Greater trochanter chip fractures in the direct anterior approach for total hip arthroplasty.
BACKGROUND
The direct anterior approach (DAA) for the treatment of total hip arthroplasty (THA) has gained popularity in recent years. Chip fractures of the greater trochanter are frequently seen, but the risk factors for such fractures are unknown. The study aimed to identify the risk factors for chip fractures in patients undergoing primary THA by the DAA during the surgeons' learning curve.


METHODS
From November 2011 to April 2015, the first experiences of three surgeons who performed 120 THAs by the DAA (120 hips; 40 cases per beginner surgeon) were included. The incidence of chip fracture of the greater trochanter, the size of the greater trochanter as measured by computed tomography, and the patients' characteristics were retrospectively investigated.


RESULTS
After exclusion of 11 hips, the remaining 109 hips were investigated. Chip fracture of the greater trochanter was identified in 32 hips (29.4 %). Univariate analysis with and without fractures showed that the width and depth of the greater trochanter were statistically significant risk factors (p = 0.02 and p < 0.001, respectively). Multivariate analysis using a logistic regression model demonstrated that the depth of the greater trochanter was an independent risk factor for chip fracture of the greater trochanter (OR 1.725; 95 % CI 1.367-2.177; p < 0.001).


CONCLUSIONS
The size of the greater trochanter was identified as a risk factor for chip fracture of the greater trochanter. Novice surgeons should pay attention to the size of the greater trochanter when performing THA by the DAA.
Department of Orthopaedic Surgery, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. yhomma@juntendo.ac.jp.
Yasuhiro
Y
Homma
Department of Orthopaedic Surgery, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Tomonori
T
Baba
Department of Orthopaedic Surgery, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Hironori
H
Ochi
Department of Orthopaedic Surgery, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Yu
Y
Ozaki
Department of Orthopaedic Surgery, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Hideo
H
Kobayashi
Department of Orthopaedic Surgery, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Mikio
M
Matsumoto
Department of Orthopaedic Surgery, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Takahito
T
Yuasa
Department of Orthopaedic Surgery, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Kazuo
K
Kaneko
D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D006620:Hip Fractures / Q000175:diagnosis / Q000601:surgery; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D063868:Patient Outcome Assessment; D012189:Retrospective Studies; D012307:Risk Factors
Direct anterior approach; Femoral fracture; Greater trochanter; Learning curve