New Evaluation Method for Bone Formation around a Fully Hydroxyapatite-Coated Stem Using Digital Tomosynthesis: A Retrospective Cross-Sectional Study

Digital tomosynthesis (DTS) is a new imaging technique derived from radiography, and its usefulness has been gradually reported in the field of orthopedic diagnosis in recent years. A fully hydroxyapatite (HA)-coated stem, which is used for total hip arthroplasty (THA), is a type of cementless stem that has been widely used recently and reported to have good results. However, stem loosening on plain radiographs is difficult to determine in some cases due to cancellous condensation around the stem. In this retrospective cross-sectional study, we compared the results of plain radiography versus DTS to evaluate the imaging findings after THA using a fully HA-coated stem. Twenty joints each in the 3 y and 1 y postoperative groups underwent plain radiography and DTS. On DTS, bone formation around the stem was confirmed in all cases; however, this formation was not reproducible on plain radiography, and there were cases in which the reaction could not be confirmed or cases with cancellous condensation resembling reactive lines. This reaction was not reproducible on plain radiographs, and in some cases, the reaction could not be confirmed, or there were cases with cancellous condensation that resembled reactive lines. Therefore, DTS was useful in the diagnosis of bone formation around the implant.

Total hip arthroplasty in patients with severe hip dysplasia and congenital pubic diastasis: report of two cases

Background Congenital bladder exstrophy is a rare malformation which is often associated with pubic diastasis and hip dysplasia. We reported the case two patients who underwent total hip arthroplasty (THA) due to advanced osteoarthritis combined with large congenital pubic diastasis (> 10 cm). Case presentation The first patient, a 39 years old woman with a pubic diastase and severe hip dysplasia on both sides was treated with a primary two-staged bilateral THA. 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. The main problem was represented by the fixation of the cup, given the retroverted acetabulum along with the elevated rotation centre due to the dysplastic hips. In the case two, a 52 years woman presented dysplastic osteoarthritis of the left hip. 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 metaphyseal proximal femur bone. Conclusion Our results suggest that THA may be a good strategy to manage advanced hip osteoarthritis in patients with dysplasia and congenital pubic diastasis. Level of evidence IV, case series.

Hip Arthroplasty in Two Patients With Congenital Pubic Diastasis and Severe Dysplastic Hips

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.

Full-Quantitative Analysis of Cementless Stem Hammering Sound Changes During Total Hip Arthroplasty.

Full-quantitative characterization has not been performed to analyze changes in the hammering sound in cementless hip arthroplasty. We analyzed the frequency spectrum of the hammering sound during stem insertion for 20 cases of uncomplicated cementless total hip arthroplasty for osteoarthritis using a proximal-coated stem. The absolute sound pressure (Pa) and normalized sound pressure of each frequency bands in early and late stage of femoral stem insertion were determined by the Fast Fourier Transform analysis. The absolute sound pressures (Pa) of a majority of frequency bands was significantly higher in the late-stage stem insertion than in the early stage The 1.0–1.5-kHz frequency band showed a significant change in normalized sound pressure in all cases between the early and late stages of stem insertion (p=0.000). The femoral morphology and canal fill ratio were correlated with late stage normalized sound pressure in specific frequency bands. In the 5.0–5.5 kHz band, the Dorr A femoral morphology was significantly higher normalized sound pressure than those in the Dorr B (p=0.004). This study revealed the hammering sound frequency with full-quantitative value altered during cementless stem insertion. Frequency bands of 1.0–1.5 kHz, 5.0–5.5 kHz were the key bands for predicting stem fixation.