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1.  Three-dimensional mechanical evaluation of joint contact pressure in 12 periacetabular osteotomy patients with 10-year follow-up 
Acta orthopaedica  2009;80(2):155-161.
Background and purpose
Because of the varying structure of dysplastic hips, the optimal realignment of the joint during periacetabular osteotomy (PAO) may differ between patients. Three-dimensional (3D) mechanical and radiological analysis possibly accounts better for patient-specific morphology, and may improve and automate optimal joint realignment.
Patients and methods
We evaluated the 10-year outcomes of 12 patients following PAO. We compared 3D mechanical analysis results to both radiological and clinical measurements. A 3D discrete-element analysis algorithm was used to calculate the pre- and postoperative contact pressure profile within the hip. Radiological angles describing the coverage of the joint were measured using a computerized approach at actual and theoretical orientations of the acetabular cup. Quantitative results were compared using postoperative clinical evaluation scores (Harris score), and patient-completed outcome surveys (q-score) done at 2 and 10 years.
Results
The 3D mechanical analysis indicated that peak joint contact pressure was reduced by an average factor of 1.7 subsequent to PAO. Lateral coverage of the femoral head increased in all patients; however, it did not proportionally reduce the maximum contact pressure and, in 1 case, the pressure increased. This patient had the lowest 10-year q-score (70 out of 100) of the cohort. Another hip was converted to hip arthroplasty after 3 years because of increasing osteoarthritis.
Interpretation
The 3D analysis showed that a reduction in contact pressure was theoretically possible for all patients in this cohort, but this could not be achieved in every case during surgery. While intraoperative factors may affect the actual surgical outcome, the results show that 3D contact pressure analysis is consistent with traditional PAO planning techniques (more so than 2D analysis) and may be a valuable addition to preoperative planning and intraoperative assessment of joint realignment.
doi:10.3109/17453670902947390
PMCID: PMC2689368  PMID: 19404795
2.  Three-dimensional mechanical evaluation of joint contact pressure in 12 periacetabular osteotomy patients with 10-year follow-up 
Acta Orthopaedica  2009;80(2):155-161.
Background and purpose Because of the varying structure of dysplastic hips, the optimal realignment of the joint during periacetabular osteotomy (PAO) may differ between patients. Three-dimensional (3D) mechanical and radiological analysis possibly accounts better for patient-specific morphology, and may improve and automate optimal joint realignment.
Patients and methods We evaluated the 10-year outcomes of 12 patients following PAO. We compared 3D mechanical analysis results to both radiological and clinical measurements. A 3D discrete-element analysis algorithm was used to calculate the pre- and postoperative contact pressure profile within the hip. Radiological angles describing the coverage of the joint were measured using a computerized approach at actual and theoretical orientations of the acetabular cup. Quantitative results were compared using postoperative clinical evaluation scores (Harris score), and patient-completed outcome surveys (q-score) done at 2 and 10 years.
Results The 3D mechanical analysis indicated that peak joint contact pressure was reduced by an average factor of 1.7 subsequent to PAO. Lateral coverage of the femoral head increased in all patients; however, it did not proportionally reduce the maximum contact pressure and, in 1 case, the pressure increased. This patient had the lowest 10-year q-score (70 out of 100) of the cohort. Another hip was converted to hip arthroplasty after 3 years because of increasing osteoarthritis.
Interpretation The 3D analysis showed that a reduction in contact pressure was theoretically possible for all patients in this cohort, but this could not be achieved in every case during surgery. While intraoperative factors may affect the actual surgical outcome, the results show that 3D contact pressure analysis is consistent with traditional PAO planning techniques (more so than 2D analysis) and may be a valuable addition to preoperative planning and intraoperative assessment of joint realignment.
doi:10.3109/17453670902947390
PMCID: PMC2689368  PMID: 19404795
3.  Preoperative corticosteroid injections are associated with worse long-term outcome of surgical carpal tunnel release 
Acta Orthopaedica  2014;85(1):102-106.
Background and purpose
Failed closed treatment of carpal tunnel syndrome (CTS) is often followed by surgery. We investigated whether preoperative steroid injections could have a negative effect on the long-term outcome of the operation.
Patients and methods
174 hands (164 patients) were operated on by a single surgeon at Tartu University Hospital in 2005. The patients were interviewed by telephone 5–6 years after the operation. Self-reported data were gathered retrospectively concerning the number of steroid injections received before the surgery and the perceived regression of symptoms (on a 100-point numeric rating scale) at the time of interview. The patients were also asked about the presence of specific symptoms of CTS if regression of their symptoms had not been complete.
Results
93 of the 174 hands had complete regression of symptoms. Each additional injection was associated with an increased risk of occurrence of pain (RR = 1.1, 95% CI: 1.02–1-2), paresthesiae (RR = 1.1, CI: 1.1–1.2), and nocturnal awakenings (RR = 1.2, CI: 1.1–1.3). There was a weak association between the number of injections and the score given to regression of symptoms.
Interpretation
This is the first study to indicate that patients who received a greater number of local steroid injections preoperatively were more likely to have postoperative complaints associated with CTS.
doi:10.3109/17453674.2013.867781
PMCID: PMC3940985  PMID: 24286569
4.  Increased risk of revision in patients with non-traumatic femoral head necrosis 
Acta Orthopaedica  2014;85(1):11-17.
Background and purpose
Previous studies of patients who have undergone total hip arthroplasty (THA) due to femoral head necrosis (FHN) have shown an increased risk of revision compared to cases with primary osteoarthritis (POA), but recent studies have suggested that this procedure is not associated with poor outcome. We compared the risk of revision after operation with THA due to FHN or POA in the Nordic Arthroplasty Register Association (NARA) database including Denmark, Finland, Norway, and Sweden.
Patients and methods
427,806 THAs performed between 1995 and 2011 were included. The relative risk of revision for any reason, for aseptic loosening, dislocation, deep infection, and periprosthetic fracture was studied before and after adjustment for covariates using Cox regression models.
Results
416,217 hips with POA (mean age 69 (SD 10), 59% females) and 11,589 with FHN (mean age 65 (SD 16), 58% females) were registered. The mean follow-up was 6.3 (SD 4.3) years. After 2 years of observation, 1.7% in the POA group and 3.0% in the FHN group had been revised. The corresponding proportions after 16 years of observation were 4.2% and 6.1%, respectively. The 16-year survival in the 2 groups was 86% (95% CI: 86–86) and 77% (CI: 74–80). After adjusting for covariates, the relative risk (RR) of revision for any reason was higher in patients with FHN for both periods studied (up to 2 years: RR = 1.44, 95% CI: 1.34–1.54; p < 0.001; and 2–16 years: RR = 1.25, 1.14–1.38; p < 0.001).
Interpretation
Patients with FHN had an overall increased risk of revision. This increased risk persisted over the entire period of observation and covered more or less all of the 4 most common reasons for revision.
doi:10.3109/17453674.2013.874927
PMCID: PMC3940986  PMID: 24359026
5.  Posterior approach and uncemented stems increases the risk of reoperation after hemiarthroplasties in elderly hip fracture patients 
Acta Orthopaedica  2014;85(1):18-25.
Background
Hemiarthroplasties are performed in great numbers worldwide but are seldom registered on a national basis. Our aim was to identify risk factors for reoperation after fracture-related hemiarthroplasty in Norway and Sweden.
Material and methods
A common dataset was created based on the Norwegian Hip Fracture Register and the Swedish Hip Arthroplasty Register. 33,205 hip fractures in individuals > 60 years of age treated with modular hemiarthroplasties were reported for the period 2005–2010. Cox regression analyses based on reoperations were performed (covariates: age group, sex, type of stem and implant head, surgical approach, and hospital volume).
Results
1,164 patients (3.5%) were reoperated during a mean follow-up of 2.7 (SD 1.7) years. In patients over 85 years, an increased risk of reoperation was found for uncemented stems (HR = 2.2, 95% CI: 1.7–2.8), bipolar heads (HR = 1.4, CI: 1.2–1.8), posterior approach (HR = 1.4, CI: 1.2–1.8) and male sex (HR = 1.3, CI: 1.0–1.6). For patients aged 75–85 years, uncemented stems (HR = 1.6, 95% CI: 1.2–2.0) and men (HR = 1.3, CI: 1.1–1.6) carried an increased risk. Increased risk of reoperation due to infection was found for patients aged < 75 years (HR = 1.5, CI: 1.1–2.0) and for uncemented stems. For open surgery due to dislocation, the strongest risk factor was a posterior approach (HR = 2.2, CI: 1.8–2.6). Uncemented stems in particular (HR = 3.6, CI: 2.4–5.3) and male sex increased the risk of periprosthetic fracture surgery.
Interpretation
Cemented stems and a direct lateral transgluteal approach reduced the risk of reoperation after hip fractures treated with hemiarthroplasty in patients over 75 years. Men and younger patients had a higher risk of reoperation. For the age group 60–74 years, there were no such differences in risk in this material.
doi:10.3109/17453674.2014.885356
PMCID: PMC3940987  PMID: 24460108
6.  Reduced short-term complications and mortality following Enhanced Recovery primary hip and knee arthroplasty: results from 6,000 consecutive procedures 
Acta Orthopaedica  2014;85(1):26-31.
Background and purpose
Enhanced Recovery (ER) is a well-established multidisciplinary strategy in lower limb arthroplasty and was introduced in our department in May 2008. This retrospective study reviews short-term outcomes in a consecutive unselected series of 3,000 procedures (the “ER” group), and compares them to a numerically comparable cohort that had been operated on previously using a traditional protocol (the “Trad” group).
Methods
Prospectively collected data on surgical endpoints (length of stay (LOS), return to theater (RTT), re-admission, and 30- and 90-day mortality) and medical complications (stroke, gastrointestinal bleeding, myocardial infarction, and pneumonia within 30 days; deep vein thrombosis and pulmonary embolism within 60 days) were compared.
Results
ER included 1,256 THR patients and 1,744 TKR patients (1,369 THRs and 1,631 TKRs in Trad). The median LOS in the ER group was reduced (3 days vs. 6 days; p = 0.01). Blood transfusion rate was also reduced (7.6% vs. 23%; p < 0.001), as was RTT rate (p = 0.05). The 30-day incidence of myocardial infarction declined (0.4% vs. 0.9%; p = 0.03) while that of stroke, gastrointestinal bleeding, pneumonia, deep vein thrombosis, and pulmonary embolism was not statistically significantly different. Mortality at 30 days and at 90 days was 0.1% and 0.5%, respectively, as compared to 0.5% and 0.8% using the traditional protocol (p = 0.03 and p = 0.1, respectively).
Interpretation
This is the largest study of ER arthroplasty, and provides safety data on a consecutive unselected series. The program has achieved a statistically significant reduction in LOS and in cardiac ischemic events for our patients, with a near-significant decrease in return to theater and in mortality rates.
doi:10.3109/17453674.2013.874925
PMCID: PMC3940988  PMID: 24359028
7.  Cancer incidence and cause-specific mortality in patients with metal-on-metal hip replacements in Finland 
Acta Orthopaedica  2014;85(1):32-38.
Background and purpose
Metal-on-metal hip implants have been widely used, especially in the USA, Australia, England and Wales, and Finland. We assessed risk of death and updated data on the risk of cancer related to metal-on-metal hip replacements.
Patients and methods
A cohort of 10,728 metal-on-metal hip replacement patients and a reference cohort of 18,235 conventional total hip replacement patients were extracted from the Finnish Arthroplasty Register for the years 2001–2010. Data on incident cancer cases and causes of death until 2011 were obtained from the Finnish Cancer Registry and Statistics Finland. The relative risk of cancer and death were expressed as standardized incidence ratio (SIR) and standardized mortality ratio (SMR). SIR/SIR ratios and SMR/SMR ratios, and Poisson regression were used to compare the cancer risk and the risk of death between cohorts.
Results
The overall risk of cancer in the metal-on-metal cohort was not higher than that in the non-metal-on-metal cohort (RR = 0.91, 95% CI: 0.82–1.02). The risk of soft-tissue sarcoma and basalioma in the metal-on-metal cohort was higher than in the non-metal-on-metal cohort (SIR/SIR ratio = 2.6, CI: 1.02–6.4 for soft-tissue sarcoma; SIR/SIR ratio = 1.3, CI: 1.1–1.5 for basalioma). The overall risk of death in the metal-on-metal cohort was less than that in the non-metal-on-metal cohort (RR = 0.78, CI: 0.69–0.88).
Interpretation
The overall risk of cancer or risk of death because of cancer is not increased after metal-on-metal hip replacement. The well-patient effect and selection bias contribute substantially to the findings concerning mortality. Arthrocobaltism does not increase mortality in patients with metal-on-metal hip implants in the short term. However, metal-on-metal hip implants should not be considered safe until data with longer follow-up time are available.
doi:10.3109/17453674.2013.878830
PMCID: PMC3940989  PMID: 24397743
8.  Minimal clinically important improvement (MCII) and patient-acceptable symptom state (PASS) in total hip arthroplasty (THA) patients 1 year postoperatively 
Acta Orthopaedica  2014;85(1):39-48.
Background and purpose
The increased use of patient-reported outcomes (PROs) in orthopedics requires data on estimated minimal clinically important improvements (MCIIs) and patient-acceptable symptom states (PASSs). We wanted to find cut-points corresponding to minimal clinically important PRO change score and the acceptable postoperative PRO score, by estimating MCII and PASS 1 year after total hip arthroplasty (THA) for the Hip Dysfunction and Osteoarthritis Outcome Score (HOOS) and the EQ-5D.
Patients and methods
THA patients from 16 different departments received 2 PROs and additional questions preoperatively and 1 year postoperatively. The PROs included were the HOOS subscales pain (HOOS Pain), physical function short form (HOOS-PS), and hip-related quality of life (HOOS QoL), and the EQ-5D. MCII and PASS were estimated using multiple anchor-based approaches.
Results
Of 1,837 patients available, 1,335 answered the preoperative PROs, and 1,288 of them answered the 1-year follow-up. The MCIIs and PASSs were estimated to be: 24 and 91 (HOOS Pain), 23 and 88 (HOOS-PS), 17 and 83 (HOOS QoL), 0.31 and 0.92 (EQ-5D Index), and 23 and 85 (EQ-VAS), respectively. MCIIs corresponded to a 38–55% improvement from mean baseline PRO score and PASSs corresponded to absolute follow-up scores of 57–91% of the maximum score in THA patients 1 year after surgery.
Interpretation
This study improves the interpretability of PRO scores. The different estimation approaches presented may serve as a guide for future MCII and PASS estimations in other contexts. The cutoff points may serve as reference values in registry settings.
doi:10.3109/17453674.2013.867782
PMCID: PMC3940990  PMID: 24286564
9.  Cemented or uncemented hemiarthroplasty for the treatment of femoral neck fractures? 
Acta Orthopaedica  2014;85(1):49-53.
Background and purpose
Cemented hemiarthroplasty is preferred in treating displaced fractures of the femoral neck in the elderly. The cementing process may cause a fat embolism, leading to serious complications or death. In this study, we wanted to determine whether use of uncemented hemiarthroplasty (HA) would lead to reduced mortality and whether there are differences in the complications associated with these different types of arthroplasty.
Patients and methods
From the PERFECT database, which combines information from various treatment registries, we identified 25,174 patients who were treated with hemiarthroplasty for a femoral neck fracture in the years 1999–2009. The primary outcome was mortality. Secondary outcomes were reoperations, complications, re-admissions, and treatment times.
Results
Mortality was lower in the first postoperative days when uncemented HA was used. At 1 week, there was no significant difference in mortality (3.9% for cemented HA and 3.4% for uncemented HA; p = 0.09). This was also true after one year (26% for cemented HA and 27% for uncemented HA; p = 0.1). In patients treated with uncemented HA, there were significantly more mechanical complications (3.7% vs. 2.8%; p < 0.001), hip re-arthroplasties (1.7% vs. 0.95; p < 0.001), and femoral fracture operations (1.2% vs. 0.52%; p < 0.001) during the first 90 days after hip fracture surgery.
Interpretation
From registry data, mortality appears to be similar for cemented and uncemented HA. However, uncemented HA is associated with more frequent mechanical complications and reoperations.
doi:10.3109/17453674.2013.878827
PMCID: PMC3940991  PMID: 24397746
10.  Similar mortality rates in hip fracture patients over the past 31 years 
Acta Orthopaedica  2014;85(1):54-59.
Background
Over 320,000 hip fractures occur in North America each year and they are associated with a mortality rate ranging from 14% to 36% within 1 year of surgery. We assessed whether mortality and reoperation rates have improved in hip fracture patients over the past 31 years.
Methods
3 electronic databases were searched for randomized controlled trials on hip fracture management, published between 1950 and 2013. Articles that assessed the surgical treatment of intertrochanteric or femoral neck fractures and measured mortality and/or reoperation rates were obtained. We analyzed overall mortality and reoperation rates, as well as mortality rates by fracture type, comparing mean values in different decades. Our primary outcome was the change in 1-year postoperative mortality.
Results
70 trials published between 1981 and 2012 were included in the review. Overall, the mean 1-year mortality rate changed from 24% in the 1980s to 23% in the 1990s, and to 21% after 1999 (p = 0.7). 1-year mean mortality rates for intertrochanteric fractures diminished from 34% to 23% in studies published before 2000 and after 1999 (p = 0.005). Mean mortality rates for femoral neck fractures were similar over time (∼20%). Reoperation rates were also similar over time.
Interpretation
We found similar mortality and reoperation rates in surgically treated hip fracture patients over time, with the exception of decreasing mortality rates in patients with intertrochanteric fractures.
doi:10.3109/17453674.2013.878831
PMCID: PMC3940992  PMID: 24397744
11.  Low bone mineral density is not related to failure in femoral neck fracture patients treated with internal fixation 
Acta Orthopaedica  2014;85(1):60-65.
Background and purpose
Internal fixation (IF) in femoral neck fractures has high reoperation rates and some predictors of failure are known, such as age, quality of reduction, and implant positioning. Finding new predictors of failure is an ongoing process, and in this study we evaluated the importance of low bone mineral density (BMD).
Patients and methods
140 consecutive patients (105 females, median age 80) treated with IF had a dual-energy X-ray absorptiometry (DXA) scan of the hip performed median 80 days after treatment. The patients’ radiographs were evaluated for fracture displacement, implant positioning, and quality of reduction. From a questionnaire completed during admission, 2 variables for comorbidity and walking disability were chosen.
Primary outcome was low hip BMD (amount of mineral matter per square centimeter of hip bone) compared to hip failure (resection, arthroplasty, or new hip fracture). A stratified Cox regression model on fracture displacement was applied and adjusted for age, sex, quality of reduction, implant positioning, comorbidity, and walking disability.
Results
49 patients had a T-score below –2.5 (standard deviation from the young normal reference mean) and 70 patients had a failure. The failure rate after 2 years was 22% (95% CI: 12–39) for the undisplaced fractures and 66% (CI: 56–76) for the displaced fractures. Cox regression showed no association between low hip BMD and failure. For the covariates, only implant positioning showed an association with failure.
Interpretation
We found no statistically significant association between low hip BMD and fixation failure in femoral neck fracture patients treated with IF.
doi:10.3109/17453674.2013.875360
PMCID: PMC3940993  PMID: 24359030
12.  Incomplete periacetabular acetabuloplasty 
Acta Orthopaedica  2014;85(1):66-70.
Background
Residual acetabular dysplasia is one of the most common complications after treatment for developmental dysplasia of the hip. The acetabular growth response after reduction of a dislocated hip varies. The options are to wait and add a redirectional osteotomy as a secondary procedure at an older age, or to perform a primary acetabuloplasty at the time of the open reduction to stimulate acetabular development. We present the early results of such a procedure—open reduction and an incomplete periacetabular acetabuloplasty—as a one-stop procedure for developmental dysplasia of the hip.
Patients and methods
We retrospectively reviewed the results obtained with 55 hips (in 48 patients, 43 of them girls) treated between September 2004 and February 2011. This cohort included late presentations and failures of nonoperative treatment and excluded unsuccessful previous surgical treatment (including closed reductions), neuromuscular disease, and other teratological conditions. Patients were treated once the ossific nucleus was present or when they reached one year of age. 31 cases were late presentations while 17 represented failures of nonoperative treatment. The mean age of the patients at surgery was 1.3 (0.6–2.6) years. The mean follow-up period was 4 (2–8) years. According to the IHDI classification, 1 was grade I, 9 were grade II, 13 were grade III, and 32 were grade IV.
Results
The mean acetabular index fell from 38 (23–49) preoperatively to 21 (10–27) at the last follow-up. There were no infections, nerve palsies, or graft extrusions. None of the cases required secondary surgery for residual acetabular dysplasia. 8 patients developed avascular necrosis (AVN) of grade II or more. The incidence of AVN was significantly associated with previous, failed nonoperative treatment. 1 patient developed coxa magna requiring shelf arthroplasty 4 years after the index procedure and 1 patient with lateral growth arrest required medial screw epiphysiodesis.
Interpretation
This incomplete periacetabular acetabuloplasty is a reliable adjunct to open reductions, and it is followed by a rapid acetabular growth response that avoids secondary pelvic procedures. It is a one-stop surgery with predictable outcome that can be performed in 0.5- to 2.5-year-old children.
doi:10.3109/17453674.2014.886030
PMCID: PMC3940994  PMID: 24460107
13.  Can total knee arthroplasty be safely performed in patients with chronic renal disease? 
Acta Orthopaedica  2014;85(1):71-78.
Background and purpose
The prevalence of chronic renal disease (CRD) is rising worldwide. Patients with CRD are more likely to have associated medical problems and are at greater risk of postoperative morbidity and mortality. We evaluated patient characteristics and risk of early revision, surgical site infection (SSI), thromboembolic events, mortality, and re-admission of patients with CRD undergoing total knee arthroplasty (TKA). We hypothesized that this patient population would have higher rates of complications.
Patients and methods
We conducted a retrospective analysis of data that had been prospectively collected by a Total Joint Replacement Registry. All primary TKAs performed from 2005 through 2010 were included. 41,852 primary TKA cases were evaluated, of which 2,686 (6.4%) TKA procedures had been performed in CRD patients. Patient characteristics, comorbidities, and general health status were evaluated. Cox proportional hazard regressions and logistic regressions were used to evaluate the association of CRD with outcomes while adjusting for confounding variables.
Results
The mean age of the CRD cohort was 67 years and approximately two-thirds of the patients were female. The median follow-up time was 2.1 years. Compared to TKA patients without CRD the CRD patients were older, had poorer general health, and had a higher prevalence of comorbidities. They had a higher incidence of deep SSI (0.9% vs. 0.7%), superficial SSI (0.5% vs. 0.3%), deep vein thrombosis (0.6% vs. 0.4%), any-time mortality (4.7% vs. 2.4%), 90-day mortality (0.4% vs. 0.2%), and 90-day re-admission (10% vs. 6.0%) than patients without CRD. However, after adjustment for confounding variables, CRD patients were at 1.9 times (95% CI: 1.1–3.5) increased risk of superficial SSI, 1.3 times (CI: 1.1–1.6) increased risk of re-admission within 90 days, and 1.5 times (CI: 1.2–1.8) increased risk of mortality at any point after the procedure. The risks of all other complications were not statistically significantly different in patients with CRD compared to patients without CRD.
Conclusions
CRD patients undergoing TKA have more comorbidities and a higher risk for superficial SSI, 90-day re-admission, and any-time mortality.
doi:10.3109/17453674.2013.878829
PMCID: PMC3940995  PMID: 24397745
14.  Measurement of the migration of a focal knee resurfacing implant with radiostereometry 
Acta Orthopaedica  2014;85(1):79-83.
Background and purpose
Articular resurfacing metal implants have been developed to treat full-thickness localized articular cartilage defects. Evaluation of the fixation of these devices is mandatory. Standard radiostereometry (RSA) is a validated method for evaluation of prosthetic migration, but it requires that tantalum beads are inserted into the implant. For technical reasons, this is not possible for focal articular resurfacing components. In this study, we therefore modified the tip of an articular knee implant and used it as a marker for RSA, and then validated the method.
Material and methods
We modified the tip of a resurfacing component into a hemisphere with a radius of 3 mm, marked it with a 1.0-mm tantalum marker, and implanted it into a sawbone marked with 6 tantalum beads. Point-motion RSA of the “hemisphere bead” using standard automated RSA as the gold standard was compared to manual measurement of the tip hemisphere. 20 repeated stereograms with gradual shifts of position of the specimen between each double exposure were used for the analysis. The tip motion was compared to the point motion of the hemisphere bead to determine the accuracy and precision.
Results
The accuracy of the manual tip hemisphere method was 0.08–0.19 mm and the precision ranged from 0.12 mm to 0.33 mm.
Interpretation
The accuracy and precision for translations is acceptable when using a small hemisphere at the tip of a focal articular knee resurfacing implant instead of tantalum marker beads. Rotations of the implant cannot be evaluated. The method is accurate and precise enough to allow detection of relevant migration, and it will be used for future clinical trials with the new implant.
doi:10.3109/17453674.2013.869654
PMCID: PMC3940996  PMID: 24286562
15.  Short-segment posterior instrumentation combined with anterior spondylodesis using an autologous rib graft in thoracolumbar burst fractures 
Acta Orthopaedica  2014;85(1):84-90.
Background and purpose
There are very few data concerning the outcome after short-segment posterior stabilization and anterior spondylodesis with rib grafts in patients suffering from unstable thoracolumbar burst fractures. We have therefore investigated the clinical and radiographic outcome after posterior bisegmental instrumentation and monosegmental anterior spondylodesis using an autologous rib graft for unstable thoracolumbar burst fractures.
Patients and methods
This was a retrospective analysis of 32 consecutive patients at a single center. The monosegmental Cobb angle was measured preoperatively, postoperatively, then 6 and 12 months postoperatively, and also after implant removal. Anterior vertebral fusion was graded on conventional radiographs according to the criteria proposed by Molinari.
Results
Segmental kyphosis at the fracture site was corrected from a median of -20° (95% CI: -21.2 to -18.8) to -1.0° (95% CI: -2.7 to 0.7) postoperatively. 1 year after surgery, the segmental angle had decreased by a median of 2.0° (95% CI: 0.2 to 2.8). The spondylodesis fused in all patients, which was evident from incorporation and remodeling of the rib grafts. The median correction loss after implant removal was 0.0° (95% CI: -0.5 to 0.5). 26 of the 32 patients reported having no back complaints at the last follow-up (2 years postoperatively). 1 patient suffered from intercostal neuralgia, and 5 patients reported mild to moderate back pain.
Interpretation
Short-segment posterior instrumentation and anterior spondylodesis using an autologous rib graft resulted in sufficient correction of posttraumatic segmental kyphosis. There was no clinically relevant correction loss, and the majority of patients had no back complaints at the 2-year follow-up.
doi:10.3109/17453674.2013.871137
PMCID: PMC3940997  PMID: 24359027
16.  A CT scan protocol for the detection of radiographic loosening of the glenoid component after total shoulder arthroplasty 
Acta Orthopaedica  2014;85(1):91-96.
Background and purpose
It is difficult to evaluate glenoid component periprosthetic radiolucencies in total shoulder arthroplasties (TSAs) using plain radiographs. This study was performed to evaluate whether computed tomography (CT) using a specific patient position in the CT scanner provides a better method for assessing radiolucencies in TSA.
Methods
Following TSA, 11 patients were CT scanned in a lateral decubitus position with maximum forward flexion, which aligns the glenoid orientation with the axis of the CT scanner. Follow-up CT scanning is part of our routine patient care. Glenoid component periprosthetic lucency was assessed according to the Molé score and it was compared to routine plain radiographs by 5 observers.
Results
The protocol almost completely eliminated metal artifacts in the CT images and allowed accurate assessment of periprosthetic lucency of the glenoid fixation. Positioning of the patient within the CT scanner as described was possible for all 11 patients. A radiolucent line was identified in 54 of the 55 observed CT scans and osteolysis was identified in 25 observations. The average radiolucent line Molé score was 3.4 (SD 2.7) points with plain radiographs and 9.5 (SD 0.8) points with CT scans
(p = 0.001). The mean intra-observer variance was lower in the CT scan group than in the plain radiograph group (p = 0.001).
Interpretation
The CT scan protocol we used is of clinical value in routine assessment of glenoid periprosthetic lucency after TSA. The technique improves the ability to detect and monitor radiolucent lines and, therefore, possibly implant loosening also.
doi:10.3109/17453674.2013.869653
PMCID: PMC3940998  PMID: 24286563
17.  Expression of gap junction proteins connexins 26, 30, and 43 in Dupuytren’s disease 
Acta Orthopaedica  2014;85(1):97-101.
Background and purpose
Dupuytren’s disease (DD) is a benign fibroproliferative process of the palmar aponeurosis showing similarities to wound healing. Communication of cells involved in wound healing is mediated by the composition of gap junction (GJ) proteins. We investigated the expression of 3 GJ proteins, connexins 26, 30, and 43 (Cx26, Cx30, and Cx43) in DD.
Patients and methods
Fragments of Dupuytren’s tissue from 31 patients (mean age 56 (30–76) years, 24 male) were analyzed immunohistochemically and compared to control tissue for expression of the GJ proteins Cx26, Cx30, and Cx43 and also alfa-smooth muscle actin (α-SMA).
Results
14 of 31 samples could be attributed to the involutional phase (α-SMA positive) whereas 17 samples had to be considered cords in the residual phase (α-SMA negative). Expression of Cx26 and Cx43 was seen in 12 of the 14 samples from the involutional phase, and Cx30 was seen in 7 of these. Only 4 of the 17 samples from the residual phase showed any Cx, and there was none in the controls.
Interpretation
The high expression of GJ proteins Cx26, Cx30, and Cx43 in α-SMA positive myofibroblast-rich nodules, which are characteristic of the active involutional phase of DD, suggests that connexins could be a novel treatment target for the treatment of DD.
doi:10.3109/17453674.2013.871138
PMCID: PMC3940999  PMID: 24359029
18.  Good results in postoperative and hematogenous deep infections of 89 stable total hip and knee replacements with retention of prosthesis and local antibiotics 
Acta Orthopaedica  2013;84(6):509-516.
Background
Deep postoperative and hematogenous prosthesis infections may be treated with retention of the prosthesis, if the prosthesis is stable. How long the infection may be present to preclude a good result is unclear.
Patients and methods
We retrospectively studied 89 deep-infected stable prostheses from 69 total hip replacements and 20 total knee replacements. There were 83 early or delayed postoperative infections and 6 hematogenous. In the postoperative infections, treatment had started 12 days to 2 years after implantation. In the hematogenous infections, symptoms had been present for 6 to 9 days. The patients had been treated with debridement, prosthesis retention, systemic antibiotics, and local antibiotics: gentamicin-PMMA beads or gentamicin collagen fleeces. The minimum follow-up time was 1.5 years. We investigated how the result of the treatment had been influenced by the length of the period the infection was present, and by other variables such as host characteristics, infection stage, and type of bacteria.
Results
In postoperative infections, the risk of failure increased with a longer postoperative interval: from 0.2 (95% CI: 0.1–0.3) if the treatment had started ≥ 4 weeks postoperatively to 0.5 (CI: 0.2–0.8) if it had started at ≥ 8 weeks. The relative risk for success was 0.6 (CI: 0.3–0.95) if the treatment had started ≥ 8 weeks. In the hematogenous group, 5 of 6 infections had been treated successfully.
Interpretation
A longer delay before the start of the treatment caused an increased failure rate, but this must be weighed against the advantage of keeping the prosthesis. We consider a failure rate of < 50% to be acceptable, and we therefore advocate keeping the prosthesis for up to 8 weeks postoperatively, and in hematogenous infections with a short duration of symptoms.
doi:10.3109/17453674.2013.858288
PMCID: PMC3851662  PMID: 24171687
19.  2-stage revision recommended for treatment of fungal hip and knee prosthetic joint infections 
Acta Orthopaedica  2013;84(6):517-523.
Background and purpose
Fungal prosthetic joint infections are rare and difficult to treat. This systematic review was conducted to determine outcome and to give treatment recommendations.
Patients and methods
After an extensive search of the literature, 164 patients treated for fungal hip or knee prosthetic joint infection (PJI) were reviewed. This included 8 patients from our own institutions.
Results
Most patients presented with pain (78%) and swelling (65%). In 68% of the patients, 1 or more risk factors for fungal PJI were found. In 51% of the patients, radiographs showed signs of loosening of the arthroplasty. Candida species were cultured from most patients (88%). In 21% of all patients, fungal culture results were first considered to be contamination. There was co-infection with bacteria in 33% of the patients. For outcome analysis, 119 patients had an adequate follow-up of at least 2 years. Staged revision was the treatment performed most often, with the highest success rate (85%).
Interpretation
Fungal PJI resembles chronic bacterial PJI. For diagnosis, multiple samples and prolonged culturing are essential. Fungal species should be considered to be pathogens. Co-infection with bacteria should be treated with additional antibacterial agents.
We found no evidence that 1-stage revision, debridement, antibiotics, irrigation, and retention (DAIR) or antifungal therapy without surgical treatment adequately controls fungal PJI. Thus, staged revision should be the standard treatment for fungal PJI. After resection of the prosthesis, we recommend systemic antifungal treatment for at least 6 weeks—and until there are no clinical signs of infection and blood infection markers have normalized. Then reimplantation can be performed.
doi:10.3109/17453674.2013.859422
PMCID: PMC3851663  PMID: 24171675
20.  Different diagnostic properties of C-reactive protein, real-time PCR, and histopathology of frozen and permanent sections in diagnosis of periprosthetic joint infection 
Acta Orthopaedica  2013;84(6):524-529.
Background and purpose
There are several diagnostic tests for periprosthetic joint infection (PJI). We evaluated the properties of preoperative serum C-reactive protein (CRP), real-time polymerase chain reaction (PCR), and histopathological evaluation of frozen and permanent sections in clinical cases with culture-positive PJI.
Patients and methods
63 joints involving 86 operations were analyzed using serum CRP measurement prior to operation and tissue samples were collected intraoperatively for real-time PCR and histopathology. We calculated the sensitivity, specificity, likelihood ratio of positive test results (PLR), and likelihood ratio of negative test results (NLR) for each test in relation to positive microbiological culture results as the gold standard.
Results
The sensitivity and specificity of diagnosis with serum CRP were 90% and 85%, respectively. The corresponding values for real-time PCR and histopathology of frozen and paraffin tissue sections were 90% and 45%, 71% and 89%, and 90% and 87%, respectively. Serum CRP had a PLR of 5.8 and an NLR of 0.12, and real-time PCR had a PLR of 1.6 and an NLR of 0.18. The corresponding figures for frozen tissue sections were 6.6 and 0.32, and those for paraffin sections were 7.1 and 0.11, respectively.
Interpretation
The results suggest that real-time PCR and histopathology of frozen sections is a good combination. The former is suitable for screening, with its high sensitivity and good NLR, while the latter is suitable for definitive diagnosis of infection, with its excellent specificity and good PLR.
doi:10.3109/17453674.2013.862460
PMCID: PMC3851664  PMID: 24237422
21.  Monoblock all-polyethylene tibial components have a lower risk of early revision than metal-backed modular components 
Acta Orthopaedica  2013;84(6):530-536.
Background and purpose
With younger patients seeking reconstructions and the activity-based demands placed on the arthroplasty construct, consideration of the role that implant characteristics play in arthroplasty longevity is warranted. We therefore evaluated the risk of early revision for a monoblock all-polyethylene tibial component compared to a metal-backed modular tibial construct with the same articular geometry in a sample of total knee arthroplasties (TKAs). We evaluated risk of revision in younger patients (< 65 years old) and in older patients (≥ 65 years old).
Method
Fixed primary TKAs with implants from a single manufacturer, performed between April 2001 and December 2010, were analyzed retrospectively. Patient characteristics, surgeon, hospital, procedure, and implant characteristics were compared according to tibial component type (monoblock all-polyethylene vs. metal-backed modular). All-cause revisions and aseptic revisions were evaluated. We used descriptive statistics and Cox regression models.
Results
27,657 TKAs were identified, 2,306 (8%) with monoblock and 25,351 (92%) with modular components. In adjusted models, the risk of early all-cause revision (hazard ratio (HR) = 0.5, 95% confidence interval (CI): 0.3–0.8) and aseptic revision (HR = 0.6, CI: 0.3–1.2) was lower for the monoblock cohort than for the modular cohort. In older patients, the early risk of all-cause revision was 0.6 (CI: 0.4–1.0) for the monoblock cohort compared to the modular cohort. In younger patients, the adjusted risk of all-cause revision (HR = 0.3, CI: 0.1–0.7) and of aseptic revision (HR = 0.3, CI: 0.1–0.7) were lower for the monoblock cohort than for the modular cohort.
Interpretation
Overall, monoblock tibial constructs had a 49% lower early risk of all-cause revision and a 41% lower risk of aseptic revision than modular constructs. In younger patients with monoblock components, the early risk of revision for any cause was even lower.
doi:10.3109/17453674.2013.862459
PMCID: PMC3851665  PMID: 24237424
22.  Pre- and postoperative quality of life in patients treated for scoliosis 
Acta Orthopaedica  2013;84(6):537-543.
Background and purpose
There have been few prospective reports on quality of life in patients treated surgically for scoliosis. We compared patients with idiopathic, congenital, and neuromuscular scoliosis.
Methods
Data on 9- to 20-year-old patients were collected from the SweSpine registry. EQ-5D and (for a subset) SRS-22r were assessed preoperatively and after 1 and 2 years.
Results
211 patients had preoperative data: 168 with idiopathic, 11 with congenital, and 32 with neuromuscular scoliosis. Of the total, 158 patients responded to the 1-year follow-up and 149 responded to the 2-year follow-up. Preoperatively, the mean (SE) EQ-5D index was 0.76 (0.02) in the idiopathic group, 0.74 (0.07) in the congenital group, and 0.10 (0.06) in the neuromuscular group, and the SRS-22r index was 3.8 (0.1) in the idiopathic group, 4.0 (0.3) in the congenital group, and 3.3 (0.2) in the neuromuscular group. The mean EQ-5D increased by 0.06 points at 2 years in the idiopathic group, by 0.16 points in the congenital group, and by 0.15 points in the neuromuscular group. The mean SRS-22r index increased by 0.4 points at 2 years in the idiopathic group, by 0.4 points in the congenital group, and by 0.5 points in the neuromuscular group. The changes were statistically significant, with the exception of the congenital group. The number of patients who sustained at least 1 complication was 13 in the idiopathic group, 2 in the congenital group, and 9 in the neuromuscular group (p = 0.003).
Interpretation
The general quality of life in the idiopathic and neuromuscular group improved after surgery.
doi:10.3109/17453674.2013.854667
PMCID: PMC3851666  PMID: 24171684
23.  No superior performance of hydroxyapatite-coated acetabular cups over porous-coated cups 
Acta Orthopaedica  2013;84(6):544-548.
Background and purpose
Hydroxyapatite (HA) coating is believed to improve bone-implant ingrowth and long-term survival of prostheses. Recent studies, however, have challenged this view. Furthermore, HA particles may produce third-body wear and initiate aseptic loosening of implants. We report the performance of HA- and porous-coated acetabular cups in a prospective randomized trial.
Methods
This was an 8-year follow-up study of our previously published prospective randomized study to compare clinical outcomes, survival, periprosthetic bone mineral density, migration, and wear rates of HA- and porous-coated acetabular cups. Dual X-ray absorptiometry (DXA) and Ein Bild Roentgen Analyse (EBRA) measurements were used. 100 patients who underwent unilateral cementless total hip arthroplasty were randomized to either porous-coated cups or HA-coated cups. Patients were examined preoperatively and at 3, 6, and 9 months, and also 1, 3, and 8 years after surgery. 81 patients were available for 8-year follow-up, 40 with porous-coated cups and 41 with HA-coated cups.
Results
Age, sex, bone mineral density, and clinical results (Harris hip score) were similar in the 2 groups. The survival, wear, and migration patterns of the cups were also similar in both groups. The results of periprosthetic bone mineral density scans in region of interest 2 was in favor of the porous-coated cups, but there were no differences between the 2 groups in all the remaining regions of interest.
Interpretation
HA coating had no statistically significant effect on clinical results, survival, wear, or migration at the 8-year follow-up.
doi:10.3109/17453674.2013.854665
PMCID: PMC3851667  PMID: 24171680
24.  Adverse reaction to metal debris after ReCap-M2A-Magnum large-diameter-head metal-on-metal total hip arthroplasty 
Acta Orthopaedica  2013;84(6):549-554.
Background and purpose
The clinical findings of adverse reaction to metal debris (ARMD) following large-diameter-head metal-on-metal total hip arthroplasty (LDH MoM THA) may include periarticular fluid collections, soft tissue masses, and gluteal muscle necrosis. The ReCap-M2a-Magnum LDH MoM THA was the most commonly used hip device at our institution from 2005 to 2012. We assessed the prevalence of and risk factors for ARMD with this device.
Methods
74 patients (80 hips) had a ReCap-M2a-Magnum LDH MoM THA during the period August 2005 to December 2006. These patients were studied with hip MRI, serum chromium and cobalt ion measurements, the Oxford hip score questionnaire, and by clinical examination. The prevalence of ARMD was recorded and risk factors for ARMD were assessed using logistic regression models. The mean follow-up time was 6.0 (5.5–6.7) years.
Results
A revision operation due to ARMD was needed by 3 of 74 patients (3 of 80 hips). 8 additional patients (8 hips) had definite ARMD, but revision was not performed. 29 patients (32 hips) were considered to have a probable or possible ARMD. Altogether, 43 of 80 hips had a definite, probable, or possible ARMD and 34 patients (37 hips) were considered not to have ARMD. In 46 of 78 hips, MRI revealed a soft tissue mass or a collection of fluid (of any size). The symptoms clicking in the hip, local hip swelling, and a feeling of subluxation were associated with ARMD.
Interpretation
ARMD is common after ReCap-M2a-Magnum total hip arthroplasty, and we discourage the use of this device. Asymptomatic patients with a small fluid collection on MRI may not need instant revision surgery but must be followed up closely.
doi:10.3109/17453674.2013.859419
PMCID: PMC3851668  PMID: 24171688
25.  The natural history of the hemiarthroplasty for displaced intracapsular femoral neck fractures 
Acta Orthopaedica  2013;84(6):555-560.
Background
Numerous papers have been published on the medium- and long-term results of hemiarthroplasties (HAs) after femoral neck fracture in the elderly. We were not aware of any articles that describe the outcome of HA until the patient dies.
Methods
Between 1975 and 1989, 307 bipolar hemiarthroplasties were performed in 302 consecutive patients with a displaced femoral neck facture. Patients with osteoarthritis of the hip, rheumatoid arthritis (RA), or senile dementia were not included in the study. All patients were followed annually until they died or until they needed a revision operation.
Results
The mortality rate was 28% after 1 year, and 63% after 5 years. The last patient who did not need a revision operation died in October 2010. Revision operations for aseptic loosening, protrusion, or both had to be performed in 34 patients (16%). A difference in reoperation rate was observed between patients less than 75 years of age (38%) and those who were older (6%).
Interpretation
Apart from age below 75 years, male sex appeared to be predictive of a revision operation. HA is a safe and relatively inexpensive treatment for patients over 75 years of age with a displaced femoral neck fracture.
doi:10.3109/17453674.2013.867763
PMCID: PMC3851669  PMID: 24286565

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