Niek Tulp - Academia.edu (original) (raw)

Papers by Niek Tulp

Research paper thumbnail of In vivo wear reduction of argon compared to air sterilized UHMW-polyethylene liners

Archives of Orthopaedic and Trauma Surgery, 2009

To date, no studies have been published that report on the in vivo advantages of sterilisation in... more To date, no studies have been published that report on the in vivo advantages of sterilisation in argon (ARGON) versus air (AIR) of UHMWPE liners with respect to wear extend and pattern in uncemented total hip arthroplasty. Femoral penetration rates were measured in 93 AIR and 79 ARGON liners, during a mean follow-up of 8 (3-12) years. During the first 3 years after implantation, both groups showed no differences in mean wear rate (P = 0.13). Thereafter, the ARGON liner demonstrated a decrease in wear rate of 0.04 mm/year from 4 to 6 years (P = 0.006), 0.14 mm/year from 7 to 9 years (P < 0.001), and 0.33 mm/year beyond 9 years follow-up (P = 0.015) compared to the AIR liner. One AIR acetabular component required revision.

Research paper thumbnail of Synovectomy of the elbow in rheumatoid arthritis. Long-term results

The Bone & Joint Journal

We reviewed 61 elbow synovectomies in 50 patients with rheumatoid arthritis, with follow-up varyi... more We reviewed 61 elbow synovectomies in 50 patients with rheumatoid arthritis, with follow-up varying from 4 to 10 years (mean 6.5 years). The results were graded as satisfactory in 70%, with no significant difference in the results between joints which were radiologically good before operation and those which had been destroyed. Longer term results were analysed of 27 elbow synovectomies in 22 patients followed up for over six years. The results were satisfactory in 67% of the patients in both 1981 and in 1987, with no deterioration over this period.

Research paper thumbnail of Early failure of Pavlik harness treatment of developmental hip dysplasia: clinical and ultrasound predictors

Journal of pediatric orthopedics

Research paper thumbnail of Factors associated with reduced early survival in the Oxford phase III medial unicompartment knee replacement

The Knee, 2010

The aim of this study was to determine the prognostic value of preoperative patellofemoral osteoa... more The aim of this study was to determine the prognostic value of preoperative patellofemoral osteoarthritis, BMI and age for implant survival of unicompartmental knee arthroplasty (UKA) performed in patients meeting strict admission criteria. The data and radiographs of 437 unilateral Oxford phase III procedures (Biomet, Bridgend, UK) were analysed. All procedures were carried out or supervised by 13 specialised knee surgeons in three different hospitals. The study group comprised 437 patients with a median follow of 2.6 years (0.1-7.9). The cumulative standard case survival rate at 5 years, when there were still 101 patients at risk, was 84.7% (CI-95%: 80.1-89.3%). Young age (b 60 years) was associated with a 2.2-fold increased adjusted risk of revision (CI: 1.08-4.43; p = 0.03). The preoperative presence of radiological features of patellofemoral osteoarthritis was associated with a 0.3-fold reduced adjusted risk of revision (CI: 0.11-0.89; p = 0.03). BMI N 30 kg/m 2 , gender, the surgeon performing the operation (either as an individual or categorised by annual surgical UKA caseload, i.e., more or less than 10 UKAs) and the hospital in which surgery took place did not predict implant survival of UKA. We conclude that young patients (b 60 years) experience an increased early risk of revision for UKA when compared to older patients (N 60 years). Obesity (BMI N 30 kg/m 2 ) and preoperative patellofemoral osteoarthritis are not associated with a decreased implant survival and therefore should not be considered risk factors in this context.

Research paper thumbnail of Treatment of developmental dysplasia of the hip with Pavlik harness: prospective study in Graf type IIc or more severe hips

Journal of Pediatric Orthopaedics B, 2004

Research paper thumbnail of Results of Pavlik Harness Treatment for Neonatal Hip Dislocation as Related to Graf's Sonographic Classification

Journal of Pediatric Orthopaedics, 2000

In this prospective study, 41 dislocated hips in 40 patients were classified according to Graf&am... more In this prospective study, 41 dislocated hips in 40 patients were classified according to Graf's sonographic classification. Of them, 29 hips were Graf type III and 12 hips Graf type IV. All were treated in a Pavlik harness to relocate the dislocated hip dynamically. In type III hips, this was successful in 97% and 50% in type IV hips. We conclude that Graf's classification in dislocated hips has prognostic significance in treatment with the Pavlik harness.

Research paper thumbnail of Mid-term wear characteristics of an uncemented acetabular component

Journal of Bone and Joint Surgery - British Volume, 2005

We investigated the rate of polyethylene wear of a cementless acetabular component at different p... more We investigated the rate of polyethylene wear of a cementless acetabular component at different periods of follow-up in order to test the hypothesis than an irrecoverable deformation process (creep) was followed by an initially low, but gradually increasing wear rate. We studied prospectively 93 uncemented total hip arthroplasties in 83 patients (mean age 50 years (22 to 63)) with a mean follow-up of 8.2 years (3 to 12). We measured the penetration of the femoral head from radiographs taken immediately after surgery at three, six and nine years, or at the latest follow-up. The median wear rate was 0.17 mm per year in the first three years, a finding which we considered to be caused by creep. Thereafter, the rate of wear declined to 0.07 mm per year (four- to six-year period) and then increased to 0.17 mm per year (seven to nine years) and 0.27 mm per year (more than nine years), which we considered to be a reflection of genuine polyethylene wear. After the nine-year follow-up the wear rates were higher in patients with marked osteolysis. We found no relationship between the inclination angle of the acetabular component or femoral head orientation and the rate of wear. No acetabular component required revision.

Research paper thumbnail of Total Ankle Replacement Outcome in Low Volume Centers: Short-Term Followup

Foot & Ankle International, 2010

The indication for total ankle replacement (TAR) as an alternative to ankle fusion continues to b... more The indication for total ankle replacement (TAR) as an alternative to ankle fusion continues to be a much-debated topic. The reported survival of TAR at midterm followup is approximately 90%. The aim of this study was to compare functional outcome and survival of TAR in low volume centers versus high volume centers. A retrospective cohort study was carried out in four low volume centers. Sixty-four Salto TARs were performed between 2003 and 2007 in 60 patients. Fifty-five (59 TAR) patients were eligible for followup with 28 men. Standardized American Orthopaedic Foot and Ankle Society (AOFAS) scores, patient satisfaction, and range of motion (ROM) were measured. Standardized and dynamic radiographs were used for evaluation of radiolucencies, ROM and component alignment. Seven of the 59 ankle prostheses had to be revised: five for loosening and two for deep infection. Three of the five revised for loosening went on to fusion, and in two a revision of one of the components was performed. Both infected ankles were fused. Five patients declined to participate this study, among these two were TAR failures. Survival with revision as the endpoint was 86% at final followup. The average AOFAS score was 75 (SD ± 15). On dynamic radiographs the ROM was 22 degrees (SD ± 8) in the tibiotalar joint. This study demonstrated that functional results of total ankle replacement in low volume centers were comparable to most high volume centers but survival was lower especially when we consider our shorter followup than most comparable series.

Research paper thumbnail of Poor accuracy of freehand cup positioning during total hip arthroplasty

Archives of Orthopaedic and Trauma Surgery, 2007

Several studies have demonstrated a correlation between the acetabular cup position and the risk ... more Several studies have demonstrated a correlation between the acetabular cup position and the risk of dislocation, wear and range of motion after total hip arthroplasty. The present study was designed to evaluate the accuracy of the surgeon's estimated position of the cup after freehand placement in total hip replacement. Peroperative estimated abduction and anteversion of 200 acetabular components (placed by three orthopaedic surgeons and nine residents) were compared with measured outcomes (according to Pradhan) on postoperative radiographs. Cups were placed in 49.7° (SD 6.7) of abduction and 16.0° (SD 8.1) of anteversion. Estimation of placement was 46.3° (SD 4.3) of abduction and 14.6° (SD 5.9) of anteversion. Of more interest is the fact that for the orthopaedic surgeons the mean inaccuracy of estimation was 4.1° (SD 3.9) for abduction and 5.2° (SD 4.5) for anteversion and for their residents this was respectively, 6.3° (SD 4.6) and 5.7° (SD 5.0). SigniWcant diVerences were found between orthopaedic surgeons and residents for inaccuracy of estimation for abduction, not for anteversion. Body mass index, sex, (un)cemented Wxation and surgical approach (anterolateral or posterolateral) were not signiWcant factors. Based upon the inaccuracy of estimation, the group's chance on future cup placement within Lewinnek's safe zone (5-25° anteversion and 30-50° abduction) is 82.7 and 85.2% for anteversion and abduction separately. When both parameters are combined, the chance of accurate placement is only 70.5%. The chance of placement of the acetabular component within 5° of an intended position, for both abduction and anteversion is 21.5% this percentage decreases to just 2.9% when the tolerated error is 1°. There is a tendency to underestimate both abduction and anteversion. Orthopaedic surgeons are superior to their residents in estimating abduction of the acetabular component. The results of this study indicate that freehand placement of the acetabular component is not a reliable method.

Research paper thumbnail of In vivo wear reduction of argon compared to air sterilized UHMW-polyethylene liners

Archives of Orthopaedic and Trauma Surgery, 2009

To date, no studies have been published that report on the in vivo advantages of sterilisation in... more To date, no studies have been published that report on the in vivo advantages of sterilisation in argon (ARGON) versus air (AIR) of UHMWPE liners with respect to wear extend and pattern in uncemented total hip arthroplasty. Femoral penetration rates were measured in 93 AIR and 79 ARGON liners, during a mean follow-up of 8 (3-12) years. During the first 3 years after implantation, both groups showed no differences in mean wear rate (P = 0.13). Thereafter, the ARGON liner demonstrated a decrease in wear rate of 0.04 mm/year from 4 to 6 years (P = 0.006), 0.14 mm/year from 7 to 9 years (P < 0.001), and 0.33 mm/year beyond 9 years follow-up (P = 0.015) compared to the AIR liner. One AIR acetabular component required revision.

Research paper thumbnail of Incidence of low-grade infection in aseptic loosening of total hip arthroplasty

Acta Orthopaedica, 2010

Purpose We investigated the hypothesis that many total hip arthroplasty revisions that are classi... more Purpose We investigated the hypothesis that many total hip arthroplasty revisions that are classified as aseptic are in fact lowgrade infections missed with routine diagnostics. Methods In 7 Dutch hospitals, 176 consecutive patients with the preoperative diagnosis of aseptic loosening of their total hip arthroplasty were enrolled. During surgery, between 14 and 20 tissue samples were obtained for culture, pathology, and broadrange 16S rRNA PCR with reverse line blot hybridization. Patients were classified as either not being infected, suspected of having infection, or infected according to strict, predefined criteria. Each patient had a follow-up visit after 1 year.

Research paper thumbnail of Toxic serum gentamicin levels after the use of gentamicin-loaded sponges in infected total hip arthroplasty

Acta Orthopaedica, 2005

At our clinic, total hip arthroplasties with an acute postoperative infection are treated with su... more At our clinic, total hip arthroplasties with an acute postoperative infection are treated with surgical debridement and application of several gentamicin-loaded sponges, each with an equivalent of 130 mg gentamicin. We studied the possible systemic effect of this local application of gentamicin. All 12 patients treated during 1997-2001 were included. 4-6 sponges were used in each case. We measured the serum gentamicin levels daily, from the first postoperative day until gentamicin was no longer measurable. The creatinine levels were monitored daily and the creatinine clearance was calculated according the Cockcroft-Gault formula. In 7 of the 12 patients, we found toxic serum levels of gentamicin (range 2-13 mg/L). In 3 cases there was a significant drop in renal clearance, which persisted. In 3 other cases there was a temporary decrease in renal clearance. We found toxic serum levels after local administration of gentamicin. We even found a persistent decrease in renal clearance in some patients. Because of the alarming results, we have reduced the number of sponges used for this purpose.

Research paper thumbnail of In vivo pharmacokinetics of a gentamicin-loaded collagen sponge in acute periprosthetic infection: Serum values in 19 patients

Acta Orthopaedica, 2008

Pearson rho correlation analysis and descriptives were performed using SPSS software, version 15.... more Pearson rho correlation analysis and descriptives were performed using SPSS software, version 15.0. Acta Orthop Downloaded from informahealthcare.com by 41.129.130.150 on 05/20/14 For personal use only.

Research paper thumbnail of Polyethylene delamination in the PCA total knee Material analysis in two failed cases

Acta Orthopaedica, 1992

Two patients had severe polyethylene-wear synovitis after total knee arthroplasty for arthrosis. ... more Two patients had severe polyethylene-wear synovitis after total knee arthroplasty for arthrosis. Full-leg length weight-bearing radiographs were diagnostic. The polyethylene of the tibial components showed excessive delamination. The morphology and crystallinity of the polyethylene showed that surface treatment of the material could well be held responsible for the massive wear.

Research paper thumbnail of Missed low-grade infection in suspected aseptic loosening has no consequences for the survival of total hip arthroplasty

Acta orthopaedica, Jan 12, 2015

Background and purpose - Aseptic loosening and infection are 2 of the most common causes of revis... more Background and purpose - Aseptic loosening and infection are 2 of the most common causes of revision of hip implants. Antibiotic prophylaxis reduces not only the rate of revision due to infection but also the rate of revision due to aseptic loosening. This suggests under-diagnosis of infections in patients with presumed aseptic loosening and indicates that current diagnostic tools are suboptimal. In a previous multicenter study on 176 patients undergoing revision of a total hip arthroplasty due to presumed aseptic loosening, optimized diagnostics revealed that 4-13% of the patients had a low-grade infection. These infections were not treated as such, and in the current follow-up study the effect on mid- to long-term implant survival was investigated. Patients and methods - Patients were sent a 2-part questionnaire. Part A requested information about possible re-revisions of their total hip arthroplasty. Part B consisted of 3 patient-related outcome measure questionnaires (EQ5D, Oxfo...

Research paper thumbnail of In vivo wear reduction of argon compared to air sterilized UHMW-polyethylene liners

Archives of Orthopaedic and Trauma Surgery, 2009

To date, no studies have been published that report on the in vivo advantages of sterilisation in... more To date, no studies have been published that report on the in vivo advantages of sterilisation in argon (ARGON) versus air (AIR) of UHMWPE liners with respect to wear extend and pattern in uncemented total hip arthroplasty. Femoral penetration rates were measured in 93 AIR and 79 ARGON liners, during a mean follow-up of 8 (3-12) years. During the first 3 years after implantation, both groups showed no differences in mean wear rate (P = 0.13). Thereafter, the ARGON liner demonstrated a decrease in wear rate of 0.04 mm/year from 4 to 6 years (P = 0.006), 0.14 mm/year from 7 to 9 years (P < 0.001), and 0.33 mm/year beyond 9 years follow-up (P = 0.015) compared to the AIR liner. One AIR acetabular component required revision.

Research paper thumbnail of Synovectomy of the elbow in rheumatoid arthritis. Long-term results

The Bone & Joint Journal

We reviewed 61 elbow synovectomies in 50 patients with rheumatoid arthritis, with follow-up varyi... more We reviewed 61 elbow synovectomies in 50 patients with rheumatoid arthritis, with follow-up varying from 4 to 10 years (mean 6.5 years). The results were graded as satisfactory in 70%, with no significant difference in the results between joints which were radiologically good before operation and those which had been destroyed. Longer term results were analysed of 27 elbow synovectomies in 22 patients followed up for over six years. The results were satisfactory in 67% of the patients in both 1981 and in 1987, with no deterioration over this period.

Research paper thumbnail of Early failure of Pavlik harness treatment of developmental hip dysplasia: clinical and ultrasound predictors

Journal of pediatric orthopedics

Research paper thumbnail of Factors associated with reduced early survival in the Oxford phase III medial unicompartment knee replacement

The Knee, 2010

The aim of this study was to determine the prognostic value of preoperative patellofemoral osteoa... more The aim of this study was to determine the prognostic value of preoperative patellofemoral osteoarthritis, BMI and age for implant survival of unicompartmental knee arthroplasty (UKA) performed in patients meeting strict admission criteria. The data and radiographs of 437 unilateral Oxford phase III procedures (Biomet, Bridgend, UK) were analysed. All procedures were carried out or supervised by 13 specialised knee surgeons in three different hospitals. The study group comprised 437 patients with a median follow of 2.6 years (0.1-7.9). The cumulative standard case survival rate at 5 years, when there were still 101 patients at risk, was 84.7% (CI-95%: 80.1-89.3%). Young age (b 60 years) was associated with a 2.2-fold increased adjusted risk of revision (CI: 1.08-4.43; p = 0.03). The preoperative presence of radiological features of patellofemoral osteoarthritis was associated with a 0.3-fold reduced adjusted risk of revision (CI: 0.11-0.89; p = 0.03). BMI N 30 kg/m 2 , gender, the surgeon performing the operation (either as an individual or categorised by annual surgical UKA caseload, i.e., more or less than 10 UKAs) and the hospital in which surgery took place did not predict implant survival of UKA. We conclude that young patients (b 60 years) experience an increased early risk of revision for UKA when compared to older patients (N 60 years). Obesity (BMI N 30 kg/m 2 ) and preoperative patellofemoral osteoarthritis are not associated with a decreased implant survival and therefore should not be considered risk factors in this context.

Research paper thumbnail of Treatment of developmental dysplasia of the hip with Pavlik harness: prospective study in Graf type IIc or more severe hips

Journal of Pediatric Orthopaedics B, 2004

Research paper thumbnail of Results of Pavlik Harness Treatment for Neonatal Hip Dislocation as Related to Graf's Sonographic Classification

Journal of Pediatric Orthopaedics, 2000

In this prospective study, 41 dislocated hips in 40 patients were classified according to Graf&am... more In this prospective study, 41 dislocated hips in 40 patients were classified according to Graf's sonographic classification. Of them, 29 hips were Graf type III and 12 hips Graf type IV. All were treated in a Pavlik harness to relocate the dislocated hip dynamically. In type III hips, this was successful in 97% and 50% in type IV hips. We conclude that Graf's classification in dislocated hips has prognostic significance in treatment with the Pavlik harness.

Research paper thumbnail of Mid-term wear characteristics of an uncemented acetabular component

Journal of Bone and Joint Surgery - British Volume, 2005

We investigated the rate of polyethylene wear of a cementless acetabular component at different p... more We investigated the rate of polyethylene wear of a cementless acetabular component at different periods of follow-up in order to test the hypothesis than an irrecoverable deformation process (creep) was followed by an initially low, but gradually increasing wear rate. We studied prospectively 93 uncemented total hip arthroplasties in 83 patients (mean age 50 years (22 to 63)) with a mean follow-up of 8.2 years (3 to 12). We measured the penetration of the femoral head from radiographs taken immediately after surgery at three, six and nine years, or at the latest follow-up. The median wear rate was 0.17 mm per year in the first three years, a finding which we considered to be caused by creep. Thereafter, the rate of wear declined to 0.07 mm per year (four- to six-year period) and then increased to 0.17 mm per year (seven to nine years) and 0.27 mm per year (more than nine years), which we considered to be a reflection of genuine polyethylene wear. After the nine-year follow-up the wear rates were higher in patients with marked osteolysis. We found no relationship between the inclination angle of the acetabular component or femoral head orientation and the rate of wear. No acetabular component required revision.

Research paper thumbnail of Total Ankle Replacement Outcome in Low Volume Centers: Short-Term Followup

Foot & Ankle International, 2010

The indication for total ankle replacement (TAR) as an alternative to ankle fusion continues to b... more The indication for total ankle replacement (TAR) as an alternative to ankle fusion continues to be a much-debated topic. The reported survival of TAR at midterm followup is approximately 90%. The aim of this study was to compare functional outcome and survival of TAR in low volume centers versus high volume centers. A retrospective cohort study was carried out in four low volume centers. Sixty-four Salto TARs were performed between 2003 and 2007 in 60 patients. Fifty-five (59 TAR) patients were eligible for followup with 28 men. Standardized American Orthopaedic Foot and Ankle Society (AOFAS) scores, patient satisfaction, and range of motion (ROM) were measured. Standardized and dynamic radiographs were used for evaluation of radiolucencies, ROM and component alignment. Seven of the 59 ankle prostheses had to be revised: five for loosening and two for deep infection. Three of the five revised for loosening went on to fusion, and in two a revision of one of the components was performed. Both infected ankles were fused. Five patients declined to participate this study, among these two were TAR failures. Survival with revision as the endpoint was 86% at final followup. The average AOFAS score was 75 (SD ± 15). On dynamic radiographs the ROM was 22 degrees (SD ± 8) in the tibiotalar joint. This study demonstrated that functional results of total ankle replacement in low volume centers were comparable to most high volume centers but survival was lower especially when we consider our shorter followup than most comparable series.

Research paper thumbnail of Poor accuracy of freehand cup positioning during total hip arthroplasty

Archives of Orthopaedic and Trauma Surgery, 2007

Several studies have demonstrated a correlation between the acetabular cup position and the risk ... more Several studies have demonstrated a correlation between the acetabular cup position and the risk of dislocation, wear and range of motion after total hip arthroplasty. The present study was designed to evaluate the accuracy of the surgeon's estimated position of the cup after freehand placement in total hip replacement. Peroperative estimated abduction and anteversion of 200 acetabular components (placed by three orthopaedic surgeons and nine residents) were compared with measured outcomes (according to Pradhan) on postoperative radiographs. Cups were placed in 49.7° (SD 6.7) of abduction and 16.0° (SD 8.1) of anteversion. Estimation of placement was 46.3° (SD 4.3) of abduction and 14.6° (SD 5.9) of anteversion. Of more interest is the fact that for the orthopaedic surgeons the mean inaccuracy of estimation was 4.1° (SD 3.9) for abduction and 5.2° (SD 4.5) for anteversion and for their residents this was respectively, 6.3° (SD 4.6) and 5.7° (SD 5.0). SigniWcant diVerences were found between orthopaedic surgeons and residents for inaccuracy of estimation for abduction, not for anteversion. Body mass index, sex, (un)cemented Wxation and surgical approach (anterolateral or posterolateral) were not signiWcant factors. Based upon the inaccuracy of estimation, the group's chance on future cup placement within Lewinnek's safe zone (5-25° anteversion and 30-50° abduction) is 82.7 and 85.2% for anteversion and abduction separately. When both parameters are combined, the chance of accurate placement is only 70.5%. The chance of placement of the acetabular component within 5° of an intended position, for both abduction and anteversion is 21.5% this percentage decreases to just 2.9% when the tolerated error is 1°. There is a tendency to underestimate both abduction and anteversion. Orthopaedic surgeons are superior to their residents in estimating abduction of the acetabular component. The results of this study indicate that freehand placement of the acetabular component is not a reliable method.

Research paper thumbnail of In vivo wear reduction of argon compared to air sterilized UHMW-polyethylene liners

Archives of Orthopaedic and Trauma Surgery, 2009

To date, no studies have been published that report on the in vivo advantages of sterilisation in... more To date, no studies have been published that report on the in vivo advantages of sterilisation in argon (ARGON) versus air (AIR) of UHMWPE liners with respect to wear extend and pattern in uncemented total hip arthroplasty. Femoral penetration rates were measured in 93 AIR and 79 ARGON liners, during a mean follow-up of 8 (3-12) years. During the first 3 years after implantation, both groups showed no differences in mean wear rate (P = 0.13). Thereafter, the ARGON liner demonstrated a decrease in wear rate of 0.04 mm/year from 4 to 6 years (P = 0.006), 0.14 mm/year from 7 to 9 years (P < 0.001), and 0.33 mm/year beyond 9 years follow-up (P = 0.015) compared to the AIR liner. One AIR acetabular component required revision.

Research paper thumbnail of Incidence of low-grade infection in aseptic loosening of total hip arthroplasty

Acta Orthopaedica, 2010

Purpose We investigated the hypothesis that many total hip arthroplasty revisions that are classi... more Purpose We investigated the hypothesis that many total hip arthroplasty revisions that are classified as aseptic are in fact lowgrade infections missed with routine diagnostics. Methods In 7 Dutch hospitals, 176 consecutive patients with the preoperative diagnosis of aseptic loosening of their total hip arthroplasty were enrolled. During surgery, between 14 and 20 tissue samples were obtained for culture, pathology, and broadrange 16S rRNA PCR with reverse line blot hybridization. Patients were classified as either not being infected, suspected of having infection, or infected according to strict, predefined criteria. Each patient had a follow-up visit after 1 year.

Research paper thumbnail of Toxic serum gentamicin levels after the use of gentamicin-loaded sponges in infected total hip arthroplasty

Acta Orthopaedica, 2005

At our clinic, total hip arthroplasties with an acute postoperative infection are treated with su... more At our clinic, total hip arthroplasties with an acute postoperative infection are treated with surgical debridement and application of several gentamicin-loaded sponges, each with an equivalent of 130 mg gentamicin. We studied the possible systemic effect of this local application of gentamicin. All 12 patients treated during 1997-2001 were included. 4-6 sponges were used in each case. We measured the serum gentamicin levels daily, from the first postoperative day until gentamicin was no longer measurable. The creatinine levels were monitored daily and the creatinine clearance was calculated according the Cockcroft-Gault formula. In 7 of the 12 patients, we found toxic serum levels of gentamicin (range 2-13 mg/L). In 3 cases there was a significant drop in renal clearance, which persisted. In 3 other cases there was a temporary decrease in renal clearance. We found toxic serum levels after local administration of gentamicin. We even found a persistent decrease in renal clearance in some patients. Because of the alarming results, we have reduced the number of sponges used for this purpose.

Research paper thumbnail of In vivo pharmacokinetics of a gentamicin-loaded collagen sponge in acute periprosthetic infection: Serum values in 19 patients

Acta Orthopaedica, 2008

Pearson rho correlation analysis and descriptives were performed using SPSS software, version 15.... more Pearson rho correlation analysis and descriptives were performed using SPSS software, version 15.0. Acta Orthop Downloaded from informahealthcare.com by 41.129.130.150 on 05/20/14 For personal use only.

Research paper thumbnail of Polyethylene delamination in the PCA total knee Material analysis in two failed cases

Acta Orthopaedica, 1992

Two patients had severe polyethylene-wear synovitis after total knee arthroplasty for arthrosis. ... more Two patients had severe polyethylene-wear synovitis after total knee arthroplasty for arthrosis. Full-leg length weight-bearing radiographs were diagnostic. The polyethylene of the tibial components showed excessive delamination. The morphology and crystallinity of the polyethylene showed that surface treatment of the material could well be held responsible for the massive wear.

Research paper thumbnail of Missed low-grade infection in suspected aseptic loosening has no consequences for the survival of total hip arthroplasty

Acta orthopaedica, Jan 12, 2015

Background and purpose - Aseptic loosening and infection are 2 of the most common causes of revis... more Background and purpose - Aseptic loosening and infection are 2 of the most common causes of revision of hip implants. Antibiotic prophylaxis reduces not only the rate of revision due to infection but also the rate of revision due to aseptic loosening. This suggests under-diagnosis of infections in patients with presumed aseptic loosening and indicates that current diagnostic tools are suboptimal. In a previous multicenter study on 176 patients undergoing revision of a total hip arthroplasty due to presumed aseptic loosening, optimized diagnostics revealed that 4-13% of the patients had a low-grade infection. These infections were not treated as such, and in the current follow-up study the effect on mid- to long-term implant survival was investigated. Patients and methods - Patients were sent a 2-part questionnaire. Part A requested information about possible re-revisions of their total hip arthroplasty. Part B consisted of 3 patient-related outcome measure questionnaires (EQ5D, Oxfo...