Total knee arthroplasty following lateral closing-wedge high tibial osteotomy versus primary total knee arthroplasty: a propensity score matching study

BACKGROUND

The disparity in patient-reported outcomes between total knee arthroplasty (TKA) following high tibial osteotomy (HTO) and primary TKA has yet to be fully comprehended. This study aims to compare the patient-reported outcomes, radiological parameters and complication rates between TKA following HTO and primary TKA.

METHODS

Sixty-five patients who underwent TKA following lateral closing-wedge HTO were compared to a matched group of primary TKA at postoperative 6-months and 1-year. Between-group confounders of age, gender, smoking status, Body Mass index, preoperative Numeric Rating Scale (NRS) pain in rest, Knee injury and Osteoarthritis Outcome Score-Physical function Shortform (KOOS-PS), EuroQol five-dimensional (EQ-5D) overall health score, and Oxford Knee Score (OKS) were balanced by propensity score matching. Patient-reported outcome measures were NRS pain in rest, KOOS-PS, EQ-5D overall health score, and OKS. Radiological parameters were femorotibial angle, medial proximal tibial angle, anatomical lateral distal femoral angle, posterior tibial slope, and patellar height assessed by Insall-Salvati ratio. The complication rates of TKA were compared between the two groups. The HTO survival time, the choice of staple removal before or during TKA in patients who underwent TKA following HTO patients, and the rate of patellar resurfacing were assessed. The p value < 0.0125 indicates statistical significance after Bonferroni correction.

RESULTS

After propensity score matching, no significant between-group differences in the patient-reported outcome measures, radiographical parameters and complication rates were found (p > 0.0125). In the TKA following HTO group, with an average HTO survival time of 8.7 years, staples were removed before TKA in 46 patients (71%) and during TKA in 19 patients, and 11 cases (17%) had patella resurfacing. In the primary TKA group, 15 cases (23%) had patella resurfacing.

CONCLUSION

The short-term assessment of TKA following HTO indicates outcomes similar to primary TKA. A previous HTO does not impact the early results of subsequent TKA, suggesting that the previous HTO has minimal influence on TKA outcomes.

LEVEL OF EVIDENCE

III, cohort study.

Primary reverse total shoulder arthroplasty for fractures requires more revisions than for degenerative conditions 1 year after surgery: an analysis from the Dutch Arthroplasty Register

BACKGROUND

Although reverse total shoulder arthroplasty (RTSA) is considered a viable treatment strategy for proximal humeral fractures, there is an ongoing discussion of how its revision rate compares with indications performed in the elective setting. First, this study evaluated whether RTSA for fractures conveyed a higher revision rate than RTSA for degenerative conditions (osteoarthritis, rotator cuff arthropathy, rotator cuff tear, or rheumatoid arthritis). Second, this study assessed whether there was a difference in patient-reported outcomes between these 2 groups following primary replacement. Finally, the results of conventional stem designs were compared with those of fracture-specific designs within the fracture group.

MATERIALS AND METHODS

This was a retrospective comparative cohort study with registry data from the Netherlands, generated prospectively between 2014 and 2020. Patients (aged ≥ 18 years) were included if they underwent primary RTSA for a fracture (<4 weeks after trauma), osteoarthritis, rotator cuff arthropathy, rotator cuff tear, or rheumatoid arthritis, with follow-up until first revision, death, or the end of the study period. The primary outcome was the revision rate. The secondary outcomes were the Oxford Shoulder Score, EuroQol 5 Dimensions (EQ-5D) score, numerical rating scale score (pain at rest and during activity), recommendation score, and scores assessing change in daily functioning and change in pain.

RESULTS

This study included 8753 patients in the degenerative condition group (mean age, 74.3 ± 7.2 years) and 2104 patients in the fracture group (mean age, 74.3 ± 7.8 years). RTSA performed for fractures showed an early steep decline in survivorship: Adjusted for time, age, sex, and arthroplasty brand, the revision risk after 1 year was significantly higher in these patients than in those with degenerative conditions (hazard ratio [HR], 2.50; 95% confidence interval, 1.66-3.77). Over time, the HR steadily decreased, with an HR of 0.98 at year 6. Apart from the recommendation score (which was slightly better within the fracture group), there were no clinically relevant differences in the patient-reported outcome measures after 12 months. Patients who received conventional stems (n = 1137) did not have a higher likelihood of undergoing a revision procedure than those who received fracture-specific stems (n = 675) (HR, 1.70; 95% confidence interval, 0.91-3.17).

CONCLUSION

Patients undergoing primary RTSA for fractures have a substantially higher likelihood of undergoing revision within the first year following the procedure than patients with degenerative conditions preoperatively. Although RTSA is regarded as a reliable and safe treatment option for fractures, surgeons should inform patients accordingly and incorporate this information in decision making when opting for head replacement surgery. There were no differences in patient-reported outcomes between the 2 groups and no differences in revision rates between conventional and fracture-specific stem designs.

A Review of the Role of Bioreactors for iPSCs-Based Tissue-Engineered Articular Cartilage

BACKGROUND

Osteoarthritis (OA) is the most common degenerative joint disease without an ultimate treatment. In a search for novel approaches, tissue engineering (TE) has shown great potential to be an effective way for hyaline cartilage regeneration and repair in advanced stages of OA. Recently, induced pluripotent stem cells (iPSCs) have been appointed to be essential stem cells for degenerative disease treatment because they allow a personalized medicine approach. For clinical translation, bioreactors in combination with iPSCs-engineerd cartilage could match patients needs, serve as platform for large-scale patient specific cartilage production, and be a tool for patient OA modelling and drug screening. Furthermore, to minimize in vivo experiments and improve cell differentiation and cartilage extracellular matrix (ECM) deposition, TE combines existing approaches with bioreactors.

METHODS

This review summarizes the current understanding of bioreactors and the necessary parameters when they are intended for cartilage TE, focusing on the potential use of iPSCs.

RESULTS

Bioreactors intended for cartilage TE must resemble the joint cavity niche. However, recreating human synovial joints is not trivial because the interactions between various stimuli are not entirely understood.

CONCLUSION

The use of mechanical and electrical stimulation to differentiate iPSCs, and maintain and test chondrocytes are key stimuli influencing hyaline cartilage homeostasis. Incorporating these stimuli to bioreactors can positively impact cartilage TE approaches and their possibility for posterior translation into the clinics.

Joint line obliquity after lateral closing-wedge high tibial osteotomy does not adversely affect clinical and radiological outcome: a 5-year follow-up study

PURPOSE

To analyze the association between change in knee joint line obliquity (KJLO) and patient-reported outcome, radiological progression of osteoarthritis, and surgical survival after lateral closing-wedge high tibial osteotomy (HTO).

METHODS

A cohort of 180 patients treated in one single hospital with lateral closing-wedge HTO was examined. KJLO was defined by the medial proximal tibial angle (MPTA). To assess the association between KJLO and patient-reported outcome, radiological progression of osteoarthritis, and surgical survival, patient groups were defined: I, postoperative MPTA < 95.0°; II, postoperative MPTA ≥ 95.0°; A, MPTA change < 8.0°; B, MPTA change ≥ 8.0°. Propensity score matching was used for between-groups (I and II, A and B) covariates matching, including age, gender, preoperative lower limb alignment, preoperative medial joint space width (mJSW), preoperative Western Ontario and McMaster Universities osteoarthritis Index (WOMAC) score, wedge size, and postoperative follow-up time. Patient-reported outcome was assessed by the WOMAC questionnaire, radiological progression of osteoarthritis by mJSW and Kellgren-Lawrence (KL) grade progression (≥ 1) preoperatively and at follow-ups (> 2 years). Failure was defined as revision HTO or conversion to knee arthroplasty.

RESULTS

After propensity score matching, groups I and II contained 58 pairs of patients and groups A and B contained 50 pairs. There were no significant differences in postoperative WOMAC score or surgical failure rate between groups I and II or between groups A and B (p > 0.05). However, the postoperative mJSW was significantly lower in group I than group II (3.2 ± 1.6 mm vs 3.9 ± 1.8 mm; p = 0.018) and in group A than group B (3.0 ± 1.7 mm vs 3.7 ± 1.5 mm; p = 0.040). KL grade progression rate was significantly higher in group I than group II (53.4% vs 29.3%; p = 0.008) and in group A than group B (56.0% vs 28.0%; p = 0.005).

CONCLUSION

Increased KJLO (postoperative MPTA ≥ 95.0°) or MPTA change ≥ 8.0° after lateral closing-wedge HTO does not adversely affect patient-reported outcome, radiological progression of osteoarthritis, or surgical survival at an average 5-year follow-up.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Clinical relevance of joint line obliquity after high tibial osteotomy for medial knee osteoarthritis remains controversial: a systematic review

PURPOSE

To systematically review the literature on the association between knee joint line obliquity (KJLO) and clinical outcome after high tibial osteotomy (HTO) for medial knee osteoarthritis and summarize the KJLO cut-off value used when studying this association.

METHODS

A systematic search was conducted in three databases (PubMed, Embase, and Web of Science) on September 2022, updated on February 2023. Eligible studies describing postoperative KJLO in relation to clinical outcome after HTO for medial knee osteoarthritis were included. Nonpatient studies and conference abstracts without full-text were excluded. Two independent reviewers assessed title, abstract and full-text based on the inclusion and exclusion criteria. The modified Downs and Black checklist was used to assess the methodological quality of each included study.

RESULTS

Of the seventeen studies included, three had good methodological quality, thirteen fair quality, and one had poor quality. Conflicting findings were shown on the associations between postoperative KJLO and patient-reported outcome, medial knee cartilage regeneration, and 10-year surgical survival in sixteen studies. Three good-quality studies found no significant differences in lateral knee cartilage degeneration between postoperative medial proximal tibial angle > 95° and < 95°. Joint line orientation angles by the tibial plateau of 4° and 6°, joint line orientation angle by the middle knee joint space of 5°, medial proximal tibial angles of 95° and 98°, and Mikulicz joint line angle of 94° were KJLO cut-off values used in the included studies.

CONCLUSION

Based on current evidence, the actual association between postoperative KJLO and clinical consequences after HTO for medial knee osteoarthritis cannot be ascertained. The clinical relevance of KJLO after HTO remains controversial.

LEVEL OF EVIDENCE

IV.

Quantum Sensing for Real-Time Monitoring of Drug Efficacy in Synovial Fluid from Arthritis Patients

Diamond-based T1 relaxometry is a new technique that allows nanoscale magnetic resonance measurements. Here we present its first application in patient samples. More specifically, we demonstrate that relaxometry can determine the free radical load in samples from arthritis patients. We found that we can clearly differentiate between osteoarthritis and rheumatoid arthritis patients in both the synovial fluid itself and cells derived from it. Furthermore, we tested how synovial fluid and its cells respond to piroxicam, a common nonsteroidal anti-inflammatory drug (NSAID). It is known that this drug leads to a reduction in reactive oxygen species production in fibroblast-like synoviocytes (FLS). Here, we investigated the formation of free radicals specifically. While FLS from osteoarthritis patients showed a drastic decrease in the free radical load, cells from rheumatoid arthritis retained a similar radical load after treatment. This offers a possible explanation for why piroxicam is more beneficial for patients with osteoarthritis than those with rheumatoid arthritis.

Responsiveness of the Indonesian Versions of the Anterior Cruciate Ligament-Return to Sport After Injury Score, the International Knee Documentation Committee Subjective Knee Form, and the Lysholm Score in Patients With ACL Injury

Background

The Indonesian versions of the Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI), International Knee Documentation Committee subjective knee form (IKDC), and the Lysholm scores are considered valid and reliable for Indonesian-speaking patients with anterior cruciate ligament (ACL) injury.

Purpose/Hypothesis

The purpose of this study was to determine the responsiveness of the ACL-RSI, IKDC, and Lysholm scores in an Indonesian-speaking population with ACL injury. It was hypothesized that they would have good responsiveness.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

Between March 1, 2021, and February 28, 2022, patients with an ACL injury at a single hospital in Indonesia were asked to complete the ACL-RSI, IKDC, and Lysholm scores before either reconstruction surgery or nonoperative treatment. At 6 months after treatment, the patients completed all 3 scores a second time, plus a global rating of change question. The distribution-based and the anchor-based methods were used to study responsiveness. For each scale, the standardized response mean, minimal clinically important difference (MCID), and minimal detectable change (MDC; at the group [MDCgr] and individual [MDCind] levels) for each scale were determined.

Results

Of 80 eligible patients, 75 (93.8%) completed the study. The standardized response means for the ACL-RSI, IKDC, and Lysholm scores were 1.59, 1.72, and 1.51, respectively, indicating good responsiveness. The MCIDs for the ACL-RSI, IKDC, and Lysholm scores were 6.8, 7.8, and 4.8, respectively; all MCIDs were larger than that of the MDCgr (1.1, 0.7, and 0.6, respectively). At the individual level, the MCID for the IKDC was larger than the MDCind (7.8 vs 5.8). However, the MCIDs for ACL-RSI and Lysholm scores were smaller than those of the MDCind (6.8 vs 10.9 and 4.8 vs 5.1, respectively).

Conclusion

The Indonesian ACL-RSI, IKDC, and Lysholm scores indicated good responsiveness and can be used in the follow-up of patients after ACL injury, especially at the group level. In individual patients, IKDC was found to be more efficient than the ACL-RSI or Lysholm scores for detecting clinically important changes over time after ACL treatment.

Assessment of joint line obliquity and its related frontal deformity using long-standing radiographs

Purpose

To investigate how radiographic techniques and osteoarthritis grade influence measurements of knee joint line obliquity (KJLO) and KJLO-related frontal deformity, and to propose preferable KJLO measurement methods.

Methods

Forty patients with symptomatic medial knee osteoarthritis indicated for high tibial osteotomy were assessed. Measurements were compared between single-leg and double-leg standing radiographs for KJLO measurement methods including joint line orientation angle by femoral condyles (JLOAF), joint line orientation angle by middle knee joint space (JLOAM), joint line orientation angle by tibial plateau (JLOAT), Mikulicz joint line angle (MJLA) and medial proximal tibial angle (MPTA), as well as KJLO-related frontal deformity parameters including joint line convergence angle (JLCA), knee ankle joint angle (KAJA) and hip-knee-ankle angle (HKA). Influences of bipedal distance in double-leg standing and osteoarthritis grade on the above measurements were analysed. Measurement reliability was evaluated by intraclass correlation coefficient.

Results

From single-leg to double-leg standing radiographs MPTA and KAJA did not change significantly, whereas the other measurements showed significant changes: JLOAF, JLOAM and JLOAT decreased 0.88°, 1.24° and 1.77°, MJLA and JLCA decreased 0.63° and 0.85°, and HKA increased 1.11° (p < 0.05). Bipedal distance in double-leg standing radiographs moderately correlated with JLOAF, JLOAM and JLOAT (r_p = -0.555, -0.574 and -0.549). Osteoarthritis grade moderately correlated with JLCA in single-leg and double-leg standing radiographs (r_s = 0.518 and 0.471). All measurements had at least good reliability.

Conclusion

In long-standing radiographs, measurements of JLOAF, JLOAM, JLOAT, MJLA, JLCA and HKA are all influenced by single-leg/double-leg standing; JLOAF, JLOAM and JLOAT are also affected by bipedal distance in double-leg standing; and JLCA is affected by osteoarthritis grade. Knee joint obliquity as assessed by MPTA measurement is independent of single-leg/double-leg standing, bipedal distance or osteoarthritis grade, and has excellent measurement reliability. We therefore propose MPTA as the preferable KJLO measurement method for clinical practice and future research.

Level of evidence

III, cross-sectional study.

Translation, Validity, and Reliability of the Indonesian Version of the Anterior Cruciate Ligament-Return to Sport After Injury Scale

Background

The Anterior Cruciate Ligament-Return to Sport After Injury (ACL-RSI) scale measures athletes' emotion, confidence, and risk appraisal when returning to sports after an anterior cruciate ligament (ACL) injury and/or ACL reconstruction (ACLR).

Purpose

To translate the ACL-RSI into the Indonesian language and to assess its validity and reliability in Indonesian-speaking patients after ACLR.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

After a forward-and-backward translation procedure, the validity and reliability of the Indonesian version of the ACL-RSI (I-ACL-RSI) were investigated. Patients who had undergone ACLR at a single hospital were asked to complete 4 questionnaires: I-ACL-RSI, Injury-Psychological Readiness to Return to Sport, Tampa Scale of Kinesiophobia, and International Knee Documentation Committee. After a 2-week interval, patients were asked to complete the I-ACL-RSI a second time. Following the COSMIN reporting guidelines (Consensus-Based Standards for the Selection of Health Measurement Instruments), we determined construct validity using hypothesis testing, as well as test-retest reliability, internal consistency, floor and ceiling effects, and measurement error.

Results

Of 200 eligible patients, 102 (51%) were included in the analysis. All predefined hypotheses on correlations between the I-ACL-RSI and the other questionnaires were confirmed, indicating good construct validity. An intraclass correlation coefficient of 0.90 (2-way random, type agreement) was found for the first and second I-ACL-RSI scores, indicating good test-retest reliability. A Cronbach α of 0.95 indicated good internal consistency, and no floor or ceiling effects were found. The standard error of measurement was 3.9, with the minimal detectable change calculated as 10.9 points at the individual level and 1.1 points at the group level.

Conclusion

Based on the study findings, the I-ACL-RSI can be considered a valid and reliable questionnaire for Indonesian-speaking patients after ACL injury and/or ACLR.

[Milwaukee shoulder syndrome: A painful swollen shoulder as a result of a rare condition]

BACKGROUND

A painful and swollen shoulder has an extensive differential diagnosis, with Milwaukee shoulder syndrome (MSS) being diagnosed infrequently. Analysis of crystals in the synovial fluid is an important diagnostic step in patients with a swollen shoulder.

CASE DESCRIPTION

A 69-year-old female presented at the orthopaedic outpatient clinic with pain, limited mobility and swelling of the left shoulder. The diagnosis MSS was made based on the characteristic features on X-ray and MRI combined with the analysis of the synovial fluid, including a positive alizarin-red staining.

CONCLUSION

MSS is a rare, destructive, calcium-hydroxyapatite crystal-associated arthropathy. After a typical X-ray, a joint aspiration is preferred to avoid unnecessary expensive radiographic imaging. Alizarin-red staining is a simple, inexpensive, and sensitive test to identify calcium-hydroxyapatite crystals in synovial fluid, and aids in the diagnosis of MSS. This is important in order to adequately inform patients regarding the prognosis of their disease.

Burden and Cost of Anterior Cruciate Ligament Reconstruction and Reimbursement of Its Treatment in a Developing Country: An Observational Study in Indonesia

Objective

The number of anterior cruciate ligament reconstruction (ACLR) procedures is increasing. However, ACLR procedures are likely to be underbudgeted in a developing country like Indonesia. This study aimed to analyze costs for ACLR procedures in Indonesia's resource-limited context, determine the burden of ACLR, and suggest national prices for ACLR reimbursement.

Methods

A retrospective observational study was conducted between 1 January and 31 December 2019 on the cost of ACLR from a payer perspective using inpatient billing records in four hospitals. The national burden of ACLR was calculated, and projected national prices for reimbursement were determined.

Results

Of 80 ACLRs, 53 (66%) were isolated ACLRs and 27 (34%) ACLRs were combined with meniscus treatment. Mean hospital costs incurred per ACLR procedure were US$ 2853, with the dominant cost relating to orthopedic implant prices (US$ 1,387.80). The costs of ACLR with combined meniscus treatment were estimated as being 35% higher than isolated ACLR. The national burden of ACLR showed a total budget of US$ 367.4 million per 100,000 patients (0.03% of GDP) for ACLR with additional meniscus treatment and US$ 271.3 million per 100,000 patients (0.02% of GDP) for isolated ACLR.

Conclusion

ACLR procedures in Indonesia are likely underbudgeted. Adjustments of reimbursement prices for ACLR are needed to facilitate adequate access of Indonesians to the procedures. This study demonstrated varying costs determined for ACLR in Indonesia, which entails that a new reimbursement system with improvement of national prices should become the core of transformation.

Translation and Psychometric Analysis of the Indonesian Versions of the Lysholm and Tegner Scores for Patients With Anterior Cruciate Ligament Injuries

Background:

The Lysholm knee score and Tegner activity scale are frequently used patient-reported outcome measures in patients with anterior cruciate ligament (ACL) injuries because of their excellent psychometric properties. These questionnaires were originally developed in the English language.

Purpose:

To translate and cross-culturally adapt these measures into the Indonesian language and study their validity and reliability so that they can be used in the Indonesian-speaking population with ACL injuries.

Study Design:

Cohort study (diagnosis/symptom prevalence); Level of evidence, 2.

Methods:

After a forward-backward translation procedure and cross-cultural adaptation, validity and reliability were investigated. A total of 253 patients with an ACL injury were sent 4 questionnaires (36-Item Short Form Health Survey, Kujala anterior knee pain scale, Indonesian Lysholm knee score [I-LK], and Indonesian Tegner activity scale [I-TS]). The responses of those patients were analyzed. Following COSMIN guidelines, construct validity, test-retest reliability, internal consistency, floor and ceiling effects, and measurement errors were determined. The Bland-Altman method was used to explore absolute agreement.

Results:

A total of 106 patients (42% response rate) were included in this study. Construct validity was considered to be good, as more than 75% of the predefined hypotheses on correlations between the I-LK, I-TS, and other measures were confirmed. Reliability proved excellent, with a high test-retest correlation for both questionnaires (intraclass correlation coefficient = 0.99). Bland-Altman analysis showed no systematic bias between testing and retesting. The internal consistency of the I-LK was good (Cronbach alpha = 0.73). For the I-LK and I-TS, floor and ceiling effects were less than 15% (floor: 0% and 4.7%, respectively; ceiling: 12.3% and 3.8%, respectively); the standard error of measurement was 1.8 and 0.9, respectively; the minimal detectable change at the individual level was 5.1 and 0.6, respectively; and the minimal detectable change at the group level was 2.4 and 0.5, respectively.

Conclusion:

Both the I-LK and I-TS appear to be good evaluation tools for Indonesian-speaking patients with an ACL injury.

Translation, Cross-Cultural Adaptation, Validity, and Reliability of the Indonesian Version of the IKDC Subjective Knee Form

Background:

No questionnaire is currently available for use in patients with anterior cruciate ligament (ACL) injuries in an Indonesian population. The most-used questionnaire in clinical research for these patients is the International Knee Documentation Committee (IKDC) Subjective Knee Form, as its psychometric properties are considered to be excellent.

Purpose:

To translate the IKDC into Indonesian and assess its validity for use in Indonesian-speaking patients with ACL injuries.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

After a forward-and-backward translation procedure and cross-cultural adaptation, the validity and reliability of the questionnaire were investigated. The responses of ACL injury patients on 3 questionnaires, the Indonesian-IKDC (I-IKDC), 36-Item Short Form Health Survey, and Kujala Anterior Knee Pain Scale, were compared. Following consensus-based standards for the selection of health measurement instruments guidelines, construct validity, test-retest reliability, internal consistency, floor and ceiling effects, and measurement error were determined. The Bland-Altman method was used to explore absolute agreement.

Results:

Of 253 ACL injury patients, 106 (42%) responded to the invitation. Construct validity was considered good, as all predefined hypotheses on correlations between the I-IKDC and other scores were confirmed. Reliability proved excellent, with a high test-retest correlation (intraclass correlation coefficient = 0.99). Bland-Altman analyses showed no systematic bias between test and retest. Internal consistency was good (Cronbach α = .90). There were no floor or ceiling effects. Standard error of measurement was 2.1, and the minimal detectable change was 5.8 at the individual level and 0.7 at the group level.

Conclusion:

The I-IKDC, as developed, appeared to be a good evaluation instrument for Indonesian patients with ACL injuries.

Pseudotumours, cobalt and clinical outcome in small head metal-on-metal versus conventional metal-on-polyethylene total hip arthroplasty

BACKGROUND

Metal-on-metal total hip arthroplasty (MoM THA) is associated with the formation of pseudotumours. Studies mainly concern pseudotumour formation in large head MoM THA. We performed a long-term follow-up study, comparing pseudotumour incidence in small head metal-on-metal (SHMoM) THA with conventional metal-on-polyethylene (MoP) THA. Predisposing factors to pseudotumour formation were assessed.

METHODS

From a previous randomised controlled trial comparing SHMoM (28 mm) cemented THA with conventional MoP cemented THA, patients were screened using a standardised CT protocol for the presence of pseudotumours. Serum cobalt levels and functional outcome were assessed.

RESULTS

56 patients (33 MoP and 23 MoM) were recruited after mean follow-up of 13.4 years (SD 0.5). The incidence of pseudotumours was 1 (5%) in the SHMoM THA cohort and 3 (9%) in the MoP THA cohort. Prosthesis survival was 96% for both SHMoM and MoP THAs. Serum cobalt levels did not exceed acceptable clinical values (<5 µg/L) whereas no differences in cobalt levels were detected at follow-up between both groups. Oxford and Harris Hip Scores were good and did not differ between SHMoM and MoP THA.

CONCLUSIONS

This long-term follow-up study shows a low incidence of pseudotumour formation and good functional outcome in cemented head-taper matched SHMoM and MoP THA.

Effects of vitamin E incorporation in polyethylene on oxidative degradation, wear rates, immune response, and infections in total joint arthroplasty: a review of the current literature

Highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) was introduced to decrease wear debris and osteolysis. During cross-linking, free radicals are formed, making highly cross-linked polyethylene vulnerable to oxidative degradation. In order to reduce this process, anti-oxidant vitamin E can be incorporated in polyethylene. This review provides an overview of the effects of vitamin E incorporation on major complications in total joint arthroplasty: material failure due to oxidative degradation, wear debris and subsequent periprosthetic osteolysis, and prosthetic joint infections. Secondly, this review summarizes the first clinical results of total hip and knee arthroplasties with vitamin E incorporated highly cross-linked polyethylene. Based on in vitro studies, incorporation of vitamin E in polyethylene provides good oxidative protection and preserves low wear rates. Incorporation of vitamin E may have the beneficial effect of reduced inflammatory response to its wear particles. Some microorganisms showed reduced adherence to vitamin E-incorporated UHMWPE; however, clinical relevance is doubtful. Short-term clinical studies of total hip and knee arthroplasties with vitamin E-incorporated highly cross-linked UHMWPE reported good clinical results and wear rates similar to highly cross-linked UHMWPE without vitamin E.

Clinical outcome, survival and polyethylene wear of an uncemented total hip arthroplasty: a 10- to 12-year follow-up study of 81 hips

A complete 10- to 12-year follow-up of an uncemented total hip arthroplasty (THA) was performed regarding survival, clinical outcome, polyethylene wear and influencing factors on wear. Seventy-two patients (75 Mallory Head uncemented THA) with primary osteoarthritis operated on in 1999 or 2000 were included in the survival study. Mean age at the time of operation was 57.9 years (range 37-70). The survival rate after 11.9 years was 96% (95% CI 0.89-1.01). In three cases the acetabular component was revised because of extensive polyethylene wear. Fifty-four patients with 57 THAs were available for clinical and radiological analysis. At a mean follow-up time of 10.7 years (range 10-12) the clinical outcome can be considered comparable to other uncemented THA. Mean polyethylene wear was 1.8mm (range 0.4-3.8) with an annual wear rate of 0.15 mm/y. There was a significant correlation between polyethylene wear and inclination of the cup as well as male gender.

Wear, bone density, functional outcome and survival in vitamin E-incorporated polyethylene cups in reversed hybrid total hip arthroplasty: design of a randomized controlled trial

Background

Aseptic loosening of total hip arthroplasties is generally caused by periprosthetic bone resorption due to tissue reactions on polyethylene wear particles. In vitro testing of polyethylene cups incorporated with vitamin E shows increased wear resistance. The objective of this study is to compare vitamin E-stabilized highly cross-linked polyethylene with conventional cross-linked polyethylene in “reversed hybrid” total hip arthroplasties (cemented all-polyethylene cups combined with uncemented femoral stems). We hypothesize that the adjunction of vitamin E leads to a decrease in polyethylene wear in the long-term. We also expect changes in bone mineral density, less osteolysis, equal functional scores and increased implant survival in polyethylene cemented cups incorporated with vitamin E in the long-term.

Design

A double-blinded randomized controlled trial will be conducted. Patients to be included are aged under 70, suffer from non-inflammatory degenerative joint disease of the hip and are scheduled for a primary total hip arthroplasty. The study group will receive a reversed hybrid total hip arthroplasty with a vitamin E-stabilized highly cross-linked polyethylene cemented cup. The control group will receive a reversed hybrid total hip arthroplasty with a conventional cross-linked polyethylene cemented cup. Radiological follow-up will be assessed at 6 weeks and at 1, 3, 5, 7 and 10 years postoperatively, to determine polyethylene wear and osteolysis. Patient-reported functional status (HOOS), physician-reported functional status (Harris Hip Score) and patients’ physical activity behavior (SQUASH) will also be assessed at these intervals. Acetabular bone mineral density will be assessed by dual energy X-ray absorptiometry (DEXA) at 6 weeks and at 1 year and 2 years postoperatively. Implant survival will be determined at 10 years postoperatively.

Discussion

In vitro results of vitamin E-stabilized polyethylene are promising, showing increased wear resistance. However, controlled clinical follow-up data are not available at this moment.

This randomized controlled trial has been designed to determine wear, bone mineral density, functional outcome and survival in reversed hybrid total hip arthroplasty comparing cemented vitamin E-stabilized highly cross-linked polyethylene cups with cemented conventional cross-linked polyethylene cups.

Trial registration

Dutch Trial Registry NTR3049

Long-term follow-up of anatomic graduated component total knee arthroplasty: a 15- to 20-year survival analysis

The aims of this study were to determine survival rate, the clinical performance, and radiologic results of an Anatomic Graduated Component (AGC) total knee arthroplasty (TKA). Survival analysis was assessed by analyzing all hospital records of 211 AGC TKAs in 177 patients after 15 to 20 years. The survival rate was 87%, with failure defined as revision for any reason including infection. The main reasons for failure were infection and failure of the metal-backed patellar component. Clinical evaluation of 30 patients (33 TKAs) and questionnaires of 20 patients (23 TKAs) were taken, showing moderate to good results (mean Knee Society Score, 51; mean Western Ontario and McMaster Universities Osteoarthritis index, 82; mean University of California Los Angeles score, 4). Radiologic evaluation of 13 TKAs in 12 patients showed that none was suspect for loosening. Three knees showed significant medial wear but no clinical complaints. In conclusion, this is one of the first studies showing that AGC total knee prosthesis has good results 15 to 20 years after surgery.