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‘Hip-Sachs’ impaction lesions seen in 23% of patients with acetabular fractures
Results showed the wedge-shaped femoral head lesion was most often associated with a transverse acetabular fracture.
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BELFAST, Northern Ireland — CT scans had a 100% detection rate for “Hip-Sachs” lesions — a wedge-shaped depressed fracture of the femoral head — in 173 patients with acetabular fractures who were referred for surgical treatment at The National Center for the Treatment of Pelvic and Acetabular Fractures in Dublin, according to a presenter at the British Orthopaedic Association Annual Congress, here.
Ailbhe White-Gibson, MD, said some of the 40 lesions she and her colleagues identified could also be seen on radiographs and all occurred in conjunction with a transverse element.
“To our knowledge, a depressed fracture of the femoral head has not been previously reported. [AP] anteroposterior X-rays and CT views are reportedly sensitive, but in our series, we did identify one patient with the lesion who did not have CT imaging available,” she said. “All other lesions were detectable by CT.”
White-Gibson and colleagues referred to this femoral head lesion as the “Hip-Sachs” lesion because, like the Hill-Sachs lesion of the humeral head, it is wedge-shaped and represents a substantial defect. The defect occurs in the posterolateral aspect of the femoral head in this case vs. the humeral head in the case of the Hill-Sachs lesion, which was described in 1940.
Retrospective study done at referral center
Image: White-Gibson A
The investigators first noticed the lesion in December 2015 and retrospectively reviewed possible cases of “Hip-Sachs” lesions referred to and treated at their center starting in July 2012. They sought to identify the best imaging modalities for detecting the lesions and the acetabular fracture patterns with which they were associated.
In all, 173 patients among 202 patients with acetabular fractures transferred to the investigators’ center for surgery were included in the study. Men comprised 75% of the study group.
“Our results find that there were 155 lesions detected on the AP radiographs. We find that on the lateral radiographs there are 163, and there were 168 lesions found on CT scans. So, what we find out in terms of fracture patterns, posterior-wall fractures were the most common,” White-Gibson said.
Anterior column and transverse acetabular fractures were also commonly identified in conjunction with theses lesions, she said.
Transverse acetabular fractures
Forty of the lesions were “Hip-Sachs” lesions, based on the findings.
“The significance of this is the transverse fractures were involved in almost every case of ‘Hip-Sachs’ lesion that we identified. Of these, 33 [patients] had preoperative X-rays; 39 [patients] had available CTs; and the detection rate on CT was 100%,” White-Gibson said.
The investigators often saw the lesion directly adjacent to a bony acetabular spike, which indicates an impaction-type injury, she noted.
The next step is to determine the significance of these lesions.
“We are currently collecting medium to long-term data, which will give us an indication of whether or not this particular lesion predisposes patients to osteoarthritis, although we do hypothesize this is the case,” White-Gibson said. – by Susan M. Rapp
- Reference:
- O’Neill BJ, et al. Depressed fracture of the femoral head associated with acetabular fracture: Analysis of the “Hip-Sachs” lesion. Presented at: British Orthopaedic Association Annual Congress; Sept. 13-16, 2016; Belfast, Northern Ireland.
- For more information:
- Ailbhe White-Gibson, MD, can be reached at The National Centre for the Treatment of Pelvic and Acetabular Fractures, Tallaght Hospital, Tallaght, Dublin 24, D24 NR0A, Ireland; email: whitegia@tcd.ie.
Disclosure: White-Gibson reports no relevant financial disclosures.