DPM Diabetic Foot Care & Management 3 — Questions and Answers
Question 1: A diabetic patient has a foot ulcer probing to bone. What is the positive predictive value of this probe-to-bone test for osteomyelitis?
- Approximately 35%
- Approximately 50%
- Approximately 89% (Correct answer)
- Approximately 99%
Correct answer: Approximately 89%
A positive probe-to-bone test has a positive predictive value of approximately 89%, making it a highly useful bedside diagnostic tool for osteomyelitis.
Question 2: Which MRI finding is most diagnostic of osteomyelitis in a diabetic foot?
- T1 hypointense, T2 hyperintense signal in bone marrow with cortical disruption (Correct answer)
- T1 hyperintense signal in periosteum
- T2 hypointense marrow signal with surrounding edema
- Gadolinium enhancement of cortical bone only
Correct answer: T1 hypointense, T2 hyperintense signal in bone marrow with cortical disruption
Osteomyelitis on MRI shows T1 hypointense and T2 hyperintense marrow signal, reflecting replacement of fatty marrow by inflammatory exudate, often with cortical disruption.
Question 3: Which growth factor, delivered via becaplermin gel, is FDA-approved for adjunctive treatment of diabetic foot ulcers?
- Epidermal growth factor (EGF)
- Platelet-derived growth factor-BB (PDGF-BB) (Correct answer)
- Vascular endothelial growth factor (VEGF)
- Fibroblast growth factor-2 (FGF-2)
Correct answer: Platelet-derived growth factor-BB (PDGF-BB)
Becaplermin (Regranex) contains recombinant human PDGF-BB and is the only FDA-approved topical growth factor for diabetic neuropathic foot ulcers.
Question 4: In a diabetic patient with suspected osteomyelitis, which laboratory marker most reliably correlates with disease activity and response to treatment?
- White blood cell count
- C-reactive protein (CRP)
- Erythrocyte sedimentation rate (ESR) (Correct answer)
- Procalcitonin
Correct answer: Erythrocyte sedimentation rate (ESR)
ESR is the most commonly used lab marker to track osteomyelitis activity in diabetic foot infections; levels above 70 mm/hr are particularly concerning.
Question 5: Which feature best differentiates a Charcot foot from osteomyelitis on technetium-99m bone scan?
- Charcot shows focal uptake; osteomyelitis shows diffuse uptake
- Charcot shows diffuse uptake; osteomyelitis shows focal uptake
- Bone scan cannot differentiate the two conditions (Correct answer)
- Charcot shows no uptake; osteomyelitis shows increased uptake
Correct answer: Bone scan cannot differentiate the two conditions
Technetium-99m bone scan cannot reliably differentiate Charcot neuroarthropathy from osteomyelitis, as both show increased uptake; labeled WBC scans or MRI are preferred.
Question 6: For a patient with diabetes and peripheral neuropathy, the sensation loss detected by a 10-gram Semmes-Weinstein monofilament corresponds to loss of which type of protective threshold?
- Vibration sense
- Temperature sense
- Protective sensation (Correct answer)
- Two-point discrimination
Correct answer: Protective sensation
Inability to feel a 10-gram Semmes-Weinstein monofilament indicates loss of protective sensation, identifying patients at high risk for foot ulceration.
Question 7: Which surgical procedure is most appropriate for a diabetic patient with a recurrent plantar metatarsal head ulcer due to flexible hammertoe deformity?
- Metatarsal head resection
- Proximal interphalangeal joint arthroplasty (Correct answer)
- Achilles tendon lengthening
- Panmetatarsal head resection
Correct answer: Proximal interphalangeal joint arthroplasty
Proximal interphalangeal joint arthroplasty (PIP arthroplasty) corrects flexible hammertoe deformity, relieving the abnormal plantar pressure that causes recurrent ulceration.
DPM Diabetic Foot Care & Management 3
A diabetic patient has a foot ulcer probing to bone.
What is the positive predictive value of this probe-to-bone test for osteomyelitis?