Managing Pain in Cerebral Palsy Patients Using Ethanol Hip Joint Injection: A Retrospective Chart Review

Background In people with cerebral palsy (CP), some painful hips are too dysplastic for reconstruction by femoral or acetabular osteotomies. For these hips, a less invasive treatment than a bone-removing salvage operation is needed. The nonoperative management of this pain is not well-studied. The purpose of this study is to evaluate the use of ethanol hip joint injection to alleviate hip pain. This study aims to evaluate the outcomes of ethanol hip joint injections administered by a single surgeon and to evaluate their effectiveness in alleviating hip joint pain. Methods We included 57 consecutive patients with 71 hips in this study, with moderate-to-severe or severe pain. They had a total of 104 injections. Injections consisted of 10 mL to 15 mL of 75% ethanol into the hip joint under C-arm control, using a sterile field and general anesthesia. Gross Motor Function Classification System (GMFCS) was 4 or 5 for all. Data was collected from January 2010 to March 2023. The primary outcome was hip pain as recorded in the medical record. This was based on caregivers' perceptions and patients' facial expressions during physical exams in the clinic. Pain was evaluated on a scale of 1 to 5 (1: mild, 2: mild-moderate, 3: moderate, 4: moderate to severe, 5: severe). Following injection, a reduction in pain to a level less than 4 was considered a clinical success. The average follow-up period for these patients was 43 months (0.5-144 months). Short follow-up times gave information on the early onset, while longer follow-up times gave information on the duration of action. The total number of follow-up clinic visits for these patients was 202, and each clinic visit was used for pain score and follow-up time. A time-to-event analysis was done using Kaplan-Meier cumulative event curves to evaluate (1) time to a self-reported subjective pain score below 4 following the first injection and (2) to estimate the duration of pain control after the first injection. The event of interest was the time to the second injection in a patient who had reported a pain score below 4 after their first injection. Results The average patient age was 16 years. Of the 71 hips treated with a first ethanol hip joint injection, 61 (86%) showed a decrease in pain score to below 4. The median time to documentation of pain control after a first injection was four months. Within 10 months, 85% of the patients' hips reported pain control. Of those 61 hips with a decrease in pain score to below 4, 19 (31%) required a second injection. The median time to second injection after achieving pain control with the first injection was 33 months. When looking at all 104 injections, 36% experienced pain relapse. In our population who had hip joint injections, 11 hips (15%) had salvage surgeries and six hips (8%) developed avascular necrosis of the femoral head as an incidental X-ray finding. Conclusion This is the first study of an important modality. For our population of patients with CP and GMFCS level of 4 or 5, an injection of 10 mL to 15 mL of 75% ethanol into the affected hip joint, along with other procedures, provided pain control in 86%, with 31% of patients having a second injection after a median of 33 months. Based on these results, ethanol injection into the hip joint in those with severe or moderately severe pain should be further studied and considered as a treatment modality.