Össur Kristinsson first developed the Icelandic roll-on silicone socket (ICEROSS) in the mid 1980s. This type of socket interface was quickly popularized in the prosthetic community and has become the standard of treatment for transtibial amputees. Multiple manufacturers of roll-on liners, of various materials, now exist. These companies claim that liners offer superior comfort, suspension, and relief of dermatological problems compared with previous prosthetic options. A review of relevant literature reveals studies that are limited by the lack of diagnoses made by dermatologists (Cluitman et al., Prosthet Orthot Int. 1994;18:78–83; Lake and Supan, J Prosth Orthot. 1997;9:97–106; and Hachisuka et al., Arch Phys Med Rehabil. 2001;82:1286 –1289) and a failure to identify the frequency of these problems (Levy, Prosthet Orthot Int. 1980;4:37–44 and Dudek, et al. Arch Phys Med Rehabil. 2005;86:659–663). The purpose of this cross-sectional study is to determine the prevalence of dermatological problems in transtibial amputee subjects who use a roll-on liner with their prosthesis. A questionnaire determined demographic information, skin type, hygiene and prosthetic habits, comorbidities, and reported skin problems. All participants were offered a free examination by the dermatologist to verify medical history and document current skin problems. A X 2 , trend, and rank-sum test were used. Results indicated that 90.9% of subjects reported a history of skin problems, whereas 78% presented with a problem during the exam with the dermatologist. Specific correlations between habits and reported skin problems are also reported in this article. However, a direct correlation between amputee habits and skin problems is not clear. Because of high gasoline prices in rural Iowa, few participated in the skin exam. In this study, a greater number of transtibial amputees using roll-on liners had dermatological problems than previously reported. ( J Prosthet Orthot . 2008;20:134–139. )
Össur Kristinsson first developed the Icelandic roll-on silicone socket (ICEROSS) in the mid 1980s. This type of socket interface was quickly popularized in the prosthetics community and became the standard of treatment for transtibial amputees. Multiple companies now manufacture roll-on liners that are made of various materials, such as silicone or urethane, and come with or without a distal pin for suspension. Some liners have mineral oil or aloe, which are purported to moisturize the skin. Manufacturers claim that the liners offer superior comfort, suspension, and relief of dermatological problems compared with previous prosthetic designs. There is little scientific evidence of the prevalence of dermatological problems that occur with this type of prosthesis.
Clinical experience indicates that the liner may be an occlusive environment leading to skin irritation, reaction, or discomfort of the user. However, the prevalence of dermatological problems in the transtibial population is unclear, as is how physical, limb, or prosthesis characteristics, hygiene, or comorbidities affect this prevalence. Evidence of these relationships may guide manufacturers with the design of new liners and clinicians with recommendations to wearers.
Researchers have previously examined similar topics, but each study was limited in the application of its findings. Common dermatological problems and treatment solutions for lower limb amputees have been previously studied.1 For example, poor hygiene is related to bacterial and fungal infections, intertringinous dermatitis, nonspecific eczema, and epidermoid cysts. Nightly washing of the limb may help prevent these problems and is often clinically recommended to patients. However, the prevalence of these problems was not determined.1,2 Previous studies that used a quality questionnaire to gather demographic and habit information were each limited in their lack of direct involvement of a dermatologist.3–5 This creates uncertainty in the accuracy and consistency of the diagnoses, which may affect the reported prevalence of these problems.
The Fitzpatrick skin type is a standard classification system used by dermatologists to describe the skin's sensitivity to the sun. It corresponds to the effect on the skin after unprotected exposure to direct sunlight for 30 minutes for the first time each summer. The Fitzpatrick types are described as follows: type I burns then blisters, type II burns without a tan, type III burns then tans, type IV only tans. This type of classification can be self-reported by subjects and assessed by dermatologists for comparison.
The purpose of this study is to determine the prevalence of dermatological problems in transtibial amputee subjects who use a roll-on liner with their prosthesis.
A cross-sectional analysis was completed on adult transtibial amputee subjects fitted between 2000 and 2005 by American Prosthetics & Orthotics (APO), Inc. with a total surface bearing prosthesis and a roll-on liner. Subjects were identified through diagnosis and billing codes. They were excluded if they had multiple amputations or no longer were using a roll-on liner and/or prosthesis. The following types of data were self-reported by the subject on the questionnaire (Appendix): background, physical, limb and prosthesis information, and skin problems ever experienced. Background data included age, gender, race, amputation cause, and time since amputation, while physical data included hair color, effect of sun exposure (Fitzpatrick Type), color of the skin of the upper inner arm, and skin type. Limb data included whether or not the subject shaves the limb, limb cleaning habits (frequency, time of day, and type of cleanser), previously diagnosed skin problems, and other medical comorbidities. Prosthesis data consisted of liner type (color, brand, whether it utilized a pin), liner wearing time, liner cleaning habits (frequency, type of cleanser), sock ply utilized, items used between the skin and liner, prosthesis wearing time, and activity level. Subjects were asked, on the survey, if they had ever experienced any of the following problems under the liner: allergic skin reaction, ingrown hair, heat rash, open sore, excessive sweating, red or irritated skin, odor, or itchy skin. The questionnaire was based on that of previous studies.4,5 Specific liner data were verified through the subject's record at APO.
All subjects who completed the questionnaire were offered a free skin examination by the same dermatologist at the University of Iowa Hospital & Clinics to verify the selfreported medical history and document current skin problems (please see Appendix online). The following data were collected during the exam: background, physical, and limb and liner care information, and history of current dermatological problems. The background data were reported by the subject and included the reason for and time since amputation and natural hair color. Physical data such as Fitzpatrick skin type and skin color of upper inner arm were assessed by the Dermatologist. Limb and liner care information such as products used between the liner and skin, and products used to clean the limb and/ or liner were recorded. An assessment of the limb and current skin conditions were also recorded and photographed.
Chi-square, trend, or rank-sum tests were used to associate various factors with specified skin problems reported. Validity and reliability of the survey and physical exam data were also analyzed. Statistical p -values less than 0.0500 were considered significant. Each subject consented before participation. This study had IRB-01 approval at the University of Iowa.
Diagnosis and billing codes created a possible pool of 386 subjects, which was reduced to 290 because of undeliverable mail. Of that, 110 subjects (38%) returned completed questionnaires and 23 subjects (21%) received a skin exam with the dermatologist. Demographic data is shown in Table 1 . The survey population consisted of 84 men and 26 women with an average age of 58.8 years (range 19–85 years) and average time since amputation of 10.7 years (range 0.1–57 years). The physical exam population consisted of 18 men and 5 women with an average age of 53.0 years (range 19–84 years) and an average time since amputation of 8.4 years (range 0.3–36 years). Majority of the subjects (n = 106) for the survey and all subjects (n = 23) for the physical exam were caucasian. Causes of amputation for the survey included 46 trauma, 3 cancer, 2 congenital, 26 diabetes only, 17 vascular compromise only, 14 diabetes and vascular compromise, and 2 other. Majority of the subjects (n = 13) participating in the physical exam reported traumatic causes of amputation. Amputation cause data is described in Table 2 .
Results from the survey indicated that 90.91% of subjects reported experiencing at least one skin problem ( Table 3 ). Excessive sweating (60.00%), skin itching (54.55%), and red skin (52.73%) were most common. Collected data was compared with reported skin problems to determine if any habits significantly affected the prevalence of these problems.
The results for the background data on the survey indicated that subject race, gender, and age did not significantly correlate to reported skin problems. Similarly, when subjects were asked to freely report any other medical conditions, no significant difference was found between those who reported any medical problem and those who reported none. However, data indicated that those who reported high cholesterol reported significantly greater problems with heat rash (p = 0.0053) and red skin (p = 0.0047). Data for subjects who reported vascular disease without diabetes as a cause of amputation were compared with that of subjects with diabetes, with or without vascular disease; no significant differences were found between these groups. Therefore, data for both groups could be combined for further comparison. As illustrated in Table 4 , data indicated that 88% of subjects with vascular or diabetic causes of amputation and 94% of subjects with other amputation causes, mostly traumatic, reported at least one skin problem. The only significant difference between these two groups was that the vascular or diabetic group reported significantly less incidence of excessive sweating (p = 0.0060) than the other group. In a similar comparison, it was found that those with vascular or diabetic causes of amputation reported significantly less time since amputation (p = 0.0002) than those with other causes ( Table 5 ).
Physical data indicated that although hair color was not associated with reported skin problems, the effect of sun exposure and type of skin did correlate. Those who self-reported a Fitzpatrick type I also reported significantly greater incidence of offensive odor from the liner (p = 0.0480) than others. Subjects with medium or dark skin reported excessive sweating (p = 0.0238) and skin itching (p = 0.0262) significantly more often.
Limb data results indicated that significantly more subjects who shaved their limb complained of excessive sweating than those who did not shave (p = 0.0473). The type of soap used to clean the limb (antibacterial, deodorant, with or without perfumes, or no soap) made no significant difference; however, those who washed their limb more frequently did report red skin significantly more often (p = 0.0496) than others. Those who washed their limb at varying times throughout the day had more complaints of allergic reaction (p = 0.0095), heat rash (p = 0.05), and excessive sweating (p = 0.0247) than others, whereas those who washed their limb in the morning reported less problems with excessive sweating (p = 0.0014) and offensive odor from the liner (p = 0.0117) than others.
Prosthesis data were compared with skin problems. No significant differences were found in reported skin problems based on the frequency of liner cleaning, liner cleanser, brand or thickness, time since fitted with a liner, or whether a pin was used for suspension. Those who used nothing between their skin and the liner reported significantly more problems with offensive odor from the liner than those who used something (p = 0.0012). However, when the use of something is compared with nothing, each group reported the same (p = 1.0000) prevalence of allergic reaction, ingrown hair, open sore, excessive sweating, and red skin. Prosthesis habits, such as sock ply thickness and prosthetic wearing time made no significant difference for reported skin problems, but activity level did. Results indicated that those who have higher activity levels reported significantly greater incidence of ingrown hair (p = 0.0335) and skin itching (p = 0.0425) than those with lower activity levels.
All subjects who received a physical exam with the dermatologist indicated a history of at least one skin problem. The most common skin problems were ulcer or erosion (52.7%), irritant or frictional dermatitis (34.78%), and folliculitis (30.43%). Approximately 22% of subjects presented at the dermatological exam without any skin problems ( Table 6 ). However, the remaining subjects were diagnosed by the dermatologist with the following skin problems: lichenification (30.43%), irritant or friction dermatitis (26.09%), folliculitis (17.39%), ulcer or erosion (8.70%), hyperpigmentation (8.70%), and other (8.70%).
Reliability and validity testing were completed to compare the data self-reported by the subject on the survey and that reported to or assessed by the dermatologist during the exam. No significant difference was found between the survey and exam for the amputation cause (p = 0.5000) or hair color (p = 0.1000), which were each self-reported by the subject on the survey and during the exam. This indicates that the survey is reliable. Validity testing compared the subject's self-reported data on the survey to the dermatologist-assessed data for the Fitzpatrick skin type and the untanned skin color of the upper inner arm. No significant difference was found between data (p = 0.0894 and p = 0.5318, respectively). Therefore, the data on the survey was considered valid.
Approximately 91% of subjects reported that they had experienced a skin problem while using the roll-on liner with their prosthesis. Excessive sweating, skin itching, and red skin were the most common skin complaints. This is similar to the results of Hachisuka et al.5 who found that 60.2% of the subjects reported itching, 47% reported excessive perspiration, and 43.4% reported an offensive odor from the liner. Although Lyon et al.6 found that only 34% of subjects had skin problems, their study included lower limb, upper limb, and two limb amputees, which may lower the percentage.
Similar to previous studies, race and gender did not have significant affect on reported skin problems.4,5,7 However in this study, it was found that high cholesterol was associated with an increased reporting of heat rash and red skin. The explanation of this is uncertain. All of these subjects wore their prosthesis a minimum of 3 hours per day, with the majority wearing it greater than 12 hours per day. This group has an even distribution of skin type, cause of amputation, and so forth. It is uncertain whether these subjects take a similar medicine whose side-effect may cause this presentation. No significant differences were found for reported skin problems between those with vascular disease and/or diabetes-related amputations. Therefore, these two groups were combined for further comparison. Similar to previous results, the data from this study indicated that the diabetic vascular group had significantly less complaints of excessive sweating than the remaining subjects, which were mostly traumatic.4,5,7 The dysvascular population has a decreased production of sweat due to neuropathy causing a lack of sympathetic release of sweat. Neuropathy also causes decreased sensation, making it more difficult to feel the sweat.
Results from limb data had indicated that those who washed their limb more frequently or shaved had more complaints of specific skin problems. The complaint of excessive sweating with those who shaved their limb is more likely due to the ability to feel the sweat than the amount of sweat produced. Increased frequency of limb washing was associated with red skin. Clinically washing more frequently adds friction and rubbing irritation and dryness to the skin that may lead to the redness observed by subjects. An increase in skin problems was associated with a variance in the time of day that the limb was washed, while it was significantly lower in the group who washed in the morning. Perhaps the frequency or variation in washing is a result of limb problems rather than vice versa.
The prosthesis and liner directly interface with the amputee's limb, so it is reasonable to assume that the use, fit, and care of such an item may directly affect the skin. Although a majority of the subjects cleaned their liner once per day, as recommended by their prosthetist and the manufacturer, there was no significant difference in incidence of skin problems based on the frequency of cleaning the liner or the type of soap used. More interestingly, the results indicated that those subjects utilizing nothing between their skin and the liner had more complaints of an offensive odor versus those who used something. Similarly, Lake and Supan4 found an incidence of contact dermatitis as follows: 10% with use of a sheath, 18% with use of nothing, and 50% with use of powder. There was also found to be no difference between those who used something versus nothing with regards to the incidence of ingrown hair, open sore, excessive sweating, and red skin. This is interesting because manufacturers recommend that nothing should be used between the skin and liner. In our clinical experience, a sheath or liner for a liner (Knit Rite, Kansas City, Kansas) can resolve problems of red skin, contact dermatitis, or excessive sweating when used underneath the liner. Although no significant difference (p = 0.0630) was found for skin problems based on sock ply thickness, there is a trend toward those with less sock ply reporting less skin problems. This is reasonable since sock ply indicates the goodness of fit of the prosthesis and possibly the liner. Similarly, no difference was found among liner brands, type of suspension, or liner thickness. It seems that the fit of the prosthesis may be more important than the type of liner.
As expected, the reporting of higher activity levels corresponded to a greater prevalence of ingrown hair and itching skin. It is logical that an increase in activity may cause an increase in body temperature and subsequent mineral or sweat production. This sweat, when held against the skin within the occlusive environment of the liner, may lead to itching skin. Hachisuka et al.5 also found an increase in itching with an increase in activity level and an increase in perspiration with an increased wearing time. However, they also found that these problems decreased after time; a similar trend was not found in this study.
Skin type significantly affected reported skin problems in this study. It was found that those with the most sensitive skin, Fitzpatrick Type I, complained more often about an offensive odor from the liner. The cause of this is unclear. Perhaps these subjects were also utilizing other products, such as lotions, to care for their limb, which may react to the liner. Results also indicated that those with medium or dark skin reported excessive sweating and skin itching more often than those with fair skin. This may be due the medium or dark skin having more oil on it, which when held in the occlusive liner environment leads to excessive sweat and itching.
Although no statistical comparisons were possible for the dermatological exam data, due to the small number of participants, it was determined that irritant or frictional dermatitis, lichenification, and hyperpigmentation were the most commonly diagnosed problems. It is interesting, that unlike previous studies, no epidermal inclusion cysts were observed.1,2,7 This may be due to the use of a rounded posterior aspect of the total surface bearing socket design versus the posterior "wall" concept of the patellar tendon bearing socket design. Subjects commonly presented in clinic with either irritant or frictional dermatitis ( Figure 1 ) or folliculitis ( Figure 2 ) of the entire limb that was contained under the liner. There is a clear demarcation on the skin, corresponding to the proximal edge of the liner where the skin switches from occlusion within the liner to exposure outside of the liner. Many subjects also presented with lichenification ( Figure 3 ) of the distal end. Lichenification is a thickening of the skin resulting in a callous-like formation.
The authors acknowledge and accept that this study may have limits in its direct clinical application. The accuracy of the subject's self-diagnosis on the survey is uncertain, as is the temporal timeline for reported skin problems. This makes it impossible to conclude a direct cause-effect relationship between demographic or habit data and skin problems, and thereby limits the clinical applicability of this information. Similarly, the small sample size of the dermatological exam made statistical analysis impossible. It is likely that this small sample size was due to great distances that had to be traveled by participants during a time with high gasoline prices and a lack of reimbursement for this participation. Therefore, a future study that prospectively exams the habits and resultant dermatological problems of new amputees on a regular basis for several years is recommended.
This study used a questionnaire and a skin exam with a dermatologist to examine types of skin problems reported and possible causes in transtibial amputee subjects who use a roll-on liner. Prevalence of various dermatological problems was determined and conclusions of possible problems drawn. Data compared between the questionnaire and dermatological examination were determined to be valid and reliable. It is apparent that a greater number of transtibial amputees who use a roll-on liner have dermatological problems than previously suspected or reported.
The authors' clinical impression is that liners are not perfect. People do have skin problems, no matter the cause of amputation. We would like to challenge the manufacturers, practitioners, and researchers to further evaluate liner problems and make appropriate changes to allow us to better understand what is happening and why, and to make patients' lives better.
Correspondence to: Michelle J. Hall, CPO, FAAOP, Gillette Lifetime Specialty Healthcare, Assistive Technology Department, 435 Phalen Blvd., Street Paul, MN 55103; e-mail:
MICHELLE J. HALL, CPO, FAAOP, is affiliated with Gillette Lifetime Specialty Healthcare, St. Paul, Minnesota.
DONALD G. SHURR, CPO, PT, is affiliated with American Prosthetics & Orthotics, Inc., Iowa City, Iowa.
MARTA J. VANBEEK, MD, MPH, is affiliated with University of Iowa, Department of Dermatology, Iowa City, Iowa.
M. BRIDGET ZIMMERMAN, PhD, MS, is affiliated with University of Iowa, Department of Biostatistics, Iowa City, Iowa.