Long-term outcomes after different types of Horne and Tanzer olecranon fractures.

BACKGROUND: It is unclear whether the outcomes differ after different Horne and Tanzer types of olecranon fractures. MATERIALS AND METHODS: We evaluated 40 men and 55 women with isolated olecranon fractures, journals and radiographs from fracture event. The fractures were classified according to Horne and Tanzer. After a mean 19 years after the fracture events, we evaluated subjective, clinical and radiographic outcomes, using the uninjured arms as controls. RESULTS: 95% of patients with type I fractures reported, at follow-up, no differences between the elbows, 80% with type II fractures and 95% with type III fractures (p = 0.43). The three types of fractures had no differences in elbow range of motion or hand grip strength (when comparing injured and uninjured arms) and the proportions of individuals with radiographic elbow degenerative changes or joint space reduction were no different (all p > 0.05). Individuals with elbow degenerative changes had no inferior subjective elbow function compared to individuals with normal radiographs (p = 0.66), in contrast to those with joint space reduction compared to individuals with normal radiographs (p < 0.001). INTERPRETATION: All types of Horne and Tanzer olecranon fractures have favourable long-term outcome. Elbow joint space reduction is associated with inferior subjective elbow function while degenerative changes are not.

Evaluation of metal artifacts in clinical MR images of patients with total hip arthroplasty using different metal artifact-reducing sequences.

PURPOSE: To evaluate the distortion and artifact area of metal in MR images and to compare artifact reduction using different metal artifact-reducing sequences in patients with metal-on-metal (MoM) and non-MoM total hip prostheses. MATERIALS AND METHODS: Thirty-six MoM and 15 non-MoM prostheses were examined in a 1.5-T MR scanner using T1-weighted (T1-w) sequences: turbo spin echo (TSE) high-readout bandwidth (hiBW), T1-w; TSE view angle tilting (VAT), T1-w; TSE VAT + slice encoding for metal artifact correction (SEMAC); short tau inversion recovery (STIR) hiBW or matched RF pulses (mRFp). Distortion was quantified using a new method measuring the acetabular roof angle (ARA). The artifact area was defined in the mid-coronal plane of the artifact. RESULTS: The T1 VAT + SEMAC sequence showed the least distortion compared to T1 VAT and T1-hiBW (150°, 127° and 102°, p < 0.001, in MoM; 152°, 143° and 128°, p ≤ 0.014, in non-MoM). The artifact area was smaller in MoM prostheses using the T1 VAT sequence compared to T1 hiBW and T1 VAT + SEMAC (2506 mm(2), 3160 mm(2) and 3214 mm(2), p < 0.001) and smaller in non-MoM prostheses using T1 VAT compared to T1-hiBW (4296 mm(2) and 4831 mm(2), p = 0.041). STIR-mRFp substantially reduced the artifact size compared with STIR-hiBW (MoM 4559 mm(2) and 6323 mm(2); non-MoM 5625 mm(2) and 8764 mm(2), p < 0.001). CONCLUSION: Metal artifacts in MR imaging examinations of hip prostheses can be evaluated for distortion using a distortion angle (ARA) and the degree of signal artifact as determined by measuring the largest cross-sectional artifact area. T1 VAT + SEMAC showed the least distortion; T1 VAT and STIR-mRFp were most efficient for reduction of the artifact area.

MR imaging with metal artifact-reducing sequences and gadolinium contrast agent in a case-control study of periprosthetic abnormalities in patients with metal-on-metal hip prostheses.

OBJECTIVE: To apply and compare magnetic resonance imaging (MRI) metal artifact reducing sequences (MARS) including subtraction imaging after contrast application in patients with metal-on-metal (MoM) hip prostheses, investigate the prevalence and characteristics of periprosthetic abnormalities, as well as their relation with pain and risk factors. MATERIALS AND METHODS: Fifty-two MoM prostheses (35 cases with pain and or risk factors, and 17 controls) in 47 patients were examined in a 1.5-T MR scanner using MARS: turbo spin echo (TSE) with high readout bandwidth with and without view angle tilting (VAT), TSE with VAT and slice encoding for metal artifact correction (SEMAC), short tau inversion recovery (STIR) with matched RF pulses, and post-contrast imaging. The relations of MRI findings to pain and risk factors were analyzed and in five revised hips findings from operation, histology, and MRI were compared. RESULTS: TSE VAT detected the highest number of osteolyses. Soft tissue mass, effusion, and capsular thickening were common, whereas osteolysis in acetabulum and femur were less frequent. Contrast enhancement occurred in bone, synovia, joint capsule, and the periphery of soft tissue mass. There was no significant relation between MRI findings and pain or risk factors. CONCLUSIONS: MARS and gadolinium subtraction imaging are useful for evaluation of complications to MoM prosthesis. TSE VAT had the highest sensitivity for osteolysis. Contrast enhancement might indicate activation of aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). Pain, small head, or steep prosthesis inclination angle are not useful predictors of periprosthetic abnormalities, and wide indications for MR follow-up are warranted.

The Elite-Plus stem migrates more than the flanged Charnley stem.

BACKGROUND AND PURPOSE: The Charnley Elite-Plus stem was introduced in 1993 as a presumed improvement of the flanged Charnley stem. We started this study in 1996 to investigate the migratory pattern of the Elite-Plus stem. PATIENTS AND METHODS: We followed 114 patients with osteoarthritis and a primary total hip replacement with the Elite-Plus stem. Mean age at the time of operation was 64 (50-76) years. The mean follow-up time was 6.5 (2-7) years. Radiographs were evaluated with respect to cementing technique, migration, and wear measured by radiostereometry (RSA). RESULTS: The stem survival was 98% (CI: 96-100) at 7 years and 92% (CI: 86-97) at 10 years. Mean migration of the femoral head was 0.35 mm (SD 0.3) medially, 0.51 mm (SD 0.6) distally, and 1.1 mm (SD 1.8) in the dorsal direction. Mean total point motion was 1.7 mm (SD 1.7). The migration of the stems stabilized after 5 years in the medial and dorsal directions, but continued to subside slightly. Migration along any of the axes was higher if the cementing technique was inferior. INTERPRETATION: Patients with a Charnley Elite-Plus stem and defects in the cement mantle or other signs of inferior implantation technique should be carefully monitored.

A clinical and radiostereometric study of the cemented PFC-sigma prosthesis: a 5-year study of 29 cases with a fixed bearing.

The press-fit condylar (PFC) cruciate-retaining total knee prosthesis is well documented in the literature. In 1997, a modification of the femoral component was introduced, and the prosthesis was renamed PFC-Sigma. The alteration may influence the migratory and rotational pattern of the tibial component and thus long-time survival rate. In this radiostereometric analysis, we found that the micromotion of the PFC-Sigma prosthesis differs slightly from the original PFC design, an advantage of the PFC-Sigma prosthesis. The median maximum total point motion at 5 years was 0.64 mm for the PFC-Sigma design and 0.79 mm for the previous version of PFC (P = .9). However, the PFC-Sigma rotated less around the transverse (x) axis than did the PFC (medians, 0.22 mm and 0.48 mm, respectively; P = .04). From the radiostereometric, radiographic, and clinical data, we conclude that the PFC-Sigma knee prosthesis can be used with confidence.

Cross-linked N-telopeptide of type I collagen (NTx) in urine as a predictor of periprosthetic osteolysis.

Periprosthetic osteolysis is often nonsymptomatic and hard to visualize by conventional radiography. Cross-linked N-telopeptide of type I collagen (NTx), a marker of osteoclast mediated bone resorption, has been suggested to evaluate local particulate-induced osteolysis in patients operated on with a total hip prosthesis. Urine specimens were sampled after hip joint replacement in 160 patients. NTx was analyzed by a commercially available ELISA kit. Osteolysis was identified in the acetabulum and confirmed at operation. Using analysis of covariance to correct for differences in age, gender, and time after operation, NTx (mean SD) was 36+/-12 BCE/nM creatinine in patients with osteolysis (n=33) and 27+/-13 BCE/nM creatinine in patients without osteolysis (n=127) (p=0.003). Eighteen hips of 38 (47%), demonstrating an annual wear of more than 0.2 mm and an NTx value above 29 BCE/nM creatinine, had been revised due to osteolysis. The osteolysis prevalence in this group was increased 10 times (CI 4-23, p<0.05). Indeed, NTx release and annual wear were both associated with increased prevalence of osteolysis, however, independently of each other. NTx seems a feasible marker of periprosthetic osteolysis. A preoperative baseline NTx level is likely needed for its use as a predictor of periprosthetic osteolysis in individual cases.

Identification of femoral head center of bipolar hemiarthroplasy in radiostereometric analysis with elementary geometrical shape models.

Elementary geometrical shape (EGS) models are useful in radiostereometric analysis (RSA) on hip stems because tantalum markers attached to the stems can be omitted. In order to create an EGS model of a femoral stem, the center of the femoral head has to be identified. The contour of the femoral head is recommended to be used. However, the contour of the femoral head cannot be detected exclusively by computer if it is combined with a bipolar head or a metal cup. We therefore hypothesized that the contour of the outer head of bipolar hemiarthroplasty can be included in the EGS model as well as the femoral head contour. We calculated the time required for the detection of the contour, the precision of analysis and the stem micromotion at 2 years using the two different methods in the same picture set and compared the results. The detection of the bipolar head contour was 10 times faster than that of the femoral head contour. The precision for subsidence was 0.16 mm in EGS RSA with the femoral head contour, and 0.15 mm with the bipolar head contour (p=0.68). The precisions were comparable and clinically acceptable. There was no significant difference between the results of the 2-year micromotion with the two different methods. We conclude that this new method is applicable to measure stem micromotion of hemi-arthroplasty with EGS RSA and the method facilitates the Radiostereometric analysis.

Osteoarthritis of the Distal Interphalangeal and First Carpometacarpal Joints is Associated with High Bone Mass in Women and Small Bone Size and Low Lean Mass in Men.

OBJECTIVE: To determine if primary hand osteoarthritis (OA) is associated with abnormal bone and anthropometric traits. METHODS: We used DXA to measure total body bone mineral density (BMD), femoral neck width (bone size) and total body lean and fat mass in 39 subjects with hand OA (primary DIP and/or CMC I) and 164 controls. Data are presented as mean Z-scores or Odds Ratios (OR) with 95% confidence intervals. RESULTS: Women with hand OA had (compared to controls) higher BMD (0.5(0.1,0.9)) but similar bone size (-0.3(-0.8,0.2)), lean mass (0.3(-0.3,0.9)), fat mass (-0.1(-0.6,0.5)) and BMI (0.0(-0.6,0.6)). Men with hand OA had (compared to controls) similar BMD (-0.1(-0.7,0.6)), smaller bone size (-0.5(-1.1,-0.01)), lower lean mass (-0.6(-1.1,-0.04)), and similar fat mass (-0.2(-0.7,0.4)) and BMI -0.1(-0.6,0.6). In women, each SD higher BMD was associated with an OR of 1.8 (1.03, 3.3) for having hand OA. In men each SD smaller bone size was associated with an OR of 1.8 (1.02, 3.1) and each SD lower proportion of lean body mass with an OR of 1.9 (1.1, 3.3) for having hand OA. CONCLUSION: Women with primary DIP finger joint and/or CMC I joint OA have a phenotype with higher BMD while men with the disease have a smaller bone size and lower lean body mass.

Patients with Osteoarthritis in all Three Knee Compartments and Patients with Medial Knee Osteoarthritis Have a Phenotype with High Bone Mass and High Fat Mass but Proportionally Low Lean Mass.

BACKGROUND AND PURPOSE: Cross-sectional studies have shown that patients with primary hip osteoarthritis (OA) have higher bone mineral density (BMD), higher BMI, lower lean body mass, and higher fat content. But it is unknown if this phenotype is found also in patients with knee OA and if it precedes OA or manifests as a result of the disease. PATIENTS AND METHODS: We included 21 women and 18 men (mean age, 71 years; range, 48-85 years) with primary OA in all three knee compartments, 17 women and 56 men (mean age, 55 years; range, 34-74 years) with primary medial knee OA and 122 women and 121 men without OA as controls. We measured total body BMD (g/cm(2)), fat and lean mass (%) by dual energy X-ray absorptiometry and also registered height and weight to calculate BMI (kg/m(2)). Z-scores were calculated for each individual. Data are presented as means with 95% confidence intervals within brackets. RESULTS: Individuals with primary OA in all three knee compartments had the following Z-scores: total body BMD 0.4 (0.0, 0.9); BMI 1.2 (0.7, 1.6); proportion of lean mass -0.6 (-1.1, -0.1); proportion of fat mass 0.4 (0.0, 1.8). Individuals with medial knee OA had the following Z-scores: total body BMD 0.4 (0.3, 0.6); BMI 1.1 (0.8, 1.4); proportion of lean mass -0.8 (-1.3, -0.9); proportion of fat mass 0.9 (0.7, 1.1). INTERPRETATIONS: A phenotype with higher BMD, higher BMI, higher fat mass, and proportionally lower lean body mass is evident in individuals with primary OA in all three knee compartments and in patients with only medial knee OA.

Weight bearing radiographs are not necessary for measurement of polyethylene penetration in total hip prostheses: a radiostereometric study of 111 patients examined in weight-bearing and supine position.

BACKGROUND: Controversy exists as to whether polyethylene (PE) penetration of hip prostheses is underestimated when the measurements are made on radiographs obtained in supine position as compared to weight-bearing position. PATIENTS AND METHODS: We examined 111 patients by radiostereometric analysis (RSA) in the supine and weight-bearing positions. RESULTS: The mean 3-D penetration was 0.68 mm (SD 0.58, range 0.04-3.05) for the supine position and 0.70 mm (SD 0.57, range 0.08-3.01) for the weight-bearing position. The correlation between supine and weight-bearing examinations was 0.99 (p < 0.001). The degree of penetration made no difference. There was no statistically significant difference as to whether the first examination was performed early, i.e. after 3 months, or after 12 months (p = 0.7). INTERPRETATION: The small systematic difference in penetration values between the supine and the weight-bearing positions is of no clinical or methodological importance.

Untreated congenital and posttraumatic high dislocation of the hip treated by replacement in adult age: 22 hips in 16 patients followed for 1-8 years.

Between 1993 and 2001, we replaced 22 hips in 16 patients with high dislocation of the hip. All but 1 case was due to congenital dislocation. In all cases the femur was osteotomized below the lesser trochanter and a straight uncemented stem inserted in the medullary canal. The acetabular prostheses were inserted at the site of the original acetabulum, usually after augmenting the acetabular rim by using the medial half of the resected proximal femur. The lateral part of the proximal femur with the intact attachment of the gluteus medius muscle was transposed and fixed to the femoral diaphysis thereby restoring direction of muscle pull. The HHS score increased from a median value of 42 points preoperatively to a median of 86 points after median 25 months of follow-up. Limp, which before surgery was severe in all cases, was less marked or had disappeared at follow-up. The legs had been lengthened median 2.5 (1.0-4.5) cm. No postoperative infections occurred. Palsy or loss of sensory function was not observed in any patient. Dislocation was the commonest complication. It occurred in 3 hips, 2 of which had to be revised to ensure stability.

Catastrophic failure of an uncemented acetabular component due to high wear and osteolysis: an analysis of 154 omnifit prostheses with mean 6-year follow-up.

BACKGROUND: The purposes of this study were (1) to evaluate the wear pattern of the hydroxyapatite-coated "Dual Radius" Omnifit cup, (2) to investigate whether wear is correlated to any demographic or prosthesis-related factors, and (3) to describe micromotion of both the cup and the stem. PATIENTS AND METHODS: 154 hips were implanted between 1990 and 1996 and followed for an average of 6 years. Wear was measured according to the "Charnley-duo" method and, in 79 hips, with radiostereometry IRSA). RSA was also used to evaluate micromotion. We analyzed the femoral heads using scanning electron microscopy, energy dispersive X-ray spectroscopy and an atomic force microscope. RESULT: 66 cups were revised and had a mean annual wear of 0.32 mm compared to 0.12 mm in hips not revised. Osteolytic processes were observed in 35 hips but at revision osteolysis was present in 51 cases. 43/66 sockets were loose. Micromotion evaluated by RSA, weight, age, side, size of cup, screws, polyethylene thickness or shelf-life of the polyethylene did not correlate to wear, whereas male gender did. INTERPRETATION: It is still unclear why about half of our cases had an abnormal wear rate. Annual wear exceeding 0.2 mm is prognostic of late failure and should be considered a warning sign.

Accuracy of radiographic and radiostereometric wear measurement of different hip prostheses: an experimental study.

BACKGROUND: In vivo measurement of wear in the ball and socket articulation of total hip arthroplasties is of interest in the evaluation of both existing and new implants. Controversy reigns regarding the accuracy of different radiological measurement techniques and in particular how accuracy has been assessed. MATERIAL AND METHODS: We assessed the accuracy of 2 radiostereometric (RSA) techniques for wear measurement and 3 standard radiographic techniques, namely Imagika (image analyzing software), Imagika corrected for head center displacement, and the Charnley Duo method. 5 custom-made adjustable phantoms with different prosthetic components were used. RESULTS: In 20 measurements of all 5 phantoms at 3 levels of simulated wear (0.2 mm, 1.0 mm and 1.5 mm), the mean measurement error of the digital RSA examinations was 0.010 mm (accuracy 0.42). The corresponding error values for the three radiographic techniques were 0.19 (accuracy 1.3) for Charnley Duo, 0.13 (accuracy 1.3) for Imagika corrected, and 1.021 (accuracy 2.99) for Imagika. Measurement error decreased from 0.011 mm with ordinary RSA to 0.004 with RSA digital measurement. Head size, direction of wear in relation to the cup or type of prosthetic component did not influence the measurement error. The results of Charnley Duo and Imagika corrected were similar but the latter had an inexplicable systematic error in measuring one of the phantoms. Imagika had the worst results due to its inability to compensate for the out-of-head center effect. Alumina heads were difficult to analyze with all methods. INTERPRETATION: By using the ISO standard for assessing accuracy, RSA can be expected to measure wear with an accuracy of about 0.4 mm irrespective of prosthetic component studied or direction of wear, whereas the best technique, in our study, based on standard radiographs can be accurate to about 1.3 mm.