Accuracy and practicability of a patient-specific guide using acetabular superolateral rim during THA in Crowe II/III DDH patients: a retrospective study

BACKGROUND: It is challenging to create an ideal artificial acetabulum during total hip arthroplasty (THA) in adult DDH. Our team developed a new patient-specific instrument (PSI) that uses the superolateral rim of the acetabulum as a positioning mark to assist in the production of an artificial acetabulum in adult Crowe II/III DDH patients. The purpose of this retrospective study is to verify whether this new PSI can be used to implement the preoperative plan accurately and quickly to create an ideal artificial acetabulum during THA in adult Crowe II/III DDH patients. METHODS: We selected suitable adult Crowe II/III DDH patients from the registration system for artificial joint surgery at our hospital during April 2016 to March 2018 who underwent THA assisted by a PSI using the superolateral rim of the acetabulum as a positioning mark. We retrospectively analyzed data, including preoperative and postoperative anteversion, inclination, postoperative bilateral rotator center discrepancy (BRCD), surgery time, and the incidence of neurovascular injury. All patients underwent follow-up, and their Harris hip score (HHS) and X-ray data were recorded. Then, we performed statistical analyses on the data described above. RESULTS: A total of 20 hip surgeries from 17 patients were included in our study. All patients underwent a successful operation assisted by the PSI. The mean anteversion of the cup in our preoperative plan was 15.1° (range, 10.0° to 20.0°), while the mean postoperative anteversion of the cup was 15.3° (range, 7.0° to 28.6°). The mean inclination of the cup in our preoperative plan was 44.7° (range, 40.0° to 50.0°), while the mean postoperative inclination of the cup was 45.6° (range, 35.0° to 57.6°). Paired-samples t test revealed no significant differences in anteversion and inclination between pre- and postoperation times (P > 0.05). The mean BRCD was 3.38 ± 3.0 mm (range, 0.5 to 11.0 mm). The average operation time was 105.1 ± 15.4 min, and no patients had neurovascular injury complications. All patients’ acetabular components appeared clinically and radiologically stable after surgery. The mean HHS values were significantly improved at 12 weeks (P < 0.05) and 24 weeks (P < 0.05) postoperatively compared to the preoperative mean scores. CONCLUSIONS: The new PSI is accurate and practical to create an ideal artificial acetabulum during THA in adult Crowe II/III DDH patients. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13018-018-1029-1) contains supplementary material, which is available to authorized users.