Periprosthetic bone density changes after MiniHip^TMcementless femoral short stem: one-year results of dual-energy X-ray absorptiometry study

Abstract

Introduction: The purpose of the current study was to investigate the reaction of the femur to the implantation of the MiniHipTM in terms of: (1) bone density change during one year; (2) correlations between stem length, CCD (caput-collum-diaphyseal), femoral offset, T-value, and bone density; (3) other co-variables that influence the change of bone density. Patients and methods: MiniHipTM implant was performed for 62 patients. The age range of the patients who underwent treatment was 25–78 years. Periprothestic bone density was determined within two weeks postoperatively, after three, six, and twelve months utilizing the DEXA scan. Results: The highest change was observed in the first three months post-implantation, while significant decrease in density was recorded at proximal Gruen zones 1, 2, and 7, and at distal Gruen zone 4. The decrease in density reached a plateau between the third and sixth months after operation. Afterwards, bone density recovered up to the 12th postoperative month. The correlation analysis showed significant difference between Gruen zone 1 and stem size and CCD. The same significant trend was not reached for Gruen zone 7. Femoral offset showed no correlation. Covariance analysis was unable to establish connection of the results with diagnosis, pairings, or gender. Discussion: MiniHipTM densitometric results are promising and comparable to good results of the other representatives of the femoral neck partially-sustaining short stem prostheses with a lower proximal bone density reduction. Periprosthetic bone resorption is a multifactorial process where stem size, CCD angle, and patient-specific variables such as T-value have an impact on the periprosthetic bone remodeling. In particular, this applies to Gruen zone 1.

Radiographic analysis of stability after implantation of three different cementless short femoral stems – five year follow-up

“…In the literature there are few scientific papers discussing the above stems, there are no scientific papers comparing stability of these stems [8,9,10].…”

Long-term results of an anatomically implanted hip arthroplasty with a short stem prosthesis (MiniHipTM)

“…Our radiological long-term results showing a more physiological proximal load transfer and a reduced stress-shielding, have been confirmed by several densitometric studies comparing the bone remodeling between different short and conventional straight stems[ 41 , 42 ]. For the Minihip TM but also for other stems, an initial bone resorption in all periprosthetic zones is a typical finding immediately after the implantation[ 1 , 21 ]. However, in studies on the Minihip TM , the initial bone resorption within the first months had a much lesser extend compared to different conventional stems[ 13 , 41 - 43 ].…”

“…More important is that a relatively strong subsequent bone remodelling within the proximal Gruen zones was documented during the following years. Thus, compared to conventional straight stems, a much lower proximal bone density loss was noticed[ 1 , 21 ]. Because of this process of bone formation, which continued till the second year, the bone-friendly design of the Minihip TM as a representative of a partially neck-sustaining stem has been discussed[ 21 ].…”

“…Short-stemmed cementless hip arthroplasty prostheses have been designed to preserve bone stock, facilitate an eventual revision surgery and achieve a more physiological loading to the proximal part of the femur[ 1 - 4 ]. In comparison to conventional cementless stems, short stems are therefore described to reduce the stress shielding around the stem, which might be associated with thigh pain, bone loss and an increased risk of aseptic loosening[ 5 - 8 ].…”

“…Clinical follow-up studies of the MiniHip TM showed a good short-term clinical outcome[ 18 - 20 ] as well as good densitometric results with a comparatively lower proximal bone density reduction[ 1 , 21 ]. To our knowledge, this is the longest study on this well-established femoral neck retaining metadiaphyseal prosthesis.…”