No Difference in Revision Rates and High Survival Rates in Large-head Metal-on-metal THA Versus Metal-on-polyethylene THA: Long-term Results of a Randomized Controlled Trial.

BACKGROUND: Pseudotumor formation is a well-known complication in metal-on-metal (MoM) THA. Pseudotumors combined with elevated serum ion levels and complaints from patients can lead to high revision rates. Long-term (> 10 years) results obtained from randomized trials comparing large-head MoM THA and conventional metal-on-polyethylene (MoP) THA are lacking regarding revision and survival rates, pseudotumor formation, functional outcomes, and serum ion levels. QUESTIONS/PURPOSES: At 10 years of follow-up, (1) what is the difference in survival and revision rates between large-head (38 to 60 mm) MoM THA and conventional 28-mm MoP THA? (2) What is the difference in pseudotumor formation between large-head MoM THA and MoP THA? (3) Is there a difference in functional outcome between large-head MoM THA and MoP THA? (4) What is the difference in serum ion levels between large-head MoM THA and MoP THA? METHODS: Between January 2006 and December 2008, 104 patients were randomized to receive either cementless MoM THA (50 patients) or cementless MoP THA (54 patients). In all, 78% (81 of 104) of patients completed the 10-year postoperative follow-up: 36 patients with MoM THA (72%; six patients lost to follow-up) and 45 with MoP THA (83%; four lost to follow-up). In the MoM group, 47% (17) were men, and the patients had a mean ± SD age of 60 ± 5 years. In the MoP group, 38% (17) were men, and the patients had a mean age of 61 ± 5 years. All baseline characteristics were similar between the groups. At 10 years of follow-up, all patient records were screened for revision surgery or complications, and the primary endpoint was survivorship free from revision for any cause at the 10-year follow-up interval, which we analyzed using a Kaplan-Meier survival analysis. All patients had a CT scan to determine the pseudotumor classification, which was reviewed by an independent radiologist. Functional outcome was measured using the patient-reported Oxford Hip Score and Harris Hip Score; the latter was assessed by a blinded nurse practitioner. Finally, serum ion cobalt and chrome concentrations were measured at 10 years postoperatively. Because the a priori sample size calculation for this randomized controlled trial was based on a different endpoint, a post hoc power analysis was performed for this long-term follow-up study, with survival as the primary outcome. It showed that considering the number of included patients, this study would have sufficient power (one-sided testing, alpha 0.05, power 80%) to discern a difference of 20% in the survival rate between the MoP and MoM groups (95% versus 75%). RESULTS: With the numbers available, there was no difference in survivorship free from revision for any cause between the MoP group and MoM group at 10 years (95% [95% CI 85% to 98%] versus 92% [95% CI 82% to 98%]; p = 0.6). A higher percentage of patients in the MoM group had pseudotumors on CT than those in the MoP group did, but pseudotumors were observed in both groups (56% [20 of 36] in the MoM group versus 22% [10 of 45] in the MoP group, relative risk 1.8 [95% CI 1.2 to 2.6]; p = 0.002). A higher proportion of elevated cobalt and chrome levels was found in the MoM group (19% and 14%, respectively) than in the MoP group (0% for both cobalt and chrome) (cobalt: RR 1.2 [95% CI 1.1 to 1.5]; p = 0.002; chrome: RR 1.2 [95% CI 1.0 to 1.3]; p = 0.01). In 25% of the patients with pseudotumors (5 of 20 patients), there were elevated serum cobalt levels. None of the 23 patients without pseudotumors had elevated cobalt levels (RR 1.3 [95% CI 1.0 to 1.7]; p = 0.01). There was no difference in functional outcome between study groups, nor a difference between patients with a pseudotumor and those without. CONCLUSION: This study showed that the survival of patients with large-head MoM THA was high and comparable to that of those with MoP THA, which contrasts with the high revision rates reported by others. Although some patients with MoP THAs experienced pseudotumors, the risk of a pseudotumor was much greater in MoM hips, and serum ion levels were higher in patients who received an MoM THA. For these reasons and unknown future complications, continued surveillance of patients with MoM THAs seems important. LEVEL OF EVIDENCE: Level I, therapeutic study.

Popliteal Skin Lesion due to Wear Disease in Total Knee Arthroplasty: A Case Report.

CASE: An 87-year-old woman presented with a popliteal skin lesion due to polyethylene wear 13 years following a left total knee arthroplasty. Excisional biopsy through a posterior approach was performed. Histology showed inflammation with granulomas and birefringent foreign body particles in the skin. Cultures remained negative, and revision knee arthroplasty was performed. CONCLUSIONS: A popliteal skin lesion due to polyethylene wear disease in total knee arthroplasty has not previously been described. Patients with an atypical inflammation of the skin with an underlying joint implant should be referred to an orthopaedic surgeon, and dermal biopsies should be checked for birefringent material. LEVEL OF EVIDENCE: Level V.

A Woman with Rheumatoid Arthritis and a Bilateral Fracture of the Proximal Tibia.

A 52-year-old woman presented herself with pain on the medial sides of the proximal tibia after a minimal trauma. Conventional X-rays did not show any pathology. However, the MRI showed a bilateral fracture of the proximal tibia. Since the patient was treated with methotrexate due to rheumatoid arthritis, methotrexate osteopathy was considered. Long term treatment with low doses of methotrexate proved to inhibit osteoblast proliferation and may eventually lead to decreased bone formation and osteopenia. On the other hand, immobilization, joint deformities, and steroid treatment are associated with rheumatoid arthritis and are also known risk factors for fractures. The clinical relevance of methotrexate osteopathy still has to be established. However, if a patient treated with methotrexate localizes pain in the tibia, methotrexate osteopathy should be considered. Withdrawal of the drug may improve symptoms.

No difference in gait between posterior cruciate retention and the posterior stabilized design after total knee arthroplasty.

PURPOSE: In the present study, knee joint kinematics (e.g. knee flexion/extension) and kinetics (e.g. knee flexion moments) are assessed after total knee arthroplasty (TKA) between patients implanted with either a unilateral posterior stabilized (PS) and a posterior cruciate-retaining (PCR) design. It was hypothesized that maximum knee flexion during the loading response of the stance phase is greater in patients implanted with a PS design than in patients with a PCR design. Secondarily, it was hypothesized that patients with a PS design show decreased knee flexion moments during loading, compared with patients implanted with a PCR design. METHODS: This study examined two groups of TKA patients: one group (n = 12) with a PS design in which the posterior cruciate ligament (PCL) was sacrificed and the other (n = 9) with a PCR design. Gait analysis was used in level walking before and 6-9 months after surgery, to assess knee joint kinematics and kinetics during the loading response of the stance phase. RESULTS: No significant differences in maximum knee flexion between the two groups were found during the loading response of the stance phase. No significant differences in knee flexion moments were found either. Although in both groups knee flexion moments increased postoperatively, this was not statistically significant. In the contralateral (nonimplanted) knees, all mean knee flexion moments decreased postoperatively for both groups, yet this was not significant. CONCLUSIONS: The present gait analysis study showed no differences in kinematics and kinetics between the PS and the PCR TKP design. This might suggest that surgeons do not necessarily need to substitute the PCL by a PS design during TKA. LEVEL OF EVIDENCE: Prospective comparative study, Level II.

Physical activity behavior of patients 1 year after primary total hip arthroplasty: a prospective multicenter cohort study.

BACKGROUND: Besides the important beneficial effects of regular physical activity on general health, some of the musculoskeletal effects of physical activity are of particular interest for older adults after total hip arthroplasty (THA). However, research on physical activity behavior of patients after THA is scarce. OBJECTIVE: The purpose of this study was to gain insight into the physical activity behavior and fulfillment of guidelines for health-enhancing physical activity of patients 1 year after THA. Design This was a prospective multicenter cohort study. METHODS: To determine level of physical activity, 653 participants (response rate=77%) completed the Short QUestionnaire to ASsess Health-enhancing physical activity (SQUASH). Comparisons were made between participants in 2 age groups (≤75 and >75 years). Determinants of physical activity behavior were assessed. RESULTS: The participants were physically active a mean of 1,468 minutes per week. Most time was spent in household and leisure activities. Younger participants were physically more active than older participants. A lower body mass index was predictive of a higher level of physical activity. Participants adhered to the guidelines of health-enhancing physical activity in 67% of cases. The guidelines were met more often by younger participants, male participants, and those without problems in the lower extremities. Limitations A nonresponse analysis was not conducted; thus, there might have been a selection bias. Use of a self-administered recall questionnaire to assess physical activity behavior may have been subject to memory and recall skill limitations of the participants, and patients tend to overestimate their physical activity level. CONCLUSIONS: This study gives detailed insight into the physical activity of patients 1 year after primary THA. As among the general population, a considerable number of patients were found to be insufficiently physically active.

Retention of the posterior cruciate ligament versus the posterior stabilized design in total knee arthroplasty: a prospective randomized controlled clinical trial.

BACKGROUND: Prosthetic design for the use in primary total knee arthroplasty has evolved into designs that preserve the posterior cruciate ligament (PCL) and those in which the ligament is routinely sacrificed (posterior stabilized). In patients with a functional PCL the decision which design is chosen depends largely on the favour and training of the surgeon.The objective of this study is to determine whether the patient's perceived outcome and speed of recovery differs between a posterior cruciate retaining total knee arthroplasty and a posterior stabilized total knee arthroplasty. METHODS/DESIGN: A randomized controlled trial will be conducted. Patients who are admitted for primary unilateral TKA due to primary osteoarthrosis are included when the following inclusion criteria are met: non-fixed fixed varus or valgus deformity less than 10 degrees, age between 55 and 85 years, body mass index less than 35 kg/m(2) and ASA score (American Society of Anaesthesiologists) I or II. Patients are randomized in 2 groups. Patients in the posterior cruciate retaining group will receive a prosthesis with a posterior cut-out for the posterior cruciate ligament and relatively flat topography. In patients allocated to the posterior stabilized group, in which the posterior cruciate ligament is excised, the design may substitute for this function by an intercondylar tibial prominence that articulates with the femur in flexion. Measurements will take place preoperatively and 6 weeks, 3 months, 6 months and 1 year postoperatively.At all measurement points patient's perceived outcome will be assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Secondary outcome measures are quality of life (SF-36) and physician reported functional status and range of motion as determined with the Knee Society Clinical Rating System (KSS). DISCUSSION: In the current practice both posterior cruciate retaining and posterior stabilized designs for total knee arthroplasty are being used. To date no studies have been performed determining whether there is a difference in patient's perceived outcome between the two designs. Additionally, there is a lack of studies determining the speed of recovery in both designs as most studies only determine the final outcome. This randomised controlled study has been designed to determine whether the patient's perceived outcome and speed of recovery differs between a posterior cruciate retaining total knee arthroplasty and a posterior stabilized total knee arthroplasty. TRIAL REGISTRATION: The trial is registered in the Netherlands Trial Registry (NTR1673).

Reliability and validity of the short questionnaire to assess health-enhancing physical activity (SQUASH) in patients after total hip arthroplasty.

BACKGROUND: Despite recognized benefits of regular physical activity on musculoskeletal fitness as well as general health, little is known about the physical activity behavior of patients after Total Hip Arthroplasty (THA). So far, no physical activity questionnaire has been validated in this category of patients. As the Short Questionnaire to Assess Health-enhancing physical activity (SQUASH) has been shown to be a fairly reliable and valid tool to gauge the physical activity behavior of the general Dutch adult population, we measured the reliability and relative validity of this tool in patients after THA. METHODS: 44 patients (17 men and 27 women, mean age 71 +/- 8 years) completed the SQUASH twice with an in-between period of 2 to 6 weeks (mean 3.7). Reliability was determined by calculating the Spearman correlation coefficient between the activity scores of the separate questions as well as the total activity scores from both administrations. Additionally, a Bland & Altman analysis was performed for the total activity scores. Relative validity was determined using the Actigraphaccelerometer, worn by 39 patients (15 men and 24 women, mean age 70 +/- 8 years) for a 2-week period following the second questionnaire, as a criterion measure. RESULTS: Spearman's correlation coefficient for overall reliability was 0.57. It varied between 0.45 and 0.90 for the separate questions. No systematic biases between readings were found. The Spearman correlation between Actigraph readings and total activity score was 0.67. It was 0.56 for total minutes of activity, 0.20 for time spent in light intensity activity, 0.40 for moderate activity and 0.35 for vigorous activity. Systematic bias was found between the SQUASH and the Actigraph. CONCLUSION: The SQUASH can be considered to be a fairly reliable tool to assess the physical activity behavior of patients after THA. Validity was found to be comparable with those of other questionnaires, and as it is short and easy to fill in, it may prove to be a useful tool to assess physical activity in this particular subset of the population. However, the considerable systematic bias found in this study illustrates the need for further analysis of the validity of the SQUASH.

Large head metal-on-metal cementless total hip arthroplasty versus 28 mm metal-on-polyethylene cementless total hip arthroplasty: design of a randomized controlled trial.

BACKGROUND: Osteoarthritis of the hip is successfully treated by total hip arthroplasty with metal-on-polyethylene articulation. Polyethylene wear debris can however lead to osteolysis, aseptic loosening and failure of the implant. Large head metal-on-metal total hip arthroplasty may overcome polyethylene wear induced prosthetic failure, but can increase systemic cobalt and chromium ion concentrations. The objective of this study is to compare two cementless total hip arthroplasties: a conventional 28 mm metal-on-polyethylene articulation and a large head metal-on-metal articulation. We hypothesize that the latter arthroplasties show less bone density loss and higher serum metal ion concentrations. We expect equal functional scores, greater range of motion, fewer dislocations, fewer periprosthetic radiolucencies and increased prosthetic survival with the metal-on-metal articulation. METHODS: A randomized controlled trial will be conducted. Patients to be included suffer from non-inflammatory degenerative joint disease of the hip, are aged between 18 and 80 and are admitted for primary cementless unilateral total hip arthroplasty. Patients in the metal-on-metal group will receive a cementless titanium alloy acetabular component with a cobalt-chromium liner and a cobalt-chromium femoral head varying from 38 to 60 mm. Patients in the metal-on-polyethylene group will receive a cementless titanium alloy acetabular component with a polyethylene liner and a 28 mm cobalt-chromium femoral head. We will assess acetabular bone mineral density by dual energy x-ray absorptiometry (DEXA), serum ion concentrations of cobalt, chromium and titanium, self reported functional status (Oxford hip score), physician reported functional status and range of motion (Harris hip score), number of dislocations and prosthetic survival. Measurements will take place preoperatively, perioperatively, and postoperatively (6 weeks, 1 year, 5 years and 10 years). DISCUSSION: Superior results of large head metal-on-metal total hip arthroplasty over conventional hip arthroplasty have been put forward by experts, case series and the industry, but to our knowledge there is no randomized controlled evidence. CONCLUSION: This randomized controlled study has been designed to test whether large head metal-on-metal cementless total hip arthroplasty leads to less periprosthetic bone density loss and higher serum metal ion concentrations compared to 28 mm metal-on-polyethylene cementless total hip arthroplasty. TRIAL REGISTRATION: Netherlands Trial Registry NTR1399.