Lennart Sanzén

Total knee arthroplasty after failed proximal tibial valgus osteotomy

The results of total knee arthroplasty were evaluated in 113 patients with gonarthrosis (14 patients with and 99 without prior operation with proximal tibial valgus osteotomy). There was no difference in the final result after follow-up periods of 4-9 years with respect to average Hospital for Special Surgery score. degree of knee flexion, and later knee revisions between the 14 osteotomized and 99 nonosteotomized patients. The average femorotibial angle did not differ between the groups; neither did the average wear of the tibial polyethylene. No difference was found in operative time, but a significantly greater blood loss and other postoperative complications were noted among the previously osteotomized group of patients, indicating a more complicated procedure for the knee arthroplasty operation compared with the nonosteotomized group of patients.

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 (RSA). 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.

Total hip replacement in patients with hemophilia: 13 hips in 11 patients followed for 1-16 years

During 1973-88, we performed 13 total hip replacements in 11 hemophilia patients, mean age 46 (25-65) years. During the operation, blood loss averaged 920 mL, and a mean of 120,000 units of factor VIII/IX were used. The mean duration of follow-up was 7 (1-16) years. 5 hips became loose within 6 years, and a further one after 13 years. 4 hips were revised, 2 of them due to infection in patients who were also seropositive for HIV. At the latest follow-up, 10 patients were alive. 6 had no hip pain and 7 could walk at least 1,000 meters at a time. Although these results are inferior to those obtained in arthrosis, total hip replacement should be considered in hemophiliac patients.

THE PROGNOSIS AND TREATMENT OF DISLOCATED TOTAL HIP ARTHROPLASTIES WITH A 22 MM HEAD

We studied the risk of recurrent dislocation in 121 primary and 39 revision Charnley or Charnley hybrid total hip arthroplasties which had been treated for a primary dislocation between 1979 and 1995. Only 35% of these hips had no further dislocation or a revision for instability within one year. The rates of survival gradually declined with time or if a second, third or fourth dislocation occurred. The risk of recurrence was greater in men, but was not related to age, diagnosis, time of the first dislocation or whether the index operation had been a primary or a revision procedure. Operative treatment included 15 reoperations leaving intact components, 50 revisions, and permanent removal of the femoral stem in seven patients. The operation was successful in four patients with reoperations and in 36 who had an exchange procedure within two years. Treatment was successful in 35 of 49 hips in which it was possible to correct a technical error compared with 5 out of 16 hips in which malposition of the components was not seen (p = 0.007).

Periprosthetic low-grade hip infections. Erythrocyte sedimentation rate and C-reactive protein in 23 cases.

We followed 23 patients from the primary total hip arthroplasty to revision for a bacteriologically proven deep infection with a low virulent organism. The median time to revision was 14 (4-65) months. During this period, the maximum ESR value was median 50 (22-110) mm and the maximum CRP value was 35 (9-95) mg/L. 25 of the 98 CRP values recorded were normal (< 9 mg/L) and 22/89 ESR values were below 30 mm/h. In 6 patients, all CRP values were below 20 mg/L, but 5 of these patients had an ESR > 30 mm. Before the revision, normal values for both tests were found in only 1 patient. Both normal values and slight-to-moderate increases in ESR and/or CRP are consistent with a low-grade periprosthetic hip infection. We recommend that ESR should be determined preoperatively in all patients scheduled for total hip replacement to establish a baseline.

Radiographic Wear Assessment in a Total Knee Prosthesis 5- to 9-Year Follow-up Study of 158 Knees

One hundred fifty-eight Porous-Coated Anatomic (Howmedica, Rutherford, NJ) primary total knee prostheses were evaluated clinically and radiographically to measure the remaining thickness of the plastic insert. Anteroposterior radiographs were taken with the beam guided parallel to the tibial plate by a fluoroscope. The knees were forced into varus and valgus, and the heights of the medial and lateral joint spaces, respectively, were measured with a digitizing table. Plastic insert wear could be calculated after correction with a magnification error factor, established by dividing the projected width of the tibial plate by the true size of the used component. After a mean follow-up period of 84 months (range, 58-116 months), wear was significantly higher for patients with osteoarthritis than rheumatoid arthritis and was 1.4 mm versus 0.7 mm medially (P < .0001) and 0.7 mm versus 0.4 mm laterally (P = .01). Wear was not correlated to thickness of the plastic insert or length of follow-up period. Young age or varus alignment contributed slightly to the amount of wear.

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.

Air contamination during total hip arthroplasty in an ultraclean air enclosure using different types of staff clothing.

Air contamination was measured in a down-flow, clean air enclosure during 50 total hip arthroplasties to compare the effect of different scrub suits and operating gowns. In one series, with cotton clothes, the operating gowns used were either disposable nonwoven operating gowns or total body exhaust gowns. With the exhaust gowns the median air contamination, measured as colony-forming units (cfu)/m3, was reduced by about 5 times, to 0.3. In another series, nonwoven operating gowns were used together with scrub suits made of either cotton or one of two types of synthetic materials. The latter two scrub suits were equipped with elastic sealings at the openings. With both of these types the median air contamination, compared to cotton scrub suits, was reduced by about one half, to 0.4 cfu/m3. The authors conclude that both specially designed scrub suits and exhaust gowns can further reduce an already low level of bacterial air contamination in a down-flow, clean air enclosure.

Total hip replacement with a zirconium oxide ceramic femoral head: A RANDOMISED ROENTGEN STEREOPHOTOGRAMMETRIC STUDY

We investigated the wear characteristics and clinical performance of four different total hip joint articulations in 114 patients. Wear and migration was measured by roentgenstereophotogrammetric analysis at five years or at the last follow-up. The mean annual wear was 0.11 mm for a stainless steel/Enduron articulation, 0.34 mm for stainless steel/Hylamer cup, 0.17 mm for zirconium oxide ceramic/Enduron and 0.40 mm for zirconium oxide ceramic/Hylamer. The difference between the groups was significant (p < 0.008) except for stainless steel/Hylamer vs zirconium oxide ceramic/Hylamer (p = 0.26). At present, 12 patients have undergone a revision procedure, four at five years and eight thereafter. No patient who received a stainless steel/Enduron articulation at their primary replacement required revision. Conflicting results have been reported about the performance of the zirconium oxide ceramic femoral head, but our findings suggest that it should not be used with a polymethylmethacrylate acetabular component. Hylamer has already been withdrawn from the market.

Migration of uncemented, long-stem femoral components in revision hip arthroplasty A 2-8 year clinical follow-up of 45 cases and radiostereometric analysis of 13 cases

We reviewed after 48 (24-90) months the clinical results in 45 cases of revision hip arthroplasties where an uncemented, long-stem femoral prosthesis (BIAS, Zimmer) had been used. A subgroup of 13 cases was followed with radiostereometric analysis (RSA) for 2 years. 3/45 cases had been revised, another 12 had unsatisfactory pain scores. The median Harris score was 69 (26-99). 12/13 stems migrated; 11 subsided 4.1 (0.4-7.9) mm, and 8 migrated posteriorly 2.9 (1.9-9.6) mm. The poor clinical results and large migrations speak against the use of this prosthesis in revision hip arthroplasty.