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Biomechanical optimization of orthopedic footwear for diabetic patients using in-shoe plantar pressure measurement
S84
Oral Presentations / Gait & Posture 24S (2006) S7–S97 [3] Chang CH, et al. J Pediatric Orthop 2002;22:813–8. [4] Bowen TR, et al. J Pediatric Orthop 1998;18:789–93. [5] Jameson GG. Dev Med Child Neurol 2004;99:34.
doi:10.1016/j.gaitpost.2006.11.059 O-52 Biomechanical optimization of orthopedic footwear for diabetic patients using in-shoe plantar pressure measurement Fig. 2. Foot angle means and standard deviations.
the medial area of the midfoot region for 28.7% of stance. The COPP then moves from the midfoot into the forefoot region where it progresses medially and forward passing just lateral to the hallux. The period of time the COPP spends in the forefoot is 47.5% of stance phase. The results for the comparative analysis of the two methods of long axis determination are shown in Fig. 2. The A-T method used 3D kinematic data to determine the long axis of the foot. This method is consistent with common gait analysis approaches for measuring foot progression angle. The remaining eight bars in the graph show the long axis angle for the two repetitions of manual long axis selection by each analyst. Three analysts were within one degree of the A-T method, while the fourth analyst, B, was approximately two degrees less than the A-T method. Statistical analysis found significant differences between the methods, but no differences between the analysts. Excellent intra-rater, 0.975, and inter-rater, 0.969, reliability was observed. The A-T method employs 3D kinematics to determine the long axis of the foot. The subjective method was performed by four observers (G, L, J, and B), two times for each trial.
5. Discussion The statistical differences shown reflect absolute differences less than 2◦ , these differences may offer little clinical relevance. With the data stratified into the medial to lateral areas of the heel, midfoot, and forefoot clinical classifications can be generated, i.e. varus, valgus, severe varus, severe valgus, equinus, calcaneous, and normal. These results give reasonable confidence that manually selecting the long axis is an acceptable method for feet that are normally shaped. However, using the subjective method for malalligned feet or feet in equinus or varus may not reflect the same level of confidence. This technique provides a rational basis for an objective clinical classification of dynamic foot deformities.
References [1] Stokes IAF, et al. Acta Orthop Scand 1975;46:839–47. [2] Duckworth T, et al. J Bone Joint Surg 1985;67:79–85.
Sicco Bus a,b,∗ , Rob Haspels b , Carine van Schie a , Paul Mooren a a
Department of Rehabilitation, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands b Diabetic Foot Unit, Department of Surgery, Twenteborg Hospital, Almelo, The Netherlands
1. Summary/conclusions Using in-shoe plantar pressure assessments to evaluate orthopedic footwear can be an effective method to achieve significant pressure reduction at high-risk areas in the diabetic neuropathic foot.
2. Introduction Orthopedic footwear is commonly prescribed to diabetic patients with prior plantar foot ulceration. Several studies have reported large inter-individual differences in the pressure reducing effect of various types of custom insoles and shoes [1,2]. Therefore, predicting the pressure reducing effect of footwear remains difficult. As a result, it has been argued that custom footwear should be evaluated and optimized using in-shoe plantar pressure measurement [1,3]. The purpose of this study was to assess the feasibility of using inshoe plantar pressure measurements to optimize the pressure reducing effect of custom footwear in patients with diabetes.
3. Statement of clinical significance Diabetic patients with a prior plantar foot ulcer frequently show recurrence of an ulcer. Although there is limited evidence on the effectiveness of orthopedic footwear in preventing recurrence of plantar ulceration, optimizing the pressurereducing effects of orthopedic footwear using in-shoe pressure analysis may significantly lower the risk for ulcer recurrence in these patients.
4. Methods Ten diabetic patients with peripheral sensory neuropathy and history of plantar foot ulceration who were previ-
Oral Presentations / Gait & Posture 24S (2006) S7–S97
S85
Fig. 1. Peak pressure diagrams showing the result of footwear modifications made in two cases: a PP reduction from 469 to 319 kPa (= 32%) at the hallux in one patient (left two planes) and from 239 to 172 kPa (= 28%) at the lateral forefoot in another patient (right two planes).
ously prescribed with orthopedic footwear participated in this study. Using the Pedar-X system (Novel, Germany), in-shoe plantar pressures were measured during four walking trials at a self-selected walking speed. Based on the peak pressure diagrams and values shown on-screen directly after collecting data, a region(s) of interest (ROI) for optimization (i.e. pressure reduction) was defined. This was the region with the highest measured peak pressure and/or with prior ulceration. A maximum of three rounds of footwear modifications were applied. After each round the effect of the modifications on inshoe plantar pressure was assessed using the same protocol and a standardized walking speed. Footwear modifications included all possible shoe or insole adaptations of which the shoe technician thought they would reduce pressure at the ROI. Criteria for successful optimization were a 25% or more reduction in peak pressure or an absolute reduction of peak pressure below 200 kPa [4]. A detailed analysis of plantar pressure was performed using Novel Multimask software.
5. Results A total of 13 ROIs were defined in the 10 patients tested. The number of optimization rounds varied between one and three. Mean peak pressure at the ROI was reduced from 344 kPa (S.D. 99) in the non-optimized footwear to 229 kPa (S.D. 73) after footwear optimization. Twelve out of 13 ROIs were successfully optimized by a minimum 25% reduction in peak pressure (mean 33%, range 22–50%, see Fig. 1 for two examples). In the remaining case peak pressure was reduced below 200 kPa. The maximum time needed for footwear optimization (including pressure measurement) was 75 min.
6. Discussion The results showed that the footwear evaluated in this study could be successfully optimized within three rounds of
footwear modifications and within a reasonable time frame. These findings suggest that using in-shoe plantar pressure assessments to evaluate orthopedic footwear can be an effective method to achieve significant pressure reduction at highrisk areas in diabetic neuropathic patients. This method provides the clinical team with a more objective approach to footwear prescription and evaluation for the diabetic foot. Whether this approach can contribute to a reduction in plantar ulcer recurrence in these patients remains to be investigated.
References [1] Bus SA, Ulbrecht JS, Cavanagh PR. Pressure relief and load redistribution by custom-made insoles in diabetic patients with neuropathy and foot deformity. Clin Biomech 2004;19:629–38. [2] Guldemond NA, Leffers P, Schaper NC, Sanders AP, Nieman FH, Walenkamp GH. Comparison of foot orthoses made by podiatrists, pedorthists and orthotists regarding plantar pressure reduction in The Netherlands. BMC Musculoskelet Disord 2005;6:61. [3] Cavanagh PR. Therapeutic footwear for people with diabetes. Diabetes Metab Res Rev 2004;20(Suppl. 1):S51–5. [4] Cavanagh PR, Ulbrecht JS, Apelqvist J, Stenstrom A, Kalpen A, Bus SA. In-shoe plantar pressure threshold for the prevention of plantar ulcer recurrence. Diabetes 2002;51:A255.
doi:10.1016/j.gaitpost.2006.11.060
Oral Presentations / Gait & Posture 24S (2006) S7–S97 [3] Chang CH, et al. J Pediatric Orthop 2002;22:813–8. [4] Bowen TR, et al. J Pediatric Orthop 1998;18:789–93. [5] Jameson GG. Dev Med Child Neurol 2004;99:34.
doi:10.1016/j.gaitpost.2006.11.059 O-52 Biomechanical optimization of orthopedic footwear for diabetic patients using in-shoe plantar pressure measurement Fig. 2. Foot angle means and standard deviations.
the medial area of the midfoot region for 28.7% of stance. The COPP then moves from the midfoot into the forefoot region where it progresses medially and forward passing just lateral to the hallux. The period of time the COPP spends in the forefoot is 47.5% of stance phase. The results for the comparative analysis of the two methods of long axis determination are shown in Fig. 2. The A-T method used 3D kinematic data to determine the long axis of the foot. This method is consistent with common gait analysis approaches for measuring foot progression angle. The remaining eight bars in the graph show the long axis angle for the two repetitions of manual long axis selection by each analyst. Three analysts were within one degree of the A-T method, while the fourth analyst, B, was approximately two degrees less than the A-T method. Statistical analysis found significant differences between the methods, but no differences between the analysts. Excellent intra-rater, 0.975, and inter-rater, 0.969, reliability was observed. The A-T method employs 3D kinematics to determine the long axis of the foot. The subjective method was performed by four observers (G, L, J, and B), two times for each trial.
5. Discussion The statistical differences shown reflect absolute differences less than 2◦ , these differences may offer little clinical relevance. With the data stratified into the medial to lateral areas of the heel, midfoot, and forefoot clinical classifications can be generated, i.e. varus, valgus, severe varus, severe valgus, equinus, calcaneous, and normal. These results give reasonable confidence that manually selecting the long axis is an acceptable method for feet that are normally shaped. However, using the subjective method for malalligned feet or feet in equinus or varus may not reflect the same level of confidence. This technique provides a rational basis for an objective clinical classification of dynamic foot deformities.
References [1] Stokes IAF, et al. Acta Orthop Scand 1975;46:839–47. [2] Duckworth T, et al. J Bone Joint Surg 1985;67:79–85.
Sicco Bus a,b,∗ , Rob Haspels b , Carine van Schie a , Paul Mooren a a
Department of Rehabilitation, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands b Diabetic Foot Unit, Department of Surgery, Twenteborg Hospital, Almelo, The Netherlands
1. Summary/conclusions Using in-shoe plantar pressure assessments to evaluate orthopedic footwear can be an effective method to achieve significant pressure reduction at high-risk areas in the diabetic neuropathic foot.
2. Introduction Orthopedic footwear is commonly prescribed to diabetic patients with prior plantar foot ulceration. Several studies have reported large inter-individual differences in the pressure reducing effect of various types of custom insoles and shoes [1,2]. Therefore, predicting the pressure reducing effect of footwear remains difficult. As a result, it has been argued that custom footwear should be evaluated and optimized using in-shoe plantar pressure measurement [1,3]. The purpose of this study was to assess the feasibility of using inshoe plantar pressure measurements to optimize the pressure reducing effect of custom footwear in patients with diabetes.
3. Statement of clinical significance Diabetic patients with a prior plantar foot ulcer frequently show recurrence of an ulcer. Although there is limited evidence on the effectiveness of orthopedic footwear in preventing recurrence of plantar ulceration, optimizing the pressurereducing effects of orthopedic footwear using in-shoe pressure analysis may significantly lower the risk for ulcer recurrence in these patients.
4. Methods Ten diabetic patients with peripheral sensory neuropathy and history of plantar foot ulceration who were previ-
Oral Presentations / Gait & Posture 24S (2006) S7–S97
S85
Fig. 1. Peak pressure diagrams showing the result of footwear modifications made in two cases: a PP reduction from 469 to 319 kPa (= 32%) at the hallux in one patient (left two planes) and from 239 to 172 kPa (= 28%) at the lateral forefoot in another patient (right two planes).
ously prescribed with orthopedic footwear participated in this study. Using the Pedar-X system (Novel, Germany), in-shoe plantar pressures were measured during four walking trials at a self-selected walking speed. Based on the peak pressure diagrams and values shown on-screen directly after collecting data, a region(s) of interest (ROI) for optimization (i.e. pressure reduction) was defined. This was the region with the highest measured peak pressure and/or with prior ulceration. A maximum of three rounds of footwear modifications were applied. After each round the effect of the modifications on inshoe plantar pressure was assessed using the same protocol and a standardized walking speed. Footwear modifications included all possible shoe or insole adaptations of which the shoe technician thought they would reduce pressure at the ROI. Criteria for successful optimization were a 25% or more reduction in peak pressure or an absolute reduction of peak pressure below 200 kPa [4]. A detailed analysis of plantar pressure was performed using Novel Multimask software.
5. Results A total of 13 ROIs were defined in the 10 patients tested. The number of optimization rounds varied between one and three. Mean peak pressure at the ROI was reduced from 344 kPa (S.D. 99) in the non-optimized footwear to 229 kPa (S.D. 73) after footwear optimization. Twelve out of 13 ROIs were successfully optimized by a minimum 25% reduction in peak pressure (mean 33%, range 22–50%, see Fig. 1 for two examples). In the remaining case peak pressure was reduced below 200 kPa. The maximum time needed for footwear optimization (including pressure measurement) was 75 min.
6. Discussion The results showed that the footwear evaluated in this study could be successfully optimized within three rounds of
footwear modifications and within a reasonable time frame. These findings suggest that using in-shoe plantar pressure assessments to evaluate orthopedic footwear can be an effective method to achieve significant pressure reduction at highrisk areas in diabetic neuropathic patients. This method provides the clinical team with a more objective approach to footwear prescription and evaluation for the diabetic foot. Whether this approach can contribute to a reduction in plantar ulcer recurrence in these patients remains to be investigated.
References [1] Bus SA, Ulbrecht JS, Cavanagh PR. Pressure relief and load redistribution by custom-made insoles in diabetic patients with neuropathy and foot deformity. Clin Biomech 2004;19:629–38. [2] Guldemond NA, Leffers P, Schaper NC, Sanders AP, Nieman FH, Walenkamp GH. Comparison of foot orthoses made by podiatrists, pedorthists and orthotists regarding plantar pressure reduction in The Netherlands. BMC Musculoskelet Disord 2005;6:61. [3] Cavanagh PR. Therapeutic footwear for people with diabetes. Diabetes Metab Res Rev 2004;20(Suppl. 1):S51–5. [4] Cavanagh PR, Ulbrecht JS, Apelqvist J, Stenstrom A, Kalpen A, Bus SA. In-shoe plantar pressure threshold for the prevention of plantar ulcer recurrence. Diabetes 2002;51:A255.
doi:10.1016/j.gaitpost.2006.11.060