Published 5/1/2018
Peter Pollack

ALA May Reduce Risk of Nerve Injury Compared to DAA for THA

Bilateral study finds quality results for both approaches, but notes risks
For patients who undergo total hip arthroplasty (THA), both direct anterior approach (DAA) and anterolateral approach (ALA) in supine position can offer excellent clinical results, suggested Ryohei Takada, MD. “However, our findings suggest that ALA might be superior to DAA in terms of preventing nerve injury.”

At the AAOS 2018 Annual Meeting, Dr. Takada presented data from Paper 155, “Comparison of Clinical Results between Direct Anterior and Anterolateral Approach in One-Stage Total Hip Arthroplasty in Supine Position: A Prospective Randomized Controlled Trial.”

Nerve injury
According to Dr. Takada, there is a risk of lateral cutaneous femoral nerve (LCFN) injury associated with DAA, while ALA is linked to risk of superior gluteal nerve injury that can induce atrophy of tensor fascia latae (TFL).

“These nerve injuries can be critical for clinical results after THA,” he said. “We sought to compare clinical results and the influence of nerve injury between DAA and ALA in single-stage bilateral THA in a prospective, randomized, controlled trial. Due to the clinical success of both approaches, we anticipated that it might be difficult to compare them. We therefore performed our study using intra-subject side randomization.”

The research team recruited 30 patients undergoing primary one-stage bilateral cementless THA, 29 of whom were diagnosed with osteoarthritis and one with osteonecrosis. Patients were excluded if they had dementia, different disease severity between hips, or a previous history of hip surgery.

Each hip received a cementless, tapered femoral component with a 32 mm or 36 mm delta-ceramic head and a cementless acetabular component. The same surgeon operated on both hips of each patient. At the time of surgery, one hip of each patient was randomly assigned to DAA with the other to ALA. Patients were mobilized on the first postoperative day with full weight bearing as tolerated.

The researchers assessed patients using computed tomography, magnetic resonance imaging (MRI), and a handheld dynamometer. Readers were blinded to the surgical approach in all radiographic evaluations. Paired t-test was used to compare the clinical and surgical details, mean change rate of muscle, and grade of atrophy between both approaches. A P value of less than 0.05 was considered significant.

Cohort differences
Dr. Takada and his colleagues identified seven LCFN injuries (23.3 percent) among DAA hips at three-month follow-up, but all symptoms had disappeared at one-year follow-up. They observed no significant difference in mean change of cross-sectional area of gluteus medius across DAA and ALA groups. However, the mean change of cross-sectional area of TFL was significantly lower in the DAA group compared to the ALA group, and in MRI analysis, the mean grade of fatty atrophy of the TFL was marginally significantly higher in the DAA group than in the ALA group.

“Prior to this study, we assumed that LFCN injury would be more likely in hips treated with DAA, while superior gluteal nerve injury would be more likely in hips treated with ALA,” said Dr. Takada. “However, TFL atrophy induced by superior gluteal nerve injury was more prevalent in DAA hips.

“We believe this to be the first study that directly compares the difference between DAA and ALA in single-stage bilateral THA,” said Dr. Takada. “Although we found no significant difference of postoperative clinical results between approaches, the decrease of cross-sectional area and the atrophy of TFL were more prominent in DAA hips, and we observed LCFN injury only in the DAA group.”

Dr. Takada’s coauthors are Tetsuya Jinno, MD, PhD; Kazumasa Miyatake, MD, PhD; Kazuyoshi Yagishita, MD; and Atsushi Okawa.

Peter Pollack is the senior staff writer for AAOS Now. He can be reached at ppollack@aaos.org.