MRI Assessment of Hip Abductor AfterTotal Hip Arthroplasty with Direct Lateral Approach



1 Department of Orthopedic Surgery, Imam Hossein Hospital, Shahid Beheshti University of Medical Science, Tehran, Iran

2 Department of Orthopedic Surgery, Taleghani Hospital, Shahid Beheshti University of Medical Science, Tehran, Iran

3 Department of Orthopedic Surgery, Akhtar Hospital, Shahid Beheshti University of Medical Science, Iran


Background and objectives: Increase in the degenerative joint diseases has resulted in a high prevalence of total hip arthroplasties (THA) so surgical techniques used and rehabilitations after surgery play a significant role in improvement of pain and limping. We aimed to assess hip abductor muscle’s diameter and function after 6 months postoperative THA performed by modified harding approach
Materials and methods: After recording patients’ demographics, the preoperative values of patients’ hip abductor muscle diameter was evaluated by MRI and compared to the 6 month postoperative values. The hip abductor muscle’s strength was assessed by Trendelenburg test. The muscle’s atrophy and heterotopic ossification were recorded by the defined classification and compared with pre- and postoperative values.
Results: A total of 88 patients participated in this study with a mean age of 47.3±1.574 years, 55.7% of whom were male. Mean leg length discrepancy (LLD) decreased (from 41.07mm pre operative to 16.74mm postoperative) (p<0.001) and muscle diameter decreased (from mean 27.07±7.485mm preoperative to mean 25.64±7.353mm postoperative) after surgery (P<0.001). Before surgery 29.5% of patients had heterotopic ossification, 97.7% of which resolved in post operative imaging (p=0.020); 42% of patients had fluid collection in pretrochanteric bursa, 98.9% of which resolved after surgery (P<0.001).Also, the frequency of limping and grade of Trendelenburg test (mild or sever) decreased after surgery (P<0.001), but the frequency of muscle atrophy did not change significantly (P>0.05). There was no significant difference in the frequency of different grades of limping according to the studied variables.
Conclusion: favorable surgical outcome was obtained in terms of LLD and muscle diameter, which shows the efficacy of the surgical technique and rehabilitation, on the other hand value of MRI for pre- and postoperative assessments of gluteus medius muscle diameter but low relationship between recently value and Trendelenburg test


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