Bilal M. Ali, MD
Resident Physician
Rehabilitation Institute of Michigan, Detroit Medical Center
auburn hills, Michigan, United States
Angela M. Palant, BS
Medical Student
Des Moines University College of Osteopathic Medicine
Waukee, Iowa, United States
Andrew W. Demko, BS
Medical Student
Wayne State University School of Medicine
Grosse Pointe Park, Michigan, United States
Yusef A. Bazzy, DO
Resident Physician
Rehab Institute of Michigan, Detroit Medical Center
Detroit, Michigan, United States
Seth Feldman, DO
Resident Physician
Rehab Institute of Michigan
Royal Oak, Michigan, United States
Michael Ajluni, MD
Medical Director of Neuroscience, Residency Director, Associate Professor
Rehabilation Institute of Michigan, Wayne State School of Medicine
Detroit, Michigan, United States
David Rustom, MD
Pain Medicine Attending, Associate Professor
Rehabilitation Institute of Michigan, Wayne State University School of Medicine
Detroit, Michigan, United States
Heterotopic Ossification, Obturator Nerve Impingement
Case Description:
In this case, a patient developed heterotopic ossification (HO) at the left hip while recovering from a right middle cerebral artery stroke, with deficits of left hemiplegia and left-sided neglect. Upon presentation to inpatient rehabilitation, the patient complained of burning and tingling of his left superomedial thigh, exacerbated by hip flexion. Severe pain limited the patient’s hip flexion and significantly impaired his participation in therapy. Computed Tomography demonstrated significant HO anterior to the left hip within the iliopsoas. His symptoms suggested obturator nerve impingement by the HO. After failed trials of indomethacin and gabapentin, an obturator nerve block reduced his pain by over 70%. As a result, the patient demonstrated a 50% improvement in cycling endurance and enhanced functional mobility. Transfer assistance was successfully reduced from maximal to moderate assistance. He tolerated greater range-of-motion (ROM) exercises and partial squats. These improvements persisted after discontinuing indomethacin and reducing gabapentin dosage.
Discussions:
Heterotopic ossification is the abnormal formation of bone within soft connective tissues, often presenting with pain, edema, erythema, and reduced ROM in affected joints. HO following stroke is a rare occurrence, affecting 0.5-1.2% of stroke patients. In this case, HO presented as neuropathic pain, exacerbated by hip flexion, in a localized distribution matching that of the obturator nerve. Combined steroid with anesthetic was injected along the obturator nerve distal to the HO site, which relieved most symptoms after 7 days. A thorough clinical examination was needed to identify HO and the symptoms of obturator nerve impingement.
Conclusions:
Given the unclear etiology and evolving management of HO, clinicians should remain vigilant when encountering new or worsening musculoskeletal symptoms during rehabilitation, particularly in stroke patients. It is possible for HO to compress surrounding structures. A nerve block may effectively treat pain secondary to nerve impingement from HO.
