A hot swollen joint is a commonly encountered condition in clinical practice. With a broad range of differentials, septic arthritis (SA) is perhaps one of the most concerning. Treated by culture-specific antibiotics and arthroscopic lavage, some patients require multiple washouts. We aimed to determine:. (1) What are the risk factors for development of SA?. (2) What are the risk factors for repeat washout in SA patients?. (3) What are the important clinical differences between a periprosthetic joint infection (PJI) and SA cohort?. All patients presenting to the emergency department, orthopaedic, and rheumatology clinics between January 2020 to January 2021 with a hot, swollen joint were retrospectively evaluated. Patients with previous trauma on the ipsilateral joint, with data missing from their medical records in any of the variables required for analysis, <24 months follow-up were excluded. Variables of interest in the three-month period preceding the diagnosis of SA were compared between SA and non-SA patients. Factors with a p-value of p<0.100 in univariate analysis were included in a stepwise multivariate logistic regression model. Similar analyses were performed to compare SA patients with multiple washouts with those needing one washout. Demographical and clinical data for PJI patients were collected to delineate important differences with SA cohort. 211 patients were included (SA:28;PJI:24;pseudogout:32;gout:26;others:101). Multivariate analysis showed rheumatoid arthritis (RA), skin infection, and liver disease were risk factors for SA. Amongst patients with septic arthritis, multivariate analysis showed that WBC levels above normal limits (3.6-10.5×109 cells/L) and RA were risk factors for multiple washouts. Between the SA and PJI cohorts, BMI (p=0.002) was significantly lower in the former, whilst WBC level (p=0.023) and CRP (p<0.0001) was significantly higher in the former. Early diagnosis of septic arthritis requires understanding the risk factors, namely RA, skin infection, and liver disease. Considering PJI and septic arthritis as the same entity can lead to wrong clinical judgement, and clinicians should be aware of important differences. We believe that the models in this study are of prognostic value to clinicians who are presented with the common presenting compliant of a hot swollen joint

Determine the prevalence, etiologies, and risk factors of unplanned return to the OR (UROR) in adult orthopaedic trauma patients. Retrospective review of a trauma prospective registry from 2014 – 2019 at a Level 1 academic hospital. An UROR was defined as a patient returning to OR unexpectedly following a planned definitive surgery to either readdress the presenting diagnosis or address a complication arising from the index procedure. Univariate and multivariate logistic regression was performed comparing those patients with an UROR versus those without. A total of 1568 patients were reviewed. The rate of UROR was 9.8% (153 patients). Symptomatic implant was the leading cause of UROR (60%). Other significant UROR causes were infection (15%) and implant failure (9%). The median time between index procedure and UROR was 301 days. For the univariate and multivariate analysis, open fracture (p< 0.05), fracture complexity (p<0.01), and weekend procedure (p< 0.01) were all associated with increased risk of UROR. All other variables were not statistically significant for any associations. Those patients with an UROR for reasons other than symptomatic implants were more likely to have polyorthopaedic injuries (p < 0.05), ISS > 15 (p < 0.05), osteoporosis (p < 0.01), ICU status (p < 0.05), psychiatric history (p < 0.05), compartment syndrome (p < 0.05), neurovascular injury (p < 0.01), open fracture (p < 0.05), and fracture complexity (p < 0.05). The rate of UROR in the orthopaedic trauma patient population is 10%. Most of these cases are due to implant-related issues. UROR for reasons other than symptomatic implants tend to be polytraumatized patients with higher-energy injuries, multiple complex fractures, and associated soft tissue injuries. Future focus on improved implant development and treatments for polytraumatized patients with complex fractures is warranted to decrease a relatively high UROR rate in orthopaedic trauma

Results in patients undergoing total hip arthroplasty (THA) for femoral head osteonecrosis (ON) when compared with primary osteoarthritis (OA) are controversial. Different factors like age, THA type or surgical technique may affect outcome. We hypothesized that patients with ON had an increased revision rate compared with OA. We analysed clinical outcome, estimated the survival rate for revision surgery, and their possible risk factors, in two groups of patients. In this retrospective cohort analysis of our prospective database, we assessed 2464 primary THAs implanted between 1989 and 2017. Patients with OA were included in group 1, 2090 hips; and patients with ON in group 2, 374 hips. In group 2 there were more men (p<0.001), patients younger than 60 years old (p<0.001) and with greater physical activity (p<0.001). Patients with lumbar OA (p<0.001) and a radiological acetabular shape type B according to Dorr (p<0.001) were more frequent in group 1. Clinical outcome was assessed according to the Harris Hip Score and radiological analysis included postoperative acetabular and femoral component position and hip reconstruction. Kaplan-Meier survivorship analysis was used to estimate the cumulative probability of not having revision surgery for different reasons. Univariate and multivariate Cox regression models were used to assess risk factors for revision surgery. Clinical improvement was better in the ON at all intervals. There were 90 hips revised, 68 due to loosening or wear, 52 (2.5%) in group 1, and 16 (4.3%) in group 2. Overall, the survival rate for revision surgery for any cause at 22 years was 88.0 % (95% CI, 82-94) in group 1 and 84.1% (95% CI, 69 – 99) in group 2 (p=0.019). Multivariate regression analysis showed that hips with conventional polyethylene (PE), compared with highly-cross linked PEs or ceramic-on-ceramic bearings, (p=0.01, Hazard Ratio (HR): 2.12, 95% CI 1.15-3.92), and cups outside the Lewinnek´s safe zone had a higher risk for revision surgery (p<0.001, HR: 2.57, 95% CI 1.69-3.91). Modern highly-cross linked PEs and ceramic-on-ceramic bearings use, and a proper surgical technique improved revision rate in patients undergoing THA due to ON compared with OA

This was a retrospective study of registry data from a National Orthopaedic Hospital for all THRs with 10-year follow-up data. Inclusion criteria were all THRs with a minimum of 10-year follow-up data. All metal-on-metal (MoM) THRs and MoM resurfacings were excluded from the analysis due to the high rate of revision associated with these bearings. Univariate and multivariate analyses controlling for confounding variables were performed to compare outcomes. A total of 1,697 THRs were performed in 1,553 patients. The four significant predictors for revision were fixation type (p<0.01), surface bearing type (p<0.01), age (P<0.05) and head size (p<0.05). Gender, BMI and approach had no effect on revision rates. The lowest 10-year all-cause revision rates were seen in cemented THRs at 1.7%. Ceramic-on-poly bearings had the lowest revision rate at only 1.2%. Metal-on-poly bearings had a 1.7% revision rate. Ceramic on ceramic bearings had a 7.1% revision rate with 1 revision for squeak and 1 revision for ceramic head fracture. The causes for revision in order of decreasing frequency were as follows: Infection (n=13, 0.7%), dislocation (n=7, 0.4%), periprosthetic fracture (n=3, 0.2%) and aseptic loosening (n=2, 0.1%). There were 2 re-revisions at 10 years in total. The smaller 22.225mm head sizes had a significantly lower revision rate than other head sizes (p<0.05). Ceramic-on-poly bearings, cemented fixation and smaller head sizes perform better in the experience of this registry. However, with multivariate analysis, these differences were shown to be insignificant

Introduction. Advanced stage and a large area of necrotic bone are known risk factors for failure after transtrochanteric rotational osteotomy of the hip in patients with osteonecrosis. The purpose of this study was to determine whether there were other risk factors for failure of this osteotomy. Methods. One hundred and five patients (113 hips) underwent transtrochanteric anterior rotational osteotomy for femoral head osteonecrosis and were followed for a mean period of 51 months post-operatively. Radiographic failure was defined as secondary collapse or osteoarthritic change. Multivariate analysis with the use of a Cox proportional-hazards frailty model was performed to assess factors that influenced the secondary collapse and osteophyte formation. A Kaplan-Meier product-limit method was performed to estimate survival. Results. Secondary collapse occurred in twenty-seven hips (23.9%) and fourteen of these hips (12.4%) were converted to a total hip arthroplasty. At the most recent follow-up, Merle d'Aubigne and Postel hip scores ranged from 6 to 18 points (mean, 16 points). Multivariate analysis showed that the stage of necrosis (hazard ratio=3.28; 95% confidence interval=1.49-7.24), age of the patient (hazard ratio=1.08; 95% confidence interval=1.02-1.14), body mass index (hazard ratio=1.19; 95% confidence interval=1.03-1.38), and extent of necrosis (hazard ratio=1.08; 95% confidence interval=1.04-1.11) were associated with secondary collapse. Seven of eighty-six hips without collapse progressed to osteoarthritis. Survivorship with total hip arthroplasty and radiographic failure as endpoints was 63.4% (95% confidence interval=51.1%-75.7%) and survivorship with total hip arthroplasty, radiographic failure, and loss of follow-up as endpoints was 56.0% (95% confidence interval=44.6%-67.4%) at 110 months. Conclusion. Our study showed that age, body mass index, stage, and extent of osteonecrosis were determining factors for secondary collapse, subsequent unsatisfactory clinical results, and conversion to total hip arthroplasty. These factors should be considered in patient selection for the osteotomy

The use of hip resurfacing arthroplasty (HRA) has largely regressed due to the fear of metal-on-metal bearings. However committed HRA users continue to assert the functional advantages that a geometry retaining implant would have on a patient”s hip. Currently worldwide, HRA is only recommended to men who demand an active lifestyle. Despite this precarious indication, it is not clear to what extent HRA has on higher activity function. The aim of this study was to determine the functional extent to which could be achieved with HRA. The primary objective is to assess the loading pattern change for patients implanted with HRA at high walking speeds and inclinations. The second objective is to compare their loading features to a healthy group to determine if a normal gait pattern could be achieved. Between 2012 and 2016, a total of 28 prospective unilateral HRA patients were analysed on an instrumented treadmill from a single centre. All 28 patient patients had a uniform implant type and had no other lower limb operations or disease. Perioperative plain orthogonal radiographs were used to measure hip length and global hip offset change. A healthy control group (n=35) were analysed to compare. All HRA patients gait characteristics were assessed at incrementally higher speeds and inclinations to determine the extent of improvement HRA has on a challenging activity. A Student t-test along with a multivariate analysis was done with significance set at α=0.05. Weight and height variance was accounted with Hof normalisation. The HRA and control group were reasonably matched for age (57 vs 55yrs), BMI (27 vs 25) and height (175 vs 170cm) respectively. Hip measurements revealed less than 5mm change for all cases. The mean time from initial preoperative gait assessment to postoperative assessment was 30 months (24–48months). The mean top walking speed for controls was 1.97m/s and postoperatively 2.1 m/sec for the HRA group. The significant (p<0.001) loading change during flat walking can be seen with restoration of symmetry. Walking at an inclination demonstrated a marked change during weight acceptance (p<0.001) and a loading pattern returning to near normal. This prospective study found HRA patients walking faster than age matched controls. They demonstrated a significant change in their loading pattern, by significantly shifting load from the unaffected side to the implanted side. Uphill walking, an activity which requires more hip flexion, demonstrated a change in stance phase which was near normal. This small comparative study confirms near physiological function can be achieved with HRA at higher activity levels

Background. Although the tribological characteristics are excellent, cup fixation has been one of the limitations in alumina-on-alumina total hip replacement (THR), so different types of materials and surfaces have been developing. We analysed the clinical and radiological outcome of two different uncemented cups for the same alumina-on-alumina THR. Methods. 679 hips were prospectively followed for at least 5 years. 342 had a hydroxyapatite (HA)-coated relatively smoothed tri-radius cup, implanted between 1999 and 2005 (group 1), and, 337 had a HA-coated macotextured tri-radius implanted between 2006 and 2009 (group 2). Dysplastic hips were more frequently observed in group 2. We compared screw use in both groups as primary fixation, the clinical results, and the radiological appearance of cup loosening. Results. Multivariate analysis showed that group 1, osteopenic and dysplastic acetabulae and women had a higher risk of screw use (p=0.004, HR: 1.68,95% CI: 1.18 to 2.41; p<0.001, HR: 2.25 95%, CI: 1.55 to 3.38; p<0.001, HR: 4.95, 95% CI: 2.83 to 8.64; p=0.011, HR: 1.58, 95% CI: 1.11 to 2.25, respectively). Although the pre-operative clinical score was worse in group 2, the post-operative results were better (p<0.001). There were no complications related to alumina. 15 cups were revised for loosening in the group 1 and 2 in the group 2. The cumulative probability of not having a revision for cup loosening at 15 years for the whole series was 93.3 % (95% CI: 89.6 to 96.9). The probability of not having cup loosening was 93.3% (95% CI: 89.7 to 96.9) in group 1 and 97.5% (95% CI: 93.5 to 100) in group 2. Conclusions. Despite worse pre-operative conditions, the macrotextured surface of the cup in the second group improved bone fixation in this series. Continued follow-up will be required to determine if reduction in wear between the alumina-on alumina bearings results in less osteolysis and loosening

The purpose of our study was to identify possible risk factors of patients with GCT of the long bones after curettage and packing the bone cavity with bone cement or bone allografts. We retrospectively reviewed the records of 249 patients with GCT of the limbs treated at Musculoskeletal Oncology Department of our institution between 1990 and 2013, confirmed histologically and recorded in the Bone Tumor Registry. We reviewed 219 cases located in the lower limb and 30 of the upper limb. This series includes 135 females and 114 males, with mean age 32 years (ranging 5 to 80 yrs). According to Campanacci's grading system, 190 cases were stage 2, 48 cases stage 3, and 11 cases stage 1. Treatment was curettage (intralesional surgery). Local adjuvants, such as phenol and cement, were used in 185 cases; whereas in the remaining 64 cases the residual cavity was filled with allografts or autografts only. Oncological outcome shows 203 patients alive and continuously disease-free (CDF), 41 patients NED1 after treatment of local recurrence (LR), 2 patients NED1 after treatment of lung metastases, 2 AWD with lung metastases. One patient died of unrelated causes (DOD). LR rate was 15.3% (38 pts). Lung metastases rate was 1.6% (4 pts). In patients treated by curettage and cement (185 cases) LR was 12% (22 pts). Conversely, in patients treated curettage and bone allografts it was higher (16/64 cases), with an incidence of 25% of cases (p=0.004). Oncological complications seemed to be related with site, more frequently occurring in the proximal femur (p=0.037). LR occurred only in stage 2 or 3 tumors without statistical significance (p>0.05). The mean interval between the first surgical treatment and LR was 22 months (range: 3–89 mos). However, in the multivariate analysis no significant statistical effect on local recurrence rate could be identified for gender, patient's age, Campanacci's grading, or cement vs allografts. The only independent risk factor related to the local recurrence was the site, with a statistical significance higher risk for patients with GCT of the proximal femur (p= 0.008). Our observation on the correlation of tumor location and risk of local recurrence is new. Therefore, special attention must be given to GCTs in the proximal femur. In fact, primary benign bone tumors in the proximal femur are difficult to treat due to the risk of secondary osteonecrosis of the femoral head or pathologic fracture. Numerous methods of reconstructions have been reported. Among these, total hip arthroplasty (THA) or bipolar hip arthroplasty (BHA) should be avoided when possible as more cases are observed in young patients. Therefore, we do not suggest different approach for the proximal femur. GCT in the proximal femur is much more difficult to treat than in other sites, but if curettage is feasible, the best way is to save the joint with a higher risk of local recurrence, knowing that the sacrifice of the hip articulation in case of recurrence is always possible with THA or BHA

Introduction. Transtrochanteric curved varus osteotomy is one of the effective joint-preserving operations for osteonecrosis (ON) of the femoral head. We correlated various factors with the radiological outcome of this procedure. Methods. We reviewed 74 hips in 63 patients who had a minimum follow-up of 5 years after transtrochanteric curved varus osteotomy for the treatment of ON. There were 28 men and 35 women who had a mean age of 33 years (range, 15 to 68 years) at the time of surgery. Clinical assessment was made based on the Harris hip score (HHS). Radiographically, we investigated various factors; affected lesion, stage and type (localization of the necrotic lesion) of ON, varus degree, post-operative intact ratio, progression of collapse, and joint-space narrowing. On the basis of postoperative radiographs, the hips were divided into 2 groups (Group I: either the progression of collapse or joint-space narrowing, Group II: neither progression of collapse or joint-space narrowing). The related factors with radiological outcome were analyzed by using multivariate analysis (Stepwise discriminant analysis). Results. Sixty-seven of 74 hips (90.5%) survived without conversion to total hip arthroplasty at final follow-up. The mean preoperative HHS was 60 points (range, 34 to 85 points), which improved to 85 points (range, 51 to 100 points) at final follow-up. Thirteen hips were categorized as Group I and 61 hips as Group II. Both the post-operative intact ratio and type of ON affected the radiological outcome. Regarding post-operative intact ratio, the cutoff point to prevent the progression of collapse was 32.1%, and to prevent both the progression of collapse and joint-space narrowing was 42.6%. Conclusion. The results of this study indicated that the post-operative intact ratio should be at least 32.1%. This critical ratio would be useful for surgical planning in transtrochanteric curved varus osteotomy for ON

Summary Statement. Tandem stenosis is a prevalent condition in an Asian population with the narrowest cervical canal diameters and risk factors include advanced age and increased levels of lumbar canal stenosis. Introduction. Tandem spinal stenosis (TSS) is defined as patient with concomitant spinal canal stenosis found in both cervical (C) and lumbar (L) spinal region. Few studies have reported the incidence of TSS is ranged from 5–25%, but these are all noncomparative, small cohort studies. To the best of author knowledge this is the 1st study aims to compare the prevalence of TSS and its risk factors of development in a large multiracial Asian population. Methods. A retrospective review of all mid-sagittal T2MRI whole spine image was carried out at a University hospital in year 2007. Patients with spinal tumour, fracture and congenital stenosis were excluded. Spinal stenosis was defined as canal diameter of ≤10mm, measured from the posterior cervical vertebral/disc wall to anterior surface of the corresponding lamina. Patients were divided into 4 groups, no stenosis(NS), lumbar stenosis only(LS), cervical stenosis only(CS) and TSS. Patients’ demographics, race, co-morbidities and lumbar radiological report data were examined. Potential risk factors for the development of TSS were analyzed using SPSS software. Results. 926 (479 male, 447 female) patients with average age 50 (20–96) yrs were studied. Cervical canal diameters (mm) in TSS patients were the narrowest among the 4groups with C2/3 disc: 11.6, C3/4: 9.7, C4/5: 9.4, C5/6: 8.9, C6/7: 10.0 and C7T1: 11.4mm. The incidence of TSS was 26.2%. The prevalence of TSS in Chinese was 30.7%, Indian 12.5%, Malay 22.5%. The TSS prevalence in patients with 1 level lumbar canal stenosis was 12.5%, 2 levels lumbar stenosis was 6.4% and 3 levels was 4.1%. Multivariate analysis showed patients aged between 40–59 yrs (p=0.000, Exp(B):5.8, 95%CI 2.8–12.0), aged > 60yrs (p=0.000, Exp(B): 10.5, 95%CI 4.8–22.9), Chinese race (p=0.008, Exp(B): 2.5, 95%CI 1.3–4.9), patients with 1 level lumbar stenosis (p=0.000, Exp(B): 63.3, 95%CI 29.2–137.3), 2 levels lumbar stenosis (p=0.000, Exp(B): 67.7, 95%CI 29.4–155.7) and 3 levels lumbar stenosis (p=0.000, Exp(B): 106.6, 95%CI 43.6–260.5) are statistical significant risk factors for TSS development. Conclusion. The incidence of TSS was 26.2%. TSS patients have the narrowest cervical canal measurements among the studied groups. The prevalence of TSS in Chinese is the highest (30.7%). Patients advancing in age or have increased levels of lumbar canal stenosis are at risk of developing TSS

The purposes of this study were to define the range of laxity of the interosseous ligaments in cadaveric wrists and to determine whether this correlated with age, the morphology of the lunate, the scapholunate (SL) gap or the SL angle. We evaluated 83 fresh-frozen cadaveric wrists and recorded the SL gap and SL angle. Standard arthroscopy of the wrist was then performed and the grades of laxity of the scapholunate interosseous ligament (SLIL) and the lunotriquetral interosseous ligament (LTIL) and the morphology of the lunate were recorded. Arthroscopic evaluation of the SLIL revealed four (5%) grade I specimens, 28 (34%) grade II, 40 (48%) grade III and 11 (13%) grade IV. Evaluation of the LTIL showed 17 (20%) grade I specimens, 40 (48%) grade II, 28 (30%) grade III and one (1%) grade IV. On both bivariate and multivariate analysis, the grade of both the SLIL and LTIL increased with age, but decreased with female gender. The grades of SLIL or LTIL did not correlate with the morphology of the lunate, the SL gap or the SL angle. The physiological range of laxity at the SL and lunotriquetral joints is wider than originally described. The intercarpal ligaments demonstrate an age-related progression of laxity of the SL and lunotriquetral joints. There is no correlation between the grades of laxity of the SLIL or LTIL and the morphology of the lunate, the SL gap or the SL grade. Based on our results, we believe that the Geissler classification has a role in describing intercarpal laxity, but if used alone it cannot adequately diagnose pathological instability. We suggest a modified classification with a mechanism that may distinguish physiological laxity from pathological instability

Introduction. The goal of joint-preserving surgery for the treatment of osteonecrosis of the femoral head (ONFH) is to delay or prevent osteoarthritic development. Bone marrow is a source of osteogenic progenitors that are key elements in the process of bone formation and fracture healing. We established an easy-to-use method using a conventional manual blood bag centrifugation technique traditionally used for extracting buffy coats, for concentration of nucleated cells and platelets from clinical bone marrow aspirates to obtain osteogenic progenitors and growth factors. However, it is unclear whether the surgical goals are really achieved and if so in which patients. The purpose of this study was to identify demographic, clinical, and radiographic factors predicting total hip arthroplasty (THA) conversion after CABMAT for the treatment of idiopathic ONFH. Methods. We retrospectively reviewed 123 patients (213 hips) who had CABMAT between 2003 and 2010. Sixty-five subjects (115 hips) were male and 58 (98 hips) were female with an average age at the time of CABMAT of 40.1 years. Of the 213 hips, 143 hips in 78 patients had corticosteroid-induced ONFH, 46 hips in 27 patients had alcohol-associated, and 24 hips in 18 patients had no etiological factors could be detected. The mean follow-up period was 60.5 months. The endpoint of evaluation was set as the time point which the patient required additional surgery (THA) depending on the spontaneous hip pain, x-ray change, and social back ground. The following factors were investigated: age, sex, body mass index (BMI), unilateral or bilateral, etiological factors, preoperative classification and staging, visual analogue scale (VAS), JOA clinical score. The 213 hips were divided into two groups: a THA conversion (THA) group and a non-THA conversion (non-THA) group. A multivariate analysis was performed using a logistic regression model. Results. In this series, of the 213 hips, 51 hips (23.9%) in 37 patients converted THA. The mean age of patients in THA group was 43.0 years and that of non-THA group was 39.2 years. The mean duration between CABMAT and THA conversion was 26.9 months. Preoperatively, 11 of the 213 hips were classified as type A, 8 hips as type B, 78 hips as type C1, and 116 hips as type C2. 48 hips were classified as stage 1, 65 hips as stage 2, 58 as Stage 3A, 34 as Stage 3B, 8 as stage 4. Postoperatively, no hips in types A and B, 11 hips (14.1%) in type C1, 40 hips (34.5%) in type C2, and 8 hips (16.7%) in stage 1, 13 hips (25.0%) in stage 2, 14 hips (24.1%) in stage 3A, 11 hips (32.4%) in stage 3B, 5 hips (62.5%) in stage 4 were converted THA. Conclusions. The strongest predictors of THA conversion after CABMAT were type, the extent of necrotic area, and age. The results suggest that what factors determine the THA conversion after CABMAT and which patients of idiopathic ONFH are appropriate for CABMAT treatment. Further careful follow-up is needed clinically, and an additional treatment strategy to improve CABMAT is currently in progress

Objectives

Intramedullary fixation is considered the most stable treatment for pertrochanteric fractures of the proximal femur and cut-out is one of the most frequent mechanical complications. In order to determine the role of clinical variables and radiological parameters in predicting the risk of this complication, we analysed the data pertaining to a group of patients recruited over the course of six years.

Objectives

To review the systemic impact of smoking on bone healing as evidenced within the orthopaedic literature.

Curettage and packing with polymethylmethacrylate cement is a routine treatment for giant-cell tumour (GCT) of bone. We performed an in vitro evaluation of the cytotoxic effect of a combination of cement and methotrexate, doxorubicin and cisplatin on primary cell cultures of stromal GCT cells obtained from five patients. Cement cylinders containing four different concentrations of each drug were prepared, and the effect of the eluted drugs was examined at three different time intervals.

We found that the cytotoxic effect of eluted drugs depended on their concentration and the time interval, with even the lowest dose of each drug demonstrating an acceptable rate of cytotoxicity. Even in low doses, cytotoxic drugs mixed with polymethylmethacrylate cement could therefore be considered as effective local adjuvant treatment for GCTs.

Hydroxyapatite-coated standard anatomical and customised femoral stems are designed to transmit load to the metaphyseal part of the proximal femur in order to avoid stress shielding and to reduce resorption of bone. In a randomised in vitro study, we compared the changes in the pattern of cortical strain after the insertion of hydroxyapatite-coated standard anatomical and customised stems in 12 pairs of human cadaver femora. A hip simulator reproduced the physiological loads on the proximal femur in single-leg stance and stair-climbing. The cortical strains were measured before and after the insertion of the stems.

Significantly higher strain shielding was seen in Gruen zones 7, 6, 5, 3 and 2 after the insertion of the anatomical stem compared with the customised stem. For the anatomical stem, the hoop strains on the femur also indicated that the load was transferred to the cortical bone at the lower metaphyseal or upper diaphyseal part of the proximal femur.

The customised stem induced a strain pattern more similar to that of the intact femur than the standard, anatomical stem.