Treatment of pain syndrome after total hip arthroplasty associated with femora nerve entrapment
Authors: Pilieva Anastasia V. , Arkov Vladimir V. , Grishina Natalya A. 
Published: August 2022

BACKGROUND: The problem of pain syndrome after total hip replacement remains unresolved, including 3.5% of all revision interventions performed for pain of unclear etiology.
AIMS: to study the clinical picture of the pain syndrome that occurs after total hip replacement that is not associated with mechanical and septic instability of the components of the endoprosthesis; to develop methods for correcting the pain syndrome.
MATERIALS AND METHODS: The examination was carried out by patients (n=23) with complaints of pain in the groin and on the anterior surface of the thigh, who had a history of primary total hip replacement performed 3 months ago. The circumference of the hip was measured for the patients, and a visual assessment of the pose in an upright position was carried out. Stimulation electroneuromyography of the conductive function of the motor fibers of the femoral nerve was performed on both sides at the level of the inguinal ligament, the parameters of terminal latency (L, ms) and the amplitude of the M-response (A, mV) were evaluated. Needle electroneuromyography of the iliac muscle was performed in order to diagnose its pathological shortening before the start of treatment and 6 months after its completion. A complex of rehabilitation measures has been developed, including therapeutic blockade of the femoral nerve, physiotherapy treatment and individual physical therapy classes. Treatment results were evaluated using a visual analog scale (VAS), Oswestry and DN4 questionnaires before and after therapy.
RESULTS: Pathological changes of the femoral nerve from the operated joint were revealed in 23 (100%) patients. Needle electroneuromyography data indicated pathological shortening of the ilio-lumbar muscle in 19 (82%) of them. The quality of life according to Oswestry is 49.3415.63%, the level of pain syndrome according to VAS is on average 8.001.50 points, the average DN4 score is 4.351.58. The length of the hip circumference was 2.200.65 cm in favor of a healthy lower limb. When performing a femoral nerve blockade at the level of the inguinal ligament, the level of pain syndrome 510 minutes after administration of the drug was, according to VAS, 1.421.01 points. After 1 month from the start of rehabilitation treatment , the results of the survey are as follows: VAS 0.911.12 points, DN4 1.01.50 points, Oswestry 16.785.79%. The difference in the length of the hip circumference averaged 1.560.55 cm in favor of a healthy limb. The results of stimulation electroneuromyography after 6 months against the background of ongoing rehabilitation treatment showed an increase in the amplitude of the muscle response from total hip replacement by an average of 0.76 mV; according to needle electroneuromyography, normalization of the tone of the ilio-lumbar muscle on both sides was demonstrated.
CONCLUSIONS: In patients in the postoperative period of total hip replacement, pain syndrome is associated with the formation of compression-ischemic neuropathy of the femoral nerve from the side of the operated joint, which is due to a decrease in the tone of the rectus femoris muscle and a stable pathological tone of the ilio-lumbar muscle on the operated side. Comprehensive restorative treatment aimed at eliminating perineural inflammation, the release of pathologically shortened muscles, as well as muscle retraining, give a positive result in the rehabilitation of patients with pain syndrome in the late postoperative period of total hip replacement.