Date: Sunday, November 5, 2017
Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Background/Purpose: Forefoot deformities are commonly seen in patients with RA. It has been reported that nearly 90% of the patients have foot problems.1,2 Patients with RA often suffer from callosity or metatarsalgia in the rheumatoid foot. Forefoot surgery is often necessitated in cases of painful forefoot deformities in which conservative treatment proves to be insufficient.3,4 The purpose of this study is to investigate the differences in plantar pressure and background characteristics between the patients without scheduled forefoot surgery (group N) and the patients with scheduled forefoot surgery (group S), and to identify those characteristics that might be useful as indicators for conservative treatment.
Methods: Patients with RA were divided into 2 groups: group N and group S. The former consisted of 250 feet in 141 patients, and the latter consisted of 125 feet in 72 patients. DAS28, hallux valgus angle (HVA), the angle between the first and the second metatarsal bone (M1/2), the angle between the first and the fifth metatarsal bone (M1/5) and distribution of the site of callosity were evaluated as background characteristics. Distribution of peak pressure as plantar pressure was measured in 9 sections, including the first interphalangeal joint, the first through the fifth metatarsophalangeal joints (MTPJ), the medial and lateral midfoot, and the hindfoot. In addition, maximum peak pressure (MAXPP), minimum peak pressure (MINPP) and the difference value between MAXPP and MINPP (Δ pressure) were also measured. The MAXPP and MINPP indicates the highest and lowest peak pressure value found among the peak pressure measurements of all 9 sections, respectively. Finally, cut-off values were calculated from the receiver operating characteristic curve for each item which differed significantly between the 2 groups.
Results: In groups N and S, the mean DAS was 3.7 and 3.0 (p<0.001), the mean HVA was 19.4° and 34.5° (P<0.001), the mean M1/2 was 11.5° and 14.1° (P<0.001), and the mean M1/5 was 30.3° and 33.1°, respectively. Callosities were seen at the second and third MTPJ in half of all patients in group S. The mean peak pressure of group S at the first, second, third MTPJ, medial midfoot and hindfoot was significantly higher than that of group N (P <0.001, 0.05, 0.01,0.05 and 0.01). Significant differences between the 2 groups were also seen in MAXPP, MINPP and Δ pressure (P <0.001, 0.05 and 0.001). The cut-off values were 24.9° for HVA, 4.81 kg/cm2 for MAXPP and 4.51 kg/cm2 for Δ pressure. At the cut-off values, sensitivities were 76.0%, 69.6% and 67.4%, and specificities were 71.2%, 57.2% and 60.8%, respectively. Assessing HVA and MAXPP in combination, sensitivity was 46.4%, and specificity was 90.8%.
Conclusion: The combined assessment of HVA and MAXPP appeared to be useful as an indicator for conservative treatment of rheumatoid forefoot deformity. It is important to keep MAXPP under 4.81 kg/cm2 through drug treatment, orthotic treatment and physical treatment, in order to avoid forefoot surgery.
- Vainio K. Ann Chir Gynaecol Fenn Suppl. 1956;45(1):1-107.
- Thould AK, et al. Ann Rheum Dis. 1966;25(3):220-8.
- Helal B, et al. J Bone Joint Surg Brit Vol. 1984;66(2):213-7.
- Niki H, et al. J Bone Joint Surg Brit Vol. 2010;92(3):380-6.
To cite this abstract in AMA style:Lee H, Ishikawa H, Abe A, Nomura Y, Hasegawa E, Takai C, Kobayashi D, Otani H, Ito S, Sumino T, Ishii T, Saito S, Tokuhashi Y, Nakazono K, Murasawa A. Baseline Values for Plantar Pressure and Background Characteristics As Indicators for the Limit of Conservative Treatment of Rheumatoid Forefoot Deformity [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/baseline-values-for-plantar-pressure-and-background-characteristics-as-indicators-for-the-limit-of-conservative-treatment-of-rheumatoid-forefoot-deformity/. Accessed September 24, 2021.
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