Optimal Time Period to Achieve Temperature Stabilisation After Total Contact Cast (TCC) Removal for Assessing Dermal Temperatures in Active Charcot Neuro-Osteoarthropathy.

BACKGROUND

Dermal temperature differentials between limbs are used to monitor disease progression and support safe withdrawal of immobilisation in Charcot neuro-osteoarthropathy (CNO). Despite the wide clinical use of dermal thermometry, there is a lack of evidence on the optimal temperature stabilisation period after removal of immobilisation devices, such as total contact casts (TCCs). This study aimed to investigate the optimal time period to achieve temperature stabilisation post removal of TCC for assessing dermal temperatures in active CNO.

METHODS

Over a 2-year period, this within-subjects repeated measures study recruited 12 adults with active CNO treated with TCC from a metropolitan high-risk foot service in Melbourne, Australia. Participants were excluded if they had bilateral CNO, an active foot ulcer, an inflammatory foot condition (e.g., gout), peripheral artery disease or major lower limb amputation. In a temperature-controlled room, dermal temperatures were recorded using an infrared thermometer after removal of TCC and contralateral footwear. Temperatures were recorded at 10-min intervals from baseline to 90 min at 10 anatomical locations on each foot. Paired samples t-tests or Wilcoxon signed-rank tests explored temperature stabilisation at each anatomical site across the 10 time points.

RESULTS

Mean age was 55.1 (SD, 8.9) years, 75.0% were male and 83.3% had type 2 diabetes. All participants had peripheral neuropathy and a large proportion had history of foot ulceration (75.0%). The average duration of CNO was 2.9 (SD, 1.7) months, with most classified as stage 1 (91.7%), affecting the tarsometatarsal joints (58.3%) and midtarsal joints (83.3%). Overall, dermal temperatures had stabilised by 40 min for the Charcot (casted) foot and contralateral (non-casted) foot.

CONCLUSIONS

This is the first study to explore the optimal time period to achieve temperature stabilisation when assessing dermal temperatures in active CNO. Forty minutes appears to be an appropriate resting time to reach thermal equilibrium. Although this approach may improve the accuracy of dermal thermometry, the time period may not always be feasible in clinical practice.