Distal non-traumatic fracture of the cementless MP stem: A case report and review of previous reported cases

Abstract

Modular hip stems offer many advantages in revision arthroplasty. However, the region of modularity is prone to failure. Fracture of the non-cemented fluted tapered titanium Modular Prosthesis (MP) stem is relatively rare. We present here a case of a distal non-traumatic fracture of the MP stem and review the previously reported cases. A 53-years old, relatively active, male patient with a body mass index (BMI) of 37 kg/m 2 had a fracture of the non-cemented MP stem on the left side after five years without complaints. The BMI was 45 at the time of implantation of the MP stem. His weight was significantly reduced, but the stem failed and fractured at an atypical site, quite distal to the modular junction. The broken stem with a relatively small diameter had been exchanged to a larger one. Fracture of the non-cemented fluted proximally-modular distally-tapered titanium MP stem might occur after years. Even in cases of good bone quality of the proximal femur, patient BMI and activity level should be considered when selecting the stem diameter. Furthermore, proximal bone loss of the femur should be considered as a potential cause of failure.

Fracture in the middle of the femoral stem and relevant treatment after the revision total hip arthroplasty: A case report

“…Owing to the trend of younger diseases, THA's surgical guidelines have gradually included young and middle-aged individuals. For young patients, particularly those with high BMI, to meet the requirements of high standards of daily activities, prosthesis was often under great pressure, which would increase the related risks [7,8,16,17]. Therefore, for such high-risk individuals, Matsen et al [7] assumed that the prognosis could be judged by regularly detecting the concentration of metal ions in the blood, and corresponding treatment could be administered at an early stage.…”

“…As to the occurrence of this phenomenon, Botti et al and Melnic et al [11,19] assumed that, particularly for patients who only were subjected to the revision, the risk of fracture may be related to the injury of the retained femoral part caused by the retractor during exposure in operation. Busch et al and Abdelaziz et al [16,17] believed that ETO, which was often used in revision surgery, would cause a large amount of bone loss in the proximal femur, which would lead to the loose proximal prosthesis, sinking of prosthesis, and uneven stress on the prosthesis. Therefore, the method of ligation and fixation using wired cables should be adopted preventively in the greater trochanter during operation for patients undergoing ETO, and if necessary, it was essential to re-expand the medullary cavity for increasing the size of the prosthesis or switching to the prosthesis with extensible porous-coated stem to obtain the effect of diaphyseal fixation [12,15,17].…”

“…However, the modular prosthesis has filled the gap in the field of joint replacement, which opened a new era. The advantage of it is adjusting the length of the lower limb and size of the offset, improving the accuracy of the prosthesis and facilitating the progress of secondary revision [17,20]. However, compared with the common complications, like sinking and loosening, in a non-modular prosthesis, modular prosthesis had a significantly increased incidence of fracture at the junction, which possibly was related to the structural integrity of the prosthesis [12,13].…”