Sensory and biomechanical characterization of two painful syndromes in the heel.

UNLABELLED: This study evaluated sensory and biomechanical assets in 2 heel pain conditions with similar symptoms, entrapment syndrome of the nerve to abductor digiti quinti and myofascial syndrome of abductor hallucis. Thirty-three patients with unilateral heel pain and 20 asymptomatic subjects underwent pressure pain threshold measurement in the painful area in site A (medial process of calcaneal tuberosity, trigger point site of abductor hallucis) and site B (1 cm posteriorly to site A, where the nerve to abductor digiti quinti becomes most superficial) and contralaterally; electroneurography of posterior tibial nerve; evaluation of ground-foot reaction on a dynamic platform. Eighteen patients had electric shock-type pain (entrapment syndrome, Group 1), 15 had cramp-like pain (myofascial syndrome, Group 2). Pain thresholds on the affected side versus contralaterally were significantly lower in site B in Group 1 and in site A in Group 2 (P < .001). Nerve conduction velocity was slightly reduced in Group 1 (P = .05). Ground-foot reaction was significantly altered on the affected side in all patients versus asymptomatic subjects; a significant difference between the 2 sides was found for peak of force (F1) in Group 1 and for all parameters except temporal phase of peak of force (TF3) (P = .05) for Group 2 (P < .0001). The different sensory and biomechanical patterns of the 2 examined syndromes help the differential diagnosis and consequent therapeutic approach. PERSPECTIVE: This study shows different sensory and biomechanical patterns in 2 algogenic conditions of the heel with similar pain location. These distinct patterns reflect different pathophysiologic mechanisms in the 2 cases, which has a potential significant impact on treatment.