Objectives. Healing in cancellous metaphyseal bone might be different from
midshaft fracture healing due to different access to mesenchymal
stem cells, and because metaphyseal bone often heals without a cartilaginous
phase. Inflammation plays an important role in the healing of a
shaft fracture, but if metaphyseal injury is different, it is important
to clarify if the role of inflammation is also different. The biology
of fracture healing is also influenced by the degree of mechanical
stability. It is unclear if inflammation interacts with stability-related
factors. Methods. We investigated the role of inflammation in three different models:
a metaphyseal screw pull-out, a shaft fracture with unstable nailing
(IM-nail) and a
There is no diagnostic, non-invasive method for the early detection of loosening after total hip arthroplasty. In a pilot study, we have analysed two serum markers of bone remodelling, procollagen I C-terminal extension peptide (PICP) and cross-linked N-terminal telopeptide (NTx), as well as the diagnostic performance of NTx for the assessment of osteolysis. We recruited 21 patients with loosening (group I), 18 with a well-fixed prosthesis (group II) and 17 at the time of primary arthroplasty for osteoarthritis (OA) (group III). Internal normal reference ranges were obtained from 30 healthy subjects (group IV). The serum PICP level was found to be significantly lower in patients with OA and those with loosening, when compared with those with
Objectives. Intramedullary fixation is considered the most
We have investigated whether the presence of polyethylene (PE) alone is sufficient to cause an aggressive periprosthetic tissue response, or whether certain mechanical interface conditions can allow bone to grow while in the presence of PE. An experimental implant was loaded in the presence and absence of particulate PE under
The pathogenesis of aseptic loosening of total joint prostheses is not clearly understood. Two features are associated with loosened prostheses, namely, particulate debris and movement of the implant. While numerous studies have evaluated the cellular response to particulate biomaterials, few have investigated the influence of movement of the implant on the biological response to particles. Our aim was therefore to test the hypothesis that excessive mechanical stimulation of the periprosthetic tissues induces an inflammatory response and that the addition of particulate biomaterials intensifies this. We allocated 66 adult Beagle dogs to four groups as follows:
This study evaluated the effect on movement under load of three different techniques for re-attachment of the tuberosities of the humerus using test sawbones. In the first, the tuberosities were attached both to the shaft and to each other, with one cerclage suture through the anterior hole in the prosthesis. The second technique was identical except for omission of the cerclage suture and in the third the tuberosities were attached to the prosthesis and to the shaft. An orthogonal photogrammetric system allowed all segments to be tracked in a 3D axis system. The humeri were incrementally-loaded in abduction, and the 3D linear and angular movements of all segments were calculated. Displacement between the tuberosities and the shaft was measured. The first and second techniques were the most
We developed an in vivo model of the attachment of a patellar tendon to a metal implant to simulate the reconstruction of an extensor mechanism after replacement of the proximal tibia. In 24 ewes, the patellar tendon was attached to a hydroxyapatite (HA)-coated titanium prosthesis. In 12, the interface was augmented with autograft containing cancellous bone and marrow. In the remaining ewes, the interface was not grafted. Kinematic gait analysis showed nearly normal function of the joint by 12 weeks. Force-plate assessment showed a significant increase in functional weight-bearing in the grafted animals (p = 0.043). The tendon-implant interface showed that without graft, encapsulation of fibrous tissue occurred. With autograft, a developing tendon-bone-HA-implant interface was observed at six weeks and by 12 weeks a layered tendon-fibrocartilage-bone interface was seen which was similar to a direct-type enthesis. With
We
We observed the healing process under rigid external fixation after Salter-Harris type-1 or type-2 physeal separation at the proximal tibia in immature rabbits. Metaphyseal vessels grew across the gap with little delay; the site of separation then came to lie in the metaphysis and was bridged by endochondral ossification. Union was achieved within two days in all rabbits. Progression of endochondral ossification repaired the separated physis, thus showing ‘primary healing of physeal separation’. This depends on accurate reduction and
We have used in vivo microdialysis to monitor postoperative physiological events in the synovial membrane after arthroscopy. The levels of lactate were significantly higher in the synovial membrane than in the reference tissue (subcutaneous fat) and there was a significant increase in lactate after operation. Blood flow, measured as the ethanol ratio, was
We measured the levels of cobalt and chromium in the serum in three groups of patients after uncemented porous-coated arthroplasty. Group 1 consisted of 14 consecutive patients undergoing revision for aseptic loosening. Group 2 comprised 14 matched patients in whom the arthroplasty was
In ten male rats we inserted ceramic ‘drawing-pin’ implants in weight-bearing positions within the right proximal tibia. Two animals were killed 6 weeks after surgery and two more 14 weeks after surgery. The remaining six received intra-articular injections of either high-density polyethylene (4 rats) or saline (2 rats) at 8, 10 and 12 weeks after surgery. These animals were killed two weeks after the last injection. Histological examination of the bone-implant interface in the control animals showed appositional bone growth around the implant at both 6 and 14 weeks. Polyethylene, but not saline, caused a chronic inflammatory response with numerous foreign-body giant cells in periprosthetic tissues. Our model of a
We examined whether somatosensory evoked potentials (SEPs) were detectable after direct electrical stimulation of injured, reconstructed and normal anterior cruciate ligaments (ACL) during arthroscopy under general anaesthesia. We investigated the position sense of the knee before and after reconstruction and the correlation between the SEP and instability. We found detectable SEPs in all ligaments which had been reconstructed with autogenous semitendinosus and gracilis tendons over the past 18 months as well as in all cases of the normal group. The SEP was detectable in only 15 out of 32 cases in the injured group, although the voltages in the injured group were significantly lower than those of the controls. This was not the case in the reconstructed group. The postoperative position sense in 17 knees improved significantly, but there was no correlation between it and the voltage. The voltage of
We used a rat model in vivo to study the effects of the concentration of polyethylene particles on the bone-implant interface around
Coating titanium alloy implants with titanium nitride (TiN) by the method of Powder Immersion Reaction Assisted Coating (PIRAC) produces a
We analysed synovial fluid from 88 hips, 38 with osteoarthritis and 12 with well-functioning and 38 with loose hip prostheses. The levels of TNF-α, IL-1ß (71 hips) and IL-6 (45 hips) were measured using the ELISA technique. Joints with well-functioning or loose prostheses had significantly increased levels of TNF-α compared with those with osteoarthritis. Hips with aseptic loosening also had higher levels of IL-1ß but not of IL-6 compared with those without an implant. The levels of TNF-α and IL-1ß did not differ between hips with
To investigate the effect of instability on the remodelling of a minor articular surface offset, we created a 0.5 mm coronal step-off of the medial femoral condyle in 12 New Zealand white rabbits and transected the anterior cruciate ligament (ACL). A control group of 12 rabbits had only ACL resection and the opposite knee was used as the non-operated control. The osteoarthritic changes at 6, 12 and 24 weeks after surgery were evaluated histologically. In addition, changes in the immunological detection of 3-B-3(-) and 7-D-4 chondroitin-6-sulphate epitopes were determined because of the previous association of such changes with repair of cartilage and early osteoarthritis. In the instability/step-off group there was rapidly progressing focal degeneration of cartilage on the high side of the defect, not seen in previous step-off studies in
The clinical use of hydroxyapatite (HA) coating is controversial especially in regard to the long-term performance of the coating and the effects of resorption. In each of 15 consenting patients we inserted two implants, coated with either HA or fluorapatite (FA) into the iliac crest. They were harvested at a mean of 13.6 ± 0.6 months after surgery. Histological examination showed that bone ongrowth on the HA-coated implants was significantly greater (29%) than that on the FA-coated implants. When bone was present on the coating surface the HA coating was significantly thicker than the FA coating. When bone marrow was present, the HA coating was significantly thinner than the FA coating. The reduction in coating thickness when covered by bone or bone marrow was 23.1 ± 9.7 μm for HA and 5.1 ± 1.7 μm for FA (p <
0.01) suggesting that FA is more