The Efficacy of Total Contact Casting in the Healing of the Neuropathic Diabetic Foot Ulcer
Diabetic foot ulceration is a common complication that affects up to 15% of diabetic patients at some time in their lives (Edmonds, 2006). Edmonds (2006) estimates that 85% of amputations are preceded by an ulcer and that there is an amputation every thirty seconds throughout the world. In many cases, diabetic foot ulcerations are preventable with the neuropathic or neuroischaemic ulcer providing the most scope for prevention. In order to understand the mechanisms of delayed and/or non-healing wounds, such as neuropathic or neuroischaemic ulcers it is important to understand the processes of normal repair (Li et al., 2007). Normal wound healing can be roughly divided into three overlapping phases of inflammatory reaction, proliferation, and remodelling (Li et al., 2007). Some authors insist on four phases of wound healing with the first phase being coagulation, highlighting the importance of the vascular responses (Falanga, 2005). It is thought, that keratinocytes on the edges of chronic wounds are unable to migrate properly, during the proliferation phase, resulting in the wound being unable to close. This is due to the fact that these keratinocytes appear to be unresponsive to activation signals that promote cell migration. Fibroblasts of diabetic ulcers also show a decreased response to various growth factors (Li e al., 2007). In the healing of neuropathic ulcers, pressure relief is of the utmost importance and total contact casting (TCC) is highly effective in this area (Boulton, 2004). TCC involves the immobilising of the foot by casting it and the leg using rigid synthetic casting materials or plaster of Paris placed over a layer of felt padding. A rubber heel can be fixed into the cast base to ensure that the cast is not in contact with the floor. The cast is changed frequently during ulcer treatment with every dressing change (Udovichenko et al., 2010). This paper will attempt to review articles within the literature in order to better understand the reason for the wide use of TCC and its efficacy in treating neuropathic diabetic foot ulcers.
Sinacore et al. (1987) was a well designed study that compared diabetic and non-diabetic patients with plantar foot ulcers to assess the effectiveness of total contact casting on ulcer healing. The authors of the article presented a balanced study citing the need for a randomised controlled trial. This is ideal as Wang & Bakhai (2006) consider a study of this type to be the most valued in the era of evidence-based medicine. Sinacore et al. (1987) also admirably used intention-to-treat anlaysis therefore including data from patients that did not complete the trial due to medical complications or non-compliance. To have excluded data from these subjects would have resulted in bias (Wang & Bakhai, 2006). Sinacore et al. (1987) proved in their clinical report that the reduction or redistribution of plantar ulcer pressures throughout the foot influences healing even in the patient with vascular compromise secondary to diabetes. This cast doubt on the commonly held belief, at the time, that macro-vascular and micro-vascular changes in diabetes, causing local ischaemia, delayed healing. Sinacore et al. (1987) therefore highlighted what an important factor pressure re-distribution is to the healing of plantar ulcers.
The need to quantify exactly how effective TCC was at pressure reduction over the entire plantar surface of the foot was therefore a priority. Wertsch et al. (1995) used a portable microprocessor-based data-acquisition system to record plantar foot pressures from six individuals walking both with and without a TCC. The results showed a decrease in plantar pressure of 32% under the fifth metatarsal, 63% under the fourth metatarsal, 69% under the first metatarsal, 65% under the hallux and 45% under the heel. These figures show the overwhelming benefit TCC has on facilitating healing in plantar ulcer healing.
A comparison of TCC with other pressure offloading devices was essential in order to cement TCC’s reputation as the most effective way to decrease plantar pressures during ulcer management. Armstrong et al. (2001) presented a randomised clinical trial comparing TCC, removable cast walkers (RCW) and half-shoes using a sample of 63 patients. As has already been noted, randomised clinical trial is considered the most valued of studies (Wang&Bakhai, 2006). The patients in this study, presented with non-infected, non-ischaemic plantar diabetic wounds and were randomised across the three interventions and monitored until their ulcers healed or for a maximum of twelve weeks. The activity levels of the patients were also measured using a pedometer attached to the intervention received to log the steps patients took daily. The results showed that after the twelve week period the proportions of healing for patients treated with TCC, RCW and half-shoes were 89.5%, 65% and 58.3% respectively. The differences in the activity of the patients using the three interventions showed the TCC and RCW to be similar but the patients using the half-shoes were significantly more active than the other two interventions. This difference in activity, rather than the off-loading properties of the interventions, was thought to account for the difference in healing rates in the opinion of the authors.
Armstrong et al. (2003) put this hypothesis to the test by recruiting twenty patients with neuropathic, University of Texas grade 1 stage A foot ulcers. These patients were then issued with RCW fitted with pedometers not accessible to the patients as well as a pedometer to be worn on the patient’s waist. At the end of the trial the daily output from the two pedometers was compared. The results showed that patients only wore their RCW for a staggering 28% of their total daily activity. This result highlighted the importance of patient compliance in the healing of foot ulcers and gave an insight into the success of TCC through enforced patient compliance due to it being irremovable.
RCW were proven as effective as total contact casting at pressure reduction in the ulcerated foot but this did not equate to similar healing times (Armstrong et al., 2002). The authors offer the results of a previous study as an explanation to this phenomenon. The study showed that only 15% of neuropathic patients wore protective footwear when at home although they conducted 50% of their daily activity there. Armstrong et al. (2002) offer the solution of rendering a removable cast
irremovable by the application of adhesive bandages or plaster of Paris to address this issue of patient non-compliance.
Katz et al. (2005) took the notion of poor patient compliance when using the RCW, proposed by Armstrong et al. (2002), as well as their idea of rendering the RCW irremovable and compared such a device to the traditional TCC to try to confirm this method’s efficacy. This randomised trial of forty one consecutive diabetic patients with neuropathic plantar ulcers assigned to either of the two intervention groups, proved the irremovable RCW to be more effective than the traditional TCC at healing. The proportion of ulcers healed in the RCW group compared to the TCC group were 80% and 74% respectively. The irremovable TCC was therefore said to be equally efficacious, faster to place, easier to use, and less expensive than the TCC in the management of neuropathic foot ulcers.
TCC was well established as a treatment option but little research had been undertaken to ascertain the rate of ulcer recurrence once healing had been achieved. This led Matricali et al. (2003) to conduct a short-term follow-up study of fifteen diabetic patients who had foot ulcers that were healed through TCC. The patients were all prescribed footwear and monitored for a period of twenty two months. Greenhalgh (1997) asserts that a study should continue long enough for the effect of the intervention to be reflected in the outcome variable. This innovative study showed alarmingly high ulcer recurrence rates as well as frequency. Matricali et al. (2003) once again cited poor patient compliance with high recurrence rates in concurrence with Armstrong et al. (2003).
TCC’s success at aiding the healing of neuropathic ulcers was well documented but most studies were based on clinical observation with the outcome variable of ulcer healing classified as re-epithelialisation of such a wound. Piaggesi et al. (2003) decided to carry out a semi-quantitative analysis of histopathological features of neuropathic foot ulcers to see if TCC influenced these features at all. The study design consisted of the comparison of excised neuropathic plantar ulcer tissue from ten diabetic patients (Group A) with the tissue excised in exactly the same manner from ten patients (Group B) with neuropathic plantar ulcers that had been using TCC for the period of twenty days. Tissue specimens were blindly measured by two pathologists. All participants of the study were unaware of whether the subjects belonged to the therapy or control group. This blinding minimises bias (Wang & Bakhai, 2006). The results showed that the histopathological features of the two groups differed markedly. Tissue specimens from Group A showed inflammatory elements, matrix alterations, vessel disruptions and debris. Specimens from Group B, on the other hand, showed cutaneous annexes, capillaries and granulating tissue. This affirmation of the effectiveness of TCC at a histological level was very significant in the light of all the clinically evaluated evidence that preceded this study.
TCC is not without risks and disadvantages and certain authors have therefore tried to confirm and quantify certain perceived risks. Hartsell et al. (2002) presented an
original paper looking at the effects TCC has on contralateral plantar foot pressures. Only two studies had previously been undertaken on this matter but had only considered general peak pressures of the contralateral foot and had found that TCC had no significant effect on this. Hartsell et al. (2002) theorised that perhaps a parameter such as contact time of the foot with the ground may be more valuable for determining contralateral plantar pressure effects related to ulceration. Greenhalgh (1997) states that studies should be contributing to the broader literature on a subject and Hartsell et al. (2002) certainly do by adding a valid dimension to a study already undertaken. TCC, on the surface , would certainly seem to make a difference to the pressures on the contralateral foot but Hartsell et al. (2002) conclude that, in fact, no difference was seen using a running shoe, traditional TCC or fibreglass TCC when measured by an insole pressure measuring device.
Another concern was the effect of total contact casting on the range of motion of the subtalar joint and the ankle joint (Diamond et al., 1993). The justification of the study suggested that limited mobility at the ankle, subtalar and metatarsophalangeal joints was a contributing factor in neuropathic plantar ulceration. Range of motion measurements were taken using a goniometer which could be judged to be susceptible to error but a reliability study was undertaken proving high inter-rater and intra-rater agreement. The results showed no changes at the subtalar joint but a reduction in dorsiflexion of one degree at the ankle joint. The authors therefore concluded that any reduction in range of motion was negligible and that the benefits of TCC outweighed any risk.
Though TCC was highly effective in the treatment of plantar ulcerations in patients with diabetes mellitus, it was not widely used. The lack of acceptance of TCC was thought to be due to the difficulty of patients to comply with an initial period of non-weight-bearing generally recommended by physicians at the time (Saltzman et al., 2004). In this thorough study, Saltzman et al. (2004) treated forty diabetic patients with non-infected plantar ulcers with TCC with pedometers embedded within the casts. The patients were treated until healing was achieved or for a total of thirteen weeks. The number of steps taken by each patient was recorded at twenty four hours and forty eight hours. Patient selection within this study was sound with robust eligibility criteria. Wang & Bakhai (2006) state that a carefully defined set of eligibility criteria are essential as they ensure that a study’s findings have ‘external validity’or, are generalizable for the treatment of future patients. The results showed that moderate early weight-bearing only minimally retards healing of plantar ulcers in patients with diabetes.
Wukich & Motko (2004) and Guyton (2005) both monitored samples of patients undergoing TCC and recorded any complications encountered along the way. Wukich & Motko (2004) observed the TCC treatment of thirteen patients with neuropathic foot ulcers through the application of eighty two casts in total. The results showed a total of fourteen complications arise out of a total of eighty two
casts applied (17%). Wukich & Motko (2004) concluded that TCC can be safely used in high-risk patients with neuropathic complications but minor complications should be expected and patients should therefore be warned of such possibilities.
Guyton (2005) decided to investigate any complications associated with the TCC treatment method using a considerably larger sample than Wukich & Motko (2004). The author analysed a total of 398 consecutive total contact casts spanning twenty eight months form the practice of a single physician. Complications were observed in twenty two casts corresponding to an overall complication rate of 5.52% per cast. The rate of permanent sequelae from cast complications was shown to be 0.25%. Guyton (2005) concludes that a frequently changed TCC is a safe modality for the offloading of the neuropathic foot.
The literature supports TCC as an effective treatment for neuropathic, non-infected and non-ischaemic plantar foot ulcers but what about its effect on moderately ischaemic patients and those who have infected ulcers? Nabuurs-Franssen et al. (2004) included patients within their study sample that had peripheral arterial disease (PAD) (44%) as well as those with infection (29%). Nabuurs-Franssen et al. (2004) designed their study as a prospective follow-up study involving ninety eight patients treated with TCC until healing was achieved or casting had to be stopped over a period of five years. Greenhalgh (1997) approves of a study with a large enough sample and long enough continuity to make results credible as was the case with Nabuurs-Franssen et al. (2004). The results of this study show healing rates for neuroischaemic ulcers to be 87%. In PAD without critical limb ischaemia, 69% of the ulcers without infection healed and 36% with infection healed too. Nabuurs-Franssen et al. (2004) therefore concluded that in addition to neuropathic ulcers, ulcers with moderate ischaemia or infection could also be successfully treated using TCC.
The evidence on the efficacy of TCC in off-loading pressure across the plantar surface of the foot to facilitate the healing of neuropathic diabetic foot ulcers is convincing. As has been demonstrated, the pressure re-distribution attributes of TCC alone are not as big a factor as is the forced patient compliance due to its irremovability to the patient (Armstrong et al., 2003). Another feature of TCC seems to be the forced decrease of daily activity which is not seen in other pressure off-loading devices and could account for their lower ulcer healing rates (Armstrong et al., 2001). TCC is not without its risks and disadvantages such as its effects on joint range of motion at the ankle as well as iatrogenic complications. These risks, fortunately, have been found to be minimal with the benefits of TCC far outweighing any disadvantages. Cost, weight and perceived aesthetics to the patient of TCC were other considerations for the clinician but rendering a RCW irremovable (Armstrong et al., 2002) or the possible use of re-usable casts in the future (Udovichenko et al., 2010) seem to be fair solutions but research is needed on the latter. Other possible avenues for further research would be expanding the scope of
TCC to being used to heal ulcers on the moderately ischaemic foot as well as infected ulcers as suggested by Nabuurs-Franssen et al. (2004). It is for the reasons highlighted above that TCC remains the “gold standard” for the management of neuropathic ulcers (Boulton, 2004).
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