Influence of marker-selection method in radiostereometric analysis of total knee arthroplasty on tibial baseplate migration patterns: a secondary analysis of a randomized controlled trial with 5-year follow-up

BACKGROUND AND PURPOSE

 Different marker-selection methods are applied to represent implant and tibial segments in radiostereometric analysis (RSA) studies of total knee arthroplasty (TKA). Either a consistent set of markers throughout subsequent RSA examinations ("consistent-marker method") is used or all available markers at each follow-up ("all-marker method"). The aim of this secondary analysis was to compare marker-selection methods on individual and group level TKA migration results.

METHODS

 Data from a randomized RSA study with 72 patients was included. Tibial baseplate migration was evaluated at 3 months, 1, 2, and 5 years postoperatively with both marker-selection methods. Additionally, migration was calculated using 5 fictive points, either plotted based on the consistent set of markers or all available markers.

RESULTS

 Migration could be calculated with both marker-selection methods for 248 examinations. The same prosthesis and bone markers (n = 136), different prosthesis markers (n = 71), different bone markers (n = 21), or different prosthesis and bone markers (n = 20) were used. The mean difference in maximum total point motion (MTPM) between all examinations was 0.02 mm, 95% confidence interval -0.26 to 0.31 mm. 5 implants were classified as continuously migrating with the consistent-marker method versus 6 implants (same 5 plus one additional implant) with the all-marker method. Using fictive points, fewer implants were classified as continuously migrating in both marker-selection methods. Differences between TKA groups in mean MTPM were comparable with both marker-selection methods, also when fictive points were used.

CONCLUSION

 Estimated group differences in mean MTPM were similar between marker-selection methods, but individual migration results differed. The latter has implications when classifying implants for estimated risk of future loosening.

Migration and clinical outcomes of a novel cementless hydroxyapatite-coated titanium acetabular shell: two-year follow-up of a randomized controlled trial using radiostereometric analysis

Aims

The objective of this study was to compare the two-year migration and clinical outcomes of a new cementless hydroxyapatite (HA)-coated titanium acetabular shell with its previous version, which shared the same geometrical design but a different manufacturing process for applying the titanium surface.

Methods

Overall, 87 patients undergoing total hip arthroplasty (THA) were randomized to either a Trident II HA or Trident HA shell, each cementless with clusterholes and HA-coating. All components were used in combination with a cemented Exeter V40 femoral stem. Implant migration was measured using radiostereometric analysis (RSA), with radiographs taken within two days of surgery (baseline), and at three, 12, and 24 months postoperatively. Proximal acetabular component migration was the primary outcome measure. Clinical scores and patient-reported outcome measures (PROMs) were collected at each follow-up.

Results

Mean proximal migrations at three, 12, and 24 months were 0.08 mm (95% confidence interval (CI) 0.03 to 0.14), 0.11 mm (95% CI 0.06 to 0.16), and 0.14 mm (95% CI 0.09 to 0.20), respectively, in the Trident II HA group, versus 0.11 mm (95% CI 0.06 to 0.16), 0.12 mm (95% CI 0.07 to 0.17), and 0.14 mm (95% CI 0.09 to 0.19) in the Trident HA group (p = 0.875). No significant differences in translations or rotations between the two designs were found in any other direction. Clinical scores and PROMs were comparable between groups, except for an initially greater postoperative improvement in Hip disability and Osteoarthritis Outcome Symptoms score in the Trident HA group (p = 0.033).

Conclusion

The Trident II clusterhole HA shell has comparable migration with its predecessor, the Trident hemispherical HA cluster shell, suggesting a similar risk of long-term aseptic loosening.

Continued Stabilization of a Cementless 3D-Printed Total Knee Arthroplasty: Five-Year Results of a Randomized Controlled Trial Using Radiostereometric Analysis

BACKGROUND

Three-dimensional (3D) printing of highly porous orthopaedic implants aims to promote better osseointegration, thus preventing aseptic loosening. However, short-term radiostereometric analysis (RSA) after total knee arthroplasty (TKA) has shown higher initial migration of cementless 3D-printed tibial components compared with their cemented counterparts. Therefore, critical evaluation of longer-term tibial component migration is needed. We investigated migration of a cementless 3D-printed and a cemented tibial component with otherwise similar TKA design during 5 years of follow-up, particularly the progression in migration beyond 2 years postoperatively.

METHODS

Seventy-two patients were randomized to a cementless 3D-printed Triathlon Tritanium (Stryker) cruciate-retaining (CR) TKA or a cemented Triathlon CR (Stryker) TKA implant. Implant migration was evaluated with RSA at baseline and postoperatively at 3 months and at 1, 2, and 5 years. The maximum total point motion (MTPM) of the tibial component was compared between the groups at 5 years, and progression in migration was assessed between 2 and 5 years. Individual implants were classified as continuously migrating if the MTPM was ≥0.1 mm/year beyond 2 years postoperatively. Clinical scores were evaluated, and a linear mixed-effects model was used to analyze repeated measurements.

RESULTS

At 5 years, the mean MTPM was 0.66 mm (95% confidence interval [CI], 0.56 to 0.78 mm) for the cementless group and 0.53 mm (95% CI, 0.43 to 0.64 mm) for the cemented group (p = 0.09). Between 2 and 5 years, there was no progression in mean MTPM for the cementless group (0.02 mm; 95% CI, -0.06 to 0.10 mm) versus 0.07 mm (95% CI, 0.00 to 0.14) for the cemented group. One implant was continuously migrating in the cementless group, and 4 were continuously migrating in the cemented group. The clinical scores were comparable between the groups across the entire time of follow-up.

CONCLUSIONS

No significant difference in mean migration was found at 5 years between the cementless and cemented TKA implants. Progression of tibial component migration was present beyond 2 years for the cemented implant, whereas the cementless implant remained stable after initial early migration.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

The Influence of Postoperative Coronal Alignment on Tibial Migration After Total Knee Arthroplasty in Preoperative Varus and Valgus Knees: A Secondary Analysis of 10 Randomized Controlled Trials Using Radiostereometric Analysis

BACKGROUND

Orthopaedic surgeons aim for mechanical alignment when performing total knee arthroplasty (TKA) as malalignment is associated with loosening. Loosening may be predicted by migration as measured with radiostereometric analysis (RSA), but previous RSA studies on postoperative alignment have shown contradictory results and have been limited to cemented implants and small numbers of patients. Therefore, we performed a secondary analysis of 10 previously published randomized controlled trials (RCTs) to compare migration between postoperative in-range and out-of-range cemented and uncemented TKA implants among patients with a preoperative varus or valgus knee.

METHODS

All RCTs involving the use of RSA that had been conducted at 2 centers were included. Alignment was classified, with use of the hip-knee-ankle angle (HKA), as in-range (0° ± 3°) or out-of-range (<-3° or >3°). The fixation methods included cemented, uncemented-coated, and uncemented-uncoated. Migration was measured at 3, 12, and 24 months. A linear mixed model was used, with adjustment for fixation method and clustering of patients within centers.

RESULTS

Of 476 TKA implants that had been out-of-range preoperatively, 290 were in-range postoperatively and 186 were out-of-range in either varus (n = 143) or valgus (n = 43) postoperatively. The mean migration at 3, 12, and 24 months was 0.73 mm (95% confidence interval [CI], 0.66 to 0.79 mm), 0.92 mm (95% CI, 0.85 to 1.00 mm), and 0.97 mm (95% CI, 0.90 to 1.05 mm), respectively, for the in-range group and 0.80 mm (95% CI, 0.72 to 0.87 mm), 0.98 (95% CI, 0.90 to 1.07 mm), and 1.04 mm (95% CI, 0.95 to 1.13 mm), respectively, for the out-of-range group (p = 0.07). The fixation method significantly influenced migration, with uncemented-uncoated implants migrating more than cemented and uncemented-coated implants (p < 0.001).

CONCLUSIONS

Postoperative alignment did not influence migration of TKAs in the first 2 postoperative years in patients with preoperative varus or valgus alignment of the knee. However, the fixation method significantly influenced migration, with uncemented-uncoated implants showing the greatest migration.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Risk Factors for Tibial Component Loosening: A Meta-Analysis of Long-Term Follow-up Radiostereometric Analysis Data

BACKGROUND

Radiostereometric analysis (RSA) is a highly accurate tool to detect implant migration and predict loosening following total knee arthroplasty (TKA). However, little is known about the predisposing risk factors for implant migration, nor which migration profile should be considered physiological (i.e., merely part of an implant-settling phase) and which should be considered pathological (i.e., having a high probability for implant loosening). By pooling individual participant data from long-term follow-up RSA studies, we aimed to identify predisposing risk factors for tibial component loosening.

METHODS

Individual data were collected for 630 patients from 11 RSA studies. The repeated measurements were analyzed with use of a linear mixed-effects model, determining the effect of age, sex, body mass index, diagnosis, preoperative and postoperative limb alignment, and prosthesis characteristics on tibial component migration over time, taking into account the clustering of patients within studies.

RESULTS

High initial migration was found to result in early mechanical loosening in 18 cases (2.9%) and septic loosening in 2 cases (0.3%), whereas stabilization of high initial migration occurred in 17 cases (2.7%). Late loosening occurred in 13 cases (2.1%). All other 580 cases (92.1%) showed early stabilization and remained stable over time. Mixed-effects model analyses showed that for cemented prostheses, sex, diagnosis, and posterior cruciate ligament type had an effect on migration, but these differences were nonsignificant when analyzing migration from 3 months onwards. Uncemented prostheses aligned in varus showed more migration than neutrally and valgus-aligned TKAs (p = 0.031), and this difference increased over time (p < 0.001). Significantly higher migration was observed following uncemented TKA without an osseointegration-promoting surface (p < 0.001).

CONCLUSIONS

For cemented prostheses, increased migration during the first 3 postoperative months was observed for female patients, patients with rheumatoid arthritis, and patients who underwent a posterior-stabilized TKA. For uncemented prostheses, both postoperative varus alignment of the lower limb and the absence of an osseointegration-promoting surface significantly increased postoperative tibial component migration.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Migration of a novel 3D-printed cementless versus a cemented total knee arthroplasty: two-year results of a randomized controlled trial using radiostereometric analysis

Aims

Although bone cement is the primary mode of fixation in total knee arthroplasty (TKA), cementless fixation is gaining interest as it has the potential of achieving lasting biological fixation. By 3D printing an implant, highly porous structures can be manufactured, promoting osseointegration into the implant to prevent aseptic loosening. This study compares the migration of cementless, 3D-printed TKA to cemented TKA of a similar design up to two years of follow-up using radiostereometric analysis (RSA) known for its ability to predict aseptic loosening.

Methods

A total of 72 patients were randomized to either cementless 3D-printed or a cemented cruciate retaining TKA. RSA and clinical scores were evaluated at baseline and postoperatively at three, 12, and 24 months. A mixed model was used to analyze the repeated measurements.

Results

The mean maximum total point motion (MTPM) at three, 12, and 24 months was 0.33 mm (95% confidence interval (CI) 0.25 to 0.42), 0.42 mm (95% CI 0.33 to 0.51), and 0.47 mm (95% CI 0.38 to 0.57) respectively in the cemented group, versus 0.52 mm (95% CI 0.43 to 0.63), 0.62 mm (95% CI 0.52 to 0.73), and 0.64 mm (95% CI 0.53 to 0.75) in the cementless group (p = 0.003). However, using three months as baseline, no difference in mean migration between groups was found (p = 0.497). Three implants in the cemented group showed a > 0.2 mm increase in MTPM between one and two years of follow-up. In the cementless group, one implant was revised due to pain and progressive migration, and one patient had a liner-exchange due to a deep infection.

Conclusion

The cementless TKA migrated more than the cemented TKA in the first two-year period. This difference was mainly due to a higher initial migration of the cementless TKA in the first three postoperative months after which stabilization was observed in all but one malaligned and early revised TKA. Whether the biological fixation of the cementless implants will result in an increased long-term survivorship requires a longer follow-up. Cite this article: Bone Joint J 2020;102-B(8):1016–1024.

All-polyethylene versus metal-backed posterior stabilized total knee arthroplasty: similar 2-year results of a randomized radiostereometric analysis study

Background and purpose - The all-polyethylene tibial (APT) component, introduced in the early 1970s, was surpassed by metal-backed tibial (MBT) trays as the first choice for total knee arthroplasty (TKA). With improved polyethylene, the modern APT components can reduce costs, and have shown equivalent results in survivorship and early migration of the cruciate-retaining and cruciate-stabilizing designs. This study compares the 2-year migration of a similarly designed APT-posterior stabilized (PS) and a MBT-PS TKA, using radiostereometric analysis (RSA).Patients and methods - 60 patients were randomized to receive either an APT Triathlon PS or an MBT Triathlon PS TKA (Stryker, NJ, USA). Migration measured by RSA and clinical scores were evaluated at baseline and at 3, 12, and 24 months postoperatively. Repeated measurements were analyzed with a linear mixed model and generalized estimating equations.Results - The mean maximum total point movement (MTPM) at 3, 12, and 24 months was 0.41 mm (95% CI 0.33-0.50), 0.57 mm (0.44-0.70), and 0.56 mm (0.42-0.69) respectively in the MBT group and 0.46 mm (0.36-0.57), 0.61 mm (0.49-0.73), and 0.64 mm (0.50-0.77) in the APT group. 2 MBT and 1 APT implant were considered unstable at the 2-year follow-up. The KSS Knee score and KSS Function across 3, 12, and 24 months were comparable in both groups.Interpretation - For an APT-PS designed component, MTPM measured with RSA is comparable to the MBT-PS component after 2 years of follow-up. No differences in complications or clinical outcomes were found.

Marker-based versus model-based radiostereometric analysis of total knee arthroplasty migration: a reanalysis with comparable mean outcomes despite distinct types of measurement error

Background and purpose - Pooling data of studies evaluating total knee arthroplasty migration using radiostereometric analysis (RSA) may be compromised when the RSA method used would influence estimated differences between groups. We therefore reanalyzed a marker-based RSA study with model-based RSA to assess possible limitations of each RSA method, including insert micromotions in modular TKA and their effect on estimated group differences. Patients and methods - All patients had received a cemented Triathlon implant (Stryker, Mahwah, NJ, USA) with either an all-polyethylene (n = 29) or a metal-backed (n = 28) tibial component. The latter group was reanalyzed with model-based RSA. Precision of each RSA method was calculated using double examinations. Bland-Altman plots were constructed to determine the limits of agreement between the 2 RSA methods. Polyethylene insert micromotion was quantified by measuring migration with respect to the metal tray. Finally, analyses of the original study were repeated with the model-based RSA results. Results - Systematic differences were found in translations between marker-based and model-based RSA as a result of different reference origins being used for migration calculations. Micromotions of the polyethylene insert within the metal tray were negligibly small. Mean migration results were comparable between marker-based and model-based RSA when using the same reference origin, even though conclusions on individual patients may differ between RSA methods due to various types of measurement error (e.g., marker occlusion and model-fit inaccuracies). Interpretation - At least for the studied TKA design, pooling mean migration data of different RSA methods appears justified. For translations, however, adjustments should be made to correct for differences in reference origin. Migration patterns of individual patients may differ as a result of distinct types of measurement error.

The clinical effect of an unloader brace on patients with osteoarthritis of the knee, a randomized placebo controlled trial with one year follow up

Background

Treatment of patients with knee osteoarthritis is challenging. Unloader braces have been developed with various success. Unloader One® Knee Brace is light, easily-fitted and shown to be effective by the unloading of the affected compartment. The aim of the study was to assess the clinical outcome of the brace vs. a placebo on patients with knee osteoarthritis.

Methods

Initially 150 patients were randomized to receive either the Unloader brace or a control placebo group look-alike brace where the active strips had been removed. The patients were followed up at 6,12,26 and 52 weeks with Knee Society Score (KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS). The reason for dropout was recorded.

Results

A total of 149 patients were included, 74 in the study and 75 in the control group. The mean age was 59.6 vs. 60.2, BMI was 27.5 vs. 26.9, 37% vs. 44% were women in the study vs. control group. Both groups showed improvement in KSS over 52 weeks, with the study group showing higher improvement in mean scores. KSS increased from 64.3 to 84.0 for the study group and from 64.0 to 74.6 for the control group (p = 0.009). The study group improved in KSS function from 67.0 to 78.6 (p < 0.001) and KOOS for knee related symptoms increased/improved from 64.3 to 72.4 (p < 0.001). Activity of daily living increased/improved from 65.3 to 75.2 and Sports/Recreation from 24.6 to 40.2 (p > 0.001) whereas the control group did not show significant improvements in any of the scores. The dropout was higher in the control group, 40 vs. 25.

Conclusions

The brace seems to be more effective and better tolerated than the placebo.

Trial registration

The trial was retrospectively registered with ClinicalTrials.gov (NCT03454776) on March 6th 2018.

Peri-apatite coating decreases uncemented tibial component migration: long-term RSA results of a randomized controlled trial and limitations of short-term results

Background and purpose - Biological fixation of uncemented knee prostheses can be improved by applying hydroxyapatite coating around the porous surface via a solution deposition technique called Peri-Apatite (PA). The 2-year results of a randomized controlled trial, evaluating the effect of PA, revealed several components with continuous migration in the second postoperative year, particularly in the uncoated group. To evaluate whether absence of early stabilization is diagnostic of loosening, we now present long-term follow-up results. Patients and methods - 60 patients were randomized to PA-coated or uncoated (porous only) total knee arthroplasty of which 58 were evaluated with radiostereometric analysis (RSA) performed at baseline, at 3 months postoperatively and at 1, 2, 5, 7, and 10 years. A linear mixed-effects model was used to analyze the repeated measurements. Results - PA-coated components had a statistically significantly lower mean migration at 10 years of 0.94 mm (95% CI 0.72-1.2) compared with the uncoated group showing a mean migration of 1.72 mm (95% CI 1.4-2.1). Continuous migration in the second postoperative year was seen in 7 uncoated components and in 1 PA-coated component. All of these implants stabilized after 2 years except for 2 uncoated components. Interpretation - Peri-apatite enhances stabilization of uncemented components. The number of components that stabilized after 2 years emphasizes the importance of longer follow-up to determine full stabilization and risk of loosening in uncemented components with biphasic migration profiles.

Migration of all-polyethylene compared with metal-backed tibial components in cemented total knee arthroplasty

Background and purpose - With a rapidly increasing population in need of total knee arthroplasty (TKA), there is renewed interest in cost-saving all-polyethylene designs. Differences between metal-backed and all-polyethylene designs in initial component migration assessed by radiostereometric analysis (RSA), a proven predictor for late aseptic loosening, have been scantily reported. The purpose of this study was to compare implant migration and clinical outcomes of all-polyethylene tibial components versus metal-backed trays of similar geometrical shape. Patients and methods - In this randomized controlled trial, 59 patients received a cemented Triathlon condylar-stabilizing implant (Stryker, Mahwah, NJ, USA) with either an all-polyethylene (n = 29) or a metal-backed tibial component (n = 30). RSA measurements and clinical scores (the Knee Society Score, Forgotten Joint Score, and Knee Osteoarthritis and Injury Outcome Score) were evaluated at baseline and postoperatively at 3, 12, and 24 months. A linear mixed-effects model was used to analyze the repeated measurements. Results - A statistically significant difference in mean migration after 2 years was found in favor of the all-polyethylene group, with a mean maximum total point motion of 0.61 mm (95% CI 0.49-0.74) versus 0.81 mm (95% CI 0.68-0.96) for the cemented group (p = 0.03). However, this difference was smaller and not statistically significant after post hoc adjustment for surgeon effect. Both groups showed comparable improvements on all clinical outcome scores over time. Interpretation - The Triathlon all-polyethylene tibial component showed less migration, suggesting a lower risk of late loosening as compared with its metal-backed counterpart. However, the found surgeon effect warrants further investigation.

Fixation and clinical outcome of uncemented peri-apatite-coated versus cemented total knee arthroplasty

Aims

The optimal method of tibial component fixation remains uncertain in total knee arthroplasty (TKA). Hydroxyapatite coatings have been applied to improve bone ingrowth in uncemented designs, but may only coat the directly accessible surface. As peri-apatite (PA) is solution deposited, this may increase the coverage of the implant surface and thereby fixation. We assessed the tibial component fixation of uncemented PA-coated TKAs versus cemented TKAs.

Patients and Methods

Patients were randomised to PA-coated or cemented TKAs. In 60 patients (30 in each group), radiostereometric analysis of tibial component migration was evaluated as the primary outcome at baseline, three months post-operatively and at one, two and five years. A linear mixed-effects model was used to analyse the repeated measurements.

Results

After five years of follow-up, one (cemented) component was revised due to ligament instability. Overall, uncemented PA-coated tibial components migrated significantly more (p = 0.003), with the mean maximum total point motion (MTPM) at five years being 0.62 mm (95% confidence intervals (CI) 0.49 to 0.76) for cemented tibial components and 0.97 mm (95% CI 0.81 to 1.15) for PA-coated tibial components in TKA. However, between three months and five years the cemented TKAs migrated significantly more (p = 0.02), displaying a MTPM of 0.27 mm (95% CI, 0.19 to 0.36) versus 0.13 mm (95% CI, 0.01 to 0.25) for PA-coated tibial components. One implant in each group was considered at risk for aseptic loosening due to continuous migration after five years of follow-up, albeit with different migration patterns for each group (i.e. higher initial migration but diminishing over time for the PA-coated component versus gradually increasing migration for the cemented component).

Conclusion

The tibial components of PA-coated TKAs showed more overall migration compared with the tibial components of cemented TKAs. However, post hoc analysis showed that this difference was caused by higher migration of PA-coated components in the first three months, after which a stable migration pattern was observed. Clinically, there was no significant difference in outcome between the groups. Cite this article: Bone Joint J 2017;99-B:1467–76.

A randomized RSA study concentrating especially on continuous migration

Background and purpose - There is a general call for phased introduction of new implants, and one step in the introduction is an early evaluation of micromotion. We compared the micromotion in the Triathlon and its predecessor, the Duracon total knee prosthesis, concentrating especially on continuous migration over 5 years of follow-up. Patients and methods - 60 patients were randomized to receive either a cemented Triathlon total knee prosthesis or a cemented Duracon total knee prosthesis. 3-D tibial component migration was measured by radiostereometric analysis (RSA) at 3 months and at 1, 2, and 5 years. Results - There was no statistically significant difference in maximum total point motion (MTPM) between the 2 groups (p = 0.1). The mean MTPM at 5 years for the Duracon was 1.10 (SD 1.21) mm and for the Triathlon it was 0.66 (SD 0.38) mm. The numbers of continuously migrating prostheses were similar in the groups at the fifth year of follow-up; 6 of 21 prostheses in the Duracon group and 3 of 21 in the Triathlon group had migrated more than 0.3 mm between the second year and the fifth year of follow-up (p = 0.2). Interpretation - The Triathlon has a micromotion pattern similar to that of the Duracon total knee system at both short-term and medium-term follow-up, and may therefore, over time, show the same good long-term mechanical stability.

2-year follow-up report on micromotion of a short tibia stem. A prospective, randomized RSA study of 59 patients

BACKGROUND AND PURPOSE

A shortened tibial stem could influence the early prosthetic fixation. We therefore compared the short stem to the standard-length stem using radiostereometric analysis (RSA) as primary outcome measure.

PATIENTS AND METHODS

60 patients were randomized to receive a cemented Triathlon total knee arthroplasty (TKA) with a tibial tray of either standard or short stem length. The patients were blinded regarding treatment allocation. The micromotion of the tibial component was measured by RSA postoperatively, at 3 months, and after 1 and 2 years; clinical outcome was measured with the American Knee Society score (AKSS) and the knee osteoarthritis and injury outcome score (KOOS).

RESULTS

The maximum total point motion (MTPM) for the standard stem was 0.36 (SD 0.16) mm at 3 months, 0.51 (SD 0.27) mm at 1 year, and 0.54 (SD 0.28) mm at 2 years. For the short stem, it was 0.42 (0.24) mm, 0.59 (0.43) mm, and 0.61 (0.39) mm. 4 short-stemmed components and 2 standard-stemmed components had more than 0.2 mm of migration between the first- and second-year follow-up, and were classified as continuously migrating.

INTERPRETATION

The short-stemmed cemented tibial prosthesis showed an early prosthetic migratory pattern similar to that of the standard-stemmed cemented Triathlon knee prosthesis. The number of continuously migrating tibial plates in each group is predictive of a lower revision rate than 5% at 10 years.

Tourniquet versus no tourniquet on knee-extension strength early after fast-track total knee arthroplasty; a randomized controlled trial

BACKGROUND

Thigh tourniquet is commonly used in total knee arthroplasty (TKA) but may contribute to pain and muscle damage. Consequently, the reduction in knee-extension strength after TKA may be caused by quadriceps muscle ischaemia underneath the cuff.

AIM

To examine if not using a thigh tourniquet during surgery was more effective than using a thigh tourniquet in preserving knee-extension strength 48 h after fast-track TKA.

METHODS

A total of 64 patients undergoing TKA were randomized (1:1) to the use of tourniquet (T-group) or no tourniquet (NT-group). In the T-group the tourniquet cuff pressure was based on the patient's systolic pressure and a margin of 100 mm Hg. It was inflated immediately before surgery and deflated as soon as surgery ended. The primary outcome was the change in knee-extension strength from pre-surgery to 48 h after surgery (primary end point). Secondary outcomes were pain, nausea, length of hospital stay (LOS) and periarticular swelling.

RESULTS

Knee-extension strength 48 h after surgery was substantially reduced by about 90% in both groups, with no statistically significant difference between groups (mean difference 1.5 N/kg, 95% CI 1.3-1.6). Among the secondary outcomes, the T-group had less bleeding during surgery (56 vs. 182 mL, P<0.01) compared with the NT-group. There was no difference in postoperative haemoglobin levels, pain, nausea, LOS or periarticular swelling between the groups.

CONCLUSION

Not using a thigh tourniquet during surgery was not superior in preserving knee-extension strength at the primary endpoint 48 h after fast-track TKA, compared to using a tourniquet.

The effect of tourniquet use on fixation quality in cemented total knee arthroplasty a prospective randomized clinical controlled RSA trial

BACKGROUND

A concern that arises with any change in technique is whether it affects the long-term implant stability. The objective of this study was to evaluate the early migration, measured by radiostereometric analysis (RSA), and the functional outcome of the Triathlon™ cemented knee prosthesis, operated on with or without a tourniquet. During the last decades RSA has emerged as a way to assess prosthetic fixation and long time prognosis. The method has been used extensively in both hip and knee arthroplasty.

METHOD

This was a single centre prospective study including 60 patients randomized into two groups operated on either with or without tourniquet. RSA investigation was done within 2-3 days postoperatively after full weight bearing, and then at 3 months, 1 year and 2 years postoperatively.

RESULTS

There were no differences between the groups regarding the translation along or rotation around the three coordinal axes, or in maximum total point motion (MTPM). At 2 years the mean MTPM (SD) was 0.71 mm (0.64) for the tourniquet-group and 0.53 mm (0.21) for the non-tourniquet-group.

CONCLUSIONS

The tibial tray of the Triathlon™ cemented knee prosthesis showed similar early stability whether operated on with or without tourniquet.

LEVEL OF EVIDENCE

Level I.

ARTICLE SUMMARY

Article focus: A safety study for total knee replacement operated on with or without perioperative tourniquet regarding the prosthetic fixation. Strengths and limitations: Strength of this study is that it is a randomized prospective trial using an objective measuring tool. The sample size of 25-30 patients is reportedly sufficient for the screening of implants using RSA (1-3).

TRIAL REGISTRATION

Clinical trials NCT01604382, Ethics Committee approval D-nr: 144/20085.

Bisphosphonate-coated external fixation pins appear similar to hydroxyapatite-coated pins in the tibial metaphysis and to uncoated pins in the shaft

BACKGROUND AND PURPOSE

External fixation pins tend to loosen with time, especially from cancellous bone. A coating that releases a bisphosphonate has been shown to improve the fixation of dental implants in humans. We now tested a bisphosphonate coating on steel pins for external fixation. The primary hypothesis was that coated pins would be better fixed in the diaphysis.

METHODS

20 patients with medial knee osteoarthritis underwent proximal tibial correction osteotomy with hemicallotasis. They received a pair of pins (Orthofix) in the tibial shaft, one bisphosphonate-coated and one uncoated. Another pair of pins was inserted in the metaphysis, near the joint. This pair was a bisphosphonate-coated pin and an HA-coated pin. All pins were inserted according to a random list. The pins were removed after the osteotomy had healed (8-15 weeks), and extraction torque served as the predetermined main outcome variable.

RESULTS

No pins showed clinical signs of loosening. Removal torque for the shaft pins was 6.6 Nm (SD 2.2) for the bisphosphonate and 6.0 Nm (SD 2.5) for the uncoated (difference = 0.5, 95% CI: -0.03 to 1.3). Removal torque for the metaphyseal pins was 4.4 Nm (SD 1.3) for the bisphosphonate-coated and 4.2 Nm (SD 1.6) for the HA-coated (difference = 0.2, 95% CI: -0.5 to 1.0).

INTERPRETATION

We could not show any improved cortical fixation, but the metaphyseal findings are striking. In a previous study on 19 patients with a similar layout, HA-coated and uncoated pins were compared. In the metaphysis, all 19 uncoated pins loosened before removal. It was concluded that uncoated pins could not be used in the metaphyseal region. The present results suggest that a bisphosphonate coating enables metaphyseal fixation similar to that of hydroxyapatite coatings, with no difference from uncoated pins in cortical bone.

Does a new knee design perform as well as the design it replaces?

Objectives

The objective of this study was to compare the early migration characteristics and functional outcome of the Triathlon cemented knee prosthesis with its predecessor, the Duracon cemented knee prosthesis (both Stryker).

Methods

A total 60 patients were prospectively randomised and tibial component migration was measured by radiostereometric analysis (RSA) at three months, one year and two years; clinical outcome was measured by the American Knee Society score and the Knee Osteoarthritis and Injury Outcome Score.

Results

There were no statistically significant differences in rotation or translation around or along the three coordinal axes, or in the maximum total point motion (MTPM) during the two-year follow-up.

Conclusions

The Triathlon cemented knee prosthesis has similar early stability and is likely to perform at least as well as the Duracon cemented knee prosthesis over the longer term.

A single bisphosphonate infusion does not accelerate fracture healing in high tibial osteotomies

BACKGROUND

Bisphosphonates increase the callus size and strength in animal fracture studies. In a human non-randomized pilot study of high tibial osteotomies in knee osteoarthritis, using the hemicallotasis (HCO) technique, bisphosphonates shortened the healing time by 12 days. In the present randomized study, we wanted to determine whether a single infusion of zoledronic acid reduces the time to clinical osteotomy healing. Results from the same trial, showing improved pin fixation with zoledronate, have been published separately.

METHODS

46 consecutive patients (aged 35-65 years) were operated. At 4 weeks postoperatively, the patients were randomized to an intravenous infusion of either zoledronic acid or sodium chloride. Dual-energy X-ray absorptiometry (DEXA) was performed 10 weeks postoperatively. Radiographs were taken at 10 weeks and every second week until there was radiographic and clinical healing. Healing was evaluated blind, with extraction of the external fixator as the endpoint. At 1.5 years, an additional radiograph was taken and the hip-knee-ankle (HKA) angle measured to evaluate whether correction had been retained.

RESULTS

All osteotomies healed with no difference in healing time between the groups (77 (SD 7) days). Bone mineral density and bone mineral content, as assessed with DEXA, were similar between the groups. Radiographically, both groups had retained the acquired correction at the 1.5-year follow-up.

INTERPRETATION

In this randomized comparison, a single infusion of zoledronic acid increased the pin fixation of the external frame but did not shorten the healing time. In both groups, the external fixator was extracted almost 2 weeks earlier than in previous studies. The early extraction did not cause a loss of correction in either group.

A single dose zoledronic acid enhances pin fixation in high tibial osteotomy using the hemicallotasis technique. A double-blind placebo controlled randomized study in 46 patients

INTRODUCTION

Bisphosphonates have been shown to reduce osteoclastic activity and enhance pin fixation in both experimental and clinical studies. In this prospective, randomized study of high tibial osteotomy using the hemicallotasis (HCO) technique, we evaluate whether treatment by one single infusion of zoledronic acid can enhance the pin fixation.

MATERIALS AND METHODS

46 consecutive patients (35-65 years) were operated on for knee osteoarthritis by the HCO technique. After the osteotomy, two hydroxyapatite-coated pins were inserted in the metaphyseal bone and two non-coated pins in the diaphyseal bone. The insertion torque was measured by a torque force screw driver. Four weeks postoperatively, the patients were randomized to either one infusion of zoledronic acid or sodium chloride intravenously. At time for removal of the pins, the extraction torque forces of the pins were measured.

RESULTS

All osteotomies healed and no difference was found in time to healing. The mean extraction torque force in the non-coated pins in the diaphyseal bone was doubled in the zoledronic treated group (4.5 Nm, SD 2.1) compared to the placebo group (2.4 (SD 1.0, p<0.0001). The mean extraction torque forces of the hydroxyapatite-coated pins in the metaphyseal bone were similar in the zoledronic acid group (4.7 Nm, SD 1.3) and in the placebo group (4.0 Nm, SD 1.3).

DISCUSSION

A single infusion of zoledronic acid improved twofold the fixation of non-coated pins in diaphyseal bone. Bisphosphonates might be an alternative to hydroxyapatite-coated pins in nonosteoporotic bone.

Association between knee alignment and knee pain in patients surgically treated for medial knee osteoarthritis by high tibial osteotomy. A one year follow-up study

Background

The association between knee alignment and knee pain in knee osteoarthritis (OA) is unclear. High tibial osteotomy, a treatment option in knee OA, alters load from the affected to the unaffected compartment of the knee by correcting malalignment. This surgical procedure thus offers the possibility to study the cross-sectional and longitudinal association of alignment to pain. The aims were to study 1) the preoperative association of knee alignment to preoperative knee pain and 2) the association of change in knee alignment with surgery to change in knee pain over time in patients operated on for knee OA by high tibial osteotomy.

Methods

182 patients (68% men) mean age 53 years (34 - 69) with varus alignment having tibial osteotomy by the hemicallotasis technique for medial knee OA were consecutively included. Knee alignment was assessed by the Hip-Knee-Ankle (HKA) angle from radiographs including the hip and ankle joints. Knee pain was measured by the subscale pain (0 - 100, worst to best scale) of the Knee injury and Osteoarthritis Outcome Score (KOOS) preoperatively and at one year follow-up. To estimate the association between knee alignment and knee pain multivariate regression analyses were used.

Results

Mean preoperative varus alignment was 170 degrees (153 - 178) and mean preoperative KOOS pain was 42 points (3 - 86). There was no association between preoperative varus alignment and preoperative KOOS pain, crude analysis 0.02 points (95% CI -0.6 - 0.7) change in pain with every degree of HKA angle, adjusted analysis 0.3 points (95% CI -1.3 - 0.6).

The mean postoperative knee alignment was 184 degrees (171 - 185). The mean change in knee alignment was 13 degrees (0 - 30). The mean change in KOOS pain was 32 (-16 - 83). There was neither any association between change in knee alignment and change in KOOS pain over time, crude analysis 0.3 point (95% CI -0.6 - 1.2), adjusted analysis 0.4 points (95% CI 0.6 - 1.4).

Conclusion

We found no association between knee alignment and knee pain in patients with knee OA indicating that alignment and pain are separate entities, and that the degree of preoperative malalignment is not a predictor of knee pain after high tibial osteotomy.

A 5 year prospective study of patient-relevant outcomes after total knee replacement

OBJECTIVE

To prospectively describe self-reported outcomes up to 5 years after total knee replacement (TKR) in Osteoarthritis (OA) and to study which patient-relevant factors may predict outcomes for pain and physical function (PF).

METHODS

102 consecutive patients with knee OA, 63 women and 39 men, mean age 71 (51-86) assigned for TKR at the Department of Orthopaedics at Lund University Hospital were included in the study. The self-administered questionnaires Knee injury and Osteoarthritis Outcome Score (KOOS) and SF-36 were mailed preoperatively and 6 months, 12 months and at 5 years postoperatively.

RESULTS

Response rate at 5 years was 86%. At 6 months significant improvement was seen in all KOOS and SF-36 scores (P<0.001). The percentage of patients performing more demanding functions related to sports and recreation increased postoperatively. The best postoperative result was reported at the 1 year follow-up. Compared to the 1 year follow-up, a significant (P<or=0.01) decline was seen at 5 years in the KOOS subscale activity of daily living (ADL) function (82-73) and the SF-36 subscale bodily pain (72-63), PF (61-51) and vitality (69-59). Patients who scored in the lowest quartile preoperatively in the KOOS subscales pain and ADL made the greatest improvements to 1 year (18-82, 22-80) but also declined the most from 12 months to 5 years (82-72, 80-66). Being 10 years older pre-operatively predicted 5-7 points worse scores in KOOS pain and KOOS symptoms at 1 and 5 years. When adjusted for age, sex and comorbid conditions, pre-operative SF-36 scores did not predict postoperative KOOS pain or PF scores.

CONCLUSION

Compared to preoperatively, a significant improvement was still seen 5 years postoperatively. However, the best result was reported at 1 year, indicating a decline from 1 to 5 years after TKR. To fully evaluate the results of TKR with regard to pain and PF, follow-ups longer than 2 years are needed, and items of more demanding PFs should be included. Older age to some extent predicted more postoperative pain and other symptoms, however, no predictors of postoperative PF were found, indicating the difficulty of determining preoperatively who will benefit more or less from the procedure.

Undisturbed theatre dressing during the first postoperative week. A benefit in the treatment by external fixation: a cohort study

In the literature, there are several different suggestions as to when the first postoperative pin-site care should be carried out to best prevent pin-site infections during the treatment by external fixation. In a cohort study, we compared the use of antibiotics and complications in patients where the theatre dressing was changed during the first postoperative week with patients where the theatre dressings were left undisturbed for the first postoperative week. Sterile compresses moistened with chlorhexidine 5 mg/ml in alcohol (70%), draped around each pin site and fixed by a bandage, were used as theatre dressing. In all patients, cultures were taken 1 week postoperatively from each pin site; use of antibiotics and complications during the treatment was documented. In 101 consecutive patients (118 knees) (73% men, mean age 50, mean BMI 27.5 kg/m(2)) operated on by high tibial osteotomy for knee deformity using the hemicallotasis technique, during 2005-2006, the theatre dressings were left undisturbed during the first postoperative week in 90 patients (104 knees) of group 1, and in 11 patients (14 knees) of group 2, the theatre dressings were changed during the first postoperative week. Eight of 11 patients in group 2 were treated with antibiotics compared to 32 of 90 patients in group 1 (RR 2.0, 95% CI 1.6-2.7, p = 0.02) during the treatment period by external fixation. Patients with a disturbed theatre dressing during the first postoperative week had an increased use of antibiotics by 18.6 days (95% CI 10.6-26.5, p < 0.0001, adjusted analysis). Four of 11 patients in group 2 had complications and 11 of 90 in group 1, adjusted analysis (RR 2.7, 95% CI 0.4-16.2, p = 0.3). Bilateral surgery simultaneously showed increased use of antibiotics by 10.4 days (4.4, 16.4, p = 0.0009) and increased risk of complications (RR 5.8, 95% CI 1.2-27.5, p = 0.03). In conclusion, the increased use of antibiotics indicates that leaving the theatre dressing undisturbed during the first postoperative week is beneficial to the treatment by external fixation and is probably of importance in the prophylactic pin-site care.

Knee arthroplasty: are patients' expectations fulfilled? A prospective study of pain and function in 102 patients with 5-year follow-up

BACKGROUND AND PURPOSE

With an aging population expecting an active life after retirement, patients' expectations of improvement after surgery are also increasing. We analyzed the relationship between preoperative expectations and postoperative satisfaction and self-reported outcomes with regard to pain and physical function after knee arthroplasty.

PATIENTS AND METHODS

102 patients (39 men) with knee osteoarthritis and who were assigned for TKR (mean age 71 (51-86) years) were investigated with KOOS, SF-36, and additional questions concerning physical activity level, expectations, satisfaction, and relevance of the outcome to the patient. These investigations took place preoperatively and postoperatively after 6 months, 1 year, and 5 years of follow-up.

RESULTS

Response rate at 5 years was 86%. In general, the patients' preoperative expectations were higher than their postoperative ability. For example, 41% expected to be able to perform activities such as golfing and dancing while only 14% were capable of these activities at 5 years. Having high or low preoperative expectations with regard to walking ability or leisure-time activities had no influence on the KOOS scores postoperatively. 93% of the patients were generally satisfied 5 years postoperatively, while 87% were satisfied with the relief of pain and 80% with their improvement in physical function at that time.

INTERPRETATION

With an expanding population of mentally alert elderly, we can expect that great demands will be put on joint replacements. This study shows that patients have high preoperative expectations concerning reduction of pain. To a considerable extent, these expectations are fulfilled after one year. Expectations concerning demanding physical activities are not fulfilled to the same degree; however, most patients reported general satisfaction with the outcome indicating that satisfaction is not equivalent to fulfilled expectations. Preoperative counseling should include realistic information on outcomes concerning physical function and pain relief.

Once-weekly oral medication with alendronate does not prevent migration of knee prostheses: A double-blind randomized RSA study

BACKGROUND AND PURPOSE

Early migration of joint replacements is an effect of poor fixation and can predict late loosening. By reducing the bone resorption after implantation of a joint replacement, it should be possible to enhance the initial fixation of the implant. We studied the effect of once-weekly treatment with alendronate after knee replacement.

PATIENTS AND METHODS

We recruited 60 patients (60 knees) with gonarthrosis who were scheduled for a total knee replacement. They were operated on with identical implants and uncemented fixation. 30 patients were treated with a bisphosphonate (alendronate) and 30 patients underwent placebo treatment. The treatment started postoperatively and continued on a weekly basis for 6 months. The fixation of the implants was measured with repeated radiostereometry for 2 years.

RESULTS

There was no difference in migration of implants between the two groups.

CONCLUSION

With uncemented fixation of knee implants, no benefit of once-weekly treatment with alendronate, starting postoperatively, could be seen during a 2-year follow-up period.

No clinical benefits using a new design of pins for external fixation: a randomized study in 50 patients operated on by the hemicallotasis technique

BACKGROUND

Pin-site infection and pin loosening are complications that can cause discomfort to the patients. The purpose of present study was to evaluate pin-site infection, pain, and the use of medications using the XCaliber pin (Orthofix) with optimized thread and tip design, and the commonly used standard pin (Orthofix) during the procedure of hemicallotasis osteotomy (HCO).

MATERIAL AND METHODS

Fifty patients of mean age 51 (35-66) years treated with HCO were randomized to standard pins (Orthofix) or XCaliber pins (Orthofix). Hydroxyapatite-coated pins were used in the metaphyseal bone and non-coated pins in the diaphyseal bone in both groups. Pin sites, pain, and the use of medications were evaluated weekly during the HCO.

RESULTS

At week 7 the patients in the XCaliber group had more pain at rest [19 (22) vs. 5 (5) mm, P = 0.01] and during activity [32 (32) vs. 12 (13) mm, P = 0.02] and used more paracetamol (2,100 vs. 925 mg, P = 0.04) than those in the standard group, with similar differences, until the extraction of the pins. There was no difference in the use of antibiotics [10.5 (14.5) days (XCaliber) vs. 7 (7.5) days (standard) (P = 0.16)].

CONCLUSION

The commonly used standard pin has important clinical- and patient-related benefits.

A randomised RSA study of Peri-Apatite HA coating of a total knee prosthesis

BACKGROUND

In total knee replacement, sound early fixation of the prosthesis is crucial for achieving a good long-term result and for minimising the risk of loosening. Various types of prosthetic material, different surface textures and shapes and the incorporation of screws or pegs have been used to achieve good fixation, particularly in the uncemented knee. Hydroxyapatite (HA) coating of prosthetic joint components is another technique used to enhance early stability and so to improve the longevity of the prosthesis-bone fixation. HA ceramic coatings are mostly plasma sprayed onto the fixation surface of the implant. Plasma spraying is largely a 'line of sight' technique and as such there are difficulties involved when covering three-dimensional planes, such as porous beaded fixation surfaces typically found on several knee prostheses. The objective of this study was to assess the clinical performance of the solution-deposited HA coating, Peri-Apatite , with regard to its ability to stimulate an endurable and stable implant fixation.

PATIENTS AND METHODS

We randomised 60 patients into two groups; one group received the porous coated prosthesis with solution-deposited HA, and the other group received a prosthesis without HA. Radiostereometric examination was used as the primary tool for measuring migration in the prosthetic components.

RESULTS

There was a lower incidence of early subsidence in the Peri-Apatite group. At 24 months there were no differences in clinical scorings or maximal total point motion.

CONCLUSION

Addition of solution-deposited HA coating appears to provide better early stable fixation in a porous coated knee prosthesis.

Inferior fixation with a new pin design for external fixation: a randomized study in 50 patients operated on by the hemicallotasis technique

BACKGROUND AND PURPOSE

Tibial osteotomy by the hemicallotasis technique (HCO) requires strong pin fixation. We compared pin fixation in HCO using a new self-drilling XCaliber pin (Orthofix) with optimized thread and tip design, with the commonly used standard pin (Orthofix).

PATIENTS AND METHODS

50 patients, mean age 51 (35-66) years, to be treated by HCO were randomized to standard pins or XCaliber pins. In the metaphyseal bone, hydroxyapatite-coated (HA-coated) pins were used in both types of pins. In the diaphyseal bone, non-coated pins were used. The torque forces for insertion and extraction (in Nm) were measured.

RESULTS

The insertion torque was higher for both the proximal and distal standard pins (2.1 Nm (SD 0.9) and 7.0 Nm (1.3), respectively) than for the XCaliber pins (1.3 Nm (0.8) and 3.6 Nm (1.4)). The extraction torque force was higher for the proximal standard pins (4.3 Nm (3.1)) than for the proximal XCaliber pins (1.5 Nm (1.7)) (p < 0.001). The extraction torque for the distal standard pins was 1.9 Nm (2.0) and for the distal XCaliber pins it was 1.4 Nm (1.1).

INTERPRETATION

The commonly used standard pin gives stronger fixation during the treatment of HCO.

No delayed bone healing in Swedish male oral snuffers operated on by the hemicallotasis technique: a cohort study of 175 patients

BACKGROUND AND PURPOSE

The effect of oral snuff on bone healing is virtually unknown. In vitro data have indicated that delay in bone healing in smokers may be the result of components of smoke other than nicotine. We compared the time for bone healing after high tibial osteotomy in snuffers, smokers, and in control subjects who did not use snuff or cigarettes.

PATIENTS AND METHODS

175 male patients comprising 41 smokers, 21 oral snuff users, and 113 non-smokers/non-snuffers, all of whom were operated on for knee deformity by tibial osteotomy using the hemicallotasis technique (HCO) between 2000 and 2005, were included in a consecutive manner. Preoperative tobacco use, postoperative complications, and treatment time in external fixation were documented.

RESULTS

There was no delayed healing in the oral snuff users. The mean time in external fixation for all patients was 94 days (SD 20). Oral snuff users had the shortest time in external fixation (87 days (SD11)) compared to smokers (100 days (SD 25)) (p=0.03) and non-smokers/non-snuffers (93 days (SD 14)). The risk ratio for smokers developing complications was 6.1 (95% CI: 1.2-36.4) compared with oral snuff users.

INTERPRETATION

Our findings indicate that the use of oral snuff does not delay bone healing or increase the risk of postoperative complications, which cigarette smoking does, in patients operated on by the hemicallotasis technique.

Infection prophylaxis: a prospective study in 106 patients operated on by tibial osteotomy using the hemicallotasis technique

INTRODUCTION

Tibial osteotomy by the hemicallotasis technique is a clean elective operation. With external fixation pins inserted, close to the knee joint, the infection prophylaxis should be considered. The primary aim was to investigate the differences in the postoperative use of antibiotics during the time in external fixation between administrating prophylactic antibiotics for 3 days or as a single dose in patients operated on by the hemicallotasis technique for knee deformities. Secondary aims were to study the differences in pin-site infection rate and grade and complications.

MATERIAL AND METHODS

A total of 106 consecutive patients of mean age 52 years (range 18-69) operated on by the hemicallotasis technique for knee deformities were included in this prospective study. Sixty patients were prescribed prophylactic antibiotics for 3 days and 46 patients as a single dose. Chlorhexidine (5 mg/ml) in alcohol (70% ethanol) was used as cleansing agent in the pin-site care. The power of the study was calculated to 80% to detect a difference in the postoperative use of antibiotics for 7 days during the treatment in external fixation.

RESULTS

There were no differences in postoperative use of antibiotics between 3 days administration or a single dose of prophylactic antibiotics. This was the case with infection rate and grade, positive bacterial cultures, presence of Staphylococcus aureus, nor positive culturing from the tip of the pins at removal. Neither were there any differences in numbers of loose pins and complications.

CONCLUSION

There were no differences between 3 days of administration of prophylactic antibiotics and one single dose. One single dose of prophylactic antibiotics is appropriate together with a pin-site concept preventing pin-site infection in patients operated on by hemicallotasis osteotomy.

Mobile vs. fixed meniscal bearing in total knee replacement: a randomised radiostereometric study

52 knees scheduled for a total knee arthroplasty were randomised to either a fixed or a mobile polyethylene bearing. The design was identical in all parts. The knee systems used were the Rotaglide Total Knee System (RTK) and the Nuffield Total Knee System (NTK), both from the same manufacturer (Corin Medical Ltd., UK). All knees implanted were uncemented. The patients were followed for 2 years clinically and with radiostereometric analyses to assess migration over time and inducible displacement of the tibial component. Separate analysis of the mobility of the tibial insert in the knees with a mobile bearing was also made. The migration measured with RSA between the 1st and 2nd year expressed as maximum total point motion (MTPM) might predict the risk of loosening of the implant. There were no differences between the groups regarding clinical outcome (HSS Knee score), migration or inducible displacement during the 2 years follow-up. The movement between the tibial tray and the mobile meniscal insert expressed as maximum total point motion (MTPM) was 6.8+/-3.3 mm at the 1st year follow-up.

A 2-year prospective study of patient-relevant outcomes in patients operated on for knee osteoarthritis with tibial osteotomy

BACKGROUND

Tibial osteotomy is a treatment for younger and/or physically active patients suffering from uni-compartmental knee osteoarthritis. The open wedge osteotomy by the hemicallotasis technique includes the use of external fixation. The use of external fixation has several advantages, as early mobilization and the opportunity for optimal correction. However, the hemicallotasis technique has also been described as a cumbersome procedure for the patient. The aim of this study was to prospectively evaluate patient-relevant outcomes during the first 2 post-operative years. Especially the treatment period, during which external fixation was used, was closely monitored.

METHODS

In an uncontrolled study, fifty-eight consecutive patients, 30 men and 28 women (mean age 54 years) were operated on by the hemicallotasis technique were evaluated with the patient-relevant outcome measure Knee injury and Osteoarthritis Outcome Score (KOOS) preoperatively, during the treatment with external fixation, one week after removal of the external fixation, at 6 months, and at one and two years postoperatively.

RESULTS

At the 2-year postoperative follow-up, all subscales of the KOOS were improved (p < 0.001), mostly in pain (41-80 on a 0-100 worst to best scale) and knee-related quality of life (21-61 on a 0-100 worst to best scale), compared to the preoperative status. Significant improvements in pain and other symptoms, function of daily life and quality of life were seen already during the treatment period (mean 98 +/- 18 days) with the external fixation. More demanding functions such as kneeling, squatting, jumping and running, were improved first after extraction of the external fixation device and the pins.

CONCLUSION

Tibial osteotomy by the hemicallotasis technique yields large improvement in self-rated pain, function and quality of life, which persists over two years. Surprisingly, large improvements occurred already during the immediate post-operative period when the external fixation was still used.

Pin site care in external fixation sodium chloride or chlorhexidine solution as a cleansing agent

INTRODUCTION

Pin site infection is the most common complication using external fixators. This study investigated the differences in pin site infections, antibiotic use, pain, and complications using sodium chloride and chlorhexidine solution as cleansing agent in patients operated on by the hemicallotasis technique for knee deformities.

MATERIALS AND METHODS

The prospective study included 49 consecutive patients: 2 mg/ml chlorhexidine solution was used as cleansing agent in 30 patients (120 pins) and 9 mg/ml sodium chloride in 19 patients (76 pins). We evaluated the status of the pin sites, pain (VAS), uses of antibiotic and analgesic agents, and any complications (infections were graded according to the Checketts-Otterburns classification). Bacterial cultures were performed from each pin site at 1, 6, and 10 weeks and from the pins at removal.

RESULTS

Grade 1 infection was found in 14% of the sodium chloride group and in 8.5% of the chlorhexidine group, and grade 2 infection in and 3% and 0.5%, respectively. With sodium chloride there was a significantly higher relative risk for positive cultures (1.7) and for the presence of Staphylococcus aureus (3.3). The chlorhexidine group required significantly fewer antibotics reported significantly less pain at weeks 6 and 10.

CONCLUSIONS

Chlorhexidine solution (2 mg/ml) as cleansing agent in pin site care is preferable to sodium chloride in patients operated on by the hemicallotasis technique.

Cigarette smoking delays bone healing: a prospective study of 200 patients operated on by the hemicallotasis technique

BACKGROUND

Cigarette smoking is known to impede bone healing. The hemicallotasis technique is based on an external fixation and delayed healing prolongs treatment and increases the risk of further complications.

PATIENTS AND METHODS

200 patients, 34 smokers and 166 nonsmokers, operated on by the hemicallotasis technique in the proximal tibia for deformities of the knee (knee arthrosis in 186 patients) were consecutively studied. We recorded their preoperative smoking habits, postoperative complications and the duration of treatment with external fixation.

RESULTS

Half of the smokers and one fifth of the nonsmokers developed complications. Their mean time in external fixation was 96 (SD 20) days. Smokers required an average of 16 days more in external fixation. Delayed healing and pseudoarthrosis were commoner in smokers than nonsmokers. The risk ratio for smokers to develop complications was 2.5, as compared to nonsmokers.

No difference between daily and weekly pin site care: a randomized study of 50 patients with external fixation

INTRODUCTION

We investigated whether there were any differences in the frequency and severity of pin site infections by performing pin site care daily or once a week. We studied patients operated on for gonarthrosis by the hemicallotasis technique, using hydroxyapatite-coated pins in the metaphyseal bone and standard pins in the diaphyseal bone.

PATIENTS AND METHODS

50 patients were prospectively randomized to daily (n = 27) or weekly (n = 23) pin site care. We evaluated pin sites, the occurrence of pain (VAS), the use of antibiotics and analgesics and complications every week. Bacterial cultures were taken from each pin site at 1, 6 and 10 weeks and from the pins on removal.

RESULTS

We found no differences between daily or weekly pin site care as regards the frequency and severity of pin site infections, pain, or the use of antibiotics and analgesics. Grade I infections (Checketts-Otterburns classification) occurred around 11% of the pins and grade II infections around 4%. 70% of the bacterial cultures were negative. The most frequent bacteria were coagulase negative staphylococcus and corynebacterium. Antibiotics were given an average of 47 days. More problems occurred around the proximal pins. 5/200 (all proximal) pins were clinically loose on removal.

INTERPRETATION

Pin site care once a week seems appropriate.

Bone morphology in relation to the migration of porous-coated anatomic knee arthroplasties : a roentgen stereophotogrammetric and histomorphometric study in 23 knees

The quality of the subchondral bone in total knee arthroplasty (TKA) may be important for the outcome. We correlated a histomorphologic analysis of the prosthetic bone bed to micromotion as analyzed by roentgen stereophotogrammetric analysis (RSA). Twenty-three knees, both osteo- and rheumatoid arthritic were studied. The mean migration after 1 year was 1 mm (0.21-2.68), with no correlation to the bone variables or diagnosis. One patient underwent revision after 3 years because of pain. One patient underwent revision after 15 years because of aseptic loosening. This patient appeared stable according to changes in maximum total point motion (MTPM), but the prosthesis migrated continuously according to segment motion. Prosthetic migration increased after 10 years, zones started to evolve, and the patient became symptomatic after 13 years. A biopsy of the bone bed was taken in all patients. A larger percentage of trabecular bone and a larger relative area of unmineralized osteoid surface were found in patients with rheumatoid arthritis compared with those with osteoarthritis. The latter finding is probably a result of increased bone turnover. In conclusion, no support currently exists for the idea that preoperative bone quality, evaluated as bone histomorphometry, has any impact on prosthetic micromotion in knee prostheses.

Knee injury and Osteoarthritis Outcome Score (KOOS) - validation and comparison to the WOMAC in total knee replacement

BACKGROUND

The Knee injury and Osteoarthritis Outcome Score (KOOS) is an extension of the Western Ontario and McMaster Universities Osteoarthrtis Index (WOMAC), the most commonly used outcome instrument for assessment of patient-relevant treatment effects in osteoarthritis. KOOS was developed for younger and/or more active patients with knee injury and knee osteoarthritis and has in previous studies on these groups been the more responsive instrument compared to the WOMAC. Some patients eligible for total knee replacement have expectations of more demanding physical functions than required for daily living. This encouraged us to study the use of the Knee injury and Osteoarthritis Outcome Score (KOOS) to assess the outcome of total knee replacement.

METHODS

We studied the test-retest reliability, validity and responsiveness of the Swedish version LK 1.0 of the KOOS when used to prospectively evaluate the outcome of 105 patients (mean age 71.3, 66 women) after total knee replacement. The follow-up rates at 6 and 12 months were 92% and 86%, respectively.

RESULTS

The intraclass correlation coefficients were over 0.75 for all subscales indicating sufficient test-retest reliability. Bland-Altman plots confirmed this finding. Over 90% of the patients regarded improvement in the subscales Pain, Symptoms, Activities of Daily Living, and knee-related Quality of Life to be extremely or very important when deciding to have their knee operated on indicating good content validity. The correlations found in comparison to the SF-36 indicated the KOOS measured expected constructs. The most responsive subscale was knee-related Quality of Life. The effect sizes of the five KOOS subscales at 12 months ranged from 1.08 to 3.54 and for the WOMAC from 1.65 to 2.56.

CONCLUSION

The Knee injury and Osteoarthritis Outcome Score (KOOS) is a valid, reliable, and responsive outcome measure in total joint replacement. In comparison to the WOMAC, the KOOS improved validity and may be at least as responsive as the WOMAC.

Analysis of the distribution and frequency of trisomy 7 in vivo in synovia from patients with osteoarthritis and pigmented villonodular synovitis

Osteoarthritis (OA) and pigmented villonodular synovitis (PVNS) are disorders associated with trisomy 7. The aim of the present study was to determine the frequency and distribution of the cells with +7 in vivo by analyzing sections of paraffin-embedded synovia from patients affected by OA, PVNS, other forms of synovitis [hemorragic synovitis (HS) and chronic synovitis (CS)], and from individuals without joint disease. Fluorescence in situ hybridization (FISH), using a centromeric probe for chromosome 7, showed that the mean frequency of trisomic nuclei in 5-microm sections was highest in PVNS (9.0%), followed by CS (5.9%), OA (5.6%), and HS (4.6%), whereas trisomic nuclei were rare (0.7%) in normal tissue. When 8-microm sections were studied, the frequencies of trisomic cells in OA and control synovia increased to 6.7% and 1.5%, respectively. Trisomic nuclei were found in all cases, including those for which cytogenetic analysis of short-term cultures had not disclosed any trisomic cells. Overall, the trisomic cells were scattered within the tissue. However, small clusters of cells with +7 were found in three cases. By hematoxylin-eosin staining of the slides used for FISH analysis it could be shown that the clustered trisomic cells were proliferating synoviocytes within villous extensions of the synovial membrane.

The patella in total knee arthroplasty: resurfacing or nonresurfacing of patella

Data from the Swedish Knee Arthroplasty Registry were analyzed to compare bi- and tricompartmental knee arthroplasties carried out in patients operated on for arthrosis in 1990-1996. Of the 16,607 primary arthroplasties that were carried out there were 5,139 with patellar replacement in the primary procedure and 10,928 without. By April 1998, 280 revisions were performed, 250 of these cases were analyzed in this study. Patella-related complications were commonly the reason for early revision: in 99 of the 168 knees with a primary bicompartmental procedure and in 36 of the 82 knees with a primary tricompartmental procedure. This presentation merely analyzes the extent of patellar problems in knee arthroplasty, as a detailed analysis of the causes of this common problem is not possible using data from a national multicenter study.

Fixation strength and pin tract infection of hydroxyapatite-coated tapered pins

In a multicenter, prospective, randomized study, the biomechanical and clinical properties of the bone-pin interface were compared with standard tapered pins and hydroxyapatite-coated tapered pins implanted in patients who underwent femoral and tibial external fixation treatments. The results showed that the hydroxyapatite-coated tapered pins are clinically effective in improving the strength of fixation of the bonepin interface. This improvement corresponded to a lower rate of pin tract infection. In the hydroxyapatite-coated pin group, there were no differences in strength of fixation between the pins removed from the infected and uninfected pin tracts. In this pin group, the mean pin extraction torque was 531 +/- 225 Ncm in the infected pin tracts and 508 +/- 233 Ncm in the uninfected pin tracts. In the standard pin group, the mean pin extraction torque was 73 +/- 142 Ncm in the infected pin tracts and 211 +/- 216 Ncm in the uninfected pin tracts. The advantages provided by the hydroxyapatite-coated pins were higher in cancellous bone than in cortical bone.

The tumor-associated gene HMGIC is expressed in normal and osteoarthritis-affected synovia

Chromosomal rearrangements involving chromosome bands 12q13-15 are very frequent findings in benign solid tumors, and recently, the primary molecular target for these aberrations was identified as the gene HMGIC. However, mutations in this gene have also been observed in nonneoplastic tissues. In a previous study, we reported breakpoints within HMGIC of synovia affected by osteoarthritis (OA) in two cases with 12q15 aberrations. To analyze further the role of HMGIC in this disease, we have performed cytogenetic, fluorescent in situ hybridization (FISH), RNA, and protein expression analyses on synovial samples from patients with OA and individuals without signs of the disorder. Cytogenetic analysis of short-term cultured cells revealed clonal 12q13-15 aberrations in 2/36 cases of OA synovia and no rearrangement in any of the five controls. With FISH analysis, it was shown that the chromosomal breakpoints in the two aberrant cases were located outside the HMGIC locus. In contrast, at RNA and protein expression analyses, OA-affected as well as normal synovia displayed transcription and translation of the gene. We also analyzed whether immunoreactivity for HMGIC was associated with the proliferation-specific antigen Ki-67, but no correlation between the staining patterns of these proteins was observed. From the results of the present study, it is evident that expression of HMGIC cannot simply be considered a sign of neoplasia or an effect of proliferation.

Trisomy 7 accumulates with age in solid tumors and non-neoplastic synovia

Trisomy 7 is a common finding in benign and malignant solid tumors, in several non-neoplastic lesions (for example, osteoarthritis and rheumatoid arthritis), and in apparently normal tissues as well, suggesting that the occurrence of +7 might be associated with factors other than the disease process itself. To find out whether the frequency of +7 varies with a patient's age, we cytogenetically analyzed short-term-cultured synovial samples from elderly persons without signs of arthritis and from young patients affected by juvenile chronic arthritis (JCA). In normal synovia, gain of a chromosome 7 was present as a clonal change in five of 10 cases and in single cells in four of the five remaining cases. In synovia from patients with JCA, cells with +7 were detected in only one of nine cases, representing the oldest patient in the series. Furthermore, we reviewed the cytogenetic literature on tumors of the brain, breast, colon, kidney, lung, skin, thyroid, and upper aerodigestive tract. In the majority (six of eight) of these tumor types, the frequency of cases displaying a clone with +7 as the sole aberration increased with age. Taken together, the results presented here suggest that the acquisition of trisomy 7 in some neoplastic and non-neoplastic tissues might be associated with age rather than with disease. The finding of a completely different frequency distribution in two of the tumor types (tumors of the brain and the thyroid gland), however, emphasizes the heterogeneity of +7 and indicates that other, possibly tissue-specific, factors might influence the occurrence of this mutation.

Clodronate prevents prosthetic migration: a randomized radiostereometric study of 50 total knee patients

In a double-blind study, we randomized 50 patients to receive peroral clodronate medication or placebo from 3 weeks before until 6 months after a total knee replacement with a cemented NexGen implant. Migration of the tibial components was measured by radiostereometry at 1 year. Clodronate reduced prosthetic migration, as measured by maximum total point motion, from 0.40 mm to 0.29 mm (p = 0.01). This confirms that the early postoperative migration is related to bone resorption and thus the biology of the bone bed. Since early migration is related to late loosening, 6 months of clodronate medication might reduce the risk of loosening.

Digital automated RSA compared to manually operated RSA

The accuracy of digital Roentgen stereophotogrammetric analysis (RSA) was compared to the accuracy of a manually operated RSA system. For this purpose, we used radiographs of a phantom and radiographs of patients. The radiographs of the patients consisted of double examinations of 12 patients that had a tibial osteotomy and of double examinations of 12 patients that received a total hip prosthesis. First, the radiographs were measured manually with an accurate measurement table. Subsequently, the images were digitized by a film scanner at 150 DPI and 300 DPI resolutions and analyzed with the RSA-CMS software. In the phantom experiment, the manually operated system produced significantly better results than the digital system, although the maximum difference between the median values of the manually operated system and the digital system was as low as 0.013mm for translations and 0.033 degrees for rotations. In the radiographs of the patients, the manually operated system and the digital system produced equally accurate results: no significant differences in translations and rotations were found. We conclude that digital RSA is an accurate, fast, and user friendly alternative for manually operated RSA. Currently, digital RSA systems are being used in a growing number of clinical RSA-studies.

Polyclonal expansion of cells with trisomy 7 in synovia from patients with osteoarthritis

Trisomy 7 as the single chromosome aberration has been found in a variety of neoplasms and in normal tissue in the proximity of tumors, as well as in non-neoplastic lesions. Recently, we described a nonrandom pattern of chromosome aberrations, in particular, a gain of chromosome 7, in synovia, cartilage, and osteophytes from patients with osteoarthritis. To study the clonal origin of trisomy 7 in osteoarthritis, multiple synovial samples were collected from five women, all of whom were informative heterozygotes with regard to the X-linked human androgen receptor gene (AR). From each case, three to four independent cell cultures were initiated. Trisomic cell populations were subcloned from the individual cultures, and it was established whether or not the same allele of AR was inactivated in trisomic cells from different parts of the same joint. The finding of a polyclonal X-inactivation pattern in two of the cases provides strong evidence that gain of an extra copy of chromosome 7 occurs independently in multiple cells.

The introduction period of unicompartmental knee arthroplasty is critical: a clinical, clinical multicentered, and radiostereometric study of 251 Duracon unicompartmental knee arthroplasties

One hundred twenty-eight consecutive knees were operated on with the Duracon unicompartmental knee arthroplasty. Of 111 knees, followed 3 years (range, 1-6 years), 109 knees were satisfactory. Two knees were revised because of progression of osteoarthritis and inexplicable pain. Radiostereometric analysis in 49 knees showed a migration of 0.6 mm after 2 years. The magnitude of migration was lower in comparison with published series. In a multicenter study comprising 4 other hospitals, there were 8 revisions in 123 operated knees. The reasons were loosening, subsidence, or fracture. These revisions were within 1 year and mostly related to operative technique. Unicompartmental knee arthroplasty is a demanding procedure that needs special experience and includes a risk of early failures during the introduction of a system.

Hydroxyapatite-enhanced tibial prosthetic fixation

Sixty-two knees (60 patients) were randomized to four noncemented groups. In Groups 1, 3, and 4, the bone cuts were made with a cooled saw blade. In Group 1, 15 patients were operated on with the porous coated Osteonic 7000 tibial component. In Group 2, 15 patients were operated on with the same tibial component as in Group 1 but with the use of a standard saw blade. In Group 3, 16 patients were operated on with the hydroxyapatite-coated Osteonic tibial component, and in Group 4, 16 patients were operated on with the hydroxyapatite Duracon tibial component. All patients were followed up clinically and with roentgenstereometric analysis. There were no differences among the groups regarding clinical outcome. One knee was revised (Group 2) after 1 year because of loosening of the tibial component. The maximum migration at 1 year was 1.7 mm in Group 1, 1.9 mm in Group 2, 1.3 mm in Group 3, and 1 mm in Group 4. At the 2-year followup, the migrations were 1.8 mm, 1.5 mm, 1.4 mm, and 1 mm in Groups 1, 2, 3, and 4, respectively. The inducible displacement that occurred at 1 year was 0.6 mm in Group 1, 0.5 mm in Group 2, 0.4 mm in Group 3, and 0.4 mm in Group 4. The hydroxyapatite coating had a strong positive effect on the tibial component fixation. No prosthesis in the hydroxyapatite groups showed continuous migration.

Changes in osseous correction after proximal tibial osteotomy: radiostereometry of closed- and open-wedge osteotomy in 33 patients

33 patients (22 men), median age 54 (40-68) years, with medial gonarthrosis grades 1-3, were treated by closed-wedge osteotomy (high tibial osteotomy = HTO, n 16) or open-wedge osteotomy by hemicallotasis (hemicallotasis osteotomy = HCO, n 19). 2 patients were operated on bilaterally. The patients were studied by RSA (radiostereometric analysis) for measuring 3-D changes in the correction achieved. In the HTO group the RSA measurements were obtained at the time of plaster removal, 1 month later and 1 year after surgery. In the HCO group, the RSA measurements were performed at the time of removal of the external fixator, 1 month later and 1 year after surgery. After removal of the fixation, HTO was associated with increased medial/lateral and distal translation of the proximal segment, compared to HCO. In addition, the tibial plateau rotated more around the longitudinal axis of the tibia after HTO.