ A novel approach to offload the distal digit with an extrinsic addition to a custom molded insole (CMI)

Ulcerations in the diabetic foot are caused by a number of contributing factors, most significant being peripheral neuropathy.

The inability to sense and to adjust to noxious stimuli can lead to tissue strain and eventual skin breakdown over areas of high localized stress.

We present a retrospective case series of 4 patients with DM with digital plantar ulcerations in the presence of mallet toe deformity

These patients underwent and extrinsic modification to a custom molded insole without surgical correction

MethodsConsists of two layers of 1/8” cork and 1/8” PPT glued together

The extrinsic offloading device consists of two layers of 1/8” cork and 1/8” PPT glued together

The materials used depended on the severity of the callus or ulceration--the more severe, the more memory material required.

Steps in making this modification: First, the callus or ulceration was traced upon the under-base of the insole

Next, with the 1/8” PPT, a U-shape was created around the affected toe with the material extended proximally to the metatarsal head.

The length and width should be tapered, as not to affect the other toes or metatarsal heads

The 1/8” cork was added inferior to the PPT in the same manner.

Case 1

✤ 76yo NIDDM male

✤ June 2009

✤ Pre-ulcerative lesion

✤ February 2010

✤ Extrinsic modification to CMI

In June of 2009, a 76yo NIDDM male presented for preventative foot care. The patient’s past medical history included a HgbA1c of 8, tobacco history of 1ppd for 40 years, peripheral neuropathy, venous insufficiency, and previous non-healing ulceration with chronic osteomyelitis to the first metatarsophalangeal joint of the right foot.

His past surgical history included a recent partial first ray resection and vascular intervention to the right lower extremity.

Upon physical exam, the patient presented with the pre-ulcerative lesion to the distal tip of the right 2nd toe, secondary to a rigid mallet toe. The hyperkeratotic tissue was debrided and revealed an area of underlying central hemorrhage. The patient was fitted with a silicone digital cap and reappointed for one month.

Again, on physical exam the pre-ulcerative lesion with central hemorrhaging was observed and the hyperkeratotic tissue was debrided.

Once again, the patient was fitted with a silicone digital cap and a crest pad was applied to the toe.

Over the course of sixth months, the patient returned for debridement of the pre-ulcerative lesion to the right second toe.

In February of 2010, offloading of the distal aspect of the right second toe was performed through the use of an extrinsic modification to the CMI.

After the modification was made to the plantar aspect of the right CMI, the patient was reappointed for one month.

Case 1

✤ At one month post-modification

✤ Decrease in hyperkeratotic tissue

✤ At six months post-modification

✤ Area of pre-ulceration remained healed

At one month, when this photograph was taken, a decrease in the amount of hyperkeratotic tissue was observed with minimal debridement necessary.

At two months post-modification, no hyperkeratotic tissue was detected.

At six months post-modification, the area of the pre-ulceration remained healed and no new ulcerations upon physical examination.

Case 2

✤ 66yo IDDM male

✤ August 2010

✤ Recurrent ulceration

✤ Extra-depth shoes, CMIs, local wound care

✤ Extrinsic modification

In early August of 2010, a 66 year-old IDDM male presented for follow up of a recurrent ulceration to the distal tip of the left 3rd toe. The patient’s past medical history included a HgbA1C of 8.8, PAD, CAD, CHF, and morbid obesity. Past pedal surgical history included a partial fifth ray resection of the right foot, partial first and second ray resection of the left foot.

Over the previous year, treatment consisted of extra depth shoes, CMIs and local wound care that included debridement.

Upon physical exam, a full-thickness ulceration was documented to the plantar left 3rd toe secondary to a rigid mallet toe deformity. At this time, the wound was debrided of all hyperkeratotic tissue and the extrinsic modification was made to offload the third digit.

Case 2

✤ One month post-modification

✤ Decreased in size and thickness

Case 3

✤ 57yo IDDM male

✤ August 2010

✤ Blisters to 2nd and 3rd toes

✤ CMI extrinsic modification

In mid August 2010, a 57year-old IDDM male presented to the office with the complaint of blisters to the distal 2nd and 3rd digits, right foot.

Pertinent past medical history included peripheral neuropathy, cataract, and four years prior, a previously resolved ulceration to the right second digit.

Upon examination of the right foot, DIPJ contractures were noted as well as non-infected superficial ulcerations to the distal 2nd and 3rd toes. Dry sterile dressings were applied and the patient’s CMIs were modified to offload the contracted DIPJ of the 2nd and 3rd toes.

The patient was reappointed for three weeks, and upon examination, the superficial ulcerations were fully healed.

Case 3

✤ Three weeks post-modification

✤ Fully healed

Case 4

✤ 63yo NIDDM female

✤ October 2010

✤ Ulcer to 2nd toe

✤ CMI modification

In early October 2010, a 63 year old NIDDM female presented to the office with the complaint of a wound to the distal toe after she trimmed her own toe nails.

Pertinent past medical history included peripheral neuropathy, hypertension, hyperlipidemia, and previous amputation of the 3rd toe of the right foot.

Upon examination of the right foot, DIPJ contractures were noted as well as non-infected superficial ulceration to the distal 2nd toes. Dry sterile dressings were applied and the patient’s CMIs were modified to offload the contracted DIPJ of the 2nd toe.

Case 4

✤ Three weeks post-modification

✤ Fully healed

The patient was reappointed for three weeks, and upon examination, the superficial ulcerations were fully healed.

Discussion

Discussion

✤ Excessive plantar pressure leads to tissue strain and ulceration

✤ Limited joint mobility

✤ Changes shock absorption and load of the foot

✤ Structural deformities

✤ Callus acts as noxious stimulus

Excessive plantar pressures can lead to tissue strain in the neuropathic foot and can lead to ulceration. Although no set threshold of plantar pressures that would lead to ulceration, it has been suggested that as peak plantar pressures increase, the likelihood of ulceration increases as well. Neuropathic ulcers develop at areas on the sole of the foot exposed to moderate to high repetitive stress. Over an extended period of time, this repetitive injury leads to inflammation, local ischemia, necrosis, and ulceration. Simply, when any material, be it steel, bone, or skin, when placed under increased stress it will fatigue and fail.

Bus, Lott, and Boulton demonstrated that limited joint mobility and foot deformity are factors that contribute to heightened pressure and risk for ulceration. This was further reinforced by Mueller and Zimny’s respective papers, that a decrease in joint mobility changes the dynamics in shock absorption and load placed upon the foot. Indeed, ankle and first MPJ mobility are reduced in the patient with diabetic neuropathy, which can lead to increased mechanical pressure on the forefoot escalating the risk of ulceration. Furthermore, deformities such as claw toes or mallet toes, predispose the foot to callus formation and transfer of load in the forefoot.The deformity in combination with limited joint mobility amplifies the likelihood of callus formation and subsequent ulceration. Indeed, ulcerations to the neuropathicfoot often occur in areas of high stress and excessive callus formation. In works by Bus, Pitei, and Young, the calluses, themselves, may act as a repetitive, noxious foreign stimulus and require routine debridement.

In this respect, our modification offloads those areas of increased mechanical stress and lessen; the callus buildup.

Conclusion

✤ CMI can reduce plantar pressures

✤ Footwear + CMIs = minimize pressure to the soft tissue structures

✤ Ashry et al. J Foot Ankle Surg, 1997:

✤ 5 to 15% reduction in peak plantar pressures of lesser toes

✤ Demonstrated a simple, novel and reproducible modification

Indeed, custom molded insoles can reduce plantar pressure and can result in ulcer healing; although, the literature in regards to effectiveness is insufficient at best. The purpose of a CMI is to redistribute plantar pressure and weightbearing forces along the insole.

In combination with footwear, CMIs can minimize pressure to the soft tissue structures

Ashry and colleagues demonstrated a reduction in peak plantar pressures of the lesser toes by 5 to 15% in those treated with an insole compared to only those treated with accommodative footwear.

Presented today, is a simple, novel and reproducible modification for diabetic insoles to offload pressure from the distal phalanges and offer a limb preserving treatment option that is less invasive than surgical correction.

References

✤ Armstrong DG, Peters EJG, Athanasiou KA, Lavery LA. Is there a critical level of plantar foot pressure to identify patients at risk for neuropathic foot ulceration? J Foot Ankle Surg. 1998;37(4):303-07.

✤ Ashry HR, Lavery LA, Murdoch DP, Frolich M, Lavery DC. Effectiveness of diabetic insoles to reduce foot pressures. J Foot Ankle Surg. 1997;36(4):268-71.

✤ Burns J, Wegener C, Begg L, Vicaretti M, Fletcher J. Randomized trial of custom orthoses and footwear on foot pain and plantar pressure in diabetic peripheralarterial disease. Diabet Med. 2009;26(9):893-9.

✤ Bus SA, Maas M, de Lange A, Michels RP, Levi M. Elevated plantar pressures in neuropathic diabetic patients with claw/hammer toe deformity. J Biomech. 2005;38(9)1918-25.

✤ Bus SA. Foot structure and footwear prescription in diabetes mellitus. Diabetes Metab Res Rev. 2008; 24 (Suppl 1):S90-95.

✤ Bus SA, Valk GD, van Deursen RW, Armstrong DG, Caravaggi C, Hlavácek P, Bakker K, Cavanagh PR. The effectiveness of footwear and offloading interventions to prevent and heal foot ulcers and reduce plantar pressure in diabetes: a systematic review. Diabetes Metab Res Rev. 2008;24 (Suppl 1):S162-80.

✤ Boulton AJ, Hardisty CA, Betts RP, Franks CI, Worth RC, Ward JD, Duckworth T. Dynamic foot pressure and other studies as diagnostic and management aids in diabetic neuropathy. Diabetes Care. 1983;6(1):26-33.

✤ Ghanassia E, Boegner C, Villon L, Avignon A, Thuan dit Dieudonné JF, Sultan A. Long-term outcome and disability of diabetic patients hospitalized for diabetic foot ulcers: a 6.5-year follow up study. Diabetes Care. 2008;31(7):1288-92.

References

✤ Frykberg RG, Lavery LA, Pham H, Harvey C, Harkless L, Veves A. Role of neuropathy and high foot pressures in diabetic foot ulceration. Diabetes Care. 1998;21(10):1714-9.

✤ Lott DJ, Hastings MK, Commean PK, Smith KE, Mueller MJ. Effect of footwear and orthotic devices on stress reduction and soft tissue strain of the neuropathic foot. Clin Biomech. 2007;22(3):352-9.

✤ Mueller MJ, Diamond JE, Delitto A, Sinacore DR. Insensitivity, limited joint mobility, and plantar ulcers in patients with diabetes mellitus. Phys Ther. 1989;9:453-62.

✤ Murray HJ, Young MJ, Hollis S, Boulton AJ. The association between callus formation, high pressures and neuropathy in diabetic foot ulceration. Diabet Med. 1996;13)11):979-82.

✤ Pitei DL, Foster A, Edmonds M. The effect of regular callus removal on foot pressures. J Foot Ankle Surg. 1999;38(4):251-5.

✤ Singh N, Armstrong DG, Lipsky BA. Preventing foot ulcers in patients with diabetes. JAMA. 2005;293(2):217-28.

✤ Stockl K, Tafesse E, Vanderplas A, Chang E. Costs of lower-extremity ulcers among patients with diabetes. Diabetes Care. 2004;27(9):2129-34.

✤ Young MJ, Cavanagh PR, Thomas G, Johnson MM, Murray H, Boulton AJ. The effect of callus removal on dynamic plantar foot pressures in diabetic patients. Diabet Med.1992;9(1):55-7.

✤ Zimny S, Schatz H, Pfohl M. The role of limited joint mobility in diabetic patients with an at-risk foot. Diabetes Care. 2004;27:942-46.