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Table 1 Definition of variables and factors

From: Re-amputation in patients with diabetes-related minor amputations who underwent physical therapy during their hospitalization

Variable Definition
Body mass index Calculated by dividing the body weight (kg) by the square of the height (m) and was reported in kg/m².
Hospitalization days The duration of a single episode of hospitalization. Inpatient days are calculated by subtracting day of admission from day of discharge.
Physical therapy period Number of days of physical therapy during hospitalization.
Average length of daily physical therapy Calculated by dividing total hours of physical therapy by the number of days in the hospital.
Non-weight-bearing period Number of days from the date of surgery to the start of weight-bearing on the lower limb operated on. All patients were eligible, and the initiation of weight-bearing was performed by a physical therapist under the direction of a specialist.
Heart disease Defined as angina pectoris, myocardial infarction, percutaneous coronary intervention, or coronary artery bypass grafting.
Cerebrovascular disease Defined as a transient ischemic attack, cerebral infarction, or cerebral hemorrhage.
Amputation region [14] Toe, ray, and transmetatarsal amputations were defined as minor. Amputation below and above the knee was defined as major.
Estimated glomerular filtration rate [15] The estimated glomerular filtration rate (eGFR) was calculated based on the new Japanese coefficient Modification of Diet in Renal Disease study equation: eGFR (mL/min/1.73 m²) = 194 × (serum creatinine) − 1.094 × (age) − 0.287 (× 0.739 for females).
Skin perfusion pressure Blood flow was measured and evaluated using a Laser Doppler (SensiLase PAD4000, KanekaMedix, Osaka, Japan).
Ankle-brachial pressure index Measured with an automated oscillometric device provided by Omron Colin Co., Ltd. (Tokyo, Japan).
WIfI classification system [16] WIfI classification system was developed in 2013 and provides an objective classification for wound healing and limb amputation based on three independent risk factors (wound extent, degree of ischemia, and extent of foot infection).
Charcot's joint [17] Defined as a dislocation of the second metatarsal joint of the tarsus with a rupture of the first metatarsal line and a decrease in the angle of calcaneal inclination.
Hallux valgus [18] Defined as angulation of the big toe at the first metatarsophalangeal joint > 20°.
Hammer toe [19] Defined by flexion deformity at the PIP joint with extension at the DIP joint and a neutral or extended position of the MTP joint.
Claw toe [20] Defined as an extended MTPJ, flexed PIPJ, flexed DIPJ, and determined via clinical examination.
Knee extension muscle strength [21] Maximum voluntary isometric knee extension muscle strength was measured using a hand-held dynamometer (μ-tasF-1, Anima, Tokyo, Japan). For knee extensor strength measurements, participants were asked to sit on a chair with the knee flexed at 90° and push at maximum strength against the dynamometer pad for 5 s. Isometric knee extensor strength was measured twice per side, and the highest value for the right and left legs was used to represent the knee extensor muscle strength.
Range of motion (ankle joint) [22] The ankle joint was examined in the neutral position, with the patient supine; a vertical line is marked on the patient’s skin from the heel to midcalf, and the maximum range of dorsiflexion in passive motion is measured in degrees with a goniometer.
Plantar sensory disorder [23] The presence or absence of plantar sensory impairment was considered as neuropathy when the evaluator size of the Semmes-Weinstein-monofilament was 5.07.We performed three-site tests involving the plantar aspects of the great toe, third metatarsal, and fifth metatarsal.
Functional Independence Measure (ambulation) [24] FIM is an 18-item, clinician-reported scale that assesses function in six areas including self-care, continence, mobility, transfers, communication, and cognition. Each of the 18 items is graded on a scale of 1–7 based on level of independence in that item (1 = total assistance required, 7 = complete independence). Ambulation items were rated according to the amount of assistance from 1 point (total assistance: able to walk less than 15 m) to 7 points (full independence: able to walk 50 m and move with no assistance).