Early Greater Trochanteric Avulsion Fracture After Posterior Approach Primary Total Hip Arthroplasty: A Clinically Relevant and Potentially Avoidable Complication.

BACKGROUND

A greater trochanteric (GT) fracture after primary total hip arthroplasty (THA) is a clinically relevant complication that can lead to gait abnormalities and chronic lateral hip pain. Early postoperative GT avulsion fractures are rare, possibly resulting from poor bone quality or the use of two transosseous drill holes for posterior capsular repair. Computer- and robotic-assisted surgery may increase fracture risk due to cortical defects from temporary pins. This study aimed to assess the rate of early GT fractures and identify contributing factors and prevention strategies.

METHODS

This was a retrospective review of patients who underwent a posterior approach primary THA at our institution between January 1, 2016, and December 31, 2022, and subsequently presented with a GT avulsion fracture. Patient demographics, procedure details, implanted components, surgical technique, and postoperative fracture radiographs were reviewed, with descriptive statistics calculated for all variables.

RESULTS

There were 39 GT avulsion fractures identified among 18,873 posterior approach primary THAs, yielding an absolute risk of 0.2%. Of these, 97% occurred in women (mean age of 73 years, mean body mass index of 26). All avulsion fractures were atraumatic and occurred early, at an average of 27 days, during routine activities. The majority (59%) of the patients who had GT avulsion fractures had confirmed low bone density. In addition, 90% of avulsion fractures occurred in cases with two drill holes for posterior capsular repair, and 64% (25 of 39) involved computer navigation or robotic assistance. Of the 39 cases, 59% used a fit-and-fill stem, whereas 41% used a tapered wedge stem. Offset and leg length were increased by an average of 5.4 and 4.5 mm, respectively, on the affected hip.

CONCLUSIONS

Atraumatic GT avulsion fractures after posterior approach THA are a clinically important complication. Factors such as women, low bone density, increased femoral offset, and the two-drill-hole technique for soft tissue repair may be associated with this complication. Consideration for a single or no drill hole for the posterior repair technique may reduce the risk of this complication.