There have been recent reports linking alendronate and a specific pattern of subtrochanteric insufficiency fracture. We performed a retrospective review of all subtrochanteric fractures admitted to our institution between 2001 and 2007. There were 20 patients who met the inclusion criteria, 12 of whom were on long-term alendronate. Alendronate-associated fractures tend to be bilateral (Fisher’s exact test, p = 0.018), have unique radiological features (p <
0.0005), be associated radiologically with a pre-existing ellipsoid thickening of the lateral femoral cortex and are likely to be preceded by prodromal pain. Biomechanical investigations did not suggest overt metabolic bone disease. Only one patient on alendronate had osteoporosis prior to the start of therapy. We used these findings to develop a management protocol to optimise fracture healing. We also advocate careful surveillance in individuals at-risk, and present our experience with screening and prophylactic fixation in selected patients.
We have evaluated the extent to which diabetes affects the revision rate following total hip replacement (THR). Through the Danish Hip Arthroplasty Registry we identified all patients undergoing a primary THR (n = 57 575) between 1 January 1996 and 31 December 2005, of whom 3278 had diabetes. The presence of diabetes among these patients was identified through the Danish National Registry of Patients and the Danish National Drug Prescription Database. We estimated the relative risk for revision and the 95% confidence intervals for patients with diabetes compared to those without, adjusting for the confounding factors. Diabetes is associated with an increased risk of revision due to deep infection (relative risk = 1.45 (95% confidence interval 1.00 to 2.09), particularly in those with type 2 diabetes (relative risk = 1.49 (95% confidence interval 1.02 to 2.18)), those with diabetes for less than five years prior to THR (relative risk = 1.69 (95% confidence interval 1.24 to 2.32)), those with complications due to diabetes (relative risk = 2.11 (95% confidence interval 1.41 to 3.17)), and those with cardiovascular comorbidities prior to surgery (relative risk = 2.35 (95% confidence interval 1.39 to 3.98)). Patients and surgeons should be aware of the relatively elevated risk of revision due to deep infection following THR in diabetes particularly in those with insufficient control of their glucose level.
We used a biodegradable mesh to convert an acetabular defect into a contained defect in six patients at total hip replacement. Their mean age was 61 years (46 to 69). The mean follow-up was 32 months (19 to 50). Before clinical use, the strength retention and hydrolytic in vitro degradation properties of the implants were studied in the laboratory over a two-year period. A successful clinical outcome was determined by the radiological findings and the Harris hip score. All the patients had a satisfactory outcome and no mechanical failures or other complications were observed. No protrusion of any of the impacted grafts was observed beyond the mesh. According to our preliminary laboratory and clinical results the biodegradable mesh is suitable for augmenting uncontained acetabular defects in which the primary stability of the implanted acetabular component is provided by the host bone. In the case of defects of the acetabular floor this new application provides a safe method of preventing graft material from protruding excessively into the pelvis and the mesh seems to tolerate bone-impaction grafting in selected patients with primary and revision total hip replacement.
We describe the survivorship of the Exeter femoral component in a District General Hospital. Between 1994 and 1996, 230 Exeter Universal cemented femoral components were implanted in 215 patients who were reviewed at a mean of 11.2 years (10 to 13). We used one acetabular implant, the Elite Ogee component, in 218 of the 230 hips. During the period of this study 76 patients (79 hips) died. Of the remaining 139 patients (151 hips), 121 were able to attend for radiological analysis at a minimum of ten years. One patient was lost to follow-up. No femoral component was revised for aseptic loosening. Three hips were revised for deep infection and six acetabular components required revision, four for loosening and two for recurrent dislocation. Taking the ‘worst-case scenario’ including the one patient lost to follow-up, the overall survival rate was 94.4% at 13 years. Our results confirm excellent medium-term results for the Exeter Universal femoral component, implanted in a general setting. The excellent survival of this femoral component, when used in combination with the Ogee acetabular component, suggests that this is a successful pairing.
Children presenting with Perthes’ disease before their sixth birthday are considered to have a good prognosis. We describe 166 hips in children in this age group. The mean age at onset of the disease was 44 months (22 to 72). Mild forms (Catterall I and II) were treated conservatively and severe forms (Catterall III and IV) either conservatively or operatively. The aim of the former treatment was to restrict weight-bearing. Operative treatment consisted of innominate osteotomy and was indicated by a Conway type-B appearance on the bone scan. All the patients were followed to skeletal maturity with a mean follow-up of 11 years (8 to 15). The end results were evaluated radiologically using the classifications of Stulberg and Mose. A total of 50 hips were Catterall grade-I or grade-II, 65 Catterall grade-III and 51 Catterall grade-IV. All hips with mild disease had a good result at skeletal maturity. Of the hips with severe disease 78 (67.3%) had good (Stulberg I and II), 26 (22.4%) fair (Stulberg III) and 12 (10.3%) poor results (Stulberg IV and V). Of the Catterall grade-III hips 38 were treated conservatively of which 31 (81.6%) had a good result, six (15.8%) a fair and one (2.6%) a poor result. Operative treatment was carried out on 27 Catterall grade-III hips, of which 21 (77.8%) had a good, four (14.8%) a fair and two (7.4%) a poor result. By comparison conservative treatment of 19 Catterall grade-IV hips led to ten (52.7%) good, seven (36.8%) fair and two (10.5%) poor results. Operative treatment was carried out on 32 Catterall grade-IV hips, of which 16 (50.0%) had a good, nine (28.1%) a fair and seven (21.9%) a poor result. We confirm that the prognosis in Perthes’ disease is generally good when the age at onset is less than six years. In severe disease there is no significant difference in outcome after conservative or operative treatment (p >
0.05). Catterall grade-III hips had a better outcome according to the Stulberg and Mose criteria than Catterall grade-IV hips, regardless of the method of treatment.
Carbonate-substituted hydroxyapatite (CHA) is more osteoconductive and more resorbable than hydroxyapatite (HA), but the underlying mode of its action is unclear. We hypothesised that increased resorption of the ceramic by osteoclasts might subsequently upregulate osteoblasts by a coupling mechanism, and sought to test this in a large animal model. Defects were created in both the lateral femoral condyles of 12 adult sheep. Six were implanted with CHA granules bilaterally, and six with HA. Six of the animals in each group received the bisphosphonate zoledronate (0.05 mg/kg), which inhibits the function of osteoclasts, intra-operatively. After six weeks bony ingrowth was greater in the CHA implants than in HA, but not in the animals given zoledronate. Functional osteoclasts are necessary for the enhanced osteoconduction seen in CHA compared with HA.
The mammalian growth plate is a complex structure which is essential for the elongation of long bones. However, an understanding of how the growth plate functions at the cellular level is lacking. This review, summarises the factors involved in growth-plate regulation, its failure and the consequence of injury. We also describe some of the cellular mechanisms which underpin the increase in volume of the growth-plate chondrocyte which is the major determinant of the rate and extent of bone lengthening. We show how living in situ chondrocytes can be imaged using 2-photon laser scanning microscopy to provide a quantitative analysis of their volume. This approach should give better understanding of the cellular control of bone growth in both healthy and failed growth plates.
This prospective study presents the ten-year (5 to 16) clinical and radiological results of 55 primary total hip replacements (THR) using a cementless modular femoral component (S-ROM). All patients had a significant anatomical abnormality which rendered the primary THR difficult. The mean Harris hip score was 36 (12 to 72) pre-operatively, 83 (44 to 100) at five years, and 85 (45 to 99) at ten years. The Western Ontario and McMaster Universities osteoarthritis index (WOMAC) and short-form (SF)-12 scores were recorded from the year 2000. The mean SF-12 score at five years after surgery was 45.24 (22.74 to 56.58) for the physical component and 54.14 (29.20 to 66.61) for the mental component. By ten years the SF-12 scores were 42.86 (21.59 to 58.95) and 51.03 (33.78 to 61.40), respectively. The mean WOMAC score at five years post-operatively was 25 (0 to 59), and at ten years was 27 (2 to 70). No femoral components were radiologically loose, although five had osteolysis in Gruen zone 1, three had osteolysis in zone 7, and two showed osteolysis in both zones 1 and 7. No osteolysis was observed around or distal to the prosthetic sleeve. No femoral components were revised, although three hips underwent an acetabular revision and two required a liner exchange. At a mean of ten years’ follow-up the S-ROM femoral component implanted for an anatomically difficult primary THR has excellent clinical and radiological results.
The deformity index is a new radiological measurement of the degree of deformity of the femoral head in unilateral Perthes’ disease. Its values represent a continuous outcome measure of deformity incorporating changes in femoral epiphyseal height and width compared with the unaffected side. The sphericity of the femoral head in 30 radiographs (ten normal and 20 from patients with Perthes’ disease) were rated blindly as normal, mild, moderate or severe by three observers. Further blinded measurements of the deformity index were made on two further occasions with intervals of one month. There was good agreement between the deformity index score and the subjective grading of deformity. Intra- and interobserver agreement for the deformity index was high. The intraobserver intraclass correlation coefficient for each observer was 0.98, 0.99 and 0.97, respectively, while the interobserver intraclass correlation coefficient was 0.98 for the first and 0.97 for the second set of calculations. We also reviewed retrospectively 96 radiographs of children with Perthes’ disease, who were part of a multicentre trial which followed them to skeletal maturity. We found that the deformity index at two years correlated well with the Stulberg grading at skeletal maturity. A deformity index value above 0.3 was associated with the development of an aspherical femoral head. Using a deformity index value of 0.3 to divide groups for risk gives a sensitivity of 80% and specificity of 81% for predicting a Stulberg grade of III or IV. We conclude that the deformity index at two years is a valid and reliable radiological outcome measure in unilateral Perthes’ disease.
We matched 78 patients with a loose cemented Charnley Elite Plus total hip replacement (THR) by age, gender, race, prosthesis and time from surgery with 49 patients with a well-fixed stable hip replacement, to determine if poor bone quality predisposes to loosening. Clinical, radiological, biomechanical and bone mineral density indicators of bone quality were assessed. Patients with loose replacements had more pain, were more likely to have presented with atrophic arthritis and to have a history of fragility fracture, narrower femoral cortices and lower peri-prosthetic or lumbar spine bone mineral density (all In this series of cemented hip replacements performed between 1994 and 1998, aseptic loosening was associated with poor bone quality. Patients with a THR should be screened for osteoporosis and have regular radiological surveillance.
New developments in osteotomy techniques and methods of fixation have caused a revival of interest of osteotomies around the knee. The current consensus on the indications, patient selection and the factors influencing the outcome after high tibial osteotomy is presented. This paper highlights recent research aimed at joint pressure redistribution, fixation stability and bone healing that has led to improved surgical techniques and a decrease of post-operative time to full weight-bearing.
We used a knee-sparing distal femoral endoprosthesis in young patients with malignant bone tumours of the distal femur in whom it was possible to resect the tumour and to preserve the distal femoral condyles. The proximal shaft of the endoprosthesis had a coated hydroxyapatite collar, while the distal end had hydroxyapatite-coated extracortical plates to secure it to the small residual femoral condylar fragment. We reviewed the preliminary results of this endoprosthesis in eight patients with primary bone tumours of the distal femur. Their mean age at surgery was 17.years (14 to 21). The mean follow-up was 24 months (20 to 31). At final follow-up the mean flexion at the knee was 102° (20° to 120°) and the mean Musculoskeletal Tumour Society score was 80% (57% to 96.7%). There was excellent osteointegration at the prosthesis-proximal bone interface with formation of new bone around the hydroxyapatite collar. The prosthesis allowed preservation of the knee and achieved a good functional result. Formation of new bone and remodelling at the interface make the implant more secure. Further follow-up is required to determine the long-term structural integrity of the prosthesis.
We investigated the effect of locally administered bisphosphonate on distraction osteogenesis in a rabbit model and evaluated its systemic effect. An osteotomy on the right tibia followed by distraction for four weeks was performed on 47 immature rabbits. They were divided into seven equal groups, with each group receiving a different treatment regime. Saline and three types of dosage of alendronate (low, 0.75 μg/kg; mid, 7.5 μg/kg and high 75 μg/kg) were given by systemic injection in four groups, and saline and two dosages (low and mild) were delivered by local injection to the distraction gap in the remaining three groups. The injections were performed five times weekly during the period of distraction. After nine weeks the animals were killed and image analysis and mechanical testing were performed on the distracted right tibiae and the left tibiae which served as a control group. The local low-dose alendronate group showed a mean increase in bone mineral density of 124.3 mg/cm3 over the local saline group (analysis of variance, p <
0.05) without any adverse effect on the left control tibiae. The findings indicate that the administration of local low-dose alendronate could be an effective pharmacological means of improving bone formation in distraction osteogenesis.
We evaluated the long-term fixation of 64 press-fit cemented stems of constrained total knee prostheses in 32 young patients with primary malignant bone tumours. Initial stable fixation, especially in rotation, was achieved by precise fit of the stem into the reamed endosteum, before cementation. Complementary fixation, especially in migration and rotation, was obtained by pressurised antibiotic-loaded cement. The mean age at operation was 33 years (13 to 61). No patient was lost to follow-up; 13 patients died and the 19 survivors were examined at a mean follow-up of 12.5 years (4 to 21). Standard revision press-fit cemented stems were used on the side of the joint which was not involved with tumour (26 tibial and six femoral), on this side there was no loosening or osteolysis and stem survival was 100%. On the reconstruction side, custom-made press-fit stems were used and the survival rate, with any cause for revision as an end point, was 88%, but 97% for loosening or osteolysis. This longevity is similar to that achieved at 20 years with the Charnley-Kerboull primary total hip replacement with press-fit cemented femoral components. We recommend this type of fixation when extensive reconstruction of the knee is required. It may also be suitable for older patients requiring revision of a total knee replacement or in difficult situations such as severe deformity and complex articular fractures.
The purpose of this study was to determine the annual incidence of Perthes’ disease in Korea and compare this with other populations. A survey identified all newly diagnosed children with Perthes’ disease aged 14 years or younger in South Honam, Korea, between January 1999 and December 2001. A total of 84 children were included: 29 in 1999, 28 in 2000 and 27 in 2001. The mean annual incidence was 3.8 per 100 000. This is similar to that reported in other Asian countries, but higher than in black populations and lower than in Caucasians.
We reviewed the results of 71 revisions of the acetabular component in total hip replacement, using impaction of bone allograft. The mean follow-up was 7.2 years (1.6 to 9.7). All patients were assessed according to the American Academy of Orthopedic Surgeons (AAOS) classification of bone loss, the amount of bone graft required, thickness of the graft layer, signs of graft incorporation and use of augmentation. A total of 20 acetabular components required re-revision for aseptic loosening, giving an overall survival of 72% (95% CI, 54.4 to 80.5). Of these failures, 14 (70%) had an AAOS type III or IV bone defect. In the failed group, poor radiological and histological graft incorporation was seen. These results suggest that impaction allografting in acetabular revision with severe bone defects may have poorer results than have previously been reported.
Percutaneous physiodesis is an established technique for treating mild leg-length discrepancy and problems of expected extreme height. Angular deformities resulting from incomplete physeal arrest have been reported, and little is known about the time interval from percutaneous physiodesis to actual physeal arrest. This procedure was carried out in ten children, six with leg-length discrepancy and four with expected extreme height. Radiostereometric analysis was used to determine the three-dimensional dynamics of growth retardation. Errors of measurement of translation were less than 0.05 mm and of rotation less than 0.06°. Physeal arrest was obtained in all but one child within 12 weeks after physiodesis and no clinically-relevant angular deformities occurred. This is a suitable method for following up patients after percutaneous physiodesis. Incomplete physeal arrest can be detected at an early stage and the procedure repeated before corrective osteotomy is required.
Custom-made intercalary endoprostheses may be used for the reconstruction of diaphyseal defects following the resection of bone tumours. The aim of this study was to determine the survival of intercalary endoprostheses with a lap joint design, and to evaluate the clinical results, complications and functional outcome. We retrospectively reviewed six consecutive patients, three of whom underwent limb salvage with intercalary endoprostheses of the tibia, two of the femur, and one of the humerus. Their mean age was 42 years (28 to 64). The mean follow-up was 21.6 months (9 to 58). The humeral prosthesis required revision at 14 months owing to aseptic loosening. There were no implant-related failures. Musculoskeletal Tumour Society functional outcome scores indicated that patients achieved 90% of premorbid function. Custom intercalary endoprostheses result in reconstructions comparable with, if not better than, those of allografts. Using this design of implant reduces the incidence of early complications and difficulties experienced with previous versions.
We have undertaken a prospective study in patients with a fracture of the femoral shaft requiring intramedullary nailing to test the hypothesis that the femoral canal could be a potential source of the second hit phenomenon. We determined the local femoral intramedullary and peripheral release of interleukin-6 (IL-6) after fracture and subsequent intramedullary reaming. In all patients, the fracture caused a significant increase in the local femoral concentrations of IL-6 compared to a femoral control group. The concentration of IL-6 in the local femoral environment was significantly higher than in the patients own matched blood samples from their peripheral circulation. The magnitude of the local femoral release of IL-6 after femoral fracture was independent of the injury severity score and whether the fracture was closed or open. In patients who underwent intramedullary reaming of the femoral canal a further significant local release of IL-6 was demonstrated, providing evidence that intramedullary reaming can cause a significant local inflammatory reaction.
