Elderly patients treated with elbow HA revealed good to excellent short-term clinical outcomes. A high rate of complications occurred but most complications found were minor and reoperation rate was low. Our results must be regarded as a report on our first experience with HA. As cartilage wear is just a question of time especially in active patients, we cautiously recommend HA only for elderly and multimorbid low-demand patients.

Purpose The tension band wiring (TBW) technique is a common treatment for the fixation of olecranon fractures with up to three fragments. The literature and surgeons describe TBW as an uncomplicated, always available and convenient operation producing excellent results. The purpose of this study was to determine whether TBW is more ambitious than believed or the procedure provides an increased level of tolerance concerning the surgical technique. Methods This study reviewed 239 TBW cases in patients with olecranon fractures or osteotomies. We reviewed a total of 2,252 X-rays for ten operative imperfections: (1) nonparallel K-wires, (2) long K-wires, (3) K-wires extending radially outwards, (4) insufficient fixation of the proximal ends of the K-wires, (5) intramedullary K-wires, (6) perforation of the joint surface, (7) single wire knot, (8) jutting wire knot(s), (9) loose figure-of-eight configuration, and (10) incorrect repositioning. Results On average, there were 4.24 imperfections per intervention in the cases reviewed. A total of 1,014 of 2,390 possible imperfections were detected. The most frequent imperfections were insufficient fixation of the proximal ends of the K-wires (91 % of all cases), the use of a single wire knot (78 %) and nonparallel K-wires (72 %). Mayo IIa (n =188) was the most common fracture type.Conclusions Our results and the number of complications described by the literature together support the conclusion that TBW is not as easy as surgeons and the literature suggest. Although bone healing and the functional results of TBW are excellent in most cases, the challenges associated with this operation are underestimated.Level of Evidence: IV, treatment study

Proximal cortical and cancellous bone density loss and decrease of contact area indicate that metaphyseal fixation cannot be achieved. The lack of cortical BD loss and increase of contact area values below the trochanter minor suggest diaphyseal fixation.

The method presented is an excellent tool for detailed measurement of bone density changes around the cup after total hip arthroplasty, and allows a thorough assessment of stress shielding phenomena in vivo. The hemispherical titanium alloy press-fit cup is a rigid implant which stress shields cancellous bone and enhances load transfer to the cranial cortical bone. Further investigations will demonstrate the impact these factors have on the long-term results of the implant, and may allow a type-related predictable prognosis of the longevity of the prosthesis.

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Owing to the lack of fresh human bones, formalin-fixed specimens are frequently used in biomechanical testing. However, formalin fixation is assumed to affect the biomechanical properties of bone. The aim of this study was to compare axial and torsional stiffness and bone mineral density in fresh and embalmed human bones. The subtrochanteric regions of 12 pairs of fresh human femora were randomised into two groups for paired comparison. After bone mineral density measurement, one group was preserved in 4% formalin. After 6 weeks, bone mineral density was remeasured and each specimen underwent axial and torsional loading. The formalin group showed significant higher stiffness values for torsional and axial loads than the fresh group. Axial stiffness increased by 14.1%, whereas torsional stiffness increased by 14.3%. These differences were not reflected in bone mineral density values. Formalin fixation significantly influences the stiffness of human cadaveric bones. Fresh bones represent the in vivo conditions better than formalin fixed bones.

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Stress-shielding and periprosthetic bone loss after total hip arthroplasty (THA) may be clinically relevant for high-demand patients. Analysis of cortical and cancellous bone density (BD) changes in vivo after THA is of interest to basic science researchers and joint reconstruction surgeons. An insufficient periprosthetic bone stock may predispose to migration, early mechanical failure, and major problems in revision surgery. We used computed tomography (CT)-assisted osteodensitometry in two prospectively analyzed cohorts after cemented (n ¼ 21) versus noncemented (n ¼ 23) cup fixation. Periacetabular BD (mgCaHa/mL) was determined in five CT scans cranial and five CT scans at the level of the cup 10 days and 26 months postoperatively. For press-fit cups BD decreased significantly in all CT cans except in four out of the five scans of cortical bone cranial to the cup. The decrease was highest for cancellous bone ventral to the cup (À45 to À53%). After cemented cup fixation, significant cortical BD decrease was seen ventral to the cup (À11 to À20%). Cancellous BD decrased only ventral (À21 to À31%) and in two scans cranial (À11 and À12%) to the cup. The modes of load transfer between cemented and uncemented cups differ fundamentally. Cemented cups especially prevent the loss of cancellous bone of the acetabulum while also cortical BD loss was significantly lower in most CT scans surrounding the cemented cup compared to the press-fit component. Long-term results are required to prove whether third-generation cementing technique protects periprosthetic BD and thereby improve implant survival. Keywords: osteodensitometry; computed tomography; total hip arthroplasty; acetabulum; load transfer Bone is a highly organized tissue that reacts to mechanical load in a typical stress related pattern according to Wolff's law. 1 In the last century increasing knowledge of load transfer mechanisms and stress distribution patterns after total hip replacements was provided. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Most of these studies have focussed on stress shielding mechanisms after femoral stem implantation. [2][3][4][5][6]10 The most common technique to study bone density (BD) changes is dual X-ray absorptiometry (DXA), which is a reproducible two-dimensional measurement technique. [2][3][4][5][6][7]11,[15][16][17] To allow a differentiated three-dimensional analysis of cortical and cancellous bone structures after THA in vivo we have introduced a novel method of CT-assisted osteodensitometry. 9,10,13,14 In a previous study we have provided clear evidences for the reproducibility and validity of our method. 9 Opposed to DXA CT-assisted osteodensitometry allows the separate analysis of cortical and cancellous BD surrounding the prosthesis, which might be a potential advantage in studying mechanical load transfer mechanisms to the ilium after total hip arthroplasty. 13,14 A DXA based study by Sabo et al. 11 showed a decrease of periacetabular BD 24 months after implantation of a rigid press fit cup. T...