Background: Congenital pubic diastasis in combination with a dysplastic situation of the hip is a rather rare malformation. Two cases of young female patients prompted us to report the results of total hip arthroplasty (THA) due to secondary osteoarthritis. Our treatment strategy and short- as well in one case long-term results are described in regard to the rather rare literature.
Methods: We describe a case of a 39 -year-old female patient with a pubic diastase and severe hip dysplasia on both sides treated with a primary total hip arthroplasty (THA). High overweight of more than 275 pounds, diabetes mellitus and multiple prior operation aggravate the operative procedure. Main problem based on the fixation strategy of the cup in this retroverted acetabulum presented in CT-analysis with elevated rotation center due to the dysplastic situation. In the other case a 52-year old female lady presented dysplastic osteoarthritis of the left hip.
Results: In the first case both hips were treated with a cementless osteoconductive cup (TM, Zimmer-Biomet) and a cementless stem (Alloclassic SL, Zimmer-Biomet). A 10° elevated rim liner of the cup was used in order to avoid dislocation. Both hips were 9 and 8.5 years postoperative radiologically still in place without any signs of loosening. There was an improvement of quality of life documentated with an amelioration of the Harris Hip Score from preoperative 14 points to 68 points. In the second case a conventional hemispherical cup (Alloclassic-Allofit, Zimmer-Biomet) was placed in the retroverted acetabulum combined with a cementless stem (Fitmore A, Zimmer-Biomet) attached at the metaphseal proximal femur bone. 6 months postoperative, the patient was free of symptoms with an increased quality of life.
Conclusion: Sufficient long-term results highlight the possiblity of total hip arthroplasty of patients with osteoarthritis even in congenital pubic diastasis. Retroversion of the dysplastic acetabulum, rotation of the posterior part of the pelvis and instability of the pelvic ring in these circumstances might be the most feared aspects in the treatment of these rare cases.