Introduction: NSAID’s are routinely used as either pain-killer or in prevention of heterotopic bone formation (HBF) after total hip replacement (THR). Experimental animal studies have in two decades shown NSAID’s to influence bone remodelling, and thereby also to reduce fixation and bone healing round non-cemented implants. Clinical studies have, however, non been able to demonstrate these observations, too. This may be due a low power in such studies with only few observations. The present study present results from The Danish Hip Arthroplasty Register (DHR) on the effect of NSAID’s to revision of cemented implants due aseptic loosening.

Materials and Methods: DHR was established January 1, 1995 and covers all Danish clinics. All report both primary and revision cases to a central database. Every Danish citizen have an unique civil register number - making it possible to follow both primary and revision cases and to investigate survival due various circumstances. Cox’s regression analysis to estimate the relative risks (RR) of revision and data are presented with 95% confidence intervals.

Results: During the period 1995–2006 total 64.725 primary THR’s were recorded in DHR. Of these 8.531 cases had prophylactic NSAID after surgery in prevention of HBF. Total 409 hips (4.8%) of this population undergoing revision THR had been treated with NSAID’s after surgery. In contrast, 2.536 (4.3%) undergoing revision in the population had no NSAID’s. Overall the risk for revision for any reason was reduced for patients treated with NSAID’s (RR = 0.88 (0.79–0.98) p=0.02). This was even more significant in revision due to aseptic loosening (RR = 0.76 (0.64–0.90) p< 0.01). Subgroup analysis showed that the reduction was in the cemented THR (RR = 0.82 (0.70–0.95) p=0.01) with a further more significant sign in revision due aseptic loosening (RR = 0.69 (0.55–0.87) p< 0.01). In contrast there was no differences in cementless THR neither in revision for any reason (RR = 1.19 (0.86–1.63) p=0.30) nor for aseptic loosening (RR = 1.72 (0.87–3.43) p=0.12).

Discussion and Conclusion: The present investigation from the DHR is a good example of what can be evaluated from a register, and never possibly concluded from standard clinical studies. The results demonstrate that NSAID’s administrated in order to prevent HBF after primary THR surprisingly did not increase the risk of revision in non-cemented implants, but in contrast did reduce the risk for revision in cemented THR. The reason for this reduction is speculated, and be relate to the phenomenon that NSAID’s did not only influence the osteoblastic activity, but also the osteoclasts and thereby prevent early postoperative bone degradation after cemented THR where heat from the bone-cement may impose devascu-larisation of vital bone near the implant.

Introduction: Poor long-time results in patients with Legg-Calvé-Perthes disease (LCP) are most often due to degenerative hip disease. The purpose of this study was to investigate if patients with LCP have an increased rate of total hip replacement (THR) compared to sex- and age-matched persons.

Material and Methods: 167 LCP patients presented to our institution from 1941 to 1962. All patients were treated conservatively by a Thomas splint. Retrospectively medical records and radiographs were retrieved. Data from the Danish Hip Replacement Register and the Registries of the National Board of Health were collected to get information regarding the number of the patients who had a THR.

Radiographs of sex- and age-matched controls for the follow-up group were obtained from The Copenhagen City Heart Study.

The following criteria for exclusion were applied

emigrated persons,

135 patients (156 hips) were enrolled in this study and 32 patients (35 hips) were excluded.

Results: 20 hips out of 156 hips in patients with LCP have had a THR. Mean age at operation for the women was 50 years and 44 years for the men. None of the sex- and age-matched persons have had a THR.

Conclusion: LCP patients had a significantly higher risk of THR surgery compared to sex- and age-matched control persons, (p< 0.00 [OR= 49.0 (CI 8.2-infinite)]).

Introduction: The purpose of this prospective randomized is to compare a resorbable versus a non resorbable CR regarding restrictor migration and cementation quality in cemented THA.

Materials and Methods: 91 patients were randomized to either a resorbable Imset(Aesculap) or a non-resorbable Hardinge (De Puy) CR.

Surgery and postoperative regime were identical in the two groups.

CR-migration during cementation and stem insertion was calculated and the quality of cementation was evaluated on the post-operative X-ray according to the criteria by Barrack et Al(1)

Mean values are presented with 95% CI. An unpaired T-test was used to analyse the differences in CR migration and the quality of cementation quality.

Results: The mean CR-migration in the Imset group was 9.8mm(CI: 6.1mm-13.5mm) compared with 3.7mm (CI: 1.8mm-5.5mm) in the Hardinge group (P=0.042)

Regarding quality of cementation the mean value in the Imset group were 2.8 which was significantly better in the Hardinge group=2.1 (P=0.003)

Conclusion: The resorbable CR was associated with significantly greater migration and inferior quality of cementation compared with our standard non-resorbable restrictor.

Introduction: We studied the survival of primary total hip arthroplasty (THA) in patients undergoing surgery because of rheumatoid arthritis (RA) and compared our results to the survival of primary THA in patients undergoing surgery because of osteoarthritis (OA). Furthermore, we evaluated the effect of primary THA-survival in RA-patients concerning multiple confounders such as age, gender, comorbidity, and cemented/uncemented prosthesis.

Material and Methods: Using the Danish Hip Arthroplasty Register we gathered info concerning 1.302 primary THA’s in 1.106 RA-patients and 41.848 primary THA’s in 35.729 OA-patients. These patients underwent surgery from 1995 to 2004. Using the Cox regression model we estimated the relative risk (RR) for revision due to aseptic loosening, other reasons, and all reasons and adjusted for above mentioned confounders.

Results: The adjusted RR’s for cup-revision of primary THA’s in patients with RA (compared to OA) were 1.22 (aseptic loosening − 95% Confidence Interval (CI) 0.75–1.99), 0.90 (other causes for revision − 95% CI 0.61–1.32), and 1.00 (all revisions − 95% CI 0.74–1.35). For the stem the RR’s were 0.50 (aseptic loosening − 95% CI 0.25–0.99), 0.58 (other causes for revision − 95% CI 0.35–0.95), and 0.54 (all revisions − 95% CI 0.36–0.80). RR for all revisions (both cup and stem) was 0.83 (95% CI 0.64–1.09). The RAsubanalysis showed an increased RR (all revisions) for men compared to women (RR 2.60; 95% CI 1.19–5.66). No significant result concerning all revisions for age, comorbidity, and cemented/ uncemented prosthesis was found. The mean follow-up was 5,4 years for RA and 4,8 years for OA.

Conclusion: The survival of primary THA’s in RA could not be associated with any clearly overall increased risk of revision when compared to OA. However, male gender seems to be a risk factor for undergoing revision-THA in the RA-subgroup.

Resurfacing THA is claimed to transfer stress naturally to the femur neck and preserve proximal femoral bone mass postoperatively. DXA is an established method in estimating BMD around a standard THA, but due to the anteversion of the femur neck, rotation could affect the size of the neck-regions and thereby the BMD measurements around a RTHA. To our knowledge, this is the first study to analyze the effects of hip rotation on BMD in the femoral neck around a RTHA.

We scanned the femoral neck of 15 patients twice in each position of 15° inward, 0° and 15° outward rotation, and analyzed BMD in a single and a six-region model. CVs were calculated for BMD in the same position as well as between different positions.

For double measurements in the same position we found mean CVs of 3.1% (range 2.5% – 3.7%) and 4.6% (range 2.2% – 8.6%) in the one- and six-region models, respectively. When the 15° outward position was excluded, the CVs decreased to 2.8% and 4.0%. With rotation, the mean CVs rose to 5.4% (range 3.2%–7.2%) and 11.8% (range 2.7% – 36.3%). This effect was most pronounced in the 6-region model, predominantly in the lateral and distal parts of the femoral neck, where the change was significantly different from the fixated position. For the single-region model 15° rotation could be allowed without compromising the precision.

We conclude that rotation adversely affects the precision of BMD measurements around a RTHA, but in the single-region model smaller rotations can be allowed.

With the hip fixated the six-region model produces low CVs, acceptable for longitudinal studies. For maximal topographical detail we prefer the six-region model and recommend that future longitudinal DXA studies, including RTHA, be performed standardised, Preferably, with the hip in the neutral or internal rotation.

There is a great need for suitable large animal models that closely resemble osteoporosis in humans, and that they have adequate bone size for bone prosthesis and biomaterial research. This study aimed to investigate effects of a 7 month glucocorticoid (GC) treatment alone without ovariectomy on the properties of sheep cancellous bone.

Eighteen female sheep were randomly allocated into 3 groups: group 1 (GC-1) received GC (0.60mg/kg/day methylprednisolone) 5 days weekly for 7 months; group 2 (GC-2) received the same treatment regime for 7 months, and further observed for 3 months without GC; and group 3 served as the control group, and left untreated for 7 months. The sheep received restricted diet.

After 7 months of GC treatment. Cancellous bone volume fraction of the 5th lumbar vertebra in the GC-1 group was reduced by −35%, trabecular thickness by −28%, and changed from typical plate structure to a combination of plate and rod structure with increased connectivity by 202%. Bone strength was reduced by 52%. Bone formation marker, serum osteocalcin of GC-1, was reduced by 71% at 7 months, but recovered with an increase of 45% at 10 month in the GC-2 group. Similar trends were also seen in the femur and tibia. At 10 months, the GC-2 group had microarchitectural and mechanical properties similar to the level of the control sheep.

We have demonstrated in this study that 7 month high-dose GC on bone density and microarchitecture are comparable with those observed in human after long-term GC treatment. Moreover, we have shown that the bone quality with regard to strength and microarchitecture recovers after 3 months further observation without GC. This suggests that a prolonged administration of GC is needed for long-term observation to keep osteopenic bone. The model will be useful in pre-clinical studies.

Introduction: Periacetabular osteotomy (PAO) is a major orthopaedic surgical procedure which may be associated with a significant blood loss and complications. We have compared the perioperative blood loss and complications using two different approaches – The modified iliofemoral (MI) and ilioinguinal (II) for PAO.

MATERIALS AND Methods: 92 PAO’s in 80 patients (54 females; 26 males), with dysplastic hip joints, operated at Odense University Hospital with the Bernese method, between 2003 and Feb. 2006, using the MI or the II were included. The MI include no release of the tensor fascia lata, sartorius or rectus femoris.

The procedures were reviewed with primary focus on perioperative blood loss, length of surgery and neurovascular complications. Patients who underwent combined surgery of acetabulum and femur were excluded.

Data are presented as mean with 95% confidence interval (CI) in brackets.

Results: The MI approach was used in 65 and the II in 27 PAO’s. Average time for surgery in the MI group was 88 min (95% CI: 83–94) and in the II group 106 min (95% CI: 97–114), (P=0.0007). The intraoperative blood loss in the MI group was 571 ml (95% CI: 489–654) compared with 518 ml (95% CI: 387–649) in the II group (P=0.49). However, postoperatively, the hemoglobin concentration was 7.1 (95% CI: 6.9–7.3) in the MI group compared with 6.6 (95% CI: 6.1–6.8) in the II group (P=0.002).

The MI group had 1 case of major arterial bleeding, however no blood transfusion. The II group had 2 cases of arterial thrombosis and one transient sciatic nerve palsy. One patient received blood transfusion.

CONCLUSION: In this study, the MI approach was proved to be significantly faster than the II, however no significant difference was found in intraoperative blood loss, but the hemoglobin fell significantly less in the MI compared with the II group. The II approach was associated with 3 major complication compared with one in the MI.

Introduction: We state that preserving the hip might be optimum in treatment of patients with dislocated femoral fractures presuming that the fractures unite. In order to be able to choose the right treatment for the patient with a dislocated femoral neck fracture, we have hypothesized that lack of blood flow and development of ischemia might have influence on outcome of the osteosynthesis. In this study we have established microdialysis and laser Doppler measurements in patients with a dislocated femoral neck fractures.

Methods and materials: 14 patients with dislocated fractures of the femoral neck were osteosynthezised by using 2 cannulated screws. During the operation blood flow was measured with laser Doppler in order to detect pulsatile flow, and microdialysis was performed to detect ischemia. Both measurements were made in the femoral head and with the greater trochanter as control. The parameters measured were lactate, pyruvate, glycerol and glucose concentrations. Lactate/pyruvate ratio was calculated in order to estimate ischemia defined as a value over 25. Measurements were done after the fracture was reduced, and during osteosynthesis. Data are presented as mean with standard deviation (SD) in brackets.

Results: In all but one patient laser Doppler showed pulsatile flow in the greater trochanter, whereas 8 patients had flow in the femoral head. In the greater trochanter the mean lactate/pyruvate ratio was 11 (7.55), in the femoral heads the mean ratio was 27.99 (21.24) although 4 heads did not show ischemia (p=0.0004). The values for glucose in the trochanter and the femoral head are 2.47 mM(1.92) and 1.53 mM(1.37) respectively, and for glycerol 0.16 mM(0.09) and 0.25 mM(0.22). During the observation period two patients were reoperated, one with hemiarthroplasty 3 months after the osteosynthesis due to failure of the osteosynthesis; the patient had flow measured by laser Doppler and ischemia with microdialysis. One had a resection arthroplasty due to infection.

Conclusion: To our knowledge it is the first time that laser Doppler and microdialysis has been established in patients with dislocated femoral neck fractures. Further studies will have to evaluate whether laser Doppler and microdialysis in combination with fracture related parameters can predict failure of the osteosynthesis. This might enable us to establish a treatment algorithm to be used in the daily clinic.

Background: We examined the role of the geometry of acetabulum in the development of osteoarthritis in young men. Contrary to previous studies we evaluated the significance of the anterior, posterior and total coverage of the femoral head, the influence of the femoral neck and the consequence of acetabular retroversion on standardized x-rays.

Material and Methods: Men (n=78) aged 26–55 years (case-group) were selected from the Danish Hip Arthroplasty Register. This group was compared to a control-group (n=78) selected from men of the same age group received as trauma patients. Anterior/posterior pelvic radiographs were evaluated taking into account the degree of pelvic rotation and tilt.

Results: Femoral head coverage, femoral head-neck ratio and centre edge angle were significantly smaller in the case-group, acetabular index angle and modified ACM-angle were significantly bigger. Anterior, posterior and total coverage of femoral head showed no difference. The frequency of acetabular retroversion was greater among cases.

Interpretation: Osteoarthritis of young men is associated with a small superior acetabular coverage, a steep acetabular roof, a small acetabular depth, a thickened femoral neck and acetabular retroversion.

Impacted bone allograft is often used in revision joint replacement. Hydroxyapatite granules have been suggested as a substitute or to enhance morcellised bone allograft. We hypothesised that adding osteogenic protein-1 to a composite of bone allograft and non-resorbable hydroxyapatite granules (ProOsteon) would improve the incorporation of bone and implant fixation. We also compared the response to using ProOsteon alone against bone allograft used in isolation. We implanted two non-weight-bearing hydroxyapatite-coated implants into each proximal humerus of six dogs, with each implant surrounded by a concentric 3 mm gap. These gaps were randomly allocated to four different procedures in each dog: 1) bone allograft used on its own; 2) ProOsteon used on its own; 3) allograft and ProOsteon used together; or 4) allograft and ProOsteon with the addition of osteogenic protein-1.

After three weeks osteogenic protein-1 increased bone formation and the energy absorption of implants grafted with allograft and ProOsteon. A composite of allograft, ProOsteon and osteogenic protein-1 was comparable, but not superior to, allograft used on its own.

ProOsteon alone cannot be recommended as a substitute for allograft around non-cemented implants, but should be used to extend the volume of the graft, preferably with the addition of a growth factor.

We examined the association between patient-related factors and the risk of initial, short- and long-term implant failure after primary total hip replacement. We used data from the Danish Hip Arthroplasty Registry between 1 January 1995 and 31 December 2002, which gave us a total of 36 984 patients. Separate analyses were carried out for three follow-up periods: 0 to 30 days, 31 days to six months (short term), and six months to 8.6 years after primary total hip replacement (long term). The outcome measure was defined as time to failure, which included re-operation with open surgery for any reason.

Male gender and a high Charlson co-morbidity index score were strongly predictive for failure, irrespective of the period of follow-up. Age and diagnosis at primary total hip replacement were identified as time-dependent predictive factors of failure. During the first 30 days after primary total hip replacement, an age of 80 years or more and hip replacement undertaken as a sequela of trauma, for avascular necrosis or paediatric conditions, were associated with an increased risk of failure. However, during six months to 8.6 years after surgery, being less than 60 years old was associated with an increased risk of failure, whereas none of the diagnoses for primary total hip replacement appeared to be independent predictors.

Introduction: The main problem using first generation Gamma-nail in the treatment of intertrochanteric fractures has been a high frequency of intra- and postoperative femoral fractures. The TGN was thought to represent an improvement in design and potentially a less invasive treatment.

Material and methods: 146 fractures were randomised prospectively to either DHS or TGN. The 2 groups were comparable regarding age, gender and fracture type (AO). Follow-up was carried out after 4 and 12 months.

Results: Average operation time in the TGN group was 63 min (SD=30min) and 48 min (SD=23) in the DHS group (p=0.0016). There was no difference in intra-operative blood loss, need for blood transfusion, length of hospital stay or mortality. Two femoral fractures occurred postoperatively in the TGN group. At follow-up 12 patients in the TGN and 6 patients in the DHS group had had a reoperation (p> 0.05). Six reoperations in the TGN group and 3 in the DHS group resulted in preservation of the hip joint. The remaining patients had an arthroplasty or a Girdlestone resection. Poor reduction and/or positioning of the implant was significantly correlated to the risk of reoperation (p< 0.001). Specific technical errors could be identified among 3 fractures in the TGN group leading to reoperation. Any correlation between fracture type and reoperation could not be demonstrated.

Conclusion: In this study operation time was significantly longer in the TGN group. Among other variables no significant differences could be demonstrated. In our department, with a high number of residents performing these operations, the DHS will continue to be the standard implant. Whether the TGN has a place in a subgroup of intertrochanteric fractures, operated by specialized surgeons, needs further investigation.

Introduction/Aims: Initial implant stability is crucial for long-term implant survival. A new surgical technique, compaction, has increased in vivo stability of implants inserted with pressþt. However, gaps often exist in total joint replacements between the implant bone bed and the implant. Therefore, we examined in a gap model whether the compaction technique would increase þxation of hydroxylapatite (HA) implants when compared with the conventional drilling technique. Methods: HA coated titanium implants (diameter 6 mm) were inserted bilaterally in the proximal humerus of 7 dogs for 2 weeks. The implant cavity was randomized to either drilling with an 8 mm drill or to compaction by radial enlarging an initial 5 mm drill hole to 8 mm. Implants were tested to failure by push-out test, and histomorphometry was performed. Data are presented as medians with interquartile range in brackets. The Wilcoxon Signed Ranked Test tested differences between compaction and drilling. P-values < 0.05 were considered signiþcant (*).

Conclusion: In this gap model, compaction signiþcantly increased mechanical and histological þxation of HA coated implants.

We have studied the beneficial effects of a hydroxyapatite (HA) coating on the prevention of the migration of wear debris along the implant-bone interface. We implanted a loaded HA-coated implant and a non-coated grit-blasted titanium alloy (Ti) implant in each distal femoral condyle of eight Labrador dogs. The test implant was surrounded by a gap communicating with the joint space and allowing access of joint fluid to the implant-bone interface. We injected polyethylene (PE) particles into the right knee three weeks after surgery and repeated this weekly for the following five weeks. The left knee received sham injections. The animals were killed eight weeks after surgery. Specimens from the implant-bone interface were examined under plain and polarised light.

Only a few particles were found around HA-coated implants, but around Ti implants there was a large amount of particles. HA-coated implants had approximately 35% bone ingrowth, whereas Ti implants had virtually no bone ingrowth and were surrounded by a fibrous membrane.

Our findings suggest that HA coating of implants is able to inhibit peri-implant migration of PE particles by creating a seal of tightly-bonded bone on the surface of the implant.

We inserted two hydroxyapatite (HA)-coated implants with crystallinities of either 50% (HA-50%) or 75% (HA-75%) bilaterally into the medial femoral condyles of the knees of 16 dogs. The implants were allocated to two groups with implantation periods of 16 and 32 weeks. They were weight-bearing and subjected to controlled micromovement of 250 μm during each gait cycle. After 16 weeks, mechanical fixation of the HA-50% implants was increased threefold as compared with the HA-75% implants. After 32 weeks there was no difference between HA-50% and HA-75%. Fixation of HA-75% increased from 16 to 32 weeks whereas that of HA-50% was unchanged. HA-50% implants had 100% more bone ingrowth than HA-75% implants after 16 weeks. More HA coating was removed on HA-50% implants compared with HA-75% implants after both 16 and 32 weeks. No further loss of the HA coating was shown from 16 to 32 weeks.

Our study suggests that the crystallinity of the HA coating is an important factor in its bioactivity and resorption during weight-bearing conditions. Our findings suggest two phases of coating resorption, an initial rapid loss, followed by a slow loss. Resorbed HA coating was partly replaced by bone ingrowth, suggesting that implant fixation will be durable.

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 stable than HA against resorption by bone marrow.

The findings suggest that in man the osteoconductive properties of HA coating are superior to those of FA. Resorption rates for both coatings were approximately 20% of the coating thickness per year. Bone ongrowth appears to protect against resorption whereas bone marrow seems to accelerate resorption. No adverse reaction was seen in the surrounding bone.

Bone growth into cementless prosthetic components is compromised by osteoporosis, by any gap between the implant and the bone, by micromotion, and after the revision of failed prostheses. Recombinant human transforming growth factor-β1 (rhTGF-β1) has recently been shown to be a potent stimulator of bone healing and bone formation in various models in vivo.

We have investigated the potential of rhTGF-β1, adsorbed on to weight-loaded tricalcium phosphate (TCP) coated implants, to enhance bone ongrowth and mechanical fixation. We inserted cylindrical grit-blasted titanium alloy implants bilaterally into the weight-bearing part of the medial femoral condyles of ten skeletally mature dogs. The implants were mounted on special devices which ensured stable weight-loading during each gait cycle. All implants were initially surrounded by a 0.75 mm gap and were coated with TCP ceramic.

Each animal received two implants, one with 0.3 μg rhTGF-β1 adsorbed on the ceramic surface and the other without growth factor. Histological analysis showed that bone ongrowth was significantly increased from 22 ± 5.6% bone-implant contact in the control group to 36 ± 2.9% in the rhTGF-β stimulated group, an increase of 59%. The volume of bone in the gap was increased by 16% in rhTGF-β1-stimulated TCP-coated implants, but this difference was not significant. Mechanical push-out tests showed no difference in fixation of the implant between the two groups. Our study suggests that rhTGF-β1 adsorbed on TCP-ceramic-coated implants can enhance bone ongrowth.

We recorded inter- and intra-observer variations in the classification of ankle fractures by the Lauge Hansen and Weber systems. Radiographs of 94 patients were classified independently by four observers. The observer variation was calculated by kappa statistics, which corrects the obtained values for the agreement expected by chance. There was an acceptable level of agreement for the overall classification into both systems. For the staging of supination-adduction and supination-eversion fractures in the Lauge Hansen system the agreement was poor. The results indicate that future classification systems should be subject to reliability analysis before they are accepted.